Motor

Abstract

Provided is a motor in which adhesion of metal powder to a sensor is prevented, for example.　For example, a motor (1), comprising: a rotating shaft (S); a bracket (2) formed of a non-magnetic material; a bearing (32) that rotatably supports the rotating shaft (S) on the bracket (2); a commutator (34); a magnet (7) fixed to the rotating shaft (S); a sensor (6) arranged on one surface (2a) of the bracket (2) in the rotating shaft direction; and a brush (35) arranged on another surface (2b) of the bracket (2) in the rotating shaft direction, wherein the sensor (6) detects a magnetic flux of the magnet (7).

Description

Motor

[0001] The present invention relates to a motor.

[0002] A brushed DC motor equipped with a sensor that detects the rotation of the motor is known. For example, Patent Document 1 discloses a motor in which a pulse receiver is inserted into a pocket molded in the base.

[0003] Special Publication No. 2003-501997

[0004] In a brushed DC motor, if metal powder generated by friction between the brushes and the commutator adheres to the sensor, it may cause a short circuit between terminals, for example. An example of an object of the present invention is to provide a motor in which metal powder is prevented from adhering to the sensor.

[0005] A motor that is one example of the present invention comprises a rotating shaft, a bracket made of a non-magnetic material, a bearing that rotatably supports the rotating shaft relative to the bracket, a commutator, a magnet fixed to the rotating shaft, a sensor arranged on one side of the bracket in the direction of the rotation axis, and a brush arranged on the other side of the bracket in the direction of the rotation axis, and the sensor detects the magnetic flux of the magnet.

[0006] FIG. 1 is a perspective view of a motor according to an embodiment that is an example of the present invention. FIG. 2 is a perspective view of a bracket included in the motor according to an embodiment that is an example of the present invention. FIG. 3 is another perspective view of the bracket included in the motor according to an embodiment that is an example of the present invention. FIG. 4 is an enlarged perspective view of a pocket of the bracket included in the motor according to an embodiment that is an example of the present invention. FIG. 5 is a perspective view of a sensor included in the motor according to an embodiment that is an example of the present invention. FIG. 6 is a perspective view showing an example of how a sensor is housed in a pocket of the bracket in the motor according to an embodiment that is an example of the present invention. FIG. 7 is a perspective view showing an example of how sensor wiring is connected to a board in the motor according to an embodiment that is an example of the present invention. FIG. 8 is a perspective view showing an example of how brushes are arranged on a bracket included in the motor according to an embodiment that is an example of the present invention. FIG. 9 is a cross-sectional perspective view showing an example of an arrangement of a sensor and brushes in the motor according to an embodiment that is an example of the present invention. FIG. 10 is a cross-sectional perspective view showing an example of an arrangement of a commutator and brushes in the motor according to an embodiment that is an example of the present invention. FIG. 11 is a cross-sectional perspective view showing a surface obtained by cutting the motor according to an embodiment that is an example of the present invention along a plane along the rotation axis.

[0007] In describing the embodiments of the present invention, for convenience of explanation, the direction along the rotation axis S is referred to as the rotation axis direction. In the rotation axis direction, the direction from the motor main body 3 toward the bracket 2 (the direction of arrow a) is referred to as one side, and the opposite direction (the direction of arrow b) is referred to as the other side. The direction of arrows c and d, which is perpendicular to the rotation axis S, is referred to as the radial direction. The direction of arrow c, which moves away from the rotation axis S, is referred to as the outer side or one side in the radial direction, and the direction of arrow d, which moves closer to the rotation axis S, is referred to as the inner side or other side in the radial direction. In a given member or part, the outer surface in the radial direction (the direction of arrow c) may be referred to as the outer peripheral surface, and the inner surface in the radial direction (the direction of arrow d) may be referred to as the inner peripheral surface. Furthermore, the direction of rotation around the rotation axis S may be referred to as the circumferential direction.

[0008] An embodiment of the present invention will now be described with reference to the drawings ( FIGS. 1 to 11 ). FIG. 1 is a perspective view showing the overall configuration of a motor 1 according to this embodiment. FIG. 2 is a perspective view of a bracket 2 included in the motor 1, showing one surface 2a of the bracket 2 for easy viewing. FIG. 3 is another perspective view of the bracket 2, showing the other surface 2b of the bracket 2 for easy viewing. FIG. 4 is an enlarged perspective view of the other side of a pocket 26 of the bracket 2 in the rotational axis direction for easy viewing. Note that in FIG. 4 , the sensor 6 housed inside the pocket 26 and hidden therein is indicated by a dashed line. FIG. 5 is a perspective view of the sensor 6 included in the motor 1. FIG. 6 is a perspective view showing an example of how the sensor 6 is housed in the pocket 26 of the bracket 2. FIG. 7 is a perspective view showing an example of how the wiring 62 of the sensor 6 is connected to the circuit board 5. FIG. 8 is a perspective view showing an example of how a brush 35 is arranged on the bracket 2. FIG. 9 is a cross-sectional perspective view showing an example of the arrangement of the sensor 6 and the brush 35. Fig. 10 is a cross-sectional perspective view showing an example of the arrangement of the commutator 34 and the brushes 35. Fig. 11 is a cross-sectional perspective view showing a surface obtained by cutting the motor 1 along a plane along the center line of the rotation axis S.

[0009] 1, the motor 1 includes a rotating shaft S, a bracket 2, a motor body 3, a cover 4 (shown in phantom lines), a circuit board 5, and a sensor 6. The motor body 3 includes a cylindrical case 31. The bracket 2 is disposed on one side of the motor body 3 in the direction of the rotation axis (the direction of arrow a). The bracket 2 covers one side of the case 31 of the motor body 3 in the direction of the rotation axis (the direction of arrow a).

[0010] The bracket 2 has a portion (hereinafter referred to as the lid portion 21) that covers the cylindrical case 31 of the motor main body 3, a portion (hereinafter referred to as the plate-shaped portion 22) that protrudes radially outward from the lid portion 21 (in the direction of arrow c), and a housing (hereinafter referred to as the connector housing 23) that protrudes from the plate-shaped portion 22 toward the other side in the direction of the rotation axis (in the direction of arrow b).

[0011] The substrate 5 is, for example, a flat printed circuit board (PCB) on which circuits and electronic components (neither of which are shown) are arranged. However, the substrate 5 may have any other shape. The substrate 5 is disposed on one side (in the direction of arrow a) of the plate-shaped portion 22 of the bracket 2 in the rotational axis direction. In the rotational axis direction, the cover 4 is disposed on one side (in the direction of arrow a) of the plate-shaped portion 22 of the bracket 2 and covers the substrate 5.

[0012] The sensor 6 is disposed on the plate-like portion 22 of the bracket 2 near the rotation axis S (at a corner 221 shown in FIG. 2). The sensor 6 is electrically connected to the circuit board 5. The sensor 6, together with the circuit board 5, is covered by the cover 4 from one side in the direction of the rotation axis (the direction of the arrow a).

[0013] The bracket 2 will be described in detail below with reference to Figures 2, 3, and 4. The bracket 2 is made of a non-magnetic material. The bracket 2 has one surface 2a (Figure 2) facing one side in the rotational axis direction (the direction of arrow a) and another surface 2b (Figure 3) facing the other side in the rotational axis direction (the direction of arrow b). Here, the one surface 2a refers to the surface of all the surfaces of the bracket 2 facing one side in the rotational axis direction (the direction of arrow a). The other surface 2b refers to the surface of all the surfaces of the bracket 2 facing the other side in the rotational axis direction (the direction of arrow b).

[0014] The cover portion 21 of the bracket 2 has an approximately disk-shaped portion extending radially (hereinafter referred to as the disk portion 211), a cylindrical portion extending to one side in the direction of the rotation axis (in the direction of arrow a) at the radial outer edge of the disk portion 211 (hereinafter referred to as the first outer peripheral portion 212), a portion protruding radially inward from the other surface 2b of the bracket 2 to the other side in the direction of the rotation axis (in the direction of arrow b) (hereinafter referred to as the second outer peripheral portion 213), and a first holder 24 that houses or supports the first bearing 32 described later.

[0015] The second outer peripheral portion 213 is disposed between the first outer peripheral portion 212 and the first holder 24 in the radial direction. As shown in FIG. 3 , a plurality of (ten in this embodiment) ribs 214 are formed on the outer peripheral surface 213o of the second outer peripheral portion 213 so as to protrude radially outward (in the direction of arrow c). Each of the plurality of ribs 214 has a curved surface (approximately semi-cylindrical shape) extending in the rotational axis direction. When the motor 1 is assembled, the curved surface is in line contact or surface contact with the inner peripheral surface 31i of the case 31 of the motor main body 3 (see also FIG. 10 ). Note that some or all of the plurality of ribs 214 may be shaped to have point contact or surface contact with the inner peripheral surface of the case 31 of the motor main body 3.

[0016] 2, the first holder 24 has a cylindrical portion 241 that protrudes to one side in the rotational axis direction (direction of arrow a) and surrounds the rotational axis S, and an annular portion 242 that extends radially inward (direction of arrow d) from the end of one side in the rotational axis direction of the cylindrical portion 241. The first holder 24 supports a first bearing 32 (described later) on the radially inner side (direction of arrow d) of the cylindrical portion 241 and on the other side in the rotational axis direction of the annular portion 242 (direction of arrow b).

[0017] As shown in Fig. 3, the cover portion 21 of the bracket 2 includes a wall 215 that protrudes toward the other side in the rotational axis direction (the direction of arrow b). The wall 215 includes two portions 215m and 215n that face each other across the rotational axis S and a commutator 34 (described later). Each portion has an arc-shaped cross section centered on the rotational axis S. In the radial direction, the wall 215 is disposed outside the commutator 34 (described later) and faces the commutator 34 (see also Fig. 10). In the radial direction, the wall 215 is disposed inside the second outer circumferential portion 213.

[0018] As shown in Fig. 3, two radially extending, generally rectangular cylindrical frames 216 and 217 are connected to the other side of the cover 21 of the bracket 2 in the rotational axis direction (in the direction of arrow b). The frames 216 and 217 are symmetrically arranged opposite each other, sandwiching the rotational axis S and a commutator 34 (described later) therebetween (see also Fig. 10). The radially inner ends of the frames 216 and 217 (in the direction of arrow d) each have an arc shape centered on the rotational axis S, and face the commutator 34.

[0019] In the radial direction, the frames 216 and 217 extend from the vicinity of the second outer peripheral portion 213 to the vicinity of the wall 215. Slits 216s and 217s are formed on the surfaces of the frames 216 and 217 on the other side in the rotation axis direction (the direction of arrow b), respectively, from the outer end in the radial direction toward the inside (the direction of arrow d).

[0020] The second outer periphery 213 is divided into two portions 213m and 213n by frames 216 and 217. The wall 215 is divided into two portions 215m and 215n by frames 216 and 217, and the two portions 215m and 215n are separated by a predetermined distance in the circumferential direction. The portion 213m of the second outer periphery 213 is located on the portion 215m side of the wall 215. The portion 213n of the second outer periphery 213 is located on the portion 215n side of the wall 215. The frame 216 houses or supports a first brush 351 (described later), and the frame 217 houses or supports a second brush 352 (described later).

[0021] A plate-shaped portion 22 is connected to the cover portion 21 of the bracket 2. The plate-shaped portion 22 is a generally rectangular portion that extends parallel or approximately parallel to the disk portion 211 of the cover portion 21. As shown in FIG. 2 , one corner 221 of the plate-shaped portion 22 (a portion extending in the radial direction of the first holder 24) is connected to the cover portion 21 near the first holder 24. A plurality of holes 222 (five in this embodiment) are formed in the plate-shaped portion 22. A terminal (not shown) that is connected to the board 5 and extends to the inside of the connector housing 23 is inserted into each hole 222.

[0022] As shown in FIG. 2 , a pocket 26 for accommodating the sensor 6 is provided at a corner 221 of the plate-like portion 22 of the bracket 2. The pocket 26 opens toward one surface 2a of the bracket 2. The pocket 26 has a first recess 261 and a second recess 262. Both the first recess 261 and the second recess 262 are recessed toward the other side in the rotational axis direction (the direction of arrow b). The first recess 261 is formed in a shape (in this embodiment, a hexagonal prism) corresponding to the main body 61 of the sensor 6 (described later). In the radial direction, the second recess 262 is formed continuous from the first recess 261 toward the connector housing 23 (the direction of arrow c). Both a cross section of the second recess 262 along the rotational axis S (a plane passing through the center line of the rotational axis S and extending in the rotational axis direction and radial direction) and a cross section along a plane perpendicular to the rotational axis direction are substantially rectangular. In the rotation axis direction, the dimension (depth of the recess) of the second recess 262 is smaller than the dimension (depth of the recess) of the first recess 261 .

[0023] Three grooves 263, 264, and 265 extending radially and in the rotational axis direction are formed in the pocket 26 in parallel or approximately parallel alignment in the circumferential direction, straddling the first recess 261 and the second recess 262. Of the three grooves 263, 264, and 265, two of the grooves 263 and 265 have the same or approximately the same dimensions. The groove 264, sandwiched between the two grooves 263 and 265, extends radially further toward the connector housing 23 (in the direction of arrow c) than the grooves 263 and 265.

[0024] As shown in FIG. 4 , the pocket 26 protrudes toward the other side in the rotational axis direction of the bracket 2 (in the direction of arrow b) or toward the inside of the motor main body 3. The pocket 26 is connected to a portion 215n of the wall 215 of the bracket 2. The pocket 26 includes an inner circumferential portion 266 that faces a magnet 7 (described later) in the radial direction, a side portion 267, and a bottom portion 268. The inner circumferential portion 266 is the portion of the pocket 26 that is radially inward (in the direction of arrow d). The inner circumferential portion 266 is on the magnet 7 side (described later) with respect to the wall 215 of the bracket 2. In other words, the pocket 26 protrudes radially inward (in the direction of arrow d) beyond the portion 215n of the wall 215 of the bracket 2.

[0025] The bottom portion 268 is the end portion of the pocket 26 on the other side in the rotational axis direction (in the direction of arrow b). The side portion 267 is a portion that extends from the edge of the bottom portion 268 toward one side in the rotational axis direction (in the direction of arrow a) and reaches the disk portion 211. When the sensor 6 is housed in the pocket 26, the sensor 6 is surrounded by the inner periphery 266, the side portion 267, and the bottom portion 268 of the pocket 26 (in FIG. 4 , the sensor 6 housed in the pocket 26 is shown by a dashed line). In this embodiment, the sensor 6 is completely covered by the pocket 26 on the other side in the rotational axis direction of the bracket 2 (in the direction of arrow b).

[0026] 2 and 3 , the connector housing 23 is a generally rectangular cylindrical portion whose end on one side in the rotational axis direction (in the direction of arrow a) is covered by the plate-like portion 22. In the axial direction, the connector housing 23 is disposed on the other side (in the direction of arrow b) of the plate-like portion 22 of the bracket 2, and is disposed on the opposite side in the radial direction from the first holder 24. By inserting a connector (not shown) into the connector housing 23, the board 5 is electrically connected to an external device (not shown).

[0027] The sensor 6 will be described in detail below with reference to FIGS. 5, 6, and 7. The sensor 6 is a sensor capable of detecting magnetic flux, and may be, for example, a Hall element, a Hall IC, or a magnetoresistive element. The sensor 6 detects magnetic flux from a magnet 7, which will be described later. Note that, in this specification, "detecting magnetic flux" may also mean detecting changes in magnetic flux. As shown in FIG. 5, the sensor 6 includes a main body 61 and wiring (terminals) 62. The main body 61 of the sensor 6 is formed in a hexagonal or approximately hexagonal prism shape. The main body 61 of the sensor 6 includes two parallel hexagonal or approximately hexagonal bottom surfaces (a first bottom surface 611 and a second bottom surface 612) and six side surfaces perpendicular to the first bottom surface 611 and the second bottom surface 612 (a first surface 613, a second surface 614, a third surface 615, a fourth surface 616, a fifth surface 617, and a sixth surface 618, in a clockwise direction when viewed from the first bottom surface 611). However, the body 61 of the sensor 6 may have other shapes.

[0028] The first surface 613 is the side surface with the largest area and extends parallel or approximately parallel to the fourth surface 616, which is the second largest surface. The second surface 614 and the sixth surface 618 adjacent to the first surface 613 are the side surfaces with the smallest areas, have the same or approximately the same dimensions and shapes, and extend parallel or approximately parallel to each other. The third surface 615 connects the second surface 614 and the fourth surface 616, and the fifth surface 617 connects the fourth surface 616 and the sixth surface 618.

[0029] The wiring 62 includes a first wiring 621, a second wiring 622, and a third wiring 623. The first wiring 621, the second wiring 622, and the third wiring 623 are arranged side by side in a direction from the second surface 614 toward the sixth surface 618. The first wiring 621, the second wiring 622, and the third wiring 623 all extend perpendicularly from the second bottom surface 612 of the main body 61 of the sensor 6, then bend and extend in a direction toward the first surface 613, and then bend again and extend in a direction from the second bottom surface 612 toward the first bottom surface 611. The first wiring 621 and the third wiring 623 have the same shape and dimensions. The second wiring 622, which is sandwiched between the first wiring 621 and the third wiring 623, has a dimension extending in a direction toward the first surface 613 that is longer than the other two wirings.

[0030] The sensor 6 is inserted into the pocket 26 of the bracket 2 in a direction from one side to the other in the rotational axis direction (the direction of arrow b). In this way, the sensor 6 is disposed on one surface 2a of the bracket 2. As shown in FIG. 6 , when the sensor 6 is accommodated in the pocket 26 of the bracket 2, the main body 61 of the sensor 6 is accommodated in the first recess 261 of the pocket 26, and the first wiring 621, the second wiring 622, and the third wiring 623 are accommodated in the grooves 263, 264, and 265, respectively. That is, the first recess 261 of the pocket 26 is a portion that accommodates the main body 61 of the sensor 6, and the grooves 263, 264, and 265 of the pocket 26 are portions that accommodate the wiring 62 of the sensor 6. When the sensor 6 is accommodated in the pocket 26 of the bracket 2, the fourth surface 616 of the main body 61 of the sensor 6 faces inward in the radial direction (the direction of arrow d), and the first surface 613 faces outward in the radial direction (the direction of arrow c). A first bottom surface 611 of the main body 61 of the sensor 6 is exposed to one side in the rotation axis direction (the direction of arrow a). A first wiring 621, a second wiring 622, and a third wiring 623 extend and protrude from the groove 263, the groove 264, and the groove 265, respectively, to one side in the rotation axis direction (the direction of arrow a).

[0031] As shown in FIG. 7 , when the substrate 5 is placed on one side of the bracket 2 in the rotational axis direction (in the direction of arrow a), the first wiring 621, the second wiring 622, and the third wiring 623 of the sensor 6 are inserted through holes 51, 52, and 53, which are through holes formed in the substrate 5. Therefore, the wiring 62 of the sensor 6 extends in a direction from the other surface 2 b toward the one surface 2 a of the bracket 2 (in a direction toward one side in the rotational axis direction) and is electrically connected to the substrate 5. Even after the substrate 5 is placed, the bottom surface 611 of the body 61 of the sensor 6 remains exposed on one side in the rotational axis direction (in the direction of arrow a). In this embodiment, the bottom surface 611 of the body 61 of the sensor 6 is slightly closer to the one side in the rotational axis direction (in the direction of arrow a) than the substrate 5. After the substrate 5 is placed, the substrate 5 and the sensor 6 are covered by the cover 4 (see FIG. 1 ).

[0032] The arrangement of the sensor 6 and the brush 35 will be described in detail below with reference to Figures 8, 9, and 10. As shown in Figure 8, the first brush 351 and the second brush 352 that make up the brush 35 are housed in the frames 216 and 217, respectively. In this manner, the brush 35 is arranged on the other surface 2b of the bracket 2. The first brush 351 and the second brush 352 are both formed in a substantially quadrangular prism shape.

[0033] Wiring 351w and wiring 352w are respectively connected to first brush 351 and second brush 352. Wiring 351w extends to the outside of frame 216 through slit 216s, and wiring 352w extends to the outside of frame 217 through slit 217s.

[0034] The first brush 351 is biased radially inward (in the direction of arrow d) by an elastic member 351s. In this embodiment, the elastic member 351s is a spirally wound spring (elastic body) disposed on a pillar 271 provided on the bracket 2. The pillar 271 is a portion that protrudes to the other side in the rotation axis direction (in the direction of arrow b), and is provided between the frame 216 and the pocket 26 in the circumferential direction.

[0035] The second brush 352 is biased radially inward (in the direction of arrow d) by an elastic member 352s. In this embodiment, the elastic member 352s is a spirally wound spring (elastic body) disposed on a pillar 272 provided on the bracket 2. The pillar 272 is a portion that protrudes to the other side in the direction of the rotation axis (in the direction of arrow b), and is disposed symmetrically or approximately symmetrically to the pillar 271 with respect to the rotation axis S.

[0036] 9 is a perspective cross-sectional view showing a cross section obtained by cutting the motor 1 parallel to the rotation axis S so as to pass through the sensor 6 and the first brush 351. As shown in FIG. 9, the sensor 6 and the substrate 5 are disposed on one surface 2a of the bracket 2, and the brushes 35 (the first brush 351 and the second brush 352) are disposed on the other surface 2b of the bracket 2. On the other surface 2b of the bracket 2, the sensor 6 is covered by the pocket 26 (completely covered in this embodiment).

[0037] 10 is a perspective cross-sectional view showing a cross section obtained by cutting the motor 1 perpendicular to the rotation axis S so as to pass through the first brush 351 and the second brush 352. As shown in FIG. 10 , the brushes 35 (the first brush 351 and the second brush 352) contact the commutator 34 from the radial outside. On the other surface 2b of the bracket 2, the inner periphery 266, side 267, and bottom 268 of the pocket 26 block the path from the contact point between the brush 35 and the commutator 34 to the sensor 6. Note that FIG. 10 also shows how the multiple ribs 214 on the second outer periphery 213 of the bracket 2 contact the inner periphery 31i of the case 31 of the motor main body 3.

[0038] The overall configuration of the motor 1 will be described in detail below with reference to Fig. 11. The motor 1 includes a motor body 3. The motor body 3 includes a case 31, a first bearing 32, a second bearing 33, a commutator 34, brushes 35, a rotor 36, and a stator 37.

[0039] The case 31 is a cylindrical member (e.g., cylindrical, rectangular, quadrilateral, or other polygonal shape, or polygonal shape with multiple curved corners) and is made of a magnetic material such as iron. The case 31 houses the rotor 36. A stator 37, which is a cylindrical permanent magnet, is fixed to an inner peripheral surface 31i of the case 31 in the radial direction. The other end of the case 31 in the rotational axis direction (in the direction of arrow b) is covered by a bottom 311. A second holder 312 protruding toward the other end in the rotational axis direction (in the direction of arrow b) is provided in a central portion of the bottom 311. The second holder 312 protrudes toward the other end in the rotational axis direction (in the direction of arrow b) and includes a cylindrical portion 312a that surrounds the rotation axis S, and an annular portion 312b that extends radially inward (in the direction of arrow d) from the other end of the cylindrical portion 312a in the rotational axis direction. The second holder 312 supports a second bearing 33 (described later) on the radially inner side (arrow d direction) of the cylindrical portion 312a and on one side (arrow a direction) of the annular portion 312b in the rotation axis direction.

[0040] In this embodiment, the stator 37 is a permanent magnet having multiple (e.g., four) magnetic poles. The stator 37 may be configured with multiple permanent magnets and have multiple magnetic poles, or may be configured with a single permanent magnet and have multiple magnetic poles. The stator 37 is magnetized with two different magnetic poles (N poles and S poles) alternately arranged in the circumferential direction.

[0041] The rotor 36 includes a core 361 having a plurality of magnetic pole portions and a coil 362 wound around the core 361. The rotor 36 faces the stator 37 in the radial direction. The core 361 of the rotor 36 is fixed to the rotation shaft S and rotates integrally with the rotation shaft S.

[0042] A substantially cylindrical commutator 34 is disposed on one side of the rotor 36 in the direction of the rotation shaft (the direction of arrow a). The commutator 34 is fixed to the rotation shaft S and rotates integrally with the rotation shaft S. The commutator 34 has a plurality of segments 34c (see FIG. 10) arranged in the circumferential direction, which come into contact with the brushes 35 to conduct electricity.

[0043] A substantially disk-shaped magnet 7 is disposed on one side of the commutator 34 in the direction of the rotation axis (the direction of arrow a). The magnet 7 is fixed to the rotation axis S and rotates integrally with the rotation axis S. The magnet 7 is a permanent magnet having multiple magnetic poles. The magnet 7 may be composed of multiple permanent magnets and have multiple magnetic poles, or may be composed of a single permanent magnet and have multiple magnetic poles. The magnet 7 is magnetized with two different magnetic poles (north and south poles) alternately arranged in the circumferential direction.

[0044] The arrangement of the magnet 7 in the rotational axis direction overlaps with the arrangement of the disk portion 211 of the bracket 2 in the rotational axis direction. In the radial direction, the magnet 7 faces the inner circumferential surface 211i of the disk portion 211 of the bracket 2. In addition, the arrangement of the magnet 7 in the rotational axis direction overlaps with the arrangement of the sensor 6 (specifically, the main body 61 of the sensor 6) in the rotational axis direction. In other words, in the radial direction, the magnet 7 faces the sensor 6 (specifically, the main body 61 of the sensor 6) across the bracket 2. This allows the sensor 6 to detect the magnetic flux of the magnet 7 or a change in magnetic flux.

[0045] A first bearing 32 is disposed on one side of the magnet 7 in the direction of the rotation axis (the direction of the arrow a). In this embodiment, the first bearing 32 is a ball bearing having an inner ring 321, an outer ring 322, and rolling elements. Note that the first bearing 32 is not limited to a ball bearing, and may be various other bearings, such as a sleeve bearing.

[0046] In the radial direction, the first bearing 32 is disposed inside (in the direction of arrow d) the cylindrical portion 241 of the first holder 24 of the bracket 2. The inner ring 321 of the first bearing 32 is bonded or press-fitted to the outer peripheral surface of the rotation shaft S. This fixes the inner ring 321 of the first bearing 32 to the rotation shaft S. The outer ring 322 of the first bearing 32 is bonded or press-fitted to the cylindrical portion 241 of the first holder 24 of the bracket 2. In this way, the first bearing 32 supports the rotation shaft S rotatably with respect to the bracket 2.

[0047] A second bearing 33 is disposed on the other side of the rotor 36 in the direction of the rotation axis (the direction of arrow b). In this embodiment, the second bearing 33 is a ball bearing having an inner ring 331, an outer ring 332, and rolling elements. Note that the second bearing 33 is not limited to a ball bearing, and may be various other bearings, such as a sleeve bearing.

[0048] In the radial direction, the second bearing 33 is disposed inside (in the direction of arrow d) the cylindrical portion 312a of the second holder 312 of the case 31. The inner ring 331 of the second bearing 33 is bonded or press-fitted to the outer peripheral surface of the rotating shaft S. This fixes the inner ring 331 of the second bearing 33 to the rotating shaft S. The outer ring 332 of the second bearing 33 is bonded or press-fitted to the cylindrical portion 312a of the second holder 312 of the case 31. In this way, the second bearing 33 supports the rotating shaft S rotatably with respect to the case 31.

[0049] The motor 1 according to this embodiment is a brushed DC motor having the above-described configuration. When current flows from wires 351w and 352w connected to a power source or the like through the brushes 35, commutator 34, and coil 362 in that order, the rotor 36 and rotating shaft S begin to rotate. As the commutator 34 rotates together with the rotating shaft S, the segment 34c with which the brush 35 comes into contact changes, and the rotor 36 continues to rotate. The sensor 6 detects the magnetic flux from the magnet 7 rotating together with the rotating shaft S, and a signal output from the sensor 6 is input to the circuit board 5.

[0050] In the motor 1, the sensor 6 and the circuit board 5 are disposed on one surface 2a of the bracket 2, and the brushes 35 (first brush 351 and second brush 352) are disposed on the other surface 2b of the bracket 2. On the other surface 2b of the bracket 2, the sensor 6 is covered by the inner periphery 266, side 267, and bottom 268 of the pocket 26. In this way, the path from the contact point between the brush 35 and the commutator 34 to the sensor 6 is blocked by the bracket 2, preventing metal powder generated by friction or the like at the contact point between the brush 35 and the commutator 34 from adhering to the sensor 6 and the circuit board 5. In the motor 1, the sensor 6 and the circuit board 5 are also covered by the cover 4. This also prevents other dust particles from adhering to the sensor 6.

[0051] In the motor 1, the second outer peripheral portion 213 of the bracket 2 contacts the inner peripheral surface 31i of the case 31 of the motor main body 3 via a plurality of ribs 214. This makes it difficult for vibrations of the motor main body 3 to propagate to the sensor 6, improving the accuracy of the sensor 6.

[0052] In the motor 1, the circuit board 5 is disposed on one surface 2a of the bracket 2. This allows the overall configuration including the motor body 3 and the circuit board 5 to be made compact.

[0053] In the motor 1, the sensor 6 can be attached after the bracket 2 is attached to the motor body 3. Therefore, the sensor 6 can be attached easily.

[0054] In the motor 1, the inner periphery 266 of the pocket 26 is on the magnet 7 side of the wall 215 of the bracket 2. In other words, the pocket 26 protrudes radially inward (in the direction of arrow d) beyond the portion 215n of the wall 215 of the bracket 2. This allows the sensor 6 to be positioned closer to the magnet 7, improving the accuracy of the sensor 6.

[0055] Although the motor of the present invention has been described above with reference to a preferred embodiment, the motor of the present invention is not limited to the configuration of the above embodiment. Below, examples of other configurations that can be adopted by the motor of the present invention will be described.

[0056] In the motor of the present invention, the sensor may be indirectly supported on one surface of the bracket via another member. Also, in the motor of the present invention, the brush may be indirectly supported on the other surface of the bracket via another member. The sensor provided in the motor of the present invention may have two wires or four or more wires. In the motor of the present invention, the outer periphery of the bracket may be in surface contact with the inner periphery of the case of the motor body. In the motor of the present invention, the circuit board may be disposed away from the bracket. In the motor of the present invention, the wall of the bracket may be closer to the magnet than the inner periphery of the pocket.

[0057] In addition, those skilled in the art can appropriately modify the motor of the present invention and change the shape, dimensions, and combination of various components in accordance with conventional knowledge. As long as the motor still has the components of the present invention even after such modifications, it naturally falls within the scope of the present invention.

[0058] 1...motor, 2...bracket, 2a...one side, 2b...other side, 215...wall, 26...pocket, 266...inner circumference, 267...side, 268...bottom, 32...bearing, 34...commutator, 35...brush, 5...circuit board, 6...sensor, 61...main body, 62...wiring, 7...magnet, S...rotating shaft

Claims

1. A motor comprising: a rotating shaft; a bracket made of a non-magnetic material; a bearing that rotatably supports the rotating shaft relative to the bracket; a commutator; a magnet fixed to the rotating shaft; a sensor arranged on one surface of the bracket in the direction of the rotating shaft; and a brush arranged on the other surface of the bracket in the direction of the rotating shaft, wherein the sensor detects the magnetic flux of the magnet.

2. The motor of claim 1, further comprising a substrate disposed on said one surface of said bracket, said sensor being electrically connected to said substrate.

3. A motor as described in claim 1 or 2, wherein the bracket is provided with a pocket for accommodating the sensor, the pocket is open on the side of the one surface of the bracket, the pocket has an inner circumferential portion facing the magnet in the radial direction, a side portion, and a bottom portion, and the sensor is surrounded by the inner circumferential portion, the side portion, and the bottom portion of the pocket.

4. The motor according to claim 3, wherein the sensor comprises a body and wiring, and the pocket comprises a portion that accommodates the body of the sensor and a portion that accommodates the wiring of the sensor.

5. The motor according to claim 4, wherein the wiring of the sensor extends in a direction from the other surface of the bracket toward the one surface and is electrically connected to a circuit board.

6. A motor according to any one of claims 3 to 5, wherein the bracket has a wall that faces the commutator in the radial direction, and the inner periphery of the pocket is on the magnet side of the wall.

Images