Method for controlling multiple refrigeration units

• US 6,698,218 B2
• Filed: 03/10/2003
• Issued: 03/02/2004
• Est. Priority Date: 06/29/2001
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Goth, Gary F., Kearney, Daniel J., Makowicki, Robert, Hickey, Jody A.
• Primary Examiner(s): Tanner, Harry B.
• Application Number:
  US10/384,857
• Publication Number:
  US 20030167783A1
• Time in Patent Office: 358 Days
• Field of Search: 621/25, 621/26, 621/27, 621/29, 621/30, 621/75, 621/761, 621/763, 621/766
• US Class Current: 62/175
• CPC Class Codes: F25B 2400/06 Several compression cycles arranged in parallel
• CPC Class Codes: F25B 2500/26 characterised by the startup of the refrigeration cycle
• CPC Class Codes: F25B 2600/021 Inverters therefor
• CPC Class Codes: F25B 2600/025 by controlling speed
• CPC Class Codes: F25B 2600/2501 Bypass valves
• CPC Class Codes: F25B 2700/02 Humidity
• CPC Class Codes: F25B 49/025 Motor control arrangements
• CPC Class Codes: H05K 7/20381 Thermal management, e.g. evaporation control
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A refrigeration system for cooling a logic module includes an evaporator housing including an evaporator block in thermal communication with the logic module. The evaporator housing includes a humidity sensor for detecting a humidity within the evaporator housing. The system further comprises a controller for controlling a refrigeration unit supplying cold refrigerant to the evaporator block in response to the operating conditions of the logic module and the temperature of the evaporator block. In another aspect of the invention, two modular refrigeration units are independently operable to cool the evaporator block, and each refrigeration unit is controllable in various modes of operation including an enabled mode in which it is ready to cool the evaporator and an on mode in which it is actively cooling the evaporator. In another aspect of the invention, the evaporator block and a heater on a reverse side of the circuit board are particularly controlled during concurrent repair operations. In another aspect of the invention, faulty sensors are recognized as such and an appropriate response is made. In another aspect of the invention, the system is shut down in a manner allowing rapid access to the logic module.

Claims

1. A method for controlling a first and second refrigeration units which are configured for cooling a common evaporator block in thermal communication with a logic module, the method comprising:

selecting a mode of operation of said first and second refrigeration units from an N mode, an N+1 mode, and a switchover mode, wherein in said N mode, only one of said first and second refrigeration units are on and another of said first and second refrigeration units is not ready to turn on, in said N+1 mode, one of said first and second refrigeration units is on and another of said first and second refrigeration units is enabled and ready to turn on, and in said switchover mode, one of said first and second refrigeration units is in a shut-down sequence and another of said first and second refrigeration units is in a start-up sequence;

controlling said first and second refrigeration units in accordance with the selected mode of operation;

selecting said switchover mode when in said N+1 mode and said one refrigeration unit that is on indicates a fault.

2. The method of claim 1 further comprising scheduling periodic initiation of said switchover mode in the absence of any fault.

3. The method of claim 1, further comprising, in said switchover mode:

posting a “

switching-from”

bit to the one of said refrigeration units that is on, now referred to as a switching-from unit, said posting causing said switching-from unit to operate at maximum cooling capacity;

posting a “

switching-to”

bit to the enabled refrigeration unit, now referred to as a switching-to unit;

starting said switching-to unit, causing said switching-to unit to enter a start-up sequence;

setting a set-point of the switching-to unit to a small amount lower than a set point of the switching from unit; and

shutting down the switching-from unit.

4. The method of claim 3, further comprising:

pausing for a short time before said starting said switching-to unit and waiting at least a minute after said setting said set-point if said switchover mode is initiated as a scheduled switchover and not a recovery switchover.

5. The method of claim 1, further comprising:

periodically reading a status of said first and second refrigeration units;

upon finding a flag indicating an over-humidity condition in an evaporator housing;

reading a first and second humidity sensor values from a respective one of said first and second refrigeration units;

calculating a difference between said first and second humidity sensor values;

indicating a bad humidity sensor fault if said difference is greater than a selected miscompare limit; and

indicating a dry air breach if said difference is less than said miscompare limit.