JPH04370445A - Harmonic gear device - Google Patents

Abstract

PURPOSE:To prevent the generation of noise and breakage of a constituting part by facilitating processing of a constituting part and smoothing rotation of a tooth mating part. CONSTITUTION:A ball bearing 6 pivotally supported by a carrier 5 and machining of which is simple causes pressing of an external gear 3 against an internal gear 1 for engagement with each other. Thus, machining of a constituting part is facilitated, rotation of an engaging part is smoothed, and the engaging part is brought into a backlash state to prevent the generation of noise. Since by revolving the ball bearing 6 as it is turning on its axis, the engaging part is rotated, the engaging part can be smoothly rotated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a harmonic gear system used when a large reduction ratio is required.

0002

2. Description of the Related Art Conventionally, as shown in FIG. 3, a harmonic gear device consists of a shaft 51 whose outer diameter is machined into an elliptical shape, a thin-walled bearing 52 fixed to the outer periphery of this shaft 51, and a thin-walled metal elastic body. It has an external gear 53 fixed to the outer periphery of the thin bearing 52, and an internal gear 55, which is made of thick and rigid ring-shaped metal and has more teeth than the external gear 53.

The thin-walled bearing 52 is constructed by interposing metal balls 58, 58, . The outer diameter is elliptical in close contact with the elliptical shaft 51.

The external gear 53 is shaped like an ellipse in close contact with the outer ring 56 of the thin bearing 52, and meshes with the internal gear 55 near the two vertices of this ellipse.

In the harmonic gear device, when the shaft 51 rotates relative to the external gear 53, the meshing portion of the external gear 53 and the internal gear 55 rotates along the inner circumference of the external gear 53.

[0006] Here, the number of teeth of the external gear 53 is N1,
If the number of teeth of the internal gear 55 is N2, then the shaft 51 is 1
During rotation, the external gear 53 rotates in a direction opposite to the rotating direction of the shaft 51 with respect to the internal gear 55 by {(N2-N1)/N
Rotate by 1}×360°.

[0007]

However, the conventional harmonic gear device described above has the following drawbacks.

[0008] ■ It is difficult to process the shaft 51 into an oval shape.

[0009] ■ It is difficult to process the thin-walled bearing 52 comprising a thin-walled metal elastic body;
2 is expensive.

[0010] It is difficult to control the dimensions of the meshing portion between the internal gear 55 and the external gear 53, and backlash is likely to occur in this meshing portion, and noise is likely to be generated in the meshing portion.

■ When the shaft 51 rotates, the speed at which the metal balls 58 of the thin-walled bearing 52 advance within the thin-walled bearing is higher than that at the top portion of the elliptical thin-walled bearing 52 at a position offset by 90° in the circumferential direction from the top portion. As the speed increases, the retainer of the thin bearing 52 is likely to be damaged.

[0012] A relatively large shaft rotational driving force is required to continuously deform the outer ring 56 of the thin-walled bearing 52.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a harmonic gear device in which the component parts are easy to process, the meshing parts of the gears are smooth, and noise generation and damage to the component parts can be prevented. It is in.

[0014]

[Means for Solving the Problems] In order to achieve the above object, the harmonic gear device of the present invention includes a first gear, a second gear made of a flexible member fixed to a second shaft, 2nd above
a carrier fixed to a first shaft provided coaxially with the axis of the second gear, and a part of the second gear is pivotally supported by a pin on the carrier so as to press toward the first gear and mesh with the first gear;
The present invention is characterized in that it includes a planetary body that rotates and revolves along the back surface of the second gear along with the rotation of the carrier.

[0015] Furthermore, the first gear is an internal gear,
The second gear is preferably an external gear that is disposed inside the first gear and has fewer teeth than the first gear.

[0016]

[Operation] According to the above structure, when the first shaft rotates with respect to the first gear and the carrier connected to the first shaft rotates, the second shaft is pivotally supported by the carrier with a pin, A planetary body that presses a part of the gear toward the first gear to mesh with the first gear rotates while rotating along the back surface of the second gear.

When the first shaft rotates once, the second gear rotates 360 times the difference in the number of teeth between the first gear and the second gear divided by the number of teeth in the second gear. It rotates relative to the first gear by an angle multiplied by °.

As described above, the present invention uses a carrier and a planetary body that do not require particularly difficult machining to connect the second gear to the first gear.
Because it is pressed against the gears of the gears and engaged with them, there is no need for elliptical shafts that are difficult to machine and thin-walled bearings that are difficult to machine and expensive. Therefore, according to the present invention, the component parts can be easily processed and the component parts can be made inexpensive.

Furthermore, unlike the conventional example in which it was necessary to continuously deform the thin-walled bearing in order to rotate the meshing part of the gear, the present invention simply revolves around the planet while rotating the first gear. The meshing portion between the gear and the second gear can be rotated.

[0020] Furthermore, since the second gear made of a flexible member is pressed toward the first gear and meshes with it, there is no backlash in the meshing area between the first gear and the second gear, and noise generation is reduced. Prevented. In addition, since the second gear is made of a flexible member, the meshing portion between the first gear and the second gear rotates smoothly, and the rotational driving force necessary to rotate the first shaft is generated. Can be reduced.

[0021] When the first gear is an internal gear and the second gear is an external gear having fewer teeth than the first gear, the internal gear and the external gear Since the gears mesh in the radial direction, the space in the axial direction is reduced.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below with reference to illustrated embodiments.

FIG. 1 shows a first embodiment of the harmonic gear system of the present invention. This embodiment includes an internal gear 1 made of metal and an external gear 3 made of elastic rubber. The external gear 3 is fixed to an output shaft 2 fitted to a block 9 via bearings 11, 11, and the internal gear 1 is fixed to blocks 8 and 9. The number of teeth of the external gear 3 is smaller than the number of teeth of the internal gear 1. A carrier 5 is fixed to an input shaft 4 which is provided coaxially with the output shaft 2 and fitted into a block 8 via a bearing 10. A ball bearing 6 as a planetary body is pivotally supported on the carrier 5 by a pin 7 passing through the end of the carrier 5 in the axial direction, and the ball bearing 6 supports a part of the external gear 3 on the internal gear 1. It is pressed towards the radial direction so that it engages in the radial direction.

In the harmonic gear device configured as described above, when the input shaft 4 rotates with respect to the internal gear 1 and the carrier 5 connected to the input shaft 4 rotates, the pin 7 erected on the carrier 5 rotates. A press-fitted ball bearing 6 presses a part of the external gear 3 toward the internal gear 1 and engages with the internal gear 1, while rotating and revolving along the back surface of the external gear 3. Then, when the input shaft 4 rotates once, the external gear 3 is rotated by multiplying the value obtained by dividing the difference in the number of teeth between the internal gear 1 and the external gear 3 by the number of teeth of the external gear 3 by 360°. The internal gear rotates by an angle relative to the internal gear 1.

As described above, in the above embodiment, the easily machined and inexpensive ball bearing 6 supported by the easily machined carrier 5 presses the external gear 3 against the internal gear 1 to mesh with it, which is not necessary in the past. Oval shafts that are difficult to machine and thin-walled bearings that are difficult to machine and expensive are unnecessary. Therefore, in this embodiment, the component parts can be easily processed.
Component parts can be made cheaper.

Furthermore, unlike the conventional example in which it was necessary to continuously deform the thin-walled bearing in order to rotate the meshing part of the gear, in this example, the internal gear 1 and the external gear 1 are connected by rotating the ball bearing 6. The meshing part with the gear 3 can be rotated, and there is no need for a thin bearing that needs to be deformed as in the past. Therefore, this embodiment requires no overstressed parts and is less susceptible to failure.

Further, since the external gear 3 made of elastic rubber is pressed toward the internal gear 1 and meshes with it, the internal gear 1
There is no backlash in the meshing portion between the external gear 3 and the external gear 3, and noise generation can be prevented. Further, since the external gear 3 is made of elastic rubber, the meshing portion between the external gear 3 and the internal gear 1 rotates smoothly, and the rotational driving force required to rotate the input shaft 4 can be reduced.

Furthermore, in this embodiment, since the internal gear 1 and the external gear 3 mesh in the radial direction, the space in the axial direction can be reduced.

Next, a second embodiment is shown in FIG. This embodiment consists of a first gear 21 having teeth on a metal end face fixed to a block 29, and an elastic rubber fixed to an output shaft 22 fitted to the block 29 via bearings 31, 31. A second gear 23 having teeth is provided. This second gear 23 has fewer gears than the first gear 21. The bearing 3 is provided coaxially with the output shaft 22.
A carrier 25 is fixed to an input shaft 24 that is fitted into a block 28 via pins 0 and 30. Then, a ball bearing 26 as a planetary body is pivotally supported on the carrier 25 by a pin 27, and the ball bearing 26 presses a part of the second gear 23 toward the first gear 21 to mesh in the axial direction. That's what I do.

In the harmonic gear device configured as described above, when the input shaft 24 rotates with respect to the first gear 21 and the carrier 25 connected to the input shaft 24 rotates, the carrier 25 is pivotally supported by the pin 27. The ball bearing 26 presses a portion of the second gear 23 toward the first gear 21 and engages with the second gear 21, while rotating and revolving along the back surface of the second gear 3. Then, when the input shaft 24 rotates once, the second gear 23 rotates 360 times to the value obtained by dividing the difference in the number of teeth between the first gear 21 and the second gear 23 by the number of teeth of the second gear 23. It rotates with respect to the first gear 21 by an angle multiplied by °.

As described above, the above embodiment uses an easy-to-work and inexpensive ball bearing 26 that is pivotally supported by an easy-to-work carrier 25.
Since the second gear 23 is pressed against and meshed with the first gear 21, there is no need for an elliptical shaft that is difficult to machine and a thin-walled bearing that is difficult to machine and expensive, which were conventionally required. Therefore, in this embodiment, the component parts can be easily processed and the component parts can be made at low cost.

Furthermore, unlike the conventional example in which it was necessary to continuously deform the thin-walled bearing in order to rotate the meshing portion of the gear, in this example, the first gear 21 and the ball bearing 26 are rotated. The meshing portion with the second gear 23 can be rotated, and there is no need for parts that need to be deformed as in the past, making it less likely to be damaged.

Furthermore, since the second gear 23 made of elastic rubber is pressed toward the first gear 21 and meshes with it, there is no backlash in the meshing portion between the first gear 21 and the second gear 23. Noise generation can be prevented. Also, the second
Since the gear 23 is made of elastic rubber, the meshing portion between the second gear 23 and the first gear 21 rotates smoothly, and the rotational driving force required to rotate the input shaft 24 can be reduced.

In the first and second embodiments described above, since ball bearings are used as the planetary bodies, the planetary bodies can revolve extremely smoothly while rotating on their own axis, and noise and transmission loss can be reduced.

In the above embodiment, a ball bearing was used as the planetary body, but a roller bearing, a sliding bearing, a spherical body, etc. may also be used. Further, in the first and second embodiments, the external gear 3 and the second gear 23 made of elastic rubber are used, but the external gear and the second gear 23 may be made of soft plastic.

[0036]

As is clear from the above description, in the harmonic gear device of the present invention, as the carrier connected to the first shaft rotates, the planetary body pivotally supported by the carrier with the pin rotates the second gear. While pressing a part of the gear toward the first gear and engaging it, the gear revolves while rotating along the back surface of the second gear. Therefore, according to the present invention, the second gear is connected to the first gear using a carrier and a planetary body that are easy to process.
Because it is pressed against the gears of the gears and engaged with them, there is no need for elliptical shafts that are difficult to machine and thin-walled bearings that are difficult to machine and expensive. Therefore, the harmonic gear system of the present invention is easy to process and inexpensive.

Furthermore, unlike the conventional example in which it was necessary to continuously deform the thin-walled bearing in order to rotate the meshing part of the gear, the present invention allows the planetary body to rotate and revolve around the first gear. The meshing portion with the second gear can be rotated smoothly, and according to the present invention, durability is improved.

Furthermore, since the second gear made of a flexible member is pressed toward the first gear and meshes with it, there is less backlash in the meshing area between the first gear and the second gear, which reduces noise generation. can be prevented. In addition, since the second gear is made of a flexible member, the meshing portion between the first gear and the second gear rotates smoothly, and the rotational driving force necessary to rotate the first shaft is generated. Can be reduced.

[0039] Further, the first gear is an internal gear,
If the second gear is an external gear having fewer teeth than the first gear, the internal gear and external gear mesh in the radial direction, reducing the space in the axial direction. can.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a first embodiment of a harmonic gearing device according to the invention.

FIG. 2 is a half-sectional view of a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of a conventional harmonic gear device.

[Explanation of symbols]

1,55 Internal gear
2, 22 Output shaft 3, 53 External gear
5, 25 Carrier 6, 26 Ball bearing
7, 27 Pin 8, 9, 28, 29 Block 10, 11,
30, 31 Bearing 21
First gear 23
Second gear 51 shaft
52 Thin wall bearing 56 Outer ring
57 Inner ring 58 Metal ball

Claims (2)

[Claims] Claim 1: A first gear, a second gear made of a flexible member fixed to a second shaft, and a first gear fixed to the first shaft provided coaxially with the second shaft. The carrier and a part of the second gear are pivotally supported by pins on the carrier so as to press toward the first gear and engage with each other, and rotate along the back surface of the second gear as the carrier rotates. A harmonic gear device characterized by having a planetary body that revolves while rotating. 2. The first gear is an internal gear, and the second gear is an external gear disposed inside the first gear and has a smaller number of teeth than the first gear. The harmonic gear device according to claim 1, wherein the harmonic gear device is a gear.