Throttle body and method of manufacturing the same

Abstract

A throttle body includes a resin body (3) defining a bore (7) through which intake air flows, and a valve body (60) having a shaft part (20) rotatably supported by the body (3) via a pair of bearing members (24) and a resin valve part (4) for opening and closing the bore (7). End faces (67) of the valve part (4) slidably contacting with end faces (69) of the bearing members (24). The end faces (67) and (69) of at least one of the valve part (4) and the bearing members (24) slidably contacting with each other are formed to have a radius (69r) equal to or larger than a radius (68r) of paths of rotation (68) of radially outer ends (67a) of the end faces (67) of the valve part (4).

Description

TECHNICAL FIELD

The present invention relates to a throttle body for controlling an intake air amount of an internal combustion engine and a method of manufacturing the same.

BACKGROUND ART

A conventional throttle body is equipped with a resin main body forming a bore through which intake air flows, a metal shaft part rotatably supported by the main body through the intermediation of a pair of metal bearing members, and a valve body having a resin valve part for opening and closing the bore. The main body is molded with the valve body inserted together with the pair of bearing members. In ordinary throttle bodies, a moving amount of the valve body in a thrust direction (axial direction) is regulated through sliding contact of end faces of the valve part with end faces of the bearing members. Patent Document 1 discloses a throttle body manufacturing method in which the main body is molded with the valve body inserted.

Patent Document 1: JP 2001-212846 A

DISCLOSURE OF THE INVENTION

Problem to be Solved by the Invention

In the above-mentioned conventional throttle body, the end faces of the bearing members are formed in a radius smaller than a radius of the paths of rotation of the radially outer ends of the end faces of the valve part. As a result, the radially outer ends of the end faces of the valve part extrude beyond the end faces of the bearing members. Thus, as a result of rotation caused by the opening/closing of the valve part, the radially outer ends of the valve part come into sliding contact with an inner wall surface or so-called bore wall surface of the main body opposed thereto. Thus, resin-to-resin sliding contact occurs between the valve part and the main body, and therefore, there has been a possibility that the wear of the resin increases, and an operation property of the valve body is impaired.

It is an object of the present invention to provide a throttle body and a method of manufacturing the same which can improve the operation property of the valve body.

Means for Solving the Problem

The above-mentioned object can be achieved by a throttle body and a method of manufacturing the same, the gist of which are defined in the claims.

That is, a first aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members, wherein:

the end faces of at least one of the valve part and the bearing members slidably contacting with each other are formed as end faces of a good sliding property, and

the end faces of the bearing members slidably contacting with the end faces of the bearing members are formed to have a radius equal to or larger than a radius of paths of rotation of radially outer ends of the end faces of the valve part.

According to the first aspect of the invention, constructed as described above, the bore of the main body is opened and closed by the valve part rotating with the shaft part of the valve body, so that an amount of intake air flowing through the bore, that is, an intake air amount, is controlled.

Further, a moving amount of the valve body in a thrust direction is regulated through sliding contact of the end faces of the valve part with the end faces of the bearing members.

The end faces of at least one of the valve part and the bearing members slidably contacting with each other are formed as end faces of a good sliding property, so that it is possible to reduce the frictional resistance of the end faces of the valve part with respect to the end faces of the bearing members.

Further, the end faces of the bearing members are formed to have a radius equal to or larger than the radius of the paths of rotation of the radially outer ends of the end faces of the valve part, so that the entire end faces of the valve part can slidably contact with the end faces of the bearing members, and it is possible to avoid sliding contact of the valve part with the bore wall surface of the main body.

Thus, due to a synergistic effect of reduction in the frictional resistance of the end faces of the valve part with respect to the end faces of the bearing members and avoidance of sliding contact of the valve part with the bore wall surface of the main body, it is possible to improve an operation property of the valve body.

A second aspect of the invention is a throttle body according to the first aspect of the invention, in which the bearing members are made of a material having a good sliding property.

According to the second aspect of the invention, constructed as described above, the bearing members are made of the material having a good sliding property, so that it is possible to reduce frictional resistance between the end faces of the valve part and the end faces of the bearing members.

A third aspect of the invention is a throttle body according to the first aspect of the invention, in which slide layers having a good sliding property are provided on the end faces of the valve part, which slidably contact with the end faces of the bearing members.

According to the third aspect of the invention, constructed as described above, the slide layers having a good sliding property are provided on the end faces of the bearing members, which slidably contact with the end faces of the valve part, so that it is possible to reduce the frictional resistance between the end faces of the valve part and the end faces of the bearing members.

A fourth aspect of the invention is a throttle body according to any one of the first to third aspects of the inventions, in which the slide layers having a good sliding property are provided on the end faces of the valve part, which slidably contact with the end faces of the bearing members.

According to the fourth aspect of the invention, constructed as described above, the slide layers having a good sliding property are provided on the end faces of the valve part, so that it is possible to reduce the frictional resistance between the end faces of the valve part and the end faces of the bearing members.

A fifth aspect of the invention is a throttle body according to any one of the first to fourth aspects of the inventions, in which slide layers having a good sliding property are provided on outer peripheral surfaces of support shaft portions of the shaft part, which are rotatably supported by the bearing members.

According to the fifth aspect of the invention, constructed as described above, the slide layers having a good sliding property are provided on the outer peripheral surfaces of the support shaft portions of the shaft part, so that it is possible to reduce frictional resistance between inner peripheral surfaces of shaft holes of the bearing members and the outer peripheral surfaces of the support shaft portions of the shaft part.

A sixth aspect of the invention relates to a throttle body according to any one of the first to fifth aspects of the inventions, in which slide layers having a good sliding property are provided on inner peripheral surfaces of shaft holes of the bearing members, which are rotatably supporting the shaft part.

According to the sixth aspect of the invention, constructed as described above, the slide layers having a good sliding property are provided on the inner peripheral surfaces of the shaft holes of the bearing members, so that it is possible to reduce the frictional resistance between the inner peripheral surfaces of the shaft holes of the bearing members and the outer peripheral surfaces of the support shaft portions of the shaft part.

A seventh aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members, wherein:

the bearing members are made of metal,

the shaft part is made of resin, and

slide layers having a good sliding property are provided on outer peripheral surfaces of support shaft portions of the shaft part rotatably supported by the bearing members.

According to the seventh aspect of the invention, constructed as described above, the bore of the main body is opened and closed by the valve part rotating with the shaft part of the valve body, so that the amount of intake air flowing through the bore, that is, the intake air amount, is controlled.

Further, the moving amount of the valve body in the thrust direction is regulated through sliding contact of the end faces of the valve part with the end faces of the bearing members.

Here, the bearing members are made of metal, the shaft part is made of resin, and the slide layers having a good sliding property are provided on the outer peripheral surfaces of the support shaft portions of the shaft part. Therefore, it is possible to reduce the frictional resistance of the support shaft portions of the resin shaft part with respect to the metal bearing members. Further, by making the shaft part of resin, it is possible to abolish the shaft part made of metal, so that it is possible to achieve a reduction in cost and weight. Further, in this case, by molding the shaft part integrally with the valve body, it is possible to achieve a further reduction in cost.

An eighth aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing member, wherein:

the bearing members are made of metal,

the shaft part is made of resin, and

slide layers having a good sliding property are provided on the end faces of the valve part, which slidably contact with the end faces of the bearing members.

According to the eighth aspect of the invention, constructed as described above, the bore of the main body is opened and closed by the valve part rotating with the shaft part of the valve body, so that the amount of intake air flowing through the bore, that is, the intake air amount, is controlled.

Further, the moving amount of the valve body in the thrust direction is regulated through sliding contact of the end faces of the valve part with the end faces of the bearing members.

Here, the bearing members are made of resin, the shaft part is made of metal, and the slide layers having a good sliding property are provided on the end faces of the valve part, which slidably contact with the end faces of the bearing members. Therefore, it is possible to reduce the frictional resistance of the end faces of the valve part made of resin with respect to the end faces of the bearing members made of resin. Further, by making the bearing members of resin, it is possible to achieve a reduction in cost and weight. Further, in this case, by molding the bearing members integrally with the main body, it is possible to achieve a further reduction in cost.

A ninth aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing member, wherein:

the bearing members are made of metal,

the shaft part is made of resin, and

slide layers having a good sliding property are provided on the end faces of the bearing members, which slidably contact with the end faces of the valve part.

According to the ninth aspect of the invention, constructed as described above the bore of the main body is opened and closed by the valve part rotating with the shaft part of the valve body, so that the amount of intake air flowing through the bore, that is, the intake air amount, is controlled.

Further, the moving amount of the valve body in the thrust direction is regulated through sliding contact of the end faces of the valve part with the end faces of the bearing members.

Here, the bearing members are made of resin, the shaft part is made of metal, and the slide layers having a good sliding property are provided on the end faces of the bearing members, which slidably contact with the end faces of the valve part. Therefore, it is possible to reduce the frictional resistance of the end faces of the valve part made of resin with respect to the end faces of the bearing members made of resin. Further, by making the bearing members of resin, it is possible to achieve a reduction in cost and weight. Further, in this case, by molding the bearing members integrally with the main body, it is possible to achieve a further reduction in cost.

A tenth aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members, wherein:

the bearing members and the shaft part are made of resin, and

slide layers having a good sliding property are provided on the end faces of the valve part, which slidably contact with the end faces of the bearing members, and on outer peripheral surfaces of support shaft portions of the shaft part, which are rotatably supported by the bearing members.

According to the tenth aspect of the invention, constructed as described above, the bore of the main body is opened and closed by the valve part rotating with the shaft part of the valve body, so that the amount of intake air flowing through the bore, that is, the intake air amount, is controlled.

Further, the moving amount of the valve body in the thrust direction is regulated through sliding contact of the end faces of the valve part with the end faces of the bearing members.

Here, the bearing members and the shaft part are made of resin, and slide layers having a good sliding property are provided on the end faces of the valve part, which slidably contact with the end faces of the bearing members, and on the outer peripheral surfaces of the support shaft portions of the shaft part, which are rotatably supported by the bearing members. Therefore, it is possible to reduce the frictional resistance of the end faces of the valve part made of resin with respect to the end faces of the bearing members, which are made of resin, and the frictional resistance of the support shaft portions of the resin shaft part with respect to the bearing members. Further, by making the bearing. members and the shaft part of resin, it is possible to achieve a reduction in cost and weight. Further, in this case, by molding the bearing members integrally with the main body, it is possible to achieve a further reduction in cost. Further, by molding the shaft part integrally with the valve body, it is possible to achieve a further reduction in cost

An eleventh aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members, wherein:

the bearing members are made of resin,

the shaft part is made of metal, and

slide layers having a good sliding property are provided on the end faces of the bearing members, which slidably contact with the end faces of the valve part, and on inner peripheral surfaces of shaft holes of the bearing members, which rotatably support the shaft part.

According to the eleventh aspect of the invention, constructed as described above, the bore of the main body is opened and closed by the valve part rotating with the shaft part of the valve body, so that the amount of intake air flowing through the bore, that is, the intake air amount, is controlled.

Further, the moving amount of the valve body in the thrust direction is regulated through sliding. contact of the end faces of the valve part with the end faces of the bearing members.

Here, the bearing members are made of resin, the shaft part is made of metal, and the slide layers having a good sliding property are provided on the end faces of the bearing members, which slidably contact with the end faces of the valve part, and on the inner peripheral surfaces of the shaft holes of the bearing members, which rotatably support the shaft part. Therefore, it is possible to reduce the frictional resistance of the end faces of the valve part formed of a resin with respect to the end faces of the bearing members formed of a resin and the frictional resistance of the support shaft portions of the resin shaft part with respect to the bearing members. Further, by making the bearing members of resin, it is possible to achieve a reduction in cost and weight. Further, in this case, by molding the bearing members integrally with the main body, it is possible to achieve a further reduction in cost.

A twelfth aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members,

wherein clearances between the end faces of the valve part and the end faces of the bearing members are adjusted through axial movement of the bearing members.

According to the twelfth aspect of the invention, constructed as described above, the bore of the main body is opened and closed by the valve part rotating with the shaft part of the valve body, so that the amount of intake air flowing through the bore, that is, the intake air amount, is controlled.

Further, the moving amount of the valve body in the thrust direction is regulated through sliding contact of the end faces of the valve part with the end faces of the bearing members.

By moving the bearing members in the axial direction, the clearances between the end faces of the valve part and the end faces of the bearing members are adjusted to a predetermined amount. Thus, it is possible to improve the operation property of the valve body. It is desirable that the clearances between the end faces of the valve part and the end faces of the bearing members are those making it possible to reduce a leakage amount of intake air (hereinafter referred to as “air leakage amount”) when the valve body is fully closed, while improving the operation property of the valve body.

A thirteenth aspect of the invention is a throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contact with end faces of the bearing members,

wherein, between the end faces of the valve part and the end faces of the bearing members, spacer means for setting clearances between the end faces to a predetermined. amount are provided.

According to the thirteenth aspect of the invention, constructed as described above, the bore of the main body is opened and closed by the valve part rotating with the shaft part of the valve body, so that the amount of intake air flowing through the bore, that is, the intake air amount, is controlled.

Further, the moving amount of the valve body in the thrust direction is regulated through sliding contact of the end faces of the valve part with the end faces of the bearing members.

By virtue of the spacer means provided between the end faces of the valve part and the end faces of the bearing members, it is possible to set the clearances between the end faces to a predetermined amount. Thus, it is possible to improve the operation property of the valve body. It is desirable that the clearances between the end faces of the valve part and the end faces of the bearing members are those making it possible to reduce the air leakage amount when the valve body is fully closed, while improving the operation property of the valve body. The spacer means may be of any type as long as they are capable of setting the clearances between the end faces of the valve part and the end faces of the bearing members to a predetermined amount; they may be removed after the setting of the clearances between the end faces, or may not be removed if they undergo resilient deformation after the setting of the clearances between the end faces.

A fourteenth aspect of the invention is a method of manufacturing a throttle body, the throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members,

the method of manufacturing the throttle body including adjusting clearances between the end faces of the valve part and the end faces of the bearing members through axial movement of the bearing members after molding the main body.

According to the fourteenth aspect of the invention, constructed as described above, it is possible to manufacture a throttle body that can provide the same effects as those of the twelfth aspect of the invention.

A fifteenth aspect of the invention is a method of manufacturing a throttle body, the throttle body including:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members,

the method of manufacturing the throttle body including setting clearances between the end faces of the valve part and the end faces of the bearing members to a predetermined amount by spacer means when one of the valve part and the main body is molded, with the other of them inserted together with the bearing members.

According to the fifteenth aspect of the invention, constructed as described above, it is possible to manufacture a throttle body that can provide the same effects as those of the thirteenth aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A front view of a throttle body according to Embodiment 1.

FIG. 2 A bottom view of the throttle body.

FIG. 3 A sectional view taken along the arrow line III-III in FIG. 2.

FIG. 4 A sectional view taken along the arrow line IV-IV in FIG. 1.

FIG. 5 A left side view of a main body with a cover body removed therefrom.

FIG. 6 An enlarged view of a portion VI in FIG. 3.

FIG. 7 An explanatory view illustrating a relationship between a valve part and bearing sleeves.

FIG. 8 A sectional view of a primary portion of Embodiment 2.

FIG. 9 A sectional view of a primary portion of Embodiment 3.

FIG. 10 A front sectional view of a throttle body according to Embodiment 4.

FIG. 11 A sectional view of a primary portion at a time of molding a main body.

FIG. 12 An end view of a portion around a bearing sleeve at the time of molding the main body.

FIG. 13 A sectional view of a primary portion after movement for adjustment of the bearing sleeve.

FIG. 14 A sectional view of the portion around the bearing sleeve after the movement for adjustment of the bearing sleeve.

FIG. 15 A sectional view of a body molding die.

FIG. 16 A perspective view of a bearing-sleeve pivotal die.

FIG. 17 A sectional view of a primary portion of Embodiment 5.

FIG. 18 A perspective view of a spacer member.

FIG. 19 A sectional view of a primary portion of Modification 1.

FIG. 20 A perspective view of a gage member.

FIG. 21 A sectional view of a primary portion of Modification 2.

FIG. 22 A side view of a valve body.

FIG. 23 A sectional view of a primary portion of Modification 3.

FIG. 24 A sectional view of a primary portion after removal of a projecting portion.

FIG. 25 A sectional view of a primary portion of Modification 4.

BEST MODES FOR CARRYING OUT THE INVENTION

Next, best modes for carrying out the invention will be described with reference to embodiments.

Embodiment 1

Embodiment 1 will be described. This embodiment will be described in relation to a so-called electronic control type throttle body in which a valve body is opening/closing-controlled by a motor. FIG. 1 is a front view of a throttle body, FIG. 2 is a bottom view of the throttle body, FIG. 3 is a sectional view taken along the arrow line III-III in FIG. 2, FIG. 4 is a sectional view taken along the arrow line IV-IV in FIG. 1, FIG. 5 is a left side view of a main body with a cover body removed therefrom, FIG. 6 is an enlarged view of a portion VI in FIG. 3, and FIG. 7 is an explanatory view illustrating the relationship between a valve member and a bearing sleeve.

As shown in FIG. 4, a throttle body 2 is provided with a resin main body 3 and a resin valve member 4 (see FIGS. 1 and 3). The main body 3 and the valve member 4 are both formed by injection molding processes.

With the main body 3, a bore wall portion 5 and a motor housing portion 6 are integrally molded (see FIGS. 3 and 4).

The bore wall portion 5 is formed substantially as a hollow cylinder having a bore 7 extending in the right and left directions as seen in FIG. 4. The bore wall portion 5 has a straight cylindrical inlet-side tubular connecting portion 8 extending continuously from the right to the left in FIG. 5, a conical tubular portion 9 formed as a conical tube whose diameter is gradually decreased, a primary tubular portion 10 formed as a straight cylinder, an inverted conical tubular portion 11 formed as an inverted conical tube whose diameter gradually increases, and an outlet-side tubular connecting portion 12 formed as a straight cylinder. The inner wall surface of the bore 7 of the bore wall portion 5 composed of the tubular portions 8, 9, 10, 11, and 12 will be generally referred to as “bore wall surface” (labeled with numeral 13).

As shown in FIG. 7, on the inner peripheral surface of the primary tubular portion 10, an annular-strip-like sealing surface 16 is formed and is surface-to-surface contact with a sealing surface 15 at the outer peripheral end surface of the valve member 4 (hereinafter described). The sealing surfaces 15 of the valve member 4 will be referred to as “valve-side sealing surfaces”, and the sealing surface 16 of the main body 3 will be referred to as “body-side sealing surface”.

As shown in FIG. 2, a flange portion 18 for fastening protrudes substantially in a rectangular-plate-like fashion and is connected with the outer peripheral surface of the opening end portion on the side of the outlet-side tubular connecting portion of the bore wall portion 5. Metal bushes 19 are provided at four corners of the flange portion 18 for fastening (see FIG. 1). Fastening bolts (not shown) for fastening an intake manifold, which is arranged on the downstream side of the main body 3, to the flange portion 18 for fastening can be passed through the bushes 19.

An air cleaner (not shown) arranged on the upstream side of the main body 3 is fitted into the inlet-side tubular connecting portion 8 of the bore wall portion 5 for communication therewith. The intake manifold (not shown), which is arranged on the downstream side of the main body 3, is fastened to the flange portion 18 for fastening by fastening bolts/nuts for communication with the outlet-side tubular connecting portion 12 of the bore wall portion 5. In this way, communication is established between the bore wall portion 5 of the main body 3, the air cleaner, and the intake manifold, so that intake air from the air cleaner flows to the intake manifold through the bore 7 in the bore wall portion 5.

As shown in FIG. 3, a metal throttle shaft 20 is disposed in the bore wall portion 5 and extends radially across the bore 7 (in right and left directions in FIG. 3). Right and left support shaft portions 21 formed at both ends of the throttle shaft 20 are rotatably supported by a pair of right and left bearing sleeves 24 inserted into a pair of right and left bearing boss portions 22. formed integrally with the bore wall portion 5. The shaft support portions 21 are formed to have a large outer diameter than that of a shaft body 20a of the throttle shaft 20. The bearing sleeves 24 are formed of a pair of metal bushes arranged symmetrically on the right and left sides. The outer peripheral portions of the bearing sleeves 24 are respectively surrounded by the bearing boss portions 22 and are placed in position with respect to the axial direction. The bearing sleeves 24 will be described later in more detail

In FIG. 3, the right end portion of the throttle shaft 20 is accommodated in the right-side bearing boss portion 22. A plug 26 is mounted to the right-side bearing portion 22 by press-fitting or like means for sealing the opening end surface thereof.

The left end portion of the throttle shaft 20 extends through the left-side bearing boss portion 22 and protrudes to the left. A rubber sealing material 27 is fitted into the left-side bearing boss portion 22 from the opening side thereof (left side in FIG. 3). The inner peripheral portion of the sealing material 27 is slidably fitted into a circumferential annular groove (not labeled with reference numeral) formed in the outer peripheral surface of the throttle shaft 20. Due to the sealing material 27, air leakage from a gear housing space 29 (described below) into the bore 7, and air leakage from the bore 7 into the gear housing space 29 are prevented.

As shown in FIG. 4, the substantially disc-like valve member 4 is formed integrally with the throttle shaft 20 by an insert molding process. The valve member 4 rotates together with the throttle shaft 20 to open/close the bore 7 in the bore wall portion 5 in order to control the amount of intake air flowing through the bore 7. The solid line 4 in FIG. 4 indicates the closed state of the valve member 4. Rotating clockwise in FIG. 4 from the closed state (i.e., in direction of arrow O in FIG. 4), sets the valve member 4 to the open state (indicated by dash-double-dot lines 4 in FIG. 4). Rotating counterclockwise in FIG. 4 (i.e., in direction of arrow S in FIG. 4) from the open state sets the valve member 4 to the closed state (see solid line 4 in FIG. 4).

As shown in FIG. 3, a throttle gear 30 formed, for example, of a resin sector gear, is integrally provided at the left end portion of the throttle shaft 20, which protrudes from the left-side bearing boss portion 22 (see FIG. 5).

Further, between the throttle gear 30 and the side surface of the main body 3 facing the end surface of the throttle gear 30, a back spring 32 is provided to be positioned on the rotational axis L of the throttle shaft 20. The back spring 32 holds the throttle gear 30 constantly and resiliently in a position (hereinafter referred to as opener opening position) opened by a predetermined angle from the fully open position.

As shown in FIG. 3, the motor housing portion 6 of the main body 3 is substantially formed as a bottomed cylinder parallel to the rotational axis L of the throttle shaft 20 and open to the left in FIG. 3. The drive motor 33 constituted, for example, by a DC drive motor is accommodated in the motor housing portion 6. A mounting flange 35 is provided on a motor housing 34 defining an outer contour of the drive motor 33 and is fixed to the main body 3 by fixing means (e.g., screws 35a) (see FIG. 5).

Further, a motor pinion 37 formed, for example, of a resin (see FIG. 5) is integrally formed with the protruding end of a motor shaft 36, which protrudes to the left in FIG. 3 from the mounting flange 35 of the drive motor 33.

As shown in FIG. 3, between the main body 3 and a cover body 40 closing the open end surface thereof (left-side open end surface in FIG. 3), a hollow counter shaft 38 is provided and extends parallel to the rotational axis L of the throttle shaft 20. The counter shaft 38 is, for example, a metal hollow cylinder and is fitted into and positioned between protruding shaft portions 41 and 42 respectively protruding from opposing end surfaces of the main body 3 and the cover body 40.

A counter gear 39 formed, for example, of a resin is rotatably supported by the counter shaft 38. As shown in FIG. 5, the counter gear 39 has a large diameter gear part 43 and a small diameter gear part 44 which are of different gear diameters. The large diameter gear part 43 is in mesh with the motor pinion 37, and the small diameter gear part 44 is in mesh with the throttle gear 30.

A reduction gear mechanism 45 is constituted by the throttle gear 30, the motor pinion 37, and the counter gear 39. The reduction gear mechanism 45 is accommodated in the gear housing space 29 formed between the main body 3 and the cover body 40 (see FIG. 3).

The cover body 40, which is made, for example, of resin is joined to one side surface (left side surface in FIG. 3) of the main body 3. As a joining means for joining the cover body 40 to the main body 3, it is possible to adopt a snap-fit means, a clip means, a screw fastening means, welding, etc. Further, between the main body 3 and the cover body 40, an O-ring 46 for maintaining hermeticity of an interior is interposed if necessary.

As shown in FIG. 1, a connector portion 48 is formed integrally with the cover body 40. An external connector (not shown) electrically is connected to a control device 52 (see FIG. 2) and can be connected to the connector portion 48. Terminals 51a to 51f are arranged in the connector portion 48. The terminals 51a to 51f are electrically connected to the drive motor 33 (see FIG. 3) and a throttle position sensor 50 described below (see FIG. 3).

The drive motor 33 (see FIG. 3) is drive-controlled by the control device 52, such as an engine control unit, or an ECU of an automobile (see FIG. 2), in response to an accelerator signal related to gas pedal depressing amount, a traction control signal, a constant-speed traveling signal, and an idle speed control signal.

The drive force of the motor shaft 36 of the drive motor 33 is transmitted from the motor pinion 37 to the throttle shaft 20 through the counter gear 39 and the throttle gear 30. This causes the valve member 4, which is integrated with the throttle shaft 20, to be rotated, with the result that the bore 7 is opened or closed.

As shown in FIG. 3, the throttle gear 30 is integrally provided with a ring-like yoke 53 made of a magnetic material and positioned coaxially with the rotational axis L of the throttle shaft 20. The inner peripheral surface of the yoke 53 is integrated with a pair of magnets 54 and 55 generating magnetic fields. The magnets 54 and 55 are formed, for example, of ferrite magnets, and are parallel-magnetized so that the magnetic lines of force generated between them, that is, the magnetic fields, are parallel to each other, generating substantially parallel magnetic fields in the space within the yoke 53.

On the inner side surface of the cover body 40, the throttle position sensor 50, which is a rotation angle sensor equipped with a sensor IC 56 with a built-in magnetoresistive element, is positioned. The throttle position sensor 50 is positioned on the rotational axis L of the throttle shaft 20 and between the magnets 54 and 55 at a predetermined interval. The sensor IC 56 of throttle position sensor 50 computes the output from the magnetoresistive element and outputs an output signal corresponding to the direction of the magnetic field to the control device 52, so that it is possible to detect the direction of the magnetic field without depending on the intensity of the magnetic field.

With the above-mentioned throttle body 2 (see FIGS. 1 through 5), when the engine is started, the drive motor 33 is drive-controlled by the control device 52. As noted above, the valve body 60 is thereby opened/closed through the reduction gear mechanism 45, with the result that the amount of intake air flowing through the bore 7 of the main body 3 is controlled.

As the throttle shaft 20 rotates, the yoke 53 and the magnets 54 and 55 rotate together with the throttle gear 30, so that the direction of the magnetic field across the sensor IC 56 of the throttle position sensor 50 varies in response to the rotation angle, and the output signal of the sensor 50 varies. The control device 52 thereby calculates the rotation angle of the throttle shaft 20, that is, the throttle opening of the valve member 4, in response to the output signal of the throttle position sensor 50.

The control device 52 (see FIG. 2) controls so-called control parameters, such as fuel injection control, correction control on the opening of the valve member 4, and automatic transmission control based on the throttle opening output from the sensor IC 56 of the throttle position sensor 50 (see FIG. 3) and detected according to the direction of the magnetic field as magnetic physical amount of the pair of magnets 54 and 55, vehicle speed detected by a vehicle speed sensor (not shown), engine RPM according to a crank angle sensor, and detection signals from sensors such as a gas pedal sensor, an O₂ sensor, and an air flow meter.

As shown in FIG. 4, the resin of the valve member 4, integrally molded on the throttle shaft 20, surrounds the periphery of the throttle shaft 20. At the center of the throttle shaft 20 corresponding to the center of the valve member 4, a through-hole 58 is formed to extend radially, and the resin has been flown into the through-hole 58. The valve body 60 is constituted by the throttle shaft 20 and the valve member 4 (see FIGS. 7 and 8).

The valve member 4 corresponds to the “valve part” in the present specification. The throttle shaft 20 corresponds to the “shaft part” in the present specification. While in this embodiment the valve body 60 is formed by integrating the throttle shaft 20 and the valve member 4, it is also possible to form the shaft part and the valve part as an integral unit of a resin (e.g., integral molding), thus forming a resin valve part in the form of a single component.

The valve member 4 has a shaft cover portion 61, a bridging portion 62, plate-like portions 63, and rib portions 65; The shaft cover portion 61 is formed in a substantially cylindrical configuration so as to surround the throttle shaft 20. The bridging portion 62 extends between opposing surfaces at the center of the shaft cover portion 61 so as to extend through the through-hole 58 of the throttle shaft 20. The plate-like portions 63 are formed of a pair of semi-circular portions and protrude in opposite directions from the shaft cover portion 61 so as to constitute a single disc (see FIG. 3). The valve-side sealing surfaces 15 are formed at the outer peripheral end surfaces of the plate-like portions 63 (see FIG. 7).

As shown in FIG. 7, the valve-side sealing surfaces 15 of the plate-like portions 63 are formed in point symmetry with respect to the axis L, and are formed as tapered surfaces whose outer diameter gradually increases from the closed side toward the open side with respect to the thickness direction. Further, the valve-side sealing surfaces 15 are formed at the time of molding the valve member 4, and are in surface-to-surface contact with the sealing surface 16 of the main body 3. As stated above, on the bore wall surface 13 of the primary tubular portion 10 of the main body 3, the body-side sealing surface 16 is formed and is in surface-to-surface contact with the valve-side sealing surfaces 15 of the valve member 4 (see FIG. 7).

The bearing contact portions 64 expand annularly from both end portions of the shaft cover portion 61 (FIG. 6 only shows the right end portion), and extend over both plate-like portions 63.

The rib portions 65 are continuous with the shaft cover portion 61 and protrude in a plural number from the front and back surfaces of the plate-like portions 63 at predetermined intervals (see FIG. 1). Ridges of the rib portions 65 extend from near free ends of the plate-like portions 63 tangentially with respect to the outer peripheral surface of the shaft cover portion 61 (see FIG. 7).

The support shaft portions 21 of the throttle shaft 20 and the bearing contact portions 64 of the valve member 4 are formed so as to be spaced apart from each other by a predetermined interval, with the small-diameter shaft body 20a being exposed in a groove-like fashion between the support shaft portions 21 and the bearing contact portions 64 (see FIG. 6). Further, except for the valve-side sealing surfaces 15, the valve member 4 is formed symmetrically with respect to both sides and both surfaces thereof.

Next, a method of manufacturing the above-mentioned throttle body 2 will be described. As methods of manufacturing the throttle body 2, a manufacturing method 1 and a manufacturing method 2, described below, are available.

Manufacturing Method 1 for the Throttle Body 2

A manufacturing method 1 for the throttle body 2 includes a process of molding the valve body 60 and a process of molding the main body 3.

In the process for molding the valve body 60, the valve member 4 is molded by a resin injection molding process using a valve molding die (mold). In this process, the throttle shaft 20 is inserted into the valve molding die, and then resin is injected into a mold space, that is, so-called cavity in conformity with the configuration of the valve member 4, so that the valve 60 is molded with the valve member 4 integrated with the throttle shaft 20. Since the valve molding die used in this process is of a well-known construction, a description thereof will be omitted.

Next, in the process for molding the main body 3, the main body 3 is molded by a resin injection molding process using a body molding die (mold). In this process, the valve body 60 molded in the previous process, the bearing sleeves 24, etc. are inserted, and then resin is injected into a mold space, that is, so-called cavity corresponding to the configuration of the main body 3, so that the main body 3 is molded with the valve body 60 assembled (see FIG. 5). Further, the resin is filled along the valve-side sealing surfaces 15 of the valve member 4, so that the body-side sealing surface 16 in conformity with the valve-side sealing surfaces 15 is formed in the main body 3. The body molding die used in this process will be described below.

Manufacturing Method 2 for the Throttle Body 2

Manufacturing method 2 for the throttle body 2 includes a process of molding the main body 3 and a process of molding the valve body 60.

First, in the process of molding the main body 3, the main body 3 is molded by a resin injection molding process using a body molding die (mold). At that time, the bearing sleeves 24 is inserted, and then the resin is injected into a molding space, that is, so-called cavity in conformity with the configuration of the main body 3, so that a body subassembly in which the main body 3 is integrated with the bearing sleeves 24. The body molding die used in this process is of a well-known construction, and therefore, a description thereof will be omitted.

Next, in the process of molding the valve body 60, the valve member 4 is molded by a resin injection molding process using a valve molding die (mold). At that time, the body subassembly molded in the previous process and the throttle shaft 20 are inserted into the valve molding die, and then resin is injected into a molding space or so-called cavity in conformity with the configuration of the valve member 4, so that the valve member 4 having the body subassembly incorporated therein and integrated with the throttle shaft 20 is molded. Further, the resin is filled along the body-side sealing surface 16 of the main body 3, so that the valve-side sealing surfaces 15 in conformity with the body-side sealing surface 16 are formed in the valve member 4. The valve molding die used in this process is of a well-known construction, and therefore, a description thereof will be omitted.

The plug 26, the sealing material 27, the back spring 32, the drive motor 33, the reduction gear mechanism 45, the cover body 40, etc. are assembled to the throttle body 2 molded by the manufacturing method 1 or the manufacturing method 2 described above, so that the throttle body 2 is completed (see FIG. 3).

As the resin material of the main body 3 and the valve member 4 described above, it is possible to use a composite material using a synthetic resin as the base material (matrix). Examples of the synthetic resin base material that can be adopted include polyester type resins such as polyethylene terephthalate and polybutylene terephthalate, polyolefin type resins such as polyethylene and polypropylene, polyamide type resins such as polyamide 6, polyamide 66, and aromatic polyamide, general-purpose resins such as ABS, polycarbonate, and polyacetal, super engineering plastics such as a polyacetal resin, polyphenylene sulfide, polyether sulfone, polyetherether ketone, polyether nitrile, and polyether imide, thermosetting resins such as a phenol resin, an epoxy resin, and an unsaturated polyester resin, and synthetic resins such as a silicone resin and a teflon (registered trademark) resin.

The above-mentioned composite material includes a fibrous material and a filler material. Examples of such materials that can be adopted include fibers such as glass fiber, carbon fiber, ceramics fiber, cellulose fiber, vinylon fiber, brass fiber, and aramide fiber, calcium carbonate, zinc oxide, titanium oxide, alumina, silica, magnesium hydroxide, talc, calcium silicate, mica, glass, carbon, graphite, thermosetting resin powder, and cashew dust. In some cases, it is possible to mix flame retardant, ultraviolet inhibitor, antioxidant, lubricant, etc. with the composite material

Next, the construction of a primary portion of this embodiment will be described. As shown in FIG. 3, the valve member 4 and the bearing sleeves 24 are formed symmetrically, so the following description will center on right-hand side portions of those, and a description of left hand side portions of those will be omitted.

As shown in FIG. 6, the moving amount of the valve member 4 in the thrust direction (horizontal direction in FIG. 6) is regulated through sliding contact between the opposing end faces of the valve member 4 and the bearing sleeves 24. The end faces 67 of the bearing contact portions 64 of the valve member 4 facing end faces 69 of the bearing sleeves 24 will be referred to as the “slide faces of the valve member 4, valve-side slide faces”, etc., and the end faces 69 in sliding contact with the valve-side slide faces 67 will be referred to as the “slide faces of the bearing sleeves 24, bearing-side slide faces 69”, etc. The valve-side slide faces 67 and the bearing-side slide faces 69 are formed by planes orthogonal to the rotation axis L of the throttle shaft 20. Between the valve-side slide faces 67 and the bearing-side slide faces 69, there are secured predetermined clearances or so-called gaps in order to achieve an improvement in terms of the operation property regarding the opening and closing of the valve body 60. In this specification, the “clearances between the valve-side slide faces 67 and the bearing-side slide faces 69” refer to the clearances between the slide faces 67, 69 when the valve member 4 is situated coaxially inside the bore 7. The bearing sleeves 24 correspond to the “bearing members” in this specification.

Each bearing sleeve 24 has a cylindrical tube body 70 and a flange portion 71 annularly expanding from the outer periphery of a valve-side end portion of the tube body 70. The bearing sleeves 24 are formed of dry bearings made of material having a good sliding property. Examples of the material having a good sliding property include metal materials, such as a copper-type sintered material and a SUS material.

The outer peripheral portion of each bearing sleeve 24 including the flange portion 71 is surrounded by a bearing boss portion 22 of the main body 3.

The slide face 69 of each bearing sleeve 24 is formed by the corresponding end face of the tube body 70 including the flange portion 71.

Further, the slide face 69 of each bearing sleeve 24 is formed to have a radius 69r which is equal to or larger than a radius 68r of a path of rotation 68 of the radially outer end (indicated by reference symbol 67a in FIG. 7) of each slide face 67 of the valve member 4 (see FIG. 7). With this arrangement, the slide faces 67 of the valve member 4 can entirely slidably contact with the slide faces 69 of the bearing sleeves 24.

FIG. 7 also shows a radius 69R of the bearing-side slide faces 69 of a conventional example. Conventionally, the bearing-side slide faces 69 are formed to have the radius 69R which is smaller than the radius 68r of the path of rotation 68, so that the radially outer end portions of the valve-side slide faces 67 extend beyond the bearing-side slide faces 69. Thus, the radially outer end portions of the valve-side slide faces 67 slidably contact with the bore wall surface 13, which is the opposing wall surface of the main body 3, resulting in resin-to-resin sliding contact between the valve member 4 and the main body 3.

With throttle body 2 described above, the bore 7 of the main body 3 is opened and closed by the valve member 4 rotating with the throttle shaft 20 of the valve body 60, so that the amount of intake air flowing through the bore 7, that is, the intake air amount, is controlled.

Further, the moving amount of the valve member 4 in the thrust direction (axial direction) is regulated through the sliding contact of the end faces 67 of the valve member 4 with the end faces 69 of the bearing sleeves 24.

The bearing sleeves 24 are formed of a metal material having a good sliding property, and the end faces 69 of the bearing sleeves 24 are formed as end faces (slide faces) of a good sliding property, so that it is possible to reduce the frictional resistance of the end faces 67 of the valve member 4 against the end faces 69 of the bearing sleeves 24.

Further, the end faces 69 of the bearing sleeves 24 are formed to have the radius 69r, which is equal to or larger than the radius 68r of the paths of rotation 68 of the radially outer ends 67a of the end faces 67 of the valve member 4, so that the end faces 67 of the valve member 4 can entirely slidably contact with the end faces 69 of the bearing sleeves 24. Therefore, it is possible to avoid sliding contact of the valve member 4 with the bore wall surface 13 of the main body 3.

Thus, by the synergistic effect of the reduction in the frictional resistance of the end faces 67 of the valve member 4 against the end faces 69 of the bearing sleeves 24 and the avoidance of sliding contact of the valve member 4 with the bore wall surface 13 of the main body 3, it is possible to improve the operation property of the valve member 4.

An experiment conducted by the present applicant for comparison between a conventional product and a product according to this embodiment in terms of a wear amount of the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24 showed that, as compared with the conventional example, this embodiment exhibits reduction in the wear amount to approximately ⅙.

Further, since the bearing sleeves 24 themselves are formed of a metal material having a good sliding property, it is possible to reduce the frictional resistance between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24.

The same effects as described above can be obtained by using, instead of a metal material having a good sliding property, a resin material having a good sliding property, such as a polyphenylene sulfide resin (PPS), as the material of the bearing sleeves 24 themselves.

Further, the same effects can be obtained by forming slide layers having a good sliding property on the end faces 69 of the bearing sleeve 24. The slide layers having a good sliding property can be formed, for example, by plasma ion implantation films, fluororesin coating films, etc. In such a case, as the bearing sleeves 24, those made of metal, resin, etc. may be used.

The same effects as described above can be obtained by forming slide layers having a good sliding property on the end faces 67 of the valve member 4. The slide layers having a good sliding property can be formed, for example, by plasma ion implantation films, fluororesin coating films, etc.

Further, it is possible to provide slide layers having a good sliding property on the outer peripheral surfaces of the support shaft portions 21 of the throttle shaft 20, which are rotatably supported by the bearing sleeves 24. With this construction, it is possible to reduce the frictional resistance between the inner peripheral surfaces of the shaft holes of the bearing sleeves 24 and the outer peripheral surfaces of the support shaft portions 21 of the throttle shaft 20.

Further, it is possible to provide slide layers having a good sliding property on the inner peripheral surfaces of the shaft holes of the bearing sleeves, which rotatably support the support shaft portions 21 of the throttle shaft 20. With this construction, it is possible to reduce the frictional resistance between the inner peripheral surfaces of the shaft holes of the bearing sleeves 24 and the outer peripheral surfaces of the support shaft portions 21 of the throttle shaft 20.

Further, it is possible to make the throttle shaft 20 of the above embodiment of resin, and to provide slide layers having a good sliding property on the outer peripheral surfaces of the support shaft portions 21 of the throttle shaft 20, which are rotatably supported by the bearing sleeves 24. With this construction, it possible to reduce the frictional resistance of the support shaft portions 21 of the resin throttle shaft 20 against the metal bearing sleeves 24. Further, by making the throttle shaft 20 of resin, it is possible to abolish the metal throttle shaft, so it is possible to achieve a reduction in cost and weight. In such a case, by molding the throttle shaft 20 integrally with the valve member 4, it is possible to achieve a further reduction in cost. The throttle shaft 20 can be made of polyphenylene sulfide resin (PPS) or the like, which has a good sliding property.

Further, it is possible to make the bearing sleeves 24 of the above embodiment of resin, and to provide slide layers having a good sliding property on the end faces 67 of the valve member 4, which slidably contact with the end faces 69 of the bearing sleeves 24. With this construction, it possible to reduce the frictional resistance of the end faces 67 of the resin valve member 4 against the end faces 24 of the resin bearing sleeves. Further, by making the bearing sleeves 24 of resin, it is possible to abolish the metal bearing sleeves, so that it is possible to achieve a reduction in cost and weight. Further, in such a case, by molding the bearing sleeves 24 integrally with the bearing boss portions 22 of the main body 3, it is possible to achieve a further reduction in cost. The bearing sleeves 24 can be made of polyphenylene sulfide resin (PPS) or the like, which has a good sliding property.

Further, it is possible to make the bearing sleeves 24 of the above embodiment of resin, and to provide slide layer of a good sliding property on the end faces 69 of the bearing sleeves 24, which slidably contact with the end faces 67 of the valve member 4. With this construction, it possible to reduce the frictional resistance of the end faces 67 of the resin valve member 4 against the end faces 24 of the resin bearing sleeves. Further, by making the bearing sleeves 24 of resin, it is possible to abolish the metal bearing sleeves, so that it is possible to achieve a reduction in cost and weight. In such a case, by molding the bearing sleeves 24 integrally with the bearing boss portions 22 of the main body 3, it is possible to achieve a further reduction in cost. The bearing sleeves 24 can be made of polyphenylene sulfide resin (PPS) or the like, which has a good sliding property.

Further, it is possible to make the bearing sleeves 24 and the throttle shaft 20 of the above embodiment of resin, and to provide slide layers having a good sliding property on the end faces 67 of the valve member 4, which slidably contact with the end faces 69 of the bearing sleeves 24, and on the outer peripheral surfaces of the support shaft portions 21 of the throttle shaft 20, which are rotatably supported by the bearing sleeves 24. With this construction, it is possible to reduce the frictional resistance of the end faces 67 of the resin valve member 4 against the end faces 69 of the resin bearing sleeves 24 and the frictional resistance of the support shaft portions 21 of the resin throttle shaft 20 against the bearing sleeves 24. Further, by making the bearing sleeves 24 and the throttle shaft 20 of resin, it is possible to abolish the bearing sleeves and the throttle shaft that are made of metal, so that it is possible to achieve a reduction in cost and weight. In such a case, by molding the bearing sleeves 24 integrally with the bearing boss portions 22 of the main body 3, it is possible to achieve a further reduction in cost. Further, by molding the throttle shaft 20 integrally with the valve body 60, it is possible to achieve a further reduction in cost. The bearing sleeves 24 and the throttle shaft 20 can be made of polyphenylene sulfide resin (PPS) or the like, which has a good sliding property.

Further, it is possible to make the bearing sleeves 24 of the above embodiment of resin, and to provide slide layers having a good sliding property on the end faces 69 of the bearing sleeves 24, which slidably contact with the end faces 67 of the valve member 4, and on the inner peripheral surfaces of the shaft holes of the bearing members, which rotatably support the throttle shaft 20. With this construction, it possible to reduce the frictional resistance of the end faces 67 of the resin valve member 4 against the end faces 69 of the resin bearing sleeves 24 and the frictional resistance of the support shaft portions 21 of the resin throttle shaft 20 against the bearing sleeves 24. Further, since the bearing sleeves 24 are made of resin, it is possible to abolish the metal bearing sleeves, so that it is possible to achieve a reduction in cost and weight. In such a case, by molding the bearing sleeves 24 integrally with the bearing boss portions 22 of the main body 3, it is possible to achieve a further reduction in cost. The bearing sleeves 24 can be made of polyphenylene sulfide resin (PPS) or the like, which has a good sliding property.

Embodiment 2

Embodiment 2 will be described. This embodiment is a partial modification of Embodiment 1, so that the following description will be made to the modified portions, and a redundant description will not be made. Also, for the following embodiments, the description will be made to the modified portions, and a redundant description will not be made.

As shown in FIG. 8, in this embodiment, annular stepped portions 73 are formed on the inner periphery of the end faces 69 of the bearing sleeves 24. The bearing contact portions 64 of the valve member 4 are fitted into the stepped portions 73.

According to this embodiment, since the bearing contact portions 64 of the valve member 4 are fitted into the stepped portions 73 of the end faces 69 of the bearing sleeves 24, clearances 72 between the end faces of the bearing sleeves 24 and the valve member 4 exhibit a labyrinth structure. As a result, when the valve body 60 is fully closed, the flow of intake air through the clearances 72 between the end faces of the bearing sleeves 24 and the valve member 4 is hindered. Thus, it is possible to reduce the air leakage amount when the valve body 60 is fully closed. If the air leakage amount when the valve body 60 is fully closed is large, increase in an idling RPM of an engine and deterioration in fuel efficiency may result. Therefore, it is preferable to reduce the air leakage amount in the fully closed state and to reduce the engine idling RPM, thereby achieving an improvement in terms of fuel efficiency.

Embodiment 3

Embodiment 3 will be described. Like Embodiment 2, this embodiment is a partial modification of Embodiment 1.

As shown in FIG. 9, in this embodiment, annular stepped portions 74 are formed on the inner periphery of the end faces 67 of the valve member 4. Annular tubular fitting portions 75 to be fitted into the stepped portions 74 of the valve member 4 are formed on the inner periphery of the end faces 69 of the bearing sleeves 24.

According to this embodiment, since the tubular fitting portions 75 of the bearing sleeves 24 are fitted into the stepped portions 74 of the valve member 4, the clearances 72 between the end faces of the bearing sleeves 24 and of the valve member 4 exhibit a labyrinth structure. Thus, as in Embodiment 2, it is possible to reduce the air leakage amount when the valve body 60 is fully closed.

Embodiment 4

Next, Embodiment 4 will be described. This embodiment is a partial modification of Embodiment 1. FIG. 10 is a front sectional view of a throttle body, FIG. 11 is a sectional view of a primary portion when molding re the main body, FIG. 12 is an end view of a portion around a bearing sleeve when molding the main body, FIG. 13 is a sectional view of a primary portion after movement for adjustment of the bearing sleeve, FIG. 14 is an end view of a portion around the bearing sleeve after the movement for adjustment of the bearing sleeve, FIG. 15 is a sectional view of a body molding die, and FIG. 16 is a perspective view of a bearing-sleeve pivotal die. In FIG. 10, the cover body 40, the plug 26, the throttle gear 30, the back spring 32, the drive motor 33, etc. of FIG. 3 are omitted.

As is better shown in FIG. 11, in this embodiment, the bearing sleeves 24 of Embodiment 1 (see FIG. 3) are replaced with straight cylindrical bearing sleeves (indicated by reference numeral 84). Like the bearing sleeves 24, the bearing sleeves 84 correspond to the “bearing members” in this specification.

As shown in FIG. 16, a male thread 85 is formed on the outer peripheral surface of each bearing sleeve 84. Further, in the outer end face of each bearing sleeve 84 on a side opposite to the valve, two recesses 86 are formed, for example, at radially opposing positions (see FIG. 12).

As shown in FIG. 15, a body molding die 90 of this embodiment molds the main body 3 with the valve body 60 and the pair of right and left bearing sleeves 84 inserted. The body molding die 90 is equipped with a lower die 91, which is a stationary die forming a cavity 88 corresponding to the main body 3, an upper die 92, which is a movable die and is vertically movable, and. a plurality of lateral dies 93, which are movable dies and are laterally movable. The body molding die 90 is applicable to the above-mentioned manufacturing method 1 for the throttle body 2.

A pouring gate or resin injecting gate 94 is formed between the lower die 91 and the lateral dies 93 and communicate with the cavity 88 from the lateral side. The valve member 4 in the fully closed position is placed between the lower die 91 and the upper die 92.

Further, bearing-sleeve pivotal dies 95 are respectively arranged in the right and left lateral dies 93. The bearing-sleeve pivotal dies 95 are positioned on the rotation axis L of the throttle shaft 20 and are rotatable and axially movable by a driving means (not shown). Engaging projections 96 are formed on distal ends of the bearing-sleeve pivotal dies 95 are respectively engageable with the recesses 86 of the bearing sleeves 84 (see FIG. 16).

The case in which the main body 3 is molded by the body molding die 90 will be described. As shown in FIG. 15, the valve body 60 is inserted into the body molding die 90 with the valve member 4 in the fully closed state, and the bearing sleeves 84 (see FIG. 16) are fitted with the support shaft portions 21 of the throttle shaft 20. In this state, the dies 91, 92, 93, 95 of the body molding die 90 are closed. At that time, the engaging projections 96 of the right and left bearing-sleeve pivotal dies 95 respectively engage with the recesses 86 of the bearing sleeves 84. Subsequently, resin (more specifically, molten resin) is injected from the resin injecting gate 94 into the cavity 88 defined by the body molding die 90 to thereby mold the main body 3.

Then, in a semi-cured state prior to the curing of the resin, the right and left bearing-sleeve pivotal dies 95 are pivoted by a predetermined angle (see arrow Y1 in FIG. 14), so that the bearing sleeves 84 move in the axial direction or to threadably retreat by a predetermined amount (see arrow Y2 in FIG. 13) with respect to the bearing boss portions 22. of the main body 3 (see FIG. 14). In this specification, “semi-cured state of the resin” means such a semi-cured state that allows the bearing sleeves 84 to move in the axial direction through rotation without generating any cracks in the bearing boss portions 22 of the main body 3 and that does not cause accidental flow of resin into clearances 98 set between the valve member 4 and the bearing sleeves 84 by the movement of the bearing sleeves 84. This semi-cured state of the resin also corresponds to the state “after molding the main body” in this specification.

As a result, predetermined clearances 98 are ensured between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 84 (see FIG. 13). The threadably retreating amount (axial retreating amount) of the bearing sleeves 84 at this time is such an amount that takes into account of the molding shrinkage of the main body 3 and that ensures the predetermined clearances 98 (see FIG. 13) between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 84.

After completion of the curing of the main body 3, the dies 91, 92, 93, 95 are opened, and the mold product or the throttle body 2 (see FIG. 10) is extracted.

According to the throttle body 2 described above, after molding the main body 3 (in the semi-cured state prior to the curing of the resin in this embodiment), the bearing sleeves 24 provided on the main body 3 are moved in the axial direction of the throttle shaft 20, so that the clearances 98 (see FIG. 13) between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24 are adjusted to a predetermined amount. Thus, it is possible to improve the operation property of the valve body 60.

If the clearances 98 is too large, the air leakage amount in the fully closed state increases. Therefore, the bearing sleeves 84 are moved in the axial direction of the throttle shaft 20 with respect to the main body 3 in order to provide the clearances 98 (see FIG. 13) between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24, which clearances enable to reduce the air leakage amount in the fully closed state of the valve member 4 while improving the operation property of the valve member 4.

Conventionally, when molding the main body 3, predetermined clearances are ensured between the valve member 4 and the bearing members (straight cylindrical bearings without male threads) by taking into account of the molding shrinkage of the main body 3 beforehand, and the main body 3 is molded in this state. Therefore, the resin may flow into the clearances to fill the requisite clearances to impair the operation property of the valve body 60.

In contrast, according to the present embodiment, it is possible, as described above, to ensure the requisite clearances 98 (see FIG. 13) between the valve member 4 and the bearing sleeves 84, so that it is possible to improve the operation property of the valve body 60.

According to the above-mentioned manufacturing method for the throttle body 2, it is possible to manufacture a throttle body 2 that can provide the above-mentioned effects.

Embodiment 5

Next, Embodiment 5 will be described. This embodiment is a partial modification of Embodiment 1. FIG. 17 is a sectional view of a primary portion, and FIG. 18 is a perspective view of a spacer member.

This embodiment is applicable to the manufacturing method 1 or manufacturing method 2 for the throttle body 2 described in Embodiment 1.

In the manufacturing method 1 for the throttle body 2, when molding the main body 3 with the valve member 4 inserted together with the bearing sleeves 24, ring-plate-like spacer members 114 having a predetermined thickness 114t (see FIG. 18) are positioned between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24 (see FIG. 17).

In the manufacturing method 2 for the throttle body 2, when molding the valve member 4 with the main body 3 inserted together with the bearing sleeves 24, the ring-plate-like spacer members 114 having the predetermined thickness 114t (see FIG. 18) are positioned between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24 (see FIG. 17). In this case, until the valve member 4 is molded, the end faces of the valve molding die (not shown) defining the same planes as the end faces 67 of the valve member 4 (hereinafter referred to as end faces of the valve member 4) correspond to the “end faces 67 of the valve member 4”, and the spacers members 114 are positioned between those end faces and the end faces 69 of the bearing sleeves 24.

The spacer members 114 are made of a material, such as bismuth, which is melted by the heat of hot water, an easily meltable alloy containing tin, etc., or a medicinal wafer, which is melted in water, and are solved by a dissolving means, such as chemical products, water, hot Water, or high temperature atmosphere. The spacer members 114 correspond to the “spacer means” in this specification.

As described above, by positioning the spacer members 114 (see FIG. 18) between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24, it is possible to mold the main body 3 or the valve member 4, with clearances (indicated by the same reference numeral as the thickness) 114t corresponding to the thickness 114t of the spacer members 114 ensured between the end faces 67 and 69. In addition, due to the presence of the spacer members 114, it is possible to prevent or reduce accidental flow of the resin between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24 when the resin is injected. The thickness 114t of the spacer members 114 is set to a dimension corresponding to the predetermined clearances 114t that takes into account of the molding shrinkage of the main body 3.

After the completion of curing of the resin of the main body 3 or the valve member 4, the spacer members 114 are dissolved and removed, for example, by the dissolving means as described above, so that it is possible to form the predetermined clearances 114t (see FIG. 17) between the valve member 4 and the bearing sleeves 24 and to ensure the requisite operation property of the valve member 4.

Further, since there the clearances between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24 will not become greater than a predetermined value, it is possible to prevent or reduce accidental inflow of the resin into the clearances 114t during molding, and increase in air leakage amount when the valve member 4 is in the fully closed state.

Further, as described above, due to the use of the spacer members 114 that are dissolved by the dissolving means, it is possible, in the manufacturing method 1 for the throttle body 2, to set the clearances 114t between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24 by using the end faces 67 of the valve member 4 as a reference. In the manufacturing method 2 for the throttle body 2, it is possible to set the clearances 114t between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24 by using the end faces 69 of the bearing sleeves 24 as a reference.

With the throttle body 2 described above, when molding one of the valve body 60 and the main body 3 with the other inserted together with the bearing sleeves 24, the spacer members 114 are positioned between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24, and the spacer members 114 are removed after molding the main body 3 or the valve member 4. Therefore, it is possible to set predetermined clearances 114t between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24 by the spacer members 114, so that operation property of the valve body 60 can be improved. Further, the clearances 114t between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24 are those enabling reduction of the air leakage amount when the valve body 60 is fully closed while improving the operation property of the valve body 60. Therefore, it is possible to reduce the air leakage amount when the valve body 60 is fully closed while improving the operation property of the valve body 60.

According to the above-mentioned manufacturing method for the throttle body 2, it is possible to manufacture a throttle body 2 providing the above-mentioned effects.

The following modifications 1 through 5 may be considered for Embodiment 5.

Modification 1

As shown in FIG. 19, between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24, pairs of metal gage members 117 having half-ring-plate-like configurations and having a predetermined thickness 117t (see FIG. 20) are positioned in place of the spacer members 114 (see FIG. 17). The gage members 17 are formed, for example, of clearance gages, and are removed by a mechanical external force after the resin of the main body 3 or the valve member 4 has been cured. Therefore, it is possible to form predetermined clearances (clearances corresponding to the thickness 117t) between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24. The gage members 117 correspond to the “spacer means” in this specification.

Modification 2

As shown in FIG. 21, projection portions 118 adapted to contact with the end faces 69 of the bearing sleeves 24 for ensuring predetermined clearances are integrally provided on the end faces 67 of the valve member 4 (see FIG. 22). After the resin of the main body 3 or the valve member 4 has been cured, the projection portions 118 of the valve member 4 are removed by a removing means, such as snapping or cutting, so that it is possible to form predetermined clearances (clearances corresponding to the projecting amount of the projection portions 118) between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24. The projection portions 118 correspond to the “spacer means” in this specification.

In Modification 2, it is also possible to provide the projection portions 118 on the end faces 69 of the bearing sleeves 24 such that it can contact with the end faces 67 of the valve member 4, or to provide them on the molding die for the valve body 60 such that they can contact with the end faces 69 of the bearing sleeves 24. Therefore, predetermined clearances between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24 can be ensured. Also in this case, the projection portions 118 are removed by a removing means, such as snapping, cutting, or laser, after the main body 3 or the valve member 4 has been molded.

Modification 3

As shown in FIG. 23, projecting portions 215 each having a contacting end face 215a for ensuring predetermined clearances by contacting with the end faces 69 of the bearing sleeves 24 are integrally formed on the plate-like portions 63 of the valve member 4. The projecting portions 215 protrude beyond the end faces 67 of the valve member 4 by an amount corresponding to the predetermined clearances. After the resin of the main body 3 or the valve member 4 has been cured, the projecting portions 215 of the valve member 4 are removed by a removing means, such as laser, in order to form end surfaces 67 defining the same planes as the end faces 67 on the plate-like portions 63 of the valve member 4 (see FIG. 24), so that it is possible to form predetermined clearances (indicated by reference numeral 217 in FIG. 29) between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24. The projecting portions 215 correspond to the “spacer means” in this specification.

The projecting portions 215 of Modification 3 may be provided on the end faces 69 of the bearing sleeves 24 such that they can contact with the end faces 67 of the valve member 4, or they may be provided on the molding die for the valve member 4 such that they can contact with the end faces 69 of the bearing sleeves 24. Therefore, it is possible to ensure predetermined clearances between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24. Also in this case, the projecting portions 215 are removed by a removing means, such as laser, after the main body 3 or the valve body 60 has been molded.

Modification 4

As shown in FIG. 25, between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24, rubber resilient members 116 of substantially the same configuration as the spacer members 114 of Embodiment 5 (see FIG. 18) are positioned. Like the spacer members 114 of Embodiment 5, the resilient members 116 are removed by a removing means after curing of the resin of the main body 3 or the valve member 4, so that it is possible to set predetermined clearances 116t of a predetermined amount between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24. The resilient members 116 correspond to the “spacer means” in this specification.

Further, it is possible to regard ranges allowed for resilient deformation (compressive deformation) in the thickness direction of the resilient members 116 as the clearances between the end faces 67 of the valve member 4 and the end faces 69 of the bearing sleeves 24. In this case, there is no need to remove the resilient members 116 after the resin of the main body 3 or the valve member 4 has been cured.

By integrally forming the resilient members 116 on the end faces 67 of the valve member 4 or the end faces 69 of the bearing sleeves 24 in advance by two-color molding, it is advantageously possible to omit the time and effort for mounting the resilient members 116.

As a material of the resilient members 116, it is possible, for example, to use elastomer.

The present invention is not restricted to the above-mentioned embodiments and allows modifications without departing from the gist of the present invention.

Claims

1. A throttle body comprising:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members, wherein:

the end faces of at least one of the valve part and the bearing members slidably contacting with each other are formed as end faces of a good sliding property, and

the end faces of the bearing members are formed to have a radius equal to or larger than a radius of paths of rotation of radially outer ends of the end faces of the valve part.

2. A throttle body according to claim 1, wherein the bearing members are made of material having a good sliding property.

3. A throttle body according to claim 1, wherein slide layers having a good sliding property are provided on the end faces of the bearing members, which slidably contact with the end faces of the valve part.

4. A throttle body according to claim 1, wherein the slide layers having a good sliding property are provided on the end faces of the valve part, which slidably contact with the end faces of the bearing members.

5. A throttle body according to claim 1, wherein the slide layers having a good sliding property are provided on outer peripheral surfaces of support shaft portions of the shaft part, which are rotatably supported by the bearing members.

6. A throttle body according to claim 1, wherein the slide layers having a good sliding property are provided on inner peripheral surfaces of shaft holes of the bearing members, which rotatably support the shaft part.

7. A throttle body comprising:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing member, wherein:

the bearing members are made of metal,

the shaft part is made of resin, and

slide layers having a good sliding property are provided on outer peripheral surfaces of support shaft portions of the shaft part, which are rotatably supported by the bearing members.

8. A throttle body comprising:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing member, wherein:

the bearing members are made of resin,

the shaft part is made of metal, and

slide layers having a good sliding property are provided on the end faces of the valve part, which slidably contact with the end faces of the bearing members.

9. A throttle body comprising:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing member, wherein:

the bearing members are made of resin,

the shaft part is made of metal, and

slide layers having a good sliding property are provided on the end faces of the bearing members, which slidably contact with the end faces of the valve part.

10. A throttle body comprising:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members, wherein:

the bearing members and the shaft part are made of a resin, and

slide layers having a good sliding property are provided on the end faces of the valve part slidably contacting with the end faces of the bearing members and on outer peripheral surfaces of support shaft portions of the shaft part, which are rotatably supported by the bearing members.

11. A throttle body comprising:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members, wherein:

the bearing members are made of resin,

the shaft part is made of metal, and

slide layers having a good sliding property are provided on the end faces of the bearing members slidably contacting with the end faces of the valve part and on inner peripheral surfaces of shaft holes of the bearing members, which rotatably support the shaft part.

12. A throttle body comprising:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members,

wherein clearances between the end faces of the valve part and the end faces of the bearing members are adjusted through axial movement of the bearing members.

13. A throttle body comprising:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members,

wherein, between the end faces of the valve part and the end faces of the bearing members, spacer means for setting clearances between the end faces to a predetermined amount are provided.

14. A method of manufacturing a throttle body, the throttle body comprising:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members,

the method of manufacturing the throttle body comprising adjusting clearances between the end faces of the valve part and the end faces of the bearing members through axial movement of the bearing members after molding the main body,

15. A method of manufacturing a throttle body, the throttle body comprising:

a resin main body defining a bore through which intake air flows; and

a valve body having a shaft part rotatably supported by the main body via a pair of bearing members and a resin valve part for opening and closing the bore of the main body, end faces of the valve part slidably contacting with end faces of the bearing members,

the method of manufacturing the throttle body comprising setting clearances between the end faces of the valve part and the end faces of the bearing members to a predetermined amount by spacer means when molding one of the valve part and the main body with the other inserted together with the bearing members.