Encoder cover

Abstract

To provide an encoder cover that can shield an encoder and prevent an increase in internal temperature due to heat from a motor body.SOLUTION: An encoder cover 40 is attached to a metal member 17 of a motor body 10 so as to cover an encoder 20 that detects positional information of a rotation shaft 12 of the motor body 10. The encoder cover 40 is formed through insert molding of a metal electromagnetic shielding shield member 45 into an insulating resin member 41, and the electromagnetic shielding shield member 45 is in contact with the metal member 17 with projections 46a, 46b therebetween.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an encoder cover attached to a metal member of a motor body so as to cover an encoder that detects position information of a rotating shaft of the motor body. [Background technology]

[0002] Generally, a servo motor includes a motor body with a rotating shaft and an encoder (rotary encoder) that detects position information (rotation angle and rotation position) of the rotating shaft. In this servo motor, an insulating encoder cover is attached to the motor body so as to cover the encoder to protect it from the outside. Here, optical encoders such as transmission and reflection types are generally used as the encoder, but it is desirable to shield the encoder to protect it from external noise and obtain a stable output.

[0003] 2. Description of the Related Art Conventionally, a rotary encoder disclosed in Patent Document 1, for example, is known as a shield for protecting an encoder from external noise and for obtaining a stable output.

[0004] The rotary encoder disclosed in Patent Document 1 includes a rotating shaft rotatably mounted on a base made of an insulating material, a rotating disk mounted on the rotating shaft and having a predetermined slit, a light-receiving element fixed to one side of the rotating disk via a fixing slit, a printed circuit board fixed to the other side of the rotating disk and having a light-emitting element and an electronic circuit unit, a case made of an insulating material attached to the base, and a case-side metal film formed on the inner surface of the case. The ground of the electronic circuit unit is connected to the case-side metal film, and the metal film shields the electronic circuit unit. The case-side metal film formed on the inner surface of the case is connected to the base-side metal film formed on the surface of the base, completely shielding the electronic circuit unit from the outside.

[0005] According to the rotary encoder disclosed in Patent Document 1, the metal film portion on the case body side can completely prevent external noise from entering the electronic circuit portion. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 62-277521 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the conventional rotary encoder disclosed in Patent Document 1 has the following problems. Specifically, in the rotary encoder disclosed in Patent Document 1, the case-side metal film formed on the inner surface of the case is cylindrical and has a bottomed shape so as to cover the entire inner surface of the case. The entire circumference of the tip of the case-side metal film is in contact with and connected to the entire circumference of the base-side metal film formed on the surface of the base. This results in a large contact area between the case-side metal film and the base-side metal film, and heat from the base side, which supports the rotating shaft of the motor body, is conducted from the entire circumference of the base-side metal film to the inside of the case. This results in a rapid temperature rise inside the case, potentially adversely affecting the rotating disk, light-receiving element, light-emitting element, and electronic circuitry that make up the rotary encoder inside the case.

[0008] Therefore, the present invention has been made to solve this conventional problem, and its purpose is to provide an encoder cover that can shield the encoder and suppress the internal temperature rise due to heat from the motor body. [Means for solving the problem]

[0009] In order to achieve the above object, one aspect of the present invention provides an encoder cover that is attached to a metal member of a motor body so as to cover an encoder that detects position information of the rotating shaft of the motor body, and is formed by insert-molding a metal electromagnetic shielding member into an insulating resin material, and the electromagnetic shielding member contacts the metal member via a protrusion. [Effects of the Invention]

[0010] According to the encoder cover of the present invention, it is possible to provide an encoder cover that can shield the encoder and can suppress an increase in the internal temperature due to heat from the motor main body side. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view of a servo motor provided with an encoder cover according to a first embodiment of the present invention, viewed obliquely from above and at the front. [Figure 2] FIG. 2 is a plan view of the servo motor shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 2 is an exploded perspective view of the servo motor shown in FIG. [Figure 5] 2 is an exploded perspective view showing a resin material and an electromagnetic shielding member that constitute the encoder cover shown in FIG. 1. FIG. [Figure 6] FIG. 2 is a bottom view of the encoder cover shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view taken along line BB in FIG. [Figure 8] FIG. 10 is a perspective view of a servo motor provided with an encoder cover according to a second embodiment of the present invention, as viewed obliquely from above the front. [Figure 9] FIG. 9 is a plan view of the servo motor shown in FIG. 8. [Figure 10] FIG. 10 is a cross-sectional view taken along line CC in FIG. [Figure 11] FIG. 9 is an exploded perspective view of the servo motor shown in FIG. 8. [Figure 12] 9 is an exploded perspective view showing a resin material and an electromagnetic shielding member that constitute the encoder cover shown in FIG. 8. FIG. [Figure 13] FIG. 9 is a bottom view of the encoder cover shown in FIG. 8. [Figure 14] FIG. 14 is a cross-sectional view taken along line DD in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are merely examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the materials, shapes, structures, arrangements, etc. of the components to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

[0013] It should be noted that the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratio of each layer, etc. may differ from the actual product. Therefore, the specific thickness and dimensions should be determined by taking into consideration the following explanation. Furthermore, it goes without saying that the drawings may contain portions in which the dimensional relationships and ratios differ from one another.

[0014] (First embodiment) A servo motor equipped with an encoder cover according to a first embodiment of the present invention is shown in FIGS. 1 to 4. FIG. The servo motor 1 shown in FIGS. 1 to 4 includes a motor body 10, an encoder 20, a sealing member 30, and an encoder cover 40.

[0015] The motor body 10 includes, within a motor frame 11, a rotating shaft 12, a rotor 13 fixed to the rotating shaft 12, a stator 14 arranged to cover the outer periphery of the rotor 13, and a metal member 17 attached to the upper end surface of the motor frame 11. The rotary shaft 12 is rotatably supported by a bearing 15 on the motor frame 11 at its lower end 12a (load side) and a bearing 16 on the metal member 17 at its upper end 12b (anti-load side). The metal member 17 is a substantially flat metal member for shielding the encoder 20, and is fixed to the upper end surface of the motor frame 11 by a plurality of fixing screws 18.

[0016] The encoder 20 detects position information (rotation angle and rotation position) of the rotating shaft 12 of the motor main body 10. The encoder 20 is a reflective optical encoder and includes an encoder disk 21 fixed to the upper end 12b of the rotating shaft 12 with disk fixing screws 24, and an encoder board 22 attached to a base plate 23 with board mounting screws 26. Multiple patterns are formed on the surface of the encoder disk 21. The encoder board 22 is provided with a light-emitting element (not shown) that irradiates the surface of the encoder disk 21, a light-receiving element (not shown) that receives light reflected by the pattern formed on the surface of the encoder disk 21, and an electronic circuit unit (not shown) that converts the reflected light received by the light-receiving element into an electrical signal to detect position information of the rotating shaft 12. The encoder board 22 is attached to the metal member 17 by attaching the base plate 23 to the metal member 17 with multiple mounting screws 25.

[0017] 3 and 4, the sealing member 30 is an annular body having a circular through-hole 31 therein through which the encoder 20 can be inserted, and is placed between the metal member 17 and a resin material 41 (described later) of the encoder cover 40 to seal the gap between the metal member 17 and the resin material 41 of the encoder cover 40. The sealing member 30 is formed with a plurality of mounting screw insertion holes 32 through which mounting screws 47 (described later) are inserted to attach the resin material 41 of the encoder 20 to the metal member 17.

[0018] The encoder cover 40 is attached to the metal member 17 of the motor body 10 so as to cover the encoder 20. The encoder cover 40 protects the encoder 20 from the outside. The encoder cover 40 includes an insulating resin material 41 attached to the metal member 17 so as to cover the encoder 20, and a metallic electromagnetic shielding member 45 insert-molded into the resin material 41.

[0019] 5 to 7, the resin material 41 is integrally molded to include an upper wall portion 41a, a left wall portion 41b extending downward from the left end of the upper wall portion 41a, a right wall portion 41c extending downward from the right end of the upper wall portion 41a, a front wall portion 41d extending downward from the front end of the upper wall portion 41a, and a rear wall portion 41e extending downward from the rear end of the upper wall portion 41a. A circular recess 42 is formed inside the resin material 41 by the upper wall portion 41a, the left wall portion 41b, the right wall portion 41c, the front wall portion 41d, and the rear wall portion 41e. As shown in FIG. 3, the resin material 41 is attached to the metal member 17 so as to place the encoder 20 in the recess 42 and cover the encoder 20. 4 to 6, two mounting screw holes 43 are formed in the resin material 41 near the left end of the front wall portion 41d and near the right end of the rear wall portion 41e, penetrating the resin material 41 in the vertical direction for attaching the resin material 41 to the metal member 17. The two mounting screw holes 43 are formed at positions 180° apart so as to face each other in the circumferential direction, as shown in FIG. 6. A mounting screw 47 is inserted into each mounting screw hole 43, and the resin material 41 is attached to the metal member 17 by the mounting screws 47. The resin material 41 is also provided with an electric wire outlet 44 for guiding electric wires (not shown) leading out from the encoder board 22 to the outside.

[0020] The electromagnetic shielding member 45 is formed by stamping and forming a metal plate. As shown in FIG. 5 , the electromagnetic shielding member 45 includes a circular upper plate portion 45a, a curved rear plate portion 45b extending downward by a predetermined width in the circumferential direction along the rear edge of the upper plate portion 45a, and a curved front plate portion 45c extending downward by a predetermined width in the circumferential direction along the front edge of the upper plate portion 45a. The upper plate portion 45a has a plurality of openings 45d. The openings 45d allow the resin material 41 to flow quickly to the inside of the electromagnetic shielding member 45 during molding and prevent the formation of unfilled portions of the resin material 41 inside the electromagnetic shielding member 45. A protrusion 46a protruding downward from the underside of the front plate portion 45c is formed near the left edge of the underside of the front plate portion 45c, and a protrusion 46b protruding downward from the underside of the rear plate portion 45b is formed near the right edge of the underside of the rear plate portion 45b.

[0021] As shown in FIG. 7, the electromagnetic shielding member 45 is insert-molded into the resin material 41 in a state where it is covered with the resin material 41 except for a part of the rear plate portion 45b. 6, the circumferential position of one of the protrusions 46a relative to the resin material 41 when the electromagnetic shielding member 45 is insert-molded into the resin material 41 is a position where the distance between the center C46a of the protrusion 46a and the center C43 of the mounting screw hole 43 provided in the front wall portion 41d of the resin material 41 is d1. Also, the circumferential position of the other of the protrusions 46b relative to the resin material 41 when the electromagnetic shielding member 45 is insert-molded into the resin material 41 is a position where the distance between the center C46b of the protrusion 46b and the center C43 of the mounting screw hole 43 provided in the rear wall portion 41e of the resin material 41 is d2.

[0022] As shown in FIG. 3, when the encoder cover 40 is attached to the metal member 17, the electromagnetic shielding member 45 contacts the metal member 17 via one protrusion 46a and the other protrusion 46b (only the other protrusion 46b is shown in FIG. 3) and is metal-grounded.

[0023] In this way, by metal-grounding the electromagnetic shielding member 45 to the metal member 17, the encoder 20 can be shielded from the outside, and the electromagnetic shielding member 45 and the metal member 17 can completely prevent external noise from entering the encoder 20.

[0024] Furthermore, when the encoder cover 40 is attached to the metal member 17, one protrusion 46a and the other protrusion 46b (only the other protrusion 46b is shown in Figure 3) are positioned inside the annular sealing member 30, as shown in Figure 3. As a result, the one projection 46a and the other projection 46b of the electromagnetic shielding member 45 that performs metal grounding are blocked from the outside air by the sealing member 30, thereby preventing deterioration thereof.

[0025] The resin material 41 is provided with an electric wire outlet 44 for leading out electric wires (not shown) leading out from the encoder board 22 to the outside.

[0026] Here, when the motor body 10 is driven with the encoder cover 40 attached to the metal member 17 of the motor body 10, heat generated on the motor body 10 side is transferred to the inside of the encoder cover 40 via the metal member 17 and the electromagnetic shielding member 45, causing the temperature inside the encoder cover 40 to rise. The rise in the temperature inside the encoder cover 40 also causes the temperature inside the encoder 20 to rise, which may have an adverse effect on the electronic circuitry, etc.

[0027] However, because the electromagnetic shielding member 45 is in contact with the metal member 17 via the protrusions 46a and 46b, the contact area with the metal member 17 is smaller than when the electromagnetic shielding member 45 is in contact with the metal member 17 over the entire periphery of the rear plate portion 45b and the front plate portion 45c. As a result, the amount of heat generated on the motor main body 10 side when transferred from the metal member 17 to the electromagnetic shielding member 45 is small, and it is possible to suppress a temperature rise inside the encoder cover 40 due to heat from the motor main body 10 side. This also suppresses a temperature rise inside the encoder 20, making it possible to avoid adverse effects on the electronic circuitry and the like.

[0028] As described above, the encoder cover 40 according to the first embodiment is formed by insert-molding the metallic electromagnetic shielding member 45 into the insulating resin material 41 attached to the metallic member 17 of the motor main body 10, and the electromagnetic shielding member 45 contacts the metallic member 17 via the protrusions 46a, 46b. This makes it possible to shield the encoder 20, and by reducing the contact area between the electromagnetic shielding member 45 and the metallic member 17, it is possible to suppress a temperature rise inside the encoder cover 40 due to heat from the motor main body 10.

[0029] Furthermore, according to the encoder cover 40 of the first embodiment, the protrusions 46a, 46b of the electromagnetic shielding member 45 are disposed inside the annular sealing member 30 that seals the gap between the resin material 41 and the metal member 17 when the resin material 41 is attached to the metal member 17. As a result, the protrusions 46a, 46b of the electromagnetic shielding member 45, which performs metal grounding, are blocked from outside air by the sealing member 30, thereby preventing their deterioration.

[0030] Furthermore, according to the encoder cover 40 according to the first embodiment, the electromagnetic shielding member 45 is insert-molded into the resin material 41 while being covered with the resin material 41. As a result, when heat from the motor main body 10 side is transferred to the electromagnetic shielding member 45 and then transferred from the electromagnetic shielding member 45 to the inside of the encoder cover 40, the heat-insulating effect of the resin material 41 reduces the amount of heat transferred to the inside of the encoder cover 40. Therefore, it is possible to further reduce the temperature rise inside the encoder cover 40 due to heat from the motor main body 10 side, and further reduce the temperature rise inside the encoder 20.

[0031] (Second embodiment) Next, an encoder cover according to a second embodiment of the present invention will be described with reference to Figs. 8 to 14. Fig. 8 is a perspective view of a servo motor equipped with an encoder cover according to the second embodiment of the present invention, viewed obliquely from above and in front. Fig. 9 is a plan view of the servo motor shown in Fig. 8. Fig. 10 is a cross-sectional view taken along line CC in Fig. 9. Fig. 11 is an exploded perspective view of the servo motor shown in Fig. 8. Fig. 12 is an exploded perspective view of the resin material and the electromagnetic shielding member that constitute the encoder cover shown in Fig. 8. Fig. 13 is a bottom view of the encoder cover shown in Fig. 8. Fig. 14 is a cross-sectional view taken along line DD in Fig. 13.

[0032] The servo motor 101 shown in FIGS. 8 to 11 includes a motor body 110, an encoder 120, a sealing member 130, and an encoder cover 140, similar to the servo motor 1 shown in FIGS. The motor body 110 includes, within a motor frame 111, a rotating shaft 112, a rotor 113 fixed to the rotating shaft 112, a stator 114 arranged to cover the outer periphery of the rotor 113, and a metal member 117 attached to the upper end surface of the motor frame 111.

[0033] The rotary shaft 112 is rotatably supported by a bearing 115 on the motor frame 111 at its lower end 112a (load side) and a bearing 116 on a metal member 117 at its upper end 112b (anti-load side). The metal member 117 is a substantially flat metal member for shielding the encoder 120, and is fixed to the upper end surface of the motor frame 111 by a plurality of fixing screws 118.

[0034] The encoder 120 detects position information (rotation angle and rotation position) of the rotating shaft 112 of the motor main body 110. The encoder 120 is a reflective optical encoder and includes an encoder disk 121 fixed to the upper end 112b of the rotating shaft 112 with a disk fixing screw 124, and an encoder board 122 attached to a base plate 123 with a board mounting screw 126. Multiple patterns are formed on the surface of the encoder disk 121. The encoder board 122 is provided with a light-emitting element (not shown) that irradiates the surface of the encoder disk 121, a light-receiving element (not shown) that receives light reflected by the pattern formed on the surface of the encoder disk 121, and an electronic circuit unit (not shown) that converts the reflected light received by the light-receiving element into an electrical signal to detect position information (rotation speed and rotation angle) of the rotating shaft 112. The encoder board 122 is attached to the metal member 117 by attaching the base plate 123 to the metal member 117 with multiple mounting screws 125.

[0035] 10 and 11, the sealing member 130 is composed of an annular O-ring, and is installed between the metal member 117 and the resin material 141 of the encoder cover 140, which will be described later, to seal the gap between the metal member 117 and the resin material 141 of the encoder cover 140.

[0036] The encoder cover 140 is attached to the metal member 117 of the motor body 110 so as to cover the encoder 120. The encoder cover 140 protects the encoder 120 from the outside.

[0037] The encoder cover 140 includes an insulating resin material 141 attached to the metal member 117 so as to cover the encoder 120, and a metallic electromagnetic shielding member 146 insert-molded into the resin material 141.

[0038] 12 to 14, the resin material 141 is integrally molded and includes a circular upper wall portion 141a, a cylindrical outer wall portion 141b extending downward from the outer peripheral edge of the upper wall portion 141a, and a mounting flange portion 143 provided at the lower end of the outer wall portion 141b. The mounting flange portion 143 includes a front flange portion 143a, a rear flange portion 143b, a left flange portion 143c, and a right flange portion 143d, which are formed so as to protrude outward from the outer wall portion 141b. Each of the front flange portion 143a, the rear flange portion 143b, the left flange portion 143c, and the right flange portion 143d is reinforced by a reinforcing rib 141c. The upper wall portion 141a, the outer wall portion 141b, and the mounting flange portion 143 form a circular recess 142 on the inside. As shown in FIG. 10 , the resin material 141 is attached to the metal member 117 so as to cover the encoder 120, with the encoder 120 disposed in the recess 142. As shown in FIGS. 11 to 13 , four mounting screw holes 144 are formed in the front flange portion 143a, the rear flange portion 143b, the left flange portion 143c, and the right flange portion 143d of the mounting flange portion 143, respectively, and extend vertically through the front flange portion 143a, the rear flange portion 143b, the left flange portion 143c, and the right flange portion 143d. The four mounting screw holes 144 are formed at equal intervals (90° intervals) in the circumferential direction, as shown in FIG. 13 . A mounting screw 148 is inserted into each mounting screw hole 144, and the resin material 141 is attached to the metal member 117 by the mounting screws 148. The resin material 141 is also provided with an electric wire outlet 145 for leading out electric wires (not shown) leading out from the encoder board 122 to the outside.

[0039] The electromagnetic shielding member 146 is formed by punching and bending a metal plate, and as shown in FIG. 12 , includes a circular upper plate portion 146a and a cylindrical outer plate portion 146b extending downward from the outer periphery of the upper plate portion 146a. The upper plate portion 146a is formed with a plurality of openings 146d. The formation of these openings 146d allows the resin material 141 to quickly flow to the inside of the electromagnetic shielding member 146 during molding and prevents the formation of unfilled portions of the resin material 141 inside the electromagnetic shielding member 146. The outer plate portion 146b is formed with an opening 146c for leading the electric wires leading from the encoder board 122 to the electric wire lead-out port 145. The lower surface of the outer plate portion 146b is provided with four protrusions 147a, 147b, 147c, and 147d that protrude downward from the lower surface. The four protrusions 147a, 147b, 147c, and 147d are arranged at equal intervals (90° intervals) in the circumferential direction.

[0040] As shown in FIG. 14, the electromagnetic shielding member 146 is insert-molded into the resin material 141 while being covered with the resin material 141.

[0041] The four protrusions 147a, 147b, 147c, and 147d formed when the electromagnetic shielding member 146 is insert-molded into the resin material 141 are located near the mounting screw holes 144 formed in the resin material 141 for attaching the resin material 141 to the metal member 117. Specifically, the four protrusions 147a, 147b, 147c, and 147d are circumferentially positioned relative to the resin material 141 when the electromagnetic shielding member 146 is insert-molded into the resin material 141, and are radially aligned with the mounting screw holes 144, 144, 144, and 144, as shown in Fig. 13. In other words, the center C147a of the protrusion 147a and the center C144 of the mounting screw hole 144 formed in the rear flange portion 143b are radially aligned. Furthermore, the center C147b of the protrusion 147b and the center C144 of the mounting screw hole 144 provided in the left flange portion 143c are aligned in the radial direction. Furthermore, the center C147c of the protrusion 147c and the center C144 of the mounting screw hole 144 provided in the front flange portion 143a are aligned in the radial direction. Furthermore, the center C147d of the protrusion 147d and the center C144 of the mounting screw hole 144 provided in the right flange portion 143d are aligned in the radial direction.

[0042] As shown in Figure 10, when the encoder cover 140 is attached to the metal member 117, the electromagnetic shielding member 146 comes into contact with the metal member 117 via four protrusions 147a, 147b, 147c, and 147d (only protrusion 147d is shown in Figure 10) and is metal-grounded.

[0043] In this way, by metal-grounding the electromagnetic shielding member 146 to the metal member 117, the encoder 120 can be shielded from the outside, and the electromagnetic shielding member 146 and the metal member 117 can completely prevent external noise from entering the encoder 120.

[0044] Furthermore, when the encoder cover 140 is attached to the metal member 117, the four protrusions 147a, 147b, 147c, and 147d (only the protrusion 147d is shown in FIG. 10) are positioned inside the annular sealing member 130, as shown in FIG.

[0045] As a result, the four projections 147a, 147b, 147c, and 147d of the electromagnetic shielding member 146 that perform metal grounding are blocked from the outside air by the sealing member 30, thereby preventing deterioration thereof.

[0046] Here, when the motor body 110 is driven with the encoder cover 140 attached to the metal member 117 of the motor body 110, heat generated on the motor body 110 side is transferred to the inside of the encoder cover 140 via the metal member 117 and the electromagnetic shielding member 146, causing the temperature inside the encoder cover 140 to rise. The rise in the temperature inside the encoder cover 140 also causes the temperature inside the encoder 120 to rise, which may have an adverse effect on the electronic circuitry and the like.

[0047] However, because the electromagnetic shielding member 146 is in contact with the metal member 117 via the protrusions 147a, 147b, 147c, and 147d, the contact area with the metal member 117 is smaller than when the entire outer plate portion 146b of the electromagnetic shielding member 146 is in contact with the metal member 117. As a result, the amount of heat generated on the motor main body 110 side when transferred from the metal member 117 to the electromagnetic shielding member 146 is small, making it possible to suppress a temperature rise inside the encoder cover 140 due to heat from the motor main body 110 side. This also suppresses a temperature rise inside the encoder 120, making it possible to avoid adverse effects on electronic circuits, etc.

[0048] As described above, the encoder cover 140 according to the second embodiment is formed by insert-molding the metallic electromagnetic shielding member 146 into the insulating resin material 141 attached to the metallic member 117 of the motor main body 110, and the electromagnetic shielding member 146 contacts the metallic member 117 via the protrusions 147a, 147b, 147c, and 147d. This makes it possible to shield the encoder 120, and by reducing the contact area between the electromagnetic shielding member 146 and the metallic member 117, it is possible to suppress a temperature rise inside the encoder cover 140 due to heat from the motor main body 110.

[0049] Furthermore, according to the encoder cover 140 of the second embodiment, the protrusions 147a, 147b, 147c, and 147d of the electromagnetic shielding member 146 are provided near the mounting screw holes 144, 144, 144, and 144 provided in the resin material 141 for attaching the resin material 141 to the metal member 117.

[0050] The encoder cover 140 is attached to the metal member 117 by inserting mounting screws 148 into mounting screw holes 144 provided in the resin material 141. At this time, a large tightening force acts near each mounting screw hole 144. For this reason, by providing the protrusions 147a, 147b, 147c, and 147d of the electromagnetic shielding member 146 near the mounting screw holes 144, the protrusions 147a, 147b, 147c, and 147d of the electromagnetic shielding member 146 come into stable contact with the metal member 117 with large force, thereby enabling stable metal grounding with large force.

[0051] Furthermore, according to the encoder cover 140 of the second embodiment, the protrusions 147a, 147b, 147c, and 147d of the electromagnetic shielding member 146 are arranged inside the annular sealing member 130 that seals the gap between the resin material 141 and the metal member 117 when the resin material 141 is attached to the metal member 117. As a result, the protrusions 147a, 147b, 147c, and 147d of the electromagnetic shielding member 146 that perform metal grounding are blocked from outside air by the sealing member 130, thereby preventing their deterioration.

[0052] Furthermore, according to the encoder cover 140 according to the second embodiment, the electromagnetic shielding member 146 is insert-molded into the resin material 141 while being covered with the resin material 141. As a result, when heat from the motor main body 110 side is transferred to the electromagnetic shielding member 146 and then transferred from the electromagnetic shielding member 146 to the inside of the encoder cover 140, the heat insulating effect of the resin material 141 reduces the amount of heat transferred to the inside of the encoder cover 140. Therefore, it is possible to further reduce the temperature rise inside the encoder cover 140 due to heat from the motor main body 110 side, and further reduce the temperature rise inside the encoder 120.

[0053] Furthermore, according to the encoder cover 140 of the second embodiment, the electromagnetic shielding member 146 has four protrusions 147a, 147b, 147c, and 147d that are evenly spaced (90° apart) in the circumferential direction, four mounting screw holes 144, 144, 144, and 144 that are evenly spaced (90° apart) in the circumferential direction, and the circumferential installation positions of each of the protrusions 147a, 147b, 147c, and 147d are aligned radially with the mounting screw holes 144, 144, 144, and 144.

[0054] This allows the four protrusions 147a, 147b, 147c, and 147d of the electromagnetic shielding member 146 to stably contact the metal member 117 with a large, uniform force in the circumferential direction, thereby enabling stable metal grounding with a large, uniform force in the circumferential direction. Although the embodiment of the present invention has been described above, the present invention is not limited to this and various modifications and improvements can be made.

[0055] For example, in the first embodiment, the electromagnetic shielding member 45 contacts the metal member 17 via two protrusions 46a and 46b, and in the second embodiment, the electromagnetic shielding member 146 contacts the metal member 117 via four protrusions 147a, 147b, 147c, and 147d, but the number of protrusions contacting the metal member 117 may be other than two or four.

[0056] Furthermore, when two protrusions 46a, 46b are provided in the first embodiment, when four protrusions 147a, 147b, 147c, 147d are provided in the second embodiment, or when any other number of protrusions are provided, the protrusions do not necessarily have to be provided at equal intervals in the circumferential direction. Furthermore, when two protrusions 46a, 46b are provided as in the first embodiment, or when a number other than four protrusions is provided, it is preferable that each protrusion be provided near a mounting screw hole provided in the insulating material.

[0057] Furthermore, when a number other than four protrusions are provided, the circumferential installation positions of the protrusions may be aligned radially with the mounting screw holes. Furthermore, when the electromagnetic shielding members 45, 146 are insert-molded into the resin materials 41, 141, the electromagnetic shielding members 45, 146 do not necessarily need to be insert-molded into the resin materials 41, 141 in a state where they are covered with the resin materials 41, 141. [Explanation of symbols]

[0058] 1 servo motor 10 Motor body 11 Motor frame 12 Rotation axis 12a Bottom end 12b Top edge 13 Rotor 14 Stator 15,16 Bearings 17 Metal parts 18 Fixing screw 20 Encoder 21 Encoder disc 22 Encoder board 23 Base Plate 24 Disc fixing screw 25 Mounting screws 26 Board mounting screws 30 Sealing member 31 Through hole 32 Mounting screw insertion hole 40 Encoder cover 41 Resin material 41a Upper wall part 41b Left wall section 41c Right wall section 41d Front wall 41e Rear wall 42 recess 43 Mounting screw holes 44 Wire outlet 45 Electromagnetic shielding materials 45a Upper plate 45b Rear plate part 45c Front plate part 45d aperture 46a One protrusion 46b Other protrusion 47 Mounting screw 101 Servo motor 110 Motor body 111 Motor Frame 112 Rotation axis 112a bottom end 112b top end 113 Rotor 114 Stator 115,116 Bearings 117 Metal parts 118 Fixing screw 120 Encoder 121 Encoder disc 122 Encoder board 123 base plate 124 Disc fixing screw 125 Mounting screw 126 PCB mounting screw 130 Sealing member 140 Encoder cover 141 Resin material 141a Upper wall 141b Exterior wall 141c Reinforcement rib 142 recess 143 Mounting flange 143a Front flange 143b Rear flange 143c Left flange 143d Right flange 144 Mounting screw hole 145 Wire outlet 146 Electromagnetic shielding materials 146a Upper plate 146b Outer panel 147a,147b,147c,147d protrusion 148 Mounting screw

Claims

1. An encoder cover attached to a metal member of a motor body so as to cover an encoder that detects position information of a rotation shaft of the motor body, 1. An encoder cover comprising an insulating resin material and a metallic electromagnetic shielding member insert-molded therein, the metallic member being in contact with the electromagnetic shielding member via a protrusion.

2. 2. The encoder cover according to claim 1, wherein the protrusion of the electromagnetic shielding member is provided near a mounting screw hole provided in the resin material for mounting the resin material to the metal member.

3. The encoder cover according to claim 1 or 2, characterized in that the protrusion of the electromagnetic shielding member is arranged inside a sealing member that seals the gap between the resin material and the metal member when the resin material is attached to the metal member.

4. 2. The encoder cover according to claim 1, wherein the electromagnetic shielding member is insert-molded into the resin material while being covered with the resin material.

5. 3. The encoder cover according to claim 2, wherein the electromagnetic shielding member has four protrusions arranged at equal intervals in the circumferential direction, four mounting screw holes arranged at equal intervals in the circumferential direction, and the circumferential installation position of each protrusion is aligned radially with the corresponding mounting screw hole.

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