Abstract:
A double side action type reciprocating compressor is provided. The double side action type reciprocating compressor includes suction valve assemblies and discharge valve assemblies loaded in a suction passage and a discharge passage to thus control suction of fluid and respectively combined with each other so that movement direction of fluid flowing inside the suction valve assemblies and the discharge valve assemblies is vertical to the movement direction of the reciprocating motor. Accordingly, it is possible to remove the suction passage and the suction valve directly formed or loaded in the piston. Therefore, it is possible to easily process the pistons. Because the diameter and the length of the pistons can be reduced, it is possible to miniaturize the compressor. Also, because the suction valve and the discharge valve are positioned on a side surface with respect to the movement direction of the pistons, it is possible to prevent the pistons from colliding with each other and to prevent the valves from being damaged. Also, because the left and right pistons share the same compression space when the pistons are in a reciprocating motion. The forward and the backward of the pistons move keeping balance. Accordingly, the compressor stably drives regardless of movement conditions.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a double side action type reciprocating compressor, and more particularly, to a double side action type reciprocating compressor including a suction/discharge system, which is suitable for manufacturing the compressor to be extremely small. 
   2. Description of the Background Art 
   In general, a double side action type reciprocating compressor is a high efficiency and low vibration compressor, where two compression units are combined with the respective reciprocating motors and are arranged to face each other in a casing. 
   As shown in  FIG. 1 , the conventional double side action type reciprocating compressor includes a cylindrical casing  10  including a suction pipe (SP) and a discharge pipe (DP) on both sides in a radial direction, a first reciprocating motor  21  and a second reciprocating motor  22  loaded on both sides inside the casing  10  in a longitudinal direction, a cylinder  30  loaded between the two reciprocating motors  21  and  22  in a long diameter direction, a first piston  41  and a second piston  42  inserted into both sides of the cylinder  30  to slide in a direction of a long diameter so that the respective leading ends of the first and second pistons  41  and  42  face each other and combined with moving magnets  21 B and  22 B of the reciprocating motors  21  and  22 , a first suction valve assembly  51  and a second suction valve assembly  52  respectively combined with the leading ends of the pistons  41  and  42  so as to face each other, and a first discharge valve  61  and a second discharge valve  62  loaded so as to open and close the discharge side of the cylinder  30 . 
   The cylinder  30  is ring-shaped and includes a through hole  31  in a reciprocating direction of the pistons  41  and  42  so that the pistons  41  and  42  are inserted into the cylinder  30  to slide, to thus form compression spaces S 1  and a discharge space S 2 . A suction passage  32  whose section is T-shaped is formed on one side outer circumference so that the outlet end of the suction passage  32  is connected to suction passages  41   a  and  42   a  of the pistons  41  and  42  through an inner space of the casing  10 . A discharge passage  33  whose inlet end is connected to the discharge space S 2  and whose section is I-shaped is formed on the opposite side outer circumference. 
   The first piston  41  and the second piston  42  are combined with the moving magnets  21 B and  22 B of the first reciprocating motor  21  and the second reciprocating motor  22 . The suction passages  41   a  and  42   a  are penetratingly formed in a reciprocating motion direction of the motors  21  and  22  in the middle of the pistons  41  and  42 . 
   As shown in  FIG. 3 , the first suction valve assembly  51  and the second suction valve assembly  52  include a first valve housing  51 A and a second valve housing  52 A including suction holes  51   a  and  52   a  connected to the suction passages  41   a  and  42   a  of the pistons  41  and  42  and fit-pressingly fixed to the leading ends of the pistons  41  and  42  and a first suction valve  51 B and a second suction valve  52 B inserted into the inner space of the valve housings  51 A and  52 A to slide, the first suction valve  51 B and the second suction valve  52 B for selectively opening and closing the suction passages  41   a  and  42   a  of the pistons  41  and  42  and the suction holes  51   a  and  52   a  of the valve housings  51 A and  52 A according to the reciprocating motion of the pistons  41  and  42 . 
   The first discharge valve  61  and the second discharge valve  62  are installed between the compression spaces S 1  and the discharge space S 2  so as to open and close the compression spaces S 1  of the cylinder  30 . The pressure back surfaces of the discharge valves  61  and  62  are supported by a valve spring  63 . 
   Among reference numerals that are not described,  21 A and  22 A are a first stator and a second stator and  71  and  72  are a first resonance spring and a second resonance spring. 
   The operation of the conventional double side action type reciprocating compressor will now be described. 
   When power is applied to the reciprocating motors  21  and  22 , the pistons  41  and  42  are in a linear reciprocating motion in the through hole  31  of the cylinder  30  and a refrigerant gas is received into both side suction pressure regions (not shown), that is, the space inside the casing  10  along the suction pipe (SP) and the suction passage  32  of the cylinder  30 . 
   The refrigerant gas is received into the compression spaces S 1  of the cylinder  30  along the suction passages  41   a  and  42   a  of the pistons  41  and  42  and is compressed, and then is discharged to the discharge space S 2  due to the continuous reciprocating motion of the first piston  41  and the second piston  42 . The compressed gas of the discharge space S 2  is discharged to a system outside the casing  10  through the discharge passage  33  and the discharge pipe (DP) during the next discharge stroke of the pistons  41  and  42 . 
   To be more specific, as shown in  FIG. 2 , when the pistons  41  and  42  move to be far from each other, the refrigerant gas filled in the suction pressure regions of the casing  10  is sucked up into the compression spaces S 1  of the cylinder  30  through the suction passages  41   a  and  42   a  while pushing the suction valves  51 B and  52 B of the pistons  41  and  42 . At this time, because the pressure of the compression spaces S 1  is lower than the pressure of the suction space, such as a suction pipe (SP) and an interior of the case  10 , the first discharge valve  61  and the second discharge valve  62  close the discharge side of the cylinder  30 . 
   As shown in  FIG. 3 , when the pistons  41  and  42  move to be closer to each other, the pressure of the compression spaces S 1  becomes higher than the pressure of the discharge space S 2 . Accordingly, the discharge valves  61  and  62  that fill up the compression spaces S 1  of the cylinder  30  are opened. At the same time, the compressed refrigerant gas is received into the discharge space S 2 . Accordingly, the compressed refrigerant gas of the discharge space S 2  is discharged to the outside of the compressor. At this time, the suction valve  51 B fills up the suction passages  41   a  and  42   a  of the pistons  41  and  42  because the pressure of the compression spaces S 1  is higher than the pressure inside the casing  10 . 
   However, according to the conventional double side action type reciprocating compressor, when the suction passages  41   a  and  42   a  are formed in the pistons  41  and  42  and the suction valve assemblies  51  and  52  are loaded in the ends of the suction passages  41   a  and  42   a  or when the suction valve assemblies  51  and  52  are loaded in the leading ends of the pistons  41  and  42 , it is difficult to manufacture the suction valve assemblies  51  and  52  suitable for the pistons  41  and  42  having a small diameter and to load the suction valves  51 B and  52 B in the pistons  41  and  42 . Accordingly, productivity deteriorates. Also, during the reciprocating motion of the pistons  41  and  42 , the suction valve assemblies  51  and  52  collide with the first discharge valve  61  and the second discharge valve  62  or deviate from the pistons  41  and  42 . Accordingly, the suction valve assemblies  51  and  52  can be damaged. 
   Also, according to the characteristics of the compressor, the pistons  41  and  42  that are moving objects must be precisely processed. Portions to be precisely processed such as a valve settling place increase in the pistons  41  and  42 . As a result, it is more difficult to process the pistons  41  and  42 . 
   Also, because the discharge valve assemblies  51  and  52  are positioned in front of the pistons  41  and  42 , the length of the entire apparatus becomes longer. 
   Also, because the plurality of compression spaces S 1  exist and the respective compression spaces S 1  are opened and closed by the linear reciprocating motion of the pistons  41  and  42  combined with the motors  21  and  22 , when there is something wrong with the electrical control of the motors  21  and  22 , the pressures of the compressed compression spaces S 1  become unbalanced. So, the motion of the compressor would be unstable. Accordingly, from side to side vibration of the compression apparatus is accelerated. 
   SUMMARY OF THE INVENTION 
   Therefore, an object of the present invention is to provide a double side action type reciprocating compressor that can be miniaturized by reducing the length of a compression part. 
   Another object of the present invention is to provide a double side action type reciprocating compressor, which is capable of easily manufacturing and loading suction valve assemblies and of preventing discharge valves from deviating or colliding with each other, to thus be damaged, during an operation. 
   Another object of the present invention is to provide a double side action type reciprocating compressor, which is capable of easily manufacturing pistons to be precisely processed. 
   Another object of the present invention is to provide a double side action type reciprocating compressor, which is capable of stabilizing a system by suppressing a phenomenon that pistons are pushed backward during the operation of the compressor. 
   To achieve these and other advantages and in accordance with the purposes of the present invention, as embodied and broadly described herein, there is provided a double side action type reciprocating compressor, comprising a casing, on both sides a suction pipe and a discharge pipe are connectedly installed, a plurality of reciprocating motors installed on both sides inside the casing and generating a reciprocating motion in opposite directions, a cylinder loaded on the inner circumference of the casing so as to be positioned in a space between the reciprocating motors, a plurality of pistons combined to moving magnets interposed between slits of the reciprocating motors and inserted into a through hole formed in the cylinder to slide, suction valve assemblies loaded in a suction passage of the cylinder to thus control suction of fluid and combined with each other so that movement direction of fluid flowing inside the suction valve assemblies is formed to be vertical to movement direction of the reciprocating motors, and discharge valve assemblies loaded in a discharge passage of the cylinder to thus control discharge of fluid and combined with each other so that movement direction of fluid flowing inside the discharge valve assemblies is formed to be vertical to movement direction of the reciprocating motors. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
     In the drawings: 
       FIG. 1  is a vertical sectional view showing an example of a conventional double side action type reciprocating compressor; 
       FIG. 2  schematically shows the suction stroke of the conventional double side action type reciprocating compressor; 
       FIG. 3  schematically shows the discharge stroke of the conventional double side action type reciprocating compressor; 
       FIG. 4  is a vertical sectional view showing an example of a double side action type reciprocating compressor according to the present invention; 
       FIG. 5  schematically shows the suction stroke of the double side action type reciprocating compressor according to the present invention; 
       FIG. 6  schematically shows the discharge stroke of the double side action type reciprocating compressor according to the present invention; 
       FIG. 7  is an enlarged sectional view showing another embodiment of a discharge valve assembly of the double side action type reciprocating compressor according to the present invention; 
       FIG. 8  schematically shows the suction stroke of another embodiment of the discharge valve assembly of the double side action type reciprocating compressor according to the present invention; and 
       FIG. 9  schematically shows the discharge stroke of another embodiment of the discharge valve assembly of the double side action type reciprocating compressor according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A double side action type reciprocating compressor according to the present invention will now be described in detail with reference to an embodiment shown in the attached drawings. 
     FIG. 4  is a vertical sectional view showing an example of a double side action type reciprocating compressor according to the present invention.  FIGS. 5 and 6  schematically show the suction stroke and the discharge stroke of the double side action type reciprocating compressor according to the present invention. 
   As shown in  FIGS. 4 through 6 , the double side action type reciprocating compressor according to the present invention includes a casing  110 , to which a suction pipe (not shown) and a discharge pipe (not shown) are connected in a radial direction of the casing  110 , a first reciprocating motor  121  and a second reciprocating motor  122 , which are installed on both sides of the casing  110  and whose moving magnets  121 B and  122 B are in a reciprocating motion in opposite directions, a cylinder  130  loaded between the first reciprocating motor  121  and the second reciprocating motor  122 , including a compression space S 1  penetratingly formed in a direction coaxial to the reciprocating motors  121  and  122 , and independently including a suction passage  132  and a discharge passage  133  connected to the compression space S 1 , a first piston  141  and a second piston  142  combined with the moving magnets  121 B and  122 B of the first reciprocating motor  121  and the second reciprocating motor  122  and inserted into a through hole  131  formed inside the cylinder  130  to slide so that the leading ends of the first and second pistons  141  and  142  face each other, a suction valve assemblies  150  loaded in the suction passage  132  of the cylinder  130 , the suction valve assemblies  150  for controlling the suction of fluid, and a discharge valve assembly  160  loaded in the discharge passage of the cylinder  130 , the discharge valve assembly  160  for controlling the discharge of fluid. 
   The cylinder  130  is formed to be integrated with the casing  110  so that the outer circumference of the cylinder  130  is attached to the inner circumference of the casing  110  or is manufactured to be separated from the casing  110 . The cylinder  130  can be fixed to the inner circumference in the middle of the casing  110  by welding or bolting. 
   The through hole  131  is formed in the cylinder  130  in a reciprocating motion direction of the pistons  141  and  142  so that the pistons  141  and  142  are inserted into the cylinder  130  to slide, to thus form the compression space S 1 . The suction passage  132  is formed so that the compression space S 1  is connected to the suction pipe (not shown). The discharge passage  133  is formed so that the compression space S 1  is connected to the discharge pipe (not shown). 
   Stepped surfaces (no references) are formed in the inside ends of the suction passages  132  and the discharge passage  133  of the cylinder  130  so that a suction valve  152  and a discharge valve  162  to be mentioned later are placed. 
   The first piston  141  and the second piston  142  are preferably in the form of empty cylinders, whose ends are closed, so as to reduce weights. 
   The suction valve assemblies  150  includes a suction adapter  151  including a suction hole  151   a  connected to the suction pipe (not shown) and press-fitted to the suction passage  132  and a suction valve  152  positioned in the leading end of the suction hole  151   a  and inserted into the inner circumference of the suction passage  132  to slide, the suction valve  152  for opening and closing the suction hole  151   a.    
   The diameter of the suction hole  151   a  of the suction adapter  151  is formed to be smaller than the diameter of the inside end of the suction passage  132 . 
   The suction valve  152  is in the form of a disk, on whose outer circumference several gas suction grooves  152   a  are included. A virtual circle that connects the inner circumferences of the gas suction grooves  152   a  to each other is formed to have a diameter larger than the diameter of the suction hole  151   a  and smaller than the inner diameter of the inside end of the suction passage  132 . 
   The discharge valve assembly  160  includes a discharge adapter  161  including a discharge hole  161   a  so as to be connected to the discharge pipe (not shown) and press-fitted to the discharge passage  133  of the cylinder  130 , a discharge valve  162  elastically supported by the leading end of the discharge adapter  161 , the discharge valve  162  for opening and closing the inside end of the discharge passage  133 , and a valve spring  163  loaded between the pressure back surface of the discharge valve  162  and the leading end of the discharge adapter  161 , the valve spring  163  for supporting the discharge valve  162 . 
   The discharge adapter  161  is preferably inserted into the cylinder  130  so as to be separated from the inside end of the discharge passage  133  of the cylinder  130  so that a discharge space S 2  holding the discharge valve  162  and the valve spring  163  is formed inside the discharge passage  133 . 
   The discharge valve  162  forms a pressure surface inserted into the discharge passage  133 , a pressure back surface wider than the discharge passage  133 , and a tilted sealing surface (no reference) between the pressure surface and the pressure back surface, to thus form a tapered cone whose head portion is cut off. The inside end of the discharge passage  133  corresponding to the cone includes a stepped surface (no reference). A tilted sealing surface (no reference) is formed at the edge of the stepped surface so as to contact the sealing surface (no reference) of the discharge valve  162 . 
   Another embodiment of the discharge valve assembly will now be described. 
     FIG. 7  is an enlarged sectional view showing another embodiment of the discharge valve assembly of the double side action type reciprocating compressor according to the present invention.  FIGS. 8 and 9  schematically show the suction stroke and the discharge stroke of another embodiment of the discharge valve assembly of the double side action type reciprocating compressor according to the present invention. 
   As shown in  FIGS. 7 through 9 , according to another embodiment  260  of the discharge valve assembly  160 , a plate spring  300  is used instead of a valve spring  163  in the form of a coil unlike in the previous embodiment, to thus improve abrasion resistance and responsibility of the valve. 
   A cylinder  230  of a predetermined form is fixedly combined with the inside of the casing  110 . A through hole  231  is formed in the middle of the cylinder  230 . The first piston  141  and the second piston  142  are inserted into both sides of the through hole  231  to slide. 
   A discharge passage F′ having the discharge space S 2  is formed so as to be connected to the through hole  231  formed inside the cylinder  130 . 
   The discharge passage F′ includes a first holes  265  formed to have predetermined inner diameter and depth on the inner wall of the cylinder through hole  231 , a tilted stepped sealing surface  266  formed to have a predetermined depth in the form of a cone so as to be extended to the first hole  265 , and a second hole  267  formed to have an inner diameter larger than the long diameter of the tilted stepped sealing surface  266  so as to be connected to a through hole  212  formed in the casing  110  to be connected to the tilted stepped sealing surface  266 . 
   The discharge passage F′ formed of the first hole  265 , the tilted stepped sealing surface  266 , and the second hole  267  is formed in a direction perpendicular to the cylinder through hole  231  of the frame. 
   An inertial discharge valve  262  in the form of a cone whose head portion is cut off is inserted into the discharge passage F′. 
   The discharge valve  262  includes a cone  263  whose head portion is cut off so as to correspond to the tilted stepped sealing surface  266  of the discharge passage F′ and a supporter  264  protruding so as to have predetermined outer diameter and height in the middle of the long diameter of the cone  263 . The outer circumference of the cone  263  forms a sealing surface. 
   The discharge adapter  261  including a discharge hole  261   b  inside thereof is inserted into the second hole  267  of the discharge passage F′ of the cylinder  230  and is combined with the cylinder  230 . 
   The discharge adapter  261  includes a body  261   a  having predetermined outer diameter and length and inserted into and fixed to the discharge passage F′ and a discharge hole  261   b  penetratingly formed in the body  261   a.    
   The discharge hole  261   b  includes a first inner diameter  261   c  formed so as to have predetermined depth and diameter in the end positioned inside the discharge passage F′ and a second inner diameter  261   d  penetratingly formed so as to have an inner diameter smaller than the first inner diameter  261   c  to be connected to the first inner diameter  261   c.    
   The plate spring  300  is combined with the inside of the discharge passage F′ so that the plate spring  300  is separated from the discharge valve  262  by a predetermined distance d during the suction stroke of the pistons  141  and  142 . 
   A plurality of through grooves  301 , in which refrigerant gas can flow during the movement of the discharge valve  262 , are formed in a thin circular thin plate in the plate spring  300 . 
   The diameter of a virtual circle formed in the inner circumference of the through grooves  301  is formed to be larger than the diameter of the supporter  264  formed in the discharge valve  262 . 
   The discharge valve  262  is supported by the plate spring  300  after moving a predetermined distance during the discharge stroke of the pistons  141  and  142 . 
   Also, in the plate spring  300 , a stepped portion  268  is formed on the inner circumference of the discharge passage F′, that is, on the inner circumference of the second hole  267  of the discharge passage F′. The plate spring  300  is fixed to and combined with the end of the discharge adapter  261  inserted into and combined with the discharge passage F′ in a state of being positioned in the stepped portion  268 . 
   As a matter of course, it is well known that the compressor can be operated even without the springs  163  and  300  in the discharge valve assemblies  160  and  260 . 
   Among reference numerals that are not described,  121 A and  122 A are a first stator and a second stator and  171  and  172  are a first resonance spring and a second resonance spring. 
   The operation and effect of the double side action type reciprocating compressor according to the present invention will now be described. 
   When power is applied to the first reciprocating motor  121  and the second reciprocating motor  122 , the first piston  141  and the second piston  142  are simultaneously in a linear reciprocating motion in opposite directions in the through hole  131  of the cylinder  130 . At the same time, refrigerant gas is discharged to a system outside the casing  110  through the suction pipe (not shown), the suction hole  151   a  of the suction adapter  151 , the discharge passage  133  of the cylinder  130 , the discharge adapter  161 , and the discharge pipe (not shown). 
   To be more specific, as shown in  FIG. 5 , when the pistons  141  and  142  move to be far from each other, the refrigerant gas outside the casing  110  is received through the suction pipe (not shown) and the suction hole  151   a  of the suction adapter  151 , pushes the suction valve  152  positioned in the leading end of the suction adapter  151 , connects the suction hole  151   a  to the suction passage  132 , and is sucked up into the compression space S 1  of the cylinder  130 . 
   At this time, the suction valve  152  is attached to the stepped surface of the suction passage  132 . However, because the diameter of a virtual circle connecting the gas suction grooves  152   a  of the suction valve  152  to each other is smaller than the diameter of the suction hole  132   a , the refrigerant gas is received into the compression space S 1  of the cylinder  130  through the gas suction grooves  152   a  and stays in the compression space S 1 . 
   As shown in  FIG. 6 , when the first piston  141  and the second piston  142  move to be closer to each other, the pressure of the refrigerant gas of the compression space S 1  is increased to more than a predetermined discharge pressure. Accordingly, the refrigerant gas opens the discharge valve  162  and is discharged to the discharge pipe (not shown) through the discharge hole  133   a , the discharge passage  133 , and the discharge hole  161   a  of the discharge adapter  161 . 
   The discharge valve  162  is pushed while being supported by the valve spring  163 , pushes the compressed refrigerant gas filled in the discharge space S 2  to the discharge hole  161   a  of the discharge adapter  161 , and lets the compressed refrigerant gas discharged to the discharge pipe (not shown). The suction valve  151  is pushed to the compressed gas and is attached to the leading end of the suction adapter  151 . However, because the diameter of the suction hole  151   a  of the suction adapter  151  is smaller than the diameter of the virtual circle connecting the inner circumferences of the gas suction grooves  152   a  of the suction valve  152  to each other, back flow of the compressed gas is prevented. 
   As the suction valve assemblies are loaded in the suction passage of the cylinder, it is possible to easily manufacture and install the suction valve. Also, because the suction valve assemblies are loaded in a fixed body but not in moving pistons, it is possible to prevent the suction valve assemblies from deviating or colliding with each other, to thus be damaged. 
   It is possible to easily process the pistons because a suction passage is not formed in the pistons and the additionally combined suction valve assemblies are not loaded. 
   It is possible to suppress a phenomenon where the pistons are pushed backward with excessive displacement during the operation of the pistons because intermediate pressure is formed between suction pressure and discharge pressure by refrigerant leaking between the cylinder and the piston backward both pistons. 
   Because both pistons share the compression, pressures backward the pistons, which affect the movement of the pistons, are the same as each other. Accordingly, it is possible to reduce the vibration of the compressor. 
   The operation and the effect of another embodiment  260  of the discharge valve assemblies  160  of the reciprocating compressor according to the present invention will now be described. 
   As shown in  FIG. 8 , when the first piston  141  and the second piston  142  simultaneously move to be far from each other, the outer circumference of a cone  263  of the inertial discharge valve  262  whose head is cut off is attached to the tilted stepped sealing surface  266  of the discharge passage F′ by difference in pressures inside the cylinder through hole  231 . Accordingly, the discharge passage F′ is closed. 
   The refrigerant gas outside the casing  110  is received through the suction pipe (not shown) and the suction hole  151   a  of the suction adapter  151 , pushes the suction valve  152  positioned in the leading end of the suction adapter  151 , connects the suction hole  151   a  to the suction passage  132 , and is sucked up into the compression space S 1  of the cylinder  130 . 
   The suction valve  152  is attached to the stepped surface of the suction passage  132 . However, the diameter of a virtual circle connecting the gas suction grooves  152   a  of the suction valve  152  to each other is smaller than the diameter of the suction hole  132   a . Accordingly, the refrigerant gas is received into the compression space S 1  of the cylinder  130  through the gas suction grooves  152   a  and stays in the compression space S 1 . 
   When the first piston  141  and the second piston  142  simultaneously move to be closer to each other, as shown in  FIG. 9 , the refrigerant gas sucked up into the through hole  231  of the cylinder  130  is gradually compressed. The inertial discharge valve  262  moves due to difference in pressure between the compression space S 1  formed by the ends of the first piston  141  and the second piston  142  and the through hole  231  and a discharge side. Accordingly, clearance is generated between the sealing surface of the discharge valve  262  and the tilted stepped sealing surface  266  of the discharge passage F′. 
   When the inertial discharge valve  262  firstly moves, the inertial discharge valve  262  is opened in a state of not being supported by the plate spring  300 . When the inertial discharge valve  262  moves by a more than predetermined distance, the inertial discharge valve  262  is elastically supported by the plate spring  300  and moves. 
   When clearance is generated between the sealing surface of the inertial discharge valve  262  and the tilted stepped sealing surface  266 , the compressed refrigerant gas leaks from the compression space S 1  and is discharged through the discharge hole  261   b  formed in the discharge adapter  261 . 
   When the first piston  141  and the second piston  142  move to be far from each other, the inertial discharge valve  262  moves by difference in pressures of the compression space S 1  and the sealing surface of the inertial discharge valve  262  is attached to the tilted stepped sealing surface  266  of the discharge passage F′. Accordingly, the discharge passage F′ is closed and the refrigerant gas is sucked up into the compression space S 1  again. 
   The inertial discharge valve  262  elastically moves in a state of being elastically supported by the plate spring  300 . After the inertial discharge valve  262  moves more than a predetermined distance, the inertial discharge valve  262  freely moves and is settled in the tilted sealing stepped surface  266 . 
   Therefore, the plate spring  300  is loaded to be separated from the inertial discharge valve  262  by a predetermined distance, the discharge valve  262  is not affected by the plate spring  300  at the point of time where the inertial discharge valve  262  is closed, that is, the sealing surface of the inertial discharge valve  262  and the tilted stepped sealing surface  266  of the discharge passage F′ are settled. 
   Also, the discharge valve  262  is not affected by the plate spring  300  even at the point of time where the discharge valve  262  is opened, that is, the sealing surface of the discharge valve  300  is separated from the tilted stepped sealing surface  266  of the discharge passage F′. Accordingly, the discharge passage F′ is correctly opened and closed. It is possible to prevent parts from being abraded and the responsibility of the discharge valve becomes excellent. 
   According to the double side action type reciprocating compressor of the present invention, the suction valve assemblies and the discharge valve assemblies including the suction valve and the discharge valve connected to the compression space formed in the middle of the cylinder are formed on both sides of the cylinder. Accordingly, the refrigerant gas is received to the compression space through the suction passage without passing through the inside of the casing and is discharged through the discharge passage. Therefore, because the suction passage directly formed in the pistons and the suction valve loaded in the pistons are removed, it is possible to easily process the pistons. Also, because the length of the compression apparatus can be reduced, it is possible to reduce the size of the entire compressor. 
   Also, the suction adapter and the discharge adapter are included, it is possible to easily manufacture the suction valve and the discharge valve. Because the suction valve and the discharge valve are loaded in the fixed body such as the suction/discharge adapter, it is possible to prevent the suction valve and the discharge valve from deviating or colliding with each other, thus to be damaged. 
   Because the intermediate pressure between the suction pressure and the discharge pressure is formed backward both pistons by the refrigerant leaking between the cylinder and the pistons, the left and right pistons are balanced during the reciprocating motion of the left and right pistons. Accordingly, it is possible to suppress the phenomenon where the backward of the piston is pushed. Because the pistons share the compression space, the motions of both pistons are the same. Accordingly, it is possible to reduce the vibration of the compressor. Since, the piston is supported by intermediate pressure, the average position of the piston can be more close to the initial position than no intermediate pressure exists. It leads to the high volumetric dfficiency. 
   Also, because abrasion between the discharge passage, through which the refrigerant gas is discharged, and the discharge valve for opening and closing the discharge passage is suppressed, the discharge passage and the discharge valve are correctly settled. Accordingly, it is possible to prolong the life of parts and the sealing stroke of the parts is improved. Also, the responsibility of the discharge valve becomes excellent, it is possible to improve the opening and closing strokes of the discharge passage and to improve the reliability of the compressor.