초록 ▼

A position actuator includes a motor driven low efficiency lead screw with a follower moving in parallel relation to a valve coupler of a valve shaft and a switch operator of a force/torque limit unit. A lever is pivotally coupled to the follower, coupler and the operator. The lever pivots about the

A position actuator includes a motor driven low efficiency lead screw with a follower moving in parallel relation to a valve coupler of a valve shaft and a switch operator of a force/torque limit unit. A lever is pivotally coupled to the follower, coupler and the operator. The lever pivots about the operator to move the valve coupler at a valve limit. The coupler cannot move and the lever pivots about the coupler to move the operator and actuates a switch to signal an alarm and/or another controller. The limit unit includes an elongated coil spring having a low spring rate within a tubular housing having mounting plates for switches. The operator passes through the spring and has retainers abutting the spring ends and the housing to provide a factory spring calibration. The lever couplings include a lever opening with spaced knife-edges to provide low friction engagement. In a damper control, limit unit is mounted to a driven sector gear and a lever is secured to a damper shaft. At limit condition, the shaft cannot move and sector gear movement moves the operator to actuate the switch. A linear actuator may be connected directly to the operator for in-line movement. The limit unit provides precise identification of the actuator movement and may provide end limit signals for initializing a stepper motor control and/or a constant speed motor control.

대표청구항 ▼

A limit switch apparatus for monitoring bi-directional movement of a positioned device between first and second limits and having an electrically operated motor means operable to establish forced movement of the positioned device in excess of the force on the device in moving between said first and

A limit switch apparatus for monitoring bi-directional movement of a positioned device between first and second limits and having an electrically operated motor means operable to establish forced movement of the positioned device in excess of the force on the device in moving between said first and second limits whereby the force increases at said first and second limits, comprising a spring means having retainer means movably mounted for stressing said spring means, a switch operator coupled to said retainer means, switch means mounted in the path of said operator, a pivot unit secured to said switch operator and extending axially outwardly of said operator, a pivoted lever coupled to said pivot unit and operable to pivot in opposite directions relative to said switch operator, said pivoted lever being operable to move said pivot support unit relative to said spring means in response to movement at both said limits and thereby actuate said switch means in response to said forced movement at said limits.