Geared motor unit having function for limiting thrust load

Patent metadata

Field	Value
Publication number	US-9503014-B2
Application number	US-201514725606-A
Country	US
Kind code	B2
Filing date	May 29, 2015
Priority date	Jun 5, 2014
Publication date	Nov 22, 2016
Grant date	Nov 22, 2016

Abstract

A compact geared motor unit, capable of properly protecting an electric motor without disengaging gears or suspending the unit, even when a thrust force larger than an allowable value is generated. The geared motor unit 10 has an electric motor and a gear configured to generate a thrust force applied to the electric motor when transmitting a torque, and a control section for controlling the electric motor. The control section has a thrust load obtaining part which obtains a thrust load of the electric motor at predetermined timings or time intervals; a critical thrust load storing part which stores a critical thrust load of the electric motor; and a torque limiting part which electrically limits the torque of the electric motor when the obtained thrust load exceeds the stored critical thrust load.

First claim

The invention claimed is:

1. A geared motor unit, comprising:
an electric motor;
a gear connected to the electric motor so that a thrust load is applied to the electric motor when transmitting a torque; and
a control section which controls the electric motor,
wherein the control section comprises:
a thrust load obtaining part which obtains a thrust load of the electric motor;
a critical thrust load storing part which stores a critical thrust load of the electric motor; and
a torque limiting part which electrically limits the torque of the electric motor when the thrust load of the electric motor obtained by the thrust load obtaining part exceeds the critical thrust load of the electric motor stored in the critical thrust load storing part.

2. The geared motor unit as set forth in claim 1 , wherein the thrust load obtaining part calculates the thrust load of the electric motor based on the torque of the electric motor obtained by the control section and information regarding a dimension of the gear.

3. The geared motor unit as set forth in claim 1 , wherein the thrust load obtaining part obtains the thrust load of the electric motor as a detected value of a thrust load detector which detects the thrust load of the electric motor.

4. The geared motor unit as set forth in claim 1 , wherein the critical thrust load storing part stores a value of the critical thrust load which is predetermined depending on a type of the electric motor.

Assignees

• Fanuc Corp

Inventors

• Mishima Yamato

Classifications

• H02P29/028 Primary

  the motor continuing operation despite the fault condition, e.g. eliminating, compensating for or remedying the fault · CPC title

• H02P29/032 Primary

  Preventing damage to the motor, e.g. setting individual current limits for different drive conditions · CPC title

• F16H35/10

  Arrangements or devices for absorbing overload or preventing damage by overload · CPC title

• F16H1/02 Primary

  without gears having orbital motion · CPC title