Cooling structure of servo motors and robots

Abstract

A cooling structure for a servo motor is disclosed for cooling a servo motor fixed to a robot structure. The servo motor includes a drive unit, an encoder, and a heat-conducting component. The drive unit includes a rotor and a stator. The encoder detects the rotation of the rotor. The heat-conducting component contacts and is fixed to the outer surface of the stator and the surface of the robot structure to conduct heat energy from the stator to the robot structure. The heat-conducting component does not contact the outer surface of the encoder.

Description

Technical Field

[0001] This application relates to a cooling structure for a servo motor. Prior Technology

[0002] A known robot, in order to cool the servo motor that generates heat during operation, has a cooling structure disposed between the servo motor and the motor housing (for example, see Patent Document 1). The cooling structure is, for example, a heat conductor made of a metal such as aluminum, to form a conduction path that transfers heat energy from the servo motor to the motor housing. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Invention Patent No. 2014-46398 Publication Specification Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] To maintain performance and lifespan, servo motors have upper limits on their operating temperature. These upper limits are not uniform across the entire servo motor; for example, the stator and rotor have higher upper limits, while electronic circuits such as encoders typically have lower upper limits.

[0006] When the stator and encoder of a servo motor are connected to the housing via the same cooling structure, the cooling structure is heated by heat dissipation from the stator, which hinders the heat dissipation of the encoder to the cooling structure. Therefore, in order to prevent the heat from being blocked by heat dissipation from the rotor and stator, it is desirable to effectively dissipate the heat from the encoder, which has a low upper limit of operating temperature. [Solutions]

[0007] In summary, according to one embodiment, a cooling structure for a servo motor is provided to cool a servo motor fixed to a robot structure. The servo motor includes a drive unit, an encoder, and a heat-conducting component. The drive unit includes a rotor and a stator. The encoder detects the rotation of the rotor. The heat-conducting component contacts and is fixed to the outer surface of the stator and the surface of the robot structure to conduct heat energy from the stator to the robot structure. The heat-conducting component does not contact the outer surface of the encoder. Simple Explanation of the Diagram

[0008] [Figure 1] is a partial longitudinal sectional view of a robot according to an embodiment. [Figure 2] is an exploded perspective view of the cooling structure of a servo motor in the robot of Figure 1 according to an embodiment. [Figure 3] is a perspective view of the assembled state of the cooling structure of the servo motor in Figure 2. [Figure 4] is a longitudinal cross-sectional view illustrating the heat flow in the cooling structure of the servo motor in Figure 2. Implementation

[0009] Regarding the cooling structure 1 of the servo motor 10 and the robot 100 of one embodiment of this application, please refer to the following description and illustrations. The robot 100 of this embodiment, for example, is a vertical multi-joint robot mounted on the ground F.

[0010] The cooling structure 1 of the servo motor 10 in this embodiment is, for example, a structure that cools the servo motor 10 of the drive mechanism 130 that rotates about a vertical axis to drive the rotating arm 120 relative to the base 110 fixed to the ground F. As shown in FIG1, the drive mechanism 130 includes a base 110, a rotating base (robot structure) 132 supported rotatably about a vertical axis above the base 110, a reducer 133 provided between the base 110 and the rotating base 132, and a servo motor 10 fixed to the rotating base 132. The rotating arm 120 is also fixed to the rotating base 132.

[0011] The servo motor 10 includes a shaft 11, a drive unit 12 for rotating and driving the shaft 11, and an encoder 13 for detecting the rotation of the shaft 11. As shown in FIG2, the drive unit 12 includes a four-cornered cylindrical stator 14 and a rotor (not shown) rotatably supported inside the stator 14 about the central axis of the stator 14. Furthermore, the rotor is fixed to the shaft 11. The shaft 11 protrudes from a mounting surface 10a provided on one end face in the direction of the central axis of the stator 14.

[0012] The encoder 13 includes a box-shaped housing 15, which is fixed to an end face opposite to the mounting surface 10a via a stator 14. The encoder 13 also includes a rotation detection mechanism (not shown) and electronic circuitry (not shown) housed within the housing 15. The housing 15 can be made of any material.

[0013] The servo motor 10 has its shaft 11 passing through a through hole 132a in the rotary seat 132 in a vertical direction, and the gear 16 fixed to the front end of the shaft 11 meshes with the input gear 134 of the reducer 133. The servo motor 10 is fixed to the rotary seat 132 by means of bolts 17, which tightly connect the mounting surface 10a to the seat surface 135 formed by machining.

[0014] As shown in Figure 2, the cooling structure 1 of the servo motor 10 in this embodiment includes four flat heat-conducting components (flat components) 2, each heat-conducting component 2 being respectively and closely connected to the four sides of the stator 14. Each heat-conducting component 2 includes a motor contact portion 3 covering the side (outer surface) of the stator 14 and being closely connected to the side, and a fixing portion 4 for fixing the heat-conducting component 2 to the seat surface 135 on the rotating base 132.

[0015] The heat-conducting component 2 is made of a material with high thermal conductivity, for example, it is made of a metal such as aluminum alloy. The heat-conducting component 2 can also be made of any material. The fixing part 4 is bent perpendicularly to the motor contact part 3 and includes a plurality of through holes 4a extending along the thickness direction of the plate. The heat-conducting component 2 is fastened to the rotating base 132 by bolts 136 passing through the through holes 4a of the fixing part 4 and screw holes 137 on the seat surface 135 of the rotating base 132, so as to be tightly fixed to the rotating base 132.

[0016] As shown in Figure 3, the heat-conducting component 2 is in close contact with each side of the stator 14 via the motor contact portion 3, and forms a heat conduction path for dissipating the heat generated by the stator 14 by connecting the fixing portion 4 to the seat surface 135 of the rotating base 132. In this embodiment, the motor contact portion 3 of each heat-conducting component 2 is only in close contact with each side of the stator 14 and is positioned in a position that does not contact the outer surface of the housing 15 of the encoder 13. The heat-conducting component 2 located on the side where the connector is located has a shorter motor contact portion 3 than the heat-conducting component 2 located on the other side to avoid contact with the connector.

[0017] Please refer to the following description for the effect of the cooling structure 1 of the servo motor 10 in this embodiment. As shown in FIG4, according to the cooling structure 1 of the servo motor 10 in this embodiment, when the operation of the servo motor 10 causes the drive part 12, which includes the rotor and the stator 14, to heat up, a portion of the heat energy of the drive part 12 is conducted to the rotating seat 132 via the mounting surface 10a which is closely connected to the seat surface 135.

[0018] Furthermore, since the four sides of the stator 14 are respectively connected to the motor contact portion 3 of the heat-conducting component 2, another part of the heat energy of the drive portion 12 will be conducted to the motor contact portion 3. The heat energy conducted to the flat motor contact portion 3 is conducted downward through the motor contact portion 3 and then conducted to the rotary seat 132 through the fixing portion 4 which is connected to the seat surface 135 of the rotary seat 132.

[0019] Due to its large heat capacity and the high heat transfer rate of the stator 14 and the heat-conducting component 2, the heat generated in the drive unit 12 can be smoothly conducted to the rotary base 132. As a result, the stator 14 is effectively cooled, and the heat flowing from the stator 14 to the encoder 13 fixed to the stator 14 is effectively reduced.

[0020] Since encoder 13 only contacts stator 14, when stator 14 becomes hotter than encoder 13, the heat from encoder 13 will primarily be released through heat conduction towards the surrounding air. In other words, because encoder 13 does not contact the heat-conducting component 2 used for heat dissipation from stator 14, the heat dissipation path from encoder 13 is separate from the heat dissipation path from stator 14. Therefore, even if heat dissipation from stator 14 causes the temperature of heat-conducting component 2 to rise, it will not hinder heat dissipation from encoder 13.

[0021] Next, by effectively cooling the stator 14 through the heat-conducting component 2, the heat input from the stator 14 to the encoder 13 can be reduced, and the encoder 13 can be effectively cooled even by simply releasing heat to the surrounding air. Although the upper limit of the operating temperature of the encoder 13 is lower than that of the stator 14, an appropriate operating temperature can be maintained because heat dissipation from the stator 14 can be prevented from flowing into the encoder 13 through the heat-conducting component 2.

[0022] Furthermore, when the stator 14 is effectively cooled, causing the encoder 13 to become hotter than the stator 14, a portion of the heat generated in the encoder 13 will be discharged to the rotary seat 132 via the cooled stator 14. In this way, the encoder 13 can be effectively cooled.

[0023] Furthermore, as described above, according to this embodiment, the heat energy of the stator 14 decreases via the heat-conducting member 2 and is discharged to the rotating seat 132 located below the stator 14. Therefore, the heat released from the stator 14 to the surrounding air is reduced.

[0024] Since the encoder 13 is located above the stator 14, by dissipating the heat of the stator 14 downwards, the temperature rise of the air around the encoder 13 can be effectively suppressed. In this way, the temperature difference between the encoder 13 and the surrounding air can be maintained, which has the advantage of effectively releasing heat from the encoder 13 to the surrounding air.

[0025] Furthermore, according to the cooling structure 1 of the servo motor 10 in this embodiment, since the flat heat-conducting component 2 is closely attached to the side of the servo motor 10, it is not necessary to ensure a large installation space around the servo motor 10, thus saving space. In addition, the cooling structure 1 can be externally assembled using a simple fixing method; that is, the flat heat-conducting component 2 is closely attached to the side of the servo motor 10 from the outside and fixed to the seat surface 135 of the rotating base 132 by bolts 136. Thus, the design of the cooling structure 1 can be carried out after the design of the main mechanism is completed, which is beneficial for development and design.

[0026] Furthermore, as a robot 100 including the cooling structure 1 of the servo motor 10 in this embodiment, a multi-joint robot is exemplified. The structure of the robot 100 shown in this embodiment and figures is merely an example and is not limited thereto. Although the rotary base 132 is exemplified as the robot structure, any other component with a large heat capacity can be used to assemble the servo motor 10.

[0027] Furthermore, while an L-shaped bent flat plate is used as an example of the heat-conducting component 2, the shape of the heat-conducting component 2 can correspond to any shape of the seat surface 135 of the rotating base 132 of the robot structure that serves as the fixed target. In addition, although the heat-conducting component 2 is in close contact with all four sides of the stator 14 of the servo motor 10, it is also possible for it to be in close contact with one or more sides.

[0028] Furthermore, to improve the adhesion between the outer surface of the stator 14 and the seat surface 135 of the rotating base 132 and the heat-conducting component 2, a filler material such as thermally conductive gel or thermally conductive sheet can be sandwiched between the heat-conducting component 2 and the stator 14 and / or the rotating base 132. This reduces the contact thermal resistance for heat conduction from the outer surface of the stator 14 to the heat-conducting component 2 and from the heat-conducting component 2 to the rotating base 132, resulting in smoother heat dissipation.

[0029] Furthermore, in this embodiment, the heat energy of the stator 14 moves away from the encoder 13 through the heat-conducting component 2. When the heat-conducting component 2 becomes hot, the heat released from the heat-conducting component 2 to the surrounding air will increase during the heat conduction process.

[0030] Therefore, the outer surface of the heat-conducting component 2 can be covered with heat-insulating material or coating that reduces heat loss from the heat-conducting component 2 to the surrounding air. In this way, the heat loss from the heat-conducting component 2 to the atmosphere can be reduced, and the temperature rise of the air around the encoder 13 can be reduced.

[0031] Regarding the servo motor 10, although the encoder 13 is shown as being located on the upper part of the drive unit 12, the servo motor 10 can be arranged in any directional relationship. On the other hand, the cooling mechanism 1 of this embodiment has the following advantages when the servo motor 10 is arranged in the example directional relationship. That is, when there is no cooling mechanism 1, after heat is released from the stator 14 to the surrounding air, the temperature of the air around the upper encoder 13 rises due to air expansion. However, with the cooling structure 1 of this embodiment, the temperature difference between the encoder 13 and the surrounding air can be maintained by suppressing the heat release from the stator 14 to the surrounding air.

[0032] Furthermore, since the encoder 13 primarily dissipates heat by releasing it into the surrounding air, methods to promote heat dissipation include, for example, providing fins on the encoder 13's housing 15, or using a fan to circulate cooling air around the encoder 13. Additionally, a heat-conducting component for cooling the encoder 13 can be provided independently of the heat-conducting component 2 used to cool the stator 14. Furthermore, a protective cover can be used to separate the space where the encoder 13 is located from the space where the stator 14 is located.

[0033] 1: Cooling structure 2: Thermal conductive components 3: Motor contact part 4: Fixing part 4a: Through hole 10: Servo Motor 10a: Mounting surface 11: Shaft 12: Drive Unit 13: Encoder 14: Stator 15: Casing 16: Gear 17: Bolts 100: Robot 110: Base 120: Rotating Arm 130: Drive mechanism 132: Rotary seat 132a: Through hole 133: Gearbox 134: Input Gear 135: Seat surface 136: Bolt 137: Screw hole F: Bed surface

Claims

1. A cooling structure for a servo motor, used to cool a servo motor fixed to a robot structure; the servo motor includes: A drive unit, including a rotor and a stator; an encoder for detecting the rotation of the rotor; A heat-conducting component is provided, which contacts and is fixed to the outer surface of the stator and the surface of the robot structure to conduct the heat energy of the stator to the robot structure; wherein the heat-conducting component does not contact the outer surface of the encoder; wherein the servo motor is fixed to the robot structure with the encoder positioned above the stator; wherein the heat-conducting component conducts the heat of the stator downwards.

2. The cooling structure for the servo motor as described in claim 1, wherein, The heat-conducting component covers the outer surface of the stator and is located in a position that does not cover the outer surface of the encoder.

3. The cooling structure for the servo motor as described in claim 1, wherein, The thermally conductive component includes an insulating material to limit the heat dissipation of the component to the surrounding air.

4. The cooling structure for the servo motor as described in claim 1 or 2, wherein, The heat-conducting component includes a flat plate material that is in close contact with the outer surface of the stator and the surface of the robot structure.

5. The cooling structure for the servo motor as described in claim 4, wherein, The thermally conductive component includes a filler material to increase the tightness of the contact between the plate material and the outer surface of the stator, or between the plate material and the surface of the robot structure.

6. The cooling structure for the servo motor as described in claim 1 or 2, wherein, The heat-conducting components are respectively in close contact with two or more outer surfaces of the stator.

7. A robot including a cooling structure for a servo motor as described in claim 1 or 2.

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