Refrigeration – Processes – Separating or preventing formation of undesirables
Reexamination Certificate
2001-08-29
2002-08-27
Jiang, Chen-Wen (Department: 3744)
Refrigeration
Processes
Separating or preventing formation of undesirables
C062S474000, C062S503000
Reexamination Certificate
active
06438972
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to refrigerant pressure vessels for use in refrigeration systems, such as a receiver-dryer or an accumulatordehy-drator. More specifically, this invention relates to an automotive accumulator assembly that has a unique outlet tube and to a related method of manufacturing the accumulator assembly to achieve a more tolerant product design and assembly process.
2. Description of the Related Art
The use of pressure vessels in refrigeration systems, particularly automotive air-conditioning systems, is very well known. A typical refrigeration system includes a compressor, a condenser, an expansion device, an evaporator, and conduits therebetween. Additionally, an accumulator-dehydrator or a receiver-dryer unit is also usually included as will be described below. The compressor compresses liquid refrigerant into high-pressure, high-temperature vapor or gas refrigerant (e.g. 200 PSI at 150° F.) and outputs the gas refrigerant as a superheated vapor through a high-pressure section of the conduit to the condenser. The condenser is typically constructed in the fashion of a tube-and-fin type heat exchanger. Within the condenser, the heat of the gas refrigerant flows through tubes and is released to or absorbed by outside air flowing around fins in contact with the tubes. As the gas refrigerant loses heat to the surrounding air, the high-pressure, high-temperature gas refrigerant cools and condenses into high-pressure, moderate temperature liquid refrigerant.
Subsequently, the liquid refrigerant passes through another high-pressure section of the conduit to the expansion device, which expands the compressed liquid refrigerant, thereby further cooling the liquid refrigerant into a low-pressure, low temperature liquid/gas refrigerant mixture (e.g. 40 PSI at 50° F.). Subsequently, the cooled liquid/gas refrigerant mixture is conveyed from the expansion device to the evaporator through a low-pressure section of the conduit. The evaporator is also typically constructed in accordance with a tube-and-fin type heat exchanger. Within the evaporator, the liquid/gas refrigerant mixture absorbs heat from fan-blown air passing around fins of the evaporator. The fan-blown air is thereby cooled and passed into a living space to be cooled. As the liquid/gas refrigerant mixture absorbs heat from the surrounding ambient air, the low-pressure, low-temperature liquid/gas refrigerant mixture warms and evaporates into a low-pressure, low-temperature gas refrigerant. The gas refrigerant is then conveyed back to the compressor through a final section of the conduit to complete the circuit of the refrigeration system.
In most refrigeration systems, it is common to use one or the other of a receiver-dryer or an accumulator for various benefits. A receiver-dryer is typically located at the outlet end of the condenser in the pressure-side section of the refrigeration circuit. In contrast, an accumulator-dehydrator is typically located at the outlet end of the evaporator in the suction-side section of the refrigeration circuit. The receiver or accumulator is used for i) removing water from the refrigerant fluid, ii) screening out particulate matter, and iii) acting as a reservoir for the refrigerant fluid when refrigeration system demand is low. Additionally, an accumulator is used for iv) lubricating gaseous refrigerant with a prescribed amount of lubricating oil, and v) separating moisture-laden, partially vaporized refrigerant fluid into a moisture-free refrigerant vapor having a certain lubricating oil content. For an accumulator, it is important to separate and lubricate the refrigerant so as to provide a lubricated moisture free gas refrigerant to the inner workings of the compressor to keep the compressor in proper working condition.
It has been a major challenge in the prior art to design and manufacture such devices that operate efficiently and that are inexpensive and easy to manufacture. Traditionally, a receiver-dryer or accumulator-dehydrator is made of metal components, often aluminum, that have a sufficiently high strength to withstand the relatively high pressure within the refrigeration circuit. Within typical receiver-dryers and accumulator-dehydrators there are some similar components. Of primary concern are outlet tubes and oil pickup filters attached thereto. Various types of outlet tubes and oil pickup filters therefor have been used in refrigerant vessel designs for many decades. Such systems typically include the outlet tube having an open intake end disposed in an upper gaseous portion of the accumulator above the level of any liquid refrigerant therein. Some outlet tubes extend downwardly from the open intake end and are U-shaped such that an intake leg extends roughly parallel to an outlet leg of the outlet tube. Other outlet tubes, such as used in refrigerant receivers, have their open intake end disposed proximate the bottom of the receiver that terminates in a filter unit. Still other outlet tubes are of single-leg, dual-channel design having a downflow channel and an upflow channel disposed side by side, wherein the outlet tube terminates in a filter unit disposed in a distal portion of the vessel.
It has long been known that it is important with all of these designs that the pickup filter be located at or as near the bottom of the accumulator as practicable. For example, it was taught in U.S. Pat. No. 2,953,906 to Quick to extend a capillary tube or pickup tube through an opening in a lowermost bight portion of a U-shaped outlet tube. A discharge end of the capillary tube extends upwardly into the outlet tube and an oppositely disposed intake end extends exteriorly of the outlet tube. The intake end of the pickup tube extends downwardly and terminates in a screen portion that rests on the bottom of the container for picking up a controlled amount of liquid refrigerant and oil.
Subsequently, U.S. Pat. No. 4,199,960 to Adams et al. taught an accumulator having telescoped sections of straight tubes that replace the conventional U-shaped tube to enable using a container having a smaller diameter. Adams et al. disclosed the accumulator container as having a closed bottom wall and a pair of telescoped tubes extending upwardly from the closed bottom wall. A lower end of the telescoped tubes fits within a filter or cage having a disk that rests directly on the closed bottom wall. During operation, oil in the refrigerant settles out at the bottom of the container and is picked up through the filter that rests on the bottom of the container.
U.S. Pat. No. 4,920,766 to Yamamoto et al. and U.S. Pat. No. 5,191,775 to Shiina et al. disclose a refrigerant receiver having an aspirating or outlet tube extending downwardly within the tank or receiver with the outlet tube having a strainer or filter attached thereto and resting on the bottom of the receiver. In Yamamoto et al. the outlet tube extends downwardly through the filter, wherein the outlet tube terminates in a lower end positioned inside a recessed portion or sump of the receiver. Similarly, U.S. Pat. No. 4,827,725 to Morse teaches a suction accumulator having an improved dirt trap or filter to reduce the problems of dirt particles that cause premature mechanical failure of system components. In the Morse accumulator, a conduit includes a weir forming an upflow and downflow passage. The conduit extends downwardly within the accumulator and terminates with the filter. The filter includes a bottom that is located against the bottom of the vessel.
U.S. Pat. No. 4,474,035 to Amin et al. discloses an accumulator assembly having a U-shaped outlet tube with an oil return orifice and a filter assembly at a bight portion thereof. The filter assembly includes an integral clamp portion for maintaining a secure connection of the filter assembly to the outlet tube by means of a compressive clamping force. The clamp portion is curved so that split ends thereof surround the outlet tube and integrally fasten together. The filter assembly further includes a plastic hou
Pickett, Jr. Paul M.
Sasser, Jr. Lowell D.
Automotive Fluid Systems, Inc.
Jiang Chen-Wen
Vanophem & Vanophem, P.C.
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