Power transmission device

Abstract

This technology provides a way to move bolts through a new movement path while avoiding interference with the reduction gear unit during bolt insertion. [Solution] A power transmission device 10 equipped with a reduction gear 12, wherein the reduction gear 12 is provided with a first bolt hole 46 for inserting bolts 52 for fastening the reduction gear 12 to an external member 44, and the reduction gear 12 is provided with an outer peripheral opening 70 that opens outward from a position overlapping the first bolt hole 46 in the axial direction X, and the outer peripheral opening 70 is provided in the first bolt hole 46.

Description

Technical Field

[0001] The present disclosure relates to a power transmission device.

Background Art

[0002] Patent Document 1 discloses a power transmission device including a speed reducer and an adapter that connects the speed reducer and a motor. The speed reducer generally includes bolt holes for inserting bolts for fixing the speed reducer to an external member.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor of the present application has found a new idea that enables a bolt to be moved through a new movement path while avoiding interference with the power transmission device during the operation of inserting the bolt into the bolt hole (hereinafter also referred to as the bolt insertion operation).

[0005] One object of the present disclosure is to provide a technique that enables a bolt to be moved through a new movement path while avoiding interference with the power transmission device during the bolt insertion operation.

Means for Solving the Problems

[0006] The power transmission device of the present disclosure is a power transmission device including a speed reducer and an adapter that connects the speed reducer and a motor, wherein the speed reducer includes a first bolt hole for inserting a bolt for fastening the speed reducer to an external member, and at least one of the adapter or the motor includes an outer peripheral opening that opens from a position axially overlapping the first bolt hole toward the outer peripheral side.

[0007] Other power transmission devices of the present disclosure include a reduction gear connected to a motor via an adapter, wherein the reduction gear has a first bolt hole for inserting bolts for fastening the reduction gear into an external member, and the reduction gear has an outer peripheral opening that opens outward from a position overlapping the first bolt hole in the axial direction, and the outer peripheral opening is provided in the first bolt hole. [Effects of the Invention]

[0008] According to this disclosure, it is possible to move the bolt through a new movement path while avoiding interference with the power transmission device during the bolt insertion operation. [Brief explanation of the drawing]

[0009] [Figure 1] This is a side cross-sectional view of the power transmission device of the first embodiment. [Figure 2] This is a view of a part of the power transmission device of the first embodiment, as seen from the motor side. [Figure 3] This is a side cross-sectional view showing an intermediate state during the bolt insertion process in the first embodiment. [Figure 4] This is a partial perspective view of the notch from the direction of arrow V1 in Figure 1. [Figure 5] This is a side cross-sectional view showing a part of the power transmission device of the second embodiment. [Figure 6] This is a partial perspective view of the notch from the direction of arrow V2 in Figure 5. [Figure 7] This is a side cross-sectional view showing a part of the power transmission device of the third embodiment. [Figure 8] This is a partial perspective view of the notch from the direction of arrow V3 in Figure 7. [Figure 9] This is a side cross-sectional view showing the intermediate state during the bolt insertion process in the third embodiment. [Figure 10] This is a side cross-sectional view of the power transmission device of the fourth embodiment. [Modes for carrying out the invention]

[0010] The embodiments are described below. The same reference numerals are used for identical components, and redundant explanations are omitted. For the sake of clarity, components are omitted, enlarged, or reduced in each drawing. The drawings should be viewed in accordance with the orientation of the reference numerals.

[0011] (First Embodiment) Refer to Figures 1 and 2. Figure 1 is also a cross-sectional view AA of Figure 2. The power transmission device 10 comprises a reduction gear 12, a motor 14, and an adapter 16 connecting the reduction gear 12 and the motor 14. The motor 14 comprises a motor casing 14a that houses a stator and rotor (not shown), and a motor shaft 14b that rotates integrally with the rotor.

[0012] The reduction gear 12 includes an input shaft 18 to which input rotation is input from the motor shaft 14b of the motor 14, a gear mechanism 20 to which the rotation of the input shaft 18 is transmitted, and an output member 22 that outputs output rotation transmitted from the gear mechanism 20 to the driven member. In addition, the reduction gear 12 includes a cylindrical reduction gear casing 24 that houses the gear mechanism 20, and carriers 26A and 26B that are arranged axially laterally with respect to the external gears 28 that constitute the gear mechanism 20.

[0013] The gear mechanism 20 of this embodiment is an eccentric oscillating gear mechanism comprising an external gear 28 and an internal gear 30 that mesh with each other. This type of gear mechanism 20 can transmit output rotation to the output member 22 by oscillating one of the external gear 28 and the internal gear 30 (in this case, the external gear 28) by a crankshaft 34. In this embodiment, an example in which the carrier 26A is the output member 22 is described, but the reduction gear casing 24 may also be the output member 22.

[0014] Hereinafter, the direction along the center line C24 of the gearbox casing 24 will be referred to as the axial direction X, and the radial direction and circumferential direction, respectively, with the center line C24 as the center of the circle, will be simply referred to as the radial direction and circumferential direction. Furthermore, the side with the motor 14 in the axial direction X will be referred to as the motor side, and the side opposite to the motor 14 in the axial direction will be referred to as the anti-motor side.

[0015] The motor shaft 14b and the input shaft 18 are connected so as to be integrally rotatable. To achieve this, the motor shaft 14b and the input shaft 18 of the present embodiment are connected using a friction fastening device 32. The method of connecting the motor shaft 14b and the input shaft 18 is not particularly limited, and for example, a key or the like may be used.

[0016] The input shaft 18 of the present embodiment is a crankshaft 34. The crankshaft 34 includes at least one (here, three) eccentric bodies 36 that are eccentric with respect to the rotation center C34 of the crankshaft 34. By rotating around the rotation center C34 of the crankshaft 34, the eccentric body 36 can swing the external gear 28.

[0017] The external gear 28 is supported so as to be relatively rotatable with respect to the eccentric body 36 of the crankshaft 34 via a gear bearing 38. The internal gear 30 is integrated with the speed reducer casing 24. A main bearing 40 that connects the speed reducer casing 24 and the carriers 26A and 26B so as to be relatively rotatable is disposed between the speed reducer casing 24 and the carriers 26A and 26B.

[0018] The carriers 26A and 26B include a counter-motor-side carrier 26A provided on the counter-motor side with respect to the external gear 28 and a motor-side carrier 26B provided on the motor side with respect to the external gear 28. The carriers 26A and 26B can be synchronized with the rotation component of the external gear 28 when the external gear 28 swings by an inner pin 42 that penetrates the external gear 28.

[0019] The speed reducer casing 24 includes a first bolt hole 46 for inserting a bolt 52 that fastens the speed reducer 12 to an external member 44. In FIG. 2, only the first bolt hole 46 with respect to the speed reducer 12 is shown. A plurality of first bolt holes 46 are provided at intervals in the circumferential direction. The bolt 52 is inserted into the first bolt hole 46 from the motor side. In order to fasten the external member 44 and the speed reducer 12 with the bolt 52, the bolt 52 may be screwed into a female screw formed in the third bolt hole 44a of the external member 44. Alternatively, the bolt 52 may be screwed into a nut provided separately from the external member 44.

[0020] ​The gearbox 12 includes an external member mounting portion 24a to which an external member 44 is attached. In this embodiment, the external member mounting portion 24a is provided on the gearbox casing 24. In this embodiment, the external member mounting portion 24a is a flange portion that protrudes radially outward from the outer circumference of the gearbox casing 24. The first bolt hole 46 is provided on the external member mounting portion 24a. An adapter 16 is positioned on the motor side of the external member mounting portion 24a.

[0021] The adapter 16 comprises a motor fixing portion 16a fixed to the motor 14 and a reduction gear fixing portion 16b fixed to the reduction gear 12. The adapter 16 in this embodiment comprises a first adapter member 48 fixed to the motor 14 and a second adapter member 50 fixed to the reduction gear 12 and separate from the first adapter member 48. The first adapter member 48 has the motor fixing portion 16a, and the second adapter member 50 has the reduction gear fixing portion 16b. The first adapter member 48 and the second adapter member 50 have a hollow structure, and the motor shaft 14b and a part of the input shaft 18 are inserted inside them. The first adapter member 48 and the second adapter member 50 are detachably connected. To achieve this, in this embodiment, they are connected using a bolt B1 inserted into the inside of the first adapter member 48 from the motor side. By changing only the first adapter member 48 according to the size of the motor 14, the second adapter member 50 can be shared when connecting multiple types of motors 14 and reduction gears 12 using the adapter 16.

[0022] In this embodiment, the motor fixing portion 16a is an adapter flange portion that protrudes radially outward at the motor-side end of the adapter 16. The motor fixing portion 16a is fixed to the motor 14 by overlapping it in the axial direction X with the motor flange portion 14c provided on the motor casing 14a of the motor 14 and fastening it with a bolt B2. The motor fixing portion 16a in this embodiment is provided with a female screw hole 16d into which the bolt B2 is screwed. When the first adapter member 48 is fixed to the motor 14, the motor 14 overlaps the bolt B1 inside the first adapter member 48 in the axial direction, and the bolt B1 is hidden by the motor 14. In this state, the connection by the bolt B1 cannot be released, and the second adapter member 50 cannot be attached to or detached from the first adapter member 48.

[0023] The gearbox fixing portion 16b of this embodiment is fixed to the gearbox casing 24 of the gearbox 12. The gearbox fixing portion 16b is fixed to the gearbox casing 24 by overlapping the external member mounting portion 24a of the gearbox casing 24 in the axial direction X and fastening it with bolts 52. The gearbox fixing portion 16b is provided with a second bolt hole 16c through which the bolts 52 are inserted. The gearbox fixing portion 16b is fitted in a spigot joint with a splice portion 24b provided on the motor side of the gearbox casing 24, which is located on the motor side of the external member mounting portion 24a.

[0024] The external member 44 is positioned outside the power transmission device 10. The external member 44 can be either a support member that supports the power transmission device 10 or a driven member that is driven by the power transmission device 10. In this embodiment, when the output member 22 is a carrier 26A, the external member 44 becomes a support member. In addition, when the output member 22 is a gearbox casing 24, the external member 44 becomes a driven member.

[0025] The external member 44 is positioned on the side opposite the motor to the external member mounting portion 24a of the reduction gear 12. The external member 44 includes a third bolt hole 44a through which a bolt 52 is inserted. In this embodiment, the third bolt hole 44a has a female thread on its inner circumferential surface, into which the shaft portion 52a of the bolt 52 is screwed. The first bolt hole 46 and the second bolt hole 16c are through holes that do not have a female thread on their inner circumferential surface and penetrate in the axial direction X. The first bolt hole 46, the second bolt hole 16c, and the third bolt hole 44a are in communication with each other. The external member 44 also includes an insertion hole 44b through which a portion of the reduction gear 12 on the side opposite the motor is inserted.

[0026] The operation of the power transmission device 10 described above will be briefly explained. When the input rotation of the motor 14 is transmitted to the input shaft 18, the gear mechanism 20 is activated. When the gear mechanism 20 is activated, the output rotation, which is reduced relative to the input rotation, is transmitted from the gear mechanism 20 to the output member 22, and that output rotation is transmitted to the driven member.

[0027] Here, on the motor side of the bolt 52, at a position that overlaps with the bolt 52 in the axial direction X, a part of the adapter 16 or at least one of the motor 14 is positioned. In this embodiment, both the motor fixing part 16a, which is part of the adapter 16, and the motor 14 are positioned. Alternatively, only a part of the adapter 16 or only the motor 14 may be positioned on the motor side of the bolt 52.

[0028] Refer to Figure 3. The power transmission device 10 is provided with a bolt arrangement space 60 outside the power transmission device 10 for positioning the bolt 52 to be inserted into the first bolt hole 46 during the bolt insertion operation. The bolt arrangement space 60 is provided in a position that overlaps with the bolt 52 in the axial direction X. The bolt arrangement space 60 is open radially outward so that the bolt 52 can pass through during the bolt insertion operation.

[0029] The bolt arrangement space 60 is provided between two outer surfaces 62A and 62B that face each other in the axial direction X. The inner surface of the outer peripheral opening 70, which will be described later, is excluded from the "outer surfaces 62A and 62B" here. The two outer surfaces 62A and 62B here include the motor-side outer surface 62A on the motor side and the non-motor-side outer surface 62B on the opposite side of the motor. In this embodiment, the motor-side outer surface 62A is provided on the motor fixing portion 16a of the adapter 16, and the non-motor-side outer surface 62B is provided on the gearbox fixing portion 16b of the adapter 16. The motor-side outer surface 62A is provided on the first adapter member 48, and the non-motor-side outer surface 62B is provided on the second adapter member 50. In this embodiment, the motor-side outer surface 62A is removed when the first adapter member 48 is removed from the second adapter member 50.

[0030] Refer to Figures 1, 3, and 4. At least one of the reducer 12, motor 14, and adapter 16 is provided with an outer peripheral opening 70 that opens outward from a position overlapping with the first bolt hole 46 in the axial direction X. In this embodiment, the adapter 16 is provided with the outer peripheral opening 70. The outer peripheral opening 70 of the adapter 16 is provided with a first opening edge 70a that opens to the outer peripheral surface of the adapter 16. The outer peripheral opening 70 of the adapter 16 is provided by cutting out a part of the adapter 16 so as to be recessed relative to the outer peripheral surface of the adapter 16. The outer peripheral opening 70 opens toward the external space 72 through the first opening edge 70a. In this embodiment, the outer peripheral opening 70 opens radially outward. The direction in which the outer peripheral opening 70 opens is not particularly limited and may be, for example, tangential to the outer peripheral surface of the reducer 12, motor 14, or adapter 16 on which the outer peripheral opening 70 is provided.

[0031] This allows the bolt 52 to be moved through the outer periphery opening 70 to the position just before insertion P1 by inserting the bolt 52 into the outer periphery opening 70 from the first opening edge 70a during the bolt insertion operation. The position just before insertion P1 here refers to the position on the motor side of the first bolt hole 46 where the shaft portion 52a of the bolt 52 overlaps with the first bolt hole 46 in the axial direction X. Furthermore, the position just before insertion P1 here is also the position in which the bolt 52 is positioned just before being moved axially towards the first bolt hole 46 during the bolt insertion operation.

[0032] The outer peripheral opening 70 includes a first opening edge 70a, a second opening edge 70b that opens toward the bolt arrangement space 60 in the axial direction X, and a bottom portion 70c provided further inward in the axial direction X than the second opening edge 70b. In this embodiment, the outer peripheral opening 70 is provided on the side opposite the motor relative to the bolt arrangement space 60, and its second opening edge 70b opens toward the outer surface portion 62B on the side opposite the motor. In this case, the shaft portion 52a of the bolt 52 can be inserted into the outer peripheral opening 70 from the first opening edge 70a during bolt insertion. In addition, as in the third embodiment described later, when the outer peripheral opening 70 is provided on the motor side relative to the bolt arrangement space 60, the head portion 52b of the bolt 52 can be inserted into the outer peripheral opening 70 from the first opening edge 70a during bolt insertion.

[0033] The outer peripheral opening 70, when the bolt 52 is fastened, radially overlaps with a portion of the shaft portion 52a of the bolt 52. Here, "a portion" refers to a portion of the shaft portion 52a that extends from the motor-side end toward the opposite motor side. To satisfy this condition, the outer peripheral opening 70 in this embodiment is provided in the second bolt hole 16c (reducer fixing portion 16b) of the adapter 16. In this embodiment, the outer peripheral opening 70 is provided in the second bolt hole 16c in an axial range that extends from the motor-side end of the second bolt hole 16c toward the opposite motor side, leaving a portion of it on the opposite motor side. The axial dimension L70 of the outer peripheral opening 70 is longer than the axial dimension L52b of the head 52b of the bolt 52. When viewed from the axial direction X, the outer peripheral opening 70 is large enough to accommodate the shaft portion 52a of the bolt 52, but not large enough to accommodate the head 52b of the bolt 52. A portion of the shaft portion 52a of the bolt 52 is exposed to the outside space through the outer peripheral opening 70. Furthermore, a seating surface 74 is provided on the outer surface 62B on the side opposite the motor, on which the head 52b of the bolt 52 rests.

[0034] In this embodiment, the axial dimension L52 of the bolt 52 (hereinafter also referred to as the bolt dimension L52) is larger than the axial dimension L60 of the bolt arrangement space 60. Furthermore, the bolt dimension L52 is smaller than the sum of the axial dimension L70 of the outer peripheral opening 70 and the axial dimension L60 of the bolt arrangement space 60.

[0035] Refer to Figure 3. The bolt insertion procedure for inserting a bolt 52 into the first bolt hole 46 will be described. In the bolt insertion procedure, the bolt 52 is moved to the aforementioned pre-insertion position P1 immediately before inserting it into the first bolt hole 46. The bolt 52 is moved to the pre-insertion position P1 through both the outer peripheral opening 70 and the external space 72 (here, the bolt arrangement space 60) of the power transmission device 10. At this time, as described above, the bolt 52 is moved to the pre-insertion position P1 through the outer peripheral opening 70 by inserting the bolt 52 into the outer peripheral opening 70 from the first opening edge 70a. Once the bolt 52 has been moved to the pre-insertion position P1, the shaft portion 52a of the bolt 52 is inserted into the first bolt hole 46 by moving the bolt 52 axially X toward the first bolt hole 46. After this, the external member 44 and the reduction gear 12 are fastened together and the reduction gear 12 is fixed to the external member 44 by screwing the bolt 52 into the female thread of the third bolt hole 44a of the external member 44 or into a nut separate from the external member 44.

[0036] The effects of the power transmission device 10 described above will now be explained.

[0037] (A) If the power transmission device 10 does not have an outer peripheral opening 70, the only way to move the bolt 52 to the position P1 just before insertion while avoiding interference with the power transmission device 10 during bolt insertion is to move it through the external space of the power transmission device 10 (in this case, the bolt arrangement space 60). In this respect, the adapter 16 of this embodiment is provided with an outer peripheral opening 70 that is located at a position that overlaps with the first bolt hole 46 in the axial direction X. Therefore, by inserting the bolt 52 into the outer peripheral opening 70 from the first opening edge 70a, the bolt 52 can be moved through the outer peripheral opening 70 to the position P1 just before insertion. In other words, in order to move the bolt 52 to the position P1 just before insertion while avoiding interference with the power transmission device 10 during bolt insertion, it is possible to move the bolt 52 through a new movement path that passes through both the outer peripheral opening 70 and the external space 72.

[0038] If the power transmission device 10 does not have an outer periphery opening 70, and there is a bolt placement space 60 outside the power transmission device 10, then in order to position the bolt 52 at the position P1 just before insertion, the entire bolt 52 must be placed in the bolt placement space 60. In this case, if a bolt 52 with a bolt dimension L52 longer than the axial dimension L60 of the bolt placement space 60 is used, the power transmission device 10 and the bolt 52 will interfere with each other. To avoid this, if the axial dimension L60 of the bolt placement space 60 is widened beyond the bolt dimension L52 while keeping the size of the bolt dimension L52 the same, it will lead to an increase in the axial dimension of the power transmission device 10.

[0039] (B) In this embodiment, the bolt dimension L52 is made longer than the axial dimension L60 of the bolt arrangement space 60, while the power transmission device 10 is equipped with the aforementioned outer peripheral opening 70. Therefore, by moving the bolt 52 so that it passes through the outer peripheral opening 70 of the power transmission device 10 and the bolt arrangement space 60, even a bolt 52 with a bolt dimension L52 that is longer than the axial dimension L60 of the bolt arrangement space 60 can be moved to the position P1 just before insertion without interfering with the power transmission device 10. At this time, the axial dimension L60 of the bolt arrangement space 60 that is necessary to avoid interference between the power transmission device 10 and the bolt 52 when moving the bolt 52 to the position P1 just before insertion can be reduced by the amount of the axial dimension L70 of the outer peripheral opening 70. For this reason, the axial dimensions of the power transmission device 10 can be made smaller compared to the case where the axial dimension L60 of the bolt arrangement space 60 is widened to the bolt dimension L52 while keeping the size of the bolt dimension L52 the same in order to avoid interference with the power transmission device 10.

[0040] (C) The adapter 16 of this embodiment comprises a first adapter member 48 fixed to the motor 14 and a second adapter member 50 fixed to the reduction gear 12. If the bolt length L52 is longer than the axial length L60 of the bolt arrangement space 60, one could consider removing the motor-side outer surface portion 62A that forms the bolt arrangement space 60 by removing the second adapter member 50 from the first adapter member 48 in order to avoid interference with the power transmission device 10 during bolt insertion work. In this respect, according to this embodiment, even if the bolt length L52 is longer than the axial length L60 of the bolt arrangement space 60, the aforementioned outer peripheral opening 70 makes it possible to avoid interference between the power transmission device 10 and the bolt 52 during bolt insertion work without removing the second adapter member 50 from the first adapter member 48. Therefore, it is possible to reduce the axial length of the power transmission device 10 while preventing a decrease in ease of assembly during bolt insertion work.

[0041] When the bolt 52 is fastened, the outer peripheral opening 70 overlaps radially with a portion of the shaft portion 52a of the bolt 52. Therefore, compared to the case where the outer peripheral opening 70 is positioned to overlap radially only with the head portion 52b of the bolt 52, the axial dimension L70 of the outer peripheral opening 70 can be easily increased. In addition, by increasing the axial dimension L70 of the outer peripheral opening 70, the axial dimension L60 of the bolt arrangement space 60, which is necessary to avoid interference between the power transmission device 10 and the bolt 52 during bolt insertion work, can be further reduced. Consequently, the axial dimensions of the power transmission device 10 can be further miniaturized.

[0042] (Second Embodiment) Refer to Figures 5 and 6. The power transmission device 10 of this embodiment differs from the first embodiment in features related to the outer peripheral opening 70, which will be described below, and is otherwise similar.

[0043] In this embodiment, the outer peripheral opening 70 overlaps radially with the head 52b of the bolt 52 when the bolt 52 is fastened. To satisfy this condition, the outer peripheral opening 70 in this embodiment is provided in the second bolt hole 16c (reducer fixing part 16b) of the adapter 16. The axial dimension L70 of the outer peripheral opening 70 is longer than the axial dimension L52b of the head 52b of the bolt 52. Unlike the first embodiment, the outer peripheral opening 70 is sized to accommodate the head 52b of the bolt 52 when viewed from the axial direction X. In this embodiment, a seating surface 74 is provided at the bottom 70c of the outer peripheral opening 70 on which the head 52b of the bolt 52 sits.

[0044] In this way, when the bolt 52 is fastened, the outer peripheral opening 70 overlaps radially with the head 52b of the bolt 52. Therefore, the head 52b of the bolt 52 can be accommodated within the outer peripheral opening 70, making it easier to avoid interference between objects in the external space 72 and the head 52b of the bolt 52. Furthermore, unlike the case where the outer peripheral opening 70 is positioned to overlap radially with the shaft portion 52a of the bolt 52, a seating surface portion 74 can be provided at the bottom 70c of the outer peripheral opening 70 in an annular manner. This allows the seating surface area for receiving the head 52b of the bolt 52 to be wider by the seating surface portion 74 compared to the case where the outer peripheral opening 70 is provided on the seating surface portion 74.

[0045] In addition, the power transmission device 10 of this embodiment includes the components described in (A), (B), and (C) above, and can obtain the effects corresponding to those descriptions.

[0046] (Third Embodiment) Refer to Figures 7 to 9. The power transmission device 10 of this embodiment differs from the first embodiment in features related to the outer peripheral opening 70, which will be described below, and is similar in other respects.

[0047] The outer peripheral opening 70 of this embodiment is provided on the motor fixing portion 16a of the adapter 16. The outer peripheral opening 70 of this embodiment is provided on the motor side with respect to the bolt arrangement space 60, and its second opening edge 70b opens to the motor-side outer surface portion 62A. The outer peripheral opening 70 of this embodiment is sized to accommodate the head 52b of the bolt 52 when viewed from the axial direction X. The axial dimension L70 of the outer peripheral opening 70 is longer than the axial dimension L52b of the head 52b of the bolt 52. The outer surface portion 62B of the adapter 16 opposite to the motor is provided with a seating surface portion 74 that is continuous in an annular shape and where the head 52b of the bolt 52 sits.

[0048] The power transmission device 10 of this embodiment also includes the components described in (A), (B), and (C) above, and can obtain the effects corresponding to those descriptions.

[0049] (Fourth Embodiment) Refer to Figure 10. The power transmission device 10 of this embodiment differs from the first embodiment in the reduction gear fixing portion 16b of the adapter 16 and the features related to the outer peripheral opening 70, which will be described below, but is similar in other respects.

[0050] The reducer fixing portion 16b of the adapter 16 in this embodiment is fixed to the motor-side carrier 26B of the reducer 12. The reducer fixing portion 16b is fixed to the motor-side carrier 26B by overlapping it with the motor-side carrier 26B in the axial direction X and fastening it with bolts B3. The bolts B3 are inserted into the first adapter member 48 and the second adapter member 50 from the motor side. The adapter 16 is not positioned to overlap with the bolts 52 in the axial direction, nor to overlap with the motor-side carrier 26B in the radial direction. Furthermore, the adapter 16 is not positioned to overlap with the radially outer side of the reducer casing 24 in the radial direction. As a result, compared to the case where the adapter 16 is positioned to overlap with the motor-side carrier 26B in the radial direction, there is room to bring the motor-side outer surface portion 62A, which forms the bolt arrangement space 60, closer to the non-motor-side outer surface portion 62B. Therefore, the axial dimensions of the power transmission device 10 can be further miniaturized.

[0051] In this embodiment, the reducer 12 is provided with an outer peripheral opening 70 instead of the adapter 16. The outer peripheral opening 70 opens outward from a position that overlaps with the first bolt hole 46 in the axial direction X, as described above. The outer peripheral opening 70 of the reducer 12 is provided with a first opening edge 70a that opens to the outer peripheral surface of the reducer 12 (here, the reducer casing 24). The outer peripheral opening 70 of the reducer 12 is provided by cutting out a part of the reducer 12 so as to be recessed from the outer peripheral surface of the reducer 12. The outer peripheral opening 70 of the reducer 12 is provided at the first bolt hole 46. The outer peripheral opening 70 of this embodiment also overlaps radially with a part of the shaft portion 52a of the bolt 52, as in the first embodiment. In providing an outer peripheral opening 70 that overlaps radially with a part of the shaft portion 52a of the bolt 52, the outer peripheral opening 70 may be provided at either the first bolt hole 46 of the reducer 12 or the second bolt hole 16c of the adapter 16.

[0052] Even when the reduction gear 12 is equipped with an outer peripheral opening 70, the bolt 52 can be moved through the outer peripheral opening 70 to a position P1 (not shown) just before insertion by inserting the bolt 52 into the outer peripheral opening 70 from the first opening edge 70a. In this case as well, similar to (A) described above, it is possible to move the bolt 52 to the position P1 just before insertion while avoiding interference with the power transmission device 10 during the bolt insertion work by moving the bolt 52 through a new movement path that passes through both the outer peripheral opening 70 and the external space 72.

[0053] In this embodiment, the bolt dimension L52 of the bolt 52 is also larger than the axial dimension L60 of the bolt arrangement space 60, similar to the first embodiment. Furthermore, the bolt dimension L52 is smaller than the sum of the axial dimension L70 of the outer peripheral opening 70 and the axial dimension L60 of the bolt arrangement space 60. In this embodiment, the anti-motor side outer surface portion 62B that forms the bolt arrangement space 60 is provided on the external member mounting portion 24a of the reduction gear casing 24, instead of the reduction gear fixing portion 16b of the adapter 16 described above.

[0054] Next, we will explain the transformation forms of each component described so far.

[0055] The power transmission device 10 does not necessarily have to include an adapter 16. In this case, the reduction gear 12 may be connected to the motor 14 without an adapter 16. In this case, the motor 14 may be positioned so as to overlap with the bolt 52 in the axial direction. In this case, a bolt arrangement space 60 is provided between the reduction gear 12 and the motor 14. Furthermore, the power transmission device 10 may be implemented in a configuration in which the motor 14 is omitted, assuming that the reduction gear 12 is connected to the motor 14 regardless of the presence or absence of the adapter 16.

[0056] The type of gearbox 12 is not particularly limited. For example, in addition to an eccentric oscillating gearbox, the gearbox 12 may be a flexible meshing gearbox, a simple planetary gearbox, a right-angle shaft gearbox, a parallel shaft gearbox, etc. Furthermore, the type of eccentric oscillating gearbox is not particularly limited. In the embodiment, a center crank type in which the crankshaft 34 is positioned on the axis of the internal gear 30 was described as an example, but other types may also be used, for example, a distribution type in which multiple crankshafts 34 are positioned at offset positions from the axis of the internal gear 30. Furthermore, the type of flexible meshing gearbox is not particularly limited, and may be a cup type, a top hat type, a cylindrical type, etc.

[0057] Up to this point, we have described examples in which the outer peripheral opening 70 is provided on either the reduction gear 12 or the adapter 16, but the outer peripheral opening 70 may also be provided on the motor 14. This assumes, for example, that the outer diameter of the adapter 16 is smaller than the outer diameter of the reduction gear 12, and the outer diameter of the motor 14 is larger than the outer diameter of the adapter 16. This can also be described as the case in which the adapter 16 does not overlap with the bolt 52 in the axial direction, and only the motor 14 overlaps with the bolt 52 in the axial direction.

[0058] Up to this point, we have described an example in which the bolt arrangement space 60 is provided between the reduction gear 12 and the adapter 16, but it may also be provided between the reduction gear 12 and the motor 14. This assumes a case where a part of the adapter 16 is not provided in a position that overlaps with the bolt 52 in the axial direction X on the motor side of the bolt 52, and only the motor 14 is provided. In this case, the bolt arrangement space 60 will be provided when the motor 14 is fixed to the adapter 16. In this case, the motor-side outer surface portion 62A that forms the bolt arrangement space 60 will be provided on the motor 14. In this case as well, the motor-side outer surface portion 62A that forms the bolt arrangement space 60 may be removed when the first adapter member 48 is removed from the second adapter member 50.

[0059] In this example, the adapter 16 comprises a first adapter member 48 having a motor fixing portion 16a fixed to the motor 14 and a second adapter member 50 having a reduction gear fixing portion 16b fixed to the reduction gear 12. In addition, the motor fixing portion 16a and the reduction gear fixing portion 16b may be integrally constructed from the same member.

[0060] The outer peripheral opening 70 may be provided in the first bolt hole 46 (external member mounting portion 24a) of the reduction gear 12, in order to overlap radially with the head 52b of the bolt 52, as in the second embodiment. Alternatively, the outer peripheral opening 70 may be provided in a position that overlaps radially with both the head 52b and the shaft portion 52a of the bolt 52.

[0061] The outer peripheral opening 70 may be provided at two or more locations among the first bolt hole 46, the second bolt hole 16c, and the motor fixing portion 16a. For example, the outer peripheral opening 70 may be provided at the first bolt hole 46 of the reduction gear 12 and the second bolt hole 16c of the adapter 16, or at the second bolt hole 16c of the adapter 16 and the motor fixing portion 16a.

[0062] The external member 44 may be positioned on the motor side relative to the external member mounting portion 24a of the reduction gear 12. Either the first bolt hole 46 of the reduction gear 12 or the third bolt hole 44a of the external member 44 may be a closed hole that does not penetrate axially.

[0063] On the motor side of the bolt 52, it is not necessary for either a part of the adapter 16 or the motor 14 to be positioned in a location that overlaps with the bolt 52 in the axial direction.

[0064] The bolt dimension L52 of bolt 52 may be smaller than the axial dimension L60 of the bolt arrangement space 60.

[0065] The embodiments and variations described above are illustrative. The abstract technical ideas derived from them should not be interpreted restrictively to the content of the embodiments and variations. Many design changes, such as changes, additions, and deletions of components, are possible in the embodiments and variations. In the embodiments described above, the content that allows for such design changes is emphasized with the notation "embodiment." However, design changes are also permitted in content without such notation. The hatching applied to the cross-sections in the drawings does not limit the material to which the hatching is applied. The structures / numerical values ​​mentioned in the embodiments and variations naturally include those that can be considered identical when considering manufacturing tolerances, etc.

[0066] Any combination of the above components is also valid. For example, one may combine any description of another embodiment with an embodiment, or one may combine any description of both an embodiment and another embodiment with a modified form.

[0067] In an embodiment, a component composed of a single member may be composed of multiple members. Similarly, in an embodiment, a component composed of multiple members may be composed of a single member. [Explanation of symbols]

[0068] 10...Power transmission device, 12...Gear reducer, 14...Motor, 16...Adapter, 16a...Motor fixing part, 16c...Second bolt hole, 26A...Carrier, 28...External gear, 44...External member, 44a...Third bolt hole, 46...First bolt hole, 48...First adapter member, 50...Second adapter member, 52...Bolt, 52a...Shaft part, 52b...Head, 60...Bolt arrangement space, 70...Outer circumference opening.

Claims

1. A power transmission device equipped with a reduction gear, The reduction gear is provided with a first bolt hole in an external member for inserting bolts to fasten the reduction gear, The reduction gear is provided with an outer peripheral opening that opens outward from a position that overlaps the first bolt hole in the axial direction, The outer peripheral opening is a power transmission device provided in the first bolt hole.

2. The power transmission device is provided with a bolt arrangement space for arranging the bolts that are to be inserted into the first bolt holes. The power transmission device according to claim 1, wherein the axial dimension of the bolt is greater than the axial dimension of the bolt arrangement space and smaller than the sum of the axial dimensions of the bolt arrangement space and the outer peripheral opening.

3. The power transmission device according to claim 1 or 2, wherein the motor is positioned on the motor side of the bolt and overlaps with the bolt in the axial direction.

4. The external member is provided with a third bolt hole through which the bolt is inserted. The power transmission device according to any one of claims 1 to 3, wherein the first bolt hole is a through hole without internal threads on its inner surface, and the third bolt hole has internal threads on its inner surface.

5. The power transmission device according to any one of claims 1 to 4, wherein, when the bolt is fastened, the outer peripheral opening overlaps radially with a part of the shaft portion of the bolt.

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