Encoder and motor

Abstract

An encoder (20) according to Embodiment 1 comprises a boss (21), a rotating plate (24), an optical module (25), a substrate (26), and a frame (30) provided between the substrate (26) and a bracket (12) of a motor (10). At least one recess (35) is formed on the surface of the frame (30) facing the bracket (12). The frame (30) has at least one communication path (36). The at least one communication path (36) is surrounded by the bracket (12), the frame (30), and the substrate (26) and allows communication between an internal space (S) in which the boss (21), the rotating plate (24), and the optical module (25) are disposed, and at least one recess (35).

Description

Encoders and Motors

[0001] The present disclosure relates to an encoder and a motor.

[0002] Conventionally, encoders that detect the rotational position of a shaft of a motor are known (for example, see Patent Document 1). Patent Document 1 discloses a rotary encoder that includes a rotating optical surface, an optical sensor, a container, an opening, and a collection member. The rotating optical surface includes an optical pattern, is fixed to a rotation shaft, and rotates together with the rotation shaft. The optical sensor detects the optical pattern. The container houses the rotating optical surface and the optical sensor in a sealed space. The opening is provided in the container and can be closed. The collection member is positioned facing the opening and collects dust.

[0003] Japanese Patent Application Laid-Open No. 2020-169918

[0004] However, the rotary encoder of Patent Document 1 requires the installation of an additional device for blowing or suctioning air into the enclosed space and a dust collection member to collect dust, resulting in a relatively complex configuration. However, if foreign matter such as dust adheres to the rotating optical surface of the encoder, it may be difficult to properly detect the rotational position, so it is desirable to take measures against foreign matter. In this situation, the present disclosure provides an encoder and motor that can easily implement measures against foreign matter.

[0005] One aspect of the present disclosure relates to an encoder. The encoder includes a boss that rotates around a rotation axis of a shaft of a motor that includes a bracket and a shaft, and a rotating plate fixed to the boss and rotating around the rotation axis. The encoder also includes an optical module having a light source that irradiates light onto the rotating plate and a light-receiving element that receives light reflected from or transmitted through the rotating plate, a substrate to which the optical module is fixed, and a frame provided between the substrate and the bracket. At least one recess is formed on a surface of the frame facing the bracket. The frame has at least one communication passage that communicates the at least one recess with an internal space surrounded by the bracket, frame, and substrate and in which the boss, rotating plate, and optical module are disposed.

[0006] Another aspect of the present disclosure relates to a motor, the motor including the encoder described above, a motor body having a bracket to which a frame is attached, and a shaft attached to a boss.

[0007] According to the present disclosure, it is possible to provide an encoder and a motor that can easily implement measures against foreign matter.

[0008] FIG. 1 is a cross-sectional view schematically showing a motor including an encoder according to a first embodiment, with its essential parts shown enlarged. FIG. 2 is a perspective view of the frame of the encoder according to the first embodiment, seen from a direction in which the surface on the board side (the upper surface in FIG. 1) can be seen. FIG. 3 is a perspective view of the frame of the encoder according to the first embodiment, seen from a direction in which the surface on the bracket side (the lower surface in FIG. 1) can be seen. FIG. 4 is a cross-sectional view schematically showing a motor including an encoder according to a second embodiment, with its essential parts shown enlarged. FIG. 5 is a cross-sectional view schematically showing a motor including an encoder according to a third embodiment. FIG. 6 is a perspective view showing a boss of the encoder according to the third embodiment. FIG. 7 is an exploded perspective view showing the frame and board of the encoder according to a fourth embodiment.

[0009] Embodiments of an encoder and a motor according to the present disclosure will be described below using examples. However, the present disclosure is not limited to the examples described below. While specific numerical values ​​and materials may be used in the following description, other numerical values ​​and materials may be used as long as the effects of the present disclosure are obtained.

[0010] (Encoder) The encoder according to the present disclosure is attached to a motor including a bracket and a shaft, and is configured to detect at least the rotational position of the shaft. The encoder according to the present disclosure includes a boss, a rotating plate, an optical module, a substrate, and a frame.

[0011] The boss rotates around the rotation axis of the motor shaft. The boss may be fixed to the shaft by a bolt. The boss may be made of a metal material such as stainless steel.

[0012] The rotating plate is fixed to the boss and rotates around the rotation axis of the shaft. The rotating plate may rotate around the rotation axis integrally with the boss. The rotating plate may have a predetermined pattern formed along its circumferential direction. The predetermined pattern may be a pattern used to detect the rotation position of the shaft, or a pattern used to detect the rotation position and rotation number of the shaft. The rotation position of the shaft refers to the relative angular position or absolute angular position of the shaft. The rotation number of the shaft refers to the number of times the shaft has rotated.

[0013] The rotating plate may be opaque or transparent. Opaque means, for example, blocking 90% or more of ultraviolet light or visible light. Transparent means, for example, transmitting 90% or more of ultraviolet light or visible light. The rotating plate may be made of a metal material such as stainless steel. The rotating plate may be formed in a circular (or disk-like) shape. A circular shape refers to a shape in which 80% or more of the outer shape is formed by an arc.

[0014] The optical module includes a light source that irradiates the rotating plate with light and a light-receiving element that receives light reflected or transmitted from the rotating plate. The light source and the light-receiving element may both be located on one side of the rotating plate, in which case the light-receiving element receives light emitted from the light source and reflected by the rotating plate. Alternatively, one of the light source and the light-receiving element may be located on one side of the rotating plate and the other on the other side of the rotating plate, in which case the light-receiving element receives light emitted from the light source and transmitted through the rotating plate. The light-receiving element may convert the received light into an electrical signal. This electrical signal may be used to determine at least one of the rotational position and the rotation speed of the shaft.

[0015] The optical module is fixed to the substrate. Various electronic components other than the optical module may be mounted on the substrate. The shape of the substrate is not particularly limited, and may be, for example, substantially disk-shaped. The substrate may be fixed to a bracket of the motor together with the frame.

[0016] The frame is provided between the substrate and the bracket. The shape of the frame is not particularly limited and may be, for example, substantially cylindrical. At least one recess is formed on the surface of the frame facing the bracket. The opening of the at least one recess may be closed by the bracket when the frame is fixed to the bracket. The frame has at least one communication passage that connects the at least one recess to an internal space surrounded by the bracket, frame, and substrate and in which the boss, the rotating plate, and the optical module are disposed. The internal space may be sealed except for the fact that it is connected to the recess via the communication passage. The shape of the at least one communication passage is not particularly limited, but it is preferably formed in a slit shape from the perspective of ease of processing. The number of communication passages is also not particularly limited and may be only one or two or more. The two openings of the communication passage (i.e., the opening on the internal space side and the opening on the recess side) may be arranged side by side in a direction perpendicular to the rotation axis.

[0017] With the above-described configuration, even if foreign matter such as dust enters or is present in the internal space, the foreign matter is sent to the communication passage formed in the frame by the airflow generated by the rotation of the boss and the rotating plate, and then enters the recess formed in the frame. Foreign matter that enters the recess is unlikely to move from the recess toward the internal space due to the airflow generated by the rotation of the boss and the rotating plate. Therefore, foreign matter is unlikely to remain attached to the surface of the rotating plate or the surface of the optical module, hindering normal operation of the encoder. Such foreign matter countermeasures can be easily achieved by simply forming a recess and a communication passage in the frame. As described above, the present disclosure can provide an encoder that allows for easy foreign matter countermeasures.

[0018] At least one communication passage may be formed by a slit formed in the frame. The slit may extend along the rotational direction of the rotary plate (or the circumferential direction of the shaft). The number of slits is not particularly limited, and if multiple slits are provided, the multiple slits may be arranged side by side in the rotational direction of the rotary plate. In the circumferential direction of the shaft, the length of the inner peripheral surface of the frame may be L1, and the length of the region where the slits are present may be L2, where 0.4≦L2 / L1≦0.8 may be satisfied. In this case, foreign matter in the internal space can efficiently enter the recess through the slit while ensuring sufficient structural strength of the frame. The maximum width of the slit may be, for example, 0.5 mm or more and 3 mm or less.

[0019] At least one communication passage may be formed by a through-hole formed in the frame. The shape of the through-hole is not particularly limited and may be, for example, circular, elliptical, or polygonal. The number of through-holes is also not particularly limited. When multiple through-holes are provided, the multiple through-holes may be arranged side by side in the rotation direction of the rotating plate.

[0020] The at least one communication passage may include a plurality of communication passages. The plurality of communication passages may be aligned along the rotation direction of the rotary plate. In this case, foreign matter in the internal space is more likely to enter the communication passage and, therefore, the recess than when only one communication passage is provided.

[0021] The at least one communication passage may narrow from the internal space toward the at least one recess. For example, the at least one communication passage may taper from the internal space toward the at least one recess in a cross section including the rotation axis of the shaft. With this configuration, the communication passage opens relatively large on the internal space side, making it easy for foreign matter in the internal space to enter the communication passage. On the other hand, the communication passage opens relatively small on the recess side, making it difficult for foreign matter contained in the recess to enter the communication passage and, therefore, return to the internal space.

[0022] The boss may have at least one fin that creates a centrifugal airflow as the boss rotates. A centrifugal airflow refers to an airflow that generally moves in a centrifugal direction overall. In other words, even if the airflow includes an airflow that moves in a direction that intersects the centrifugal direction microscopically, the airflow is considered to be a centrifugal airflow as long as it moves in a centrifugal direction macroscopically. The at least one fin may be integrally formed with the boss or attached to the boss. With this configuration, when the boss rotates (or when the boss and the rotating plate rotate), foreign matter in the internal space is more likely to be carried toward the communicating passage and the recess by the centrifugal airflow.

[0023] The at least one fin may include a first fin disposed between the rotating plate and the optical module in the direction along the rotation axis, in which case foreign matter adhering to the rotating plate and the optical module can be efficiently removed by a centrifugal air flow created by the first fin.

[0024] The at least one fin may include a second fin disposed between the rotating plate and the bracket in the direction along the rotation axis, in which case foreign matter in the internal space can be efficiently carried to the communication passage and the recess by a centrifugal air flow created by the second fin.

[0025] The substrate may have at least one through hole. The frame may have at least one blocking portion that blocks an opening of the at least one through hole on the frame side. Here, if a through hole is present in the substrate, the internal space may communicate with the outside via the through hole, which may allow foreign matter to enter the internal space from the outside. In contrast, in this configuration, the opening of the through hole on the frame side is blocked by the blocking portion of the frame, so that the internal space and the outside are not substantially connected via the through hole, and foreign matter is less likely to enter the internal space from the outside.

[0026] (Motor) A motor according to the present disclosure includes the above-described encoder, a motor body, and a shaft. The motor may be, for example, an inner rotor type three-phase synchronous motor, but is not limited to this.

[0027] The motor body has a bracket to which the encoder frame is attached. The motor body may further have a case to which the bracket is fixed, and a rotor and a stator housed in the case. The rotor may be attached to the shaft. The rotor may have a rotor core made of a magnetic material and a plurality of permanent magnets fixed to the rotor core. The stator may be provided facing the rotor. The stator may have a stator core made of a magnetic material and a plurality of coils wound around the stator core.

[0028] The shaft is attached to the boss of the encoder. The shaft may be attached to the boss by a bolt. The shaft may be made of a magnetic material or a non-magnetic material.

[0029] As described above, according to the present disclosure, by providing a recess and a communication passage in the frame of the encoder, it is possible to provide a motor that can easily implement measures to prevent foreign matter from entering the encoder.

[0030] An example of an encoder and a motor according to the present disclosure will be described in detail below with reference to the drawings. The components described above can be applied to the components of the example encoder and motor described below. The components of the example encoder and motor described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above-described embodiment. Among the components of the example encoder and motor described below, components that are not essential to the encoder and motor according to the present disclosure may be omitted. Note that the diagrams shown below are schematic and do not accurately reflect the shapes or number of actual components. Furthermore, in the following description, terms indicating specific directions, such as "up" and "down," may be used, but this is for convenience of explanation and does not limit the present disclosure.

[0031] Embodiment 1 Embodiment 1 of the present disclosure will be described with reference to Figures 1 to 3. Figure 1 is a cross-sectional view that schematically shows a motor 10 equipped with an encoder 20 according to embodiment 1, with a main portion thereof shown enlarged. Figure 2 is a perspective view of a frame 30 of the encoder 20 according to embodiment 1, seen from a direction in which the surface on the circuit board 26 side (the upper surface in Figure 1) can be seen. Figure 3 is a perspective view of the frame 30 of the encoder 20 according to embodiment 1, seen from a direction in which the surface on the bracket 12 side (the lower surface in Figure 1) can be seen.

[0032] The motor 10 of this embodiment is an inner rotor type three-phase synchronous motor, but is not limited to this. As shown in Figure 1, the motor 10 includes a motor body 11, a shaft 16, and an encoder 20.

[0033] The motor main body 11 includes a bracket 12, a case 13, a rotor 14, and a stator 15. A frame 30 (described later) of the encoder 20 is attached to the bracket 12. The bracket 12 is fixed to the case 13. The case 13 is a hollow cylindrical member that houses the rotor 14 and the stator 15. The stator 15 is fixed to the inner surface of the case 13. In this embodiment, the case 13 and the bracket 12 are separate bodies, but they may also be integrally formed. The rotor 14 is attached to a shaft 16 and rotates together with the shaft 16 around the rotation axis O. In this embodiment, the rotor 14 is an embedded magnet rotor, but is not limited to this. The stator 15 faces the rotor 14 across an air gap. The stator 15 is provided radially outside the rotor 14 of the motor 10. In this embodiment, the stator 15 is a concentrated winding stator, but is not limited to this.

[0034] The shaft 16 passes through the bracket 12 and is rotatably supported by the bracket 12 via a bearing 17. The shaft 16 is attached to a boss 21 (described later) of the encoder 20 and rotates together with the boss 21 around its own rotation axis O.

[0035] The encoder 20 of this embodiment is a multi-rotation absolute encoder, but is not limited to this. The encoder 20 of this embodiment is a battery-powered encoder, but may also be a battery-less encoder equipped with a permanent magnet and a power generating element. As shown in Figures 1 to 3, the encoder 20 includes a boss 21, a rotating plate 24, an optical module 25, a substrate 26, and a frame 30.

[0036] The boss 21 rotates around the rotation axis O together with the shaft 16. The boss 21 is fixed to the shaft 16 by a bolt 40 inserted through the bolt hole 22. The boss 21 is made of stainless steel, but is not limited to this.

[0037] The rotating plate 24 is formed in a circular (or annular) shape. The rotating plate 24 is fixed to the boss 21 and rotates together with the boss 21 around the rotation axis O. The rotating plate 24 has a predetermined pattern (not shown) formed along its circumferential direction. The predetermined pattern is used to detect the rotational position and rotation speed of the shaft 16. The rotating plate 24 is made of stainless steel, but is not limited to this. The rotating plate 24 is opaque, but may have a certain degree of translucency. The rotating plate 24 reflects light irradiated from the optical module 25.

[0038] The optical module 25 includes a light source (e.g., an LED) that irradiates the rotating plate 24 with light and a light-receiving element (e.g., a photodiode) (both not shown). The optical module 25 has a substantially rectangular shape when viewed along the rotation axis O (the vertical direction in FIG. 1 , hereinafter also referred to as the rotation axis direction), but the shape is not particularly limited. The substantially rectangular shape includes not only a rectangular shape but also a rectangular shape with rounded corners. The light-receiving element receives light emitted from the light source and reflected by the rotating plate 24. The light-receiving element converts the received light into an electrical signal. This electrical signal is used to determine the rotational position and rotation speed of the shaft 16.

[0039] The optical module 25 is fixed to the substrate 26. Although not shown, various electronic components are also mounted on the substrate 26. The substrate 26 is substantially disk-shaped, and is attached to the bracket 12 via a frame 30 with a plurality of screws (not shown).

[0040] The frame 30 is provided between the substrate 26 and the bracket 12 and is fixed to the bracket 12. The frame 30 is substantially cylindrical. The frame 30 houses the rotating plate 24 and supports the substrate 26 so that the optical module 25 faces the rotating plate 24 (more specifically, an area of ​​the rotating plate 24 on which a predetermined pattern is formed). The substrate 26 is fixed to the frame 30 by a predetermined fixing means. For example, it is conceivable to fix the two to each other by press-fitting pins 32 ( FIG. 2 ) of the frame 30 into pin holes (not shown) formed in the substrate 26.

[0041] As shown in Figure 2, the surface of the frame 30 facing the substrate 26 (the upper surface in Figure 1) is provided with a plurality of (three in this example) fixing regions 31 in which insertion holes 33 for inserting the screws are arranged. Two of the three fixing regions 31 are provided with pins 32 for fixing the frame 30 to the substrate 26. The fixing regions 31 are arranged at approximately equal intervals in the circumferential direction, but this is not limited to this. A peripheral edge 34 is provided between adjacent fixing regions 31 in the circumferential direction. The surface of each fixing region 31 and the surface of each peripheral edge 34 are flush with each other, and both abut against the substrate 26 when the encoder 20 is assembled.

[0042] The boss 21, the rotating plate 24, and the optical module 25 are disposed in the space surrounded by the bracket 12, the frame 30, and the substrate 26 (hereinafter referred to as the internal space S). Foreign matter such as dust and metal fragments may enter this internal space S, for example, when assembling the encoder 20. In contrast, the encoder 20 of this embodiment can easily implement measures against foreign matter by using the configuration described below.

[0043] As shown in Fig. 3, at least one recess 35 (three in this example) is formed on the surface of the frame 30 facing the bracket 12 (the lower surface in Fig. 1). Each recess 35 extends in the circumferential direction, and an insertion hole 33 is disposed between adjacent recesses 35. The frame 30 also has at least one communication passage 36 (three in this example) that connects the at least one recess 35 with the internal space S.

[0044] At least one communication passage 36 is formed by a slit 36A formed in the frame 30. The slit 36A extends in the circumferential direction. The region in which the slit 36A extends in the circumferential direction is narrower than the region in which the recess 35 extends, but this is not limited to this. When viewed from the rotation axis direction, the angle formed by the line segment connecting one end of each slit 36A to the rotation axis O and the line segment connecting the other end of each slit 36A to the rotation axis O (or the central angle when each slit 36A is considered to be an arc) may be, for example, 10° or more and 120° or less. Although not shown, at least one communication passage 36 may be formed by a through-hole formed in the frame 30.

[0045] In this embodiment, the at least one communication passage 36 includes a plurality (three in this example) of communication passages 36. The plurality of communication passages 36 are aligned along the rotation direction (or circumferential direction) of the rotating plate 24. The plurality of communication passages 36 may be aligned at equal intervals along the circumferential direction, or may be aligned at unequal intervals.

[0046] When the motor 10 is driven, the boss 21 and the rotating plate 24 rotate in conjunction with the rotation of the shaft 16, generating a centrifugal air flow within the internal space S. This air flow carries, for example, foreign matter adhering to the rotating plate 24 to at least one recess 35 via at least one communication passage 36 formed in the frame 30. In this way, in the encoder 20, foreign matter countermeasures can be easily achieved simply by devising the shape of the frame 30, without the need for a separate device such as a blower.

[0047] Second Embodiment A second embodiment of the present disclosure will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view that schematically illustrates a motor 101 equipped with an encoder 201 according to the second embodiment, with a main portion thereof shown enlarged. The encoder 201 of this embodiment differs from the communicating path 36 of the first embodiment in the configuration of the communicating path 361. The following description will mainly focus on the differences from the first embodiment.

[0048] As shown in Fig. 4, the at least one communication passage 361 is formed by a slit 361A formed in the frame 30. The at least one communication passage 361 narrows from the internal space S toward the at least one recess 35 (or from the inner periphery toward the outer periphery). In this embodiment, the communication passage 361 narrows continuously or linearly from the internal space S toward the at least one recess 35, but this is not limitative. The other configurations are the same as those in the first embodiment.

[0049] Third Embodiment A third embodiment of the present disclosure will be described with reference to Figures 5 and 6. Figure 5 is a cross-sectional view that schematically shows a motor 102 equipped with an encoder 202 of the third embodiment. Figure 6 is a perspective view that shows a boss 212 of the encoder 202 of the third embodiment. In the encoder 202 of this embodiment, the configuration of the boss 212 differs from the configuration of the boss 21 of the first embodiment. The following mainly describes the differences from the first embodiment.

[0050] As shown in FIGS. 5 and 6 , the boss 212 includes at least one fin 23 that generates a centrifugal airflow as the boss 212 rotates. The at least one fin 23 includes a first fin 23A disposed between the rotating plate 24 and the optical module 25 in the rotational axis direction and a second fin 23B disposed between the rotating plate 24 and the bracket 12 in the rotational axis direction. However, it is sufficient that the at least one fin 23 includes at least one of the first fin 23A and the second fin 23B. Each second fin 23B is larger than each first fin 23A, but this is not a limitation. Each first fin 23A is located more inward than each second fin 23B, but this is not a limitation. The second fin 23B is located radially opposite the communicating passage 36. The remaining configuration is the same as that of the first embodiment.

[0051] Fourth Embodiment A fourth embodiment of the present disclosure will be described with reference to Fig. 7. Fig. 7 is an exploded perspective view showing a frame 303 and a substrate 263 of an encoder of the fourth embodiment. In the encoder of this embodiment, the configuration of the frame 303 differs from the configuration of the frame 30 of the first embodiment. The following mainly describes the differences from the first embodiment.

[0052] As shown in Figure 7, the substrate 263 has at least one (in this example, multiple) through-hole 26a. Note that the substrate 26 of the first embodiment may also have a similar through-hole 26a. The frame 303 has at least one (in this example, three) blocking portion 37 that blocks the opening of at least one through-hole 26a on the frame 303 side (the lower side in Figure 7). Note that in Figure 7, for ease of understanding, the portion of the frame 303 that corresponds to the blocking portion 37 is hatched with diagonal lines. The rest of the configuration is the same as that of the first embodiment.

[0053] <<Supplementary Note>> The above description of the embodiment discloses the following techniques.

[0054] (Technology 1) An encoder of Technology 1 includes a boss that rotates around the rotation axis of a shaft of a motor that includes a bracket and a shaft, and a rotating plate that is fixed to the boss and rotates around the rotation axis. The encoder of Technology 1 also includes an optical module that has a light source that irradiates light onto the rotating plate and a light receiving element that receives light reflected from or transmitted through the rotating plate, a substrate to which the optical module is fixed, and a frame that is provided between the substrate and the bracket.

[0055] At least one recess is formed in a surface of the frame facing the bracket, and the frame has at least one communication passage that connects the at least one recess with an internal space surrounded by the bracket, frame, and base plate and in which the boss, rotating plate, and optical module are disposed.

[0056] (Technology 2) In the encoder of Technology 2, in the encoder described in Technology 1, at least one communication path is formed by a slit formed in the frame.

[0057] (Technology 3) In the encoder of Technology 3, in the encoder according to Technology 1, at least one communication path is configured as a through hole formed in the frame.

[0058] (Technology 4) In the encoder of Technology 4, in the encoder described in any one of Technologies 1 to 3, at least one communication path includes a plurality of communication paths, and the plurality of communication paths are aligned along the rotation direction of the rotating plate.

[0059] (Technology 5) In the encoder of Technology 5, in the encoder according to any one of Technologies 1 to 4, the at least one communication path narrows from the internal space toward the at least one recess.

[0060] (Technology 6) In the encoder of Technology 6, in the encoder according to any one of Technologies 1 to 5, the boss has at least one fin that creates a centrifugal air flow as the boss rotates.

[0061] (Technology 7) In an encoder of Technology 7, in the encoder according to Technology 6, the at least one fin includes a first fin disposed between the rotating plate and the optical module in a direction along the rotation axis.

[0062] (Technology 8) In an encoder of Technology 8, in the encoder according to Technology 6 or 7, the at least one fin includes a second fin disposed between the rotating plate and the bracket in the direction along the rotation axis.

[0063] (Technology 9) In the encoder of Technology 9, in the encoder described in any one of Technologies 1 to 8, the substrate has at least one through hole, and the frame has at least one blocking portion that blocks an opening on the frame side of the at least one through hole.

[0064] (Technology 10) A motor of Technology 10 includes the encoder according to any one of Technologies 1 to 9, a motor body having a bracket to which a frame is attached, and a shaft attached to the boss.

[0065] The present disclosure can be used in encoders and motors.

[0066] REFERENCE SIGNS LIST 10 Motor 11 Motor body 12 Bracket 13 Case 14 Rotor 15 Stator 16 Shaft 17 Bearing 20 Encoder 21 Boss 22 Bolt hole 23 Fin 23A First fin 23B Second fin 24 Rotating plate 25 Optical module 26 Substrate 26a Through hole 30 Frame 31 Fixing area 32 Pin 33 Insertion hole 34 Peripheral edge portion 35 Recess 36 Communication path 36A Slit 37 Closure portion 40 Bolt 101 Motor 102 Motor 201 Encoder 202 Encoder 212 Boss 263 Substrate 303 Frame 361 Communication path 361A Slit O Rotating shaft S Internal space

Claims

1. An encoder comprising: a boss that rotates around the rotation axis of a shaft of a motor having a bracket and a shaft; a rotating plate fixed to the boss and rotating around the rotation axis; an optical module having a light source that irradiates light onto the rotating plate and a light receiving element that receives light reflected from or transmitted through the rotating plate; a substrate to which the optical module is fixed; and a frame provided between the substrate and the bracket, wherein at least one recess is formed on the surface of the frame facing the bracket, and the frame has at least one communication path that connects the at least one recess with an internal space surrounded by the bracket, frame, and substrate, and in which the boss, rotating plate, and optical module are arranged.

2. The encoder according to claim 1, wherein the at least one communication path is formed by a slit formed in the frame.

3. The encoder according to claim 1, wherein the at least one communication path is configured as a through hole formed in the frame.

4. An encoder according to any one of claims 1 to 3, wherein the at least one communication path includes a plurality of communication paths, and the plurality of communication paths are aligned along the rotation direction of the rotating plate.

5. An encoder according to any one of claims 1 to 3, wherein the at least one communication passage narrows from the internal space toward the at least one recess.

6. An encoder according to any one of claims 1 to 3, wherein the boss has at least one fin that creates a centrifugal air flow as the boss rotates.

7. The encoder according to claim 6, wherein the at least one fin includes a first fin disposed between the rotating plate and the optical module in the direction along the rotation axis.

8. The encoder according to claim 6, wherein the at least one fin includes a second fin disposed between the rotating plate and the bracket in the direction along the rotation axis.

9. An encoder according to any one of claims 1 to 3, wherein the substrate has at least one through hole, and the frame has at least one blocking portion that blocks an opening of the at least one through hole on the frame side.

10. A motor comprising: the encoder according to any one of claims 1 to 3; a motor body having the bracket to which the frame is attached; and the shaft attached to the boss.

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