ACCUMULATOR WITH REFRIGERANT PROCESSING CARTRIDGE FOR AUTOMOTIVE AIR CONDITIONING SYSTEM

Abstract: An accumulator for use in an air conditioning system for an automotive vehicle includes a cylindrical housing (10) with an inlet tube (22) and an outlet tube (26) extending through the housing, and an axially insertable refrigerant processing cartridge positioned within the housing (10) and including an outer casing (32,34) a desiccant (40), a filter (36a,36b,38) and a separator (32), all for processing the refrigerant flowing through the accumulator.

Description: This invention relates to a refrigerant processing cartridge for use in an accumulator of an air conditioning system for an automotive vehicle according to the first part of claim 1. Automotive air conditioning systems typically use Freon as a refrigerant. An air conditioning compressor in the system compresses Freon for delivery to an air conditioning condenser where the state of the refrigerant changes from gas to liquid. The outlet side of the condenser is connected to an expansion device and to an evaporator where the refrigerant changes state from a liquid to a gas. An air blower circulates air over the evaporator to the vehicle passenger compartment causing heat transfer to occur from the ambient air to the evaporator. The outlet side of the evaporator in some air conditioning systems is connected to an accumulator that contains a liquid-gas separator. The separator causes liquid components of the refrigerant to be separated from the gaseous component before the gaseous component is returned to the compressor. The accumulator also provides for recovery of lubricating oil contained in the refrigerant gas and for returning a metered amount of lubricating oil to the inlet side of the compressor for lubrication purposes. Because the accumulator is connected to the inlet side of the compressor, the reduced absolute pressure in the accumulator causes a portion of the liquified refrigerant to return to the gaseous state, whereupon it is returned to the inlet side of the compressor. An example of a prior art air conditioning accumulator is shown in Figure 1 of the specification and described in U.S. patent 4,474,035, which is assigned to the assignee of the present invention. An example of an accumulator for use on the high pressure side of a refrigeration system is shown in U.S. patent 3,778,984 which is also assigned to the assignee of the present invention. Both arrangements, regardless of whether the accumulator or separator is on the inlet side of the compressor or on the high pressure or outlet side of the compressor, function to separate liquid refrigerant from gaseous refrigerant and for separating the lubricating oil from the gas. The amount of liquid retained in the accumulator of the present invention depends upon the conditions under which the system operates. Regardless, however, of the amount of liquid retained in the accumulator, the accumulator functions to allow only vapor to be returned to the compressor together with a very small metered amount of lubricating oil. Designers have employed a variety of schemes for arranging accumulators or oil separators for use with compressors. In the usual case, the working fluid of the the system is circulated to the accumulator tank, where the vapor components are caused to rise in the tank and are drawn off through a filter. Typically, all of the vapor passing from the accumulator or separator must first pass through the filter element. The following U.S. patents generally describe such types of accumulators or separators: 1,672,571; 3,633,377; 4,173,440; 4,289,461 and 4,553,906. Further, British patent 1,512,507 and German patents 2,720,214 and 3,506,433 describe similar systems for separating and filtering oil from the working fluid of a compressor. Each of these defices employs a single flow path for the working fluid being returned to the compressor. This is disadvantageous inasmuch as a blockage of the single flow path will cause failure of the refrigerating system. U.S. patent 2,608,269 describes an oil separator for a refrigeration system in which all of the gases and oil entering the oil separator must first pass through a solid adsorbent block and then through a matted mesh strainer before passing out of the separator. This type of system as well as systems described in U.S. patents 4,331,001 and 4,509,340 suffer from a common deficiency inasmuch as the refrigerant may be subjected to an excessively high pressure drop occasioned by the requirement of passage along a single flow path through not only a screen element but also through a desiccant or dehydrator material. The latter two patents described automotive air conditioning accumulator asemblies in which a cartridge including a desiccant material has an outlet extending from the cartridge at a right angle to the exis of the accumulator. These cartridges are not well suited, therefore, to automated assemblies of the accumulators because the cartridges are not susceptible to axial insertion into the upper portion of the cylindrical housing of the accumulator. US-A-4,331,001 discloses an accumulator-dehydrator assembly for an air conditioning system wherein refrigerant and oil and possibly water are circulated. All vapour components are forced to pass through a desicant to allow the dessicant to effectively adsorb any water entrained therein and liquid refrigerant and oil are collected and eventually atomised for continued circulation with the vapour components passing through the dessicant. It is an object of the invention to provide a refrigerant processing cartridge for use in an accumulator of an air conditioning system wherein the cartridge has a dual flow path for the refrigerant in order that the refrigerant will not be subjected to an unduly great flow restriction on its way through the accumulator. According to the invention there is provided a refrigerant processing cartridge for use in the accumulator of an air conditioning system for an automotive vehicle, said system including refrigerant and a refrigerant circuit having a compressor, a condenser and an evaporator arranged in a series relationship on the higher pressure side of the compressor, said cartridge comprising a casing filter means for removing particulate matter from said refrigerant, and drier means for removing moisture from said refrigerant, characterised in that said filter means and drier means are disposed within said casing so as to comprise a first flow path for said refrigerant in which refrigerant passing through said cartridge from a fluid inlet to a fluid outlet passes through both said filter means and said drier means, and a second flow path in which refrigerant passes only through said filter means. The invention will now be described further by way of example, with reference to the accompanying drawings in which: Figure 1 is a cut away view of a prior art automotive air conditioning accumulator. Figure 2 is a cut away view of an accumulator according to the present invention, as well as a schematic of an air conditioning system suitable for use with an accumulator according to the present invention. Figure 3 is a cross section, partially broken away, of an accumulator according to the present invention taken along the line 3-3 of Figure 2. Figure 4 is a partial cross section of an accumulator according to the present invention taken along the line 4-4 of Figure 2. Figure 1 shows a prior art accumulator in which cylindrical housing 10 comprising upper portion 12 having an upper housing wall 20 and lower portion 14 having lower housing wall 18 is equipped with inlet tube 22 and outlet tube 26. Domed baffle 28 is provided for the purpose of assisting the separation of the refrigerant components into the gaseous and liquid fractions. The capability for drying refrigerant is provided by desiccant bag 24 which is strapped to outlet tube 26. The accumulator shown in Figure 1 suffers from several deficiencies. First, the placement of desiccant bag is difficult to achieve through a manual operation because the bag must be wired in place upon the outlet tube. If this wiring operation is not performed properly, the bag may become damaged during a subsequent operation in which brazed or welded joint 16 is formed. If this should occur, the desiccant pellets will be allowed to escape from the bag and will fall to the bottom of the accumulator and become submerged in the oil and liquid refrigerant held in the accumulator. Much of the efficiency of the desiccant will thereby become lost because desiccant will not function efficiently when submerged in liquid. This deficiency is of considerable importance because failure of the compressor may be caused by the ingestion of loose dessicant. Yet another deficiency of the design shown in Figure 1 resides in the fact that it is not suitable for automated assembly of the accumulator because of the need to wire the desiccant bag to the outlet tube as well as the need to bend the pickup tube and to braze the dome to the tube. The accumulator designs disclosed in U.S. patents 4,331,001 and 4,509,340 suffer from previously described deficiencies inasmuch as neither is suitable for automated assembly of the accumulator, and further because only a single flow path is available for refirgerant passing through the accumulator. As shown in Figure 2, an accumulator according to the present invention includes cylindrical housing 10 having an axial centerline as shown and comprising upper portion 12 which includes upper housing wall 20, and lower portion 14 which includes lower housing wall 18. The upper and lower portions of the housing are joined by brazed joint 16. Those skilled in the art will appreciate in view of this disclosure that joint 16 could comprise a brazed or welded joint, or a threaded or bolted joint or any other type of suitable joint. In the event that it is desired to manufacture an easily rebuildable accumulator, joint 16 may comprise a threaded or bolted joint which will allow the refrigerant processing cartridge to be readily removed from the accumulator for renewal. Those skilled in the art will further appreciate in view of this disclosure that cylindrical housing 10 could be fabricated of various materials such as ferrous and nonferrous metals, plastics, composite materials, or other types of materials known to those skilled in the art. Those skilled in the art will further appreciate in view of this disclosure that the accumulator housing could have a geometrical shape other than that of a cylinder. Other shapes may be appropriate for other applications of the present invention. As shown in Figure 2, an accumulator according to the present invention is provided with inlet tube 22 which is joined with upper housing wall 20. Inlet tube 22 conveys refrigerant from evaporator 62 into the accumulator. Although figure 2 shows evaporator 62, condenser 58, expansion orifice 60 and compressor 56 of a conventional air conditioning system, those skilled in the art will appreciate in view of this disclosure that an accumulator according to the present invention may be used in other types of air conditioning systems and at other locations within such systems. An accumulator according to the present invention may be joined with compressor 56 of the air conditioning system illustrated in Figure 2 by means of outlet tube 26 which extends through upper housing wall 20 of the accumulator. As shown in Figures 2 and 4, an axially insertable refrigerant processing cartridge positioned within the housing is operatively connected with outlet tube 26. The refrigerant processing cartridge shown within the accumulator of Figure 2 comprises a generally cylindrical outer casing including a cylindrical casing side wall 34 and a domed upper casing wall 32 which comprises a convex baffle. The baffle functions as separator means for promoting separation of the liquid and vapor components of the refrigerant entering the accumulator through inlet tube 22. The outer casing of the cartridge additionally includes a lower casing wall which is divided into strainer sections 36A and 36B (Figure 3). Each strainer section functions as a filter to remove particulate material from the flowing refrigerant. In combination, strainer sections 36A and 36B comprise a first strainer element extending across substantially the entire lower portion of the casing. Strainer section 36A comprises a portion of a first flow path through which refrigerant flows through both the strainer and also through desiccant 40 (See Figure 2). Strainer section 36B (Figure 3) comprises a portion of a second flow path which permits refrigerant to flow into outlet tube 26 without first passing through desiccant material 40. In usual fashion, the desiccant material is intended to remove moisture residing in the circulating refrigerant. As shown in Figures 2, 3 and 4, second strainer element 38, which comprises an internal wall of the refrigerant cartridge casing, divides the first strainer element into a first section, 36A which, in combination with second strainer element 38, contains desiccant material 40 within the outer casing of the cartridge. Thus, strainer section 36A and second strainer element 38 comprise filter means for retaining desiccant 40 within the cartridge casing. First strainer element 36A and second strainer element 38 thereby define a portion of a first flow path in which refrigerant will flow through both strainer elements and desiccant material 40 before flowing into apertures 46 in coupling tube 42 prior to leaving the accumulator through outlet tube 26. According to this first flow path, refrigerant impinging upon the domed upper casing wall 32 is separated into gaseous and liquid fractions and then flows up through section 36A of the first strainer element, and then through or over desiccant pellets 40. Flow continues through second strainer element 38, through apertures 46 within coupling tube 42 mounted within the refrigerant cartridge, and then into outlet tube 26. As previously noted, a second refrigerant flow path is partially defined by strainer section 36B, which permits refrigerant to flow into apertures 46 in coupling tube 42 and then into outlet tube 26 without passing through desiccant material 40. Accordingly, because the refrigerant is not caused to flow through the desiccant material, the flow of refrigerant will not be hampered even in the event that the desiccant material becomes blocked to flow due to contamination. This fact is important because the performance of the air conditioning system will be maintained for a longer period of time even with a contaminated system. Another advantage of the dual flow path system resides in the fact that operation of the system with little or no refrigerant flow will likely cause damage to the compressor; this possibillity is limited by a refrigerant processing cartridge according to the present invention. The details of coupling tube 42 and outlet tube 26 are shown in Figures 2, 3 and 4. Particularly with reference to Figure 4, coupling tube 42 is shown as being mounted within the cartridge and extending from upper casing wall 32. Coupling tube 42 is equipped with O-ring seal 44 which slidingly accepts outlet tube 26 during the accumulator assembly. Accordingly, coupling tube 42 and O-ring seal 44 comprise a port for sealingly receiving outlet tube 26 within the refrigerant processing cartridge. In a broader sense, coupling tube 42 and O-ring seal 44 comprise means for connecting the refrigerant processing cartridge with outlet tube 26. As previously noted, Figures 2, 3, and 5 also show apertures 46 in coupling tube 42, which allow refrigerant to pass into the outlet tube as part of the two defined flow paths. Those skilled in the art will appreciate in view of this disclosure that the desiccant contained within a refrigerant processing cartridge according to the present invention could comprise either a pellet or a porous cake form of desiccant, or any other type of desiccant suitable for use in a refrigerant processing cartridge. A refrigerant processing cartridge according to the present invention is axially insertable within the accumulator described herein because the cartridge may be slidably engaged with outlet tube 26 and movement of the cartridge into the accumulator is guided by a plurality of retention and locating structures comprising retention and locating tabs 52 extending from the casing of the refrigerant processing cartridge in the vicinity of the lower casing wall. Structures 52, which are shown in Figures 2 and 3, permit an accumulator according to the present invention to be assembled properly with either automated or manual production methods. Because, as shown in Figure 3, retention and locating tabs 52 are placed asymetrically about the periphery of the lower casting wall 36A-36B, retention and locating tabs 52 may be utilized for the purpose of positioning the refrigerant processing cartridge casing within an automated assembly machine as well as ultimately within the accumulator housing itself. In effect, retention and locating tabs 52 may be employed to index the refrigerant processing cartridge casing within the automated assembly machine. Moreover, as shown in Figure 2, retention and locating tabs 52 are also employed for the purpose of retaining refrigerant processing cartridge casing within the accumulator. As shown in Figure 2, each of the tabs 52 rides up and over a localized embossment 54 formed within the upper portion 12 of the cylindrical housing 10. Thus, once the refrigerant processing cartridge casing has been axially engaged with outlet tube 26 and retention and locating tabs 52 have been allowed to lock in place above embossments 54, the refrigerant processing cartridge will be retained within the accumulator. The localized nature of embossments 54 allows these embossments to be employed as a further aid to the correct assembly of the present accumulator, because the assembly operator, whether man or machine, will be able to correctly index the cartridge with the accumulator housing by indexing embossments 54 with retention and locating tabs 52. Those skilled in the art will appreciate in view of this disclosure that the outer casing of a refrigerant processing cartridge according to the present invention, including the strainer elements, could be fabricated of various materials such as ferrous or nonferrous metals, plastic materials, or various composite materials. Lubricating oil is allowed to circulate with the refrigerant of most conventional automotive air conditioning systems. Accordingly, an accumulator according to this invention preferably includes aspirator tube 48 including aspirator tube strainer 50. Aspirator tube 48 allows droplets of liquid refrigerant and oil to be entrained into the flow of refrigerant leaving the accumulator through outlet tube 26. Advantageously, an accumulator according to the present invention is rebuildable. Rebuilding of the accumulator could involve disassembly of cylindrical housing 10 followed by removal of the spent or contaminated refrigerant processing cartridge, followed by insertion of a new refrigerant processing cartridge. In sum, a refrigerant processing cartridge according to the present invention will provide dual flow paths with filter means for removing particulate matter from the refrigerant. The first of said flow paths also comprises drier or desiccant means disposed within the cartridge so as to comprise a flow path in which the refrigerant exiting the accumulator must pass through both filter and drier means. In taking said second flow path, refrigerant leaving the accumulator must pass only through the filter means. This dual path aspect of the present invention is important because it has been found that prior art accumulators which require that the refrigerant leaving the accumulator flow serially through filter means and then through a desiccant sometimes impose an undesirably great pressure restriction upon the flow of the gaseous refrigerant. An accumulator according to the present invention will not subject the flowing refrigerant to unduly great flow restriction. Further, the positioning of desiccant within a cartridge elevated above the liquid within the accumulator assures that the desiccant will be more efficiently utilized, as it will not be submerged within the liquid refrigerant and lubricating oil.

Claims: A refrigerant processing cartridge for use in the accumulator of an air conditioning system for an automotive vehicle, said system including refrigerant and a refrigerant circuit having a compressor (56), a condenser (58) and an evaporator (62) arranged in a series relationship on the higher pressure side of the compressor (56), said cartridge comprising a casing (32,34), filter means (36A, 36B, 38) for removing particulate matter from said refrigerant, and drier means (40) for removing moisture from said refrigerant, characterised in that said filter means (36A,36B,38) and drier means (40) are disposed within said casing (32,34) so as to comprise a first flow path for said refrigerant in which refrigerant passing through said cartridge from a fluid inlet to a fluid outlet passes through both said filter means (36A,36B,38) and said drier means (40), and a second flow path in which refrigerant passes only through said filter means (36A,36B,38). A refrigerant processing cartridge according to Claim 1, further comprising a domed baffle (32) for promoting separation of the liquid and vapor components of the refrigerant. A refrigerant processing cartridge according to Claim 1 or Claim 2, further comprising means (48,50) for aspirating lubricating oil and refrigerant droplets into the flow of refrigerant leaving said accumulator. A refrigerant processing cartridge according to any one of the Claims 1 to 3, further comprising tabs (52) for positioning said cartridge within an automated assembly machine and for indexing said casing (32,34) within said accumulator. A refrigerant processing cartridge according to Claim 4, comprising a plurality of locating tabs (52) spaced about the outside of said casing (32,34) An accumulator for use in an air conditioning system for an automotive vehicle, said system including refrigerant and a refrigerant circuit having a compressor (56), a condenser (58) and an evaporator (62) arranged in a series relationship on the high pressure side of the compressor, said accumulator comprising a housing (10) comprised of upper and lower portions (12,14) together in abutting relationship to define a closed chamber with a central axis, said accumulator housing having an upper housing wall (20) and a lower housing wall (18), an inlet tube (22) extending through said upper wall (20) for communication with the outlet side of said evaporator (62), an outlet tube (26) extending through said upper wall of said housing for communication with the inlet side of said compressor, and a cartridge as claimed in claim 1, positioned within said housing, said cartridge further comprising, upper and lower casing walls (32,36A,36B), separator means for promoting the separation of the liquid and vapor components of said refrigerant, said cartridge being positioned within said housing (10) by axially inserting said cartridge into said upper portion (12) of said housing so that said cartridge is operatively connected with said outlet tube (26). An accumulator according to Claim 6, wherein said upper and lower portions (12,14) of said housing (10) are generally cylindrical. An accumulator according to Claim 6 or 7, wherein said outer casing (32,34) of said refrigerant processing cartridge comprises a generally cylindrical casing (34) having a domed upper casing wall (32) comprising a convex baffle, with said baffle comprising said separator means, and means (42,44) for connecting said cartridge with said outlet tube (26). A accumulator according to Claim 8, wherein said casing (32,34) further comprises a plurality of retention and locating structures (52) extending from said generally cylindrical casing (34) in the vicinity of said lower casing wall. An accumulator according to Claim 8 or 9, wherein said means (42,44) for connecting said cartridge with said outlet tube (26) comprises a port for sealingly receiving said outlet tube (26) within said cartridge. An accumulator according to any one of Claims 6 to 10, wherein said filter means (36A,36B,38) comprises a strainer extending across a lower portion of said casing and comprising said lower casing wall. An accumulator according to any one of Claims 6 to 11, wherein said drier means (40) comprises desiccant retained within said casing by said filter means (36A,36B,38). An accumulator according to Claim 6, wherein said housing (10) is a cylindrical housing, the inlet tube (22) extends through said upper wall (20) at a location proximate the geometric centre of said upper wall, the casing (32,34) of said cartridge is a generally cylindrical casing having a domed upper wall (32) comprising a convex baffle maintained in close proximity to said inlet tube (22), and the filter means (36A,36B,38) include first and second particulate strainer elements with said first strainer element (36A,36B) positioned as the,lower wall of said casing (32,34) and said second strainer element (38) positioned as an internal wall of said casing (32,34), thereby dividing said first strainer element into a first section (36A) which, in combination with said second strainer element (38), contains said desiccant material within said outer casing, and a second section (36B) which permits refrigerant to flow into said outlet tube (26) without passing through said desiccant material, and further includes a port (42,44) for sealingly receiving the outlet tube (26) within said cartridge and means (52,54) for retaining said casing (32,34) within said upper cylindrical portion.

Inventors: AMIN, JEYENDRA J., BREUHAN, RONALD G.
Applicants: FORD FRANCE SOCIETE ANONYME, FORD MOTOR COMPANY LIMITED, FORD-WERKE AKTIENGESELLSCHAFT
Application year: 1988
Main classification: F25B43
IPC codes: F25B43