Patent Publication Number: US-10316831-B2

Title: Valve assembly for variable swash plate compressor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Korean Patent Application Nos. 10-2014-0027085, 10-2014-0032247, and 10-2013-0112369, filed on Mar. 7, 2014, Mar. 19, 2014, and Sep. 23, 2013, respectively, the disclosures of which are incorporated herein by reference in their entirety. 
     FIELD OF THE INVENTION 
     Exemplary embodiments of the present invention relate to a valve assembly for a variable swash plate compressor, and more particularly, to a valve assembly for a variable swash plate compressor, capable of enhancing performance of a compressor through an increase in flow rate and extending a life of the compressor through an improvement of durability thereof. 
     BACKGROUND OF THE INVENTION 
     In general, compressors serving to compress refrigerant in vehicle cooling systems have been developed in various forms. The compressors are basically classified into a reciprocating compressor which performs compression by reciprocating motion and a rotary compressor which performs compression by rotary motion, according to a driving method. 
     There is a swash plate compressor as one type of the reciprocating compressor. The swash plate compressor includes a fixed capacity type swash plate compressor capable of fixing an installation angle of a swash plate and a variable capacity type swash plate compressor capable of changing an inclined angle of a swash plate so as to vary a discharge capacity. 
       FIG. 1  shows a configuration of a typical variable swash plate compressor. As shown in  FIG. 1 , a variable swash plate compressor  10  (hereinafter, referred to as “a compressor”) includes a cylinder block  20  defining a portion of an external appearance and frame of the compressor  10 . A center bore  21  is formed by penetrating the middle of the cylinder block  20  and a rotary shaft  30  is rotatably installed to the center bore  21 . 
     A plurality of cylinder bores  22  is radially arranged with respect to the center bore  21  so as to be formed by penetrating the cylinder block  20 . A piston  23  is installed within each of the cylinder bores  22  so as to be capable of linearly reciprocating. The piston  23  has a cylindrical shape and the cylinder bore  22  is a cylindrical space corresponding to the same. Refrigerant is introduced into or compressed and discharged from the cylinder bore  22  by reciprocating motion of the piston  23 . 
     A front housing  40  is coupled to the front of the cylinder block  20 . The front housing  40  defines a crank chamber  41  therein together with the cylinder block  20 . 
     A pulley  42  connected to an external power source (not shown) such as an engine by a belt is rotatably installed in the front of the front housing  40 . The rotary shaft  30  is rotated along with rotation of the pulley  42 . 
     A rear housing  50  is coupled to the rear of the cylinder block  20 . A discharge chamber  51  is defined in the rear housing  50  along a position adjacent to an outer peripheral side edge of the rear housing  50 , so as to selectively communicate with the associated cylinder bore  22 . A suction chamber  52  is defined radially inward of the discharge chamber  51 , namely, at a central portion of the rear housing  50 . 
     In this case, a valve assembly, which includes a valve plate  60 , and a suction reed plate and a discharge reed plate respectively installed on both side surfaces of the valve plate, is installed between the cylinder block  20  and the rear housing  50 . 
     The discharge chamber  51  communicates with the associated cylinder bore  22  through each discharge port  61  formed at the valve plate  60  and the suction chamber  52  communicates with the associated cylinder bore  22  through each suction port  62  of the valve plate  60 . 
     A rotor  70  is installed at one side of the rotary shaft  30  and integrally rotates with the rotary shaft  30  during rotation of the rotary shaft  30 . The rotor  70  is installed within the crank chamber  41  such that the rotary shaft  30  passes through the middle of the crank chamber. A hinge section  71  is protrusively formed on one surface of the rotor  70 . 
     A swash plate  80  is installed on the rotary shaft  30  in such a way to be spaced apart from the rotor  70 . The swash plate  80  is protrusively formed with a hinge receiving section  81  hinge-coupled to the hinge section  71  of the rotor  70 . The hinge receiving section  81  of the swash plate  80  is hinge-coupled to the hinge section  71  of the rotor  70  by a hinge pin  72 , thereby allowing the swash plate  80  to rotate along with rotation of the rotor  70 . 
     The swash plate  80  is connected to the individual pistons  23  by shoes  82 . Refrigerant is introduced into or compressed and discharged from the cylinder bore  22  while the pistons  23  linearly reciprocate within the cylinder bores  22  by rotation of the swash plate  80 . 
     In this case, the swash plate  80  is installed such that an angle of the swash plate  80  is variable according to the rotary shaft  30 , so as to enable a discharge amount of refrigerant in the compressor  10  to be regulated. To this end, an opening degree of a passage (not shown), which allows the discharge chamber  51  to communicate with the crank chamber  41 , is adjusted by a pressure regulation valve (not shown), and thus an inclined angle of the swash plate  80  is changed by a change in pressure in the crank chamber  41 . 
     The variable swash plate compressor having the above configuration is disclosed in Korean Patent Laid-Open Publication No. 10-2003-0048228 (Jun. 19, 2003) and Korean Patent Publication No. 10-125976 (Apr. 24, 2013). 
     Hereinafter, the configuration of the valve assembly will be described in more detail. 
     The valve assembly includes a central valve plate, a suction reed plate installed on a cylinder block side surface of the valve plate, and a discharge reed plate installed on a rear housing side surface of the valve plate. 
       FIG. 2  is an exploded perspective view illustrating a conventional valve plate  60  and suction reed plate  63 . Although not shown, the discharge reed plate is installed on the other side surface of the valve plate  60 . The valve plate  60  is a metal plate having a disc shape and is formed with the discharge ports  61  and suction ports  62  corresponding to the respective cylinder bores  22 . 
     A plurality of suction reeds  64  for opening and closing the suction ports  62  of the valve plate  60  is formed in a cut manner on the suction reed plate  63 . 
     The discharge reed plate is formed wherein a plurality of discharge reeds for opening and closing the discharge ports  61  of the valve plate  60  is protrusively formed on an outer periphery of the circular plate covering portions at which the suction ports  62  of the valve plate  60  are formed. 
       FIG. 3  shows a portion of the valve assembly facing one cylinder bore  22 .  FIG. 3  shows one suction reed  64 , one discharge reed  66 , and one suction port  62  and discharge port  61  formed on the valve plate  60  in a state in which the suction reed plate  63 , the valve plate  60 , and the discharge reed plate are sequentially stacked. Reference numeral  53  is a partition wall formed in the rear housing  50  to partition the suction chamber  52  and the discharge chamber  51 . 
     In the above state, when the piston is moved to a top dead center (suction stroke), a negative pressure is generated in the cylinder bore  22 . Consequently, the suction reed  64  opens the suction port  62  while being bent about base end portions  64   c  of leg sections  64   b  toward the cylinder bore  22  so that refrigerant in the suction chamber  52  is introduced into the cylinder bore  22  through the suction port  62 . In this case, the discharge reed  66  closes the discharge port  61  so that the refrigerant is smoothly introduced through the suction port  62 . 
     Subsequently, when the piston is moved to a bottom dead center (compression stroke), the suction reed  64  is returned to an original position by a compressed refrigerant pressure so as to close the suction port  62 . In this case, the refrigerant pressure acts on the discharge reed  66  through an opening hole  64   a  of the suction reed  64  and the discharge port  61 , and thus the discharge reed  66  opens the discharge port  61  while being pushed toward the discharge chamber  51  so that the refrigerant in the cylinder bore  22  is discharged to the discharge chamber  51  through the discharge port  61 . 
     Meanwhile, refrigerant should be rapidly introduced into and discharged from the cylinder bore  22 , in order to enhance performance of the compressor. However, when the compressor is merely driven at high speed for increasing a flow rate of refrigerant, there are problems in that noise and pulsation are increased and durability of the compressor is deteriorated. 
     When the compressor  10  is operated, the suction reed  64  performs an opening and closing operation at a rate of once per one revolution of the rotary shaft  30 . Thus, the suction reed  64  performs the opening and closing operation at high speed at a rate of ten times to several hundred times per second according to the operation speed of the compressor  10 . 
     Accordingly, the base end portion  64   c  of the leg section  64   b  of the suction reed  64 , namely a connection portion between the suction reed  64  and the suction reed plate  63 , is repeatedly folded and unfolded. 
     According to a result of analyzing stress distribution of the suction reed  64 , it may be seen that a stress is concentrated on the base end portion  64   c . In this case, a maximum principal stress applied to the base end portion  64   c  reaches about 436.69 Mpa. 
     In addition, since both leg sections  64   b  of the suction reed  64  are arranged in parallel with each other, the leg sections  64   b  have a weak structure in a torsional load acting on the suction reed  64  during the opening and closing operation thereof. 
     Thus, when fatigue is accumulated due to the repeated opening and closing operation of the suction reed  64 , the base end portion  64   c  may be easily broken. Since the suction reed  64  is not normally operated when the base end portion  64   c  is broken, the refrigerant is not normally introduced through the suction port  62  of the valve plate  60 . Consequently, since the refrigerant is not normally compressed and discharged, the compressor  10  may not be operated. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a valve assembly for a variable swash plate compressor, capable of enhancing performance of a compressor by changing shapes of components of the valve assembly to increase a flow rate, without an increase in driving speed of the compressor. 
     Another object of the present invention is to provide a valve assembly for a variable swash plate compressor, capable of extending a service life of a compressor by preventing damage of a base end portion of a suction reed. 
     Other objects and advantages of the present invention can be understood by the following description, and become apparent with reference to the embodiments of the present invention. Also, it is obvious to those skilled in the art to which the present invention pertains that the objects and advantages of the present invention can be realized by the means as claimed and combinations thereof. 
     In accordance with one aspect of the present invention, a valve assembly for a variable swash plate compressor includes a valve plate formed with a suction port and a discharge port, a suction reed plate installed to one side surface of the valve plate, and formed with a suction reed for opening and closing the suction port and an opening hole communicating with the discharge port, and a discharge reed plate installed to the other side surface of the valve plate, and formed with an opening hole communicating with the suction port and a discharge reed for opening and closing the discharge port, wherein the opening hole is enlarged to a position adjacent to the suction port, and a suction refrigerant flow is formed through the opening hole when the suction port is opened. 
     The suction reed may include a valve section for opening and closing the suction port and leg sections connecting the valve section to the suction reed plate, a catching end, which is caught by a catching hook formed at an edge of a cylinder bore when the suction port is opened, may be protrusively formed at a tip end of the valve section, and the catching end may have a width by which the suction refrigerant flow is capable of being generated through left and right side portions of the catching end when the suction port is opened. 
     The suction port may have a greater width than a distance between outer sides of both leg sections. 
     The valve section may have a width enlarged in left and right directions so as to be capable of fully closing the suction port. 
     The discharge reed may have an increasing width as it approaches a radially outside end portion of the discharge reed plate from a radially inside end portion thereof. 
     The suction reed may be formed wherein a distance between base end sides of the leg sections is longer than a distance between center lines at the valve section side in width directions of both leg sections. 
     Each of the leg sections may be formed such that a width at the base end side is smaller than a width at the valve section side. 
     An outside portion of the opening hole of the suction reed in a radial direction of the suction reed plate may have a semicircular shape, and thus an inside portion of the base end of the leg section may have a smooth round shape. 
     Both end portions of reed holes surrounding the suction reed may be formed with circular extension holes, and thus an outside portion of the base end of the leg section may have a smooth round shape. 
     The suction port may include first suction ports which are protrusively formed in an arc shape so as to be convex at both sides thereof, and a second suction port which is protrusively formed in an arc shape so as to be convex radially inward of the valve plate from one side of the first suction ports, and a plurality of arc portions may be formed at an end portion of the suction reed so as to correspond to the suction port. 
     The suction reed may include a first arc portion which is convexly formed radially inward of the suction reed plate so as to correspond to the second suction port, and second arc portions which are convexly formed at both sides of the first arc portion so as to correspond to the first suction ports. 
     Each of the second arc portions may be formed with an angle of 45° relative to an imaginary extension line which radially extends via the first arc portion from a center of the suction reed plate. 
     The first arc portion may have a radius of curvature greater than a radius of curvature of each of the second arc portions. 
     The radius of curvature of the first arc portion may be 4 mm to 10 mm, and the radius of curvature of each of the second arc portions may be 3 mm to 5 mm. 
     The suction reed may further include third arc portions which are concavely recessed between the first and second arc portions. 
     Each of the third arc portions may have a radius of curvature of 4 mm to 10 mm. 
     In accordance with another aspect of the present invention, a valve assembly for a variable swash plate compressor comprising a cylinder bore and a suction chamber separated from a discharge chamber by a partition wall comprises a valve plate formed with a suction port providing communication between the suction chamber and the cylinder bore and a discharge port providing communication between the discharge chamber and the cylinder bore, a suction reed plate installed to one side surface of the valve plate and formed with a suction reed for opening and closing the suction port and an opening hole communicating with the discharge port, and a discharge reed plate installed to the other side surface of the valve plate and formed with an opening hole communicating with the suction port and a discharge reed for opening and closing the discharge port, wherein the opening hole of the suction reed plate extends radially inwardly toward and at least partially beyond a radially outside edge of the partition wall and to a position adjacent the suction port, wherein a suction refrigerant flow is formed through the opening hole of the suction reed plate when the suction port is opened. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a view illustrating a configuration of a typical variable swash plate compressor; 
         FIG. 2  is an exploded perspective view illustrating a conventional valve assembly (a discharge reed plate being not shown); 
         FIG. 3  is a partially enlarged view illustrating the conventional valve assembly applied to one cylinder bore; 
         FIG. 4  is a partially enlarged perspective view illustrating a valve assembly according to an embodiment of the present invention; 
         FIG. 5  is a partially enlarged view illustrating a valve plate of the valve assembly according to the embodiment of the present invention; 
         FIG. 6  is a front view illustrating a discharge reed plate of the valve assembly according to the embodiment of the present invention; 
         FIG. 7  is a partial cross-sectional view taken along line VII-VII of the valve assembly of  FIG. 4  according to the embodiment of the present invention; 
         FIG. 8  is a partially enlarged view illustrating the valve assembly applied to one cylinder bore according to the embodiment of the present invention, and corresponds to  FIG. 3 ; 
         FIG. 9  is a flow rate-pressure graph of a compressor to which the related art (dotted line) and the present invention (solid line) are applied; 
         FIG. 10  is a partially enlarged view illustrating a suction reed plate in which a suction reed is formed according to the embodiment of the present invention; 
         FIG. 11  is an exploded perspective view illustrating a valve plate and a suction reed plate according to another embodiment of the present invention; and 
         FIG. 12  is an enlarged fragmentary view of a suction reed illustrated in  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Exemplary embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Therefore, it should be understood that the scope and spirit of the present invention can be extended to all variations, equivalents, and replacements in addition to the appended drawings of the present invention. In the description, the thickness of each line or the size of each component illustrated in the drawings may be exaggerated for convenience of description and clarity. 
     In addition, terms to be described later are terms defined in consideration of functions of the present invention, and these may vary with the intention or practice of a user or an operator. Therefore, such terms should be defined based on the entire content disclosed herein. 
     Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings. 
     As shown in  FIGS. 4 to 8 , refrigerant is introduced and discharged through a rear housing coupled to the rear of a cylinder block in a variable swash plate compressor. 
     A center bore into which one end of a rotary shaft is inserted is formed at a center of the cylinder block, so that the rotary shaft is rotatably supported by the center bore. A plurality of cylinder bores  22  is radially formed around the center bore. 
     The cylinder bores  22  are formed by penetrating the cylinder block. A piston is provided in each of the cylinder bores  22  to reciprocate by a swash plate when the rotary shaft is rotated. 
     The rear housing is formed with a circular partition wall  53  which partitions an inner space of the rear housing into inside spaces and outside spaces in a radial direction thereof. The partition wall  53  traverses the cylinder bores  22  in a state in which the cylinder block is coupled to the rear housing. In spaces partitioned by the partition wall  53 , an inside space corresponds to a partial space inside each cylinder bore  22  (inside the cylinder block in a radial direction thereof) and an outside space corresponds to the remaining space outside the cylinder bore  22 . 
     The inside spaces and the outside spaces of the rear housing are respectively suction chambers  52  and discharge chambers  51  for refrigerant. The rear housing is formed with refrigerant inlets connected to the suction chambers  52  and refrigerant outlets connected to the discharge chamber  51 . 
     Meanwhile, a valve plate  100  is provided between the rear housing and the cylinder block. The valve plate  100  has a suction port  110  formed at a portion corresponding to each suction chamber  52  and a discharge port  120  formed at a portion corresponding to each discharge chamber  51 . The suction port  110  and the discharge port  120  are formed for each cylinder bore  22 . 
     Reed plates are installed at both sides of the valve plate  100  in order to open and close the suction port  110  and discharge port  120  formed on the valve plate  100 . A suction reed plate  200  configured as an intake valve for opening and closing the suction port  110  is installed between the cylinder block and the valve plate  100 . A discharge reed plate  300  configured as a discharge valve for opening and closing the discharge port  120  is installed between the valve plate  100  and the rear housing. 
     The intake valve opens the suction port  110  only toward the cylinder bore  22  so that refrigerant may be supplied from the suction chamber  52  of the rear housing to the cylinder bore  22 . The discharge valve opens the discharge port  120  only toward the discharge chamber  51  of the rearing housing so that refrigerant compressed by the piston may be discharged from the cylinder bore  22  to the discharge chamber  51 . 
     As shown in  FIG. 4 , the suction reed plate  200  has a disc shape as a whole and the remaining portion thereof has the same shape. 
     A plurality of suction reeds  210  for opening and closing the suction ports  110  of the valve plate  100  is formed in a cut manner on the suction reed plate  200 . The suction reeds  210  have the same number as the suction ports  110  formed on the valve plate  100 . That is, the dedicated suction port  110  is formed for each cylinder bore  22  provided with the piston, and the dedicated suction reed  210  is provided for each suction port  110 . 
     Each of the suction reeds  210  includes a valve section  211  for opening and closing the associated suction port  110  and a pair of leg sections  212  for connecting the valve section  211  to the suction reed plate  200 . An opening hole  213  is formed between the pair of leg sections  212  such that a refrigerant pressure in the cylinder bore  22  may act on a discharge reed  320  through the discharge port  120 . 
     That is, the suction reed  210  is formed in such a manner that a reed hole  205  surrounding an outer portion of the suction reed  210  and the opening hole  213  are formed/drilled in the suction reed plate  200 . 
     The discharge port  120  is fully included at an outside portion of the opening hole  213  in a radial direction of the valve plate  100 , and an inside portion of the opening hole  213  in the radial direction is enlarged and extends to an adjacent position corresponding to a boundary of the suction port  110  of the valve section  211 . That is, when the valve section  211  has no problem in closing the suction port  110  and is spaced apart from the suction port  110 , a flow F1 of refrigerant introduced through the suction port  110  may also be achieved through the opening hole  213 . 
     A catching end  211   a  is protrusively formed at an inside tip end of the valve section  211  in the radial direction of the valve plate. A catching hook (not shown) corresponding to the catching end  211   a  is formed at an edge portion of the cylinder bore  22 . Accordingly, the catching end  211   a  is caught by the catching hook when the suction reed  201  is opened, thereby enabling a bending amount of the suction reed  210  to be limited. 
     A width C (see  FIG. 8 ) of the catching end  211   a  is formed to the extent of obtaining minimum rigidity required to maintain a caught state of the catching end  211   a  corresponding to a negative pressure and refrigerant flow pressure acting on the suction reed  210 . The width C of the catching end  211   a  is smaller than a width serving as a catching end in a conventional suction reed. Thus, a suction refrigerant flow may also be performed through a portion applied to a difference between the width of the conventional catching end and the width of the catching end  211   a  of the present invention when the valve section  211  is opened. That is, the catching end  211   a  has a width by which a suction refrigerant flow F2 may be generated through left and right side portions of the catching end  211   a  when the suction port  110  is opened. 
     As shown in  FIG. 5 , the valve plate  100  has one suction port  110  and one discharge port  120  formed for each position corresponding to the cylinder bore  22 . 
     The suction port  110  is formed radially inward on the valve plate  100  and the discharge port  120  is formed radially outward on the valve plate  100 . 
     The suction port  110  has a slot shape configured such that the width is further enlarged in the left and right directions compared to a conventional suction port. That is, the suction port  110  has a greater width than a distance between outer sides of both leg sections  212  of the suction reed  210 . 
     The discharge port  120  has the same circular shape as the conventional suction port but has an enlarged diameter. To this end, each discharge reed  320  has an outside end portion width B greater than an inside end portion width A, as described below. 
     As shown in  FIG. 6 , the discharge reed plate  300  has the discharge reeds  320  for opening and closing the discharge ports  120 , and the discharge reeds  320  protrude from an edge of a disc plate formed to the extent of covering a range in which the suction ports  110  of the valve plate  100  are formed. 
     Each discharge reed  320  has a semicircular outside end portion, and has the greater width B of the outside end portion than the width A of the inside end portion connected to the disc plate. Consequently, the discharge reed  320  has an area capable of fully closing the discharge ports  120 . 
     An opening hole  310  having the same shape as each suction port  110  of the valve plate  100  is formed radially outward on the disc plate. Thus, when the suction reed  210  is opened, the refrigerant in the suction chamber  52  may be introduced into the cylinder bore  22  through the opening hole  310  and the suction port  110  (also see  FIG. 7 ). 
       FIG. 10  shows the shape of each suction reed according to the embodiment of the present invention. Both leg sections  212  of the suction reed  210  are not parallel with each other. In the leg sections  212 , a width between the leg sections  212  at an end of the leg sections  212  connected to the suction reed plate  200  is greater than a width between the leg sections  212  at an end of the leg sections  212  connected to the valve section  211 . 
     When respective center lines (indicated by dotted lines) in width directions of both leg sections  212  traversing centers of both leg sections  212  in the width directions are set, a distance A between the two center lines at the valve section  211  side is shorter than a distance B between the base end sides of the leg sections  212  (A&lt;B). 
     In other words, the leg sections  212  of the suction reed  210  are formed to have a shape which is gradually spaced as approaching the base end sides connected to the suction reed plate  200 . 
     Each leg section  212  has a base end side width b smaller than a width a at the valve section  211  side (a&gt;b). 
     That is, each leg section  212  has a shape configured such that the width is gradually narrowed as approaching the base end side from the valve section  211  side. 
     The outside portion of the opening hole  213  in the radial direction of the suction reed plate  200  has a semicircular shape. Accordingly, the inside of the base end portion (which means a connection portion between the leg section  212  and the suction reed plate  200 ) of the leg section  212  has a smooth curved round shape. Therefore, stresses at the base end portion are widely distributed and thus stress concentration at the base end portion is prevented. 
     In addition, each of both end portions (applied to outside portions of the base end portions of the leg sections  212 ) of the reed holes  205  surrounding the outside portions of the suction reed  210  is formed with a circular extension hole  205   a  having a greater diameter than a width between the reed hole  205  and a side portion of each leg section  212 . 
     The outside of the base end portion of the leg section  212  has a smooth curved round shape by the extension hole  205   a . Therefore, stresses at the base end portion are widely distributed and thus stress concentration at the base end portion is prevented. 
       FIG. 11  is an exploded perspective view illustrating a valve plate and a suction reed plate according to another embodiment of the present invention.  FIG. 12  is an enlarged view of a suction reed illustrated in  FIG. 11 . 
     As shown in  FIGS. 11 and 12 , each suction port  110  of a valve plate  100  includes first suction ports  111  having an arc shape configured such that lengths are long in left and right directions and both ends are convex, and a second suction port  112  which is protrusively formed in a convex arc shape formed radially inward of the valve plate  100  from one side of the first suction ports  111 . In addition, the suction port  110  may further include a third rectangular suction port  113  which faces the second suction port  112  and is protrusively formed radially outward of the valve plate  100 . 
     A plurality of arc portions is formed at an end portion of each suction reed  210  so as to correspond to the shape of the suction port  110  of the valve plate  100 . In more detail, the arc portions includes a first arc portion  211   b  which is convexly formed radially inward of a suction reed plate  200  so as to correspond to the second suction port  112 , and second arc portions  211   c  which are convexly formed at both rear sides of the first arc portion  211   b  so as to correspond to the first suction ports  111 . 
     Here, third arc portions  211   d  are concavely formed between the first and second arc portions  211   b  and  211   c , in order for the first arc portion  211   b  to be easily elastically deformed. In addition, a radius of curvature of each of the first and third arc portions  211   b  and  211   d  is preferably 4 mm to 10 mm, and a radius of curvature of each of the second arc portions  211   c  is preferably 3 mm to 5 mm so as to be smaller than the radius of curvature of each of the first and third arc portions  211   b  and  211   d . This is because the first arc portion  211   b  opens and closes the second suction port  112  which is a main passage and the second arc portions  211   c  open and close the first suction ports  111  which are auxiliary passages. 
     A pair of second arc portions  211   c  is preferably formed with respective angles of 45° relative to an imaginary extension line which radially extends via the first arc portion  211   b  from the center of the suction reed plate  200 , such that directions of the passage are not overly diffused when the suction reed  210  is opened. That is, an imaginary line L1 which radially outwardly extends via the first arc portion  211   b  from the center of the suction reed plate  200  forms an angle of 45° with an imaginary line L2 which connects the radius of curvature of the second arc portion  211   c  to an intermediate portion M of the second arc portion  211   c.    
     In this case, when the second arc portion  211   c  is formed with an angle less than 45° relative to the first arc portion  211   b , elastic force of the first arc portion  211   b  is reduced. When the second arc portion  211   c  is formed with an angle greater than 45° relative to the first arc portion  211   b , a time for which the first arc portion  211   b  is opened and then the second arc portion  211   c  is opened is slightly delayed. For this reason, it may be impossible to immediately respond the request for an increase in suction flow rate. 
     Reference numeral  220  is a cut section machined to form the suction reed  210  in the suction reed plate  200 . 
     Hereinafter, the operation and effect of the present invention will be described. 
     The suction stroke of refrigerant is as follows. When the piston is moved to a top dead center and a negative pressure is generated in the cylinder bore  22 , the suction reed  210  is bent toward the cylinder bore  22  while the valve section  211  is spaced apart from the valve plate  100 , so that the suction port  110  is opened. 
     The valve section  211  of the suction reed  210  is maintained in a state spaced apart from the suction port  110  by a predetermined distance in such a manner that the catching end  211   a  is caught by the catching hook of the cylinder block in a state in which the suction port  110  is opened. In this state, the refrigerant is introduced through the suction port  110 . Since the suction port  110  has a slot shape enlarged in the left and right directions, a refrigerant introduction amount is increased by an increase of the area of the suction port. 
     Particularly, since the radially inside end portion of the opening hole  213  of the suction reed  210  is formed adjacent to the suction port  110 , the refrigerant introduced into the suction port  110  may also be introduced into the cylinder bore  22  through the opening hole  213 . That is, a portion closed by the conventional suction reed is opened by extension of the opening hole  213 , and thus a new refrigerant flow F1 is generated through the portion. Consequently, a suction flow rate of refrigerant may be increased (see  FIG. 8 ). 
     In addition, the width of the catching end  211   a  maintained in a caught state when the suction reed  210  is opened is reduced, and thus a portion in which the refrigerant may flow is formed at the tip end portion of the valve section  211 , in more detail, at both portions of the catching end  211   a . Accordingly, since a new refrigerant flow F2 is generated through a new flow space obtained by the reduction of the width of the catching end, the suction flow rate of refrigerant may be increased. 
     That is, in the related art, the refrigerant flow is present only in the left and right directions (directions indicated by arrows in  FIG. 3 ) of the suction port, and is hardly present inwardly and outwardly in the radial direction (which means the radial direction of the suction reed plate). However, in the present invention, the refrigerant flow F2 is also present radially inwardly (in the left and right side portions of the catching end  211   a ) as well as both directions of the suction port. Particularly, the refrigerant flow F1 is actively performed radially outwardly (in the portion of the opening hole  213  side). 
       FIG. 9  is a graph illustrating a relation between the suction refrigerant flow rate and the pressure according to the related art and the present invention. In  FIG. 9 , the dotted line refers to the related art and the solid line refers to the present invention. In comparison with two lines, it may be seen that a pressure required to reach the same flow rate is reduced in the present invention compared to the related art. That is, it may be seen that the present invention generates a greater flow rate under the same pressure condition. 
     Meanwhile, since the discharge port  120  of the present invention has an increased area compared to the conventional discharge port, the refrigerant in the cylinder bore  22  may be more smoothly discharged to the discharge chamber  51  of the rear housing through the discharge port  120  when the compression is performed by the piston. 
     As described above, according to the present invention, the suction flow may be actively performed through the extension of the suction port  110  and the improvement of the shape of the suction reed  210  and the discharge flow may be smoothly performed through the extension of the discharge port  120 . Accordingly, when the compressor is driven under the same conditions, the performance of the compressor may be enhanced by the increase of refrigerant which is introduced, compressed, and discharged. 
     It may be possible to reduce operation noise and pulsation since a method of increasing the driving speed of the compressor is not adopted when the increase in refrigerant flow rate is promoted for enhancing the performance of the compressor. The durability of the compressor may be improved. 
     In addition, when the suction reed  210  is opened and closed, the leg sections  212  of the suction reed  210  are formed to have a shape which is gradually spaced as approaching the base end sides from the valve section  211  (A&lt;B) and thus torsional rigidity of the suction reed  210  is improved. 
     When the suction negative pressure and the refrigerant pressure do not uniformly act on the entirety of the valve section  211 , the valve section  211  is inclined and torsion is generated in the leg sections  212 . However, it may be possible to reliably correspond to the torsion generated in the valve section  211  since the distance between the both leg sections  212  is gradually increased as approaching the base end portions. 
     Accordingly, it may be possible to prevent stresses from being concentrated at the base ends of the leg sections  212  due to torsion deformation and thus to prevent fatigue from being accumulated. 
     In addition, since each leg section  212  has the base end side width b smaller than the width a at the valve section  211  side, the base end side is relatively flexible and thus the stresses are prevented from being concentrated at the base end side. 
     The inside of the base end portion of the leg section  212  has a smooth curved round shape since the outside portion of the opening hole  213  in the radial direction of the suction reed plate  200  has a semicircular shape. Therefore, the stresses at the inside of the base end portion are effectively distributed and thus stress concentration at the inside of the base end portion is prevented. 
     The outside of the base end portion of the leg section  212  has a smooth curved round shape since both end portions of the reed holes  205  are formed with the extension holes  205   a . Therefore, the stresses at the outside of the base end portion are effectively distributed and thus stress concentration at the outside of the base end portion is prevented. 
     As described above, the stress concentration at the base end portion of the leg section  212  is prevented by various shape factors of the suction reed  210  and the stresses are distributed to the peripheries of the base end portion. Consequently, damage of the leg section  212  caused by accumulation of fatigue is prevented. 
     According to a result of analyzing stress distribution, the maximum principal stress applied to the base end of the leg section  212  is 337.23 Mpa. Therefore, it may be seen that the maximum principal stress is reduced compared to the maximum principal stress of 436.69 Mpa applied to the same portion in the related art. 
     Meanwhile, according to another embodiment of the present invention, the suction reed  210  is elastically deformed by the pressure of the suction refrigerant during the suction stroke to open the suction port  110 . In this case, the first arc portion  211   b  first opens the second suction port  112  while being elastically deformed toward the cylinder bore. Subsequently, when the pressure of the suction refrigerant is increased, the second arc portions  211   c  are elastically deformed to open the first suction ports  111  together with the first arc portion  211   b.    
     In this case, since the circumferential width of each first suction port  111  is greater than the circumferential width of the second suction port  112  (here, the first suction port being two portions), the refrigerant introduced through the first suction port  111  is uniformly introduced into the cylinder bore along the edge of the first suction port  111  without obstruction of the flow of the refrigerant introduced through the second suction port  112 . 
     That is, according to the embodiment of the present invention, the refrigerant is introduced through the first suction port  111  as well as the second suction port  112  corresponding to the conventional suction port. Accordingly, the flow rate of the suction refrigerant may be increased and thus the performance of the compressor may be enhanced. 
     For example, in the compressor adopting the conventional suction reed  64  shown in  FIG. 2 , the compressor exhibits performance of 4220 W at 800 rpm and 5480 W at 2000 rpm. However, it may be seen that the compressor adopting the suction reed  210  according to the embodiment of  FIG. 11  exhibits excellent performance of 4720 W at 800 rpm and 6150 W at 2000 rpm. 
     As is apparent from the above description, an area of a suction port is increased, and thus a suction flow rate of refrigerant is increased. 
     Since an area of a valve section of a section reed is increased according to the increase of the area of the suction port, the suction port may be reliably opened and closed. 
     Since an opening hole of the suction reed is enlarged toward the valve section to be formed adjacent to the suction port of a valve plate, a flow of refrigerant is further generated through the opening hole, thereby increasing the suction flow rate. 
     In addition, an area of a discharge port is increased, and thus a discharge flow rate of refrigerant is increased. 
     Since an area of a valve section of a discharge reed is increased according to the increase of the area of the discharge port, the discharge port may be reliably opened and closed. 
     Accordingly, refrigerant is smoothly introduced and discharged, and thus the suction and discharge flow rates of refrigerant are increased. As a result, performance of a compressor may be enhanced. 
     Since the performance of the compressor is enhanced without an increase in driving speed of the compressor, noise and pulsation caused by the mere increase of the driving speed of the compressor may be prevented. 
     In addition, since stresses applied to a base end portion of the suction reed are easily distributed, the base end portion of the suction reed has a reduced maximum principal stress applied thereto so as to prevent damage of the suction reed. 
     Since a series of processes in which the refrigerant is introduced, compressed, and discharged are normally performed by the prevention of the damage of the suction reed, the compressor may be normally operated. As a result, a service life of the compressor is extended. 
     Since durability of the suction reed is improved with no change of material, production costs of the compressor may be greatly reduced. 
     The suction port of the refrigerant may be more accurately and stably opened and closed by an improvement in rigidity against a torsional load of the suction reed. 
     In addition, according to an embodiment of the present invention, the refrigerant is uniformly introduced into cylinder bores through many portions of the suction port when the suction reed is opened. Thus, fluidity of the introduced refrigerant is increased and the suction flow rate is increased. Consequently, the performance of the compressor may be enhanced. 
     While the present invention has been described with respect to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.