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US 2011/0030392 A1Published application
Expander speed control
AssigneeSumitomo (SHI) Cryogenics of America, Inc.
InventorsJohn Borchers, Gary Ash, Relph C. LongsWorth
Life of this patent
Estimating the term…
Abstract
Apparatus and method for controlling the speed for a GM type expander includes relays that interrupt power when the current in the line is zero. The speed controller apparatus limits the maximum speed providing the expander with sufficient gas to meet its cooling requirements.
Claims5
A method for a controlling the operating speed of at least one GM type expander that is driven by an AC synchronous motor comprising:
- interrupting power when the current in the line is zero by relays.
A cryopump comprising:
- at least one GM type expander driven by an AC synchronous motor;
- a controlling means that limits the maximum speed so that each expander has sufficient gas to meet its cooling requirements;
- and wherein said controlling means interrupts power when the current in the line is zero by relays.
Dependencies are inferred from the claim text.