JP2889666B2 - Linear drive type harmonic transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a linear drive type harmonic transmission, and more particularly to a harmonic transmission capable of generating a relatively large thrust.

[Conventional technology]

A harmonic transmission generally has a rigid internal gear, an elastic external gear disposed inside the rigid internal gear, and radially bending the stepped external gear to mesh with the rigid internal gear at a plurality of locations. And a wave generator capable of moving the meshing position in the circumferential direction. When the wave generator is rotated at high speed, the meshing position of the rigid internal gear and the elastic external gear moves in the circumferential direction, and with the movement of the meshing position, the rigid internal gear and the elastic external gear are , A relative rotation occurs according to the difference in the number of teeth. Therefore, if one of these is fixed and the other is rotatable, a reduced rotation output can be obtained from the rotatably supported side.

In such a harmonic transmission, instead of the rigid internal gear, a cylindrical member having an internal thread formed on an inner peripheral surface is used,
If instead of the elastic external gear, a cylindrical member having an external thread formed on the outer peripheral surface capable of being screwed to the internal thread is used, the relative rotation according to the difference in peripheral length between the internal thread and the external thread is performed. Can occur in between. When such a relative rotation occurs, these members relatively move in the direction of the central axis. Therefore, for example, the cylindrical member on the male screw side is rotatably supported, and is restrained so as not to be movable in the center axis direction, and the cylindrical member on the other female screw side is restrained to be unrotatable. If the wave generator is supported so as to be movable in the central axis direction, the high-speed rotational motion of the wave generator can be converted into a linear motion in the central axis direction of the cylindrical member on which the external female screw is formed.

[Problems to be solved by the invention]

The linear drive type harmonic transmission having such a configuration has a problem in that a relatively large thrust for linear drive cannot be generated. That is, since the cylindrical member on the side where the external thread is formed on the outer peripheral surface must be elastically deformable in the radial direction, it must be a thin member. A thin member cannot transmit a large thrust. Therefore, the thrust that can be generated is relatively small.

An object of the present invention has been made in view of the above, and an object of the present invention is to realize a linear drive type harmonic transmission that can generate a relatively large thrust.

[Means for solving the problem]

In order to solve the above problems, in the linear drive type harmonic transmission according to the present invention, a male screw portion is formed on the outer peripheral surface on the opening end side of the cup-shaped member, and the cylindrical portion on which the male screw portion is formed is formed. , A plurality of slits extending in the central axis direction.

[Action]

Since the cylindrical portion on which the external thread portion is formed has a slit, it can be easily bent in the radial direction. Therefore, this part is formed from a thick member,
The rigidity in the central axis direction can be increased. For this reason, it is possible to generate a relatively large thrust from the linear drive type harmonic transmission of the present invention.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show a linear drive type harmonic transmission of this embodiment. As shown in these figures, the harmonic transmission device 1 of the present embodiment includes a rigid cylindrical member 2, a cup-shaped member 3 disposed coaxially inside the cylindrical member 2, and a wave generator mounted inside the cup-shaped member. 4 basically. A female screw portion 2a is formed on the inner peripheral surface of the rigid cylindrical member 2 over a predetermined range.

Explaining also with reference to FIG. 3, in the cylindrical portion 3a of the cup-shaped member 3, a male screw portion 3b screwable to the female screw portion 2a is formed on the outer peripheral surface on the opening end side. The external thread portion 3a is set to be slightly smaller than the internal thread portion 2a. Furthermore, the cylindrical part of this cup-shaped member
3a is formed with a plurality of slits 3c extending in the direction of the central axis 1a from the opening end to a position near the closed end side, and these slits 3c extend in the circumferential direction. They are formed at equal intervals.

On the other hand, the wave generator 4 mounted inside the cup-shaped member 3
Is composed of an elliptical rigid cam plate 4a, a ball bearing 4b fitted on the outer periphery of the cam plate, and an input shaft 4c fixed coaxially to the cam plate 4a. As can be seen from FIG. 2, the cylindrical portion 3a of the cup-shaped member 3 is bent into an elliptical shape by the rigid cam plate 4a, and the portions A and B of the male screw portions located at both ends in the longitudinal direction thereof are rigid cylinders. It is in a state of being screwed into the female screw portion 2a on the inner peripheral surface of the member 2.

Here, in the device 1 of this example, the rigid cylindrical member 2
Is constrained so as not to rotate, but is supported so as to be reciprocally movable in the direction of the central axis 1a. On the other hand, the inner cup-shaped member 3 is rotatably supported, but is restrained so as not to move in the direction of the central axis 1a. The input shaft 4c of the wave generator 4 is connected to a high-speed rotation output shaft (not shown) such as a motor.

In the device 1 of this example, when the wave generator 4 rotates at high speed, the screwing position between the male screw portion 3b bent by this and the female screw portion 2a on the side of the rigid cylindrical member is increased at high speed in the circumferential direction. Moving. Since the cup-shaped member 3 is rotatably supported and the rigid cylindrical member 2 is restrained from rotating, the cup-shaped member 3 rotates at a low speed. Here, since the low-speed rotating cup-shaped member 3 is constrained so as not to move in the direction of the central axis, when such rotation occurs, the side of the rigid cylindrical member 2 which is screwed with the cup-shaped member 3 is aligned with the central axis 1a. Move in the direction. As described above, in the device 1 of the present example, the rigid cylindrical member 2 can be reciprocated linearly in the direction of the central axis 1a by changing the rotation direction of the wave generator 4. Therefore, if the rigid cylindrical member 2 is connected to a driven member (not shown), the driven member can be reciprocated linearly.

Here, in the apparatus 1 of the present example, a plurality of slits 3c are formed in a portion of the cup-shaped member 3 where the male screw portion 3b is formed. The presence of these slits allows this part to flex easily in the radial direction. Therefore, even if this portion is formed from a thick member, required bending characteristics in the radial direction can be obtained. As a result, the cup-shaped member 3 of the device of this embodiment can transmit a relatively large thrust.
In other words, the device of this example can generate a relatively large thrust.

Although the rigid cylindrical member 2 is used as an output element in the device 1 of the present embodiment, the output element may be on the side of the cup-shaped member 3 on the contrary. Further, in this example, the male screw portion is screwed to the female screw portion at two places, but it is a matter of course that both may be screwed together at more places.

On the other hand, the shape, size, number, and the like of the slits formed in the cup-shaped member are properties that should be individually and appropriately set according to the thickness of the member, required bending characteristics, and the like.

〔The invention's effect〕

As described above, the linear drive type harmonic transmission according to the present invention employs a configuration in which a plurality of slits are provided in the cylindrical portion of the cup-shaped member where the male screw portion is formed. Accordingly, it is possible to increase the thickness of the cylindrical portion while maintaining the radial bending characteristics of the cylindrical portion in a good condition. Therefore, it is possible to realize a linear drive type harmonic transmission that can generate a larger thrust than before.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a linear drive type harmonic transmission according to one embodiment of the present invention, FIG. 2 is a schematic transverse sectional view showing a portion cut along the line II-II in FIG. The figure is a perspective view showing the cup-shaped member of the apparatus shown in FIG. [Description of Signs] 1 ……………………………………………………………………………………………………………………………………………………………………………………………………… NaN Generator.

Claims (1)

(57) [Claims] 1. A cylindrical rigid member having an internal thread formed on an inner peripheral surface thereof, and a cylindrical rigid member disposed on the inner side of the cylindrical rigid member and having an external thread which can be screwed to the internal thread formed on an outer peripheral surface thereof. A cup-shaped member provided with an elastic portion on the opening end side, and a cylindrical elastic member which is bent in a radial direction so that the male screw portion is screwed to the female screw portion at a plurality of circumferential positions. A wave generator capable of moving the mating position in the circumferential direction, wherein the cylindrical elastic portion of the cup-shaped member is formed with a plurality of slits extending in the center axis direction. Characteristic linear drive type harmonic transmission.