초록 ▼

A fail-safe electric actuator, for use with a control mechanism such as a valve, is disclosed. The actuator device eliminates the possibility of the control mechanism being locked in operative position by the interruption of electric power, by automatically and mechanically returning the control mec

A fail-safe electric actuator, for use with a control mechanism such as a valve, is disclosed. The actuator device eliminates the possibility of the control mechanism being locked in operative position by the interruption of electric power, by automatically and mechanically returning the control mechanism to its inopertive position as soon as current is cut off. This is accomplished by the release of a torsion spring, wound previously by the rotation of a fluid-driven vaned torque actuator in turning both the control-mechanism and the electric fail-safe actuator into operative position.

대표청구항 ▼

In combination with a control mechanism characterized by the ability to be moved from inoperative to operative position and back, a fail-safe actuator device for automatically returning the control mechanism to inoperative position when interruption of electric power occurs, which comprises: a fluid

In combination with a control mechanism characterized by the ability to be moved from inoperative to operative position and back, a fail-safe actuator device for automatically returning the control mechanism to inoperative position when interruption of electric power occurs, which comprises: a fluid-driven vaned torque actuator: electric-motor-driven fluid power means for operating said torque actuator; electrically operated valve means for controlling the power fluid flow between said torque actuator and said fluid power generating means: at least one shaft projecting from said torque actuator; coupling means for operatively connecting said shaft to the control mechanism to be operated by the failsafe actuator device; reversible means for storing energy, said reversible means being operatively connected to said shaft; a limit-switch operating cam mounted on and rotatable with said shaft; a limit switch positioned for activation by said limit-switch operating cam; and electric circuitry means for interconnecting said motor-driven fluid power generating means, said valve means, and said limit switch, so that when electric power is applied to said circuitry means, said motor-driven fluid power generating means are energized and power fluid is delivered to said torque actuator, thereby rotating said torque actuator, said shaft, and the control mechanism to operative position, at the same time storing energy in said reversible energy-storage means: when said limit switch is activated said motor-driven fluid power means is deenergized and stopped, said valve means is closed to lock said torque actuator in place; and when electric power supply is interrupted, said valve means is deenergized and opened, permitting energy stored in said reversible means to return said shaft, thereby restoring the failsafe actuator device and the control mechanism to their initial inoperative position.