Rotational to linear movement actuator with limiter
AssigneeMeasurex Devron Inc.
InventorsAlbert A. Cuffe, Werner E. Jordi
Life of this patent
Estimating the term…
Abstract
An actuator converts rotational movement to linear movement and at the same time transmits a limited linear force without requiring slip clutches or the like. The actuator has an electric motor in a fixed housing with a drive shaft on a longitudinal axis. A drive gear, substantially free of backlash, is connected to the drive shaft and has an output connection to drive a drive nut with an internal screw thread on the rotary axis. An output shaft has an external screw thread engaging with the internal screw thread of the drive nut and moves linearly when the drive nut is rotated. A voltage control system allows the voltage to the motor to be set so that for a set voltage there is a predetermined longitudinal force on the output shaft.
Claims13
An actuator for converting a rotational movement to a linear movement for transmitting a predetermined longitudinal force comprising:
- a rotary electric motor within a fixed housing, the motor having a longitudinal axis with a rotating drive shaft extending thereon;
- a drive gear reducer, substantially free of backlash, the drive gear reducer having an intermediate shaft on the longitudinal axis connected to the rotating drive shaft, and an output connection about the longitudinal axis, the output connection rotating at a lower speed than the rotating drive shaft;
- a drive nut having an internal screw thread capable of rotating in the fixed housing about the longitudinal axis, and joined to the output connection of the drive gear the drive nut rotatable but not movable longitudinally in the fixed housing;
- an output shaft having an external screw thread capable of engaging with the internal screw thread of the drive nut, the output shaft having means to prevent rotation within the housing and adapted to move linearly on the longitudinal axis when the drive nut is rotated;
- voltage controller to set a voltage for the motor to provide the predetermined longitudinal force on the output shaft;
- and
- a linear potentiometer joined to the output shaft with a spring loaded sensor shaft extending from the linear potentiometer to measure linear movement between the fixed housing and the output shaft.
A method of applying a predetermined longitudinal force utilizing a rotary electric motor comprising the steps of:
- rotating an electric motor on a longitudinal axis to rotate a drive nut through a drive gear reducer within a fixed housing, the drive nut rotating at a slower rotational speed than the electric motor, the drive nut rotatable but not movable longitudinally in the fixed housing on the longitudinal axis, an internal screw thread on the drive nut engaging with an external screw thread on an output shaft such that rotation of the drive nut moves the output shaft linearly on the longitudinal axis;
- controlling voltage to the electric motor so that a set voltage provides the predetermined longitudinal force on the output shaft;
- and
- measuring linear movement between the fixed housing and the output shaft using a linear potentiometer joined to the output shaft with a spring loaded sensor shaft extending from the linear potentiometer.
Dependencies are inferred from the claim text.