JPH0450464B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to a hydraulic power drive device that can be suitably used for turning or rotating parts that require precise position control in industrial robots, machine tools, etc. It is.

(B) Prior Art Conventionally, as such a power device, there is one in which a hydraulic motor and a harmonic reduction gear are connected in series, and the arm of a robot can be operated by the power taken out from the output shaft of the harmonic reduction gear. However, such a motor and speed reducer having a special structure is bulky, and it is difficult to shorten the dimension particularly in the axial direction, and there is a certain limit to the reduction in weight.

Therefore, recently, a system in which a hydraulic motor a is housed inside a harmonic reduction gear b as shown in FIG. 1 has been considered. That is, the harmonic reducer b has a cup-shaped flexspline e that can be flexibly deformed inside a circular spline d fixed to a housing c, and the flexspline e is deformed by a wave generator f. The spline d can be meshed with the circular spline d. A spindle g of the hydraulic motor a is fixed to the center of the end wall of the housing c, and a casing h of the motor a, which rotates around the spindle g, is disposed within the flexspline e. The wave generator f is integrally formed with h.

However, in this case, the output shaft i is attached to the end face of the flexspline e which can be flexibly deformed, and the power is extracted from the output shaft i.
It is essential to provide a bearing j for supporting the output shaft i at the end of the housing c. Therefore, the effect of shortening the dimension in the axial direction could not be said to be sufficient.

(C) Purpose The present invention was developed in response to these circumstances.It is possible to significantly shorten the axial dimension, and it can be easily applied to narrow parts such as the arm joint part of a robot. The present invention provides a driving device that can be installed.

(d) Structure In order to achieve the above object, the present invention not only accommodates the casing of the hydraulic motor inside the flexspline of the harmonic reducer, but also connects the flexspline of the harmonic reducer to the spindle of the motor. It is characterized in that it is fixed to a cup-shaped housing that holds the housing, and rotational power can be taken out from a circular spline rotatably supported on the inner periphery of the housing.

(E) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 2 to 4.

As shown in FIGS. 2 and 3, the power unit according to the present invention outputs the power of a hydraulic motor 1 via a harmonic reduction gear 2. As shown in FIGS.

The hydraulic motor 1 has a support shaft 3 having an eccentric portion 3a.
and a casing 4 that is rotatable around the axis O1 of the support shaft 3. The casing 4 includes a cup-shaped main body 4a that surrounds the eccentric portion 3a of the support shaft 3, and a lid 4 that closes the opening of the main body 4a.
One end of the support shaft 3 is fitted through the lid 4b and protrudes outside the casing 4. Further, an odd number of flat portions 4c are formed on the inner periphery of the casing 4 at equiangular intervals in the circumferential direction. Pistons 5 are provided inside the casing 4 at portions corresponding to the respective plane portions 4c.
are arranged, and the distal end surface of each piston 5 is attached to the corresponding flat portion 4c via a hydrostatic bearing 6. The hydrostatic bearing 6 is connected to the piston 5
The distal end surface is formed into a planar shape so as to be in close contact with the flat portion 4C, and a pressure pocket 7 is formed on this distal end surface, and fluid pressure is introduced into the pressure pocket 7. A cylinder block 8 is rotatably fitted to the eccentric portion 3a of the support shaft 3, and the cylinder block 8 increases or decreases the volume of the base end surface of each piston 5 as the casing 4 rotates. It forms a space 9. Specifically, a plurality of cylinders 11 are formed radially in the cylinder block 8 at equal angular intervals in the circumferential direction. Each piston 5 is slidably fitted into each cylinder 11, and the space 9 is formed by the base end surface of each piston 5 and the inner surface of each cylinder 11. A pin 12 is provided protruding from the end surface of the cylinder block 8, and by loosely fitting the tip end surface of the pin 12 into a hole 13 provided in the casing 4, the cylinder block 8 is attached to the casing 4. It is designed so that it does not rotate beyond a certain rotation angle. That is, this cylinder block 8 is adapted to rotate following the casing 4. Further, the interior of the casing 4 is divided into a first area and a second area B with an imaginary dividing line P passing through the axis O2 of the support shaft 3 as a boundary.
The space 9 is divided and is passing through the first area A.
is communicated with the first fluid circulation path 14, and the space 9 passing through the second region B is communicated with the second fluid circulation path 15. First fluid flow path 1
Reference numeral 4 is for communicating the pressure pocket 16 on the first region A side provided on the outer circumferential surface of the eccentric portion 3a with a first inlet/outlet (not shown) provided at the tip of the support shaft 3. and is formed on the support shaft 3. Further, the second fluid circulation path 15 connects a pressure pocket 17 on the second area B side provided on the outer peripheral surface of the eccentric portion to a second inlet/outlet (not shown) provided on the distal end surface of the support shaft 3. It is for communication and is formed within the support shaft 3. Furthermore, a pressure introduction path 18 is provided at the axial center of each piston 5 for introducing the fluid pressure in the corresponding space 9 into the pressure pocket 7 in the corresponding hydrostatic bearing 6.

On the other hand, the harmonic reducer 2 includes a ring-shaped circular spline 22 having inward teeth 21 on the inner periphery, and a ring-shaped circular spline 22 which is disposed inside the circular spline 22 so that its axes coincide with each other, and has an inwardly directed A thin cup-shaped flexspline 24 having outward facing teeth 23 having the same pitch as the teeth 21 and a slightly smaller number; It is provided with a wave generator 25 which causes the outward teeth 23 to mesh with the inward teeth 21 and sequentially moves the engagement positions a and b in the circumferential direction. The circular spline 22 is a ring-shaped rigid body that is held between an output disk 26 and a presser cylinder 27, and is rotatably supported on the inner periphery of a cup-shaped housing 28 via a bearing 29. The flexspline 24 is a cup-shaped member made of a material with good elastic deformation, and its end wall 24a is fixed to the end wall 28a of the housing 28. In addition, the wave generator 25
The elliptical cam 29 rotatable around the axis of the flexspline 24 is fitted onto the inner periphery of the flexspline 24 via a flexible ball bearing 30, and the outer ring 30a of the ball bearing 30 is It is designed to be elastically deformable together with the flex spline 24.

Then, the support shaft 3 of the hydraulic motor 1 is fixed to the axial center of the end wall 28a of the housing 28, and the casing 4 of the pump 1 is disposed within the flexspline 24, and the wave is attached to the casing 4. A generator 25 is integrally provided. That is, the elliptical cam 29 is integrally formed on the outer periphery of the main body portion 4a of the casing 4.

Furthermore, the casing 4 of the hydraulic motor 1 is disposed within the flexspline 24, and the casing 4 of the hydraulic motor 1 is disposed within the housing 28.
An electromagnetic brake 32 is provided for applying braking to stop the vehicle. Electromagnetic brake 32
A brake shoe 33 is fixed to the end surface of the casing 4, and a magnetic armature 35 is rotatably held in the housing 28 via a plurality of guide pins 34 so as to be movable back and forth in the axial direction.
and a lining 36 attached to the surface of the armature 35 facing the brake shoe 33.
and a plurality of braking springs 37 that press the lining 36 against the brake shoe 33 and apply braking to the casing 4 by urging the armature 35 in the direction of the casing 4, and are supported by the wafer ring 28. Braking release excitation that is disposed on the back side of the armature 35 and attracts the armature 35 in a direction away from the casing 4 against the biasing force of the spring 37 when energized, thereby separating the lining 35 from the brake shoe 33. It is equipped with a coil 38. In addition, 39 is an electromagnetic rotation detector,
This detector 39 detects the rotational position and rotational speed of the casing 4 with respect to the support shaft 3.

Next, the operation of this prime mover will be explained. First, a high-pressure fluid is introduced into the first fluid distribution system path 1, for example.
4 into the spaces 9, 9 existing in the first area A, high fluid pressure is introduced into the hydrostatic bearings 6, 6 existing in the first area A, and these fluid pressures cause the hydraulic pressure to increase. Forces Fa and Fb acting on the casing 4 of the motor 1 pass through the axis O2 of the eccentric portion 3a and are perpendicular to the plane portion 4c of the casing 4. Therefore, the resultant force Fab of these forces Fa and Fb
The line of action passes through the axis O2 and is deviated by a certain distance L from the axis O1 of the support shaft 3, which is the center of rotation of the casing 4 (see FIG. 4). As a result, a moment |Fab|×L acts on the casing 4, thereby causing the casing 4 to rotate in the direction of arrow X. in this case,
The spaces 9, 9 existing in the first region A gradually increase in volume as the casing 4 rotates, and
The volumes of the spaces 9, 9 existing in the region B gradually decrease, so that the high-pressure fluid flows through the first fluid flow path 14.
The fluid that has completed its work flows sequentially into the spaces 9, 9 passing through the first region A through the second region B, and then flows out through the second fluid flow path 15. is discharged to. In this way, when the casing 4 of the hydraulic motor 1 rotates, for example, in the direction of the arrow X, the elliptical cam 29 of the wave generator 30 also rotates in the direction of the arrow and,
The meshing positions a and b of the circular spline 22 with the inward teeth 21 move in the direction of the arrow X. Then, each time the elliptical cam 29 rotates once, the circular spline 22 rotates in the direction of arrow Y by the difference in the number of teeth between the inward teeth 21 and the outward teeth 23, and this rotation causes the output disk 26 to rotate. It is taken out of the housing 28 through. However, if such a system exists, the first and second fluid flow paths 1
By controlling the direction and flow rate of the pressure fluid supplied to the rotary disks 4 and 15, a desired rotational force can be extracted from the rotating disk 26.

Note that the hydraulic motor is not limited to the illustrated embodiment, and can be modified in various ways without departing from the spirit of the present invention.

(F) Effects Since the present invention has the above configuration, the following effects can be obtained.

First, the casing of the hydraulic motor is placed inside the flex spline of the harmonic reducer, and the wave generator is integrally formed in the casing of the motor, so the hydraulic motor and harmonic reducer can be separated. It is possible to reduce the number of parts and use space more effectively than in the case of a configuration, and it is possible to meet the demands for miniaturization and weight reduction.

Moreover, since the flexspline is fixed to the housing and the rotational power is extracted from the ring-shaped circular spline rotatably supported on the inner circumference of the housing, the output shaft is attached to the flexspline which can be flexibly deformed. There is no need for a bearing like in the case where the bearing is mounted. Therefore, in combination with the fact that the hydraulic motor is disposed within the harmonic reduction gear, the axial dimension of the entire device can be significantly shortened. Therefore, it is possible to provide an excellent driving device that can be easily placed in various narrow areas such as the arm joint of a robot.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a conventional example, FIG. 2 is a sectional view showing an embodiment of the present invention, FIG. 3 is a schematic enlarged sectional view taken along the - line in FIG.
The figure is an explanatory diagram of the operation of the same embodiment. DESCRIPTION OF SYMBOLS 1... Hydraulic motor, 2... Harmonic reduction gear, 3... Support shaft, 4... Casing, 22... Circular spline, 24... Flex spline, 25... Wave generator, 28... Housing.

Claims (1)

[Claims] 1 A cup-shaped housing, and a ring-shaped circular spline rotatably supported on the inner periphery of the housing, which is disposed inside the circular spline and is biased by a wave generator to mesh with the circular spline. a harmonic reducer comprising a cup-shaped flexspline fixed to the housing; a casing having one end of a support shaft fixed to the housing and rotating around the support shaft disposed inside the flexspline; and a hydraulic motor provided with the wave generator,
A driving device characterized in that it is configured such that rotational output can be taken out from the circular spline.