US 5,655,636 A · Compact actuator including resettable force limiting and anti-backdrive devices

Abstract

A compact ball screw type actuator having both load limiting capability above a pre-determined value and position holding capability at all load values above, below and at the pre-determined value is provided through use of a resettable force limiting assembly acting directly on an element of the ball screw, in conjunction with a friction drag device operating directly upon an input shaft operatively coupled through a crossed-helical gear train to the ball screw. The force limiter utilizes axial force on the ball screw above the pre-determined value for engaging clutch teeth to limit the force applied by the ball screw, or to provide the position holding function and for preventing backdriving of the actuator. For force levels at or below the pre-determined value, the input drag device provides the position holding function.

Claims16

Dependent claims

An actuator comprising:

a force transmitting reciprocating output member drivingly carried by an actuating member mounted for rotation about an axis within a housing;
a reversible torque input operatively coupled to said actuating member to cause said output member to translate along said axis in a direction dependent upon the direction of rotation of said input;
force limiting means operatively connected between said actuating member and said housing for reacting input torque into said housing when axially directed tension or compressive forces above a predetermined value are experienced by said output member, reverse rotation of said input torque resulting in the release and resetting of the force limiting means;
and
position holding means including friction drag means operatively connected between said input and said housing for imposing sufficient continuous friction drag torque on said input to prevent axially directed tension or compressive forces experienced by said output member at or below said predetermined value from backdriving said input.

2 more elements

Dependencies are inferred from the claim text.

Compact actuator including resettable force limiting and anti-backdrive devices

Life of this patent

Compact actuator including resettable force limiting and anti-backdrive devices

Life of this patent

Abstract

Claims16