Patent Publication Number: US-7210913-B2

Title: Scroll fluid machine with a silencer

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to a scroll fluid machine with a silencer that reduces as much as possible noise caused by the discharge of a compressed gas during operation. 
   A scroll fluid machine itself is known among those skilled in the art. In order to more easily understand the present invention, an example of the basic construction will be explained with reference to  FIG. 6 . 
     FIG. 6  is a vertical cross-sectional view of a known scroll fluid machine in which, by having an orbiting scroll with a fixed amount of eccentricity move in an orbiting motion inside a housing, a gas is sucked in from the outside of the housing and directed to a compression section that is formed by a combination of an orbiting scroll and stationary scrolls, and after becoming compressed by moving toward the center, the gas is discharged from the center. 
   The housing  21  which has a disk-shaped sealed compression chamber  22  comprises a casing  23  and cover  24 , and has an inlet hole  25  formed in its outer circumferential surface. 
   Both the casing  23  and cover  24  have stationary end plates  26 ,  27  that are located on both sides of the compression chamber  22  so that they face each other, and spiral stationary wraps  28 ,  29  are formed on the inner surfaces of these end plates that face toward the side of the compression chamber  22 , and form stationary scrolls  30 ,  31 . 
   An orbiting scroll  32  is located inside the compression chamber  22  between both of the stationary end plates  26 ,  27  so that it moves in an orbiting motion around the axis of the compression chamber  22 . 
   The orbiting scroll  32  has orbiting wraps  34 ,  35  that are formed on both surfaces of an orbiting end plate  33 , fit inside and engage with the stationary scrolls  30 ,  31  and are 180° with respect thereof. The orbiting scroll  32  is supported by bearings  40 ,  41  so that it can turn around the eccentric shaft portion  39  of a drive shaft  38 , which is fitted inside the center of the housing  21  by bearings  36 ,  37 . 
   The orbiting end plate  33  is linked to the stationary end plates  26 ,  27  by way of three known pin-crank-type self-rotation-prevention mechanisms (not shown) that are evenly spaced from each other and located around the same circumference. When the drive shaft  38  rotates, the orbiting end plate  33  moves in an eccentric orbiting motion inside the compression chamber  22  so that the dimension in the radial direction of the space between the stationary wraps  28 ,  29  and orbiting wraps  34 ,  35 , which are engaged with each other, changes. 
   An outlet hole  43  is formed in the stationary end plate  27  at a location near the center of the casing  23 . The inner end of the outlet hole  43  opens at a location near the center of the pressure chamber  22 , and the outer end is closed off by a stopper  42 . 
   Also, a discharge hole  44  is formed radially of the stationary end plate  27  so that it extends from the outlet hole  43  to the outer surface, and a exhaust joint  45  with a check valve fits into the outer end radially of this discharge hole  44 . 
   The drive shaft  38  is driven by a motor (not shown), and cooling fans  46 ,  47  are installed on the drive shaft  38  outside the casing  23  and the cover  24 . 
   A plurality of radial cooling fins  48 ,  49  protrude from the rear surface of the casing  23  and cover  24 . 
   As the drive shaft  38  rotates, the orbiting scroll  32 , which is supported so that it turns around the eccentric-shaft portion  39 , moves in an orbiting motion while still being engaged with the stationary scrolls  30 ,  31  with a constant amount of eccentricity. As it moves, a gas is sucked in from an inlet hole  25 , compressed inside the compression chamber  22  and directed toward the center, where it is finally discharged from the compression chamber  22  by way of the outlet hole  43 , discharge hole  44  and exhaust joint  45 . 
   The sound of the exhaust gas that is discharged from the discharge hole  44  and exhaust joint  45  has a considerably high pitch, so normally a suitable silencer  50  is installed in the outlet of the discharge hole  44  or exhaust joint  45 . 
   However, the silencer  50  protrudes outward in the axial or radial direction of the scroll fluid machine itself, so the dimensions of the scroll fluid machine are increased by that amount, which hinders handling and installation of the machine. 
   SUMMARY OF THE INVENTION 
   The object of the present invention is to provide a scroll fluid machine with a silencer that does not protrude outward from the scroll fluid machine, or does not change the shape or dimensions of the scroll fluid machine. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a vertical cross-sectional view showing the first embodiment of a scroll fluid machine according to the present invention; 
       FIG. 2  is a rear view of the stationary scroll shown in  FIG. 1 ; 
       FIG. 3  is a view showing a cylindrical silencer shown in  FIGS. 1 and 2 ; 
       FIG. 4  is a view similar to  FIG. 2  and shows the second embodiment of a scroll fluid machine according to the present invention; 
       FIG. 5  is an exploded perspective view of the cylindrical silencer shown in  FIG. 4 ; and 
       FIG. 6  is a vertical cross-sectional view of a known scroll fluid machine. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 to 3  show the first embodiment of a scroll fluid machine according to the present invention. 
   Except for the installation of a cylindrical silencer, the embodiment shown in  FIG. 1  to  FIG. 3  is the same as the scroll fluid machine that is shown in  FIG. 6 . Therefore, in  FIGS. 1 to 3 , the same reference numerals will be allotted to elements that are the same as those in  FIG. 6 , and description thereof will be omitted, so that only what are different will be described. 
   A cylindrical expansion-decompression type silencer  1 , having a thin, fan-shaped appearance, is suitably fitted between any arbitrary pair of adjacent radial cooling fins  49  that protrude from the rear surface of a stationary end plate  27  of a stationary scroll  31 . The silencer  1  is fastened with a suitable screw  2 , adhesive or the like. 
   The cylindrical silencer  1  is nearly the same height as the cooling fins  49 , or a little lower, where an inflow hole  3  thereof is connected to an outlet hole  43  formed in the stationary scroll  31 , and a discharge hole  4  thereof is located in the outer perimeter area of the stationary scroll  31 . 
   An exhaust joint  5  is connected to the discharge hole  4  of the cylindrical silencer  1 . 
   The silencer  50  connected to the outlet of the exhaust joint  45  in  FIG. 6  is omitted. 
   As shown in the enlarged view of  FIG. 3 , the cylindrical silencer  1  is such that the inflow hole  3 , which faces in the centripetal direction, has a small diameter, and connected to a large-diameter expansion hole  6 , and an adjustment nut  9 , which has a very small-diameter introduction tube  8  on its inside end, is screwed onto a female thread hole  7  that is formed on the outer end of the expansion hole  6 . 
   As the scroll fluid machine operates, pressurized gas coming from the outlet hole  43  near the center of the machine passes through the smaller-diameter inflow hole  3  of the cylindrical silencer  1  and flows inside the larger-diameter expansion hole  6  where it is decompressed by expansion, and the generation of noise is suppressed. 
   When changes in the intensity of noise occur due to changes in the operating conditions of the scroll fluid machine, or due to fluctuations in air temperature or the like, it is possible to adjust the effective length of the cylindrical silencer  1  by adjusting the adjustment nut  9  and changing the position in the axial direction of the inlet of the introduction tube  8 . 
     FIG. 4  and  FIG. 5  show the second embodiment of a cylindrical silencer according to the present invention. 
   A space between adjacent cooling fins  49  and  49  is covered with a cover piece  10  and fixed airtightly with screws  11  to form a tubular silencer  12  surrounded by the cooling fins  49 , 49  and the cover piece  10 . 
   The construction inside the cylindrical silencer  12  is the same as that shown in  FIGS. 2 and 3 , so the same reference numbers are applied and a detailed explanation is omitted. 
   The foregoing relates to embodiments of the invention. Various changes and modifications may be made by a person skilled in the art without departing from the scope of claims wherein: