JP2008220026A - Fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a fuel pump wherein, when a ball plug is press fit into a guide hole in a cover body, an end of a coil spring can be prevented from biting into the edge of the guide hole. <P>SOLUTION: The fuel pump has the ball plug 17B that is press-fit into the guide hole 9B in the cover body 9 and supports the coil spring 17A. The winding diameter of the first turn 17a of the coil spring 17A is made smaller than the winding diameter of the normal portion 17c, and the position of the cross-sectional center of the element wire in the first turn 17a is set between the straight line, connecting the cross-sectional center of the element wire in the second turn 17b and the center of the ball plug 17B and the outer circumferential surface of the coil spring 17A. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel pump.

  Conventionally, various fuel pumps have been proposed, and Patent Document 1 discloses a fuel pump driven by an electric motor as an example.

The fuel pump disclosed in Patent Document 1 is provided with a power supply brush slidably contacting the rotor of the electric motor in the guide hole of the cover body and urged toward the commutator by a coil spring. At the time of assembly, a coil spring is inserted into the guide hole of the cover body, and then a ball plug is press-fitted into the end portion of the guide hole, whereby the coil spring is supported by the ball plug.
JP 2004-324612 A

  However, in the above-described prior art, when the ball plug 103 is press-fitted into the guide hole 102 of the cover body 101 when the fuel pump is assembled, as shown in FIG. 7, the spherical surface of the ball plug 103 is the end 104 a of the coil spring 104. , The winding diameter of the end 104a is expanded, and the end 104a is caught on the edge of the guide hole 102 as shown in FIG. 7B. Finally, (c) in FIG. ), There is a problem that when the ball plug 103 is press-fitted into the guide hole 102, the end 104a is bitten.

  On the other hand, in order to prevent such a problem, the speed of press-fitting the ball plug 103 into the guide hole 102 of the cover body 101 can be slowed to suppress the expansion of the winding diameter of the end 104a of the coil spring 104 to some extent. In this case, the time required for assembling the fuel pump becomes long, so there is a problem that the production capacity is lowered and the manufacturing cost is increased.

  Therefore, an object of the present invention is to obtain a fuel pump capable of suppressing the end of a coil spring from biting into the edge of a guide hole when a ball plug is press-fitted into the guide hole of the cover body.

  In order to achieve the above object, according to the first aspect of the present invention, a cylindrical casing, a pump portion provided in the casing, an electric motor for driving the pump portion, and a rotor of the electric motor A brush that slidably contacts the rotor and supplies power to the coil of the rotor, a cover body that accommodates the brush and the electric motor, a guide hole that is provided in the cover body and accommodates the brush, and the brush that extends in the rotor direction In a fuel pump that includes a coil spring that is biased toward the valve and a ball plug that is press-fitted into the guide hole to close the coil spring, and the coil spring supports the coil spring, the winding diameter of the end of the coil spring on the ball plug side Is smaller than the winding diameter of the general part of the coil spring.

In the second aspect of the present invention, the winding diameter of the coil spring and D _1, the diameter of the ball plug and D _2, the diameter of the guide hole and D _3, the wire diameter of the coil spring and d When the winding diameter of the first winding on the ball plug side of the coil spring is r ₁ and the winding diameter of the second winding is r ₂ , (r ₂ −r ₁ ) / 2 <d × (2D ₁ -D ₃ + d) / (D ₂ + 3d) is configured to hold.

  In the invention of claim 3, a cylindrical casing, a pump portion provided in the casing, an electric motor for driving the pump portion, and a rotor of the electric motor in sliding contact with the rotor. A brush for supplying power to the coil; a cover body for housing the brush and the electric motor; a guide hole provided in the cover body for housing the brush; a coil spring for biasing the brush toward the rotor; And a ball plug that is press-fitted into the guide hole to close the coil spring. The fuel pump supports the coil spring by the ball plug. It is characterized by being adhered.

  According to the first aspect of the present invention, since the winding diameter of the end of the coil spring on the ball plug side is made smaller than that of the general portion, the end of the coil spring is expanded when the ball plug is press-fitted into the guide hole of the cover body. Biting into the edge of the hole can be suppressed.

According to the second aspect of the present invention, half of the difference between the diameters of the first and second turns on the ball plug side of the coil spring (that is, the difference between the radii of the first and second turns) {= (r ₂ −r ₁ ) / 2} is made smaller than the reference value {= d × (2D ₁ −D ₃ + d) / (D ₂ + 3d)}, so that the position of the first wire strand cross-sectional center is set to the second volume. Since the coil spring can be set on the outer periphery side of the coil spring from the straight line connecting the center of the wire cross section and the center of the ball plug, when the ball spring is pressed into the guide hole of the cover body, The first roll is biased toward the outer peripheral side of the coil spring by the resultant force of the force acting on the first volume from the plug and the force acting on the second volume to the first volume. That is, according to such a configuration, the first winding of the coil spring is not urged toward the center, so that when the ball plug is press-fitted into the guide hole of the cover body, the winding diameter of the first winding of the coil spring is It is possible to suppress the first volume from entering the center direction from the second volume by narrowing.

  According to the invention of claim 3, since the first and second windings of the coil spring are bonded to each other, when the ball plug is press-fitted into the guide hole of the cover body, the end of the coil spring expands and the guide hole It is possible to suppress biting into the edge of the.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments embodying the invention will be described with reference to the drawings. Here, a fuel pump for pumping and supplying fuel in a fuel tank to an automobile internal combustion engine is illustrated.

  (First Embodiment) FIG. 1 is a longitudinal sectional view of a fuel pump according to this embodiment, FIG. 2 is a sectional view taken along line II-II in FIG. 1, and FIG. 3 is a ball plug provided in the present embodiment. 4 is a longitudinal sectional view showing a state in which the coil body is press-fitted into the guide hole of the cover body, FIG. 4 is a longitudinal sectional view for explaining a difference between the radii of the first and second windings of the coil spring, and FIG. It is a longitudinal cross-sectional view which shows the state where the part sunk in the center direction.

  First, a schematic configuration of the fuel pump will be described. In FIG. 1, the fuel pump according to the present embodiment has a cylindrical casing 1 having both axial ends open. A rotating shaft 13 is rotatably provided at the center portion of the casing 1, and a pump portion 2 and a covered cylindrical cover body 9 are provided at both ends in the axial direction, and the pump portion 2 and the cover body are provided. 9, an electric motor 14 that drives the pump unit 2 is disposed.

  The pump unit 2 includes an outer housing 3 and an inner housing 4 that close the bottom side of the casing 1, an impeller 5 that is rotatably provided between the housings 3 and 4, and an outer peripheral side of the impeller 5. A substantially C-shaped fuel passage 6 defined between the housings 3 and 4, a fuel suction port 7 provided in the outer housing 3, and a fuel discharge port 8 provided in the inner housing 4 are roughly configured.

  As shown in FIGS. 1 and 2, the cover body 9 is provided with a bearing cylinder 9 </ b> A that is located at the center and opens downward, and a brush 17 that will be described later is disposed at a symmetrical position across the bearing cylinder 9 </ b> A. A guide hole 9B to be supported, and a connector 12 and a terminal 12A for connecting the electric motor 14 to an external power source (not shown) are provided.

  The electric motor 14 includes a pair of stators 15 made of permanent magnets fixed in the casing 1, a rotor 16 positioned on the inner peripheral side of each stator 15 and attached to the rotary shaft 13, and a cover body 9. The pair of brushes 17 provided in the guide hole 9B and a commutator 18 provided at the other end in the axial direction of the rotor 16 are roughly configured. The impeller 5 of the pump unit 2 is rotationally driven by the electric motor 14 via the rotary shaft 13.

  Each brush 17 is provided in the guide hole 9B of the cover body 9, and is urged toward the commutator 18 by a coil spring 17A. Each brush 17 is connected to the terminal 12 </ b> A of the external power connector 12, and the tip end surface thereof is in sliding contact with the sliding contact surface 19 </ b> A of the sliding contact member 19.

  A coil spring 17A is inserted into the guide hole 9B of the cover body 9 and the coil spring 17A is supported by press-fitting the ball plug 17B into the end of the guide hole 9B. That is, the coil spring 17A is provided between the ball plug 17B and the brush 17, and the outer periphery of the coil spring 17A is guided by the guide hole 9B. The winding diameter of the coil spring 17A is set smaller than the outer diameter of the ball plug 17B and the inner diameter of the guide hole 9B of the cover body 9.

The coil spring 17A includes a first roll 17a in contact with the ball plug 17B, a subsequent second roll 17b, and a third and subsequent general portions 17c. Winding diameter _{r 1} of 1 tum 17a, as well is set to be smaller than the winding diameter _{D 1} of the general portion 17c, winding diameter _{r 2} of 2 tum 17b is equivalent to the winding diameter _{D 1} of the general portion 17c.

In the present embodiment, the diameter of the ball plug 17B and _{D 2,} the diameter of the guide hole 9B and _{D 3,} the wire diameter of the coil springs 17A and d, 1 tum 17a and the radius of 2 tum 17b When the difference {(r ₂ −r ₁ ) / 2} is α, an inequality of α <d × (2D ₁ −D ₃ + d) / (D ₂ + 3d) is established. That is, when the center of the ball plug 17B, the wire cross-sectional center of the first winding 17a of the coil spring 17A, and the wire cross-sectional center of the second winding 17b are in a straight line, the center of the ball plug 17B and the second winding 17b the distance between the strand cross-section center and L _1, the distance between the strand cross-section center of the vertical line and 2 tum 17b passing through the center of the ball plug 17B When L _2, of 1 tum 17a and 2 tum 17b The reference value α _{0 for} the difference between the radii is obtained by the following equation. _{Therefore, α 0 = d × L 2} / L 1, L 1 = D 2/2 + d + d / 2 = (D 3 + 3d) / 2, L 2 = D 3 / 2- {D 3 - (D 1 + d / 2) } = (2D ₁ −D ₃ + d) / 2 holds, and from these equations, the reference value α ₀ of the above α is determined as α ₀ = d × (2D ₁ −D ₃ + d) / (D ₂ + 3d). ).

  In the above configuration, when the fuel pump is assembled, after inserting the coil spring 17A into the guide hole 9B of the cover body 9, the ball plug 17B is pressed toward the guide hole 9B of the cover body 9 as shown in FIG. Press fit into the guide hole 9B.

At that time, as shown in FIG. 4, when viewed in an axial cross section passing through the center of the ball plug 17B, the first roll 17a of the coil spring 17A has a direction opposite to the second roll 17b and the ball plug 17B. Forces F1 and F2 act. Then, the winding diameter _{r 1} of 1 tum 17a and (the difference between the radii of ie 1 tum 17a and 2 tum 17b) half the difference between the winding diameter _{r 2} of 2 tum 17b alpha of the coil spring 17A, By making it smaller than the reference value α ₀ {= d × (2D ₁ −D ₃ + d) / (D ₂ + 3d)}, the position of the wire cross-sectional center of the first roll 17a is changed to the element of the second roll 17b. It can be set on the outer peripheral side of the coil spring 17A from a straight line connecting the center of the line cross section and the center of the ball plug 17B.

As a result, when the coil spring 17A is pressed via the ball plug 17B when the ball plug 17B is press-fitted into the guide hole 9B of the cover body 9, the force F ₁ acting on the first roll 17a from the ball plug 17B and the second roll the resultant force of the force _{F 2} acting from 17b to 1 tum 17a, so that the 1 tum 17a is urged to the outer peripheral side of the coil spring 17A. Therefore, according to this embodiment, it can suppress that the 1st volume 17a of the coil spring 17A is urged | biased to a center direction.

Incidentally, the difference α between the radii of the first and second windings 17a and 17b of the coil spring 17A is based on the reference value α ₀ {= d × (2D ₁ −D ₃ + d) / (D ₂ + 3d)}. If it is larger, the position of the wire cross-section center of the first roll 17a is positioned in the center direction of the coil spring 17A than the straight line connecting the wire cross-section center of the second roll 17b and the center of the ball plug 17B. Therefore, the force for biasing the 1 tum 17a towards the center occurs, as a result, the center than 1 tum 17a 2 tum 17b narrows the winding diameter r ₁ of 1 tum 17a as shown in FIG. 5 The trouble that enters in the direction will occur.

As described above, according to the fuel pump of this embodiment, since the winding diameter r ₁ of 1 tum 17a of the coil spring 17A (end) are smaller than the general portion, the ball plug 17B into the guide hole 9B of the cover body 9 It is possible to prevent the first roll 17a from expanding and biting into the edge portion of the guide hole 9B when press-fitting. Further, it is possible to improve the production capacity by increasing the press-fitting speed of the ball plug 17B.

  (Second Embodiment) FIG. 6 is a cross-sectional view of an essential part of a fuel pump according to a second embodiment of the present invention. Note that the fuel pump according to the present embodiment includes the same components as the fuel pump according to the first embodiment. Therefore, the same components are denoted by common reference numerals, and redundant description is omitted.

  In the fuel pump according to the present embodiment, the first winding 17a of the coil spring 17A has a winding diameter equivalent to that of the second winding 17b and the third and subsequent general portions 17c, and the first winding 17a and the second winding 17b. Are glued together.

  According to the present embodiment, since the first winding 17a and the second winding 17b of the coil spring 17A are bonded to each other in this manner, the rigidity of the end increases, so that the ball plug is inserted into the guide hole 9B of the cover body 9. When press-fitting 17B, it can prevent that the 1st volume 17a expands and it is caught in the edge of guide hole 9B. As a result, the first winding 17a of the coil spring 17A can be prevented from being bitten, and the press-fitting speed of the ball plug 17B can be increased to improve the production capacity.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the present invention can be implemented as long as the spring is supported by a plug, and the internal structure of the fuel pump itself is not limited to the above embodiment.

It is a longitudinal cross-sectional view (cross-sectional view along an axial direction) of the fuel pump concerning 1st Embodiment of this invention. It is sectional drawing (sectional drawing along an axial direction) which follows the II-II line | wire of FIG. It is a longitudinal cross-sectional view (cross-sectional view along an axial direction) which shows the state which press-fits the ball plug provided in 1st Embodiment in the guide hole of a cover body. It is a longitudinal cross-sectional view (cross-sectional view along an axial direction) explaining the difference of each radius of the 1st volume and the 2nd volume of the coil spring provided in the fuel pump concerning 1st Embodiment of this invention. It is a longitudinal cross-sectional view (cross-sectional view along an axial direction) which shows the state which the edge part of the coil spring provided in the fuel pump concerning 1st Embodiment of this invention sunk in the center direction. It is principal part sectional drawing (sectional drawing along an axial direction) of the fuel pump concerning 2nd Embodiment of this invention. It is a longitudinal cross-sectional view (cross-sectional view along an axial direction) which shows the state which press-fits the ball plug provided in the conventional fuel pump to the guide hole of a cover body, Comprising: (a) is the state which the coil spring end part expanded (B) is a sectional view showing a state in which the coil spring end is hooked on the edge of the guide hole, and (c) is a sectional view showing a state in which the coil spring end is bitten. is there.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 Pump part 9 Cover body 9B Guide hole 12 Connector 12A Terminal 14 Electric motor 17A Coil spring 17B Ball plug 17a First roll 17b Second roll 17c General part

Claims (3)

A cylindrical casing, a pump unit provided in the casing, an electric motor that drives the pump unit, a brush that is in sliding contact with the rotor of the electric motor and supplies power to the coil of the rotor, and the brush A cover body that houses the electric motor, a guide hole that is provided in the cover body and houses the brush, a coil spring that urges the brush toward the rotor, and a ball that is press-fitted into the guide hole to close it In a fuel pump comprising a plug and supporting the coil spring by the ball plug,
The fuel pump according to claim 1, wherein a winding diameter of the coil spring on the ball plug side is smaller than a winding diameter of a general part of the coil spring. The winding diameter of the coil spring and D _1, and the diameter of the ball plug and D _2, the guide diameter of the hole and D _3, the wire diameter of the coil spring is d, the ball plug side of the coil spring When the winding diameter of the first winding is r ₁ and the winding diameter of the second winding is r ₂ ,
_{(R 2 -r 1) / 2} <d × (2D 1 -D 3 + d) / (D 2 + 3d)
The fuel pump according to claim 1, wherein the following formula is satisfied. A cylindrical casing, a pump unit provided in the casing, an electric motor that drives the pump unit, a brush that is in sliding contact with the rotor of the electric motor and supplies power to the coil of the rotor, and the brush A cover body that houses the electric motor, a guide hole that is provided in the cover body and houses the brush, a coil spring that urges the brush toward the rotor, and a ball that is press-fitted into the guide hole to close it In a fuel pump comprising a plug and supporting the coil spring by the ball plug,
A fuel pump characterized in that the first and second windings at the end of the coil spring on the ball plug side are bonded to each other.

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