JPS62288747A - Differential epicyclic train - Google Patents

Abstract

PURPOSE:To obtain an efficient transfer of large torque and to reduce the weight of the captioned device as a whole, by arranging an epicyclic gear bearing in a carrier in such a manner that the bearing extends in the axial direction and further arranging a carrier bearing at a close range to the aforementioned bearaing in both radial and axial directions. CONSTITUTION:Both ends of a shaft 39 of an epicyclic gear 37 are extended in both directions of the face width and are supported by epicyclic gear bearings 40 installed to carriers 41 and 42. As a result, the gear-to-gear distance becomes larger than the face width. Thus, the load acting on the bearings 40 when the couple is applied to the epicyclic gear 37 decreases, thereby reducing the size of the bearings required. In addition, projected, peripheral walls 43 and 45 are provided in a close range from the bearings 40 in both radial and axial directions of the bearings 40, so that the carriers 41 and 42 are supported by carrier bearings 44 and 46. As a result, the load acting on the bearings 40 is supported by the carrier bearings, thereby thinning the thickness of the carriers 41 and 42. With this contrivance, a device, which is light but can withstand a large load, can be obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Object of the Invention] (Industrial Field of Application) The present invention provides a structure in which, for example, the joints vJ of the robot 1 to the arm are suitable for use as a speed reducer constituting the mechanism. This invention relates to a dynamic pulsating gear device.

(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 controlled by the plurality of planetary gears 4 that mesh with both the sun gear 2 and the fixed internal teeth 13. These 'y11 star gears 4 revolve around the sun gear 2 while rotating on their own axis. In addition to the fixed internal gear 3, each planetary gear 4 is meshed with a rotating internal gear RI5 having a slight difference in the number of teeth from the fixed internal gear 3, and the output shaft 6 is driven by the rotating internal gear 5. I'm trying to rotate it. Therefore, as described above, when each planetary gear 4 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 teeth 1 and 3, and 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 such a differential planetary gear device, generally,
As shown in FIG. 2, the planetary gear 4 is connected to the planetary gear shaft 12.
It is supported rotatably by two gear bearings 13. The planetary gear shaft 12 is sandwiched between carriers 7.8, and the carriers 7.8 are rotatably supported by the casing 11 and the output shaft flange portion 16 via carrier bearings 9.10.

However, in the conventional differential planetary gear device configured as described above, the planetary gear 4 is supported by two TI star gear bearings 13 arranged within the tooth width of the planetary gear 4. This caused the following problems.

That is, when torque is transmitted to a load through the meshing of the planetary gear 4 with the fixed internal gear 3 and the rotating internal gear 5, the fixed internal gear 3 and
A load F3 acts on the center position in the face width direction of the rotating internal gear 5, a load F5 acts on the center position in the face width direction of the rotating internal gear 5, and a reaction force F13 acts on the planetary gear bearing 13, respectively. Now, F3. F5. F1
When the distance between the points on which a acts is set to λ0, 21, the following equation holds true.

F1a-(<1) +l) F3-nI F5)/
(λ0 +21) (1) In the ax vJ planetary gear system, the values of F3 and F5 are very large, but the difference between them is small, so the following equation holds approximately.

F13=(1/(Ω0 +21))F3...(2) As can be seen from this equation (2), two planetary gear bearings 1
If the value of the interval (ρ0+2ρ1) of 3 is small, the load on the planetary gear bearing becomes very large. For this reason, a bearing with a large load capacity was required, which was an obstacle to reducing size and weight.

Therefore, in order to eliminate such problems, the tooth widths of the planetary gear 4, fixed internal gear 3, and rotating internal gear 5 are increased, and the diameter of the 'f1 star gear 4 is increased to create a large planetary gear. It is conceivable to use a bearing 13.

However, increasing the tooth widths of the planetary teeth I4, the fixed internal gear 3, and the rotating internal gear 5 increases the axial dimension of the entire differential planetary gear device, and increases the overall weight.

Furthermore, if the module of all the gears is increased in order to increase the diameter of the planetary gear 4, the diameter of the entire planetary gear device will become larger, and the overall weight will also increase.

In addition, in the conventional differential planetary gear device, the load acting on the planetary gear 4 during load is transferred to the planetary gear shaft 12 and the planetary gear bearing 13.
, carrier 7.8 and carrier bearing 9.10, the load transmission path becomes long and deformation during this time cannot be ignored. For this reason, Ti
There was also the problem that the position of the star gear 4 was displaced, making it impossible to maintain good meshing with other gears, and making it impossible to efficiently transmit high torque. In addition, if an attempt is made to reduce the above-mentioned deformation, the thickness of the carrier becomes thicker, which poses a problem of increasing the weight of the entire device.

(Problems to be Solved by the Invention) As described above, in the conventional differential planetary gear device, the load on the planetary gear bearing is large, and for this reason, it is not possible to apply a high load. If an attempt is made to improve this, there is a problem in that the overall size increases and lff1 increases.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a differential planetary gear device that can be operated with high efficiency and high load without increasing the size and weight of the entire device.

[Structure of the Invention] (Means for Solving the Problems) In the differential planetary gear device according to the present invention, a shaft portion extending longer than the tooth width is provided at both axial ends of the planetary gear, and a support body of the planetary gear is provided. A Ti early double gear bearing is provided in a certain carrier, and these bearings rotatably support the planetary gear with a bearing interval longer than the tooth width, and furthermore, the outer surface of the carrier supports the planetary gear bearing at a close distance in the radial and axial directions. A projecting peripheral wall is provided at the position, and this projecting peripheral wall is supported by a carrier bearing.

(Function) When a load is connected to the output shaft, a very large couple acts on the TI star gear that meshes with the fixed internal gear and the rotating internal gear. Since the 'ti star gear bearing is arranged in a carrier located outside the tooth width of the planetary gear, the bearing spacing is long. Therefore, the bearing load applied to the planetary gear bearing to balance the above couple is very small. In general, since the carrier bearing is disposed close to the planetary gear bearing to support the carrier, deformation of the carrier can be reduced and the thickness of the carrier can be made thinner, contributing to weight reduction of the entire device.

(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 a fixed internal gear 24 is formed on the inner surface of this convex portion.

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. 29
．． It is rotatably supported via 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. 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 integrally constitute an arm and a shaft 39 inside a rim 38, and both ends of the shaft 39 protrude on both sides of the tooth width, and a planetary gear bearing 40, which will be described later,
It has a shape that allows it to fit.

On the other hand, annular carriers 41 and 42 are arranged on both sides of the planetary gear 37 in the axial direction, as shown in FIG. Holes are provided in opposing positions of these carriers 41 and 42, and planetary gear bearings 40 made of ball bearings or the like that support both ends of the shaft 39 of the planet teeth 1137 are installed in these holes. Therefore, the three planetary gears 37 are rotatably supported by the planetary gear bearings 40 at long bearing intervals with respect to the carriers 41 and 42. In this case, the mutual positional relationship between the carriers 41 and 42 must be fixed, and in this embodiment, for example, three spacing blocks 47 are inserted between them as shown in FIG. 4 to firmly connect them integrally. I try to do that. As shown in FIG. 4, a projecting peripheral wall 43 is formed on the outer surface of the carrier 41 and extends around the input shaft 25. As shown in FIG. The carrier 41 is rotatably supported on the inner surface of the input casing section 21 via a carrier bearing 44 mounted on the outer peripheral surface of the projecting peripheral wall 43. Furthermore, a projecting peripheral wall 45 that covers the input shaft 25 is also formed on the carrier 42 . The carrier 42 is rotatably supported by the flange portion 32 of the output shaft 26 via a carrier bearing 46 mounted on the outer peripheral surface of the projecting peripheral wall 45. For example, ball bearings are used as these carrier bearings 44 and 46, and the carrier 41.4 supporting the planetary gear 37
2 and the spacing block 47 is supported from both sides thereof.

In the above configuration, when the rotational drive power from the motor (not shown) is transmitted to the input shaft 25, the input shaft 25 and the
The a-tooth 1136 is rotationally driven. Due to this rotation of the sun gear 36, each planetary gear 37 rotates while the sun gear 36
revolves around. When the 'ti star gear 37 moves in this manner, the rotating internal gear 34 rotates in accordance with the difference in the number of teeth between the fixed internal gear 24 and the rotating internal gear 34. This rotating internal gear 3
4 is transmitted to the output shaft 26 via the cylindrical body 33 and the flange portion 32.

By the way, in this device, each @ star gear 37 meshes with two gears, the fixed internal gear 24 and the rotating internal gear 34. Therefore, when a load is applied to the output shaft 26, two large tangential loads in opposite directions are applied to each planetary gear 37 at two meshing portions. Since the distance between the points of application of this load is considered to be the center of the face width of the cylinder gear, the planetary gear 3
A very large couple will act on 7.

However, since the planetary gear 37 is supported at both ends by planetary gear bearings 40 housed in carriers 41 and 42, the distance between the bearings is long. Therefore, the load on the planetary gear bearing 40 is small compared to the above-mentioned large couple, and as a result, it is possible to use a small bearing with a low load capacity.

Moreover, the load applied to the 'gl star gear bearing 40 is supported by the carrier bearings 44.46 via the carriers 41 and 42, but the carrier bearing 44.degree. 4G is arranged and supported by this carrier bearing 44.46, the rigidity can be increased even if the thickness of the carrier 41.42 itself is made thinner.
As a result, the entire 'Htff can be made smaller and lighter.

Note that this invention is not limited to the embodiments described above. For example, the planetary gear 37 may be solid,
The shaft 39 may be hollow, and its shape is not limited. Further, the planetary gear bearing 40 and the carrier bearings 44, 46 are not limited to ball bearings, and may be bearings of other structures such as roller bearings or needle bearings, and the number thereof is not limited. Further, the projecting peripheral wall formed on the carrier 41, 42 may be coupled to the outer ring of the carrier bearing 44, 46, or even if the carrier bearing 44, 46 is supported by the input shaft 25, the effects of the present invention will not be affected. It's not something that can be damaged.

Furthermore, in the above-mentioned embodiment, the differential planetary gear device is applied to the speed reducer, but it can also be applied to speed increase by making the first shaft the output shaft and the second shaft the input shaft. be.

[Effects of the Invention] As described above, according to the present invention, by arranging the planetary gear bearing that supports the rotation of the planetary gear in the carrier, the planetary gear is supported with a bearing interval that is longer than the tooth width of the planetary gear. Therefore, it is possible to reduce the load that would be applied to the planetary gear bearing due to the large couple acting on the planetary gear. Therefore, it is possible to downsize the planetary gear bearing. Furthermore, the load due to the above couple is supported by the carrier bearing via the carrier, but the planet l
l! Since the carrier bearing is placed close to the 1liI bearing in the radial and axial directions, deformation of the carrier can be minimized even if the carrier itself is made thinner, and the planetary gear can always be placed in the correct position even when the load fluctuates. can be kept. Therefore, good meshing between the planetary gear and the two internal gears can be maintained, and high torque can be efficiently transmitted.

Moreover, according to the present invention, the planetary gear bearing can be downsized,
In addition, since the carrier can be made thinner, the weight of the entire device can also be reduced.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a planetary m-wheel device according to an embodiment of the present invention, FIG. 2 is a perspective view showing the main parts of the same device, and FIG. 3 is a vertical cross-sectional view of a conventional cruising gear device. , FIG. 4 is a diagram for explaining the problems of the conventional device. 1.25...Input shaft, 2.36...Sun gear, 3゜24...Fixed internal m wheel, 4,37...Planetary gear, 5゜34...Rotating internal gear, 6, 26...Output shaft, 7, 8
゜41.42...Carrier, 13.40...Ti star gear bearing, 39...Planetary (i!) axle, 9.10.4
4.46...Carrier bearing. Applicant's agent Patent attorney Takehiko Suzue Illustration 1 Illustration 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 that meshes with the fixed internal gear, the rotating internal gear and the sun gear; and a pair of carriers that rotatably support the planetary gear. and a pair of carrier bearings that rotatably support these carriers about the rotation axis of the sun gear, the carrier bearings being integrally provided with the planet gear and having both ends of the planet gear. A shaft portion projecting outward from an axial end portion, a planetary gear bearing that is fitted in the shaft portion and is installed in each of the pair of carriers to rotatably support the planetary gear, and a planetary gear bearing that rotatably supports the planetary gear; Projected peripheral walls protruding from the outer surface of the planetary gear bearing at positions close to the planetary gear bearing in the radial and axial directions so as to cover the first shaft, and a carrier bearing that rotatably supports these projecting peripheral walls. A differential planetary gear device featuring: