JPH01210642A - Reduction gear - Google Patents

Abstract

PURPOSE:To transmit high torque with few vibration and torque variation by constituting a reduction gear of two internal gears concentrically arranged and provided with an output shaft, one internal gear being fixed and the other being rotatable with different number of teeth. CONSTITUTION:An input shaft 1-1 is provided with three cranks, the central crank supporting an external gear 3 and both side cranks supporting external gears 3-1, 3-2 respectively meshing with the fixed side internal gear 4 and the rotary side internal gear 4-1. The external gears 3-1, 3-2 have the same number of teeth as the central external gear 3 and are interconnected by a pin 5 to be rotated in a body. Thus, bending movement applied to the input shaft 1-1 is reduced, while the bending moment of the output shaft is reduced since the output side internal gear 4-1 meshes with the external gear in two points.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a reduction gear that can provide a high reduction ratio suitable for small rotating mechanisms such as joints of robots and rotating parts of machine tools.

(Prior art) Conventionally used high speed reduction and high precision speed reducers include the one called Harmonic Drive (product name) shown in Figures 8 and 9, and the one shown in Figures 10 and 11. There is something called a cyclo reducer.

Among these, the harmonic drive has two internal gears a and b that are arranged in parallel and have thin walls that elastically deform.

A thin external gear C called a flex-spline, which has slightly fewer gears than the internal gears a and b, is meshed at two major diameter points of an ellipsoid d placed inside the gear.
This mechanism is such that one of the internal gears a and b is decelerated by using the difference in the number of minority teeth between the internal gears a and b and the external gear C as the ellipsoid d rotates.

On the other hand, the cyclo reducer is a mechanism in which a pin gear e and a cycloid external gear f are meshed over the entire circumference, and the difference in the number of teeth is used to reduce the speed.

In addition, as shown in FIG. 12, a known reduction gear disclosed in Japanese Patent Application Laid-Open No. 60-44637 has one external gear g (and g −+
l g −t ) has two internal gears with different numbers of teeth, i
There is a differential gear reducer that uses a mechanism that meshes the two wheels at the same center distance.

(Problem to be Solved by the Invention) However, in the harmonic drive described above, since the external gear C is thin, when torque is applied, the tooth tilts due to deformation of the tooth bottom of the external gear C, resulting in lost motion. Occur.

Teeth skipping occurred, and the spring constant as a reducer was also low.

In addition, in the cyclo reducer, it is difficult to process the pin gear e and the external gear f that meshes with the pin gear e, and furthermore, these gears e and f are in contact with each other around the entire circumference, so high-precision machining is required.

Furthermore, the number of parts was large, such as the need for a pin j to receive the reaction force of the external gear f and its bearing k, making the manufacturing process cumbersome.

In the case shown in Fig. 12, torque is transmitted only through the meshing of external gear g, and the other external gears gr, gz rotate on their own axis as the input shaft l rotates. By simply repeating the revolution, almost no force is generated by meshing with the internal gears and I, which each have a different number of teeth. For this reason, even if there are three external gears, the weight can be balanced around the input and output shafts, but the forces around the input and output shafts cannot be balanced, and the input and output shafts end up being cantilevered, resulting in bending moment. becomes large, making it difficult to transmit large torque, and the structure is prone to vibration.

In view of this, the present invention uses only involute gears, which are easy to manufacture, and is equipped with a gear for receiving one reaction force to reduce the number of parts, thereby making manufacturing easier, preventing tooth skipping due to overload, and improving the spring constant. The purpose of this invention is to provide a speed reducer that maintains a good force and weight balance, transmits large torque, and produces low vibrations, thereby overcoming the drawbacks of the prior art.

(Means and operations for solving the problem) In order to achieve the above object, the present invention provides two parts having different numbers of teeth, arranged concentrically in parallel, one of which is fixed, and the other is rotatable, and has an output shaft. A gear, three crank parts are formed on one side concentric with both internal gears, a human power shaft supported on the fixed side on the other side, and two internal teeth in the center of the crank part of the input shaft. A central external gear is supported so as to mesh across the gears, and crank portions on both sides of the central external gear have one side meshing with the internal gear on the fixed side and the other on the output shaft side. An external gear is supported to mesh with an internal gear.

The external gears on both sides are provided with a support that penetrates through a hole provided in the central external gear and integrally connects the external gears, and each of the gears is formed into a helical gear. The internal gear on the rotating side is rotated at a reduction ratio according to the difference in the number of teeth with the internal gear on the stationary side.

Involute gears can be manufactured even if the modules of external and internal gears are equal (1) By skillfully giving a shift to both or one of the gears, the difference in the number of teeth is small (1) Even if the difference in the number of teeth is 1 or even 0, The teeth and external teeth can mesh without causing meshing interference. In other words, Fig. 5 shows the number of external gear teeth Z
.

-29, internal gear fractional number Zi = 30, which is an example of a difference in the number of teeth of one tooth.If the amount of shift is further increased, it is also possible to manufacture internal teeth and external teeth that mesh with a difference in the number of teeth of zero. Figure 6 shows the fractional number of external gears Z, =
This is an example in which the gear difference is 0, such as 3t and the number of internal gear teeth zz=a1.

It is known that if the pressure angle is large and the teeth are made low, they can mesh without meshing interference even with a smaller amount of misalignment.

When the gears are shifted, the center distance between the two gears changes, and the amount of change is determined by the combination of the shift coefficients of the internal and external teeth. Therefore, if the shift coefficients are adjusted well, a single outer gear mechanism known as a mysterious gear mechanism can be created. This makes it possible to realize a gear mechanism in which two internal gears with slightly different numbers of teeth are meshed with each other at the same center distance.

(Embodiments) The present invention will be described below with reference to embodiments shown in FIGS. 1 to 7.

The speed reducer according to the present invention utilizes the properties of the above-mentioned dislocation impoliate gear, and a basic embodiment thereof will be explained based on FIG. 1.

In the figure, 1 is an input shaft with a crank part, 2 is an output shaft, 3 is an external gear supported on the crank part of the input shaft, 4 is an internal gear on the fixed side fixed to the machine frame, 4-1 is an internal gear on the rotating side fixed to the output shaft 2, and the external gear 3 meshes with both internal gears 4°4-+. Each of the external gears 3
The number of teeth on the internal gear 4 on the fixed side is ZI, the number of teeth on the internal gear 4 on the fixed side is Zt1, and the number of teeth on the internal gear 4-1 on the rotating side is Z Z l + However,
Zz≠Z□.

In this configuration, when the input shaft l rotates.

External gear 3 with number of teeth Z is internal gear 4° with number of teeth Zt, number of teeth 22
It revolves while simultaneously meshing with the positive internal gear 4-1.

At this time, Zz ≠Z! l, and the internal gear 4 on the fixed side
The shift coefficients of the internal gears 4-5 on the rotating side are adjusted so that they mesh with the external gear 3 at the same center distance, so when the input shaft 1 rotates at the rotational speed N1, the internal gears 4-5 on the rotating side Gear 4-+ is.

Rotate with. In other words, the reduction ratio m is the case where the number of external gears 3 is one in the above embodiment, but in this case, the reduction ratio m is the case where there is only one external gear 3. The input shaft 1.i meshes with the input shaft 1 at one point.
A large bending moment is applied to the output shaft 2, and large torque cannot be transmitted.

Therefore, this reduction gear has a configuration as shown in FIG.

That is, the input shaft 1-I is provided with three crank parts,
Both internal gears 4. External gears 3-1 and 3- support the external gear 3 that meshes with i, and mesh with the internal gear 4 on the fixed side and the internal gear 4-1 on the one-rotation side, respectively, on the crank portions on both sides.
support t. The external gears 3-+ and 3-z on both sides have the same number of teeth as the external gear 3 at the center.

Further, the crank parts on both sides of the input shaft 1-+ are out of phase with the central crank part by 180 degrees. External gears 3 on both sides
-+ and 3-z are connected by a support 5 passing through a hole 6 provided in the central external gear 3 so that they rotate together.

With this structure, the bending moment applied to the input shaft 1-1 is reduced, and since the internal gear 4-1 on the output side has two meshing points, the bending moment of the output shaft 1-+ is also reduced. Furthermore, the number of joint engagements is doubled, making it possible to transmit larger torque. Also, external gears on both sides: l
,, :1. If the total weight of the gear and the weight of the central external gear 3 are adjusted to be equal, the dynamic balance will be very good and there will be no vibration.

This type of reducer does not require pins or bearings for reaction force, and it uses involute gears instead of pin gears or cycloid gears, which are difficult to machine, making it extremely easy to manufacture the reducer. Furthermore, since no members with low rigidity are used, there are no drawbacks such as the tooth being susceptible to overload.

Furthermore, since it is an involute gear, the teeth can be easily twisted, and it becomes a so-called helical gear, increasing the number of teeth that mesh at the same time, so there is little load fluctuation at the beginning of tooth meshing and during the meshing process.

The effect of reducing load fluctuation when the teeth are helical has been studied in the case of externally toothed spur gears, and it has been reported that it is very effective.

What is shown in FIGS. 3 and 4 is a concrete example of the principle shown in FIG. This will be explained below.

At the center of the reducer, a crank part is provided on one side of the input shaft 1-4, and the central part and both ends are equal in size and have a phase difference of 180 degrees, and on the outer periphery of each crank part, bearings 7, 7- 1+
7-t are provided respectively. Each of these bearings 7
．． '1. ．． '! , each external gear 1, . . . has the same module, number of teeth, and shift coefficient. 3.3-2 are rotatably supported in order.

The external gears 3-1.3-z on both sides are integrally connected by a support 5 that passes through the hole 6 provided avoiding the teeth and axis of the central external gear 3 so as not to contact them. The connection is made by tightening a bolt 8 passing through the support column 5.

Further, the external gears 3-+ and 3-t are positioned in their rotational direction by a knock pin 9.9 provided on the support column 5.

The total weight of the external gears 3-+ and 3-z is made equal to the weight of the central external gear 3, thereby preventing vibration during rotation.

The fixed side internal gear 4 is an external gear 3.1. , 3 +g, and the internal gear 4-1 on the 0-rotation side, which has the same module and the same number of teeth, or has a minor difference in the number of teeth, has the same module as 4, but has a different shift coefficient and number of teeth.

The stationary internal gear 4 is fixed to a frame (not shown), and the rotating internal gear 4-+ is fixed to a rotating member (not shown) such as a joint of a robot.

This specific embodiment also has the same effect as the embodiment shown in FIG. 2 above.

That is, when rotation is inputted to the input shaft 1-1 from the morph axis that is not being implemented, this rotation is transmitted to the three external gears 3.3-, through the bearings 7.7-+ and 1-t.

3-z will be informed. At this time, if the fixed side internal gear 4 has the same number of teeth as each external gear 3.3-1+3-t, the external gears 3.3-1+3-t will not rotate and there will be a difference in the number of teeth. While rotating slightly, they each revolve at the same rotational speed as the input shafts 1-+. Center and left external gear 3.3-z
further transmits meshing power to the internal gear 4-8 on the rotating side, but this internal gear 4-1 on the rotating side is connected to the internal gear 4 on the stationary side.
Since the number of teeth is slightly different, it performs rotational movement and rotates the rotating member connected to it.

At this time, if the number of teeth of the fixed-side and rotating-side internal gears 4.4-+ is l+Zt+, the rotational speed of the input shaft 1- is N,
When , the rotational speed N0 of the internal gear 4-+ on the 1st rotation side is.

N. =(1-and)NtZ! It becomes I. The reaction force generated by the meshing of the external gear 3I of the internal gear 4-7 on the rotating side is generated by the reaction force between the external gear 3-I on the right side and the internal gear 4 on the stationary side, which are integrated by the support 5. The reaction force due to the meshing between the rotating internal gear 4-1 and the central external gear 3 is received by the meshing between the external gear 3 itself and the stationary internal gear 4. .

By making each tooth helical in such a gear, the number of gears that are simultaneously engaged increases as shown in FIG. 7, thereby reducing torque fluctuations, vibrations, and noise.

(Effects of the Invention) Since the present invention is configured as described above, it can produce various effects as shown below.

(1) Unlike the pin-cycloid gear, the gold teeth do not mesh at the same time, so there is no need for high-precision gear cutting as in the bottle-cycloid gear.

(2) Since the involute gears are simply shifted or have lower teeth, they can all be processed with the same pinion cutter, and unlike thin-walled gears, special jigs are not required and processing is easy.

(3) Since the reaction force generated by the meshing of the output stage is received by the meshing of the gears themselves, there is no need for many reaction force bins, bearings, etc. like in a cyclo-type reducer, and the number of parts is small and assembly is easy. It is also compact.

(4) Since it does not use members with weak rigidity like thin-walled gears, there is no tooth skipping due to overload.

The spring constant is also high.

(5) Since it is a combination of internal gears and external gears with slightly different numbers of teeth, the distance between the respective tooth surfaces is very close, and even slight deformation of the gears due to load torque results in a large effective meshing ratio and high torque. It is possible to communicate.

(6) By using three external gears and two internal gears, the shape is easy to install on the fixed side and output side, and the external gears can mesh at 180° symmetrical positions. As a result, there is less vibration and torque fluctuation.

(7) Backlash can be easily removed by slightly shifting the positions of the teeth of the two external gears at both ends in the rotational direction.

(8) By making all teeth helical, the actual number of meshing teeth increases, resulting in torque fluctuations and vibrations.

Noise is reduced.

[Brief explanation of the drawing]

Figures 1 to 7 show the reduction gear of the present invention.
The figure is a basic configuration diagram of the present invention, FIG. 2 is a diagram of a basic embodiment,
3 and 4 show specific examples, FIG. 3 is a cross-sectional view, FIG. 4 is a cross-sectional view taken along line A-A in FIG. 3,
5 and 6 are front views of an embodiment showing the meshing state of internal teeth and external teeth, which is the basis of the present invention, and FIG. 7 is an explanatory diagram showing the simultaneous meshing ratio of the speed reducer according to the invention. 8 to 12 show conventional examples, FIGS. 8 and 9 show harmonic drives, FIG. 8 is a sectional view, and FIG. 9 is a sectional view taken along line B-B in FIG. 8. Arrow view, 1st
0 and 11 show a cyclo reducer, and FIG. 10 is a sectional view. Figure 11 is a cross-sectional view taken along line C-C in Figure 10, the first
FIG. 2 is a configuration explanatory diagram showing the mysterious gear mechanism. 1-+... Input shaft 3. 3-+, 3-t... External gear 4, i,... Internal gear 5... Support 6... Hole
7.7-,,7-z... Bearing patent applicant Komatsu Ltd. Representative (patent attorney) Oka 1) Kazuyoshi Figure 1 Figure 2 Figure 3 Figure 4 Figure 8 Figure 9 Figure 11 Figure 42

Claims (1)

[Claims] Two internal gears with different numbers of teeth, one of which is concentric and parallel, one is fixed and the other is rotatable and has an output shaft, and three crank parts on one side that are concentric with both internal gears. an input shaft whose other side is supported on the fixed side, a central external gear supported in the center of the crank part of the input shaft so as to mesh with both internal gears, and External gears are supported on crank portions on both sides of the external gear so that one side meshes with the internal gear on the fixed side, and the other side meshes with the internal gear on the output shaft side, and What is claimed is: 1. A speed reducer characterized in that the gears are provided with a support that extends through a hole provided in the central external gear and integrally connects the gears, and each of the gears is formed as a helical gear.