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US 5,333,989 AGranted
Electric actuators for steam turbine valves
AssigneeGeneral Electric Company
InventorsAdrian Missana, Russell A. Gary
Life of this patent
Estimating the term…
Abstract
Linear electric actuators powered by DC brushless servomotors are individually controlled to position steam turbine valves by way of levers, pins and links to thus eliminate hydraulics and the attendant disadvantages of fluid filtering, conditioning and leakage as well as obtaining more flexible individual valve control, vis-a-vis, camshaft operated hydraulic actuators. Additionally, low friction actuators and springs are employed to automatically close the turbine valves in the event of a power failure.
Claims7
A steam turbine control system comprising:
- at least one valve for controlling the admission or extraction of steam to a turbine;
- a lever;
- a support element for pivotally supporting one end of said lever;
- an electrically operated linear actuator for pivotally supporting another end of said lever, said actuator including a linearly extendable shaft, an electric motor and a drive means operatively connected between the motor and the shaft for reciprocally positioning said shaft at a controllable and selectable position;
- sensor means for determining system operating conditions and for providing signals indicative of the conditions;
- a control means responsive to said sensor means and connected to said actuator for supplying electrical signals and power to said motor for controllably positioning said valve at a said selectable position;
- a linkage element pivotally connected between said lever and said valve for conveying linear motion to said valve;
- and
- said support element including means for pivotally mounting said actuator so that an axis along which the actuator shaft reciprocally extends cooperatively moves with an axis along which the linkage element reciprocally extends so as to compensate for any horizontal movement of the linkage element axis at the pivotal connection between said linkage element and said lever;
- a spring supportably mounted about said linkage element and operatively connected to said valve for forcing said valve to a closed position in the absence of electrical power being supplied to said motor.
7 more elements
A steam turbine control system comprising:
- at least one valve for controlling the admission or extraction of steam to a turbine;
- a lever;
- a support element for pivotally supporting one end of said lever;
- an electrically operated linear actuator for pivotally supporting another end of said lever, said actuator including a linearly extendable shaft, an electric motor and a drive means operatively connected between the motor and the shaft for reciprocally positioning said shaft;
- a control means connected to said actuator for selectively supplying electrical signals and power to said motor;
- a linkage element pivotally connected between said lever and said valve for conveying linear motion to said valve;
- and
- a spring supportably mounted about said linkage element and operatively connected to said valve for forcing said valve to a closed position in the absence of electrical power being supplied to said motor,
- wherein said motor is a DC brushless servomotor.
6 more elements
A steam turbine control system comprising:
- at least one valve for controlling the admission or extraction of steam to a turbine;
- a lever;
- a support element for pivotally supporting one end of said lever;
- an electrically operated linear actuator for pivotally supporting another end of said lever, said actuator including a linearly extendable shaft, an electric motor and a drive means operatively connected between the motor and the shaft for reciprocally positioning said shaft;
- a control means connected to said actuator for selectively supplying electrical signals and power to said motor;
- a linkage element pivotally connected between said lever and said valve for conveying linear motion to said valve;
- and
- a spring supportably mounted about said linkage element and operatively connected to said valve for forcing said valve to a closed position in the absence of electrical power being supplied to said motor,
- wherein said drive means includes a toothed wheel and a timing belt.
6 more elements
A steam turbine control system comprising:
- at least one valve for controlling the admission or extraction of steam to a turbine;
- a lever;
- a support element for pivotally supporting one end of said lever;
- an electrically operated linear actuator for pivotally supporting another end of said lever, said actuator including a linearly extendable shaft, an electric motor and a drive means operatively connected between the motor and the shaft for reciprocally positioning said shaft;
- a control means connected to said actuator for selectively supplying electrical signals and power to said motor,
- a linkage element pivotally connected between said lever and said valve for conveying linear motion to said valve;
- and
- a spring supportably mounted about said linkage element and operatively connected to said valve for forcing said valve to a closed position in the absence of electrical power being supplied to said motor,
- wherein said drive means is a gearing arrangement.
6 more elements
A steam turbine control system comprising:
- at least one valve for controlling the admission or extraction of steam to a turbine;
- a lever;
- a support element for pivotally supporting one end of said lever;
- an electrically operated linear actuator for pivotally supporting another end of said lever, said actuator including a linearly extendable shaft, an electric motor and a drive means operatively connected between the motor and the shaft for reciprocally positioning said shaft;
- a control means connected to said actuator for selectively supplying electrical signals and power to said motor;
- a linkage element pivotally connected between said lever and said valve for conveying linear motion to said valve;
- and
- a spring supportably mounted about said linkage element and operatively connected to said valve for forcing said valve to a closed position in the absence of electrical power being supplied to said motor,
- wherein said actuator includes a ball screw for providing linear motion to the actuator shaft.
6 more elements
Dependencies are inferred from the claim text.