CN212412923U

CN212412923U - Motor

Info

Publication number: CN212412923U
Application number: CN201890001029.3U
Authority: CN
Inventors: 吉田雄策; 二之宫优太
Original assignee: Nidec Corp
Current assignee: Nidec Corp
Priority date: 2017-08-09
Filing date: 2018-06-11
Publication date: 2021-01-26
Anticipated expiration: 2028-06-11
Also published as: WO2019031050A1

Abstract

The motor has: a rotor having a shaft disposed along a central axis extending in a vertical direction and rotating around the central axis; a stator that is opposed to the rotor with a gap therebetween in a radial direction; a housing having a cylindrical portion surrounding the stator from the outside in the radial direction; a bearing that supports a shaft so that the shaft can rotate; and a bearing holder which is held by the cylindrical portion and supports the bearing, wherein a groove portion extending in the circumferential direction is provided on an inner circumferential surface of the housing, and the bearing holder has an outer edge portion which is housed in the groove portion.

Description

Motor

Technical Field

The utility model relates to a motor.

Background

Conventionally, the following motors are known: the flange holding the bearing is fixed to the housing by shrink fitting (for example, patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2014-17955

SUMMERY OF THE UTILITY MODEL

Problem to be solved by utility model

In the case where the flange and the housing are fixed by the shrink fitting, since there is no need to provide a fixing member such as an adhesive or a screw, it is possible to reduce the manufacturing cost and weight, and the housing may be deformed after the shrink fitting. Therefore, when the motor is assembled to the external device based on the size of the housing, there is a problem that the assembly accuracy cannot be ensured.

In view of the above, an object of the present invention is to provide a motor capable of holding a bearing holder in a housing while suppressing deformation of the housing.

Means for solving the problems

The utility model discloses a motor of mode has: a rotor having a shaft disposed along a central axis extending in a vertical direction and rotating around the central axis; a stator that is opposed to the rotor with a gap therebetween in a radial direction; a housing having a cylindrical portion surrounding the stator from a radial outer side; a bearing for rotatably supporting the shaft; and a bearing holder which is held by the cylindrical portion and supports the bearing, wherein a groove portion extending in a circumferential direction is provided on an inner circumferential surface of the housing, and the bearing holder has an outer edge portion which is accommodated in the groove portion.

Effect of the utility model

According to an aspect of the present invention, there is provided a motor capable of holding a bearing holder in a housing while suppressing deformation of the housing.

Drawings

Fig. 1 is a sectional view of a motor according to an embodiment.

Fig. 2 is an enlarged view of region II of fig. 1.

Fig. 3 is a partial sectional view of a motor according to modification 1.

Detailed Description

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. In the drawings below, in order to facilitate understanding of each structure, the actual structure may be different from the scale, the number, and the like of each structure.

In each figure, the Z-axis is shown as appropriate. The Z-axis direction in each drawing is a direction parallel to the axial direction of the central axis J shown in fig. 1. 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". The upper side and the lower side are directions for explanation only, and do not limit actual positional relationship and directions. Unless otherwise specified, a direction parallel to the central axis J (Z-axis direction) is simply referred to as "axial direction" or "vertical direction", a radial direction about the central axis J is simply referred to as "radial direction", and a circumferential direction about the central axis J, that is, a direction around the central axis J is simply referred to as "circumferential direction". In the following description, the term "plan view" refers to a state viewed from the axial direction.

[ Motor ]

Fig. 1 is a sectional view of a motor 1 of the present embodiment. The motor 1 includes a rotor 20 having a shaft 21, a stator 30, a bus bar unit 60, a housing 40, an upper bearing (bearing) 6A, a lower bearing 6B, and a bearing holder 10. The motor 1 is connected to an external device (control unit) 9 through an external connection terminal 61a extending upward from the bus bar unit 60. The motor 1 controls the rotation of the rotor 20 by the external device 9.

[ ROTOR ]

The rotor 20 rotates about the center axis J. The rotor 20 includes a shaft 21, a rotor core 24, and a rotor magnet 23. The shaft 21 is disposed along a central axis J extending in the vertical direction (axial direction) as a center. The shaft 21 is supported by the upper bearing 6A and the lower bearing 6B so as to be rotatable about the center axis J.

The rotor core 24 is fixed to the shaft 21. The rotor core 24 circumferentially surrounds the shaft 21. The rotor magnet 23 is fixed to the rotor core 24. More specifically, the rotor magnet 23 is fixed to an outer surface of the rotor core 24 in the circumferential direction. The rotor core 24 and the rotor magnet 23 rotate together with the shaft 21.

[ STATOR ]

The stator 30 is opposed to the rotor 20 with a gap therebetween in the radial direction, and surrounds the rotor 20 on the radially outer side. The stator 30 includes a stator core 31, an insulator 32, and a coil 33. The insulating member 32 is made of an insulating material. The insulator 32 covers at least a portion of the stator core 31. When the motor 1 is driven, the coil 33 excites the stator core 31. The coil 33 is formed by winding a coil wire (not shown). The coil wire is wound around the teeth of the stator core 31 via the insulator 32. The end of the coil wire is drawn out to the upper side.

[ busbar Unit ]

The bus bar unit 60 is located between the stator 30 and the bearing holder 10 in the axial direction. That is, the bus bar unit 60 is positioned at an upper side of the stator 30 and at a lower side of the bearing holder 10. The bus bar unit 60 has a plurality of bus bars 61 and a bus bar holder 62 that holds the bus bars 61. The bus bar 61 is connected to a coil wire drawn out from the stator 30. A part of the bus bar 61 penetrates the bearing holder 10 and extends upward as an external connection terminal 61 a. The external connection terminal 61a is connected to an external device 9 that controls the energization of the coil 33 of the stator 30. Further, the bus bar unit 60 may be positioned above the bearing holder 10.

[ Upper and lower side Bearings ]

The upper bearing 6A rotatably supports the upper end 21a of the shaft 21. The upper bearing 6A is located on the upper side of the stator 30. The upper bearing 6A is supported by a bearing holder 10. The lower bearing 6B rotatably supports the lower end portion 21B of the shaft 21. The lower bearing 6B is located on the lower side of the stator 30. The lower bearing 6B is supported by the lower bearing holding portion 48 of the housing 40.

In the present embodiment, the upper bearing 6A and the lower bearing 6B are ball bearings. However, the types of the upper bearing 6A and the lower bearing 6B are not particularly limited, and may be other types of bearings.

[ Shell ] for a refrigerator

The housing 40 has a cylindrical shape opened to the upper side (+ Z side). The housing 40 houses the rotor 20 and the stator 30. The housing 40 has a cylindrical portion 45, a bottom portion 49, and a lower bearing holding portion 48. The housing 40 may be a cylindrical member without the bottom portion 49. In this case, a bearing holder for holding a bearing is separately attached to the opening on the lower side of the housing 40.

The cylindrical portion 45 surrounds the stator 30 from the radially outer side. In the present embodiment, the cylindrical portion 45 has a cylindrical shape. A groove 44 extending in the circumferential direction is provided on an inner circumferential surface 45c of the cylindrical portion 45.

Fig. 2 is an enlarged view of region II of fig. 1. The groove portion 44 has: a bottom surface 44a facing radially inward; an upper groove wall surface (upper groove wall surface) 44b extending radially inward from an upper end of the bottom surface 44 a; and a lower groove wall surface (lower groove wall surface) 44c extending radially inward from the lower end of the bottom surface 44 a. The upper groove wall surface 44b faces axially downward. The lower groove wall surface 44c faces axially upward. The bottom surface 44a, the upper groove wall surface 44b, and the lower groove wall surface 44c extend in the circumferential direction with the same width.

The inner peripheral surface 45c is provided with a stepped surface 41 facing upward. The step surface 41 extends in the circumferential direction with the same width. The step surface 41 is located below the groove portion 44. The step surface 41 is flush with the lower groove wall surface 44c of the groove portion 44, and is continuous with the lower groove wall surface 44 c. That is, the step surface 41 is a surface extending radially inward on the lower groove wall surface 44c of the groove portion 44.

The inner peripheral surface 45c is provided with a lower inner peripheral surface 45e positioned below the groove 44 and an upper inner peripheral surface 45d positioned above the groove 44. As described above, since the stepped surface 41 extending radially inward is provided on the lower groove wall surface 44c of the groove portion 44, the inner diameter of the upper inner peripheral surface 45d is larger than the inner diameter of the lower inner peripheral surface 45 e.

As shown in fig. 1, the stator 30 is fixed to the lower inner circumferential surface 45 e. Further, a storage space a for storing the external device 9 is provided radially inside the upper inner peripheral surface 45 d. That is, the housing space a is provided radially inside the cylindrical portion 45 and above the bearing holder 10. The external device 9 is connected to the external connection terminal 61a of the motor 1 in the housing space a. According to the present embodiment, the cylindrical portion 45 surrounds a part of the external device 9, and protects the connection between the external device 9 and the external connection terminal 61 a.

Since the cylindrical portion 45 surrounds the housing space a from the radially outer side, the housing space a may be deformed when the amount of deformation of the cylindrical portion 45 is increased. This may destabilize the storage state of the external device 9, and may affect the connection state between the external device 9 and the motor 1. As will be described later, according to the motor 1 of the present embodiment, the deformation amount of the cylindrical portion 45 is reduced, whereby the connection state between the external device 9 and the motor 1 can be stabilized.

In the present embodiment, the housing area 45c1 surrounding the housing space a on the inner peripheral surface 45c of the cylindrical portion 45 is in contact with the external device 9. In this way, when a part of the inner peripheral surface 45c contacts the external device 9, the deformation of the cylindrical portion 45 directly affects the assembly accuracy of the external device 9 and the motor 1. Therefore, when a part of the inner peripheral surface 45c contacts the external device 9, the deformation amount of the cylindrical portion 45 is reduced, whereby the connection state between the external device 9 and the motor 1 can be stabilized, and the positioning accuracy of the external device 9 with respect to the motor 1 can be improved.

The inner peripheral surface 45c of the cylindrical portion 45 is machined by a cutting process such as lathe machining. The inner peripheral surface 45c is formed by machining the groove portion 44 after machining the entire axial region to the inner diameter of the lower inner peripheral surface 45e in a cutting step, and further machining the upper inner peripheral surface 45d on the upper side of the groove portion 44. Therefore, a corner R portion 44d is formed at the corner of the groove portion 44. That is, the method of manufacturing the motor 1 includes a cutting step of forming the groove portion 44 in the inner peripheral surface 45c of the housing 40 by lathe machining. The housing 40 is manufactured by molding a cylindrical shape by die casting or the like, and then processing the inner peripheral surface 45 c.

The bottom portion 49 is located at the lower end of the cylindrical portion 45. The bottom 49 is located on the underside of the stator 30. The lower bearing holding portion 48 is located at the center of the bottom portion 49 in plan view. The lower bearing holding portion 48 holds the lower bearing 6B. The lower bearing holding portion 48 includes: a cylindrical portion 48a extending in the axial direction about the central axis J; and a lower end projection 48b extending radially inward from the lower end of the tube 48 a. A hole 48c penetrating in the axial direction is provided at the center of the lower end protrusion 48b in a plan view.

[ Bearings-holder ]

The bearing holder 10 is located on the upper side (+ Z side) of the stator 30. The bearing holder 10 holds the upper bearing 6A. The bearing holder 10 is held by the cylindrical portion 45 of the housing 40. The top view (XY view) of the bearing holder 10 is, for example, a circular shape concentric with the central axis J.

The bearing holder 10 has an upper bearing holding portion (holding portion) 18, a curved portion 17, a flat portion 16, and an extending portion 15. The upper bearing holding portion (holding portion) 18, the curved portion 17, the flat portion 16, and the extending portion 15 are arranged in this order from the radially inner side toward the radially outer side.

The upper bearing holding portion 18 holds the upper bearing 6A. The upper bearing holding portion 18 is located at the center of the bearing holder 10 in plan view. The upper bearing holding portion 18 includes: a cylindrical portion 18a extending in the axial direction about the central axis J; and an upper end projection 18b extending radially inward from the upper end of the tube 18 a. The upper end projection 18b positions the upper bearing 6A in the up-down direction. A hole 18c penetrating in the axial direction is provided at the center of the upper end projection 18b in a plan view. The hole 18c is inserted with the upper end of the shaft 21.

The upper end protrusion 18b of the upper bearing holding portion 18 contacts the outer ring of the upper bearing 6A via a wave washer (elastic member) 5. Namely, the motor 1 has a wave washer 5. The wave washer 5 is sandwiched between the upper end protrusion 18b and the outer ring of the upper bearing 6A in a compressed state. The wave washer 5 applies a force to the upper-end protrusion 18b and the outer ring of the upper bearing 6A in a direction axially apart from each other. The wave washer 5 imparts preload to the upper bearing 6A. The wave washer 5 presses the bearing holder 10 upward.

The curved portion 17 is located between the flat portion 16 and the upper bearing holding portion 18 in the radial direction. The bent portion 17 extends obliquely upward from the axial middle of the cylindrical portion 18a of the upper bearing holding portion 18 toward the radially outer side. A concave groove 17a is provided in the bearing holder 10 above the bent portion 17. That is, the bearing holder 10 is provided with a recessed groove 17a located radially outward of the upper bearing holding portion 18. The groove 17a is open in the axial direction (upper side in the present embodiment). The groove 17a extends in the circumferential direction.

According to the present embodiment, the bearing holder 10 is provided with the concave groove 17 a. Thereby, even when a radial or axial stress is applied to the bearing holder 10, the deformation of the upper bearing holding portion 18 located radially inward of the recessed groove 17a can be suppressed. This can improve the reliability of the holding of the upper bearing 6A by the upper bearing holding portion 18. Although the concave groove 17a of the present embodiment is open to the upper side, the stress applied to the upper bearing holder 18 can be reduced even when the concave groove is open to the lower side.

The flat portion 16 is located radially outward of the upper bearing holding portion 18 and the bent portion 17. The flat portion 16 extends along a plane perpendicular to the central axis J. The flat portion 16 has a disk shape centered on the central axis J in a plan view.

The extension 15 extends axially from the outer edge of the flat portion 16. In the present embodiment, the extension portion 15 extends downward with respect to the flat portion 16. Therefore, the housing space a on the upper side of the bearing holder 10 can be secured larger than in the case of extending upward. The extension portion 15 extends cylindrically in the circumferential direction. The extending portion 15 is radially opposed to the inner peripheral surface 45c of the cylindrical portion 45. A part of the extension portion 15 overlaps with the upper bearing holding portion 18 in the axial direction.

As shown in fig. 2, an outer edge 14 is provided on the outer edges of the flat portion 16 and the extended portion 15. The outer edge portion 14 constitutes the outer shape of the bearing holder 10. The outer edge 14 is housed in the groove 44, and the groove 44 is provided on the inner circumferential surface 45c of the cylindrical portion 45. That is, the bearing holder 10 has the outer edge 14 received in the groove 44.

The outer edge portion 14 has an outer peripheral surface 14a facing radially outward. The outer peripheral surface 14a has an outer diameter larger than the inner diameter of the inner peripheral surface 45 c. Here, the inner diameter of the inner peripheral surface 45c refers to the inner diameter of the upper inner peripheral surface 45d and the inner diameter of the lower inner peripheral surface 45 e. The outer diameter of the outer peripheral surface 14a is smaller than the inner diameter of the bottom surface 44a of the groove 44. Therefore, the outer edge 14 is positioned inside the groove 44 and faces the bottom surface 44a of the groove 44 with a gap in the radial direction.

According to the present embodiment, the outer edge portion 14 of the bearing holder 10 is received in the groove portion 44. Therefore, when stress is applied to the bearing holder 10 in the axial direction, the outer edge portion 14 is prevented from moving by coming into contact with the upper groove wall surface 44b and the lower groove wall surface 44c of the groove portion 44. This enables the bearing holder 10 to be held by the housing 40.

According to the present embodiment, a gap is provided between the outer peripheral surface 14a of the outer edge 14 and the bottom surface 44a of the groove portion 44. In the case where the cylindrical portion and the bearing holder are fixed by thermocompression bonding with surfaces facing in the radial direction in contact with each other as in the conventionally known structure, stress is applied to the cylindrical portion from the bearing holder to the outside in the radial direction. This may deform the cylindrical portion. In contrast, according to the present embodiment, the cylindrical portion 45 is not subjected to stress directed radially outward from the bearing holder 10, and deformation of the cylindrical portion 45 can be suppressed.

The outer peripheral surface 14a of the outer rim 14 may contact the bottom surface 44a of the groove 44. Since the outer rim 14 is housed in the groove 44, even when the outer peripheral surface 14a of the outer rim 14 is brought into contact with the bottom surface 44a of the groove 44 and fixed by shrink fitting, the interference can be reduced while securing the holding force. This can reduce the amount of deformation of the cylindrical portion 45 compared to conventional fixing by shrink fitting.

As described above, the outer peripheral surface 14a of the outer edge 14 can be in contact with the bottom surface 44a of the groove 44 even when the outer peripheral surface faces the bottom surface 44a with a gap therebetween. In the case where the gap is provided between the outer peripheral surface 14a and the bottom surface 44a, the stress received by the housing 40 from the bearing holder 10 can be reduced, and the deformation of the housing 40 can be suppressed. On the other hand, when the outer peripheral surface 14a contacts the bottom surface 44a, the bearing holder 10 can be prevented from moving in the vertical direction with respect to the housing 40, and the rattling and tilting of the bearing holder 10 can be prevented.

Preferably, the difference between the inner diameter of the bottom surface 44a and the outer diameter of the outer peripheral surface 14a is smaller than 2 times the depth of the groove 44 (i.e., the dimension of the upper groove wall surface 44b in the radial direction). In this case, even when the bearing holder 10 is biased to one side in the radial direction, the upper groove wall surface 44b and the lower groove wall surface 44c are positioned above and below the outer edge portion 14 over the entire circumference. Therefore, even when stress directed upward or downward is applied to the bearing holder 10, the outer edge portion 14 can be effectively prevented from coming off the groove portion 44.

The dimension of the outer rim portion 14 in the axial direction is smaller than the dimension of the groove portion 44 in the axial direction (i.e., the distance between the upper groove wall surface 44b and the lower groove wall surface 44 c). Therefore, the outer edge 14 faces at least one of the upper groove wall surface 44b and the lower groove wall surface 44c with a gap therebetween in the axial direction. As described above, the bearing holder 10 is axially upwardly stressed by the wave washer 5. Therefore, the outer edge 14 contacts the upper groove wall surface 44b, and the outer edge 14 is provided with a gap from the lower groove wall surface 44 c.

According to the present embodiment, the outer edge portion 14 is pressed against the upper groove wall surface 44b, whereby the bearing holder 10 is positioned in the axial direction with respect to the housing 40, and the bearing holder 10 can be prevented from rattling with respect to the housing 40. In the present embodiment, the case where the outer edge portion 14 is pressed against the upper groove wall surface 44b by the wave washer 5 is exemplified. However, the outer edge portion 14 may be pressed against the lower groove wall surface 44 c. The wave washer 5 may not necessarily be used as long as an elastic member that applies stress to the bearing holder 10 in one axial direction is provided. That is, the motor 1 may have an elastic member (the wave washer 5 in the present embodiment) which is interposed between the outer ring of the upper bearing 6A and the bearing holder 10 and presses the outer edge portion against the upper groove wall surface 44b or the lower groove wall surface 44c of the groove portion.

An upper tapered portion 14j is provided at the upper end of the outer edge portion 14. The upper tapered portion 14j is inclined radially inward as it goes upward. Further, a lower tapered portion 14k is provided at the lower end of the outer edge portion 14. The lower tapered portion 14k is inclined radially inward as it goes downward. The upper tapered portion 14j and the lower tapered portion 14k are formed by chamfering. As described above, the corner R portion 44d is provided at the corner of the groove portion 44. The upper tapered portion 14j and the lower tapered portion 14k are opposed to the corner R portion 44d, respectively.

According to the present embodiment, the outer edge portion 14 is provided with the upper tapered portion 14j and the lower tapered portion 14k, and thus the outer edge portion 14 can be prevented from interfering with the corner R portion 44 d. As a result, the contact between the outer edge 14 and the groove wall surfaces (the upper groove wall surface 44b and the lower groove wall surface 44c) of the groove portion 44 is stabilized, and the positioning accuracy in the axial direction of the bearing holder 10 can be improved. In the present embodiment, a case where the upper tapered portion 14j and the lower tapered portion 14k linearly extend obliquely from the radially inner side toward the radially outer side has been described. However, the upper tapered portion 14j and the lower tapered portion 14k may be curved as long as they have tapered shapes that suppress interference with the corner R portion 44 d. For example, the upper tapered portion 14j and the lower tapered portion 14k may be R surfaces having a larger radius of curvature than the corner R portion 44 d.

Next, a method for manufacturing the motor 1 will be described. The method of manufacturing the motor 1 includes a holding step of holding the bearing holder 10 in the housing 40. The holding step is a part of an assembling step of assembling the respective members. Therefore, the step of manufacturing each member is performed before the holding step. Of course, the step of lathing the groove portion 44 of the housing 40 may be performed before the holding step.

In the holding step, first, the housing 40 is heated to expand the inner diameter of the cylindrical portion 45. Next, the bearing holder 10 is disposed inside the cylindrical portion 45. At this time, the outer edge 14 is disposed between a pair of groove wall surfaces (an upper groove wall surface 44b and a lower groove wall surface 44c) of the groove 44 of the cylindrical portion 45 in the axial direction. Next, the housing 40 is cooled, and the cylindrical portion 45 is contracted to the original inner diameter to house the outer edge portion 14 in the groove portion 44. Through the above steps, the bearing holder 10 is held by the housing 40.

As described above, the inner circumferential surface 45c of the cylindrical portion 45 is provided with the step surface 41 continuous with the lower groove wall surface 44c of the groove portion 44. Therefore, the inner peripheral surface 45c has a lower inner peripheral surface 45e positioned below the groove 44 and has a smaller inner diameter than an upper inner peripheral surface 45d positioned above the groove 44.

The inner diameter of the upper inner circumferential surface 45d located above the groove 44 is set to be larger than the outer diameter of the bearing holder 10 in the step of heating the housing 40 to expand the inner diameter of the cylindrical portion 45. That is, in the holding step, the inner diameter of the upper inner peripheral surface 45d that is heated and expanded is larger than the outer diameter of the outer edge 14. This allows the bearing holder 10 to be smoothly disposed inside the cylindrical portion 45.

On the other hand, the inner diameter of the lower inner circumferential surface 45e located below the groove 44 is set to: even in the expanded state of the cylindrical portion 45, the outer diameter is smaller than the outer diameter of the bearing holder. Therefore, in the process of disposing the bearing holder 10 inside the housing 40, the lower end surface 15a of the extending portion 15 of the bearing holder 10 is brought into contact with the stepped surface 41, whereby the outer edge portion 14 can be easily disposed between the upper groove wall surface 44b and the lower groove wall surface 44 c. That is, according to the present embodiment, the inner diameter of the lower inner peripheral surface 45e is made smaller than the inner diameter of the upper inner peripheral surface 45d, so that the bearing holder 10 can be easily positioned with respect to the housing 40 in the assembly step.

According to the present embodiment, the lower inner peripheral surface 45e has a smaller inner diameter than the upper inner peripheral surface 45d, and therefore can be brought into contact with the lower end surface 15a of the outer edge portion 14 so as to secure a large area. Therefore, when a stress directed downward is applied to the bearing holder 10, the effect of suppressing the outer edge portion 14 from coming off the groove portion 44 can be improved.

The bearing holder 10 is held by the housing 40 through the holding step described above. However, the outer edge portion 14 may be accommodated in the groove portion 44 by press-fitting the bearing holder 10 into the upper inner peripheral surface 45d of the housing 40. When the outer edge portion 14 is accommodated in the groove portion 44 by press-fitting, the outer edge portion 14 of the bearing holder 10 may rub against the upper inner circumferential surface 45d, thereby causing contamination. In contrast, when the outer edge portion 14 is accommodated in the groove portion 44 in the above-described holding step of heating the case 40 to expand the inner diameter, a holding structure that suppresses the occurrence of contamination can be realized.

In the case of adopting the holding step of heating the housing 40 to enlarge the inner diameter and thereby accommodating the outer edge portion 14 in the groove portion 44, the inner peripheral surface 45c of the housing 40 is not scraped by the bearing holder 10. Therefore, the surface roughness of the inner peripheral surface 45c of the cylindrical portion 45 is the same on the upper side of the bearing holder 10 and on the lower side of the bearing holder 10.

The bearing holder 10 and the housing 40 are each made of a metal material. The ratio of the linear expansion coefficient of the housing 40 to the linear expansion coefficient of the bearing holder 10 is preferably 0.9 or more and 1.1 or less. The motor 1 may thermally expand or contract due to a temperature change caused by the ambient environment or the driving of the motor 1. According to the present embodiment, by setting the ratio of the linear expansion coefficient of the housing 40 to the linear expansion coefficient of the bearing holder 10 within the above range, the difference in dimensional change between the bearing holder 10 and the housing 40 with respect to temperature change can be reduced, and the outer edge portion 14 can be prevented from coming off the groove portion 44. Most preferably, the bearing holder 10 and the housing 40 are made of the same material. In this case, the linear expansion coefficients of the bearing holder 10 and the housing 40 can be made the same. In addition, when the radially outer edge portion 14 is sufficiently deeply received in the groove portion 44, the outer edge portion 14 is not easily detached from the groove portion 44 even when the bearing holder 10 and the housing 40 expand or contract at a high temperature or a low temperature. Therefore, in this case, the linear expansion coefficient of the bearing holder 10 can be made smaller than the linear expansion coefficient of the housing 40.

< modification 1 >

Fig. 3 is a partial sectional view of the motor 101 of modification 1. The motor 101 of the present modification differs from the above-described embodiment in the structure for holding the bearing holder 110 and the housing 140. The same reference numerals are given to the same constituent elements as those of the above embodiment, and the description thereof will be omitted.

The housing 140 has a cylindrical portion 145, and the cylindrical portion 145 is provided with an inner peripheral surface 145c facing radially inward. A groove 144 extending in the circumferential direction is provided on the inner circumferential surface 145c of the cylindrical portion 145.

The inner circumferential surface 145c is provided with a lower inner circumferential surface 145e located below the groove 144 and an upper inner circumferential surface 145d located above the groove 144. The inner diameter of the lower inner peripheral surface 145e is equal to that of the upper inner peripheral surface 145 d. The inner peripheral surface 145c of the cylindrical portion 145 is machined by a cutting process. The inner peripheral surface 145c is formed by machining the groove portion 144 after machining the entire axial region to the inner diameter of the lower inner peripheral surface 145e (the inner diameter of the upper inner peripheral surface 145 d) by a cutting process. Therefore, the number of steps can be reduced compared to the case where the inner diameter of the lower inner peripheral surface 145e is different from the inner diameter of the upper inner peripheral surface 145 d.

The bearing holder 110 includes: a flat portion 116 extending along a plane perpendicular to the central axis J; and an extension 115 located radially outward of the flat portion 116. Although not shown in fig. 3, the bearing holder 110 includes an upper bearing holding portion (holding portion) 18 and a bent portion 17, as in the above-described embodiment. The upper bearing holding portion (holding portion) 18 and the curved portion 17 are located radially inward of the flat portion 116.

The extension 115 extends axially downward from the outer edge of the flat portion 116. The extension 115 extends cylindrically in the circumferential direction. The extending portion 115 radially faces the inner peripheral surface 145c of the cylindrical portion 145.

The extension 115 has a projection 119. The protruding portion 119 protrudes radially outward from the radially outward surface of the extending portion 115. The projection 119 is located in the lower region of the extension 115. The convex portion 119 is arranged offset axially downward with respect to the flat portion 116. That is, the upper end of the projection 119 is located below the lower surface 116a of the flat portion 116. The convex portion 119 extends in the circumferential direction with the same dimension in the axial direction. The upper region 115a of the extension portion 115 and the upper inner peripheral surface 145d of the cylindrical portion 145 face each other with a gap in the radial direction.

An outer edge 114 is provided on the outer edge of the projection 119. That is, the outer edge portion 114 extends radially outward from the extending portion 115. The outer edge portion 114 is axially offset from the flat portion 116. The outer edge portion 114 constitutes the outer shape of the bearing holder 110. The outer edge portion 114 is housed in a groove portion 144, and the groove portion 144 is provided on an inner peripheral surface 145c of the cylindrical portion 145. That is, the bearing holder 110 has the outer edge portion 114 received in the groove portion 144.

The outer edge portion 114 has an outer peripheral surface 114a facing radially outward. The outer peripheral surface 114a has an outer diameter larger than an inner diameter of the inner peripheral surface 145 c. Here, the inner diameter of the inner peripheral surface 145c refers to the inner diameter of the upper inner peripheral surface 145d and the inner diameter of the lower inner peripheral surface 145 e. The outer diameter of the outer peripheral surface 114a is smaller than the inner diameter of the bottom surface 144a of the groove 144. Therefore, the outer edge portion 114 is positioned inside the groove portion 144. The outer peripheral surface 114a faces the bottom surface 144a of the groove 144 with a gap in the radial direction.

According to this modification, the outer edge portion 114 of the bearing holder 110 is housed in the groove portion 144, as in the above embodiment. Therefore, when axial stress is applied to the bearing holder 110, the outer edge portion 114 is prevented from moving by coming into contact with the upper groove wall surface 144b and the lower groove wall surface 144c of the groove portion 144. This enables the bearing holder 110 to be held by the housing 140.

According to the present modification, a gap is provided between the outer peripheral surface 114a of the outer edge portion 114 and the bottom surface 144a of the groove portion 144. Therefore, the cylindrical portion 145 is not stressed radially outward from the bearing holder 110, and deformation of the cylindrical portion 145 can be suppressed.

Since the outer rim portion 114 is housed in the groove portion 144, even when the outer peripheral surface 114a of the outer rim portion 114 is brought into contact with the bottom surface 144a of the groove portion 144 and fixed by shrink fitting, the interference can be reduced while securing the holding force. In the present modification, the outer edge portion 114 is arranged offset in the axial direction with respect to the flat portion 116, and the flat portion 116 and the cylindrical portion 145 are opposed to each other with a gap in the radial direction. Therefore, even when the outer peripheral surface 114a of the outer edge portion 114 is brought into contact with the bottom surface 144a of the groove portion 144 and fixed by shrink fitting, the stress applied from the cylindrical portion 145 to the bearing holder 110 toward the radial inner side is not directly applied to the flat portion 116. Stress directed radially inward is applied in the direction of axially deflecting the flat portion 116, so that the bearing holder 110 is easily deformed. As a result, the reaction force applied from the bearing holder 110 to the housing 140 can be reduced, and the amount of deformation of the housing 140 can be suppressed.

While the embodiment and the modified examples of the present invention have been described above, the configurations and combinations thereof in the embodiment and the modified examples are only examples, and addition, omission, replacement, and other modifications of the configurations can be made without departing from the scope of the present invention. In addition, the present invention is not limited by the embodiments.

Description of the reference symbols

1. 101: a motor; 5: wave washers (elastic members); 6A: an upper side bearing (bearing); 9: an external device (control unit); 10. 110: a bearing retainer; 14. 114: an outer edge portion; 14a, 114 a: an outer peripheral surface; 15. 115: an extension portion; 16. 116: a flat portion; 17 a: a groove; 18: an upper bearing holding section (holding section); 20: a rotor; 21: a shaft; 30: a stator; 40. 140: a housing; 44. 144, and (3) 144: a groove part; 44a, 144 a: a bottom surface; 44 b: an upper groove wall surface (upper groove wall surface); 44 c: a lower groove wall surface (lower groove wall surface); 45. 145: a cylindrical portion; 45c, 145 c: an inner peripheral surface; 45d, 145 d: an upper inner peripheral surface; 45e, 145 e: a lower inner peripheral surface; j: a central axis.

Claims

1. A motor is characterized in that a motor is provided,

the motor has:

a rotor having a shaft disposed along a central axis extending in a vertical direction and rotating around the central axis;

a stator that is opposed to the rotor with a gap therebetween in a radial direction;

a housing having a cylindrical portion surrounding the stator from a radial outer side;

a bearing for rotatably supporting the shaft; and

a bearing holder which is held by the cylindrical portion and supports the bearing,

a groove portion extending in the circumferential direction is provided on the inner circumferential surface of the housing,

the bearing holder has an outer edge portion received in the groove portion,

the outer edge portion is axially opposed to at least one of upper and lower groove wall surfaces of the groove portion with a gap therebetween.

2. The motor of claim 1,

the outer peripheral surface of the outer edge portion and the bottom surface of the groove portion facing radially inward face each other with a gap in a radial direction.

3. The motor of claim 1,

the motor includes an elastic member interposed between the outer ring of the bearing and the bearing holder, and pressing the outer edge portion against a groove wall surface on an upper side or a lower side of the groove portion.

4. The motor of claim 1,

the inner peripheral surface of the cylindrical portion is provided with a lower inner peripheral surface located below the groove portion and an upper inner peripheral surface located above the groove portion,

the inner diameter of the lower inner circumferential surface is equal to the inner diameter of the upper inner circumferential surface.

5. The motor of claim 1,

the inner diameter of the upper inner circumferential surface is larger than that of the lower inner circumferential surface.

6. The motor of claim 1,

the bearing holder has:

a flat portion extending along a plane perpendicular to the central axis; and

an extension portion extending from the flat portion in an axial direction,

the outer edge portion extends radially outward from the extending portion and is axially offset from the flat portion.

7. The motor of claim 1,

the bearing holder has a holding portion for holding the bearing,

the bearing holder is provided with a groove which is located radially outside the holding portion, extends in the circumferential direction, and opens in the axial direction.

8. The motor of claim 1,

a housing space for housing a control unit that controls energization to the stator is provided radially inside the cylindrical portion and above the bearing holder.

9. The motor of claim 1,

the ratio of the coefficient of linear expansion of the housing to the coefficient of linear expansion of the bearing holder is 0.9 or more and 1.1 or less.

10. The motor of claim 1,

the surface roughness of the inner peripheral surface of the cylindrical portion is the same on the upper side of the bearing holder and on the lower side of the bearing holder.