JPH08303531A - Micro speed reduction device - Google Patents

Abstract

PURPOSE: To reduce friction loss by fixing a material of low friction coefficient and preventing the generation of foreign substance such as powder caused from abrasion. CONSTITUTION: A micro speed reduction device is provided with an sun-external gear 1, a pulurality of planetary gears 2 engaging with the sun-external gear 1, a fixed sun-internal gear 3, a cylindrical casing 4 inwardly fixing the fixed sun-internal gear 3, end plates 41 and 42 which close both ends of the casing 4, a movable sun-internal gear 5 disposed in the casing 4 so that its external surface may slide with the inner surface of the casing 4 and engaging with the planetary gear 2, and an output gear 6 engaging with the movable sun- internal gear 5 and fixed to an output shaft 7. Sliding elements 9 of a high molecular material with low friction coefficient is further provided between the mutual end surfaces of every gears so that the surfaces are perpendicular to the axes of the gears as well as between the movable sun-internal gear 5 and the casing 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed reducer for an actuator used in small precision instruments, micromachines and the like.

[0002]

2. Description of the Related Art Conventionally, a so-called micro speed reducer used for small precision instruments and micromachines has a diameter of 1
Since it is extremely small, about 5 mm, a planetary gear mechanism is used, and is configured as shown in FIG. 6, for example. That is, 1 is a sun outer gear fixed to the input shaft 11, 2 is a plurality of planetary gears meshing with the sun outer gear 1, and 3 is each planetary gear 2
It is fixed to the inside of the cylindrical casing 4 by a fixed sun gear that meshes with the. Reference numeral 5 denotes a movable inner sun gear that meshes with the planetary gear 2 and that has an outer peripheral surface that slides inside the casing 4. Reference numeral 6 denotes an output gear that meshes with the movable sun inner gear 5 and is fixed to an output shaft 7. It is a bearing that supports the output shaft 7 in the casing 4. The rotational force transmitted to the input shaft 11 causes the plurality of planetary gears 2 to rotate and revolve through the sun outer gear 1 and the fixed sun inner gear 3, and is decelerated and transmitted to the movable sun inner gear 5. This planetary gear mechanism is called a 3K mysterious planetary mechanism and is disclosed as being suitable for downsizing because it can have a large reduction ratio per unit volume. (For example, the 1990 Precision Engineering Society Autumn Meeting Academic Lecture Proceedings, First Volume 67 pages).

[0003]

However, in the prior art, the axial end faces of the fixed sun internal gear 3, the bearing 8 and the movable sun internal gear 5 and the end faces of the planetary gear 2 and the output gear 6 are axially opposed to each other. The gears face each other and relatively move in the circumferential direction during rotation. At the same time, if axial thrust is applied, it will come into direct contact and slide, resulting in a large friction loss, and abrasion powder and foreign matter that has entered through the gaps in the casing will adhere to the gear meshes, causing the foreign matter to surface the gear. Since it acts like polishing, it causes a loss of energy.
As a result, there are problems that the transmission efficiency in the reduction gear is reduced and the life is shortened. The present invention provides a micro speed reducer with a low friction loss by attaching a material having a low friction coefficient to the sliding surface of each gear and preventing foreign matter such as abrasion powder from appearing on the sliding surface of the gear. It is intended.

[0004]

In order to solve the above problems, the present invention provides a sun outer gear fixed to an input shaft, a plurality of planetary gears meshing with the sun outer gear, and a fixed sun meshing with the planetary gear. An internal gear, a cylindrical casing that fixes the fixed sun internal gear to the inside, end plates that close both ends of the casing, and an outer peripheral surface that is provided so that the outer peripheral surface slides inside the casing, In a micro speed reducer including a movable sun internal gear that meshes with the movable sun internal gear, and an output gear that is fixed to the output shaft, between the axial end faces of the respective gears, and between the movable sun internal gears. Sliding members having a small friction coefficient are provided between the outer periphery and the casing, and between the end plate and the gears. Further, the sliding member is a sliding sheet made of a sheet-shaped polymer material. Further, the sliding member has a large number of minute holes on the surface. Further, the sliding member has a large number of minute protrusions on its surface. Further, the sliding member is one in which an adhesive layer is provided on the surface of the concave portion formed between the minute protrusions.

[0005]

By the above means, each gear does not come into direct contact with other gears or the casing except for meshing, but slides with a sliding member having a small friction coefficient, so that the friction loss becomes smaller than that of the case of direct sliding. In addition, since a large number of minute holes and minute protrusions are provided at even intervals on the surface of the sliding member, the contact area of the sliding surface of the gear is reduced, the contact pressure is reduced by the fluid pressure, and the friction loss is reduced. To do. Further, foreign matters such as abrasion powder and fine dust are accumulated in the concave portions formed between the minute holes and the minute protrusions to prevent the foreign matters from adhering to the sliding surface, further reducing the friction loss. Further, by providing the adhesive layer in the concave portion, it is possible to prevent foreign matter once entering the concave portion from adhering to the gear again, so that the life of the reduction gear transmission can be extended.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a side sectional view showing a first embodiment of the present invention, and FIG. 2 is a front sectional view taken along the line AA of FIG. In the figure, 1 is a sun outer gear fixed to an input shaft 11, 2 is a plurality of planet gears meshing with the sun outer gear 1, and 3 is each planet gear 2
It is fixed to the inside of the cylindrical casing 4 by a fixed sun gear that meshes with the. 41 and 42 are end plates for closing both ends of the casing 4, 5 is a movable sun internal gear that meshes with the planetary gear 2, and 6 is meshed with the movable sun internal gear 5. , An output gear fixed to the output shaft 7. Reference numeral 9 denotes a sliding member made of a sheet-shaped polymer material having a low friction coefficient such as fluororesin, fixed between the end plate 41 and the sun external gear 1, between the end plate 41 and the planetary gear 2, and fixed to the end plate 41. Sliding sheet 91 inserted between sun inner gear 3, fixed sun inner gear 3 and movable sun inner gear 5
Of the sliding seat 92 inserted between the inner peripheral surface of the frame 4 and the outer peripheral surface of the movable sun internal gear 5, the planetary gear 2 and the output gear 6. Sliding sheet 94 inserted between, end plate 42 and movable sun internal gear 5
And a sliding sheet 95 inserted between the output gear 6 and the output gear 6. With such a configuration, the gears and the casing and the gears slide through the sliding member having a small friction coefficient, so that the friction loss can be made smaller than that of the direct sliding.

FIG. 3 (a) is an enlarged plan view showing the sliding member 9, and FIG. 3 (b) is a sectional view thereof, in which fine holes 10 of about 10 to 100 .mu.mm are evenly distributed over the entire surface of the sliding member 9. As shown in FIG. It is provided at various intervals. This reduces the contact area of the sliding surface of the gear and reduces friction loss. Further, abrasion powder generated from the inside of the speed reducer and foreign matter entering from the outside are carried to the minute holes 901 by the rotation of the gears, caught at the corners with the surface of the minute holes 901 and separated from the sliding surface of the gears, etc. It is accumulated inside the micropore 901. As a result, the sliding surface is always maintained in a normal state, and it is possible to prevent the performance of the reduction gear transmission from being deteriorated due to wear due to foreign matter and increase in friction loss. FIG. 4 is a perspective view showing a second embodiment of the sliding member 9,
Instead of providing micropores 901 on the surface, the diameter is 100μ.
mm, height 10 to 100 μm
02 are provided at even intervals over the entire surface of the sliding member 9, and recesses 903 are formed between the minute protrusions 902 so that foreign matters are accumulated in the recesses 903. As a result, the contact area of the sliding surface of the gear is reduced, and the sliding surface is always kept in a normal state. Further, the action of the dynamic pressure fluid bearing which increases the fluid dynamic pressure in the concave portion 903 occurs,
The contact pressure applied to the sliding surface is reduced, and the friction loss is reduced. FIG. 5 is a perspective view showing a third embodiment of the sliding member 9,
An adhesive layer 904 having an adhesive property is provided on the surface of the recess 903 of the sliding member 9 shown in the second embodiment. As a result, foreign matter once entering the recess 903 from the sliding surface of the gear or the like does not adhere again to the sliding surface of the gear or the like, and the life of the reduction gear transmission can be extended. In the above embodiment, the sheet-shaped sliding member 9 is inserted between the gears. However, the film-shaped sliding member is directly formed on the surface of the gear or the casing by means of coating or the like. Good.

[0008]

As described above, according to the present invention, since the sliding member having a small friction coefficient is provided between the gear and the casing, the friction loss can be reduced and the surface of the sliding member can be made minute. By providing holes or minute protrusions and accumulating abrasion powder generated in the speed reducer and foreign substances entering from the outside in the minute holes or recesses, it is possible to provide a micro speed reducer with good transmission efficiency and long life.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first embodiment of the present invention.

FIG. 2 is a front sectional view showing a first embodiment of the present invention.

FIG. 3A is a plan view and FIG. 3B is a side sectional view showing a sliding member according to a first embodiment of the present invention.

FIG. 4 is a perspective view showing a sliding member according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a sliding member according to a third embodiment of the present invention.

FIG. 6 is a side sectional view showing a conventional example.

[Explanation of symbols]

1 sun outer gear, 11 input shaft, 2 planetary gears, 3 fixed sun inner gear, 4 casing, 41, 42 end plates, 5
Movable sun gear, 6 output gear, 7 output shaft, 9 sliding member, 91, 92, 93, 94, 95 sliding sheet

Claims (5)

[Claims] 1. A sun outer gear fixed to an input shaft, a plurality of planetary gears meshing with the sun outer gear, a fixed sun inner gear meshing with the planetary gear, and a cylinder having the fixed sun inner gear fixed inside. -Shaped casing, end plates for closing both ends of the casing, an outer peripheral surface is provided so as to slide inside the casing, a movable sun internal gear that meshes with the planetary gear, meshes with the movable sun internal gear, In a micro reduction gear having an output gear fixed to an output shaft, between the axial end faces of the respective gears, between the outer periphery of the movable sun internal gear and the casing, the end plate and the respective A micro-reduction device characterized in that a sliding member having a small coefficient of friction is provided between the gear and the gear. 2. The micro speed reducer according to claim 1, wherein the sliding member is a sliding sheet made of a sheet-shaped polymer material. 3. The micro speed reducer according to claim 1, wherein the sliding member has a large number of minute holes on its surface. 4. The micro speed reducer according to claim 1, wherein the sliding member has a large number of minute projections on its surface. 5. The micro reduction gear transmission according to claim 4, wherein the sliding member is provided with an adhesive layer on a surface of a recess formed between the minute protrusions.