Fluid pump having bearing hold

Abstract

A fluid pump includes a stationary part. A rotator is rotatable around the inner circumferential periphery of the stationary part. One of the stationary part and the rotator includes at least one coil that generates magnetic force between the stationary part and the rotator for rotating the rotator when being supplied with electricity. A pump portion is provided to one axial end of the rotation axis of the rotator. A cover covers the other axial end of the rotation axis of the rotator and the stationary part. The cover defines an outlet passage through which fluid is discharged from the pump portion. The cover has a bearing hole that rotatably supports the other axial end of the rotation axis. The bearing hole has a closed bottom. The cover has a communication passage that communicates the outlet passage with the bearing hole.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and incorporates herein by reference Japanese Patent Applications No. 2005-257416 filed on Sep. 6, 2005, No. 2005-302698 filed on Oct. 18, 2005, No. 2005-315974 filed on Oct. 31, 2005, No. 2005-347593 filed on Dec. 1, 2005, No. 2005-363423 filed on Dec. 16, 2005, No. 2006-154435 filed on Jun. 2, 2006, and No. 2006-171173 filed on Jun. 21, 2006.

FIELD OF THE INVENTION

The present invention relates to a fluid pump having a bearing hole.

BACKGROUND OF THE INVENTION

According to U.S. 2005/0074343 A1 (JP-A-2005-110478), the fuel pump includes the pump portion that is driven by rotative force of the motor portion for pumping fuel. In this structure, a cover surrounds the axial end of the motor portion on the opposite side of the pump portion. The motor portion includes a brushless motor. The cover has the outlet port through which fuel is discharged. The cover has the bearing that rotatably supports the rotation axis of the rotator of the motor portion.

The cover has the bearing hole accommodating the bearing. The bearing hole is blocked at the bottom thereof. In this structure, fuel accumulating in the bearing hole may be deteriorated, and the rotation axis may be corroded due to the deteriorated fuel. Furthermore, foreign matters such as debris caused by ablation in the fuel pump may accumulate in the bearing hole. Consequently, the foreign matters may be stuck in the sliding portion between the rotation axis and the bearing, for example.

SUMMARY OF THE INVENTION

In view of the foregoing and other problems, it is an object of the present invention to produce a fluid pump having a bearing hole, in which fuel and foreign matters can be restricted from accumulating.

According to one aspect of the present invention, a fluid pump includes a stationary part that has an inner circumferential periphery. The fluid pump further includes a rotator that is rotatable around the inner circumferential periphery. The rotator has a rotation axis. One of the stationary part and the rotator includes at least one coil. The at least one coil generates magnetic force between the stationary part and the rotator for rotating the rotator when being supplied with electricity. The fluid pump further includes a pump portion that is provided to one axial end of the rotation axis of the rotator. The rotator is adapted to rotating the pump portion for pumping fluid. The fluid pump further includes a cover that covers an other axial end of the rotation axis of the rotator. The cover covers the stationary part on a side of the other axial end of the rotation axis. The cover defines an outlet passage through which fluid is discharged from the pump portion. The cover has a bearing hole that rotatably supports the other axial end of the rotation axis. The bearing hole has a closed bottom. The cover has a communication passage that communicates the outlet passage with the bearing hole.

Alternatively, the bearing hole substantially may axially extend to a closed axial end in the cover. The closed axial end may block the bearing hole with respect to an axial direction of the bearing hole.

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 made with reference to the accompanying drawings. In the drawings:

FIG. 1 is a longitudinal partially sectional view showing a fuel pump according to a first embodiment;

FIG. 2 is a sectional view taken along the line II-II in FIG. 1;

FIG. 3 is a sectional view taken along the line III-III in FIG. 1;

FIG. 4 is a schematic sectional view showing an end cover of a fuel pump according to a second embodiment;

FIG. 5 is a schematic sectional view showing an end cover of a fuel pump according to a third embodiment; and

FIG. 6 is a sectional view showing a fuel pump according to a fourth embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

First Embodiment

As shown in FIG. 1, a fuel pump 10 of this embodiment is an in-tank turbine pump, for example. The fuel pump 10 is provided in a fuel tank of a motorcycle with an engine size of 150 cc, for example.

The fuel pump 10 includes a pump portion 12 and a motor portion 13. The motor portion 13 rotates the pump portion 12. The housing 14 serves as a housing. The housing 14 accommodates both the pump portion 12 and the motor portion 13. A pump case 20 and an end cover 50 are fixed by crimping axially both ends of the housing 14. The end cover 50 serves as a cover. The thickness of a portion of the housing 14 covering the outer circumferential periphery of a stator core 30 in the motor portion 13 is less than the thickness of a portion defining a step 15 in the pump portion 12. The stator core 30 may serve as a stationary part. The housing 14 is not necessary for defining a magnetic circuit. In this structure, the thickness of the housing 14 surrounding the outer circumferential periphery of the stator core 30 can be reduced, so that the outer diameter of the motor portion 13 can be reduced.

The pump portion 12 serves as a turbine pump. The pump portion 12 includes pump cases 20, 22, and an impeller 24. The pump case 22 is abutted axially onto the step 15 of the housing 14, so that the pump case 22 is axially aligned. A bearing 26 is press-inserted into the center of the pump case 22. The pump case 20 is fixed by crimping one end of the housing 14. Axial force is caused by the crimping, thereby producing pressure for axially pressing the pump case 22 and the pump case 20 respectively onto the step 15 and the pump case 22, so that fuel is sealed.

The pump cases 20, 22 rotatably accommodates the impeller 24 as a rotor member. The pump cases 20, 22 and the impeller 24 define pump passages 202 in substantially C-shapes thereamong. Fuel is drawn through an inlet port 200 provided to the pump case 20, and is pressurized through the pump passages 202 by rotation of the impeller 24, thereby being press-fed toward the motor portion 13. The fuel press-fed toward the motor portion 13 is supplied toward an engine through an outlet port 208 after passing through a fuel passage 204 and an outlet passage 206. The fuel passage 204 is defined between the stator core 30 and a rotator 70. The outlet port 208 communicates the outlet passage 206 with the outside of the end cover 50. The outlet port 208 is eccentric with respect to a bearing hole (bearing) 52.

The motor portion 13 is a brushless motor that includes the stator core 30, bobbins 40, coils 42, and the rotator 70. The stator core 30 is constructed of six cores 32 that are circumferentially arranged. An unillustrated control apparatus controls current supplied to the coils 42 in accordance with a rotational position of the rotator 70, thereby switching magnetic poles defined in the inner circumferential peripheries of the cores 32. The inner circumferential peripheries of the cores 32 are opposed to the outer circumferential periphery of the rotator 70.

As shown in FIG. 2, each of the cores 32 has a tooth 33 and an outer circumferential periphery 34. Each core 32 is integrally formed by crimping magnetic steel plates, which are stacked with respect to the axial direction of the shaft 72. The shaft 72 serves as a rotation axis. The tooth 33 protrudes from the center of the outer circumferential periphery 34 inwardly toward the rotator 70. Each of the bobbins 40 formed of electrically insulative resin engages with each of the cores 32. Six of the outer circumferential peripheries 34 define a toroidal core. Each of the outer circumferential peripheries 34 is in a substantially arc shape that has a circumferentially substantially regular width.

Each of the coils 42 is constructed by concentrically winding a wire around the outer periphery of the bobbin 40 of each of the cores 32 in a condition where each of the six cores 32 is a single component before being circumferentially arranged to be the stator core 30. Each of the coils 42 electrically connects with each of terminals 44, 45 on the side of the end cover 50 depicted in FIG. 1. The terminals 44 are taken from junctions electrically connecting with the coils 42 to the outside of the end cover 50, thereby being exposed from the end cover 50. The terminals 44 connect with a connector. The terminals 45 are not exposed from the end cover 50. The terminals 45 electrically connect the coils 42 with each other.

The bearing hole 52 is defined in the center of the end cover 50. The terminals 44, 45 are inserted molded in the end cover 50 at locations spaced from the bearing hole 52 by substantially constant distances for securing distances from the housing 14 in order to secure insulation from the metallic housing 14 located on the radially outer side. The terminals 44 are bent such that the terminals 44 are taken from the inside of the end cover 50 to the outside at a location in which the terminals 44 are exposed on the radially outer side with respect to the locations of the terminals 44 inside the end cover 50.

The terminals 44 are bent such that the terminals 44 are exposed from the radially outer side with respect to the location of the terminals 44 inside the end cover 50. The outlet port 208 is eccentric with respect to the bearing hole 52, so that the outlet port 208 is spaced from the center of the end cover 50. Therefore, the terminals 44, which are exposed from the surface of the end cover 50, can be possibly spaced from the outlet port 208.

Here, the bearing hole 52 may be coaxial with respect to the outlet port 208 of the outlet passage 206 opening in the surface of the end cover 50. That is, the outlet port 208 may be defined in the center of the end cover 50. In this structure, when components such as the terminals 44 are provided to the surface of the end cover 50 other than the outlet port 208, alternatively when the components are taken from the inside of the end cover 50 to a portion other than the outlet port 208, the distance between the terminals 44 and the outlet port 208 may be less than the radius of the end cover 50, even spaced at most. Accordingly, the distance between the outlet port 208 and the other component is small, particularly in a small fuel pump. Consequently, for example, a space for connecting the terminals 44 with a connector or a space for connecting the outlet port 208 with a pipe or the like becomes small. Accordingly, manufacturing work for connecting the fuel pump with the other component becomes difficult.

By contrast, in this embodiment, the outlet port 208 of the outlet passage 206 is eccentric with respect to the bearing hole 52, so that the outlet port 208 is spaced from the center of the end cover 50. Therefore, components such as the terminals 44 arranged in the surface of the end cover 50 can be possibly spaced from the outlet port 208. Alternatively, when components are taken from the inside of the end cover 50 to a location other than the outlet port 208, the location can be possibly spaced from the outlet port 208.

Therefore, the terminals 44, which are exposed from the surface of the end cover 50, can be possibly spaced from the outlet port 208. Thus, connection of the terminals 44 with the connectors can be facilitated, and connection of the outlet port 208 with a pipe or the like can be also facilitated.

The structure of this embodiment may be effective to a small fuel pump, in particular.

An electrically insulative resin material 46 is charged between the teeth 33, which are circumferentially adjacent to each other, thereby being molded such that the electrically insulative resin material 46 covers the coils 42. The electrically insulative resin material 46 is integrally molded with the end cover 50, which covers the end of the stator core 30 on the opposite side of the pump portion 12 with respect to the stator core 30. The electrically insulative resin material 46 may be poly phenylene sulfide (PPS) or poly acetal (POM). The end cover 50 is molded of the electrically insulative resin material 46 integrally with the bearing hole 52, which rotatably supports the shaft 72, a supporting portion of the terminals 44, and the outlet port 208. The electrically insulative resin material 46 is integrally molded with the end cover 50, so that the number of components constructing the fuel pump 10 can be reduced, and manufacturing work for assembling the fuel pump 10 can be reduced.

The end cover 50 has the bearing hole 52 in the center thereof for rotatably support the shaft 72. The bearing hole 52 directly supports the shaft 72. The bottom of the bearing hole 52 is blocked. The end cover 50 has the outlet passage 206 eccentrically with respect to the bearing hole 52. The outlet passage 206 linearly penetrates the end cover 50 substantially in the axial direction of the end cover 50. The outlet passage 206 and the bearing hole 52 directly overlap, so that the outlet passage 206 communicates with the bearing hole 52.

A slant restriction member 60 is in a substantially annular shape defining a through hole at the center thereof. The slant restriction member 60 hooks to the end of the bobbin 40 on the opposite side of the pump portion 12. The slant restriction member 60 has fitting holes to which the terminals 44, 45 fit. The electrically insulative resin material 46 is molded in a condition where the terminals 44, 45 fit to the fitting holes, so that the terminals 44, 45 can be restricted from being inclined and causing interference with peripheral components when the electrically insulative resin material 46 is molded.

As referred to FIGS. 1, 2, the rotator 70 includes the shaft 72 and a permanent magnet 74. The rotator 70 is rotatable around the inner circumferential periphery of the stator core 30. The shaft 72 is rotatably supported by the bearing 26 at one end, and is rotatably supported by the bearing hole 52 at the other end. The permanent magnet 74 is a resin magnet that is produced by mixing magnetic powder with thermoplastic resin such as polyphenylene sulfide (PPS) and shaping it to be cylindrical. The shaft 72 has a knurled outer circumferential periphery to which the permanent magnet 74 is directly formed by injection molding or the like. The permanent magnet 74 has eight magnetic poles 75 arranged with respect to the rotative direction of the rotator 70. The eight magnetic poles 75 are magnetized to define magnetic poles in the outer circumferential periphery opposed to the stator core 30. The magnetic poles are different from each other with respect to the rotative direction of the rotator 70.

The end cover 50 has the outlet port 208 that accommodates a valve member 80, a stopper 82, and a spring 84 that construct a check valve. Thus, the end cover 50 also serves as a housing of the check valve, so that the number of the components constructing the fuel pump 10 can be reduced, and manufacturing work for assembling the fuel pump 10 can be reduced.

The valve member 80 is lifted against bias force of the spring 84 when pressure of fuel pressurized in the pump portion 12 becomes equal to or greater than a predetermined pressure, so that fuel is discharged toward the engine through the outlet port 208. The valve member 80 restricts fuel, which is discharged from the fuel pump 10, from causing reverse flow.

In the first embodiment, the end cover 50 defines closed axial end. The bearing hole 52 substantially axially extends to the closed axial end in the end cover 50. The closed axial end may be located between the outlet port 208 and the bearing hole 52. The closed axial end blocks the bearing hole 52 with respect to an axial direction of the bearing hole 52.

In the first embodiment, the bearing hole 52 communicates with the outlet passage 206, so that fresh fuel passes through the bearing hole 52. Thus, the fresh fuel passes through a sliding portion between the shaft 72 and the bearing hole 52. In this structure, fuel can be restricted from being deteriorated due to accumulating between the shaft 72 and the bearing hole 52, so that the shaft 72 can be protected from corrosion due to deterioration of fuel. Thus, smooth sliding property of the bearing hole 52 relative to the shaft 72 can be maintained. Even when foreign matters such as debris caused by ablation flow into the bearing hole 52, the foreign matters immediately flow out toward the outlet passage 206, so that the foreign matters can be restricted from being stuck between the bearing hole 52 and the shaft 72. Thus, smooth sliding property of the bearing hole 52 relative to the shaft 72 can be maintained.

In the first embodiment, the outlet port 208 is eccentric with respect to the bearing hole 52. The outlet passage 206 having the outlet port 208 and the bearing hole 52 directly overlap, so that the outlet passage 206 communicates with the bearing hole 52. In this structure, the bearing hole 52 and the outlet passage 206 also serve as communication passages, and can be readily communicated with each other.

The outlet passage 206 is substantially linearly defined. Therefore, molding dies can be pulled from each other in the opposite direction after molding the end cover 50. Thus, the end cover 50 can be integrally molded of resin.

In the first embodiment, the coil 42 is constructed of the concentrated winding formed around the tooth 33 of each of the cores 32, so that an occupancy rate of the winding is enhanced compared with a structure of distributed winding, for example. Therefore, a winding space occupied by the coil 42 is reduced when the number of the winding is constant. Consequently, the motor portion 13 can be reduced, so that the fuel pump 10 can be reduced.

In this embodiment, the bearing hole 52 directly supports the shaft 72, so that the number of the components constructing the fuel pump 10 can be reduced, and manufacturing work for assembling the fuel pump 10 can be reduced.

Furthermore, the electrically insulative resin material 46 is charged between the teeth 33, which are circumferentially adjacent to each other, thereby being molded such that the electrically insulative resin material 46 covers the coils 42. Therefore, the coils 42 are protected from corrosion due to exposure to fuel, and the coils 42 can be restricted from being exposed to foreign matters, by applying a simple structure. Furthermore, the electrically insulative resin material 46 is capable of protecting the coils 42, which is constructed of the concentrated winding, from causing deformation in the winding.

Second, Third, and Fourth Embodiments

As shown in FIG. 4, in the second embodiment, an end cover 100 defines a bearing hole 102. The bearing hole 102 and the outlet passage 206 do not directly overlap. The bearing hole 102 and the outlet passage 206 are radially spaced from each other. The bottom of the bearing hole 102 is blocked. The bearing hole 102 communicates with the outlet passage 206 through a communication passage 220.

As shown in FIG. 5, in the third embodiment, an end cover 110 defines a bearing hole 112. The bearing hole 112 and the outlet port 208 of the outlet passage 206 are located substantially on the same axis 120. The bearing hole 112 and the outlet passage 206 do not directly overlap. The bearing hole 112 and the outlet passage 206 are radially spaced from each other. The bottom of the bearing hole 112 is blocked. The bearing hole 112 communicates with the outlet passage 206 through the communication passage 220.

As shown in FIG. 6, in a fuel pump 130 of the fourth embodiment, an end cover 132 defines a bearing hole 134 to which a metallic bearing 140 is press-inserted. The metallic bearing 140 is a component separate from the end cover 132, which is molded of resin. The end cover 132 is integrally molded of the electrically insulative resin material 46. The shaft 72 is rotatably supported by the bearing 26 and the bearing 140. The bearing 140 is may be formed of a material of sintered copper alloy or carbon in view of oil resistance.

The bearing hole 134 is defined in the center of the end cover 132. The bottom of the bearing hole 134 is blocked. The outlet passage 206 is eccentric with respect to the bearing hole 134. The outlet passage 206 and the bearing hole 134 directly overlap, and communicate with each other. In this structure, fresh fuel passes through the bearing hole 134, so that the fresh fuel passes through a sliding portion between the shaft 72 and the bearing 140. Thus, fuel can be restricted from being deteriorated due to accumulating between the shaft 72 and the bearing 140, so that the shaft 72 can be protected from corrosion due to deterioration of fuel. Thus, smooth sliding property of the bearing 140 relative to the shaft 72 can be maintained. Even when foreign matters such as debris caused by ablation flow into the bearing hole 134, the foreign matters may immediately flow out toward the outlet passage 206, so that the foreign matters can be restricted from being stuck between the bearing 140 and the shaft 72. Thus, smooth sliding property of the bearing 140 relative to the shaft 72 can be maintained.

Other Embodiment

In the above embodiments, the brushless motor is applied to the pump portion of the fuel pump for generating force driving the pump portion of the fuel pump. The brushless motor may not cause a loss arising in a brush motor due to slide resistance between a commutator and a brush, electric resistance between the commutator and the brush, and fluid resistance applied to a groove, which divides the commutator into segments. Consequently, the blushless motor is higher than a brush motor in motor efficiency, so that the fuel pump is enhanced in efficiency. The efficiency of the fuel pump is a ratio of an amount of work produced by the fuel pump, i.e., (fuel discharge pressure)×(fuel discharge amount) relative to electricity supplied to the fuel pump. When the amount of work is constant, as the efficiency of the fuel pump increases, a motor portion is reduced in size by applying a brushless motor compared with applying a motor (brush motor) with a brush, so that the fuel pump can be downsized. Thus, the fuel pump downsized by applying the brushless motor is preferable, in particular, for a motor cycle.

However, alternatively, a brush motor may be applied to the pump portion. Even when a brush motor is applied, fuel and foreign matters can be restricted from accumulating in the bearing hole by communicating the bearing hole, which is defined in the end cover and blocked at the bottom thereof, with the outlet passage. Thus, smooth sliding property of the bearing hole relative to the shaft can be maintained.

The end cover may be integrally formed by welding multiple resin members, instead of integrally molding the end cover of resin. When the end cover is integrally formed with a redundant opening, the redundant opening may be closed using a sealing plug. The end cover may be integrally formed of a material other than resin. That is, the end cover may be formed of metal, for example.

In the above multiple embodiments, the teeth, which are circumferentially arranged to construct the stator core, are separate components. Alternatively, the teeth may be integrally formed such that the teeth are circumferentially arranged.

In the above multiple embodiments, the pump portion 12 is constructed of the turbine pump including the impeller 24. Alternatively, the pump portion may be constructed of a pump having another structure such as a gear pump.

The above structures of the embodiments can be combined as appropriate.

In the above embodiments, the structures of the shaft, the bearing hole, and the end cover are applied to fuel pumps. However, the above structures are not limited to the application of the fuel pumps. The above structures can be applied to any other fluid pumps.

Various modifications and alternations may be diversely made to the above embodiments without departing from the spirit of the present invention.

Claims

1. A fluid pump comprising: a stationary part that has an inner circumferential periphery; a rotator that is rotatable around the inner circumferential periphery, the rotator having a rotation axis, wherein one of the stationary part and the rotator includes at least one coil, the at least one coil generates magnetic force between the stationary part and the rotator for rotating the rotator when being supplied with electricity, the fluid pump further comprising: a pump portion that is provided to one axial end of the rotation axis of the rotator, the rotator being adapted to rotating the pump portion for pumping fluid; and a cover that covers an other axial end of the rotation axis of the rotator, the cover covering the stationary part on a side of the other axial end of the rotation axis, the cover defining an outlet passage through which fluid is discharged from the pump portion, wherein the cover has a bearing hole that rotatably supports the other axial end of the rotation axis, the bearing hole has a closed bottom, and the cover has a communication passage that communicates the outlet passage with the bearing hole.

2. The fluid pump according to claim 1, wherein the at least one coil includes a plurality of coils, the stationary part includes a plurality of teeth, which are circumferentially arranged, each of the plurality of coils is formed by concentrically winding a wire around an outer circumferential periphery of each of the plurality of teeth, the plurality of coils circumferentially generates magnetic poles in inner circumferential peripheries of the plurality of teeth when being supplied with electricity, the magnetic poles are switched by controlling electricity supplied to the plurality of coils, the rotator has an outer circumferential periphery that is opposed to the inner circumferential peripheries of the plurality of teeth, and the outer circumferential periphery of the rotator defines magnetic poles different from each other with respect to a rotative direction of the rotator.

3. The fluid pump according to claim 1, wherein the cover is formed of resin, the cover directly supports the rotation axis, and the rotation axis is rotatable with respect to the cover.

4. The fluid pump according to claim 1, further comprising: a metallic bearing that is a component separate from the cover, wherein the cover is formed of resin, the metallic bearing is press-inserted into the bearing hole, and the metallic bearing rotatably supports the rotation axis.

5. The fluid pump according to claim 1, wherein the cover is integrally formed of resin.

6. The fluid pump according to claim 1, wherein the outlet passage has an outlet port that is eccentric with respect to the bearing hole.

7. The fluid pump according to claim 6, wherein the bearing hole and the outlet passage overlap, and the bearing hole communicates with the outlet passage.

8. The fluid pump according to claim 1, wherein the bearing hole substantially axially extends to an closed axial end in the cover, and the closed axial end blocks the bearing hole with respect to an axial direction of the bearing hole.

9. A fluid pump comprising: a stationary part that has an inner circumferential periphery; a rotator that is rotatable around the inner circumferential periphery, the rotator having a rotation axis, wherein one of the stationary part and the rotator includes at least one coil, the at least one coil generates magnetic force between the stationary part and the rotator for rotating the rotator when being supplied with electricity, the fluid pump further comprising: a pump portion that is provided to one axial end of the rotation axis of the rotator, the rotator being adapted to rotating the pump portion for pumping fluid; and a cover that covers an other axial end of the rotation axis of the rotator, the cover covering the stationary part on a side of the other axial end of the rotation axis, the cover defining an outlet passage through which fluid is discharged from the pump portion, wherein the cover has a bearing hole that rotatably supports the other axial end of the rotation axis, the bearing hole substantially axially extends to a closed axial end in the cover, the closed axial end blocks the bearing hole with respect to an axial direction of the bearing hole, and the cover has a communication passage that communicates the outlet passage with the bearing hole.

10. The fluid pump according to claim 9, wherein the communication passage is located on a side of the bearing hole with respect to the closed axial end.