System and method for monitoring overheat of a compressor

• US 8,539,786 B2
• Filed: 10/07/2008
• Issued: 09/24/2013
• Est. Priority Date: 10/08/2007
• Status: Active Grant

• Current Assignee: Copeland Corporation LLC (Emerson Electric Company)
• Original Assignee: Emerson Climate Technologies Incorporated (Emerson Electric Company)
• Inventors: McSweeney, Daniel L.
• Primary Examiner(s): Norman, Marc
• Assistant Examiner(s): Bradford, Jonathan
• Application Number:
  US12/247,033
• Publication Number:
  US 20090090117A1
• Time in Patent Office: 1,813 Days
• Field of Search: 622/04, 622/281, 622/25, 417/32, 417/44.1
• US Class Current: 62/228.1
• CPC Class Codes: F25B 2500/19 Calculation of parameters
• CPC Class Codes: F25B 2600/02 Compressor control
• CPC Class Codes: F25B 2600/2513 Expansion valves
• CPC Class Codes: F25B 2700/171 of the compressor
• CPC Class Codes: F25B 2700/21151 at the suction side of the compressor
• CPC Class Codes: F25B 2700/2117 of an evaporator
• CPC Class Codes: F25B 2700/21174 of the refrigerant at the inlet of the evaporator
• CPC Class Codes: F25B 2700/21175 of the refrigerant at the outlet of the evaporator
• CPC Class Codes: F25B 41/34 with the valve member being actuated by electric means, e.g. by piezoelectric actuators
• CPC Class Codes: F25B 49/005 of safety devices F25B49/02 and F25B49/04 take precedence
• CPC Class Codes: F25B 49/022 Compressor control arrangements
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A system and method for monitoring an overheat condition of a compressor is provided. A compressor connected to an evaporator. A suction sensor outputs a suction signal corresponding to a temperature of refrigerant entering the compressor. A control module is connected to the evaporator sensor and the suction sensor and determines an evaporator temperature, calculates a suction superheat temperature based on the evaporator temperature and the suction signal, and monitors an overheat condition of the compressor by comparing the suction superheat with a predetermined suction superheat threshold.

Claims

1. A system comprising:

a compressor connected to an evaporator;

a suction sensor that outputs a suction signal corresponding to a temperature of refrigerant entering said compressor;

a control module connected to said suction sensor that determines an evaporator temperature, that calculates a suction superheat temperature based on said evaporator temperature and said suction signal, that monitors an overheat condition of said compressor by comparing said suction superheat temperature with a predetermined temperature range having an upper limit temperature and a lower limit temperature, and that reduces a speed of said compressor to a reduced speed and operates said compressor at said reduced speed when it is determined that said suction superheat temperature is between said upper limit temperature and said lower limit temperature, said reduced speed being determined based on said suction superheat temperature.

2. The system of claim 1 wherein said control module stops said compressor when said suction superheat is greater than said upper limit temperature of said predetermined temperature range.

3. The system of claim 1 wherein said upper limit temperature of said predetermined temperature range is fifty degrees Fahrenheit.

4. The system of claim 1 wherein said lower limit temperature of said predetermined temperature range is thirty degrees Fahrenheit and said upper limit temperature is fifty degrees Fahrenheit.

5. The system of claim 1 wherein said control module adjusts said speed of said compressor when said control module determines that said suction superheat temperature is between said upper limit temperature and said lower limit temperature for a predetermined time period.

6. The system of claim 1, further comprising an expansion valve connected to said evaporator, wherein said control module increases an opening of said expansion valve when said suction superheat temperature is between said upper limit temperature and said lower limit temperature.

7. A system comprising:

a compressor connected to an evaporator;

an expansion valve connected to said evaporator;

a suction sensor that outputs a suction signal corresponding to a temperature of refrigerant entering said compressor;

a control module connected to said suction sensor that determines an evaporator temperature, that calculates a suction superheat temperature based on said evaporator temperature and said suction signal, that monitors an overheat condition of said compressor by comparing said suction superheat temperature with a predetermined temperature range having an upper limit temperature and a lower limit temperature, and that increases an opening of said expansion valve when said suction superheat temperature is determined to be between said upper limit temperature and said lower limit temperature, said increase of said opening of said expansion valve being determined based on said suction superheat temperature.

8. The system of claim 7, wherein said control module reduces a speed of said compressor to a reduced speed and operates said compressor at said reduced speed when said suction superheat temperature is between said upper limit temperature and said lower limit temperature.

9. The system of claim 7 wherein said upper limit temperature of said predetermined temperature range is fifty degrees Fahrenheit.

10. The system of claim 7 wherein said lower limit temperature of said predetermined temperature range is thirty degrees Fahrenheit and said upper limit temperature is fifty degrees Fahrenheit.

11. A method comprising:

determining an evaporator temperature of an evaporator connected to a compressor;

receiving a suction signal that corresponds to a temperature of refrigerant entering said compressor;

calculating a suction superheat temperature based on said evaporator temperature and said suction signal;

monitoring an overheat condition of said compressor by comparing said suction superheat with a predetermined temperature range having an upper limit temperature and a lower limit temperature; and

performing, when said suction superheat temperature is determined to be within said predetermined temperature range, at least one of;

reducing a speed of said compressor to a reduced speed determined based on said suction superheat temperature and operating said compressor at said reduced speed; and

increasing an opening of said expansion valve, said increase being based on said suction superheat temperature.

12. The method of claim 11 further comprising stopping said compressor when said suction superheat is greater than said upper limit temperature of said predetermined temperature range.

13. The method of claim 11 wherein said upper limit temperature of said predetermined temperature range is fifty degrees Fahrenheit.

14. The method of claim 11 wherein said lower limit temperature of said predetermined temperature range is thirty degrees Fahrenheit and said upper limit temperature is fifty degrees Fahrenheit.

15. The method of claim 11 further comprising reducing said speed of said compressor when said suction superheat temperature is between said upper limit temperature and said lower limit temperature for a predetermined time period.