Refrigeration – With indicator or tester – Operatively correlated with automatic control
Reexamination Certificate
1999-01-19
2001-01-23
Tanner, Harry B. (Department: 3744)
Refrigeration
With indicator or tester
Operatively correlated with automatic control
C062S127000, C062S196200, C062S228500
Reexamination Certificate
active
06176095
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the field of refrigeration systems for heating or cooling a controlled environment, and in particular to the compressor of the refrigeration system, and more particularly to a device or method for determining the operational condition of a compressor.
BACKGROUND OF THE INVENTION
Refrigeration systems are used in many applications for heating and cooling a controlled environment, including a cargo box on a transport truck, train, ship or plane. The refrigeration system has many components including a condenser, an evaporator, and a compressor. The compressor typically includes a plurality of cylinder banks, where at least one of the cylinder banks has an unloader for loading and unloading the cylinder bank. Before transporting cargo, it is desirable to determine whether the refrigeration system is in an operational condition.
There have been some attempts to use a pretrip device to determine the operational condition of the refrigeration system prior to transportation. One such device to Hanson et al., U.S. Pat. No. 5,172,561, includes a pretrip device which determines the operational condition of the refrigeration system as a function of temperature change. When the box is humid, the refrigeration system will remove moisture from the air prior to changing the temperature. As a result, this device has a propensity for false alarms. Further, this device does not have the capability to isolate the particular problem within the refrigeration system.
When an alarm is signaled, the refrigeration system must be taken out of service and be inspected for problems, which takes time and costs money. When the alarm is false, it takes longer to service because there are no identifiable problems.
Further, the pretrip device of Hanson et al. does not have the capability to identify a particular problem with or within a compressor. As a result, the entire refrigeration system must be tested by a technician in order to isolate and repair a problem within a compressor. Due to the mechanical complexity of a compressor including many components, troubleshooting a compressor results in a significant loss of time and money.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to overcome the limitations of the prior art.
It is a further object of the present invention to provide a pretrip device operating a pretrip subroutine for determining the operational condition of a compressor of a refrigeration system.
It is another object of the present invention to provide a pretrip device operating a pretrip subroutine to determine the operational condition of an unloader of a compressor prior to placing the compressor in a cooling or heating/defrost mode of operation.
It is yet another object of the present invention to provide a pretrip device operating a pretrip subroutine to signal an alarm when an unloader is in a non-operational condition.
It is still another object of the present invention to provide a pretrip device operating a pretrip subroutine that results in a minimal number of false alarms.
It is a further object of the present invention to provide a pretrip device operating a pretrip subroutine to determine the operational condition of an individual cylinder bank of a compressor. It is another object of the present invention to provide a pretrip device operating a pretrip subroutine to signal an alarm when a problem exists within a cylinder bank of a compressor.
These and other objects are provided for by a device for testing the operational performance of a compressor, wherein said compressor includes at least one cylinder bank and at least one unloader, said at least one cylinder bank being connected to said at least one unloader, said at least one unloader for loading and unloading said at least one cylinder bank, said device comprising:
pressure sensing means for sensing a pressure differential indicator of said compressor; and
determining means responsive to said pressure sensing means for determining the operational state of said compressor based on said pressure differential indicator.
The determining means of the device is responsive to the pressure differential indicator so that said determining means provides an operational state of said at least one unloader.
Further, the determining means is responsive to the pressure differential indicator so that said determining means provides an operational state of a first and second cylinder bank.
Further objects, features and advantages of the present invention will become apparent when reading the Detailed Description of the Invention in conjunction with the drawings.
REFERENCES:
patent: 2401827 (1946-06-01), Heitchue
patent: 3110160 (1963-11-01), Miner
patent: 4848096 (1989-07-01), Funahashi et al.
patent: 5140825 (1992-08-01), Hanson et al.
patent: 5172561 (1992-12-01), Hanson et al.
patent: 5209076 (1993-05-01), Kauffman et al.
Carrier Corporation
Tanner Harry B.
Wall Marjama & Bilinski
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