Patent Publication Number: US-2004052666-A1

Title: Valve assembly for hermetic compressor

Description:
TECHNICAL FIELD  
       [0001] The present invention relates to a hermetic compressor, and in particular to a valve assembly for a hermetic compressor which is capable of simplifying its structure and improving a compressing efficiency.  
       BACKGROUND ART  
       [0002] Generally, compressors can be divided into several kinds according to compressing types, in an air conditioning apparatus required to be small and lightweight, a hermetic reciprocating compressor is mainly used.  
       [0003] The hermetic reciprocating compressor is constructed with an enclosed casing, a driving unit housed in the casing and generating a driving force and a compressing unit, etc. compressing a fluid by a rotational force generated by the driving unit.  
       [0004] The compressing unit includes a cylinder at which a fluid flows into, a piston housed in the cylinder so as to be performable a reciprocating motion, a valve assembly, etc. supplying the fluid to the cylinder and discharging the compressed fluid by being connected to the cylinder. Accordingly, the compressing unit compresses a fluid flowing into the cylinder by the reciprocating motion of the piston and discharges it through the valve assembly.  
       [0005] The valve assembly is constructed with a cylinder head fastened to the cylinder and having a suction/discharge hole, a suction/discharge valve installed to the cylinder head, a packing for sealing hermetically and a head cover, etc. installed to the cylinder head and having a suction channel sucking a fluid from outside and a discharge channel discharging a compressed fluid.  
       [0006] Because the valve assembly affects a performance of the compressor, a development of the valve assembly proceeds steadily.  
       [0007] In the valve assembly presented in the U.S. Pat. No. 4,723,896, a groove having a specific size is formed around a discharge hole of a cylinder head, a valve for opening/closing the discharge hole is placed inside the groove, and a valve spring for a returning operation of the valve is installed to the valve. And, a retainer fixedly maintaining positions of the valve spring and the valve is installed so as to contact with the bottom surface of the groove.  
       [0008] In the retainer, a clamp is inserted into a notch formed at the cylinder head in order to fix each construction part.  
       [0009] However, in the conventional valve assembly, because a valve spring and a retainer, etc. are installed additionally besides base construction parts such as a cylinder head, a suction/discharge valve and a head cover, its structure is intricate due to lots of construction parts.  
       [0010] In addition, in the conventional valve assembly, because an additional process for forming a groove around a discharge hole of a cylinder head is required, a production cost and a production time are increased, and a productivity is lowered.  
       [0011] In addition, in the conventional valve assembly, a discharge valve is fixed to a cylinder head with a valve spring by a retainer, etc., a groove for inserting the valve, the valve spring and the retainer, etc. is formed at the cylinder head, because each construction part is fabricated so as to have a certain tolerance in consideration of a facility of an assembly and a fabrication error, when a discharge of a fluid is instantly performed under a high discharge pressure, a discharge valve may not operate accurately, accordingly a discharge efficiency may be lowered.  
       [0012] In addition, when a high pressure occurs instantly in a discharging process of a refrigerant, the discharge valve may orderly collide with the valve spring and the retainer, etc., accordingly a noise may occur.  
       TECHNICAL GIST OF THE PESENT INVENTION  
       [0013] In order to solve the above-mentioned problems, it is an object of the present invention to provide a valve assembly for a hermetic compressor which is capable of facilitating an assembly and reducing a production cost by simplifying a structure of a valve assembly and minimizing the number of construction parts.  
       [0014] It is another object of the present invention to provide a valve assembly for a hermetic compressor which is capable of improving a suction and a discharge efficiencies of a compressor and improving a performance of the compressor by being operated stably under a high compressing pressure.  
       [0015] It is yet another object of the present invention to provide a valve assembly for a hermetic compressor which is capable of lowering a noise occurred in a compressing by minimizing a relative motion of a valve, etc. according to variation of a compressing pressure and collisions between construction parts.  
       [0016] In order to achieve the above-mentioned objects, a valve assembly for a hermetic compressor in accordance with the present invention includes a cylinder head installed to an opened end of a cylinder having a specific space filled with a fluid and having a suction hole and a discharge hole, a suction valve fixed to a certain surface of the cylinder head and opening/closing the suction hole, a discharge valve fixed to the other surface of the cylinder head and opening/closing the discharge hole and a head cover fixed to the surface of the cylinder head and having a suction space at which a fluid is sucked and a discharge space at which a fluid is discharged.  
       [0017] The assembly for the hermetic compressor in accordance with the present invention further includes a gasket placed between the cylinder head and the head cover and preventing a leakage of the fluid.  
       [0018] The cylinder head is formed as a plate shape having a certain thickness endurable a pressure of the fluid pressurized inside the cylinder.  
       [0019] The suction valve includes a fixation portion fixed to the surface of the cylinder head, an opening/closing portion contacted to the suction hole, opening/closing the suction hole and having a diameter larger than a diameter of the suction hole and a connecting portion connected between the opening/closing portion and the fixation portion and applying a specific elastic force to the opening/closing portion in a direction contacting to the suction hole.  
       [0020] The fixation portion is formed so as to have a width larger than a width of the connecting portion in order to be stably fixed to the cylinder head.  
       [0021] The fixation portion is fixed to the surface of the cylinder head by a welding.  
       [0022] The connecting portion is a plate spring having a specific length and a specific width to provide a certain elastic force to the opening/closing portion within a range not disturbing a flow of the fluid flowing into the cylinder.  
       [0023] The opening/closing portion is formed as a circular plate shape having a diameter larger than a diameter of the suction hole.  
       [0024] The discharge valve includes a fixation portion fixed to the surface of the cylinder head combined with the head cover, an opening/closing portion contacted to the discharge hole, performing an opening/closing operation and having a diameter larger than a diameter of the discharge hole and a connecting portion connected between the opening/closing portion and the fixation portion and providing a certain elastic force in a direction at which the opening/closing portion is contacted to the suction hole.  
       [0025] The fixation portion is formed so as to have a width larger than a width of the connecting potion in order to be stably fixed to the surface of the cylinder head.  
       [0026] The fixation portion is fixed to the surface of the cylinder head by a welding.  
       [0027] The connecting portion is formed so as to have a width larger than a width of the connecting portion of the suction valve.  
       [0028] The connecting portion is formed so as to have a length shorter than a length of the connecting portion of the suction valve.  
       [0029] The opening/closing portion is formed as a circular plate shape having a diameter larger than a diameter of the discharge hole.  
       [0030] The head cover includes a suction space at which the fluid flows into from outside by connecting to the suction hole, a discharge space separated from the suction space by a septum wall, connected to the discharge hole and discharging the compressed fluid to outside and a fixation surface formed on the front surface and fixing the fixation portion of the discharge valve.  
       [0031] The head cover further includes a supporting portion formed by being extended from the fixation surface along the discharge valve and restricting an opening range of the discharge valve.  
       [0032] The supporting portion is constructed with a first supporting portion in order to support the connecting portion of the discharge valve and a second supporting portion extended from the first supporting portion so as to be inclined at a certain angle in order to restrict an opening range of the opening/closing portion of the discharge valve.  
       [0033] A valve assembly for a hermetic compressor in accordance with another embodiment of the present invention includes a cylinder head installed to an opened side of a cylinder having a certain space filled with a fluid and having a suction hole and a discharge hole, a suction valve fixed to the side of the cylinder head and opening/closing the suction hole, a discharge valve fixed to the other side of the cylinder head and opening/closing the discharge hole, a head cover fixed to the side of the cylinder head and having a suction channel at which the fluid is sucked and a discharge channel at which the fluid is discharged, a first reinforcing member placed between the cylinder head and the cylinder in order to reinforce the cylinder head and having a space for housing the suction valve, and a second reinforcing member placed between the cylinder head and the head cover in order to reinforce the cylinder head and having a space for housing the discharge valve.  
       [0034] The first reinforcing member is formed as a plate shape including a suction valve installing portion punched so as to have the same shape as the suction valve in order to place the suction valve and a connecting hole connected to the discharge hole of the cylinder head.  
       [0035] The second reinforcing member is formed as a plate shape including a discharge valve installing portion punched so as to have the same shape as the discharge valve in order to place the discharge valve and a connecting hole connected to the suction hole of the cylinder head. 
     
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
     [0036] 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.  
     [0037] In the drawings:  
     [0038]FIG. 1 is a transverse sectional view illustrating a hermetic compressor in accordance with the present invention;  
     [0039]FIG. 2 is a disassembled perspective view illustrating a valve assembly for a hermetic compressor in accordance with the present invention;  
     [0040]FIG. 3 is a front view illustrating a suction valve of a valve assembly in accordance with the present invention;  
     [0041]FIG. 4 is a front view illustrating a discharge valve of a valve assembly in accordance with the present invention;  
     [0042]FIG. 5 is a sectional view taken along the line A-A of FIG. 2;  
     [0043]FIG. 6 is a front view illustrating a first supporting member of a valve assembly in accordance with the present invention; and  
     [0044]FIG. 7 is a front view illustrating a second supporting member of a valve assembly in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0045] Hereinafter, embodiments of a valve assembly for a hermetic compressor in accordance with the present invention will be described with reference to accompanying drawings.  
     [0046] There can be a plurality of embodiments of the present invention, hereinafter the preferred embodiment will be described.  
     [0047]FIG. 1 is a transverse sectional view illustrating a hermetic compressor in accordance with the present invention.  
     [0048] A hermetic compressor in accordance with the present invention includes an enclosed casing  10  at which a suction pipe  2  and a discharge pipe  4  are respectively connected, a driving unit  12  housed in the lower portion of the casing  10  and generating a rotational force, and a compressing unit  14  arranged at the upper portion of the casing  10 , compressing a fluid sucked into the suction pipe  2  with the rotational force generated by the driving unit  10  and discharging the fluid to the discharge pipe  4 .  
     [0049] In the casing  10 , an upper casing  6  and a lower casing  8  are combined each other and sealed in order to prevent a leakage of the fluid flowing into.  
     [0050] The driving unit  12  is fixed inside the casing  10  and is constructed with a stator  16  receiving power from outside, a rotator  18  placed at the side (toward the center of the driving unit  12 ) of the stator  16  so as to have a certain distance from the stator  16  and being rotated by operating mutually with the stator  16  when power is applied to the stator  16 , and a crankshaft  20  rotating together with the rotator  18  by being fixed to the rotator  18  and rotatively supported by a frame  22  fixed to the casing  10 .  
     [0051] The compressing unit  14  includes a connecting rod  24  connected to the upper end of the crankshaft  20  and performing a linear reciprocating motion in a rotational motion of the crankshaft  20 , a cylinder  26  fixed to the upper side surface of the frame  22  and having a certain space at which a fluid flows into, a piston  28  performing a linear motion together with the connecting rod  24  by being connected to the connecting rod  24  and placed so as to be slide-movable inside the cylinder  26  in order to compress the fluid flowing into the cylinder  26 , and a valve assembly  30  installed to the side surface of the cylinder  26 , supplying the fluid inside the cylinder  26  and discharging the fluid compressed by the piston  28 .  
     [0052] The connecting rod  24  is connected to an eccentric pin  32  formed at the upper end of the crankshaft  20  and performs a linear reciprocating motion in the rotational motion of the crankshaft  20 .  
     [0053] The cylinder  26  has a certain space filled with a fluid, the connecting rod  24  penetrates through the side of the cylinder  26  so as to be sealed, and the valve assembly  30  is installed to the other opened side of the cylinder  26 .  
     [0054]FIG. 2 is a disassembled perspective view illustrating a valve assembly for a hermetic compressor in accordance with the present invention.  
     [0055] The valve assembly  30  includes a cylinder head  34  installed to the opened side of the cylinder  30 , a suction valve  36  installed to the side of the cylinder head  34  and performing an opening/closing operation about a sucked fluid, a discharge valve  38  installed to the other side of the cylinder head  34  and performing an opening/closing operation about a discharged fluid, a head cover  40  fixed to the cylinder head  34  and having a suction space  42  at which a fluid is sucked into and a discharge space  44  at which a fluid is discharged, and a gasket  46  inserted into a connecting portion between the head cover  40  and the cylinder head  34  and performing a sealing operation.  
     [0056] In the cylinder head  34  formed as a flat plate having a certain thickness, a suction hole  48  at which a fluid is sucked into the cylinder  26  is formed at a portion at which the suction valve is fixed, and a discharge hole  50  at which a fluid inside the cylinder  26  is discharged is formed at a portion at which the discharge valve  38  is fixed.  
     [0057] In a design of the cylinder head  34 , a dead volume influencing an efficiency of a compressor has to be considered in the first place.  
     [0058] The term “dead volume” means a volume of the cylinder  26  and a volume of the discharge hole  50  when the piston  28  is at a top dead center, in other words, it means a quantity of the rest of the fluid which has not been discharged when the piston  28  reaches the top dead center.  
     [0059] When the dead volume is increased, a suction operation suctioning new fluid into the cylinder  26  is obstructed, accordingly an efficiency of the whole compressor is lowered. Herein, a volume of the discharge hole  50  is increased according to an increase of a thickness of the cylinder head  34 , accordingly a dead volume is increased.  
     [0060] Accordingly, it is preferable to form the cylinder head  34  thinly to the utmost within a range endurable a pressure of a sucked/discharged fluid.  
     [0061] Because the cylinder head  34  is fabricated with a material having an improved strength and forming a groove is unnecessary, etc., the cylinder head  34  can be formed thinly to the utmost within a range endurable the fluid pressure, therefore it is possible to eliminating a performance lowering factor of the compressor.  
     [0062] The suction valve  36  formed as a strip type having a certain elastic force in a direction contacted to the suction hole  48  is fixed to the side of the cylinder head  34  installed to the cylinder  26 .  
     [0063] In more detail, as depicted in FIG. 3, the suction valve  36  includes a fixation portion  52  fixed to the surface of the cylinder head  34 , an opening/closing portion  54  contacted to the suction hole  48  and opening/closing the suction hole  48 , and a connecting portion  56  connecting the opening/closing portion  54  and the fixation portion  52 .  
     [0064] Herein, the fixation portion  52  formed so as to have a wide area at the connecting portion  56  in order to be stably fixed to the cylinder head  34  is fixed to the surface of the cylinder head  34  by a welding, etc.  
     [0065] Besides a welding any method can be applied to fixing the fixation portion  52  to the cylinder head  34 .  
     [0066] The opening/closing portion  54  is formed as a circular flat plate shape having a diameter larger than a diameter of the suction hole  48 .  
     [0067] And, the connecting portion  56  between the fixation portion  52  and the opening/closing portion  54  is formed as a plate shape having a certain length (L 1 ) and a certain width (W 1 ) so as to provide a certain elastic force in order to make the opening/closing portion  54  contact to the suction hole  48 .  
     [0068] Herein, the elastic force of the connecting portion  56  is varied according to the length (L 1 ) between the fixation portion  52  and the opening/closing portion  54 . In more detail, because a distance between the fixation portion  52  as a supporting portion and the opening/closing portion  54  performing the opening/closing operation is increased as the length (L 1 ) of the connecting portion  56  is lengthened, the elastic force provided to the opening/closing portion  54  is decreased, on the contrary, the elastic force provided to the opening/closing portion  54  is increased as the length (L 1 ) of the connecting portion  56  is shortened.  
     [0069] The connecting portion  56  of the suction valve  36  is formed as a shape having the width (W 1 ) smaller than a width of the opening/closing portion  54  and the length (L 1 ) longer than a length of the opening/closing portion  54  in order to make the opening/closing portion  54  perform the opening/closing operation sensitively when a pressure by the fluid is applied through the suction hole  48 .  
     [0070] The discharge valve  38  is fixed to the surface of the cylinder head  34  at which the head cover  40  is installed and is formed as a strip type having a certain elastic force in a direction contacting to the discharge hole  50 , accordingly the discharge valve  38  is operated in a direction opening the discharge hole  50  and discharges the fluid outside when the fluid flowing into the cylinder  26  is pressurized according to the linear motion of the piston  28 .  
     [0071] In more detail, as depicted in FIG. 3, the discharge valve  38  is constructed with a fixation portion  58  fixed to the surface of the cylinder head  34 , an opening/closing portion  60  contacted to the discharge hole  50  and performing the opening/closing operation and a connecting portion  62  connecting the opening/closing portion  60  and the fixation portion  58 .  
     [0072] Herein, the fixation portion  58  is formed by being extended from the end portion of the connecting portion  62  so as to have a wider contact area in order to be stably fixed to the cylinder head  34 , and is fixed to the surface of the cylinder head  34  by a method such as a welding, etc.  
     [0073] Besides the welding, any method can be applied to fixing the fixation portion  58  to the surface of the cylinder head  34 .  
     [0074] The opening/closing portion  60  is formed as a circular flat plate shape having a diameter larger than a diameter of the discharge hole  50  so as to enclose the discharge hole  50  easily.  
     [0075] And, the connecting portion  62  connecting the fixation portion  58  and the opening/closing portion  60  is formed as a plate type having a certain length in order to have a certain elastic force for making the opening/closing portion  60  contact to the discharge hole  50 .  
     [0076] Because a pressure applied to the discharge hole  50  is larger than a pressure applied to the suction hole  48 , the connecting portion  62  of the discharge valve  38  is formed so as to provide a larger elastic force to the opening/closing portion  60  than the connecting portion  56  of the suction valve  36 .  
     [0077] Because the connecting portion  62  of the discharge valve  38  has a length (L 2 ) shorter than a length of the connecting portion  56  of the suction valve  36  and a width (W 2 ) larger than a width of the connecting portion  56  of the suction valve  36 , the elastic force acting on the opening/closing portion  60  of the discharge valve  38  is larger than the elastic force acting on the opening/closing portion  54  of the suction valve  36 .  
     [0078] As depicted in FIG. 4, the head cover  40  has a suction space  42  connected to the suction hole  48  and filled with a fluid sucked from outside and a discharge space  44  connected to the discharge hole  50  and discharging the compressed fluid outside. And, a fixation surface  64  at which the fixation portion  52  of the discharge valve  38  is tightly contacted and fixed is formed at the front surface of the head cover  40  fastened to the cylinder head  34 .  
     [0079] The suction space  42  and the discharge space  44  are divided by a septum wall  66  inside the head cover  40 .  
     [0080] In addition, the head cover further includes a supporting portion extended from the fixation surface  64  toward the discharge valve  38  and limiting an opening range of the discharge valve  38 .  
     [0081] As depicted in FIG. 4, the supporting portion is constructed with a first supporting portion  68  limiting a bending range of the connecting portion  62  of the discharge valve  38  and a second supporting portion  70  extended from the first supporting portion  68  and limiting an opening range of the opening/closing portion  60  of the discharge valve  38 . And, the supporting portion is formed so as to be inclined at a certain angle (θ) from the first supporting portion  68  to the second supporting portion  70 .  
     [0082] As described above, when the discharge valve  38  is bent by an instant high pressure, the first and the second supporting portions  68 ,  70  can prevent damage of the discharge valve  38  by limiting a deformation range of the discharge valve  38 , make the discharge valve  38  return to a home position instantly and make the discharge valve  38  perform the accurate operation.  
     [0083] And, the first and the second supporting portions  68 ,  70  absorb an impact occurred by the fluid discharged with a high pressure through the discharge hole  50 , transmit the impact to all over the head cover  40 , accordingly a noise generated in the discharge space of the head cover  40  due to the rapid diffusion of the fluid can be lowered.  
     [0084] In addition, in discharging of the fluid, the discharge valve  38  contacts to the first and the second supporting portions  68 ,  70 , a noise due to vibration, etc. of the discharge valve  38  due to the discharge pressure can be lowered.  
     [0085] It is preferable to form the area of the first and the second supporting portions  68 ,  70  so as to coincide with or be larger than the area of the discharge valve  38 .  
     [0086] The gasket  46  is tightly contacted between the cylinder head  34  and the head cover  40  in order to prevent a leakage of the fluid, it has the same shape as the shape of the front surface of the head cover  40 .  
     [0087] In the valve assembly  30 , reinforcing members  72 ,  74  for respectively reinforcing a strength of the cylinder head  34  between the cylinder head  34  and the head cover  40  or the cylinder head  34  and the cylinder  26  and housing the suction valve  36  and the discharge valve  38  can be additionally formed.  
     [0088] As depicted in FIGS. 5 and 6, the reinforcing members  72 ,  74  are formed as a relatively thin plate shape so as not to increase a total size of the valve assembly, the first reinforcing member  72  is placed between the cylinder head  34  and the cylinder  26 , and the second reinforcing member  74  is placed between the cylinder head  34  and the head cover  40 .  
     [0089] As depicted in FIG. 5, a suction valve installing portion  76  having the same shape as the suction valve  36  penetrates through the first reinforcing member  72  in order to place the suction valve  36 , and a connecting hole  78  connected to the discharge hole  50  of the cylinder head  34  is formed at the side of the first reinforcing member  72 .  
     [0090] As depicted in FIG. 6, a discharge valve installing portion  80  having the same shape as the discharge valve  38  or larger than the discharge valve  38  is formed in order to place the discharge valve  38 , and a connecting hole  82  connected to the suction hole  48  of the cylinder head  34  is formed at the side of the second reinforcing member  74 .  
     [0091] The assembly process and the operation of the valve assembly of the hermetic compressor in accordance with the present invention will be described.  
     [0092] First, in the assembly process of the valve assembly, the suction valve  36  and the discharge valve  38  are respectively installed to the both sides of the cylinder head  34 . In more detail, the fixation portions  52 ,  58  of the suction valve  36  and the discharge valve  38  are respectively fixed to the both sides of the cylinder head  34  by a method such as a welding, etc. Afterward, the cylinder head  34  at which the suction valve  36  and the discharge valve  38  are fixed is placed at the opened side of the cylinder  26 , and the gasket  46  and the head cover  40  are combined with the other side of the cylinder head  34  by fastening bolts (not shown).  
     [0093] And, when the first and the second reinforcing members  72 ,  74  are additionally installed, the first and the second reinforcing members  72 ,  74  are respectively installed to the both sides of the cylinder head  34 .  
     [0094] After completing the assembly, when power is applied to the driving unit  12 , the crankshaft  20  is rotated, and the connecting rod  24  performs the linear reciprocating motion. Then, the piston  28  connected to the connecting rod  24  performs the compressing operation of the fluid while performing the linear reciprocating motion inside the cylinder  26 .  
     [0095] In more detail, when the piston  28  moves linearly in the left direction in FIG. 1, the discharge hole  50  formed at the cylinder head  34  is closed by the elastic force of the discharge valve  38 , the suction valve  36  is opened, the suction hole  48  is opened, accordingly the fluid is sucked into the cylinder  26 . Herein, the fluid flows into the cylinder  26  through the suction space  42  of the head cover  40  and the suction hole  48 .  
     [0096] In that state, when the crankshaft  20  is rotated more, the piston  28  moves linearly in the right direction in FIG. 1, the fluid sucked into the cylinder  26  is pressurized by the push force of the piston  28  and is discharged outside through the discharge hole  50 . Herein, when the piston  28  is moved in the right direction, the suction valve  36  is operated in a direction closing the suction hole  48 , the discharge valve  38  is operated in a direction opening the discharge hole  50 , accordingly the pressed fluid is discharged through the discharge hole  50 .  
     [0097] Herein, when the discharge valve  38  is opened, because it contacts to the supporting portions  68 ,  70  formed at the head cover  40 , the opening range is limited, and a noise due to vibration of the discharge valve  38  caused by the discharge pressure can be lowered.  
     Industrial Applicability  
     [0098] In a valve assembly for a hermetic compressor in accordance with the present invention, because a suction valve and a discharge valve are respectively and directly fixed to the both sides of a cylinder head, an additional part for fixing the suction valve and the discharge valve is unnecessary, it is possible to simplify a structure and reduce the number of components, accordingly a production cost can be reduced.  
     [0099] In addition, forming a groove, etc. at a cylinder head in order to house a suction valve and a discharge valve is unnecessary, it is possible to simplify an assembly process, accordingly a productivity can be improved.  
     [0100] In addition, because a supporting portion for supporting a discharge valve in opening operation of the discharge valve is formed at a head cover, it is possible to prevent vibration of the discharge valve due to a discharge pressure of a fluid in the opening operation, accordingly the vibration due to the discharge pressure of the fluid can be minimized.