Low refrigerant charge detection using a combined pressure/temperature sensor

• US 5,586,445 A
• Filed: 09/30/1994
• Issued: 12/24/1996
• Est. Priority Date: 09/30/1994
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Bessler, Warren F.
• Primary Examiner(s): Tanner, Harry B.
• Application Number:
  US08/315,804
• Time in Patent Office: 816 Days
• Field of Search: 62/126, 62/129, 62/127, 62/208, 62/209, 62/203, 62/214
• US Class Current: 62/126
• CPC Class Codes: F25B 2700/1931 Discharge pressures
• CPC Class Codes: F25B 2700/21152 at the discharge side of the compressor
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence
• CPC Class Codes: G01F 23/14 by measurement of pressure
• CPC Class Codes: G01F 23/22 by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water involving the use of floats G01F23/30

Abstract

Low refrigerant charge in a refrigeration system is detected by monitoring the compressor discharge pressure and temperature. This monitoring is accomplished with a combined pressure/temperature sensor located at or near the compressor outlet. The sensor output signals are fed to a controller which produces a low charge signal whenever a combination of high discharge temperature and a low discharge pressure is detected. The controller can optionally receive input of additional operating characteristics of the refrigeration system to provide a more accurate low charge signal. The controller is connected to an indicator and/or the compressor so that the low charge signal activates the indicator and/or deactivates the compressor.

Claims

1. A low refrigerant charge detecting system for a refrigeration system having a compressor, said low refrigerant charge detecting system comprising:

a combined pressure and temperature sensor located near the discharge of said compressor; and

a controller coupled to said combined pressure and temperature sensor wherein said controller produces a low charge signal in response to a high discharge temperature and a low discharge pressure is detected by said pressure and temperature sensor from said compressor.

2. The low refrigerant charge detecting system of claim 1 wherein said controller is coupled to said compressor so that said low charge signal deactivates said compressor.

3. The low refrigerant charge detecting system of claim 1 further comprising an indicator coupled to said controller so that said low charge signal activates said indicator.

4. The low refrigerant charge detecting system of claim 1 wherein said controller receives input of additional operating characteristics of the refrigeration system.

5. A method for detecting low refrigerant charge in a refrigeration system having a compressor, said method comprising the steps of:

monitoring the discharge temperature and the discharge pressure of said compressor; and

producing a low charge signal whenever there is a high discharge temperature and a low discharge pressure.

6. The method of claim 5 wherein said low charge signal deactivates said compressor.

7. The method of claim 5 wherein said low charge signal activates an indicator.

8. The method of claim 5 further comprising the step of monitoring additional operating characteristics of the refrigeration system.

9. A method for detecting low refrigerant charge in a refrigeration system having a compressor, said method comprising the steps of:

monitoring the discharge temperature and the discharge pressure of said compressor;

determining compressor load, compressor cycle rate and temperature cycle rate from said compressor discharge temperature and said compressor discharge pressure;

predicting an expected compressor discharge temperature from said compressor load, compressor cycle rate and temperature cycle rate; and

producing a low charge signal whenever the actual compressor discharge temperature exceeds said expected compressor discharge temperature.

10. The method of claim 9 further comprising the step of monitoring additional operating characteristics of the refrigeration system.