Refrigeration – Refrigeration producer – With refrigerant treater
Reexamination Certificate
1999-08-27
2001-01-09
Tapolcai, William E. (Department: 3744)
Refrigeration
Refrigeration producer
With refrigerant treater
C062S509000
Reexamination Certificate
active
06170287
ABSTRACT:
TECHNICAL FIELD
This invention relates to air conditioning systems in general, and specifically to an improved desiccant installation for a condenser having an attached receiver.
BACKGROUND OF THE INVENTION
Automotive air conditioning systems typically include either an accumulator canister or a receiver canister that serve as a refrigerant reservoir. An accumulator is located just before the compressor, and allow only (or substantially only) refrigerant vapor to be drawn off of the top before compression, with liquid settling at the bottom. Receiver canisters are located just after the condenser, and are intend to allow only (or substantially) only liquid refrigerant to be drawn off the bottom for the refrigerant expansion valve. A canister of either type also provides a convenient location for a container of desiccant material, usually a bag or pouch of mesh material, which absorbs water vapor from the liquid refrigerant reservoir. Either an accumulator or a receiver usually has ample room within it for the desiccant, and some kind of pre existing piping arrangement within it from which the desiccant bag can be conveniently suspended. The desiccant works better if suspended within, rather than resting free on the bottom of, the canister, and is also less subject to damage in the event that a bottom closure is later welded to the canister. A typical example of such an arrangement may be seen in U.S. Pat. No. 4,354,362, where an internal pipe provides a practical suspension post for a desiccant container.
A relatively recent trend is the attached or so called “integral” receiver, in which a reservoir canister is incorporated structurally onto, on into, the return header tank of a so called cross flow condenser design. A cross flow or “headered” condenser typically has a main pass, within which gas condenses to liquid, and a sub cooling section, within which liquid refrigerant is further cooled. An example may be seen in U.S. Pat. No. 5,537,839. The reservoir runs along the side of the return tank, and two openings or short pipes near the base of the return tank connect the main pass condenser tubes to the reservoir canister. The two openings are separate or discrete, so that all condensed refrigerant entering the return tank from the main pass is forced to flow through the upper opening and into the reservoir canister, where it forms a rising or falling reserve liquid column (depending on conditions). From the reservoir canister, liquid refrigerant can flow into the discrete lower opening and into the sub cooling section, and ultimately to the expansion valve. Generally, and preferably, the reservoir canister or tank section is no more than an empty vessel, with no internal structure suitable for suspending a desiccant cylinder or pouch. One exception may be seen in U.S. Pat. No. 5,159,821. There, refrigerant is forced centrally up into the reservoir canister in a fountain like central pipe, which also provides a convenient suspension pole for the desiccant cylinder. This is an undesirably complex and expensive structure, however.
More typically, the desiccant would simply rest where gravity would take it anyway, on the inside of the base of the reservoir canister, and this is the situation disclosed in U.S. Pat. No. 5,537,839, already noted above. This puts the desiccant container both in a position where it could be damaged by welding or brazing on a bottom closure, and in a position where it is axially coextensive with, and could clog or block, the discrete openings between the reservoir canister and the return manifold. The patent recognizes this issue by providing a separate bottom threaded plug for installing the desiccant container. There is also provided an additional internal cage like structure to confine the desiccant away from the openings. That same structure retains the desiccant so that it is in line with the openings, and therefore at least theoretically capable of blocking them. Furthermore, the cage like structure represents a potential threat to the structural integrity of the desiccant container, which is generally a cloth or plastic open mesh, especially when subjected to vibration and bouncing in operation. Both the threaded plug and the retention cage also require additional cost and manufacturing steps.
SUMMARY OF THE INVENTION
An improved desiccant installation for a condenser with an integral receiver is provided in accordance with claim
1
.
In the embodiment disclosed, a refrigerant condenser of the cross flow, headered type has an inlet header on one side, a return header on the other, and an upper or main pass section of flow tubes divided from a smaller sub cooler section by a separator located near the bottom of the return tank. Alongside the return tank, a simple cylindrical reservoir canister is structurally attached by any suitably solid and compact means. The main pass empties into the return header, which then empties into the reservoir canister through a discrete inlet just above the separator. From the reservoir canister, the liquid refrigerant empties back into the return tank through an outlet and then into the sub cooler section. There is no inner structure within the reservoir canister beyond the smooth inner wall, and it is preferably enclosed at top and bottom by a simple cap that is brazed or welded in place, giving a simple and reliable seal.
A cylindrical, open mesh container of desiccant material has a diameter that gives it a small radial clearance from the inner wall of the reservoir canister, and an axial length which, if it were allowed to rest on the bottom of the reservoir canister, would put it in line with both the inlet and outlet, and liable to block free flow through them. However, this is prevented by a standoff structure that consists of a narrow, centrally located bottom post and an upper, disk shaped base. The post is longer than the height of the inlet above the bottom end cap of the reservoir canister, and the base has an outer diameter that makes a tight interference fit with the inner wall of the reservoir canister. Therefor, the standoff structure can be used to insert the desiccant into the reservoir canister before the bottom end cap is sealed in place. The desiccant can be inserted past and beyond the inlet and outlet openings, where it will remain, at least temporarily, until after the bottom cap is welded in place, safe from heat damage. In later operation, the interference fit will help prevent vibration and damage of the desiccant tube within the canister, and even if the desiccant should sink downwards, the desiccant itself will never rest on the bottom of the canister, or block the inlet and outlet, because of the dimensions of the post. Cut outs are provided in the edge of the disk to allow liquid refrigerant to freely flow up or down past the disk.
REFERENCES:
patent: 4354362 (1982-10-01), Schumacher et al.
patent: 5146767 (1992-09-01), Kadle et al.
patent: 5159821 (1992-11-01), Nakamura
patent: 5177982 (1993-01-01), Plemens
patent: 5537839 (1996-07-01), Buck et al.
patent: 5666791 (1997-09-01), Burk
patent: 5813249 (1998-09-01), Matsuo et al.
patent: 6038884 (2000-03-01), Dabrowski
Brick Steve C.
Czajkowski Michael
Gmerek Robert Charles
Leitch Frank Joseph
Ali Mohammad M
Delphi Technologies Inc.
Griffin Patrick M.
Tapolcai William E.
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