Harsh drive gear

Abstract

To provide a wave gear device that includes a rotation transmission member for transmitting rotation in a direction orthogonal to a rotation center line, can be configured to be compact, and can secure support strength of the rotation transmission member.SOLUTION: A wave gear device 1 includes: a pulley 2 and an output shaft 8 that transmit rotation in a direction orthogonal to a rotation center line 1a and are disposed on a first side 1A in an axial direction relative to a cup-shaped external tooth gear 4; and an input shaft 7 that transmits input rotation to a wave generator 5 from the pulley 2, functions as support shaft for both of the pulley 2 and the wave generator 5, and is supported by both first and second bearings 11, 12, thereby configuring a rotation transmission mechanism from the pulley 2 to the wave generator 5 and the support mechanism thereof to be compact and securing support strength. A second side 1B of the wave gear device 1 in the axial direction is covered by a cover plate 9, thereby omitting a seal structure.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a harmonic gear device provided with a rotation transmission member such as a pulley or spur gear to which rotation is transmitted from a direction orthogonal to the rotation center line.

Background Art

[0002] In this type of harmonic gear device, the output rotation of motors arranged in parallel is transmitted and decelerated via a pulley-belt type rotation transmission mechanism or a reduction gear train, and the decelerated rotation is transmitted to the load side. Alternatively, the decelerated rotation output from the harmonic gear device is transmitted to the load side via a pulley-belt type rotation transmission mechanism or a reduction gear train. For example, Patent Document 1 describes a flat type harmonic gear device in which a driven side pulley to which rotation is input is arranged at one end in the axial direction, and an output shaft for decelerated rotation is arranged at the other end. Patent Document 2 describes a cup type harmonic gear device in which an input shaft projects from one side in the axial direction, and a pulley attached to an output shaft for decelerated rotation is arranged on the other side.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a harmonic gear device to which a rotation transmission member such as a pulley or spur gear is attached, the device dimensions, particularly the dimensions in the axial direction, increase in order to attach the rotation transmission member and its support mechanism. When attempting to arrange the support mechanism for a pulley or the like inside the harmonic gear device for the purpose of avoiding an increase in dimensions and achieving compactness, sufficient support strength may not be obtained due to restrictions on the size and arrangement of the bearings.

[0005] The object of the present invention is to provide a harmonic drive gear device equipped with a rotation transmission member that transmits rotation in a direction perpendicular to the rotation centerline, and having a structure advantageous for flattening and compacting. Furthermore, the object is to provide a harmonic drive gear device that is advantageous for flattening and compacting, while also having a structure that can ensure the support strength of the rotation transmission member. [Means for solving the problem]

[0006] The present invention relates to a wave gear device equipped with a rotation transmission member that transmits rotation in a direction perpendicular to the rotation centerline, A rigid internal gear, A cup-shaped, radially flexible external gear is coaxially positioned inside the internal gear, A wave generator fitted inside the external gear, which bends the external gear into a non-circular shape and partially engages with the internal gear, An input shaft extending coaxially from the wave generator to a first side which is one side in the axial direction along the rotation centerline, With respect to the boss defining the center of the bottom of the cup shape of the external gear, an output shaft is coaxially attached from the first side in the axial direction, A cover plate is attached to the internal gear from a second side opposite to the first side in the axial direction, and covers the internal gear, the external gear, and the wave generator from the second side. It is equipped with, The tip of the input shaft protrudes to the first side through the central hole that penetrates the boss and the output shaft. The rotational transmission member is characterized by being coaxially attached to the tip of the input shaft.

[0007] Also, wave drive gears, The shaft end on the side of the wave generator in the input shaft is rotatably supported by the boss of the external gear or the cover plate via the first bearing. The tip of the input shaft is rotatably supported by the output shaft via a second bearing.

[0008] In the harmonic drive gear of the present invention, the rotational transmission member and the output shaft are arranged on one side in the axial direction, which is the tip of the input shaft, relative to the cup-shaped external gear. The other side in the axial direction is covered by a cover plate, eliminating the need for sealing structures such as oil seals to prevent oil leakage from the inside to the outside of the harmonic drive gear. Therefore, it is advantageous for miniaturizing and flattening the harmonic drive gear.

[0009] The input shaft that transmits input rotation from the rotation transmission member to the wave generator also functions as a support shaft for both the rotation transmission member and the wave generator, and is supported in a double-supported manner by first and second bearings. Therefore, the rotation transmission mechanism from the rotation transmission member to the wave generator and their support mechanisms can be constructed compactly, and the support strength of the rotation transmission member and the wave generator can be ensured. [Brief explanation of the drawing]

[0010] [Figure 1] (A) is a schematic longitudinal cross-sectional view showing a harmonic drive gear according to Embodiment 1, and (B) is an explanatory diagram showing the internal structure of the harmonic drive gear. [Figure 2] This is a schematic longitudinal cross-sectional view showing a harmonic drive gear according to Embodiment 2. [Figure 3] This is a schematic longitudinal cross-sectional view showing a harmonic drive gear according to Embodiment 3. [Figure 4] This is a schematic longitudinal cross-sectional view showing a harmonic drive gear according to Embodiment 4. [Figure 5] (A) and (B) are explanatory diagrams showing example configurations of actuators equipped with a harmonic drive gear and a motor. [Modes for carrying out the invention]

[0011] A harmonic drive gear according to an embodiment of the present invention will be described below with reference to the drawings. Each embodiment is an example of the present invention and is not intended to limit the present invention to the structure of the embodiment.

[0012] (Embodiment 1) An embodiment of the harmonic drive gear according to the present invention will be described with reference to Figures 1 and 5. The harmonic drive gear 1 is equipped with a pulley 2, which is a rotation transmission member that transmits rotation in a direction perpendicular to the rotation centerline 1a. As shown in Figure 5(A), rotation is transmitted to the pulley 2 from a motor M arranged in parallel at an adjacent position to the harmonic drive gear 1 via a pulley-belt type rotation transmission mechanism 100. As shown in Figure 5(B), a gear train 100A can also be used as the rotation transmission mechanism. In this case, a driven gear 2A is attached to the harmonic drive gear 1 instead of the pulley 2.

[0013] As shown in Figures 1(A) and (B), the wave drive gear 1 comprises a rigid internal gear 3, a cup-shaped radially flexible external gear 4 coaxially positioned inside the internal gear 3, and a wave generator 5 fitted inside the external gear 4, which partially engages with the internal gear 3 by bending the external gear 4 into a non-circular shape. The internal gear 3 and external gear 4 are supported in a state of relative rotation by a main bearing 6 consisting of a cross roller bearing. An input shaft 7 is attached coaxially to the wave generator 5, and a pulley 2 is attached to the input shaft 7. The internal gear 3 is a stationary side member attached to a fixed side member (not shown), and the external gear 4 is a driven side member. An output shaft 8 is attached coaxially to the external gear 4. The output shaft 8 is integrally formed with the inner ring 61 of the main bearing 6, but these may be manufactured as separate members and fixed coaxially. A cover plate 9 is positioned at the end of the wave drive gear 1 opposite to the pulley 2.

[0014] The input rotation transmitted from the outside to the pulley 2 is transmitted to the wave generator 5 via the input shaft 7. When the wave generator 5 rotates, the meshing position of the external gear 4 with respect to the internal gear 3 moves in the circumferential direction, and a relative rotation corresponding to the difference in the number of teeth of both gears occurs between the two gears. The external gear 4 rotates at a rotational speed that is significantly reduced with respect to the input rotation. A load-side member 10 is connected to the output shaft 8 attached to the external gear 4 as shown by the imaginary line, and the decelerated rotation is output from the output shaft 8 to the load-side member 10. Drive control of the actuator including the motor M and the wave generator 5 is performed so that the load-side member 10 rotates within a finite angle range where it does not interfere with the members constituting the motor, the pulley-belt type transmission mechanism.

[0015] The internal gear 3 of the harmonic gear device 1 has an annular shape, and internal teeth 31 are formed on its inner peripheral surface. The external gear 4 includes a cylindrical body portion 41 that can be deflected in the radial direction, a diaphragm 42 that extends radially inward from one end of the cylindrical body portion 41, and a rigid boss 43 having an annular shape integrally formed on the inner peripheral edge of the diaphragm 42. External teeth 44 that can mesh with the internal teeth 31 of the internal gear 3 are formed on the outer peripheral surface portion of the open end, which is the other end of the cylindrical body portion 41. The wave generator 5 includes a rigid cam plate 51 and a wave generator bearing 52 mounted on the non-circular outer peripheral surface of the cam plate 51. The non-circular outer peripheral surface is, for example, an elliptical outer peripheral surface, and the outer peripheral surface of the wave generator bearing 52 is in a deflected elliptical state and is fitted to the side of the open end of the cylindrical body portion 41 of the external gear 4. As a result, the portion of the external gear 4 where the external teeth 44 are formed is deflected into an elliptical shape, and a state is formed in which the portions of the external teeth 44 located at both ends of the long axis of the elliptical shape are meshed with the internal teeth 31. When the wave generator 5 rotates, the meshing position of the two gears 3 and 4 moves in the circumferential direction.

[0016] The input shaft 7 is integrally formed with the cam plate 51 of the vibration generator 5. The input shaft 7 extends coaxially from the cam plate 51 toward the boss 43 that defines the central portion of the cup-shaped bottom of the external gear 4. In other words, the input shaft 7 extends from the cam plate 51 toward the first side 1A, which is one side in the axial direction along the rotation center line 1a. The input shaft 7 can also be manufactured as a separate member and fastened and fixed to the cam plate 51. The input shaft 7 extends through the central hole 45 of the annular boss 43 that defines the central portion of the cup-shaped bottom of the external gear 4 and extends to the first side 1A. A pulley 2, which is a rotation transmission member, is coaxially fastened and fixed to the axial tip end portion 71 of the input shaft 7 that protrudes from the central hole 45 of the boss 43 of the external gear 4 by a fastening bolt 15.

[0017] The main bearing 6 that supports the internal gear 3 and the external gear 4 in a relatively rotatable state is disposed on the first side 1A in the axial direction with respect to the internal gear 3. The outer ring 62 of the main bearing 6 is coaxially fastened and fixed to the internal gear 3. As described above, the output shaft 8 is integrally formed with the inner ring 61 of the main bearing 6. The output shaft 8 is coaxially fixed to the boss 43 of the external gear 4 from the first side 1A. In this example, the inner peripheral edge portion of the central hole 81 of the output shaft 8 is joined to the outer peripheral edge portion of the boss 43 of the external gear 4 by full circumference welding. It can also be joined using a fastening bolt or the like.

[0018] The cover plate 9 is fastened and fixed to the end face of the internal gear 3 from the second side 1B, which is opposite to the first side 1A in the axial direction. The cover plate 9 covers the internal gear 3, the external gear 4, and the vibration generator 5 from the second side 1B.

[0019] Here, the axial end portion 72 of the input shaft 7 on the side of the vibration generator 5 is rotatably supported by the boss 43 of the external gear 4 via a first bearing 11 composed of a ball bearing. In this example, a first bearing holder 13 is coaxially fixed to the boss 43 of the external gear 4 from the second side 1B. The first bearing 11 is mounted between the first bearing holder 13 and the outer peripheral surface of the axial end portion 72 of the input shaft 7.

[0020] Furthermore, the shaft tip portion 71 on the pulley 2 side of the input shaft 7 is rotatably supported by the output shaft 8 via a second bearing 12 made of ball bearings. The pulley 2 has a pulley shaft portion 22 that protrudes from its end face to the second side 1B, and the shaft tip portion 71 of the input shaft 7 is fitted coaxially into the central hole 23 of this pulley shaft portion 22. In this state, the pulley 2 is coaxially fastened and fixed to the input shaft 7 by fastening bolts 15. A bearing mounting surface 24 is formed on the circular outer surface of the pulley shaft portion 22. A second bearing holder 14 is fastened and fixed coaxially to the end face of the first side 1A of the output shaft 8. The second bearing 12 is mounted between the bearing mounting surface 24 on the pulley 2 side and the second bearing holder 14 on the output shaft 8 side.

[0021] Furthermore, a wave washer 16 is sandwiched between the pulley 2 attached to the input shaft 7 and the output shaft 8 (boss 43 of the external gear 4) to apply axial preload. The preload eliminates axial play in the wave generator 5, which is supported by the first and second bearings 11 and 12, and the components are fixed in this state by adhesive or the like. This eliminates the need for axial position adjustment work of the wave generator 5.

[0022] In the harmonic drive gear 1 configured in this way, the pulley 2 and output shaft 8 are positioned on the side of the shaft tip 71 of the input shaft 7, which is one side in the axial direction relative to the cup-shaped external gear 4. The input shaft 7, which transmits input rotation from the pulley 2 to the wave generator 5, functions as a support shaft for both the pulley 2 and the wave generator 5, and is supported in a double-supported manner by the first and second bearings 11 and 12. Therefore, the rotation transmission mechanism from the pulley 2 to the wave generator 5 and their support mechanisms can be made compact, and the support strength of the pulley 2 and the wave generator 5 can be ensured. In addition, the axial second side 1B of the harmonic drive gear 1 is covered by a cover plate 9, and a sealing structure such as an oil seal to prevent oil leakage from the inside of the harmonic drive gear 1 to the second side 1B can be omitted. Therefore, it is advantageous for miniaturization and flattening of the harmonic drive gear 1.

[0023] (Embodiment 2) Figure 2 is a schematic longitudinal cross-sectional view showing a harmonic drive gear 200 according to Embodiment 2. Since the basic configuration of the harmonic drive gear 200 is the same as that of the harmonic drive gear 1, the same reference numerals are used for corresponding parts, and descriptions of those parts are omitted.

[0024] In the wave drive gear unit 200, the first bearing 11 supporting the wave generator 5 is located on the second axial side 1B relative to the wave generator 5, and the first bearing 11 is mounted on the cover plate 9. The input shaft 7 has an axial projection 73 that coaxially protrudes from the cam plate 51 of the wave generator 5 to the second axial side 1B. The cover plate 9 has a bearing mounting portion 91 that opens to the first axial side 1A. The axial projection 73 of the input shaft 7 is supported by the first bearing 11 mounted on the bearing mounting portion 91.

[0025] Furthermore, in the wave drive gear unit 200, the output shaft 8, which is integrally formed with the inner ring 61 of the main bearing 6, is fastened and fixed to the boss 43 of the external gear 4 by fastening bolts 17, rather than by welding.

[0026] (Embodiment 3) Figure 3 is a schematic longitudinal cross-sectional view showing a harmonic drive gear 300 according to Embodiment 3. Since the basic configuration of the harmonic drive gear 300 is the same as that of the harmonic drive gear 1, the same reference numerals are used for corresponding parts, and their descriptions are omitted.

[0027] In the wave drive gear unit 300, the first bearing 11 supporting the wave generator 5 is located on the second axial side 1B relative to the wave generator 5, and the first bearing 11 is mounted on the cover plate 9. The input shaft 7 has an axial projection 73 that coaxially protrudes from the cam plate 51 of the wave generator 5 to the second axial side 1B. The cover plate 9 has a bearing mounting portion 91 that opens to the first axial side 1A. The axial projection 73 of the input shaft 7 is supported by the first bearing 11 mounted on the bearing mounting portion 91.

[0028] Furthermore, in the wave drive gear unit 300, the output shaft 8, which is integrally formed with the inner ring 61 of the main bearing 6, is fastened and fixed to the boss 43 of the external gear 4 by fastening bolts 17, rather than by welding.

[0029] Furthermore, in the wave drive gear unit 300, the second bearing 12 is mounted between the shaft tip 71 of the input shaft 7 and the second bearing holder 14. That is, the second bearing 12 is located on the second axial side 1B with respect to the pulley 2 and supports the shaft tip 71 of the input shaft 7.

[0030] (Embodiment 4) Figure 4 is a schematic longitudinal cross-sectional view showing a harmonic drive gear 400 according to Embodiment 4. Since the basic configuration of the harmonic drive gear 400 is the same as that of the harmonic drive gear 1, the same reference numerals are used for corresponding parts, and their descriptions are omitted.

[0031] In the wave drive gear unit 400, the first bearing 11 supporting the wave generator 5 is located on the second axial side 1B relative to the wave generator 5, and the first bearing 11 is mounted on the cover plate 9. The input shaft 7 has an axial projection 73 that coaxially protrudes from the cam plate 51 of the wave generator 5 to the second axial side 1B. The cover plate 9 has a bearing mounting portion 91 that opens to the first axial side 1A. The axial projection 73 of the input shaft 7 is supported by the first bearing 11 mounted on the bearing mounting portion 91.

[0032] Furthermore, in the wave drive gear unit 400, the output shaft 8, which is integrally formed with the inner ring 61 of the main bearing 6, is fastened and fixed to the boss 43 of the external gear 4 by fastening bolts 17, rather than by welding.

[0033] Furthermore, in the wave drive gear unit 400, a bearing mounting surface 82 is formed on the inner circumferential surface of the central hole of the output shaft 8, which is integrally formed with the inner ring 61. The second bearing 12 is mounted on the bearing mounting surface 82 of the output shaft 8 and supports the shaft tip portion 71 of the input shaft 7. [Explanation of Symbols]

[0034] 1. Harmonic drive gear 1a Rotation centerline 1A First side 1B Second side 2 Pulley 2A Gear 3 Internal gear 4 External gears 5 Wave Generator 6 Main bearings 7 Input axes 8 Output shafts 9 Cover plate 10 Load-side member 11. First bearing 12. Second bearing 13. First bearing holder 14. Second bearing holder 15 Fastening bolts 16 Wave Washer 17 Fastening bolts 22 Pulley shaft 23 Center hole 24 Bearing mounting surface 31 Inner teeth 41 Cylindrical body 42 diaphragm 43 Boss 44 External teeth 45 center hole 51 Cam plate 52 Wave Generator Bearing 61 Inner Ring 62 Outer ring 71 Shaft tip 72 Shaft end 73 Shaft protrusion 81 Center hole 82 Bearing mounting surface 91 Bearing mounting section 100 RPM transmission mechanism 100A Gear Train 200 Harsh drive gear 300 Harmonic drive gear 400 Harmonic drive gear M Motor

Claims

1. In a wave drive gear system equipped with a rotation transmission member that transmits rotation in a direction perpendicular to the rotation centerline, A rigid internal gear, A cup-shaped, radially flexible external gear is coaxially positioned inside the internal gear, A wave generator fitted inside the external gear, which bends the external gear into a non-circular shape and partially engages with the internal gear, An input shaft extending coaxially from the wave generator to the first side, which is one side in the axial direction along the rotation centerline, The output shaft is coaxially mounted from the first side in the axial direction to the boss that defines the center of the bottom of the cup shape of the external gear, A cover plate is attached to the internal gear from a second side opposite to the first side in the axial direction, and covers the internal gear, the external gear, and the wave generator from the second side. The input shaft is rotatably supported by a first bearing and a second bearing, It is equipped with, The input shaft comprises a shaft end extending from the wave generator and a shaft tip extending from this shaft end through a central through-hole formed in the boss to the first side. The rotational transmission member comprises a shaft portion protruding to the second side and a central hole formed in this shaft portion and opening to the second side. The tip of the input shaft is coaxially fitted into the central hole of the rotation transmission member. The shaft end of the input shaft is rotatably supported by the boss of the external gear via the first bearing. The tip of the input shaft is rotatably supported by the output shaft via the second bearing. The second bearing is mounted between the shaft portion of the rotation transmission member and the output shaft. A harmonic drive gear device characterized in that the output shaft, the second bearing, and the shaft portion of the rotation transmission member are arranged concentrically in the radial direction.

2. In claim 1, A bearing mounting surface formed on the circular outer surface of the shaft portion, A bearing holder is positioned radially inward of the output shaft and fixed coaxially to the output shaft, It is equipped with, The second bearing is mounted radially between the bearing mounting surface and the bearing holder in a harmonic drive gear.

3. In claim 1, The system includes a main bearing that supports the internal gear and the external gear in a state where they can rotate relative to each other. The main bearing is positioned on the first side with respect to the internal gear. The outer ring of the main bearing is mounted coaxially to the internal gear. A harmonic drive gear in which the output shaft is coaxially mounted to the inner ring of the main bearing, or the output shaft is integrally formed with the inner ring.

4. In claim 1, A wave drive gear device comprising a wave washer that applies axial preload between an input-side member to which the rotation transmission member is attached and an output-side member to which the output shaft is attached, thereby eliminating axial play in the wave generator.

5. In claim 1, The external gear is provided with a first bearing holder that is coaxially attached to the boss from the second side, The first bearing is a harmonic drive gear mounted between the first bearing holder and the shaft end of the input shaft.

6. In claim 1, A bearing mounting surface formed on the outer circumferential surface of the rotation transmission member, A second bearing holder is attached coaxially to the output shaft from the first side. It is equipped with, The second bearing is mounted between the bearing mounting surface and the second bearing holder in a harmonic drive gear.

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