US 2006/0221518 A1 · Linear actuator

Abstract

A linear actuator having a housing, a plunger slidably mounted to the housing between an extended and retracted position, and an electric motor drivingly connected to the plunger to move the plunger between its extended and retracted positions. A motor circuit controls the activation of the motor circuit and deactivates the motor circuit whenever the motor current exceeds a threshold value which varies as a function of the supply voltage to the electric motor and/or temperature. A memory storage unit stores the position of the plunger. Whenever the position of the plunger is in a state of transition between its retracted and extended position upon system initialization, the motor control circuit activates the motor to drive the plunger to a preselected extended or retracted position.

Claims24

Dependent claims

A linear actuator comprising:

a housing,
an electric motor having a supply voltage and a rotary drive shaft,
a plunger slidably mounted to said housing and movable between an extended position and a retracted position,
a mechanical transmission assembly which converts rotary motion of said motor drive shaft to linear displacement of said plunger between said extended position and said retracted position,
a motor control circuit which deactivates said motor when the motor current exceeds a threshold value, said motor control circuit including an adjustment circuit which varies said threshold value as a function of a sensed condition.

2 more elements

Dependencies are inferred from the claim text.

Linear actuator

Life of this patent

Linear actuator

Life of this patent

Abstract

Claims24