Monitoring the health of a cryocooler

• US 8,794,016 B2
• Filed: 08/13/2009
• Issued: 08/05/2014
• Est. Priority Date: 08/14/2008
• Status: Expired due to Fees

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Ogden, Robert R., Barton, Paul H., Heer, Bernard D., Ross, Bradley A., Kirkconnell, Carl S., Beshears, Raymond R.
• Primary Examiner(s): Jules, Frantz
• Assistant Examiner(s): DUKE, EMMANUEL E
• Application Number:
  US12/540,576
• Publication Number:
  US 20100037639A1
• Time in Patent Office: 1,818 Days
• Field of Search: 62/6, 62125-127, 621/29, 626/00, 374/5
• US Class Current: 62/127
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence
• CPC Class Codes: F25B 9/00 Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point

Abstract

According to certain embodiments, monitoring the health of a cryocooler includes monitoring physical properties of the cryocooler to obtain failure precursor parameters that indicate cryocooler health. A health fingerprint of the cryocooler is accessed. The health fingerprint associates the failure precursor parameters with a health level of the cryocooler. The health of the cryocooler is estimated in accordance with the health level.

Claims

1. A method comprising:

monitoring a plurality of physical properties of a cryocooler to obtain one or more failure precursor parameters, the one or more failure precursor parameters indicating a health of the cryocooler, wherein monitoring the plurality of physical properties comprises monitoring available power headroom and slopes of a power versus time curve at different environmental temperatures wherein,

power is an average power used to maintain the cryocooler at steady state over time at a given environmental temperature, and

power headroom is the difference between the average power required at steady state at a given environmental temperature and available maximum power;

accessing a health fingerprint of the cryocooler, the health fingerprint generated from collected parameters of a sample cryocooler similar to the cryocooler, and the health fingerprint associating the one or more failure precursor parameters with a health level of the cryocooler; and

estimating the health of the cryocooler in accordance with the health level.

2. The method of claim 1, further comprising:

determining that a failure precursor parameter has satisfied a threshold; and

sending a notification in response to the determination.

3. The method of claim 1,

wherein estimating the health of the cryocooler further comprises:

determining a time at which the power reaches a maximum available cryocooler power, the time representing an end of useful life; and

estimating a remaining useful life according to the end of useful life.

4. The method of claim 1, wherein monitoring the plurality of physical properties further comprises:

monitoring a power headroom of a steady state of the cryocooler; and

wherein estimating the health of the cryocooler further comprises;

calculating a rate of decrease of the power headroom; and

determining a particular remaining useful life that corresponds to the rate of decrease.

5. The method of claim 1, wherein monitoring the plurality of physical properties further comprises:

monitoring one or more piston knocking indicators to monitor piston knocking of the cryocooler, the one or more piston knocking indicators comprising sounds or vibrations made by the cryocooler; and

wherein estimating the health of the cryocooler further comprises;

determining that the one or more piston knocking indicators have deviated from one or more expected values.

6. The method of claim 1, wherein

monitoring the plurality of physical properties further comprises monitoring temperature at one or more locations of the cryocooler;

and

estimating the health of the cryocooler further comprises determining that the temperature has satisfied a threshold.

7. The method of claim 1, wherein monitoring the plurality of physical properties further comprises monitoring a waveform of input current or voltage;

and

wherein estimating the health of the cryocooler further comprises determining that the waveform deviates from an expected waveform.

8. The method of claim 1, wherein estimating the health of the cryocooler further comprises:

receiving one or more environmental condition values; and

estimating the health of the cryocooler at the one or more environmental condition values.

9. The method of claim 1, wherein estimating the health of the cryocooler further comprises:

receiving a future time value; and

predicting the health of the cryocooler at the future time value.

10. The method of claim 1, further comprising:

predicting a future time when a failure event may occur; and

sending a predicted failure notification in response to the prediction.

11. The method of claim 1, further comprising generating the health fingerprint from collected parameters of a sample cryocooler similar to the cryocooler by:

monitoring a plurality of physical properties of the sample cryocooler to obtain one or more failure precursor parameters, the one or more failure precursor parameters indicating a health of the sample cryocooler; and

associating the one or more failure precursor parameters from the sample cryocooler with a health level of the sample cryocooler and any other cryocooler similar to the sample cryocooler.

12. An apparatus comprising:

a computer readable medium configured to store logic, the logic when executed by a processor configured to;

monitor a plurality of physical properties of a cryocooler to obtain one or more failure precursor parameters, the failure precursor parameter indicating health of the cryocooler, wherein monitoring the plurality of physical properties comprises monitoring available power headroom and slopes of a power versus time curve at different environmental temperatures wherein,

power is an average power used to maintain the cryocooler at steady state over time at a given environmental temperature, and

power headroom is the difference between the average power required at steady state at a given environmental temperature and available maximum power;

access a health fingerprint of the cryocooler, the health fingerprint generated from collected parameters of a sample cryocooler similar to the cryocooler, and the health fingerprint associating the one or more failure precursor parameters with a health level of the cryocooler; and

estimate the health of the cryocooler in accordance with the health level.

13. The apparatus of claim 12, wherein the logic, when executed by the processor is further configured to:

determine that the failure precursor parameter has satisfied a threshold; and

send a notification in response to the determination.

14. The apparatus of claim 12, wherein the logic, when executed by the processor is further configured to:

estimate the health of the cryocooler by determining a time at which the power reaches a maximum available cryocooler power, the time representing an end of useful life; and

estimating a remaining useful life according to the end of useful life.

15. The apparatus of claim 12, wherein the logic, when executed by the processor is further configured to:

monitor the plurality of physical properties by monitoring a power headroom of a steady state of the cryocooler; and

estimate the health of the cryocooler by;

calculating a rate of decrease of the power headroom; and

determining a particular remaining useful life that corresponds to the rate of decrease.

16. The apparatus of claim 12, wherein the logic, when executed by the processor is further configured to:

monitor the plurality of physical properties by monitoring one or more piston knocking indicators to monitor piston knocking of the cryocooler, the one or more piston knocking indicators comprising sounds or vibrations made by the cryocooler; and

estimate the health of the cryocooler by determining that the one or more piston knocking indicators have deviated from one or more expected values.

17. The apparatus of claim 12, wherein the logic, when executed by the processor is further configured to:

monitor the plurality of physical properties by monitoring temperature at one or more locations of the cryocooler; and

estimate the health of the cryocooler by determining that the temperature has satisfied a threshold.

18. The apparatus of claim 12, wherein the logic, when executed by the processor is further configured to:

monitor the plurality of physical properties by monitoring a waveform of input current or voltage; and

estimate the health of the cryocooler by determining that the waveform deviates from an expected waveform.

19. The apparatus of claim 12, wherein the logic, when executed by the processor is further configured to estimate the health of the cryocooler by:

receiving one or more environmental condition values; and

estimating the health of the cryocooler at the one or more environmental condition values.

20. The apparatus of claim 12, wherein the logic, when executed by the processor is further configured to estimate the health of the cryocooler by:

receiving a future time value; and

predicting the health of the cryocooler at the future time value.

21. The apparatus of claim 12, wherein the logic, when executed by the processor is further configured to:

predict a future time when a failure event may occur; and

send a predicted failure notification in response to the prediction.

22. The apparatus of claim 12, the logic, when executed by the processor is further configured to generate the health fingerprint from collected parameters of a sample cryocooler similar to the cryocooler by:

monitoring a plurality of physical properties of the sample cryocooler to obtain one or more failure precursor parameters, the one or more failure precursor parameters indicating a health of the sample cryocooler; and

associating the one or more failure precursor parameters from the sample cryocooler with a health level of the sample cryocooler and any other cryocooler similar to the sample cryocooler.

23. An apparatus comprising:

a computer readable medium configured to store logic such that when executed by a processor is configured to;

monitor a plurality of physical properties of a cryocooler to obtain one or more failure precursor parameters, the one or more failure precursor parameters indicating health of the cryocooler, the one or more failure precursor parameters including at least one of an actual measured value or a value derived from the measured value, wherein monitoring the plurality of physical properties comprises monitoring available power headroom and slopes of power versus time curve at different environmental temperatures wherein,

power is an average power used to maintain the cryocooler at steady state over time at a given environmental temperature and

power headroom is the difference between the average power required at steady state at a given environmental temperature and available maximum power;

when the cryocooler is a sample cryocooler, generate a health fingerprint of the sample cryocooler and any other cryocooler similar to the sample cryocooler from the one or more failure precursor parameters of the sample cryocooler, wherein the health fingerprint associates one or more failure precursor parameters from the sample cryocooler with a health level of the sample cryocooler and any other cryocooler similar to the sample cryocooler;

when the cryocooler is not a sample cryocooler, access the health fingerprint of the cryocooler, the health fingerprint generated from collected parameters of a sample cryocooler similar to the cryocooler, the health fingerprint associating the one or more failure precursor parameters from the cryocooler with a health level of the cryocooler;

estimate the health of the other cryocooler in accordance with the health level;

determine that a failure precursor parameter of the one or more other failure precursor parameters has satisfied a threshold; and

send a notification in response to the determination.

24. The apparatus of claim 23, wherein the logic, when executed by the processor is further configured to:

estimate the health of the other cryocooler by;

determining a time at which the power reaches a maximum available cryocooler power, the time representing an end of useful life; and

estimating a remaining useful life according to the end of useful life.

25. The apparatus of claim 23, wherein the logic, when executed by the processor is further configured to:

monitor the plurality of physical properties by;

monitoring a power headroom of a steady state of the cryocooler; and

estimate the health of the other cryocooler by calculating a rate of decrease of the power headroom; and

determining a particular remaining useful life that corresponds to the rate of decrease.

26. The apparatus of claim 23, wherein the logic, when executed by the processor is further configured to:

monitor the plurality of physical properties by monitoring one or more piston knocking indicators to monitor piston knocking of the cryocooler, the one or more piston knocking indicators comprising sounds or vibrations made by the cryocooler; and

estimate the health of the other cryocooler by determining that the one or more piston knocking indicators have deviated from one or more expected values.

27. The apparatus of claim 23, wherein the logic, when executed by the processor is further configured to:

monitor the plurality of physical properties by monitoring temperature at one or more locations of the cryocooler; and

estimate the health of the other cryocooler by determining that the temperature has satisfied a threshold.

28. The apparatus of claim 23, wherein the logic, when executed by the processor is further configured to:

monitor the plurality of physical properties by monitoring a waveform of input current or voltage; and

estimate the health of the other cryocooler by determining that the waveform deviates from an expected waveform.