Patent Publication Number: US-9416681-B2

Title: Turbo compressor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Continuation Application of PCT International Application No. PCT/JP2012/067339 (filed on Jul. 6, 2012), which is based upon and claims the benefit of priority from Japanese Patent Application No. 2011-154647 (filed on Jul. 13, 2011), the entire contents of which are incorporated herein with reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a turbo compressor capable of compressing fluid by its plural impeller. 
     2. Background Art 
     As a conventional turbo compressor to be applied to a turbo refrigerator or the like, one disclosed in a Patent Document 1 (Japanese Patent Application Laid-Open No. 2011-26960) is known. The turbo compressor includes a housing in which lubrication oil is accumulated, a large-diameter gear housed in the housing, and a demister disposed above the large-diameter gear in the housing. The large-diameter gear supplies the lubrication oil by its rotations. The demister is provided with intakes communicating with an outside of the housing. The demister catches oil mist of the lubrication oil splashed by rotations of the large-diameter gear to return it to a lower portion of the housing. 
     In the turbo compressor, the intakes of the demister are connected with a lower-pressure space than an inside of the housing via a pressure equalizing pipe, and thereby pressure rise in the housing is restricted. In addition, the oil mist of the lubrication oil is generated in the housing by the rotations of the large-diameter gear. Therefore, the demister catches the oil mist when inside air in the housing is inhaled from the intakes and returns it to the lower portion of the housing in order to prevent the lubrication oil from being discharged out from the housing. 
     SUMMARY OF INVENTION 
     However, in the above turbo compressor, there is a possibility that the demister cannot catch the lubrication oil completely if the lubrication oil passing through the demister is too much, and thereby the lubrication oil may be discharged out from the housing. 
     An object of the present invention is to provide a turbo compressor that can reduce an amount of lubrication oil passing through a demister. 
     An aspect of the present invention provides a turbo compressor comprising: a housing in which lubrication oil is accumulated; a gear that is housed in the housing and to which the lubrication oil is supplied; a demister that is disposed above the gear and on which an intake is provided to catch oil mist of the lubrication oil in the housing; a gear cover that is provided surrounding the gear to catch lubrication oil splashed by the gear and then drip the caught lubrication oil downward; and a demister cover that is disposed near the demister to drip the lubrication oil caught by the demister downward, wherein a narrow gap is formed between the demister cover and an inner wall surface of the housing. 
     Since the gear cover that drips the lubrication oil splashed by the gear downward is provided so as to surround the gear in the turbo compressor, a distance between the lubrication oil accumulated at a lower portion of the housing and the demister can be made long and thereby the lubrication oil is restricted from reaching the demister. 
     In addition, since the demister cover for dripping the lubrication oil caught by the demister downward is provided near the demister, lubrication oil that is not caught by the gear cover can be restricted from reaching the intake by the demister cover. 
     Therefore, according to the turbo compressor, an amount of lubrication oil that reaches the demister can be reduced by the gear cover and the demister cover. 
     Here, it is preferable that a lower end edge of the gear cover counter to a rotational direction of the gear is extended downward further than an opposed-side lower end edge. According to this, spatters of the lubrication oil can be restricted effectively on a predominant side of the lubrication oil splashed by the gear. In addition, the gear cover can be light-weighted because the opposed-side lower end edge is made minimum. 
     In addition, it is preferable that a total area of the narrow gap is made larger than an opening area of the intake of the demister. According to this, an amount of lubrication oil that reaches the demister can be reduced by the demister cover without degrading inhale performance of the demister. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of a turbo refrigerator including a turbo compressor according to an embodiment; 
         FIG. 2  is a cross-sectional view of the turbo compressor; 
         FIG. 3  is a cross-sectional view taken along a line shown in  FIG. 2 ; 
         FIG. 4  is a perspective view of a demister and a demister cover of the turbo compressor; and 
         FIG. 5  is a perspective view of a gear cover of the turbo compressor. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     First, a turbo refrigerator  101  to which a turbo compressor  1  according to an embodiment is applied will be explained with reference to  FIG. 1 . 
     As shown in  FIG. 1 , the turbo refrigerator  101  is an apparatus for preparing coolant for air conditioning. The turbo refrigerator  101  includes a condenser  103 , an economizer  105 , an evaporator  107 , and the turbo compressor  1 . 
     The condenser  103  is connected with the turbo compressor  1  via a flow path F 1 , and connected with the economizer  105  via a flow path F 2  on which an expansion valve (pressure reduction valve)  109  is provided. Refrigerant gas C 1  compressed by the turbo compressor  1  is supplied to the condenser  103  through the flow path F 1 , and the condenser  103  condenses the compressed refrigerant gas into refrigerant liquid C 2  (some remains as refrigerant gas). The refrigerant liquid C 2  condensed by the condenser  103  is decompressed by the expansion valve  109  on the flow path F 2 , and then supplied to the economizer  105 . 
     The economizer  105  is connected with the turbo compressor  1  via a flow path F 3 , and connected with the evaporator  107  via a flow path F 4  on which an expansion valve (pressure reduction valve)  111  is provided. The economizer  105  temporarily accumulates the refrigerant liquid C 2  (part thereof is refrigerant gas) decompressed by the expansion valve (pressure reduction valve)  109  after being condensed by the condenser  103 . Gas-phase component (refrigerant gas) C 3  of the refrigerant liquid C 2  (part thereof is refrigerant gas) accumulated by the economizer  105  is supplied to a second compression stage  23  of the turbo compressor  1  via the flow path F 3 . On the other hand, liquid-phase component of the refrigerant liquid C 2  (part thereof is the refrigerant gas) accumulated by the economizer  105  is decompressed on the flow path F 4 , and then supplied to the evaporator  107 . 
     The evaporator  107  is connected with a first compression stage  21  of the turbo compressor  1  via a flow path F 5 . The evaporator  107  evaporates the refrigerant liquid C 2  decompressed on the flow path F 4  into refrigerant gas C 4 . The refrigerant gas C 4  evaporated by the evaporator  107  is supplied to the first compression stage  21  of the turbo compressor  1  via the flow path F 5 . 
     The turbo compressor  1  is connected with the condenser  103  via the flow path F 1 , and has the first compression stage  21  and the second compression stage  23 . The turbo compressor  1  compresses the refrigerant gas C 4  supplied via the flow path F 5  by its first compression stage  21  and then discharges it to the flow path F 3 , and concurrently compresses the refrigerant gas C 3  supplied via the flow path F 3  (containing the refrigerant gas discharged from the first compression stage  21 ) by its second compression stage  23  and then discharge it to the flow path F 1 . The refrigerant gas C 1  compressed by the turbo compressor  1  is supplied to the condenser  103  via the flow path F 1 . The coolant for air conditioning is cooled by heat-exchanging with the refrigerant at the evaporator  107 . 
     Hereinafter, the turbo compressor  1  will be explained with reference to  FIG. 2  to  FIG. 4 . 
     The turbo compressor  1  includes a gear housing  3  in which lubrication oil is accumulate, a gear  5  housed in the gear housing  3 , and a demister  9  disposed above the gear  5  in the gear housing  3 . The gear  5  supplies the lubrication oil by its rotations. The demister  9  is provided with intakes  7  (see  FIG. 3  and  FIG. 4 ) communicated with an outside of the gear housing  3 . The demister  9  catches oil mist of the lubrication oil splashed by the rotations of the gear  5  to return it to a lower portion of the gear housing  3 . 
     A gear cover  11  for catching the lubrication oil splashed by the rotations of the gear  5  and dripping it to the lower portion of the gear housing  3  is provided around the gear  5 . In addition, a demister cover  15  for dripping the oil mist of the lubrication oil caught by the demister  9  to the lower portion of the gear housing  3  is provided. A narrow gap  13  is formed, near the demister  9 , between the demister cover  15  and an inner wall surface of the gear housing  3  (see  FIG. 2  and  FIG. 3 ). 
     In addition, a lower end edge of the gear cover  11  counter to a rotational direction (see an arrow in  FIG. 3 ) of the gear  5  is extended downward further than an opposed-side lower end edge (see  FIG. 3  and  FIG. 5 ). Further, a total area of the narrow gap  13  formed between the demister cover  15  and the inner wall surface of the gear housing  3  is made larger than an opening area of the intakes  7  of the demister  9 . 
     As shown in  FIG. 2 , the turbo compressor  1  is configured of a housing  17 , a gear unit  19 , the first compression stage  21 , the second compression stage  23 , and so on. 
     The housing  17  is composed of a motor housing  25 , the above-explained gear housing  3  and a compressor housing  27 , and the housings are fixed with each other by bolts or the like. The gear unit  19 , the first compression stage  21  and the second compression stage  23  are housed in the housing  17 . 
     The gear unit  19  is configured of a motor (drive source: not shown), an output shaft  29 , a gear set  31 , and a rotary shaft  33 . The output shaft  29  is rotatably supported by the motor housing  25  with a bearing  35  interposed therebetween. Rotations of the output shaft  29  are transmitted to the gear set  31 . 
     The gear set  31  is housed in the gear housing  3 , and composed of the above-explained gear  5  as a large-diameter gear and a pinion gear  37  as a small-diameter gear. The gear  5  is fixed with an end of the output shaft  29 , and rotates together with the output shaft  29 . The pinion gear  37  meshes with the gear  5 , and multiplies the rotations of the output shaft  29 . The pinion gear  37  is fixed with an end of the rotary shaft  33 , and rotates together with the rotary shaft  33 . 
     On end of the rotary shaft  33  along its axial direction is rotatably supported by the gear housing  3  with a bearing  39  interposed therebetween. Another end of the rotary shaft  33  is rotatably supported by the compressor housing  27  with a bearing  41  interposed therebetween. The first compression stage  21  and the second compression stage  23  are driven by rotations of the rotary shaft  33 . 
     The first compression stage  21  is configured of a first inlet port  43 , a first impeller  45 , and a first scroll chamber  47 . The inlet port  43  is provided on the compressor housing  27 , and communicated with the flow path F 5  (see  FIG. 1 ). Plural inlet guide vanes  49  for adjusting an inlet volume of the refrigerant gas C 4  as fluid are disposed in the inlet port  43 . The inlet guide vane(s)  49  is rotated by a drive mechanism  51  to change an effective opening area of the inlet port  43 , and thereby adjusts the inlet volume of the refrigerant gas C 4 . The inlet port  43  suctions the refrigerant gas C 4  evaporated at the evaporator  107  (see  FIG. 1 ), and then supplies it to the first impeller  45 . 
     The first impeller  45  is fixed with the rotary shaft  33 , and rotates together with the rotary shaft  33 . The first impeller  45  compresses the refrigerant gas C 4  supplied from the inlet port  43  by the rotations of the rotary shaft  33 , and then discharges it in its radial directions. The compressed refrigerant gas C 4  is supplied to the first scroll chamber  47 . 
     The first scroll chamber  47  is provided in the compressor housing  27 , and is communicated with an outer pipe (not shown) provided outside the housing  17 . The first scroll chamber  47  supplies the refrigerant gas C 4  compressed by the first impeller  45  to the flow path F 3  through the outer pipe. Note that the first scroll chamber  47  may be directly communicated with the flow path F 3  without the outer pipe interposed therebetween. 
     The second compression stage  23  is configured of an inlet scroll chamber  53 , a second impeller  55 , and a second scroll chamber  57 . The inlet scroll chamber  53  is provided in the gear housing  3 , and communicated with the flow path F 3  (see  FIG. 1 ). The inlet scroll chamber  53  suctions the refrigerant gas C 3  from the economizer  105  (see  FIG. 1 ) and the refrigerant gas C 4  compressed by the first compression stage  21 , and then supplies it to the second impeller  55 . 
     The second impeller  55  is fixed with the rotary shaft  33 , and rotates together with the rotary shaft  33 . The second impeller  55  is oriented so that its back surface faces a back surface of the first impeller  45 . The second impeller  55  compresses the refrigerant gas C 3  supplied from the inlet scroll chamber  53  by the rotations of the rotary shaft  33 , and then discharges it in its radial directions. The compressed refrigerant gas C 1  is supplied to the second scroll chamber  57 . 
     The second scroll chamber  57  is provided in the gear housing  3 , and is communicated with the flow path F 1  (see  FIG. 1 ). The second scroll chamber  57  supplies the refrigerant gas C 1  compressed by the second impeller  55  to the condenser  103  through the flow path F 1 . 
     As explained above, in the turbo compressor  1 , the rotary shaft  33  is rotated by the rotations of the output shaft  29  via the gear set  31 . The first compression stage  21  and the second compression stage  23  are driven by the rotations of the rotary shaft  33  to compress refrigerant. 
     At the first compression stage  21 , the refrigerant gas C 4  flowing through the flow path F 5  is supplied to the first impeller  45  from the inlet port  43 . The refrigerant gas C 4  supplied to the first impeller  45  is compressed by the first impeller  45 , and then supplied to the inlet scroll chamber  53  of the second compression stage  23  through the first scroll chamber  47 . Note that the refrigerant gas C 3  from the economizer  105  (see  FIG. 1 ) through the flow path F 3  is also supplied to the inlet scroll chamber  53  of the second compression stage  23 . 
     The refrigerant gas C 3  supplied to the inlet scroll chamber  53  (containing the refrigerant gas from the first compression stage  21 ) is supplied to the second impeller  55 . The refrigerant gas C 3  supplied to the second impeller  55  is compressed by the second impeller  55 , and then supplied to the condenser  103  (see  FIG. 1 ) through the second scroll chamber  57  and the flow path F 1 . 
     An oil tank  59  for accumulating lubrication oil is provided at a lower portion of the gear housing  3 . The lubrication oil accumulated in the oil tank  59  is supplied to slidably contact portions such as the above-mentioned bearings  35 ,  39  and  41  and to gear-meshing portions via an oil cooler (not shown) and an internal pipe(s) (not shown) to lubricate and cool the slidably contact portions and the gear-meshing portions. The slidably contact portions and the gear-meshing portions are communicated with the oil tank  59 , and the lubrication oil after lubricating and cooling the slidably contact portions and the gear-meshing portions drips into the oil tank  59  due to gravity to be collected. 
     In the turbo compressor  1 , a pressure equalizing pipe  61  for communicating an inside of the gear housing  3  with a portion near the inlet port  43  is provided in order to supply refrigerant gas generated in the oil tank  59  upon activation of the turbo refrigerator  101  to the portion near the inlet port  43 . Here, pressure inside the gear housing  3  in which the gear set  31  and so on are housed becomes relatively high, but pressure of the portion near the inlet port  43  in the compressor housing  27  is lower than the pressure inside the gear housing  3 . Therefore, airflow is generated in the pressure equalizing pipe  61  from the gear housing  3  that is a high-pressure side to the portion near the inlet port  43  in the compressor housing  27  that is a low-pressure side due to the pressure difference. 
     In addition, the lubrication oil is splashed by the rotations of the gear  5  in the gear set  31 , and thereby oil mist is generated in the gear housing  3 . The oil mist is subject to be discharged out from the gear housing  3  by the airflow through the pressure equalizing pipe  61 . Therefore, the demister  9  for catching the oil mist of the lubrication oil is provided in the gear housing  3 . 
     As shown in  FIG. 3  and  FIG. 4 , the demister  9  is disposed above the gear  5  and fixed with the gear housing  3  by bolts or the like to cover an open end of the pressure equalizing pipe  61  opened to the inside of the gear housing  3  (see  FIG. 2 ). In addition, the demister  9  is provided with the two intakes  7  opened to the inside of the gear housing  3 . The inside of the demister  9  is configured of a lattice-shaped or mesh-shaped catching member for catching lubrication oil, and catches oil mist contained in refrigerant gas flowing from the intakes  7  to the pressure equalizing pipe  61 . The lubrication oil (oil mist) caught by the demister  9  flows downward along sloped surfaces of the demister cover  15  due to its own weight, and then drips from the narrow gap  13  to the lower portion of the gear housing  3  (see  FIG. 3 ) and is collected in the oil tank  59  (see  FIG. 2 ). 
     As explained above, the lubrication oil splashed by the gear  5  is caught by the demister  9 , so that the lubrication oil is prevented from being discharged out from the gear housing  3 . However, as explained above, there is a possibility that the demister  9  cannot catch the lubrication oil sufficiently if the lubrication oil passing through the demister  9  is too much. Therefore, the gear cover  11  and the demister cover  15  are provided in the gear housing  3  in the present embodiment. 
     The gear cover  11  is fixed with the gear housing  3  by bolts or the like so as to surround the gear  5 . The gear cover  11  prevents spatters of lubrication oil by the gear  5 , and drips the lubrication oil downward to the oil tank  59  provided farthest from the demister  9  at the lower portion of the gear housing  3  to collect it. 
     In addition, as explained above, the lower end edge of the gear cover  11  counter to a rotational direction of the gear  5  is extended downward further than the opposed-side lower end edge. Therefore, lubrication oil can be received by the gear cover  11  efficiently at a rotation start of the gear  5  when spatters of lubrication oil are most predominant. In addition, the gear cover  11  can be light-weighted because the opposed-side lower end edge is made minimum. The demister cover  15  is disposed above the gear cover  11 . 
     The demister cover  15  is integrated with the demister  9  so as to be inclined downward from the intakes  7  of the demister  9 . The inclination of the demister cover  15  is set so that lubrication oil can flow downward against an airflow inhaled into the intakes  7 , in consideration of a volume of the airflow inhaled into the intakes  7  and viscosity of lubrication oil. 
     In addition, as explained above, the narrow gap  13  (see  FIG. 2  and  FIG. 3 ) is formed between the demister cover  15  and the inner wall surface of the gear housing  3 . The total area of the narrow gap  13  is made larger than the opening area of the intakes  7  of the demister  9 . Therefore, it never affects inhaling of gas into the intakes  7  (never reduces an intake volume). The demister cover  15  returns the lubrication oil caught by the demister  9  to the lower portion of the gear housing  3 , and protects portions near the intakes  7  from oil mist to restrict lubrication oil that is not caught by the gear cover  11  from reaching the intakes  7 . 
     Since the gear cover  11  that catches lubrication oil splashed by rotations of the gear  5  and then drips it to the lower portion of the gear housing  3  is provided around the gear  5  in the above-explained turbo compressor  1 , a distance between the oil tank  59  for accumulating lubrication oil and the demister  9  can be made long and thereby the lubrication oil is restricted from reaching the demister  9 . 
     In addition, the demister cover  15  that drips the lubrication oil (oil mist) caught by the demister  9  to the lower portion of the gear housing  3  is provided and the narrow gap  13  is formed between the demister cover  15  and the inner wall surface of the gear housing  3 , so that lubrication oil that is not caught by the gear cover  11  can be restricted from reaching the intakes  7  by the demister cover  15  (and the narrow gap  13 ). 
     Therefore, according to the above-explained turbo compressor  1 , an amount of lubrication oil that reaches the demister  9  can be reduced by the gear cover  11  and the demister cover  15 . 
     In addition, since the lower end edge of the gear cover  11  counter to a rotational direction of the gear  5  is extended downward further than the opposed-side lower end edge, spatters of the lubrication oil can be restricted effectively on a predominant side of the lubrication oil splashed by the gear  5 . Further, since the opposed-side lower end edge of the gear cover  11  is made minimum, the gear cover  11  can be light-weighted. 
     Furthermore, since the total area of the above-explained narrow gap  13  is made larger than the opening area of the intakes  7  of the demister  9 , an amount of lubrication oil that reaches the demister  9  can be reduced by the demister cover  15  (and the narrow gap  13 ) without degrading inhale performance of the demister  9 . 
     Note that, in the above embodiment, provided are the two intakes  7  that are opened to opposite sides to each other and parallel to a fixture plane of the demister  9  with the housing  17 . However, intake(s) that is perpendicular to the fixture plane may be provided. The demister (and its intake(s)) can take any configuration as long as it has a function of catching oil mist. 
     In addition, the gear cover  11  is formed so as to surround the gear  5 . However, the gear cover may have a shape that also surrounds the pinion gear, even if the gear and the pinion gear can mesh with each other. The gear cover may have any shape, even if it can restrict spatters of lubrication oil by the gear (and generation of oil mist involved therewith).