초록 ▼

A valve actuator preferably driven by an electric motor is disclosed. The valve actuator is useful with surface safety valves and uses power input from an electric motor to position the valve in its normal position. A mechanism is provided to allow the valve to shift positions to a failsafe position

A valve actuator preferably driven by an electric motor is disclosed. The valve actuator is useful with surface safety valves and uses power input from an electric motor to position the valve in its normal position. A mechanism is provided to allow the valve to shift positions to a failsafe position upon failure of electrical power to the motor connected to the actuator. A screw drive is provided with the motor, with a latch mechanism holding a nut against rotation. The nut can advance longitudinally upon rotation of the drive to move a valve stem. Upon failure of electrical power, the latch mechanism releases the nut from a coupling in the actuator which is connected to the valve stem, and the main return springs in the actuator allow the nut to rotate with respect to the screw drive so that the valve can assume its failed position. Normal applications allow the valve to fail closed; however, the valve can be configured so that failure results in opening of the valve if the application requires it.

대표청구항 ▼

[ We claim:] [1.] An actuator for a valve having a valve stem, comprising:a housing;a coupling movably mounted in said housing and adapted to be connected to said valve stem;an electrically powered drive assembly for selective actuation of said coupling in a first direction;a return mechanism in sai

[ We claim:] [1.] An actuator for a valve having a valve stem, comprising:a housing;a coupling movably mounted in said housing and adapted to be connected to said valve stem;an electrically powered drive assembly for selective actuation of said coupling in a first direction;a return mechanism in said housing operably connected to said coupling to selectively move said coupling in a second direction opposite said first direction;said drive assembly further comprising a mechanical latch mechanism to selectively engage said drive assembly to said coupling;a threaded shaft;a nut mounted to said threaded shaft, said latch mechanism selectively retaining said nut rotationally with respect to said coupling;whereupon with said nut retained by said coupling against rotation, said coupling is translated in response to a rotation of said shaft which translates said nut.