Abstract:
An accumulator for an air conditioning system has a passage for oil to travel from an orifice to an outlet. To improve the percentage of oil flowing from the orifice to the outlet and/or the rate of flow, one or more oil vanes extend from or near the orifice to or near the outlet. Alternatively, instead of oil vanes, indentations could be used.

Description:
FIELD OF THE INVENTION  
       [0001]     The invention relates to suction accumulators for refrigeration or air/conditioning system use.  
       BACKGROUND OF THE INVENTION  
       [0002]     Closed-loop refrigeration systems conventionally employ a compressor that is meant to draw in gaseous refrigerant at relatively low pressure and discharge hot refrigerant at relatively high pressure. The hot refrigerant condenses into liquid as it is cooled in a condenser. A small orifice or valve divides the system into high and low-pressure sides. The liquid on the high-pressure side passes through the orifice or valve and turns into a gas in the evaporator as it picks up heat. (Some systems operate in “transcritical” mode, in that the hot refrigerant is merely cooled in a high side heat exchanger, now termed a “gas cooler”, and turns to gas plus liquid as it passes through the expansion device.) At low heat loads, it is not desirable or possible to evaporate all the liquid in the evaporator. However, excess liquid refrigerant entering the compressor (known as “slugging”) causes system efficiency loss and can cause damage to the compressor. Hence it is standard practice to include a reservoir between the evaporator and the compressor to separate and store the excess liquid. It is also a reservoir for excess refrigerant, which is typically added to the system during manufacture to compensate for unavoidable leakage during the working life of the system. This reservoir is called a suction line accumulator, or simply an accumulator.  
         [0003]     An accumulator is typically a metal can, welded together, and often has fittings attached for a switch, transducer and/or charge port. One or more inlet tubes and an outlet tube pierce the top, sides, or occasionally the bottom, or attach to fittings provided for that purpose. The refrigerant flowing into a typical accumulator will impinge upon a deflector or baffle intended to reduce the likelihood of liquid flowing out the exit, generally by removing kinetic energy from the liquid so it settles quietly into the reservoir area without churning or splashing.  
         [0004]     A consequence of using a suction line accumulator is that compressor oil can become trapped within it. Compressor oil is circulated with the refrigerant in most systems in current usage. Even if a separator is used, a small amount of oil escapes into the system. This oil will find its way into the accumulator, and while liquid refrigerant may be expected to evaporate and return to circulation as needed, the oil does not evaporate. Some means must be provided to return this oil to circulation. A known practice is to use a J-shaped outlet tube to carry the exiting gaseous refrigerant from the top of the accumulator down to the bottom and then back up to the outlet from the accumulator. A carefully sized orifice at the bottom of this “J-tube” entrains the oil from the bottom of the liquid area into the stream of exiting gas. Generally, the orifice has a filter around it, and the filter may extend into a sump formed in the bottom of the accumulator to collect the oil-rich liquid. The. J-tube also typically has a hole near the top, which prevents the liquid from siphoning or flowing out of the accumulator reservoir when the system is switched off. The size of the hole is a balance between breaking any siphon and reducing the effectiveness of oil pickup.  
         [0005]     A recent development in accumulator design is to incorporate a plastic liner in the accumulator to assist with the oil pick up function (as shown, for example, in U.S. Pat. No. 06,612,128, U.S. Pat. No. 06,463,757). However, existing designs and literature do not teach how to optimize or improve the oil entraining function, especially for those cases where the refrigerant flow is the reverse of the flow in most previous accumulators using liners.  
         [0006]     While previous accumulator designs have sought to return oil to the compressor, the previous designs do not appear to have considered improving the rate at which oil is returned to the compressor. As well, it would also be desirable to increase the amount of oil returned to the compressor and reduce the amount of liquid refrigerant flowing to the compressor.  
       SUMMARY OF THE INVENTION  
       [0007]     According to one embodiment of the present invention relating to a liner-style accumulator, one or more vanes may protrude from an outer surface of the liner, from or near an oil bleed orifice and extend upward towards an outlet. The vanes provide a path or channel for the oil exiting the oil bleed orifice to follow towards the outlet of the accumulator. Gaseous refrigerant with metered liquid will then exit the accumulator through the outlet.  
         [0008]     Embodiments of the accumulators and related designs described herein may be used in air conditioning systems within vehicles. Embodiments of the accumulators and related designs described herein could also be used in stationary commercial or industrial air conditioning systems.  
         [0009]     According to a further aspect, the invention provides an accumulator for an air conditioning system comprising an outlet, a passage for oil to travel towards the outlet, an orifice to allow oil to enter the passage, and one or more oil vanes projecting from a surface of the passage, but not projecting across the passage, the one or more oil vanes extending from or near the orifice towards the outlet.  
         [0010]     According to a further aspect, the invention provides an accumulator for an air conditioning system comprising an outlet, a passage for oil to travel towards the outlet, an orifice to allow oil to enter the passage, and one or more indentations formed within a surface of the passage, the one or more indentations extending from or near the orifice towards the outlet.  
         [0011]     Advantageously, different embodiments of the present invention may provide some of the following: an accumulator having a liner, where the liner has vanes to help direct oil to an outlet which may allow for the size of an oil bleed orifice to be reduced, which thereby reduces the amount of liquid refrigerant entering the compressor, which thereby improves system performance; an accumulator which more efficiently returns oil to the compressor; an accumulator which returns oil to the compressor at a more predictable rate; an accumulator which returns more oil to the compressor with proportionally less liquid refrigerant; an accumulator providing improved performance; an accumulator which is more cost-effective.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     Preferred embodiments of the invention will now be described with reference to the attached drawings in which  
         [0013]      FIG. 1   a  is a perspective view of a liner-style, side-in-side-out (SISO) accumulator (with some of the internal components shown in dotted outline) in accordance with an embodiment of the present invention;  
         [0014]      FIG. 1   b  is a vertical sectional view of the accumulator of  FIG. 1   a , with arrows showing the direction of flow within the accumulator;  
         [0015]      FIG. 1   c  is an exploded view of the accumulator of  FIG. 1   a , in which the oil vanes on the liner are visible;  
         [0016]      FIG. 2  is a perspective view of the liner of  FIG. 1   c.   
     
    
     DETAILED DESCRIPTION  
       [0017]     An embodiment of an accumulator  20  is shown in  FIGS. 1   a - 1   c . The accumulator  20  has an outer surface or housing formed by a top canister  22  ( FIG. 1   c ) and a bottom canister  24 . The top canister  22  fits securely and sealingly with the bottom canister  24 . The top canister  22  comprises and inlet fitting  26  ( FIG. 1   b ) and an outlet fitting  30 . In this embodiment, both the inlet fitting  26  and the outlet fitting  30  extend from or are formed in the side(s) of the top canister  22 . The inlet fitting is adapted to accommodate an inlet tube or conduit  28 . The outlet fitting  30  is adapted to accommodate an outlet conduit (not shown). The bottom canister  24  is generally cylindrical, with a closed bottom or floor  32  and an open top.  
         [0018]     Within the accumulator  20  depicted in  FIGS. 1   a - 1   c , is a liner  36 , which is secured within the bottom canister  24  of the accumulator  20 , a deflector  40 , which is secured near a top portion of the accumulator  20 , and a gas flow tube or conduit  42 , which extends within the accumulator  20 , partway along the height of the accumulator  20 . The accumulator may also incorporate a desiccant container  44 , among other features.  
         [0019]     As shown in  FIG. 2 , the liner  36  is generally cylindrical, having an outer surface  46 , with a diameter slightly less than that of the bottom canister  24 . The top of the liner is open. In this embodiment, a hole  48  is located near the top of the liner  36 . (In other embodiments and accumulator designs, the hole  48  could be omitted.) From the top of the liner  36 , the outer surface  46  extends downward. Near a bottom portion of the liner  36 , the outer surface  46  extends inwardly to a nadir. From or near the nadir, the outer surface  46  extends inwardly and upwardly, to form a generally circular liner outlet  50 . Formed within the liner  36 , advantageously at or near the nadir of the liner  36 , is an oil bleed orifice  52 . (Different embodiments could incorporate two or more oil bleed orifices.) Extending along, and spaced evenly around the outer surface  46  of the liner  36  in this embodiment, are liner ribs  54 . Oil vanes or oil ribs  56  extend from or near the oil bleed orifice  50  up along the outer surface  46  of the liner  36  towards the outlet. In this embodiment, the oil vanes extend to or near the outlet. The liner ribs  54  project outward further than the oil vanes  56 . There may be one or more oil vanes  56 . Advantageously, in the embodiment depicted, there are two oil vanes  56 , on opposite edges of the oil bleed orifice  52 .  
         [0020]     In this embodiment, the liner ribs  54  and the oil vanes  56  extend longitudinally upward along the outer surface  46  of the liner  36 . However, the liner ribs  54  and the oil vanes  56  could also extend upward in a helical fashion (not shown) or in another fashion.  
         [0021]     The accumulator  20  is assembled as generally suggested by  FIG. 1   c . The accumulator  20  may be assembled as follows. The desiccant container  44  is lowered into the liner  36 . The outer surface of the desiccant container  44  and the inner surface of the liner  36  are adapted to ensure that no fluid can flow between them. For example, the inner surface of the liner  36  may incorporate a small horizontal half bead (not shown), to provide a tight seal between the two surfaces. Many other techniques could be used to achieve the same result.  
         [0022]     The gas flow tube  28  is then inserted through the opening formed within the desiccant container  44 . The outer diameter of the gas flow tube  28  is sized such that it is slightly smaller than the inner diameter of the opening formed within the desiccant container  44 , but still forms a tight seal between the two surfaces.  
         [0023]     The deflector  40 , in this embodiment, is secured to the ceiling of the top canister  22 .  
         [0024]     The liner  36  is then placed within the bottom canister  24 . There is a gap or passage between an inside surface of the bottom canister  24  and the outer surface  46  of the liner  36  defined (in this embodiment) by the extent to which the liner ribs  54  project from the outer surface  46 .  
         [0025]     The top canister  22  is secured to the bottom canister  24 . The top canister  22  and the bottom canister  24  may be made of aluminum or steel, for example, and welded together to form a hermetic seal.  
         [0026]     In this embodiment, the top of the liner  36  extends to the ceiling of the top canister  22 . The hole  48  in the liner  36  is oriented in line with the inlet tube  28 . The inlet tube  28  passes through the hole  48  in the liner  36  (or the inlet tube  28  is sealingly secured to the hole  48  in the liner  36 ).  
         [0027]     In operation, fluid enters the accumulator  20  through the inlet tube  28 . The fluid passes through the hole  48  in the liner  36 . The arrows shown in  FIG. 1   b  illustrate the movement of the different components of the fluid. The fluid comprises liquid refrigerant, gaseous refrigerant (“gas”) and oil. The fluid entering the accumulator  20  flows against the deflector  40 . The deflector  40  acts as a barrier to prevent liquid refrigerant and oil from entering the gas flow tube  42 . The gaseous refrigerant is separated from the liquid refrigerant and oil. The liquid refrigerant and oil after contacting the deflector  40  flow downward due to gravity. The liquid refrigerant and oil pass through the desiccant container  44 , which removes moisture from the liquid, and the liquid then settles on the floor of the liner  36 .  
         [0028]     Meanwhile, the gas flows towards the gas flow tube  42 . The gaseous refrigerant flows into the entrance of the gas flow tube  42  and then down the gas flow tube  42 . After leaving the gas flow tube  42 , the gaseous refrigerant then flows through the gap between the liner  36  and the bottom canister  24 . Accordingly, the gas flows below the liner  36  and then up to the outlet fitting  30 , whereupon, the gaseous refrigerant exits the accumulator though the outlet conduit (not shown). As the gaseous refrigerant flows past the oil bleed orifice  52  near the nadir of the liner  36 , oil (and possibly some liquid refrigerant) passes through the oil bleed orifice  52  and is entrained within the flow of gaseous refrigerant. As well, the oil vanes  56  provide a direct path between the oil bleed orifice  52  and the outlet fitting  30 . The oil vanes  56  improve the flow of oil from the oil bleed orifice  52  up the liner  36 . When oil exits the oil bleed orifice  52  it is immediately contained in the oil vanes  56  and is channeled up the side of the liner  36  by the passing gaseous refrigerant. The channeling effect helps maintain a constant and predictable stream of oil from the oil bleed orifice  52  to the outlet fitting  30 . Some oil is entrained in the gaseous refrigerant and some oil is pulled up along or between the oil vanes  56  through suction or is dragged by the flowing gaseous refrigerant. The oil vanes  56  also help increase the amount of oil exiting the accumulator and thereby allow a reduction in the size of the oil bleed orifice  52 . This, in turn, limits the amount of liquid refrigerant that exits the oil bleed orifice  52  and therefore limits the amount of liquid refrigerant entering the compressor.  
         [0029]     In the above-noted embodiment, the oil vanes  56  extend or protrude from the outer surface  46  of the liner  36 . Alternately, the oil vanes  56  could instead protrude or extend inwardly from an inner surface of the bottom canister  24 .  
         [0030]     The embodiments described above relate to a side-in-side-out (SISO) liner-style accumulator. However, the principles described above could also be applied to accumulators having other configurations, such as a top-in-side-out (TISO) accumulator or indeed other configurations as well as non-liner style accumulators.  
         [0031]     For example, the oil vanes described above could be applied to a J-tube (or U-tube) style accumulator (not shown). The J-tube incorporates an orifice which permits oil to enter the J-tube. In the case of a J-tube style accumulator, oil vanes project inside the J-tube and extend from or near the orifice to or near an outlet. The interior of the J-tube may be referred to as a “passage.” The embodiments mentioned above describe oil vanes projecting from a surface. In another embodiment, the relevant surface could incorporate indentations or depressions instead of oil vanes. In that case, oil would flow along or within or would be directed by the oil indentation(s), toward the outlet.  
         [0032]     The embodiments described above relate to liner-style accumulators and J-tube-style accumulators. However, the principles described herein could also be applied to other styles of accumulators including trumpet tube-style accumulators (which have a J-tube with a return down to the bottom of the accumulator (not shown)) and pick-up tube-style accumulators (not shown). In such cases, oil vanes or indentations would project within a passage (a J-tube, or a trumpet tube, or a pick-up tube, or a centre tube, etc.) and extend advantageously, from or near an orifice in the passage (where oil enters the passage) towards an outlet in the accumulator.  
         [0033]     Numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. For example, in the embodiments described above, an orifice is described as being formed within a surface, and projections or indentations extend along a particular surface to or near an outlet. Instead of the oil vanes or indentations extending along a single surface, the oil vanes or indentations could extend along two or more adjacent surfaces. Similarly, the oil vanes or indentations could be formed within a surface adjacent to a surface having the orifice, instead of the same surface having the orifice. Accordingly, when the term “surface” is used herein, it is intended to cover all of the alternative embodiments described herein.