JPS62200057A - Differential gearing device - Google Patents

Abstract

PURPOSE:To have good meshing of a sun gear with a planet gear by making a carrier in both side borne construction and making sturdy the supporting construction for the planet gear. CONSTITUTION:A planet gear 37 meshes with a sun gear 36, a fixed internally cogged gear 24 and a rotating internally cogged gear 34. Therefore, it receives a load of radial direction component, and the whole of carriers 41, 42 receives radial direction component, wherein a planet gear 37 is both side borne by the carriers 41, 42 and carrier bearings 44, 46 and these carriers 41, 42 are consolidated by a space block with each other, so that radial direction displacement will hardly occur. Accordingly squeaking etc. will not be generated at the time of meshing of the gears to contribute to maintaining good meshing performance.

Description

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

(Prior Art) For example, in a multi-joint arm type robot, actuators for driving the joints are distributed and arranged for each joint, and these actuators are configured with a reducer that decelerates the rotation of the motor. ing. In such a multi-jointed arm robot, the heavy fluid of the actuator placed at the joint on the distal end of the arm acts as a load on the actuator placed on the joint on the proximal end of the arm. The speed reducer used in this type of actuator must not only have a large reduction ratio, but also be small and lightweight, and must also be capable of transmitting high torque.

For this reason, the above-mentioned reducer usually has a second
A differential planetary gear system as shown in the figure is used. That is, when the sun gear 2 rotates with the rotation of the input shaft 1, the rotation of the sun gear 2 is transmitted to the plurality of planetary gears 4 that mesh with both the sun gear 2 and the fixed internal gear 3, which are arranged concentrically. As a result, these planetary gears 4 revolve around the sun gear 2 while rotating on their own axis. On the other hand, in addition to the fixed internal gear 3, each planetary gear 4 is meshed with a rotating internal gear 5 having a slight difference in the number of teeth compared to the fixed internal gear 3. This rotating internal gear 5 is connected to an output shaft 6. Therefore, as described above, while each planetary gear 4 rotates, the sun gear 1
When revolving around i2, the rotating internal gear 5 rotates around the stationary internal gear 3.
It will rotate according to the difference in the number of teeth. As a result, the output shaft 6 rotates at a rotation speed that is reduced compared to the rotation speed of the input shaft 1.

By the way, in the above-mentioned differential planetary gear device, the second
As shown in the figure, the planetary gear 4 is sandwiched and supported by carriers 7.8 so as to be rotatable.

One end of the carrier 7 is connected to a carrier bearing 9°10 so that the iris gear 4 can revolve around the sun gear 2.
It is rotatably supported by the casing 11 via.

However, as is clear from this structure, since the planetary gear 4 was conventionally supported in a so-called cantilever manner, the following problem occurred. 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 Fs in the radial direction relative to the load F is generated as shown in an enlarged view in FIG.
is generated, and this component force Fs is small at the sun gear 2 portion and extremely large at the meshing portion of the mountain gears 3 and 5. Moreover, the component force F1 of each M genus bacteria 114. F2.

F3 is not necessarily equal due to play in the bearings of each gear. Therefore, when these component forces are combined, the entire carrier receives a difference in radial component forces of ΔF. The difference between these radial component forces acts on the carrier. Since the carrier has a cantilever support structure as described above, it is deformed by this force, the center position of the planetary gear 4 moves in the radial direction, and normal meshing is no longer performed, reducing the meshing efficiency of the gears, that is, this difference. The power transmission efficiency of the dynamic planetary gear system will be reduced.

In order to solve this problem, it is necessary not only to increase the bending rigidity of the carrier 7゜8 itself, but also to use bearings 9 and 10 with a large allowable cargo capacity, and also to increase the dimension between the bearings 9 and 10. It is desirable to increase the support rigidity of the planetary gear 4 by setting this.

However, in order to increase the rigidity of the carrier 7.8, it is necessary to increase the thickness of these walls, which not only increases the weight of the carrier 7.8 itself, but also increases the weight of the large bearings 9, 10. Its use also increases the weight of the entire differential planetary gear set. Moreover, the bearing 9 mentioned above,
If the dimension between 10 and 10 is increased, the axial dimension of the differential planetary gear device itself will also become large.

(Problems to be Solved by the Invention) As described above, in the conventional differential planetary gear device, the differential 'tl
The power transmission efficiency of the star gear system was poor, and any attempt to improve this would result in an increase in overall size.

The present invention was made based on the above circumstances, and an object of the present invention is to provide a differential planetary gear device that can improve power transmission efficiency without increasing the size of the entire device.

[Structure of the Invention] (Means for Solving the Problems) The present invention is such that a carrier, which is a support for a planetary gear, is rotatably supported on both sides of the rotation axis with the planetary gear sandwiched therebetween. It is characterized by having the planetary gear supported on both sides instead of on one side.

(Function) While the planetary gear meshes with the sun gear, fixed internal gear, and rotating internal gear, it is thick! When the planetary gear revolves around 1fiIII, a component force acts on the planetary gear at the meshing part between the sun gear and the planetary gear and the meshing part between the two internal gears and the planetary gear. Since this component force is usually not constant in the radial direction, a radial force acts on the carrier. At this time, carrier bearings arranged on both sides of the carrier in the axial direction act to prevent deformation of the carrier.

(Example) An embodiment of the present invention will be described below with reference to FIG.

In the figure, 11L is a casing, and the input side casing part 2
1. Intermediate casing part 22 and output side casing part 23
are integrally connected in series in the axial direction. The intermediate casing portion 22 has a convex portion extending in the circumferential direction on a part of its inner circumferential surface, and a fixed internal gear 23 is formed on the inner surface of this convex portion.

Inside the casing part is the input side casing part 2.
An input shaft 25 as a first shaft is inserted from the first side, and an output shaft 26 as a second shaft is inserted from the output side casing 23 side. They are arranged concentrically, and one end side of each other is rotatably connected via a ball bearing 27 inside 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 the output side casing part 21.
A ball bearing 2 is mounted on the inner peripheral surface of a projecting peripheral wall 28 extending toward the output side of the
It is rotatably supported via 9.30.

At the end of the output shaft 26 located inside the casing L, a disk-shaped seven flange portion 32 is integrally formed. A cylindrical body 33 that extends along the inner peripheral surface of the casing 20 in the axial direction to near the end face of the fixed internal gear 24 is integrally connected to the outer peripheral edge of the flange portion 32. A rotating internal gear 34 is formed on the inner circumferential surface of the body 33 on the distal end side.

This rotary internal gear 34 has substantially the same diameter as the fixed internal gear 24 described above and is coaxially arranged, but the number of teeth thereof is slightly different from the number of teeth of the fixed internal gear 24.

The peripheral surface 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. The sun gear 3
6. For example, three planetary gears 37 meshing with the fixed internal gear 24 and the rotating internal gear 34 are arranged at equal intervals in the circumferential direction. These planetary gears 37 are rotatably supported by three support shafts via ball bearings 38. The three support shafts 39 are firmly fixed by annular carriers 41 and 42 arranged on both sides in the axial direction so that their mutual positional relationship is fixed. In this case, carrier 41.
The mutual positional relationship between the 42 and 42 also needs to be fixed, and in this embodiment, for example, three spaced blocks P are inserted between the two, as shown in FIG. 3, so as to firmly and integrally connect them. The carrier 41 includes a projecting peripheral wall 43 that covers the input shaft 25.
is formed, and is rotatably supported on the inner surface of the input side casing part 21 via a carrier bearing 44 mounted on the outer peripheral surface of the projecting peripheral wall 43. Also, carrier 42
Also, a projecting peripheral wall 45 is formed to cover the input shaft 25,
A carrier bearing 46 mounted on the outer peripheral surface of this projecting peripheral wall 45
The output shaft 26 is rotatably supported by the flange portion 32 of the output shaft 26 mentioned above. These carrier bearings 44, 46 are, for example, ball bearings, and constitute a structure in which the combined body of the carriers 41, 42 is supported from both sides of the planetary gear 37.

In the above configuration, when a rotational driving force 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 26, each planetary gear 37 revolves around the sun tooth 1 [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 this rotating internal gear 34 is transmitted to the output shaft 2 through the cylindrical body 33 and the flange portion 32.
6 and becomes the rotational driving force of the output shaft 26.

By the way, in this device, one planetary gear 36 meshes with a total of three gears: the sun gear 36, the fixed internal gear 24, and the rotating internal gear m234. 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 entire carrier 41, 42 receives a radial component force, but the free WmP
J37 is carrier 41.42. Since the carriers 41 and 42 are firmly connected to each other by the spacing block P, they are not easily displaced in the radial direction. Therefore, unnecessary creaks and the like do not occur when the respective gears mesh, and high torque can be efficiently transmitted from the input shaft 25 to the output shaft 26.

Moreover, according to this device, since there is no need to particularly increase the rigidity of the carrier itself, the wall thickness can be reduced, and as a result, the weight of the entire device can be reduced.

Note that the present invention is not limited to the embodiments described above. For example, the carrier bearings 44 and 46 are not limited to ball bearings, but may also be roller bearings, needle bearings, or other types of bearings, and the number thereof is not limited.

Furthermore, the carriers 41 and 42 may be supported by the input shaft 25, and even if the carrier bearing coupling portion of each carrier 41, 42 is disposed outside of the portion that supports it, the effects of the present invention are not lost in any way. You won't be hit.

Furthermore, in the above-mentioned embodiment, an example was described in which the differential planetary gear device was applied to the reduction gear, but the first shaft is the output shaft,
It is also possible to apply it to a speed increaser by using the second shaft as an input shaft.

[Advantageous Effects of the Invention 1] As described above, according to the present invention, since the carrier has a dual support structure, the support structure for the planetary gear becomes strong. Therefore, good meshing between the sun gear and the planet gear can be maintained, and high torque can be efficiently transmitted. Moreover, according to the present invention, it is not necessary to make the rigidity of the carrier itself so high, which contributes to the weight reduction of the entire device.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a planetary gear device according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a conventional planetary gear device, and FIG. 3 is a diagram for explaining problems with the conventional device. be. 1.25...Input shaft, 2.36...Sun gear, 3゜24...Fixed internal gear, 4,37...Planetary gear, 5゜34...Rotating internal gear, 6,26 ...Output shaft, 7, 8
゜41.42...Carrier, 44.46...Carrier bearing. Applicant's agent Patent attorney Takehiko Suzue JAl Figure

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 that meshes with the fixed internal gear, the rotating internal gear, and the sun gear, and sandwiching the planetary gear from both sides in the rotational axis direction; A carrier that supports this so that it can rotate,
In the differential planetary gear device comprising a carrier bearing that rotatably supports the carrier around the rotational axis of the sun gear, the carrier bearing is disposed at least on both sides of the planetary gear in the rotational axis direction. A differential planetary gear device featuring: