Abstract:
A scroll-type fluid machine such as a scroll compressor or a scroll vacuum pump generates compression heat during compressing operation. A scroll body comprises a stationary scroll and an orbiting scroll that is revolved with respect to the stationary scroll eccentrically. The stationary scroll has a stationary wrap and the orbiting scroll has an orbiting wrap engaged with the stationary wrap to form a compression chamber therebetween. In the scroll-type fluid machine, a cooler is provided to cool high-temperature compressed air discharged from a discharge bore at the center of the stationary scroll.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a scroll-type fluid machine such as a scroll compressor or a scroll vacuum pump, and especially to a scroll-type fluid machine for improving cooling capability of air which is discharged from a scroll compressor.  
         [0002]     When a scroll compressor is used as an air compressor, compression heat is generated during compressing operation and transmitted to each structural elements such as sealing members and bearings to decrease its mechanical life.  
         [0003]     To prevent such problems, as shown in Japanese Patent Publication No.9-53589A, in a conventional scroll compressor, a cooling path that communicates with external air is provided between the outer surface of a stationary scroll and casing, and between the outer surface of an orbiting scroll and an electric motor or a casing that enclose it to forward air with a cooling fan at one end of a compressor body, thereby cooling the stationary and orbiting scrolls and an electric motor, etc.  
         [0004]     However, in the above scroll compressor, air in a compression chamber is indirectly cooled With the stationary and orbiting scrolls, but compressed air from the compression chamber is directly discharged from an outlet to the outside to make cooling capability lower.  
         [0005]     Thus, when high-temperature air discharged from the compression chamber is stored in an air tank or used for an air tool, pressure-storage efficiency is decreased and the lives of the air tools are likely to decrease.  
         [0006]     To solve the problem a separate cooler is connected to the compressor to form a unit so that air discharged from the compression chamber may be cooled. But, addition of such a cooler makes the compressor unit larger to limit the place for installation of the fluid machine and increase manufacturing cost.  
       SUMMARY OF THE INVENTION  
       [0007]     In view of the disadvantages as above, it is an object of the present invention to provide a scroll-type fluid machine for cooling high-temperature air discharged from a compression chamber without a separate cooler.  
         [0008]     To achieve the object, according to the present invention, there is provided a scroll-type fluid machine comprising a stationary scroll having a stationary wrap which axially extends; an orbiting scroll having an orbiting wrap which is engaged with said stationary wrap of said stationary scroll, air being pressurized by revolving said orbiting scroll with respect to the stationary scroll; a discharge bore formed in the stationary scroll to discharge said pressurized air; and a cooler including a cooling path that communicate with said discharge bore to pass and cool said. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The above and other features and advantages of the present invention will become more apparent from the following description with respect to embodiments as shown in appended drawings wherein:  
         [0010]      FIG. 1  is a vertical sectional side view of the first embodiment of a scroll air compressor that is a scroll-type fluid machine according to the present invention;  
         [0011]      FIG. 2  is an enlarged vertical sectional front view taken along the line II-II in  FIG. 1 ;  
         [0012]      FIG. 3  is a partially cut-away view seen from the line III-III in  FIG. 1 ;  
         [0013]      FIG. 4  is a vertical sectional side view of the second embodiment of the present invention:  
         [0014]      FIG. 5  is a vertical sectional side view of the third embodiment of the present invention:  
         [0015]      FIG. 6  is an enlarged vertical sectional rear view taken along the line VI-VI in  FIG. 5 ; and  
         [0016]      FIG. 7  is an enlarged vertical sectional front view of the fourth embodiment according to the present invention, similar to  FIG. 2 . 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0017]     In  FIG. 1 , a scroll body  1  comprises a stationary scroll  2  and an orbiting scroll  3  driven by a motor (not shown). On the outer side surface or front surface (hereinafter, the left side of  FIG. 1  will be as front.) of a stationary end plate  4  of the stationary scroll  2 , cooling fins  5  for circulating cooling wind are suitably spaced and projected, and on the inner side surface or rear surface, a spiral stationary wrap  6  is axially projected.  
         [0018]     On the front or outer side surface of the orbiting end plate  7  of the orbiting scroll  3 , a spiral orbiting wrap  8  is projected forward and engaged with the stationary wrap  6 . On the rear surface of the orbiting end plate  7 , a plurality of cooling fins  9  for passing cooling wind are suitably spaced and projected.  
         [0019]     On the rear end face of the orbiting scroll  3 , a bearing plate  10  is bolted, and on the center of the rear surface, a tubular boss  14  is projected and engaged with an eccentric axial portion  12  of a drive shaft  11  connected to an orbiting shaft (not shown) of a motor.  
         [0020]     Between the orbiting scroll  3  and a tubular housing  15  for storing it, there are three sets of known crank-pin type rotation-preventing mechanism  16  for preventing the orbiting scroll  3  from rotating on its own axis so that the orbiting scroll  3  may be revolved with respect to the stationary scroll at predetermined eccentricity.  
         [0021]     Accordingly, volume between the orbiting scroll  3  and the stationary scroll  2  or between the orbiting wrap  8  and the stationary wrap  6  thereof gradually becomes smaller towards the center to form a compression chamber  17 . Around the stationary scroll  2 , an air intake bore  18  is provided, so that air that passes through a filter (not shown) is supplied into the compression chamber  17 .  
         [0022]     A discharge bore  19  that communicates with the compression chamber  17  is axially formed at the center of the stationary end plate  4  of the stationary scroll  2 .  
         [0023]     The flange of the stationary scroll  2  is fastened by clamp screws  20  to the front end opening of the housing  15  and integrally connected to the orbiting scroll  3 .  
         [0024]     On the front surface of the stationary scroll  2 , a cooler  21  for cooling high-temperature compressed air discharged from the discharge bore  19  is fixed by a plurality of bolts  22  to contact or come closer with the front end of the cooling fin  5  projected on the stationary end plate  5 .  
         [0025]     As shown in  FIGS. 2 and 3 , the cooler  21  comprises a cooler body  23  that has substantially a rectangle and a plurality of fins  24  spaced vertically. Openings between the cooling fins  24  are closed by a cover  26  bolted to the cooler body  23 .  
         [0026]     As shown in  FIG. 3 , each of the cooling fin  24  is corrugated to increase contact area with external air. Gaps between the cooling fins  24  open only at the horizontal ends so that air may flow horizontally. The cooler  21  is made of high-thermal-conductivity material such as Al alloy or Cu alloy.  
         [0027]     A plurality of cooling paths  24  are arranged in parallel in the cooler body  23 , and the cooling paths  27  communicate with each other via vertical communicating paths  28 ,  28  to form a long cooling path.  
         [0028]     The right end of the middle cooling path  27  which has a half length communicates with the discharge bore  19  at the center of the stationary scroll  2 . In the middle of the right-side communicating path  28 , there is formed a cooling outlet  29 , which is connected to a discharge pipe  30 . Numeral  31  denotes a plug for closing an opening when the cooling paths  27  and the communicating paths  28  are formed by a drill.  
         [0029]     Air compressed in the compression chamber  17  of the scroll body  1  and discharged through the discharge bore  19  flows into the middle cooling path  27  as shown by arrows in  FIG. 2 . Thereafter, air flows to a cooling outlet  29  through a plurality of cooling paths  27 , and is supplied to an air tank, an air tool etc. through a discharge pipe  30  connected to the cooling outlet  29 .  
         [0030]     When high-temperature air discharged from the compression chamber  17  passes through each of the cooling paths  27 , it is cooled by the cooler body  23 . A plurality of corrugated cooling fins  24  are projected on the cooler body  23 , thereby providing suitable cooling and radiating properties, so that air which passes through the cooling path  27  is effectively cooled.  
         [0031]     As shown by two-short-dash line in  FIG. 3 , the cooling fins  24  of the cooler  21  are surrounded by a blower duct  32  which opens at right and left sides. Air in the duct  32  may be discharged by a cooling or sucking fun  33  at one of the openings, thereby cooling the cooling fins  24  forcedly by air that flows in through the other opening. Thus, cooling effect by the cooler body  23  is increased, so that air in the cooling paths  27  is effectively cooled.  
         [0032]      FIG. 4  illustrates the second embodiment of the present invention, in which the same numerals are assigned to members similar to those in the first embodiment and detailed description therefor is omitted. In this embodiment, a stationary scroll  2  itself acts as a cooler  34 . That is to say, a stationary end plate  4  of a stationary scroll  2  is somewhat thick, and a cooling path  27  having the same shape as that in the first embodiment is formed in the stationary end plate. The middle cooling path  27  communicates with a discharge bore  19  at the center of the stationary scroll  2 . On the front surface of the stationary end plate  4 , a plurality of cooling fins  24  similar to those in the first embodiment project to increase cooling capability of the stationary end plate  4 .  
         [0033]     High temperature air discharged from a compression chamber  17  is not directly discharged from a discharge pipe  30 , but is thermally radiated to the stationary end plate  4  when it flows in the cooling paths  27 , thereby achieve efficient cooling. Temperature of the stationary end plate  4  rises by compression heat. So, compared with the first embodiment, lower cooling capability is achieved.  
         [0034]     In this embodiment, the cooling fins  24  may be covered with a blower duct similar to that in the first embodiment so as to cool air forcedly by a sucking fun.  
         [0035]      FIGS. 5 and 6  show the third embodiment of the present invention, in which a tubular cooler  35  is mounted with bolts  22  to the front surface of a stationary scroll  2  similar to that of the first embodiment in  FIG. 1 .  
         [0036]     The cooler  35  comprises a high-thermal-conductivity cooler body  36  made of Al alloy or Cu alloy, and a conduit  38  that is tightly engaged in a semi-circular sectioned meandering groove  37  on the rear surface of the cooler body  36 . One end of the conduit  38  is connected to a discharge bore  19  at the center of the stationary scroll  2 , and the other end is connected to a cooling outlet  29  of the cooler body  36 . The conduit  38  is made of high thermally conductive material such as Cu.  
         [0037]     A cover  26  similar to those in the foregoing embodiments is bolted to the cooling fin  24 , but may be omitted.  
         [0038]     In the third embodiment, high-temperature air discharged from a compression chamber  17  of the scroll body  1  flows into the conduit  38  and is discharged from a discharge pipe  30  connected to the cooling outlet  29 .  
         [0039]     The conduit  38  is heated with high-temperature air. But the conduit  38  has high thermal conductivity and large meandering length, so that heat is radiated to the cooler body  36  that has realtively low temperature. Thus, high-temperature air that flows through the conduit  38  is effectively cooled. In the third embodiment, only the conduit  38  may be mounted to the front of the stationary scroll  2  with a suitable fixing tool and touched to air directly for cooling.  
         [0040]      FIG. 7  illustrates the fourth embodiment of the present invention and a cooler  39  therein is applicable to a single-winding two-step scroll air compressor in which a low-pressure pressurizing step portion is formed on the outer portion of stationary and orbiting wraps and a high-pressure pressurizing step portion is formed on the inner portion, thereby further pressurizing, in the high-pressure pressurizing step portion, air pressurized and discharged from the low-pressure pressurizing step portion. As to a body of the single-winding two-step scroll air compressor, detailed description is omitted. A cooler  39  has substantially the same shape as the cooler  21  in the first embodiment, and the same numerals are allotted to the same members.  
         [0041]     In the cooler  39  mounted to the front of a stationary end plate  4  of a stationary scroll  2 , there are independently formed an intermediate cooling portion  40  that has a plurality of cooling paths  27  that communicate with each other; and a rear cooling portion  41  that has a plurality of cooling paths  27  different from the above cooling paths  27  and communicating with each other under the intermediate cooling portion  40 .  
         [0042]     In a middle cooling path  27  of an intermediate cooling portion  40 , there are formed a low-pressure discharge bore  42  that communicates with a low-pressure outlet of the stationary scroll; and a high-temperature intake bore  43  that communicates with a high-temperature inlet of the stationary scroll.  
         [0043]     At the end of the highest shorter cooling path  27  of the rear cooling portion  41 , there is formed a high-pressure discharge bore  44  that communicates with a high-pressure outlet of the stationary scroll; and a cooling discharge bore  29  at the upper end of a communicating path  28 .  
         [0044]     Air that is pressurized by the low-pressure pressurizing portion of a single-winding two-step scroll air compressor flows to the cooling path  27  of the intermediate cooling portion  40 , and cooled while it runs as shown by arrows. Cooled air flows into the high-pressure pressurizing step portion of the compressor through the high-pressure intake bore  43 .  
         [0045]     Air pressurized in the high-pressure pressurizing step portion flows into the cooling path  27  of the rear cooling portion  41  through the high-pressure discharge bore  40  and cooled while it runs as shown by arrows. Air cooled in the rear cooling portion  41  is discharged into an air tank through a discharge pipe connected to the cooling discharge bore  29 .  
         [0046]     As achieved in this embodiment, the intermediate cooling portion  40  and the rear cooling portion  41  are provided in the cooler  39 , and mounted to a single-winding two-step scroll air compressor. Conventionally, air discharged from a low-pressure pressurizing step portion is cooled by a separate intermediate cooler, but in this invention, air can be cooled by a single cooler  39 , thereby reducing size of a compressor unit to decrease manufacturing cost significantly.  
         [0047]     As described above, in the embodiments of a scroll air compressor, high-temperature air discharged from the compression chamber  17  of the scroll body  1  is cooled with the coolers  21 ,  34 ,  35 ,  39  on the front of the stationary scroll and discharged, thereby preventing decrease in pressure-storage efficiency of an air tank and preventing an air tool from being heated to lengthen its life.  
         [0048]     A cooler that is small and simple in structure can be installed in the compressor  1  easily, thereby omitting necessity of connection to a separate cooler, making the compressor itself smaller and decreasing manufacturing cost.  
         [0049]     The present invention is also applicable to a multi-step scroll air compressor which comprises one or more low-pressure pressurizing step portion for pressurizing air pressure to a predetermined pressure, and one or more high-pressure pressurizing step portion for further pressurizing air pressurized in the low-pressure pressurizing step portion, air pressurized in the low-pressure pressurizing step portion being cooled by an external cooler to introduce into the high-pressure pressurizing step portion.  
         [0050]     Furthermore, the present invention is also applicable to a double-wrap scroll or one- or multi-step compressor that has a orbiting wrap on both sides of an end plate of a orbiting scroll, the above cooler beings mounted to a stationary scroll end plate to provide functions as rear or intermediate cooler. An air inlet into the coolers  21 ,  34 ,  35  may be connected to an air discharge bore at the center of a high-pressure pressurizing step portion.  
         [0051]     The foregoing merely relates to embodiments of the invention. Various modifications and changes may be made by a person skilled in the art without departing from the scope of claims wherein: