JPH0323778B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a harmonic reduction gear that is configured to perform a reduction function by utilizing the difference in the number of teeth between the internal teeth of an internal gear and the external teeth of a flexible gear that meshes with the internal teeth. It's about machines.

This type of harmonic reducer includes a ring-shaped internal gear having internal teeth, and external teeth arranged on the outer periphery with the axis aligned with each other on the inside of the internal gear, and having a different number of teeth than the internal teeth. input to elastically deform the flexible gear into an elliptical cross-sectional shape, mesh the external teeth with the internal teeth at the long axis portion, and sequentially move the meshing position in the circumferential direction. It is equipped with a mechanism.

The conventional input mechanism includes a flexible bearing fitted to the inner periphery of the flexible gear, and an elliptical cam fitted to the inner periphery of the flexible bearing. The bearing and the flexible gear are elastically deformed to cause the outward teeth and the inward teeth to mesh with each other, and by rotating the elliptical cam, the meshing position can be moved in the circumferential direction. Things are common. However, the elliptical cam merely deforms the flexible gear to match its own shape, and has no function of actively reducing the clearance at the meshing portion between the inwardly directed teeth and the outwardly directed teeth to zero. I don't have it. Therefore, it is difficult to bring the inwardly directed teeth and the outwardly directed teeth into close contact with each other without strain, resulting in a disadvantage that the backlash must be relatively large.

Further, as another type of input mechanism, a large number of plungers are arranged radially inside the flexible gear, and each plunger is sequentially pressed against the inner circumferential surface of the flexible gear by hydraulic pressure. There is a system in which the outward teeth of the flexible gear mesh with the internal teeth of the internal gear, and the meshing position can be moved in the circumferential direction (Japanese Patent Publication No. 1973-
(See Publication No. 27935). This device can press the outward facing teeth until they are tightly meshed with the internal facing teeth, so it is possible to minimize or eliminate the crushing, but this requires selectively and sequentially operating a large number of plungers. Therefore, there are problems in that the structure is extremely complicated, making it difficult to reduce the size and weight, and the cost is high.

The present invention has been made with attention to such circumstances, and includes an input mechanism provided on an annular sliding surface provided on the inner circumference of a flexible gear, and an input mechanism rotatably provided on the inside of the flexible gear. a rotor that holds a plunger in a position corresponding to the sliding contact surface so that it can be protruded and retracted; and a rotor that is elastically deformed in a direction in which the plunger is pressed against the sliding contact surface by hydraulic pressure and the flexible gear is meshed with the internal gear. the plunger biasing means, wherein the tip surface of the plunger and the sliding surface are formed into spherical surfaces with the same curvature, and a hydrostatic bearing is provided between the tip surface and the sliding surface. By forming this, it is possible to provide a harmonic speed reducer which has a simple structure and is easy to implement, and which can minimize or eliminate backlash.

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a longitudinal cross-sectional view of a harmonic speed reducer 1 according to the present invention, and FIG. 2 is a cross-sectional view thereof. As shown in these drawings, the present harmonic reducer 1 includes an internal gear 3 having inwardly directed teeth 2 on the inner periphery, and an axis arranged so that the axis coincides with the inside of the internal gear 3. A thin cup-shaped flexible gear 5 having outward teeth 4 having the same pitch as the inward teeth 2 but slightly fewer in number on the outer periphery of the open end, and a thin cup-shaped flexible gear 5 that crosses the open end of the flexible gear 5. The input mechanism 6 is provided with an input mechanism 6 that elastically deforms into an elliptical shape to cause the outward teeth 4 to mesh with the inward teeth 2 at their long axis portions, and sequentially moves the engagement positions a and b in the circumferential direction. It becomes. The internal gear 3 is a ring-shaped rigid body, and is held between a disk-shaped first casing 7 and a cup-shaped second casing 8. The flexible gear 5 is made of a material with good elastic deformation, and the base end of an output shaft 11 supported by the casing 8 via bearings 9 is fixed to the center of its bottom wall. There is. An elastically deformable ring 12 is fitted onto the inner periphery of the open end of the flexible gear 5. The input mechanism 6 also includes an annular sliding surface 13 formed on the inner periphery of the ring 12, a plunger 14 rotatably provided inside the flexible gear 5, and a plunger 14 at a portion corresponding to the sliding surface 13. The rotor 15 holds the plunger 14 in a retractable manner, and the plungers 14 and 1 are moved by hydraulic pressure.
4 to the sliding surface 13 and press the flexible gear 5.
and a plunger biasing means 16 for elastically deforming the plunger in the direction of meshing with the internal gear 3. The rotor 15 has an input shaft 17 that extends through the first casing 7 with its axis aligned with the output shaft 11.
The input shaft 17 is provided integrally with the
One end of the output shaft 1 is connected to the output shaft 1 through a bearing 18.
1 and the other end is supported by a bearing 19.
It is supported by the first casing 7 via. To be more specific, the rotor 15 is connected to the input shaft 17
It is a lever-shaped member provided perpendicularly to the sliding surface 13, and its both ends are close to the sliding surface 13. Cylinders 21, 21 that open toward the sliding surface 13 are formed at both ends of the rotor 15, and the plungers 14, 14 are slidably fitted into the cylinders 21, 21. Incidentally, as shown in an enlarged view in FIG. 3, protrusions 22 and 23 are provided on the edges of both ends of the rotor 15 to prevent the fitting position of the ring 12 from shifting. The distance l between the tip surfaces of the protrusions 22 and 23 and the inner circumferential surface of the flexible gear 5 is equal to the distance l between the inward teeth 2 and the outward teeth 4
It is set at about 1/3 to 1/4 of the tooth height. on the other hand,
The plunger biasing means 16 receives a pressure liquid A supplied from a hydraulic pump (not shown) or the like to the input shaft 17.
The cylinder 2 is connected to the cylinder 2 through a trunk port 24 provided in the rotor 15 and a branch port 25 provided in the rotor 15.
1, 21, and the plungers 14, 14 project outward due to the hydraulic pressure in the cylinders 21, 21, and press the sliding surface 13. . Further, the tip surfaces 14a, 14a of the plungers 14, 14 and the sliding surface 13 are formed into spherical surfaces having the same curvature. Specifically, the tip surfaces 14 of the plungers 14, 14
a, 14a are formed into convex spherical surfaces with a constant radius of curvature, and the sliding surfaces 13 at the meshing positions a, b are formed into concave spherical surfaces with the same radius of curvature as the tip end surface 14a. It is set to do this. Furthermore, a pressure liquid guide path 26 is provided in each of the plungers 14 to guide a portion of the pressure liquid A to the tip surface 14a of the plunger 14, so that static pressure can be maintained between the tip surface 14a and the sliding surface 13. A bearing 27 is formed. Specifically, the pressure fluid guide path 26 is connected to a port 28 formed in the axial center of the plunger 14.
one end of the cylinder 2 through the orifice 29.
1, and its other end communicates with the pressure pocket 27a of the hydrostatic bearing 27. The opening diameter and pressure receiving area of the orifice 29 are set so that the liquid film between the tip surface 14a and the sliding contact surface 13 is not broken.

Next, the operation of this embodiment will be explained.

First, the stem port 24 of the plunger biasing means 16
and a branch port 25 to supply pressure fluid A to the cylinder 2.
1, 21, plungers 14, 14
protrudes outward and presses the sliding surface 13. As a result, the ring 12 and the open end of the flexible gear 5 are elastically deformed into an elliptical cross section, and the flexible gear 5
The external teeth 4 of the internal gear 3 are located at two locations on the circumference.
This results in close meshing with the inward facing teeth 2 of the. Also,
At the same time, a portion of the pressure fluid A in each of the cylinders 21, 21 passes through the pressure fluid guide passages 26, 26 to the hydrostatic bearings 2 provided at the tips of each plunger 14, 14.
7, 27, the plunger 14,
A liquid film is formed between the tip surfaces 14a, 14a of the plungers 14 and the sliding contact surface 13, and the frictional resistance between the plungers 14, 14 and the sliding contact surface 13 becomes extremely small. Note that the peripheral wall 5a of the flexible gear 5
has a cantilevered structure, so when its open end is elastically deformed into an elliptical shape, the angle between the inner circumferential surface of the flexible gear 5 and the axis of the plunger 14 changes its elasticity. It will change depending on the degree of deformation. However, since the tip surface 14a of the plunger 14 and the sliding surface 13 provided on the inner circumference of the flexible gear 5 are formed into spherical surfaces with the same curvature, the peripheral wall 5a of the flexible gear 5 Even when tilting, a stable liquid film is always formed between the tip surface 14a and the sliding surface 13, so that the function of the hydrostatic bearing 27 is not impaired.

With such a device, for example, when the input shaft 17 is driven to rotate the rotor 15 with the internal gear 3 fixed together with the casings 7 and 8, the plungers 14 and 14 move into the sliding contact. Side 1
3, the meshing positions a and b between the inward teeth 2 and the outward teeth 4 move in the circumferential direction. Then, every time the meshing positions a and b rotate once, the flexible gear 5 rotates by the difference in the number of teeth between the inward teeth 2 and the outward teeth 4, and this rotation is caused by the rotation of the output shaft 11. It is taken out of the casing 8 through. In this case, when the output shaft 11 is fixed and the casings 7 and 8 are opened, the casings 7 and 8 will rotate together with the internal gear 3.

It should be noted that the structure of the plunger is of course not limited to that of the embodiment described above, and may be, for example, as shown in FIG. 4. That is, the fourth
The plunger 14' shown in the figure has a distal end member 31 and a proximal end member 32 connected via a ball joint 33, and an orifice 34 provided in the ball joint 33 and a hole bored in the proximal end member 32. The provided port 35 constitutes a pressure fluid guide path 26'.

Furthermore, the tooth profiles of the inward facing teeth and the outward facing teeth are not limited to those shown in the illustrated example, but in short, any tooth profile may be used as long as it does not cause crushing when pressed against each other by hydraulic pressure. good.

Since the present invention has the above configuration, the following effects can be obtained.

First, since the flexible gear is elastically deformed by the plunger which is biased in a certain direction by hydraulic pressure, the outward teeth of the flexible gear can be tightly engaged with the internal teeth of the internal gear. Therefore, the backlash can be minimized or reduced to zero.

Furthermore, by rotating the plunger along an annular sliding surface provided on the inner circumference of the flexible gear, the meshing position of the outward teeth and the inward teeth can be moved in the circumferential direction. Therefore, compared to a system in which a large number of plungers are arranged radially and actuated in sequence, the number of parts is reduced and the structure is much simpler. Therefore, it is easy to reduce the size and weight, and it is possible to reduce costs.

Moreover, since the tip surface of the plunger and the sliding contact surface are formed into spherical surfaces with the same curvature, and a hydrostatic bearing is provided between these surfaces, as described above, regardless of the degree of deformation of the flexible gear, First, it is possible to maintain the frictional resistance between the plunger and the sliding surface at an extremely small value, and smooth operation can be guaranteed. Therefore, it is possible to provide an excellent harmonic reduction gear with low friction loss and high efficiency.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the present invention, in which FIG. 1 is a longitudinal cross-sectional view, FIG. 2 is a cross-sectional view, and FIG. 3 is an enlarged view of essential parts. FIG. 4 is an enlarged view of main parts showing another embodiment of the present invention. 1...Harmonic reducer, 2...Internal gear, 3...Internal gear, 4...External gear, 5...Flexible gear, 6...
Input mechanism, 13...Sliding surface, 14, 14'...Plunger, 14a...Tip surface, 15...Rotor,
16... Plunger biasing means, 26, 26'...
Pressure fluid guideway, 27...static pressure bearing, 29...
Orifice.

Claims (1)

[Claims] 1. A ring-shaped internal gear having inward facing teeth, a flexible gear having outward facing teeth disposed inside the internal gear so that the axes coincide with each other, and the flexible gear being elastically deformed to The harmonic reducer includes an input mechanism that partially meshes outward teeth with the inward teeth and sequentially moves the meshing position in the circumferential direction, the input mechanism being connected to the inner teeth of the flexible gear. an annular sliding surface provided on the periphery; a rotor that is rotatably provided inside the flexible gear and holds a plunger retractably in a portion corresponding to the sliding surface;
plunger biasing means for pressing the plunger against the sliding surface using hydraulic pressure to elastically deform the flexible gear in a direction in which it meshes with the internal gear; A contact surface is formed into a spherical surface having the same curvature, and a pressure fluid guide path is provided to guide a part of the pressure fluid for urging the plunger to the tip surface of the plunger via an orifice. A harmonic reducer characterized by forming a hydrostatic bearing between the sliding surface and the sliding surface.