Rate of change detector for refrigerant floodback

• US 6,578,373 B1
• Filed: 06/11/2001
• Issued: 06/17/2003
• Est. Priority Date: 09/21/2000
• Status: Expired due to Fees

• Current Assignee: Concept Technology, Inc.
• Original Assignee: William J. Barbier
• Inventors: Barbier, William J.
• Primary Examiner(s): WAYNER, WILLIAM E
• Application Number:
  US09/878,571
• Time in Patent Office: 736 Days
• Field of Search: 622/27, 621/26, 621/29, 621/58, 236/78.D, 340/589, 340/870, 340/17
• US Class Current: 62/158
• CPC Class Codes: F25B 2500/28 Means for preventing liquid refrigerant entering into the compressor
• CPC Class Codes: F25B 2700/1933 Suction pressures
• CPC Class Codes: F25B 2700/21151 at the suction side of the compressor
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence
• CPC Class Codes: G05D 23/1917 using digital means

Abstract

A floodback detector for refrigerant systems employing any of: minimum suction temperature, temperature rate of change and duration thereof; minimum superheat, superheat rate of change and duration thereof.

Claims

1. A floodback detector for a refrigeration system comprising:

means for establishing a maximum rate of suction temperature change,

means for observing consecutive suction temperatures at regular time intervals;

means for calculating a suction temperature rate of change;

means for comparing the calculated rate of suction temperature change with the established maximum rate of suction temperature change;

means for establishing a minimum allowable suction temperature; and

means for stopping the compressor on the condition that the calculated rate of change is equal to or greater than the established rate of change, and

means for automatically restarting the compressor after the observed suction temperature has risen to a temperature equal to or higher than the minimum allowable suction temperature plus 15 F.

14. A floodback detector for a refrigeration system as recited in claim 1 further providing that the alarm event includes means for stopping and automatically restarting the compressor.

2. A floodback detector for a refrigeration system comprising:

means for establishing a maximum rate of suction temperature change;

means for observing consecutive suction temperatures at regular time intervals;

means for calculating a suction temperature rate of change;

means for comparing the calculated rate of suction temperature change with the established maximum rate of change;

means for establishing a compressor protective action on the violation condition that the calculated rate of change is equal to or greater than the established rate of change.

3. A floodback detector for a refrigeration system as recited in claim 2 where the compressor protective action comprises means for stopping and automatically restarting the compressor.

4. A floodback detector for a refrigeration system as recited in claim 2, further providing means for establishing a minimum allowable suction temperature;

where the compressor protective action comprises means for stopping and automatically restarting the compressor after the observed suction temperature has risen to a temperature equal to or higher than the minimum allowable suction temperature plus 15 F.

5. A floodback detector as recited in claim 2 further providing first timer means having a first reset period and where the compressor protective action comprises:

means for stopping the compressor and simultaneously starting first timer means and means for automatic compressor restart on the elapse of the first reset period.

6. A floodback detector for a refrigeration system as recited in claim 3 further providing second timer means having a reset period;

and further providing a manual compressor restart mode;

means for initiating second timer operation substantially simultaneously with stopping the compressor on a first violation, and

means for stopping the compressor in the manual restart mode on the condition of reoccurrence of the compressor stoppage before the end of the reset period of the second timer means.

7. A floodback detector for a refrigeration system having a compressor, an evaporator and suction conduit means for refrigerant flow between the evaporator and the compressor, said flow including possible refrigerant liquid floodback to the compressor, the suction conduit means being subject to periodic changes of conditions selected from the group consisting of temperature and superheat;

said refrigerant floodback being accompanied by changes in a selected condition occuring at a greater rate than a predetermined maximum rate;

said detector comprising;

means for establishing and storing a maximum rate of change for a condition,

means for periodically measuring the condition, means for determining a rate of change of the condition from at least two of the periodic measurements, and means for generating an alarm event on the determination of a rate of change of the condition in excess of the predetermined maximum rate.

8. A floodback detector for a refrigeration system as recited in claim 7 where the condition is temperature.

9. A floodback detector for a refrigeration system as recited in claim 8 further providing that the alarm event includes means for stopping and automatically restarting the compressor.

10. A floodback detector as recited in claim 9 further providing that the means for automatically restarting the compressor includes first timer means having a first reset period, said timer means being arranged to start timing on the occurance of the alarm event when the compressor stops and to restart the compressor on elapse of the first reset period.

11. A floodback detector as recited in claim 10 further providing second timer means having a reset period and further providing a manual restart mode and means for starting the compressor in the manual restart mode on the condition of recurrance of the compressor stoppage before the end of the reset period of the second timer means.

12. A floodback detector as recited in claim 11 further providing counter means for counting the number of alarm events, and means for starting the compressor in the manual restart mode on the condition of more than two alarm events occurring before the end of the reset period of the second timer means.

13. A floodback detector as recited in claim 7 where the condition is superheat.

15. A floodback detector as recited in claim 9 further providing that the means for automatically restarting the compressor includes first timer means having a first reset period, said timer means being arranged to start timing on the occurance of the alarm event when the compressor stops and to restart the compressor on elapse of the first reset period.

16. A floodback detector as recited in claim 10 further providing second timer means having a reset period and further providing a manual restart mode and means for starting the compressor in the manual restart mode on the condition of recurrance of the compressor stoppage before the end of the reset period of the second timer means.

17. A floodback detector as recited in claim 11 further providing counter means for counting the number of alarm events, and means for starting the compressor in the manual restart mode on the condition of more than two alarm events occurring before the end of the reset period of the second timer means.

18. A floodback detector for a refrigeration system comprising:

means for establishing a maximum rate of suction temperature change,

means for observing consecutive suction temperatures at regular time intervals;

means for calculating a suction temperature rate of change;

means for comparing the calculated rate of suction temperature change with the established maximum rate of change;

means for stopping the compressor on the condition that the calculated rate of change is equal to or greater than the established rate of change, and further providing means for automatically restarting the compressor said restarting means comprising;

first timer means for measuring a first preset time interval,

means for starting the first timer means simultaneously with the actuation of the compressor stopping means, and

means for restarting the compressor on the elapse of said first preset time interval.

19. A floodback detector for a refrigeration system as recited in claim 18 comprising:

second timer means having a second reset period and further providing a manual compressor restart mode;

means for initiating second timer means operation substantially simultaneously with stopping the compressor on a first violation, and

means for stopping the compressor in the manual restart mode on the condition of one reoccurrence of the compressor stoppage before the end of the second reset period.

20. A floodback detector as recited in claim 19 further providing,

means for establishing a maximum number of compressor stoppage events and,

means for counting the number of compressor stoppage events occurring during the second reset period, and

means for stopping the compressor in the manual restart mode on the occurrence of a greater number of stoppage events than the maximum.

21. A floodback detector for a refrigeration system comprising:

means for establishing a maximum cooling rate of suction temperature change;

means for observing consecutive suction temperatures at regular time intervals;

means for calculating a suction temperature cooling rate of change;

means for comparing the calculated cooling rate of suction temperature change with the established maximum cooling rate of change;

means for stopping the compressor when the calculated cooling rate of suction temperature change is equal to or greater than said established maximum cooling rate of suction temperature change.

22. A floodback detector for a refrigeration system as recited in claim 21 further comprising:

means for establishing a minimum suction temperature and

means for restarting the compressor on the condition that the temperature of the suction line has risen to a temperature equal to the minimum suction temperature plus 15 degrees.

23. A floodback detector for a refrigeration system having a compressor, an evaporator, and suction conduit means for refrigerant flow between the evaporator and the compressor, said flow including possible refrigerant liquid floodback to the compressor, said refrigerant floodback being accompanied by reductions in the temperature of said suction conduit means occurring at a greater rate than a predetermined maximum rate, said detector comprising:

means for establishing and storing a maximum cooling rate of suction conduit means temperature change,

means for periodically measuring the temperature of said suction conduit means,

means for determining a cooling temperature rate of change of said suction conduit means from at least two of the periodic measurements, and

means for stopping the compressor on the determination of a cooling temperature rate of change of the suction conduit means in excess of the predetermined maximum cooling temperature rate of change of said suction conduit means.

24. A floodback detector as recited in claim 23 further providing, means for automatically restarting the compressor comprising:

first timer means having a first reset period, said first timer means being arranged to start timing on the occurrence of the alarm event when the compressor stops and to restart the compressor on elapse of the first reset period.

25. A floodback detector as recited in claim 24, further providing:

second timer means having a second reset period and further providing a manual restart mode and

means for stopping the compressor in the manual restart mode on the condition of recurrence of the compressor stoppage before the end of the reset period of the second timer means.

26. A floodback detector as recited in claim 25 further providing

counter means for counting the number of compressor stoppages, and

means for stopping the compressor in the manual restart mode on the condition of more than two compressor stoppages occurring before the end of the reset period of the second timer means.