Refrigeration – Processes – Separating or preventing formation of undesirables
Reexamination Certificate
1999-09-15
2001-01-23
Doerrler, William (Department: 3744)
Refrigeration
Processes
Separating or preventing formation of undesirables
C062S474000, C055S428000
Reexamination Certificate
active
06176093
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to automotive air conditioning systems and more particularly to refrigerant filters for automotive air conditioning systems.
BACKGROUND
A typical automotive air conditioning system comprises a compressor in the engine compartment for compressing refrigerant and delivering the compressed refrigerant to a condenser. The compressed refrigerant is expanded in the condenser, causing to the condenser to be chilled. Air is blown through the chilled condenser, which cools the air, and into the passenger compartment to cool the vehicle. The expanded refrigerant is then returned to the compressor where it is again compressed and the cycle repeats.
The refrigerant loop usually is coupled to the compressor through a compressor manifold having an inlet port communicating with the low pressure side or “low side” of the compressor and an outlet port communicating with the high pressure side or “high side” of the compressor. High pressure compressed refrigerant is delivered to the condenser through a hose coupled to the high pressure port and expanded refrigerant is delivered back to the compressor for recompression through a hose coupled to the low pressure port. In general, the pressure of the refrigerant on the high side can be many times the pressure of the refrigerant on the low side. It is therefore common when the engine of a vehicle is shut off that the pressure differential between the high side and low side of the compressor self equalizes. When this occurs, compressed refrigerant in the hose connected to the high side of the compressor rushes back through the reed valves and cylinder of the compressor and into hoses coupled to the low side until the pressure is equalized. The rush of refrigerant in such an equalization sometimes is heard as an audible hiss after the engine is shut off.
Compressor failure can occur for a number of reasons. One common circumstance in which failure can occur is when debris such as a small sliver of metal from a reed valve, a shard of plastic or metal from a compressor piston ring, or dirt becomes entrained in the refrigerant and circulates through the compressor. Such debris can cause gradual deterioration of compressor components or, in some cases, can result in sudden catastrophic failure. When this occurs, the compressor must be replaced. One problem often associated with replacement of a defective compressor results from the aforementioned equalizing reflux of refrigerant back into the hose coupled to the low side of the compressor during operation of the old compressor. Specifically, debris entrained in the refrigerant becomes lodged in the low side hose and is not always removed by a refrigerant flush. Accordingly, when the new compressor is installed and operated, this debris again becomes entrained within the refrigerant and destroys the new compressor in the same way as the old. In some cases, a number of compressors have been installed on a vehicle only to be destroyed in turn by debris trapped in the system and entrained in the refrigerant. A need therefore exists for a method and apparatus of preventing debris entrained in the refrigerant of an automotive air conditioning system from circulating through a newly installed compressor. It is to the provision of such a method and apparatus that the present invention is primarily directed.
SUMMARY OF THE INVENTION
Briefly described, the present invention, in one preferred embodiment thereof, comprises a method and apparatus of preventing debris entrained within the refrigerant of an automotive air conditioning system from circulating through and ruining the compressor. The apparatus comprises a small thimble shaped filter having an outer rim sized to be pressed into the inlet and/or outlet port of a compressor manifold. The device also includes a manual press adapted to press and secure the filter in place within the manifold ports. In use, when a spent air conditioning compressor is replaced with a new compressor, or as a part of standard maintenance procedures, an auto mechanic uses the press to secure a filter of this invention in place in the low pressure port and, if desired, also in the high pressure of the compressor manifold. When the manifold is reattached to the new compressor and the system charged with refrigerant, debris that may be lodged within the hoses of the system, either on the high side or low side of the compressor is trapped by the filters and prevented from recirculating through the compressor. The filter on the low side prevents debris in the low side hose from being pumped through the compressor during normal operation and the filter on the high side prevents debris from flushing back through the compressor during refrigerant equalization. As a result, the new compressor is isolated from trapped debris in the system and thus receives only filtered refrigerant. Instances of subsequent failure are therefore reduced significantly.
Thus, a method and apparatus is now provided for efficiently and economically addressing the problem of continued automotive air conditioning compressor failure as a result of debris entrained within the refrigerant. The filter is easily installed by an auto mechanic as a standard step when replacing or servicing the compressor. Once installed, the filter isolates the compressor from debris to provide only filtered refrigerant to the compressor. Subsequent compressor failure is therefore reduced and compressor life is extended. These and other features, objects, and advantages of the invention will become more apparent upon review of the detailed description set forth below taken in conjunction with the accompanying drawings, which are briefly described as follows.
REFERENCES:
patent: 979481 (1910-12-01), Hannold
patent: 2202403 (1940-05-01), Sandberg
patent: 2645099 (1953-07-01), Cumming
patent: 2702993 (1955-03-01), Harris
patent: 4376331 (1983-03-01), Clark
patent: 5492143 (1996-02-01), Cooper et al.
patent: 5586378 (1996-12-01), Smith
patent: 5630939 (1997-05-01), Bulard et al.
patent: 0594431 (1994-04-01), None
patent: 403025265 (1991-02-01), None
Potate Tommy P.
Stein Myron
AirSept, Inc.
Doerrler William
Jiang Chen-Wen
Womble Carlyle Sandridge & Rice
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