US 4,876,906 A · Non-jamming actuator system

Abstract

A non-jamming electro-mechanical hydrostatic actuator system includes one embodiment in which a ballscrew assembly has a rotatable nut and an axially movable ballscrew. A motor rotates the nut to axially move the ballscrew. An actuator is operatively connected to a load to be actuated. A hydraulic system is coupled between the ballscrew and the actuator and includes a closed hydraulic circuit for statically trapping fluid in the circuit to effect movement of the actuator in response to movement of the ballscrew. The closed circuit is selectively opened to allow fluid flow in the circuit in the event of failure or jamming of the ballscrew assembly to allow reaction movement of the actuator in response to load forces. In another embodiment a rotary vaned assembly includes a cylinder housing a rotary vane, with the motor rotating the cylinder. The hydraulic system is coupled between the cylinder and the vane and includes a closed hydraulic circuit for statically trapping fluid in the circuit on opposite sides of the vane to effect conjoint rotation of the cylinder and the van. When the closed circuit is opened to allow fluid flow in the circuit the vane can rotate independently of the cylinder to allow reaction movement of the actuator in response to load forces.

Claims9

Dependent claims

A non-jamming actuator system, comprising:

a ballscrew assembly including a rotatable nut and an axially movable ballscrew, said ballscrew having means thereon for cooperating with the nut and for producing axial movement of the ballscrew upon the nut being rotated, the ballscrew comprising a cylinder of a double-acting piston and cylinder device;
drive means for rotating the nut;
axially moveable actuator means operatively associated with a load to be actuated, the actuator means being coupled to a piston within a chamber defined by said cylinder,
at least part of said cooperating means on said ballscrew axially overlapping said cylinder chamber;
and
a closed hydraulic circuit, including selectively operable valve means, communicating with the cylinder on opposite sides of the piston, whereby a closed condition of the valve means traps fluid in the circuit to effect movement of the actuator means in response to movement of the ballscrew and an open condition of the valve means allows fluid flow in the circuit in the event of failure or jamming of the ballscrew assembly to allow reaction movement of the actuator means in response to load forces.

3 more elements

Dependencies are inferred from the claim text.

Non-jamming actuator system

Life of this patent

Non-jamming actuator system

Life of this patent

Abstract

Claims9