WO2018062005A1

WO2018062005A1 - Motor and electric power steering device

Info

Publication number: WO2018062005A1
Application number: PCT/JP2017/034193
Authority: WO
Inventors: 佳明山下
Original assignee: 日本電産株式会社
Priority date: 2016-09-30
Filing date: 2017-09-22
Publication date: 2018-04-05
Also published as: CN109716631A; JP7031595B2; JPWO2018062005A1; CN109716631B

Abstract

A motor provided with: a shaft that rotates about a center axis extending in the vertical direction; a bearing for supporting the top end of the shaft; a metal heat sink for directly or indirectly holding the bearing; a substrate disposed on the upper side of the heat sink; a sensor magnet fixed to the shaft at the top end of the shaft above the bearing; a rotation sensor mounted in a position overlapping the sensor magnet of the substrate viewed from the axial direction; and a heat-dissipating material positioned between the substrate and the heat sink, the heat sink being provided with a through hole passing in the vertical direction, the bearing and the sensor magnet being accommodated in the through hole, and a cover covering at least a part of the opening on the upper side of the through hole being attached to the heat sink.

Description

Motor and electric power steering apparatus

The present invention relates to a motor and an electric power steering apparatus.

Generally, a motor in which a control unit is mounted on one end side of an output shaft is known (for example, Patent Document 1). Such a motor has a magnet (sensor magnet) at the end of the output shaft, and detects the rotation angle of the output shaft by means of a magnetic rotation sensor arranged opposite to the magnet.

Japanese Patent No. 5414869

Patent Document 1 describes that a bearing holder serves as a heat sink. That is, the bearing holder is in close contact with the lower surface of the control unit (for example, the substrate) and radiates heat generated by the control unit. The bearing holder is provided with a through hole for arranging the magnet so as to face the control unit. The through hole is a factor that reduces the heat transfer efficiency between the bearing holder and the control unit in order to reduce the area where the bearing holder and the control unit face each other.

In view of the above problems, one aspect of the present invention is to provide a motor that can efficiently dissipate heat generated in a substrate, and an electric power steering device including such a motor. .

One aspect of the motor of the present invention includes a shaft that rotates about a central axis extending in the vertical direction, a bearing that supports the upper end of the shaft, and a metal heat sink that directly or indirectly holds the bearing. And a substrate disposed above the heat sink, a sensor magnet fixed to the shaft above the bearing at the upper end of the shaft, and a position overlapping the sensor magnet of the substrate when viewed from the axial direction. A rotation sensor mounted; and a heat dissipating material positioned between the substrate and the heat sink. The heat sink has a through-hole penetrating in a vertical direction and accommodating the bearing and the sensor magnet. The heat sink is attached with a lid that covers at least a part of the upper opening of the through hole. That.

According to one aspect of the present invention, a motor capable of efficiently dissipating heat generated in a substrate and an electric power steering apparatus including such a motor are provided.

Sectional drawing which shows the motor of embodiment. The expanded sectional view of the motor which expanded a part of FIG. The expanded sectional view of the motor of a modification. The schematic diagram which shows the electric power steering apparatus of embodiment.

Hereinafter, a motor according to an embodiment of the present invention will be described with reference to the drawings. The scope of the present invention is not limited to the following embodiments, and can be arbitrarily changed within the scope of the technical idea of the present invention. Moreover, in the following drawings, in order to make each structure easy to understand, the actual structure may be different from the scale, number, or the like in each structure. *

In the drawings, an XYZ coordinate system is appropriately shown as a three-dimensional orthogonal coordinate system. In the XYZ coordinate system, the Z-axis direction is a direction parallel to the axial direction of the central axis J shown in FIG. The X-axis direction is a direction orthogonal to the Z-axis direction and is the left-right direction in FIG. The Y-axis direction is a direction orthogonal to both the X-axis direction and the Z-axis direction.

In the following description, the positive side (+ Z side, one side) in the Z-axis direction is referred to as “upper side”, and the negative side (−Z side, the other side) in the Z-axis direction is referred to as “lower side”. Call. The upper side and the lower side are simply names used for explanation, and do not limit the actual positional relationship and direction. Unless otherwise specified, a direction parallel to the central axis J (Z-axis direction) is simply referred to as an “axial direction”, and a radial direction around the central axis J is simply referred to as a “radial direction”. The circumferential direction centering around, that is, the circumference of the central axis J is simply referred to as “circumferential direction”.

<Motor>
FIG. 1 is a cross-sectional view showing a motor 1 of the present embodiment. FIG. 2 is an enlarged cross-sectional view in which a part of FIG. 1 is enlarged. The motor 1 includes a motor housing 11, a substrate housing 12, a rotor 20 having a shaft 21, a stator 30, an upper bearing (bearing) 24, a lower bearing 25, a sensor magnet 63, and a bearing holder (heat sink). 40, a lid 70, a first substrate 66, a second substrate 67, a rotation sensor 61, and heat radiation grease (heat radiation material) G.

[housing]
The motor housing 11 and the substrate housing 12 accommodate each part of the motor 1 inside. The motor housing 11 has a cylindrical shape that opens upward (+ Z side). The substrate housing 12 has a cylindrical shape that opens downward (−Z side). The motor housing 11 and the substrate housing 12 are disposed with their openings facing each other. Between the motor housing 11 and the substrate housing 12, a peripheral portion of a bearing holder 40 described later is sandwiched.

The motor housing 11 has a first cylindrical portion 14, a first bottom portion 13, and a lower bearing holding portion 18. The first cylindrical portion 14 has a cylindrical shape that surrounds the radially outer side of the stator 30. In this embodiment, the 1st cylindrical part 14 is cylindrical, for example. The first cylindrical portion 14 is fitted in a stepped portion 40b provided on the periphery of the bearing holder 40 at the upper end. A stator 30 is fixed to the inner side surface of the first cylindrical portion 14.

The first bottom portion 13 is provided at the lower (−Z side) end portion of the first cylindrical portion 14. The first bottom portion 13 is provided with an output shaft hole portion 13a penetrating the first bottom portion 13 in the axial direction (Z-axis direction). The lower bearing holding portion 18 is provided on the upper (+ Z side) surface of the first bottom portion 13. The lower bearing holding portion 18 holds the lower bearing 25.

The substrate housing 12 is located on the upper side (+ Z side) of the motor housing 11. In the present embodiment, the substrate housing 12 accommodates the first substrate 66 and the second substrate 67. An electronic component or the like is mounted on at least one of the upper surface and the lower surface of the first substrate 66 and the second substrate 67. The substrate housing 12 has a second cylindrical portion 15 and a second bottom portion 16. Note that the number of substrates used in the motor 1 is not limited to two and may be one or three or more.

The second cylindrical portion 15 has a cylindrical shape surrounding the first substrate 66 and the second substrate 67 in the radial direction. The 2nd cylindrical part 15 is cylindrical shape, for example. A flange portion 15 a is provided at the lower end of the second cylindrical portion 15. The second cylindrical portion 15 is connected to the upper surface 40a of the bearing holder 40 at the flange portion 15a.

[Rotor]
The rotor 20 includes a shaft 21, a rotor core 22, and a rotor magnet 23. The shaft 21 is centered on a central axis J extending in the vertical direction (Z-axis direction). The shaft 21 is supported by the lower bearing 25 and the upper bearing 24 so as to be rotatable around the central axis J. The lower end (−Z side) of the shaft 21 protrudes to the outside of the housing 10 through the output shaft hole 13a. For example, a coupler (not shown) for connecting to an output target is press-fitted into the lower end portion of the shaft 21. A hole is provided in the upper end surface 21 a of the shaft 21. An attachment member 62 is fitted into the hole of the shaft 21. The attachment member 62 is a rod-like member extending in the axial direction.

The rotor core 22 is fixed to the shaft 21. The rotor core 22 surrounds the shaft 21 in the circumferential direction. The rotor magnet 23 is fixed to the rotor core 22. More specifically, the rotor magnet 23 is fixed to the outer surface along the circumferential direction of the rotor core 22. The rotor core 22 and the rotor magnet 23 rotate together with the shaft 21. The rotor core 22 may have a through hole or a recess, and the rotor magnet 23 may be accommodated in the through hole or the recess.

[Stator]
The stator 30 surrounds the outer side of the rotor 20 in the radial direction. The stator 30 includes a stator core 31, a bobbin 32, and a coil 33. The bobbin 32 is made of an insulating material. The bobbin 32 covers at least a part of the stator core 31. When the motor 1 is driven, the coil 33 excites the stator core 31. The coil 33 is configured by winding a conductive wire. The coil 33 is provided on the bobbin 32. A connection terminal (not shown) is provided at the end of the conductive wire constituting the coil 33. The connection terminal extends upward from the coil 33. The connection terminal passes through the bearing holder 40 and is connected to the first substrate 66. Note that the end of the conductive wire constituting the coil 33 may be directly connected to the first substrate 66.

[Upper bearing and lower bearing]
In the present embodiment, the upper bearing 24 is a ball bearing. The upper bearing 24 rotatably supports the upper end portion of the shaft 21. The upper bearing 24 is located on the upper side (+ Z side) of the stator 30. The upper bearing 24 is held by a bearing holder 40. In the present embodiment, the lower bearing 25 is a ball bearing. The lower bearing 25 rotatably supports the lower end portion of the shaft 21. The lower bearing 25 is located on the lower side (−Z side) of the stator 30. The lower bearing 25 is held by the lower bearing holding portion 18 of the motor housing 11.

The upper bearing 24 and the lower bearing 25 support the shaft 21 of the rotor 20. The types of the upper bearing 24 and the lower bearing 25 are not particularly limited, and other types of bearings may be used.

[Sensor magnet]
As shown in FIG. 2, the sensor magnet 63 is located above (+ Z side) the upper bearing 24. In the present embodiment, the sensor magnet 63 has an annular shape. The sensor magnet 63 is fitted on the outer surface of the mounting member 62 fixed to the shaft 21. Thereby, the sensor magnet 63 is attached to the shaft 21. Further, the sensor magnet 63 is located above the upper bearing 24. That is, the sensor magnet 63 is fixed to the shaft 21 via the mounting member 62 above the upper bearing 24 at the upper end portion of the shaft 21. The shape of the sensor magnet 63 is not limited to an annular shape, and may be another shape such as an annular shape or a disk shape. In this case, the sensor magnet 63 may be provided with a recess, and the tip of the mounting member 62 may be fixed to the recess by press-fitting or bonding. Further, the sensor magnet 63 may be directly attached to the tip of the shaft 21.

[Bearing holder]
As shown in FIG. 1, the bearing holder 40 is located on the upper side (+ Z side) of the stator 30. In the present embodiment, the bearing holder 40 directly holds the upper bearing 24. The planar view (XY plane view) shape of the bearing holder 40 is, for example, a circular shape concentric with the central axis J. The bearing holder 40 is made of metal. In the present embodiment, the bearing holder 40 is sandwiched between the motor housing 11 and the substrate housing 12. In addition, the planar view (XY plane view) shape of the bearing holder 40 is not limited to a circular shape, and may be another shape such as a polygonal shape.

The bearing holder 40 is provided with a through hole 45 penetrating in the vertical direction. The through hole 45 is located at the approximate center of the bearing holder 40. The upper end portion of the shaft 21 is disposed inside the through hole 45. By providing the through hole 45 in the bearing holder 40, the degree of freedom in the assembly process of the shaft 21 with respect to the bearing holder 40 can be increased. For example, when assembling, a jig that receives a force during press-fitting into the upper end surface 21 a of the shaft 21 can be disposed in the through hole 45, so that another member is attached to the shaft 21 with the shaft 21 assembled to the bearing holder 40. The assembly order of press-fitting can be adopted.

As shown in FIG. 2, on the inner peripheral surface of the through hole 45, a downward step surface 45a, an upward step surface 45b, a lower inner peripheral surface 45c, a middle inner peripheral surface 45d, and an upper inner peripheral surface 45e. And are provided. The downward step surface 45a is a step surface facing downward. The downward step surface 45 a is located on the lower side of the through hole 45. The upward step surface 45b is a step surface facing upward. The upward step surface 45 b is located closer to the upper side of the through hole 45. The lower inner peripheral surface 45c is positioned below the downward step surface 45a. The middle inner peripheral surface 45d is located between the downward step surface 45a and the upward step surface 45b. The upper inner peripheral surface 45e is located above the upward step surface 45b. The lower inner peripheral surface 45c, the middle inner peripheral surface 45d, and the upper inner peripheral surface 45e are concentric circular shapes when viewed from the axial direction. The inner diameters of the lower inner peripheral surface 45c and the upper inner peripheral surface 45e are larger than the diameter of the intermediate inner peripheral surface 45d.

The through-hole 45 accommodates the upper bearing 24 in a region below the downward step surface 45a (a region surrounded by the lower inner peripheral surface 45c). The through hole 45 accommodates the sensor magnet 63 in a region between the downward step surface 45a and the upward step surface 45b (a region surrounded by the intermediate inner peripheral surface 45d). Further, the through hole 45 accommodates the lid body 70 in a region above the upward step surface 45b (region surrounded by the upper inner peripheral surface 45e).

The upper surface of the outer ring of the upper bearing 24 is in contact with the downward stepped surface 45a through the wave washer 46. Further, the lower inner peripheral surface 45 c is fitted with the outer ring of the upper bearing 24. By providing the downward step surface 45 a, the upper bearing 24 can be easily positioned with respect to the bearing holder 40. In addition, a preload can be applied to the upper bearing 24 by interposing the wave washer 46 between the downward stepped surface 45 a and the outer ring of the upper bearing 24.

As shown in FIG. 1, the bearing holder 40 has a flat upper surface 40a on the upper side. The upper surface 40 a faces the lower surface 66 a of the first substrate 66. The upper surface 40a is provided with a housing recess 41 that is recessed downward. The housing recess 41 opens upward. A spacer 80 is inserted into the housing recess 41.

The spacer 80 includes a side wall portion 81 along the inner surface of the housing recess 41, a bottom wall portion 82 along the bottom surface of the housing recess 41, and a flange portion 83 positioned at the upper end of the side wall portion 81. The spacer 80 is made of an insulating material. The flange portion 83 is screwed to the flange portion 83 together with the first substrate 66 while being sandwiched between the bearing holder 40 and the first substrate 66. The flange portion 83 determines the vertical position of the first substrate 66 with respect to the bearing holder 40.

[Heat dissipation grease (heat dissipation material)]
The heat radiation grease G is located between the upper surface 40 a of the bearing holder 40 and the lower surface 66 a of the first substrate 66. The heat dissipation grease G transfers heat generated in the first substrate 66 and the mounted component mounted on the first substrate 66 to the bearing holder 40. The bearing holder 40 radiates heat transmitted from the heat radiation grease G to the outside.

According to the present embodiment, the bearing holder 40 receives the heat generated in the first substrate 66 and the mounted components of the first substrate 66 through the heat dissipation grease G and dissipates the heat to the outside. That is, according to this embodiment, the bearing holder 40 can function as a heat sink. The bearing holder 40 is preferably made of a material having high heat conduction efficiency, and is preferably made of, for example, an aluminum alloy. The bearing holder 40 may be made of a material such as aluminum, copper, a copper alloy, or an iron-based metal such as SUS.

In this embodiment, the heat radiation grease G has an insulating property. Thereby, the thermal radiation grease can suppress discharge between the first substrate 66 and the bearing holder 40. In addition, when the thermal radiation grease G does not have insulation, an insulation measure such as attaching an insulating sheet to the upper surface 40a of the bearing holder 40 may be performed.

[Lid]
The lid 70 is attached to the through hole 45 of the bearing holder 40. The lid 70 covers and closes the upper opening of the through hole 45. The lid 70 has a disk shape. The lid body 70 is fitted to the upper inner peripheral surface 45e of the through hole 45. Therefore, the outer diameter of the lid 70 is the same as or slightly larger than the inner diameter of the upper inner peripheral surface 45e.

According to the present embodiment, the cover 70 covers the through hole 45, so that the arrangement region of the heat dissipation grease G in a plan view can be widened. Thereby, the heat transfer efficiency from the 1st board | substrate 66 to the bearing holder 40 is improved, and the heat generated in the 1st board | substrate 66 can be thermally radiated more efficiently via the bearing holder 40. FIG.

Further, according to the present embodiment, since the lid 70 closes the opening on the upper side of the through hole 45, when the heat dissipation grease G is adopted as the heat dissipation material, the heat dissipation grease G enters the through hole 45. Can be suppressed. Thereby, it can suppress that the thermal radiation grease G affects the motion of the upper bearing 24 and the function of the stator 30. Note that a gap is allowed between the lid 70 and the bearing holder 40 (that is, the inner peripheral surface of the through-hole 45) so that the heat-dissipating grease G having viscosity does not easily pass therethrough.

Further, according to the present embodiment, since the lid 70 closes the opening above the through hole 45, the heat in the surface of the first substrate 66 can be moved uniformly toward the bearing holder 40. . That is, the distribution of the heat radiation efficiency of the first substrate 66 can be made uniform. Therefore, it is possible to increase the degree of freedom of mounting the first substrate 66 such as an electronic component. As a result, the mounting components can be mounted on the first substrate 66 with high density, and the motor 1 can be downsized.

The lower surface 70 b of the lid 70 is in contact with the upward step surface 45 b of the through hole 45. The thickness of the lid 70 is smaller than the distance between the upper surface 40a of the bearing holder 40 and the upward step surface 45b (that is, the height of the step). Therefore, the upper surface 70 a of the lid 70 is positioned below the upper surface 40 a of the bearing holder 40. The rotation sensor 61 is mounted on the lower surface 66 a of the first substrate 66 and faces the upper surface 70 a of the lid 70. By disposing the upper surface 70a of the lid 70 below the upper surface 40a of the bearing holder 40, the sensor magnet 63 and the rotation sensor 61 can be disposed close to each other in the vertical direction. Thereby, the detection accuracy of the rotation angle of the rotation sensor 61 can be increased. Further, by arranging the upper surface 70 a of the lid 70 below the upper surface 40 a of the bearing holder 40, it is possible to suppress the interference between the lid 70 and the rotation sensor 61. In addition, even when the upper surface 70a of the lid 70 and the upper surface 40a of the bearing holder 40 have the same height, certain similar effects can be obtained.

The lid 70 is located between the sensor magnet 63 and the rotation sensor 61 mounted on the first substrate 66. The lid 70 is preferably made of a nonmagnetic material in order to suppress the influence on the magnetic field generated by the sensor magnet 63. Moreover, it is preferable to comprise the cover body 70 from a metal material with high heat conduction efficiency. Thereby, it becomes possible to move heat efficiently from the heat radiation grease G toward the lid body 70, and further efficient heat radiation is possible. Further, the lid 70 and the bearing holder 40 are desirably fitted. Since the lid body 70 and the bearing holder 40 are in contact with each other, heat can be efficiently moved from the lid body 70 toward the bearing holder 40.

The lid 70 is preferably made of the same material as the bearing holder 40. In the present embodiment, the lid body 70 is fixed to the bearing holder 40 by fitting. By configuring the lid body 70 from the same material having the same thermal expansion coefficient as that of the bearing holder 40, it is possible to suppress the lid body 70 from falling off the bearing holder 40 due to a change in temperature environment.

The thickness of the lid 70 is preferably 0.5 mm or more and 5 mm or less. By setting the thickness of the lid 70 to 0.5 mm or more, handling of the lid 70 in the assembly process becomes easy. Moreover, the raw material cost of the cover body 70 can be lowered | hung by the thickness of the cover body 70 being 5 mm or less. In addition, when the lid 70 is formed by press working, the pressure applied by the forming can be reduced, so that the manufacturing cost can be reduced. Further, when the lid 70 is fixed to the bearing holder 40 by press-fitting, it is more preferable that the thickness of the lid 70 is 2 mm or more so that the lid 70 has sufficient rigidity.

The fixing means between the lid 70 and the bearing holder 40 is not limited to fitting. For example, the lid 70 and the bearing holder 40 may be connected by a joining means such as welding, adhesion, or caulking. When at least one of the lid 70 and the bearing holder 40 is a resin material, the lid 70 and the bearing holder 40 may be integrally connected by a molding means such as insert molding or two-color molding. .

[First substrate, second substrate]
The first substrate 66 and the second substrate 67 control the motor 1. That is, the motor 1 includes a first substrate 66 and a second substrate 67 and includes a control device 60 that controls the rotation of the shaft 21. Electronic components are mounted on the first substrate 66 and the second substrate 67. Electronic components mounted on the first substrate 66 and the second substrate 67 are a rotation sensor 61, an electrolytic capacitor, a choke coil, and the like.

The first substrate 66 is disposed on the upper side (+ Z side) of the bearing holder 40. The second substrate 67 is disposed on the upper side of the first substrate 66. The plate surface directions of the first substrate 66 and the second substrate 67 are both perpendicular to the axial direction. The first substrate 66 and the second substrate 67 are disposed so as to overlap each other when viewed from the axial direction. That is, the first substrate 66 and the second substrate 67 are stacked with a predetermined gap along the axial direction.

The first substrate 66 has a lower surface 66a and an upper surface 66b. Similarly, the second substrate 67 has a lower surface 67a and an upper surface 67b. The upper surface 66b of the first substrate 66 and the lower surface 67a of the second substrate 67 face each other in the vertical direction with a gap therebetween. Further, the lower surface 66a of the first substrate 66 and the upper surface 40a of the bearing holder 40 face each other in the vertical direction with a gap therebetween. A gap between the lower surface 66a of the first substrate 66 and the upper surface 40a of the bearing holder 40 is filled with heat radiation grease G.

The first substrate 66 and the second substrate 67 are electrically connected by a plurality of connection pins (wirings) 51. The first substrate 66 and the second substrate 67 are provided with a plurality of

holes

66c and 67c penetrating in the vertical direction. The hole 66c of the first substrate 66 and the hole 67c of the second substrate 67 are arranged so as to overlap each other when viewed from the axial direction. The connection pin 51 extends along the axial direction (vertical direction) between the

holes

66c and 67c. The connection pin 51 has a first tip portion 51a located on the lower side and a second tip portion 51b located on the upper side. The first tip 51a is press-fitted into the hole 66c of the first substrate 66 from the upper surface 66b side. The second tip 51b is press-fitted into the hole 67c of the second substrate 67 from the lower surface 67a side.

A rotation sensor 61 is mounted on the lower surface 66a of the first substrate 66. The rotation sensor 61 is disposed so as to overlap with the sensor magnet 63 of the first substrate 66 when viewed from the axial direction. The rotation sensor 61 detects the rotation of the sensor magnet 63. In the present embodiment, the rotation sensor 61 is a magnetoresistive element. The rotation sensor 61 may be a Hall element, for example.

<Modification>
FIG. 3 shows a sectional view of a bearing holder (heat sink) 140, a lid 170, and a first substrate 166, which are modifications that can be employed in the above-described embodiment. In addition, about the component of the same aspect as the above-mentioned embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

The first substrate 166 is arranged with the lower surface 166a facing the upper side of the bearing holder 140, as in the above-described embodiment. In the present modification, the rotation sensor 161 is mounted on the upper surface 166 b of the first substrate 166.

The bearing holder 140 is provided with a through hole 145 as in the above-described embodiment. In the present modification, the lid 170 is fixed to the upper surface 140a of the bearing holder 140 and covers and closes the opening above the through hole 145. Since the lid 170 is fixed to the upper surface 140 a of the bearing holder 140, the upper surface 170 a of the lid 170 is positioned above the upper surface 140 a of the bearing holder 140. The upper surface 140a of the bearing holder 140 and the lower surface 170b of the lid 170 are connected to each other by a joining means such as welding, adhesion, or caulking.

According to this modification, the upper surface 170a of the lid 170 is positioned above the upper surface 140a of the bearing holder 140. Thereby, the distance between the rotation sensor 161 mounted on the upper surface 66b of the first substrate 66 and the sensor magnet 63 can be arranged close to each other. Thereby, the detection accuracy of the rotation angle of the rotation sensor 161 can be increased.

<Other variations>
In the present embodiment, the following configuration may be employed. In this embodiment, the case where the heat sink is the bearing holder 40 that directly holds the upper bearing 24 is illustrated. However, the heat sink (corresponding to the bearing holder 40 of the above-described embodiment) may indirectly hold the upper bearing 24 via a separately prepared bearing holder. In this case, the heat sink is preferably fixed to the bearing holder.

In the present embodiment, the case where the lid 70 closes the opening of the through hole 45 of the bearing holder 40 is illustrated. However, the lid 70 only needs to cover at least a part of the opening above the through hole 45. For example, a lid provided with a hole may be used. Even in such a case, the lid body can exhibit a certain effect of widening the arrangement area of the heat dissipation grease G.

In the present embodiment, the case where fluidized heat radiation grease G is employed as the heat radiation material positioned between the first substrate 66 and the bearing holder 40 is exemplified. However, the heat dissipation material may be, for example, a gel or solid heat dissipation material.

<Electric power steering device>
Next, an embodiment of an apparatus on which the motor 1 of this embodiment is mounted will be described. In the present embodiment, an example in which the motor 1 is mounted on an electric power steering device will be described. FIG. 4 is a schematic diagram showing the electric power steering apparatus 2 of the present embodiment.

The electric power steering device 2 is mounted on a steering mechanism of a vehicle wheel. The electric power steering device 2 is a device that reduces the steering force by hydraulic pressure. As shown in FIG. 4, the electric power steering apparatus 2 of the present embodiment includes a motor 1, a steering shaft 114, an oil pump 116, and a control valve 117.

The steering shaft 114 transmits the input from the steering 111 to the axle 113 having the wheels 112. The oil pump 116 generates hydraulic pressure in the power cylinder 115 that transmits driving force by hydraulic pressure to the axle 113. The control valve 117 controls the oil of the oil pump 116. In the electric power steering apparatus 2, the motor 1 is mounted as a drive source for the oil pump 116.

Since the electric power steering apparatus 2 of the present embodiment includes the motor 1 of the present embodiment, the heat generated in the first substrate 66 can be efficiently radiated. Thereby, according to this embodiment, the electric power steering device 2 excellent in reliability can be obtained.

Although the embodiments and modifications of the present invention have been described above, the configurations and combinations thereof in the embodiments are examples, and the addition, omission, replacement, and configuration of the configurations are within the scope that does not depart from the spirit of the present invention. Other changes are possible. Further, the present invention is not limited by the embodiment.

DESCRIPTION OF SYMBOLS 1 ... Motor, 2 ... Electric power steering device, 21 ... Shaft, 24 ... Upper bearing (bearing), 40, 140 ... Bearing holder (heat sink), 45, 145 ... Through-hole, 60 ... Control device, 61, 161 ... Rotation Sensor, 63 ... sensor magnet, 70, 170 ... lid, 111 ... steering, G ... heat radiation grease (heat radiation material), J ... center shaft

Claims

A shaft that rotates about a central axis extending in the vertical direction;
A bearing that supports the upper end of the shaft;
A metal heat sink that directly or indirectly holds the bearing;
A substrate disposed above the heat sink;
A sensor magnet fixed to the shaft above the bearing at the upper end of the shaft;
A rotation sensor mounted at a position overlapping the sensor magnet of the substrate as seen from the axial direction;
A heat dissipating material located between the substrate and the heat sink,
The heat sink is provided with a through hole that penetrates in the vertical direction and accommodates the bearing and the sensor magnet.
The motor, wherein a lid that covers at least a part of the opening above the through hole is attached to the heat sink.
The rotation sensor is mounted on the lower surface of the substrate;
The motor according to claim 1, wherein the upper surface of the lid is located at the same height as the upper surface of the heat sink or below the heat sink.
The rotation sensor is mounted on an upper surface of the substrate;
The motor according to claim 1, wherein an upper surface of the lid is located above an upper surface of the heat sink.
The motor according to any one of claims 1 to 3, wherein the lid closes the through hole.
The motor according to any one of claims 1 to 4, wherein the lid is made of a nonmagnetic metal.
The motor according to any one of claims 1 to 5, wherein the heat dissipation material has an insulating property.
The motor according to any one of claims 1 to 6, further comprising a control device that controls rotation of the shaft.
An electric power steering apparatus having the motor according to any one of claims 1 to 7.