JP2015195705A - motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor which surely protects a ball bearing without generating deformation or the like of a bearing housing with respect to an axially external force applied to a rotor part.SOLUTION: The motor includes: a cylindrical bearing housing; a ball bearing that is fitted to an inner peripheral surface of the bearing housing; a stator part fixed at an outer peripheral side of the bearing housing; a rotary shaft supported by the ball bearing in a rotatable manner; a rotor part including a magnet that faces the stator part, and attached to the rotary shaft; an elastic member applying a preload to the ball bearing; and a support plate that is attached to one opening end of the bearing housing and opposes an end face of the rotary shaft. A distance between the end face of the rotary shaft and the support plate is shorter than a distance for the ball bearing to move from a preload application state of the elastic member to a perfect compression state.

Description

  The present invention relates to a motor.

  There is known a motor that supports a rotating shaft of a rotor portion by two ball bearings housed in a bearing housing. This type of motor has two ball bearings arranged axially inside a cylindrical bearing housing, and the rotor part can be rotated by inserting the rotating shaft of the rotor part into the inner ring of the two ball bearings. To support. Moreover, the structure which provides the spring which provides a preload to a ball bearing is taken.

  In such a conventional motor, when an axial force is applied to the rotor, the ball bearing may be damaged and stable rotation may not be obtained. For this reason, the structure which provided the projection part which receives force in the location where a rotor part and a stator part contact | abut, and a load is not applied directly to a ball bearing is known (refer patent document 1 and patent document 2). ).

  More specifically, in Patent Document 1, in a DC brushless fan motor, a soft cushioning material is disposed at a location where the rotor portion and the stator portion abut against each other by an external force so as not to damage the ball bearing. Further, in Patent Document 2, a protrusion is provided on the rotor boss of the rotor portion so as to face the end surface of the bearing housing, and when the rotor portion moves in the axial direction by an external force, the protrusion contacts the bearing housing. The impact is not applied to the.

Japanese Patent Publication No.6-1963 Japanese Utility Model Publication No. 1-66496

  However, in the conventional motor described above, in the case of Patent Document 1, an impact applied to the rotor portion is received by the cushioning material of the stator portion. For this reason, when a large force acts on the rotor portion in the axial direction, the cushioning material is easily deformed and there is no function of preventing movement in the axial direction. Therefore, the ball bearing cannot be protected, and the ball bearing may be damaged.

  Further, in the case of Patent Document 2, a force that acts on the rotor portion in the axial direction is received by the bearing housing for connecting the rotor portion to the rotation shaft. The protection effect of the ball bearing can be expected as compared with the case of Patent Document 1, but when a stronger impact is applied to the rotating body, the bearing housing itself holding the ball bearing may be deformed or damaged. If the bearing housing is deformed or damaged, not only the ball bearing cannot be stably held, but also the stator portion attached to the outside of the bearing housing is distorted. In particular, in the case where the rotary shaft protrudes from the rotor portion and a load is attached to the protruding end, it is easy to receive a large axial impact from the rotary shaft, and the above-described problem becomes significant.

  The present invention has been made in view of the above points, and provides a motor that reliably protects a ball bearing without causing deformation of the bearing housing with respect to an axial external force applied to the rotor portion. Objective.

  In order to solve the above-described problems, a motor according to an exemplary first invention of the present application includes a cylindrical bearing housing, a ball bearing fitted to an inner peripheral surface of the bearing housing, and an outer peripheral side of the bearing housing. A stator portion fixed to the ball bearing, a rotating shaft rotatably supported by the ball bearing, a rotor portion having a magnet facing the stator portion and attached to the rotating shaft, and preloading the ball bearing An elastic member, and a receiving plate attached to one open end of the bearing housing and facing the end surface of the rotating shaft, and the distance between the end surface of the rotating shaft and the receiving plate is determined by the ball bearing. It is smaller than the distance that the elastic member moves from the preload applied state to the fully compressed state.

  According to an exemplary embodiment of the present invention, it is possible to provide a motor that reliably protects a ball bearing without causing deformation of the bearing housing against an axial external force applied to the rotor portion.

FIG. 1 is a cross-sectional view of a motor according to an embodiment. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is a bottom view of the motor according to the embodiment. FIG. 4 is a perspective view of a bearing housing provided in the motor according to the embodiment. FIG. 5 is a partial cross-sectional view of the motor of the first modification. FIG. 6 is a partially enlarged view of FIG. FIG. 7 is a bottom view of the motor of the first modification. FIG. 8 is a perspective view of a receiving plate provided in the motor of the first modification. FIG. 9 is a perspective view of a backing plate of the second modification. FIG. 10 is a partial cross-sectional view of the motor of the third modification.

Hereinafter, embodiments will be described with reference to the drawings.
In the drawings used in the following description, for the purpose of emphasizing the feature portion, the feature portion may be shown in an enlarged manner for convenience, and the dimensional ratios of the respective constituent elements are not always the same as in practice. Absent. In addition, for the same purpose, portions that are not characteristic may be omitted from illustration.
Each figure shows an XYZ coordinate system. In the following description, each direction will be described based on each coordinate system as necessary.

The motor 1 of this embodiment is an outer rotor type brushless motor.
FIG. 1 is a sectional view of the motor 1, and FIG. 2 is a partially enlarged view of the vicinity of the bearing housing 20 of FIG. In FIG. 2, the stator portion 30 is omitted. FIG. 3 is a bottom view of the motor 1 as viewed from below.
In the description of each part of the present specification, the + Z direction in the drawing is defined as the upward direction, and the −Z direction is defined as the downward direction. However, the motor 1 is not limited to use in a state where the + Z direction is the upward direction. For example, the motor 1 may be used in a state where the + Z direction is horizontal or downward.

As shown in FIG. 1, the motor 1 includes a bearing housing 20, an upper ball bearing (ball bearing) 40, a lower ball bearing 42, a stator portion 30, a rotating shaft 52, a rotor portion 50, and an elastic member. 44 and a receiving plate 60.
The bearing housing 20 is cylindrical. The upper ball bearing 40 and the lower ball bearing 42 are fitted to the inner peripheral surface of the bearing housing. The stator portion 30 is fixed to the outer peripheral side of the bearing housing 20. The rotating shaft 52 is rotatably supported by the upper ball bearing 40 and the lower ball bearing 42. The rotor unit 50 has a rotor magnet (magnet) 56 facing the stator unit 30 and is attached to a rotating shaft. The elastic member 44 applies preload to the upper ball bearing 40 and the lower ball bearing 42. The receiving plate 60 is attached to one open end of the bearing housing 20 and faces the end surface 52 e of the rotating shaft 52.
Hereinafter, the structure of each part is demonstrated concretely.

<Motor base>
The motor base 10 is a metal flat plate.
As shown in FIG. 3, an opening 12 is provided in the approximate center of the motor base 10. The opening 12 includes a circular hole 12a and a rectangular notch 12b extending radially outward from three locations on the outer periphery of the circular hole 12a. A receiving plate 60 is accommodated in the opening 12.
A bearing housing 20 is disposed on the upper surface 10 b of the motor base 10 so that the cylindrical inner peripheral surface thereof matches the circular hole 12 a of the opening 12. Around the opening 12, three first screw holes 15 for attaching the stator portion 30 and the bearing housing 20 are provided.

As shown in FIG. 1, a circuit board 70 is fixed to an upper surface 10 b that is an upper surface of the motor base 10. The motor base 10 and the circuit board 70 are fixed by screws, for example.
The circuit board 70 constitutes a motor drive circuit by mounting various electronic components. The circuit board 70 is provided with lands, and terminals of the winding 36 extending from the stator portion 30 are soldered and connected. On the circuit board 70, a Hall IC 72 for detecting a magnetic pole is mounted. The Hall IC 72 is disposed in the vicinity of the rotor magnet 56 of the rotor unit 50 and detects the rotation angle of the rotor unit 50. A connector (not shown) is mounted at a position away from the rotor unit 50 on the circuit board 70. An external device is connected to the connector, and power and control signals are supplied from the external device.

<Bearing housing>
As shown in FIG. 2, the bearing housing 20 has a cylindrical shape, and is disposed on the radially outer side of the rotating shaft 52 and on the radially inner side of the stator portion 30. The bearing housing 20 includes a cylindrical portion 21, an annular projecting portion 22 provided on the inner peripheral surface of the cylindrical portion 21, and a flange portion 24 provided on the outer peripheral surface of the cylindrical portion 21.

  The annular projecting portion 22 of the bearing housing 20 projects inward in the radial direction of the cylindrical portion 21 to reduce the inner diameter of the cylindrical portion 21. The annular projecting portion 22 is located substantially at the center in the vertical direction on the inner peripheral surface of the cylindrical portion 21. On the inner peripheral surface of the cylindrical portion 21, an upper ball bearing 40 and a lower ball bearing 42 are disposed above and below the annular protrusion 22, respectively.

  FIG. 4 is a perspective view of the bearing housing 20. The flange portion 24 of the bearing housing 20 protrudes in a disk shape on the radially outer side of the cylindrical portion 21. The flange portion 24 is located at the lower end on the outer peripheral surface of the cylindrical portion 21. As shown in FIG. 4, the flange portion 24 has three protruding portions 24 c that protrude further outward from the outer peripheral end of the flange portion 24. The three projecting portions 24 c are arranged at positions that are rotationally symmetric with respect to the central axis of the cylindrical portion 21. A first through hole 25 is provided in the protruding portion 24c. As shown in FIG. 1, a first screw 38 is inserted into the first through hole 25. The first screw 38 is screwed into the first screw hole 15 of the motor base 10 to fix the bearing housing 20 to the motor base 10.

  As shown in FIG. 2, a second screw hole 27 is provided on the lower surface 24 b of the bearing housing 20. A second screw 62 inserted into a second through hole 65 provided in the receiving plate 60 is screwed into the second screw hole 27. Accordingly, the receiving plate 60 is fixed to the lower surface 24 b of the bearing housing 20 so as to close the lower opening of the cylindrical portion 21 of the bearing housing 20.

<Bearing>
As shown in FIG. 2, the upper ball bearing 40 and the lower ball bearing 42 are fixed by fitting outer rings 40 a and 42 a to the inner peripheral surface of the cylindrical portion 21 of the bearing housing 20. A rotating shaft 52 is inserted into the inner rings 40b and 42b of the upper ball bearing 40 and the lower ball bearing 42, respectively. The upper ball bearing 40 and the lower ball bearing 42 support the rotating shaft 52 in a rotatable manner.
The upper surface of the inner ring 40 b of the upper ball bearing 40 is in contact with the lower end surface of the burring portion 54 d in the rotor holder 54 of the rotor portion 50. An elastic member 44 is disposed between the upper ball bearing 40 and the annular protrusion 22.
The upper surface of the outer ring 42 a of the lower ball bearing 42 is in contact with the lower end surface of the annular protrusion 22. The lower surface of the inner ring 42 b of the lower ball bearing 42 is in contact with a retaining ring 58 attached to the tip of the rotating shaft 52.

<Rotating shaft>
As shown in FIG. 1, the rotating shaft 52 has a rotation support part 52a and a load attachment part 52b. The rotation support portion 52 a is slightly longer than the axial length of the bearing housing 20 and is inserted into the inner rings of the ball bearings 40 and 42. The load attachment portion 52b has a larger diameter than the rotation support portion 52a and protrudes longer upward than the rotation support portion 52a. A load (not shown) for applying rotation is attached to the load attachment portion 52b.
A knurled surface 52c is provided on the rotation support portion 52a. The rotor holder 54 of the rotor unit 50 is press-fitted into the knurled surface 52c.

As shown in FIG. 2, the lower end of the rotation support portion 52 a of the rotation shaft 52 protrudes downward from the lower surface of the lower ball bearing 42. An annular groove 52d for attaching a retaining ring (a retaining washer) 58 is provided in the vicinity of the lower end of the rotation support portion 52a.
The lower end surface 52e of the rotating shaft 52 has a rounded convex shape. The shape of the end surface 52e is a rotationally symmetric shape around the central axis of the rotating shaft 52, and the center protrudes downward.

<Elastic member>
The elastic member 44 is a preload spring made of, for example, a leaf spring. As the elastic member 44, for example, a disc spring or a wave washer can be employed. As shown in FIG. 2, the elastic member 44 is disposed between the upper ball bearing 40 and the annular protrusion 22 in a properly compressed state. The elastic member 44 applies an upward force to the outer ring 40 a of the upper ball bearing 40. The inner ring 40 b of the upper ball bearing 40 is lifted upward by the elastic member 44 until the upper surface 40 c comes into contact with the lower end surface of the burring portion 54 d in the rotor holder 54 of the rotor portion 50. Thereby, a preload is applied to the upper ball bearing 40.
Further, together with the inner ring 40b of the upper ball bearing 40, the rotating shaft 52 is lifted upward. Accordingly, the inner ring 42b of the lower ball bearing 42 that contacts the retaining ring 58 at the tip of the rotating shaft 52 is also lifted upward, and the inner ring 42b of the lower ball bearing 42 is moved upward. Thereby, a preload is applied to the lower ball bearing 42.
As described above, the elastic member 44 applies a preload to the two ball bearings 40 and 42 to ensure smooth rotation of the rotating shaft 52.

<Back plate>
As shown in FIG. 3, the receiving plate 60 has substantially the same shape as the opening 12 of the motor base 10 and is accommodated in the opening 12.
The receiving plate 60 includes a disc portion 63 and three projecting plate portions 64 that extend radially outward from the disc portion 63. As shown in FIG. 2, the protruding plate portion 64 is provided with a second through hole 65. The receiving plate 60 is attached to the bearing housing 20 by the second screw 62 being fastened to the second screw hole 27 of the bearing housing via the second through hole 65.

The lower surface 60a of the backing plate and the lower surface 10a of the motor base are surfaces having a uniform height. That is, the lower surface 60 a of the receiving plate 60 is substantially flush with the lower surface 10 a of the motor base 10. The receiving plate 60 faces the lower end surface 52e of the rotation shaft 52. As shown in FIG. 2, a gap L <b> 1 is provided between the lower end surface 52 e of the rotation shaft 52 and the upper surface of the receiving plate 60. The clearance L <b> 1 is set to be smaller than the distance L <b> 2 by which the ball bearing 40 moves from the preload application state of FIG. 2 to the fully compressed state by the elastic member 44 due to the axially downward force applied to the rotating shaft 52.
When a downward external force larger than the upward force by the elastic member 44 is applied to the rotating shaft 52, the rotating shaft 52 moves downward and the lower end contacts the receiving plate 60. The backing plate 60 supports stress applied to the rotating shaft 52 and prevents the ball bearings 40 and 42 from being damaged.

<Stator part>
As shown in FIG. 1, the stator portion 30 is attached to the upper surface 10 b side of the motor base 10. The stator unit 30 includes a stator core 32, an insulator 34, and a winding 36. The stator core 32 has an annular core back and a plurality of magnetic teeth protruding radially outward from the core back. The insulator 34 covers at least each magnetic tooth of the stator core 32. The winding 36 is wound around each magnetic tooth of the stator core 32 via an insulator 34 to form a coil.

The stator core 32 of the stator portion 30 is fitted on the outer periphery of the cylindrical portion 21 of the bearing housing 20. Further, the lower surface of the stator core 32 is in contact with the upper surface 24 a of the flange portion 24 of the bearing housing 20. Thereby, the axial position of the stator portion 30 is determined by the upper surface 24a of the flange portion 24 (that is, the surface opposite to the motor base).
The stator core 32 is provided with a hole 32a penetrating in the axial direction. A first screw 38 is inserted into the hole 32a. The first screw 38 is inserted into the hole 32 a of the stator core 32 and the first through hole 25 of the bearing housing 20, and is screwed into the first screw hole 15 of the motor base 10. As a result, the bearing housing 20 is fixed to the motor base 10, and the stator portion 30 is supported by the bearing housing 20.

<Rotor part>
The rotor unit 50 includes a rotor holder 54 and a rotor magnet 56, and is attached to the rotating shaft 52. The rotor unit 50 rotates relative to the stator unit 30 about the central axis J together with the rotation shaft 52.
The rotor holder 54 is made of metal and has a cup shape. The rotor holder 54 has a top plate portion 54a in which the rotation shaft 52 is connected to the central portion, and a cylindrical portion 54b that extends the outer peripheral portion of the top plate portion 54a downward. A circular concave portion 54c and a burring portion 54d are formed in the central portion of the top plate portion 54a.

A stepped surface provided at the boundary between the rotation support portion 52a of the rotating shaft 52 and the load mounting portion 52b is in contact with the bottom surface of the circular recess 54c of the rotor holder 54. A knurled surface 52c of the rotating shaft 52 is press-fitted into the inner peripheral surface of the burring portion 54d. Thereby, the rotor holder 54 and the rotating shaft 52 are integrally coupled. The knurled surface 52c prevents the rotating shaft 52 and the rotor holder 54 from spinning freely.
The coupling between the rotating shaft 52 and the rotor holder 54 is not limited to press-fitting, and an adhesive may be used, or press-fitting and adhesion may be used in combination.

  The rotor magnet 56 is attached to the inner peripheral surface of the cylindrical portion 54 b in the rotor holder 54. The rotor magnet 56 is a permanent magnet that arranges different magnetic poles in the circumferential direction of the rotor holder 54.

<Action, effect>
Generally, a force may be applied to the rotating shaft 52 of the motor 1 toward the lower side in the axial direction as an excessive load or impact. In such a case, force is transmitted to the inner ring 40b of the ball bearing 40 that supports the rotating shaft 52, and the elastic member 44 is compressed. When the axial downward force acting on the rotating shaft 52 exceeds the fully compressed state of the elastic member 44, the ball bearings 40 and 42 support the axial downward force. If it does so, there exists a possibility that damage and a deformation | transformation may generate | occur | produce in each outer ring | wheel 40a, 42a, inner ring | wheel 40b, 42b, and a ball | bowl of the ball bearings 40 and 42.

  According to the motor 1 of the present embodiment, when the rotating shaft 52 is pushed downward in the axial direction, the lower end surface 52e of the rotating shaft 52 contacts the receiving plate 60 before the elastic member 44 is completely compressed. . Thereby, the receiving plate 60 receives the axial downward force applied to the rotating shaft 52, and the receiving plate 60 supports the elastic member 44 so that the elastic member 44 is not completely compressed. As a result, even if an excessive force is not applied to the ball bearings 40 and 42 and a large impact force is generated on the rotating shaft 52 or a large force that pushes the rotating shaft 52 downward in the axial direction is generated, the rotating shaft 52 is reliably supported, The bearings 40 and 42 can be protected. Moreover, damage to the elastic member 44 can also be prevented by avoiding the fully compressed state of the elastic member 44.

  In addition, according to the motor 1 of the present embodiment, the downward force in the axial direction applied to the rotating shaft 52 is supported by the receiving plate 60, so that it is not necessary to support the upper end of the bearing housing 20. Therefore, since the bearing housing 20 is not deformed by the force applied to the rotating shaft 52, a stable rotation state of the rotor portion 50 can be ensured.

  Further, in the motor 1 of the present embodiment, the lower end surface 52e of the rotating shaft 52 has a rounded convex shape with the center protruding downward. When the axially downward force applied to the rotating shaft 52 is supported by the receiving plate 60 on the end surface 52e of the rotating shaft 52, the end surface 52e of the rotating shaft 52 makes point contact with the receiving plate 60 at the center. When the rotating shaft 52 rotates with the rotating shaft 52 and the receiving plate 60 in contact with each other, the frictional resistance in the rotating direction is small and rotation loss can be suppressed. Such an effect is a characteristic effect when the end surface 52e of the rotating shaft 52 is supported by the receiving plate 60, and cannot be obtained when the force applied to the rotating shaft 52 is supported by the upper end of the bearing housing 20. It is.

<Modification 1>
Next, the motor 2 of the modification 1 is demonstrated based on FIGS. FIG. 5 is a part of a sectional view of the motor 2 of the first modification. 6 is a partially enlarged view of region A in FIG. FIG. 7 is a bottom view of the motor 2. FIG. 8 is a perspective view of a receiving plate 160 provided in the motor 2.
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 motor 2 of Modification 1 includes a bearing housing 120, a motor base 110, and a receiving plate 160 in place of the bearing housing 20, the motor base 10, and the receiving plate 60 in the motor 1 described above.

As shown in FIG. 8, the receiving plate 160 has a main body 168 and a sliding plate member 180.
The main body 168 is a metal plate member having sufficient rigidity. The main body portion 168 includes a disc portion 163 and three protruding plate portions 164. The protruding plate portion 164 is provided with a second through hole 165. A circular accommodation recess 161 is provided at the center of the disc portion 163. The housing recess 161 is provided on a surface (upper surface) 168 b facing the rotation axis of the main body 168. The main body 168 corresponds to a configuration in which the housing recess 161 is provided on the upper surface of the receiving plate 60 of the motor 1.

  The housing recess 161 of the main body 168 can be formed by pressing. In this case, the convex portion 169 is formed on the lower surface 168 a of the main body portion 168 together with the accommodating concave portion 161 at a position overlapping the accommodating concave portion 161 when viewed from the axial direction. As shown in FIG. 5, the height of the convex portion 169 is preferably lower than the head of the second screw 62 for fixing the receiving plate 160 to the bearing housing 120. Thereby, the convex part 169 does not protrude from the lower side of the motor 2, and the increase in the dimension of the motor 2 by the convex part 169 can be suppressed.

  As shown in FIG. 5, the second screw 62 is inserted into the second through hole 165 provided in the protruding plate portion 164 of the main body portion 168. The receiving plate 160 is attached to the bearing housing 120 by fastening the second screw 62 to the second screw hole 127 provided in the bearing housing 120 via the second through hole 165.

  The sliding plate member 180 is housed in the housing recess 161 of the main body 168. The sliding plate member 180 is disposed to face the end surface 52e of the rotating shaft 52. A gap L1 between the upper surface 180b of the sliding plate member 180 and the end surface 52e of the rotating shaft 52 is set to be smaller than a distance L2 at which the elastic member 44 moves to a fully compressed state. When the axially downward force is applied to the rotating shaft 52, the end surface 52e of the rotating shaft 52 contacts the sliding plate member 180 before the elastic member 44 is in a completely compressed state.

  The sliding plate member 180 is made of, for example, a hard resin, and a material having a low coefficient of friction with the metal material constituting the rotating shaft 52 is selected. Since the sliding plate member 180 is made of a hard resin, the sliding plate member 180 is not easily deformed when receiving a force from the rotating shaft 52, and even when the rotating shaft 52 rotates in contact with the sliding plate member 180, energy loss during rotation is lost. Can be suppressed. As the sliding plate member 180, for example, a polyslider (registered trademark) can be adopted.

The sliding plate member 180 is fitted in the housing recess 161. In the present embodiment, the housing recess 161 has a circular shape when viewed from the axial direction. The sliding plate member 180 has a rounded rectangular shape with four corners 181 rounded. The corners of the sliding plate member 180 are in press contact with the inner wall of the housing recess.
Since the sliding plate member 180 is fitted in the housing recess 161, the certainty of holding the sliding plate member 180 in the housing recess 161 can be increased.
Moreover, when the sliding plate member 180 is rectangular, when the sliding plate member is punched from the plate material, the number of sliding plate members 180 can be increased.

As shown in FIG. 5, the thickness of the sliding plate member 180 substantially coincides with the depth of the accommodating recess 161. The surface (upper surface) 168b on the rotating shaft side of the main body 168 and the surface (upper surface) 180b on the rotating shaft side of the sliding plate member 180 are arranged at positions aligned in the axial direction. Here, the depth of the accommodation recess 161 means the distance from the upper surface of the upper surface 168b of the main body 168 of the receiving plate 160 to the bottom surface 161a of the accommodation recess 161.
The thickness of the sliding plate member 180 is preferably larger than the gap L1 between the upper surface 180b of the sliding plate member 180 and the end surface 52e of the rotating shaft 52. By making the thickness of the sliding plate member 180 larger than the gap L <b> 1, the sliding plate member 180 can be prevented from sliding down from the accommodation recess 161.

Next, the motor base 110 and the bearing housing 120 of the motor 2 will be described with reference to FIGS.
The motor base 110 of the motor 2 has substantially the same structure as the motor base 10 of the motor 1, but as shown in FIG. 6, a recess 116 is provided on the lower surface 110a and a protrusion 117 is provided on the upper surface 110b. The point is mainly different.
The bearing housing 120 of the motor 2 has substantially the same structure as the bearing housing 20 of the motor 1, except that a positioning recess 126 is provided on the lower surface 124 b as shown in FIG. 6.

As shown in FIG. 7, the motor base 110 is provided with an opening 112 for receiving the receiving plate 160.
Further, as shown in FIG. 6, the motor base 110 is provided with a recess 116 in a surface (lower surface) 110 a opposite to the bearing housing 120. Further, the motor base 110 is provided with a convex portion 117 on the upper surface 110b facing the bearing housing 120 so as to overlap the concave portion when viewed in the axial direction. The recess 116 and the protrusion 117 can be formed by press working in the thickness direction of the motor base 110. Further, the motor base 110 is provided with a first screw hole 115 that penetrates in the axial direction and opens into the recess.

  On the other hand, the bearing housing 120 is provided with a first through hole 125. In addition, the bearing housing 120 is provided with a positioning recess 126 in which a first through hole 125 is opened on a lower surface 124 b facing the upper surface 110 b of the motor base 110. The positioning recess 126 accommodates the convex portion 117 of the motor base 110. Thereby, positioning of the bearing housing 120 with respect to the motor base 110 can be performed easily.

  The bearing housing 120 is attached to the motor base with a first screw 138 fastened to the first screw hole of the motor base 110 via the first through hole 125. The tip 138 a of the first screw 138 is accommodated in the recess 116 of the motor base 110. Accordingly, the tip 138a of the first screw does not protrude from the lower surface 110a of the motor base 110. Therefore, the tip 138a of the first screw 138 does not damage other members or the operator's hand.

As shown in FIG. 7, the bearing housing 120 is attached to the motor base 110 by three first screws 138. The receiving plate 160 is attached to the bearing housing 120 with three second screws 62. The three first screws 138 and the three second screws 62 are alternately arranged around the central axis J of the rotation shaft 52. Further, in the present modification, the first screw 138 and the second screw 62 are arranged at equal intervals.
By alternately arranging the first screw 138 and the second screw 62 around the central axis J of the rotating shaft, the receiving plate 160 and the bearing housing 120 can be fixed, and the motor base 110 and the bearing housing 120 can be fixed. Fixing can be performed stably with a minimum number of screws.

  According to the motor 2 of this modified example, the receiving plate 160 has the sliding plate member 180 and is disposed to face the end surface 52e of the rotating shaft 52. Accordingly, when an axially downward force is applied to the rotating shaft 52 and the elastic member 44 is compressed, the end surface 52e of the rotating shaft 52 and the sliding plate member 180 come into contact with each other. Since the sliding plate member 180 is made of a material having a low coefficient of friction with the rotating shaft 52, when the rotating shaft 52 rotates in a state where the rotating shaft 52 and the sliding plate member 180 are in contact with each other, the frictional resistance in the rotating direction is reduced. Less rotation loss can be suppressed.

  In addition, since the friction coefficient is low, even if the rotation shaft 52 rotates while the rotation shaft 52 and the sliding plate member 180 are in contact with each other, the end surface 52e of the rotation shaft 52 and the sliding plate member 180 are not easily worn. Therefore, it is possible to suppress the gap L1 between the sliding plate member 180 and the end surface 52e of the rotating shaft 52 from increasing due to wear. In the motor 2 of this modification, the gap L1 is set to be smaller than the distance L2 that the elastic member 44 moves to the fully compressed state. Thereby, the motor 2 avoids the complete compression state of the elastic member 44 and protects the ball bearings 40 and 42 when the axially downward force is applied to the rotating shaft 52. By suppressing the wear and suppressing the gap L1 from becoming large, the motor 2 ensures a sufficiently large gap L1 not only in the initial state but also after a long period of use, and the ball bearing 40. , 42 can be protected. Thereby, the service life of the motor 2 can be lengthened.

  Note that the sliding plate member 180 of this modification has a rounded rectangular shape with four corners 181 rounded, but the shape is not limited to this, and a circular shape may be used, for example. . Similarly, the accommodation recess 161 provided in the main body 168 of the receiving plate 160 is not limited to a circle that can fit and hold the sliding plate member 180.

<Modification 2>
Next, a receiving plate 260 of Modification 2 that can be used in the motor 2 of Modification 1 will be described with reference to FIG. FIG. 9 is a perspective view of the receiving plate 260.
The receiving plate 260 has a main body portion 268 and a sliding plate member 280.
The main body 268 has a triangular shape as viewed in the axial direction, and a second through hole 265 is provided in the vicinity of each vertex 264. The main body 268 is provided with a circular housing recess 261 for housing the sliding plate member 280 at the center. A second screw 62 (see FIG. 5) is inserted into the second through hole 265. The receiving plate 260 is fixed to the bearing housing by the second screw 62.

Since the receiving plate 260 of this modification has a simple triangular shape, the shape of the mold is simplified in manufacturing by punching with a press, and the receiving plate 260 can be stably manufactured at low cost.
When the receiving plate 260 of this modification is employed, the motor base 110 is preferably provided with an opening (corresponding to the opening 112 in FIG. 7) having substantially the same shape as the receiving plate 260. .

<Modification 3>
Next, the motor 3 of Modification 3 will be described with reference to FIG. FIG. 10 is a part of a sectional view of the motor 3 of the third modification.
In addition, about the component of the aspect same as the above-mentioned embodiment and modification, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  The motor 3 of Modification 3 has a rotation shaft 352 and a receiving plate 360 instead of the rotating shaft 52 and the receiving plate 60 in the motor 1 described above.

The rotating shaft 352 includes a shaft body 353 and a sliding plate member 355.
The shaft body 353 is rotatably supported by the upper ball bearing 40 and the lower ball bearing 42. An accommodation recess 353 a is provided on the lower end surface 353 b of the shaft body 353. A sliding plate member is housed in the housing recess 353a. The shape and depth of the housing recess 353a are not particularly limited, and may be the same as the shape of the housing recesses 161 and 261 of the first and second modifications.

  The sliding plate member 355 is attached to the housing recess 353a. The sliding plate member 355 is preferably fitted in the housing recess 353a. The sliding plate member 355 constitutes a part of the end surface 353 b of the rotating shaft 352 and faces the receiving plate 360. The shape of the sliding plate member 355 is not particularly limited, and may be a shape that follows the shape of the sliding plate member 180 of the first and second modifications. The material of the sliding plate member is preferably a hard resin.

  The receiving plate 360 has an upper surface 360 b that faces the lower end surface 353 b of the rotation shaft 352. On the upper surface 360 b of the receiving plate 360, an opposing convex portion 360 c that protrudes rounded upward toward the sliding plate member 355 is provided. The opposing convex portion 360c is disposed so as to overlap the sliding plate member 355 when viewed from the axial direction. The opposing convex portion 360 c has a rotationally symmetric shape with respect to the central axis J of the rotation shaft 352. Further, the center of the opposing convex portion 360 c is the most convex because it coincides with the central axis J of the rotation shaft 352. Thereby, when a downward force in the axial direction is applied to the rotating shaft 352, the sliding plate member 355 of the rotating shaft 352 and the receiving plate 360 are in point contact at the center. Therefore, when the rotating shaft 352 rotates in a state where the rotating shaft 352 and the sliding plate member 355 are in contact, the frictional resistance in the rotating direction is small, and the rotation loss can be suppressed.

  As shown in this modification, even if the rotating shaft has a sliding plate member, the same effects as those of the above-described embodiment and modification can be achieved.

  The embodiment of the present invention and its modifications have been described above, but each configuration and combination thereof in the embodiment is an example, and additions, omissions, and substitutions of configurations are within the scope not departing from the gist of the present invention. And other changes are possible.

  For example, the backing plate 60 of the motor 1 of the embodiment may be made of a hard resin. In this case, the same effect as that of the first modification can be obtained without using a sliding plate member. However, when the strength of the backing plate 60 made of a hard resin is insufficient with respect to the axial downward force applied to the rotating shaft 52, as shown in the first modification, the metal main body 168 slips. It is preferable to use a receiving plate 160 composed of the plate member 180.

  The motor according to the present invention is effective for a usage pattern in which an external force acts on the rotor portion, and can be applied to a usage in which an axial pushing force may be generated directly on the rotating shaft.

1, 2, 3 ... motor 10, 110 ... motor base, 12, 112 ... opening, 15, 115 ... first screw hole, 20, 120 ... bearing housing, 21 ... cylindrical portion, 22 ... annular projection, 24 ... flange portion, 25, 125 ... first through hole, 27, 127 ... second screw hole, 30 ... stator portion, 38, 138 ... first screw, 40 ... (upper side) ball bearing, 42 ... ( Lower side) Ball bearing, 44 ... Elastic member, 50 ... Rotor part, 52, 352 ... Rotating shaft, 52e ... End face, 54 ... Rotor holder, 56 ... (Rotor) magnet, 58 ... Retaining ring (retaining washer), 60, 160, 260, 360 ... receiving plate, 62 ... second screw, 63, 163 ... disc portion, 64, 164 ... projecting plate portion, 65, 165, 265 ... second through hole, 70 ... circuit board, 116 ... concave, 117 ... convex, 126 ... position Female recess, 138a ... tip, 161, 261 ... receiving recess, 168, 268 ... main body, 169 ... convex, 180, 280, 355 ... sliding plate member, 181 ... corner, 264 ... vertex, 353 ... shaft, 353a ... accommodation recess, 353b ... end surface, 360c ... opposite projection, J ... center axis, L ... gap, L1 ... gap, L2 ... distance

Claims (8)

A cylindrical bearing housing;
A ball bearing fitted to the inner peripheral surface of the bearing housing;
A stator portion fixed to the outer peripheral side of the bearing housing;
A rotating shaft rotatably supported by the ball bearing;
A rotor portion having a magnet facing the stator portion and attached to the rotating shaft;
An elastic member for applying a preload to the ball bearing;
A receiving plate attached to one open end of the bearing housing and facing the end surface of the rotating shaft;
With
The distance between the end surface of the rotating shaft and the backing plate is smaller than the distance that the ball bearing moves from the preload applied state to the fully compressed state of the elastic member. A motor base having a through hole;
The bearing housing is attached at a position facing the through hole of the motor base,
The motor according to claim 1, wherein the receiving plate is attached to the bearing housing in the through hole. Protrusions projecting radially inward are provided on the inner peripheral surface of the bearing housing,
The ball bearing is fitted to the opposite side of the protrusion from the receiving plate via the elastic member,
A lower ball bearing that supports the rotating shaft together with the ball bearing is fitted on the motor base side of the protrusion,
A part of the rotating shaft or a part of the rotor part contacts the upper surface of the inner ring of the ball bearing, and a stopper is attached to the end of the rotating shaft protruding from the lower surface side of the inner ring of the lower ball bearing. The motor according to claim 2. A flange portion projecting outward in the radial direction is provided at the receiving plate side end portion of the outer peripheral surface of the bearing housing,
The axial position of the stator portion is determined by the surface of the flange portion opposite to the motor base,
The motor according to claim 2 or 3, wherein the receiving plate is fixed to a surface of the flange portion on the motor base side. The backing plate has a main body portion and a sliding plate member,
The main body has a receiving recess,
The sliding plate member faces the end surface of the rotating shaft and is attached to the housing recess.
The motor according to any one of claims 2 to 4. The housing recess is circular when viewed from the axial direction,
The sliding plate member has a rounded rectangular shape with four rounded corners,
The corner of the sliding plate member is in press contact with the inner wall of the housing recess,
The motor according to claim 5. The motor base includes a recess disposed on a lower surface opposite to the bearing housing, a convex surface disposed on an upper surface facing the bearing housing and overlapping the recess when viewed from the axial direction, and the recess. A first screw hole that is open,
The bearing housing is provided with a first through hole and a positioning recess in which the first through hole opens on a lower surface facing the upper surface of the bearing housing, and the convex portion is accommodated in the positioning recess,
The bearing housing has a first screw fastened to the first screw hole via the first through hole and is attached to the motor base, and the tip of the first screw has the concave portion Housed inside the station,
The motor according to claim 5 or 6. The receiving plate is attached to the bearing housing by a second screw being fastened to a second screw hole provided in the bearing housing through a second through hole provided in the receiving plate. ,
The attachment of the backing plate to the bearing housing is made by the three second screws,
The attachment of the bearing housing to the motor base is made by the three first screws,
The three first screws and the three second screws are alternately arranged around the central axis of the rotating shaft,
The motor according to claim 7.