Electromechanical cryocooler

• US 5,582,013 A
• Filed: 05/09/1995
• Issued: 12/10/1996
• Est. Priority Date: 05/09/1995
• Status: Expired due to Term

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Neufeld, Kenneth W.
• Primary Examiner(s): Capossela, Ronald C.
• Application Number:
  US08/438,219
• Time in Patent Office: 581 Days
• Field of Search: 62/6, 60/520
• US Class Current: 62/6
• CPC Class Codes: F16F 15/02 Suppression of vibrations of non-rotating, e.g. reciprocating systems; Suppression of vibrations of rotating systems by use of members not moving with the rotating systems F16F15/005 takes precedence ; layered products B32B; suppression of vibration in ships B63; relieving load on bearings, using magnetic means F16C39/06
• CPC Class Codes: F25B 2309/001 with a linear configuration or a linear motor
• CPC Class Codes: F25B 2500/13 Vibrations
• CPC Class Codes: F25B 9/14 characterised by the cycle used, e.g. Stirling cycle
• CPC Class Codes: G05D 19/02 characterised by the use of electric means

Abstract

An electromechanical cryocooler is disclosed for substantially reducing vibrations caused by the cooler. The direction of the force of the vibrations is measured and a counterforce sufficient to substantially reduce this vibration is calculated and generated. The counterforce is 180° out of phase with the direction of the force of the vibrations.

Claims

1. An electromechanical cooler for cooling an instrument while generating minimal vibration, comprising:

a compressor, wherein the compressor vibrates during operation of the cooler;

a counterbalance mechanically coupled to the compressor;

measuring means for measuring the direction of the external mechanical forces of vibrations of the compressor and generating a corresponding signal; and

control means for interpreting the signal generated by the measuring means and generating a drive signal to move the counterbalance with counterforces 180°

out of phase with the vibrations to reduce the vibrations at a fundamental frequency and associated harmonics.

2. The electromechanical cooler as recited in claim 1, wherein the compressor comprises a linear motor and a piston.

3. The electromechanical cooler as recited in claim 1, wherein the counterbalance and the compressor occupy antipodal parts of a single axis so that a space is interposed along the axis between the compressor and the counterbalance.

4. The electromechanical cooler as recited in claim 3, wherein the counterbalance and the compressor are aligned with each other along a horizontal axis.

5. The electromechanical cooler as recited in claim 1, wherein the measuring means is connected to the counterbalance.

6. The electromechanical cooler as recited in claim 1, wherein the control means comprises an electronic system that receives and interprets the signals from the measuring means and generates a sinusoidal drive signal to initiate compressor and counterbalance movement.

7. The electromechanical cooler as recited in claim 6, wherein the movement of the counterbalance produces ramping up in power of the counterbalance as the compressor ramps up in power.

8. The electromechanical cooler as recited in claim 6, wherein the electronic system periodically calculates the vibration of the compressor.

9. The electromechanical cooler as recited in claim 6, wherein the control means further comprises an H-bridge driver with pulse width modulation for inputting the sinusoidal drive signal.

10. The electromechanical cooler as recited in claim 1, wherein the measuring means is selected from the group consisting of lasers, strain gauges, accelerometers, and piezoelectric devices.

11. The electromechanical cooler as recited in claim 1, wherein the instrument is selected from the group consisting of a detector, a spectrometer, and a gas chromatograph.

12. The electromechanical cooler as recited in claim 1, wherein the cooler is substantially insensitive to axis orientation.

13. The electromechanical cooler as recited in claim 1, further comprising temperature control means for reducing input power after the instrument has reached a predetermined operating temperature.

14. The electromechanical cooler as recited in claim 1, further comprising safeguard means for shutting down the cooler to prevent any damage to individual components from mechanical or electrical defects.

15. An electromechanical cryocooler for cooling a gamma ray detector while generating minimal vibration, comprising:

a compressor, wherein the compressor vibrates during operation of the cooler;

a counterbalance mechanically coupled to the compressor;

measuring means for measuring the direction of the external mechanical forces of vibrations of the compressor and for generating a corresponding signal; and

control means for receiving and interpreting the signal from the measuring means, and initiating movement of the counterbalance with counterforces 180°

out of phase with the compressor'"'"'s vibrational force to reduce the vibrations at a fundamental frequency and associated harmonics.

16. An electromechanical cooler for cooling an instrument while generating minimal vibration, comprising:

a compressor, wherein the compressor vibrates during operation of the cooler;

a counterbalance mechanically coupled to the compressor;

measuring means for measuring the direction of the external mechanical forces of vibrations of the compressor and generating a corresponding signal, wherein the measuring means measures frequency, magnitude, and phase angles of the vibrations; and

control means for interpreting the signal generated by the measuring means and generating a drive signal to move the counterbalance with counterforces 180°

out of phase with the phase angles of the vibrations to reduce the vibrations at a fundamental frequency and associated harmonics.