Abstract:
An accumulator including a liquid accumulating chamber for accumulating refrigerant, a refrigerant inlet port leading the refrigerant, a refrigerant outlet pipe, an oil return opening, a refrigerant flow generating structure and a refrigerant flow mixing structure. The refrigerant outlet pipe includes an upstream open end exposed to an upper part of the liquid accumulating chamber to discharge the refrigerant from the chamber to outside the chamber. The oil return opening is in the refrigerant outlet pipe to return oil contained in the lower part of the liquid accumulating chamber to a compressor of the refrigeration cycle system. The refrigerant flow generating structure provides refrigerant from the refrigerant inlet port with a given flow, the given flow being produced by a drive force possessed by the refrigerant. The refrigerant flow mixing structure provides the given flow with an upward-and-downward movement to mix the refrigerant.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates in general to a refrigeration cycle system and more particularly to an accumulator installed in the refrigeration cycle system at a position between an evaporator and a compressor. 
         [0003]    2. Description of the Related Art 
         [0004]    In a refrigeration cycle system of vapor-compression type (or heat pump type), there is arranged an accumulator in a refrigerant flow line at a position between an evaporator and a compressor. The accumulator has basically two functions, one being to feed the compressor with gaseous refrigerant to prevent the compressor from effecting compression against liquid refrigerant, and the other being to return oil, which circulates in the refrigeration cycle circuit together with the refrigerant, to the compressor. Actually, the oil is applied to the compressor for lubricating rotating parts of the compressor. However, under operation of the refrigeration cycle system, the oil leaks into the refrigerant. 
         [0005]    One of the accumulators having such two functions is shown in Japanese Laid-open Patent Application (Tokkai) 2004-324899. 
         [0006]    In order to clarify the feature of the present invention, the accumulator of this Japanese Laid-open Patent Application will be briefly described with the aid of  FIG. 8  that shows schematically the known accumulator. 
         [0007]    In  FIG. 8 , denoted by numeral  50  is the known accumulator. When in use, the known accumulator  50  is arranged to stand upright as is shown in the drawing. 
         [0008]    The known accumulator  50  comprises a cylindrical case  52  which has a liquid accumulating chamber  51  formed therein, a refrigerant inlet pipe  53  through which refrigerant is led into the liquid accumulating chamber  51 , a refrigerant outlet pipe  54  through which the refrigerant is discharged from the liquid accumulating chamber  51  to the outside (viz., to a compressor), stirring vanes  60  which are placed in the liquid accumulating chamber  51  and rotatably disposed around the refrigerant outlet pipe  54 , and an electric drive mechanism (not shown) which turns the stirring vanes  60  with electric power. The refrigerant inlet pipe  53  has an outlet end  53   a  that is exposed to an upper part of the liquid accumulating chamber  51 , as shown. The refrigerant outlet pipe  54  has an inlet end  54   a  that is exposed to the upper part of the liquid accumulating chamber  51 . The refrigerant outlet pipe  54  is formed with a plurality of small openings  55  which serve as oil returning openings. 
         [0009]    In operation of an associated refrigeration cycle system, refrigerant is led into the liquid accumulating chamber  51  from the refrigerant inlet pipe  53  as is indicated by an arrow. The refrigerant is then temporarily accumulated in the liquid accumulating chamber  51 . During the temporal accumulation, liquid refrigerant is forced to take a lower position due to its higher specific gravity and gaseous refrigerant is forced to take a higher position due to its lower specific gravity. Since the inlet end  54   a  of the refrigerant outlet pipe  54  is kept exposed to the upper gaseous part of the liquid accumulating chamber  51 , the inlet end  54   a  sucks only the gaseous refrigerant. The gaseous refrigerant thus led into the refrigerant outlet pipe  54  is led to the compressor (not shown). During this, the liquid refrigerant placed in the lower part (which will be referred to lower liquid part hereinafter) of the liquid accumulating chamber  51  is stirred by the stirring vanes  60 . Thus, oil in the liquid refrigerant is sufficiently mixed with the liquid refrigerant. Then, a small amount of oil-mixed liquid refrigerant is led into the refrigerant outlet pipe  54  from the small openings  55  and then led to the compressor. 
         [0010]    Usually, when it is very cold, for example, when the outside air temperature is lower than −25° C., it tends to occur that oil is separated from the oil-mixed liquid refrigerant due to difference in specific gravity and viscosity. In the known accumulator, such undesired separation is suppressed by the stirring work of the stirring vanes  60 . Thus, in the known accumulator, a sufficient oil circulation rate (OCR) can be obtained in the refrigeration cycle system. 
       SUMMARY OF THE INVENTION 
       [0011]    However, in the above-mentioned known accumulator, an electric drive mechanism is used for driving the stirring vanes  60 . This means that it is necessary to provide an electric power source (or motor), a link mechanism extending between the power source and each stirring vane  60  and an electrically insulated construction for electric power transmission. Thus, the known accumulator tends to be complicated in construction and high in cost. 
         [0012]    Accordingly, it is an object of the present invention to provide an accumulator for a refrigeration cycle system, which is free of the above-mentioned drawbacks. 
         [0013]    That is, an object of the present invention is to provide an accumulator for a refrigeration cycle system, which can exhibit its essential function without the aid of electric power. 
         [0014]    Another object of the present invention is to provide an accumulator for a refrigeration cycle system, which can exhibit its essential function without inducting complicated and high cost construction. 
         [0015]    A still another object of the present invention is to provide an accumulator for a refrigeration cycle system, which can exhibit a sufficient oil circulation rate (OCR) even in a low temperature condition of an associated refrigeration cycle system. 
         [0016]    In accordance with a first aspect of the present invention, there is provided an accumulator ( 1 A,  1 B) for use in a refrigeration cycle system, which comprises a liquid accumulating chamber ( 2 ) in which refrigerant is accumulated; a refrigerant inlet port ( 4   a ) through which the refrigerant is led into the liquid accumulating chamber ( 2 ); a refrigerant outlet pipe ( 5 ) that has an upstream open end ( 5   a ) exposed to an upper part of the liquid accumulating chamber ( 2 ) to discharge the refrigerant from the liquid accumulating chamber ( 2 ) to the outside of the chamber ( 2 ); an oil return opening ( 6 ) provided in a given part of the refrigerant outlet pipe ( 5 ) to return oil, which is contained in the refrigerant in the lower part of the liquid accumulating chamber ( 2 ), to a compressor of the refrigeration cycle system; a refrigerant flow generating structure ( 10 ,  30   a ,  30   b ) that provides the refrigerant from the refrigerant inlet port ( 4   a ) with a given flow, the given flow being produced by a drive force possessed by the refrigerant; and a refrigerant flow mixing structure ( 21 ,  31 ,  32 ) that provides the given flow of refrigerant from the refrigerant flow generating structure ( 10 ,  30   a ,  30   b ) with an upward-and-downward movement thereby to mix the refrigerant. 
         [0017]    In accordance with a second aspect of the present invention, there is provided an accumulator ( 1 A,  1 B) for use in a refrigeration cycle system, which comprises a case ( 3 ) having a liquid accumulating chamber ( 2 ) defined therein, the liquid accumulating chamber ( 2 ) forming a gaseous part in an upper portion thereof and a liquid part in a lower portion thereof when the refrigeration cycle system is in operation; a refrigerant inlet pipe ( 4 ) through which refrigerant is led into the liquid accumulating chamber ( 2 ); a refrigerant outlet pipe ( 5 ) having an upstream open end ( 5   a ) exposed to the gaseous part of the liquid accumulating chamber ( 2 ), a middle part placed in the liquid part of the liquid accumulating chamber ( 2 ) and a downstream open end exposed to the outside of the case ( 3 ); a first flow guide device ( 10 ,  30   a ,  30   b ) installed in the liquid accumulating chamber ( 2 ) at a position near the refrigerant inlet pipe ( 4 ) to provide the refrigerant from the refrigerant inlet pipe ( 4 ) with a predetermined flow, the predetermined flow being produced by a kinetic energy possessed by the refrigerant; a second flow guide device ( 21 ,  31 ,  32 ) installed in the liquid accumulating chamber ( 2 ) at a position remote from the refrigerant inlet pipe ( 4 ) to provide the flow of refrigerant from the first flow guide device ( 10 ,  301 ,  30   b ) with an upward and downward movement; and an opening ( 6 ) formed in the middle part of the refrigerant outlet pipe ( 5 ) at a position near the second flow guide device ( 21 ,  31 ,  32 ) to discharge a certain small amount of refrigerant in the liquid part to the outside through the refrigerant outlet pipe ( 5 ). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    Other objects and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, in which: 
           [0019]      FIG. 1  is a perspective view of an accumulator of a first embodiment of the present invention; 
           [0020]      FIG. 2  is a sectional view of the accumulator of the first embodiment of the present invention; 
           [0021]      FIG. 3  is a plan view of a flow guide device employed in the accumulator of the first embodiment; 
           [0022]      FIG. 4A  is an enlarged sectional view of an interference ridge portion employed in the accumulator of the first embodiment; 
           [0023]      FIG. 4B  is a view similar to  FIG. 4A , but showing a modified interference ridge portion; 
           [0024]      FIG. 5  is a horizontally sectional view of an accumulator of a second embodiment of the present invention; 
           [0025]      FIG. 6  is a vertically sectional view taken along the line VI-VI of  FIG. 5 ; 
           [0026]      FIG. 7  is a perspective view of a part of the accumulator of the second embodiment showing an arrangement of flow guide members; and 
           [0027]      FIG. 8  is a vertically sectional view of a known accumulator. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    In the following, the present invention will be described in detail with reference to the accompanying drawings. 
         [0029]    For ease of understanding, in the following description, various directional terms, such as, upper, lower, right, left, upward and the like, are used. However, such terms are to be understood with respect to only a drawing or drawings on which corresponding portion or part is shown. 
       First Embodiment 
       [0030]    Referring to  FIGS. 1 to 4 , there is shown an accumulator  1 A is of a first embodiment of the present invention for a refrigeration cycle system. 
         [0031]    Like the above-mentioned known accumulator  50  of  FIG. 8 , the accumulator  1 A of the first embodiment is arranged to stand upright when in use. 
         [0032]    As is well shown in  FIGS. 1 and 2 , the accumulator  1 A comprises a cylindrical case  3  that has a cylindrical liquid accumulating chamber  2  formed therein, a refrigerant inlet pipe  4  through which refrigerant is led into the liquid accumulating chamber  2  from an evaporator (not shown), a refrigerant outlet pipe  5  through which the refrigerant is discharged from the liquid accumulating chamber  2  to the outside (viz., compressor), a flow guide device  10  which provides the refrigerant from the refrigerant inlet pipe  4  with a whirling movement and an interference ridge portion  21  which provides the whirled flow of refrigerant from the flow guide device  10  with up-and-down movement (or stirs the whirled flow of refrigerant in up-and-down direction). The refrigerant outlet pipe  5  is a straight pipe, as shown. 
         [0033]    As is seen from  FIGS. 1 and 2 , the cylindrical case  3  has an upper end closed by a circular head wall (no numeral) and a cylindrical inner surface  2   a  that constitutes an inner side wall of the liquid accumulating chamber  2 . 
         [0034]    As is seen from  FIG. 2 , the refrigerant inlet pipe  4  is integral with the upper head wall of the cylindrical case  3  and has an outlet end  4   a  exposed to an upper part of the liquid accumulating chamber  2 . 
         [0035]    As is seen from  FIGS. 1 and 2 , the outlet end  4   a  of the refrigerant inlet pipe  4  is positioned at a center of the upper head wall of the cylindrical case  3 . The refrigerant inlet pipe  4  is connected to a refrigerant outlet port of the evaporator (not shown). 
         [0036]    As is seen from  FIGS. 1 and 2 , the straight refrigerant outlet pipe  5  is arranged to pass through a center of the liquid accumulating chamber  2  and through a center of a circular bottom member  20  that is press-fitted into the lower open end of the cylindrical case  3  and fitted to the case  3  by a known connector (not shown). 
         [0037]    As is seen from  FIG. 1 , the above-mentioned interference ridge portion  21  is integrally formed on the circular bottom member  20 . The refrigerant outlet pipe  5  has an inlet end  5   a  that is exposed to the upper part of the liquid accumulating chamber  2 . 
         [0038]    As shown, the inlet end  5   a  of the refrigerant outlet pipe  5  is directed to the outlet end  4   a  of the refrigerant inlet pipe  4  keeping a given clearance therebetween. 
         [0039]    The refrigerant outlet pipe  5  is formed at a portion near the interference ridge portion  21  with a small opening  6  which serves as an oil returning opening. The refrigerant outlet pipe  5  is connected to a refrigerant inlet port of the compressor (not shown). 
         [0040]    As is seen from  FIGS. 1 ,  2  and  3 , the flow guide device  10  is a cylindrical member with an engraved upper head. As shown, the cylindrical flow guide device  10  is concentrically disposed in the upper part of the liquid accumulating chamber  2  and fixed to the circular head of the cylindrical case  3  through three screws (no numerals). Upon tight installation of the flow guide device  10 , there is defined an annular clearance “d” between the cylindrical flow guide device  10  and the cylindrical inner surface  2   a  of the case  3 , as shown. 
         [0041]    More specifically, the flow guide device  10  comprises a cylindrical side wall  12  and a circular upper head  11 . 
         [0042]    As is seen from  FIGS. 1 to 3 , the circular upper head  11  is formed at its upper surface with a recessed flow guide portion which comprises a circular center recess  11   a  that faces the outlet end  4   a  of the refrigerant inlet pipe  4  and three equally spaced curved grooves  11   b  that extend radially outward from the circular center recess  11   a  to the annular clearance “d”. 
         [0043]    As will be seen from  FIG. 2 , in operation of the associated refrigeration cycle system, refrigerant is led to the circular center recess  11   a  from the refrigerant inlet pipe  4  and then guided to flow radially outward by the three curved grooves  11   b . The refrigerant then falls into the annular clearance “d” and then into the lower part of the liquid accumulating chamber  2 . 
         [0044]    As is seen from  FIG. 1 , the interference ridge portion  21  extends diametrically on the circular bottom member  20 . The ridge portion  21  has at a middle position thereof an enlarged circular part  21   c  through which a lower part of the refrigerant outlet pipe  5  passes. 
         [0045]    As is seen from  FIG. 4A , the interference ridge portion  21  has a trapezoidal cross section and comprises a top wall  21   d  and first and second inclined side walls  21   a  and  21   b  which extend obliquely downward from the top wall  21   d , as shown. Each of the first and second inclined side walls  21   a  and  21   b  defines an obtuse angle to a base surface defined by an upper flat surface of the circular bottom member  20 . 
         [0046]    In the following, operation will be described with the aid of  FIGS. 1 ,  2  and  4 A. 
         [0047]    Under operation of the associated refrigeration cycle system, refrigerant from the evaporator (not shown) is led into the liquid accumulating chamber  2  of the accumulator  1 A through the refrigerant inlet pipe  4 . As will be easily understood from  FIGS. 1 and 2 , during this flow, the refrigerant is at first led or dropped into the circular center recess  11   a  of the flow guide device  10  and then forced to flow in the three curved grooves  11   b  by the force of its kinetic energy and its own weight. The refrigerant flowing in each curved groove  11   b  is then dropped into the liquid accumulating chamber  2  through the annular is clearance “d”. 
         [0048]    Because of the curved shape of the grooves  11   b , the refrigerant having just passed through the grooves  11   b  shows a whirling movement along the cylindrical inner surface  2   a  of the case  3  and thus, in the lower part of the case  3 , the refrigerant is whirled, as is shown in  FIG. 1 . 
         [0049]    As will be understood from  FIG. 4A , due to provision of the interference ridge portion  21 , the whirled flow of refrigerant is forced to move upward and downward thereby moving the whirled flow of refrigerant in up-and-down direction. More specifically, due to provision of the first inclined side wall  21   a , the whirled flow of refrigerant is moved upward and then due to provision of the second inclined side wall  21   b , the flow is moved downward. With such upward and downward movement of the whirled flow, the refrigerant in the lower part of the liquid accumulating chamber  2  is enforcedly mixed or stirred. 
         [0050]    Even when the outside air temperature is very low (for example, lower than −25° C.) which would induce a possibility of separation of oil from the oil-mixed liquid refrigerant in the liquid accumulating chamber  2 , such undesired oil separation is suppressed due to the enforced mixing of the oil-mixed liquid refrigerant. 
         [0051]    As is seen from  FIG. 2 , under such very cold condition, a small amount of the oil-mixed liquid refrigerant placed in the lower part of the liquid accumulating chamber  2  is permitted to flow into the refrigerant outlet pipe  5  from the small opening  6  and then led or returned to the compressor (not shown), and the gaseous refrigerant placed at the upper part of the liquid accumulating chamber  2  is led into the refrigerant outlet pipe  5  from the inlet end  5   a  and led to the refrigerant inlet port of the compressor. 
         [0052]    As will be understood from the above, in the first embodiment of the present invention, the oil-mixed liquid refrigerant in the lower part of the accumulator  1 A is effectively stirred or mixed without the aid of electric power. That is, the accumulator  1 A can be produced without inducing complicated and high cost construction, and can exhibit a sufficient oil circulation rate (OCR) even in a low temperature condition of the refrigeration cycle system. 
         [0053]    In the first embodiment, the flow guide device  10  provides the refrigerant led into the accumulator  1 A with a whirling movement by practically using the force of kinetic energy and the own weight of the refrigerant. That is, in the first embodiment, such whirling flow of refrigerant is produced by a simple construction. 
         [0054]    Because of the cylindrical inner surface  2   a  of the case  3 , the whirling flow of refrigerant produced by the flow guide device  10  is smoothly promoted. 
         [0055]    Due to provision of interference ridge portion  21 , the whirling flow of refrigerant is forced to move upward and downward and thus, the refrigerant in the liquid accumulating chamber  2  is effectively stirred and mixed. 
         [0056]    It is to be noted that the small opening  6  is provided near the interference ridge portion  21 . This is because mixing of refrigerant is most effectively carried out near the interference ridge portion  21 . Thus, the oil-mixed liquid refrigerant can be assuredly led to the compressor together with a certain amount of oil. 
         [0057]    Referring to  FIG. 4B , there is shown a modified interference ridge portion  21 A. In this modification, the second inclined side wall  21   b ′ has a vertical surface, as shown. Substantially same function as the above-mentioned interference ridge portion  21  is expected. 
       Second Embodiment 
       [0058]    Referring to  FIGS. 5 to 7 , there is shown an accumulator  1 B of a second embodiment of the present invention for a refrigeration cycle system. 
         [0059]    The accumulator  1 B of the second embodiment is arranged to stand upright when in use, like in such a posture as shown in  FIGS. 6 and 7 . 
         [0060]    As will be understood from  FIG. 5  which is a horizontally sectrional view of the accumulator  1 B, the accumulator  1 B comprises a rectangular case  3  that has a rectangular liquid accumulating chamber  2  formed therein, first and second partition walls  30   a  and  30   b  that are alternately arranged in the chamber  2  to define therein first, second and third flow passages  2   a ,  2   b  and  2   c  that are connected in series in zigzag manner, a refrigerant inlet pipe  4  through which refrigerant is led into an upstream part of the first flow passage  2   a , a refrigerant outlet pipe  5  through which the refrigerant is discharged from a downstream part of the third flow passage  2   c  to the outside, and a plurality of flow guide members  31  and  32  that are arranged in the third flow passage  2   c.    
         [0061]    As will be seen from  FIG. 6 , the refrigerant inlet pipe  4  is connected to an upper position of one side wall of the case  3  so that the refrigerant from an outlet end  4   a  of the inlet pipe  4  is fed to the first flow passage  2   a  from an upper position. Although not shown in the drawing, the refrigerant inlet pipe  4  is connected to an outlet port of an evaporator. 
         [0062]    As is best shown in  FIG. 7 , the refrigerant outlet pipe  5  is connected to a lower position of the other side wall of the case  3 . The pipe  5  has an upright portion  5   b  placed in the downstream part of the third flow passage  2   c . An inlet end  5   a  of the upright portion  5   b  is exposed to an upper part of the downstream part of the third flow passage  2   c , as shown. 
         [0063]    As is seen from  FIGS. 6 and 7 , the refrigerant outlet pipe  5  is formed at a position near a base part of the upright portion  5   b  with a small opening  6  which serves as an oil returning opening. The refrigerant outlet pipe  5  is connected to a refrigerant inlet port of a compressor (not shown). 
         [0064]    As is seen from  FIG. 5 , the first partition wall  30   a  is connected at its left end to the left side wall of the case  3  leaving the right end thereof from the right side wall of the case  3 , and the second partition wall  30   b  is connected at its right end to the right side wall of the case  3  leaving the left end thereof from the left side wall of the case  3 . With this, a sufficiently long zigzag flow passage including the first, second and third flow passages  2   a ,  2   b  and  2   c  is provided. 
         [0065]    As is understood from  FIGS. 5 to 7 , the flow guide members  31  and  32  are arranged in the third flow passage  2   c . The flow guide members  31  are secured to a larger wall of the case  3  and the other flow guide members  32  are secured to the second partition wall  30   b.    
         [0066]    As is well shown in  FIG. 7 , each flow guide member  31  or  32  is inclined in such a manner that a height of the member  31  or  32  relative to a bottom wall of the case  3  increases as a distance to the refrigerant outlet pipe  5  reduces, as shown. As is seen from the drawings, the flow guide members  31  and  32  are alternately arranged with respect a direction in which the refrigerant flows. 
         [0067]    As will be seen from  FIG. 5 , in operation of the associated refrigeration cycle system, refrigerant is led to the first flow passage  2   a  from the refrigerant inlet pipe  4  and then guided to flow in the second and third flow passages  2   b  and  2   c  in zigzag manner. That is, due to provision of the first and second partition walls  30   a  and  30   b , the refrigerant led into the liquid accumulating chamber  2  is forced to have a zigzag flow as is seen from the arrows shown in the drawing. 
         [0068]    As will be seen from  FIGS. 6 and 7 , the refrigerant led to the third flow passage  2   c  is forced to move upward and downward due to provision of the flow guide members  31  and  32 . With such upward and downward movement, the refrigerant in the third flow passage  2   c  is enforcedly mixed or stirred. 
         [0069]    Even when the outside air temperature is very low (for example, lower than −25° C.) which would induce a possibility of separation of oil from the oil-mixed liquid refrigerant in the liquid accumulating chamber  2 , such undesired oil separation is suppressed due to the enforced mixing of the oil-mixed liquid refrigerant. 
         [0070]    As is seen from  FIG. 7 , under such very cold condition, a small amount of the oil-mixed liquid refrigerant placed in the lower part of the third flow passage  2   c  is permitted to flow into the refrigerant outlet pipe  5  from the small opening  6  and then led or returned to the compressor (not shown), and the gaseous refrigerant placed at the upper part of the third flow passage  2   c  is led into the refrigerant outlet pipe  5  from the inlet end  5   a  and led to the refrigerant inlet port of the compressor. 
         [0071]    As will be understood from the above, also in the second embodiment of the present invention, the oil-mixed liquid refrigerant in the accumulator  1 B is effectively stirred or mixed without the aid of electric power. 
         [0072]    In the second embodiment, the zigzag flow of the refrigerant is easily produced by the two partition walls  30   a  and  30   b . That is, in the second embodiment, such zigzag flow of refrigerant is produced by a simple construction. 
         [0073]    Due to provision of the flow guide members  31  and  32 , the zigzag flow of refrigerant led into the third flow passage  2   c  is forced to move upward and downward and thus, the refrigerant in the liquid accumulating chamber  2  is effectively stirred and mixed. 
         [0074]    That is, the accumulator  1 B of the second embodiment can be produced without inducing complicated and high cost construction and can exhibit a sufficient oil circulation rate (OCR) even in a low temperature condition of the refrigeration cycle system. 
         [0075]    In the above-mentioned first and second embodiments 1A and 1B, the flow guide device  10  and the two partition walls  30   a  and  30   b  are used for providing the flow of refrigerant with a whirling movement and zigzag movement respectively. However, if desired, such movement may be produced by other devices. 
         [0076]    In the above-mentioned first and second embodiments 1A and 1B, the interference ridge portion  21  and the flow guide members  31  and  32  are used to move the flow of refrigerant upward and downward for effectively mixing the refrigerant in the liquid accumulating chamber  2 . However, if desired, such upward and downward movement may be produced by other devices. 
         [0077]    The entire contents of Japanese Patent Application 2010-284282 filed Dec. 21, 2010 are incorporated herein by reference. 
         [0078]    Although the invention has been described above with reference to the embodiments of the invention, the invention is not limited to such embodiments as described above. Various modifications and variations of such embodiments may be carried out by those skilled in the art, in light of the above description.