The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 16, 1991
Filed:
Dec. 04, 1989
Wilfred J Gully, Torrance, CA (US);
Paul M Okada, Westminster, CA (US);
Other;
Abstract
A direct current powered, linear resonant cryocooler having a compressor in which the piston is reciprocated by a linear motor at substantially resonant frequency and the length of stroke of the piston is varied as a direct function of cryocooler temperature. There are two control loops, a temperature control loop and a voltage control loop which is independent of the temperature control loop. In the temperature control loop, temperature is sensed at the cryocooler or expander and the temperature signal is compared with a reference temperature signal to produce a temperature error signal or voltage. The voltage control loop controls motor voltage. As input to the voltage control loop, the linear motor voltage is fed back and compared with the temperature error voltage V.sub.TE to produce a voltage level signal V.sub.L in the input of the voltage control loop, representative of the correction required to obtain and then to maintain the cryocooler temperature represented by the reference temperature voltage. Either a pulse width modulated, variable amplitude sine wave signal or a constant duty cycle, pulse width modulated, square wave signal powers the linear motor.