Reverse Balance Flow Valve Assembly For Refrigerant Systems

Abstract

The reverse balance flow valve is used in circumstances using an expansion valve controlled evaporator where the air conditioner evaporator coils and the heater core are in a common plenum chamber. It is a one-way valve installed between the line extending from the expansion valve to the evaporator and the upper gas portion of the receiver tank on the high pressure liquid side of the condenser. It automatically relieves or balances the pressure in the system during non-air conditioning cycles (where the compressor is connected to the engine at all times), when and if the refrigerant on the evaporator side increases in pressure over the refrigerant on the condenser side thus preventing refrigerant and oil migration and subsequent flooded starts with possible damage to the compressor when the refrigerant unit is switched to the air conditioning cycle.

Description

BACKGROUND OF THE INVENTION

This invention relates to new and useful improvements in air conditioning systems, particularly air conditioning systems which are used on motor coaches, automotive or commercial central household units which employ an expansion valve controlled evaporator and where the heating and air conditioning evaporator coils are in common plenum chamber.

Such systems usually have a compressor which is running at all times inasmuch as it is normally driven from a common source of power and various pressure switches determine whether or not the refrigeration system is operative.

Under normal circumstances, and during the non-air conditioning cycle, refrigerant and lubricating oil are sometimes purged from the compressor or, liquid refrigerant accumulates at the compressor causing damage on subsequent start up of the air conditioning system.

The damage occurring at the present time is caused by the fact that the expansion valve function is to allow the refrigerant to flow as required from the receiver tank through the evaporator coil. It is designed not to allow a reverse flow of pressure or refrigerant.

The compressor discharge valve acts as a function of the compressor allowing refrigerant under pressure to be exerted in one direction only, namely towards the condenser and receiving tank. Once again these valves are so designed to not allow pressure to reverse through them during the normal air conditioning cycle.

Therefore when the systems are shut down and heat is applied in the plenum chamber, the evaporator is heated to the heating system temperature and its effect on the refrigerant system causes the pressure of the refrigerant in the evaporator to rise due to the increase in temperature.

When this pressure exceeds the pressure of the refrigerant in the condenser (which is usually remotely situated and is at ambient temperature) the refrigerant tends to migrate towards the compressor and accumulate at the compressor base or, is forced through the condenser carrying the lubricating oil with it.

This causes what is commonly known as a flooded start and because of the reciprocating type of compressors normally used which need lubrication, the piston cannot compress the refrigerant towards the cylinder head without damage. If oil is forced through under the evaporator heating migration then the compressor will run with lack of lubrication until the oil can return from the entire system.

Under these circumstances shock loading is often encountered during starts and lack of lubrication can also cause piston damage to the compressor.

SUMMARY OF THE INVENTION

The present invention overcomes these disadvantages by providing a reverse flow valve assembly which is a relatively low pressure one-way valve situated preferably between the line extending from the expansion valve to the evaporator and the gas portion of the receiver tank which is normally situated on the outlet side of the condenser. This valve and associated conduit permits pressure to equalize through the upper part or gas portion of the receiver tank if the evaporator encounters a higher temperature and pressure than the condenser. Therefore both sides of the expansion valve will neutralize in pressure and migrated flow is virtually eliminated as the discharge valve in the compressor can then keep the compressor static with the rest of the system.

Although the preferred embodiment shows a connection between the one side of the expansion valve and the receiver tank, nevertheless these conduits could be situated any where between the high pressure outlet from the condenser and the low pressure side of the expansion valve.

The principal object and essence of the invention is therefore to provide a device of the character herewithin described which automatically relieves excess pressure generated in the evaporator during non-air conditioning cycles of expansion valve controlled evaporator refrigeration units.

Another object of the invention is to provide a device of the character herewithin described which eliminates migration of lubricating oil and/or refrigerant during non-operating or non-air conditioning cycles.

A still further object of the invention is to provide a device of the character herewithin described which is extremely simple in construction, economical in manufacture, and otherwise well suited to the purpose for which it is designed.

With the foregoing objects in view, and such other or further purposes, advantages or novel features as may become apparent from consideration of this disclosure and specification, the present invention consists of the inventive concept which is comprised, embodied, embraced, or included in the means, method, process, product, construction, composition, arrangement of parts, or new use of any of the foregoing, herein exemplified in one or more specific embodiments of such concept, reference being had to the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a refrigeration system with the invention installed therein.

FIG. 2 is a modification of the apparatus.

DETAILED DESCRIPTION

Proceeding therefore to describe the invention in detail, reference to the accompanying drawing will show a conventional reciprocating compressor 10 normally driven in a continuous fashion from the engine of a motor coach or the like.

Situated in a plenum chamber shown in phantom by reference character 11, is an evaporator collectively designated 12 and which is conventional in construction.

Situated remotely from the compressor and the evaporator and preferably in a location where it can operate most efficiently, is a conventional condenser 13.

Reference character 14 indicates a conventional expansion valve which controls the evaporator and a gas and liquid low pressure and low temperature line 15 extends between the expansion valve and the evaporator as clearly shown. The suction line or low pressure, low temperature gas line 16 extends from the evaporator to the compressor which includes a one-way suction valve 17 thereon and a hose discharge line 18 extends from the discharge valve 19 of the compressor to the hose inlet 20 of the condenser 13.

A hose outlet 21 extends from the condenser to a conventional gas/liquid receiver tank 22 and a high pressure liquid line 23 extends from the base of this tank to the other side of the expansion valve 14 as clearly illustrated.

Conventional switches and monitoring devices are provided and are illustrated in the drawing.

Under these circumstances and when the refrigeration cycle is in effect, the expansion valve 14 releases high pressure liquid through line 15 to the evaporator and the low pressure, low temperature gas is then pumped by the compressor via line 16 to the discharge line 18 whereupon it becomes high pressure and high temperature gas. This then is fed to the condenser which changes this to liquid which in turn is passed to the receiver tank in the conventional manner.

However, when the unit is in the non-refrigeration cycle, the temperature of the plenum chamber may rise considerably due to the fact that the conventional heater unit (not illustrated) operates to heat the air passing through the plenum chamber rather than the air being refrigerated. This means that the evaporator together with any gas and/or liquid which may be therein, rises in temperature and therefore rises in pressure. The expansion valve being one-way in the direction of arrow 24, cannot relieve this pressure which then exhausts or migrates the refrigerant through the compressor and thence through to the condenser 13 taking with it any oil which may be picked up due to pressure differentials existing in the unloaded compressor 10.

The invention collectively designated 25 prevents this from happening. In the preferred embodiment it consists of a conduit 26 tapped into the low pressure, low temperature gas and liquid line 15 on the down stream aide of the expansion valve 14. This conduit leads to a relatively low pressure one-way valve 27 which operates one-way only in the direction of arrow 28 and a further conduit 29 extends from this valve 27 to the top or gas portion 30 of the receiver tank 22. The valve 27 is designed to open at approximately half pound per square inch so that any build up of pressure within the evaporator immediately exhausts through conduits 26 and 29 and valve 27 to the receiver tank thus maintaining a pressure equilibrium on both sides of the one-way expansion valve 14 and the one-way discharge valve 19. This of course effectively eliminates any migration of refrigerant and/or lubricating oil and prevents flooded starts and shock starts occurring to the system when the refrigeration system once again is switched on.

Although the embodiment just described is the preferred one due to the shortness of the routing of the conduits, nevertheless an alternate routing can be used and this is shown in phantom in the drawing. Under these circumstances a conduit 31 is tapped into the line 16 at any convenient point and extends to the one-way valve 27A which operates in the direction of arrow 28A only. A further conduit then extends from this valve to any convenient location on the high pressure liquid line 21. However, as this distance is considerable under normal installation design characteristics, it is the least preferred of the two embodiments.

Various modifications may be constructed or performed within the scope of the inventive concept disclosed. Therefore what has been set forth is intended to illustrate such concept and is not for the purpose of limiting protection to any herein particularly described embodiment thereof.

Claims

What I claim as my invention is:

1. In a refrigerant system which includes a compressor, a condenser, an expansion valve control evaporator with the necessary operating conduits therebetween, said evaporator being situated in a common plenum chamber together with heater means therein whereby air passing through said plenum chamber may be heated by said heater means or cooled by said evaporator; the improvement which comprises a reverse flow assembly for use during non-refrigeration cycles of said system when said heater means is operating, said reverse flow assembly including a relatively low pressure one-way valve and conduits connecting said valve between the downstream side of the expansion valve and the condenser outlet side of the expansion valve, said one-way valve allowing refrigerant to flow only from the former to the latter.

2. The system according to claim 1 in which said operating conduits include a gas and liquid low pressure conduit extending from said expansion valve to said evaporator, and a gas/liquid receiver tank on said outlet side of said condenser, said conduit connecting said valve between said gas and liquid low pressure conduit and the gas portion of said receiver tank.

3. The assembly according to claim 1 in which said operating conduits include a high pressure liquid outlet conduit from said condenser and a low pressure gas conduit between said evaporator and said compressor, said conduits connecting said one-way valve therebetween.