Actuator

Abstract

An actuator 10 includes a motor 14 having a motor body 12 for generating a rotating magnetic field, and a reducer 16 for decelerating rotation output from the motor body 12. The actuator also comprises a motor casing 24 that accommodates the motor body 12, and a first casing 70 that is adjacent to the motor casing 24 in an axial direction. The motor casing 24 and the first casing 70 are fastened in a radial direction by a first fastening member 74A.

Description

Actuator

[0001] The present disclosure relates to actuators.

[0002] Patent Document 1 discloses an actuator including a motor having a motor body that generates a rotating magnetic field and a reducer that reduces the rotation output from the motor body. This actuator includes a motor casing that houses the motor body and a first casing that is adjacent to the motor casing in the axial direction.

[0003] Japanese Patent Application Laid-Open No. 2021-097430

[0004] The motor casing and the first casing in Patent Document 1 are fastened in the axial direction by a fastening member. After studying the technology disclosed in Patent Document 1, the inventors of the present application recognized that there was room for improvement in terms of making the actuator lighter.

[0005] One of the objects of the present disclosure is to provide an actuator that is advantageous in terms of weight reduction.

[0006] The actuator of the present disclosure is an actuator comprising a motor having a motor body that generates a rotating magnetic field, and a reducer that decelerates the rotation output from the motor body, and further comprising a motor casing that houses the motor body, and a first casing that is axially adjacent to the motor casing, and the motor casing and first casing are radially fastened together by a first fastening member.

[0007] The present disclosure is advantageous in reducing the weight of the actuator.

[0008] Fig. 2 is a perspective view of an actuator of an embodiment. Fig. 3 is a side cross-sectional view showing a part of the actuator of an embodiment. Fig. 4 is an enlarged view showing a part of Fig. 2. Fig. 5 is another enlarged view showing a part of Fig. 2. Fig. 6 is a side cross-sectional view showing a part of an actuator of a reference embodiment.

[0009] Hereinafter, an embodiment for implementing the actuator of the present disclosure will be described. The same or equivalent elements will be given the same reference numerals, and duplicate explanations will be omitted. In each drawing, for the sake of convenience, components will be omitted, enlarged, or reduced as appropriate. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0010] See Figures 1 and 2. The actuator 10 is capable of driving a driven device (not shown) by outputting rotation. The driven device is, for example, at least a part of various machines such as (1) industrial machines such as machine tools and construction machines, (2) robots such as industrial robots and service robots, (3) transportation equipment such as conveyors, and (4) vehicles. The actuator 10 is an integrated actuator in which a reducer casing 34 and a motor casing 24 (described later) are integrated together.

[0011] The actuator 10 includes a motor 14 having a motor main body 12 that generates a rotating magnetic field, and a reducer 16 that decelerates the rotation output from the motor main body 12. The actuator 10 also optionally includes a counter-load side casing 18 that is disposed on the counter-load side of a motor casing 24 of the motor 14, and at least one accessory device 20 housed in the counter-load side casing 18. Hereinafter, the direction along the rotation center line La of the motor shaft 22 of the motor 14 will be simply referred to as the axial direction, and the radial and circumferential directions of a circle centered on the rotation center line La will be simply referred to as the radial and circumferential directions. The side of the motor 14 toward the reducer 16 in the axial direction (the left side of the paper in FIG. 2 ) will be referred to as the load side, and the opposite axial side (the right side of the paper in FIG. 2 ) will be referred to as the counter-load side.

[0012] 2, the motor 14 includes, in addition to the motor body 12, a motor shaft 22 that rotates due to the rotating magnetic field generated by the motor body 12, and a motor casing 24 that houses the motor body 12.

[0013] The motor main body 12 includes a motor rotor 26 and a stator 28 that cooperates with the motor rotor 26 to generate a rotating magnetic field. The motor rotor 26 is provided to be rotatable integrally with the motor shaft 22, for example, by interference fit, adhesive bonding, etc. The type of motor rotor 26 is not particularly limited, and may be, for example, a permanent magnet rotor, a squirrel-cage rotor, a wound rotor, a coreless rotor, etc. The stator 28 is disposed on the inner periphery of the motor casing 24 and fixed to the motor casing 24 by interference fit, adhesive bonding, etc. The type of stator 28 is not particularly limited, and may be, for example, a permanent magnet stator, a wound stator, a coreless stator, etc.

[0014] The motor casing 24 accommodates the motor shaft 22 and the like in addition to the motor main body 12. The motor casing 24 in this embodiment is made up of a single member, but may be made up of multiple members.

[0015] The speed reducer 16 includes an input shaft 30 to which rotation output from the motor main body 12 is input via the motor shaft 22, a speed reduction mechanism 32 that reduces the rotation of the input shaft 30, a speed reducer casing 34 that houses at least a portion of the speed reduction mechanism 32, and a load-side cover 36 that is disposed on the load side of the speed reduction mechanism 32. The speed reduction mechanism 32 in this embodiment includes an external gear 38 and an internal gear 40 that mesh with each other. The speed reduction mechanism 32 in this embodiment is an eccentric oscillating speed reduction mechanism that rotates one of the external gear 38 and the internal gear 40 by oscillating the external gear 38 with an eccentric body 42, and extracts the rotation component using an output member 44. The output member 44 extracts the rotation reduced by the speed reduction mechanism 32 and outputs it to the outside. The output member 44 in this embodiment is formed by the load-side cover 36.

[0016] The input shaft 30 of this embodiment is provided so as to be rotatable integrally with the motor shaft 22, and constitutes a shaft body 46 integral with the motor shaft 22. The input shaft 30 of this embodiment includes at least one eccentric body 42 (two in this embodiment).

[0017] The external gear 38 of the reduction mechanism 32 in this embodiment is provided corresponding to the eccentric body 42 and is supported by the corresponding eccentric body 42 via an eccentric bearing 48. In this embodiment, the internal gear 40 of the reduction mechanism 32 is provided on the inner periphery of the reducer casing 34. A pin 50 that penetrates the external gear 38 protrudes from the load side cover 36 in this embodiment. The pin 50 directly or indirectly abuts against the external gear 38, enabling the rotation component of the external gear 38 and the load side cover 36 to be synchronized.

[0018] The reducer casing 34 is disposed on the load side relative to the motor casing 24. The reducer casing 34 accommodates at least a portion of the reduction mechanism 32 (here, the external gear 38), as well as the input shaft 30, the load-side cover 36, a main bearing 58 (described later), and the like. In this embodiment, the reducer casing 34 is composed of multiple reducer casing members 52A, 52B, but may be composed of a single member. The multiple reducer casing members 52A, 52B have a shape obtained by dividing the reducer casing 34 in the axial direction. The multiple reducer casing members 52A, 52B include a first reducer casing member 52A and a second reducer casing member 52B that is located closer to the load side than the first reducer casing member 52A. In this embodiment, an example is shown in which there are two reducer casing members 52A, 52B, but the number is not particularly limited and may be three or more.

[0019] In this embodiment, the load side cover 36 is composed of multiple load side cover members 54A, 54B connected by screws or the like (not shown), but may be composed of a single member. The multiple load side cover members 54A, 54B include a first load side cover member 54A and a second load side cover member 54B disposed on the load side of the first load side cover member 54A. A support bearing 56 supporting the shaft body 46 is disposed between the load side cover 36 and the input shaft 30. A main bearing 58 supporting the output member 44 is disposed between the reducer casing 34 and the load side cover 36.

[0020] The counter-load side casing 18 is disposed on the counter-load side relative to the motor casing 24. In this embodiment, the counter-load side casing 18 is composed of multiple counter-load side casing members 60A, 60B, but may also be composed of a single member. The multiple counter-load side casing members 60A, 60B have a shape obtained by dividing the counter-load side casing 18 in the axial direction. The counter-load side casing 18 in this embodiment includes a first counter-load side casing member 60A and a second counter-load side casing member 60B located on the counter-load side of the first counter-load side casing 18. While this embodiment illustrates an example in which there are two counter-load side casing members 60A, 60B, the number is not particularly limited and may be three or more. The counter-load side casing 18 in this embodiment includes a counter-load side cover portion 18a that covers the accessory device 20 from the counter-load side.

[0021] The accessory device 20 is attached to the actuator 10 separately from the motor 14 and the reducer 16. The accessory device 20 in this embodiment is a rotation detector that detects the rotation of a rotating body used in the actuator 10. Here, the rotating body is described using the shaft 46 as an example, but it may also be the output member 44. Specific examples of the accessory device 20 are not limited to rotation detectors and may include a brake device that brakes the rotating body, a motor driver that controls the motor main body 12, etc. Furthermore, multiple types of accessory devices 20 may be housed within the anti-load side casing 18. The accessory device 20 as a rotation detector is described using an encoder as an example, but the specific example is not particularly limited and may also be a resolver, etc. The accessory device 20 includes a detected part 20a fixed to the rotating body via a circuit board 62 or the like, and a detecting part 20b fixed to the anti-load side casing 18 via a circuit board 64 or the like. The detected part 20a is a scale such as an optical scale or a magnetic scale, and the detecting part 20b is a sensor such as an optical sensor or a magnetic sensor. The detecting unit 20b detects the rotation of the rotating body by detecting a change in a predetermined physical quantity (magnetic field, light amount, etc.) when the detected unit 20a rotates together with the rotating body. The detected unit 20a may be fixed directly to the rotating body without using a circuit board 62 or the like.

[0022] The above-described actuator 10 includes a first casing 70 axially adjacent to the motor casing 24, and a second casing 72 axially adjacent to the motor casing 24 on the axially opposite side of the first casing 70 with respect to the motor casing 24. One of the first casing 70 and the second casing 72 is the reducer casing 34, and the other is the anti-load side casing 18. In this embodiment, the first casing 70 is the reducer casing 34, and the second casing 72 is the anti-load side casing 18.

[0023] A motor accommodating space 24a that accommodates the motor main body 12 is formed inside the motor casing 24. A first accommodating space 70a that accommodates at least one component that will be a constituent part of the actuator 10 is formed inside the first casing 70. A second accommodating space 72a that accommodates at least one component that will be a constituent part of the actuator 10 is formed inside the second casing 72. The components accommodated in the first casing 70 that becomes the reducer casing 34 include at least a part of the reduction mechanism 32 (here, the external gear 38), the input shaft 30, the load side cover 36, the main bearing 58, etc. The components accommodated in the second casing 72 that becomes the anti-load side casing 18 include the accessory device 20, etc.

[0024] The motor casing 24 and the first casing 70 are fastened radially by at least one first fastening member 74A. The motor casing 24 and the second casing 72 are fastened radially by at least one second fastening member 74B. Two axially adjacent anti-load side casing members 60A, 60B are fastened radially by at least one third fastening member 74C. Two axially adjacent reducer casing members 52A, 52B are fastened radially by at least one fourth fastening member 74D. Here, "fastening radially" means connecting radially aligned locations of multiple fastened elements using fastening members 74A to 74D that have radially extending shaft portions. Fastening in the radial direction using fastening members in this manner is also referred to as radial fastening.

[0025] Referring to FIG. 3 , one of the motor casing 24 and the first casing 70 (here, the first casing 70) is referred to as the first outer casing 80, and the other of the two casings (here, the motor casing 24) is referred to as the first inner casing 82. The first outer casing 80 includes a first outer fastened portion 84A, and the first inner casing 82 includes a first inner fastened portion 86A disposed radially inward of the first outer fastened portion 84A. The first outer fastened portion 84A and the first inner fastened portion 86A are fastened together by first fastening members 74A. In this embodiment, the first outer fastened portion 84A and the first inner fastened portion 86A are each annular. In this embodiment, the first outer fastened portion 84A and the first inner fastened portion 86A are fastened together by a plurality of first fastening members 74A (see FIG. 1 ) spaced apart in the circumferential direction.

[0026] Referring to FIG. 4 , one of the motor casing 24 and the second casing 72 (here, the motor casing 24) is referred to as the second outer casing 88, and the other of the two casings (here, the second casing 72) is referred to as the second inner casing 90. The second outer casing 88 includes a second outer fastened portion 84B, and the second inner casing 90 includes a second inner fastened portion 86B disposed radially inward of the second outer fastened portion 84B. The second outer fastened portion 84B and the second inner fastened portion 86B are fastened together by second fastening members 74B. In this embodiment, the second outer fastened portion 84B and the second inner fastened portion 86B are each annular. In this embodiment, the second outer fastened portion 84B and the second inner fastened portion 86B are fastened together by a plurality of second fastening members 74B (see FIG. 1 ) spaced apart in the circumferential direction.

[0027] In this embodiment, there are two adjacent anti-load side casing members 60A, 60B, which are radially fastened together by the third fastening members 74C. When there are three or more anti-load side casing members 60A, 60B, it is sufficient that at least one pair of adjacent anti-load side casing members 60A, 60B is radially fastened together by the third fastening members 74C.

[0028] One of the two adjacent anti-load side casing members 60A, 60B (here, the second anti-load side casing member 60B) is referred to as the first outer casing member 92, and the other of the two casing members (here, the first anti-load side casing member 60A) is referred to as the first inner casing member 94. The first outer casing member 92 includes a third outer fastened portion 84C, and the first inner casing member 94 includes a third inner fastened portion 86C disposed radially inward of the third outer fastened portion 84C. The third outer fastened portion 84C and the third inner fastened portion 86C are fastened together by third fastening members 74C. In this embodiment, the third outer fastened portion 84C and the third inner fastened portion 86C are each annular portions. In this embodiment, the third outer fastened portion 84C and the third inner fastened portion 86C are fastened together by a plurality of third fastening members 74C spaced apart in the circumferential direction.

[0029] 3, in this embodiment, there are two adjacent reducer casing members 52A, 52B, which are fastened together in the radial direction by the fourth fastening members 74D. In the case where there are three or more reducer casing members 52A, 52B, it is sufficient that at least one pair of adjacent reducer casing members 52A, 52B is fastened together in the radial direction by the fourth fastening members 74D.

[0030] One of the two adjacent reducer casing members 52A, 52B (here, the second reducer casing member 52B) is referred to as the second outer casing member 96, and the other of the two casing members (here, the first reducer casing member 52A) is referred to as the second inner casing member 98. The second outer casing member 96 includes a fourth outer fastened portion 84D, and the second inner casing member 98 includes a fourth inner fastened portion 86D disposed radially inward of the fourth outer fastened portion 84D. The fourth outer fastened portion 84D and the fourth inner fastened portion 86D are fastened together by a fourth fastening member 74D. In this embodiment, the fourth outer fastened portion 84D and the fourth inner fastened portion 86D are each annular. In this embodiment, the fourth outer fastened portion 84D and the fourth inner fastened portion 86D are fastened together by a plurality of fourth fastening members 74D (see FIG. 1 ) spaced apart in the circumferential direction.

[0031] The first fastening member 74A includes a shaft portion 74a extending radially. In this embodiment, the shaft portion 74a is formed with a male thread. In this embodiment, the first fastening member 74A is described as being configured as a head screw; however, set screws, bolts, etc. may also be used. When these are used as the first fastening member 74A, multiple fastened elements are fastened together by screw fastening. Alternatively, the first fastening member 74A may be a rivet such as a blind rivet. The first fastening member 74A serving as a head screw includes, in addition to the shaft portion 74a, a head portion 74b provided at one end of the shaft portion 74a. The head portion 74b of the first fastening member 74A may be provided with a tool hole 74c, such as a hexagonal hole, for inserting a tool to rotate the first fastening member 74A. The configuration of the first fastening member 74A described here may also be applied to the second to fourth fastening members 74B to 74D. Here, common components are denoted by common reference numerals (74a to 74c), and common explanations will be omitted.

[0032] In this embodiment, an outer fastening hole 84a is formed in the first outer fastened portion 84A, and an inner fastening hole 86a is formed in the first inner fastened portion 86A. The shank 74a of the first fastening member 74A is inserted through each of the outer fastening hole 84a and the inner fastening hole 86a. In this embodiment, the outer fastening hole 84a is an unthreaded hole without an internal thread. In this embodiment, the outer fastening hole 84a has a counterbore 84b formed at its outer end with a seat on which the head 74b of the first fastening member 74A sits. At least a portion of the head 74b of the first fastening member 74A is disposed within the counterbore 84b. Alternatively, the seat may be provided on the outer peripheral surface of the first outer fastened portion 84 outside the outer fastening hole 84a. In this embodiment, the inner fastening hole 86a has an internal thread 86b into which the shank 74a of the first fastening member 74A is threaded. The configurations of the first outer fastened portion 84A and the first inner fastened portion 86A described here may also be applied to the second to fourth outer fastened portions 84B to 84D and the second to fourth inner fastened portions 86B to 86D. Here, common components are denoted by common reference numerals (84a, 84b, 86a, 86b), and common descriptions will be omitted.

[0033] The effects of the actuator 10 described above will be explained. Reference is made to FIG. 5 . FIG. 5 shows an actuator 200 according to a reference embodiment. The actuator 200 according to the reference embodiment is similar to the actuator 10 according to the embodiment, except for the shapes of the fastening members and the casings 18, 24, and 34. In the actuator 10 according to the reference embodiment, the motor casing 24 and the first casing 70 (the reducer casing 34) are fastened in the axial direction by a first fastening member 74A. Additionally, the motor casing 24 and the second casing 72 (the anti-load side casing 18) are fastened in the axial direction by a second fastening member 74B. Hereinafter, "axial fastening" refers to connecting axially aligned positions of multiple fastened elements using fastening members 74A and 74B having axially extending shaft portions 74a. Hereinafter, axial fastening is also referred to as "axial fastening." Furthermore, the dimension of the actuator 10 in the axial direction is referred to as the "axial dimension."

[0034] When axial fastening is used, it is necessary to secure locations in the multiple fastened elements through which the shanks 74a of the fastening members 74A and 74B pass axially. Furthermore, when axial fastening is used, the fastening members 74A and 74B often pass axially over a wide axial range of one of the fastened elements, which tends to increase the axial dimensions of the fastening members 74A and 74B. Therefore, in the wide axial range including the fastening members 74A and 74B, waste material portions that increase the outer diameter of the multiple fastened elements are likely to occur. Figure 5 shows the position Pa of the maximum outer diameter R10 of the actuator 10 in Figure 2, and a location 202 radially outward from this position Pa is an example of a waste material portion.

[0035] See FIG. 2. In contrast, when radial fastening is used as in this embodiment, it is not necessary to secure a location for passing the shanks 74a of the fastening members 74A to 74D through multiple fastened elements, as is the case with axial fastening. Furthermore, when radial fastening is used, it is not necessary to pass the fastening members 74A to 74D axially through a wide axial range of one of the fastened elements, making it easier to shorten the axial dimensions of the fastening members 74A to 74D. Therefore, compared to when axial fastening is used, it is less likely that wasted material portions that would increase the outer diameter of the multiple fastened elements will occur in a wide axial range that includes the fastening members 74A to 74D.

[0036] For example, consider the case where the motor casing 24 and the first casing 70 are fastened together in the radial direction by the first fastening members 74A. In this case, compared to when axial fastening is used, excess material that would increase the outer diameter is less likely to occur in the motor casing 24 and the first casing 70 over a wide axial range including the first fastening members 74A. As a result, this is advantageous for reducing the weight of the motor casing 24 and the first casing 70, and therefore the weight of the actuator 10. Furthermore, because excess material that would increase the outer diameter is less likely to occur in the motor casing 24 and the first casing 70, this is also advantageous for reducing the maximum outer diameter of the motor casing 24 and the first casing 70.

[0037] Consider the case where the motor casing 24 and the second casing 72 are fastened together in the radial direction by the second fastening members 74B. In this case, compared to the case where axial fastening is used, it is less likely that excess material will be produced in the motor casing 24 and the second casing 72, which would increase the outer diameter, over a wide axial range including the second fastening members 74B. As a result, this is advantageous for reducing the weight of the motor casing 24 and the second casing 72. Furthermore, because it is less likely that excess material will be produced in the motor casing 24 and the second casing 72, which would increase the outer diameter, it is also advantageous for reducing the maximum outer diameter of the motor casing 24 and the second casing 72.

[0038] Consider the case where two axially adjacent anti-load side casing members 60A, 60B are radially fastened with the third fastening member 74C. In this case, compared to the case where axial fastening is used, it is less likely that a portion of the anti-load side casing members 60A, 60B will have a reduced thickness that would increase the outer diameter over a wide axial range including the third fastening member 74C. As a result, this is advantageous for reducing the weight of the anti-load side casing 18. Furthermore, because it is less likely that a portion of the anti-load side casing members 60A, 60B will have a reduced thickness that would increase the outer diameter, it is also advantageous for reducing the maximum outer diameter of the anti-load side casing 18.

[0039] Consider the case where two axially adjacent reducer casing members 52A, 52B are radially fastened together using the fourth fastening member 74D. In this case, compared to when axial fastening is used, excess material that would increase the outer diameter is less likely to occur in each reducer casing member 52A, 52B over a wide axial range including the fourth fastening member 74D. As a result, this is advantageous for reducing the weight of the reducer casing 34. Furthermore, because excess material that would increase the outer diameter is less likely to occur in each reducer casing member 52A, 52B, this is also advantageous for reducing the maximum outer diameter of the reducer casing 34.

[0040] In the example of Figure 2, it is also possible to reduce the weight of the motor casing 24 and each of the casings 18, 24, and 34 by approximately 16%. It is also possible to reduce the maximum outer diameter of the motor casing 24 and each of the casings 18, 24, and 34 by approximately 10%.

[0041] Another feature of the actuator 10 will now be described. Refer to Figure 3. The motor casing 24 and the first casing 70 are spigot-fitted at their respective locations where they are fastened radially by the first fastening members 74A. The first outer fastened portion 84A and the first inner fastened portion 86A, which are fastened by the first fastening members 74A, are spigot-fitted. Here, spigot-fitting refers to a structure in which the inner fastened portion is fitted into the outer fastened portion.

[0042] The locations of the axially adjacent reducer casing members 52A, 52B that are fastened radially by the fourth fastening members 74D are spigot-fitted. The fourth outer fastened portion 84D and the fourth inner fastened portion 86D that are fastened by the fourth fastening members 74D are spigot-fitted.

[0043] 4, the motor casing 24 and the second casing 72 are spigot-fitted at their radially fastened portions by the second fastening members 74B. The second outer fastened portion 84B and the second inner fastened portion 86B, which are fastened by the second fastening members 74B, are spigot-fitted.

[0044] The locations of the axially adjacent anti-load side casing members 60A, 60B that are fastened radially by the third fastening members 74C are spigot-fitted. The third outer fastened portion 84C and the third inner fastened portion 86C that are fastened by the third fastening members 74C are spigot-fitted.

[0045] With the above configuration, the structure of the actuator 10 can be simplified compared to when a spigot fitting point is provided separately from the fastening points (outer fastening portions 84A to 84D and inner fastening portions 86A to 86D) by the fastening members 74A to 74D.

[0046] The following describes common features of the aforementioned spigot-fit outer fastened portions 84A-84D and inner fastened portions 86A-86D. The inner fastened portions 86A-86D are fitted into the outer fastened portions 84A-84D by being axially inserted into the outer fastened portions 84A-84D that spigot-fit with the inner fastened portions 86A-86D. This facilitates axial alignment of the two objects that are spigot-fitted. The two objects here refer to, for example, the motor casing 24 and the first casing 70, the motor casing 24 and the second casing 72, two adjacent reducer casing members 52A and 52B, or two adjacent anti-load side casing members 60A and 60B.

[0047] The inner fastened portions 86A to 86D may be fitted by clearance fit or transition fit to the outer fastened portions 84A to 84D that are spigot-fitted with the inner fastened portions 86A to 86D. This improves the ease of inserting the inner fastened portions 86A to 86D into the outer fastened portions 84A to 84D compared to when the spigot-fitted outer fastened portions 84A to 84D and the inner fastened portions 86A to 86D are fitted by interference fit. Alternatively, the spigot-fitted outer fastened portions 84A to 84D and the inner fastened portions 86A to 86D may be fitted by interference fit. In this embodiment, the inner peripheries of the spigot-fitted outer fastened portions 84A to 84D and the outer peripheries of the spigot-fitted inner fastened portions 86A to 86D are circular, but the shapes are not particularly limited and may be polygonal or the like.

[0048] Referring to Figure 2, the first inner casing 82 (here, the motor casing 24) has a first partition wall 100A that protrudes radially inward from the inner periphery of the first inner casing 82. The first partition wall 100A is provided at the axial end of the first inner casing 82 that is axially butted against the first outer casing 80 (here, the first casing 70). The first partition wall 100A partially axially separates the motor accommodating space 24a in the motor casing 24 from the first accommodating space 70a in the first casing 70. The first partition wall 100A is, for example, disk-shaped.

[0049] The first fastening member 74A is threaded into an inner fastening hole 86a formed in the first inner casing 82 at a position radially overlapping with the first partition wall portion 100A. In this embodiment, the inner fastening hole 86a has, in addition to a female thread portion 86b into which the first fastening member 74A is threaded, a pilot hole portion 86c that extends radially inward from the female thread portion 86b. At least a portion of the inner fastening hole 86a is formed in the first partition wall portion 100A. In this embodiment, the pilot hole portion 86c of the inner fastening hole 86a is formed in the first partition wall portion 100A.

[0050] The second inner casing 90 (here, the anti-load side casing 18) has a second partition wall 100B that protrudes radially inward from the inner periphery of the second inner casing 90. The second partition wall 100B is provided at the axial end of the second inner casing 90 that is axially butted against the second outer casing 88 (here, the motor casing 24). The second partition wall 100B partially axially separates the motor accommodating space 24a in the motor casing 24 from the second accommodating space 72a in the second casing 72. The second partition wall 100B is, for example, disk-shaped.

[0051] The second fastening member 74B is screwed into an inner fastening hole 86a formed in the second inner casing 90 at a position radially overlapping with the second partition wall portion 100B. In this embodiment, the inner fastening hole 86a also has a female thread portion 86b into which the second fastening member 74B is screwed, as well as a pilot hole portion 86c that extends radially inward from the female thread portion 86b. In this embodiment, at least a portion of the inner fastening hole 86a is also formed in the second partition wall portion 100B. In this embodiment, the pilot hole portion 86c of the inner fastening hole 86a is formed in the second partition wall portion 100B.

[0052] At least one mounting surface 100a is provided on the inner periphery of each partition wall 100A, 100B, on which annular members 102A, 102B are mounted. The annular members 102A, 102B are disposed between the shaft 46 and the partition wall 100A, 100B. In this embodiment, a seal member such as an oil seal is disposed on the mounting surface 100a of the first partition wall 100A as the first annular member 102A. A support bearing that supports the shaft 46 is disposed on the mounting surface 100a of the second partition wall 100B as the second annular member 102B. Specific examples of the annular members 102A, 102B are not particularly limited and may be other than a bearing or a seal member. Furthermore, the first annular member 102A may be a support bearing, and the second annular member 102B may be a seal member.

[0053] The radial dimensions of the partition walls 100A, 100B of the inner casings 82, 90 can be more easily ensured at locations where the partition walls 100A, 100B are located than at other locations on the inner casings 82, 90. Forming the inner fastening holes 86a at locations that radially overlap these locations makes it easier to ensure the radial dimensions of the female threaded portions 86b of the inner fastening holes 86a, which is advantageous for ensuring the fastening strength of the fastening members 74A, 74B threaded into the inner fastening holes 86a. Furthermore, the partition walls 100A, 100B of the inner casings 82, 90 are originally necessary for the function of separating the motor accommodating space 24a from the respective accommodating spaces 70a, 72a. Forming the inner fastening holes 86a at locations that radially overlap these locations minimizes the need for excess material on the inner casings 82, 90 compared to cases where separate screw-in locations for the fastening members 74A, 74B are provided. That is, this is advantageous in ensuring the radial dimension of the female thread portions 86b of the fastening members 74A, 74B while minimizing the amount of excess material in the inner casings 82, 90. To effectively obtain the effects described here, the female thread portions 86b may be formed in the partition walls 100A, 100B of the inner casings 82, 90.

[0054] See Figures 3 and 4. The first fastening member 74A and the second fastening member 74B may satisfy at least one of the following conditions (A1), (A2), and (A3). Condition (A1) is that the shaft diameter R74B of the second fastening member 74B is smaller than the shaft diameter R74A of the first fastening member 74A. Condition (A2) is that the shaft length L74B of the second fastening member 74B is smaller than the shaft length L74A of the first fastening member 74A. Condition (A3) is that the number of second fastening members 74B is smaller than the number of first fastening members 74A. The "shaft diameter" here refers to the diameter (mm) of the shaft portion 74a of the fastening member. The "shaft length" here refers to the length (mm) of the male thread portion of the shaft portion 74a in the direction along the center line of the shaft portion 74a of the fastening member. In addition, the axial length of condition (A2) may be the meshing length (mm), which is the length in the direction along the center line of the fastening member at the meshing point of the male thread portion of the shank 74a of the fastening member with the female thread portion 86b of the inner fastening hole 86a.

[0055] When multiple second fastening members 74B are present, conditions (A1) and (A2) need only be satisfied by at least one second fastening member 74B. Conditions (A1) and (A2) may be satisfied by two or more second fastening members 74B, or may be satisfied by all second fastening members 74B. When multiple first fastening members 74A are present, condition (A1) needs only to be satisfied if the shaft diameter R74B of the second fastening member 74B is smaller than the smallest shaft diameter R74A among the multiple first fastening members 74A. When multiple first fastening members 74A are present, condition (A2) needs only to be satisfied if the axial length L74B of the second fastening member 74B is smaller than the smallest axial length L74A among the multiple first fastening members 74A. Any one, two, or all of conditions (A1), (A2), and (A3) may be satisfied.

[0056] When condition (A1) is satisfied, reducing the shaft diameter R74B of the second fastening member 74B is advantageous for reducing the weight of the actuator 10, compared to when the shaft diameter R74B of the second fastening member 74B is the same as the shaft diameter R74A of the first fastening member 74A. When condition (A2) is satisfied, reducing the shaft length L74B of the second fastening member 74B is advantageous for reducing the weight of the actuator 10, compared to when the shaft length L74B of the second fastening member 74B is the same as the shaft length L74A of the first fastening member 74A. When condition (A3) is satisfied, reducing the number of second fastening members 74B is advantageous for reducing the weight of the actuator 10, compared to when the number of second fastening members 74B is the same as the number of first fastening members 74A. In other words, satisfying any of conditions (A1) to (A3) is advantageous for reducing the weight of the actuator 10.

[0057] The reducer casing 34 is often located in the transmission path of the large torque output from the reducer 16 and often supports a large load of the driven device. In other words, the reducer casing 34 is often used under conditions where large torque and large loads are applied. For this reason, the fastening between the reducer casing 34 and the motor casing 24 is required to be robust, and the fastening strength required is high. In contrast, the motor casing 24 and the anti-load side casing 18, which are located on the anti-load side of the reducer casing 34, are often used under conditions where large torque and large loads are not applied, compared to the reducer casing 34. Therefore, the fastening strength required between the motor casing 24 and the anti-load side casing 18 is lower than the fastening between the reducer casing 34 and the motor casing 24. Therefore, by satisfying at least one of the above-described conditions (A1), (A2), and (A3), the fastening strength required for fastening the motor casing 24 and the anti-load side casing 18 can be easily ensured, even if the fastening strength of the second fastening member 74B is reduced. This is advantageous in reducing the weight of the actuator 10 while ensuring the required fastening strength between the motor casing 24 and the anti-load side casing 18 and between the reducer casing 34 and the motor casing 24.

[0058] The first fastening member 74A and the third fastening member 74C may satisfy at least one of the following conditions (B1), (B2), and (B3): Condition (B1) is that the shaft diameter R74C of the third fastening member 74C is smaller than the shaft diameter R74A of the first fastening member 74A. Condition (B2) is that the shaft length L74C of the third fastening member 74C is smaller than the shaft length L74A of the first fastening member 74A. Condition (B3) is that the number of third fastening members 74C is smaller than the number of first fastening members 74A.

[0059] When multiple third fastening members 74C are present, conditions (B1) and (B2) need only be satisfied by at least one third fastening member 74C. Conditions (B1) and (B2) may be satisfied by two or more third fastening members 74C, or may be satisfied by all third fastening members 74C. Condition (B1) needs only to be satisfied when multiple first fastening members 74A are present, as long as the shaft diameter R74C of the third fastening member 74C is smaller than the smallest shaft diameter R74A among the multiple first fastening members 74A. Condition (B2) needs only to be satisfied when multiple first fastening members 74A are present, as long as the axial length L74C of the third fastening member 74C is smaller than the smallest axial length L74A among the multiple first fastening members 74A. Any one, two, or all of conditions (B1), (B2), and (B3) may be satisfied.

[0060] When condition (B1) is satisfied, reducing the shaft diameter R74C of the third fastening member 74C is advantageous for reducing the weight of the actuator 10, compared to when the shaft diameter R74C of the third fastening member 74C is the same as the shaft diameter R74A of the first fastening member 74A. When condition (B2) is satisfied, reducing the shaft length L74C of the third fastening member 74C is advantageous for reducing the weight of the actuator 10, compared to when the shaft length L74C of the third fastening member 74C is the same as the shaft length L74A of the first fastening member 74A. When condition (B3) is satisfied, reducing the number of third fastening members 74C is advantageous for reducing the weight of the actuator 10, compared to when the number of third fastening members 74C is the same as the number of first fastening members 74A. In other words, satisfying any of conditions (B1) to (B3) is advantageous for reducing the weight of the actuator 10.

[0061] As described above, the two adjacent anti-load side casing members 60A, 60B located on the anti-load side of the reducer casing 34 are often used under conditions where large torques and loads are not applied, compared to the reducer casing 34. Therefore, the fastening strength required for fastening the two adjacent anti-load side casing members 60A, 60B is lower than the fastening strength required for fastening the reducer casing 34 and the motor casing 24. Therefore, by satisfying at least one of the above-described conditions (B1), (B2), and (B3), the fastening strength required for fastening the two adjacent anti-load side casing members 60A, 60B can be easily ensured even if the fastening strength of the third fastening member 74C is reduced. Therefore, this is advantageous for reducing the weight of the actuator 10 while ensuring the fastening strength required for fastening the two adjacent anti-load side casing members 60A, 60B and for fastening the reducer casing 34 and the motor casing 24.

[0062] Next, variations of the components described above will be described.

[0063] The specific example of the reduction mechanism 32 of the reducer 16 is not particularly limited. The reduction mechanism 32 may be an eccentric oscillating reduction mechanism, a simple planetary gear reduction mechanism, a flexible mesh reduction mechanism (including cylindrical, top hat, and cup types), a perpendicular-axis gear reduction mechanism, a parallel-axis gear reduction mechanism, or other gear mechanism. The reduction mechanism 32 may be a friction transmission mechanism or other gear mechanism. While the eccentric oscillating reduction mechanism has been described as a center crank type in which the input shaft 30 is disposed on the rotation center line La, it may also be a distribution type in which the input shaft 30 is disposed at a position radially offset from the rotation center line La. The output member 44 may be configured by the reducer casing 34 instead of the load-side cover 36.

[0064] The fastening points of the motor casing 24 and the first casing 70 by the first fastening members 74A do not have to be spigot-fitted. The first casing 70 may be the anti-load side casing 18 instead of the reducer casing 34.

[0065] The motor casing 24 and the second casing 72 may be fastened in the axial direction by the second fastening members 74B. The fastening points of the motor casing 24 and the second casing 72 by the second fastening members 74B do not have to be spigot-fitted.

[0066] Two axially adjacent anti-load side casing members 60A, 60B may be fastened together in the axial direction by the third fastening members 74C. The fastening points of these anti-load side casing members 60A, 60B by the third fastening members 74C do not have to be spigot-fitted.

[0067] Two axially adjacent reducer casing members 52A, 52B may be fastened together in the axial direction by the fourth fastening members 74D. The fastening points of these reducer casing members 52A, 52B by the fourth fastening members 74D do not have to be spigot-fitted.

[0068] The inner casings 82, 90 may have inner fastening holes 86a formed at positions that do not overlap the partition walls 100A, 100B in the radial direction, into which the fastening members 74A, 74B are screwed.

[0069] The content of each component described in the above embodiments is merely illustrative. The abstract technical ideas should not be interpreted as being limited to the content of this specification. The content of each component described in the embodiments is subject to many design changes, such as modifications, additions, and deletions. Contents subject to such design changes are emphasized by the notation "this embodiment" or "embodiment." However, design changes are also permitted even in content without such notation. The structures and numerical values ​​referred to in the embodiments and modified forms naturally include those that can be considered identical when considering manufacturing errors, etc. In the description of this specification, a component composed of a single member may be composed of multiple members. Similarly, a component composed of multiple members may be composed of a single member.

[0070] The present disclosure relates to actuators.

[0071] 10...actuator, 12...motor body, 14...motor, 16...reduction gear, 18...anti-load side casing, 24...motor casing, 34...reduction gear casing, 52A, 52B...reduction gear casing members, 60A, 60B...anti-load side casing members, 70...first casing, 72...second casing, 74A...first fastening member, 74B...second fastening member, 74C...third fastening member, 74D...fourth fastening member, 86a...fastening hole (inner fastening hole), 100A...first partition portion, 100B...second partition portion.

Claims

1. An actuator comprising: a motor having a motor body that generates a rotating magnetic field; and a reducer that decelerates the rotation output from the motor body; a motor casing that houses the motor body; and a first casing that is axially adjacent to the motor casing, wherein the motor casing and the first casing are radially fastened together by a first fastening member.

2. The actuator according to claim 1, wherein the motor casing and the first casing are fitted together at their radially fastened portions by the first fastening members.

3. An actuator as described in claim 1 or 2, wherein one of the motor casing and the first casing has a first partition wall portion that protrudes radially inward at the inner periphery of the one casing, and the first fastening member is screwed into a fastening hole formed in the one casing at a position that radially overlaps with the first partition wall portion.

4. An actuator as described in any one of claims 1 to 3, comprising a second casing that is axially adjacent to the motor casing on the axially opposite side of the first casing with respect to the motor casing, and the motor casing and the second casing are fastened together radially by a second fastening member.

5. An actuator as described in claim 4, wherein one of the motor casing and the second casing has a second partition wall portion that protrudes radially inward from the inner periphery of the one casing, and the second fastening member is screwed into a fastening hole formed in the one casing at a position that radially overlaps with the second partition wall portion.

6. The actuator described in claim 4 or 5, wherein the second casing is an anti-load side casing arranged on the anti-load side of the motor casing, and satisfies at least one of the following conditions (A1), (A2) and (A3): condition (A1) is that the shaft diameter of the second fastening member is smaller than the shaft diameter of the first fastening member; condition (A2) is that the shaft length of the second fastening member is smaller than the shaft length of the first fastening member; and condition (A3) is that the number of the second fastening members is smaller than the number of the first fastening members.

7. An actuator as described in any one of claims 1 to 6, comprising an anti-load side casing arranged on the anti-load side of the motor casing, the anti-load side casing comprising a plurality of anti-load side casing members, and two axially adjacent anti-load side casing members being fastened radially by a third fastening member.

8. The actuator described in claim 7, wherein the first casing is a reducer casing arranged on the load side of the motor casing, and satisfies at least one of the following conditions (B1), (B2) and (B3): condition (B1) is that the shaft diameter of the third fastening member is smaller than the shaft diameter of the first fastening member; condition (B2) is that the shaft length of the third fastening member is smaller than the shaft length of the first fastening member; and condition (B3) is that the number of the third fastening members is smaller than the number of the first fastening members.

9. An actuator according to any one of claims 1 to 8, wherein the reducer comprises a reducer casing arranged on the load side of the motor casing, the reducer casing comprises a plurality of reducer casing members, and two axially adjacent reducer casing members are fastened radially by a fourth fastening member.

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