Speed reducer, robot hand and robot

Abstract

Through holes are formed in a revolving gear which revolves while being engaged with a ring gear, and penetration pins which are configured to extract rotation of the revolving gear are inserted in the through holes. The ring gear and the revolving gear are divided into halves in the thickness direction. Two sheets of ring gears are biased to rotate in reverse directions.

Description

BACKGROUND[0001]1. Technical Field[0002]The present invention relates to a speed reducer which reduces an input rotational speed to be output.[0003]2. Related Art[0004]Most of the power obtained from a power source such as a motor is too high in its rotational speed or is too insufficient to be used as it is. In this respect, a technique has been typically used in which the rotational speed is reduced to an appropriate rotational speed using a speed reducer to obtain a necessary rotation number and a necessary torque.[0005]As a speed reducer which obtains a large reduction ratio, the following has been proposed. Firstly, a revolving gear which has a smaller size than a ring gear and has a smaller number of teeth (for example, by one tooth) than the ring gear is installed inside the ring gear. A circular cam is installed to be able to rotate with respect to the revolving gear in the central position of the revolving gear. A first rotational shaft is vertically installed in the circul...

AI Technical Summary

Benefits of technology

[0008]An advantage of some aspects of the invention is to provide a speed reducer which is capable of suppressing or avoiding occurrence of a backlash without sorting of component dimensions or assembly inspection, even with components having manufacturing errors.

[0011]According to this configuration, as the gear teeth of the first ring gear are pressed against the gear teeth of the first revolving gear and the first revolving gear rotates, the through hole of the first revolving gear is pressed against the penetration pin. Further, since the second ring gear is biased in the reverse direction to the first ring gear, as the gear teeth of the second ring gear are pressed against the gear teeth of the second revolving gear, the second revolving gear rotates in the reverse direction to the first revolving gear, and thus, the through hole of the second revolving gear is pressed against the penetration pin. In this state, if the first rotational shaft rotates to revolve the first revolving gear and the second revolving gear, even though the first rotational shaft rotates in any direction, any one of the first revolving gear and the second revolving gear is pressed against the first ring gear and the penetration pin, or the second ring gear and the penetration pin. As a result, the rotation of the first rotational shaft can be directly transmitted to the second rotational shaft, and thus, it is possible to suppress or avoid occurrence of a backlash.

[0013]According to this configuration, it is possible to bias the first ring gear and the second ring gear in the reverse directions in a simple manner. Further, the first ring gear and the second ring gear pull each other by a force of the coil spring. Thus, it is possible to suppress or avoid separation of the first ring gear and the second ring gear. Thus, it is possible to simplify the structure of the speed reducer.

[0015]According to this configuration, it is possible to set the centers of the two first revolving gear and second revolving gear on the central axis. As a result, for example, even in a case where the first rotational shaft rotates at high speed, it is possible to avoid generation of vibration due to fluctuation of the centers.

[0016]Further, the above-described speed reducer according to the aspect of the invention can realize a large reduction ratio and can suppress or avoid generation of a backlash between the ring gear and the revolving gear and a backlash between the through hole of the revolving gear and the penetration pin. Thus, the speed reducer is particularly effective as a speed reducer used in combination with a robot hand or a robot.

Problems solved by technology

Most of the power obtained from a power source such as a motor is too high in its rotational speed or is too insufficient to be used as it is.

However, in JP-A-2008-240852 as described above, there is a problem that a backlash easily occurs.

The latter backlash occurs due to a manufacturing error in the speed reducer having an operation principle of JP-A-2008-240852.

Further, since these two kinds of backlashes are present, a large backlash easily occurs as a whole.

As a result, there is a problem that a period occurs during which an output torque is not obtained with respect to the input of the first rotational shaft, or a large rattling in the rotational direction is generated in the second rotational shaft.

Alternatively, the dimensions of all the components are measured and sorted in advance, and the speed reducer is assembled with the components combined so that the size of the backlash is within an allowable range in assembly, which results in a considerably long time for assembly.