Refrigerant cycle with operating range extension

• US 6,925,823 B2
• Filed: 10/28/2003
• Issued: 08/09/2005
• Est. Priority Date: 10/28/2003
• Status: Expired due to Fees

• Current Assignee: Carrier Corporation (Carrier Global Corporation)
• Original Assignee: Carrier Corporation (Carrier Global Corporation)
• Inventors: Taras, Michael F., Lifson, Alexander
• Primary Examiner(s): Tapolcai, William E.
• Application Number:
  US10/695,114
• Publication Number:
  US 20050086957A1
• Time in Patent Office: 651 Days
• Field of Search: 621/961, 621/962, 621/963, 622/284, 622/285, 417/18, 417/32, 417/44.1, 417/44.11
• US Class Current: 62/196.3
• CPC Class Codes: F25B 1/04 with compressor of rotary type F25B1/005, F25B1/10 take precedence
• CPC Class Codes: F25B 2400/13 Economisers
• CPC Class Codes: F25B 2500/08 Exceeding a certain temperature value in a refrigeration component or cycle
• CPC Class Codes: F25B 2600/0253 with variable speed
• CPC Class Codes: F25B 2600/0261 external to the compressor
• CPC Class Codes: F25B 2600/2509 Economiser valves
• CPC Class Codes: F25B 2700/15 Power, e.g. by voltage or current
• CPC Class Codes: F25B 2700/1931 Discharge pressures
• CPC Class Codes: F25B 2700/1933 Suction pressures
• CPC Class Codes: F25B 2700/2106 of fresh outdoor air
• 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: 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 refrigerant cycle is provided with a control that monitors system conditions such as current, voltage or temperature at a compressor motor or refrigerant state conditions at compressor ports. A protection switch on the motor is operable to stop operation of the compressor should a system condition exceed a predetermined maximum. The control monitors a system condition, and determines that the system condition indicates the protection switch may be actuated as the condition is moving toward the predetermined limit. Under such conditions, the control moves the compressor to a less loaded mode of operation such that it is less likely that the protection switch will actuate.

Claims

1. A compressor comprising:

a compressor pump unit, said compressor pump unit driven by a motor;

a protection device associated with said motor, said protection device operable to stop operation of said motor should a first system condition reach a predetermined level; and

a control for said compressor, said control monitoring a second system condition, and identifying when said second system condition indicates said first system condition is approaching said predetermined level, said control being operable to reduce a load on said compressor as said first system condition approaches said predetermined level.

2. A compressor as set forth in claim 1, wherein said control is operable to open an unloader valve on said compressor should said first system conditions approach said predetermined level.

3. A compressor as set forth in claim 1, wherein said control is operable to close an economizer valve on said compressor should said first system conditions approach said predetermined level.

4. A compressor as set forth in claim 1, wherein said motor is a variable speed motor, and said control being operable to slow a compressor motor speed should said first system condition approach said predetermined level.

5. A compressor as set forth in claim 1, wherein said second system conditions are at least one of the motor temperature, oil sump temperature, motor current, motor power, discharge temperature, suction pressure, discharge pressure, operating voltage, ambient temperature, economizer pressure or economizer temperature.

6. A compressor as set forth in claim 1, wherein at least one of said first and at least one of said second system conditions are the same.

19. A compressor as set forth in claim 1, wherein a housing enclosing said motor, and said protection device being attached to said housing.

20. A compressor as set forth in claim 19, wherein said protection device is within said housing.

7. A refrigerant cycle comprising:

a compressor having a compressor pump unit and a motor for driving said compressor pump unit, said motor being provided with a protection device operable to stop operation of said motor should a first system condition exceed a predetermined level;

a condenser downstream of said compressor;

an expansion device downstream of said condenser;

an evaporator downstream of said expansion device; and

a control for controlling at least said compressor, said control being operable to sense a second system condition and move said refrigerant cycle to a less loaded operation should said monitored second system condition indicate said first system condition may be approaching said predetermined level.

8. A refrigerant cycle as set forth in claim 7, wherein said control actuates an unloader valve for unloading said compressor pump unit and returning a compressed refrigerant back to a suction line when said monitored second system condition indicate said first system condition may be approaching said predetermined level.

9. A refrigerant cycle as set forth in claim 7, wherein said refrigerant cycle further includes an economizer cycle between said condenser and said expansion device, said economizer cycle being provided with a shut-off valve, and said control stopping operation of said economizer unit by closing said shut-off valve should said monitored second system condition indicate said first system condition may be approaching said predetermined level.

10. A refrigerant cycle as set forth in claim 7, wherein said refrigerant cycle further includes an economizer cycle between said condenser and said expansion device, said economizer cycle being provided with a shut-off valve, and said control stopping operation of said economizer unit by closing said shut-off valve should said monitored second system condition indicate said first system condition may be approaching said predetermined level, having both economizer shutoff valve and unloader bypass valve open.

11. A refrigerant cycle as set forth in claim 7, wherein said motor is a variable speed motor, and said control being operable to slow a compressor motor speed should said system conditions said monitored second system condition indicate said first system condition may be approaching said predetermined level.

12. A refrigerant cycle as set forth in claim 7, wherein said second system condition is at least one of the motor temperature, oil sump temperature, motor current, motor power, discharge temperature, suction pressure, discharge pressure, operating voltage, ambient temperature, economizer pressure or economizer temperature, and said control being operable to determine said first system condition approaching said undesirable level by monitoring said at least one of said motor temperature, oil sump temperature, motor current, motor power, discharge temperature, suction pressure, discharge pressure, operating voltage, ambient temperature, economizer pressure or economizer temperature.

13. A refrigerant cycle as set forth in claim 7, wherein said first and second system conditions are the same condition.

17. A refrigerant cycle as set forth in claim 7, wherein said compressor including a housing enclosing said motor, and said protection device being attached to said housing.

18. A refrigerant cycle as set forth in claim 17, wherein said protection device is within said housing.

14. A method of operating a refrigerant cycle comprising the steps of:

(1) monitoring a first system condition on a compressor, and providing a motor for said compressor with a shut-off switch, said shut-off switch being operable to stop operation of said compressor motor should said first system condition exceed a predetermined maximum;

(2) monitoring a second system condition and determining when said second system condition indicates said first system condition is approaching said predetermined maximum, and moving said refrigerant cycle to a lower capacity mode of operation.

15. The method of claim 14, wherein said shut-off switch is attached with a housing that also encloses said motor.

16. The method of claim 15, wherein said shut-off switch is within said housing.