REFRIGERATION SUCTION ACCUMULATOR
United States Patent 3643466
The suction accumulator of the invention is designed for use with the suction or compression side of a refrigeration system. The accumulator comprises a casing having an inlet and outlet. A conduit is provided within the casing. The conduit extends from a point adjacent the bottom of the casing to the casing outlet and acts as a suction tube to draw liquid from the casing and expel it into the casing outlet at a metered rate. A liquid trap chamber is connected to the outlet to receive excessive amounts of liquid expelled from the conduit. The liquid trap chamber is connected exteriorly of the casing.
F25B43/00; (IPC1-7): F25B43/00
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CROSS-REFERENCE TO RELATED
This application is a division of
my application filed Sept. 16, 1968, Ser. No. 759,863 now
U.S. Pat. No. 3,563,053, issued Feb. 16, 1971.
What I claim as my invention is
1. In a suction accumulator for the compressor of a refrigeration system, said accumulator comprising a casing having an inlet and an outlet, a conduit within the casing having an open end adjacent the upper portion of the casing and having a portion extending from said open end to a point adjacent the bottom of the casing and thence to the casing outlet, said conduit having a metering opening adjacent the bottom of the casing, said conduit acting to draw gas through said open end thereof and draw liquid at a controlled rate through said metering opening therein and expel both the gas and the liquid into the casing outlet, the improvement comprising a liquid trap chamber connected to the outlet at a point thereabove to receive and hold excessive amounts of liquid expelled from said conduit, said trap chamber having a sufficient volume to receive any liquid which may be present at a given time in the conduit and still permit gas to pass through the outlet, said trap chamber being defined by a trap casing, said trap casing being positioned exteriorly of the accumulator casing, said trap casing being connected to the accumulator outlet, the interior of said trap casing defining the liquid trap chamber, and a lower surface within said trap casing angled downwardly toward said outlet whereby liquid refrigeration will drain from the trap casing back into the accumulator casing.
2. A suction accumulator as defined in claim 1, and further characterized in that sad trap casing comprises a boxlike structure having a lower wall angled from one end thereof towards the other, said outlet from the casing being connected to the lowermost portion of said wall, and conduit means leading from the upper portion of said trap casing and positioned over an upper portion of said wall and spaced from said casing outlet.
3. A suction accumulator as defined in claim 1, and further characterized in that said trap casing comprises a helical tube extending upwardly from the accumulator casing, the diameter of said helical tube being greater than the diameter of the conduit within the accumulator casing.
BACKGROUND OF THE INVENTION
The suction accumulator of the type to which the present invention relates is provided in a refrigeration system between the suction side of the system and the evaporator side. The function of the accumulator is to pass gaseous refrigerant on to the compressor of the system but to trap liquid refrigerant when this liquid is present in excessive amounts. The liquid refrigerant is retained within the accumulator and metered to the compressor at a controlled rate. This protects the compressor against shock resulting from the sudden injection into the compressor of large amounts of liquid refrigerant. Large amounts of liquid refrigerant may result in damage to the compressor or associated components.
The present invention provides an additional safety factor over and above the usual protection offered by a suction accumulator. Suction accumulators work well under normal operating conditions. However, it sometimes happens that an extremely large amount of liquid refrigerant will be present within the accumulator. Such accumulators have suction tubes which draw the gaseous and liquid refrigerant from the accumulator and deliver this fluid to the accumulator outlet. When the suction tube becomes filled with liquid refrigerant, such as may happen when the refrigeration system is shut down and then restarted, the slug of liquid material within the suction tube is injected into the outlet of the accumulator. This slug may cause damage to the compressor of associated components.
The present invention relieves this problem by providing a trap chamber in association with the accumulator outlet. The trap chamber is of sufficient capacity to receive all of the liquid within the suction tube while still permitting gas to be exhausted through the outlet.
A valve structure is provided for those instances where the trap chamber is not sufficient in capacity to handle all of the liquid refrigerant which may be injected thereinto. A further refinement of the invention is the provision of an inlet tube of low-cost construction which directs the stream of incoming fluid in a manner to prevent turbulence occurring within the accumulator.
SUMMARY OF THE INVENTION
The suction accumulator is for the compressor of a refrigeration system. The accumulator comprises a casing having an inlet and an outlet. A conduit is provided within the casing having an open end adjacent the upper portion of the casing and having a portion extending from the open end to a point adjacent the bottom of the casing and thence to the casing outlet. The conduit has a metering opening adjacent the bottom of the casing. The conduit acts to draw gas through said open end thereof and draw liquid at a controlled rate through the metering opening therein and expel both the gas and the liquid into the casing outlet. This suction accumulator is improved by providing a liquid trap chamber connected to the outlet at a point thereabove to receive and hold excessive amounts of liquid expelled from the conduit. The trap chamber has a sufficient volume to receive any liquid which may be present at a given time in the conduit and still permit gas to pass through the outlet.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a side elevational view in section of one embodiment of the suction accumulator of the present invention; and
FIG. 2 is a side elevational view in section of another embodiment of the accumulator of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, the suction accumulator 10 includes a casing which comprises an open-ended tube 12 having an upper end closure 14 and a lower end closure 16 secured thereto. An inlet tube 18 extends through the sidewall of the tube 12 adjacent the upper end of the tube. The inlet tube 18 extends for a short distance into the casing. One wall portion 20 is deformed inwardly into the tube to form a scoop for directing the flow of incoming fluid into the casing. The inlet tube 18 is angled downwardly so that the outlet directs the stream of refrigerant at a slightly downwardly inclined angle to thereby provide for a downward helical spiral of the gas stream. This is advantageous in that it prevents undue turbulence of the refrigerant gases in the upper portion of the casing which turbulence results in a reduction of the energy level of the incoming gases and causes foaming.
An outlet tube 22 extends through the upper end closure 14. The inner end 24 of the tube 22 is of reduced diameter and receives one end of a U-tube 26. One leg 28 of the tube 26 extends from the outlet tube 22 downwardly to a point adjacent the lower end closure 16. The tube is then provided with a bend 30 and the second leg 32 extends upwardly and terminates in an open end 34 adjacent the upper end closure 14. A small metering opening 36 is provided in the tube bend 30.
In operation of the accumulator, cold refrigerant gas having a small amount of entrained liquid refrigerant therein enters the accumulator through the inlet tube 18. The incoming gases, which move at a relatively high velocity, are directed tangentially against the interior wall casing and follow a spiral path around the casing interior. The gases are then free to expand with resultant reduction of the velocity thereof. As a consequence, incoming gases are not directed as a high-speed jet against any liquid which may be retained in the lower portion of the casing. This prevents turbulence of the liquid which may result in objectionable foaming and also prevents splashing of liquid into the open end 34 of the U-shaped tube 26. Introduction of liquid into the U-shaped tube by splashing is undesirable because it is desired to control the rate at which liquid enters the U-shaped tube.
The refrigerant gases which enter the casing are drawn into the open end 34 of the U-tube 26, pas through both legs of the U-tube and exit into the chamber 38. The gases are extracted from the chamber 38 via the outlet tube 40 and are then passed to the compressor of the system (not shown). The compressor, which creates a suction, draws the gaseous refrigerant through the accumulator at a relatively rapid rate.
Liquid refrigerant which enters the accumulator through the inlet tube 18 drops to the bottom of the accumulator casing and is subsequently drawn through the opening 36 and then through the leg 28 into chamber 38. It will be appreciated that the liquid which is metered into the leg 28 is entrained in the stream of gaseous refrigerant. It remains entrained in the gas within the chamber 38 and is drawn through the outlet tube 40 and thence to the compressor of the system. The opening 36 acts as a restriction and causes liquid refrigerant to be metered into the compressor at a controlled rate. The accumulator thus acts to prevent large amounts of liquid refrigerant from suddenly entering the compressor. Such sudden surges of liquid may result in seriously damaging the compressor.
During operation of the refrigeration system, there are times when an unusual amount of liquid refrigerant will collect in the accumulator. For example, when the system is shut off, such as is the case with an intermittently operated air conditioning system, the refrigerant tends to condense in the entire system and collects in the accumulator. A similar situation may occur when the system is operated under low load conditions. Further in extreme overload or flood-back conditions, an unusual amount of liquid refrigerant may be present in the system. At such times, the level of refrigerant may rise considerably above the bend 30 of the U-tube. There will then be a relatively large quantity of refrigerant within the legs of the N-tube. It is undesirable to deliver this liquid as a single slug to the compressor because this may cause compressor damage such as broken valves, pistons, connecting rods, crankshaft, blown gaskets or bearing failure. Additionally, such liquid may result in dilution of the oil liquid wash-out of the bearings or complete loss of oil from the crankcase.
The liquid trap chamber 38 is provided to prevent sending slugs of liquid refrigerant into the compressor. The liquid trap chamber 38 is defined by a casing 42 which is provided on the exterior end of the outlet tube 22. It will be noted that the casing 42 extends laterally from the outlet tube 22 and has an upwardly inclined bottom wall 44. The tube 40 extends from the upper wall 46 and is connected to the compressor of the refrigeration system.
In the event of an excess amount of refrigerant being present in the casing so as to fill the U-tube 26, the slug of liquid refrigerant in the U-tube will be injected into the trap chamber 38. The gaseous refrigerant will rise above the level of the liquid refrigerant in chamber 38 and be expelled through the tube 40 to the compressor. The slant or slope of the bottom wall 44 provides for run-back of the liquid refrigerant into the N-tube. Eventually, the liquid refrigerant will be metered into the outlet tube 40 by entrainment thereof in the stream of gaseous refrigerant to ultimately relieve the condition of excess liquid refrigerant in the accumulator without suddenly sending a slug of liquid material into the compressor structure.
It will be noted that a small orifice 48 is provided in the leg 28 of the U-tube 26 at approximately the same level as the open end 34 of the leg 32. The orifice 48 operates to equalize pressure in both legs of the U-tube, thereby preventing the flow of quantities of liquid into the suction line during the inactive period of the refrigeration cycle.
FIG. 2 illustrates an accumulator which is similar in concept and function to that illustrated in FIG. 1. In FIG. 2, the accumulator 50 comprises a casing 52 having an inlet tube 54 extending through the upper end closure 56. A U-tube 58 is provided within the casing 52. One leg 60 is connected to the outlet 62 which extends through the upper end closure 56. The outlet 62 is connected to a helical tubular member 64. The other leg 66 of the U-tube extends upwardly parallel with the leg 60 and terminates in an open end 68. A metering opening 70 is provided in the bend 72 of the U-tube.
In operation of the FIG. 2 embodiment, gaseous refrigerant enters the accumulator 50 through the inlet tube 54 and is drawn through the open end 68 of the leg 66 through the U-tube and thence through the outlet 62 into the tubular, helical member 64. The member 64 is eventually connected to the compressor structure of the refrigeration system via a conduit 78. The member 64 is of considerably larger diameter than the diameter of the U-tube. Consequently, it receives any liquid refrigerant in the U-tube without being completely filled. Gaseous refrigerant may bubble therethrough without carrying with it the liquid contents of the tube. The slant of the coils of the member 64 causes the liquid to tend to flow back into the U-tube so that it does not become dispersed by entrainment in the gaseous stream so that he device will operate ultimately in the normal manner.