JPH028538A - Small reduction gear - Google Patents

Abstract

PURPOSE:To attain substantial reduction ratio and high torque by a less number of a part items by providing planet gears, meshing with a fixed internal gear and a movable internal gear, and a sun gear meshing with these planet gears, in the case of a small reduction gear directly connected to a small motor. CONSTITUTION:A small motor 1 provides on its center axis a motor boss 2, motor shaft 3 and a sun gear 4 driven into the motor shaft 3. The sun gear 4, bottom case 6, fixed internal gear 20 and an upper case 25 are provided, serving a the parts having the same center axis to the center axis of the motor shaft 3. A planet gear 6 meshes with the sun gear 4, being arranged in quantity of 2 to 4 by the point symmetry of the sun gear 4, further the planet gear meshes also with the fixed internal gear 20 and a movable internal gear 10. Thus, transmitting efficiency is improved obtaining large reduction ratio with a less number of part items.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reduction mechanism for a small reduction gear that is directly connected to a small motor.

[Summary of the Invention] The present invention uses a special planetary gear mechanism in the reduction mechanism of a small reduction gear that is directly connected to a small motor, and achieves a large reduction ratio and high torque with a small number of parts, and provides an inexpensive small reduction gear. Realize and provide.

[Prior Art] An example of a conventional small speed reducer using this type of planetary gear mechanism is shown in FIG.

In FIG. 3, a motor shaft gear 33 is driven into a motor shaft 32 located at the center of a small motor 31. A lower case 64 is attached to the small motor 31 by screwing around the motor shaft 32 as a central axis.

Internal teeth 35 are fixed to the lower case 34, and two to four planetary gears 36 are disposed between the lower case 34 and the motor shaft 62. The motor shaft gear 33 meshes with the inside of the plurality of planetary gears 36,
Internal teeth 65 mesh with the outside. The centers of the plurality of planetary gears 36 are connected by a holder 37, and an output shaft gear portion 39 is located at the center of the holder 37. Intermediate receiver is stand 38
is connected to the lower case 34 and serves as a bearing for the output shaft gear portion 39. The output shaft gear portion 39 meshes with the planetary gear 36, and the planetary gear 36 meshes with the internal teeth 35. In this way, the gear in the center becomes the driving force, and the planetary gear 5
If the rotation of the holder 37 via the gear 6 is one set, then if the reduction ratio is large, the mechanism is such that this set is stacked in many stages. At the final stage of stacking these sets, an output shaft 40 is located at the center of rotation of the holder 37.

[Problems to be Solved by the Invention] In a small reducer using a planetary gear mechanism with such a conventional configuration, the speed is reduced from the motor shaft gear 36 to the holder 67 via the planetary gear 36, but from the motor shaft gear 33 to the holder 67. The reduction ratio of one set up to the holder 57 is small, and several sets of gear trains are required to obtain a large reduction ratio. This has resulted in problems such as increased cost, increased noise, and increased backlash.

The present invention is intended to solve these conventional problems.The purpose of the present invention is to reduce the number of parts and cost, and to create a compact and lightweight reducer with a large reduction ratio, low backlash, and high transmission efficiency. The purpose is to provide machines.

[Means for Solving the Problems] The small reducer of the present invention comprises a fixed internal gear having the same center and having m teeth, a movable internal gear having r teeth, and an external tooth having r teeth meshing with the fixed internal gear. and 1 to 4 planetary gears having external teeth with a number of teeth s that mesh with the movable internal gear, and a sun gear with a number of teeth t that is located at the center of the fixed internal gear and the movable internal gear and meshes with the planetary gear. [Examples] Examples of the present invention will be described below based on the drawings. 1st
The figure shows an embodiment of the present invention, in which a motor boss 2 and a motor shaft 3 are located on the central axis of a small motor 1.
There is a sun gear 4 driven in. The sun gear 4 is a component that has the same center axis as the center axis of the motor shaft B. Lower case 6, fixed internal gear 10. Holder 15. Holder presser 1
9. Movable internal gear 20. There is an upper case 25. A lower case 6 guided and positioned on the motor post 2 is fastened to the motor 1 with a fixing screw 9. The fixed internal gear 1o is fixed to the lower case 6 by a rotation stopper type fall portion 8. The rotation stopper shape may be any tooth shape or unevenness of the upper and lower cases. The planetary gears 6 mesh with two to four sun gears 4 in a symmetrical arrangement, and also mesh with the fixed internal gear 10 and the movable internal gear 20. The center axis of the planetary gear 12 is the sun gear 4
It is held by the holder 15 and the holder presser 19 so that it is always kept parallel to the central axis of the holder 15 and the holder presser 19. The upper and lower shafts of the planetary gear are accommodated in bearings of the holder 15 and the holder retainer 19, and are supported at both ends. The holder 15 is the planetary gear 12
The bearing at one end consists of a planetary gear support 16, a column 17 that holds the holder holder 19, and a holder holder 1.
9 consists of a guide shaft 18 that is positioned and fixed.

A unit in which a planetary gear 12 is assembled in a holder 15 and fixed by a holder presser 19 is referred to as a planetary gear unit. The lower end of the planetary gear unit is a holder support base7. The upper end is supported at both ends with the holder presser part 23 serving as a bearing part, and rotates around the sun gear 4 as the central axis. The movable internal gear 2o is made up of an outer peripheral part 24 on the outside of the internal tooth profile and an output shaft part 22 in the center, and the outer peripheral part 24 at the lower end is connected to the lower case 6.
The output shaft portion 22 at the upper end constitutes a part with the upper case 25, and bearings supported at both ends thereof respectively rotate around the central axis of the sun gear 4. The upper case 25 has a hook 26, which is fixed to the lower case member 6 by the hook, and also serves as a bearing for the output shaft 22, so it is integrally made of plastic with sliding properties. It serves as the housing for the entire small reducer.

The movable internal gear 2o having the output shaft 22 is integrally molded with high precision from plastic having sliding properties. Conventionally,
When the output shaft 22 and the movable internal tooth 2o were separate bodies, and the output shaft 22 was made of metal, it was an expensive part that required double D-cut machining. Further, the movable internal gear 20 and the output shaft 22 must be briefly assembled, which reduces reliability. However, by integrally molding the movable internal gear 20 and the output shaft 22, it has been possible to reduce the cost and improve reliability.

The plastic used to integrally mold the movable internal gear 20 is a blend of POM or PA with carbon fiber or whiskers. Note that this resin material is used not only for the movable internal gear 20 but also for the fixed internal gear 10 and the planetary gear 12.

In this small speed reducer, the lower case 6, holder 15. Holder presser 19. There is an upper case 25. These plastic materials are crystalline resins such as POM, F
A, PBT is the base polymer, carbon fiber, whiskers,
glass fiber.

Blended with mica, etc.

The tooth profile portion of the planetary gear 12 is composed of a planet gear tooth profile portion α13 and a planet gear tooth profile portion b14. The tooth profile part α13 of the planetary gear is connected to the tooth profile part 5 of the sun gear 4 and the fixed gear 1.
It meshes with both of the tooth profile portions 11 of 0. Planetary gear 12
The tooth profile b14 meshes with the tooth profile 21 of the movable internal gear 20. The tooth profile α13 of the planetary gear has the number of teeth r1 and the tooth number 8, and the module and phase are the same as the tooth profile 5 of the sun gear 4, the tooth profile 11 of the fixed internal gear 10, and the tooth profile 21 of the movable internal gear 20. It varies depending on the mesh of the

Therefore, when the sun gear 4 rotates, the planetary gear 12 starts to rotate and revolve since the fixed internal gear 10 does not move. When the number of teeth of the sun gear 4 is t1 and the number of teeth of the fixed internal gear 10 is m, the revolution of the planetary gear 12 is as follows:
Planetary gear 1 for 1/n/L+1) fixed internal gear 10
The rotation of 2 is m/r with respect to the revolution of 1. Further, when the number of teeth of the movable internal gear 20 is Le, 200 rotations of the movable internal gear is (Le/(n-s
It becomes 1/m/r)). The above can be expressed numerically as follows.

Reduction ratio = (yL/l, 4-1) x (yL/(r
L-sXm/r)) In the above, the value may be negative, which indicates that the output shaft portion 22 is rotating in the opposite direction to the sun gear 4.

In this way, the rotation of the sun gear 4 transmits a reduced rotation and increased torque to the movable internal gear 20, and the output shaft portion 22
is output to.

FIG. 2 shows a plan view of this embodiment. Although two planetary gears are shown in FIG. 2, theoretically one may be sufficient, and considering the balance of forces, two to four are necessary, and it is also desirable to have six. However, the number of planetary gears is also limited by the above formula and the number of teeth on each gear.

In this way, a large reduction ratio is achieved by meshing a small number of gears, so there is little reduction in transmission efficiency due to meshing, and the transmission efficiency from human power to output is high. as a result,
The output shaft portion 22 can generate a large torque.

This means that the peripheral portion of the output shaft portion 220 and the peripheral portion 22 must have strength to withstand large torque, and this mechanism is designed to withstand large torque in principle. First, if the output shaft torque is replaced with the tooth profile part 21 of the movable internal gear,
Since the radius from the center is large, the force applied to the tooth profile is small. Further, there are a plurality of planetary gears 12, and the meshing ratio between the toothed portion 21 of the movable internal gear and the toothed portion b14 of the planetary gear is large. As described above, the tooth profile portion 21 of the movable internal gear, the tooth profile portion b14 of the planetary gear, the tooth profile portion a13 of the planetary gear, and the tooth profile portion 11 of the fixed internal gear may receive small loads, and as a result, High torque is achieved.

Furthermore, since a high reduction ratio can be achieved by combining a small number of gears, backlash is small and the number of parts is small, resulting in a small, low-cost reduction gear.

Furthermore, since the speed reduction mechanism is sealed between the lower case 6 and the upper case 25, it is a small speed reducer that has low noise and is difficult for dust to enter.

[Effects of the Invention] As described above, according to the present invention, compared to known small-sized reduction gears of the same type, a large reduction ratio can be obtained with a sufficiently small number of parts, high transmission efficiency, and no backlash. A compact speed reducer that is small, has low noise, has excellent dust resistance, and is low in cost is provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention. FIG. 2 is a plan view showing one embodiment of the present invention. FIG. 6 is a sectional view showing a conventional structure. 1...Small motor 2...Motor post 3...Motor shaft 4゛...Sun gear 5... ......Tooth profile part 6 of sun gear...
...Lower case 7...Holder support base 8...Rotation stopper shape 9...Fixing screw 0... Fixed internal gear 1...Tooth profile portion of the fixed internal gear 2...Planet gear 3...Tooth profile portion α of the planet gear 4...Tooth profile portion of the planet gear b 5...Holder 6...Planetary gear support 7...Strut 8...Guide shaft 9...Holder retainer 0... ...Movable internal gear 1 ...Tooth profile section of movable internal gear 2 ...Output shaft 3 ...Holder presser part 4 ...Outer peripheral part 5... Upper case 6... Hook is part 1... Small motor 2... Motor shaft 3... Motor shaft gear 4. ...Lower case part 5 ...Inner teeth 6 ...Planetary gear 7 ...Holder 8 ...Intermediate support is stand 9 ...・・Output shaft gear part 0・・・・・・Above the output shaft

Claims (1)

[Claims] A fixed internal gear having m teeth and a movable internal gear having the same center, a movable internal gear having the number n of teeth, an external tooth having the number r of teeth that meshes with the fixed internal gear, and an external tooth having the number s of teeth that meshes with the movable internal gear. 4
1. A small speed reducer characterized by a planetary gear mechanism consisting of a number of planetary gears, and a sun gear having a number of teeth located at the center of the fixed internal gear and the movable internal gear and meshing with the planetary gear.