Strain wave gearing

Abstract

To provide a wave gear device which includes a small-sized compact mechanism capable of retaining an assembly state of components, and is reduced in an installation space.SOLUTION: A wave gear device 1 includes three components of an internal gear 2, a cup-shaped external gear 3, and a wave generator 4, and a temporary fixing jig 9. The temporary fixing jig 9 is fastened and fixed by a temporary fixing bolt 10 to an output shaft 6 fixed to the external gear 3, and is fastened and fixed by a temporary fixing center bolt 11 to an input shaft 5 fixed to a cam plate 41 of the wave generator 4. The temporary fixing jig 9 is engaged with the output shaft 6 and the input shaft 5 to hold an assembly state of the three components 2, 3, 4. The wave gear device 1 does not require positioning work of the three components in mounting work on a motor. Since the temporary fixing jig 9 is removed from the wave gear device 1 after the wave gear device 1 is mounted on the motor, an installation space of the wave gear device 1 can be saved.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a strain wave gear device that is provided to the user as a unit in which three components, an internal gear, an external gear, and a strain wave generator, are assembled. [Background technology]

[0002] A wave gearing device is basically composed of three parts: a rigid internal gear, a flexible external gear, and a wave generator. The assembly work of a wave gearing device includes the work of attaching the wave generator to the motor shaft and the work of installing the wave generator attached to the motor shaft inside the external gear that is attached to the internal gear. In addition, positioning adjustment work such as centering the installed wave generator and positioning it in the axial direction is required. In order to make it easy for users to assemble the wave gearing device on their side, the wave gearing device is sometimes provided to users as a unit in which the three parts are pre-assembled and their positions are adjusted.

[0003] Such unit products are proposed, for example, in Patent Documents 1 and 2. The strain wave gear unit described in Patent Document 1 has a sealed structure with an input shaft supported by a bearing mechanism so that it can be easily assembled to a motor or the like. The bearing mechanism maintains the assembled state of the three parts and prevents problems such as misalignment of the wave generator during transport of the product and resulting damage to other parts such as the oil seal. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-74450 A [Patent Document 2] Utility Model Registration No. 3187367 Summary of the Invention [Problem to be solved by the invention]

[0005] A wave gear device that is a unit in which three parts are pre-assembled incorporates a support mechanism such as a bearing mechanism to maintain the assembled state of the three parts, particularly the assembled state of the wave generator relative to the external gear. A coupling mechanism and the like are also incorporated to facilitate attachment to the motor shaft, etc. However, because a support mechanism, coupling mechanism, etc. are incorporated, the dimensions and weight of the unitized wave gear device increase, requiring more installation space, increasing rotation loss, and raising other issues that must be resolved.

[0006] In view of the above, the main object of the present invention is to provide a strain wave gear device that has a small, compact mechanism that can maintain the assembled state of the parts and is configured to require a small installation space. [Means for solving the problem]

[0007] In order to solve the above problems, the wave gear device of the present invention is configured so that the assembled state of the components is maintained using a temporary fixing jig until it is attached to the device to which it is to be attached, such as a motor, and so that the temporary fixing jig can be removed after it is attached to the device to which it is to be attached.

[0008] Furthermore, in the wave gear device of the present invention, when the side of the axial direction of the wave gear device that is attached to the motor to which the wave gear device is to be attached is designated as the input side and the other side is designated as the output side, the work of attaching and removing the temporary fixing jig, and the work of attaching the input shaft to the motor shaft can all be performed from the output side.

[0009] Furthermore, the wave gear device of the present invention is configured so that the mounting portion of the temporary fixing bolt that fastens the temporary fixing jig to the input shaft of the wave gear device can be used to mount a shaft fastening bolt instead of the temporary fixing bolt, thereby fastening the input shaft of the wave gear device to the rotating shaft (motor shaft) of the device to which it is to be attached.

[0010] In the wave gearing of the present invention, the assembled state of the components of the wave gearing, particularly the three components of the internal gear, external gear, and wave generator, is maintained by the temporary fixing jig. There is no misalignment of the three components during transportation of the wave gearing, and adverse effects such as unnecessary loads being placed on other components such as oil seals due to misalignment are avoided.

[0011] Furthermore, when attaching the strain wave gear device to the device to which it is to be attached, there is basically no need to adjust the positions of the three components, simplifying the installation process. Once the strain wave gear device is attached to the device to which it is to be attached, the temporary fixing jig used to maintain the assembled state of the three components can be removed. This requires less installation space, which is advantageous for making the entire device smaller and more compact. Furthermore, it is convenient because the work of attaching the strain wave gear device and the work of removing the temporary fixing jig can be done from one direction.

[0012] Furthermore, instead of the temporary fixing bolts that fasten the temporary fixing jig to the input shaft of the strain wave gear device, shaft fastening bolts can be attached to fasten the input shaft to the motor shaft to which it is attached, allowing the coupling mechanism for attaching the input shaft to the motor shaft to be made small and compact. [Brief explanation of the drawings]

[0013] [Figure 1] 1A is a schematic vertical cross-sectional view showing a strain wave gear device to which the present invention is applied, and FIG. 1B is an explanatory diagram showing the meshing state of an internal gear and an external gear. [Figure 2] 1A is a schematic vertical cross-sectional view showing the strain wave gear device with the temporary fixing jig removed, and FIG. 1B is a perspective view showing the input shaft. [Figure 3] 10(A) to 10(D) are explanatory views showing a procedure for removing the temporary fixing jig. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1 and 2, an embodiment of a wave gearing device to which the present invention is applied will be described. The wave gearing device 1 includes a rigid internal gear 2, a cup-shaped flexible external gear 3 coaxially arranged inside the internal gear 2, a wave generator 4 coaxially arranged inside the external gear 3, an input shaft 5 coaxially fixed to the wave generator 4, an output shaft 6 coaxially fixed to the external gear 3, a main bearing 7 that supports the output shaft 6 (external gear 3) in a state where it can rotate relatively to the internal gear 2, and an end plate 8. The wave gearing device 1 also includes a temporary fixing jig 9 for holding the internal gear 2, external gear 3, and wave generator 4 in a positioned state after they are assembled and positioned relative to each other. The temporary fixing jig 9 is fastened and fixed to the output shaft 6 with multiple temporary fixing bolts 10, and is fastened and fixed to the input shaft 5 with one temporary fixing center bolt 11. In the following description, in the axial direction, which is the direction along the central axis 1a of the wave gear device 1, the side on which the end plate 8 is located is referred to as the axial input side, and the side on which the temporary fixing jig 9 is located is referred to as the axial output side.

[0015] The internal gear 2 is an annular member with a rectangular cross section, and internal teeth 21 are formed on its circular inner peripheral surface. The external gear 3 includes a radially flexible cylindrical body 32 on which external teeth 31 that can mesh with the internal teeth 21 of the internal gear 2 are formed, a diaphragm 33 that extends radially inward from the rear end of the cylindrical body 32, and a rigid annular boss 34 formed on the inner peripheral edge of the diaphragm 33. The wave generator 4 includes a rigid annular cam plate 41 and a wave generator bearing 43 attached to the elliptical outer peripheral surface (non-circular outer peripheral surface) of the cam plate 41. The wave generator 4 is fitted inside the cylindrical body 32 of the external gear 3, and bends the cylindrical body 32 into an elliptical shape, causing the external teeth 31 to partially mesh with the internal teeth 21.

[0016] The input shaft 5 extends through the central hole of the cam plate 41 of the wave generator 4. The input shaft 5 is a hollow shaft, and a disk-shaped flange 51 is integrally formed on its outer circumferential surface. The cam plate 41 of the wave generator 4 is coaxially fastened and fixed to the outer periphery of the disk-shaped flange 51. In this example, the input shaft 5 is a separate member from the cam plate 41, but it is also possible to use a single part in which the cam plate 41 and the input shaft 5 are integrated.

[0017] The output shaft 6 is coaxially fastened to the annular boss 34 of the external gear 3 from the output side. The output shaft 6 is a disk-shaped member with a center hole 61 having the same diameter as the center hole 35 of the boss 34. The main bearing 7 is disposed on the outer periphery of the output shaft 6. The main bearing 7 is a cross roller bearing, and its inner ring 71 is integrally formed with the output shaft 6. The inner ring 71 can also be manufactured as a separate component from the output shaft 6 and fastened coaxially to the outer periphery of the output shaft 6. The outer ring 72 of the main bearing 7 is located on the output side of the internal gear 2 and fastened coaxially to the internal gear 2. A roller is inserted in a raceway groove formed between the inner ring 71 (output shaft 6) and the outer ring 72 in a rollable state. The gap between the inner ring 71 (output shaft 6) and the outer ring 72, which is open to the output side, is sealed by an output-side oil seal 12. The end plate 8 is located on the input side of the internal gear 2 and fastened to the internal gear 2. An input-side shaft end portion 52 of the input shaft 5 protrudes toward the input side through a central hole 81 of the end plate 8. The gap between the outer peripheral surface of the input shaft 5 and the inner peripheral surface of the central hole of the end plate 8 is sealed by an input-side oil seal 13.

[0018] The temporary fixing jig 9 is disposed on the output side of the output shaft 6. The temporary fixing jig 9 has a cylindrical portion 91 sized to be inserted into the central hole 61 of the output shaft 6, and a disk-shaped flange 92 that extends radially outward from the output side end of the cylindrical portion 91. The outer diameter of the flange 92 is approximately the same as the outer diameter of the output shaft 6. The end face of the flange 92 facing the output shaft 6 has an inner peripheral portion that forms a stepped end face 93 that protrudes toward the output shaft 6. This stepped end face 93 has a shape complementary to the stepped end face 62 on the output side of the output shaft 6.

[0019] Bolt holes 94 for attaching temporary fixing bolts 10 are formed in the outer peripheral edge portion of the flange of the temporary fixing jig 9. The bolt holes 94 are arranged at regular angular intervals in the circumferential direction and penetrate the outer peripheral edge portion of the flange in the axial direction. In this example, bolt holes 94 are formed in two locations. Axial-extending bolt screw holes 63 open in the outer peripheral edge portion of the stepped end face 62 of the output shaft 6 at positions corresponding to the bolt holes 94. The temporary fixing jig 9 is coaxially fastened to the output shaft 6 by temporary fixing bolts 10 that are screwed into the bolt screw holes 63 from the output side via the bolt holes 94.

[0020] The circular center hole 95 of the cylindrical portion 91 of the temporary fixing jig 9 is a bolt hole into which the temporary fixing center bolt 11 can be inserted from the output side. This circular center hole 95 has a small-diameter circular inner circumferential surface portion midway in the axial direction, and is formed with an annular stepped surface 96 facing the output side and an annular stepped surface 97 facing the input side. The head of the temporary fixing center bolt 11 can engage with the annular stepped surface 96. The output-side shaft end 53 of the input shaft 5 is coaxially inserted into the circular center hole 95 from the input side. The center hole portion of this output-side shaft end 53 forms a bolt threaded hole 55 into which the temporary fixing center bolt 11 can be threaded. The temporary fixing jig 9 is coaxially fastened to the input shaft 5 by the temporary fixing center bolt 11 threadedly fixed into the bolt threaded hole 55 via the circular center hole 95 from the output side.

[0021] Here, the axial position of the input shaft 5 is fixed by abutting the tip surface 54 of the output-side shaft end 53 of the input shaft 5 against an annular stepped surface 97 (axial positioning surface) of the circular center hole 95 of the temporary fixing jig 9. Furthermore, as shown in FIG. 2(B), the outer peripheral surface 56 of the output-side shaft end 53 of the input shaft 5 has a D-cut shape, with both diametrically opposed portions of the circular outer peripheral surface being flat. The input-side inner peripheral surface 98 (rotational positioning surface) of the circular center hole 95 of the temporary fixing jig 9 has a D-cut shape complementary to the outer peripheral surface 56 of the input shaft 5, with both diametrically opposed portions of the circular inner peripheral surface jutting inward to form flat surfaces. The rotation-direction position of the input shaft 5 is fixed by the anti-rotation mechanism formed by these components.

[0022] In this way, by fastening and fixing the temporary fixing jig 9 to the input shaft 5 and the output shaft 6, the assembled state of the wave generator 4 attached to the input shaft 5 relative to the external gear 3 attached to the output shaft 6 is maintained, and the meshing state of the external gear 3 and the internal gear 2 by the wave generator 4 is also maintained. Therefore, the assembled state of these three parts is maintained when transporting the strain wave gear device 1, and adverse effects such as excessive load being placed on parts such as the input side oil seal 13 due to axial positional deviation, misalignment, tilt, etc. can be avoided. Furthermore, because the assembled state is maintained, there is no need to adjust the position of the parts when installing them in the device to which they are to be installed, such as a motor, and this can be done easily.

[0023] (Jig removal procedure) 3(A) to 3(D) are explanatory diagrams showing the procedure for removing the temporary fixing jig 9 when attaching the strain wave gear device 1, which has been carried into the installation location with the temporary fixing jig 9 attached, to the device to be attached, for example, a motor.

[0024] First, as shown in FIG. 3(A), the strain wave gearing 1 with the temporary fixing jig 9 attached is attached to the motor housing 101 of the motor 100 to which it is to be attached. The end plate 8, which defines the input side end face of the strain wave gearing 1, is positioned on the motor housing 101 (motor-side mounting flange). The strain wave gearing 1 is attached to the motor housing 101 by passing fastening bolts (not shown) through bolt holes 15 that extend through the internal gear 2, the outer ring 72 of the main bearing 7, and the end plate 8, which constitute the device housing of the strain wave gearing 1. The tip of the motor shaft 102 is coaxially inserted into the center hole of the input side shaft end 52 of the input shaft 5 of the strain wave gearing 1. A bolt screw hole 105 is opened in the tip face of the tip of the motor shaft 102, into which a shaft fastening center bolt 104 can be screwed in to fasten the motor shaft 102 to the input shaft 5 of the strain wave gearing 1.

[0025] On the output side of the strain wave gear device 1, the head of the temporary fixing center bolt 11 is exposed on the output side within a circular center hole 95 of a temporary fixing jig 9 attached to the output side of the strain wave gear device 1. As shown in FIG. 3(B), the temporary fixing center bolt 11 is removed to release the fastening between the temporary fixing jig 9 and the input shaft 5.

[0026] Next, the input shaft 5 of the strain wave gear device 1 is fastened to the motor shaft 102 using a shaft fastening center bolt 104 instead of the temporary fixing center bolt 11. As shown in FIG. 3(C), on the output side of the strain wave gear device 1, the shaft fastening center bolt 104 is screwed from the output side of the strain wave gear device 1 through the circular center hole 95 of the temporary fixing jig 9 and into a bolt screw hole 105 formed at the tip of the motor shaft 102. The input shaft 5 of the strain wave gear device 1 is fastened and fixed coaxially to the motor shaft 102. As a result, the strain wave gear device 1 is attached to the motor 100 with the assembled state of the three parts maintained by the temporary fixing jig 9. There is no need to adjust the positions of the external gear 3 and the wave generator 4 during the attachment work.

[0027] 3(D), on the output side of the strain wave gearing 1, the temporary fixing bolts 10 that fasten the temporary fixing jig 9 to the output shaft 6 are loosened, and the temporary fixing jig 9 is removed from the output shaft 6 to the output side. An O-ring groove 66 is formed in the stepped end face 62 on the output side of the output shaft 6 of the strain wave gearing 1, and an O-ring 67 is fitted into this groove. A load-side member (not shown) is attached to the output-side end face 65 of the output shaft 6 with the O-ring 67 sandwiched between them.

[0028] As described above, in the strain wave gearing 1 of this example, the assembled state of the components including the three parts, the internal gear 2, the external gear 3, and the wave generator 4, is maintained by the temporary fixing jig 9 until it is attached to the motor 100. This eliminates the need to adjust the positions of the three parts when attaching the strain wave gearing 1 to the motor 100, simplifying the attachment work.

[0029] The strain wave gear device 1 does not require the incorporation of a bearing mechanism or the like for maintaining the assembled position of the wave generator 4 relative to the external gear 3, resulting in a unit structure that easily reduces the inertia of the input shaft 5. The temporary fixing jig 9 that maintains the assembled state is removed after the strain wave gear device 1 is attached to the motor 100. This means that the strain wave gear device 1 requires less installation space, which is advantageous for making the entire device to which the strain wave gear device 1 is attached smaller, more compact, and lighter.

[0030] For example, in the input shaft 5 to which the cam plate 41 (wave plug) of the wave generator 4 shown in FIG. 2(B) is attached, the output-side shaft end portion 53 protruding from the output side can be eliminated to make the input shaft 5 even flatter and lighter (lower inertia). In this case, a recess with a D-cut inner peripheral surface of a predetermined depth is formed on the output-side end face of the input shaft 5. The cylindrical portion 91 of the temporary fixing jig 9 may be made to have a D-cut outer peripheral surface that can be fitted into this recess.

[0031] Furthermore, in the strain wave gearing 1 of this example, the input shaft 5 and the motor shaft 102 are fastened and fixed by a shaft fastening center bolt 104 that is arranged in place of the temporary fixing center bolt 11. This is advantageous for making the strain wave gearing 1 smaller and more compact than when a shaft coupling, spline shaft, or other shaft coupling mechanism is incorporated.

[0032] Furthermore, the work of attaching the strain wave gear device 1 to the motor 100 and the work of removing the temporary fixing jig 9 can be performed from the same side (output side) of the strain wave gear device 1. This makes it easy to attach the strain wave gear device 1 to the motor 100, and also makes it easy for the user to automatically assemble the strain wave gear device 1.

[0033] In addition, the strain wave gearing 1 of this example is configured as a sealed unit equipped with an input side oil seal 13 and an output side oil seal 12. There is no need to arrange sealing components (oil seals, etc.) on the side of the motor 100 to which it is to be attached. Furthermore, the structure of the input shaft 5 side of the wave generator 4 of the strain wave gearing 1 can be set to match the shaft fastening structure on the motor shaft 102 side. [Explanation of symbols]

[0034] 1 Strain wave gearing 1a Center axis 2 Internal gear 3 External gear 4. Wave Generator 5 Input shaft 6 Output shaft 7 Main bearing 8 End Plate 9 Temporary fixing jig 10 Temporary fixing bolt 11 Temporary fixing center bolt 12 Output oil seal 13 Input oil seal 15 bolt holes 21 Inner teeth 31 Outer teeth 32 Cylindrical body 33 Diaphragm 34 Boss 35 center hole 41 Cam plate 43 Wave generator bearing 51 Disc-shaped flange 52 Input side shaft end 53 Output side shaft end 54 Tip surface 55 bolt threaded holes 56 Outer surface 61 Center hole 62 Step edge 63 Bolt screw holes 65 Output side end face 66 Ring groove 67 Ring 71 Inner circle 72 outer ring 81 Center hole 91 Cylindrical part 92 flange 93 Step edge 94 bolt holes 95 circular center hole 96 Annular step surface 97 Annular step surface 98 Inner surface 100 motor 101 Motor housing 102 Motor shaft 104 Shaft fastening center bolt 105 bolt screw hole

Claims

1. a rigid internal gear; a cup-shaped flexible external gear coaxially arranged inside the internal gear; a wave generator arranged coaxially inside the external gear; a main bearing that supports the external gear in a state that allows it to rotate relatively to the internal gear; Equipped with the external gear comprises a cylindrical body portion flexible in the radial direction and having external teeth that can mesh with internal teeth of the internal gear, a diaphragm extending radially inward from one end of the cylindrical body portion, and a rigid boss formed on the inner peripheral edge of the diaphragm; the wave generator comprises a rigid cam plate having an input shaft, and a wave generator bearing mounted on a non-circular outer peripheral surface of the cam plate; the wave generator is fitted inside the cylindrical body portion of the external gear and bends the cylindrical body portion in a radial direction to partially engage the external teeth with the internal teeth, the main bearing includes an outer ring coaxially fixed to the internal gear and an inner ring having an output shaft coaxially fixed to the boss of the external gear, In a wave gear device in which the wave generator is disposed on one axial side, i.e., an input side, and the output shaft is disposed on the other axial side, i.e., an output side, with the boss of the external gear sandwiched therebetween, a temporary fixing jig that holds the three members of the internal gear, the external gear, and the wave generator in a predetermined assembled state; a first temporary fixing bolt and a second temporary fixing bolt; It is equipped with The input shaft an input side shaft end portion fastened and fixed to a motor shaft to be attached; an output side shaft end portion fastened and fixed to the temporary fixing jig; It is equipped with The temporary fixing jig is a disk-shaped flange located on the output side of the output shaft; a cylindrical portion protruding from the disk-shaped flange to the input side through a center hole of the output shaft and a center hole of the boss; a hollow portion extending through the disk-shaped flange and the cylindrical portion; Equipped with the cylindrical portion engages with the output-side shaft end portion of the input shaft and includes an axial positioning surface that defines an axial position of the wave generator relative to the external gear and a rotational positioning surface that defines a rotational position of the wave generator relative to the external gear, The temporary fixing jig is the first temporary fixing bolt is attached to the disk-shaped flange from the output side, and the first temporary fixing bolt is fastened and fixed coaxially to the output shaft; a wave gear device characterized in that the input shaft is coaxially fastened to the output-side shaft end portion of the input shaft by the second temporary fixing bolt attached to the hollow portion from the output side.

2. In claim 1, the axial positioning surface is an annular stepped surface formed on an inner circumferential surface of the hollow portion of the temporary fixing jig and facing the input side, a tip end surface of the input-side shaft end portion of the input shaft inserted into the hollow portion abuts against the annular step surface from the input side, the rotational direction positioning surface is formed on an inner circumferential surface on the input side of the hollow portion of the temporary fixing jig, and a part of the circular inner circumferential surface protrudes radially inward, A wave gear device in which the outer peripheral surface of the input side shaft end of the input shaft inserted into the hollow portion has a shape complementary to the rotational direction positioning surface.

3. In claim 1, further comprising: a shaft fastening bolt that is attached to the hollow portion after the second temporary fixing bolt is removed and fastens the input side shaft end of the input shaft to the motor shaft to be attached.

4. In claim 1, further comprising: an end plate fixed to the internal gear from the input side; An input side oil seal, Output oil seal and It is equipped with the input-side shaft end of the input shaft protrudes toward the input side through a center hole of the end plate, and a gap between an inner peripheral surface of the center hole of the end plate and an outer peripheral surface of the input-side shaft end is sealed by the input-side oil seal, a gap formed between the outer ring and the inner ring of the main bearing and opening to the output side is sealed by an output side oil seal.

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