Refrigeration – Refrigeration producer – With refrigerant treater
Reexamination Certificate
1999-07-26
2001-02-20
Doerrler, William (Department: 3744)
Refrigeration
Refrigeration producer
With refrigerant treater
C062S512000
Reexamination Certificate
active
06189333
ABSTRACT:
TECHNICAL FIELD
This invention relates to automotive air conditioning system block connectors, and especially to a refrigerant filter specifically designed to be incorporated therein.
BACKGROUND OF THE INVENTION
Automotive air conditioning systems can be divided roughly into two categories based on the type of expansion valve assembly used to expand and drop the pressure of the liquid refrigerant before it enters the evaporator. This distinction, in turn, determines the manner in which a system reserve of liquid refrigerant is stored, dried and filtered of contaminants. The subject invention relates especially to refrigerant filtering.
One common type of refrigerant expansion valve is a fixed, small diameter orifice, typically a brass tube held by a centering plug within the liquid refrigerant line. These are inexpensive, with no moving parts, but are obviously incapable of changing size to adapt to differing system demands. Such systems generally use a so called accumulator canister to store the refrigerant reserve with vapor only being pulled from the top of the canister to the compressor. Refrigerant drying desiccant bags can also be installed in the accumulator. Fixed orifice valves also provide a convenient location for a refrigerant contaminant filter screen, which can be secured to the centering plug to surround the orifice tube and filter the refrigerant as it flows through the tube.
The other basic type of expansion valve is an active, thermostatic expansion valve, in which the size of the expansion orifice can be actively varied, depending on system parameters and demands. An example may be seen in U.S. Pat. No. 4,342,421, which is often referred to as a TXV system. With a TXV system, it is most efficient if only liquid refrigerant be fed to the expansion valve, so it is convenient to store (and dry) liquid refrigerant reserve in a so called receiver-drier canister located just upstream of the valve. The more complex TXV valves, with their moving parts and small internal passages, are not convenient locations for direct incorporation of a refrigerant filter, which may be placed instead in the receiver-drier canister. As receiverdryers have become more compact, however, and sometimes integrated directly into the return header tank of the condenser, there is less room for filter installation. Moreover, a receiver canister is generally not easily opened or disconnected to allow a filter to be serviced or removed, if at all.
A recent U.S. Pat. No. 5,562,427, claims a refrigerant filter of a specific material and pore size, and discloses it in numerous possible locations, including the receiver, refrigerant line, and compressor housing. The filter design itself is not particularly amenable to handling, installation or removal, having several parts. In addition, every installation location disclosed would require some major modification to the existing air conditioning system and components.
It is generally necessary in any vehicle air conditioning system, or at least convenient, to be able to reversibly attach and detach both refrigerant lines (the liquid supply line into the evaporator, and the suction or gas line out of the evaporator) from the evaporator, both for initial installation and for later servicing or removal of the evaporator. This is conveniently done with block connections, in which two or more blocks or plates are bolted together to simultaneously join four line ends (two ends for each line) in sealed communication. In one block connector design, the line ends are solidly brazed down into bores formed in end fittings, which are then bolted together into bores in a block, as in U.S. Pat. No. 5,354,101. In another, the four line ends are instead pulled toward one another and into a central block by two side plates, which act as clamps. The line ends are not solidly fixed to the side plates, however. Instead, the side plates bear against the outside of enlarged beads on the lines, which are set back from the terminal edges of the line ends. In either case, when the block fitting is disconnected, the ends of the lines, or at least the ends of the fittings to which the lines are fixed, are visible and accessible. One design in which the filter of the invention may be conveniently installed is disclosed in U.S. Pat. No. 5,467,611, which uses a central block and side plates.
SUMMARY OF THE INVENTION
The invention provides a refrigerant filter design specially designed to be incorporated into the type of block fitting described above, with no substantial modification to the system components. The filter is simple and unitary in design, and can be installed or removed simply by making or breaking the block fitting.
In the preferred embodiment disclosed, the bottom surface of block bore and the edge of the cylindrical end of a liquid refrigerant supply line detachably clamped therein has a predetermined axial clearance. Liquid refrigerant flows through and out of the end of the liquid line, into the bore and through the central block, into a continuation of the line on the other side. The refrigerant filter, in a preferred embodiment, has a cylindrical filter screen, with a closed end upstream to the flow, and an open downstream end. The outside of the screen is supported along its length by a molded plastic, ribbed frame, which, in general, makes a close fit inside the open end of the liquid line. Specifically, a cylindrical end plug at the downstream end of the frame is inserted closely into the open line end until an annular collar abuts the line's terminal edge. The collar's thickness is close to the axial clearance noted above. In addition, in the embodiment disclosed, a resilient loop at the upstream end of the support frame plugs into a necked down portion of the line, helping to center the filter frame within the line.
Given the relative dimensions described above, the filter can be installed in the line with a simple press fit, and the annular collar acts as a stop to prevent over insertion. Next, the line is clamped into the block bore in the usual way. When refrigerant flows through the line toward the fitting, it is forced to flow through the screen, because of the close press fit with the frame plug. Since the collar thickness prevents the close fitting cylindrical plug from pulling out of the line end, flow cannot by pass the filter screen. In addition, the resilient end loop acts to prevent chatter. Removing or servicing the filter involves no more than a breaking of the block fitting and pulling the frame out at the accessible collar. No substantial structural changes to the system or any pre existing component are needed to accommodate the filter, and no installation or removal steps are necessary beyond those already built into the system.
REFERENCES:
patent: 2702993 (1955-03-01), Harris
patent: 4255940 (1981-03-01), Grahl et al.
patent: 4266408 (1981-05-01), Krause
patent: 4342421 (1982-08-01), Widdowson
patent: 4745772 (1988-05-01), Ferris
patent: 5354101 (1994-10-01), Anderson, Jr.
patent: 5467611 (1995-11-01), Cummings et al.
patent: 5562427 (1996-10-01), Mangyo et al.
patent: 6023940 (2000-02-01), Abbott et al.
patent: 6044649 (2000-04-01), Numoto et al.
patent: 6058711 (2000-05-01), Maciaszek et al.
Cummings Larry Donald
Zheng Jing
Delphi Technologies Inc.
Doerrler William
Griffin Patrick M.
Shulman Mark
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