Harmonic Drive Systems Inc.

Hideo Asawa

Yoshihide Kiyosawa

Masaru Kobayashi

Toshiki Maruyama

Naomi Shirasawa

Akira Akahane

Hiroshi Takizawa

A wave gear drive ( ) includes an annular rigid internal gear ( ), an annular flexible external gear ( ) arranged inside of the annular rigid internal gear ( ), and a wave generator ( ) fitted inside of the annular flexible external gear. The wave generator ( ) includes a rigid cam plate ( ) having a predetermined outline, and a hub ( ) inserted into a fitting hole ( ) formed in the center of the rigid cam plate ( ). A transfer-torque control mechanism for limiting the torque transferred through the wave generator ( ) to the flexible external gear ( ) is defined by a nut ( ) that fastens the rigid cam plate ( ) and the hub ( ). When the torque equal to or greater than a predetermined value is transferred, a slip is generated in a rotational direction between the rigid cam plate ( ) and the hub ( ), thus limiting the transfer torque to a predetermined limit value. As a result, the torque limiter is not required. The use of the wave gear drive ( ), therefore, makes it possible to configure a small, compact actuator for driving the robot arm or the like as well as reduce the cost.

Wave gear drive having a transfer-torque control mechanism

A wave gear drive (1) has a silk-hat shaped flexible external gear (12) comprising a cylindrical body (13), a circular diaphragm (14), a circular boss (15) formed integrally on the diaphragm (14), and external teeth (16) formed on the body (13) at a side of an open end (13a) thereof. The boss (13) of the flexible external gear, a cross roller bearing (7) and the rigid internal gear (11) are arranged between first and second end plates (2, 3) so as to define a substantially sealed inside space of the wave gear drive (1). A resilient seal ring member (8) is mounted on the open end (13a) of the flexible external gear to divide the inside space into an inside portion (9) where a first lubricant having a high viscosity is supplied and an outside portion (10) where a second lubricant having a low viscosity is supplied. These lubricants are prevented from being mixed with each other during operation, thus proper lubrication to portions of the teeth (11a, 16) of the gears (11, 12) and to a wave bearing (19) of the wave generator (17) can be maintained.

Lubricant supplying mechanism for a wave gear drive

An optical position sensor comprises a linearity correction circuit 20 having ROM 22 in which a corresponding table between compensation values and respective rotational angular position of a rotational disk 51. The compensation values are obtained such that an actual relationship is measured between the rotational angular positions of the rotational disk 51 and the output B of a semiconductor position sensing device 54, deviation of the output B of the device 54 from a predetermined linearity relationship (A) is calculated, and compensation values are determined for eliminating the deviation of the output B of the device 54 at respective rotational angular positions of the rotational disk 51. The linearity correction circuit 20 retrieves a compensation value E from ROM 22 based on the output B of the device 54, and compensates the output A so as to produce the sensing output E which has a linearity relationship to the rotational angle of the rotational disk 51.

Optical position sensor

A wave gear device has a circular spline, a flexspline arranged within the circular spline, and a wave generator disposed within the flexspline for deflecting the flexspline in radial direction for partially engaging external tooth formed on the flexspline with internal gear teeth formed on the circular spline and shifting an engaging position in circumferential direction to cause relative rotation depending upon difference in number of teeth of the internal gear teeth and the external gear teeth between the circular spline and the flexspline. The circular spline has an annular rigid teeth portion formed with the internal gear teeth along the inner periphery thereof, a fastening portion to be rigidly secured on one of a device housing and a supporting member rotatably supported in the device housing, and a connecting portion connecting the rigid teeth portion and the fastening portion. The connecting portion has a low rigidity at least in one of a direction of an axis of the device and a direction perpendicular to the axis, in comparison with that of the rigid teeth portion.

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Nagano-ken, Japan

Hideo Asawa