Patent Publication Number: US-2005115771-A1

Title: Hermetic compressor

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims the benefit of Korean Patent Application No. 2003-85710, filed Nov. 28, 2003 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates, in general, to hermetic compressors and, more particularly, to a hermetic compressor which has an improved oil feed structure to efficiently feed lubricating oil using a rotating force of a rotating shaft to a plurality of drive parts.  
      2. Description of the Related Art  
      As an example of conventional techniques of hermetic compressors, Japanese Patent Laid-open Publication No. 2000-205130 discloses a hermetic compressor having an oil feed unit to feed lubricating oil using a rotating force of a rotating shaft to a plurality of drive parts. The oil feed unit of the above-mentioned hermetic compressor has an oil piece, a main oil feed path and a spiral oil feed groove, thus forcing the lubricating oil upward from a bottom of a hermetic casing to the drive parts. The oil piece of the conventional oil feed unit is provided on a lower end of the rotating shaft, while the main oil feed path extends upward in the rotating shaft above the oil piece while being eccentric from a central axis of the rotating shaft. The spiral oil feed groove is provided around an outer surface of the rotating shaft at a portion above an upper end of the main oil feed path so that the spiral oil feed groove communicates with the main oil feed path. The conventional oil feed unit further includes an upper oil feed path to feed the lubricating oil to a piston of a compression unit of the hermetic compressor. The upper oil feed path is provided in an eccentric part which is provided on an upper end of the rotating shaft, so that the upper oil feed path communicates with an upper end of the spiral oil feed groove.  
      During an operation of the conventional hermetic compressor, the rotating shaft rotates and the lubricating oil is lifted upward from the bottom of the hermetic casing by the oil piece. Thus, the lubricating oil is fed to the spiral oil feed groove via the eccentric main oil feed path. Thereafter, the lubricating oil flows upward along the spiral oil feed groove to the upper oil feed path of the eccentric part. While the oil flows upward along the spiral oil feed groove as described above, the oil lubricates and cools a junction between the outer surface of the rotating shaft and an inner surface of a shaft support part which supports the rotating shaft. The oil is, thereafter, fed from the upper oil feed path to the piston of the compression unit, thus lubricating the piston.  
      However, the conventional hermetic compressor having the above-mentioned oil feed unit is problematic as follows. Because the main oil feed path linearly and longitudinally extends in the rotating shaft while being in parallel to the central axis of the rotating shaft, a force which lifts the oil in the main oil feed path is reduced during a low speed rotation of the rotating shaft. In the above state, the main oil feed path may fail to feed a sufficient amount of lubricating oil to the spiral oil feed groove.  
      Furthermore, the upper oil feed path linearly extends upward in the eccentric part of the rotating shaft while being in parallel to the central axis of the rotating shaft, the oil lift force in the upper oil feed path may be reduced, so that the conventional oil feed unit of the hermetic compressor may fail to feed a sufficient amount of lubricating oil to the piston of the compression unit.  
     SUMMARY OF THE INVENTION  
      Accordingly, it is an aspect of the present invention to provide a hermetic compressor, which has an improved oil feed structure to generate a sufficient force which lifts oil upward even when a rotating shaft rotates at a low speed, thus efficiently feeding a sufficient amount of lubricating oil to a plurality of drive parts.  
      Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.  
      The above and/or other aspects are achieved by providing a hermetic compressor, including: a hermetic casing; a frame provided in the hermetic casing; a drive unit provided in a lower portion of the frame; a compression unit provided on an upper portion of the frame; a rotating shaft vertically installed in the frame to transmit a rotating force of the drive unit to the compression unit, with an eccentric part provided on an upper end of the rotating shaft and coupled to the compression unit; and an oil feed unit provided on the rotating shaft to feed oil from a bottom of the hermetic casing to a plurality of drive parts, the oil feed unit including: a first oil pickup unit provided on a lower end of the rotating shaft to lift the oil upward from the bottom of the hermetic casing; a first oil feed path provided in the rotating shaft above the first oil pickup unit while being eccentric from a central axis of the rotating shaft; a spiral oil feed groove provided around an outer surface of the rotating shaft above the first oil feed path and communicating with the first oil feed path; a second oil feed path provided in the eccentric part of the rotating shaft and communicating with the spiral oil feed groove; and a second oil pickup unit provided in the first oil feed path to increase an oil lift force.  
      The first oil feed path may be inclinedly provided in the rotating shaft so that a central axis of the first oil feed path is diverged from the central axis of the rotating shaft in a direction from the lower end to the upper end of the rotating shaft.  
      The second oil feed path may be inclinedly provided in the eccentric part of the rotating shaft so that a central axis of the second oil feed path is diverged from the central axis of the rotating shaft in a direction from a lower end to an upper end of the eccentric part.  
      The hermetic compressor may further include: a bearing provided between the upper portion of the frame and a lower end of the eccentric part of the rotating shaft, wherein the second oil feed path may extend from the eccentric part of the rotating shaft to a predetermined position of an interior of the rotating shaft under the bearing and communicates with the spiral oil feed groove via a communication hole which is provided on the rotating shaft in a radial direction.  
      The bearing may be a thrust bearing to support an axial load.  
      The hermetic compressor may further include: an oil guide part provided on the outer surface of the rotating shaft so that the oil guide part extends from an upper end of the spiral oil feed groove to a position of the bearing, thus feeding the oil to the bearing.  
      The oil guide part may be a flat surface which is provided on the outer surface of the rotating shaft in an axial direction.  
      The first oil pickup unit may include: an oil guide body having a cylindrical shape and provided with an oil inlet at a lower end of the oil guide body, the oil inlet of the oil guide body having an inner diameter which is smaller than an outer diameter of the oil guide body; and a spiral blade provided in the oil guide body.  
      The second oil pickup unit may be a spiral blade provided in the first oil feed path.  
      The hermetic compressor may further include: an auxiliary oil feed path provided in the eccentric part of the rotating shaft in a radial direction to communicate with the second oil feed path.  
      The above and/or other aspects are achieved by providing a hermetic compressor, including: a hermetic casing; a frame provided in the hermetic casing; a drive unit provided in a lower portion of the frame; a compression unit provided on an upper portion of the frame; a rotating shaft vertically installed in the frame to transmit a rotating force of the drive unit to the compression unit, with an eccentric part provided on an upper end of the rotating shaft and coupled to the compression unit; and an oil feed unit provided on the rotating shaft to feed oil from a bottom of the hermetic casing to a plurality of drive parts, the oil feed unit including: a first oil pickup unit provided on a lower end of the rotating shaft to lift the oil upward from the bottom of the hermetic casing; a first oil feed path provided in the rotating shaft above the first oil pickup unit while being eccentric from a central axis of the rotating shaft; a spiral oil feed groove provided around an outer surface of the rotating shaft above the first oil feed path and communicating with the first oil feed path; and a second oil feed path provided in the eccentric part of the rotating shaft and communicating with the spiral oil feed groove, the second oil feed path being inclined in the eccentric part so that a central axis of the second oil feed path is diverged from the central axis of the rotating shaft in a direction from a lower end to an upper end of the eccentric part. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:  
       FIG. 1  is a sectional view showing a construction of a hermetic compressor, according to an embodiment of the present invention;  
       FIG. 2  is a partially sectioned front view showing a construction of an oil feed unit provided on a rotating shaft of the hermetic compressor of  FIG. 1 ;  
       FIG. 3  is a partially sectioned front view showing a construction of both a second oil feed path and an oil guide part provided on an upper portion of the rotating shaft of  FIG. 2 ; and  
       FIG. 4  is a sectional view taken along a line IV-IV′ of  FIG. 3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
      As shown in  FIG. 1 , the hermetic compressor according to the embodiment of the present invention has a hermetic casing  10 , a frame  12  installed in the hermetic casing  10  while being supported by a plurality of damping units  11 , a compression unit  20  provided on an upper portion of the frame  12 , and a drive unit  30  provided in a lower portion of the frame  12  to drive the compression unit  20 .  
      The hermetic compressor further includes a rotating shaft  40  which is vertically installed in the frame  12  while being supported by a shaft support part  13  of the frame  12  to rotate relative to the frame  12 . The rotating shaft  40  transmits a rotating force of the drive unit  30  to the compression unit  20 , with an eccentric part  41  provided on an upper end of the rotating shaft  40  to be eccentric from a central axis of the rotating shaft  40 . The eccentric part  41  is coupled to the compression unit  20 . The hermetic compressor further includes a bearing support unit  42  which is provided at a lower end of the eccentric part  41 , with a diameter of the bearing support unit  42  being larger than an outer diameter of the rotating shaft  40  so that the bearing support unit  42  is supported on an upper surface of the frame  12 . The hermetic compressor further includes a thrust bearing  43  which is provided between the upper surface of the frame  12  and a lower surface of the bearing support unit  42  to support an axial load of the rotating shaft  40  and to allow for a smooth rotation of the rotating shaft  40 .  
      The drive unit  30  of the hermetic compressor includes a rotor  31  which is axially fitted over the rotating shaft  40  to rotate along with the rotating shaft  40 . The drive unit  30  further includes a stator  32  which is securely mounted around the rotor  31  to generate an electromagnetic field during an operation of the hermetic compressor. The compression unit  20  has a cylinder block  21  which defines a compression chamber therein to compress a refrigerant, with a cylinder head  22  mounted to an end of the cylinder block  21  to cover the compression chamber. The compression unit  20  further includes a piston  23  which is received in the compression chamber of the cylinder block  21  to compress the refrigerant while reciprocating within the compression chamber. The piston  23  of the compression unit  20  is connected to the eccentric part  41  of the rotating shaft  40  by a connecting rod  25 . Thus, when the rotating shaft  40  rotates by an operation of the drive unit  30 , an eccentric rotating motion of the eccentric part  41  is converted into a rectilinear reciprocating motion of the piston  23  by the connecting rod  25 , so that the piston  23  rectilinearly reciprocates in the compression chamber to compress the refrigerant in the compression chamber.  
      The hermetic compressor of the present invention contains a predetermined amount of lubricating oil on a bottom of the hermetic casing  10  to lubricate and cool a plurality of drive parts of the hermetic compressor. The hermetic compressor of the present invention further includes an oil feed unit which is provided on the rotating shaft  40  to feed the lubricating oil from the bottom of the hermetic casing  10  to the plurality of drive parts using the rotating force of the rotating shaft  40 .  
      The oil feed unit of the present invention includes a first oil pickup unit  51 , a first oil feed path  52 , a spiral oil feed groove  54  and a second oil feed path  56 , as shown in  FIG. 2 . The first oil pickup unit  51  is provided on the lower end of the rotating shaft  40 , while the first oil feed path  52  is provided in the rotating shaft  40  above the first oil pickup unit  51 . The spiral oil feed groove  54  is provided around the outer surface of the rotating shaft  40  above the first oil feed path  52  and communicates with the first oil feed path  52 . The second oil feed path  56  is provided in the eccentric part  41  of the rotating shaft  40  and communicates with the spiral oil feed groove  54 .  
      In a detailed description of the oil feed unit, the first oil pickup unit  51  includes an oil guide body  51   a  which is mounted at an upper end thereof to the lower end of the rotating shaft  40 . The oil guide body  51   a  has a hollow cylindrical shape, with a diameter of the oil guide body  51   a  reduced in a direction from the upper end to a lower end thereof. The oil guide body  51   a  is immersed at the lower end thereof in the lubricating oil, with an oil inlet  51   c  provided at the lower end of the oil guide body  51   a . The oil inlet  51   c  of the oil guide body  51   a  has an inner diameter which is smaller than an outer diameter of the lower end of the oil guide body  51   a . The first oil pickup unit  51  further includes a spiral blade  51   b  which is provided in the oil guide body  51   a . During a rotation of the rotating shaft  40 , the lubricating oil which has been introduced into the lower portion of the first oil pickup unit  51  through the oil inlet  51   c  is lifted upward along the spiral blade  51   b  to the first oil feed path  52  by a rotation of the spiral blade  51   b.    
      The first oil feed path  52  to guide the oil upward in the rotating shaft  40  longitudinally extends in the rotating shaft  40  from a predetermined lower position above the upper end of the first oil pickup unit  51  to a predetermined upper position above a lower end of the shaft support part  13  of the frame  12  which supports the rotating shaft  40 . The first oil feed path  52  is eccentric from the central axis of the rotating shaft  40 , and is inclined in the rotating shaft  40  so that a central axis of the first oil feed path  52  is diverged from the central axis of the rotating shaft  40  in an upward direction at a predetermined angle θ 1 . The first oil feed path  52  further includes a first communication hole  52   a  which is provided on the rotating shaft  40  in a radial direction at a position aligned with the upper end of the first oil feed path  52 . Thus, the upper end of the first oil feed path  52  communicates with a lower end of the spiral oil feed groove  54  via the first communication hole  52   a . The above-mentioned construction of the first oil feed path  52  increases a centrifugal force acting on the lubricating oil in the first oil feed path  52  during the rotation of the rotating shaft  40 , thus the oil is efficiently lifted upward through the first oil feed path  52 . The oil feed unit of the present invention further includes a second oil pickup unit  53  which is a spiral blade provided in the first oil feed path  52  to increase the oil lift force in the first oil feed path  52 . During an operation of the hermetic compressor, the oil lift force in the first oil feed path  52  is increased by both an operation of the second oil pickup unit  53  and the centrifugal force acting on the lubricating oil resulting from the rotation of the rotating shaft  40 . Thus, the oil is efficiently lifted upward to the spiral oil feed groove  54  through the first oil feed path  52 .  
      The spiral oil feed groove  54  is provided around the outer surface of the rotating shaft  40  to have a predetermined depth, so that an oil passage is defined between the outer surface of the rotating shaft  40  and the inner surface of the shaft support part  13  of the frame  12 . Thus, the lubricating oil smoothly flows upward along the spiral oil feed groove  54  during the rotation of the rotating shaft  40 . While the lubricating oil flows upward along the spiral oil feed groove  54 , the oil lubricates and cools the junction between the outer surface of the rotating shaft  40  and the inner surface of the shaft support part  13 .  
      The second oil feed path  56  is inclined in the eccentric part  41  of the rotating shaft  40  so that a central axis of the second oil feed path  56  is diverged from the central axis of the rotating shaft  40  in the upward direction at a predetermined angle θ 2 . The second oil feed path  56  communicates, at a lower end thereof, with an upper end of the spiral oil feed groove  54  via a second communication hole  55  that is provided on the rotating shaft  40  in the radial direction. The second oil feed path  56  communicates, at an upper end thereof, with an upper surface of the eccentric part  41  of the rotating shaft  40 . The above-mentioned construction of the second oil feed path  52  increases a centrifugal force acting on the lubricating oil in the second oil feed path  56  during the rotation of the rotating shaft  40 . Thus, the lubricating oil is efficiently fed through the second oil feed path  56  from the upper end of the spiral oil feed groove  54  to the compression unit  12  which is provided on the upper portion of the frame  12 . The oil feed unit of the present invention further includes a second oil pickup unit  53  which is a spiral blade provided in the first oil feed path  52  to increase the oil lift force in the first oil feed path  52 . During an operation of the hermetic compressor, the oil lift force in the first oil feed path  52  is increased by both an operation of the second oil pickup unit  53  and the centrifugal force acting on the lubricating oil resulting from the rotation of the rotating shaft  40 . Thus, the oil is efficiently lifted upward to the spiral oil feed groove  54  through the first oil feed path  52 . The hermetic compressor further includes an auxiliary oil feed path  57  which is provided in the eccentric part  41  of the rotating shaft  40  in the radial direction to communicate with the second oil feed path  56 . Thus, the lubricating oil is fed from the second oil feed path  56  to the connecting rod  25  connected to the eccentric part  41 .  
      As shown in  FIG. 3 , the second oil feed path  56  extends from the eccentric part  41  of the rotating shaft  40  to a predetermined position of an interior of the rotating shaft  40  under the thrust bearing  43 . In other words, the second communication hole  55 , which allows the second oil feed path  56  to communicate with the spiral oil feed groove  54 , is provided at the position under the thrust bearing  43 . When the upper end of the spiral oil feed groove  54  provided around the outer surface of the rotating shaft  40  is terminated at a position aligned with the thrust bearing  43 , the lubricating oil which has reached the upper end of the spiral oil feed prove  54  cannot flow upward, but is undesirably dispersed to an outside in the radial direction through gaps of the thrust bearing  43 . Thus, the second communication hole  55  is provided on the rotating shaft  40  at the position under the thrust bearing  43 .  
      The hermetic compressor of the present invention further includes an oil guide part  58  which is provided on the outer surface of the rotating shaft  40  so that the oil guide part  58  extends from the upper end of the spiral oil feed groove  54  to the position of the thrust bearing, thus feeding the lubricating oil from the upper end of the spiral oil feed groove  54  to the thrust bearing  43  to lubricate and cool the thrust bearing  43 . The oil guide part  58  is defined by a flat surface which is provided on the outer surface of the rotating shaft  40  in an axial direction, as shown in  FIG. 4 . Thus, the oil guide part  58  provides an oil passage between the outer surface of the rotating shaft  40  and the inner surface of the shaft support part  13  of the frame  12 .  
      The operation and effect of the hermetic compressor will be described herein below.  
      When the rotating shaft  40  rotates by the operation of the drive unit  30  provided in the lower portion of the frame  12 , as shown in  FIG. 1 , the rotating motion of the rotating shaft  40  is converted into the rectilinear reciprocating motion of the piston  23  by the connecting rod  25  of the compression unit  20 , so that the piston  23  rectilinearly reciprocates in the compression chamber of the cylinder block  21 . Due to the rectilinear reciprocating motion of the piston  23 , the refrigerant is drawn into the compression chamber of the cylinder block  21  to be compressed, prior to being discharged from the compression chamber.  
      During the above-mentioned operation, the lubricating oil is lifted upward along the rotating shaft  40  from the bottom of the hermetic casing  10  to the plurality of drive parts by an operation of the oil feed unit, the lubricating and cooling the drive parts and allows for a smooth operation of the hermetic compressor. The operation of the oil feed unit in the above state will be described in more detail herein below.  
      When the first oil pickup unit  51  rotates along with the rotating shaft  40 , the lubricating oil on the bottom of the hermetic casing  10  is introduced into the first oil pickup unit  51  through the oil inlet  51   c , and is fed upward to the first oil feed path  52  by the operation of the spiral blade  51   b  provided in the first oil pickup unit  51 .  
      In the above state, the first oil feed path  52  is eccentric from the central axis of the rotating shaft  40 , and is inclined in the rotating shaft  40  so that the central axis of the first oil feed path  52  is diverged from the central axis of the rotating shaft  40  at the angle θ 1 . Furthermore, the second oil pickup unit  53  is provided in the first oil feed path  52 . Therefore, even when the rotating shaft  40  rotates at a low speed, the oil lift force in the first oil feed path  52  is increased, thus the oil is efficiently fed to the spiral oil feed groove  54  through the first oil feed path  52 . In the above state, the first communication hole  52   a  which is provided on the rotating shaft  40  at the position aligned with the upper end of the first oil feed path  52 , feeds the oil from the first oil feed path  52  to the spiral oil feed groove  54 .  
      Once the oil is introduced to the spiral oil feed groove  54 , the oil flows upward by the operation of the spiral oil feed groove  54  while lubricating and cooling the junction between the outer surface of the rotating shaft  40  and the inner surface of the shaft support part  13  of the frame  12 . Thus, the oil reaches the upper end of the spiral oil feed groove  54  and, thereafter, the oil is fed from the spiral oil feed groove  54  to the second oil feed path  56  through the second communication hole  55  of the rotating shaft  40 . The oil is, thereafter, fed from the second oil feed path  56  to a plurality of drive parts of the compression unit  20 . In the above state, the second oil feed path  56  is inclined in the eccentric part  41  relative to the central axis of the rotating shaft  40  at the angle θ 2 . Therefore, even when the rotating shaft  40  rotates at a low speed, the oil lift force in the second oil feed path  56  is increased, thus the oil is efficiently fed to the compression unit  20 . Furthermore, in the above state, because the oil is fed from the upper end of the spiral oil feed groove  54  to the thrust bearing  43  through the oil guide part  58 , the thrust bearing  43  is efficiently lubricated and cooled.  
      As apparent from the above description, the present invention provides a hermetic compressor, in which a first oil feed path is provided in a rotating shaft while being eccentric from a central axis of the rotating shaft and being diverged from the rotating shaft in an upward direction, with a second oil pickup unit provided in the first oil feed path. Therefore, even when the rotating shaft rotates at a low speed, an oil lift force in the first oil feed path is increased, thus lubricating oil is efficiently fed upward along the rotating shaft.  
      Furthermore, a second oil feed path is provided in an upper portion of the rotating shaft of the hermetic compressor while being diverged from the rotating shaft in the upward direction. Therefore, even when the rotating shaft rotates at a low speed, an oil lift force in the second oil feed path is increased, thus the lubricating oil is efficiently fed to a plurality of drive parts of a compression unit.  
      Furthermore, because the lubricating oil is fed to a thrust bearing through an oil guide part provided on the upper portion of the rotating shaft, the thrust bearing is efficiently lubricated and cooled.  
      Although a preferred embodiment of the present invention has been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.