Eccentric oscillation type speed reduction device

Abstract

To provide an eccentric oscillation type speed reduction device that can detect torque acting on a constituent member.SOLUTION: An eccentric oscillation type speed reduction device comprises an eccentric body 12, an external gear 16 capable of being oscillated by the eccentric body 12, an internal gear 18 engaged with the external gear 16, and a carrier 20 capable of being synchronized with the rotation component of the external gear 16. One of the internal gear 18 and the carrier 20 constitutes at least a portion of a fixed body 28 fixed to an outside member 26. The fixed body 28 comprises: a first ring part 40; a second ring part 42 provided separately from the first ring part 40 in a radial direction, and fixed to the outside member 26; and a strain generation part 44 provided between the first ring part 40 and the second ring part 42. A strain sensor 60 is installed in the strain generation part 44.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an eccentric swing type reduction gear.

Background Art

[0002] Patent Document 1 discloses an eccentric swing type reduction gear including an eccentric body, an external gear swung by the eccentric body, an internal gear meshing with the external gear, and a carrier synchronized with the rotation component of the external gear.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an eccentric swing type reduction gear, it may be required to detect the torque acting on its constituent members.

[0005] Therefore, one object of the present disclosure is to provide an eccentric swing type reduction gear capable of detecting the torque acting on a constituent member.

Means for Solving the Problems

[0006] The eccentric swing type reduction gear of the present disclosure is an eccentric swing type reduction gear including an eccentric body, an external gear swung by the eccentric body, an internal gear meshing with the external gear, and a carrier synchronized with the rotation component of the external gear, wherein one of the internal gear and the carrier constitutes at least a part of a fixed body fixed to an external member, the fixed body includes a first ring portion, a second ring portion provided radially apart from the first ring portion and fixed to the external member, and a strain generating portion provided between the first ring portion and the second ring portion, and a strain sensor is installed in the strain generating portion.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0008] Embodiments for implementing the eccentric swing type speed reduction device (hereinafter also referred to as the speed reduction device) of the present disclosure will be described. The same or equivalent elements are denoted by the same reference numerals, and duplicate descriptions are omitted. In each drawing, for the convenience of explanation, components are appropriately omitted, enlarged, or reduced. The drawings are to be viewed in accordance with the direction of the reference numerals.

[0009] (First Embodiment) Refer to FIG. 1. The reduction gear 10 includes a crankshaft 14 having at least one eccentric body 12, an external gear 16 swingable by the eccentric body 12, an internal gear 18 meshing with the external gear 16, a synchronizing carrier 20 synchronizable with the rotation component of the external gear 16, a casing 22 disposed radially outside the external gear 16, and an asynchronous carrier 24 provided on the side opposite to the synchronizing carrier 20 with respect to the external gear 16 in the axial direction. In this embodiment, a center crank type eccentric swing type reduction gear 10 will be described. In this type of reduction gear 10, the crankshaft 14 is disposed on the swing center C16a of the external gear 16. Hereinafter, the direction along the swing center C16a of the external gear 16 is referred to as the axial direction, and with respect to the radial direction and the circumferential direction centered on the swing center C16a, they are referred to as the radial direction and the circumferential direction.

[0010] The reduction gear 10 includes a fixing body 28 fixed to an external member 26 and an output body 32 that outputs rotation to an external driven member 30. Here, an example will be described in which the synchronizing carrier 20 and the casing 22 constitute the fixing body 28, and the internal gear 18 and the asynchronous carrier 24 constitute the output body 32. The external member 26 is provided outside the reduction gear 10 and supports the reduction gear 10. The driven member 30 is provided outside the reduction gear 10 and is driven by the output of the output body 32. The driven member 30 is, for example, a part of various machines such as industrial machines (machine tools, construction machines, etc.), robots (industrial robots, service robots, etc.), and transportation equipment (conveyors, vehicles, etc.). When rotation is input from a drive source (not shown) to the crankshaft 14, the output body 32 outputs rotation decelerated from the rotation of the crankshaft 14 to the driven member 30. The drive source is, for example, a motor, but other than this, a gear motor, an engine, etc. may also be used.

[0011] The eccentric body 12 has a circular shape eccentric with respect to the rotation center line C14 of the crankshaft 14. The eccentric body 12 can swing the external gear 16 by rotating around the rotation center line C14 of the crankshaft 14. Here, "swing" means that the gear center C16b of the external gear 16 rotates around the swing center C16a. The number of eccentric bodies 12 is not particularly limited, and either a single one or three or more may be used.

[0012] The external gear 16 is individually provided corresponding to each of the plurality of eccentric bodies 12, and is supported by the corresponding eccentric body 12 via an eccentric bearing 34. The internal gear 18 includes an internal gear main body 18a and a plurality of internal teeth 18b provided on the inner peripheral portion of the internal gear main body 18a and meshing with the external gear 16. The plurality of internal teeth 18b may be integrally provided by the same member as the internal gear main body 18a, or may be constituted by a plurality of pins rotatably supported by the internal gear main body 18a.

[0013] Pins 36 project axially from the synchronization carrier 20. A plurality of pins 36 are provided at intervals in the circumferential direction. The pins 36 may be constituted by the same member as the synchronization carrier 20, or may be constituted by a member different from the synchronization carrier 20. The pins 36 penetrate the external gear 16 axially, and can receive a load from the external gear 16 when the external gear 16 swings.

[0014] That the synchronization carrier 20 is "synchronized with the rotation component of the external gear 16" means that, within a numerical range including zero, the rotation component of the synchronization carrier 20 is maintained at the same magnitude with respect to the rotation component of the external gear 16. For example, as in this embodiment, when the internal gear 18 becomes the output body 32 and the synchronization carrier 20 becomes the fixed body 28, the internal gear 18 rotates during the operation of the speed reduction device 10. In this case, the synchronization carrier 20 is fixed to the external member 26, so that its rotation component is maintained at zero. Further, since the rotation of the external gear 16 is restricted by the synchronization carrier 20 and the pins 36, the rotation component of the external gear 16 is also maintained at zero. As a result, the rotation component of the synchronization carrier 20 is synchronized with the rotation component of the external gear 16. On the other hand, when the internal gear 18 becomes the fixed body 28 and the synchronization carrier 20 becomes the output body 32, the external gear 16 rotates during the operation of the speed reduction device 10. The rotation component of this external gear 16 is transmitted to the synchronization carrier 20 via the pins 36. Thereby, the synchronization carrier 20 rotates with a rotation component having the same magnitude as the rotation component of the external gear 16, and thereby is synchronized with the rotation component of the external gear 16.

[0015] The asynchronous carrier 24 is not connected to the synchronous carrier 20 and does not synchronize with the rotation component of the synchronous carrier 20 during the operation of the speed reducer 10. Consider the case where, as in this embodiment, the synchronous carrier 20 becomes the fixed body 28 and maintains the rotation component at zero. In this case, the asynchronous carrier 24 becomes the output body 32 and rotates, thus not synchronizing with the rotation component of the synchronous carrier 20. On the other hand, consider the case where the synchronous carrier 20 becomes the output body 32 and rotates. In this case, the asynchronous carrier 24 becomes the fixed body 28 and maintains the rotation component at zero, thus not synchronizing with the rotation component of the synchronous carrier 20.

[0016] The casing 22 of this embodiment is provided separately from the internal gear 18. The casing 22 of this embodiment is integrated with the synchronous carrier 20 by being fixed to the synchronous carrier 20 by a fixture such as bolts (not shown).

[0017] An example of the operation of the speed reducer 10 described above will be explained. When rotation is input from the drive source to the crankshaft 14, the external gear 16 swings due to the eccentric body 12 of the crankshaft 14. When the external gear 16 swings, the meshing position between the external gear 16 and the internal gear 18 changes in the circumferential direction. Accordingly, every time the crankshaft 14 makes one revolution, either the external gear 16 or the internal gear 18 (here, the internal gear 18) rotates. The output body 32 rotates by the rotation component of one of the external gear 16 and the internal gear 18 and outputs the rotation to the driven member 30. At this time, the output body 32 outputs to the driven member 30 a rotation that has been decelerated at a reduction ratio corresponding to the difference in the number of teeth between the external gear 16 and the internal gear 18 with respect to the rotation input to the crankshaft 14.

[0018] Refer to FIGS. 1 to 3. The speed reducer 10 includes a strain sensor 60 installed at the strain generating portion 44 (described later) of the fixed body 28, and a circuit board 62 electrically connected to the strain sensor 60. In addition to these, the speed reducer 10 is characterized by the structure of the fixed body 28.

[0019] The fixed body 28 includes a first ring portion 40, a second ring portion 42 provided radially apart from the first ring portion 40 and fixed to the external member 26, and a strain generating portion 44 provided between the first ring portion 40 and the second ring portion 42. The first ring portion 40, the second ring portion 42, and the strain generating portion 44 of this embodiment are provided on the synchronous carrier 20. In this embodiment, they are provided on a single member constituting the synchronous carrier 20.

[0020] The first ring portion 40 is ring-shaped. The second ring portion 42 is ring-shaped. The first ring portion 40 of this embodiment becomes an inner ring portion provided on the radially inner side, and the second ring portion 42 becomes an outer ring portion provided on the radially outer side.

[0021] Torque is input to the first ring portion 40 during the operation of the speed reduction device 10. Specifically, torque is input to the first ring portion 40 when torque is transmitted from either the external gear 16 or the internal gear 18 during the operation of the speed reduction device 10. Consider the case where the synchronous carrier 20 forms at least a part of the fixed body 28 as in this embodiment. In this case, the torque transmitted from the external gear 16 is input to the first ring portion 40 of the fixed body 28 via the pin 36. On the other hand, consider the case where the internal gear 18 forms at least a part of the fixed body 28 as in the embodiment of FIG. 7 described later. In this case, the torque transmitted from the internal teeth 18b of the internal gear 18 is input to the first ring portion 40 of the fixed body 28.

[0022] The second ring portion 42 includes a first fixing portion 46 fixed to the external member 26. The first fixing portion 46 of this embodiment is directly fixed to the external member 26 by a fixture 48 such as a bolt. In FIG. 1, only the center line of the bolt serving as the fixture 48 is shown. In FIG. 1, only the center lines are shown for the locations of other bolts as well. A first through hole 46a for passing the fixture 48 is formed in the first fixing portion 46 of this embodiment at intervals in the circumferential direction. In addition to this, the first fixing portion 46 may be fixed to the external member 26 via other constituent members (for example, the casing 22) of the fixed body 28.

[0023] The distortion portion 44 connects the first ring portion 40 and the second ring portion 42. The distortion portion 44 is deformable while transmitting the torque transmitted to the first ring portion 40 to the second ring portion 42. When such torque is applied, the distortion portion 44 is configured to be deformable in the circumferential direction more than the first ring portion 40 and the second ring portion 42. It can also be said that the amount of deformation of the distortion portion 44 in the circumferential direction is larger than that of the first ring portion 40 and the second ring portion 42.

[0024] In order to increase the amount of deformation of the distortion portion 44 in this way, the distortion portion 44 of this embodiment is composed of a plurality of column portions 50 provided at intervals in the circumferential direction. A specific example for increasing the amount of deformation of the distortion portion 44 in this way is not particularly limited. In order to realize this, for example, the distortion portion 44 may have a reduced axial dimension with respect to both the first ring portion 40 and the second ring portion 42. In this case, the distortion portion 44 may form a continuous ring shape in the circumferential direction.

[0025] The plurality of column portions 50 of this embodiment are provided so as to extend radially when viewed from the axial direction. The specific shape of the column portion 50 is not particularly limited. The column portion 50 may have, for example, a linear shape, a curved shape, a crank shape, etc. when viewed from the axial direction.

[0026] The fixing body 28 includes an axially penetrating hole 52 formed between adjacent column portions 50. The axially penetrating hole 52 penetrates the fixing body 28 in the axial direction. A plurality of axially penetrating holes 52 of this embodiment are formed at intervals in the circumferential direction. The axially penetrating hole 52 includes a pair of circumferential side portions 52a formed by adjacent column portions 50 and a pair of radial side portions 52b, 52c formed by the first ring portion 40 and the second ring portion 42. The pair of radial side portions 52b, 52c includes an inner radial side portion 52b formed by the outer peripheral portion of the ring portion 40 on the radially inner side and an outer radial side portion 52c formed by the inner peripheral portion of the ring portion 42 on the radially outer side.

[0027] Refer to FIGS. 4, 5, and 6. The strain sensor 60 is used to detect the torque acting on the fixed body 28. The strain sensor 60 is installed on the axial side surface of the strained portion 44 by adhesion or the like. When the strained portion 44 of the fixed body 28 is deformed, the strain sensor 60 detects an electrical signal corresponding to the strain. The electrical signal detected by the strain sensor 60 indicates the strain of the strained portion 44. The strain sensor 60 of the present embodiment detects an electrical signal indicating the shear strain of the strained portion 44 in a direction orthogonal to the axial direction.

[0028] The strain sensor 60 of the present embodiment is a strain gauge, but its specific example is not particularly limited. The strain gauge may be a uniaxial gauge using a single gauge element made of a resistance wire, or a multi-axial gauge such as a rosette gauge using a plurality of gauge elements. Here, as the strain gauge, a biaxial gauge using two gauge elements 64A and 64B is exemplified, but its specific example is not particularly limited. The gauge elements 64A and 64B are deformed together with the strained portion 44 of the fixed body 28 to detect an electrical signal indicating the strain in the detection direction corresponding to each of the gauge elements 64A and 64B. The gauge elements 64A and 64B of the present embodiment include a first gauge element 64A for detecting the shear strain in the first detection direction D1 and a second gauge element 64B for detecting the shear strain in a second detection direction D2 orthogonal to the first detection direction D1.

[0029] The strain sensor 60 includes a sensor electrode 66 for outputting the detected electrical signal. The sensor electrode 66 of the present embodiment is a pad electrode provided on the main surface (axial side surface) of the strain sensor 60, but its specific example is not particularly limited. The sensor electrode 66 of the present embodiment is individually provided corresponding to each of the individual gauge elements 64A and 64B, and is provided at both ends of each of the gauge elements 64A and 64B.

[0030] The strain sensors 60 of this embodiment are installed in a plurality of numbers at intervals in the circumferential direction. Specifically, in this embodiment, a total of four strain sensors 60 are installed at intervals in the circumferential direction. The strain sensors 60 are connected so as to form a bridge circuit (not shown) according to a predetermined connection method (1-gauge method, 2-gauge method, 4-gauge method, etc.). Here, a connection method of the 4-gauge method using four strain sensors 60 is exemplified. In addition to this, any of the 1-gauge method using one strain sensor 60, the 2-gauge method using two strain sensors 60, etc. may be used. The number and arrangement positions of the strain sensors 60 are not limited to this, and may be changed as appropriate.

[0031] The strain sensor 60 is electrically connected to a processing device 68 for detecting torque via a circuit board 62. The processing device 68 is, for example, a combination of a CPU, ROM, and RAM such as a microcomputer, and is composed of, for example, a processing chip or the like. The processing device 68 may be mounted on the circuit board 62 or may exist outside the speed reducer 10.

[0032] The strain sensor 60 outputs an electrical signal indicating the strain of the strained portion 44 to the processing device 68 via the aforementioned bridge circuit. The processing device 68 can detect the torque acting on the fixed body 28 by processing the electrical signal output from the strain sensor 60. As a processing method for detecting torque from the electrical signal of the strain sensor 60, in addition to known methods, a method that can be used in the future may be used, and a detailed description thereof is omitted.

[0033] Circuit elements 70 used for processing the electrical signals of the strain sensors 60 are mounted on the circuit board 62. The circuit elements 70 are, for example, an amplifier that amplifies the electrical signal of the strain sensor 60, a processing chip that constitutes the processing device 68, an A / D converter, etc. The circuit elements 70 are mounted on a mounting surface 62d provided on the main surface of the circuit board 62.

[0034] The circuit board 62 includes a plurality of board electrodes 72 for electrically connecting to the strain sensor 60. The board electrodes 72 of this embodiment are end face through-hole electrodes provided on the end face of the circuit board 62 (the end face of the first protruding portion 62b described later). The type of the board electrode 72 is not particularly limited, and it may be a pad electrode provided on the main surface of the circuit board 62 or the like. The plurality of board electrodes 72 constitute an electrode group 74 composed of a plurality (here, four) of board electrodes 72. The circuit board 62 of this embodiment includes a plurality of sets of electrode groups 74. The plurality of sets of electrode groups 74 are provided at intervals in the circumferential direction of the circuit board 62. The electrode group 74 corresponds to one strain sensor 60, and each board electrode 72 belonging to the electrode group 74 is electrically connected to each sensor electrode 66 of the corresponding strain sensor 60. Note that the number and positions of the sensor electrodes 66 and the board electrodes 72 are not particularly limited.

[0035] The strain sensor 60 and the circuit board 62 are electrically connected via a conductive connection material 76 that contacts them. Specifically, the sensor electrode 66 of the strain sensor 60 and the board electrode 72 of the circuit board 62 that are to be electrically connected to each other are electrically connected via the conductive connection material 76 that contacts them. The conductive connection material 76 of this embodiment is solder, but other conductive resins or the like may also be used. The circuit board 62 and the strain sensor 60 of this embodiment are directly connected by the conductive connection material 76, but they may also be connected using a wire such as a bonding wire and the conductive connection material 76. The electrical signal output from the strain sensor 60 is sent to other locations such as the circuit element 70 via the board electrode 72 of the circuit board 62 → the conductor pattern 78 (see FIG. 6) of the circuit board 62 in sequence.

[0036] The effects of the above-described speed reducer 10 will be described.

[0037] (A) When torque is input to the first ring portion 40 during the operation of the speed reducer 10, the strained portion 44 of the fixed body 28 deforms while transmitting the torque. A strain sensor 60 is installed on such a strained portion 44 of the fixed body 28. Therefore, by using the electrical signal corresponding to the strain of the strained portion 44 detected by the strain sensor 60, the torque acting on the fixed body 28 can be detected.

[0038] As described above, this torque can be detected by processing an electrical signal by the processing device 68. In solving the problem of providing the eccentric swing type reduction gear 10 capable of detecting torque, this processing device 68 is not essential, and the reduction gear 10 does not need to include this processing device 68.

[0039] The strain generating portion 44 of the fixed body 28 is configured to be more deformable than each of the ring portions 40 and 42 of the fixed body 28, and is likely to increase the strain when torque acts. By installing the strain sensor 60 at a location where such strain is likely to increase, the electrical signal detected by the strain sensor 60 can be increased as compared with the case where the strain sensor 60 is installed on each of the ring portions 40 and 42 of the fixed body 28. As a result, even if the torque acting on the first ring portion 40 of the fixed body 28 is small, the torque can be easily detected using this electrical signal as compared with such a case.

[0040] Next, other features of the reduction gear 10 of this embodiment will be described. Refer to FIGS. 3 and 5. The strain generating portion 44 of the fixed body 28 includes a first recess 80 that houses the strain sensor 60. The first recess 80 is provided on the axial side surface of the fixed body 28. The first recess 80 is provided between the first ring portion 40 and the second ring portion 42, and is recessed axially with respect to the axial side surface of at least one of the first ring portion 40 and the second ring portion 42 (here, the first ring portion 40). The first recess 80 of this embodiment is also recessed axially with respect to the axial side surface of a reinforcing portion 90 provided in the strain generating portion 44 described later. The strain sensor 60 is installed on the bottom surface portion of the first recess 80 by adhesion or the like.

[0041] One of the first ring portion 40 and the second ring portion 42 of the fixing body 28 is provided with a second recess 82 for accommodating at least a part of the circuit board 62. The second recess 82 is provided on the axial side surface of the fixing body 28. The second recess 82 of the present embodiment is provided on the axial side surface of the second ring portion 42, and is recessed axially with respect to the axial outer surface 42a of the second ring portion 42 that is axially outside the second recess 82. The circuit board 62 is installed on the bottom surface portion of the second recess 82 by adhesion or the like. The internal space of the second recess 82 of the present embodiment is continuous with the internal space of the first recess 80. The bottom surface portion of the second recess 82 and the bottom surface portion of the first recess 80 are flush and continuous.

[0042] When viewed axially, the second recess 82 includes a circumferential extension portion 82a that extends in the circumferential direction, a first radial extension portion 82b that extends radially from the circumferential extension portion 82a toward the strain generating portion 44, and a second radial extension portion 82c that extends radially from the circumferential extension portion 82a toward the axial through hole 52. Here, for the convenience of explanation, the positions of the respective portions are indicated by two-dot chain lines in FIG. 3. The circumferential extension portion 82a is shown partially. The circumferential extension portion 82a of the present embodiment extends so as to be continuously annular, but may be provided only in a partial circumferential range. The first radial extension portions 82b of the present embodiment are provided individually corresponding to each of the plurality of pillar portions 50. A plurality of first radial extension portions 82b are provided at intervals in the radial direction. The second radial extension portions 82c of the present embodiment are provided individually corresponding to each of the plurality of axial through holes 52. A plurality of second radial extension portions 82c are provided at intervals in the radial direction.

[0043] Refer to FIGS. 4 and 5. The circuit board 62 includes a circumferential portion 62a that axially faces one of the first ring portion 40 and the second ring portion 42, a first protruding portion 62b that protrudes radially from the circumferential portion 62a, and a second protruding portion 62c that protrudes radially from the circumferential portion 62a. The mounting surface 62d of the circuit board 62 is mainly provided on the circumferential portion 62a of the circuit board 62 and the second protruding portion 62c.

[0044] The circumferential portion 62a has a circumferential shape extending in the circumferential direction. To achieve this, the circumferential portion 62a of the present embodiment is continuously annular, but it may be provided only in a partial circumferential range. The circumferential portion 62a of the present embodiment is axially opposed to the second ring portion 42 and is installed on the opposed second ring portion 42 with an adhesive or the like. The circumferential portion 62a of the present embodiment is axially opposed in the second recess 82 of the second ring portion 42. The circuit board 62 is installed on the fixing body 28 at the ring portion 42, which is a location different from the strain generating portion 44 where the strain sensor 60 is installed. The circumferential portion 62a is accommodated in the circumferential extension portion 82a of the second recess 82 of the fixing body 28.

[0045] The first protrusion 62b protrudes radially with respect to the circumferential portion 62a toward the side where the strain generating portion 44 of the fixing body 28 is located. The first protrusion 62b of the present embodiment protrudes into the first recess 80 where the strain generating portion 44 is located with respect to the circumferential portion 62a. The first protrusion 62b is accommodated not only in the first recess 80 of the fixing body 28 but also in the first radial extension portion 82b of the second recess 82. A substrate electrode 72 is provided on the first protrusion 62b. The first protrusion 62b is connected to the strain sensor 60 by the conductive connection material 76 as described above.

[0046] The second protrusion 62c protrudes radially on the same side as the first protrusion 62b with respect to the circumferential portion 62a. The second protrusion 62c is provided at a location overlapping the internal space of the axial through-hole 52 of the fixing body 28 when viewed from the axial direction. The second protrusion 62c protrudes from the circumferential portion 62a of the circuit board 62 so as to be located between adjacent column portions 50 when viewed from the axial direction. The second protrusion 62c protrudes more radially than the first protrusion 62b with respect to the circumferential portion 62a. The second protrusion 62c is partially accommodated in the second radial extension portion 82c (see FIG. 3) of the second recess 82 of the fixing body 28.

[0047] The effects of the above features will be described.

[0048] (B) The warpage portion 44 includes a first recess 80 that houses the strain sensor 60. Therefore, compared with the case where the first recess 80 is not provided in the warpage portion 44, it is possible to make it difficult for the strain sensor 60 to interfere with other members.

[0049] (C) The second ring portion 42 of the fixing body 28 includes a second recess 82 that houses the circuit board 62. Therefore, compared with the case where the second recess 82 is not provided in the second ring portion 42, it is possible to make it difficult for the circuit board 62 to interfere with other members. This effect can also be obtained when the first ring portion 40 includes the second recess 82 instead of the second ring portion 42.

[0050] (D) The circuit board 62 includes a first protruding portion 62b that protrudes into the first recess 80 of the fixing body 28 and is electrically connected to the strain sensor 60. Therefore, compared with the case where the circuit board 62 does not include the first protruding portion 62b, it is possible to have a part of the circuit board 62, i.e., the first protruding portion 62b, near the strain sensor 60 within the first recess 80. As a result, it becomes easier to electrically connect the circuit board 62 and the strain sensor 60 using the first protruding portion 62b.

[0051] (E) The circuit board 62 includes a circumferential portion 62a that axially faces the second ring portion 42, and a first protruding portion 62b that protrudes radially from the circumferential portion 62a and is connected to the strain sensor 60. Therefore, compared with the case where the circuit board 62 does not include the first protruding portion 62b, it is possible to have a part of the circuit board 62, i.e., the first protruding portion 62b, near the strain sensor 60 installed in the warpage portion 44 of the fixing body 28. As a result, it becomes easier to connect the circuit board 62 and the strain sensor 60 using the first protruding portion 62b. This effect can also be obtained when the first ring portion 40 axially faces the circumferential portion 62a of the circuit board 62 instead of the second ring portion 42.

[0052] (F) The circuit board 62 includes a second protruding portion 62c that protrudes so as to be positioned between adjacent column portions 50 of the fixing body 28. Therefore, a part of the circuit board 62 can also be present between the adjacent column portions 50 of the fixing body 28, which is advantageous for increasing the large area of the mounting surface 62d on which the circuit element 70 is mounted.

[0053] Refer to FIGS. 3 and 5. The fixed body 28 includes a reinforcing portion 90 provided on the column portion 50. The reinforcing portion 90 of this embodiment is provided in pairs on both circumferential sides of the column portion 50. The reinforcing portion 90 is constituted by convex portions that protrude axially outward in the column portion 50. The reinforcing portion 90 is provided to reinforce the column portion 50. The reinforcing portion 90 of this embodiment is provided to suppress the bending strain of the column portion 50 by increasing the rigidity against the bending deformation of the column portion 50. Here, the bending deformation and bending strain refer to the deformation and strain caused by the moment load acting to tilt the rotation center line of the output body 32. This is advantageous for accurately detecting the torque using the electrical signal indicating the shear strain of the strained portion 44. To achieve this, the reinforcing portion 90 of this embodiment includes a radially extending portion 90a provided on the circumferential side portion of the column portion 50 and extending in the radial direction. In addition to this, the reinforcing portion 90 of this embodiment includes a circumferentially extending portion 90b provided on the ring portion 42 and extending in the circumferential direction from the end of the radially extending portion 90a. The circumferentially extending portion 90b extends outward in the circumferential direction with respect to the column portion 50 where the reinforcing portion 90 is provided, from the end of the radially extending portion 90a.

[0054] The reinforcing portion 90 of this embodiment protrudes axially from the bottom surfaces of the first and second recesses 80 and 82. The radially extending portion 90a of the reinforcing portion 90 partially forms the first radially extending portion 82b of the first recess 80 and the second recess 82. The circumferentially extending portion 90b of the reinforcing portion 90 partially forms the circumferentially extending portion 82a of the second recess 82.

[0055] The above reinforcing portions 90 are provided in pairs corresponding to the circumferential side portions 52a of the pair of axially through holes 52. The pair of reinforcing portions 90 are interrupted at the outer radial side portion 52c, which is on the second recess 82 side of the fixed body 28 in the radial direction with respect to the axially through hole 52, among the pair of radial side portions 52b and 52c of the axially through hole 52. In FIG. 3, the interrupted portion S1 of this pair of reinforcing portions 90 is indicated by a two-dot chain line. Here, "interrupted" means that, when viewed from the axial direction, the pair of reinforcing portions 90 are not continuous at the mentioned radial side portion 52c, and they are provided at intervals. A second radially extending portion 82c, which is a part of the second recess 82, is provided at the radial side portion 52c of the axially through hole 52 at the interrupted portion S1 of the pair of reinforcing portions 90. The second protruding portion 62c of the circuit board 62 protrudes so as to be positioned between the adjacent column portions 50 while passing through the interrupted portion S1 where the pair of reinforcing portions 90 are interrupted, when viewed from the axial direction.

[0056] (G) Thereby, the interrupted portion S1 where the pair of reinforcing portions 90 are interrupted can be used as an arrangement space for the circuit board 62 accommodated in the second recess 82 of the fixed body 28, which is advantageous for increasing the large area of the mounting surface on which the circuit element 70 is mounted. Also, while securing the arrangement space for the circuit board 62 in this way, the column portions 50 of the fixed body 28 can be reinforced by the pair of reinforcing portions 90.

[0057] Refer to FIG. 1. A main bearing 92 is arranged between the fixed body 28 and the output body 32. The main bearing 92 of this embodiment is arranged between the casing 22 and the internal gear 18. In addition to this, the main bearing 92 may also be arranged between the casing 22 and the asynchronous carrier 24. The main bearing 92 can transmit the moment load input from the driven member 30 to the output body 32 to the fixed body 28. To achieve this, the main bearing 92 of this embodiment is constituted by a cross roller bearing, but it may also be constituted by a four-point contact ball bearing or the like. In addition to this, to achieve this, a plurality of main bearings 92 may be provided at intervals in the axial direction. In this case, the main bearings 92 may be constituted by various bearings such as, for example, deep groove ball bearings and angular ball bearings.

[0058] The fixed body 28 includes fixing portions 46 and 94 that are fixed to the external member 26. The fixing portions 46 and 94 include, in addition to the aforementioned first fixing portion 46 provided on the second ring portion 42 of the synchronous carrier 20, a second fixing portion 94 provided on the casing 22. The first fixing portion 46 of the synchronous carrier 20 and the second fixing portion 94 of the casing 22 in this embodiment are fixed to the external member 26 by a common fixture 48. The second fixing portion 94 of the casing 22 is formed at a location where a second through hole 94a for passing the fixture 48 axially overlaps with the first through hole 46a.

[0059] The reduction gear 10 is provided with a load transmission path 96 that extends from the output body 32 through the main bearing 92 and the fixed body 28 to the external member 26. Here, an arrow is attached to a part of the load transmission path 96 for indication. The load transmission path 96 can transmit the load input from the driven member 30 to the output body 32 to the external member 26. This "load" mainly assumes a moment load, but may also include an axial load and a radial load. In this embodiment, on this load transmission path 96, in addition to the second fixing portion 94 of the casing 22 of the fixed body 28, the first fixing portion 46 of the second ring portion 42 of the synchronous carrier 20 is provided.

[0060] The strain generating portion 44 of the fixed body 28 is provided at a location different from this load transmission path 96. In addition to the strain generating portion 44, the first ring portion 40 of the fixed body 28 is also provided at a location different from this load transmission path 96. Although torque is transmitted from the first ring portion 40 during the operation of the speed reduction device 10, the strain generating portion 44 is provided at a location different from the load transmission path 96 that transmits moment loads and the like. Under the condition of satisfying this, the strain generating portion 44 of the present embodiment is provided in a part of the synchronous carrier 20 that is integrated with the casing 22 while torque is transmitted from the external gear 16 via the pin 36. In integrating the casing 22 and the synchronous carrier 20 in this way, the second ring portion 42 of the synchronous carrier 20 may be directly fixed to the external member 26 as in the present embodiment, or may be fixed to the external member 26 via the casing 22 that is directly fixed to the external member 26. Further, in order to be provided at a location different from the load transmission path 96, the strain generating portion 44 of the present embodiment is provided at a position shifted radially inward with respect to the second ring portion 42 fixed to the external member 26.

[0061] When the bending strain generated in the strain generating portion 44 of the fixed body 28 increases due to a moment load acting on the strain generating portion 44, it is known that the detection accuracy of torque is reduced when detecting torque using the electrical signal of the strain sensor 60 that indicates the shear strain of the strain generating portion 44. The strain generating portion 44 of the fixed body 28 is provided at a location different from the load transmission path 96 that transmits the moment load that causes such a reduction in detection accuracy. Thereby, it becomes difficult for bending strain to occur in the strain generating portion 44, which is advantageous for accurately detecting torque as described above.

[0062] (Second Embodiment) Refer to FIG. 7. In the following embodiments, among the components described in the first embodiment, the components not described below may have the same content applied as in the first embodiment.

[0063] In the reduction gear 10 of the embodiment of FIG. 1, the casing 22 and the internal gear 18 were provided separately. In contrast, the reduction gear 10 of this embodiment is different in that the casing 22 and the internal gear 18 are integrated. On the premise of satisfying this condition, at least the internal gear body 18a of the internal gear 18 among the internal gear body 18a and the plurality of internal teeth 18b constituting the internal gear 18 may be integrated with the casing 22.

[0064] In the reduction gear 10 of the embodiment of FIG. 1, a synchronous carrier 20 and an asynchronous carrier 24 were provided on both axial sides with respect to the external gear 16. In contrast, in the reduction gear 10 of this embodiment, a pair of synchronous carriers 20 are provided on both axial sides with respect to the external gear 16. Each synchronous carrier 20 is connected via a pin 36, and both can be synchronized with the rotation component of the external gear 16.

[0065] The fixed body 28 of the embodiment of FIG. 1 is composed of the synchronous carrier 20 and the casing 22, and the output body 32 is composed of the asynchronous carrier 24 and the internal gear 18. In contrast, the fixed body 28 of this embodiment is composed of the internal gear 18 and the casing 22, and the output body 32 is composed of each synchronous carrier 20. Different from the form of FIG. 1, a pair of main bearings 92 are arranged at an axial interval between the output body 32 and the fixed body 28. Each of the pair of main bearings 92 is arranged between an individual synchronous carrier 20 and the casing 22.

[0066] The first and second ring portions 40, 42 and the distortion generating portion 44 of the fixed body 28 of this embodiment are provided on the casing 22 integrated with the internal gear 18. These are provided on a single member constituting the casing 22, similar to the embodiment of FIG. 1. The first ring portion 40 of the fixed body 28 constitutes an inner ring portion, and the second ring portion 42 constitutes an outer ring portion. A plurality of internal teeth 18b are provided on the inner peripheral portion of the first ring portion 40 of this embodiment. Also, a main bearing 92 is arranged on the inner peripheral portion of the first ring portion 40 of this embodiment. When the internal gear 18 becomes at least a part of the fixed body 28 as in this embodiment, the torque transmitted from the internal teeth 18b of the internal gear 18 is input to the first ring portion 40 of the fixed body 28.

[0067] Refer to FIG. 8. The strain generating portion 44 of the fixed body 28 of this embodiment also includes a first recess 80 for housing the strain sensor 60. Further, the second ring portion 42 of the fixed body 28 of this embodiment also includes a second recess 82 for housing the circuit board 62. The circuit board 62 of this embodiment also includes a first protruding portion 62b that protrudes into the first recess 80 of the fixed body 28.

[0068] As described above, the speed reducer 10 of this embodiment includes the components described in (A) to (E) above, and the effects corresponding to those descriptions can be obtained. Further, the speed reducer 10 of this embodiment includes, in addition to the second protruding portion 62c of the circuit board 62 described in (F) above, the features related to the reinforcing portion 90 of the fixed body 28 in (G), and the effects corresponding to those descriptions can be obtained.

[0069] Note that, in the speed reducer 10 of this embodiment, unlike the first embodiment, the strain generating portion 44 of the fixed body 28 is provided in the load transmission path 96 from the output body 32 via the main bearing 92 and the fixed body 28 to the external member 26. In this case, unlike the first embodiment, a moment load is transmitted to the strain generating portion 44 of the fixed body 28, which may cause a decrease in detection accuracy when detecting torque using the electrical signal of the strain sensor 60 indicating the shear strain of the strain generating portion 44. As a countermeasure, various methods including known methods may be adopted to suppress the influence of the bending strain generated in the strain generating portion 44.

[0070] As this method, for example, a dedicated strain sensor for detecting the bending strain generated in the fixed body 28 may be installed on the fixed body 28. In this case, based on the electrical signal of the dedicated strain sensor indicating the bending strain of the strain generating portion 44, the electrical signal of the strain sensor 60 indicating the shear strain of the strain generating portion 44 may be corrected to reduce the bending strain component included in the electrical signal of the strain sensor 60.

[0071] In addition to this, as this method, individual strain sensors 60 may be installed on both axial sides of the strain generating portion 44 of the fixed body 28, and the individual strain sensors 60 may be arranged on opposite sides of the bridge circuit to cancel out the bending strain components included in the electrical signals of the individual strain sensors 60.

[0072] In addition to this, in order to suppress the influence of the bending strain component included in the electric signal of the strain sensor 60, a machine learning model may be used. This machine learning model is trained to output a torque with the influence of the bending strain component included in the electric signal of the strain sensor 60 reduced when an electric signal of the strain sensor 60 indicating the shear strain of the strained portion 44 is input. This machine learning model is, for example, a neural network such as an artificial neural network (ANN: Artificial Neuronal Network).

[0073] (Third Embodiment) Refer to FIG. 9. The entire circuit board 62 of the first embodiment is constituted by a rigid board. The circumferential portion 62a of the circuit board 62 of this embodiment is constituted by a rigid board 100, and the first protruding portion 62b is constituted by a flexible board 102. The flexible board 102 is connected to the rigid board 100 by various connection methods including known methods. The second protruding portion 62c is constituted by the rigid board 100 common to the circumferential portion 62a, but may be constituted by the flexible board 102. Further, both the circumferential portion 62a and the first protruding portion 62b of the circuit board 62 may be constituted by the flexible board 102.

[0074] When the strained portion 44 is deformed more than the respective ring portions 40, 42 due to the torque acting on the fixed body 28, the strain sensor 60 provided on the strained portion 44 and the circuit board 62 provided on the ring portion 42 tend to move relative to each other in the circumferential direction. The flexible board 102 can be flexibly deformed following such relative movement of the circuit board 62 and the strain sensor 60. At this time, the flexible board 102 of this embodiment can be mainly sheared in the circumferential direction, but can also be deformed in the axial direction. Although not shown, the flexible board 102 is provided with a slight gap with respect to the axial side surface of the fixed body 28 in order to allow its own flexible deformation, and is not fixed to the fixed body 28 by an adhesive or the like. On the other hand, the circumferential portion 62a of the circuit board 62 constituted by the rigid board 100 is fixed to the ring portion 42 of the fixed body 28 by an adhesive or the like.

[0075] Accordingly, when the strain sensor 60 and the circuit board 62 attempt to move relative to each other in the circumferential direction, the flexible board 102 deforms, thereby avoiding a situation where a local large load acts on the connection portion between the strain sensor 60 and the circuit board 62 and the conductive connection material 76. Consequently, it is possible to suppress the occurrence of a connection failure in which the strain sensor 60 and the circuit board 62 are not electrically connected due to the separation of either the sensor electrode 66 of the strain sensor 60 or the board electrode 72 of the circuit board 62 from the conductive connection material 76. This connection failure can occur, for example, when the conductive connection material 76 is broken by a local large load.

[0076] In addition, when thermal expansion occurs in the strained portion 44 of the fixed body 28 or vibration is input to the strained portion 44, the strain sensor 60 installed in the strained portion 44 may attempt to shift relative to the rigid board 100 of the circuit board 62. At this time, the flexible board 102 of the circuit board 62 deforms flexibly, thereby avoiding a situation where a large load acts on the connection portion between the circuit board 62 and the conductive connection material 76. Also, the flexible board 102 is thinner in the axial direction than the rigid board 100. Therefore, the axial dimension from the main surface on the outer side in the axial direction of the circuit board 62 (the main surface of the flexible board 102) to the main surface of the strain sensor 60 can be reduced. This also has the advantage that it becomes easier to provide the conductive connection material 76 so as to cover the main surface side portion of the board electrode 72 located on the main surface of the circuit board 62 and the sensor electrode 66 located on the main surface of the strain sensor 60.

[0077] Next, a modified form of each component described so far will be described.

[0078] As a specific type of the eccentric swing type reduction gear 10, the center crank type in which the crankshaft 14 is arranged on the swing center C16a of the external gear 16 has been described. This specific type is not particularly limited, and for example, a distribution type in which a plurality of crankshafts 14 are arranged at positions offset radially from the swing center C16a of the external gear 16 may also be used.

[0079] In the first embodiment, the fixed body 28 is constituted by at least the synchronizing carrier 20, and the output body 32 is constituted by at least the internal gear 18. Further, in the second embodiment, the fixed body 28 is constituted by at least the internal gear 18, and the output body 32 is constituted by the synchronizing carrier 20. Thus, one of the internal gear 18 and the synchronizing carrier 20 may constitute at least a part of the fixed body 28, and the other may constitute at least a part of the output body 32.

[0080] In the case where one of the internal gear 18 and the synchronizing carrier 20 constitutes at least a part of the fixed body 28, the presence or absence of other components of the fixed body 28 is not questioned, and the specific examples of the components are not particularly limited. Similarly, in the case where the other of the internal gear 18 and the synchronizing carrier 20 constitutes at least a part of the output body 32, the presence or absence of other components of the output body 32 is not questioned, and the specific examples of the components are not particularly limited.

[0081] An example in which the first ring portion 40 of the fixed body 28 constitutes the inner ring portion and the second ring portion 42 constitutes the outer ring portion has been described. Alternatively, the first ring portion 40 may constitute the outer ring portion and the second ring portion 42 may constitute the inner ring portion.

[0082] The strain generating portion 44 of the fixed body 28 may not include the first concave portion 80. Both the first and second ring portions 40 and 42 of the fixed body 28 may not include the second concave portion 82. Instead of the second ring portion 42 of the fixed body 28, the first ring portion 40 may include the second concave portion 82.

[0083] The circuit board 62 may not include each of the first protruding portion 62b and the second protruding portion 62c, or may include only one of them. Further, the number of the first protruding portion 62b and the second protruding portion 62c is not particularly limited.

[0084] The pair of reinforcing portions 90 may not be interrupted at the radial side portions of the pair of radial side portions 52b and 52c of the axially through hole 52, which are on the second concave portion 82 side of the circuit board 62 in the radial direction.

[0085] In providing the strain generating portion 44 of the fixed body 28 at a location different from the above-described load transmission path 96, at least a part of the fixed body 28 does not have to be constituted by the synchronous carrier 20 and the casing 22 as in the first embodiment.

[0086] The above embodiments and modified forms are examples. The technical ideas abstracted from these should not be construed as being limited to the contents of the embodiments and modified forms. Many design changes such as changes, additions, and deletions of components are possible for the contents of the embodiments and modified forms. In the above-described embodiments, with respect to the contents for which such design changes are possible, the notation "embodiment" is attached and emphasized. However, design changes are also permitted for the contents without such notation. The hatching attached to the cross-section of the drawing does not limit the material of the object to which the hatching is attached.

[0087] Any combination of the above components is also effective. For example, any explanatory matter of other embodiments may be combined with an embodiment, or any explanatory matter of an embodiment and other modified forms may be combined with a modified form. A component configured by a single member in an embodiment may be configured by a plurality of members. Similarly, a component configured by a plurality of members in an embodiment may be configured by a single member.

Explanation of Reference Numerals

[0088] 10... Eccentric swing type reduction gear, 12... Eccentric body, 16... External gear, 18... Internal gear, 20... Carrier, 22... Casing, 26... External member, 28... Fixed body, 32... Output body, 40... First ring portion, 42... Second ring portion, 44... Strain generating portion, 50... Column portion, 52... Axial through hole, 52a... Circumferential side portion, 52b, 52c... Radial side portions, 60... Strain sensor, 62... Circuit board, 62a... Circumferential portion, 62b... First protruding portion, 62c... Second protruding portion, 76... Conductive connecting material, 80... First recess, 82... Second recess, 90... Reinforcing portion, 92... Main bearing, 96... Load transmission path, 102... Flexible board.

Claims

1. An eccentric body, an external gear that can be swung by the eccentric body, an internal gear that meshes with the external gear, and a carrier that can be synchronized with the rotation component of the external gear, and is an eccentric swing type reduction gear device, one of the internal gear and the carrier constitutes at least a part of a fixed body fixed to an external member, the fixed body includes a first ring portion, a second ring portion provided radially apart from the first ring portion and fixed to the external member, and a strain generating portion provided between the first ring portion and the second ring portion, An eccentric swing type reduction gear device in which a strain sensor is installed in the strain generating portion.

2. The eccentric swing type reduction gear device according to claim 1, wherein the strain generating portion includes a first recess for housing the strain sensor.

3. The eccentric swing type reduction gear device according to claim 1, further comprising a circuit board to which the strain sensor is electrically connected.

4. The eccentric swing type reduction gear device according to claim 3, wherein one of the first ring portion and the second ring portion includes a second recess for housing at least a part of the circuit board.

5. The strain generating portion includes a first recess for housing the strain sensor, The eccentric swing type reduction gear device according to claim 3, wherein the circuit board includes a first protruding portion that protrudes into the first recess and is connected to the strain sensor.

6. The eccentric swing type reduction gear device according to claim 3, wherein the circuit board includes a circumferential portion axially opposed to one of the first ring portion and the second ring portion, and a first protruding portion that protrudes radially from the circumferential portion and is electrically connected to the strain sensor.

7. The first protruding portion and the strain sensor are electrically connected via a conductive connecting material, The first protruding portion is the eccentric swing type reduction gear according to claim 5 or 6, which is composed of a flexible substrate.

8. The distortion generating portion is the eccentric swing type reduction gear according to claim 3, which includes a plurality of column portions provided at intervals in the circumferential direction.

9. The circuit board is the eccentric swing type reduction gear according to claim 8, which includes a second protruding portion that protrudes so as to be located between adjacent column portions when viewed from the axial direction.

10. The fixed body includes an axially penetrating hole formed between adjacent column portions, and a pair of reinforcing portions provided respectively at circumferential side portions of a pair of the axially penetrating holes. One of the first ring portion and the second ring portion includes a second recess for accommodating at least a part of the circuit board. The pair of reinforcing portions is interrupted at a radial side portion of the axially penetrating hole that is on the second recess side in the radial direction with respect to the axially penetrating hole. The eccentric swing type reduction gear according to claim 8.

11. The other of the internal gear and the carrier constitutes at least a part of an output body that outputs rotation. A main bearing is disposed between the output body and the fixed body. The distortion generating portion is provided at a location different from a load transmission path from the output body, through the main bearing and the fixed body, to the external member. The eccentric swing type reduction gear according to claim 1.

12. It includes a casing provided on the radially outer side of the external gear. The fixed body is at least partially constituted by the casing and the carrier. The distortion generating portion is provided on the carrier. The eccentric swing type reduction gear according to claim 11.

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