Patent Publication Number: US-2004047750-A1

Title: Reciprocating compressor

Description:
RELATED APPLICATIONS  
       [0001] The present disclosure is related to subject matter contained in Korean Patent Application No. 2002-0054054, filed on Sep. 7, 2002, which is expressly incorporating herein, by reference, in its entirety.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates to a reciprocating compressor, and particularly, to a reciprocating compressor which is configured to smoothly operate a suction valve by reducing a contact area between a piston and the suction valve.  
       [0004] 2. Description of the Background Art  
       [0005] Generally, a compressor is an apparatus for compressing refrigerant gas under the condition of low temperature and pressure, which is introduced from an evaporator and discharging the gas by changing the condition to high temperature and pressure.  
       [0006] The compressor can be classified as a rotary compressor, reciprocating compressor and a scroll compressor according to the method of compressing fluid.  
       [0007] Particularly, the reciprocating compressor sucks and compresses fluid while a piston moves linearly. A method of compressing in such a reciprocating compressor is divided into a method which compresses fluid by converting the rotary movement of a driving motor into a reciprocating movement of the piston, and a method which compresses and sucks fluid by having the piston perform a reciprocating movement as the driving motor performs a linear reciprocating movement.  
       [0008]FIG. 1 is a longitudinal sectional view showing a conventional reciprocating compressor, FIG. 2 is a partially cross-sectional view showing an engagement of a piston and a suction valve in FIG. 1 and FIG. 3 is a partially longitudinal cross-sectional view showing a compression operation in FIG. 1.  
       [0009] As shown in the drawing, the conventional reciprocating compressor includes a case  10  having a gas suction pipe SP and gas discharging pipe DP, and a frame unit  20  which is elastically installed inside the case  10 . A reciprocating motor  30  is fixed to the frame  20  and has having a movable element which reciprocates linearly, a compression unit  40  is engaged to the movable element  33  of the reciprocating motor  30  and is supported by the frame unit  20 . A resonance spring unit  50  for inducing resonating movement by elastically supporting the movable element of the reciprocating motor  30  in the movement direction is provided.  
       [0010] The compression unit  40  includes a cylinder  41  which is integrally formed in a front frame  21  of the frame unit  20 , a piston  42  which is attached to the movable element of the reciprocating motor  30  for performing a reciprocating movement in a compression space P of the cylinder  41 , a suction valve  43  which is mounted at the front end of the piston  42  for controlling suction of gas by opening and closing the suction path F of the piston  42 , and a discharging valve assembly  70  which is mounted at the discharge side of the cylinder  41  for controlling discharge of gas by opening and closing the compression space P.  
       [0011] The discharging valve assembly  70  includes a discharge cover  71  for covering a side of the cylinder  41 , and a discharge valve  72  which is located at the inner portion of the discharging cover  71  for elastically opening and closing the compression space P.  
       [0012] The suction valve  43  (FIG. 2) is formed as a circular thin plate and provided with a cutting groove  43   a  at the center thereof. The suction valve  43  is divided into a fixed portion  43   b  and an open/close portion  43   c  by the cutting groove  43   a.    
       [0013] The suction valve  43  is fixed to an end portion surface  46  of the piston by a bolt B to be in contact therewith.  
       [0014] The operation process of the conventional reciprocating compressor with the above construction will be described as follows.  
       [0015] The piston  42  reciprocates in the cylinder  41  by a driving force of the reciprocating motor  30  and changes a volume of the compression space P, thereby sucking and compressing gas into the compression space P.  
       [0016] When the pressure of the gas is higher than a predetermined pressure, the discharge cover  72  of the discharging valve assembly  70  is opened and discharges the compressed gas, which process is sequentially repeated.  
       [0017] That is, when the piston  42  moves to a lower dead point (a), the discharge valve  72  of the discharging valve assembly  70  blocks the compression space P of the cylinder  41  and the open/close portion  43   c  of the suction valve  43  engaged to the piston  42  is bent, thereby opening the suction path F. At this time, gas is sucked into the compression space P of the cylinder  41  through the suction path F of the piston  42 .  
       [0018] Then, as the piston  42  moves to an upper dead point (b), the suction valve  43  returns to an initial state and the suction path F of the piston  42  is closed, thereby compressing the gas sucked in the compression space P. When the pressure of the gas is higher than a predetermined pressure, the discharge cover  72  of the discharging valve assembly  70  is opened and the compressed gas is discharged.  
       [0019] Generally, to perform a smooth reciprocation of the piston, oil is provided between the suction valve  43  and an end portion surface  46  of the piston. However, in the conventional compressor, the suction valve  43  is temporarily adhered to the end portion surface  46  of the piston by viscosity of the oil.  
       [0020] As aforementioned, when the suction valve  43  is adhered to the end portion surface  46  of the piston, the suction path F is opened more later and more much, thereby degrading efficiency of the compressor.  
       SUMMARY OF THE INVENTION  
       [0021] Therefore, an object of the present invention is to provide a reciprocating compressor which is configured to smoothly operate a suction valve by weakening adhesive force of oil by reducing a contact area between an end portion surface of a piston and a suction valve, and to reduce noise by a damping operation.  
       [0022] To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and as broadly described herein, there is provided a reciprocating compressor comprising: a piston which reciprocates in a compression space of a cylinder by being engaged with a reciprocating motor and has a suction path connected to the compression space therein; a suction valve mounted at an end surface of the piston to control gas suction by opening and closing the suction path of the piston; a discharging valve assembly mounted at a discharge side of the cylinder to control gas discharge by opening and closing the compression space; and an adhesion preventing unit formed at a contact portion between the end portion surface of the piston and the suction valve to minimize adhesion due to oil by reducing a contact area between the piston and the suction valve.  
       [0023] The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0024] 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.  
     [0025] In the drawings:  
     [0026]FIG. 1 is a longitudinal sectional view showing the conventional reciprocating compressor;  
     [0027]FIG. 2 is a disassembled perspective view showing an engagement of a piston and a suction valve of the compressor of FIG. 1;  
     [0028]FIG. 3 is a longitudinal sectional view showing a suction operation of the compressor of FIG. 1;  
     [0029]FIG. 4 is a longitudinal sectional view showing a compression operation of the compressor of FIG. 1;  
     [0030]FIG. 5 is a longitudinal sectional view showing a reciprocating compressor according to one preferred embodiment of the present invention;  
     [0031]FIG. 6 is a disassembled perspective view showing an engagement of a piston and a suction valve of the compressor of FIG. 5;  
     [0032]FIG. 7 is a longitudinal sectional view showing a suction operation of the suction valve of the compressor of FIG. 5;  
     [0033]FIG. 8 is a longitudinal sectional view showing a compression operation of the suction valve of the compressor of FIG. 5;  
     [0034]FIG. 9 is a frontal view showing an end portion surface of the piston of the compressor of FIG. 5;  
     [0035]FIG. 10 is a disassembled perspective view showing an engagement between the piston and the suction valve according to another preferred embodiment of the present invention.  
     [0036]FIG. 11 is a longitudinal sectional view showing an engagement between the piston and the suction valve of the compressor of the embodiment of an engagement between the piston and the suction valve of FIG. 10; and  
     [0037]FIG. 12 is a longitudinal sectional view showing a reciprocating compressor according to still another preferred embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0038] Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.  
     [0039]FIG. 5 is a longitudinal sectional view showing a reciprocating compressor according to one preferred embodiment of the present invention, FIG. 6 is a disassembled perspective view showing an engagement of a piston and a suction valve of FIG. 5, FIG. 7 is a longitudinal sectional view showing a suction operation of the piston of FIG. 5, FIG. 8 is a longitudinal sectional view showing a compression operation of FIG. 5, and FIG. 9 is a frontal view showing a piston end surface portion of FIG. 5.  
     [0040] As shown, the reciprocating compressor according to the present invention includes a case  10  having a gas suction pipe SP and a gas discharging pipe DP, a frame unit  20  which is elastically installed inside the case  10 . A reciprocating motor  30  is fixed to the frame  20 , and has having a movable element (not shown) which linearly reciprocates, a compression unit  140  engaged to the movable element of the reciprocating motor  30  and is supported by the frame unit  20 , and a resonance spring unit  50  for inducing resonating movement by elastically supporting the movable element of the reciprocating compressor  30  in the movement direction are provided.  
     [0041] The compression unit  140  includes a cylinder  141  which is integrally formed with the frame unit  20 , and a piston  142  which is secured for movement with the movable element of the reciprocating motor  30  for performing a reciprocating movement in a compression space P of the cylinder  141 . A suction valve  143  is mounted at the front end of the piston  142  for controlling the suction of gas by opening and closing the suction path F of the piston  142 , and a discharging valve assembly  170  is mounted at the discharge side of the cylinder  141  for controlling discharge of gas by opening and closing the compression space P.  
     [0042] The piston  142  includes a head portion  145  (FIG. 6) having a predetermined length and which is inserted to an inner portion of the cylinder  141 , an end portion surface  146  of the piston formed at an end portion of one side of the head portion  145  and defining a predetermined space P, and a connecting portion  147  formed with a predetermined area extending perpendicularly to the longitudinal direction and configured to be connected to the movable element of the motor at the side opposite the head portion  145 .  
     [0043] The suction path F along which gas flows is formed within the head portion  145  and extends to the end portion surface  146  of the piston.  
     [0044] The discharging valve assembly  170  includes a discharge cover  171  for covering a compression space P of the cylinder  141 , and a discharge valve  172  which is located within the discharging cover  171  for elastically opening and closing the compression space P.  
     [0045] The suction valve  143  is formed as a circular thin plate and provided with a cutting groove  143   a  at the center thereof. The suction valve  143  is divided into a fixed portion  143   b  and an open/close portion  143   c  by the cutting groove  143   a . The suction valve  143  is fixed to an end portion surface  146  of the piston by a bolt B.  
     [0046] That is, in performing suction, the suction valve  143  opens the flow path F by a pressure difference, and in performing operating compression, the suction valve  143  closes the flow path F by the pressure difference.  
     [0047] In the present invention, an adhesion preventing unit is formed at a contact portion of the end portion surface  146  of the piston and the suction valve  143  in order to minimize the viscous effect of the oil by reducing the contact area of the surface  146  with the suction valve  143 .  
     [0048] The adhesion preventing unit can be formed one side of either the end portion surface  146  of the piston the suction valve  143 . The adhesion preventing unit can also be formed at both sides thereof.  
     [0049] As shown in FIGS.  5  to  9 , in the reciprocating compressor according to one preferred embodiment of the present invention, an adhesion preventing groove  146   a  comprises a dent or depressed area with a predetermined depth at the end portion surface  146  of the piston which serves as the adhesion preventing unit.  
     [0050] A depth of the adhesion preventing groove  146   a  is determined so as not to influence the viscosity of the oil, which is preferably formed to be about 20-200 μm.  
     [0051] Also, an oil back flow preventing protrusion  146   b  (FIGS. 8 and 9) is formed at the end portion of the suction path F located at the end portion surface  146  of the piston so as to prevent back flow of the oil, which has flowed into the adhesion preventing groove  146   a  to the suction path F.  
     [0052] The oil back flow preventing protrusion  146   b  is formed on the same vertical surface as the end portion surface  146  of the piston so as to selectively open and close the suction path F by the suction valve  143 .  
     [0053]FIG. 10 is a disassembled perspective view showing an engagement between the piston and the suction valve according to another preferred embodiment of the present invention.  
     [0054]FIG. 11 is a longitudinal sectional view showing a reciprocating compressor of FIG. 10. As shown, the adhesion preventing groove  156   a  comprises a dent or depression with a predetermined depth that is formed at the end portion surface  146  of the piston to prevent adhesion according to another preferred embodiment of the present invention. The adhesion preventing groove  156   a  is partially formed at the upper side of the end portion surface of the piston  146 .  
     [0055] The reason for the formation of the groove  156   a  is in order to provide timely opening of the suction path F by the suction valve  143  at the time of a suction operation and to tightly close the suction path F without gas leakage by the suction valve  143  at the time of a compression operation.  
     [0056] A depth of the adhesion preventing groove  156   a  is determined within a range which does not influence the viscosity of the oil. The depth is preferably formed to be about 20-200 μm.  
     [0057] Also, an oil back flow preventing protrusion  156   b  is formed at the end portion of the suction path F located at the end portion surface  146  of the piston so as not to prevent back flow of the oil which has flowed into the adhesion preventing groove  156   a  to the suction path F.  
     [0058] The oil back flow preventing protrusion  156   b  is formed on the same vertical surface as the end portion surface  146  of the piston so as to selectively open and close the suction path F by the suction valve  143 .  
     [0059]FIG. 12 is a longitudinal sectional view showing a reciprocating compressor according to still another preferred embodiment of the present invention.  
     [0060] As shown, the adhesion preventing groove  166   a  is formed in the suction valve  143  in another preferred embodiment of the present invention.  
     [0061] A depth of the adhesion preventing groove  166   a  is preferably formed to be about 20-200 μm.  
     [0062] Hereinafter, operations of the reciprocating compressor according to one preferred embodiment will be explained.  
     [0063] The piston  142  reciprocates in the cylinder  141  by a driving force of the reciprocating motor  30  and changes a volume of the compression space P, thereby sucking and compressing gas into the compression space P.  
     [0064] When the pressure of the gas is higher than a predetermined pressure, the discharging valve assembly  170  is opened and discharges the compressed gas and this operation is sequentially repeated.  
     [0065] That is, when the piston  142  moves to a lower dead point (a) as shown in FIG. 7, the discharging valve assembly  170  closes the compression space P of the cylinder  141  and the open/close portion  143   c  of the suction valve  143  engaged to the piston  142  is bent, thereby opening the suction path F. At this time, gas is sucked into the compression space P of the cylinder  141  through the suction path F of the piston  142 .  
     [0066] In the present invention, the adhesion preventing groove  146   a  is formed at the end portion surface  146  of the piston  142 , so that the suction valve  143  has less contact area with the end portion surface  146  of the piston.  
     [0067] That is, since the viscous force of the oil is proportional to the contact area, the suction valve  143  is not influenced by the viscous force of the oil but can open the suction path F in a timely manner.  
     [0068] Then, when the piston  142  moves to an upper dead point (b) as shown in FIG. 8, the suction valve  143  returns to an initial state and the suction path F of the piston  142  is closed, thereby compressing the gas sucked into the compression space P. When the pressure of the gas is higher than a predetermined pressure, the discharge cover  172  of the discharging valve assembly  170  is opened and discharges the compressed gas.  
     [0069] When the suction operation is converted to the compression operation, the bent open/close portion of the suction valve  143  returns to the initial state and is damped by the oil in the adhesion preventing groove  146   a . That is, by reducing the contact area of the open/close portion  143   c  of the suction valve  143  and the end portion surface  146  of the piston, chattering noise can be reduced.  
     [0070] As aforementioned, in the present invention, since the suction valve  143  is opened timely by reducing the viscosity force of the oil, the compression performance is increased and a reliability of the device is improved.  
     [0071] Also, in the present invention, the chattering noise generated by a contact of the piston  142  and the suction valve  143  can be reduced by damping the suction valve  143 .  
     [0072] 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.