Fuel pump

Abstract

A fuel pump includes a plurality of magnets that are disposed circumferentially on an inner surface of a housing of the fuel pump and alternately form different magnetic poles, an armature rotatably disposed inside the permanent magnets, a rotating member disposed on a rotary shaft that is connected with the armature and rotates with the rotary shaft by rotating the armature, a pump casing that accommodates and rotatably supports the rotating member, and a discharge port disposed on the pump casing so as to discharge fuel pressurized by the rotation of the rotating member. According to the present invention, an imaginary line extending straight through the discharge port in a flow direction of fuel discharging from the discharge port extends into a circumferential gap between two of said permanent magnets.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application is based upon, claims priority from and incorporates herein by reference the contents of Japanese Patent Applications No. 2006-272933 filed on Oct. 4, 2006.

FIELD OF THE INVENTION

The present invention relates to a fuel pump that supplies fuel suctioned from a fuel tank to an internal combustion engine.

BACKGROUND OF THE INVENTION

Fuel pumps that include a motor section and a pump section that is driven by the motor section, pumps up and pressurizes fuel for supplying the fuel from a fuel tank to an internal combustion engine through the inside of the motor section are well-known, as disclosed in JP-A-5-187382, JP-A-6-167291 and JP-A-6-229390. The motor section includes a plurality of permanent magnets that are positioned about a circumference of its housing so as to form a plurality of magnetic poles in a circumferential direction, an armature disposed inside the permanent magnets, etc.

As shown in FIG. 4, fuel pressurized in the pump section is discharged toward the permanent magnets 310 from a discharge port 302 formed in a pump casing 300 of the pump section, which accommodates a rotating member. Fuel discharged from the discharge port 302 flows through the inside of the motor section. Specifically, the discharged fuel flows through a gap between an outer surface of the armature and an inner surface of the permanent magnets (not shown), and a gap 312 between the adjacent permanent magnets 310 arranged in the circumferential direction of the inside of the motor section.

However, in the fuel pump, fuel discharged from the discharge port 302 of the pump casing 300 cannot flow smoothly into a gap 312 between the adjacent permanent magnets 310 because the fuel collides with an edge surface 314 of the permanent magnets 310, as shown in FIG. 4. This increases the pressure loss of the fuel flow.

SUMMARY OF THE INVENTION

In view of the foregoing problems, it is an object of the present invention to provide a fuel pump, in which the fuel pressurized in the pump section can flow smoothly into the gap between the adjacent permanent magnets of the motor section.

According to the present invention, a fuel pump includes a plurality of magnets that are disposed circumferentially on an inner surface of a housing of the fuel pump and alternately form different magnetic poles, an armature rotatably disposed inside the permanent magnets, a rotating member disposed on a rotary shaft that is connected with the armature and rotates with the rotary shaft by rotating the armature, a pump casing that accommodates and rotatably supports the rotating member, and a discharge port disposed on the pump casing so as to discharge fuel pressurized by the rotation of the rotating member. According to the present invention, an imaginary line extending straight through the discharge port in a flow direction of fuel discharging from the discharge port extends into a circumferential gap between two of said permanent magnets. In a first embodiment, an imaginary line extending in a flow direction of fuel discharging from the discharge port along an inner inclined surface of the discharge port extends between upstream ends of adjacent permanent magnets. In a second embodiment, an edge between the inner inclined surface of the discharge port and an outer surface of the pump casing is below a gap formed between two permanent magnets.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings. In the drawings:

FIG. 1 is a longitudinal cross-sectional view showing a fuel pump according to the first embodiment of the present invention;

FIG. 2A is a plan view showing a pump casing of the fuel pump shown in FIG. 1;

FIG. 2B is an enlarged cross-sectional view of a portion around an discharge port of the pump casing of the fuel pump shown in FIG. 1;

FIG. 3A is a plan view showing a pump casing of the fuel pump according to the second embodiment of the present invention;

FIG. 3B is an enlarged cross-sectional view of a portion around an discharge port of the pump casing of the fuel pump according to the second embodiment of the present invention;

FIG. 4A is a plan view showing a pump casing of a conventional fuel pump; and

FIG. 4B is an enlarged cross-sectional view of a portion around an discharge port of the pump casing of the conventional fuel pump.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

A fuel pump 10 according to the first embodiment will be described with reference to FIGS. 1 and 2.

The fuel pump 10 is an in-tank type turbine pump that is usually accommodated in a fuel tank (not shown) of a vehicle, such as two-wheel vehicle or four-wheel vehicle. The fuel pump 10 pressurizes fuel suctioned from the fuel tank, and supplies the pressurized fuel to an internal combustion engine.

The fuel pump 10 includes a pump section 12 and a motor section 13 that drives the pump section 12. The pump section 12 and the motor section 13 are housed in a housing 14. A casing cover 20 is caulked at the outer periphery thereof by the edge portion of the housing 14. With this structure, the pump casing 22 can be held between the casing cover 20 and a step 15 formed on the inner surface of the housing 14.

The pump section 12 is a turbine pump that includes the casing cover 20, a pump casing 22 and an impeller 30. The pump section 12 is arranged on the upstream side of the motor section 13 in the axial direction of the rotation axis of an armature 50 of the motor section 13. The impeller 30 (as a rotating member) is assembled on a rotary shaft 56 (as a rotation axis). The casing cover 20 and the pump casing 22 form a casing member, which accommodates and rotatably supports the impeller 30. The casing cover 20 has a fuel suction port 200, through which fuel is pumped up from the fuel tank into pump passages 202a,202b. The fuel passages 202a,202b are formed as C-shaped grooves along an outer edge of the impeller 30 in the casing cover 20 and the pump casing 22, respectively. The impeller 30 is disc-shaped, and a plurality of blades and blade ditches are alternately formed at the outer edge of the impeller 30. When the impeller 30 rotates with the rotary shaft 56 by rotating the armature 50 of the motor section 13, fuel flows out of the blade ditches of the impeller 30 toward the inner surface of the fuel passage 202a,202b. The fuel returns to the blade ditches from the inner surface of the fuel passage 202a,202b and flows out of the blade ditches of the impeller 30 again. After the fuel repeats the above flowing out and returning, the fuel is pressurized and forms a circulating flow in the fuel passage 202a,202b. Thus, fuel can be pumped up through the fuel suction port 200 and be pressurized in the fuel passage 202a,202b by the rotating impeller 30. Fuel pressurized in the fuel passage 202a,202b flows together in a discharge port 204 of the pump casing 22, and is discharged into the motor section 13 through the discharge port 204.

The motor section 13 includes permanent magnets 40a,40b, the armature 50, a commutator 60, a brush 80 and a choke coil 82. Permanent magnets 40a,40b have arc-shaped cross sections, respectively, and are fixed on the inner surface of the housing 14 with adhesive at equal intervals, so that S-pole and N-pole are positioned. As shown in FIG.2A, a circumferential angle θ of the permanent magnets 40a,40b is equal to or less than 150 degrees and more than 120 degrees. Accordingly, gaps 208a,208b are formed between edge faces of the permanent magnets 40a,40b that are disposed in the circumferential direction of the housing 14. A plate spring 42 is disposed in the gap 208b. On the other hand, a support member 72 of a bearing holder 70, which extends toward the pump section 12, is disposed in the gap 208a. The plate spring 42 and the support member 72 can prevent permanent magnets 40a,40b from shifting in the circumferential direction. In this embodiment, a distance d (shown in FIG. 2B) between an edge face 41 of the permanent magnets 40a,40b which face the pump casing 22 and an opening 206 of the discharge port 204 which faces the permanent magnet 40a is equal to or less than 10 mm.

The armature 50 is rotatably positioned inside two permanent magnets 40a,40b so that a clearance space is formed as a fuel passage 210 between inner surfaces of the permanent magnets 40a,40b and an outer surface of the armature 50. The armature 50 has a core 52 that is made of the laminated magnetic steel sheets, and coils wound around the core 52. The core 52 has a plurality of magnetic pole cores 54 which are arranged in the rotation direction of the armature 50. The coils are wound around each of the magnetic pole cores 54. Moreover, the rotary shaft 56 is inserted into a core 52. A metal bearing 24 rotatably supports one end of the rotary shaft 56, and a metal bearing 26 rotatably supports the other end of the rotary shaft 56. The bearing 24 is disposed in the pump casing 22, and the bearing 26 is disposed in the bearing holder 70.

The commutator 60 is formed as a plane disk-shape, and is disposed on the opposite side of the impeller 30 with respect to the armature 50. The commutator 60 has a plurality of segments 62 which are arranged in the rotation direction of the armature 50. The segments 62 are made of carbon, for example, and electrically connected to the coils of the armature 50. The adjacent segments 62 are separated by a gap or an insulating resin. This prevents the adjacent segments 62 from connecting electrically. With this structure, when the armature rotates, each segment 62 will make contact with the brush 80 sequentially, and drive current to be supplied to the coils of the armature 50 will be commutated. A terminal 64 is inserted in an end cover 74. Drive current is supplied to the coils of the armature 50 from an external power source through the terminal 64, the brush 80, and the commutator 60. The end cover 74 is caulked at the outer periphery thereof by the edge portion of the housing 14, as shown in FIG. 1. With this structure, the bearing holder 70 can be held between the end cover 74 and a step 16 formed on the inner surface of the housing 14. A discharge port 212 is disposed on the end cover 74, and accommodates a check valve 90 for preventing back-flow of fuel discharged from the discharge port 212. The bearing holder 70 and the end cover 74 are made of resin.

With the above-described structure, fuel discharged from the discharge port 204 of the pump section 12 will be supplied to the internal combustion engine through the gap 208a,208b, the fuel passage 210 and the discharge port 212. Thus, fuel pressurized in the pump section 12 flows in the motor section 13. Accordingly, the fuel flowing in the motor section 13 cools the motor section 13, and improves the lubricity of a slide member in the motor section 13.

Especially, with the structure of the fuel pump described in the present invention, an imaginary line extending straight through the discharge port in a flow direction of fuel discharging from the discharge port extends into a circumferential gap between two of said permanent magnets. Accordingly, fuel discharging from the discharge port 204 flows straight into the gap 208b between two permanent magnets 40a,40b.

In a first embodiment, as shown in FIG. 2B, an inner inclined surface 205 is formed in the discharge port 204 on the front side of the rotation direction of the impeller 30. An imaginary line 220 extending in a flow direction of fuel discharging from the discharge port 204 along the inner inclined surface 205 extends between the upstream ends of the adjacent permanent magnets 40a,40b. Thus, the imaginary line 220 is inclined to the outer surface 23 of the pump casing 22, which faces the motor section 13. In this embodiment, an angle α between the imaginary line 220 and the outer surface 23 of the pump casing 22 is equal to or less than 60 degrees and more than 10 degrees. The discharge port 204 is disposed in the vicinity of the gap 208b in which the plate spring 42 is disposed. The plate spring 42 is made of thin plate so as to reduce the pressure loss of the fuel flowing through the gap 208b.

In the first embodiment, described above, the imaginary line 220 extends in a flow direction of fuel discharging from the discharge port 204 along the inner inclined surface 205 that is formed in the discharge port 204 on the front side of the rotation direction of the impeller 30. Moreover, the imaginary line 220 extends between the upstream ends of the adjacent permanent magnets 40a,40b. With this structure, pressurized fuel that is discharged from the discharge port 204 flows smoothly into the gap 208b, which is closer to the discharge port 204. As a result, pressure loss of the fuel flowing into the gaps 208a,208b is reduced. At the same time, a noise generated due to fuel flowing from the pump section 12 into the motor section 13 is reduced.

In the first embodiment, described above, the angle e of circumference of the permanent magnets 40a,40b is equal to or less than 150 degrees and more than 120 degrees. Thus, larger gaps 208a,208b are formed. Accordingly, the pressure loss of the fuel flowing into the gaps 208a,208b is reduced.

In the first embodiment, described above, the distance d between the edge face 41 of the permanent magnets which face the pump casing 22 and the opening 206 of the discharge port 204 which faces the permanent magnet 40a is equal to or less than 10 mm. Accordingly, the pump section 12 can be closer to the motor section 13. Therefore, the fuel pump 10 can be downsized.

In the first embodiment, described above, the angle α between the imaginary line 220 and the outer surface 23 of the pump casing 22 is equal to or less than 60 degrees and more than 10 degrees. With this structure, the direction of fuel flowing in the rotation direction of the impeller 30 through the fuel passage 202a,202b is not changed significantly. Therefore, fuel will be discharged smoothly along the inner inclined surface 205 that is formed in the discharge port 204 on the front side of the rotation direction of the impeller 30.

Second Embodiment

A fuel pump according to the second embodiment will be described with reference to FIG. 3. The same or similar reference numerals hereafter indicate the same or substantially the same part, portion or component as the first embodiment.

As shown in FIG. 3, an edge 207 between the inner inclined surface 205 of the opening 206 and the outer surface 23 of the pump casing 22 is axially below the gap 208b formed between permanent magnets 40a,40b. With this structure, fuel discharged from the discharge port 204 flows smoothly into the gap 208b. Therefore, pressure loss of the fuel flowing into the gap 208a,208b is reduced. At the same time, noise generated due to fuel flowing from the pump section 12 into the motor section 13 is reduced.

The range of the circumferential angle θ of the permanent magnets 40a,40b, the distance d between the edge face 41 and the opening 206, and the angle α between the imaginary line 220 and the outer surface 23 in the second embodiment are the same as described in the first embodiment.

(Variation)

In the above embodiments, the circumferential angle θ of the permanent magnets 40a,40b is equal to or less than 150 degrees and more than 120 degrees. However, the angle θ may be defined outside of the above range.

In the above embodiments, the distance d between the edge face 41 and the opening 206 is equal to or less than 10 mm. However, the distance d may be defined outside of the above range.

In the above embodiments, the angle α between the imaginary line 220 and the outer surface 23 is equal to or less than 60 degrees and more than 10 degrees. However, the angle α may be defined outside of the above range.

In the above embodiments, two permanent magnets are provided. However, four permanent magnets, or the even more than four permanent magnets, may be provided.

Various other modifications and alternations may be made to the above embodiments without departing from the spirit of the present invention. Thus, while the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A fuel pump for supplying fuel suctioned from a fuel tank to an internal combustion engine, comprising:

a housing;

a plurality of magnets that are disposed circumferentially on an inner surface of said housing, and forming different magnetic poles alternately;

an armature disposed rotatably inside the permanent magnets;

a rotating member disposed on a rotary shaft that is connected with the armature and rotates with the rotary shaft by rotating the armature;

a pump casing that accommodates and rotatably supports the rotating member; and

a discharge port disposed in the pump casing to discharge fuel pressurized by the rotation of the rotating member;

wherein:

an imaginary line extending straight through the discharge port in a flow direction of fuel discharging from the discharge port extends into a circumferential gap between two of said permanent magnets.

2. The fuel pump according to claim 1, wherein:

said imaginary line extends along an inner inclined surface of the discharge port.

3. The fuel pump according to claim 1, wherein:

an edge between an inner inclined surface of the discharge port and an outer surface of the pump casing is disposed axially below said circumferential gap.

4. A fuel pump for supplying fuel suctioned from a fuel tank to an internal combustion engine, comprising:

a housing;

a plurality of magnets that are disposed circumferentially on an inner surface of said housing, and forming different magnetic poles alternately;

an armature disposed rotatably inside the permanent magnets;

a rotating member disposed on a rotary shaft that is connected with the armature and rotates with the rotary shaft by rotating the armature;

a pump casing that accommodates and rotatably supports the rotating member; and

a discharge port disposed in the pump casing to discharge fuel pressurized by the rotation of the rotating member;

wherein:

an imaginary line extending in a flow direction of fuel discharging from the discharge port along an inner inclined surface of the discharge port extends between upstream ends of adjacent permanent magnets.

5. The fuel pump according to claim 4, wherein:

a distance d between an edge face of the permanent magnets which face the pump casing and an opening of the discharge port which faces the permanent magnet is equal to or less than 10 mm.

6. The fuel pump according to claim 4, wherein:

there are two permanent magnets.

7. The fuel pump according to claim 6, wherein:

a circumferential angle θ of the permanent magnets is equal to or less than 150 degrees and more than 120 degrees.

8. The fuel pump according to claim 4, wherein:

an angle between the imaginary line and the outer surface of the pump casing is equal to or less than 60 degrees and more than 10 degrees.

9. A fuel pump for supplying fuel suctioned from a fuel tank to an internal combustion engine comprising:

a housing;

a plurality of magnets that are disposed circumferentially on an inner surface of said housing, and forming different magnetic poles alternately;

an armature disposed rotatably inside the permanent magnets;

a rotating member disposed on a rotary shaft that is connected with the armature and rotates with the rotary shaft by rotating the armature;

a pump casing that accommodates and rotatably supports the rotating member; and

a discharge port disposed on the pump casing to discharge fuel pressurized by the rotation of the rotating member;

wherein:

an edge between an inner inclined surface of the discharge port and an outer surface of the pump casing being disposed axially below a circumferential gap formed between two of said permanent magnets.

10. The fuel pump according to claim 9, wherein:

a distance d between an edge face of the permanent magnets which face the pump casing and an opening of the discharge port which faces the permanent magnet is equal to or less than 10 mm.

11. The fuel pump according to claim 9, wherein:

there are two permanent magnets.

12. The fuel pump according to claim 11, wherein:

a circumferential angle θ of the permanent magnets is equal to or less than 150 degrees and more than 120 degrees.