Refrigeration – Refrigeration producer – With lubricant handling means
Reexamination Certificate
2002-10-16
2003-09-02
Doerrler, William (Department: 3744)
Refrigeration
Refrigeration producer
With lubricant handling means
C062S503000, C062S513000, C062S509000
Reexamination Certificate
active
06612128
ABSTRACT:
The present invention relates to an accumulator for use in an air-conditioning system, and more particularly to a suction accumulator for use in an air-conditioning system of a motor vehicle.
Closed-loop refrigeration systems conventionally employ a compressor that is meant to draw in gaseous refrigerant at relatively low pressure and discharge hot refrigerant at relatively high pressure. The hot refrigerant condenses into liquid as it is cooled in a condenser. A small orifice or valve divides the system into high and low-pressure sides. The liquid on the high-pressure side passes through the orifice or valve and turns into a gas in the evaporator as it picks up heat. At low heat loads it is not desirable or possible to evaporate all the liquid. However, liquid refrigerant entering the compressor (known as “flooding”) causes system efficiency loss and can cause damage to the compressor. Hence it is standard practice to include an accumulator between the evaporator and the compressor to separate and store the excess liquid.
An accumulator is typically a metal can, welded together, and often has fittings attached for a switch and/or charge port. One or more inlet tubes and an outlet tube pierce the top, sides, or occasionally the bottom, or attach to fittings provided for that purpose. The refrigerant flowing into a typical accumulator will impinge upon a deflector or baffle intended to reduce the likelihood of liquid flowing out the exit.
There are many inventions of baffles and deflectors in the prior art, all designed to reduce liquid carryover (see for instance U.S. Pat. Nos. 5,787,729, 5,201,792, 5,184,479, 5,021,792, 4,768,355, 4,270,934, and 4,229,949), and the prior art includes designs that claim not to need deflectors (U.S. Pat. Nos. 5,179,844, 5,471,854). However in current standard use most accumulators use a variation of the dome (U.S. Pat. No. 4,474,035) or “dixie cup” (U.S. Pat. No. 411,005) deflector—usually because these are the simplest and most cost-effective.
All deflector designs sacrifice some effective internal volume, as the beginning of the outlet tube must be underneath the deflector. Size is critical in accumulator application, hence there is a need for a more cost-effective design that does not need a deflector.
Some prior art is concerned with reducing the turbulence of the inlet flow (U.S. Pat. No. 5,184,480) as a way to reduce liquid carryover. Other designs are more concerned with the coupling between the inner reservoir and the outlet passage (U.S. Pat. Nos. 5,660,058, 5,179,844, 4,627,247), mainly to reduce the pressure drop across the accumulator (a critical system performance parameter).
The outlet tube is a main feature of accumulators in the prior art. Compressor oil is circulated with the refrigerant in all but very special systems. In systems where compressor oil circulates with the refrigerant the oil will settle out of the stream into the bottom of the liquid reservoir area of the accumulator. Some means must be provided to return this oil to circulation. Much of the prior art is concerned with various tubes, shapes and configurations to accomplish this with the minimum amount of oil inventory left in the accumulator (U.S. Pat. Nos. 5,660,058, 5,778,697, 5,052,193, 4,354,362, 4,199,960). The typical current practice uses a J-shaped outlet tube to carry the exiting gaseous refrigerant from the top of the accumulator down to the bottom and then back up to the outlet from the accumulator. A carefully sized orifice at the bottom of the J-tube entrains the oil from the bottom of the liquid area into the stream of exiting gas. Generally the orifice has a filter around it, and the filter and oil pickup may extend into a sump formed in the bottom of the can to collect the oil.
Another key feature of the prior art is the inclusion of a desiccant in the accumulator. Some refrigerant systems are more susceptible to moisture ingression and damage than others, especially less modern systems. For many systems it is necessary to remove any moisture, and the accumulator is a convenient spot to house the desiccant. Many early designs featured desiccant cartridges and the like (U.S. Pat. Nos. 4,509,340, 4,633,679, 4,768,355, 4,331,001), but the typical modern usage is a fabric bag of some suitable shape, full of desiccant beads and secured to some inner feature of the accumulator (like the J-tube) where the beads will contact the liquid refrigerant.
Another feature typical of the prior art is an anti-siphon measure, which prevents the liquid from siphoning or flowing out of the accumulator reservoir when the system is switched off. Complicated systems have been proposed (U.S. Pat. No. 5,347,829), but the standard technique is a hole near the top of the outlet J-tube to break any siphon effect. The size of the hole is a balance between breaking any siphon and reducing the effectiveness of oil pickup.
A further feature typical of the prior art is the use of insulation placed around the outside of accumulators to modify the thermal characteristics (U.S. Pat. No. 5,701,759). This is an added expense and is only used when required to reduce flooding.
Many examples of prior art (for example U.S. Pat. No. 5,365,751) are proposed as simple, flexible designs that can be easily manufactured for many installations. Since in practice several designs are in use, it is evident that such a multi-purpose design has not been realized in the prior art. An accumulator with reduced number of parts and improved performance is required.
SUMMARY OF THE INVENTION
The invention provides an accumulator for use in air-conditioning system comprising: a hermetically sealed outer housing comprising a top, an inlet opening, a peripheral side wall, and a base; an inner liner positioned within said outer housing, said inner liner having a peripheral wall and a base which form a container to receive refrigerant delivered through said inlet opening, said inner liner being spaced from the peripheral wall and the base of said outer housing to define therewith an annular passage, said inner liner having an upper edge that is spaced from said outer housing; passage means extending around the upper edge of said inner liner and communicating the interior of said inner liner with a first upper end of said annular passage; an outlet passage opening from a second lower end of said annular passage at a location between the base of the inner liner and the base of the outer housing, said outlet passage leading to the exterior of said outer housing; the arrangement being such that vaporized refrigerant can pass through said passage means from said inner liner to the upper end of said annular passage, descend downwards through said annular passage to the opening of said outlet passage, and exit said accumulator via said outlet passage.
In one embodiment the outer housing comprises an open topped deep-drawn metal can sealed by a cap through which the inlet opening and an outlet port for the outlet passage extend. In this arrangement the upper edge of the inner liner engages the underside of the cap. The cap preferably is hermetically sealed to the top of the peripheral side wall of the outer housing and may include the inlet opening and also an outlet port for said outlet passage.
Preferably the passage means is formed by a substantially continuous gap between the upper end of the inner liner and the cap, and through this gap refrigerant in gaseous state can pass from the inner container to the annular passage where it can descend between the inner and outer walls to reach the outlet passage at the base. The annular gap is preferably baffled so that it is shielded from passage of liquid refrigerant added to the inner container through the inlet. The passage defined by the annular gap can be configured to create turbulence in the flow of refrigerant gas passing therethrough. The interior of the inner container preferably includes baffles to prevent excessive movement of the refrigerant liquid contained therein. Such a baffle may be provided in the form of a desiccant body positioned in the inner containe
Cram Kenneth Peter Luke
Dickson Timothy Russell
Nuss Matthew Bryan
Rhodes Steven Murray
Ryu Ki-Sun Jason
Baker & Daniels
Doerrler William
Halla Climate Control Canada Inc.
Shulman Mark S.
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