JP2016223323A - Fuel pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel pump capable of suppressing abrasion of an impeller.SOLUTION: An outer wall surface of an output end portion 37 includes a pair of first planes 51, 52 in parallel with each other. An inner wall surface of a fitting hole 44 includes a pair of second planes 61, 62 in parallel with each other, and engaged with one first plane 51 or the other first plane 52 when a rotating shaft 31 is rotated in a prescribed rotating direction. A value obtained by dividing a width across flats S by an outer diameter D of the output end portion 37 is 0.75 or less. By setting the width across flats S in this manner, restriction force acting on an impeller 39 from the output end portion 37 is increased, and frictional force between the output end portion 37 and the impeller 39 is increased. Thus a situation that the force due to axial difference of pressure applied to the impeller 39 from a fuel becomes more than the frictional force between the output end portion 37 and the impeller 39, hardly occurs. Accordingly, sliding of the fitting hole 44 and the output end portion 37 is suppressed, and abrasion of the impeller 39 can be suppressed.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a fuel pump.

There is known a fuel pump that includes a motor, an impeller coupled to an output end of a rotating shaft of the motor, and a case that houses the impeller. The case has a pump chamber, a suction hole penetrating from the pump chamber in one axial direction, and a discharge hole penetrating from the pump chamber in the other axial direction.
In this type of fuel pump, the output end of the rotating shaft is fitted into the fitting hole of the impeller, so that the impeller and the rotating shaft are coupled so as to be able to transmit rotation. For example, as disclosed in Patent Document 1, the cross-sectional shape of the fitting hole is non-circular, and is D-shaped or polygonal.

JP 2014-173456 A

  By the way, the conventional fuel pump has a problem that the fitting hole of the impeller is worn as it is used. According to the studies by the present inventors, it has been found that the main cause of the wear is that the impeller slides relative to the rotating shaft in the axial direction and the fitting hole and the output end slide. As a result of further research, the pressure applied from the fuel to the impeller is different between the suction hole side and the discharge hole side, and when the force due to this pressure difference is larger than the frictional force between the output end and the impeller, the impeller It was found that relative movement occurred. In particular, when a high-pressure pump is provided at the discharge destination of the fuel pump and the pulsation of the fuel pressure generated in the high-pressure pump is transmitted to the fuel pump, the pressure difference becomes larger and the impeller is likely to be worn.

  This invention is made | formed in view of the above-mentioned point, The objective is to provide the fuel pump which can suppress abrasion of an impeller.

  As a result of repeated studies on the shape of the output end of the rotating shaft by the present inventors, (1) it is preferable that the outer wall surface of the output end includes a pair of parallel planes, and (2) the distance between the pair of planes. It was found that the smaller the two-surface width, the greater the restraining force acting on the impeller from the output end, and the greater the frictional force between the output end and the impeller. When two surfaces parallel to the shaft are provided to transmit the rotation, the width of the two surfaces is usually set to about 0.8 times the outer diameter of the shaft as defined in JIS B 1002. It is. On the other hand, the present inventors aim to make the frictional force between the output end and the impeller larger than the force due to the axial difference in pressure applied from the fuel to the impeller. The idea of reducing the width was reached and the present invention was completed.

A fuel pump according to the present invention includes a motor, an impeller having a fitting hole that is fitted to an output end portion of a rotating shaft of the motor, and a case. The case has a pump chamber accommodating the impeller, a suction hole penetrating from the pump chamber in one axial direction, and a discharge hole penetrating from the pump chamber to the other axial direction.
The outer wall surface of the output end includes a pair of first planes parallel to each other. A pair of inner wall surfaces of the fitting holes are parallel to each other in a cross section orthogonal to the axis of the impeller, and engage with one first plane or the other first plane when the rotation shaft rotates in a predetermined rotation direction. Of the second plane. In a case where the distance between the pair of first planes is referred to as a dihedral width, a value obtained by dividing the dihedral width by the outer diameter of the output end is 0.75 or less.

  By setting the two-surface width in this way, the restraining force that acts on the impeller from the output end increases, and the frictional force between the output end and the impeller increases. Therefore, a situation in which the force due to the axial difference in pressure applied from the fuel to the impeller is greater than the frictional force between the output end and the impeller is less likely to occur. Therefore, sliding between the fitting hole and the output end portion is suppressed, and wear of the impeller can be suppressed.

It is a figure which shows the longitudinal cross-section of the fuel pump by 1st Embodiment of this invention. It is the II-II sectional view taken on the line of FIG. It is a figure which shows the impeller of FIG. It is an enlarged view of the IV part of FIG. It is the VV sectional view taken on the line of FIG. 1, Comprising: It is an enlarged view of the output end part of a rotating shaft, and the fitting hole of an impeller. It is a figure which shows a mode that the output end part and impeller of a rotating shaft of FIG. 5 contact and rotate in two places. It is a figure which shows the state which moved so that one 1st plane of an output edge part might contact | connect one 2nd plane of a fitting hole from the state of FIG. It is a figure which expands and shows the fitting part of the output-end part of a rotating shaft, and an impeller among the longitudinal cross-sections of the fuel pump by 2nd Embodiment of this invention.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. In the embodiments, substantially the same components are denoted by the same reference numerals and description thereof is omitted.
[First Embodiment]
The fuel pump according to the first embodiment of the present invention is an in-tank type pump installed in a fuel tank of a vehicle. The fuel pump sucks fuel from a suction port 14 shown in the lower part of FIG. It discharges to the engine which is not illustrated from the discharge port 18 shown on the upper part.

(overall structure)
First, the overall configuration of the fuel pump 10 will be described with reference to FIGS.
The fuel pump 10 is roughly divided into an outer shell, a driving unit, and a boosting unit. The outer shell includes a housing 11, a suction side cover 12, and a discharge side cover 15.

The housing 11 is formed in a cylindrical shape.
The suction side cover 12 is provided at one end of the housing 11. The suction side cover 12 has a suction hole 13 penetrating in the axial direction. The suction port 14 is an inlet of the suction hole 13.
The discharge side cover 15 is provided at the other end of the housing 11. Further, the discharge side cover 15 forms a cylindrical portion 16 that protrudes outside the housing 11, and has a discharge flow path 17 formed inside the cylindrical portion 16. The discharge port 18 is an outlet of the discharge flow channel 17. A bearing 19 is provided at the center of the discharge side cover 15.

The drive unit includes a motor 20 and includes a stator 21 and a rotor 22.
The stator 21 is provided in the housing 11 and includes a stator core 23, an insulator 24, a winding 25, and a terminal 26. The stator core 23 is made of a magnetic material, and forms a cylindrical yoke portion 27 and a plurality of teeth portions 28 that protrude radially inward from the yoke portion 27. The insulator 24 is attached to the tooth portion 28 of the stator core 23. The winding 25 is wound around the insulator 24. In the present embodiment, winding 25 includes a U-phase winding portion, a V-phase winding portion, and a W-phase winding portion. Three terminals 26 are provided, and the winding portions of each phase can be connected to an external control device.

A fuel flow path 29 is defined between the housing 11 and the stator 21. The discharge side cover 15 has a fuel flow path (not shown) that connects the fuel flow path 29 and the discharge flow path 17.
The rotor 22 is provided inside the stator 21, and includes a rotation shaft 31, a rotor core 32, and a plurality of magnets 33 to 36. The rotating shaft 31 is rotatably supported by the bearing 19 and a bearing 43 described later. The rotor core 32 is cylindrical and is fitted and fixed to the rotating shaft 31. The magnets 33 to 36 are provided on the outer periphery of the rotor core 32. The magnets 33 to 36 are provided such that the polarities on the outer side in the radial direction are alternately different in the circumferential direction.

  In the motor 20 configured as described above, when a current having a phase difference flows in each phase winding portion of the winding 25 of the stator 21, a rotating magnetic field is generated, and this rotating magnetic field pulls the magnetic pole of the rotor 22. As a result, the rotor 22 rotates.

The pressure increasing unit includes a casing 38, an impeller 39, and the suction side cover 12. The suction side cover 12 constitutes an outer shell of the fuel pump 10 and also constitutes a booster.
The casing 38 is formed in a bottomed cylindrical shape, is provided between the stator 21 and the suction side cover 12, and is combined with the suction side cover 12. The casing 38 defines a pump chamber 41 between the suction side cover 12 and the casing 38. A through hole 42 is formed in the center of the casing 38. A bearing 43 is fitted into the through hole 42. The output end 37 of the rotating shaft 31 is inserted through the bearing 43 and protrudes into the pump chamber 41.

  The impeller 39 is a disk-shaped impeller and is accommodated in the pump chamber 41. A fitting hole 44 is formed at the center of the impeller 39. The fitting hole 44 is fitted to the output end 37 of the rotating shaft 31 so that rotation can be transmitted from the rotating shaft 31 to the impeller 39.

  A C-shaped suction side pressure increasing flow path 45 extending in the circumferential direction is formed in a wall portion of the suction side cover 12 facing the impeller 39. The suction hole 13 communicates with an upstream end portion located at an end portion on the opposite side to the rotation direction of the impeller 39 in the suction side pressurizing flow path 45. A C-shaped discharge side pressurizing flow path 46 extending in the circumferential direction is formed in a wall portion of the casing 38 facing the impeller 39. The casing 38 has a discharge hole 47 that communicates with a downstream end located at an end in the rotational direction of the discharge side pressurizing flow path 46. The suction hole 13 is a hole penetrating from the pump chamber 41 in one axial direction, and the discharge hole 47 is a hole penetrating from the pump chamber 41 in the other axial direction. The casing 38 and the suction side cover 12 constitute a case 48.

  In the booster configured as described above, when the impeller 39 rotates together with the rotating shaft 31, fuel is sucked into the pump chamber 41 from the suction port 14 via the suction hole 13. The fuel in the pump chamber 41 flows in a spiral manner between the impeller 39 and the pressure increasing passages 45 and 46, and is pressurized as it goes from the suction hole 13 toward the discharge hole 47. The boosted fuel is guided to the discharge channel 17 via the discharge hole 47 and the fuel channel 29 and discharged from the discharge port 18.

(Feature configuration)
Next, a characteristic configuration of the fuel pump 10 will be described with reference to FIGS. 4 to 7 are schematically shown for easy understanding of the configuration. The dimensions, angles and dimensional ratios of the parts shown in the drawings are not necessarily accurate.

  Here, the research conducted by the inventors will be described. The inventors wanted to reduce the wear of the fitting hole of the impeller and analyzed the cause of this wear. As a result, it has been found that the main factor of wear of the fitting hole is that the impeller moves relative to the rotation shaft in the axial direction and the fitting hole and the output end slide. As a result of further analysis, the pressure applied from the fuel to the impeller has a difference between the suction hole side and the discharge hole side, and when the force due to this pressure difference is larger than the frictional force between the output end and the impeller, the relative impeller It was found that movement occurred. In particular, when a high-pressure pump is provided at the discharge destination of the fuel pump and the pulsation of the fuel pressure generated in the high-pressure pump is transmitted to the fuel pump, the pressure difference becomes larger and the impeller is likely to be worn.

In response to the above result, the fuel pump 10 has the following configuration with the aim of making the frictional force between the output end 37 and the impeller 39 larger than the force due to the axial difference in pressure applied from the fuel to the impeller 39. Adopted.
As shown in FIGS. 4 to 6, the outer wall surface of the output end portion 37 includes a pair of first planes 51 and 52 that are parallel to each other. The first planes 51 and 52 are parallel to the axis AX1 of the rotation shaft 31.

Further, the outer wall surface of the output end portion 37 is located between the first flat surface 51 and the other first flat surface 52 in the circumferential direction, and is a pair of first curved surfaces 53 that protrude outward in the radial direction. , 54. In the first embodiment, the centers of curvature of the first curved surfaces 53 and 54 coincide with the axis AX1. Further, the radius of the first curved surface 53 is the same as the radius of the first curved surface 54. That is, the first curved surface 53 and the first curved surface 54 are formed along a virtual cylindrical surface centered on the axis AX1.
That is, the output end portion 37 is a two-chamfered shaft having a pair of first planes 51 and 52 parallel to each other. This two-chamfered shaft is also referred to as an I-cut shaft or a double D-cut shaft.

  The inner wall surface of the fitting hole 44 includes a pair of second planes 61 and 62 that are parallel to each other. The second planes 61 and 62 are parallel to the axis AX2 of the impeller 39. The second plane 61 faces the first plane 51 in the radial direction, and engages with the first plane 51 when the rotation shaft 31 rotates in a predetermined rotation direction. The second plane 62 faces the first plane 52 in the radial direction, and engages with the first plane 52 when the rotation shaft 31 rotates in a predetermined rotation direction.

  In addition, the inner wall surface of the fitting hole 44 is positioned between one second plane 61 and the other second plane 62 in the circumferential direction, and is a pair of second curved surfaces 63 that are recessed outward in the radial direction. 64. In the first embodiment, the centers of curvature of the second curved surfaces 63 and 64 coincide with the axis AX2. Further, the radius of the second curved surface 63 is the same as the radius of the second curved surface 64. That is, the second curved surface 63 and the second curved surface 64 are formed along a virtual cylindrical surface centered on the axis AX2.

As shown in FIGS. 4 and 5, when the distance between the pair of first planes 51 and 52 is referred to as a two-surface width S, the value obtained by dividing the two-surface width S by the outer diameter D of the output end portion 37 is 0. .75 or less. In the first embodiment, the value obtained by dividing the dihedral width S by the outer diameter D is, for example, 0.74.
As shown in FIG. 7, in the state where one first plane 51 and one second plane 61 are in contact with each other, the clearance C between the other first plane 52 and the other second plane 62 is defined as a two-surface width S. The value divided by is 0.011 or less. In the first embodiment, the value obtained by dividing the clearance C by the dihedral width S is 0.011.

  In the fuel pump 10 configured as described above, the clearance C and the transmission are compared with the normal configuration in which the width of the two surfaces is set to about 0.8 times the outer diameter of the shaft as defined in JIS B 1002. When the torque is in the same condition, the restraining force acting on the impeller 39 from the output end 37 is increased. As shown in FIG. 6, the restraining force Fb is a direction perpendicular to the second planes 61 and 62 out of the force F acting on the impeller 39 from the output end 37 at the contact portion between the output end 37 and the impeller 39. It is a component.

(effect)
As described above, in the first embodiment, the outer wall surface of the output end portion 37 includes a pair of first planes 51 and 52 that are parallel to each other. The inner wall surfaces of the fitting holes 44 are parallel to each other, and a pair of second planes 61 that engage with one first plane 51 or the other first plane 52 when the rotation shaft 31 rotates in a predetermined rotation direction. 62. A value obtained by dividing the two-surface width S by the outer diameter D of the output end portion 37 is 0.75 or less.

  By setting the two-surface width S in this way, the restraining force acting on the impeller 39 from the output end portion 37 becomes larger than in the above-described normal form, and the frictional force between the output end portion 37 and the impeller 39 becomes larger. . Therefore, a situation in which the force due to the axial difference in pressure applied from the fuel to the impeller 39 is greater than the frictional force between the output end 37 and the impeller 39 is less likely to occur. Therefore, sliding between the fitting hole 44 and the output end portion 37 is suppressed, and wear of the impeller 39 can be suppressed.

In the first embodiment, in the state where one first plane 51 and one second plane 61 are in contact with each other, the clearance C between the other first plane 52 and the other second plane 62 is set to a two-plane width. The value divided by S is 0.011 or less.
The restraining force acting on the impeller 39 from the output end 37 increases as the two-surface width S decreases, and increases as the clearance C decreases. Therefore, the wear of the impeller 39 can be further suppressed.

[Second Embodiment]
In the second embodiment of the present invention, as shown in FIG. 8, the inner wall surface of the fitting hole 71 includes second planes 72 and 73, third planes 74 and 75, and second curved surfaces 63 and 64.
The second plane 72 and the second plane 73 are parallel to each other. The second plane 72 is opposed to the first plane 51 in the radial direction, and engages with the first plane 51 when the rotation shaft 31 rotates in a predetermined rotation direction. The second plane 73 faces the first plane 52 in the radial direction, and engages with the first plane 52 when the rotation shaft 31 rotates in a predetermined rotation direction.

  The third plane 74 and the third plane 75 are parallel to each other. The third plane 74 is formed between the second plane 72 and the second curved surface 64 in the circumferential direction. The second plane 72 and the third plane 74 form a convex surface that is convex toward the axis AX2. The third plane 74 engages with the first plane 51 when the rotation shaft 31 rotates in the direction opposite to the rotation direction. The third plane 75 is formed between the second plane 73 and the second curved surface 63 in the circumferential direction. The second plane 73 and the third plane 75 form a convex surface that is convex toward the axis AX2. The third plane 75 engages with the first plane 52 when the rotation shaft 31 rotates in the direction opposite to the rotation direction.

  An interval W1 between one third plane 74 and the other third plane 75 is larger than an interval W2 between one second plane 72 and the other second plane 73. The interval W2 is slightly larger than the two-surface width S. On the other hand, the interval W1 is sufficiently larger than the two-surface width S.

In the second embodiment, the value obtained by dividing the dihedral width S by the outer diameter D of the output end portion 37 is 0.75 or less. Therefore, similarly to the first embodiment, sliding between the fitting hole 71 and the output end portion 37 is suppressed, and wear of the impeller 39 can be suppressed.
In the second embodiment, when the rotating shaft 31 and the impeller 39 are assembled, the output end 37 is inserted between one third plane 74 and the other third plane 75. When the rotation is transmitted from the rotating shaft 31 to the impeller 39, the first planes 51 and 52 and the second planes 72 and 73 are engaged. Therefore, the clearance between the output end 37 and the fitting hole 71 at the time of rotation transmission is made as small as possible without sacrificing the assembling property, and the restraining force acting on the impeller 39 from the output end 37 is increased. can do. Therefore, sliding between the fitting hole 71 and the output end portion 37 can be further suppressed.

[Other Embodiments]
In another embodiment of the present invention, the outer wall surface of the output end portion is not only composed of a pair of first planes and a pair of first curved surfaces, but also a pair of first planes and one or more other planes. May be configured. In short, the outer wall surface of the output end portion only needs to include a pair of first planes.
In another embodiment of the present invention, the corner between the plane and the curved surface of the outer wall surface of the output end or the corner between the plane and the plane may be rounded.
In another embodiment of the present invention, the impeller is not limited to resin, and may be made of other materials such as metal.
The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from the spirit of the invention.

13 ... Suction hole 20 ... Motor 31 ... Rotating shaft 37 ... Output end 39 ... Impeller 41 ... Pump chamber 44 ... Fitting hole 47 ... Discharge hole 48 ..Case 51, 52: First plane 61, 62, 72, 73: Second plane D: Outer diameter S: Width across flats

Claims (3)

A motor (20);
An impeller (39) having a fitting hole (44, 71) fitted to the output end (37) of the rotating shaft (31) of the motor;
A pump chamber (41) containing the impeller, a suction hole (13) penetrating from the pump chamber in one axial direction, and a discharge hole penetrating from the pump chamber to the other axial direction ( A case (48) having 47);
With
The outer wall surface of the output end includes a pair of first planes (51, 52) parallel to each other,
Inner wall surfaces of the fitting holes are parallel to each other in a cross section perpendicular to the axis of the impeller, and one of the first planes or the other first plane when the rotation shaft rotates in a predetermined rotation direction. A pair of second planes (61, 62, 72, 73) that engage with
In the case where the distance between the pair of first planes is referred to as a dihedral width (S), a value obtained by dividing the dihedral width by the outer diameter (D) of the output end is 0.75 or less. And fuel pump.   In a state where one of the first planes is in contact with one of the second planes, the value obtained by dividing the clearance between the other first plane and the other second plane by the width of the two surfaces is 0.011. The fuel pump according to claim 1, wherein: A pair of inner wall surfaces of the fitting hole (71) are parallel to each other and engage one of the first planes or the other first plane when the rotation shaft rotates in a direction opposite to the rotation direction. A third plane (74, 75) of
The distance (W1) between one of the third planes and the other third plane is greater than the distance (W2) between one of the second planes and the other second plane. The fuel pump according to 1 or 2.

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