JPS6367401A - Rotary actuator - Google Patents

Abstract

PURPOSE:To greatly improve the stopping accuracy by limiting the flow rate of hydraulic oil flowing from the first return passage to the second return passage when an output shaft approaches the stop position. CONSTITUTION:The first return passage 27 is provided in an input shaft 20 along its axial direction. On the periphery portion of the input shaft 20, there are provided grooves 29 which extend substantially in the circumferential direction from the opening portion of the first return passage 27. In the grooves 29, the part extending from the end portion of the first return passage 27 to the front end portion of the groove 29 is set to have a cross-sectional area smaller than that of a space which is partitionedly formed with an overlapped part of one end portion of the first return passage 27 on the first or second passage 8, 9. Therefore, when an output shaft 2 approaches the stop position, it is possible to greatly limit the flow rate of hydraulic oil, so as to reduce the impact force at the time of stop, consequently for remarkably improving the stopping accuracy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rotary actuator configured to rotate an output shaft by following the angular displacement of an input shaft, and particularly relates to a rotary actuator configured to rotate an output shaft by following the angular displacement of an input shaft. This relates to a rotary actuator that can brake this.

[Prior Art] In recent years, rotary actuators, which can rotate an input shaft with a small force and obtain a large torque on an output shaft, have been increasingly used as rotational drive mechanisms for robot arms used in manibrakes and the like. This applicant has previously developed the 11th rotary actuator of this type.
The device shown in Figures 1 to 15 (Japanese Patent Publication No. 52-11399
Publication No.) was provided.

The rotary actuator shown in these figures includes a casing 1, an output shaft 2 rotatably supported within the casing, and an output shaft 2 rotatably disposed within the output shaft 2 with its axis aligned with the axis of the output shaft 2. As shown in FIG. 12, the inside of the casing l includes a rotor 4 formed on the output shaft 2, partitions 5 and 5 attached to the casing l. The hydraulic chambers are divided into first hydraulic chambers 6, 6 and second hydraulic chambers 7, 7.

The output shaft 2 is composed of a shaft body 2a and a bushing 2b fitted in the center of the shaft body 2a.
A first flow path 8,8 that opens into the hydraulic chambers 6,6, and a second flow path 9,9 that opens at one end to the second hydraulic chamber 7,7 are formed. On the other hand, the input shaft 3 is formed with a first supply channel (supply channel) 10-10 and a first return channel +1-11. The first return channels 11, 11 are
As shown in FIG. 3, the input shaft 3 is composed of a small diameter portion 11a formed on the outer circumference of the input shaft 3, and a groove 1lb-1lb extending from the small diameter portion 11a in the axial direction.

Further, as shown in FIG. 14, the first supply flow paths 10, 10 include a main hole 10a formed at the center of the input shaft 3, and a branch hole 10b formed at one end of this main hole 10a. -10
b, and a hole 10d opening in a small diameter portion 10c formed on the outer circumference of the input shaft 3. These first supply channels IO and IO and the first return channel 11-11
is determined by the relative angular position between the output shaft 2 and the input shaft 3.
The second flow path 8 and the second flow path 9 communicate with the other end of either one of the flow paths.

On the other hand, on the output shaft 2, as shown in FIG. A second supply flow path 1 communicating with the small diameter portion 10a of the supply flow path IO of
2, and a second return flow path 13 communicating with the small diameter portion 11c of the first return flow path 11 are formed. In addition, in FIG. 15, for convenience of explanation, only the bushing 2b of the output shaft 2 is shown, or the shaft body 2a is similarly formed with a second supply flow path 12 and a second return flow path I3. There is.

In such a rotary actuator, when the input shaft 3 is rotated relative to the output shaft 2,
While selectively supplying hydraulic oil to either the first hydraulic chambers 6, 6 or the second hydraulic chambers 7, 7, hydraulic oil is discharged from the other hydraulic chamber, thereby inputting the output shaft 2. It can be rotated to follow the shaft 3, and high torque can be obtained on the output shaft 2.

[Problems to be Solved by the Invention] However, when the above rotary actuator is used as a rotational drive mechanism for a robot arm, etc., a large impact force acts when the output shaft 2 stops, and the output shaft 2
Since the rotary actuator rotates beyond the normal stopping position, not only the stopping accuracy of the robot arm deteriorates, but also the output shaft 2 vibrates as it tries to return to the normal stopping position, which makes the rotary actuator and the robot arm more likely to malfunction. There was a problem that it became.

That is, in the above rotary actuator, when the output shaft 2 approaches the stop position, as shown in FIG.
Flow path 10. When If are shifted from each other in the circumferential direction, the area of the opening S formed by overlapping them gradually becomes smaller, and the flow paths 8, . . . II between the output shaft 2 and the input shaft 3 are all blocked (Fig. The output shaft 2 stops in the state shown by the two-dot chain line. However, since the second return flow path 13 of the output shaft 2 always communicates with the small diameter portion 11a of the first return flow path II with a large opening area, the output shaft 2
is located near the stop position, the hydraulic oil flows through a gap with an area approximately equal to the area of the opening S and the first
It flows into the return flow path 11 of. Therefore, the flow rate of the hydraulic oil is rarely restricted, and the output shaft 2 reaches the stop position without being braked.

[Purpose of the Invention] This invention was made to solve the above-mentioned problems, and it is possible to sufficiently brake the output shaft to reduce the impact force at the time of stopping. It is an object of the present invention to provide a rotary actuator that can not only significantly improve stopping accuracy but also prevent vibrations from occurring when stopping.

[Means for Solving the Problems] The rotary actuator of the present invention has a first return flow path provided along the axial direction, and the first return flow path is provided at the outer circumference of the input shaft or the inner circumference of the output shaft. A groove extending substantially circumferentially from the opening of the passage or the opening of the second return passage is provided, and at least a portion of the groove extending from the edge of the return passage to the tip of the groove is The cross-sectional area of the gap defined when one end of the first return flow path and the first flow path or the second flow path overlap is larger than the cross-sectional area of the groove and the opening of the return flow path facing the groove. The cross-sectional area of the gap defined by the two parts is smaller.

[Function] In the rotary actuator configured as described above, when the output shaft approaches the stop position, the flow rate of the hydraulic oil flowing from the first return passage to the second return passage is restricted, so that the output The shaft is braked and comes to a gentle stop.

[Embodiment] FIGS. 1 to 10 are diagrams showing an embodiment of the present invention. The rotary actuator of this embodiment differs from the conventional one in that a groove is formed on the input shaft.

Therefore, in the following description, the same components as those of the conventional one are given the same reference numerals, and the description thereof will be omitted.

In the figure, numeral 20 is an input shaft, and 21 is a shaft body. The shaft body 21 has first supply channels (supply channels) 22 and 22.
is formed. The first supply channels 22, 22 are
As shown in the figure, the axis line is inserted into the shaft body 21.
1, a main hole 23 formed to coincide with the axis of the main hole 23, branch holes 24 extending radially from an axially intermediate part of the main hole 23 and opening at the outer peripheral part of the shaft main body 21, 21 and a hole 26 communicating with the main hole 23. And each branch hole 24
A rectangular flat portion 24a is formed at the opening end of the opening.

In addition, a first return flow path 27 and a
27 is located at the center of the first supply channels 22 in the circumferential direction. These first return channels 27 and
27 is a communication iM 2 formed on the outer periphery of the shaft body 21
1a communicate with each other. Communication groove 21
a is for making the flow rates of the hydraulic oil flowing through the first return passages 27, 27 uniform. The first return flow path 27 is formed by forming a groove extending in the axial direction on the outer circumference of the shaft body 21, and one end thereof is located on the same circumference as the branch ports 24. is located in
The other end is located between the branch port 24 and the hole 26. At one end of the first return flow path 27, the first
A flat portion 27a is formed in the same way as the supply channel 22.

Further, at the other end of the first return flow path 27, a sub flow path (a first
A return flow path) 28, 28 is formed. Sub-channel 28
As shown in FIG. 4, the outer circumferential portion of the shaft body 2I is cut out in a substantially fan shape from the side wall portion 27a of the first return passage 27 to the outer circumferential surface of the shaft body 21. and,
A groove 29 is formed in the outer periphery of the shaft body 21 and extends from the tip of the sub flow path 28 in the circumferential direction. This groove 29 has a flat bottom surface 29a that is inclined at approximately 45 degrees with respect to the bottom 28a of the sub-channel 28, and side surfaces 29b and 29.
b.

The width of this '+b729 is approximately 0.5 nm.

On the other hand, the bush (output shaft) 30 has a second supply flow path 31 that opens on its inner and outer peripheral surfaces, and a second return flow path 32 and 3.
2 is formed. The opening of the second return flow path 32 is opened when the first supply flow paths 22, 22 and the second return flow paths 27, 27 of the input shaft 20 are all closed (see FIG. 5). The tips overlap the tips of the grooves 29, 29, and a slight gap S is defined between the grooves 29, 29.

In the rotary actuator having such a configuration, when the input shaft 20 is rotated relative to the output shaft 2, the first flow passages 8 and 8 or the second
Hydraulic oil is selectively supplied to either one of the channels 9, 9, and at the same time hydraulic oil is discharged from the other channel, thereby causing the output shaft 2 to follow the input shaft 20 and rotate. (See Figures 6 and 7). However, when the output shaft 2 rotates and reaches the groove 29, the gap in which the hydraulic oil can flow is such that the groove 29 and the second return passage 32 overlap each other, as shown in FIGS. 8 and 9. A gap S defined by
2, and its area is significantly smaller than the area of the gap S defined by the overlapping of the first return channel groove 27 and the second channel 9 (or the first channel 8). It has become.

Here, the changes in the flow rate of the hydraulic oil until the output shaft 2 reaches the stop position will be explained in detail with reference to Figure 1O.
FIG. 0 is a diagram showing the relationship between the angular deviation between the input shaft 20 and the output shaft 2 and the gap area through which hydraulic oil can flow. In the figure, the solid line indicates the area of the gap S defined by the opening of the first return passage 27 and the opening of the second passage 9 (or the first passage 8), and the broken line indicates the area of the gap S defined by the opening of the first return passage 27 and the opening of the second passage 9 (or the first passage 8). The area of the gap S defined by the opening of the return flow path 32 of No. 2 is shown. Since the flow rate of the hydraulic oil is limited by the smaller of the gap S and the gap S2, it can be seen that the flow rate is significantly limited when the angular deviation θ becomes 30°. Then, when the angular deviation becomes 01 or less, the flow rate is limited by the gap S and changes linearly until the flow rate becomes zero.

In this way, in the above-mentioned rotary actuator, when the angular deviation between the output shaft 2 and the input shaft 20 becomes 30° or less, the flow rate of the hydraulic oil is significantly restricted.
The output shaft 2 is greatly braked. Then, as the output shaft 2 approaches the stop position, the rotational speed of the output shaft 2 further decreases, and the output shaft 2 gradually stops. Therefore, not only can the accuracy of stopping the robot arm and the like be greatly improved, but also vibrations during stopping can be prevented, and failures of the robot arm and rotary actuator can be prevented. Further, in a state where the output shaft 2 is located at the stop position, there is a gap S between the groove 29 and the second discharge flow path 32.

Therefore, when the angular deviation between the output shaft 2 and the input shaft 20 is less than or equal to θ, the flow rate of the hydraulic oil is reduced to the first return flow path 2.
7 and the second flow path 9 (or the first flow path), the flow rate changes rapidly. Therefore, it is possible to improve the stopping accuracy of the output shaft 2.

In the above embodiment, the groove 29 is formed in the input shaft 20, but it may be formed in the inner circumference of the bushing 30. Also,
The bottom surfaces 29a of the two grooves are not limited to flat surfaces as in the above embodiment, but may be formed, for example, into curved surfaces that extend along the circumferential direction of the input shaft 20 and whose depth gradually decreases. It's okay.

[Effects of the Invention] As explained above, in the rotary actuator of the present invention, the first return flow path is provided along the axial direction, and the first return flow path is provided at the outer circumference of the input shaft or the inner circumference of the output shaft. A groove extending substantially circumferentially from the opening of the passage or the opening of the second return passage is provided, and at least a portion of the groove extending from the edge of the return passage to the tip of the groove is The cross-sectional area of the gap defined when one end of the first return flow path and the first flow path or the second flow path overlap is larger than the cross-sectional area of the groove and the opening of the return flow path facing this sea. Since the cross-sectional area of the gap defined by This allows the output shaft to be sufficiently braked to reduce the impact force when stopping. Therefore, not only can the stopping accuracy of the robot arm, etc. be greatly improved, but also vibration can be prevented from occurring when stopping, and failures of the robot arm and rotary actuator can be prevented. This effect can be obtained.

[Brief explanation of drawings]

1 to 10 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a side view showing the input shaft, FIG. Figure 4 is a side view showing the bushing, and Figure 4 is a side view showing the bushing.
Figure 5 is a cross-sectional view taken along the line IV--IV in the figure. Figure 5 is a cross-sectional view taken along the line ■-■ in Figure 1 in the state shown in Figure 4. Figure 6 is a cross-sectional view taken along the line ■-■ in Figure 1 in the state shown in Figure 4. Figure 7 is a cross-sectional view along the line ■-■ in the state shown in Figure 6. Figure 8 is a cross-sectional view along the line ■-■ in Figure 1 in the state shown in Figure 6. Figure 9 is a cross-sectional view taken along the line IX-IXX in Figure 1 in the state shown in Figure 8. Figure 1θ is the angular deviation between the input shaft and the output shaft, and the operation FIG. 3 is a diagram showing the relationship between the gap area and the area through which oil can flow. 11 to 16 are diagrams showing an example of a conventional rotary actuator, with FIG. 11 being a side sectional view thereof, and FIG. 12 being a first! 13 is a side view showing the input shaft, FIG. 14 is a view taken along the Xv/direction arrow in FIG. 13, and FIG. 15 is a side view showing the bushing. FIG. 16 is an enlarged view showing details of the flow paths of the output shaft and the input shaft. l...Casing, 2...Output shaft, 2
a... Bush (output shaft) 3... Input shaft, 4... Rotor, 5...
...Partition, 6...First hydraulic chamber, 7...
...Second hydraulic chamber, 8...First flow path, 9
...Second flow path, 9a...Edge, 10
...First supply channel (supply channel), 11...
...first return channel, 20...input shaft, 22...first supply channel (supply channel), 27.
...First return flow path, 28...Sub flow path (first return flow path), 29...
...Bay, 32...Second return channel, S...
...Gap, S, ...Gap.

Claims (1)

[Claims] The output shaft is rotatably placed inside the casing, and
An input shaft is rotatably disposed in the center along the axis of the output shaft, and the inside of the casing is divided by a partition provided between the casing and the output shaft and a rotor provided on the output shaft. a first hydraulic chamber and a second hydraulic chamber, and the output shaft includes a first flow path having one end opening into the first hydraulic chamber and one end opening opening into the second hydraulic chamber. A second flow path is provided on the input shaft, and one end thereof is connected to the other end of either the first flow path or the second flow path depending on the relative angular position with respect to the output shaft. A supply flow path that communicates with the other end of the first return flow path is provided, and a first return flow path that communicates with the other end of the other flow path is provided. A communicating second return passage is provided, and the hydraulic oil is selectively supplied to either the first hydraulic chamber or the second hydraulic chamber, and the hydraulic oil is discharged from the other hydraulic chamber. In the rotary actuator, the first return flow path is provided along the axial direction, and the other end opening of the first return flow path or the second a groove extending substantially circumferentially from the opening of the return flow path, and at least a portion of the groove extending from the edge of the return flow path to the tip of the groove is connected to one end of the first return flow path. The gap defined by the groove and the opening of the return flow path facing the groove is larger than the cross-sectional area of the gap defined when the part and the first flow path or the second flow path overlap. A rotary actuator characterized in that it is formed so that its cross-sectional area is smaller.