Actuator
AssigneeThe Bendix Corporation
InventorJames M. Eastman
Life of this patent
Estimating the term…
Abstract
In an actuator system (10) having an air motor (12) for supplying a ball-screw actuator (14) with rotary input. The ball screw actuator (12) has a friction clutch mechanism (206) that limits the torque applied to the screw (176) when the ball nut (166) reaches first and second extreme positions. Thus, the maximum output from the air motor (12) can be applied to ball screw actuator (14) without braking before the positions are reached. A torsion bar and a cam 274 act to regulate the clutch (206) slipping torque to narrow limits, thereby easing strength requirements in the actuation mechanism (10).
Claims17
In an actuator having a housing with a bore therein, a shaft located in said bore, a nut carried on said shaft and rotationally restrained in said bore, an input member, an output member connected to said nut, and a linkage member for connecting said input member to said shaft, said linkage member transmitting a rotary torque from the input member to said shaft causing said nut to move in said bore and provide said output member with linear movement, said linkage being characterized by a drive member connected to said input member, a driven member connected to said shaft by a torsionally flexible member and an axially resilient member for urging said driven member into engagement with said drive member, said torsionally flexible member transferring a rotary torque from said driven member into said shaft until rotary movement of said nut is restrained, said rotary torque thereafter rotating said driven member to reduce the force of the axially resilient member and allow the drive member to rotate independent of said driven member.
In an actuator system having a source of fluid under pressure, a motor responsive to said fluid pressure for developing a rotary torque, a transmission mechanism for transferring said rotary torque to drive a screw mechanism and move a nut between first and second positions and supply a device with an operational output, a valve responsive to an operational signal for allowing fluid from the source to flow to said motor and develop said rotary torque, and limiter valve means responsive to movement of said device to initiate termination of the communication of fluid from said source, and a brake for locking said motor when fluid from said source is terminated, the improvement in the transmission mechanism comprising:
- a drive member connected to said transmission mechanism;
- a driven member;
- a resilient member for urging said driven member into frictional engagement with said drive member;
- and
- a flexible torsional member connected to said driven member for transferring rotary torque to said screw mechanism from said driven member, said screw mechanism being rotationally restrained when said nut reaches said first and second positions, said flexible torsional member responding to the increased rotary torque during restraint of said screw mechanism by rotating said driven member with respect to said screw to reduce the axial urging force of said resilient member and permitting said drive member to rotate independent of said driven member to prevent inertial damage to said nut and said screw mechanism by an abrupt stop at said first and second positions.
In a motor driven two position rotary actuator a control means comprising:
- stop means for limiting the angular stroke of the actuator;
- friction means for establishing a slip torque;
- elastic means for exerting a force on said friction means to determine the magnitude of the slip torque;
- flexible torsional means responsive to said clutch output torque;
- cam means operated by said flexible torsional means to increase the length of said elastic means when output torque increases above a predetermined level to rapidly lower the force on said friction means and initiate slipping at a substantially predetermined torque to allow the motor to over run after engaging said stop means to limit the torque developed by motor inertia and absorb its kinetic energy;
- shut off means for turning off the motor power when said stop means is engaged;
- and
- brake means for locking the motor in a fixed position when power is turned off and rotation has stopped.
Dependencies are inferred from the claim text.