Abstract:
A discharge valve of a hermetic compressor includes a valve plate disposed on a cylinder head that sucks and discharges refrigerant according to reciprocal movement of a piston, and the discharge valve having a discharge hole formed therein through which refrigerant is discharged, a disc valve disposed adjacent the discharge hole of the valve plate, the disc valve being raised or lowered by the reciprocal movement of the piston, and a stopper disposed above the disc valve, for guiding the raising and lowering of the disc valve and also for limiting the height to which the disc valve may be raised. The compressor is not subject to overload or over pressurization that may otherwise result from the elastic force of the valve, and as a result, compression efficiency is increased, while noise is decreased.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates generally to a hermetic compressor, and more particularly, to a discharge valve of a hermetic compressor which is installed in a cylinder head and discharges a compressed refrigerant.  
           [0003]    2. Description of the Related Art  
           [0004]    Generally, a hermetic compressor is employed in equipment using a refrigerant, such as an air conditioner, and a refrigerator, for compressing the refrigerant.  
           [0005]    As shown in FIG. 1, a general conventional hermetic compressor comprises a stator  1 , a rotor  2  rotating inside the stator  1 , a crank shaft  3  revolving with the rotor  2 , a piston  5  connected to the crank shaft  3 . A connecting rod  4 , reciprocates linearly with the revolution of the crankshaft  3 . A cylinder  6  forms a compressive chamber  6 B, together with the piston  5 , and a valve assembly  7  assembled into a cylinder head  6 A for controlling the discharge and a suction of the refrigerant.  
           [0006]    The valve assembly  7  consists of a suction valve, which opens during a suction stroke when the piston  5  moves to the bottom dead center and closes during a discharge stroke when the piston moves to the top dead center, and a discharge valve, which opens during the discharge stroke and closes during the suction stroke.  
           [0007]    Referring to FIG. 2, the discharge valve  10  includes a valve plate  11 , a reed valve  13 , a stopper  14 , and a keeper  16 .  
           [0008]    The valve plate  11  has a suction hole  8  for sucking refrigerant into the chamber  6 B (FIG. 1) and a discharge hole  12  for discharging refrigerant The discharging hole  12  is formed in a recess  11 A of the discharge plate  11 .  
           [0009]    Within the recess  11 A are consecutively piled on and installed in sequences the reed valve  13  for opening/closing the discharge hole  12 , the stopper  14  for controlling the degree of opening of the reed valve  13 , and the keeper  16  for preventing the reed valve  13  and the stopper  14  from separation from the discharge plate  11 .  
           [0010]    The operation of the conventional hermetic compressor comprising the same structure as that described above is explained hereafter.  
           [0011]    When the rotor  2  rotates by the mutual operation of the rotor  2  and the stator  1 , the crank shaft  3  assembled together with the rotor  2  revolves. When the crank shaft  3  rotates, the refrigerant is sucked and discharged as the piston  5  reciprocates rectilinearly A inside the cylinder  6  by the reciprocal action of the connecting rod  4  eccentrically assembled at the end of the crank shaft  3 .  
           [0012]    At the time of a discharge stroke, the piston  5  moves to the bottom dead center and the compressive chamber  6 B forms a vacuum. Accordingly, the suction valve (not shown) of the suction hole  5  opens by the suction force of the vacuum and the refrigerant flows into the compressive chamber  6 B. At this point, the reed valve  13  (FIG. 2) keeps the discharge hole  12  closed. When the piston  5  reaches the bottom dead center, the piston  5  moves back to the top dead center and thereby the discharge stroke compresses the refrigerant and discharges it through the discharge hole  12  and into a discharge tube  9  (FIG. 1). During the discharge stroke, the suction valve closes off the suction hole  8  by means of the pressure of the compressed refrigerant whereby the compressed refrigerant is discharged through the discharge hole  12  by the same pressure pushing up the reed valve  13  and the stopper  14 .  
           [0013]    In addition, when the piston  5  reaches the top dead center, it begins its movement back again to the bottom dead center, the reed valve, which was moved up and open, falls down and closes the discharge hole  12  and continuous suction and discharge of the refrigerant proceed as the suction valve of the suction hole  8  opens.  
           [0014]    Accordingly, the hermetic compressor continues the refrigerating cycle of sucking the refrigerant, compressing the sucked refrigerant and discharging the compressed refrigerant in accordance with the above described process.  
           [0015]    However, in the above discharge valve  10 , in order for the refrigerant to be discharged during the discharge stroke the discharge hole  12  should be opened by action of lifting the reed valve  13  and the stopper  14 . In other words, since the discharge pressure of the refrigerant should be higher than the total force of the elasticity of the reed valve  13  and the stopper  14  in order for the discharge hole  12  to remain open, thereby allowing the refrigerant to discharge, more refrigerant pressure than the pressure required for operation of the pressurization of the refrigerant will be required in compressive chamber  6 B. When the cylinder  6  is over pressurized, more power is needed to rotate the rotor  2 , thereby resulting in the operation of the hermetic compressor to a less efficient state.  
           [0016]    Additionally, it is also problematic in that the compressor makes loud noises due to the beating or impulse sounds made by the reed valve  13  hitting the top of the discharge hole  12  by the elasticity of the reed valve  13  and the stopper  14 , and in the discharge force of the piston  5  occurring at the time of the suction stroke.  
           [0017]    Furthermore, it is a problem that the discharge valve  10  requires too many i structural elements and forms a complex shape and therefore is not easy to manufacture or assemble.  
         SUMMARY OF THE INVENTION  
         [0018]    The present invention has been made to overcome the above-mentioned problems of the related art, and accordingly, it is an object of the present invention to provide a discharge valve of the hermetic compressor that is quiet and effective as a result of the cylinder not being over-pressurized by compressing and discharging the refrigerant against the weight of the valve itself during the discharge stroke.  
           [0019]    Another object of the present invention is to provide a discharge apparatus of a hermetic compressor that is simple in shape, processable and assemblable by being comprised of a small number of structural elements.  
           [0020]    In order to achieve the above objects, according to the present invention a discharge valve of a hermetic compressor is installed in a cylinder head which opens and closes according to the reciprocal movement of a piston reciprocally moving within the cylinder head, for discharging compressed refrigerant. The discharge valve of the hermetic compressor includes a valve plate disposed on the cylinder head of the hermetic compressor providing suction and discharge of refrigerant according to reciprocal movement of the piston, The discharge valve has a discharge hole formed therein through which refrigerant is discharged, a disc valve disposed above the discharge hole of the valve plate, being raised or lowered by the reciprocal movement of the piston, and a stopper disposed adjacent the disc valve and separated from the discharge hole, for guiding the raising and lowering of the disc valve and also for limiting the height to which the disc valve may be raised to a predetermined range. Alternatively, a hermetic compressor having a cylinder head and a piston for providing sequentially suction and discharge of a refrigerant during a compression/decompression cycle, adjacent to a discharge valve, the discharge valve may comprise a valve plate disposed on the cylinder head including a discharge hole formed therein for discharge of the refrigerant, a disc valve disposed adjacent the discharge hole of the valve plate, so as to cover the discharge hole during a portion of the compression/decompression cycle depending on the pressure developed within the cylinder head by the piston, and a stopper, adjacent to the disc valve and spaced from the discharge hole, including guides for guiding the orientation of the disc valve and a stopper portion for limiting to a predetermined range the reciprocal motion of the disc valve between the disc hole and the stopper portion.  
           [0021]    Preferably, the stopper is connected to the valve plate with a space therebetween by a plurality of guiding pins that are standing upright around the discharge hole of the valve plate, to thereby guide the disc valve by point-contact between the disc valve and the guiding pins.  
           [0022]    In another embodiment, the stopper is connected to the valve plate with a space therebetween due to supporting members extending downward from two ends of the stopper, for guiding the disc valve by line-contact of the supporting member and an edge of the disc valve. The stopper is connected to the valve plate with a space therebetween due to a supporting member extending downward from one end of the stopper, and has a plurality of guiding pins protruding from the other end of the stopper toward the valve plate for guiding the disc valve.  
           [0023]    The stopper preferably comprises at least three guiding pins, one end of each guiding pin being connected to a circumference of the discharge hole of the valve plate in a vertical manner, while on the other end of each guiding pin is formed an extended end for limiting the height to which the disc valve may be raised. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]    The aforementioned objects and characteristics of the present invention will be made more apparent by describing a preferred embodiment of the present invention in greater detail with reference to the accompanying drawings, in which:  
         [0025]    [0025]FIG. 1 is a sectional side view showing a general conventional hermetic compressor;  
         [0026]    [0026]FIG. 2 is an exploded perspective of a conventional discharge valve;  
         [0027]    [0027]FIG. 3 is an exploded perspective showing the first embodiment of a discharge valve of the hermetic compressor in accordance with the present invention;  
         [0028]    [0028]FIG. 4A is a sectional view showing the disc valve of FIG. 3 being guided by three guiding pins;  
         [0029]    [0029]FIG. 4B is a sectional view showing the disc valve of FIG. 3 being guided by two guiding pins;  
         [0030]    [0030]FIG. 5A is a cross-sectional view showing the discharge valve of FIG. 3 in a closed position;  
         [0031]    [0031]FIG. 5B is a cross-sectional view showing the discharge valve of FIG. 3 in an open position;  
         [0032]    [0032]FIG. 6 is a cross-sectional view showing a second embodiment of the hermetic compressor according to the present invention;  
         [0033]    [0033]FIG. 7 is a cross-sectional view showing a third embodiment of the hermetic compressor according to the present invention;  
         [0034]    [0034]FIG. 8 is a perspective view showing a fourth embodiment of the hermetic compressor according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    Hereinafter, a preferred embodiment of the present invention will be described in greater detail with reference to the accompanying drawings.  
         [0036]    Referring to FIGS.  3  to  5 B, the hermetic compressor  100  according to the first embodiment of the present invention includes a valve plate  101 , a disc valve  103 , a stopper  105  and a number of guiding pins  107 .  
         [0037]    The valve plate is disposed on the cylinder head and has a discharge hole  102  for discharging a refrigerant and a suction hole (not shown) for sucking refrigerant into the compression chamber. It is preferable that a seating portion  102   a  is formed at the top of the discharge hole  102 , as shown, for the disc valve  103  to effectively close the discharge hole  102 .  
         [0038]    Being located at the top of the discharge hole  102 , the disc valve  103 , which is used for closing the discharge hole  102 , helps the refrigerant to be compressed by closing the discharge hole with its own weight at the time of the discharge stroke and helps the refrigerant to be discharged as the disc valve  103  is raised by the pressure when the compressive force inside the cylinder exceeds the disc valve weight. Preferably the disc valve  103  is shaped and dimensioned to be bigger than the diameter of the discharge hole  102  so that it can close the discharge hole  102  and may take the shape of a disc, although it is preferred that the shape corresponds to the shape of the discharge hole  102 .  
         [0039]    The stopper  105  is disposed on the top of the discharge valve  103  of the discharge hole  102  and restricts the height the disc valve  103  can be raised when the disc valve  103  is raised by the pressure of the refrigerant during the discharge stroke. Additionally, the middle of the stopper has a through hole  105 A communicating with the discharge hole  102  for smooth flow of the discharged refrigerant.  
         [0040]    Each guiding pin  107 , having a cylindrical shape, fastens the stopper to the valve plate  105  so that the stopper can be attached at a predetermined distance from the valve plate  105 . The guiding pins  107  guide the disc valve  103  during the raising and lowering movements. The method of fastening the guiding pins  107  to the valve plate  101  can take various forms, including welding, but riveting  108 , as shown in FIG. 5A and.  5 B, is preferable. In addition, for the guiding pin  107  to guide the raising and lowering movement stably and by engaging the disc  103  in point-contact, at least three guiding pins  107  are needed, as shown in FIG. 4A. Undoubtedly, in the case of the alternative shape of the disc valve  103 ′ being as that shown in FIG. 4B, two guiding pins  107  only can stably guide the raising and lowering movement of the disc valve  103 ′.  
         [0041]    The movement of the discharge valve in the first embodiment having the above described structure is described below.  
         [0042]    Referring now to FIGS. 5A and 5B, when the piston moves to the bottom dead center during the suction stroke, the discharge valve is opened by the suction force of the vacuum formed in the cylinder and the refrigerant is sucked into the cylinder. At the same time, the disc valve  103  drops down by the suction force of the vacuum and the weight of the disc valve  103  and closes the discharge hole  102  as shown in FIG. SA.  
         [0043]    When the piston reaches the bottom dead center, it starts to compress the sucked refrigerant while moving back to the top dead center. If the compressive pressure force developed by the piston exceeds the weight of the disc valve  103 , the disc valve  103  will lift along the guiding pins  107 . As the disc valve  103  is lifted, its movement is stopped by the stopper  105 , as shown in FIG. 5B, and the compressed refrigerant being discharged through the discharge hole  102  is discharged through the space between the disc valve  103  and the valve plate  101  and finally throughout the discharge tube  9  (FIG. 1).  
         [0044]    During the discharge stroke, since the piston moves back to the bottom dead center and starts the suction stroke when it reaches the top dead center, suction and discharge of the refrigerant continue.  
         [0045]    As the disc valve  103  is guided by the three guiding pins and engages them in point-contact during the discharge and suction stroke, it can stably open and close the discharge hole  102 .  
         [0046]    The hermetic compressor  110  according to a second embodiment of the present invention, shown in FIG. 6, is identical to the hermetic compressor  100 , according to the first embodiment, except for having supporting members connected to the lower part of the stopper, instead of a connection of the guiding pins  107 . The supporting members help the stopper keep its predetermined distance and also guide the disc valve  103 . In FIG. 6, the supporting members  112  are fastened to the valve plate  101  by the rivet  113 , but the method for fastening the supporting members  112  can take various forms, including welding. Cantilevered sections of the supporting members  112  form a stopper  111  that define a through hole  111   a  provided at the stopper.  
         [0047]    The movement of the discharge valve  110  according to the second embodiment is identical to that of the first embodiment except that the disc valve  103  is guided by line-contact with the inner surface of the supporting members  112  and the operation therefore will not be described in detail.  
         [0048]    Additionally, the discharge valve according to a third embodiment of the present invention is shown in FIG. 7.  
         [0049]    The discharge valve  120  according to the third embodiment is comprised of a valve plate  101  having a discharge hole  102 , a disc valve  103  opening and closing the discharge hole  102  according to the reciprocating movement of a piston, and a canti-levered stopper  121  restricting the height to which of the disc valve  103  may be raised.  
         [0050]    One end of the stopper  121  is fastened at a predetermined distance from the valve plate  101  by the supporting members  122  which extend toward the valve plate  101  by the cantilevered section. The fastening means for the supporting members  112  can include welding, as well as riveting  124 , which is shown in FIG. 7.  
         [0051]    In addition, the other end of the stopper has a number of guiding pins  123  that can guide the disc valve  103 . The guiding pins  123  protrude toward the valve plate  101  and the inner space of the circle formed by the guiding pins  123  defines a through hole  121   a.    
         [0052]    The detailed description of the third embodiment having the above structure will be omitted as it is identical to the first embodiment except that the guiding pins  123  only function for guiding the disc valve  103  and the supporting members  122  of the stopper  121  limit the height to which the disc valve  103  may be raised.  
         [0053]    Referring to FIG. 8, the hermetic compressor  130  according to a fourth embodiment of the present invention has an identical structure to that of the first embodiment  100  except that the stopper is provided by the guiding pins  131  having extended end portions  13  la.  
         [0054]    In the fourth embodiment  130 , the height to which the disc valve  103  may be raised is determined by the height of the extended end portion of the guiding pins  131  measured from the surface of the valve plate  101 , and the raising and lowering movements of the disc valve  103  are guided by the guiding pins. Two guiding pins  131  may be sufficient but three are preferable.  
         [0055]    According to the discharge valve of the hermetic compressor according to the present invention, as described above, the weight of the disc valve  103  only is applied in opening and closing the discharge hole  102  and the piston will not be over pressurized at the time of discharge since the elasticity of the reed valve  13  and the stopper  14 , as in the conventional compressor, are not utilized in the present invention.  
         [0056]    In addition, at the time of the suction stroke when the disc valve  103  closes the discharge hole  102 , the noises reduce as the beating sounds reduce since the top of the discharge hole  102  is beaten only by the suction force and the weight of the disc valve  103  and the elasticity and the beating force of the reed valve  13  and the stopper  14  are not heard.  
         [0057]    Also, the ease of manufacture and assembly and reliability of the products increase in comparison to the conventional discharge valve as the discharge valve simply comprises the disc valve  103  and the stopper  105 .  
         [0058]    As described above, according to the discharge valve of the hermetic compressor of the present invention, the efficiency of the hermetic compressor can be improved as the disc valve  103  opens and closes the discharge valve by its own weight and the piston will not be over pressurized at the time of the discharge.  
         [0059]    Additionally, the noises made by the beating sounds from the discharge hole reduce as the discharge hole is opened and closed by the weight of the disc valve  103  and the suction force only.  
         [0060]    In addition, the ease of manufacture and assembly and reliability of the products increase as the shape of the discharge valve is simplified to a disc shape and a number of structural elements are eliminated.  
         [0061]    Although the preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that the present invention should not be limited to the described preferred embodiments. Various changes and modifications can be made while utilizing the present invention, meanwhile remaining within the spirit and scope of the present invention, as defined by the appended claims.