Patent Publication Number: US-2005139428-A1

Title: Oil feeding apparatus for reciprocating compressor

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a reciprocating compressor, and particularly, to an oil feeding apparatus for a reciprocating compressor capable of simplifying the number of components for feeding oil to a compressing portion where gas is compressed and of preventing distortion of components during assembling process.  
      2. Description of the Conventional Art  
      In general, a reciprocating compressor is a device for sucking and compressing a refrigerant gas by a linear reciprocation of a piston in a cylinder. The reciprocating compressor may be divided into two different methods according to its driving mechanism. Namely, in one method, a rotational motion of a motor is transformed to a linear reciprocation to be then transferred to the piston, while, in the other method, a linear reciprocation of a motor is directly transferred to the piston.  
       FIG. 1  shows an example of a reciprocating compressor in which the linear reciprocation is directly transferred to the piston. As shown in  FIG. 1 , the reciprocating compressor includes: a casing  100  having a certain inner space and filled with a certain amount of oil at a bottom surface thereof; a frame unit installed at the casing  100  to be elastically supported; a driving motor  200  fixed to the frame unit, for generating a linear reciprocating driving force; a compression unit  300  for receiving the linear reciprocating driving force of the driving motor  200  to suck and compress a gas; a resonant spring unit  400  for elastically supporting in a moving direction components linearly reciprocating among components of the driving motor  200  and the compression unit  300  to induce a resonant motion; and an oil feeding unit  500  mounted on the frame unit.  
      The frame unit includes: a front frame  610  to which the compression unit  300  is fixedly-coupled and a part of the driving motor  200  is supported; a middle frame  620  positioned having a certain interval from the front frame  610 , for fixing the driving motor  200  together with the front frame  610 ; and a rear frame  630  for supporting the resonant spring unit  400  together with the middle frame  620 .  
      The driving motor  200  is comprised of: an outer stator  210  coupled between the front frame  610  and the middle frame  620 ; an inner stator  220  fixedly-coupled to the front frame  610  to form a certain interval with the outer stator  210 ; and a mover  230  inserted between the outer stator  210  and the inner stator  220  to be linearly reciprocated. The outer stator  210  has a winding coil  240  therein, and the mover  230  has a magnet  231  and a holder  232  for supporting the magnet  231 .  
      The compression unit  300  includes: a cylinder  310  fixedly-coupled to the front frame  610 ; a piston  320  inserted in a compression space of the cylinder  310  to be linearly moved and coupled to the mover  230  of the driving motor  200 ; a suction valve  330  coupled to an end surface of the piston  320 , for opening/closing a suction passage formed in the piston  320 ; a discharge cover  340  coupled to the front frame  610 , for covering one side of the cylinder  310 ; a discharge valve  350  inserted into the discharge cover  340 , for opening/closing the compression space of the cylinder  310 ; and a valve spring  360  for elastically supporting the discharge valve  350  positioned in the discharge cover  350 .  
      The resonant spring unit  400  includes: a spring plate  410  coupled to a connection portion between the mover  230  and the piston  320 ; and resonant springs  420  respectively positioned at both sides of the spring plate  410 .  
      An unexplained reference numeral  110  indicates a suction pipe, and  120  indicates a discharge pipe.  
      An operation the aforementioned reciprocating compressor will now be described.  
      First of all, once power is applied to the driving motor  200 , a flux is formed at the outer stator  210  and the inner stator  220  by current flowing on the winding coil  240  of the driving motor  200 . Depending on an interaction between the flux and another flux formed by the magnet  231  of the mover  230 , the mover  230  is linearly reciprocated. According to the linear reciprocation of the mover  320 , the piston  320  connected to the mover  320  is linearly reciprocated in the cylinder  310 .  
      By a pressure difference of the compression space of the cylinder  310  by the linear reciprocation of the piston  320 , the suction valve  330  and the discharge valve  350  open/close the gas flow passage, and then suck the gas in the cylinder  310 , compress and discharge the gas. According to the repetition of those processes, the gas is continually compressed.  
      During sucking, compressing and discharging the gas in the compression unit  300 , a vibration is generated, which is then transferred to the frame unit to thereby vibrate the frame unit. According to the vibration of the frame unit, the oil feeding unit  50  is also vibrated so as to pump the oil filled in the bottom surface of the casing  100 . Then, the oil is fed to components in which a relative motion is generated, among components of the compression unit  300 .  
      On the other hand, it will now be explained of the oil feeding unit  500  coupled to the frame unit, for pumping the oil filled in the bottom surface of the casing  100  in detail.  
      The oil feeding unit  500 , as can be seen from  FIG. 2 , is comprised of: an oil pumping part mounted on a lower portion of the frame unit, for pumping oil with vibrating together with the frame unit; and an oil flow passage part for guiding the pumped oil to the compression unit  300 .  
      The oil pumping part includes: an oil cylinder  510  pressed in the lower portion of the front frame  610  and coupled thereto; an oil piston  520  slidingly inserted in the oil cylinder  510 , for pumping the oil; springs  530  positioned at each side of the oil piston  520 , for elastically supporting the oil piston  520 ; and an oil valve  540  positioned at a front surface of the front frame  610 , for opening/closing between the oil cylinder  510  and the oil flow passage part.  
      The oil flow passage part includes: a first oil groove  611  formed in a certain shape at a front surface of the front frame  610 ; and an oil cover  550  having a second oil groove  551  of a certain shape therein, and coupled to the front frame  610  to form the oil flow passage with the first oil groove  611  of the front frame  610 .  
      The oil valve  540  is positioned between the front frame  610  and the oil cover  550 , and is supported by a valve seat  560  placed between the front frame  610  and the oil cover  550 .  
      The oil cylinder  510  is formed in a pipe shape having a certain length. A ring-shaped coupling groove  612  having a certain outside diameter and depth is formed at one side of the front frame  610 . A through hole  613  connected to the first oil groove  611  is formed at an inner surface of the ring-shaped coupling groove  612 . The oil cylinder  510  is coupled to the front frame  610  by being pressed in the ring-shaped coupling groove  612  of the front frame  610 .  
      An oil suction pipe  570  is coupled to the front frame  610  to be positioned at a side portion of the oil cylinder  510 . The oil suction pipe  570  is formed in a curved shape having a certain length. Also, the oil suction pipe  570  is coupled to the front frame  610  to be communicated with the first oil groove  611  of the front frame and the curved part thereof is positioned in the oil filled in the bottom surface of the casing  100 .  
      An unexplained reference numeral  580  indicates an oil cylinder cover.  
      As stated above, when the oil feeding unit is vibrated together with the frame unit, the oil piston  520  is relatively moved in the oil cylinder  510 . Then, the oil filled in the bottom surface of the casing  100  is pumped through the oil suction pipe  570  by a pressure difference generated in the oil cylinder  510  according to the relative motion of the oil piston  520  in the oil cylinder  510 . The oil pumped through the oil suction pipe  570  is fed to the compression unit  300  through the oil flow passage part. The oil fed to the compression unit  300  is then recovered in the bottom surface of the casing  100  via the inside of the compression unit  300 .  
      However, in the oil feeding unit of the reciprocating compressor, as shown in  FIG. 3 , the front frame  610  and the oil cylinder  510  are manufactured with respectively different components and then coupled to each other. As a result, because processes for manufacturing the components become complicated and processing therefor becomes precise, the manufacturing costs for the components are increased. Also, the number of components are relatively increased to thereby increase the number of assembling processes, which causes an assembling productivity to be degraded. If procedures for the processing and assembling are not completed precisely, the oil may not be pumped well and thus it may cause a lack of oil of the compression unit  300 .  
      Furthermore, the oil cylinder  510  is pressed in by such a press to be coupled to the ring-shaped coupling groove  612  of the front frame, which causes a distortion or breakage of the thin oil cylinder  510  during the assembling process and an oil contamination due to fine debris generated by abrasion of the oil cylinder  510 .  
     SUMMARY OF THE INVENTION  
      Therefore, an object of the present invention is to provide an oil feeding apparatus for a reciprocatirig compressor capable of simplifying the number of components for feeding oil to a compressing portion where gas is compressed and of preventing distortion of components during assembling therefor.  
      Another object of the present invention is to provide an oil feeding apparatus for a reciprocating compressor capable of preventing an oil contamination as well as an oil leakage.  
      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 an oil feeding apparatus for a reciprocating compressor, comprising: a frame unit having thereon a compression unit for receiving a linear reciprocating driving force of a driving motor to compress a gas, and positioned in a casing filled with oil at a bottom surface thereof to be elastically supported; an oil cylinder positioned at a lower portion of the frame unit and vibrating together with the frame unit; an oil flow passage formed at the frame unit to be communicated with the oil cylinder; an oil valve placed at the frame unit, for opening/closing the oil flow passage; an oil piston movably-inserted in the oil cylinder; and a spring for elastically supporting the oil piston, wherein the frame unit and the oil cylinder are integrally formed with each other.  
      Another embodiment of the present invention, there is provided an oil feeding apparatus for a reciprocating compressor comprising: a frame having a frame main body mounted with a driving motor for generating a linear reciprocating driving force and a compression unit for compressing gas by receiving the driving force of the driving motor, and an oil cylinder which is extendedly-protruded from a lower surface of the frame main body to have certain inside diameter and length; an oil piston movably-inserted in the oil cylinder of the frame; and springs for elastically supporting the oil piston.  
      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  
      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 sectional view showing a typical reciprocating compressor;  
       FIG. 2  is a sectional view showing an oil feeding apparatus for a conventional reciprocating compressor;  
       FIG. 3  is a perspective view showing an oil feeding apparatus for the conventional reciprocating compressor;  
       FIG. 4  is a sectional view showing a reciprocating compressor having an oil feeding apparatus in accordance with an embodiment of the present invention;  
       FIG. 5  is a sectional view showing an oil feeding apparatus for a reciprocating compressor according to the present invention; and  
       FIG. 6  is a perspective view showing the oil feeding apparatus for the reciprocating compressor according to 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.  
      Hereinafter, it will be described in detail about an oil feeding apparatus for a reciprocating compressor in accordance with embodiments of the present invention with reference to the accompanying drawings.  
       FIG. 4  is a sectional view showing a reciprocating compressor having an oil feeding apparatus in accordance with an embodiment of the present invention, and  FIG. 5  is a sectional view showing the oil feeding apparatus for the reciprocating compressor according to the present invention. The same portions to the conventional art have the same reference numerals.  
      As shown in  FIGS. 4 and 5 , the reciprocating compressor includes: a casing  100  having a certain inner space and filled with a certain amount of oil at a bottom surface thereof; a frame unit installed in the casing to be elastically supported; a driving motor  200  fixed to the frame unit, for generating a linear reciprocating driving force; a compression unit  300  for receiving the linear reciprocating driving force of the driving motor and then sucking and compressing a gas; and a resonant spring unit  400  for elastically supporting in a moving direction components linearly reciprocating, among components of the driving motor  200  and the compression unit  300  thereby to induce a resonant motion. This construction is similar to the aforementioned one, of which detailed explanation will be then omitted.  
      The frame unit has an oil feeding apparatus therein.  
      The frame unit includes: a front frame  640  fixedly-coupled to the compression unit  300  and to which a part of the driving motor  200  is supported; a middle frame  620  positioned having a certain interval from the front frame  640 , for fixing the driving motor  200  together with the front frame  640 ; and a rear frame  630  for supporting the resonant spring unit  400  together with the middle frame  620 .  
      The oil feeding apparatus includes: an oil cylinder placed at a lower portion of the front frame  640  and vibrating together with the frame unit; an oil flow passage formed at the frame unit to be communicated with the oil cylinder  641 ; an oil valve  540  placed at the frame unit, for opening/closing the oil flow passage; an oil piston  520  movably-inserted in the oil cylinder  641 ; springs  530  for elastically supporting the oil piston  520 ; and an oil suction pipe  645  placed at a lower portion of the front frame  640  to be communicated with the oil flow passage.  
      The oil cylinder  641  is integrally formed with the front frame  640  and formed in a pipe shape having certain inside diameter and length. The front frame  640  and the oil cylinder  641  are formed of the same material.  
       FIG. 6  shows a structure of the front frame  640 . The front frame  640 , as shown in  FIG. 6 , is comprised of: a frame main body  642  on which the driving motor  200  and the compression unit  300  are mounted; and the oil cylinder  641  formed to be extendedly-protruded from a lower surface of the frame main body  642  to have certain inside diameter and length.  
      The oil piston  520  is movably-inserted in the oil cylinder  641  of the frame, and the spring  530  for supporting both sides of the oil piston  520  is inserted in the oil cylinder  641 .  
      A first oil groove  643  is formed in a certain shape at a front surface of the front frame  640  and a through hole  644  is formed to communicate the first oil groove  643  and the oil cylinder  641 . An oil cover  550  having a second oil groove  551  therein of a certain shape is coupled to the front frame  640  to cover the first oil groove  643 . The first oil groove  643 , the second oil groove  551  and the through hole  644  form the oil flow passage.  
      The oil valve  540  is positioned between the front frame  640  and the oil cover  550 , and is supported by a valve seat  560  placed between the front frame  640  and the oil cover  550 .  
      The oil suction pipe  645  is formed in a curved shape. One side thereof is under the oil filled in a bottom surface of the casing  100 . Preferably, the oil suction pipe  645  is integrally formed with the front frame  640 .  
      Hereinafter, an operation effect of the oil feeding apparatus for the reciprocating compressor according to the present invention will be explained as follows.  
      First, the reciprocating compressor having the oil feeding apparatus according to the present invention is operated as aforementioned.  
      Furthermore, the oil feeding apparatus is operated as below. First, vibration in a horizontal direction is generated in the frame unit by an operation of the compression unit  300  and the driving motor  200  coupled to the frame unit. The oil piston  520  is relatively moved in the oil cylinder  641  by the vibration of the frame unit. Then, the oil filled in the bottom surface of the casing  100  is pumped through the oil suction pipe  645  by a pressure difference generated in the oil cylinder  641  according to the relative movement of the oil piston  520  in the oil cylinder  641 .  
      The oil pumped through the oil suction pipe  645  is fed to the compression unit  300  through the oil flow passage. The oil fed to the compression unit  300  is then recovered to the bottom surface of the casing  100  through the inside of the compression unit  300 .  
      Since the front frame  640  and the oil cylinder  641  are integrally formed in the oil feeding apparatus, the front frame  640  and the oil cylinder  641  may be manufactured by a casting.  
      Since the front frame  640  and the oil cylinder  641  are formed in the oil feeding apparatus according to the present invention, there is required for only one component to form the front frame  640  and the oil cylinder  641 , thereby relatively simplifying a configuration of the oil feeding apparatus.  
      Moreover, since the front frame  640  and the oil cylinder  641  are integrally formed, there is no need to manufacture each front frame  640  and the oil cylinder  641  separately, thereby decreasing assembling processes as well as allowing easy manufacturing and processing.  
      Furthermore, in case of manufacturing a separate oil cylinder  641  and then assembling it into the front frame  640 , the thin oil cylinder  641  may be distorted or damaged, which may cause the relative movement of the oil piston  520  not to be well achieved. However, in the present invention, because the front frame  640  and the oil cylinder  641  are integrally formed, a mis-operation of the oil piston due to a distortion of the oil cylinder  641  can be prevented thereby to feed oil smoothly.  
      Also, in case of manufacturing a separate oil cylinder  510  and then assembling it into the front frame  610  as the conventional art, an impurity may be generated between the oil cylinder  510  and the front frame  610  so as to contaminate the oil. However, in the present invention, since the front frame  640  and the oil cylinder  641  are integrally formed, the oil can be protected from being contaminated and prevented from being leaked out due to errors that may be occurred during manufacturing or assembling, which results in prevention of a lack of oil.  
      As stated so far, in the oil feeding apparatus for the reciprocating compressor in accordance with the present invention, since the number of components as well as the number of assembling processes are reduced, it is advantageous to increase assembling productivity. Also, it is effective to reduce manufacturing costs owing to a simplification of processing and manufacturing.  
      Furthermore, the oil can be easily fed by preventing the oil leakage and reliability of the compressor can be improved by preventing the oil contamination.  
      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.