Patent Publication Number: US-2013236344-A1

Title: Scroll fluid machine

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The invention relates to a scroll fluid machine such as a compressor, a vacuum pump, a blower, and an expander. 
     2. Background Art 
     A scroll compressor is proposed, which is configured to drive the center part of an orbiting scroll having wraps on both sides such that an orbiting scroll performs an orbiting motion. For example, a scroll fluid machine as described in Japanese published unexamined application JP,2010-77913,A (8 Apr. 2010) is configured such that a drive shaft passes through the hollow portion of the center part of the orbiting scroll and the drive shaft is rotatably supported on both sides. The intermediate part of the drive shaft passing through the center part of the orbiting scroll is an eccentric shaft. An eccentric bearing is provided between the eccentric shaft and the orbiting scroll. 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     In a conventional scroll fluid machine, a orbiting bearing is provided in the hollow portion of the center part of an orbiting scroll. Fluid is subjected to a change in temperature due to compression when using a compressor or a vacuum pump, whereby the center part of the orbiting scroll is heated to a high temperature. In an expander, since high-temperature high-pressure fluid inflows, the center part of the orbiting scroll is heated to a high temperature. Thus, there has been a problem that the orbiting bearing is heated to a high temperature, thereby reducing the durability of the orbiting bearing. 
     The present invention addresses the aforementioned problem and an object of the present invention is to provide a scroll fluid machine which has a high-durability orbiting bearing. 
     Technical Solution 
     In the invention according to claim  1 , a scroll fluid machine is constituted of a combination of an orbiting scroll that has a spiral wrap on both surfaces of a paneling and a pair of fixed scrolls that has a spiral wrap on one surface of a paneling, wherein a hollow orbiting shaft is provided at the center part of said orbiting scroll to pass through said fixed scroll; a rotating shaft passes through the hollow portion of said orbiting shaft such that it is rotatably supported by a pair of covers provided on the outer surface side of said fixed scroll; orbiting bearings are provided on both ends of said orbiting shaft to fit an eccentric portion provided on said rotating shaft; and a self-rotation prevention mechanism of said orbiting scroll is provided on one end of said orbiting shaft. 
     In the invention according to claim  2 , said eccentric portion is provided only at the position of said rotating shaft corresponding to said orbiting bearing, and the intermediate portion between the eccentric portions of said rotating shaft is formed coaxially with the rotation center axis. 
     In the invention according to claim  3 , said self-rotation prevention mechanism is constituted of a pair of fixed-side key grooves provided coupled with said fixed scroll on one side; a pair of orbiting-side key grooves provided so as to cross orthogonally to said fixed-side key grooves in an orbiting bearing housing which is provided on said orbiting shaft to accommodate said orbiting bearing; and an Oldham&#39;s ring having a pair of Oldham&#39;s keys fitting said fixed-side key grooves and a pair of Oldham&#39;s keys fitting said orbiting-side key grooves. 
     In the invention according to claim  4 , a 1st balance weight is attached to said rotating shaft between said orbiting bearing at one end of said orbiting shaft and the rotating shaft bearing rotatably supporting said rotating shaft at said one cover; and a 2nd balance weight is attached to said rotating shaft between said orbiting bearing at the other end of said orbiting shaft and the rotating shaft bearing rotatably supporting said rotating shaft at said the other cover. 
     Advantageous Effects 
     In the invention according to claim  1 , orbiting bearings which support an orbiting shaft provided at the center part of an orbiting scroll are arranged on both sides of the orbiting shaft and the orbiting bearing is not located at the center part of the orbiting scroll, whereby the heat of orbiting scroll is hardly transmitted to the orbiting bearing. Even if the center part of the orbiting scroll is heated to a high temperature, the orbiting bearing is not heated to a high temperature. Thus, the durability of the orbiting bearing is increased. Further, the diameter of the orbiting shaft can be reduced, whereby the diameter of the orbiting scroll can be reduced. Hereby, a scroll fluid machine can be made compact. 
     In the invention according to claim  2 , the eccentric portion of the rotating shaft is provided only at two positions of the orbiting bearing. Other portions of the rotating shaft are not eccentrically formed. A centrifugal force is not generated in portions which are not eccentrically formed. Thereby, the deformation of the rotating shaft is reduced. As such, the vibration of the scroll fluid machine is also reduced. 
     In the invention according to claim  3 , the housing of the orbiting bearing is also a component of a self-rotation prevention mechanism, whereby the number of components used in the scroll fluid machine is reduced. 
     In the invention according to claim  4 , the distance between a 1st and a 2nd balance weights and an orbiting bearing can be reduced, whereby a moment applied to a rotating shaft can be reduced, thus the deformation of the shaft can be suppressed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an axial sectional view of an embodiment of a compressor according to the present invention. 
         FIG. 2  is a cross-sectional view of a self-rotation prevention mechanism taken along the plane orthogonal to the cross-sectional surface of  FIG. 1 . 
     
    
    
     MODE FOR THE INVENTION 
       FIG. 1  and  FIG. 2  show an embodiment of compressor according to the present invention. An orbiting scroll  1  is installed inside a compressor. An orbiting scroll  1  includes a paneling  1 A which has a spiral wrap  1 B and a spiral wrap  1 C on both sides thereof. The orbiting scroll  1  is interposed between a 1st fixed scroll  2  and a  2 nd fixed scroll  3 . The 1st fixed scroll  2  and the 2nd fixed scroll  3  are fixed to each other. The 1st fixed scroll  2  includes a paneling  2 A which has a spiral wrap  2 B. The 2nd fixed scroll  3  includes a paneling  3 A which has a spiral wrap  3 B. Compression chamber  4  is constituted of the paneling  1 A of the orbiting scroll  1  and the wrap  1 B, and the paneling  2 A of the 1st fixed scroll  2  and the wrap  2 B. Compression chamber  5  is constituted of the paneling  1 A of the orbiting scroll  1  and the wrap  1 C, and the paneling  3 A of the 2nd fixed scroll  3  and the wrap  3 B. 
     A hollow orbiting shaft  1 D is provided radially in the center part of the paneling  1 A. A 1st orbiting bearing housing  11  is fixed to one end of the orbiting shaft  1 D in the axial direction. A 1st orbiting bearing  12  is provided at the center part of the 1st orbiting bearing housing  11 . A 2nd orbiting bearing housing  13  is fixed to the other end of the orbiting shaft  1 D in the axial direction. A 2nd orbiting bearing  14  is provided at the center part of the 2nd orbiting bearing housing  13 . A rotating shaft  6  passes through the hollow portion of the orbiting shaft  1 D. A cylindrical portion  2 C is provided on the back surface of the 1st fixed scroll  2 . A cover  7  is arranged on the end face of the cylindrical portion  2 C. A 1st rotating shaft bearing  8  is provided on the center part of the cover  7 . A cylindrical portion  3 C is provided on the back surface of the 2nd fixed scroll  3 . A cover  9  is arranged on the end face of the cylindrical portion  3 C. A 2nd rotating shaft bearing  10  is provided on the center part of the cover  9 . The one end  6 C of the rotating shaft  6  is supported by the 1st rotating shaft bearing  8 . The edge of the rotating shaft  6  passes through the cover  7  and extends outside the cover  7 . A sealing member  15  is provided on the center part of the cover  7  so as to seal between the rotating shaft  6  and the cover  7 . The other end  6 D of the rotating shaft  6  is supported by the 2nd rotating shaft bearing  10 . Eccentric portions  6 A and  6 B are formed at two positions of the rotating shaft  6 . The intermediate portion between the eccentric portion  6 A and the eccentric portion  6 B of the rotating shaft  6  is formed coaxially with the rotation center axis of the rotating shaft  6 . The 1st orbiting bearing  12  fits the eccentric portion  6 A. The  2 nd orbiting bearing  14  fits the eccentric portion  6 B. That is, the eccentric portions  6 A and  6 B are provided only on the positions corresponding to the 1st orbiting bearing  12  and the 2nd orbiting bearing  14  of the rotating shaft  6 . 
     The 1st orbiting bearing housing  11  has a flange portion  11 A. The flange portion  11 A has orbiting-side key grooves  11 B,  11 B. A fixed board  16  is fixed to the inner surface of the cylindrical portion  2 C. An Oldham&#39;s ring  17  fits in between the flange portion  11 A and the fixed board  16 . The Oldham&#39;s ring  17  has Oldham&#39;s keys  17 A,  17 A. The Oldham&#39;s keys  17 A,  17 A fit the orbiting-side key grooves  11 B,  11 B. 
       FIG. 2  is a partial cross-sectional view taken along the plane in the axial direction orthogonal to the cross-sectional surface of  FIG. 1 . As shown in  FIG. 2 , the Oldham&#39;s ring  17  has the Oldham&#39;s keys  17 B,  17 B on the surface of the opposite side while having the Oldham&#39;s keys  17 A,  17 A. The Oldham&#39;s keys  17 A,  17 A and the Oldham&#39;s keys  17 B,  17 B cross orthogonally to each other. The fixed board  16  has fixed-side key grooves  16 A,  16 A at the positions facing the Oldham&#39;s keys  17 B,  17 B. That is, a pair of the fixed-side key grooves  16 A,  16 A is provided coupled to the 1st fixed scroll  2 . The Oldham&#39;s keys  17 B,  17 B fit the fixed-side key grooves  16 A,  16 A. The Oldham&#39;s ring  17 , the orbiting-side key grooves  11 B,  11 B, and the fixed-side key grooves  16 A,  16 A constitute a self-rotation prevention mechanism. Owing to the self-rotation prevention mechanism, the 1st orbiting bearing housing  11  is prevented from rotating while being able to orbit. As such, the orbiting scroll  1  is also only able to orbit without rotation. 
     The 1st orbiting bearing housing  11  has a sealing board  11 C. A sealing ring  18  is provided on the paneling  2 A so as to seal between the sealing board  11 C and the paneling  2 A. 
     The 2nd orbiting bearing housing  13  has a flange portion  13 A, while a sealing board  19  is attached to the inner surface of the cylindrical portion  3 C. 
     A sealing ring  20  is provided on the outer peripheral surface of the sealing board  19 . A sealing ring  21  is provided on the end face of the sealing board  19 . The sealing ring  20  and the sealing ring  21  seal between the inner surface of the cylindrical portion  3 C and the end face of the flange portion  13 A, and the sealing board  19 . 
     A weight chamber  27  is formed between the cover  7  and the 1st orbiting bearing housing  11 . A 1st balance weight  22  is attached between the 1st rotating shaft bearing  8  of the rotating shaft  6  and the 1st orbiting bearing  12 , in the weight chamber  27 . A weight chamber  28  is formed between the cover  9  and the 2nd orbiting bearing housing  13 . A 2nd balance weight  23  is attached between the 2nd rotating shaft bearing  10  of the rotating shaft  6  and the 2nd orbiting bearing  14 , in the weight chamber  28 . 
     An inlet  24  is provided on the outer peripheral portion of the fixed scroll  2 . An opening  38  is provided on the paneling  1 A adjacent to the orbiting shaft  1 D. An outlet chamber  25  is provided on the backside of the paneling  3 A of the fixed scroll  3 . An outlet  26  is provided on the outer peripheral portion of the paneling  3 A. A compressor is installed on one side  37 A of a base  37 . 
     An electric motor  29  is placed on the other side  37 B of the base  37 . A drive shaft  29 A of the electric motor  29  and one end  6 C of the rotating shaft  6  are coaxially arranged, and connected to each other with a coupling  30  while being prevented from rotating by a key and so forth. 
     An oil tank  31  is installed. Lubricant oil  32  is reserved in the oil tank  31 . An oil inlet tube  33  is connected to the bottom of the oil tank  31 , and is connected to the entrance of a pump  34 . An oil feed tube  35  is connected to the exit of the pump  34 , and is communicated with the top of the weight chamber  27  and the weight chamber  28 . An oil return tube  36  is connected to the bottom of the weight chamber  27  and the weight chamber  28 , and is communicated with the oil tank  31 . 
     Next, the operation of the compressor is described. When the electric motor  29  is energized, the drive shaft  29 A rotates, and the rotating shaft  6  which is coupled with the drive shaft  29 A rotates. When the rotating shaft  6  rotates, the orbiting shaft  1 D is eccentrically driven while being prevented from self-rotating by the self-rotation prevention mechanism. As a result, the orbiting scroll  1  which is integrally formed with the orbiting shaft  1 D performs orbiting motion. Thereby gas moves from the outer periphery to the inner periphery in the compression chamber  4  and the compression chamber  5  while being reduced in volume. Gas is inleted through an inlet  24 , is compressed in the compression chamber  4  and the compression chamber  5 . Then, the gas is discharged into the outlet chamber  25 , and is discharged outside through the outlet  26 . Owing to the 1st balance weight  22  and the 2nd balance weight  23 , a centrifugal force of the orbiting scroll  1  is canceled. As such, vibration hardly occurs. 
     The lubricant oil  32  is fed from the oil tank  31  through the oil inlet tube  33 , pressurized by the pump  34 , and is dropped into the weight chamber  27  and the weight chamber  28  through the oil feed tube  35 . The lubricant oil  32  is supplied to the 1st rotating shaft bearing  8 , the 2nd rotating shaft bearing  10 , the 1st orbiting bearing  12 , the 2nd orbiting bearing  14 , Oldham&#39;s keys  17 A,  17 A, and so forth, and returns from the bottom of the weight chamber  27  and the weight chamber  28  to the oil tank  31  through the oil return tube  36  after lubricating the curved portions and slide portions of these components. 
     According to an example of this embodiment, the 1st orbiting bearing  12  and the 2nd orbiting bearing  14  are not located at the center part of the orbiting scroll  1 . Thus, the 1st orbiting bearing  12  and the 2nd orbiting bearing  14  are difficultly affected by the heat of the orbiting scroll  1  even when the orbiting scroll  1  is heated to a high temperature due to compression heat, thereby being less heated. That is, the durability of the compressor is increased. Further, since no bearing exists inside the orbiting shaft  1 D, the distance between the outer periphery of the rotating shaft  6  and the inner periphery of the orbiting shaft  1 D becomes small, thus the diameter of the orbiting shaft  1 D can be made smaller. As such, the diameters of the orbiting scroll  1 , the 1st fixed scroll  2  and the 2nd fixed scroll  3  can be made smaller, whereby the compressor can be made compact. 
     Further, since orbiting scroll  1  is located between the 1st orbiting bearing  12  and the 2nd orbiting bearing  14 , a centrifugal force and gas load are equally applied to the 1st orbiting bearing  12  and the 2nd orbiting bearing  14 . Thus, no tilt occurs for the orbiting scroll  1 . 
     Further, the distance between the 1st orbiting bearing  12  and the 1st rotating shaft bearing  8  and the distance between the 2nd orbiting bearing  14  and the 2nd rotating shaft bearing  10  are small. Also, the distance between the 1st balance weight  22  and the 1st orbiting bearing  12  and the distance between the 2nd balance weight  23  and the 2nd orbiting bearing  14  are small. Thus, the moment applied to the rotating shaft  6  is small, thereby causing little deformation to the rotating shaft  6 . As such, the orbiting scroll  1  can be stably operated with a set amount of eccentricity, even if the orbiting scroll  1  is driven at a high speed. Thus, little vibration occurs in the compressor. 
     In an example of this embodiment, a compressor is described. However, the present invention can be also applied to a scroll fluid machine such as a vacuum pump, a blower, an expander and so forth.