JP2007195295A - Axial motor and fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an axial motor radially miniaturized. <P>SOLUTION: Since a circuit board 64 is disposed so as to face an outer circumference of a stator coil 60, the circuit board 64 does not need to be radially extended even if a drive circuit for driving the stator coil is provided on the circuit board 64, and an outside diameter of the motor 70 can be reduced. Since the circuit board 64 faces the outer circumference of the stator coil, an axial length of the motor 70 is prevented from increasing. As the motor 70 can be prevented from being axially enlarged, it can be radially miniaturized. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an axial type motor. In the present specification, the “axial motor” means a flat motor in which a rotor and a stator face each other.

  Since the axial type motor can shorten the length in the rotation axis direction of the motor, its use for various devices is being studied. As an example of the axial type motor, there is a motor disclosed in Patent Document 1. The motor of Patent Document 1 includes a disk-shaped rotor and a stator coil. The rotor has a rotor magnet formed in a ring shape around the rotation axis of the motor (rotor). The stator coil has a core and a coil winding wound around the core. The core of the stator coil faces the rotor magnet, and is arranged concentrically around the rotation axis of the motor (rotor). A drive circuit is connected to the stator coil. In this motor, when a current flows through the coil winding of the stator coil, a magnetic force is generated from the stator coil core toward the rotor magnet, and an attractive force / repulsive force is generated between the stator coil and the rotor magnet. The drive circuit turns ON / OFF the current supply to the plurality of stator coils, whereby the rotor rotates.

JP-A-7-303362

Axial motors are also required to be smaller in the radial direction of the motor. In the axial type motor of Patent Document 1, a circuit board is arranged to face a rotor magnet, and a stator coil and a drive circuit are provided on the circuit board. Since the stator coil is disposed in a region facing the rotor magnet, the drive circuit is disposed in a region protruding outward in the radial direction of the motor from the outer periphery of the stator coil of the circuit board. For this reason, there is a problem that the circuit board becomes larger in the radial direction of the motor, and as a result, the motor itself is increased in size in the radial direction.
An object of the present invention is to provide a technique capable of downsizing an axial type motor in the radial direction.

An axial type motor of the present invention includes a disk-shaped rotor having a rotor magnet, a plurality of stator coils disposed concentrically with a point on the rotation axis of the rotor as opposed to the rotor. And a circuit board provided with a drive circuit for driving a plurality of stator coils. And the surface in which the drive circuit of a circuit board is provided, or its back surface is facing the outer peripheral surface of a stator coil, It is characterized by the above-mentioned.
In the above axial type motor, since the surface of the circuit board on which the drive circuit is provided extends in the direction of the rotation axis of the motor, the circuit board is prevented from becoming large in the radial direction of the motor. Further, since the circuit board is disposed on the outer peripheral side of the stator coil and both are not juxtaposed in the direction of the rotation axis of the motor, it is possible to prevent the axial length of the motor from becoming long. According to the axial type motor of the present invention, it is possible to reduce the size of the motor in the radial direction while preventing the motor from increasing in the axial direction.

The circuit board of the axial motor of the present invention is preferably arranged in a circle or arc along the outer peripheral surface of the stator coil.
According to such a configuration, the area of the circuit board can be increased without increasing the size of the motor, and the heat dissipation of the drive circuit can be improved. Thereby, the temperature rise of the drive circuit is suppressed, and the motor efficiency can be improved.

The axial type motor of the present invention described above can be suitably used for a fuel pump. That is, the fuel pump of the present invention includes any one of the above-described axial motors, and a circuit board is disposed in the fuel passage.
In the above fuel pump, since the circuit board of the motor is disposed in the fuel passage, the drive circuit is further cooled by the fuel. According to the fuel pump of the present invention, the motor unit can be downsized and the motor efficiency can be improved. As a result, the pump efficiency can be improved while miniaturizing the fuel pump.

The fuel discharge port of the fuel pump of the present invention is preferably provided on the downstream side of the circuit board.
According to such a configuration, the drive circuit can be effectively cooled by the fuel. The motor efficiency can be further improved.

Hereinafter, preferred embodiments of the present invention will be described. The first embodiment and the second embodiment are both examples of a vehicle fuel pump on which an axial motor is mounted.
(Mode 1) The circuit board is disposed in a gap between the housing and the outer periphery of the core of the stator coil. The circuit board has a substantially rectangular shape with one long side, the long side is bent along the outer periphery of the core, and is arranged in a state of facing the outer peripheral surface of the stator coil.
(Mode 2) A terminal for connecting the coil winding is formed on the edge of one long side of the circuit board.
(Mode 3) The terminal is formed in a cut shape at the edge of the long side of the circuit board. The ends of the coil windings are pushed into the notched terminal and are sandwiched and connected.
(Mode 4) The terminal is formed in a long and narrow plate shape extending from the edge of the long side of the circuit board. The end portion of the coil winding is wound around and connected to the elongated plate-like terminal.

A first embodiment embodying the present invention will be described with reference to the drawings. The present embodiment is an example of a vehicle fuel pump on which an axial motor is mounted. The fuel pump 10 according to this embodiment is for an automobile and is installed inside a fuel tank mounted on the automobile. In a state where the fuel pump 10 is installed in the fuel tank, the lower surface of the fuel pump 10 contacts the bottom surface of the fuel tank. The fuel pump operates while being immersed in the fuel, and pumps the fuel in the fuel tank to the engine.
FIG. 1 is a longitudinal sectional view of the fuel pump 10. As shown in FIG. 1, the fuel pump 10 includes a motor unit 70 and a pump unit 30. Note that the top and bottom in FIG. 1 coincide with the top and bottom when the fuel pump 10 is mounted in the fuel tank.

  The motor unit 70 employs an axial brushless motor structure. The motor unit 70 includes a housing 14, a top cover 12, a rotor 41, a stator coil 60, and the like. The housing 14 is formed in a substantially cylindrical shape. The top cover 12 is fixed to the upper end of the housing 14. The top cover 12 is formed with a discharge port 68 that opens upward. A yoke 44 is fixed to the lower surface of the top cover 12. The yoke 44 is formed in a ring shape, and its inner peripheral edge faces the inner peripheral edge of the rotor magnet 42 described later, and its outer peripheral edge faces the outer peripheral edge of the rotor magnet 42. The rotor 41 is supported so as to be rotatable with respect to the top cover 12. The stator coil 60 is disposed on the upper surface of the discharge-side casing 18.

First, the rotor 41 will be described. The rotor 41 includes a rotor magnet 42 and a shaft 40 that passes through the center of the rotor magnet 42. The rotor magnet 42 is a plastic magnet obtained by molding a resin mixed with magnetic powder such as iron powder into a disk shape. The position of the outer peripheral edge of the rotor magnet 42 substantially coincides with the position of the outer peripheral edge of the yoke 44 and the position of the outer peripheral edge of the core magnetic pole 56 of the stator coil 60. The rotor magnet 42 is clamped between the holder 33 and the holder 35 and fixed to the shaft 40. The position of the outer peripheral edge of the holder 35 substantially coincides with the position of the inner peripheral edge of the yoke 44. Therefore, the region of the rotor magnet 42 exposed from the holder 35 substantially coincides with the region of the yoke 44 and the region of the core magnetic pole 56, and the magnetic force of the rotor magnet 42 is converged by the yoke 44. Since the rotor magnet 42 and the shaft 40 are fixed, when the rotor magnet 42 rotates, the shaft 40 also rotates.
The upper end of the shaft 40 is attached to the top cover 12 through a bearing 36 so as to be rotatable. The lower end of the shaft 40 is attached to the discharge-side casing 18 of the pump casing 20 via a ball bearing 34. The inner ring of the ball bearing 34 is clamped between the holder 35 and the sleeve 32 and fixed to the shaft 40. The outer ring of the ball bearing 34 is press-fitted into the discharge-side casing 18 and fixed. Thus, the lower end of the shaft 40 is attached to the discharge-side casing 18 in a rotatable state. An impeller 22 described later is fixed to the lower end of the shaft 40.

  Next, the stator coil 60 will be described with reference to FIGS. FIG. 2 is a diagram schematically showing an arrangement state of the stator coil 60 as viewed from the rotor magnet 42 side. As shown in FIG. 2, a plurality of stator coils 60 are arranged on concentric circles centering on the shaft 40 (specifically, the rotation axis of the shaft 40). In the present embodiment, nine stator coils 60 are arranged around the shaft 40 at equal intervals. The stator coil 60 has a fan shape when viewed from above, and the circumferential length increases as the distance from the shaft 40 increases.

  As shown in FIG. 1, each stator coil 60 has a core 54 and a coil winding 50 wound around the core 54. The core magnetic pole 56 at the upper end of the core 54 faces the rotor magnet 42. A back yoke 52 is provided at the lower end of the core 54. The outer diameter of the back yoke 52 is larger than the outer diameter of the core 54. The back yoke 52 is fixed on the discharge side casing 18 of the pump unit 30.

  As shown in FIG. 2, each stator coil 60 is arranged in a state in which the back yokes 52 of adjacent stator coils 60 are adjacent and continuous. A circuit board 64 is disposed on the outer peripheral side of the stator coil 60 (the structure of the circuit board 64 will be described in detail later). A coil winding 50 of each stator coil 60 is connected to the circuit board 64. The circuit board 64 is connected to a terminal 66 provided on the top cover 12, and the terminal 66 is connected to an external power source (not shown). When electric power from an external power source is supplied to each stator coil 60 via the circuit board 64, the rotor 41 is rotationally driven.

The core 54 and the core magnetic pole 56 are spaced from each other between the adjacent core 54 and the core magnetic pole 56. The core 54 is formed in a columnar body whose horizontal cross section has a fan shape. A coil winding 50 is wound around the side surface of the core 54.
The core magnetic pole 56 also has a fan-like horizontal cross-sectional shape, and has a shape similar to the horizontal cross-sectional shape of the core 54. However, the inner peripheral edge and both side edges of the core magnetic pole 56 protrude outward from the core 54, thereby forming teeth 58 on the inner peripheral edge and both side edges of the core magnetic pole 56. Accordingly, the circumferential interval between adjacent core magnetic poles 56 is narrow, and the circumferential interval between adjacent cores 54 is wide. Further, the distance from the shaft 40 to the core magnetic pole 56 is short, and the distance from the shaft 40 to the core 54 is long. As a result, a space for winding the coil winding 50 around the core 54 is secured, and the core magnetic pole 56 is widened to increase the magnetic force acting on the rotor magnet 42. In particular, in the present embodiment, the core magnetic pole 56 projects greatly toward the shaft 40, and the center of the magnetic pole of the stator coil 60 is shifted toward the shaft 40.
The outer peripheral surface of the core 54 and the outer peripheral surface of the core magnetic pole 56 are formed to be in the same plane (that is, a step is formed between the outer peripheral surface of the core 54 and the outer peripheral surface of the core magnetic pole 56. (See Figure 1). Therefore, the length from the center of the shaft 40 to the outer peripheral surface of the core 54 is substantially equal to the length from the center of the shaft 40 to the outer peripheral surface of the core magnetic pole 56. As is clear from FIG. 1, the position of the outer peripheral edge of the rotor magnet 42 also corresponds to the position of the outer peripheral surface of the core magnetic pole 56, and the length from the shaft 40 to the outer peripheral edge of the rotor magnet 42 is the shaft 40. The length from the center of the core to the outer peripheral surface of the core magnetic pole 56 is substantially equal.

  FIG. 3 is a front view of the circuit board 64. As shown in FIG. 3, the circuit board 64 has a substantially rectangular shape with a long lateral direction. A plurality of terminals 64 a for connecting the coil winding 50 are formed on the upper edge of the circuit board 64. A drive circuit for driving each stator coil 60 is disposed in a region 64 on the surface of the circuit board 64 (a region facing the outer peripheral surface of the stator coil 60). The drive circuit provided in the region 64 includes a wiring that connects each terminal 64a and the terminal 66, and a drive control element that turns ON / OFF the current supply from the terminal 66 to each terminal 64a. The circuit board 64 may be provided with only wiring for connecting each terminal to the terminal, and the drive control element may be disposed outside the fuel pump.

  FIG. 4 is a front view of the terminal 64a, and FIG. 5 is a top view of FIG. As shown in FIG. 4, the terminal 64a is formed with a tapered portion 64b and a clamping portion 64c. The tapered portion 64b is formed so as to gradually become narrower from the upper end portion downward. A clamping part 64c is connected to the lower end of the taper part 64b. The width of the sandwiching portion 64c is substantially the same as the width of the lower end of the tapered portion 64b. The width of the upper end of the tapered portion 64 b is larger than the diameter of the coil winding 50, and the width of the lower end of the tapered portion 64 b and the sandwiching portion 64 c is slightly smaller than the diameter of the coil winding 50. For this reason, the coil winding 50 pushed from the upper end of the taper portion 64b is sandwiched and connected by the sandwiching portion 64c. Further, as shown in FIG. 5, the thickness of the terminal 64 a is made thicker than other portions of the circuit board 64. For this reason, the end of the coil winding 50 is stably connected to the terminal 64a. With such a shape of the terminal 64a, the coil winding 50 can be firmly supported, and the connection work can be easily performed.

  The circuit board 64 is disposed in the gap between the housing 14 and the outer peripheral surface of the core 54 of the stator coil 60. The circuit board 64 is bent so that its long side is along the outer periphery of the core 54, and is arranged in a state of facing the outer peripheral surface of the stator coil 60. The circuit board 64 has a circular arc shape in cross section, and the outer diameter of the bent circuit board 64 substantially matches the outer diameter of the back yoke 52. Since the circuit board 64 is disposed in the gap between the housing 14 and the outer peripheral surface of the core 54, the outer diameter of the motor unit 70 can be suppressed to substantially the same size as the outer diameter of the stator coil 60.

The pump unit 30 includes a pump casing 20 and an impeller 22 accommodated in the pump casing 20. The impeller 22 has a substantially disk shape. In the outer peripheral portion of the impeller 22, a group of recesses 26 and 27 arranged in the circumferential direction are formed (FIG. 1 shows only one recess 26 and 27 formed on both upper and lower surfaces of the impeller 22. However, the recesses 26 and 27 are formed over the entire circumference). A recess 27 formed on the upper surface side of the impeller 22 communicates with a recess 26 formed on the lower surface side of the impeller 22 at the bottom. A slight gap is formed between the outer peripheral surface of the impeller 22 and the pump casing 20 (not shown in FIG. 1). This gap is provided for the impeller 22 to rotate smoothly.
A through-hole penetrating in the thickness direction is formed at the center of the impeller 22. The shaft 40 is inserted through the through hole. The shaft 40 and the impeller 22 are attached so as not to be relatively rotatable. When the shaft 40 rotates, the impeller 22 rotates together with the shaft 40.

The pump casing 20 is fixed to the lower end of the housing 14 in a state where the impeller 22 is rotatably accommodated. The pump casing 20 includes a discharge side casing 18 and a suction side casing 16. A through-hole penetrating in the thickness direction is formed at the center of the discharge-side casing 18. A shaft 40 is inserted through the through hole through a ball bearing 34. Thereby, the lower end of the shaft 40 is rotatably supported by the discharge-side casing 18.
On the surface of the discharge casing 18 facing the upper surface of the impeller 22, an upper surface side groove 25 extending from upstream to downstream in a region facing the recess group 27 of the impeller 22 is formed. The downstream end of the upper surface side groove 25 communicates with the inside of the motor unit 70 (specifically, the space surrounded by the housing 14, the top cover 12, and the pump casing 20) by a discharge flow path (not shown) formed in the discharge side casing 18. is doing.
On the surface of the suction side casing 16 that faces the lower surface of the impeller 22, a lower surface side groove 24 that extends from the upstream to the downstream in a region that faces the recess group 26 of the impeller 22 is formed. The upstream end of the lower surface side groove 25 communicates with the outside through a suction flow path (not shown) formed in the suction side casing 16.

In the fuel pump 10 described above, when electric power is supplied to the coil winding 50 of the stator coil 60 and a current flows through the coil winding 50, electromagnetic force acts from the core magnetic pole 56 toward the rotor magnet 42. As a result, an attractive / repulsive force is generated between the stator coil 60 and the rotor magnet 42. When the drive circuit of the circuit board 64 turns ON / OFF the power supply to the coil winding 50 of each stator coil 60, the rotor magnet 42 rotates.
When the rotor magnet 42 rotates, the shaft 40 fixed to the rotor magnet 42 rotates. When the shaft 40 rotates, the impeller 22 fixed to the shaft 40 rotates. When the impeller 22 rotates, fuel is sucked into the pump casing 20. The fuel sucked into the pump casing 20 is increased in pressure with the rotation of the impeller 22 and discharged into the motor unit 70. The fuel discharged into the motor unit 70 flows through the motor unit 70 and is discharged from the discharge port 68 of the top cover 12.

As is apparent from the above description, in the fuel pump 10 of this embodiment, the circuit board 64 is disposed in a state of facing the outer peripheral surface of the stator coil 60, and the surface of the circuit board (in the direction of the rotation axis of the fuel pump 10). The driving circuit is provided on the surface extending to the surface. For this reason, even if the area for providing the drive circuit is provided in the circuit board 64, the circuit board 64 does not increase in the radial direction of the fuel pump 10. As a result, the outer diameter of the motor unit 70 can be reduced. Further, the circuit board 64 is disposed without changing the axial length of the motor unit 70 by causing the circuit board 64 to face the outer peripheral surface of the stator coil 60 (that is, by not arranging both of them in the axial direction). can do. Furthermore, since the area of the circuit board 64 can be increased by making the circuit board 64 face the outer peripheral surface of the stator coil 60, the heat dissipation of the drive circuit can be improved.
Further, in the fuel pump 10 of the present embodiment, the circuit board 64 is bent along the outer periphery of the stator coil 60 and disposed so as to have an arc shape along the outer peripheral surface of the stator coil 60. As a result, the circuit board 64 can be disposed in the gap between the inner wall surface of the housing 14 and the outer peripheral surface of the core 54, and the outer diameter of the motor unit 70 is suppressed to be approximately the same as the outer diameter of the stator coil 60. be able to. By arranging the circuit board 64 in an arc shape, the area of the circuit board 64 can be increased without increasing the outer diameter of the motor unit 70, and the heat dissipation of the drive circuit can be further improved. it can.
Further, the circuit board 64 is disposed on the fuel passage of the fuel pump 10. For this reason, the circuit board 64 can be effectively cooled by the passing fuel.
According to the fuel pump 10 of the present embodiment, the motor unit 70 can be reduced in size. Further, since the heat dissipation of the drive circuit is improved, an increase in resistance value due to an increase in the temperature of the drive circuit is suppressed, and the motor efficiency can be improved. Thereby, the fuel pump 10 can be downsized and the pump efficiency can be improved.

  A second embodiment embodying the present invention will be described with reference to the drawings. This embodiment is also an example of a vehicle fuel pump on which an axial motor is mounted. Also in the present embodiment, the circuit board 164 has a substantially rectangular shape that is long in the lateral direction (see FIG. 6), a drive circuit is provided in a region 164 c on the surface, and its long side extends along the outer periphery of the stator coil 60. The arrangement in the bent arc shape is the same as the circuit board 64 (see FIG. 2) of the first embodiment. However, in this embodiment, the shape of the terminal 164a provided on the circuit board 164 is different from that of the first embodiment. Therefore, here, the difference between the present embodiment and the first embodiment will be mainly described, and the description of other parts will be omitted.

  6 is a front view of the circuit board 164, and FIG. 7 is a front view of the terminal 164a. As shown in FIG. 6, a plurality of terminals 164 a for connecting the coil winding 50 are formed on the upper edge of the circuit board 164. As shown in FIG. 7, a welded portion 164b is formed on the terminal 164a. The welded portion 164b is formed in a plate shape elongated in the vertical direction extending upward from the upper end of the circuit board 164. The welded portion 164b is formed such that the width of the upper end portion is slightly larger than the width of other portions. The ends of the coil winding 50 are connected by welding after being wound around the welded portion 164b several times. Since the width of the upper end portion of the welded portion 164b is formed large, the wound coil winding 50 does not come out upward. With such a terminal 164a, it is possible to easily and reliably connect the coil winding 50, and it is possible to improve work efficiency and reduce costs.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

The longitudinal cross-sectional view of the fuel pump of 1st Example. The upper surface schematic diagram which showed arrangement | positioning of the stator of 1st Example. The front view of the circuit board of 1st Example. The principal part enlarged view of FIG. FIG. 5 is a top view of FIG. 4. The front view of the circuit board of 2nd Example. The principal part enlarged view of FIG.

Explanation of symbols

10: Fuel pump 12: Top cover 14: Housing 16: Suction casing 18: Discharge casing 20: Pump casing 22: Impeller 24: Lower surface groove 25: Upper surface groove 26: Recess group 27: Recess group 30: Pump part 32: Sleeve 33: Holder 34: Bearing 35: Holder 36: Bearing 40: Shaft 41: Rotor 42: Rotor magnet 44: Yoke 50: Coil winding 52: Back yoke 54: Core 56: Core magnetic pole 58: Teeth 60: Stator Coil 64: circuit board, 64a: terminal, 64b: taper part, 64c: clamping part 66: terminal 68: discharge port 70: motor part 164: circuit board, 164a: terminal, 164b: welded part

Claims (4)

A disc-shaped rotor having a rotor magnet;
A plurality of stator coils arranged concentrically around a point on the rotation axis of the rotor and disposed opposite the rotor;
A circuit board provided with a drive circuit for driving a plurality of stator coils, and an axial type motor,
An axial type motor characterized in that a surface of a circuit board on which a drive circuit is provided or a back surface thereof faces an outer peripheral surface of a stator coil.   2. The axial type motor according to claim 1, wherein the circuit board is arranged in a circle or arc along the outer peripheral surface of the stator coil. A fuel pump comprising the axial type motor according to claim 1 or 2,
A fuel pump, wherein the circuit board is disposed in a fuel passage.   4. The fuel pump according to claim 3, wherein the fuel discharge port is provided downstream of the circuit board.

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