Measuring and testing – Dynamometers – Responsive to torque
Patent
1997-09-08
1999-12-14
Fuller, Benjamin R.
Measuring and testing
Dynamometers
Responsive to torque
G01L 302
Patent
active
060002891
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a flexible meshing type gear, and more particularly to a torque detecting device for a flexible meshing type gear which can detect torque with accuracy.
BACKGROUND ART
A servo system is used in a driving mechanism for driving an object to be controlled such as a robot and the like, and it is desirable in this case that torque applied to the object to be controlled be regulated. For that purpose, generally a torque detecting device is provided between a reduction unit composing a driving force transmission mechanism and an object to be controlled in order to detect transmission torque. For an appropriate torque detection, it is desirable that a reduction unit is provided therein with a torque detecting mechanism. In such a torque detecting mechanism, there have known a method of using a strain gauge, and that of measuring impedance of a magnetic-material-coated rotational part of a reduction unit.
As a reduction unit accommodated in a servo system, a flexible meshing type gear is known. The flexible meshing type gear is widely used in a system requiring drive control with accuracy, because the device of this type has a small number of parts and can give high reduction gear ratio. As a torque detecting mechanism for the flexible meshing type gear, there is a mechanism in which a strain gauge is adhered on a component flexible external gear. There is also a mechanism in which an outer periphery of a flexible external gear is coated with a magnetic material, and at the same time a magnetic head is placed in a position facing the coated position.
DISCLOSURE OF THE INVENTION
The inventors et al. confirmed that magnetic impedance varies according to internal stress when the rotational torque is applied to a flexible external gear, a component of a flexible meshing type gear.
The object of this invention is to provide a torque detecting device for a flexible meshing type gear with a configuration different from a conventional one, which can detect torque with accuracy, making use of a change in magnetic impedance generated in a flexible external gear.
The inventors et al. examined a change in magnetic impedance of a flexible external gear and found that there is a position where the positive rate of change of magnetic impedance turns negative, and vice versa, as an inherent property of the flexible external gear. This invention was realized on the basis of this discovery.
Namely, according to this invention, in a flexible meshing type gear which has a circular rigid internal gear, a circular flexible external gear placed inside the rigid internal gear and having external teeth which can mesh with internal teeth of the rigid internal gear, and a wave generator for deforming the flexible external gear radially to mesh the external teeth partially with the internal teeth and for moving meshing positions of the teeth in the circumferential direction so that relative rotation is generated between the rigid internal gear and the flexible external gear according to a difference in tooth number between the external teeth and the internal teeth; the flexible meshing type gear is provided with first and second magnetic impedance detecting elements in first and second positions, respectively, where changes in magnetic impedance with respect to transmission torque of the flexible external gear show opposite properties, whereby a transmission torque is detected on the basis of detected outputs of the first and second magnetic impedance elements.
As a flexible external gear, a cup-shaped one and a silk-hat-shaped one are generally known as well as a circular one. A cup-shaped flexible external gear has a tubular body, a circular diaphragm integrally formed at one end of the body, a boss integrally formed in the center of the diaphragm, and the external teeth formed on an outer periphery on the side of an open end of the body. In this case, the first magnetic impedance element may be placed at the end portion on the side of the diaphragm of the body, while the second magnetic impe
Horiuchi Masashi
Mohri Kaneo
Fuller Benjamin R.
Harmonic Drive Systems Inc.
Thompson Jewel V.
LandOfFree
Torque detecting device for a flexible meshing type gear does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Torque detecting device for a flexible meshing type gear, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Torque detecting device for a flexible meshing type gear will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-854044