Patent Publication Number: US-6666663-B2

Title: Gas suction apparatus for a reciprocating compressor with a piston inertia valve

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a compressing apparatus of refrigerant gas for a reciprocating compressor and particularly, to a gas suction apparatus for a reciprocating compressor capable of improving compressing performance of refrigerant gas and reliability of components. 
     2. Description of the Background Art 
     Generally, a compressor is an instrument for compressing fluid such as air and refrigerant gas. The compressor generally includes a driving unit installed in a closed container, for generating a driving force and a compressing unit for sucking and compressing refrigerant gas by receiving the driving force of the above driving unit and is classified into a rotary compressor, reciprocating compressor and a scroll compressor according to the structure of the compressing unit. 
     The reciprocating compressor among them is a compressor in which a driving force of the driving unit is transmitted to the piston and the piston sucks and compresses refrigerant gas performing linear reciprocating movement in a cylinder. 
     FIGS. 1 and 2 show an embodiment of the compressing unit of the reciprocating compressor and the compressing unit of the reciprocating compressor includes a cylinder  10  where a through hole  11  forming a compression space P inside the hole is formed, a piston inserted in the through hole  11  of the cylinder  10  enabling linear reciprocating movement and a discharge valve assembly  30  combined to the end portion of the cylinder  10  to cover the through hole  11 . 
     The piston  20  has a head portion  22  at one side of the body portion  21  having a certain length and a connection portion  23  extended into a certain area at the other side of the body portion  21 . In the body portion  21 , a first gas passage  24  having a certain depth is formed in the body portion  21  and in the head portion, a second gas passage  25  is formed. 
     The first gas passage  24  is composed of a hole and the second gas passage  25  is composed of a plurality of through holes. 
     A suction valve  40  for opening and closing the second gas passage  25  is positioned in the head portion  22  and the connection portion  23  of the piston  20  is connected into the driving unit for generating a driving force. 
     On the other hand, the suction valve  40  is composed of a thin plate in a round form and has a dissection portion  41  is positioned inside the valve. The suction valve is divided into a fixing portion  42  and opening and closing portion  43  by the dissection portion  41 . 
     The suction valve  40  is fixed-combined to the head portion  22  having a fixing bolt  50  penetrated by the fixing portion  42  under the condition that the valve is contacted on the end surface of the head portion  23  of the piston  20 . 
     Also, the discharge valve assembly  30  includes a discharge cover  31  combined to cover the end portion of the cylinder  10 , a discharge valve  30  inserted in the discharge cover  31 , for opening and closing the compression space P formed by the through hole  11  and piston  20  of the cylinder  10  and a valve spring  33  for elastically supporting the discharge valve  32 . 
     In the operation of the compressing unit of the above reciprocating compressor, first, a driving force of the driving unit is transmitted to the piston  20  and the piston  20  performs linear reciprocating movement in the cylinder  10 . 
     In the process, as shown in FIG. 3, when the piston  20  moves to the direction of a bottom dead point a, the discharge valve  32  is contacted on the end portion of the cylinder  10  by pressure difference and blocks the compression space P. At the same time, the suction valve  40  combined to the piston  20  is bent and open the second gas passage  25 , thus to suck refrigerant gas to the compression space P formed in the cylinder  10  through the first gas passage  24  and the second gas passage  25  of the piston  20 . 
     When the piston  20  moves to an upper dead center (b) after reaching the bottom dead center (a), the suction valve  40  is restored to the former condition and the second gas passage  25  of the piston  20  is closed, thus to compress refrigerant gas sucked to the compression space P formed in the cylinder  10 . When the piston  20  reaches the top dead center (b), the discharge valve  32  is opened and the compressed refrigerant gas is discharged. 
     As the above process is repeated continuously, refrigerant gas is compressed. 
     However, in the above structure, since the suction valve  40  formed as a thin plate is fixed-combined by the fixing bolt  50 , the head portion of the fixing bolt  50  is positioned in the compression space P in the protruded form and accordingly, a dead volume is generated, thus to decline compressing efficiency. Also, position sensing of the top dead center (b) and bottom dead center (a) of the piston  20  is difficult and accordingly, controlling of a stroke of reciprocating movement of the piston  20  becomes difficult. 
     Since the suction valve  40  formed as a thin plate is combined by the fixing bolt  50 , design of the second gas passage  25  is limited. Namely, in case the flowing cross section of the second gas passage  25  is large, the flowing cross section where the refrigerant gas flows becomes large. However, the suction valve  40  formed as a thin plate could be damaged by an excessive suction pressure in bending the valve and in case the size of the flowing cross section of the second gas passage  25  is small, the flowing resistance of refrigerant gas could be increased by the small cross section. 
     As the piston  20  moves, in the process that the suction valve  40  is repeated opened or closed, a slip rotation is generated between the suction valve  40  and the fixing bolt  50  and accordingly, compressing performance could not be performed well since the piston  20  is seceded from the second gas passage  25 . 
     Also, as the suction valve  40  was bent and restored to its former state, the second gas passage  25  is opened or closed and accordingly, a fatigue crack is generated and a screw hole  44  for combining the fixing bolt  50  is formed at the bending portion of the suction valve  40 . Therefore, structural strength was declined. 
     As a structure for making up for the above disadvantage, as shown in FIG. 4, an embodiment that the fixing portion  42  of the suction valve  40  is directly welded-connected to the end surface of the head portion  22  of the piston  20  is disclosed. 
     With such structure, the dead volume can be reduced and control of a stroke is eased but, characteristic of the material is changed by heat transformation by welding heat for welding the suction valve  40  on the head portion  22  of the piston  20 . When the opening and closing operation of the suction valve  40  is continuously performed, cracks by fatigue are generated centering around the welding point, thus to decrease reliability of the compressor. 
     SUMMARY OF THE INVENTION 
     Therefore, the present invention provides a gas suction apparatus for a reciprocating compressor which can make the suction of refrigerant gas smoothly and increase structural combining strength. 
     Also, another object is to provide a gas suction apparatus for a reciprocating compressor which can minimize dead volume of a compression space of refrigerant gas and ease controlling of a stroke. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a gas suction apparatus for a reciprocating compressor comprising a piston having a gas flowing passage where refrigerant gas flows, being inserted in the compression space formed in a cylinder enabling linear reciprocating movement, a fixing means combined to the piston, an inertia valve including a valve cone portion formed to have a larger area than the cross section of the gas flowing passage and a certain thickness, for opening and closing the gas flowing passage, being contacted on the end surface of the piston or separated, a valve body portion extended having a smaller outer diameter than the inner diameter of the gas flowing passage at the center of the one side surface of the valve cone portion and inserted in the gas flowing passage, a plurality of guide members extended to have a certain length on the outer circumferential surface of the valve body portion and contacted on the inner circumferential surface of the gas flowing passage and an inertia valve penetrated-formed to have a certain width and length in the valve body portion having the fixing means inserted in the valve. 
     The foregoing and other, features, aspects and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
     In the drawings: 
     FIG. 1 is a cross-sectional view showing a compressing unit of a conventional reciprocating compressor; 
     FIG. 2 is a partial perspective view showing an embodiment of a valve combining structure of the conventional reciprocating compressor; 
     FIG. 3 is a cross-sectional view showing an operational condition of the compressing unit of the conventional reciprocating compressor; 
     FIG. 4 is a cross-sectional view showing another embodiment of the valve combining structure of the conventional reciprocating compressor; 
     FIG. 5 is a cross-sectional view showing a compressing unit of a reciprocating compressor having a gas suction apparatus for a reciprocating compressor in accordance with the present invention; 
     FIG. 6 is a perspective view showing an inertia valve composing the gas suction apparatus for the reciprocating compressor in accordance with the present invention; 
     FIG. 7 is a cross-sectional view showing an embodiment of another valve cone portion of the inertia valve composing the gas suction apparatus for the reciprocating compressor in accordance with the present invention; 
     FIG. 8 is a cross-sectional view showing another embodiment of a fixing means composing the gas suction apparatus for the reciprocating compressor in accordance with the present invention; 
     FIG. 9 is a cross-sectional view showing another modified example of a guide feet composing the gas suction apparatus for the reciprocating compressor in accordance with the present invention; 
     FIG. 10 is a cross-sectional view showing an operational condition of the compressing unit in a suction operation of the compressor having the gas suction apparatus for a reciprocating compressor in accordance with the present invention; and 
     FIG. 11 is a cross-sectional view showing an operational condition of the compressing unit in a compressing operation of the compressor having the gas suction apparatus for a reciprocating compressor in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     Reference numeral which are same as the conventional art designates the same reference numeral and the description will be omitted. 
     FIG. 5 is a cross-sectional view showing a compressing unit of a reciprocating compressor having a gas suction apparatus for a reciprocating compressor in accordance with the present invention. As shown in FIG. 5, The compressing unit of the reciprocating compressor includes a cylinder  10  where a through hole  11  forming a compression space P inside the hole is formed, a piston having a gas flowing passage where refrigerant gas flows, being inserted in the compression space formed in a cylinder enabling linear reciprocating movement, a discharge valve assembly  30  combined to the end portion of the cylinder  10  to cover the through hole  11 , a fixing means  70  combined to the piston  60  and an inertia valve  80  inserted in the gas flowing passage F movably to have a restricted moving distance by the fixing means  70 , for opening and closing the gas flowing passage F moving according to pressure difference and inertia generated by linear reciprocating movement of the piston  60 . 
     Here, the piston  60  has a certain length, a gas flowing passage F penetrated having a certain inner diameter is formed at the center of the body portion  61  formed in an annual bar form and a connection portion  62  extended along the circumferential direction having a certain area is formed at one side of the body portion  61 . 
     The end surface of the piston body portion  61  positioned at the opposite side of the connection portion  62  is formed as a flat surface forming a sealing surface  63  and the connection portion  62  is connected to the driving unit for generating a driving force. 
     The fixing means  70  includes a pin combining hole  64  penetrated-formed at one side of the piston  60  to cross the gas flowing passage F of the piston  60  and a fixing pin  71  inserted-fixed to the pin combining hole  64 , for restricting the moving distance of the inertia valve  80 . 
     The fixing pin  71  includes a pin portion  71   a  having a certain outer diameter and length and a head portion  71   b  formed to have a certain length and an outer diameter larger than that of the pin portion  71   a  at one side of the pin portion  71   a . 
     It is desirable that the pin combining hole  64  formed in the body portion  61  of the piston  60  is formed to have a different inner diameter so that the fixing pin  71  can be inserted and a stepped portion  65  is formed on the outer circumferential surface of the piston body portion  61  where the pin combining hole  64  is formed not to be contacted on the inner circumferential surface of the cylinder  10  when it is operated. 
     Also, as shown in FIG. 6, the inertial vale  80  includes a valve cone portion  81  having a larger area than the cross section of the gas flowing passage F and a certain thickness, for opening and closing the gas flowing passage F, being contacted on the end surface of the piston  60  or separated, a valve body portion  82  extended having a smaller outer diameter than the inner diameter of the gas flowing passage F at the center of the one side surface of the valve cone portion  81  and inserted in the gas flowing passage F, a plurality of guide feet  83  and  84  extended to have a certain length on the outer circumferential surface of the valve body portion  82  and contacted on the inner circumferential surface of the gas flowing passage F and a guide hole  85  penetrated-formed having a certain width and length, in which the fixing means  70  are inserted. 
     The guide feet  83  and  84  include a plurality of front guide feet  83  formed on an outer circumferential surface at a side of the valve body portion  82  at a certain interval to be positioned at the side of the valve cone portion  81  and a plurality of rear guide feet  84  formed at the other side of the guide hole  85  having a certain distance from the front guide feet  83 . 
     It is desirable that the front guide feet  83  are formed contacted on the portion ranged from the outer circumferential surface of the valve body portion  82  to the inner side surface of the valve cone portion  81  to increase the structural strength. 
     The front guide feet  83  are radially formed at a certain interval in the circumferential direction of the valve body portion  82  and the rear guide feet  84  are radially formed at a certain interval in the circumferential direction of the valve body portion  82 . 
     It is desirable that the numbers of the front guide feet  83  and the rear guide feet  84  are formed same and the direction is formed to be positioned on a same line in the shaft direction of the valve body portion  82 . 
     Also, the end surface of the guide feet  83  and  84  contacted with the inner circumferential surface of the piston  60  is formed in a square surface. 
     The guide member can further include a plurality of middle guide feet  830 ,  850  radially formed on the circumferential surface of the piston  60  between the front guide feet  83  and the rear guide feet  84  along the same circumferential direction. 
     The middle guide feet  830 ,  850  can be respectively positioned on the same line along the shaft direction of the valve body portion  82  where the front guide feet  83  and the rear guide feet  84  are formed, as shown in FIG. 8, or the middle guide feet  830 ,  850  can be formed on a dislocated line from the shaft direction for better guidance, as shown in FIG.  9 . 
     On the other hand, in the inertia valve  80 , the inner surface of the valve cone portion  81  is contacted-combined on the sealing surface  63  of the piston  60  as the lengthy portion  82  and guide feet  83  and  84  are inserted to the gas flowing passage F of the piston  60 . 
     At this time, the guide feet  83  and  84  are contacted-supported on the inner circumferential surface of the gas flowing passage F. 
     Under the condition that the guide hole  85  of the inertia valve  80  and the pin combining hole  64  formed at the piston  60  are unified, the fixing pin  71  Composing the fixing means  70  is penetrated inserted and fixed-combined to the pin combining hole  64  of the piston  60  and the guide hole  85  of the inertia valve  80 . 
     Since a fixing pin  71  is inserted in the guide hole  85  in the inertia valve  80 , moving distance is limited by the fixing pin  71 . 
     On the other hand, as shown in FIG. 7, in the other embodiment of the sealing structure between the valve cone portion  81  of the inertia valve  80  and the end surface of the piston body portion  61 , a chamfered inclination contact surface  66  is formed on the border of the gas flowing passage F positioned on the end surface of the piston  60  and an inclination contact surface  86  which is formed to be contacted on the above inclination contact surface  66  is formed on the inner border of the valve cone portion  81  of the inertia valve  80 . 
     Also, as shown in FIG. 8, the other embodiment of the fixing means  70  includes a bolt combining hole  67  penetrated-formed at one side of the piston  60  to cross the gas flowing passage F of the piston  60  and a fixing bolt  72  combined to the bolt combining hole  67 , for restricting the moving distance of the inertia valve  80 . 
     On the other hand, as shown in FIG. 9, the guide feet  83  and  84  are formed in the same position and shape as above but the feet can be formed as transformed guide feet  85  and  86  having the end surface meeting with the inner circumferential surface of the piston  60  forming a curved surface r, thus to move more smoothly. 
     Also, the guide feet are formed at both sides of the valve body portion  82  but the guide feet can be formed having more guide feet at the center portion of the lengthy portion  82  to perform more smooth and reliable movement. 
     The discharge valve assembly  30  includes a discharge cover  31  combined to cover the through hole  11  of the cylinder  10 , a discharge valve  32  inserted in the discharge cover  31  and formed by the through hole  11  and the piston  60  of the cylinder  10 , for opening and closing the compression space P and a valve spring  33  for supporting the discharge valve  32  elastically. 
     Hereinafter, the operation and effect of the gas suction apparatus for the reciprocating compressor in accordance with the present invention will be described. 
     Firstly, the operation of the compressing unit of the reciprocating compressor is performed as follows. When driving force of the driving unit is transmitted to the piston  60  and the piston  60  performs linear reciprocating movement inside the cylinder  10 , namely, between the top dead center (b) and the bottom dead center (a) of the compression space P, the inertia valve  80  performs linear reciprocating movement by pressure difference of the compression space P of the cylinder  10  and inertial of the inertia valve  80  and opens and closes the gas flowing passage F of the piston  60 . Accordingly, refrigerant gas is sucked to the compression space P of the cylinder  10  through the gas flowing passage F of the piston  60  and the gas is compressed and discharged by the opening and closing performance of the discharge valve  32  which composes a discharge valve assembly  30 . 
     In the process, first, when the piston  60  moves to the bottom dead center (a), as shown in FIG. 10, under the condition that the inner surface of the valve cone portion  81  of the inertia valve  80  and the sealing surface  63  of the piston  60  is opened by pressure difference of the inner and outer portion of the compression space P and stop inertia of the inertia valve  80 , the inertia valve  80  is caught by the fixing pin  71  which is the fixing means  70  and moves to the bottom dead center (a) together with the piston  60  and at the same time, the refrigerant gas flows through the gas flowing passage F of the piston  60 . Then the refrigerant gas passes through the space between the outer circumferential surface of the valve body portion  82  of the inertia valve  80  and the inner wall of the gas flowing passage F and is sucked to the compression space of the cylinder  20  through the portion between the inner surface of the valve cone portion  81  of the inertia valve  80  and the sealing surface  63  of the piston  60 . 
     As shown in FIG. 11, when the piston  60  moves from the bottom dead center (a) to the top dead center (b), by inertia of the inertia valve  80 , pressure difference and movement of the piston  60 , the fixing pin  71  which is a fixing means  70  moves along the guide hole  85  of the inertia valve  80  and supports the inner wall of the guide hole  85 . The inner surface of the valve cone portion  81  of the inertia valve  80  is contacted on the sealing surface  63  of the piston  60  and the gas flowing passage F of the piston  60  is blocked. Accordingly, refrigerant gas sucked to the compression space P of the cylinder  10  is compressed as the piston moves to the top dead center (b). 
     Then, when the piston  60  reaches the top dead center (b), the discharge valve  32  is opened and the refrigerant gas sucked to the compression space P of the cylinder  10  is discharged. 
     As the above process is repeated, the refrigerant gas is sucked, compressed and discharged. 
     On the other hand, as the piston  60  performs linear reciprocating movement, in the process that the inertia valve  80  performs linear reciprocating movement in the gas flowing passage F of the piston  60 , since the guide feet  83 ,  84 ,  85  and  86  of the inertia valve  80  are contacted-supported on the inner circumferential surface of the gas flowing passage F, the inertia valve  80  can move uniformly without slanting to a side and rotary movement of the inertia valve  80  is restricted by the fixing means  70 . 
     Also, since the surface of the valve cone portion  81  of the inertia valve  80  positioned at the compression space P of the cylinder  10  is formed in a flat form in the apparatus in accordance with the present invention, dead volume of the compression P is minimized and position sensing of the stroke of the piston  60  becomes easier, thus to ease stroke controlling of the piston  60 . Namely, in the present invention, since the dead volume generated by the head portion of the fixing bolt  50  is excluded in combining the fixing bolt  50  as conventionally, the compression space P is relatively larger and position sensing of the stroke of the piston  60  is easy. 
     Also, with the present invention, since the inertia valve  80  has a certain volume and weight, the structural strength is increased and the design of the cross section of the gas passage  25  where refrigerant gas flows is not limited. Namely, conventionally, the cross section of the gas passage  25  where refrigerant gas flows is designed according to strength of the suction valve  40  using the suction valve  40  formed as a thin plate and accordingly, design for increasing the cross section of the inertia valve  80  is limited. However, in accordance with the present invention, by applying the gas passage  25  limit in designing the gas passage according to strength of the suction valve  40  is removed. 
     Also, in accordance with present invention, since an opening amount of the inertia valve  80  is limited by the fixing means  70 , reliability of response of the inertia valve  80  becomes excellent and the refrigerant gas can be sucked and flown smoothly. 
     As described above, the gas suction apparatus for the reciprocating compressor can minimize the dead volume of the compression space and control the stroke easily. Refrigerant gas is smoothly sucked and flown by excellent reliability of response of the valve and compressing performance can be improved. Also, damage of the components is restricted by increasing the structural strength, thus to improve reliability of the compressor. 
     As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.