JP2009261149A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless motor having a hollow-shaped shaft, which can properly seal a clearance generated between an encoder cover and a motor body with a simple means. <P>SOLUTION: The brushless motor is equipped with the hollow-shaped shaft 4 rotatably supported with brackets 9, 10 and the shaft 4 has a projection part 4a projecting outside from the through-hole 9a of one bracket 9. An encoder ring 14a is fitted to the projection part 4a and an optical sensor 15 is fitted to the bracket 9. The bottomed cylindrical encoder cover 17 is fitted to the bracket 9 in a manner to cover the encoder 13. Furthermore, the encoder cover 17 is provided with a hole opening 17c opposed to the through-hole 9a. In this case, the brushless motor is further equipped with a sealing member 19 incontact with and arranged between the encoder cover 17 and the projection part 4a for sealing the clearance 22 formed between the encoder cover 17 and the projection part 4a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a brushless motor, and more particularly to a brushless motor that prevents foreign matter from entering a rotation detection unit from the outside of the motor.

  The brushless motor includes a rotor that is rotatably arranged inside the stator. The stator includes a ring-shaped stator body and a plurality of salient poles integrally projecting from the inner peripheral surface of the stator body. The rotor has a cylindrical shaft and a ring magnet attached to the outer peripheral surface of the shaft. In general, the shaft has a solid cylindrical shape, but there is a brushless motor in which the shaft has a hollow cylindrical shape, a space portion is provided inside the shaft, and the space portion is effectively used. For example, in the brushless motor of Patent Document 1, a lens that is a driven body is arranged in a space portion inside a shaft to reduce the size of the motor system.

  As described above, the brushless motor having the hollow cylindrical shaft needs to detect the rotational position of the rotor and supply a control signal corresponding to the rotational position to the stator in the same manner as a normal brushless motor. Therefore, it is necessary to attach rotation detection means for detecting the rotation position of the rotor to the shaft. For example, in the brushless motor of Patent Document 2, a resolver having a resolver rotor and a resolver stator as rotation detection means is attached to a shaft inside the motor.

Japanese Patent Laid-Open No. 6-22519 JP 2001-191931 A

  However, in such a brushless motor having a hollow cylindrical shaft, for example, when used as a drive source for an arm of an industrial robot, it is necessary to detect the rotational position of the rotor with higher accuracy. In such a case, an optical encoder using an optical sensor is used as a highly accurate rotation detection means.

  The optical encoder has an optical sensor and an encoder ring attached to the shaft. The waveform signal of the irradiation light emitted from the optical sensor to the encoder ring, and the irradiation light is reflected by the reflective disk and received by the optical sensor. The rotational position of the rotor is detected with high accuracy using the waveform signal of the reflected light. In this optical encoder, in order to increase the S / N ratio of the waveform signal, the positions of the optical sensor and the encoder ring need to be finely adjusted after the motor is assembled.

  However, when the motor is assembled after the rotation detecting means is previously attached to the interior of the motor as in Patent Document 2, fine adjustment after the motor is not assembled. Therefore, after the motor is assembled, it is necessary to have a structure in which an encoder ring is attached to the shaft from the outside of the motor and an optical sensor is attached to the motor body from the outside of the motor.

  At this time, in the optical encoder, if dust or the like from the outside adheres to the encoder ring, the waveform signal of the reflected light is distorted and the rotational position cannot be detected with high accuracy. In order to prevent dust from the outside from adhering to the encoder ring of the optical encoder, an encoder cover that covers the optical encoder from the outside of the motor is attached to the motor body from the outside, and the encoder is sealed between the encoder cover and the motor body. Conceivable. However, in an industrial robot in which a brushless motor is used as its drive source, for example, wiring such as a signal line of an industrial robot is introduced from one end of a hollow cylindrical shaft and discharged from the other end. In some cases, the inside of the motor is allowed to pass. In such a case, it is necessary to provide an opening in the encoder cover and allow the wiring to pass therethrough.

  Since the opening is provided in this way, a gap is generated between the encoder cover and the motor body, and the optical encoder cannot be sealed from the outside. For this reason, dust or the like may enter the encoder cover from the gap, and dust or the like may adhere to the encoder ring. Therefore, it is required to appropriately close a gap between the encoder cover and the motor main body, which is generated by providing the opening, with simple means.

  Accordingly, an object of the present invention is to provide a brushless motor with an encoder having a hollow shaft that can appropriately close a gap generated between the encoder cover and the motor body by simple means and prevent foreign matters such as dust from adhering to the encoder. Is to provide.

  In order to solve the above-described problems, a brushless motor according to the present invention includes a stator case formed in a substantially cylindrical shape, a substantially disk shape formed with a through hole in a central portion, and the opening of the stator case is closed. A pair of brackets, a stator body formed in a substantially annular shape and attached to the inner wall of the stator case, and a plurality of salient poles protruding radially inward from the inner peripheral surface of the stator body. A stator, a coil wound around each of the salient poles of the stator, and a shaft that is formed in a hollow cylindrical shape and is rotatably supported by the pair of brackets through the through holes of the pair of brackets. A brushless motor comprising: a magnet supported by the shaft; and a rotor disposed opposite to the salient poles of the stator. The shaft of the lashless motor includes a protruding portion that protrudes to the outside from the through hole of one bracket of the bracket, and the brushless motor includes a substantially disc-shaped slit plate on the outer peripheral surface of the protruding portion of the shaft. An encoder having an attached encoder ring, a sensor element, the sensor element facing the slit plate of the encoder ring, and an optical sensor attached to the one bracket; and a substantially bottomed cylindrical shape An opening that is opposed to the through hole of the bracket is formed at the substantially center of the bottom, covers the encoder, and is attached to the one bracket; the encoder cover; and a protruding portion of the shaft; In contact with the encoder cover and the protruding portion of the shaft, the protruding portion of the shaft And a sealing member covering a gap portion formed between the encoder cover with.

  As described above, the sealing member is disposed in the gap formed between the encoder and the shaft, and the gap is covered with the sealing member, so that the gap generated between the encoder cover and the motor body can be appropriately closed with simple means. It is possible to prevent foreign matters such as dust from adhering to the encoder.

  Next, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of the brushless motor according to the first embodiment. FIG. 2 is a longitudinal sectional view of the brushless motor of the first embodiment indicated by the A plane in FIG. FIG. 3 is a cross-sectional view of the brushless motor of the first embodiment indicated by the B plane in FIG.

  The brushless motor 1 includes a motor case 7, a stator 2 attached to the inside of the motor case 7, and a rotor 3 that is rotatably arranged inside the stator 2. The motor case has a substantially cylindrical stator case 8 and a rear bracket (bracket) 9 which is formed in a substantially disk shape and has a through hole 9a formed in the center, and is closed at one end of the stator case 8. And a front bracket (bracket) 10 that is formed in a substantially disk shape, has a through hole 10a at the center, and is disposed with the opening closed at the other end of the stator case. Note that the stator case 8, the rear bracket 9, and the front bracket 10 are formed of an aluminum alloy in order to reduce the weight and efficiently dissipate heat generated in the stator 2.

  The stator 2 is formed by laminating thin magnetic steel plates, and has a substantially annular stator body 2a and 15 salient poles integrally projecting radially inward from the inner peripheral surface of the stator body 2a. ing. The stator 2 is press-fitted into the stator case 8 and attached to the inner wall of the stator case 8 by the stator body 2a.

  The rotor 3 includes a hollow cylindrical shaft 4 made of a magnetic material, and a ring magnet (magnet) 5 attached and fixed to the outer peripheral surface of the shaft 4 with an adhesive. The ring magnet 5 is formed of, for example, a rare earth element such as neodymium (Nd—Fe—B), and is magnetized alternately in the circumferential direction in the order of N pole, S pole,. Is the pole.

  A concave portion 9 b is provided in the central portion of the rear bracket 9, an outer race of the bearing 11 is inserted into the concave portion 9 b, and the bearing 11 is attached to the rear bracket 9. On the other hand, a recess 10 b is provided at the center of the front bracket 10, and an outer race of the bearing 12 is inserted into the recess 10 b, and the bearing 12 is attached to the front bracket 10.

  The reduced diameter portion 4 d on the rear bracket 9 side of the shaft 4 is inserted into the inner race of the bearing 11, and the reduced diameter portion 4 e on the front bracket 10 side is inserted into the inner race of the bearing 12. As described above, the shaft 4 of the rotor 3 is supported by the bearings 11 and 12 attached to the rear and front brackets 9 and 10, and the rotor 3 is rotatably arranged inside the salient pole 2 b of the stator 2.

  The shaft 4 includes a cylindrical first projecting portion (projecting portion) 4 a integrally projecting from one end of the shaft 4 to the outside of the motor case 7 from the through hole 9 a of the rear bracket 9, and from the through hole 10 a of the front bracket 10. A cylindrical second protrusion (protrusion) 4 b that integrally protrudes from the other end of the shaft 4 is provided outside the motor case 7. A planetary reduction gear (not shown) is attached to the second protrusion 4b, and the rotation of the shaft 4 is reduced by the reduction gear and output to the outside.

  A resin insulator 20 is attached to each of the 15 salient poles 2b of the stator 2 to ensure insulation. And the conducting wire is wound around the outer peripheral surface of the insulator 20 by concentrated winding, and the coil 6 is formed on each of the salient poles 2b. The conducting wire at the beginning and end of winding of each coil 6 is entangled with a pin 20 a integrally formed at one end of the insulator 20, and the pin 20 a is electrically and mechanically connected to the power distribution board 21. .

  A power distribution pattern is formed on the power distribution board 21. The power distribution pattern in which the circumferentially arranged coils 6 become a U-phase coil 6a, a V-phase coil 6b, a W-phase coil 6c,. It has become. A lead wire 18 is connected to the power distribution board 21, and a control signal corresponding to the rotational position of the rotor 3 is supplied to an external driver (not shown) to the U-phase coil 6a, V-phase coil 6b, and W-phase coil 6c. Supplied from

  As described above, since the control signal corresponding to the rotational position of the rotor 3 is supplied to the U-phase coil 6a, the V-phase coil 6b, and the W-phase coil 6c, it is necessary to accurately detect the rotational position of the rotor 3. Here, the brushless motor 1 according to the present embodiment is used as an actuator for driving an arm of an industrial robot or the like that is required to drive with high accuracy in positioning, and detects the rotational position of the rotor 3 with high accuracy. There is a need. Therefore, the brushless motor 1 of the present embodiment uses the optical encoder 13 as the rotational position detection means.

  The optical encoder 13 includes an encoder disk 14 and an optical sensor 15. The encoder ring 14 includes a ring-shaped encoder ring main body 14a and a disk-shaped slit plate 14b attached to an end surface of the encoder ring main body 14a. A male screw is formed on the outer peripheral surface of the first protrusion 4a, while a female screw is formed on the inner peripheral surface of the encoder ring body 14a, and the reflective disk main body 14a is a screw on the outer peripheral surface of the first protrusion 4a. Installed by fitting. Note that 1024 slits are formed in the slit plate 14b.

  The optical sensor 15 includes a sensor element 15a attached to the sensor substrate 15b and a sensor wiring 15c that outputs a signal from the sensor substrate 15b to the outside. The optical sensor 15 is fixed to the rear bracket 9, and at this time, the sensor element 15 a is arranged at a position away from the slit plate 14 b of the encoder disk 14 and facing the slit plate 14 b. The sensor element 15a includes a light emitting unit (not shown) that emits irradiation light to the slit plate 14b and a light receiving unit (not shown) that receives reflected light from the slit plate 14b. The rotational position signal of the rotor 3 is detected from the waveform signals of the light and the reflected light.

  An encoder cover 17 is used to protect the optical encoder 13 from external dust and the like. The encoder cover 17 has a substantially cylindrical cylindrical portion 17a and a bottom portion 17b integrally formed at one end of the cylindrical portion 17a, and is formed in a substantially bottomed cylindrical shape. The other end of the cylindrical portion 17 a is attached to the rear bracket 9, and the encoder cover 17 is fixed to the brushless motor 1.

  Here, as described above, the brushless motor 1 of the present embodiment is used as an actuator for driving an arm of an industrial robot or the like, for example, various sensors provided in the industrial robot. The wiring 30 such as the like passes through the inside of the shaft 4. Therefore, an opening 17c having an inner diameter similar to the inner diameter of the shaft 4 is provided in the bottom portion 17b at a position facing the through hole 9a of the rear bracket 9 through which the shaft 4 is inserted.

  By providing the opening 17c in the encoder cover 17 as described above, the wiring 30 can be inserted through the passage from the opening 17c to the inside of the shaft 4. Thus, by attaching the encoder cover 17 to the brushless motor 1, the optical encoder 13 can be substantially covered. However, since the opening 17c is provided in the encoder cover 17, a gap 22 is generated between the end 4c of the first protrusion 4b of the shaft 4 and the wall 17d that forms the opening 17c.

  For this reason, dust or the like may enter the encoder cover 17 from the gap 22 and the dust or the like may adhere to the slit plate 14b or the like. If dust or the like adheres to the slit plate 14b, the waveform signal of the reflected light detected by the sensor element 15b is distorted, and the rotational position cannot be detected with high accuracy. Therefore, a means for covering the gap 22 is required.

  In this embodiment, an O-ring (sealing member) made of elastic silicon rubber is provided in the gap 22 between the end 4c of the first protrusion 4b of the shaft 4 and the wall 17d forming the opening 17c. 22 is arranged. The inner diameter of the O-ring 22 is set slightly smaller than the outer diameter of the first projecting portion 4a, and is attached to the outer peripheral surface of the first projecting portion 4a by an elastic force that tends to shrink in the circumferential direction. Yes. On the other hand, the outer diameter of the O-ring 22 after being attached to the first projecting portion 4a projects slightly from the bottom portion 17b toward the optical encoder 13 and is slightly larger than the inner diameter of the projecting portion 17e that forms the wall portion 17d. Is set to

  On the other hand, the outer diameter of the O-ring 22 after being attached to the first projecting portion 4a projects slightly from the bottom portion 17b toward the optical encoder 13 and is slightly larger than the inner diameter of the projecting portion 17e that forms the wall portion 17d. Is set to As described above, the inner periphery of the O-ring 22 is in contact with the outer periphery of the first protrusion 4a, and the outer periphery of the O-ring 22 is in contact with the inner periphery of the projecting portion 17e. A gap 22 formed between 4 a and the encoder cover 17 is covered with an O-ring 22.

  Thus, the O-ring 22 is in contact with the protruding portion 17e of the encoder cover 17 and the first protruding portion 4a of the shaft 4, and the protruding portion 17e of the encoder cover 17 and the first protruding portion 4a of the shaft 4 are contacted. Is disposed in the gap portion 22 formed between and the O-ring 22, so that the gap portion 22 is formed between the projecting portion 17 e of the encoder cover 17 and the first projecting portion 4 a of the shaft 4. Can be covered.

  In this way, it is appropriate that dust or the like enters the encoder cover 17 from the gap portion 22 by a simple means of attaching the O-ring (sealing member) 22 and adheres to the slit plate 14b or the like. Can be prevented. Thereby, adhesion of dust etc. to the slit plate 14b can be prevented, and highly accurate rotation position detection can be secured. In addition, it cannot be overemphasized that the shape and attachment means of the sealing member 22 are not restricted to what is shown to said 1st Embodiment, For example, the sealing member 22 shown to the 2nd-6th embodiment shown below, for example There are also shapes and attachment means.

  FIG. 4 shows the shape and attachment means of the sealing member 22 of the second embodiment of the present invention, and is an enlarged view of the second embodiment corresponding to the portion indicated by C in FIG. . In the second to sixth embodiments described below, the shape of the sealing member 22 and the structure of the other brushless motors other than the attachment means are the same, and the shape and attachment means of the sealing member 22 will be described. The description of the structure is omitted.

  As shown in FIG. 4, in the second embodiment, a protruding portion 17e protruding toward the optical encoder 13 in the vicinity of the outside of the opening 17c of the encoder cover 17 is formed integrally with the disc portion 17b. Yes. The projecting portion 17e has a circular shape centered on the shaft center of the shaft 4 and the wall portion 17d is formed by the projecting portion 17e and the end portion 17f that forms the opening 17c. It is formed.

  If the gap portion 22 is formed between the wall portion 17d and the end portion 4c of the shaft 4, and there is no sealing means, dust or the like may enter the encoder cover 17 from the gap portion 22. In the present embodiment, a rubber O-ring (sealing member) 19 is used as the sealing means, and the O-ring (sealing member) 22 is disposed in the gap portion 22.

  The outer periphery and one side surface of the O-ring (sealing member) 22 are in contact with the inner periphery of the projecting portion 17e and the disc portion 17b, and are fixed to the inner periphery of the projecting portion 17e and the disc portion 17b by an adhesive. ing. On the other hand, the other side surface of the O-ring (sealing member) 22 is in contact with the end surface of the end portion 4 c of the shaft 4. In this way, the outer periphery and one side surface of the O-ring 22 are fixed to the inner periphery of the projecting portion 17e and the disc portion 17b, and one side surface of the O-ring 22 is in contact with the end surface of the end portion 4c of the shaft 4. As a result, the gap 22 formed between the first protrusion 4 a of the shaft 4 and the encoder cover 17 is covered with the O-ring 22.

  FIG. 5 shows the shape and attachment means of the sealing member 22 of the third embodiment of the present invention, and is an enlarged view of the third embodiment corresponding to the portion indicated by C in FIG. . As shown in FIG. 5, in the third embodiment, the protruding portion 17 e protruding toward the inside of the brushless motor 1 has a circular plate at the end portion 17 f of the circular plate portion 17 b that forms the opening 17 c. It is integrally formed with the part 17b. The projecting portion 17e has a circular shape centered on the shaft center of the shaft 4 and the wall portion 17d is formed by the projecting portion 17e and the end portion 17f that forms the opening 17c. It is formed.

  The end 4c of the shaft 4 has an inner diameter and a thin shape, and a gap 22 is formed between the wall 17d and the inner periphery of the end 4c. If there is no sealing means for closing the gap 22, dust or the like may enter the encoder cover 17 from the gap 22. In the present embodiment, a rubber O-ring (sealing member) 19 is used as the sealing means, and the O-ring (sealing member) 22 is disposed in the gap portion 22.

  The inner diameter of the O-ring (sealing member) 22 is set slightly smaller than the outer diameter of the protruding portion 17e, and the O-ring (sealing member) 22 has an outer periphery of the protruding portion 17e due to an elastic force that tends to shrink in the circumferential direction. It is attached to the surface. On the other hand, the outer diameter of the O-ring (sealing member) 22 attached to the outer peripheral surface of the protruding portion 17e is set to be slightly larger than the inner diameter of the end 4c of the shaft 4, and the O-ring (sealing member) 22 The outer periphery of the O-ring (sealing member) 22 comes into contact with the inner periphery of the end portion 4c in a state where the cross section of FIG.

  In this way, the inner periphery of the O-ring 22 is in contact with the outer periphery of the projecting portion 17e, and the outer periphery of the O-ring 22 is in contact with the inner periphery of the end portion 4c of the shaft 4, whereby the first protrusion of the shaft 4 A gap 22 formed between 4 a and the encoder cover 17 is covered with an O-ring 22.

  FIG. 6 shows the shape and attachment means of the sealing member 22 of the fourth embodiment of the present invention, and is an enlarged view of the third embodiment corresponding to the portion indicated by C in FIG. . As shown in FIG. 6, in the fourth embodiment, the protruding portion 17e that protrudes toward the optical encoder 14 has a disc portion 17b at the end portion 17f of the disc portion 17b that forms the opening 17c. Are integrally formed. The projecting portion 17e has a circular shape centered on the shaft center of the shaft 4 and the wall portion 17d is formed by the projecting portion 17e and the end portion 17f that forms the opening 17c. It is formed.

  The inner periphery of the wall portion 17e and the outer periphery of the end portion 4c of the shaft 4 are separated from each other, and a gap portion 22 is formed between the inner periphery of the wall portion 17e and the outer periphery of the end portion 4c of the shaft 4. . If there is no sealing means for closing the gap 22, dust or the like may enter the encoder cover 17 from the gap 22. In this embodiment, a rubber sealing ring (sealing member) 19 is used as the sealing means, and the sealing ring (sealing member) 22 is disposed in the gap portion 22.

  The sealing ring (sealing member) 22 has a mountain shape when viewed in cross section, and gradually decreases in width from the outer periphery toward the inner periphery, and a sharpened portion 19a is formed on the inner periphery. The outer periphery of the sealing ring (sealing member) 22 is attached to the inner periphery of the wall portion 17d with an adhesive. The inner diameter of the sealing ring (sealing member) 22 attached to the wall 17d is set to be slightly smaller than the outer diameter of the end 4c of the shaft 4, and the tip of the sharpened portion 19a of the sealing ring 22 is the end 4c. It is in contact with the outer periphery of. In this way, the gap 22 formed between the inner periphery of the wall 17e and the outer periphery of the end 4c of the shaft 4 is covered with the sealing ring 22.

  FIG. 7 shows the shape and attachment means of the fifth embodiment of the present invention, and is an enlarged view of the fifth embodiment corresponding to the portion indicated by C in FIG. As shown in FIG. 7, in the fifth embodiment, the protruding portion 17e that protrudes toward the inside of the brushless motor 1 has a circular plate at the end portion 17f of the circular plate portion 17b that forms the opening 17c. It is integrally formed with the part 17b. The projecting portion 17e has a circular shape centered on the shaft center of the shaft 4 and the wall portion 17d is formed by the projecting portion 17e and the end portion 17f that forms the opening 17c. It is formed.

  The end 4c of the shaft 4 has an inner diameter and a thin shape, and a gap 22 is formed between the wall 17d and the inner periphery of the end 4c. If there is no sealing means for closing the gap 22, dust or the like may enter the encoder cover 17 from the gap 22. In this embodiment, a rubber sealing ring (sealing member) 19 is used as the sealing means, and the sealing ring (sealing member) 22 is disposed in the gap portion 22.

  The sealing ring (sealing member) 22 has a mountain shape in cross section, and a sharpened portion 19a whose width gradually decreases from the inner periphery toward the outer periphery is integrally formed with the inner diameter portion. The inner periphery of the sealing ring (sealing member) 22 is attached to the outer periphery of the wall portion 17d with an adhesive. The outer diameter of the sealing ring (sealing member) 22 attached to the wall portion 17d is set to be slightly larger than the inner diameter of the end portion 4c of the shaft 4, and the tip of the sharpened portion 19a of the sealing ring 22 is the end portion 4c. It is in contact with the inner periphery of. In this way, the gap 22 formed between the outer periphery of the wall 17e and the inner periphery of the end 4c of the shaft 4 is covered with the sealing ring 22.

  FIG. 8 shows the shape and attachment means of the sixth embodiment of the present invention, and is an enlarged view of the sixth embodiment corresponding to the portion indicated by C in FIG. Since the sixth embodiment differs from the fifth embodiment only in the shape of the sharpened portion 19a, the sharpened portion 19a will be described, and description of the other portions will be omitted.

  In the fifth embodiment, one sharpened portion 19a is formed, and the tip of one sharpened portion 19a abuts on the inner periphery of the end 4c of the shaft 4 to ensure the sealing of the gap 22. It was. On the other hand, as shown in FIG. 8, in the sixth embodiment, two sharpened portions 19a are formed integrally with the sealing ring 19 in parallel in the axial direction. Therefore, when the tips of the two sharpened portions 19 a and 19 a are in contact with the inner periphery of the end portion 4 c of the shaft 4, the sealing performance of the gap portion 22 is further ensured.

  In this way, by a simple means of attaching the sealing member 22, dust or the like enters the encoder cover 17 from the gap portion 22 and is appropriately prevented from adhering to the slit plate 14 b or the like. Can do. Thereby, adhesion of dust etc. to the slit plate 14b can be prevented, and highly accurate rotation position detection can be secured.

It is a perspective view of the brushless motor in the 1st embodiment of the present invention. It is a longitudinal cross-sectional view of the brushless motor indicated by A in FIG. It is a cross-sectional view of the brushless motor indicated by B in FIG. It is an enlarged view of 2nd Embodiment of the part designated by C in FIG. It is an enlarged view of 3rd Embodiment of the part designated by C in FIG. It is an enlarged view of 4th Embodiment of the part designated by C in FIG. It is an enlarged view of 5th Embodiment of the part designated by C in FIG. It is an enlarged view of 6th Embodiment of the part designated by C in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Brushless motor 2 Stator 2a Stator main body 2b Salient pole 3 Rotor 4 Shaft 4a First protrusion (protrusion)
4b Second protrusion (protrusion)
4c End 5 (Ring) Magnet 6 Coil 7 Motor case 8 Stator case 9 Rear bracket (bracket)
9a First through hole (through hole)
10 Front bracket (bracket)
10a Second through hole (through hole)
13 Optical encoder 14 Encoder ring 14a Encoder ring main body 14b Slit plate 15 Optical sensor 15a Sensor element 17 Encoder cover 17a Cylindrical portion 17b Disc portion 17c Opening 17d Wall portion 17e Projection portion 17f End portion 19 Sealing member 22 Gap portion

Claims (1)

A stator case formed in a substantially cylindrical shape;
A pair of brackets that are formed in a substantially disc shape and a through hole is formed in the center, and the opening of the stator case is closed; and
A stator having a substantially annular shape and having a stator body attached to the inner wall of the stator case, and a plurality of salient poles projecting radially inward from the inner peripheral surface of the stator body;
A coil wound around each of the salient poles of the stator;
A shaft formed in a hollow cylindrical shape, inserted through the through holes of the pair of brackets and rotatably supported by the pair of brackets, and a magnet supported by the shafts, In a brushless motor comprising a rotor disposed oppositely,
The shaft of the brushless motor includes a protruding portion that protrudes to the outside from a through hole of one bracket of the bracket,
The brushless motor is
An encoder ring attached to the outer peripheral surface of the projecting portion of the shaft; and a sensor element, the sensor element facing the slit plate of the encoder ring, An encoder having an optical sensor attached to one of the brackets;
Formed in a substantially bottomed cylindrical shape, an opening facing the through hole of the bracket is formed in the approximate center of the bottom, covers the encoder, and an encoder cover attached to the one bracket;
The encoder cover and the protruding portion of the shaft are in contact with each other, and are disposed between the encoder cover and the protruding portion of the shaft, and cover a gap formed between the protruding portion of the shaft and the encoder cover. A brushless motor comprising a sealing member.

Images