JP2017089804A - Wave gear device with traction drive mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wave gear device capable of realizing a low reduction ratio without changing the number of teeth of an internal gear by utilizing a roller bearing type traction drive mechanism.SOLUTION: A wave gear device 1 has a wave gear mechanism 2 and a roller bearing type traction drive mechanism 3. A wave generator bearing 23 for the wave gear mechanism 2 may act as the roller bearing type traction drive mechanism 3 to increase speed of input rotation inputted to the holder input shaft 24 and to transmit it to a wave generator plug 21. Increased speed rotation of the wave generator plug 21 is decreased through the wave gear mechanism 2 and outputted from its external gear 12. It is possible to realize a low reduction ratio of the wave gear mechanism without changing the number of teeth of an internal gear of a present wave gear mechanism.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wave gear device having a reduced speed ratio, and more particularly to a wave gear device that realizes a reduced speed ratio using a rolling bearing type traction drive mechanism.

  In the wave gear device, the input / output member is located on the same axis, a high reduction ratio is obtained in one stage, and has a high torque capacity, excellent positioning accuracy, and excellent rotation accuracy. The reduction ratio of current wave gear devices is generally 1/30 to 1/160.

  In recent years, with respect to a wave gear device, a higher speed operation of an actuator in which the wave gear device is incorporated is required, and a demand for a lower speed ratio is increasing. In order to reduce the speed ratio of the wave gear device, the speed ratio of the current wave gear device is used, and the number of teeth of the internal gear (circular spline) is changed by 4 from the external gear (flex spline), There is a method of making a difference of 6 sheets. In this case, it is necessary to design the internal gear separately.

  On the other hand, a traction drive mechanism is known as a deceleration mechanism. As a traction drive mechanism, a planetary roller type traction drive mechanism as described in Patent Document 1 has been proposed. A rolling bearing type traction drive mechanism is also known.

Japanese Utility Model Publication No. 04-52510

  Here, in realizing the reduction speed ratio of the wave gear device, it is possible to realize the reduction speed ratio while maintaining its excellent characteristics without changing the number of teeth of the internal gear of the current wave gear device. desirable.

  In view of this point, an object of the present invention is to provide a wave gear device that can realize a reduction in speed ratio without changing the number of teeth of an internal gear by using a rolling bearing type traction drive mechanism. .

  In order to solve the above problems, the wave gear device of the present invention includes a rolling bearing type traction drive mechanism and a wave gear mechanism. The traction drive mechanism includes an outer ring that is fixed so as not to rotate, an inner ring that is a rotation output element, a rolling element that is mounted on a raceway formed between the outer ring and the inner ring in a freely rollable state, A rolling element holder, which is a rotation input element, holds the moving body in a rotatable state at a predetermined angular interval. The wave gear mechanism also includes a rigid internal gear, a flexible external gear that can be bent in the radial direction, and a non-circular bending of the external gear to partially mesh with the internal gear, A wave generator that rotates integrally with the inner ring and moves the meshing position of both gears in the circumferential direction is provided.

  A rolling bearing type traction drive mechanism is generally used as a speed reducer using the rolling element holder as an output element. In the present invention, the traction drive mechanism is used as a speed increaser. In other words, the rolling element cage is a rotation input element, and the inner ring is a rotation output element. The increased rotational output from the traction drive mechanism is transmitted to the wave generator of the wave gear mechanism. The reduction ratio of the wave gear mechanism is lowered by the speed increase.

  For example, an existing wave gear reducer having a reduction ratio of 1/30 is used as the wave gear mechanism. High-speed rotation is input from a motor or the like to the rolling element holder of the traction drive mechanism. If the traction drive mechanism has a rolling element bearing structure that obtains a speed increase of 2.5 times, for example, the rotation of the wave generator of the wave gear mechanism is increased by 2.5 times the input rotation. As a result, the overall reduction ratio of the wave gear device is 1/12. Therefore, a wave gear device with a reduced speed ratio can be obtained.

  According to the present invention, the characteristics (high torque capacity, excellent positioning accuracy, excellent rotation accuracy) of the wave gear mechanism are maintained without changing the number of teeth of the constituent gears of the wave gear mechanism, compared with the conventional one. A wave gear device with a low reduction ratio can be realized.

  Here, an input shaft portion may be formed integrally with the rolling element holder, and a rotation shaft such as a motor rotation shaft may be connected to the input shaft portion to input rotation.

  In this case, when the wave gear mechanism and the traction drive mechanism are arranged in the direction of their axial lines, the overall axial length of the wave gear device becomes long. Therefore, in the present invention, a structure in which the traction drive mechanism is integrated with the wave gear mechanism is adopted.

  That is, in the wave gear device of the present invention, the wave generator is rotatably supported on the outer peripheral surface of the input shaft portion of the rolling element holder via the support bearing. The wave generator includes a rigid plug having a non-circular outer peripheral surface and a wave generator bearing attached to the outer peripheral surface of the plug and deflected in a non-circular shape. The outer ring, inner ring, and rolling element in the wave generator bearing are used as the outer ring, inner ring, and rolling element of the traction drive mechanism, respectively.

  In the wave gear mechanism, the wave generator bearing of the wave generator is bent non-circularly by its plug and partially meshes the external gear with the internal gear. The rolling elements of the wave generator bearing located at the portion corresponding to the meshing position of both gears are in a state in which preload is applied in the radial direction. Therefore, by using the rolling element holder of the wave generator bearing as a rotation input element, the wave generator bearing can function as a traction drive mechanism as it is.

Next, the wave gear device of the present invention is
A rigid internal gear,
A radially-flexible flexible external gear that is coaxially disposed inside the internal gear;
A wave generator that is coaxially mounted inside the external gear, flexes the external gear into a non-circular shape, and partially meshes with the internal gear;
A rotating shaft coaxially disposed inside the wave generator;
Have
The wave generator is
A rigid plug supported in a freely rotatable state by the rotary shaft via a support bearing;
A wave generator bearing fitted between the non-circular outer peripheral surface of the plug and the inner peripheral surface of the external gear forming portion of the external gear;
With
The wave generator bearing is
An outer ring fitted on the inner peripheral surface of the outer tooth forming portion;
An inner ring fitted on the non-circular outer peripheral surface of the plug;
A rolling element mounted in a freely rollable state between the outer ring and the inner ring;
A rolling element holder that holds the rolling elements at a predetermined angular interval in a freely rollable state and rotates integrally with the rotating shaft;
It is characterized by having.

It is the cross-sectional view and longitudinal cross-sectional view which show an example of the wave gear apparatus of the structure with which the traction drive mechanism to which this invention was applied was integrated. It is a longitudinal cross-sectional view which shows the reference example of the wave gear apparatus provided with the traction drive mechanism.

  Embodiments of a wave gear device to which the present invention is applied will be described below with reference to the drawings.

  FIG. 1A is a transverse sectional view showing a transverse section when the wave gear device according to the first embodiment is cut along a plane orthogonal to the central axis, and FIG. 1B includes the central axis. It is a longitudinal cross-sectional view which shows the longitudinal cross section at the time of cut | disconnecting by a plane.

  The wave gear device 1 includes a wave gear mechanism 2 and a traction drive mechanism 3 incorporated in the wave gear mechanism 2. The wave gear mechanism 2 includes a ring-shaped rigid internal gear 11, a cup-shaped flexible external gear 12 that is coaxially disposed on the inside thereof, and a wave generator that is coaxially fitted on the inside. 13. In this example, the external gear 12 is bent elliptically by the wave generator 13 and meshes with the internal gear 11 at the position of the elliptical long axis L1.

  In this example, the wave gear mechanism 2 including the cup-shaped external gear 12 is used, but a wave gear mechanism including a top hat-shaped external gear may be used. Moreover, a wave gear mechanism called a flat type in which a cylindrical external gear is arranged inside two internal gears and reduced rotation is output from one of the internal gears may be used. Furthermore, in this example, the external gear 12 is bent into an elliptical shape by the wave generator 13, and the two gears 11 and 12 are engaged at two positions in the circumferential direction. The external gear may be bent non-circularly and meshed with the internal gear at three or more positions.

  In the wave gear mechanism 2, when the wave generator 13 rotates, the meshing position of both gears 11, 12 moves in the circumferential direction. When the wave generator 13 rotates once, relative rotation occurs between both gears by the difference in the number of teeth of both gears 11 and 12. For example, the internal gear 11 is fixed so as not to rotate, and the external gear 12 is connected to a load member (not shown). In this case, the rotation of the wave generator 13 is decelerated according to the difference in the number of teeth and is output from the external gear 12 to a load member (not shown).

  The external gear 12 includes a cylindrical body 14 that can be bent in the radial direction, a diaphragm 15 that extends radially inward from the rear end thereof, and an annular shape that is formed continuously from the inner peripheral edge of the diaphragm 15. A rigid boss 16 is provided. A portion of the cylindrical body portion 14 on the front end opening side is an external tooth forming portion 17, and external teeth 18 are formed on the outer peripheral surface thereof.

  The wave generator 13 is fitted inside the external tooth forming portion 17 of the external gear 12. The wave generator 13 includes a rigid wave generator plug 21 having a cylindrical shape, and a wave generator bearing 23 that is attached to the elliptical outer peripheral surface 22 of the wave generator plug 21 and is bent in an elliptical shape. I have. The wave generator 13 includes a hollow rotating shaft (cage input shaft) 24 that is coaxially disposed in the hollow portion of the wave generator plug 21, and the hollow rotating shaft 24 is a ball bearing attached to the outer peripheral surface thereof. The wave generator plug 21 is supported in a freely rotatable state via a support bearing 25 composed of

  The wave generator bearing 23 includes an outer ring 26 fitted to the inner peripheral surface 19 of the external tooth forming portion 17 of the external gear 12, an inner ring 27 fitted to the elliptical outer peripheral surface 22 of the wave generator plug 21, and the outer ring 26 and A plurality of rolling elements 28 mounted in a freely rolling manner on the track between the inner rings 27, and a rolling element holder 30 holding the rolling elements 28 so as to be rotatable at regular angular intervals in the circumferential direction. And.

  The rolling element holder 30 is formed integrally with an outer shaft end portion 24a of the hollow rotary shaft 24, and has a disk-shaped arm portion 31 (or a plurality of radially extending portions) extending radially outward from the shaft end portion 24a. And a plurality of rolling element holding portions 32 that are bent at right angles from the outer peripheral end of the arm portion 31 and are inserted between the rolling elements 28. Since each rolling element 28 is held in a freely rotatable state between the adjacent rolling element holding portions 32, each rolling element 28 can roll along the raceway surfaces of the outer ring 26 and the inner ring 27.

  In this example, a ball bearing is used as the wave generator bearing 23. As the wave generator bearing 23, various bearings such as a roller bearing can be used.

  In the wave gear mechanism 2, the wave generator bearing 23 is bent in an elliptical shape by the wave generator plug 21, and the rolling elements 28 located near the elliptical long axis L 1 are preloaded in the radial direction. It becomes a state. Therefore, by using the rolling element holder 30 of the wave generator bearing 23 as a rotation input element, the wave generator bearing 23 functions as the traction drive mechanism 3 as it is.

  In the wave gear device 1, when the hollow rotary shaft 24 integrally formed with the rolling element holder 30 is rotated, the inner ring 27 of the wave generator bearing 23 that functions as the traction drive mechanism 3 rotates at an increased speed. Therefore, the elliptical wave generator plug 21 to which the inner ring 27 is attached also rotates at a higher speed. For example, the dimensions of the component parts of the wave generator bearing 23 are set, and the traction drive mechanism 3 having a speed increasing ratio of 2.5 is configured.

  The wave generator plug 21 that rotates at a speed of 2.5 times moves the meshing position of the two gears 11 and 12 of the wave gear mechanism 2 in the circumferential direction, and the relative rotation generated between the two gears 11 and 12 is caused. , And output from the external gear 12 to a load side (not shown). It is assumed that the reduction ratio of the wave gear mechanism 2 is 1/30 that can be realized by the current wave gear device. In this case, the rotation input to the hollow rotary shaft 24 is increased by 2.5 times by the traction drive mechanism 3 and then reduced to 1/30. From the external gear 12 which is a decelerated rotation output element, the rotation whose input rotation is decelerated to 1/12 is taken out. Therefore, a wave gear device having a reduction speed ratio of 1/12 can be realized.

(Reference example)
FIG. 2 is a longitudinal sectional view showing a reference example of the wave gear device provided with the traction drive mechanism. In the wave gear device 100, a wave gear mechanism 110 and a traction drive mechanism 120 are connected in tandem in the direction of the central axis 100a. Although the axial length of the wave gear device 100 is increased, the speed increasing ratio of the traction drive mechanism 120 can be easily designed.

  The wave gear mechanism 110 is the same as a general wave gear mechanism, and includes a rigid internal gear 111, a flexible external gear 112 disposed coaxially with the rigid internal gear 111, and an elliptical shape fitted inside the external gear 112. And a contour wave generator 113. The external gear 112 has, for example, a cup shape, and a wave generator 113 is mounted inside the external tooth forming portion 114.

  The wave generator 113 includes a cylindrical hub 115, a wave generator plug 116 attached to the outer peripheral surface of the hub 115 via an Oldham coupling, and a wave attached to the elliptical outer peripheral surface of the wave generator plug 116. Generator bearing 117.

  The traction drive mechanism 120 is a rolling bearing type mechanism, and the rolling bearing portion 121 includes an outer ring 122, an inner ring 123, and a plurality of rolling elements 124 that are mounted so as to be capable of rolling therebetween. And a rolling element holder 125 that holds the rolling element 124 in a state of being freely rotatable at equal angular intervals in the circumferential direction. A cage input shaft 126 is integrally formed coaxially with the rolling element cage 125.

  A support bearing 127 is coaxially disposed on the side of the wave gear mechanism 110 in the rolling bearing portion 121 of the traction drive mechanism 120. An output shaft 130 is fitted in the inner ring 123 of the rolling bearing 121 and the inner ring 128 of the support bearing 127. The outer ring 122 of the rolling bearing part 121 and the outer ring 129 of the support bearing 127 are fixed to a fixed side member such as a device housing (not shown), and the output shaft 130 rotates via the rolling bearing part 121 and the support bearing 127. In a free state, it is supported by a fixed side member (not shown).

  A small-diameter shaft coupling portion 131 extends coaxially on the shaft end surface on the wave gear mechanism 110 side of the output shaft 130 of the traction drive mechanism 120. The shaft coupling portion 131 is attached to the central shaft hole of the hub 115 of the wave gear mechanism 110 and is coaxially coupled so as to rotate integrally with the hub 115.

  In the wave gear device 100, when the cage input shaft 126 of the traction drive mechanism 120 is rotated, the output shaft 130 rotates at an increased speed. The accelerated rotation is input to the wave generator 113 of the wave gear mechanism 110 connected to the output shaft 130. When the wave generator 113 rotates, the meshing position of the two gears 111 and 112 moves in the circumferential direction, and a relative rotation according to the difference in the number of teeth occurs between the two gears. For example, the internal gear 111 is fixed, and the reduced speed rotation is output from the external gear 112 to a load side (not shown).

  The rotation increased by the traction drive mechanism 120 is decelerated by the wave gear mechanism 110 and output to the load side. Therefore, a wave wave gear reduction device with a low speed ratio can be realized using the existing wave gear mechanism.

DESCRIPTION OF SYMBOLS 1 Wave gear apparatus 2 Wave gear mechanism 3 Traction drive mechanism 11 Internal gear 12 External gear 13 Wave generator 14 Cylindrical trunk | drum 15 Diaphragm 16 Boss 17 External tooth formation part 18 External tooth 19 Inner peripheral surface 21 Wave generator plug 22 Ellipse Outer peripheral surface 23 Wave generator bearing 24 Hollow rotating shaft (Cage input shaft)
24a Shaft end 25 Support bearing 26 Outer ring 27 Inner ring 28 Rolling body 30 Rolling body holder 31 Arm 32 Rolling body holding part L1 Long axis

Claims (2)

Rolling bearing type traction drive mechanism,
A wave gear mechanism;
Have
The traction drive mechanism is
An outer ring fixed so as not to rotate,
An inner ring which is a rotation output element;
A rolling element mounted in a freely rollable state on an annular raceway formed between the outer ring and the inner ring;
A rolling element holder that is a rotational input element that holds the rolling element at a predetermined angular interval in the rotatable state;
With
The wave gear mechanism is
A rigid internal gear,
A flexible external gear capable of bending in a radial direction;
A wave that bends the outer gear into a non-circular shape, partially meshes with the inner gear, rotates together with the inner ring of the traction drive mechanism, and moves the meshing position of both gears in the circumferential direction. A generator,
With
The rolling element cage includes an input shaft portion,
The wave generator is supported on the outer peripheral surface of the input shaft portion via a support bearing in a rotatable state.
The wave generator includes a rigid wave generator plug having a non-circular outer peripheral surface, and a wave generator bearing attached to the outer peripheral surface of the wave generator plug and bent in a non-circular shape. And
The wave generator bearing is a wave gear device including the outer ring, the inner ring, and the rolling element. A rigid internal gear,
A radially-flexible flexible external gear that is coaxially disposed inside the internal gear;
A wave generator that is coaxially mounted inside the external gear, flexes the external gear into a non-circular shape, and partially meshes with the internal gear;
A rotating shaft coaxially disposed inside the wave generator;
Have
The wave generator is
A rigid wave generator plug supported in a rotatable state by the rotary shaft via a support bearing;
A wave generator bearing fitted between a non-circular outer peripheral surface of the wave generator plug and an inner peripheral surface of an external tooth forming portion of the external gear;
With
The wave generator bearing is
An outer ring fitted on the inner peripheral surface of the outer tooth forming portion;
An inner ring fitted on the non-circular outer peripheral surface of the wave generator plug;
A rolling element mounted in a freely rollable state between the outer ring and the inner ring;
A rolling element holder that holds the rolling elements at a predetermined angular interval in a freely rollable state and rotates integrally with the rotating shaft;
A wave gear device comprising:

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