Patent Publication Number: US-11655819-B2

Title: Scroll compressor

Description:
TECHNICAL FIELD 
     The present invention relates to a scroll compressor. 
     Priority is claimed on Japanese Patent Application No. 2018-152322, filed Aug. 13, 2018, the content of which is incorporated herein by reference. 
     BACKGROUND ART 
     A scroll compressor includes a scroll compression unit which includes a fixed scroll and an orbiting scroll with a boss portion, a shaft which rotates about a first axis, a drive bush which is accommodated in the boss portion, and an eccentric shaft which extends in a direction of a second axis parallel to the first axis and different from the first axis and is partially inserted into the drive bush. 
     Patent Document 1 discloses a technique of easily manufacturing the shaft and the eccentric shaft by separately forming the shaft and the eccentric shaft having a constant outer diameter in a longitudinal direction. 
     Further, Patent Document 1 discloses that the eccentric shaft is press-inserted into a fitting hole formed in the shaft. 
     CITATION LIST 
     Patent Document(s) 
     
         
         Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2002-371976 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     However, when the eccentric shaft is supported in a cantilever state as in Patent Document 1, high stress is generated at a boundary portion between a fitting hole and the eccentric shaft (hereinafter referred to as a “base portion of the eccentric shaft”) in the eccentric shaft during operation. Accordingly, there is a probability of a large load being applied to the base portion of the eccentric shaft. 
     Further, when a large load is applied to the base portion of the eccentric shaft as described above, there is a probability of the strength of the eccentric shaft decreasing. Accordingly, it has been difficult to decrease the outer diameter of the eccentric shaft. Therefore, there has been a problem of a radial size of the drive bush increasing. 
     Here, an object of the present invention is to provide a scroll compressor capable of decreasing a radial size of a drive bush while improving strength of an eccentric shaft. 
     Solution to Problem 
     In order to achieve the aforementioned object, a scroll compressor according to an aspect of the present invention includes: a fixed scroll which includes a first end plate portion and a first swirl portion formed upright in the first end plate portion; an orbiting scroll which includes a second end plate portion having one surface facing the first end plate portion, a second swirl portion formed upright in the one surface of the second end plate portion and joining with the first swirl portion to form a compression chamber, and a boss portion formed on the other surface of the second end plate portion located opposite to the one surface and protruding from the other surface; a shaft which includes a first hole portion formed on close to one end surface facing the other surface of the second end plate portion, extends in the direction of the first axis, and rotates about the first axis; a drive bush which includes a drive bush body formed between the second end plate portion and the one end surface of the shaft while being accommodated in the boss portion and a penetration portion penetrating the drive bush body in a direction from the second end plate portion toward the one end surface of the shaft; an eccentric shaft which is disposed in the first hole portion, a press-fitting hole through which the first hole portion is exposed, and the penetration portion and which extends in a direction of a second axis parallel to the first axis; and a base seat portion which is integrally formed with the one end surface of the shaft and is provided with the press-fitting hole, wherein the penetration portion includes a first portion which is disposed close to the orbiting scroll and a second portion which is disposed close to the shaft, which is communicated with the first portion, and a diameter of which is larger than that of the first portion, wherein the eccentric shaft is fitted into the first hole portion and the first portion and is press-inserted into the press-fitting hole, and wherein the base seat portion is disposed in the second portion with a gap interposed between the base seat portion and the drive bush body. 
     According to the present invention, since the base seat portion which is integrally formed with the one end surface of the shaft and is provided with the press-fitting hole exposing the first hole portion is provided and the base seat portion is disposed in the second portion of the penetration portion with the gap interposed between the drive bush body and the base seat portion, it is possible to improve the strength of the eccentric shaft (the base of the eccentric shaft) located in the vicinity of the one end surface of the shaft that easily generates high stress. 
     Further, it is possible to shorten the length of the eccentric shaft protruding toward the drive bush compared to a case in which the base seat portion is not provided. Accordingly, since it is possible to secure the strength of the eccentric shaft, it is possible to decrease the outer diameter of the eccentric shaft. Accordingly, it is possible to decrease the radial size of the drive bush to which the eccentric shaft is fitted. 
     Further, since the gap is interposed between the drive bush body and the base seat portion, it is possible to decrease a frictional force between the drive bush body and the base seat portion. 
     Further, in the scroll compressor according to the aspect of the present invention, the shaft may include a second hole portion which is formed close to the one end surface, a third hole portion may be formed in a portion of the drive bush body facing the second hole portion, the scroll compressor may further include a limit pin which extends in a direction of a third axis parallel to the first and second axes; and a rubber ring which is provided on an outer peripheral surface of the limit pin, part of the limit pin provided with the rubber ring may be accommodated in one of the second and third hole portions so that the rubber ring comes into contact with an inner peripheral surface of the one of the second and third hole portions, and the remaining part of the limit pin protruding from the one end surface of the shaft may be fitted into the other of the second and third hole portions. 
     In this way, when the second hole portion is formed in the shaft, the third hole portion facing the second hole portion is formed in the drive bush body, part of the limit pin is accommodated in the one hole portion, and the remaining part of the limit pin is fitted into the other hole portion, the position of the drive bush with respect to the shaft is regulated by two members (the eccentric shaft and the limit pin), and hence the swing amount can be decreased. 
     Further, when part of the limit pin provided with the rubber ring is accommodated in the one hole portion so that the rubber ring comes into contact with the inner peripheral surface of the one of the second and third hole portions, it is possible to alleviate an impact when a swing occurs. 
     Further, in the scroll compressor according to the aspect of the present invention, a center axis of the drive bush may be parallel to the first axis, and the second and third axes may be disposed at positions passing through a line orthogonal to the center axis. 
     In this way, when the second and third axes are disposed at the positions passing through the line orthogonal to the center axis of the drive bush, it is possible to dispose the third axis on the outside of the drive bush as much as possible and to secure the thickness of the limit pin. 
     Further, in the scroll compressor according to the aspect of the present invention, an annular diameter-reduced portion may be formed in an outer peripheral surface of drive bush body located close to the shaft, and the scroll compressor may further include a balance weight which includes a fitting penetration portion fitted to a portion of the drive bush in which the diameter-reduced portion is formed. 
     In this way, when the drive bush and the balance weight are formed as separate members, they have shapes which are easily processed compared to a case in which the drive bush and the balance weight are integrally formed with each other and hence the drive bush and the balance weight can be easily manufactured. 
     Further, the scroll compressor according to an aspect of the present invention may further include a bush radial bearing which is disposed between an inner peripheral surface of the boss portion and an outer peripheral surface of the drive bush body, the bush radial bearing may be a ball bearing, and a material of the drive bush may be cast iron. 
     In this way, when the ball bearing is used as the bush radial bearing disposed between the inner peripheral surface of the boss portion and the outer peripheral surface of the drive bush body, it is possible to decrease the inner diameter of the bush radial bearing. Accordingly, it is possible to decrease the outer diameter of the drive bush. 
     In this way, when the outer diameter of the drive bush is small, it is possible to use inexpensive cast iron and to decrease the cost of the drive bush. 
     Further, the scroll compressor according to an aspect of the present invention may further include: a motor which rotates the shaft; and a shaft radial bearing which rotatably supports an outer peripheral surface of a portion located between the motor and the drive bush in the shaft and an outer diameter of the base seat portion may be smaller than an inner diameter of the shaft radial bearing. 
     In this way, when the outer diameter of the base seat portion is smaller than the inner diameter of the shaft radial bearing, it is possible to decrease the radial size of the drive bush. Accordingly, it is possible to form a space for disposing the balance weight on the outside of the drive bush in the radial direction. 
     Advantageous Effects of Invention 
     According to the present invention, the strength of the eccentric shaft can be improved and the size of the drive bush in the radial direction can be decreased. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a cross-sectional view showing a schematic configuration of a scroll compressor according to an embodiment of the present invention. 
         FIG.  2    is a cross-sectional view of a drive bush, an orbiting scroll, a shaft end portion, a shaft radial bearing, a bush radial bearing, and a balance weight through an eccentric shaft and a limit pin constituting the scroll compressor shown in  FIG.  1   . 
         FIG.  3    is a cross-sectional view of the shaft end portion and the orbiting scroll shown in  FIG.  2   . 
         FIG.  4    is a cross-sectional view of the drive bush, the limit pin, and a rubber ring shown in  FIG.  2   . 
         FIG.  5    is a plan view of the structure shown in  FIG.  4    from A. 
         FIG.  6    is a plan view of the structure shown in  FIG.  4    from B. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 
     Embodiment 
     A scroll compressor  10  according to an embodiment of the present invention will be described with reference to  FIG.  1    to  FIG.  6   . A cross-section of  FIG.  1    corresponds to a cross-section in a direction of a line C 1 -C 2  shown in  FIG.  5   . In  FIG.  2   , R 1  indicates an outer diameter of a base seat portion  92  (hereinafter referred to as an “outer diameter R 1 ”) and R 2  indicates an inner diameter of a shaft radial bearing  17  (hereinafter referred to as an “inner diameter R 2 ”). A cross-section of the structure shown in  FIG.  2    and  FIG.  4    corresponds to a cross-section in a direction of a line D 1 -D 2  shown in  FIG.  5   . 
     In  FIG.  5   , L indicates a line orthogonal to a center axis O 4  of a drive bush  29  (hereinafter referred to as a “line L”). 
     In  FIG.  1    to  FIG.  6   , O 1  indicates an axis of a shaft  15  (hereinafter referred to as a “first axis O 1 ”), O 2  indicates an axis of an eccentric shaft  33  (hereinafter referred to as a “second axis O 2 ”), O 3  indicates an axis of a limit pin  37  (hereinafter referred to as a “third axis O 3 ”), and O 4  indicates a center axis of a drive bush  29  (hereinafter referred to as a “center axis O 4 ”). 
     Additionally, the first axis O 1  is also an axis of a casing  12 . 
     The scroll compressor  10  includes the casing  12 , the shaft  15 , shaft radial bearings  17  and  18 , a motor  21 , a scroll compression unit  23 , a thrust bearing  25 , a thrust plate  26 , an Oldham ring  28 , the drive bush  29 , a bush radial bearing  31 , a balance weight  32 , the eccentric shaft  33 , a base seat portion  92 , a snap ring  35 , the limit pin  37 , and a rubber ring  38 . 
     The casing  12  includes a casing body  41 , a cover  43 , a first lid  44 , and a second lid  46 . 
     The casing body  41  includes a first cylindrical portion  51 , a second cylindrical portion  52 , and an annular portion  54 . 
     The first cylindrical portion  51  is a member that is formed in a cylindrical shape about the first axis O 1 . The first cylindrical portion  51  is formed such that both ends are open ends. The first cylindrical portion  51  includes a motor accommodation space  51 A disposed therein. The motor accommodation space  51 A is a columnar space. 
     The second cylindrical portion  52  is a member that is formed in a cylindrical shape about the first axis O 1 . The second cylindrical portion  52  is formed such that both ends are open ends. The second cylindrical portion  52  includes a compression unit accommodating space  52 A disposed therein. The compression unit accommodating space  52 A is a columnar space. 
     The annular portion  54  protrudes from an inner peripheral surface of a boundary portion between the first cylindrical portion  51  and the second cylindrical portion  52  toward the inside of the casing body  41  in the radial direction. The annular portion  54  is provided with a flow passage  56  which allows the motor accommodation space  51 A and the compression unit accommodating space  52 A to communicate with each other. 
     The flow passage  56  functions as a flow passage through which a fluid or lubricating oil compressed by the scroll compression unit  23  moves. 
     The cover  43  is a member for partitioning a substrate chamber and is formed such that both ends are open ends. The cover  43  is provided at the open end located on the other side of the first cylindrical portion  51  in the X direction. 
     The cover  43  includes a boss portion  43 A which extends to the inside of the motor accommodation space  51 A. An annular diameter-enlarged portion  43 Aa for disposing the shaft radial bearing  18  is formed inside the boss portion  43 A. 
     The cover  43  with the above-described configuration is fixed to the first cylindrical portion  51  by, for example, a bolt or the like. 
     The first lid  44  is provided in the cover  43  to block an open end located on the other side of the cover  43  in the X direction. 
     The second lid  46  is provided in the second cylindrical portion  52  to block an open end located on one side of the second cylindrical portion  52  in the X direction. The second lid  46  is fixed to the second cylindrical portion  52  by, for example, a bolt or the like. 
     The shaft  15  is accommodated in the casing  12  and extends in the X direction. The shaft  15  includes one end portion  61 , another end portion  62 , and an intermediate portion  63 . 
     The one end portion  61  is an end portion which is disposed on the other side in the X direction. The one end portion  61  is formed in a columnar shape and is formed to have a diameter larger than the intermediate portion  63 . Part of the one end portion  61  is disposed inside the annular portion  54  and the remaining part is disposed in the motor accommodation space  51 A. 
     The one end portion  61  includes an end surface  61   a  (one end surface), an outer peripheral surface  61   b , a first hole portion  65 , and a second hole portion  66 . 
     The end surface  61   a  is an end surface disposed on the one side in the X direction. The end surface  61   a  faces the other surface  76 Ab of a second end plate portion  76 A constituting an orbiting scroll  76 . 
     The outer peripheral surface  61   b  faces an inner peripheral surface  54   a  of the annular portion  54  while being separated from the annular portion  54 . 
     The first hole portion  65  is a columnar hole about the second axis O 2 . The first hole portion  65  extends in the direction of the second axis O 2 . The first hole portion  65  is a hole for allowing the eccentric shaft  33  to be fitted to one end portion  61 . 
     The second hole portion  66  is a columnar hole about the third axis O 3 . The second hole portion  66  extends in the direction of the third axis O 3 . The inner diameter of the second hole portion  66  is a size at which the limit pin  37  to which the rubber ring  38  is attached can be accommodated. 
     The other end portion  62  is an end portion which is disposed on the other side in the X direction. The other end portion  62  is formed in a columnar shape and is formed to have a smaller diameter than that of the intermediate portion  63 . An outer peripheral surface of the other end portion  62  faces the diameter-enlarged portion  43 Aa while being separated from the diameter-enlarged portion  43 Aa in the radial direction. 
     The intermediate portion  63  is a columnar member that is disposed in the motor accommodation space  51 A. The intermediate portion  63  connects the one end portion  61  and the other end portion  62  to each other. 
     The shaft radial bearing  17  is provided between the outer peripheral surface  61   b  of the one end portion  61  and the inner peripheral surface  54   a  of the annular portion  54 . The shaft radial bearing  17  rotatably supports the one end portion  61  of the shaft  15 . 
     The shaft radial bearing  18  is disposed between the outer peripheral surface of the other end portion  62  and the diameter-enlarged portion  43 Aa. The shaft radial bearing  18  rotatably supports the other end portion  62  of the shaft  15 . 
     The motor  21  includes a rotor  71  and a stator  72 . The rotor  71  is fixed to the outer peripheral surface of the intermediate portion  63  constituting the shaft  15 . 
     The stator  72  is formed in an annular shape about the first axis O 1 . An outer peripheral surface of the stator  72  is fixed to an inner peripheral surface of the first cylindrical portion  51  with a gap interposed therebetween. The stator  72  is disposed on the outside of the rotor  71  in the radial direction with a gap interposed between the stator and the rotor  71 . 
     The motor  21  with the above-described configuration rotates the shaft  15  about the first axis O 1 . 
     The scroll compression unit  23  is disposed in the compression unit accommodating space  52 A formed inside the casing body  41 . The scroll compression unit  23  includes a fixed scroll  75  and the orbiting scroll  76 . 
     The fixed scroll  75  and the orbiting scroll  76  are disposed in the X direction. The fixed scroll  75  is disposed between the second lid  46  and the orbiting scroll  76 . 
     The fixed scroll  75  is fixed to an inner peripheral surface of the second cylindrical portion  52 . The fixed scroll  75  includes a first end plate portion  75 A, a first swirl portion  75 B, and a discharge hole  75 C. 
     The first end plate portion  75 A is a circular plate member and includes one surface  75 Aa and another surface  75 Ab disposed on the side opposite to the one surface  75 Aa. The one surface  75 Aa faces the second lid  46 . The other surface  75 Ab faces the orbiting scroll  76 . 
     The first swirl portion  75 B is provided upright in the X direction from the other surface  75 Ab of the first end plate portion  75 A toward the orbiting scroll  76 . 
     The discharge hole  75 C is formed to penetrate the center portion of the first end plate portion  75 A. The discharge hole  75 C discharges a fluid compressed by the scroll compression unit  23  to the outside of the scroll compression unit  23 . 
     The orbiting scroll  76  includes a second end plate portion  76 A, a second swirl portion  76 B, and a boss portion  76 C. The second end plate portion  76 A is a circular plate member and includes one surface  76 Aa and another surface  76 Ab disposed on the side opposite to the one surface  76 Aa. The one surface  76 Aa faces the other surface  75 Ab of the first end plate portion  75 A in the X direction. The other surface  76 Ab faces the annular portion  54  in the X direction. 
     The second swirl portion  76 B is provided upright in the X direction from the one surface  76 Aa of the second end plate portion  76 A toward the fixed scroll  75 . The second swirl portion  76 B joins with the first swirl portion  75 B. A compression chamber  78  in which a fluid is compressed is formed between the orbiting scroll  76  and the fixed scroll  75 . 
     The thrust bearing  25  is provided between the annular portion  54  and the thrust plate  26  disposed in the X direction. 
     The thrust plate  26  is provided between the thrust bearing  25  and the Oldham ring  28  disposed in the X direction. 
     The Oldham ring  28  is provided between the thrust plate  26  and the second end plate portion  76 A disposed in the X direction. 
     The drive bush  29  includes a drive bush body  81 , a penetration portion  82 , a third hole portion  84 , a hole portion  85 , and a diameter reduced portion  86 . 
     The drive bush body  81  is accommodated in the boss portion  76 C with a gap between the drive bush body and the boss portion  76 C. The drive bush body  81  is provided between the second end plate portion  76 A and the end surface  61   a  (the one end surface) of the shaft  15 . 
     The drive bush body  81  includes one surface  81   a  and another surface  81   b  disposed on the side opposite to the one surface  81   a . The one surface  81   a  and the other surface  81   b  are surfaces disposed in the X direction. The one surface  81   a  faces the second end plate portion  76 A. The other surface  81   b  is in contact with the end surface  61   a  of the shaft  15 . 
     The penetration portion  82  is formed to penetrate a portion facing the first hole portion  65  formed in the one end portion  61  of the shaft  15  in the drive bush body  81  in the X direction (the direction from the second end plate portion  76 A toward the end surface  61   a  of the shaft  15 ). 
     The penetration portion  82  includes a first portion  82 A and a second portion  82 B. 
     The first portion  82 A is formed on the side of the second end plate portion  76 A and extends in the X direction. The first portion  82 A is a hole which is formed in a columnar shape. The inner diameter of the first portion  82 A is set to substantially the same size as the outer diameter of the eccentric shaft  33 . 
     The second portion  82 B is formed on the side of the shaft  15  and extends in the X direction. The second portion  82 B is a hole which is formed in a columnar shape. The second portion  82 B communicates with the first portion  82 A and has an inner diameter which is larger than the inner diameter of the first portion  82 A. 
     The axes of the first and second portions  82 A and  82 B with the above-described configuration match the second axis O 2  of the eccentric shaft  33  accommodated in the first and second portions  82 A and  82 B. 
     The third hole portion  84  is formed on the side of the other surface  81   b  of the drive bush body  81  facing the second hole portion  66 . The third hole portion  84  is formed in a columnar shape and extends in the X direction. 
     The inner diameter of the third hole portion  84  is formed to be smaller than the inner diameter of the second hole portion  66 . The inner diameter of the third hole portion  84  is set to a size at which the limit pin  37  can be fitted thereto. 
     The hole portion  85  is formed on the side of the one surface  81   a  in the drive bush body  81 . The hole portion  85  is a columnar hole having a diameter larger than that of the second portion  82 B. 
     The bush radial bearing  31  is provided between an inner peripheral surface of the boss portion  76 C and an outer peripheral surface of the drive bush  29 . As the bush radial bearing  31 , for example, a ball bearing may be used. 
     In this way, when the ball bearing is used as the bush radial bearing  31 , the inner diameter of the bush radial bearing  31  can be decreased. Accordingly, the outer diameter of the drive bush  29  can be decreased. 
     In this way, when the outer diameter of the drive bush  29  decreases, inexpensive cast iron can be used as the material of the drive bush  29 . Accordingly, the cost of the drive bush  29  can be decreased. 
     The diameter reduced portion  86  is formed in an annular shape in the outer peripheral surface located on the side of the shaft  15  in the drive bush body  81 . 
     The balance weight  32  includes a fitting penetration portion  32 A which is fitted to a portion provided with the diameter-reduced portion in the drive bush. 
     The fitting penetration portion  32 A is fitted to a portion provided with the diameter reduced portion  86  in the drive bush  29 . 
     That is, the balance weight  32  is formed as a separate member from the drive bush  29 . 
     In this way, when the drive bush  29  and the balance weight  32  are formed as separate members, they have shapes which are easily processed compared to a shape in which the drive bush  29  and the balance weight  32  are integrated with each other and hence the drive bush  29  and the balance weight  32  can be easily manufactured. 
     The center axis O 4  of the drive bush  29  with the above-described configuration is an axis which extends in the X direction and is parallel to the first to third axes O 1 , O 2 , and O 3 . 
     The eccentric shaft  33  extends in the direction of the second axis O 2 . The eccentric shaft  33  is set to a size having a constant outer diameter. The eccentric shaft  33  is fitted (press-inserted) into the first hole portion  65  and the penetration portion  82 . An end portion  33 A of the eccentric shaft  33  located on the side of the second end plate portion  76 A is disposed in the hole portion  85 . The end portion  33 A of the eccentric shaft  33  is disposed at a position separated from the second end plate portion  76 A in the X direction. 
     The base seat portion  92  is integrally formed with the end surface  61   a  of the shaft  15  and is provided with a press-fitting hole  92 A which exposes the first hole portion  65 . The base seat portion  92  is disposed in the outer peripheral surface  33   a  located at the second portion  82 B in the outer peripheral surface  33   a  of the eccentric shaft  33 . 
     The base seat portion  92  forms a gap  95  between the base seat portion and the drive bush body  81  while being disposed in the second portion  82 B. 
     In this way, when the base seat portion  92  which is integrally formed with one end surface  61   a  of the shaft  15  and is provided with the press-fitting hole  92 A exposing the first hole portion  65  is provided and the base seat portion  92  is disposed in the second portion  82 B of the penetration portion  82  with the gap  95  interposed between the drive bush body  81  and the base seat portion  92 , it is possible to improve the strength of the eccentric shaft  33  (the base of the eccentric shaft) located in the vicinity of one end surface  61   a  of the shaft  15  that easily generates high stress. 
     Further, it is possible to shorten the length of the eccentric shaft  33  protruding toward the drive bush  29  compared to a case where the base seat portion  92  is not provided. Accordingly, since it is possible to secure the strength of the eccentric shaft  33 , it is possible to decrease the outer diameter of the eccentric shaft  33 . Accordingly, it is possible to decrease the radial size of the drive bush  29  to which the eccentric shaft  33  is fitted. 
     Further, since the gap  95  is interposed between the drive bush body  81  and the base seat portion  92 , it is possible to decrease a frictional force between the drive bush body  81  and the base seat portion  92 . 
     It is preferable that the outer diameter R 1  of the base seat portion  92  be smaller than, for example, the inner diameter R 2  of the shaft radial bearing  17 . 
     In this way, when the outer diameter R 1  of the base seat portion  92  is set to be smaller than the inner diameter R 2  of the shaft radial bearing  17 , it is possible to decrease the radial size of the drive bush  29 . Accordingly, it is possible to form a space for disposing the balance weight  32  on the outside of the drive bush  29  in the radial direction. 
     The snap ring  35  is provided in the outer peripheral portion of the end portion  33 A of the eccentric shaft  33 . The snap ring  35  protrudes outward in the radial direction from the outer peripheral surface  33   a  of the end portion  33 A of the eccentric shaft  33 . 
     In this way, when the snap ring  35  is provided to protrude outward in the radial direction from the outer peripheral surface  33   a  of the end portion  33 A of the eccentric shaft  33 , it is possible to regulate the position of the eccentric shaft  33  in the X direction from the second end plate portion  76 A toward the shaft  15 . 
     The limit pin  37  is a columnar pin, part of the limit pin  37  is disposed in the second hole portion  66 , and the remaining part thereof is fitted (press-inserted) to the third hole portion  84 . 
     The limit pin  37  extends in the direction of the third axis O 3  parallel to the direction of the first axis O 1 . An annular diameter-reduced portion  37 A is formed in an outer peripheral surface of part of the limit pin  37 . 
     The rubber ring  38  is disposed in the diameter-reduced portion  37 A. The rubber ring  38  is disposed in the second hole portion  66  together with part of the limit pin  37 . 
     Part of the limit pin  37  provided with the rubber ring  38  is accommodated in the second hole portion  66  so that the rubber ring  38  comes into contact with the inner peripheral surface of the second hole portion  66 . 
     In this way, when part of the limit pin  37  provided with the rubber ring  38  is disposed in the second hole portion  66  and the remaining part of the limit pin  37  is fitted (press-inserted) to the third hole portion  84 , the position of the drive bush  29  with respect to the shaft  15  is regulated by two members (the eccentric shaft  33  and the limit pin  37 ) and hence the swing amount can be decreased. 
     Further, when part of the limit pin  37  provided with the rubber ring  38  is accommodated so that the rubber ring  38  comes into contact with the inner peripheral surface of the second hole portion  66 , it is possible to alleviate an impact when a swing occurs. 
     It is preferable that the second and third axes O 2  and O 3  be disposed at, for example, a position passing through the line L orthogonal to the center axis O 4  of the drive bush  29 . 
     In this way, when the second and third axes O 2  and O 3  are disposed at positions passing through the line L orthogonal to the center axis O 4  of the drive bush  29 , the position of the third axis O 3  can be disposed on the outside of the drive bush  29  as much as possible and the thickness of the limit pin  37  can be secured. 
     According to the scroll compressor  10  of this embodiment, when the base seat portion  92  which is integrally formed with one end surface  61   a  of the shaft  15  and is provided with the press-fitting hole  92 A exposing the first hole portion  65  is provided and the base seat portion  92  is disposed in the second portion  82 B of the penetration portion  82  with the gap  95  interposed between the drive bush body  81  and the base seat portion  92 , it is possible to improve the strength of the eccentric shaft  33  located in the vicinity of one end surface  61   a  of the shaft  15  that easily generates high stress (the base of the eccentric shaft). 
     Further, it is possible to shorten the length of the eccentric shaft  33  protruding toward the drive bush  29  compared to a case in which the base seat portion  92  is not provided. Accordingly, since it is possible to secure the strength of the eccentric shaft  33 , it is possible to decrease the outer diameter of the eccentric shaft  33 . Accordingly, it is possible to decrease the radial size of the drive bush  29  to which the eccentric shaft  33  is fitted. 
     Further, since the gap  95  is interposed between the drive bush body  81  and the base seat portion  92 , it is possible to decrease a frictional force between the drive bush body  81  and the base seat portion  92 . 
     Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to such a specific embodiment and can be modified and changed in various forms in the scope of the spirit of the present invention described in claims. 
     For example, in this embodiment, a case in which the second hole portion  66  is formed in the shaft  15  and the third hole portion  84  is formed in the drive bush body  81  has been described as an example. However, the third hole portion  84  to which the remaining part of the limit pin  37  is fitted (press-inserted) may be formed in the shaft  15  and the second hole portion  66  accommodating part of the limit pin  37  provided with the rubber ring  38  may be formed in the drive bush body  81 . 
     INDUSTRIAL APPLICABILITY 
     The present invention is applicable to a scroll compressor. 
     REFERENCE SIGNS LIST 
     
         
         
           
               10  Scroll compressor 
               12  Casing 
               15  Shaft 
               17 ,  18  Shaft radial bearing 
               21  Motor 
               23  Scroll compression unit 
               25  Thrust bearing 
               26  Thrust plate 
               28  Oldham ring 
               29  Drive bush 
               31  Bush radial bearing 
               32  Balance weight 
               32 A Fitting penetration portion 
               33  Eccentric shaft 
               33 A End portion 
               35  Snap ring 
               37  Limit pin 
               37 A Annular diameter-reduced portion 
               38  Rubber ring 
               41  Casing body 
               43  Cover 
               43 A Boss portion 
               86  Diameter-reduced portion 
               44  First lid 
               46  Second lid 
               51  First cylindrical portion 
               51 A Motor accommodation space 
               52  Second cylindrical portion 
               52 A Compression unit accommodating space 
               54  Annular portion 
               54   a  Inner peripheral surface 
               56  Flow passage 
               61  One end portion 
               61   a  End surface 
               61   b ,  33   a  Outer peripheral surface 
               62  Other end portion 
               63  Intermediate portion 
               65  First hole portion 
               66  Second hole portion 
               71  Rotor 
               72  Stator 
               75  Fixed scroll 
               75 A First end plate portion 
               75 Aa,  76 Aa,  81   a  One surface 
               75 Ab,  76 Ab,  81   b  Other surface 
               75 B First swirl portion 
               75 C Discharge hole 
               76  Orbiting scroll 
               76 A Second end plate portion 
               76 B Second swirl portion 
               76 C Boss portion 
               78  Compression chamber 
               81  Drive bush body 
               82  Penetration portion 
               82 A First portion 
               82 B Second portion 
               84  Third hole portion 
               85  Recessed portion 
               92  Base seat portion 
               92 A Press-fitting hole 
               95  Gap 
             L Line 
             O 1  First axis 
             O 2  Second axis 
             O 3  Third axis 
             O 4  Center axis 
             R 1  Outer diameter 
             R 2  Inner diameter