FINGER LEVER

Abstract

The invention proposes a finger lever (1) for actuating a gas exchange valve (4) of an internal combustion engine, said finger lever (1) being composed of side walls (11), a valve contacting element (12), a roller axle (8)/roller (9) and a joint socket element (13). According to the invention, the side walls comprise through-openings (15, 16) that are aligned to each other in pairs and in which each of the valve contacting element and the joint socket element are retained after the manner of a pin and bore connection by respective axle ends or axle stubs (18, 19) pointing in a transverse direction of the side walls.

Description

FIELD OF THE INVENTION

The invention concerns a finger lever for actuating a gas exchange valve of an internal combustion engine, said finger lever comprising a first lever end on which a valve contacting surface for the gas exchange valve extends, and further comprising a lever center in which a roller axle and a roller mounted on said roller axle for contact of a cam extends, and comprising still further a second lever end on which a joint socket for a pivotal mounting of said finger lever on a stationary joint head arranged in the internal combustion engine extends. The finger lever comprises two side walls which extend spaced from each other in a longitudinal direction of the finger lever and are made as separate parts while being connected to each other, on the first lever end, through a valve contacting element retained on the side walls, at the lever center, through the roller axle retained in aligned through-openings of the side walls and, on the second lever end, through a joint socket element retained on the side walls.

BACKGROUND OF THE INVENTION

A finger lever of the pre-cited type comprising a lever body composed of a plurality of separate parts is disclosed already in the document DE 10 2005 057 298 A1 considered to be generic. In contrast to finger levers with lever bodies that are shaped out of a single sheet metal blank into a finished component by a multi-step punching and bending method and that, by reason of their dimensioning can be used only in a specific valve train kinematics, the modular construction of the multi-part lever body permits a maximized flexibility with regard to matching the finger lever to different valve train kinematics while simultaneously assuring minimized manufacturing costs for sample and large series tools. It is thus possible to equip finger levers of different sizes made after the modular principle with identical valve contacting elements, rollers and joint socket elements and modify only the side walls to suit the specific case of use.

A drawback of the pre-cited prior art is the proposed joining method for connecting the side walls to the valve contacting element and the joint socket element which are fixed by a sort of key and slot joint on the side walls. With a view to obtaining the precision required for the dynamic fatigue strength of valve train components, a connection of this type can only be realized with correspondingly high complexity and costs involved in the manufacturing.

A constructed finger lever is likewise disclosed in EP 1 500 794 A1 and comprises a valve contacting element made as a separate part. This valve contacting element is mounted floatingly and with limited rotational ability in aligned through-openings of the side wall after the manner of a pin and bore connection. The side walls, however, are shaped in one piece together with the joint socket element which connects the side walls to each other, so that the above-mentioned flexibility of the finger lever with regard to its matching to different valve train kinematics is not provided, or provided only to an inadequate extent.

OBJECT OF THE INVENTION

The object of the invention is therefore to improve the constructional design of a finger lever of the aforesaid type so that the cited drawbacks are eliminated.

SUMMARY OF THE INVENTION

The invention achieves the above object by the fact that the side walls on the first lever end and on the second lever end comprise through-openings aligned to each other in pairs, in which through-openings each of the valve contacting element and the joint socket element is retained after the manner of a pin and bore connection by respective axle ends or axle stubs pointing in a transverse direction of the side walls.

The measures disclosed in the dependent claims constitute appropriate, partially alternative developments of the invention which are described and explained more clearly in the following in connection with further features and advantages of the invention with reference to the appended drawings. In so far as possible and appropriate, these features can also be combined as desired with each other to obtain embodiments other than those represented herein.

Further, not represented embodiments concern rocker arms assembled together after the modular principle of the invention. In contrast to finger levers, rocker arms are not mounted for pivoting on one end of the lever but at its center.

BRIEF DESCRIPTION OF THE DRAWINGS

The figures show three-dimensional perspective views of a finger lever in an assembled state as well as the separate parts of the finger lever.

FIG. 1 show a first embodiment of a finger lever according to the invention;

FIG. 2 show a second embodiment of a finger lever according to the invention;

FIG. 3 show a third embodiment of a finger lever according to the invention;

FIG. 4 show a fourth embodiment of a finger lever according to the invention;

FIG. 5 show a fifth embodiment of a finger lever according to the invention;

FIG. 6 show a sixth embodiment of a finger lever according to the invention;

FIG. 7 show a seventh embodiment of a finger lever according to the invention;

FIG. 8 show an eighth embodiment of a finger lever according to the invention;

FIG. 9 show a ninth embodiment of a finger lever according to the invention;

FIG. 10 show a tenth embodiment of a finger lever according to the invention;

FIG. 11 show an eleventh embodiment of a finger lever according to the invention;

FIG. 12 shows a portion of a finger lever valve train, with different valve train kinematics as also finger levers matched to these, following the modular concept.

If not otherwise stated, identical or functionally identical components or features bear the same reference numbers.

DETAILED DESCRIPTION OF THE DRAWINGS

Starting point of the following elucidations is FIG. 12 in which finger levers 1, 1′ und 1″ constructed according to the modular principle of the invention for actuating gas exchange valves in internal combustion engines for different valve train kinematics are represented in a single drawing. A valve contacting surface 3 for actuating the gas exchange valve 4 extends on a first lever end 2 of the finger lever, and a joint socket for a pivotal mounting of the finger lever on a joint head of a support element 6 mounted immovably in the internal combustion engine extends on a second lever end 5 of the finger lever. The joint socket and the joint head are concealed in the illustration but are made in the form of a semi-spherical recess and as a ball head as known per se. At the lever center 7 extends a roller axle 8 and, mounted thereon through a rolling bearing or a slide bearing, a roller 9 for a low friction take-up of the lift of a cam 10. According to the invention, matching of the finger levers 1, 1′ und 1″ to the different valve train kinematics is achieved by the fact that the finger levers comprise only a pair of side walls 11, 11′ 11″ that are differently designed whereas the remaining components are identical parts. In design, the finger levers 1, 1′ und 1″ correspond to the embodiment of the invention illustrated in FIG. 8 to be described below.

FIG. 1 shows a finger lever 1a in the assembled state. The finger lever 1a is composed of two spaced side walls 11a extending parallel to each other in the longitudinal direction of the finger lever 1a, a valve contacting element 12a on which a valve contacting surface 3 extends, a joint socket element 13a on which a joint socket 14 extends and a roller axle 8 on which a roller 9 is mounted. The side walls 11a made as separate punched parts out of a sheet metal material are disclosed in FIG. 1a. The side walls 11a comprise on lever ends 2, 5 and at the lever center 7 through-openings 15a, 16a and 17 which are aligned to each other in pairs and in which the valve contacting element 12a, the joint socket element 13a and the roller axle 8 are respectively retained after the manner of a pin and bore joint and connect the side walls 11a to each other.

The valve contacting element 12a and the joint socket element 13a are made as sintered parts and are disclosed in enlarged illustrations in FIGS. 1b and 1c respectively. As also valid for the embodiments of the invention according to FIGS. 2 to 11 described below, alternatively, it is also conceivable to use creative forming manufacturing methods such as metal injection molding, casting, extrusion molding, forging etc. Both the elements 12a and 13a comprise, integrally configured thereon, axle studs 18a and 19a respectively which have a cylindrical shape and point in a transverse direction of the side walls 11a. These studs 18a and 19a are inserted into the circular through-openings 15a, 16a. Through a riveting of the front ends of the axle studs 18a, 19a, the elements 12a and 13a are retained secure against rotation through force locking on the side walls 11a.

According to FIG. 2a, the finger lever 1b illustrated in FIG. 2, comprises side walls 11b whose through-openings 15b, 16b on the two lever ends 2, 5 are not circular but oval in shape. The valve contacting element 12b (see FIG. 2b) in this case is an axle with a complementary shape to the through-openings 15b, i.e. a generally oval cross-sectional shape whose center section is recessed to form the convex valve contacting surface 3. The joint socket element 13b shown in FIG. 2c comprises integrally formed axle studs 19b which have an oval cross-section likewise complementary to the through-openings 16b. Through the oval axle ends 18b and the oval axle studs 19b, the valve contacting element 12b and the joint socket element 13b are retained secure against rotation by positive engagement in the through-openings 15b, 16b. In this way, the riveted joints on the front ends of the likewise riveted axle ends 18b and axle studs 19b have a good mechanical strength.

The finger lever 1c disclosed in FIG. 3 likewise comprises a good strength, positive engagement anti-rotation feature of the valve contacting element 12c and the joint socket element 13c relative to the side walls 11c. While the through-openings 15c, 16c, similar to the finger lever 1a, are circular in shape for receiving cylindrical axle ends 18c and 19c, the positive engagement is achieved through the fact that the elements 12c and 13c comprise on both sides, projections 20c and 21c that extend in transverse direction of the side walls 11c and engage into complementary recesses 22 and 23 on the lower edges of the side walls 11c (i.e. on the side turned towards the gas exchange valve). The valve contacting element 12c and the joint socket element 13c are made together with the projections 20c and 21c as one-piece sintered parts and are disclosed in enlarged illustrations in FIGS. 3a and 3b respectively. Each of the elements 12c, 13c comprises in this case a cross-bore 24 and 25 respectively through which, during assembly of the finger lever 1c a cylindrical axle 26, 27 is inserted. The axle ends 18c and 19c serve to retain the elements 12c and 13c in the through-openings 15c and 16c.

The advantageous feature of the finger levers 1a to 1c is the small number of separate parts.

In the examples of embodiment according to FIGS. 4 to 11 described below, the valve contacting element 12 and the joint socket element 13 are retained for rotation in a transverse direction of the finger lever 1 on the side walls 11. An advantage resulting from this arrangement is the comparatively low friction between the valve contacting surface 3 and the gas exchange valve 4. In contrast, the arrangement in which the elements 12 and 13 are secured against rotation has the advantage that the ratio between the cam lift curve and the valve lift curve does not vary.

The finger lever 1d illustrated in FIG. 4 comprises side walls 11d according to FIG. 4a that comprise circular through-openings 15d and 16d arranged on the lever ends 2, 5. Similar to the finger lever 1c, the valve contacting element 12d according to FIG. 4b and the joint socket element 13d according to FIG. 4c comprise cross-bores 24, 25 for receiving cylindrical axles 26, 27 whose axle ends 18d, 19d in this case, however, extend with a production-conducive clearance fit in the through-openings 15d and 16d so that the elements 12d, 13d are retained free to rotate on the side walls 11d, i.e. through any desired angle, in transverse direction of the finger lever 1d. The advantageous feature of this embodiment is the simplicity of manufacture of the finger lever 1d.

In contrast, in the finger levers 1 represented in FIGS. 5 to 11, the valve contacting element 12 and the joint socket element 13 comprise projections 28 and 29 extending in a transverse direction of the side walls 11, which projections 28 and 29, for limiting the rotation of the valve contacting element 12 and the joint socket element 13, abut against stop surfaces 30 and 31 of the side walls 11. Similar to the finger lever 1c and 1d, the valve contacting elements 12 and the joint socket elements 13 comprise cross-bores 24, 25 for receiving cylindrical axles 26, 27 whose axle ends 18, 19 extend with a production-conducive clearance fit in the through-openings 15 and 16.

The valve contacting element 12e (see FIG. 5b) and the joint socket element 13e (see FIG. 5c) of the finger lever 1e disclosed in FIG. 5 comprise on their cross-surfaces cylindrical projections 28e, 29e which, according to the longitudinal sectional illustration of the finger lever 1e (see FIG. 5a) extend in circular arc-shaped grooves 32, 33 of the opposing inner sides of the side walls 11e to abut against the ends of the grooves 32, 33 serving as stop surfaces 30e, 31e.

The finger lever 1f illustrated in FIG. 6 comprises a valve contacting element 12f according to FIG. 6b and a joint socket element 13f according to FIG. 6c each of these elements has a T-shaped cross-section and, correspondingly, projections 28f, 29f in shape of a right parallelepiped, which extend with a clearance, in this case of approximately 0.2 mm, opposite the upper edges of the side walls 11f according to FIG. 6a (i.e. on the side turned away from the gas exchange valve) serving as stop surfaces 30f,31f.

The finger lever 1g illustrated in FIG. 7 comprises a valve contacting element 12g according to FIG. 7a and a joint socket element 13g according to FIG. 7b each of which likewise has a T-shaped cross-section and, correspondingly, projections 28g, 29g in shape of a right parallelepiped, which extend in this case with a clearance of approximately 0.2 mm, opposite the lower edges of the side walls 11g serving as stop surfaces 30g, 31g.

The finger lever 1h illustrated in FIG. 8 differs from the finger lever 1g only by the fact that the abutting surfaces 34, 35 of the projections 28h and 29h which are configured on the valve contacting element 12h and on the joint socket element 13h respectively and situated opposite the lower edges of the side walls 11h, are not flat but slightly convex in shape, as will become clear through a comparison of FIG. 7a with FIG. 8a and of FIG. 7b with FIG. 8b.

The finger lever 1i according to FIG. 9 corresponds substantially to the finger lever 1h which is supplemented here with a connecting element 36 for anti-loss retention of the joint socket 14 on the joint head of the support element 6 (see FIG. 12). The connecting element 36 illustrated in FIG. 9a and known per se, is made out of a punched and bent thin sheet metal with upwards pointing legs 37 and 38 that are snapped into longitudinal recesses 39 and 40 of a matched joint socket element 13i as shown in FIG. 9a.

The finger lever 1k disclosed in FIG. 10 comprises, as shown in FIG. 10a, a joint socket element 13k which, as compared to the joint socket element 13i, is made with a greater economy of material.

The finger lever 1l disclosed in FIG. 11 comprises a valve contacting element 12l according to FIG. 11a and a joint socket element 13l according to FIG. 11b, both of these elements being suitable for manufacturing by sintering.

REFERENCE NUMERALS

• 1 Finger lever
• 2 First lever end
• 3 Valve contacting surface
• 4 Gas exchange valve
• 5 Second lever end
• 6 Support element
• 7 Lever center
• 8 Roller axle
• 9 Roller
• 10 Cam
• 11 Side wall
• 12 Valve contacting element
• 13 Joint socket element
• 14 Joint socket
• 15 Through-opening on first lever end
• 16 Through-opening on second lever end
• 17 Through-opening at lever center
• 18 Axle end/axle stud
• 19 Axle end/axle stud
• 20 Projection on valve contacting element
• 21 Projection on joint socket element
• 22 Recess on side wall
• 23 Recess on side wall
• 24 Cross-bore in the valve contacting element
• 25 Cross-bore in the joint socket element
• 26 Axle for valve contacting element
• 27 Axle for joint socket element
• 28 Projection for rotation limitation of the valve contacting element
• 29 Projection for rotation limitation of the joint socket element
• 30 Stop surface of the side wall
• 31 Stop surface of the side wall
• 32 Groove in inner side wall on the first lever end
• 33 Groove in inner side wall on the second lever end
• 34 Abutting surface on the valve contacting element
• 35 Abutting surface on the joint socket element
• 36 Connecting element
• 37 Leg of the connecting element
• 38 Leg of the connecting element
• 39 Longitudinal recess on the joint socket element
• 40 Longitudinal recess on the joint socket element

Claims

1. A finger lever (1) for actuating a gas exchange valve (4) of an internal combustion engine, said finger lever (1) comprising a first lever end (2) on which a valve contacting surface (3) for the gas exchange valve (4) extends, and further comprising a lever center (7) in which a roller axle (8) and a roller (9) mounted on said roller axle (8) for contact of a cam (10) extends, and comprising still further a second lever end (5) on which a joint socket (14) for a pivotal mounting of said finger lever (1) on a stationary joint head arranged in the internal combustion engine extends, said finger lever (1) comprising two side walls (11) which extend spaced from each other in a longitudinal direction of the finger lever (1) and are made as separate parts while being connected to each other, on the first lever end (2), through a valve contacting element (12) retained on the side walls (11), at the lever center (7), through the roller axle (8) retained in aligned through-openings (17) of the side walls (11) and, on the second lever end (5), through a joint socket element (13) retained on the side walls (11), characterized in that the side walls (11) on the first lever end (2) and on the second lever end (5) comprise through-openings (15, 16) aligned to each other in pairs, in which through-openings (15, 16) each of the valve contacting element (12) and the joint socket element (13) is retained after the manner of a pin and bore connection by respective axle ends or axle stubs (18, 19) pointing in a transverse direction of the side walls (11).

2. A finger lever (1) according to claim 1, characterized in that the side walls (11) are made as punched parts out of a sheet metal material and the valve contacting element (12) and the joint socket element (13) are made as sintered or metal injection molded parts.

3. A finger lever (1a, 1b) according to claim 1, characterized in that the axle studs (18, 19) are configured in one piece with the valve contacting element (12a) and/or with the joint socket element (13a, 13b).

4. A finger lever (1a, 1b, 1c) according to claim 1, characterized in that the valve contacting element (12a, 12b, 12 c) and/or the joint socket element (13a, 13b, 13c) is retained secure against rotation on the side walls (11a, 11b, 11c) in transverse direction of the finger lever (1a, 1b, 1c).

5. A finger lever (1a) according to claim 4, characterized in that the through-openings (15a, 16a) on one or both of the lever ends (2, 5) are circular in shape, and that the axle ends or axle studs (18a, 19a) are cylindrical in shape, the valve contacting element (12a) and/or the joint socket element (13a) being retained secure against rotation by force locking through riveting of the axle ends or axle studs (18a, 19a) in the through-openings (15a, 16a).

6. A finger lever (1b) according to claim 4, characterized in that the through-openings (15b, 16b) on one or on both lever ends (2, 5) are non-circular in shape and that the axle ends (18b) or axle studs (19b) have a cross-sectional shape complementary to the through-openings (15b, 16b) so that the valve contacting element (12b) and/or the joint socket element (13b) are retained secure against rotation by positive engagement in the through-openings (15b, 16b).

7. A finger lever (1b) according to claim 6, characterized in that the through-openings (15b, 16b) and the axle ends (18b) or axle studs (19b) are oval in shape.

8. A finger lever (1c) according to claim 4, characterized in that the through-openings (15c, 16c) on one or on both lever ends (2, 5) are circular in shape and that the axle ends (18c, 19c) or axle studs are cylindrical in shape, the valve contacting element (12c) and/or the joint socket element (13c) comprise projections (20c, 21c) that extend in transverse direction of the side walls (11c) and engage into complementary recesses (22, 23) of the side walls (11c) so that the valve contacting element (12c) and/or the joint socket element (13c) are retained secure against rotation by positive engagement in the through-openings (15c, 16c).

9. A finger lever (1c to 1l) according to claim 1, characterized in that the valve contacting element (12c to 12l) and/or the joint socket element (13c to 13l) comprises a cross-bore (24, 25) through which an axle (26, 27) is inserted through whose axle ends (18c, 9c) the valve contacting element (12c to 12l) and/or the joint socket element (13c to 13l) is retained in the through-openings (15, 16).

10. A finger lever (1d to 1l) according to claim 9, characterized in that the valve contacting element (12d to 12l) and/or the joint socket element (13d to 13l) is retained on the side walls (11d to 11l) for rotation in transverse direction of the finger lever (1d to 1l).

11. A finger lever (1e to 1l) according to claim 10, characterized in that the valve contacting element (12e to 12l) and/or the joint socket element (13e to 13l) comprises projections (28, 29) that extend in transverse direction of the side walls (11e to 11l) and, to limit a rotation of the valve contacting element (12e to 12l) and/or of the joint socket element (13e to 13l), abut against stop surfaces (30, 31) of the side walls (11e to 11l).

12. A finger lever (1e) according to claim 11, characterized in that the projections (28e, 29e) are cylindrical in shape and extend in circular arc-shaped grooves (32, 33) of inner sides of the side walls (11e) facing each other, said grooves (32, 33) serving as stop surfaces (30e, 31e).

13. A finger lever (1f to 1l) according to claim 11, characterized in that the projections (28, 29) are made substantially in shape of a right parallelepiped and extend with clearance relative to opposing upper edges or lower edges of the side walls (11f to 11l) serving as stop surfaces (30, 31).

14. A finger lever (1f, 1h to 1l)) according to claim 13, characterized in that the abutting surfaces (34, 35) of the projections (28, 29) turned towards the upper edges or lower edges of the side walls (11f, 1h to 1l) have a slightly convex shape.

15. A finger lever (1i to 1l) according to claim 1, characterized in that a connecting element (36) made of flat material is mounted on the joint socket element (13i to 12l) for achieving an anti-loss retention of the joint socket (14) on the joint head.