JPS58196349A - Driving apparatus - Google Patents

Abstract

PURPOSE:To permit centering of harmonic drive apparatus with high accuracy by setting a sphere in a concentric circular groove formed by two opposed circular splines. CONSTITUTION:A flex-spline 21 which is elastically deformable through a bearing 28 relative to a wave generator 25 is engaged with circular splines 15 and 16 each of which has different number of teeth, and thus a harmonic drive apparatus is constituted. The circular splines 15 and 16 each of which having a V- groove are pressed through a steel ball 20 by thrust forces 26 and 27, and each concentricity of the both circular splines 15 and 16 can be kept with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive device, and in particular to the well-known 7
The purpose is to accurately center the fumonic drive device.

Conventionally, for the purpose of obtaining a large reduction ratio, the
A drive device called a harmonic drive device as shown in FIG. 2 is used. Fig. 1 is a diagram explaining the principle of operation of the spline, which has a circular spline 1 having 21 internal teeth, and external teeth having the number of teeth (Zl-2), and has some radial direction. It is composed of a flexible spline 3, a generator 2 having an oval cross section, and a group of steel balls 4 arranged between the flexible spline and the generator. The circular spline 1 and the flexible spline 3 mesh at two locations on the circumference. Now, when the generator 2 rotates once, the meshing point between the circular spline 1 and the flexible spline 3 rotates once, and both rotate by a pitch of 2l-(Zl-2)=2, that is, two teeth relative to each other. do. In the end, for one rotation of the generator, the circular spline 1 and the flexible spline 3 move relative to each other by 2/Z1 rotations.The above is the operating principle of a drive device called a harmonic drive.The one in Figure 2 2 is an application example using this circular spline 6 and 6 to facilitate integration into equipment.
．． The flexible spline 7 is engaged with the circular spline 6, and radially flexible ball bearings 8 and 9 are mounted in correspondence with the circular spline. A wave generator 1o having an elliptical cross section is attached to the inner ring of the bearing. here,
Assuming that there is a difference of two teeth between the number of teeth 22 of the circular spline 5 and the number of teeth 23 of the circular spline 6, and that the number of teeth of the flexible spline is the same as the number of teeth 22 of the circular spline 6, FIG. According to the principle, when the generator 1o rotates once, the circular spline 6 and the flexible spline 7 rotate by 2/Z2. On the other hand, circular spline 6 and flexible spline are
Since the number of teeth is the same, there is no change in the relative relationship. in the end,
Circular splines 6 and 6 are relatively 2/Z2
It will rotate. Generally, Z2 can have around 200 sheets, and the reduction ratio is 2/200, that is, 1.
It can be ranked 7100th.

In this way, a characteristic of the harmonic drive device is that a large reduction ratio can be obtained with just one device.

However, with the structure shown in Figure 2, it is difficult to reliably match the concentricity of the circular spline 6, 6, flex spline 7, etc., and as a result, irregularities may occur in the meshing between the circular spline and the flex spline. This may cause damage. In order to solve this kind of trouble, for example, a method as shown in FIG. 3 is adopted. The example shown in FIG. 3 was devised for the purpose of eliminating the above-mentioned trouble by keeping the concentricity of the circular spline 5°6 and the flexible spline 7 the same.
0 through a ball bearing 13 and a bracket 12, so that both can rotate relative to each other and are designed to ensure concentricity. However, as can be seen from the figure, the configuration shown in FIG. 3 has the disadvantage that it is too thick compared to the configuration shown in FIG.

A first object of the present invention is to provide a drive device that is compact and capable of accurately transmitting power by eliminating these drawbacks of conventional products. Further, the drive device of the present invention includes:
As will be described later, the second purpose is to provide a drive device that can achieve an even greater effect by using two in parallel, and that can accurately transmit power when two are used. .

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 4 to 7. In FIG. 4, circular spline 16
,16. Flex spline 21° generator 25
and an outer ring 22. The flexible ball bearing 28, which consists of an inner ring of 24° steel balls 23, has the same basic structure as the conventional product shown in FIG. A simple but very effective countermeasure has been taken. Next, the difference will be explained. Circular spline 16. As shown in FIG. 5, a V-shaped groove 27 is provided inside the grooves 16 and 16, and a steel ball 20 is fitted in both grooves over the entire circumference of the groove. In addition, a retainer 19 is provided to prevent each steel ball from interfering with each other. When this drive mechanism is actually used, an external force is applied in the directions of arrows 26 and 27, as will be described in detail later.

The second difference lies in the relationship between the flexible ball bearing 28 and the generator 26. In Fig. 4, flexible ball bearing 2
8 has a double row, and the races of steel balls in each row correspond to the circular splines 15 and 16. The generator 25 has a cylindrical portion 29 at its center.
Both parts 1 are provided with a slight roundness 30. With this configuration, as shown in FIG. 5, the reaction forces 31 and 3 that the flex spline 21 receives when the circular spline and flex spline engage
The combined forces of the two forces are transmitted to the inner ring 24 via the steel balls 23 as forces 33 and 34 in FIG. 7, respectively. Furthermore, this force is combined and generated by the generator 260.
It is applied to the cylindrical portion and balances the reaction force 36 of the generator.

FIG. 8 shows the circular spline 15 shown in FIG.
Thrust bearings 36, 37 instead of V groove 16
It is equipped with. By making the bearing a separate component in this way, the rolling surface of the steel ball 2o can be machined with high precision.

FIG. 9 shows an embodiment in which a robot arm or the like is driven using the drive device of the present invention. The purpose of this is to attach the arm 39' and the arm 38 rotatably around a shaft 43, and to drive both arms relative to each other in rotation by the motor 40. In order to reduce the speed and increase the torque, a drive device with the structure explained in Fig. 4 is used.
We are hiring. The circular spline 16 is fixed to both sides of the arm 390 by two screws 61.

The circular spline 16 is attached to the 7 langes 47 with screws 6
Two sets of flanges 47 are fixed to each side of the arm 38 via a spacer 48. The flanges 47 on both sides are the thrust bearings 4
6. It is tightened by a shaft 43 and a nut 43 via a washer 46. With this structure, the radial load applied to the arm 38 is reduced by the circular spline 16. Steel ball 20. circular spline 16
is transmitted to the arm 39 via.

On the other hand, the shaft 43 includes a motor 40, a pinion 41 fixed to the output shaft of this motor, and a gear 4 fixed to the shaft 43.
2, it is rotationally driven. Furthermore, this rotating operation is transmitted to the generator 26 fixed to the shaft 43,
Based on the principle mentioned above, circular spline 15
and the circular spline 16 to give relative rotational motion. Here, a spacer 48 is provided to adjust the dimension in the thrust direction when both circular splines 16.degree. 16 are tightened using the nut 44 and the dimension in the thrust direction determined by the arm 38 and the flange 47.

The embodiment shown in FIG. 10 is based on the premise of two-way use, and is further improved. 1. Two sets of circular splines 16, 16. 15
a, 16 a are engaged. Flex spline 2
1 includes 4 flexible ball bearings 28.28a, 28b, 2
8c is mounted between them via spacers 61 and 62, and is in contact with a generator (not shown) at the inner diameter of this flexible ball bearing. The inner circular splines 16 , 16 a are fixed to both sides of the arm 39 , and the outer circular splines 16 , 168 are fixed to the arm 38 . Although omitted in Fig. 10, tightening the outer circular splines 15, 16a in the thrust direction using shafts, nuts, thrust bearings, etc. is the same as that explained in Fig. 8. .

The embodiment of FIG. 11 is almost the same as that of FIG. 10, but the inner circular spline 16 in FIG.
16a is constituted by one central circular spline 53.

Next, the effects of each of the above embodiments will be explained in sequence. As shown in Fig. 4, the concentricity of both circular splines is maintained with high accuracy by pressurizing circular splines 15 and 16 with grooves through steel balls 20 with thrust forces 26 and 27. Therefore, the teeth of both circular splines 15 and 16 and the flexible spline 21 are accurately engaged. When actually used, a radial force is applied to the circular spline 1616, but it is held with high precision by the V-groove and steel balls. The embodiment shown in FIG. 9 is a mechanism devised in anticipation of this effect, and the radial load applied to the arm 38 is applied to the circular splines 15, 16, . The structure is such that the load is transmitted to the arm 39 via the steel ball 20, etc., and no load is applied to the flex spline 21° shaft 43, etc. For this reason, the rotational movement provided by the motor 4o is exactly the same as that of the motor 43. The flexible ball bearing 28 degree flexible spline 21 and the like are driven, and as a result, both circular splines 15 and 16 can be accurately driven relative to each other. A major feature is that by separating the radial load transmission system and the rotational motion transmission system, accurate transmission can be achieved.

In addition, in Fig. 9, two drive mechanisms shown in Fig. 4 are used on both sides, and both generators are driven by one shaft 43, but the rotation center of both generators is determined by the rotation center of the flex spline. At the same time as the bearing 4
It is also determined from the center of rotation of the shaft 43 supported by 6. As mentioned above, since the bearing 46 is a thrust bearing, it has very high rigidity in the thrust direction, but has some flexibility in the radial direction. It can be adapted to some extent to the center of rotation determined by the flex spline.

Furthermore, as explained in FIGS. 6 and 7, by receiving the force 31.32 from the circular spline at one location in the center of the generator, the error in the center of rotation of the tooth surface of the circular spline 15.16 can be reduced. As a result, it is possible to avoid overloading the tooth surface.

In the embodiment shown in FIG.
0. It is transmitted to the arm 39 via the circular spline 16° 16a and is securely supported on both sides. On the other hand, as mentioned above, the rotational movement is performed by one generator via the four flexible ball bearings 38.28a, 28b, and 28c.
1 This flex spline is being driven. in this way,
Since two sets of circular splines are driven by 1 this generator and 1 this flex spline,
The phases of the two sets of drive mechanisms can be easily made the same.

The embodiment shown in Fig. 11 was also devised with the expectation of the same effect as Fig. 10, but the inner circular spline 6
3 are integrated, so compared to Fig. 10, the inner circular spline is 16°'. FIG. 3 is a half-sectional view of a conventional driving device that maintains the concentricity of the circular spline, and FIG. 4 is a cross-sectional view of a driving device according to an embodiment of the present invention. 6 is a perspective view of a circular spline with a V-groove, and FIG. 6 is a schematic diagram illustrating a situation in which a force applied from the south side is transmitted to a generator in a drive device according to an embodiment of the present invention.
Figure 7 is an explanatory diagram of the force balance situation explained in Figure 6;
Fig. 8 is a cross-sectional view of a curus spline equipped with a dedicated bearing, and Fig. 9 is a cross-sectional view of a joint of a robot arm using two drive devices according to an embodiment of the present invention.
Figure 10 is a sectional view of a device in which two sets of drive devices are configured for one Tourex spline, and Figure 11 is a cross-sectional view of a device in which two circular splines inside the device in Figure 10 are configured into one. FIG.

15.16...Circular spline, 20.
... Steel ball, 21 ... Flexible spline, 2
6... Generator, 29... Groove, 4
3...shaft, 46...bearing.

Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 1 Figure 2 Figure 3 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11

Claims (1)

[Claims] (1) A driving shaft that is rotatable and is provided with rotational force;
a generator that is elliptical and rotatable and transmits the rotational force of the driving shaft; and a generator that has a plurality of teeth on its outer circumferential surface, that contacts the outer circumferential surface of the generator on its inner circumferential surface, and that is elastic as the generator rotates; a deformable flex spline; the inner surface has teeth having the same pitch as the flex spline and the same number of teeth as the flex spline and more teeth than the flex spline, and can mesh with teeth on the outer periphery of the flex spline;
and two circular splines whose perpendicular surfaces to the axial direction face each other and each having a groove on a concentric circle of the opposed surfaces, and a ball provided so as to be able to fit into each groove of the circular spline. A drive device consisting of. (2) The driving device 0 according to claim 1, wherein the circular spline having the groove removably has a groove and a component having a ball that can fit into the groove. 2. The drive device according to claim 1, wherein two sets of splines are provided, and one flexible spline is provided so as to be able to mesh with the two sets of circular splines. (4) The drive device according to claim 3, wherein in the two sets of circular splines, the inner circular splines are the same. (6) Two sets of each of the generator, flex spline, circular spline, and sphere are provided concentrically and spaced apart from each other by a predetermined distance, and the driving shaft can be tightened in the axial direction and rotated around the axis. 2. The drive device according to claim 1, wherein the drive device has two bearings, the two bearings are tightened close to each other, and the two sets of outer circular splines are pressed.