Encoder cover and motor

Abstract

The present invention keeps heat from being transmitted from a motor body part to an encoder. This encoder cover (10) is to cover an encoder (20) that detects the rotational position of a shaft (41) of a motor (1). The encoder cover (10) comprises a flange (11) that is attached to the encoder (20), a first cover member (12) that is provided at an opposite position from the flange (11) as seen from the encoder (20) and covers a portion of the encoder (20), and a second cover member (13) that connects the flange (11) and the first cover member (12) and covers a portion of the encoder (20). The thermal conductivity of the second cover member (13) of the encoder cover (10) is lower than the thermal conductivity of the flange (11) and the thermal conductivity of the first cover member (12).

Description

Technical Field

[0005]

[0001] The present disclosure relates to an encoder cover that covers an encoder for detecting the rotational position of a motor shaft and a motor provided with the same.

Background Art

[0002] Conventionally, an encoder cover that covers an encoder for detecting the rotational position of a motor shaft has been known (for example, Patent Document 1). The encoder cover of Patent Document 1 includes an encoder housing portion for housing the encoder and a flange portion for joining to a bracket of the motor. The encoder housing portion and the flange portion are integrally formed of a die-cast alloy having conductivity.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] In the encoder cover of Patent Document 1, the normal operation of the encoder may be hindered due to the heat of the motor main body (including the magnetic circuit portion having a rotor and a stator). That is, since the encoder housing portion and the flange portion are integrally formed of a die-cast alloy having a high thermal conductivity, the heat of the motor main body is likely to be transmitted to the encoder housing portion through the flange portion. In this way, heat accumulates inside the encoder housing portion, that is, in the space where the encoder is housed, and the normal operation of the encoder is hindered by the heat. In such a situation, one of the objects of the present disclosure is to suppress the transmission of heat from the motor main body to the encoder.

[0005] One aspect of the present disclosure relates to an encoder cover. The encoder cover comprises a flange for mounting an encoder, a first cover member provided on the opposite side of the flange from the encoder and covering a portion of the encoder, and a second cover member connecting the flange and the first cover member and covering a portion of the encoder, wherein the thermal conductivity of the second cover member is smaller than that of the flange and the first cover member.

[0006] Another aspect of this disclosure relates to a motor. The motor comprises the encoder cover described above, an encoder housed in the encoder cover, and a main body having a shaft whose rotational position is detected by the encoder.

[0007] According to this disclosure, it is possible to suppress the transfer of heat from the motor body to the encoder. [Brief explanation of the drawing]

[0008] [Figure 1] A perspective view showing an example of an encoder cover according to one embodiment of this disclosure. [Figure 2] This is a top view of an encoder cover according to one embodiment of the present disclosure. [Figure 3] This is a cross-sectional view along the line III-III in Figure 2, showing the motor shaft and other components. [Modes for carrying out the invention]

[0009] An embodiment of an encoder cover and motor according to one embodiment of this disclosure will be described below with reference to examples. However, this disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values ​​and materials may be applied as long as the effects of this disclosure are obtained.

[0010] (Encoder cover) The encoder cover according to this disclosure is an encoder cover that covers an encoder for detecting the rotational position of a motor shaft, and comprises a flange, a first cover member, and a second cover member. The motor comprises a main body having a rotor including a shaft and a stator facing the rotor with a gap between them.

[0011] The flange is a component for mounting the encoder. The flange may have through holes through which mounting screws for attaching itself to the motor bracket are inserted. The encoder and a bearing that rotatably supports the motor shaft may be mounted on the flange. The rotating plate of the encoder may be mounted on the motor shaft.

[0012] The first cover member is provided on the opposite side of the flange from the encoder. The first cover member covers a portion of the encoder. The first cover member may be lid-shaped.

[0013] The second cover member connects the flange and the first cover member. The second cover member covers a portion of the encoder. The second cover member may be provided between the flange and the first cover member. The second cover member may be cylindrical.

[0014] The flange, the first cover member, and the second cover member may define the housing space in which the encoder is housed. This housing space may be a sealed space.

[0015] The thermal conductivity of the second cover member is lower than that of the flange and the first cover member. This second cover member suppresses heat conduction between the flange and the first and second cover members. Therefore, even if heat is generated in the motor body, it is less likely to be transferred to the first and second cover members via the flange, and heat is less likely to accumulate inside the encoder cover, i.e., in the space where the encoder is housed. Thus, it is possible to suppress the transfer of heat from the motor body to the encoder.

[0016] The first cover member and the flange may each be made of a conductive material. Suitable conductive materials include metals, carbon materials such as glassy carbon, or conductive resins.

[0017] The first cover member may be made of a first metal (e.g., aluminum, aluminum alloy). The first cover member made of the first metal has high thermal conductivity. Therefore, even if heat accumulates inside the encoder cover, that heat can be dissipated to the outside through the first cover member. Thus, the normal operation of the encoder can be further prevented from being hindered by heat.

[0018] The second cover member may be made of the first resin (for example, nylon resin). The second cover member made of the first resin has low thermal conductivity. Therefore, the heat insulation function of the second cover member can be easily ensured.

[0019] The encoder cover may further include a magnetic shielding member fixed to the first cover member and covering at least a portion of the encoder. The magnetic shielding member is made of a second metal (e.g., iron, iron alloy) and does not need to be in contact with the flange. Such a magnetic shielding member can suppress the influence of magnetic noise on the encoder. Also, for functional reasons, the magnetic shielding member is made of a second metal with high thermal conductivity. If the magnetic shielding member is not in contact with the flange, the transfer of heat from the flange to the first cover member via the magnetic shielding member is suppressed, and heat buildup inside the encoder cover is avoided. The second metal may be different from or the same as the first metal.

[0020] The first cover member may be fixed to the flange by a conductive bolt (for example, an iron bolt). According to this configuration, even if electric field noise enters the first cover member, the electric field noise is released to the flange through the bolt. Therefore, it is difficult for the electric field noise to be transmitted to the encoder, and malfunction of the encoder can be suppressed. Note that the electric field noise transmitted to the flange may further be transmitted to the bracket provided in the motor main body part.

[0021] The second cover member may have a housing of a connector. The housing may be made of a second resin (for example, nylon resin). The connector may be a connector to which wiring for transmitting a detection signal of the encoder is connected. According to such a configuration, since there is no need to separately provide the housing of the connector as the second cover member, the manufacturing cost of the encoder cover can be reduced. Note that the second resin may be the same type or a different type from the first resin.

[0022] The portion other than the housing of the second cover member and the housing may be integrally formed. According to this configuration, the second cover member having a housing can be easily manufactured. In addition, the encoder cover can be easily assembled as compared with the case where the portion other than the housing of the second cover member and the housing are separate bodies.

[0023] In the axial direction of the motor shaft (the direction in which the flange and the first cover member face each other), the length of the second cover member may be at least half of the length of the encoder cover. By the second cover member having such a length, the heat insulation function of the second cover member can be further enhanced.

[0024] (Motor) A motor according to another embodiment of the present disclosure includes the above-described encoder cover, an encoder housed in the encoder cover, and a main body portion having a shaft whose rotational position is detected by the encoder. The main body portion may include a rotor including the shaft, and a stator facing the rotor with a gap therebetween. The motor may be an inner rotor type three-phase synchronous motor, but is not limited thereto. The encoder may be a multi-turn absolute encoder (an absolute encoder that detects the rotational position and rotational speed of the shaft), but is not limited thereto. The encoder may include a battery or may not include a battery.

[0025] As described above, according to the present disclosure, heat transfer from the motor main body portion to the encoder can be suppressed, thereby enabling the encoder to operate normally.

[0026] Hereinafter, an example of the encoder cover and the motor according to the present disclosure will be specifically described with reference to the drawings. The above-described components can be applied to the components of the encoder cover and the motor in the example described below. The components of the encoder cover and the motor in the example described below can be changed based on the above description. Also, the matters described below may be applied to the above embodiments. Among the components of the encoder cover and the motor in the example described below, components that are not essential to the encoder cover and the motor according to the present disclosure may be omitted. Note that the drawings shown below are schematic and do not accurately reflect the actual shape and number of members.

[0027] FIG. 1 is a perspective view showing an example of an encoder cover 10 according to an embodiment of the present disclosure. FIG. 2 is a top view of the encoder cover 10. FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2, showing a cross-section including the shaft 41 of the motor 1 and the like.

[0028] As shown in Figures 1 to 3, the motor 1 comprises an encoder cover 10, an encoder 20, and a main body 40 having a rotor and stator including a shaft 41. The motor 1 in this embodiment is an inner rotor type three-phase synchronous motor, but is not limited to this.

[0029] The encoder cover 10 is an element that covers the encoder 20 and includes a flange 11, a first cover member 12, a second cover member 13, and a magnetic shielding member 14.

[0030] The flange 11 is a component for mounting the encoder 20. In this embodiment, the flange 11 is made of aluminum (an example of a third metal), but is not limited to this. For example, the flange 11 may be made of stainless steel. The flange 11 has through holes 11a through which mounting screws for attaching itself to the bracket 42 of the motor 1 are inserted. In this example, four through holes 11a are provided, but the number of through holes 11a is not limited to this. In addition to mounting the encoder 20, a bearing 50 that rotatably supports the shaft 41 is mounted on the flange 11. An annular magnetic shield plate 11c, made of iron, for example, is embedded in the flange 11. A magnetic material is preferable for the magnetic shield plate 11c, and in addition to iron, an iron alloy such as stainless steel can be used.

[0031] The first cover member 12 is provided on the opposite side of the flange 11 from the encoder 20 (to the left of the encoder 20 in the plane of Figure 3). In this embodiment, the first cover member 12 is made of aluminum (first metal) as a conductive material, but is not limited to this. A material with high thermal conductivity is particularly desirable for the first cover member 12, and in addition to aluminum, aluminum alloys such as duralumin, copper, or alloys containing copper can be used. The first cover member 12 covers a part of the encoder 20. In this example, the first cover member 12 covers the top of the encoder 20. The first cover member 12 is lid-shaped, but is not limited to this.

[0032] The first cover member 12 and the flange 11 may each be made of a conductive material. In addition to the materials mentioned above, conductive materials such as metals, carbon materials represented by glassy carbon, or conductive resins can be used. The first cover member 12 and the flange 11 may be made of the same material or different materials.

[0033] The first cover member 12 is fixed to the flange 11 by iron bolts 60. In this example, four bolts 60 are provided, but the number of bolts 60 is not limited to this. Each bolt 60 is screwed into the bolt hole 11b of the flange 11 through the first through hole 12a of the first cover member 12 and the second through hole 13b of the second cover member 13. It is desirable that the material of the bolts 60 be conductive, and not limited to iron, aluminum, stainless steel, or brass can be used, for example.

[0034] The second cover member 13 is provided between the flange 11 and the first cover member 12. The second cover member 13 connects the flange 11 and the first cover member 12. The second cover member 13 is fixed to the first cover member 12 at one end 13e and to the flange 11 at the other end 13f. In this embodiment, the second cover member 13 is made of nylon resin (first resin), but is not limited thereto. A material with low thermal conductivity is desirable for the second cover member 13, and in addition to nylon resin, polystyrene or the like can be used. The second cover member 13 covers a part of the encoder 20. In this example, the second cover member 13 covers the side of the encoder 20. The second cover member 13 is cylindrical, but is not limited thereto.

[0035] The second cover member 13 has a housing 13a for the connector 31. The housing 13a houses the connector 31 such that the external terminals 31a of the connector 31 are exposed. The parts of the second cover member 13 other than the housing 13a and the housing 13a are integrally formed. In this embodiment, the housing 13a is made of nylon resin (second resin), but is not limited to this. As the material for the housing 13a, a material with low thermal conductivity is desirable, and in addition to nylon resin, polystyrene or the like can be used. Wiring 32 for transmitting detection signals from the encoder 20 is connected to the connector 31. The first resin and the second resin may be made of the same material or different materials.

[0036] Here, the thermal conductivity of the second cover member 13 made of nylon resin is lower than that of the aluminum flange 11 and the first cover member 12 made of aluminum. Therefore, even if heat is generated in the main body 40, that heat is less likely to be transferred to the first cover member 12 and the second cover member 13 via the flange 11. As a result, heat is less likely to accumulate in the housing space S described later, and the transfer of heat from the main body 40 to the encoder 20 is suppressed.

[0037] In Figure 3, the flange 11, the first cover member 12, and the second cover member 13 define the housing space S in which the encoder 20 is housed. The housing space S is a sealed space.

[0038] The magnetic shielding member 14 is fixed to the first cover member 12. In this embodiment, the magnetic shielding member 14 is made of iron (second metal), but is not limited to this. A magnetic material is preferable as the material for the magnetic shielding member 14, and in addition to iron, nickel or stainless steel can be used as the material. The magnetic shielding member 14 covers at least a part of the encoder 20. In this example, the magnetic shielding member 14 covers the top and side portions of the encoder 20. In this embodiment, the magnetic shielding member 14 is bottomed cylindrical, but is not limited to this. The magnetic shielding member 14 is not in contact with the flange 11. In this example, a predetermined gap exists between the tip 14e of the magnetic shielding member 14 and the flange 11.

[0039] The encoder 20 is an element that detects the rotational position and rotational speed of the shaft 41. The encoder 20 in this embodiment is a battery-powered multi-turn absolute encoder, but is not limited to this. The encoder 20 has a rotating plate 21 fixed to the shaft 41. The encoder 20 detects the rotational position and rotational speed of the shaft 41 by reading a predetermined pattern on the rotating plate 21.

[0040] The shaft 41 is a member that extends in the direction along the rotor's axis of rotation C (the left-right direction in the plane of the paper in Figure 3). The shaft 41 is fixed to the rotor and rotates together with the rotor. The shaft 41 is rotatably supported by the bearing 50. [Industrial applicability]

[0041] This disclosure can be used for encoder covers and motors. [Explanation of Symbols]

[0042] 1: Motor 10: Encoder cover 11: Flange 11a: Through hole 11b: Bolt hole 11c: Magnetic shielding plate 12: First cover member 12a: 1st through hole 13: Second cover member 13a: Enclosure 13b: 2nd through hole 13e: One end 13f: Other end 14: Magnetic shielding member 14e: Tip 20: Encoder 21: Rotating plate 31: Connector 31a: External terminal 32: Wiring 40: Main body 41: Shaft 42: Bracket 50: Bearings 60: Bolt S: Containment space

Claims

1. An encoder cover that covers an encoder for detecting the rotational position of a motor shaft, A flange for mounting the encoder, With respect to the encoder, a first cover member is provided on the opposite side of the flange and covers a part of the encoder, A second cover member connects the flange and the first cover member and covers a part of the encoder, A magnetic shielding member fixed to the first cover member and covering at least a portion of the encoder, Equipped with, The thermal conductivity of the second cover member is smaller than that of the flange and the first cover member. The encoder cover is made of a second metal and is not in contact with the flange.

2. The encoder cover according to claim 1, wherein the first cover member and the flange are each made of a conductive material.

3. The encoder cover according to claim 1 or 2, wherein the first cover member is made of a first metal.

4. The encoder cover according to claim 1 or 2, wherein the second cover member is made of the first resin.

5. The encoder cover according to claim 1 or 2, wherein the first cover member is fixed to the flange by conductive bolts.

6. The second cover member has a housing for the connector, The encoder cover according to claim 1 or 2, wherein the housing is made of a second resin.

7. The encoder cover according to claim 6, wherein the portion of the second cover member other than the housing and the housing are integrally formed.

8. An encoder cover according to claim 1 or 2, The encoder housed in the encoder cover, A main body having the shaft whose rotational position is detected by the encoder, A motor equipped with a motor.

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