JPS6388346A - Differential epicyclic gearing - Google Patents

Abstract

PURPOSE:To strengthen the supporting structure of an epicyclic gearing by rotatably supporting both the ends of an epicyclic gear shaft on the peripheral planes of circularily projected walls formed on a stationary part and a shaft opposite to said part respectively. CONSTITUTION:Driving torque transmitted by an input shaft 25 rotates a sun gear 36 to cause each of epicyclic gears to rotate autorotationally and orgitally and thereby rotate an output shaft 26 through a cylindrical body 33 and a flange part 32 according to a difference in the number of teeth of a stationary and a rotary inner gear 24, 34. Said eicyclic gear 37 engages with three gears, namely the sun gear 36, the stationary and the rotary inner gear 24, 34, and is therefore subjected to strong radial component force, but since its epicyclic gear shaft 39 is rotatably supported on both the circularly projected wall 43 of a casing 21 on an input side and the circularly projected wall 46 of the flange 32 of the output shaft 26, said gear shaft 39 can accurately make autorotational and orbital rotation without its radial displacement. Thus high torque can be effectively transmitted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a differential 171 planetary gear device suitable as a speed reducer constituting a joint drive mechanism of a robot arm, for example.

(Prior Art) For example, a multi-joint arm type robot usually employs a configuration in which actuators for driving the joints are distributed at each joint. Each actuator is provided with a speed reducer that reduces the rotation of the motor. In such a multi-joint arm robot, the weight of the actuator placed at the distal end of the arm is applied as a load to the actuator placed at the proximal end. Therefore, the reducer used in this type of actuator must not only have a large reduction ratio, but also be small and lightweight, and must also have high torque and high transmission performance. Ru.

For this reason, the above-mentioned reducer is usually
A differential planetary gear system as shown in FIG. 3 is used. That is, this differential planetary gear device rotates the input shaft 1 to rotate the sun gear 2, and the rotation of the sun gear 2 is equally distributed so as to mesh with both the sun gear 2 and the fixed internal gear 3. The transmission is transmitted to three planetary gears 4, and these planetary teeth 1!
4 revolves around the sun gear 2 while rotating. In addition to the fixed internal gear 3, each planetary gear 4 is connected to a rotating internal gear 5 having a slight difference in the number of teeth with respect to the m number of the fixed internal gear 3.
The rotating internal gear 5 is used to rotate the output shaft 6. Therefore, as described above, each planetary gear 4
When it revolves around the sun gear 2 while rotating, the rotating internal gear 5 rotates according to the difference in the number of teeth with the fixed internal gear 3, and as a result, the output shaft 6 is decelerated relative to the rotation speed of the input shaft 1. It rotates at the specified rotation speed.

By the way, in such a differential planetary gear device, generally,
As shown in FIG. 3, a planetary gear shaft 14 is provided so as to pass through a planetary gear bearing 13 mounted in the planetary gear 4, and both ends of this planetary gear shaft 14 are supported by carriers 7.8.
Furthermore, the carrier 7 is rotatably supported by the casing 11 via carrier bearings 9 and 10, thereby enabling the planetary gear 4 to revolve. That is, carrier 7.8
supports the planetary gear 4 rotatably through the planetary gear shaft 14, and rotates around the sun gear 2 at the same revolution period as the planetary gear 4. As shown in FIG. 4, the carriers 7.8 are firmly connected by a fixture (not shown) using three blocks 15 as spacers. These carriers 7.8, blocks 15, and fixtures are designed with rigidity in order to always maintain the correct axial position of the planetary gears 4 even when the planetary gears 4 are subjected to high torque loads, and to perform highly efficient power transmission. It has been designed to a high standard, and is also processed and assembled with high precision.

However, in the conventional differential planetary gear device configured as described above, the planetary gear 4 is supported by the carrier 7.8, which causes the following problem.

That is, in order to increase the rigidity of the carrier 7.8, it is necessary to increase the wall thickness, and this causes a problem of increasing the axial dimension of the entire reduction gear and increasing lff1. Furthermore, since the carriers 7 and 8 must have a highly rigid and highly precise structure, the structure becomes complicated and requires a long time to process and assemble, resulting in an increase in the overall price.

Therefore, to solve such problems, carrier 7.
8, block 15, bearings 9, 10, and the above-mentioned fixtures are preferably removed.

However, if these are removed, the following new problems arise. That is, at the meshing portions between the planetary gear 4, the sun gear 2, the fixed internal gear 3, and the rotating internal gear 5, a component force 1'' in the radial direction against the load ff1Fn is applied as shown in an enlarged view in FIG.
r is generated, and this component force Fr is small at the sun gear 2 portion and extremely large at the meshing portion of the mountain gear 3.5. Due to this difference in component forces, the planetary gear 4 has the sun gear 2
A large force F1. F2 and Fl act. In the conventional device, this force is supported by the carrier 7.8, but if the carrier 7.8 etc. are removed as mentioned above, there is nothing to support Fr, F2, Fl, so this force is supported by the carrier 7.8. A force will act on the sun gear 2. In this case, an abnormal load is applied to the meshing portion between the planetary gear 4 and the sun gear 2 due to Fl, F2, and Fl.
As a result, the meshing efficiency of the gears, that is, the power transmission efficiency of the differential Ti star gear device is significantly reduced.

(Problems to be Solved by the Invention) As described above, in the conventional differential Tl star gear IA system, the provision of a carrier increases the overall size and weight, and furthermore, the structure is complicated and the overall The problem was that it led to higher prices. Furthermore, when attempting to remove the carrier, there was a problem in that the power transmission efficiency was significantly reduced.

Therefore, the present invention aims to provide a differential M star gear device that can obtain good power transmission efficiency without increasing the size and weight of the entire device, complicating the configuration, or increasing the price. There is.

[Structure of the Invention] (1,000 points for solving the problems) In the differential planetary gear device according to the present invention, the carrier that is the support of the planetary gear is removed, and a projecting peripheral wall is provided on the casing and the output shaft instead. Both ends of the planetary gear shaft are movably supported by the outer peripheral surface of the projecting peripheral wall.

(Function) When the M star gear revolves around the sun gear while meshing with the sun gear, fixed internal gear, and rotating internal gear, the sun gear and Y
A force component acts on the planetary gear at the meshing portion with the Ii star gear and the meshing portion between the two internal gears and the planetary gear. This component force is usually not constant in the radial direction, so the planet l! A force acts on the Fl car in the radial direction. At this time, the planetary gear is supported at both ends so as to be able to revolve by the projecting peripheral walls arranged at both ends in the axial direction of the planetary gear. Therefore, good meshing is obtained between the planetary gear and the sun gear, and a decrease in the efficiency of power transmission of the entire device is prevented.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a differential planetary gear device according to an embodiment of the present invention.

That is, 20 in the figure is a casing, and this casing 20 includes an input side casing part 21 and an intermediate casing part 2.
2 and the output side casing part 23 are integrally coupled in the axial direction. A convex portion projecting inward is formed in a circumferential direction on a part of the inner surface of the intermediate casing portion 22, and fixed internal teeth are provided on the inner surface of this convex portion! [24 is formed.

Inside the casing 20, an input shaft 25 as a first shaft is inserted from the input side casing part 21 side, and an output shaft 26 as a second shaft is inserted from the output side casing part 23 side. 25 and 26 are arranged coaxially with each other and concentrically with the fixed internal gear 24, and one end side of each other is rotatably connected via a ball bearing 27 within the casing 20. The input shaft 25 is rotatably supported by the input side casing part 21 via a ball bearing (not shown), and the output shaft 26 is supported by a ball bearing on the inner peripheral surface of a projecting peripheral wall 28 provided in the output side casing part 23. Bearing 2
It is rotatably supported via 9.30.

A disk-shaped flange portion 32 is integrally formed at the end of the output shaft 26 located inside the casing 20 . A cylindrical body 3 extending along the inner peripheral surface of the casing 20 to near the end surface of the fixed internal gear 24 is provided at the outer peripheral edge of the flange portion 32.
3 are integrally connected to each other, and a rotating internal gear 34 is formed on the inner circumferential surface of the distal end portion of this cylindrical body 33. The rotating internal gear 34 has approximately the same diameter and is arranged coaxially with the stationary internal gear 24 described above, but the number of teeth thereof is slightly different from the number of teeth of the stationary internal gear 24.

A portion of the input shaft 25 facing the intermediate casing portion 22 is formed to have a large diameter, and a sun gear 36 is formed in this large diameter portion. On the outer periphery of the sun gear 36, for example, three :iUl gears 37, which mesh with the thick PA gear 36, the fixed internal gear 24, and the rotating internal teeth FJ34, are arranged at equal intervals in the circumferential direction. These TI star gears 37 are rotatably supported by a planetary gear shaft 39 via ball bearings 38. Both ends of the three planetary gear shafts 39 protrude on both sides of the planetary gear 37.

On the other hand, a projecting peripheral wall 43 is formed in a disc-shaped portion of the input side casing section 21 that faces the end surface of the planetary gear 37 so as to cover the input shaft 25, and the planetary gear shaft is formed on the outer peripheral surface of the projecting peripheral wall 43. One end side of 39 is supported so as to be transferable. Furthermore, the planetary gear 3 of the flange portion 32 integrated with the output shaft 26
A circumferential wall 46 that is coaxial with the circumferential wall 43 and has an outer circumferential surface having the same outer diameter is also provided on the disc-shaped portion facing the end surface of the protruding circumferential wall 43 . The other end is supported in a transferable manner.

In the above configuration, when rotational drive power from a motor (not shown) is transmitted to the input shaft 25, the sun gear 36 is rotationally driven together with the input shaft 25. Due to this rotation of the sun gear 36, each planet gear 37 revolves around the sun gear 36 while rotating. When the planetary gear 37 moves in this way,
The rotating internal gear 34 rotates according to the difference in the number of teeth between the fixed internal gear 24 and the rotating internal gear 34. The rotational force of the rotating internal gear 34 is transmitted to the output shaft 26 via the cylindrical body 336 and the flange portion 32.

By the way, in this device, the planetary gear 37 making one revolution meshes with the three # wheels of the sun gear 36, the fixed internal gear 24, and the rotating internal gear 34. Therefore, when a load is applied to the output shaft 26, each of the three meshing portions receives loads of different radial component forces. As a result, the planetary gears 37 are subjected to a large radial component force, but these planetary gears 37 are supported by the planetary (@ axle 39), and the planetary gear shaft 39 is movably supported by the projecting peripheral wall 43, 46. Therefore, high-precision rotation and revolution are possible without displacement in the radial direction.Therefore, unnecessary squeaks etc. do not occur when each gear meshes, and the input?j125
High torque is efficiently transmitted from the output shaft 26 to the output shaft 26. Moreover, this 8! Since there is no equivalent to the carrier in the conventional device, the entire device can be made smaller, the configuration simpler, and the cost lower.

Note that the present invention is not limited to the embodiments described above. For example, planetary AM bearings are not limited to ball bearings,
Bearings with similar structures such as roller bearings and needle bearings may be used, and the number thereof is not limited. Further, in the above-described embodiment, the protruding periphery W43.46 is formed integrally with the input side casing part 21 and the seventh flange part 32, but it may be made as a separate part and fixed with screws or the like. In addition, in the above-described actual example, both ends of the planetary gear shaft 39 are directly supported by the projecting peripheral walls 43, 46, but as shown in FIG. 2, only one side is supported through a bearing 51. You can do it like this. Further, in the above-described embodiment, the differential idling gear device is applied to a speed reducer, but it can also be applied to a speed increaser by using the first shaft as the output shaft and the second shaft as the input shaft.

[Effects of the Invention] As described above, according to the present invention, both ends of the planetary gear shaft are movably supported by the fixed portion and the outer peripheral surface of the projecting peripheral wall provided on one shaft, so that the M The support structure of the star gear can be made stronger. therefore,
Good meshing between the sun gear and the planetary gears can be maintained, and high torque can be efficiently transmitted. Furthermore, since there is no carrier equivalent to the conventional device, it is possible to contribute to making the entire device smaller and lighter, simplifying the configuration, and lowering the cost.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a planetary gear device according to an embodiment of the present invention, and FIG. Fig. 3 is a vertical cross-sectional view of a conventional TI star gear device, Fig. 4 is a diagram schematically showing the meshing portion of the planetary gear, sun gear, and fixed internal gear of the same device, and Fig. 5 is a diagram showing the meshing part of the planetary gear, sun gear, and fixed internal gear of the same device. It is an enlarged view showing part A. 1.25...Input shaft, 2.36...Sun gear, 3.
24... Fixed internal gear, 4, 37... Idle gear, 5.
34... Rotating internal gear, 6, 26... Output shaft, 7.8
...Carrier, 13.38...T1 star gear bearing, 1
4.39... Planetary gear shaft, 43.46... Projection wall,
51...Bearing. 1 to 1 Figure 2

Claims (1)

[Claims] a first shaft rotatably provided with respect to the fixed part;
a sun gear mounted on a shaft; a fixed internal gear disposed outside the sun gear concentrically with respect to the sun gear and fixed to the fixed part; a rotating internal gear that is rotatably arranged with respect to the fixed part and has a slight difference in the number of teeth from the fixed internal gear;
a second shaft coaxially connected to the rotating internal gear; at least one planetary gear meshing with the stationary internal gear, the rotating internal gear and the sun gear; and a planetary gear bearing mounted within the planetary gear; , a differential planetary gear device comprising a planetary gear shaft that passes through the planetary gear bearing and rotatably supports the planetary gear; a projection that rotatably supports both ends of the planetary gear shaft on an outer peripheral surface; The peripheral wall is connected to the fixed part and the second part.
A differential planetary gear device characterized by being installed on the shaft.