Drive unit, robot, and method for assembling the drive unit

Abstract

The present invention provides a drive unit, a robot, and a method for assembling the drive unit, all of which facilitate grease filling. [Solution] The drive device 1 comprises a motor 14 having a rotating shaft 17 and a harmonic drive gear reducer 16 that reduces the rotation of the rotating shaft 17. The harmonic drive gear reducer 16 includes an internal gear 23, a flexible external gear 24 that partially meshes with the internal gear 23, and a wave generator 25 connected to the rotating shaft 17, in contact with the inner circumferential surface of the external gear 24, and bending the external gear 24 to move the meshing position between the internal gear 23 and the external gear 24 in the circumferential direction. The drive device 1 comprises a motor 14 having a rotating shaft 17 and a harmonic drive gear reducer 16 that reduces the rotation of the rotating shaft 17, and the harmonic drive gear reducer 16 includes an internal gear 23, a flexible external gear 24 that partially meshes with the internal gear 23, and a wave generator 25 that partially meshes with the external gear 24 and the wave generator 25 and is filled with grease, and a second region R2 formed by the wave generator 25 and the motor 14 and is filled with grease. The wave generator 25 is provided with a through hole 34 connecting the first region R1 and the second region R2.

Description

Technical Field

[0001] The present invention relates to a drive device, a robot, and a method for assembling a drive device.

Background Art

[0002] For example, in Patent Document 1, in a rotary table device in which a harmonic drive speed reducer is disposed inside a device case, lubricating oil is injected from an oil supply passage formed in the device case into an oil supply hole formed in a cup-shaped flexible external gear to smoothly lubricate an inner wave bearing and a bearing with the lubricating oil. A rotary table device is described.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the rotary table device described in Patent Document 1, although the supply of lubricating oil to the upper side of the wave generator is possible from the oil supply hole, the supply of lubricating oil to the lower side of the wave generator, that is, the flange side holding the harmonic drive speed reducer, must be performed before assembling the harmonic drive speed reducer to the flange. Therefore, the supply of lubricating oil around the wave generator has to be carried out in multiple steps, and there are restrictions on the assembly procedure.

Means for Solving the Problems

[0005] The drive device comprises a motor having a rotating shaft and a harmonic drive gear reducer for reducing the rotation of the rotating shaft, wherein the harmonic drive gear reducer includes an internal gear, a flexible external gear that partially meshes with the internal gear, and a wave generator connected to the rotating shaft, in contact with the inner circumferential surface of the external gear, and bending the external gear to move the meshing position between the internal gear and the external gear in the circumferential direction, and has a first region formed by the external gear and the wave generator and filled with grease, and a second region formed by the wave generator and the motor and filled with grease, and the wave generator is provided with a through hole connecting the first region and the second region.

[0006] The robot has the drive device described above.

[0007] The method for assembling a drive device comprises a motor having a rotating shaft and a harmonic drive gear reducer for reducing the rotation of the rotating shaft, wherein the harmonic drive gear reducer comprises an internal gear, a flexible external gear that partially meshes with the internal gear, and a wave generator connected to the rotating shaft, in contact with the inner circumferential surface of the external gear, and bending the external gear to move the meshing position between the internal gear and the external gear in the circumferential direction, and comprises a first region formed by the external gear and the wave generator and filled with grease, and a second region formed by the wave generator and the motor and filled with the grease, wherein the wave generator is provided with a through hole connecting the first region and the second region, and after assembling the motor and the harmonic drive gear reducer, the grease is injected into the first region to fill the first region and the second region with grease. [Brief explanation of the drawing]

[0008] [Figure 1] A perspective view showing the schematic structure of the drive device according to the first embodiment. [Figure 2] A cross-sectional view showing details of the drive device according to the first embodiment. [Figure 3]A cross-sectional view showing details of the gear section of a harmonic drive gear reducer according to the first embodiment. [Figure 4] A side view showing the structure of a harmonic drive gear reducer according to the first embodiment. [Figure 5] A perspective view showing the structure of a ring member in a harmonic drive gear reducer according to the first embodiment. [Figure 6] A schematic diagram of a robot equipped with a drive device according to the second embodiment. [Modes for carrying out the invention]

[0009] 1. First Embodiment The drive unit 1 according to this embodiment will be described with reference to Figures 1 to 5. Note that in Figure 3, for the sake of explanation, the ring member 35 is shown removed.

[0010] Furthermore, for the sake of clarity, the following perspective views, cross-sectional views, and side views illustrate the X, Y, and Z axes as three mutually orthogonal axes. Therefore, Figure 2 shows a cross-section parallel to the XZ plane, and Figure 3 shows a cross-section parallel to the XY plane.

[0011] Please note that, for the sake of clarity, the dimensions of each part in the diagrams have been exaggerated as needed, and the dimensional ratios between parts do not necessarily match the actual dimensional ratios.

[0012] As shown in Figure 1, the drive unit 1 comprises a motor 14 having a rotating shaft 17, a support member 15, and a harmonic drive gear reducer 16 that reduces the rotation of the rotating shaft 17.

[0013] The support member 15 supports the motor 14 and the harmonic drive gear reducer 16.

[0014] Motor 14 generates driving force. While motor 14 is not particularly limited, a servo motor such as an AC servo motor or a DC servo motor is preferred.

[0015] The motor 14 includes a rotating shaft 17, bearings 18 and 19, a first case 20, a second case 21, and a rotation detector 22.

[0016] The bearings 18 and 19 are rolling bearings each including an inner ring and an outer ring. Both ends of the rotating shaft 17 are fixed to the inner rings of the bearings 18 and 19 by interference fitting. The outer ring of the bearing 18 is supported by the second case 21. The outer ring of the bearing 19 is supported by the first case 20. The second case 21 is fixed to the support member 15 by screws or bolts.

[0017] In such a motor 14, the rotating shaft 17 is supported by the support member 15 via the bearings 18 and 19 and rotates about the axis a with respect to the support member 15. The rotating shaft 17 is connected to a rotation detector 22 that detects the rotation of the rotating shaft 17 at its b end which is the end on the bearing 19 side. Also, the rotating shaft 17 is connected to the harmonic gear reducer 16 at its c end which is the end on the bearing 18 side and transmits the driving force to the harmonic gear reducer 16.

[0018] The harmonic gear reducer 16 is a speed reducer using a harmonic gear mechanism, which reduces the rotation of the driving force input from the rotating shaft 17 and outputs it. On the output side, torque proportional to the reduction ratio can be obtained.

[0019] As shown in FIGS. 2 and 3, the harmonic gear reducer 16 includes a rigid internal gear 23, a flexible external gear 24 that partially meshes with the internal gear 23, a wave generator 25 that is connected to the rotating shaft 17, contacts the inner peripheral surface of the external gear 24, and deflects the external gear 24 to move the meshing position between the internal gear 23 and the external gear 24 in the circumferential direction, and a case 26 that covers the internal gear 23, the external gear 24, and the wave generator 25.

[0020] The internal gear 23 is a gear composed of a rigid body that does not substantially bend in the radial direction of the axis a, and is a ring-shaped internal gear having internal teeth 29. In the present embodiment, the internal gear 23 is a spur gear. That is, the internal teeth 29 have tooth flanks parallel to the axis a. Incidentally, the tooth flanks of the internal teeth 29 may be inclined with respect to the axis a. That is, the internal gear 23 may be a herringbone gear or a double helical gear. Incidentally, the internal gear 23 is fixed to the support member 15.

[0021] A ring member 35 for fastening the harmonic gear reducer 16 and an external unit is attached to the outer peripheral surface of the internal gear 23. As shown in FIGS. 4 and 5, a plurality of cutouts 36 are provided at equal intervals in the ring member 35. By measuring the outer peripheral portion of the internal gear 23 in the cutout 36, the coaxiality between the internal gear 23 and the elliptical bearing can be managed, and the assembly accuracy management can be maintained.

[0022] The external gear 24 is inserted inside the internal gear 23. The external gear 24 is a gear having a flexible cylindrical portion 31 that can be elastically deformed in the radial direction of the axis a, and is an external gear having external teeth 30 that mesh with the internal teeth 29 of the internal gear 23. Further, the number of teeth of the external gear 24 is less than the number of teeth of the internal gear 23.

[0023] The external gear 24 has a silk hat shape including a cylindrical portion 31 and a flange portion 32 that extends radially outward of the axis a from one end of the cylindrical portion 31. The external teeth 30 are formed radially outward of the axis a at the other end of the cylindrical portion 31.

[0024] The wave generator 25 includes a main body portion 38 and a bearing 39 attached to the outer periphery of the main body portion 38.

[0025] The main body portion 38 is connected to the rotating shaft 17, and when viewed from the axial direction of the axis a, the outer periphery has an elliptical or oval shape. As shown in FIG. 2, a plurality of through holes 34 penetrating the main body portion 38 along the Z axis are provided in the main body portion 38, and as shown in FIG. 3, the plurality of through holes 34 are provided at the same position from the rotating shaft 17.

[0026] Therefore, the first region R1 formed by the external gear 24 and the wave generator 25, and the second region R2 formed by the wave generator 25, the motor 14, and the support member 15 can be connected by the through hole 34. Consequently, after assembling the drive unit 1, grease can be injected from the first region R1 side, allowing the grease to pass through the through hole 34 and fill the second region R2. This means that grease filling can be completed in one step during the assembly of the drive unit 1, reducing the assembly process.

[0027] The bearing 39 is a rolling bearing comprising a flexible inner ring 40 and outer ring 41, and a plurality of balls 42 positioned between them. The inner ring 40 is fitted onto the outer circumference of the main body 38 and elastically deforms in an elliptical or oblong shape along the outer surface of the main body 38. Consequently, the outer ring 41 also elastically deforms in an elliptical or oblong shape. The outer surface of the inner ring 40 and the inner surface of the outer ring 41 serve as raceway surfaces that guide and roll the plurality of balls 42 along the circumferential direction. The plurality of balls 42 are held by a cage (not shown) to maintain a constant spacing between them in the circumferential direction.

[0028] The wave generator 25 is inserted inside the external gear 24 and is rotatable around axis a. The wave generator 25 contacts the inner circumferential surface of the cylindrical portion 31 of the external gear 24, and bends the cylindrical portion 31 into an elliptical or oblong shape with the major axis La and the minor axis Lb, thereby partially engaging the external teeth 30 with the internal teeth 29 of the internal gear 23. Here, the external gear 24 and the internal gear 23 are rotatable around axis a and mesh with each other internally and externally.

[0029] In such a wave drive gear reducer 16, when the driving force from the motor 14 is input to the wave generator 25, the internal gear 23 and the external gear 24 rotate relative to each other around axis a due to the difference in the number of teeth, while their meshing positions move in the circumferential direction. As a result, the rotation of the driving force input to the wave generator 25 from the rotating shaft 17 of the motor 14, which is the driving source, is reduced and output from the external gear 24. Then, on the output side, a torque proportional to the reduction ratio can be obtained. In other words, a gear reducer can be realized with the wave generator 25 as the input side and the external gear 24 as the output side.

[0030] Next, an example of how to assemble the drive unit 1 in this embodiment will be briefly described. However, the assembly of the motor 14 will be omitted. Also, the order of assembly is not limited to the following.

[0031] First, the motor 14 is assembled to the support member 15. At this time, the second case 21 of the motor 14 comes into contact with the support member 15. Also, the outer ring of the bearing 18, whose inner ring is fixed to the rotating shaft 17 of the motor 14 by an interlocking fit, is supported by the second case 21.

[0032] Next, the wave generator 25 and the rotating shaft 17 of the motor 14 are fixed together. The method of fixing is not particularly limited, but in addition to fixing with screws or bolts, fixing may also be done with adhesive, welding, etc.

[0033] Next, the external gear 24 is rotatably assembled to the internal gear 23. The assembly method is not particularly limited, but the flange portion 32 can be fixed to the case 26 by screws or bolts, adhesive, welding, etc.

[0034] Next, the internal gear 23 is assembled to the support member 15. The assembly method is not particularly limited, but examples include fixing with screws or bolts, adhesive, welding, press-fitting, shrink-fitting, etc.

[0035] Next, by assembling the motor 14 and the wave drive gear reducer 16, a first region R1 is formed by the external gear 24 and the wave generator 25, a second region R2 is formed by the wave generator 25, the motor 14, and the support member 15, and by injecting grease into the first region R1, the first region R1 and the second region R2 are filled with grease.

[0036] With the above steps, the drive unit 1 is complete.

[0037] According to this embodiment, the following effects can be obtained.

[0038] According to this embodiment, since the wave generator 25 is provided with a through hole 34 connecting the first region R1 and the second region R2, after assembling the motor 14 and the wave gear reducer 16, grease is injected into the first region R1, causing the grease to flow from the through hole 34 into the second region R2. This allows grease to be filled into both the first region R1 and the second region R2, requiring only one grease filling operation, reducing the assembly process, and lowering the cost of the drive unit 1.

[0039] Furthermore, according to this embodiment, a ring member 35 is attached to the outer circumferential surface of the internal gear 23 of the wave drive gear reducer 16, and a plurality of notches 36 are provided in the ring member 35. By measuring the outer circumferential portion of the internal gear 23 at the notches 36, the coaxiality between the internal gear 23 and the elliptical bearing can be managed, and assembly accuracy can be maintained.

[0040] 2. Second Embodiment A robot 100 having a drive device 1 according to the first embodiment will be described with reference to Figure 6.

[0041] In Figure 6, the vertical direction coincides with the vertical direction, and the upper side of the paper is also referred to as "up" and the lower side as "down". For robot arms 72, the first arm 73, and the second arm 74, the right side in Figure 6 is also referred to as the "base end" and the left side as the "tip end".

[0042] Furthermore, in this specification, "vertical" means not only when it coincides with the vertical, but also when it is slightly inclined from the vertical, for example, within ±10°. Furthermore, in this specification, "parallel" means not only when two objects coincide parallel to each other, but also when they are slightly inclined from parallel, for example, within ±10°.

[0043] The robot 100 of this embodiment is equipped with drive units 1 assembled according to the assembly method of the drive unit 1 of the first embodiment at the first joint 10K and the second joint 20K. The drive unit 1 located at the first joint 10K and the drive unit 1 located at the second joint 20K have substantially the same configuration except for differences in torque and rotational speed.

[0044] In this embodiment, robot 100 is a SCARA robot and is used for various tasks such as holding, transporting, assembling, and inspecting workpieces such as electronic components. However, the application of robot 100 is not particularly limited. Furthermore, robot 100 may be other than a SCARA robot, such as a 6-axis articulated robot or a dual-arm robot.

[0045] As shown in Figure 6, the robot 100 includes a base 71, a robot arm 72 rotatably connected to the base 71, and a robot control device 9 that controls the driving of each part of the robot 100. The robot arm 72 also includes a first arm 73 whose base end is connected to the base 71 and which rotates around a first rotation axis J1 perpendicular to the base 71, and a second arm 74 whose base end is connected to the tip of the first arm 73 and which rotates around a second rotation axis J2 perpendicular to the first arm 73.

[0046] A working head 75 is provided at the tip of the second arm 74. The working head 75 has a spline nut 751 and a ball screw nut 752 arranged coaxially at the tip of the second arm 74, and a spline shaft 753 inserted through the spline nut 751 and the ball screw nut 752. The spline shaft 753 is rotatable about a third rotation axis J3 which is the central axis of the second arm 74 and runs vertically along it, and is also vertically movable along the third rotation axis J3.

[0047] An end effector 76 is attached to the lower end of the spline shaft 753. The end effector 76 is detachable from the spline shaft 753, and the appropriate one can be selected for the intended work.

[0048] The robot 100 has a first joint 10K that rotatably connects the base 71 and the first arm 73, and a drive device 1 is installed on this first joint 10K that rotates the first arm 73 around a first rotation axis J1 relative to the base 71.

[0049] Furthermore, the robot 100 has a second joint 20K that rotatably connects the first arm 73 and the second arm 74, and a drive device 1 is installed in this second joint 20K that rotates the second arm 74 around the second rotation axis J2 relative to the first arm 73.

[0050] Furthermore, the robot 100 includes a first drive mechanism 791 that rotates a spline nut 751 to rotate the spline shaft 753 around a third rotation axis J3, and a second drive mechanism 792 that rotates a ball screw nut 752 to raise and lower the spline shaft 753 in a direction along the third rotation axis J3. The second drive mechanism 792 is installed below the first drive mechanism 791.

[0051] The drive unit 1 located at the second joint 20K is positioned closer to the tip than the drive unit 1 located at the first joint 10K. Furthermore, the spline nut 751, ball screw nut 752, spline shaft 753, first drive mechanism 791, and second drive mechanism 792 are all positioned closer to the tip than the drive unit 1 located at the second joint 20K.

[0052] The robot 100 of this embodiment is equipped with a drive unit 1 that allows for easy grease filling of the first region R1 formed by the external gear 24 and the wave generator 25, and the second region R2 formed by the wave generator 25, the motor 14, and the support member 15, thus achieving excellent reliability. [Explanation of Symbols]

[0053] 1...Drive unit, 14...Motor, 15...Support member, 16...Wave gear reducer, 17...Rotating shaft, 18,19...Bearings, 20...First case, 21...Second case, 22...Rotation detector, 23...Internal gear, 24...External gear, 25...Wave generator, 26...Case, 29...Internal teeth, 30...External teeth, 31...Cylindrical part, 32...Flange part, 34...Through hole, 35...Ring member, 36...Notch, 38...Main body part, 39...Bearing, 40...Inner ring, 41...Outer ring, 42...Ball, 100...Robot, a...Axis, La...Long axis, Lb...Short axis, R1...First region, R2...Second region.

Claims

1. A drive device comprising a motor having a rotating shaft and a harmonic drive gear reducer for reducing the rotation of the rotating shaft, The aforementioned wave drive gear reducer is Internal gears and A flexible external gear that partially meshes with the internal gear, It includes a wave generator connected to the rotating shaft, in contact with the inner circumferential surface of the external gear, and bending the external gear to move the meshing position between the internal gear and the external gear in the circumferential direction, A first region formed by the external gear and the wave generator, and filled with grease, The wave generator and the motor form a second region which is filled with the grease, The wave generator is provided with a through hole connecting the first region and the second region. Drive unit.

2. Furthermore, it includes a support member that supports the motor and the harmonic drive gear reducer, The second region is formed from the wave generator, the motor, and the support member. The drive device according to claim 1.

3. The wave generator is provided with multiple through holes, Multiple through holes are at the same distance from the axis of rotation. The drive device according to claim 1.

4. The aforementioned wave drive gear reducer has a ring member attached to the outer circumferential surface of the internal gear, The ring member has a notch, The drive device according to claim 1.

5. Having the drive device described in claim 1, robot.

6. A method for assembling a drive device comprising a motor having a rotating shaft and a harmonic drive gear reducer for reducing the rotation of the rotating shaft, The aforementioned wave drive gear reducer is Internal gears and A flexible external gear that partially meshes with the internal gear, It includes a wave generator connected to the rotating shaft, in contact with the inner circumferential surface of the external gear, and bending the external gear to move the meshing position between the internal gear and the external gear in the circumferential direction, A first region formed by the external gear and the wave generator, and filled with grease, The wave generator and the motor form a second region which is filled with the grease, The wave generator is provided with a through hole connecting the first region and the second region. After assembling the motor and the harmonic drive gear reducer, The grease is injected into the first region, thereby filling the first region and the second region with the grease. How to assemble the drive unit.

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