JP2007325329A - Axial gap type motor and fuel pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the contact of a rotor and a stator coil by axially supporting the rotor without the need for installing a different component, in an axial gap type motor with the stator coil axially arranged with respect to the rotor. <P>SOLUTION: A core upper face 24 opposing the rotor 30 of a core 22 is formed so that a gap between the rotor 30 and the core upper face 24 becomes narrow toward the rotative direction of the rotor 30. Since fluid flows between the rotor 30 and the core upper face 24 accompanied by the rotation of the rotor 30, the fluid is raised in pressure, and the pressure in a direction apart from the core upper face 24 is imparted to the rotor 30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an axial gap type motor and a fuel pump using the axial gap type motor. An “axial gap type motor” refers to a motor in which a rotor and a stator coil are arranged to face each other in the axial direction.

Axial gap motors are used in various devices because the length of the motor in the rotation axis direction can be shortened. The axial gap type motor includes a disk-shaped rotor and a plurality of stator coils. The rotor has a rotor magnet formed in a ring shape around the rotation axis of the motor (rotor). The plurality of stator coils face the rotor magnet in the axial direction, and are arranged at equal intervals on a concentric circle around the rotation axis of the motor (rotor). When the stator coil is energized, a magnetic force is generated in the stator coil, and an attractive force / repulsive force is generated between the stator coil and the rotor magnet. The motor (rotor) rotates by controlling ON / OFF of the current to the plurality of stator coils.
This axial gap type motor is usually provided with a thrust bearing that supports the rotating shaft of the rotor in the axial direction in order to prevent contact between the rotor and the stator coil. As this thrust bearing, a contact-type bearing that is supported in contact with the rotating shaft is usually used. However, when a contact-type thrust bearing is used, the vibration of the rotor is transmitted to the motor main body through the rotating shaft when the rotor rotates, and the vibration of the motor main body is increased. In view of this, a motor that can support the rotation shaft of the rotor in the thrust direction in a non-contact manner when the rotor rotates is proposed (for example, Patent Document 1).

  The motor of Patent Document 1 has a disk-shaped rotor and a plurality of stator coils arranged to face the rotor in the axial direction. On the side of the stator coil opposite to the rotor, a substantially disk-shaped rotating body is arranged coaxially with the rotor. The rotating body is fixed to the rotating shaft of the rotor, and dynamic pressure generating grooves are formed on both surfaces of the rotating body. Further, the surface of the rotating body on which the dynamic pressure generating groove is formed is opposed to the plane of the casing fixed to the stator coil. Therefore, when the rotating body rotates with the rotation of the rotor, dynamic pressure is generated between the rotating body and the casing plane facing both surfaces of the rotating body, and the rotating body is supported in the axial direction without contact. That is, in this motor, the rotating body and the casing plane facing both surfaces of the rotating body serve as a thrust bearing that supports the rotating shaft in the axial direction. In this way, the thrust bearing supports the rotating shaft in a non-contact manner, so that the vibration of the rotor is prevented from being transmitted to the motor body through the rotating shaft, and the vibration of the motor body can be prevented as much as possible.

Japanese Patent Laid-Open No. 8-130851

In the axial gap motor of Patent Document 1, in order to support the rotating shaft of the rotor, a rotating body separate from the rotor must be provided. For this reason, the number of parts increases and the cost increases, and the number of assembling steps also increases.
Further, since the rotating body is fixed to the rotating shaft of the rotor, the length of the motor in the rotating axis direction is increased by the amount of the rotating body. For this reason, the advantage of the axial gap motor (that is, the length of the motor in the direction of the rotation axis) can be reduced.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to support the rotor in the direction of the rotation axis without using a separate component separate from the rotor, thereby rotating the motor. It is to provide a technique capable of preventing the length in the axial direction from becoming long.

In order to solve the above-mentioned problems, a first axial gap type motor of the present invention includes a disc-shaped rotor having a rotor magnet and an annular shape in the rotational direction of the rotor at a position facing one surface of the rotor. A plurality of stator coils arranged, and each stator coil has a core and a coil winding wound around the core. The surface of each core facing the rotor is formed so that the gap between the facing surface and the rotor gradually decreases in the rotation direction of the rotor.
Here, the “rotation direction” means the rotation direction when the rotor is viewed in plan. Therefore, “gradually smaller in the direction of rotation of the rotor” means that when the distance between the point on the core (the point on the opposite surface of the core) and the rotor is measured, This means that the distance between the point and the rotor gradually decreases as the direction changes.
In this motor, when the rotor rotates, the fluid in the gap between the rotor and the core flows in the rotation direction of the rotor. Since the gap between the rotor and the core is gradually reduced in the rotation direction of the rotor, the pressure of the fluid flowing in the gap between the rotor and the core is gradually increased as the gap between the rotor and the core is reduced. Due to the pressure of the fluid, the rotor receives a thrust pressure in a direction away from the core. Thus, the rotor is supported in the thrust direction. Therefore, in this motor, the rotor can be supported in the thrust direction without using separate parts separate from the rotor.

It is preferable that the surface of the core of each stator coil facing the rotor is formed so that the gap between the facing surface and the rotor gradually increases toward the outer side in the radial direction of the rotor. In this configuration, the fluid flowing into the gap between the rotor and the core can be increased outside the rotor in the radial direction.
Further, at this time, it is preferable that the rate of change of the gap between the facing surface and the rotor of the surface of each stator coil core facing the rotor gradually increases toward the outer side in the radial direction of the rotor. According to such a configuration, the flow rate cross-sectional area of the fluid flowing in the radially outer side of the rotor has a higher rate of change than the flow channel cross-sectional area of the fluid flowing in the radially inner side (the rate at which the flow channel becomes narrower). large). As a result, the pressure of the fluid flowing radially outside the rotor is increased higher than the pressure of the fluid flowing radially inside. Therefore, the thrust pressure received by the rotor from the fluid can be increased toward the outer side in the radial direction of the rotor.

The second axial gap type motor of the present invention supports the rotor in the thrust direction by forming a groove on the surface of each core facing the rotor. That is, the second axial gap type motor of the present invention includes a disk-shaped rotor having a rotor magnet and a plurality of stators arranged in an annular shape in the rotational direction of the rotor at a position facing one surface of the rotor. Each stator coil has a core and a coil winding wound around the core. A groove extending in the rotation direction of the rotor is formed on a surface of each core facing the rotor, and at least an end of the groove on the rotation direction side is closed.
In this motor, when the rotor rotates, the fluid in the groove flows in the groove toward the rotation direction of the rotor. Since the end of the groove in the rotational direction is closed, the fluid flowing in the rotational direction in the groove collides with the end of the groove in the rotational direction, and flows out of the groove into the gap between the rotor and the core. Thereby, a thrust pressure in a direction away from the core is applied to the rotor, and the rotor is supported in the thrust direction. Therefore, even in this motor, the rotor can be supported in the thrust direction without using separate parts separate from the rotor.

  In addition, you may form the groove | channel formed in the surface facing the rotor of a core so that a cross-sectional area may become small in a rotation direction. Since the flow path becomes narrower as the fluid flowing into the groove flows in the groove, the pressure of the fluid flowing in the groove can be further increased. Therefore, the fluid that hits the downstream end of the groove and flows out of the groove can apply a higher pressure to the rotor. Therefore, the thrust in the thrust direction that the rotor receives from the fluid can be further increased.

In addition, when a plurality of grooves are formed on the surface of the core facing the rotor at intervals in the radial direction, the depth of the groove located on the radially outer side is the groove formed on the radially inner side. It is preferable that it is formed deeper.
As the depth of the groove increases, the flow rate of the fluid flowing into the groove increases. For this reason, the flow rate of the fluid that collides with the downstream end (end portion on the rotation direction side) of the groove and flows out of the groove is also larger on the outer side than on the inner side in the radial direction of the rotor. Therefore, the thrust force opposite to the core received by the rotor is greater on the outer side than on the inner side in the radial direction. Thereby, the inclination of the rotor can be suitably prevented.

The third axial gap type motor of the present invention supports the rotor in the thrust direction by forming a groove on the surface facing the core of the rotor. That is, the third axial gap type motor of the present invention has a disk-shaped rotor having a rotor magnet and an annular shape at a position facing one surface of the rotor with a predetermined interval in the rotational direction of the rotor. A plurality of stator coils arranged, and each stator coil has a core and a coil winding wound around the core. The surfaces of the cores facing the rotor are arranged on the same plane, and the gap between adjacent cores is closed by a nonmagnetic material in the plane. And the groove | channel extended in the rotation direction of a rotor is formed in the surface facing the core of a rotor, and the edge part by the side of the counterclockwise rotation direction of the rotor of the groove | channel is closed.
In this motor, when the rotor rotates, the fluid in the groove formed on the surface facing the rotor core (rotor side facing surface) flows from the upstream end (rotation direction end) to the downstream end (counter rotation direction side). Flows in the groove toward the end) and hits the downstream end. The fluid hitting the downstream end flows out toward the surface of the core facing the rotor (core-side facing surface), and pressurizes the fluid in the gap between the rotor facing surface and the core facing surface. Thereby, a thrust force in a direction away from the core is applied to the rotor. Therefore, even in this motor, the rotor can be supported in the thrust direction without using separate parts separate from the rotor. In this motor, the surfaces of the cores facing the rotor are arranged on the same plane, and the gap between adjacent cores is closed by a nonmagnetic material in the plane. This prevents the fluid that has flowed out of the groove formed in the rotor toward the core-side facing surface from flowing into the gap between the adjacent cores, and the fluid in the gap between the rotor-side facing surface and the core-side facing surface. Is preferably boosted.

  Furthermore, the groove formed in the rotor is preferably formed so that the cross-sectional area increases as it goes in the rotation direction. Since the flow of the fluid flowing into the groove becomes narrower from upstream to downstream, the pressure of the fluid flowing in the groove increases. Therefore, the pressure of the fluid flowing out from the downstream end of the groove toward the core side facing surface can be further increased.

Further, the end of the groove formed in the rotor on the rotational direction side of the rotor is opened, and the open position is provided radially inward from the inner peripheral edge of the core or radially outward from the outer peripheral edge of the core. It is preferable.
The end of the groove is opened, and the opened end is provided on the inner side or the outer side in the radial direction from the region facing the rotor core, so that the fluid flows into the groove without being interrupted by the core. Can do. Thereby, the flow rate of the fluid flowing out from the groove is increased, and the pressure of the fluid in the gap between the rotor-side facing surface and the core-side facing surface is further increased.

The present invention also provides another axial gap type motor for solving the above-described problems. That is, another axial gap type motor of the present invention includes a disk-shaped rotor having a rotor magnet, and a plurality of stator coils arranged annularly in the rotational direction of the rotor at a position facing one surface of the rotor. Each stator coil has a core and a coil winding wound around the core. At least one of the core-side facing surface facing the rotor of each core or the rotor-side facing surface facing each core of the rotor is a fluid that flows in a gap between the rotor-side facing surface and the core-side facing surface when the rotor rotates. Thus, a force in a direction in which the rotor-side facing surface and the core-side facing surface are separated from each other is generated.
Also in this motor, a force in a direction in which the core-side facing surface and the rotor-side facing surface are separated is generated by the fluid flowing through the gap between the rotor and the core according to the rotation of the rotor. Thereby, the rotor can be supported in the thrust direction.

The axial gap type motor described above can be used as a fuel pump motor.
That is, the fuel pump of the present invention includes any of the above-described axial gap type motors, and includes a casing that houses the rotor of the axial gap type motor. A blade groove that repeats in the circumferential direction is formed on at least one surface of the rotor, and a region facing the blade groove of the rotor is formed on the surface facing the rotor of the casing at the upstream end along the rotation direction of the rotor. A pump passage extending from the downstream end to the downstream end is formed. The casing is formed with a suction port that communicates the upstream end of the pump flow path and the outside of the casing, and a discharge port that communicates the downstream end of the pump flow path and the outside of the casing.
By forming the blade grooves in the rotor, the impeller function of the fuel pump can be imparted to the rotor. As a result, the rotor and the impeller need not be provided as separate parts, and the fuel pump can be downsized. Further, since the rotor is supported in the thrust direction, contact between the rotor (impeller) and the casing is prevented, and wear and noise of the impeller can be reduced.

The main features of the techniques described in the following examples are listed.
(Embodiment 1) The groove formed on the surface of the core facing the rotor is formed so that its cross-sectional area decreases as it goes in the rotational direction of the rotor.
(Mode 2) The groove formed on the surface facing the core of the rotor is formed so that its cross-sectional area increases as it goes in the rotational direction of the rotor.
(Mode 3) The rotor is composed of a yoke and a magnet arranged on the core side surface of the yoke. The yoke and the magnet are entirely covered with resin.
(Form 4) The impeller of the fuel pump does not have a rotating shaft.

An axial gap type motor 10 embodying the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a main part of the motor 10. As shown in FIG. 1, the motor 10 includes a stator unit 20 and a rotor unit 30.
The rotor unit 30 includes a substantially disc-shaped rotor 31 and a rotating shaft 32 fitted in the center of the rotor 31. Both ends of the rotating shaft 32 are rotatably supported by bearings 32a and 32b. The bearings 32 a and 32 b are fixed to a case (not shown) that houses the stator unit 20 and the rotor unit 30. For this reason, the rotor part 30 can rotate with respect to a case (namely, stator part 20).
The rotor 31 has a substantially disk-shaped yoke 31 a centering on the rotation axis of the rotation shaft 32. A rotating shaft 32 is fitted in the center of the yoke 31a. A magnet 33 is fixed to the lower surface of the yoke 31a (the lower surface in FIG. 1). The magnet 33 is a ring-shaped permanent magnet and is arranged concentrically with the yoke 31a. The outer diameter of the magnet 33 substantially matches the outer diameter of the yoke 31a, and the inner diameter of the magnet 33 substantially matches the inner diameter of the upper surface 24 of the core 22 described later. The yoke 31a and the magnet 33 are entirely covered with a resin mold 31b. The outer shape of the rotor 31 covered with the resin mold 31b has a substantially disk shape.

  As shown in FIG. 2, the stator unit 20 includes stator coils 21 that are arranged at equal intervals in the circumferential direction of the rotor 31 around the rotation axis of the rotation shaft 32. The stator coil 21 includes a core 22 and a coil winding 23 wound around the core 22. The stator coil 21 has the lower surface of the core 22 fixed to a case (not shown) by bonding or the like. The upper surface 24 of the core 22 (hereinafter referred to as the core upper surface) faces the rotor 31. As shown in FIG. 2, six stator coils 21 are arranged in the stator portion 20, but since all the stator coils 21 have the same structure, only one stator coil 21 is indicated by a reference numeral in FIG. 2. It is attached.

  As shown in FIG. 2, the core upper surface 24 has a fan shape when seen in a plan view, and the length in the circumferential direction (that is, the length of the arc) becomes longer toward the outer side in the radial direction. As shown in FIG. 3, the core upper surface 24 is inclined with respect to the lower surface of the rotor 31 when viewed from the side. This inclination is such that the gap between the core upper surface 24 and the lower surface of the rotor 31 decreases as the rotation direction 31c of the rotor 31 (see FIG. 2), that is, from the first end side 24f of the core upper surface 24 toward the second end side 24g. It is formed to become. For example, the gap between the first inner peripheral end 24 a of the core upper surface 24 and the lower surface of the rotor 31 is larger than the gap between the second inner peripheral end 24 b of the core upper surface 24 and the lower surface of the rotor 31. The gap between the first outer peripheral end 24 c and the lower surface of the rotor 31 is made larger than the gap between the second outer peripheral end 24 d of the core upper surface 24 and the lower surface of the rotor 31. Further, the gap is formed between the core upper surface 24 and the lower surface of the rotor 31 in the radial direction of the rotor 31, that is, from the inner peripheral edge to the outer peripheral edge of the core upper surface 24. That is, the core upper surface 24 is formed such that the inclination angle with respect to the rotor 31 increases as it goes outward in the radial direction of the rotor 31. Note that, at the second end side 24 g of the core upper surface 24, the gap between the core upper surface 24 and the lower surface of the rotor 31 is substantially constant. For example, the gap between the second inner peripheral end 24 b of the core upper surface 24 and the lower surface of the rotor 31 is substantially the same as the gap between the second outer peripheral end 24 d of the core upper surface 24 and the lower surface of the rotor 31.

  Next, the operation at the time of driving the motor 10 will be described. The coil winding 23 of the stator coil 21 is energized from an external power supply (not shown) via a control device (not shown). The rotor 31 is rotationally driven by turning ON / OFF the energization of each stator coil 21 by the control device. When the rotor 31 rotates, the fluid in the gap between the lower surface of the rotor 31 and the core upper surface 24 flows according to the rotation of the rotor 31. That is, the fluid in the gap between the rotor 31 and the core upper surface 24 flows from the first end side 24f toward the second end side 24g due to the rotation of the rotor 31 due to its viscosity. Since the core upper surface 24 is inclined with respect to the rotor 31, the flow path cross-sectional area of the fluid (that is, the gap between the lower surface of the rotor 31 and the core upper surface 24) is downstream (first end 24f) from the downstream (first end 24f). It becomes smaller as it goes to the two end sides 24g). Therefore, the pressure of the fluid in the gap between the lower surface of the rotor 31 and the core upper surface 24 is increased from upstream to downstream. The fluid pressurized in the gap between the lower surface of the rotor 31 and the core upper surface 24 gives the rotor 31 pressure to push the rotor 31 upward (that is, the side opposite to the core upper surface 24). Due to the pressure of the fluid, the rotor 31 can rotate without contacting the core upper surface 24. Moreover, since the change of the flow path cross-sectional area of the fluid is larger on the outer side in the radial direction than on the inner side, the pressure can be increased toward the outside. As a result, a large upward force acts on the outside of the rotor 31, and the rotor 31 is preferably suppressed from contacting the core upper surface 24. The pressure of the fluid flowing between the lower surface of the rotor 31 and the core upper surface 24 depends on the size of the motor 10, the shape of the core upper surface 24, the type of fluid, the rotational speed of the rotor 31, and the desired pressure. As described above, the above conditions can be arbitrarily changed.

The same effect can be obtained when the shape of the core upper surface is other than the shape of the core upper surface 24 described above. For example, also in the core 300 shown in FIG. 11, the lower surface of the rotor 31 and the upper surface 301 of the core are moved from the upstream end side to the downstream end side of the fluid flowing by the rotation of the rotor 31 (that is, in the rotational direction 31 c of the rotor 31) The gap is formed to be small. In the core 300, a step 301 a that increases the gap between the rotor 31 and the core upper surface 301 is formed in the approximate center between the upstream end and the downstream end of the core 300. The gap between the rotor 31 and the core upper surface 301 is formed so as to decrease from the upstream end of the core upper surface 301 toward the step 301a, and further, from the lowermost part 301b of the step 301a toward the downstream end of the core upper surface 301. The gap between the rotor 31 and the core upper surface 301 is formed to be small. Even when such a core 300 is used, the fluid between the rotor 31 and the core upper surface 301 is pressurized and contact between the rotor 31 and the core upper surface 301 is prevented.
Furthermore, the core 400 shown in FIG. 12 can also be used. In the core 400, a part of the core upper surface 401 (in FIG. 12, intermediate between the upstream end and the downstream end of the core 400) is inclined with respect to the rotor 31, and the inclination is from the upstream side to the downstream side of the flowing fluid. The rotor 31 and the core upper surface 401 are formed so as to become smaller toward the head (that is, in the rotation direction 31c of the rotor 31). Even in such a core 400, the fluid in the gap between the rotor 31 and the core upper surface 401 is pressurized, and the rotor 31 can be pushed upward.

In the motor 10 described above, the fluid flowing between the rotor 31 and the core upper surface 24 is pressurized by inclining the core upper surface 24 with respect to the rotor 31. However, as shown in FIG. 4, the fluid flowing between the rotor and the upper surface of the core can be pressurized by forming a groove on the surface (the upper surface of the core) facing the rotor of the core. FIG. 4 is a view of the stator portion having a groove formed on the upper surface of the core as viewed from above. Here, since the configuration other than the shape of the upper surface of the core is the same as that of the first embodiment, the description thereof is omitted. Moreover, the same code | symbol is used for the part of the same structure as the motor 10, and the description is abbreviate | omitted.
As shown in FIG. 4, each core upper surface 50 has a fan shape when seen in a plan view, and the length in the circumferential direction becomes longer toward the outer side in the radial direction. The core upper surface 50 is parallel to the rotor 31. Grooves 51 and 52 extending in the rotational direction of the rotor 31 are formed on the core upper surface 50 (however, not all of the core upper surfaces and grooves are labeled in FIG. 4). The grooves 51 and 52 are formed so that the cross-sectional area decreases in the rotation direction of the rotor 31. The groove 51 on the outer side in the radial direction of the core is formed deeper than the inner groove 52.

  The fluid in the gap between the rotor 31 and the core upper surface 50 flows according to the rotation of the rotor 31. The fluid in the grooves 51 and 52 formed on the core upper surface 50 flows from the upstream ends 51 a and 52 a toward the downstream ends 51 b and 52 b by the rotation of the rotor 31. The fluid reaching the downstream ends 51b and 52b collides with the downstream ends 51b and 52b, and flows upward from the grooves 51 and 52, that is, from the grooves 51 and 52 toward the rotor 31. Therefore, the rotor 31 receives an upward pressure from the fluid flowing out of the grooves 51 and 52. Due to the pressure of the fluid, the rotor 31 can rotate without contacting the core upper surface 50. At this time, the fluid in the grooves 51 and 52 becomes narrower as it goes downstream, so that the fluid flowing in the groove is pressurized as it goes downstream. Thereby, the pressure which pushes the rotor 31 upward is made higher. In addition, since the groove 51 is formed deeper than the groove 52, the pressure for pushing up the rotor 31 of the fluid flowing out from the groove 51 is higher than that of the fluid flowing out from the groove 52. For this reason, a large upward force acts on the outside of the rotor 31, and the rotor 31 is preferably prevented from contacting the core upper surface 50.

A core having both the shape of the core upper surface 24 of the first embodiment and the shape of the core upper surface 50 of the second embodiment may be used. That is, the upper surface of the core is inclined from upstream to downstream in the same manner as the upper surface 24 of the core, and grooves similar to the upper surface 50 of the core are formed on the surface. Thereby, the pressure of the fluid between a rotor and a core upper surface can be raised more, and a rotor can be supported suitably in a thrust direction.
Further, the grooves 51 and 52 may extend to the downstream side edge of the core upper surface 50 without the downstream ends 51b and 52b being closed. At this time, the cross-sectional area of the groove decreases from upstream to downstream. By reducing the cross-sectional area, the fluid flowing in the groove is pressurized and flows out into the gap between the rotor 31 and the core upper surface 50, whereby the fluid in the gap between the rotor 31 and the core upper surface 50 is pressurized. Thereby, the fluid in the gap between the rotor 31 and the core upper surface 50 can apply an upward force to the rotor 31.

In the motor described above, an upward force is applied to the rotor by inclining the surface of the core facing the rotor or forming a groove. However, in the present invention, a groove may be formed on the surface facing the core of the rotor. Such an axial gap type motor 100 will be described with reference to FIGS. FIG. 5 is a view of the stator unit 120 used in the motor 100 as viewed from the upper side (that is, the rotor 110 side), and FIG. 6 is a bottom view of the rotor 110 used in the motor 100.
As shown in FIG. 5, the stator section 120 has a plurality of stator coils 121 each having a core 122 and a coil winding 123, as in the first embodiment, and these stator coils 121 are centered on a rotating shaft 111 of the rotor. It is arranged in a ring. A space 124 between the stator coils 121 adjacent in the circumferential direction (hereinafter referred to as between the cores) is filled with a non-magnetic material (for example, resin). The upper surface (surface on the rotor 110 side) of the nonmagnetic material filled between the cores 124 is flush with the upper surface of the core 122.

  On the lower surface of the rotor 110 (that is, the surface facing the core 122 of the rotor 110), as shown in FIG. 6, a recess 110e that has a ring shape when the rotor 110 is viewed from below is formed. A rotation shaft 32 is fixed at the center of the recess 110e. The outer diameter of the recess 110 e is smaller than the inner diameter of the upper surface 1 of the core 122. A groove 110a extending from the outer peripheral edge of the recess 110e toward the outside of the rotor 110 is formed on the outer peripheral portion of the recess 110e. The inner peripheral end 110b of the groove 110a opens into the recess 110e. The groove 110a extends radially outward and in the circumferential direction (specifically, the counter-rotating direction of the rotor 110), and the outer peripheral end 110c of the groove 110a is closed. Further, the groove 110a is formed so that the cross-sectional area gradually increases in the rotation direction 110d of the rotor 110 (that is, the cross-sectional area gradually decreases in the counter-rotation direction of the rotor 110). A plurality of grooves 110a are formed at intervals in the circumferential direction of the rotor 110 (however, in FIG. 6, not all grooves and stator coils are denoted by reference numerals).

The fluid in the groove 110 a flows from the inner peripheral end 110 b of the groove 110 a toward the outer peripheral end 110 c according to the rotation of the rotor 110. The fluid flowing in the groove 110 a is pressurized in accordance with the change in the cross-sectional area of the groove 110. Then, the fluid that hits the downstream end 110c of the groove 110a flows out between the rotor 110 and the upper surface of the core 122 from the groove 110a, and pressurizes the fluid in the gap between the rotor 110 and the upper surface of the core 122. Since the pressurized fluid pushes up the rotor 110 in the opposite direction to the core 122, the rotor 110 can be rotated without contacting the core 122.
In this embodiment, since the inner peripheral end 110b of the groove 110a is opened to the recess 110e, the fluid in the recess 110e can smoothly flow into the groove 110a. Further, the groove 110 a extends toward the outside of the rotor 110 and extends in the counter-rotating direction of the rotor 110. For this reason, centrifugal force and inertial force due to rotation of the rotor 110 act on the fluid in the groove 110a, and the fluid flows smoothly in the groove 110a from the inner peripheral end 110b to the outer peripheral end 110c. For this reason, the flow rate of the fluid flowing in the groove 110a can be increased, and the upward force acting on the rotor 110 can be increased.

Moreover, the groove | channel formed in a rotor is not restricted to said example, A groove | channel as shown in FIG. 7 can also be formed. In the rotor 130 shown in FIG. 7, the lower surface of the rotor 130 (i.e., the surface facing the core 122 of the rotor 130) from the outer periphery of the rotor 130 to the center and circumferential direction of the rotor 130 (specifically, the counter rotation of the rotor 130 is reversed). Grooves 130a extending in the direction) are formed. A plurality of grooves 130 a are formed at intervals in the circumferential direction of the rotor 130. The outer peripheral end 130b of the groove 130a opens to the outer peripheral edge of the rotor 130, and the inner peripheral end 130c of the groove 130a is closed. The cross-sectional area of the groove 130a gradually increases toward the rotation direction 130d of the rotor 130 (that is, gradually decreases in the counter-rotation direction of the rotor 130).
Even when the rotor 130 is used, when the rotor 130 rotates, the fluid flows in the groove 130a while being pressurized from the outer peripheral end 130b toward the inner peripheral end 130c, and flows out from the inner peripheral end 130c to the rotor 130 side. As a result, an upward force is applied to the rotor 130, and the rotor 130 is supported in the thrust direction. In this rotor 130, since the outer peripheral end 130b of the groove 130a opens to the outer peripheral edge of the rotor 130, more fluid can be smoothly introduced into the groove 130a than the outside of the rotor 130. Thereby, the rotor 130 can be suitably supported in the thrust direction.

Furthermore, in addition to the rotor 130 described above, a rotor 500 as shown in FIGS. 13 and 14 can also be used. In the rotor 500, a plurality of inclined portions 501 are formed on the surface facing the core of the rotor 500. These inclined portions 501 are continuously provided in the radial direction of the rotor 500. As shown in FIG. 14, each inclined portion 501 is formed such that a gap between the rotor 501 and the core upper surface 502 increases as the direction of rotation of the core 500 a progresses.
Also with this configuration, the fluid in the gap between the rotor 500 and the core upper surface 502 can be boosted. That is, when the rotor 500 rotates, fluid flows between the rotor 500 and the core upper surface 502 in the counter-rotating direction of the rotor 500. The fluid flowing between the rotor 500 and the core upper surface 502 is pressurized by each inclined portion 501 and gives an upward force to the rotor 500. Thereby, the rotor 500 can be rotated without being brought into contact with the core upper surface 502.

Each motor mentioned above can be used conveniently for a fuel pump. The embodiment described next is an example of a vehicle fuel pump using an axial type motor. The fuel pump 200 of this embodiment is for an automobile and is installed in a fuel tank mounted on the automobile. In a state where the fuel pump 200 is installed in the fuel tank, the lower surface of the fuel pump 200 contacts the bottom surface of the fuel tank. The fuel pump 200 operates in a state where it is immersed in fuel, and pumps the fuel in the fuel tank to the engine.
FIG. 8 is a longitudinal sectional view of the fuel pump 200. As shown in FIG. 8, the fuel pump 200 includes an impeller 210 and a stator unit 230. The impeller 210 and the stator unit 230 are accommodated in the pump casing 220. The pump casing 220 includes a housing 221, a pump base 222, and a pump cover 223. A pump base 222 is attached to the lower end of the substantially cylindrical housing 221, and a pump cover 223 is attached to the upper end.

As shown in FIG. 9, the impeller 210 is formed in a substantially disc shape. The impeller 210 has a substantially disk-shaped yoke 212, and a magnet 213 is attached to the lower surface of the yoke 212. The magnet 213 is a ring-shaped permanent magnet and is arranged concentrically with the yoke 212. The outer diameter of the magnet 213 substantially matches the outer diameter of the yoke 212, and the inner diameter of the magnet 213 substantially matches the inner diameter of the upper surface of the core 231 described later. The yoke 212 and the magnet 213 are entirely covered with a resin mold 214.
On the outer peripheral portion of the impeller 210 (resin mold 214), blade groove portions 215 and 216 are formed on both the upper and lower surfaces in the circumferential direction. The blade groove portion 215 formed on the upper surface of the impeller 210 communicates with the blade groove portion 216 formed on the lower surface of the impeller 210 at the bottom.
The impeller 210 is accommodated in a recess 223 a formed on the lower surface of the pump cover 223. The recess 223a has substantially the same outer diameter as the impeller 210, and the depth thereof is substantially the same as the thickness of the impeller 210. A slight gap is formed between the outer periphery of the impeller 210 and the recess 223a (not shown in FIG. 8). This gap is provided for the impeller 210 to rotate smoothly. In addition, a first groove portion 224 extending from the upstream end to the downstream end along the rotation direction of the impeller 210 is formed on the lower surface of the pump cover 223 in a region facing the blade groove portion 215 of the impeller 210. The downstream end of the first groove portion 224 communicates with a discharge port 225 that penetrates the pump cover 223 up and down.
A recess 210d having a circular cross section is formed at the center of the lower surface of the impeller 210 (see FIG. 9). On the lower surface of the impeller 210, a groove 210a is formed in a region inside the blade groove 215 and outside the recess 210d. The groove 210a extends in the radial direction and the circumferential direction (specifically, the counter-rotating direction of the impeller 210) from the outer peripheral edge of the recess 210d. The groove 210a is formed so that the cross-sectional area decreases from the inner peripheral end toward the outer peripheral end. A plurality of grooves 210 a are formed at intervals in the circumferential direction of the impeller 210.

  The stator unit 230 includes a stator coil 233 having a core 231 and a coil winding 232 wound around the core 231. The stator coils 233 are arranged concentrically with the impeller 210 at equal intervals in the circumferential direction. The lower surface of the stator coil 233 is fixed on the pump base 222. A space formed by the stator coil 233, the housing 221, and the pump base 222 is filled with a resin 240 that is a non-magnetic material. The top surface of the filled resin 240 is flush with the top surface of the core 231. As a result, the resin 240 is filled between the adjacent stator coils 233, and a flat surface 240a facing the lower surface of the impeller 210 is formed by the filled resin 240 and the upper surface of the core of the stator coil 233. A second groove portion 241 that extends from the upstream end to the downstream end along the rotation direction of the impeller 210 is formed in the plane 240 a in a region facing the blade groove portion 215 of the impeller 210. The upstream end of the second groove portion 241 communicates with a suction port 221 a formed in the housing 221 via a suction path 242.

  Similar to the motor, the coil winding 232 of the stator coil 233 is energized from the outside. The impeller 210 rotates by turning ON / OFF the energization of each stator coil 233. When the impeller 210 rotates, fuel is sucked into the casing 220 through the suction port 221a and the suction path 242. While the fuel sucked into the casing 220 flows through the second groove portion 241 and the first groove portion 224, the pressure is increased with the rotation of the impeller 210, and the fuel is discharged from the discharge port 225 to the outside of the pump. Further, the fuel sucked into the casing 220 flows into the gap between the impeller 210 and the flat surface 240a. At this time, the fuel also flows into the groove 210 a formed in the impeller 210. The fuel in the groove 210a flows from the upstream end 210b toward the downstream end 210c as the impeller 210 rotates (see FIG. 9). The fuel flowing in the groove 210a gradually increases in pressure from the upstream end 210a toward the downstream end 210c because the cross-sectional area (fluid flow path) of the groove 210a gradually decreases from the upstream end 210a toward the downstream end 210c. The Then, the fuel that has hit the downstream end 210c flows out between the impeller 210 and the stator coil 233 from the groove 210a. At this time, a downward pressure (that is, an upward pressure on the impeller 210) is applied to the stator coil 233. Thereby, the impeller 210 can rotate without contacting with the stator coil 233.

  The positioning accuracy in the axial direction of the impeller of the fuel pump is required to be within 10 to 20 μm. On the other hand, since the axial positioning accuracy of the rotor of the axial gap type motor is affected by the dimensional accuracy of various components such as the rotor, each stator coil, and the case, the positioning of the rotor in the axial direction with respect to the stator coil is 10 to 20 μm. It was difficult to do within. However, in the structure of the present embodiment, the magnetic attraction force generated between the magnet 213 of the impeller 210 (rotor) and the core 231 causes the impeller 210 to approach the core 231 and the groove 210 a formed in the impeller 210. By flowing the fuel, a force in a direction away from the core 231 is applied to the impeller 210 to support the impeller 210 with respect to the core 231. For this reason, the position of the impeller 210 in the axial direction with respect to the core 231 is determined by the balance between the magnetic attraction force and the force in the direction away from the core 231 from the impeller 210. Accordingly, the axial positioning of the impeller 210 can be performed within 10 to 20 μm. For this reason, in the fuel pump 200 of the present embodiment, the impeller 210 and the rotor can be integrally formed. Therefore, the fuel pump can be reduced in size and simplified. Further, by integrating the impeller and the rotor, a shaft for transmitting the rotation of the rotor to the impeller is not necessary, and the structure can be simplified.

  In addition, the fuel pump 200 of the present embodiment prevented the contact between the impeller 210 and the stator coil 233 by forming the groove 210a in the impeller 210. However, any of the above-described axial gap motors may be used for the fuel pump of the present invention. For example, an inclination similar to the core upper surface 24 shown in FIGS. 1 to 3 may be formed on the core upper surface facing the impeller of the core of the stator coil, or a groove similar to the core upper surface 50 shown in FIG. 4 may be formed. May be. Also, an impeller 250 as shown in FIG. 10 can be used.

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 exemplified in this specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

1 is a longitudinal sectional view of an axial gap type motor 10 of the present embodiment. The same figure which looked at the stator part 20 from the upper side. The side view of the axial gap type motor 10 of a present Example. The figure which looked at the stator part of the other Example of the axial gap type motor 10 from the upper side. The figure which looked at the stator part 120 of the axial gap type motor 100 of a present Example from the upper side. The top view which looked at the rotor 110 from the bottom same as the above. The top view which looked at the rotor part of the other Example of the axial gap type motor 100 from the lower side. The longitudinal cross-sectional view of the fuel pump 200 of a present Example. The figure which looked at the impeller 210 from the lower side. The figure which looked at the impeller of the other Example of the fuel pump 20 from the lower side. The side view of the motor which shows the other core upper surface of a 1st motor. Same as above The figure which looked at the rotor which shows the other rotor of a 2nd motor from the lower side. IV-IV sectional drawing of FIG.

Explanation of symbols

10: Axial gap type motor 20 of the first embodiment 20: Stator section 21: Stator coil 22: Core 30: Rotor section 50: Core upper surfaces 51, 52 of other embodiments of the core 50: Groove 100 formed on the core upper surface 50 Axial gap type motor 110 of the second embodiment 110: Rotor portion 110a: Groove 120 formed on the lower surface of the rotor 120: Stator portion 124: Inter-core portion 130: Other rotor 200: Fuel pump 210: Impeller 210a: Lower surface of the impeller Grooves 215, 216 formed on the blade: vane groove portion 230: stator portion 250: other impeller 300: other core

Claims (9)

A disc-shaped rotor having a rotor magnet;
A plurality of stator coils arranged annularly in the rotational direction of the rotor at a position facing one surface of the rotor,
Each stator coil has a core and a coil winding wound around the core,
An axial gap type motor characterized in that a surface of each core facing the rotor is formed such that a gap between the facing surface and the rotor is gradually reduced in the rotation direction of the rotor.   The surface of each stator coil facing the rotor is formed such that a gap between the facing surface and the rotor is gradually increased toward a radially outer side of the rotor. Axial gap type motor.   The surface of each stator coil facing the rotor is formed such that the rate of change of the gap between the facing surface and the rotor is gradually increased toward the outer side in the radial direction of the rotor. 2. An axial gap type motor described in 2. A disc-shaped rotor having a rotor magnet;
A plurality of stator coils arranged annularly in the rotational direction of the rotor at a position facing one surface of the rotor,
Each stator coil has a core and a coil winding wound around the core,
An axial gap type motor characterized in that a groove extending in the rotation direction of the rotor is formed on a surface of each core facing the rotor, and at least an end of the rotation direction side of the rotor is closed. . The axial gap type motor according to claim 4, wherein a plurality of grooves are formed on the surface of each core facing the rotor at intervals in the radial direction.
An axial gap type motor characterized in that the depth of the groove formed on the radially outer side is deeper than that of the groove formed on the radially inner side. A disc-shaped rotor having a rotor magnet;
A plurality of stator coils arranged in a ring at a predetermined interval in the rotation direction of the rotor at a position facing one surface of the rotor;
Each stator coil has a core and a coil winding wound around the core,
The surface of each core facing the rotor is arranged on the same plane, and the gap between adjacent cores is closed by a nonmagnetic material in the plane,
An axial gap type motor characterized in that a groove extending in the rotation direction of the rotor is formed on a surface facing the core of the rotor, and an end of the groove on the side opposite to the rotation direction of the rotor is closed.   An end of the groove in the rotational direction of the rotor is open, and the open position is provided radially inward from the inner peripheral edge of the core or radially outward from the outer peripheral edge of the core. The axial gap type motor according to claim 6. A disc-shaped rotor having a rotor magnet;
A plurality of stator coils arranged annularly in the direction of rotation of the rotor at a position facing one surface of the rotor,
Each stator coil has a core and a coil winding wound around the core,
At least one of the core-side facing surface that faces the rotor of each core or the rotor-side facing surface that faces each core of the rotor is rotated by the fluid that flows through the gap between the rotor-side facing surface and the core-side facing surface when the rotor rotates. An axial gap type motor characterized in that a force in a direction in which the side facing surface and the core side facing surface are separated is generated. An axial gap type motor according to any one of claims 1 to 8,
A casing that accommodates the rotor of the axial gap motor, and
A blade groove that repeats in the circumferential direction is formed on at least one surface of the rotor,
On the surface facing the rotor of the casing, a pump channel extending from the upstream end to the downstream end along the rotation direction of the rotor is formed in a region facing the rotor groove of the rotor,
A fuel pump, characterized in that a suction port that communicates the upstream end of the pump flow path and the outside of the casing and a discharge port that communicates the downstream end of the pump flow path and the outside of the casing are formed in the casing.

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