Accumulator-Dehydrator Assembly for an Air Conditioning System

This invention relates to air conditioning systems and particularly to air conditioning systems for automobiles and the like.

With the increased use of air conditioners in automobiles, it has been found that system failures may occur because of the circulation of moisture in the refrigerant that adversely affects all components of the system but is especially damaging to the close tolerance components of the compressor. As a result increased repair costs and maintenance may be required.

Such air conditioning compressors are designed to operate on gaseous refrigerant only and include an accumulator that receives liquid and gaseous refrigerant from the evaporator and separates the liquid and gaseous refrigerant allowing only the gaseous refrigerant to enter the compressor. One way that has been used to remove moisture is to provide desiccant in cloth bags in the liquid refrigerant in the accumulator to adsorb moisture from the liquid. Although such a method is simple and inexpensive, it does not efficiently remove moisture since the desiccant adsorbs much less moisture from liquid than the vaporized refrigerant and there is no assurance that the gaseous refrigerant entering the compressor has come into contact with the desiccant.

In U.S. Pat. No. 4,331,001, it has been proposed to hold the desiccant above the liquid level in the accumulator housing and expose all of the vapors entering the compressor to the desiccant to remove any moisture. Although such a system is effective in removing moisture, it involves many parts requiring difficult assembly.

Accordingly, among the objectives of the present invention are to provide an accumulator-dehydrator assembly which is effective to remove the moisture, utilizes a minimum number of parts, is easy to assemble, utilizes low cost materials, and is easy to fill with dessicant.

In accordance with the invention, the accumulator-dehydrator assembly for an air conditioning system comprises an accumulator housing defining an enclosed chamber including an inlet and an outlet in the upper end and a refrigerant and oil accumulator in the lower end and a vapor drier canister assembly comprising a one-piece plastic body defining a closed top wall, a closed side wall and an open bottom. The canister includes an integral outlet projecting into and sealingly engaging the outlet of the housing.

A vapor filter is associated with the outlet of the canister such that refrigerant flows through the filter before passing through the outlet. A perforated plate with a felt pad is provided in the bottom of the canister for holding desiccant within said canister. A refrigerant and oil tube is mounted externally of the canister and has a lower end extending to the bottom of the chamber of the accumulator housing and has an upper end extending into the outlet of the canister. A plastic filter is associated with the lower end of the tube. Spring means yieldingly urges the perforated bottom plate upwardly. The canister has a desiccant filling opening in the side wall thereof, and interengaging means between the bottom plate and the canister for holding said bottom plate in a position such that desiccant can be introduced into the canister after which the bottom plate is released to hold the desiccant in the canister.

FIG. 1 is a part sectional partly diagrammatic view of an air conditioning system embodying the invention.

FIG. 2 is a vertical sectional view through a vapor drier canister assembly embodying the invention.

FIG. 3 is a fragmentary bottom plan view of the vapor drier canister assembly taken along the line 3--3 in FIG. 2.

FIG. 4 is a fragmentary side elevational view of the vapor drier canister assembly.

FIG. 5 is an elevational view of the canister prior to assembly.

FIG. 6 is a fragmentary sectional view taken along the line 6--6 in FIG. 5.

FIG. 7 is a top plan view of the portion shown in FIG. 5.

FIG. 8 is an elevational view of the liquid filter used in the system.

FIG. 9 is a top plan view taken along the line 9--9 in FIG. 8.

FIG. 10 is a side elevational view of the liquid filter shown in FIG. 8.

FIG. 11 is a sectional view taken along the line 11--11 in FIG. 10.

FIG. 12 is a top plan view of the liquid filter prior to assembly.

FIG. 13 is a fragmentary sectional view on an enlarged scale taken along the line 13--13 in FIG. 1.

Referring to FIG. 1, an air conditioning system is shown schematically and comprises a compressor 10 which delivers refrigerant to a condenser 11 and, in turn, to an expander 12 and an evaporator 13 back to the compressor 10. The accumulator-dehydrator assembly 15 embodying the invention is provided between the evaporator 13 and compressor 10 and functions to remove the moisture from the gaseous refrigerant.

Referring to FIGS. 1 and 2, the accumulator-dehydrator assembly 15 comprises a housing 16 that is entirely enclosed to define an accumulator chamber 17 for the liquid refrigerant at the lower end. The housing 16 includes an axially aligned inlet and outlet tubes 18, 19. The accumulator-dehydrator assembly 15 further includes a vapor drier canister assembly 20 including a liquid refrigerant and oil tube 21 mounted externally of the assembly with the upper end of the tube extending into an outlet tube 22 of a canister 23 and the lower end of the tube 21 extending into a liquid filter 24 submerged in the liquid refrigerant.

The canister assembly 20 comprises a one-piece canister 23 made of plastic such as polypropylene. The canister 23 comprises two molded halves 23a, 23b joined by an integral hinge 39 and brought together, as presently described, to define a closed top wall 25, a closed side wall 26, an open bottom and the integral outlet 22 that projects into the outlet 19 of the accumulator housing and sealingly engages the outlet by use of an O-ring 27.

The canister assembly further includes a perforated plate 28 that is yieldingly urged upwardly by a spring 29 to press desiccant upwardly. The perforated plate 28 includes a felt pad 32 overlying and attached thereto as by rivets which functions to prevent particles of the desiccant D formed by vibrations from falling through the holes in the bottom plate 28, which would deplete the supply of desiccant. The felt pad 32 provides little restriction to the gas flow. The spring 29 is interposed between the perforated plate 28 and a retainer ring 30 crimped over the bottom of the side wall 26 at circumferentially spaced points. The canister is also formed with a desiccant filler opening 31 in the side wall.

Initaially, the canister 23 is inverted and the bottom plate 28 is held in position below the filler opening 31 (FIG. 2) so that the canister can be inverted, desiccant can be introduced through the filler opening 31 and the bottom plate 28 is thereafter released. Specifically, the bottom plate 28 includes a peripheral flange 33 having axial tabs 34 that extend through openings in the ring and are bent inwardly as in FIGS. 2 and 3 to retain the perforated bottom plate 28 below the filler opening 31. After the desiccant has been introduced, the tabs 34 are straightened permitting the spring 29 to urge the perforated plate 28 against the desiccant.

A filter 35 is provided with a peripheral flange 36 that telescopes over an annular wall 37 on the outlet 22. Gaseous refrigerant passes downwardly from the inlet, then upwardly through the desiccant and through the filter to the outlet. Filter 35 has mesh or foraminous walls 38 which function as a filter.

As shown in FIGS. 5-7, the canister 23 is molded as one piece comprising two halves 23a, 23b joined by an integral hinge 39. After molding, the filter 35 is positioned on the annular wall 37 and the two halves are brought together and joined ultrasonically to define the canister. The side wall includes a plurality of ribs or projections 40 extending inwardly into contact with filter 35 to hold the filter in position. Ribs 41a and grooves 41b may be provided to facilitate alignment and engagement of the two halves 23a and 23b prior to joining. Ribs 41a and grooves 41b provide a tongue and groove joint which has the primary purpose of insuring that there is no opening at the joined edge so that particles of desiccant and a secondary purpose of aligning the edges for joining.

After the canister halves are brought together and joined and the refrigerant and oil tube 21 is inserted into the outlet wall 22, the subassembly of retainer ring 30, bottom plate 28, pad 32 and spring 29, with tabs 34 extending through ring 30 and bent over, is placed on the open end of the canister 23 and attached thereto by crimping the ring 30 over the end of the canister as at 30a.

Self-actuating integral stops 50 are provided on the side walls 23a, 23b of the canister for engaging the lower edge of the peripheral flange 33 of bottom plate 28 to insure that the plate 28 can not move downwardly on impact due to the weight of the desiccant overcoming the spring force to expose the filling opening momentarily allowing desiccant to escape. Each stop 50 is formed as a tab in the wall of the canister and is connected at its base to the wall. Each stop includes a transverse wall 51 and a ramp 52 inclined upwardly and radially inwardly so that as the flange 33 or bottom plate 28 is moved upwardly it will move along the ramp 52 pushing the stops 50 outwardly and snap over the wall 51 and the stops 50 will move radially inwardly under flange 33 to prevent axially outward movement of the bottom plate 28. (FIG. 13)

Referring to FIGS. 2 and 4, the refrigerant and oil tube 21 is made of one-piece metal such as steel and includes an integral orifice 42 at the upper end, a deformed radially outwardly extending integral portion 43 spaced from the upper end which engages the outer wall of the outlet 22 and a flattened portion 44 intermediate the ends which engages a notch 45 in the ring 30 to hold the tube 21 in position externally of the canister. A tab 46 on plate 28 initially extends axially and is bent over to a transverse position to retain tube 21. The liquid filter 24 is press fitted on the lower end of the tube. The enlarged deformed portion 43 of the tube 21 adjacent the tube end serves two functions when it engages the outside wall of the tube 22. First it locates the orifice 42 in the proper position along the inner wall of the outlet to insure that the outlet flow of gaseous refrigerant causes sufficient venturi effect to draw oil and refrigerant droplets up the tube 21 and through the orifice 42. Secondly, it acts as a stop in conduction with the stop formed by the flattened portion 44 of the tube in the bottom member to hold the tube 21 in the proper vertical position.

Referring to FIGS. 8-12, filter 24 comprises a hollow plastic body having foraminous or mesh walls 46 such that the liquid must flow through the filter to pass upwardly into the tube 21. As shown in FIG. 12, the liquid filter is molded in one piece to define two halves joined by an integral hinge such that when the halves are brought together and joined by fusion or bonding on the remaining edges, the hollow filter is defined.

It can thus be seen that there has been provided an accumulator-dehydrator assembly that is easy to manufacture and assemble, low in cost, and utilizes a minimum number of parts.