JPH01316548A - Small size reduction gear - Google Patents

Abstract

PURPOSE:To increase a reduction ratio with a small and light reduction gear by forming the captioned reduction gear with planetary gears engaged with fixed and movable internal gears which have mutually different number of teeth and the sun gear of a motor shaft which is engaged with the planetary gears, supporting the holder bodies on both ends of the planetary gears on an axis and forming the movable internal gear with a plastic having a sliding characteristic and high strength. CONSTITUTION:Both ends of a planetary gear unit are held by a holder-body supporting base 7 and a holder retainer receiving portion 23, and a movable internal gear 20 is integrally formed with a plastic having sliding characteristic and high mechanical strength. When a sun gear 4 is rotated, planetary gears 12 start rotating on their axes and revolving because of a fixed internal gear 10. Since the number of teeth of the fixed internal gear 10 is (n) while that of the movable internal gear 20 being (n+ or -1-4), due to the rotation and revolution of the planetary gears 12, the tooth profile portions 11, 21 of both internal gears 10, 20 are gradually shifted from each other, rotating the movable internal gear 20 at a reduced sped. Thereby, the rotation of the sun gear 4 is transmitted to the movable internal gear 20 in the form of reduced rotation and increased torque, to be outputted to an output shaft portion 22.

Description

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

[Summary of the invention]

The present invention uses a special planetary gear (a) next to the reduction gear (a) of a small reduction gear that is directly connected to a small motor to achieve a wide reduction ratio and high torque with a small number of parts, thereby creating an inexpensive small reduction gear. Realize and provide.

[Conventional technology]

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. As shown in FIG. A lower case portion 34 is attached to the small motor 31 by screw connection with the motor shaft 32 as the central axis. The lower case part 34 has a support shaft 35
There are four planetary gears 36 on each support shaft 35.
The motor shaft gear 33 meshes with the inner periphery of the plurality of planetary gears 36 into which the planetary gears 36 are fitted, and the internal gear 37 meshes with the outer periphery. The output shaft gear part 3 is located at the center of the internal gear 37.
There are 9. The intermediate pedestal 38 is connected to the lower gauge part 34,
It serves as a bearing for the output shaft gear portion 39 and has a support shaft 35 . The output shaft gear portion 39 meshes with a planetary gear 36, and the planetary gear 36 meshes with an internal gear 37. In this way, if the gear in the center becomes the driving force and rotates the internal gear 37 via the planetary gear 36 as one set, then if the reduction ratio is large, this set will be repeated many times. There is. At the final stage of stacking these sets, an output shaft 40 is located at the center of rotation of the internal gear 37.

[Problem to be solved by the invention]

In a small reducer using a planetary gear mechanism with such a conventional configuration, the motor shaft gear 33 meshes with the internal gear 37 via the planetary gear 36 for deceleration, but the motor shaft gear 3
The reduction ratio of one set from 3 to the internal gear 37 is small, and several sets of gear trains are required to obtain a large reduction ratio. In this way, multiple gear parts are used to reduce speed by combining multiple gears. This has resulted in problems such as increased cost, large noise, and large backlash.

The present invention solves these conventional problems.The purpose of the present invention is to reduce the number of parts and cost, and to achieve a compact, lightweight design with a large reduction ratio, low backlash, and high transmission efficiency. The aim is to provide a high-performance compact speed reducer.

[Means to solve the problem]

The small reducer of the present invention includes a fixed internal gear 10 having a fractional number of internal gears, a movable internal gear 20 having an internal gear having a number of teeth of n±1 to 4, a fixed internal gear 10, and 1 to 4 planetary gears 1 that are external teeth with a number of teeth Z that mesh with the movable internal gear 20
2, and a sun gear 4 directly connected to a motor shaft 3 having one tooth that meshes with a planetary gear 12.

Further, the planetary gear 12 has a bearing supported at both ends on the holder integral 15, and the holder integral 15 has a bearing supported at both ends on the central axis of the sun gear 4. Furthermore, the movable internal gear 20 having the output shaft portion 22 is characterized by a mechanism that is integrally molded from plastic having sliding characteristics and high mechanical strength.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, in which a small motor 1 has a motor boss 2 and a motor shaft 3 on the central axis, and a sun gear 4 driven into the motor shaft 3. Components that have the same center axis as the center axis of the motor shaft 3 include a sun gear 4, a lower case member 6, a fixed internal gear 10, an integrated holder 15, a holder presser 19, a movable internal gear 20, and an upper case member 25. .

A lower gauge member 6 guided and positioned on the motor boss 2 is fastened to the motor 1 with a fixing screw 9. Fixed internal gear 1
0 is fixed to the lower case member 6 by the rotation stopper tooth 8. If the lower case member 61PI is a male tooth, the fixed internal gear 101FJ is female. They have a tooth-shaped shape and are fitted and fixed into each other. The planetary gears 6 mesh with two to four sun gears 4 in a point-symmetrical arrangement, and further mesh with the fixed internal gears 10.
The movable internal gear 20 also meshes with the movable internal gear 20. The planetary gear 12 is held by an integral holder 15 and a holder retainer 19 so that its central axis is always kept parallel to the central axis of the sun gear 4.

The upper and lower shafts of the planetary gear fit into the bearings of the holder unit 15 and the holder presser 19, and are supported at both ends. The holder unit 15 is composed of a planetary support stand 16 serving as a bearing part for one end of the planetary gear 12, a support column 17 for holding a holder presser 19, and a guide shaft 18 on which the holder presser 19 is positioned and fixed. A unit in which a planetary gear 12 is assembled into a holder integral 15 and fixed with a holder presser 19 is referred to as a planetary gear unit. The planetary gear unit is supported at both ends, with the lower end serving as a holder integrated support base 7 and the upper end serving as a bearing portion for the holder presser receiving portion 23, and rotates about the sun gear 4 as a central axis. The movable internal gear 20 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. Upper gauge member 2
5 and each constitute a bearing portion supported at both ends, and rotate around the central axis of the sun gear 4. The upper case member 25 has a hook 26, and the hook is fixed to the lower case member 6 by the claw 26, so that the bearing of the output shaft portion 22 is also arranged.
It is integrally molded from plastic with sliding properties and serves as the housing for the entire small reducer.

The movable internal gear 20 having the output shaft portion 22 is integrally molded with high precision from plastic having sliding characteristics and high mechanical strength. In the conventional case where the output shaft section 22 and the movable internal gear 20 were separate bodies and the output shaft section 22 was made of metal, it was an expensive part that required double D-cut machining. Furthermore, sub-assembly of the movable internal gear 20 and the output shaft portion 22 is required, reducing reliability. However, the movable internal gear 20 and the output shaft portion 22 can be integrally molded,
The aim was to lower the price and improve reliability.

The plastic material for integrally molding the movable internal gear 20 is as follows:
A blend of ROM or PA with carbon transitions or whiskers is used. 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 reducer, the lower case member 6,
Holder integrated 15, holder presser 1, upper case member 25
There is. These plastic materials are crystalline resins, with base polymers of POM, PA, and PBT, and blends of carbon fibers, whiskers, glass fibers, mica, and the like.

The tooth profile part of the planetary gear 12 is a tooth profile part a13 of the planetary gear,
It consists of a tooth profile part b14 of a planetary gear. The tooth profile part a13 of the planetary gear meshes with the tooth profile part 5 of the sun gear of the tooth profile part of the sun gear 4 and the tooth profile part 11 of the fixed internal gear of the tooth profile part of the fixed internal gear 10. The tooth profile b14 of the planetary gear meshes with the tooth profile 21 of the movable internal gear 20.

The tooth profile part a13 of the planetary gear and the tooth profile part b14 of the planetary gear have the same number of teeth Z, and the modules are slightly different.
The tooth profiles are in phase.

Therefore, when the sun gear 4 rotates, the fixed internal gear 10 does not move, so the planetary gear 12 starts to rotate and revolve.

The number of teeth of the fixed internal gear 10 is n, and the movable internal gear is a2.
The number of teeth of 0 is n±1 to 4.

Therefore, as the planetary gear 12 rotates and revolves around its axis, the tooth profiles of the fixed internal gear 10 and the movable internal gear 20 become misaligned, so that the movable internal gear 20 rotates at a reduced speed. This can be expressed numerically as follows.

In the above formula, numbers 1 to 4 are used as integers whose numerator and denominator are equal.

In this way, the rotation of the sun gear 4 is controlled by the movable internal gear 2.
The rotation that has been reduced to 0 and the increased torque are transmitted to the output shaft section 2.
2 is output.

FIG. 2 shows a plan view of this embodiment.As shown in FIG.
Two planetary gears are shown, but theoretically one could be used, but
From the balance of forces, the number of planetary gears ranges from 2 to 4, with 3 being the most desirable.However, from the above formula, the number of planetary gears is also limited by the reduction ratio.

In this way, a wide reduction ratio is achieved by meshing a small number of gears, so the reduction in transmission efficiency due to meshing is small and the transmission efficiency from input to output is high.

As a result, a large torque can be generated in the output shaft portion 22.

This means that the peripheral portion of the output shaft portion 22 must have strength to withstand large torque, but this mechanism is designed to withstand large torque in principle.

First, when the output shaft l/luk is replaced with the toothed portion 21 of a movable internal gear, the radius from the center is large, so the force received by the toothed portion is small.Furthermore, there are a plurality of planetary gears 12. Furthermore, the tooth profile portion 21 of the movable internal gear and the tooth profile portion b1 of the planetary gear
The engagement rate with 4 is large.

As a result of the above, the load applied to each tooth of the tooth profile part 21 of the movable internal gear, the tooth profile part b14 of the planetary gear, the tooth profile part a13 of the "a" star gear, and the tooth profile part 11 of the fixed internal gear can be small.
As a result, high torque of the output shaft portion 22 is achieved.

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

Furthermore, deceleration I! Since the I-structure is sealed by the lower gate member 6 and the upper case member 25, it is a small speed reducer with low noise and less dust.

〔Effect of the invention〕

As described above, according to the present invention, compared to known small-sized reduction gears of the same type, it is sufficiently small, can achieve a large reduction ratio with fewer parts, has high transmission efficiency, has low backlash, and has low noise. A small reducer with excellent dust resistance and low 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 an embodiment of the present invention. FIG. 3 is a sectional view showing a conventional structure. 1...Small motor 2...Motor boss 3...Motor shaft 4...Sun gear 5...Tooth profile of sun gear 6...Lower case member゛ 7...Holder integrated support stand 8... Rotation stop tooth profile part 9...Fixing screw 10...Fixed internal gear 11... Tooth profile of fixed internal gear 12... Planetary gear 13...Tooth profile part a of planetary gear 14...Tooth profile part b of planetary gear 15...Holder integrated 16... Planetary gear support stand 17... Pillar 18...Guide shaft 19...Holder presser 20...Movable internal gear 21...Tooth profile of movable internal gear 22...Output shaft part 23...Holder presser receiving part 24...outer periphery 25... Upper case member 26...The catch is the nail 31...small motor 32...Motor shaft 33...Motor shaft gear 34...Lower case part 35...Support shaft 36... Planetary gear 37...Internal gear 38...Intermediate cradle 39...Output shaft gear part 40...output shaft that's all Applicant: Seiko Epson Corporation Agent: Patent attorney Kisanbe Suzuki (and 1 other person) Figure 1 liu 2 figure

Claims (3)

[Claims] (1) Fixed internal gear with an internal gear with n teeth and n teeth
a movable internal gear having an internal gear of ±1 to 4; 1 to 4 planetary gears having a number of teeth Z that mesh with the fixed internal gear and the movable internal gear; A small speed reducer characterized by a planetary gear mechanism consisting of a sun gear directly connected to a motor shaft of a gear l meshing with a gear. (2) The small speed reducer according to claim 1, wherein the planetary gear is supported by a holder body with bearings supported at both ends, and the holder body has bearings supported at both ends on the central axis of the sun gear. (3) The small speed reducer according to claim 1, wherein the movable internal gear having an output shaft portion is integrally molded from a plastic having sliding characteristics and high mechanical strength.