Patent Publication Number: US-9890785-B2

Title: Rotary compressor with silicon dioxide

Description:
CROSS-REFERENCE 
     This application is the U.S. National Phase under 35 U.S.C. § 371 of International Application No. PCT/JP2014/051980, filed Jan. 29, 2014, which claims the benefit of Japanese Application No. 2013-205824, filed Sep. 30, 2013, the entire contents of each are hereby incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to a rotary compressor that is used in an air conditioner or a refrigerating machine. 
     BACKGROUND ART 
     An acid material (carboxylic acid or the like produced due to degradation of lubricant oil or hydrochloric acid, hydrofluoric acid, or the like which is produced when halogen ions which are produced through chemical decomposition of molecules that make up a refrigerant react with water) inside refrigerant piping in an air conditioner, a refrigerating machine, or the like causes a copper surface of the refrigerant piping (copper piping) to become corroded and copper ions are eluted in the lubricant oil. The eluted copper ions are precipitated and adhered, in a plating manner, on a portion which becomes high in temperature, such as a sliding portion (which is made of steel or cast iron which has high ionization tendency with respect to copper) of a rotary compressor (copper plating phenomenon). 
     Progress of the copper plating phenomenon causes a gap in the sliding portion to become smaller and thus sliding friction of the rotary compressor to be increased. In addition, when the copper plating peels off, interposition of the copper plating on the sliding portion is caused and thus abnormal wear of the sliding portion may occur or an expansion valve or the like in a refrigerant circuit may become jammed. 
     In order to solve the above problems, in the related art, a refrigerating machine is disclosed, in which refrigerant is subjected to compression or expansion such that movement of heat is performed and the refrigerating machine is equipped with a zinc or zinc alloy component that removes infiltrated or produced copper ions in the refrigerant circuit (for example, see PTL 1). 
     CITATION LIST 
     Patent Literature 
     PTL 1: JP-A-5-106941 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, according to a technology in the related art disclosed in PTL 1 above, the copper ions in the refrigerant react chemically with a surface of the zinc or zinc alloy component and then, copper is precipitated on the zinc surface. As a result, molten zinc reacts with the refrigerant (for example, R22 or R410A) and then, zinc halide (for example, zinc chloride) is produced. When a temperature of the surface of the zinc or zinc alloy component exceeds the dissolution temperature of the zinc chloride, the zinc chloride dissolves in the refrigerant circuit even though the dissolution of the zinc chloride depends on refrigerant temperature distribution in the refrigerant circuit. This results in problems in that adhesion of the zinc chloride occurs in the refrigerant circuit which has a refrigerant temperature lower than the dissolution temperature and the cycle is closed. 
     The present invention is performed by taking the above problems into account and has an object to achieve a rotary compressor in which copper ions in a refrigerant circuit can be removed without producing a reaction product such as zinc chloride. 
     Solution to Problem 
     In order to solve the above problems and to achieve the object, a rotary compressor of the present invention includes: a vertically-positioned airtight compressor housing having an upper section in which a discharge portion of a refrigerant is provided and a lower section in which an inlet unit of the refrigerant is provided and lubricant oil is stored; a compressing unit that is disposed in the lower section of the compressor housing and that compresses the refrigerant sucked in via the inlet unit and discharges the refrigerant from the discharge portion; a motor that is disposed in the upper section of the compressor housing and drives the compressing unit via a rotation shaft; and an accumulator that is attached to a side section of the compressor housing and is connected to the inlet unit of the refrigerant. Inside the accumulator and/or inside the compressor housing, silicon dioxide having a crystal structure which contains a vacancy with a diameter equal to or less than a diameter of a water molecule, or a composite which includes silicon dioxide having a crystal structure which contains a vacancy with a diameter equal to or less than the diameter of the water molecule is placed. 
     Advantageous Effects of Invention 
     According to the present invention, copper ions are subjected to physisorption into a vacancy with a diameter equal to or less than a diameter of a water molecule, in a crystal structure of silicon dioxide. Hence, the effects that a reaction product such as zinc chloride is not produced, a refrigerant circuit is not closed by the reaction product, and lubricant oil is not decomposed by the reaction product are achieved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a vertical cross-sectional view illustrating an example of a rotary compressor according to the present invention. 
         FIG. 2  is a horizontal cross-sectional view of first and second compressing units according to the example when viewed from above. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an example of a rotary compressor according to the present invention will be described in detail based on the drawings. The invention is not limited to the example. 
     Example 
       FIG. 1  is a vertical cross-sectional view illustrating an example of a rotary compressor according to the present invention.  FIG. 2  is a horizontal cross-sectional view of first and second compressing units according to the example when viewed from above. 
     As illustrated in  FIG. 1 , a rotary compressor  1  of the example includes a compressing unit  12  that is disposed in the lower section of a vertically-positioned airtight compressor housing  10  which has a cylindrical shape and a motor  11  that is disposed in the upper section of the compressor housing  10  and drives the compressing unit  12  via a rotation shaft  15 . 
     A stator  111  of the motor  11  is formed in a cylindrical shape and is shrink-fitted and fixed in the inner circumferential surface of the compressor housing  10 . A rotor  112  of the motor  11  is disposed inside the cylindrical stator  111  and is shrink-fitted and fixed to the rotation shaft  15  that mechanically connects the motor  11  with the compressing unit  12 . 
     The compressing unit  12  includes a first compressing section  12 S and a second compressing section  12 T that is disposed in parallel with the first compressing section  12 S and is stacked on the first compressing section  12 S. As illustrated in  FIG. 2 , the first and second compressing units  12 S and  12 T include annular first and second cylinders  121 S and  121 T in which first and second inlet holes  135 S and  135 T that are radially disposed and first and second vane grooves  128 S and  128 T are provided in first and second side-flared portions  122 S and  122 T. 
     As illustrated in  FIG. 2 , circular first and second cylinder inner walls  123 S and  123 T are formed in the first and second cylinders  121 S and  121 T so as to be concentric with the rotation shaft  15  of the motor  11 . First and second annular pistons  125 S and  125 T which have an outer diameter smaller than an inner diameter of the cylinder are provided inside the first and second cylinder inner walls  123 S and  123 T, respectively. First and second operation chambers  130 S and  130 T which suck in, compress, and discharge a refrigerant gas are formed between the first and second cylinder inner walls  123 S and  123 T and the first and second annular pistons  125 S and  125 T. 
     The first and second vane grooves  128 S and  128 T are formed over the entire cylinder height of the first and second cylinders  121 S and  121 T in a radial direction from the first and second cylinder inner walls  123 S and  123 T. First and second vanes  127 S and  127 T, each of which has a plate shape, are slidably fit in the first and second vane grooves  128 S and  128 T. 
     As illustrated in  FIG. 2 , first and second spring bores  124 S and  124 T are formed in a deep portion of the first and second vane grooves  128 S and  128 T such that communication from the outer circumferential portions of the first and second cylinders  121 S and  121 T to the first and second vane grooves  128 S and  128 T is performed. First and second vane springs (not illustrated) which press the back surface of the first and second vanes  127 S and  127 T are inserted into the first and second spring bores  124 S and  124 T. 
     When the rotary compressor  1  is started, the first and second vanes  127 S and  127 T protrude from the inside of the first and second vane grooves  128 S and  128 T to the inside of the first and second operation chambers  130 S and  130 T due to bounces of the first and second vane springs and ends of the vanes come into contact with the outer circumferential surfaces of the first and second annular pistons  125 S and  125 T. This allows the first and second vanes  127 S and  127 T to partition the first and second operation chambers  130 S and  130 T into first and second inlet chambers  131 S and  131 T and first and second compression chambers  133 S and  133 T. 
     In addition, the refrigerant gas compressed in the compressor housing  10  is guided into the first and second cylinders  121 S and  121 T by communicating the deep portion of the first and second vane grooves  128 S and  128 T with the inside of the compressor housing  10  via an opening R illustrated in  FIG. 1 . In this manner, First and second pressure guiding-in paths  129 S and  129 T which cause back pressures to be applied by the pressure of the refrigerant gas are formed in the first and second vanes  127 S and  127 T. 
     The first and second inlet holes  135 S and  135 T which cause the first and second inlet chambers  131 S and  131 T to communicate with the outside are provided in the first and second cylinders  121 S and  121 T such that a refrigerant is sucked into the first and second inlet chambers  131 S and  131 T from the outside. 
     In addition, as illustrated in  FIG. 1 , an intermediate partition plate  140  is disposed between the first cylinder  121 S and the second cylinder  121 T and partitions and closes the first operation chamber  130 S (refer to  FIG. 2 ) of the first cylinder  121 S from the second operation chamber  130 T (refer to  FIG. 2 ) of the second cylinder  121 T. A lower end plate  160 S is disposed on a lower end portion of the first cylinder  121 S and closes the first operation chamber  130 S of the first cylinder  121 S. In addition, an upper end plate  160 T is disposed on an upper end portion of the second cylinder  121 T and closes the second operation chamber  130 T of the second cylinder  121 T. 
     A sub-bearing unit  161 S is formed on the lower end plate  160 S and a sub-shaft unit  151  of the rotation shaft  15  is rotatably supported in the sub-bearing unit  161 S. A main-bearing unit  161 T is formed on the upper end plate  160 T and a main-shaft unit  153  of the rotation shaft  15  is rotatably supported in the main-bearing unit  161 T. 
     The rotation shaft  15  includes a first eccentric portion  152 S and a second eccentric portion  152 T which are eccentric by a 180° phase shift from each other. The first eccentric portion  152 S is rotatably fit in the first annular piston  125 S of the first compressing unit  12 S. The second eccentric portion  152 T is rotatably fit in the second annular piston  125 T of the second compressing unit  12 T. 
     When the rotation shaft  15  rotates, the first and second annular pistons  125 S and  125 T make orbital motions inside the first and second cylinders  121 S and  121 T along the first and second cylinder inner walls  123 S and  123 T in a counterclockwise direction in  FIG. 2 . Accordingly, the first and second vanes  127 S and  127 T perform reciprocal motions. The motions of the first and second annular pistons  125 S and  125 T and the first and second vanes  127 S and  127 T cause volumes of the first and second inlet chambers  131 S and  131 T and the first and second compression chambers  133 S and  133 T to be continually changed. In this manner, the compressing unit  12  continually sucks in, compresses, and discharges the refrigerant gas. 
     As illustrated in  FIG. 1 , a lower muffler cover  170 S is disposed on the lower side of the lower end plate  160 S and a lower muffler chamber  180 S is formed between the lower end plate  160 S and the lower muffler cover  170 S. The first compressing unit  12 S opens to the lower muffler chamber  180 S. That is, a first outlet  190 S (refer to  FIG. 2 ) through which the first compression chamber  133 S of the first cylinder  121 S communicates with the lower muffler chamber  180 S is provided in the vicinity of the first vane  127 S of the lower end plate  160 S. In addition, a first discharge valve  200 S which prevents the compressed refrigerant gas from flowing backward is disposed in the first outlet  190 S. 
     The lower muffler chamber  180 S is a single annular chamber. The lower muffler chamber  180 S is a part of a communication path through which a discharge side of the first compressing unit  12 S communicates with the inside of the upper muffler chamber  180 T by passing through a refrigerant path  136  (refer to  FIG. 2 ) which penetrates the lower end plate  160 S, the first cylinder  121 S, the intermediate partition plate  140 , the second cylinder  121 T and the upper end plate  160 T. The lower muffler chamber  180 S causes pressure pulsation of the discharged refrigerant gas to be reduced. In addition, a first discharge valve cover  201 S which controls an amount of flexural valve opening of the first discharge valve  200 S is stacked on the first discharge valve  200 S and is fixed to the first discharge valve  200 S using a rivet. The first outlet  190 S, the first discharge valve  200 S, and the first discharge valve cover  201 S configure a first discharge valve unit of the lower end plate  160 S. 
     As illustrated in  FIG. 1 , an upper muffler cover  170 T is disposed on the upper side of the upper end plate  160 T and an upper muffler chamber  180 T is formed between the upper end plate  160 T and the upper muffler cover  170 T. A second outlet  190 T (refer to  FIG. 2 ) through which the second compression chamber  133 T of the second cylinder  121 T communicates with the upper muffler chamber  180 T is provided in the vicinity of the second vane  127 T of the upper end plate  160 T. A reed valve type second discharge valve  200 T which prevents the compressed refrigerant gas from flowing backward is disposed in the second outlet  190 T. In addition, a second discharge valve cover  201 T which controls an amount of flexural valve opening of the second discharge valve  200 T is stacked on the second discharge valve  200 T and is fixed using a rivet with the second discharge valve  200 T. The upper muffler chamber  180 T causes pressure pulsation of discharged refrigerant to be reduced. The second outlet  190 T, the second discharge valve  200 T, and the second discharge valve cover  201 T configure a second discharge valve unit of the upper end plate  160 T. 
     The first cylinder  121 S, the lower end plate  160 S, the lower muffler cover  170 S, the second cylinder  121 T, the upper end plate  160 T, the upper muffler cover  170 T, and the intermediate partition plate  140  are integrally fastened using a plurality of penetrating bolts  175  or the like. The outer circumferential portion of the upper end plate  160 T of the compressing unit  12  which is integrally fastened using the penetrating bolts  175  or the like is firmly fixed to the compressor housing  10  through spot welding such that the compressing unit  12  is fixed to the compressor housing  10 . 
     First and second through holes  101  and  102  are provided in the outer-side wall of the cylindrical compressor housing  10  at an interval in an axial direction in this order from a lower section thereof so as to communicate with first and second inlet pipes  104  and  105 , respectively. In addition, outside the compressor housing  10 , an accumulator  25  which is formed of a separate airtight cylindrical container is held by an accumulator holder  252  and an accumulator band  253 . 
     A system connecting pipe  255  which is connected to an evaporator in a refrigeration cycle is connected at the center of the top portion of the accumulator  25 . First and second low-pressure communication tubes  31 S and  31 T, each of which has one end extending toward the upward side inside the accumulator  25 , and which have the other ends connected to the other end of each of the first and second inlet pipes  104  and  105 , are connected to a bottom through hole  257  provided in the bottom of the accumulator  25 . 
     The first and second low-pressure communication tubes  31 S and  31 T which guide a low pressure refrigerant in the refrigeration cycle to the first and second compressing units  12 S and  12 T via the accumulator  25  are connected to the first and second inlet holes  135 S and  135 T (refer to  FIG. 2 ) of the first and second cylinders  121 S and  121 T via the first and second inlet pipes  104  and  105  as an inlet unit. That is, the first and second inlet holes  135 S and  135 T are connected to the evaporator of the refrigeration cycle in parallel. 
     A discharge pipe  107  as a discharge portion which is connected to the refrigeration cycle and discharges a high pressure refrigerant gas to a side of a condenser in the refrigeration cycle is connected to the top portion of the compressor housing  10 . That is, the first and second outlets  190 S and  190 T are connected to the condenser in the refrigeration cycle. 
     Lubricant oil is sealed in the compressor housing  10  substantially to the elevation of the second cylinder  121 T. In addition, the lubricant oil is sucked up from a lubricating pipe  16  attached to the lower end portion of the rotation shaft  15 , using a pump blade (not illustrated) which is inserted into the lower section of the rotation shaft  15 . The lubricant oil circulates through the compressing unit  12 , sliding components are lubricated, and the lubricant oil seals a fine gap in the compressing unit  12 . 
     Next, a characteristic configuration of the rotary compressor of the example will be described with reference to  FIG. 1 . As illustrated in  FIG. 1 , on the bottom of the accumulator  25 , silicon dioxide (silica)  27  having a crystal structure which contains a vacancy (for example, a diameter is 0.3 nm) with a diameter equal to or less than a diameter (0.38 nm) of a water molecule, or a composite that includes silicon dioxide having a crystal structure which contains a vacancy with a diameter equal to or less than the diameter of the water molecule is placed. The silicon dioxide  27  having the crystal structure which contains the vacancy with the diameter equal to or less than the diameter of the water molecule, or the composite  27  that includes the silicon dioxide having the crystal structure which contains the vacancy with the diameter equal to or less than the diameter of the water molecule may be placed inside the compressor housing  10 . In addition, the silicon dioxide  27  having the crystal structure which contains the vacancy with the diameter equal to or less than the diameter of the water molecule or the composite  27  that includes the silicon dioxide having the crystal structure which contains the vacancy with the diameter equal to or less than the diameter of the water molecule may be placed both inside the accumulator  25  and inside the compressor housing  10 . 
     Further, the silicon dioxide  27  having the crystal structure which contains the vacancy with the diameter equal to or less than the diameter of the water molecule, or the composite  27  that includes the silicon dioxide having the crystal structure which contains the vacancy with the diameter equal to or less than the diameter of the water molecule may be placed on and may coat an inner wall surface of the accumulator  25  and/or an inner wall surface of the compressor housing  10 . 
     It is known that eluted copper ions become trapped (adsorbed) into the silicon dioxide. However, the surface contact area acquired only by the silicon dioxide is small and thus, the effect of trapping the copper ions is small. Therefore, the composite  27  that includes the silicon dioxide is placed inside the accumulator  25  and/or inside the compressor housing  10 . This causes the eluted copper ions in the lubricant oil to be trapped and thus, it is possible to prevent the sliding portion of the compressing unit  12  from being plated with copper. 
     Crystalline synthetic zeolites {trade name: molecular sieve: general formula=M 2/n O.Al 2 O 3 .xSiO 2 .yH 2 O (M: metallic cation and n: valence)} which are used as a desiccant that removes water in the refrigeration cycle include the silicon dioxide. However, the synthetic zeolites are the desiccant and thus have large vacancies that are suitable for trapping water. Therefore, when a great amount of water is present in the refrigeration cycle, water is trapped before the copper ions are trapped and it is not possible for the synthetic zeolites to achieve an effect of sufficiently preventing copper plating. 
     The diameter of the water molecule is about 0.38 nm and a molecular diameter of a copper ion is about 0.128 nm. Therefore, the size (diameter) of the vacancy of the composite  27  including the silicon dioxide is set to a size (for example, 0.3 nm or less) so that water is not trapped. In this manner, it is possible for only the copper ions to be trapped in the vacancy and it is possible to prevent the sliding portion of the compressing unit  12  from being plated with copper. 
     Particularly, when the silicon dioxide  27  having the crystal structure which contains a vacancy of 0.3 nm or less, or the composite  27  that includes the silicon dioxide having the crystal structure which contains a vacancy of 0.3 nm or less is placed inside the accumulator  25 , it is possible to trap copper ions in the refrigerant which has not yet flowed into the compressing unit  12  of the rotary compressor  1  and it is highly effective to prevent the copper plating. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  rotary compressor 
               10  compressor housing 
               11  motor 
               12  compressing unit 
               15  rotation shaft 
               16  lubricating pipe 
               25  accumulator 
               27  silicon dioxide having a crystal structure which contains a vacancy of 0.3 nm or less or a composite which includes silicon dioxide having a crystal structure which contains a vacancy of 0.3 nm or less 
               31 S first low-pressure communication tube 
               31 T second low-pressure communication tube 
               101  first through hole 
               102  second through hole 
               104  first inlet pipe (inlet unit) 
               105  second inlet pipe (inlet unit) 
               107  discharge pipe (discharge portion) 
               111  stator 
               112  rotor 
               12 S first compressing unit 
               12 T second compressing unit 
               121 S first cylinder (cylinder) 
               121 T second cylinder (cylinder) 
               122 S first side-flared portion 
               122 T second side-flared portion 
               123 S first cylinder inner wall (cylinder inner wall) 
               123 T second cylinder inner wall (cylinder inner wall) 
               124 S first spring bore 
               124 T second spring bore 
               125 S first annular piston (annular piston) 
               125 T second annular piston (annular piston) 
               127 S first vane (vane) 
               127 T second vane (vane) 
               128 S first vane groove (vane groove) 
               128 T second vane groove (vane groove) 
               129 S first pressure guiding-in path 
               129 T second pressure guiding-in path 
               130 S first operation chamber (operation chamber) 
               130 T second operation chamber (operation chamber) 
               131 S first inlet chamber (inlet chamber) 
               131 T second inlet chamber (inlet chamber) 
               133 S first compression chamber (compression chamber) 
               133 T second compression chamber (compression chamber) 
               135 S first inlet hole (inlet hole) 
               135 T second inlet hole (inlet hole) 
               136  refrigerant path 
               140  intermediate partition plate 
               151  sub-shaft unit 
               152 S first eccentric portion (eccentric portion) 
               152 T second eccentric portion (eccentric portion) 
               153  main-shaft unit 
               160 S lower end plate (end plate) 
               160 T upper end plate (end plate) 
               161 S sub-bearing unit 
               161 T main-bearing unit 
               170 S lower muffler cover 
               170 T upper muffler cover 
               175  penetrating bolt 
               180 S lower muffler chamber 
               180 T upper muffler chamber 
               190 S first outlet (outlet) 
               190 T second outlet (outlet) 
               200 S first discharge valve 
               200 T second discharge valve 
               201 S first discharge valve cover 
               201 T second discharge valve cover 
               252  accumulator holder 
               253  accumulator band 
               255  system connecting pipe 
             R opening