Abstract:
A refrigeration system including a condenser, a compressor, an evaporator and an accumulator is provided. The refrigeration system includes a device for preventing condensation of liquid refrigerant in the compressor when the refrigeration is switched off for a prolonged period of time. Particularly, the device comprises a first reservoir that is a part of the conduit connecting the compressor and the accumulator. The first reservoir is placed below the body of the compressor and has a larger cross-section than the rest of the conduit. The present invention also includes a second reservoir in the conduit connecting the compressor and the condenser. Like the first reservoir, the second reservoir is also placed below the body of the compressor and has a larger cross-section than the rest of the conduit. The condensation of the refrigerant in the compressor is prevented by the following method when the refrigeration system is shut off the vapor present in the conduit condense in the conduit. As the refrigeration system continues to cool the liquid formed in the conduit will get collected in the reservoirs. Since the reservoirs are placed vertically below the compressor all of the liquid is collected in the reservoirs and prevented from traveling to the body of the compressor.

Description:
TECHNICAL FIELD OF THE INVENTION 
     This invention generally relates to refrigeration system to be used in automobiles. More specifically, this invention relates to a liquid refrigerant separator that prevents condensation of liquid refrigerant in the compressor during off cycle when the engine is switched off. 
     BACKGROUND OF THE INVENTION 
     Modern refrigerant compressor technology has generated designs which provide the maximum capacity per unit, weight, cost and efficiency. The compressors are generally designed for high rotative speeds and high bearing loads. In order to achieve these features it is important for these compressors not to have any liquid of any sort. Liquid can cause undue loads and NVH in the compressor chamber. 
     Liquid entering the cylinder can stem from two sources liquid oil can enter the cylinder from foaming of the oil in the compressor crankcase on start up. The other source of liquid is liquid refrigerant in relatively pure form, which can return under abnormal conditions through the suction or discharge lines. 
     If large quantities of liquid refrigerant enter the compressor much of the refrigerant will be entrapped into the cylinder with the vapor and will cause a condition known as slugging which accompanied by pounding and knocking sounds could cause compressor damage. 
     The liquid refrigerant can also return to the compressor in small quantities but over a period of time. This can happen in two ways. The first is when the refrigerant vapor condenses in the compressor over a prolonged period of time. The other way liquid refrigerant can enter the compressor is during start-ups. In order to prevent any liquid from entering the compressor, modern technology have developed suctions drums or surge accumulators whose sole purpose is to catch the liquid refrigerant returning in large or small quantities and prevent this potentially harmful liquid refrigerant from reaching the compressor. A suction accumulator is usually positioned between an evaporator and the compressor in an air conditioning unit. During operation, the suction accumulator receives the combined liquid and vapor from the evaporator via an inlet tube. Vapor passes on to the compressor via an outlet tube. Over the years various technologies have been developed to insure that only vapor passes through the suction tube and reaches the compressor. The suction accumulators prevent any liquid refrigerant from reaching the compressor. 
     However, when the system is turned off for a prolonged period, and the outdoor ambient temperature is less than the indoor ambient temperature, the compressor can become the coldest part of an air conditioning system. When this occurs, the refrigerant migrates to the compressor sometimes filling it completely with liquid refrigerant. Although modern technologies have devised systems to prevent any liquid refrigerant from reaching the compressor during use of the system, technology has yet to be developed to prevent any condensation of vapor refrigerant in the compressor when the system is turned off for a prolonged period of time. 
     Therefore there is a need for a refrigeration system that will prevent substantial condensation of a vapor refrigerant in the compressor when the system is turned off for a prolonged period of time. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, this invention provides for a refrigeration system that prevents condensation of the liquid refrigerant in the compressor when the system is shut off for a prolonged period of time. 
     Briefly, the invention includes a compressor for compressing vapor refrigerant, a condenser for condensing liquid refrigerant discharged out of the compressor, an evaporator for converting liquid refrigerant into vapor refrigerant and an accumulator for preventing liquid refrigerant from reaching the compressor. 
     The refrigeration system includes a device for preventing condensation of liquid refrigerant in the compressor when the refrigeration is switched off for a prolonged period of time. 
     The device comprises a first reservoir that is a part of the conduit connecting the compressor and the accumulator. The first reservoir is placed below the body of the compressor and has a larger cross-section than the rest of the conduit. 
     The present invention also includes a second reservoir in the conduit connecting the compressor and the condenser. Like the first reservoir, the second reservoir is also placed below the body of the compressor. 
     The present invention also provides for a method of preventing condensation of the refrigerant in the compressor. When the refrigeration system is shut off the vapor present in the conduit condense in the conduit. As the refrigeration system continues to cool the liquid formed in the conduit will get collected in the reservoirs. Since the reservoirs are placed vertically below the compressor all of the liquid is collected in the reservoirs and prevented from traveling to the body of the compressor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further features and advantage of the invention will become apparent from the following discussions and accompanying drawings. 
     FIG. 1 is a front perspective view of the refrigeration system in accordance with the teachings of the preferred embodiment of the invention; 
     FIG. 2 is a partial front view of the refrigeration system comprising the compressor and the accumulator and the conduit from the accumulator to the compressor in accordance with the teachings of the present invention, and 
     FIG. 3 is a cross section view of the conduit taken along the lines  2 — 2  in accordance with the preferred embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description of the preferred embodiment is merely exemplary in nature, and is in no way intended to limit the invention or its application or uses. 
     Referring in particular to the drawings, a closed circuit refrigeration system  10  in accordance with the preferred embodiment for use in automobiles is generally illustrated. 
     As shown in FIG. 1, the refrigeration system  10  circulates a refrigerant in the direction as shown by arrows  11  either to supply heat or to remove heat from the air supplied to the refrigeration system  10 . Typically the refrigeration system comprises an evaporator  12 , an accumulator  14 , a compressor  16  and a condenser  18 . 
     The evaporator  12  is a conventional evaporator and preferably includes an inlet end  13  for receiving the liquid refrigerant, an outlet end  15  for discharging vapor refrigerant and a heating element (not shown in the FIGURE) to heat the liquid refrigerant and to convert the liquid refrigerant into vapor refrigerant. The inlet end  13  of the evaporator  12 , preferably is connected by a conduit (not shown) to an evaporation valve (not shown). The evaporator  12  may not include some of these elements or include other elements to heat the liquid refrigerant when the refrigeration system  10  is turned on. The accumulator  14 , which functions to retain any liquid refrigerant not evaporated by the evaporator  12 , preferably includes an inlet end  17  for receiving the vapor and or liquid refrigerant from the evaporator  12 , an outlet end  19  for discharging the vapor refrigerant to the compressor  16 . The outlet end  15  of the evaporator  12  and the inlet end  17  of the accumulator  14  are preferably connected through a conduit  20 . The accumulator  14  preferably is a vertical suction type accumulator conventional in the art, although it is possible to have a horizontal suction type accumulator. Preferably, the inlet end  17  of the accumulator is present at the bottom of the accumulator  14  and the outlet end  19  is present at the top of the accumulator  14 . 
     The compressor  16 , functions to compress the vapor refrigerant from the accumulator  14 . Preferably, the compressor  16  comprises an inlet end  21  for receiving the vapor refrigerant; an outlet end  23  for discharging compressed vapor refrigerant and a high-speed motor (not shown) capable of compressing the vapor refrigerant. An outlet conduit  22  connects the outlet end  19  of the accumulator  14  and the inlet end  21  of the compressor  16 . Preferably the outlet conduit  22  is a U shaped tube (as shown in FIG.  1 ). The condenser  18 , functions to condense vapor refrigerant discharged from the compressor  16  to liquid refrigerant. The compressor  16  preferably comprises an inlet end  35 , an outlet end  37  for discharging the liquid refrigerant and a cooling element (not shown) for condensing the vapor refrigerant to liquid refrigerant. The outlet end  37  of the condenser  18  is preferably connected to the inlet end  13  of the evaporator  12  through the evaporation valve. The inlet end  35  is connected to the outlet end  23  of the compressor  16  by a discharge conduit  24 . Preferably, like the outlet conduit  22 , the discharge conduit  24  is also a u-shaped tube. 
     In a typical working of a refrigeration system  10  a liquid refrigerant (not shown) is circulated inside the refrigeration system  10  as indicated by arrows  11 . Typically the liquid refrigerant flowing inside the system  10  is evaporated at the evaporator  12 . The vaporized refrigerant is then transported to the accumulator  14  where any liquid refrigerant present or mixed with the vaporized refrigerant is retained by the accumulator  14 . Vaporized refrigerant is then discharged to the compressor  16  through the outlet conduit  22  whereby the vapor refrigerant is compressed. The compressed vapor is finally discharged to the condenser  18  through the discharge conduit  24 , where the vapor refrigerant condenses back to a liquid refrigerant. From the condenser  18 , the liquid refrigerant is re-circulated back to the evaporator  12 . 
     Referring in particular to FIGS. 2 and 3, the outlet conduit  22  consists of a first reservoir  26 , a first flow portion  28  and a second flow portion  30 . The first reservoir  26  is an integral part of the outlet conduit  22 . The first reservoir  26  has a hollow interior (not shown). As will be discussed later, the first reservoir  26  serves to collect the liquid refrigerant condensed in the outlet conduit  22  and prevent the liquid from reaching the compressor  16  when the refrigeration system  10  is shut off for a prolonged time. 
     Preferably, the first reservoir  26  comprises a base  25  and two arms  27 A and B. The base  25  and the arms  27 A and B are formed of one piece and preferably are u-shaped. Alternatively, the first reservoir  26  may take any shape that can substantially collect liquid refrigerant as indicated by reference numeral  39  when the refrigeration system is turned off for a prolonged period of time. Preferably the base  25  of the first reservoir is positioned such that the base  25  is lower than the body of the compressor  16 . As will be explained later, the liquid refrigerant will be substantially collected in the first reservoir  26  and prevented from reaching the compressor  16 . 
     The first flow portion  28  at one end  32  is integrally connected to the inlet end  21  of the compressor  16 . The other end  34  of the first flow portion  28  is connected to the first reservoir  26 . Similarly, one end  36  of the second flow portion  30  is connected to the outlet end  19  of the accumulator  14  and the other end  38  is connected to the first reservoir  26 . Preferably, the first flow portion  28  and second flow portion  30  have equal cross-section. Preferably, the first flow portion  28  has a diameter equal to the diameter of the second flow tube  30 . Preferably, the first flow portion  28  and the second flow portion  30  are substantially parallel to each other. Alternatively the first flow portion  28  and the second flow portion  30  may be oriented substantially perpendicular to each other or at an angle with respect to each other. In the preferred embodiment, the first reservoir  26  has a larger cross section than the first flow portion  28  and the second flow portion  30 . Preferably, the first reservoir  26  has an increased diameter than the first flow portion  28  and the second flow portion  30  for storing the liquid refrigerant. 
     In the preferred embodiment the first flow portion  28 , the second flow portion  30  and the first reservoir  26  are formed of one integral piece. Preferably, the first reservoir  26  is made of a metallic material such as aluminum or stainless steel preferably the same material as the compressor  16 . It is also preferred that the first flow portion  28  be made of the same metallic material as the compressor  16  and the first reservoir  26 . Alternatively, the first reservoir  26  and the first flow portion  28  may be made of a non-metallic material or a combination of a metallic and non-metallic material. The second flow portion  30  may be made of metallic material or of a non-metallic material. Preferably, the second flow portion  30  is made from a combination of metallic material and non-metallic material. Preferably the metallic portion  40  of the second flow portion  30  is connected to the first reservoir  26  and the non-metallic portion  42  is connected to the outlet end  19  of the accumulator  14 . Preferably the non-metallic portion  42  of the second flow portion  30  is made of a non-conductive material such as rubber or plastic. The metallic portion  40  is preferably made of the same metallic material as the first flow portion  28  such as aluminum or steel. 
     Referring in particular to FIGS. 1, the discharge conduit  24  in the refrigeration system  10  consists of a second reservoir  44 , a first flow portion  46  and a second flow portion  48 . The second reservoir  44  has a hollow interior (not shown). As will be discussed later, like the first reservoir  26 , the second reservoir  44  serves to collect the liquid refrigerant condensed in the discharge conduit  24  and prevent the liquid refrigerant from reaching the compressor  16  when the refrigeration system  10  is shut off for a prolonged time. 
     Preferably, the second reservoir  44  comprises a base  45  and two arms  47  A and B. The base  45  and the arms  47  A and B are formed of one piece and preferably are u-shaped. Alternatively, the second reservoir  44  may take any shape that can substantially collect liquid refrigerant as indicated by reference numeral  41  when the refrigeration system  10  is turned off for a prolonged period of time. Preferably the base  45  of the second reservoir  44  is positioned such that the base  45  is lower than the body of the compressor  16 . Preferably the second reservoir  44  is positioned above the first reservoir  26  such that the first reservoir  26  is the lowest part in the refrigeration system  10 . Alternatively, it is possible that the second reservoir  44  is placed in any position where it can collect liquid refrigerant condensed on discharge conduit  24  and prevent the refrigerant from reaching the compressor  16 . As will be explained later, the liquid refrigerant will substantially collect in the second reservoir  44  and will be prevented from reaching the compressor  16 . 
     The first flow portion  46  at one end  50  is integrally connected to the outlet end  23  of the compressor  16 . The other end  52  of the first flow portion  46  is connected to the arm  47 A of the second reservoir  44 . Similarly, one end  54  of the second flow portion  48  is connected to the inlet end  35  of the condenser  18  and the other end  56  is connected to the arm  47 B of the second reservoir  44 . The first flow portion  46  and second flow portion  48  have equal cross-sections. Preferably, the first flow portion  46  and second flow portion  48  have equal diameter. Preferably, the first flow tube  46  and the second flow tube  48  are substantially parallel to each other. Alternatively the first flow portion  46  and the second flow portion  48  may be oriented substantially perpendicular to each other or at an angle with respect to each other. In the preferred embodiment, the second reservoir  44  has a larger cross section than the first flow portion  46  and the second flow portion  48 . Preferably, the second reservoir  44  has an increased diameter as compared to the first flow portion  46  and second flow portion  48 . 
     Preferably, as seen in FIG. 1, first flow portion  46  is of winding shape having a u-section  49 . Alternatively, the first flow portion  46  may be formed without this u-section  49 , hence resembling the first flow portion  26  of the outlet conduit  24 . In the preferred embodiment the first flow portion  46 , the second flow portion  48  and the second reservoir  44  are formed of one integral piece. In the preferred embodiment, the second reservoir  44  is made of a metallic material such as aluminum or stainless steel, preferably the same material as the compressor  16 . It is also preferred that the first flow portion  46  be made of the same metallic material as the compressor  16  and the second reservoir  44 . Alternatively, the second reservoir  44  and the first flow portion  46  may be made of a non-metallic material or a combination of a metallic and non-metallic material. The second flow portion  48  may be made of metallic material or of a non-metallic material. Preferably, the second flow portion  48  is made from a combination of metallic material and non-metallic material. Preferably the metallic portion  60  of the second flow portion  48  is connected to the second reservoir  44  and the non-metallic portion  62  is connected to the inlet end  35  of the condenser  18 . Preferably the non-metallic portion  62  of the second flow portion  48  is made of a non-conductive material such as rubber or plastic. The metallic portion  60  is preferably made of the same metallic material as the first flow tube  46  such as aluminum or steel. 
     The refrigeration system  10 , in accordance with the teachings of the present invention may include a third reservoir (not shown) formed as a part of the conduit  20 . The third reservoir like the first reservoir  26  and the second reservoir  44  is made of the same metallic material as the compressor  16 . 
     The refrigeration system  10 . in accordance with the teachings of the present invention will prevent condensation of vapor refrigerant in the compressor  16  in the following manner. Once refrigeration system  10  is turned off the compressor  16  typically is the coldest part of the refrigeration system  10 . The change in temperature will force the vapor refrigerant to flow towards the compressor  16  as the temperature continues to drop. Since the first flow portion  28 , the metallic portion  40  of the second flow portion  30 , are made of the same metallic material as the compressor  16 , they are maintained at the same temperature as the compressor  16 . Due to gravity, the vapor refrigerant flowing towards the compressor  16  comes in contact with the metallic portion  40 . of the second flow portion  30  and the vapor refrigerant will condense in the tube  30 . Similarly, the vapor present in the first flow portion  28  will condense in the first flow portion  28 . Due to drop in pressure and gravity, the condensed liquid refrigerant present in the first flow portion  28  and the second flow portion  30  will then continue to flow (as shown by arrows  51 ) towards the first reservoir  26  where it will accumulate as liquid refrigerant represented by reference numeral  39 . As discussed above since the first reservoir  26  is positioned below the compressor  16 , the liquid refrigerant will be collected in the first reservoir  26  and will be prevented from reaching the compressor  16 . 
     Similarly. the discharge conduit  24  will have a substantial amount of vapor refrigerant present when the refrigeration system is turned off. As discussed above the vapor present in the first flow portion  46  and the second flow portion  48  will flow towards the second reservoir  44  (as shown by arrows  51 ) and be collected as liquid refrigerant as indicated by reference numeral  41 . 
     When the refrigeration system  10  is operated in other words during start up, the liquid refrigerant present in the first reservoir  26  and second reservoir  44  are sucked into the accumulator  14 . When the refrigeration system  10  is operated, the refrigerant liquid is pushed toward the condenser  18 . The refrigerant liquid present in the reservoir  26  will be vaporized before reaching the compressor  16  due to the negative suction exerted upon by the compressor  16 . 
     The foregoing discussion discloses and describes a preferred embodiment of the invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that changes and modifications can be made to the invention without departing from the true spirit and fair scope of the invention as defined in the following claims.