Fuel pump having bearing member

Abstract

A fuel pump includes a pump device for pumping fuel. The fuel pump further includes a motor device that has a commutator and an armature including a shaft. The commutator commutating electricity supplied to the armature for rotating the armature to drive the pump device. The fuel pump further includes a brush supplying electricity to the armature by making contact with the commutator. The fuel pump further includes a bearing member supporting the shaft. The fuel pump further includes a holder including a partition wall for supporting the bearing member. The partition wall electrically insulates the bearing member from the brush. The bearing member has a first bearing end surface on a side of the commutator. The partition wall has a wall end surface on a side of the commutator. The first bearing end surface is on an opposite side of the commutator with respect to the wall end surface.

Description

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 sectional view showing a fuel pump according to a first embodiment;

FIG. 2 is a view showing a pump cover of the fuel pump being viewed from the arrow 11 in FIG. 1;

FIG. 3 is a sectional view taken along the line III-O-III in FIG. 2;

FIG. 4 is a sectional view showing a shaft and a bearing member of a fuel pump according to a second embodiment;

FIG. 5 is a sectional view showing a fuel pump according to a third embodiment;

FIG. 6 is a sectional view showing a shaft and a bearing member of the fuel pump in FIG. 5;

FIG. 7 is a graph showing an experimental result indicating a relationship between abrasion caused in a thrust support of the fuel pump and a travel distance of a vehicle; and

FIG. 8 is a sectional view showing a shaft and a bearing member of a fuel pump according to a prior art.

Claims

1. A fuel pump comprising: a pump device for pumping fuel;a motor device that includes a commutator and an armature, the armature including a shaft being a rotation center, the commutator commutating electricity supplied to the armature for rotating the armature to drive the pump device;a brush for supplying electricity to the armature by making contact with the commutator;a bearing member for rotatably supporting the shaft; anda holder that includes a partition wall for supporting the bearing member, the partition wall electrically insulating the bearing member from the brush,wherein the bearing member has a first bearing end surface on a side of the commutator,the partition wall has a wall end surface on a side of the commutator, andthe first bearing end surface is on an opposite side of the commutator with respect to the wall end surface.

2. The fuel pump according to claim 1, further comprising: a cover that is located on a side of the commutator to surround the brush and the motor device,wherein the holder is integrated with the cover.

3. The fuel pump according to claim 1, wherein the shaft has an end via which the bearing member supports the shaft,the end of the shaft has a chamfer portion that has an axial length L1 with respect to an axial direction of the shaft,the wall end surface is opposed to the commutator,the first bearing end surface is opposed to the commutator,the wall end surface is away from the first bearing end surface at a distance L2,the partition wall has a thickness L3, andthe axial length L1 of the chamfer portion is less than at least one of the distance L2 and the thickness L3.

4. The fuel pump according to claim 1, wherein the shaft has a shaft end surface on an opposite side of the commutator,the fuel pump further comprising:a thrust support member that supports the shaft end surface with respect to a thrust direction,wherein the shaft has an end via which the bearing member supports the shaft,the end of the shaft has a chamfer portion and a bar portion,the chamfer portion connects with the bar portion to define a boundary therebetween,the bearing member has a second bearing end surface on an opposite side of the commutator, andthe boundary is on an opposite side of the commutator with respect to the second bearing end surface.

5. The fuel pump according to claim 4, wherein the second bearing end surface is away from the boundary at a distance equal to or greater than 0.3 mm.

6. The fuel pump according to claim 4, wherein the thrust support member has a thickness t with respect to a thrust direction,the second bearing end surface is away from the boundary at a distance L4, andthe thickness t and the distance L4 satisfies L4≧0.3×t.

7. The fuel pump according to claim 1, wherein the bearing member is located on the side of the commutator.

8. The fuel pump according to claim 1, wherein the partition wall has an inner surface, which is in a substantially cylindrical shape, for receiving the bearing member,the shaft, the bearing member, the inner surface of the partition wall, are arranged substantially coaxially with respect to each other, andthe brush is arranged outside of the partition wall with respect to the radial direction of the shaft.

9. A fuel pump comprising: a pump device for pumping fuel;a motor device that includes an armature including a shaft, the motor device further including a commutator for commutating electricity supplied to the armature for rotating the pump device via the shaft;a brush for supplying the electricity to the armature by making contact with the commutator;a bearing member for radially supporting the shaft; anda holder that includes a partition wall for supporting the bearing member,wherein the partition wall is interposed between the brush and the bearing member with respect to a radial direction of the shaft for electrically insulating the bearing member from the brush,the bearing member has a first bearing end surface opposed to the commutator with respect to an axial direction of the shaft,the partition wall has a wall end surface opposed to the commutator with respect to the axial direction of the shaft, andthe wall end surface is interposed between the first bearing end surface and the commutator with respect to the axial direction of the shaft.

10. The fuel pump according to claim 9, wherein the partition wall has an inner surface, which is in a substantially cylindrical shape, for receiving the bearing member,the shaft, the bearing member, the inner surface of the partition wall, are arranged substantially coaxially with respect to each other, andthe brush is arranged outside of the partition wall with respect to the radial direction of the shaft.