Patent Publication Number: US-7722335-B2

Title: Linear compressor

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a linear compressor, and, more particularly, to a linear compressor in which a spring seat, for use in the fixation of a supporting spring, is provided with a buffer to prevent vibration generated in the spring seat from being transmitted to a shell, thereby eliminating noise discharge to the outside of the linear compressor. 
   2. Description of the Related Art 
   Generally, a linear compressor is an apparatus to suction and compress fluid, such as gaseous fluid (hereinafter, referred to as fluid) while linearly reciprocating a piston inside a cylinder using a linear driving force of a linear motor to thereby discharge the compressed fluid. 
     FIG. 1  is a longitudinal sectional view of a conventional linear compressor. 
   As shown in  FIG. 1 , the conventional linear compressor includes a shell  2 , and a linear compression unit  4  arranged in the shell  2  to compress fluid. 
   A fluid suction pipe  6  is penetrated through one side of the shell  2 , and a fluid discharge pipe  8  is also penetrated through the other side of the shell  2 . 
   The linear compression unit  4  includes a cylinder block  12  centrally provided with a cylinder  10 , a back cover  16  having a fluid suction port  14 , a piston  18  inserted in the cylinder  10  to be linearly reciprocated inside the cylinder  10 , a linear motor  20  to generate a driving force required to linearly reciprocate the piston  18  inside the cylinder  10 , and a discharge unit  30  provided at a front side of the cylinder  10  to discharge compressed fluid from the cylinder  10 . 
   The linear motor  20  is basically comprised of a stator and a mover. The stator includes an outer stator  21 , an inner stator  22 , a bobbin  23  mounted in the outer stator  21 , and a coil  24  wound around the bobbin  23  to produce a magnetic field. The mover includes a magnet  25  to be linearly reciprocated using a magnetic force generated in the vicinity of the coil  24 , and a magnet frame  26  to support the magnet  25  mounted thereon. 
   The piston  18  is affixed to the magnet frame  26  to receive a linear movement force of the magnet  25 . The piston  18  is formed at a rear end thereof with a flange portion  28  to be affixed to a front surface of the magnet frame  26 . 
   The linear compressor further comprises main springs to elastically support the piston  18  when the piston is linearly reciprocated. The main springs include a first main spring  34  interposed between the back cover  16  and a spring support  32  affixed to a rear surface of the magnet frame  26 , and a second main spring  38  interposed between the spring support  32  and a stator cover  36  affixed to a rear end of the outer stator  21 . 
   A plurality of supporting springs  40  are mounted between the shell  2  and the linear compression unit  4  to support the linear compression unit  4  in a shock-absorbing manner. 
   The supporting springs  40  include a first supporting spring  41  interposed between the cylinder block  12  and the shell  2 , and a second supporting spring  42  interposed between the spring support  32  and the shell  2 . 
   Each of the first and second supporting springs  41  and  42  has a first end fitted into a first spring seat  43  mounted at the shell  2 , and a second end fitted into a second spring seat  44  mounted at the cylinder block  12  or spring support  32 . 
   Now, operation of the conventional linear compressor configured as stated above will be explained. 
   First, when the linear motor  20  is operated, the magnet  25  is linearly reciprocated to transmit a linear reciprocating movement force to the piston  18  by way of the magnet frame  26 . Thereby, the piston  18  is linearly reciprocated inside the cylinder  10 . 
   According to the linear reciprocating movement of the piston  18 , fluid present inside the shell  2  is introduced into the cylinder  10  through the fluid suction port  14  of the back cover  16  to thereby be compressed in the cylinder  10  by means of the piston  18 . After that, the compressed fluid is discharged to the outside of the shell  2  through the discharge unit  30  and the discharge pipe  8 . 
   In operation, the first and second supporting springs  41  and  42  serve to absorb vibration generated in the linear compression unit  4 . 
   This prevents the vibration of the linear compression unit  4  from being transmitted to the shell  2 , eliminating noise generation of the linear compressor. 
   However, in the case of the conventional linear compressor, since both ends of the supporting springs  40  are fitted into the first and second spring seats  43  and  44 , it shows relative movement between the supporting springs  40  and the first and second spring seats  43  and  44  upon intensive operation of the linear compression unit  4 , causing frictional vibration relative to each other. Consequently, the frictional vibration is transmitted to the shell  2 , resulting in discharge of high-frequency noise to the outside of the linear compressor. 
   SUMMARY OF THE INVENTION 
   Therefore, the present invention has been made in view of the above problem, and it is an object of the present invention to provide a linear compressor capable of preventing vibration and noise due to relative movement between supporting springs and spring seats. 
   In accordance with a first aspect of the present invention, the above and other objects can be accomplished by the provision of a linear compressor comprising: a shell; a linear compression unit mounted in the shell to compress fluid using a linear driving force of a linear motor; a plurality of supporting springs provided between the shell and the linear compression unit to support the linear compression unit in a shock-absorbing manner; a plurality of spring seats configured to affix opposite ends of each supporting spring to the shell and the linear compression unit, respectively; and a plurality of buffers provided at part of the spring seats to absorb shock caused by relative movement between the spring seats and the supporting springs. 
   Preferably, the spring seats may include: shell spring seats provided at the shell to fix one end of each supporting spring; and compression unit spring seats provided at the linear compression unit to fix the other end of the supporting spring; and the buffers are provided at the shell spring seats, respectively, to absorb shock transmitted to the shell. 
   Preferably, each of the shell spring seats may include: a shell coupling portion coupled to the shell; and a spring coupling portion formed around an outer circumference of the shell coupling portion to be spaced apart from the shell coupling portion by a predetermined distance, the spring coupling portion being coupled to the supporting spring. 
   Preferably, each of the buffers may be interposed between the shell coupling portion and the spring coupling portion of each shell spring seat, and is adapted to absorb shock transmitted from the spring coupling portion to the shell coupling portion. 
   Preferably, the buffer may include: a cylindrical portion configured to be fitted to an outer circumference of the shell coupling portion; and a flange portion protruding radially from a lower end of the cylindrical portion to come into contact with the shell. 
   Preferably, the cylindrical portion may be provided at an upper end thereof with a radially protruding second holding portion to prevent separation of the spring coupling portion. 
   Preferably, the buffer may be a plate spring assembly having a ring shape to be fitted to the outer circumference of the shell coupling portion. 
   Preferably, the plate spring assembly may include: a lower plate spring disposed at the lower end of the shell coupling portion to elastically support a lower end of the spring coupling portion; and an upper plate spring disposed at the upper end of the shell coupling portion to elastically support an upper end of the spring coupling portion. 
   Preferably, the lower or upper plate spring may include: a lower or upper first conical portion having an inclination suitable to absorb the vertical vibration of the spring coupling portion; and a lower or upper second conical portion bent from an inner circumference of the lower or upper first conical portion and having an inclination suitable to absorb horizontal vibration of the spring coupling portion. 
   Preferably, the shell coupling portion may be provided at the upper end thereof with a first holding portion to prevent both the buffer and the spring coupling portion from being separated upwardly from the shell coupling portion. 
   The linear compressor according to the present invention is configured such that each shell spring seat includes the shell coupling portion and the spring coupling portion, and the buffer is interposed between the shell coupling portion and the spring coupling portion to absorb vibration, thereby preventing vibration from being transmitted from the spring coupling portion to the shell coupling portion. This consequently prevents noise discharge to the outside of the shell. 
   Further, the buffer is fitted around the outer circumference of the shell coupling portion, and in turn, the spring coupling portion is fitted around the outer circumference of the buffer. This simplified structure facilitates assembly of the buffer. 
   Furthermore, with the use of the compressed holding portion formed at the upper end of the shell coupling portion, there is no risk of separation of the buffer and the spring coupling portion from the shell coupling portion. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a longitudinal sectional view of a conventional linear compressor; 
       FIG. 2  is a longitudinal sectional view illustrating a linear compressor according to a first embodiment of the present invention; 
       FIG. 3  is an enlarged sectional view illustrating a spring seat of the linear compressor according to the first embodiment of the present invention; and 
       FIG. 4  is an enlarged sectional view illustrating a spring seat of the linear compressor according to a second embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Now, preferred embodiments of the present invention will be described with reference to the accompanying drawings. 
     FIG. 2  is a longitudinal sectional view illustrating a linear compressor according to a first embodiment of the present invention.  FIG. 3  is an enlarged sectional view illustrating a spring seat of the linear compressor according to the first embodiment of the present invention. 
   As shown in  FIGS. 2 and 3 , the linear compressor according to the first embodiment of the present invention comprises a shell  50 , and a linear compression unit  51  mounted in the shell  50  and adapted to compress fluid using a linear driving force from a linear motor  60 . 
   A fluid suction pipe  52  is penetrated through one side of the shell  50 , and a fluid discharge pipe  53  is also penetrated through the other side of the shell  50 . 
   The linear compression unit  51  includes a cylinder block  55  centrally provided with a cylinder  54 , a back cover  57  having a fluid suction port  56  positioned to face the suction pipe  52 , a piston  58  inserted in the cylinder  54  to be linearly reciprocated inside the cylinder  54 , the linear motor  60  to generate a driving force required to linearly reciprocate the piston  58  inside the cylinder  54 , and a discharge unit  59  provided at a front side of the cylinder  54  to discharge compressed fluid from the cylinder  54 . 
   The linear motor  60  is basically comprised of a stator and a mover. The stator includes an outer stator  61 , an inner stator  62 , and a coil  63  to produce a magnetic field. The mover includes a magnet  64  to linearly reciprocate using a magnetic force generated in the vicinity of the coil  63 , and a magnet frame  65  to support the magnet  64  mounted thereon. 
   Here, a stator cover  66  is affixed to the outer stator  61 . 
   The piston  58  is affixed to the magnet frame  65  to receive a linear movement force of the magnet  64 . For this, the piston  18  is formed at a rear end thereof with a flange portion  67  to be affixed to a front surface of the magnet frame  65 . To a rear surface of the magnet frame  65  is coupled a spring support  68 , which cooperates with the piston  58 . 
   The spring support  68  is provided with a plurality of main springs to elastically support the piston  58  upon reciprocation of the piston  58 . 
   The linear compressor further comprises a plurality of supporting springs  70  mounted between the shell  50  and the linear compression unit  51  to support the linear compression unit  51  in a shock-absorbing manner, spring seats to affix both ends of each supporting spring  70  to both the shell  50  and the linear compression unit  51 , and buffers  80  provided at some of the spring seats to absorb vibration caused by relative movement between the spring seats and the supporting springs  70 . 
   The plurality of supporting springs  70  include a first supporting spring  71  interposed between the cylinder block  55  and the shell  50 , and a second supporting spring  72  interposed between the spring support  68  and the shell  50 . 
   The spring seats include shell spring seats  73  provided at the shell  50  to fix one end of each supporting spring  70 , respectively, and compression unit spring seats  74  provided at the linear compression unit  51  to fix the other end of the supporting spring  70 , respectively. 
   Specifically, the compression unit spring seats  74  are provided at the cylinder block  55  or spring support  68 . 
   Meanwhile, the buffers  80  are provided at the respective shell spring seats  73  to absorb vibration transmitted from the shell spring seats  73  to the shell  50 . 
   As shown in  FIG. 3 , each of the shell spring seats  73  includes a shell coupling portion  75  coupled to the shell  50 , and a spring coupling portion  76  formed around an outer circumference of the shell coupling portion  75  to be spaced apart therefrom by a predetermined distance. The spring coupling portion  76  is coupled to one of the supporting springs  70 . 
   The shell coupling portion  75  has a cylindrical shape, and is affixed at a lower end thereof to the shell  50  by welding or adhesion. 
   The spring coupling portion  75  is divided into a fitting portion  76   a  configured to face the outer circumference of the shell coupling portion  75  to be fitted to an inner circumference of the supporting spring  70 , and a seating portion  76   b  protruding radially from a lower end of the fitting portion  76   a  to support an end of the supporting spring  70  placed thereon. 
   Each buffer  80  is interposed between the shell coupling portion  75  and the spring coupling portion  76  to absorb shock generated therebetween. 
   The buffer  80  includes a cylindrical portion  80   a  configured to be fitted to the outer circumference of the shell coupling portion  75 , and a flange portion  80   b  protruding radially from an end of the cylindrical portion  80   a  to come into contact with the shell  50 . 
   The spring coupling portion  76  is fitted to an outer circumference of the cylindrical portion  80   a  so that it is seated at an upper surface of the flange portion  80   b  rather than coming into direct contact with the shell  50 . 
   The buffer  80  is preferably made of an elastic material, such as rubber. 
   The shell coupling portion  75  is provided with a first holding portion  75   a  to prevent both the buffer  80  and the spring coupling portion  76  from being separated upwardly from the shell coupling portion  75 . 
   That is, the first holding portion  75   a  protrudes radially from an upper end of the shell coupling portion  75 . 
   The first holding portion  75   a  is formed by compressing the upper end of the shell coupling portion  75  after the buffer  80  and the spring coupling portion  76  are fitted around the shell coupling portion  75 . 
   Upon compression of the first holding portion  75   a , an upper end of the cylindrical portion  80   a  is simultaneously compressed, forming a radially protruding second holding portion  80   c  which serves to prevent upward separation of the spring coupling portion  76 . 
   Now, the operation of the linear compressor according to the first embodiment of the present invention configured as stated above will be explained. 
   First, if the linear motor  60  is driven, the magnet  64  is linearly reciprocated. As the linear reciprocating movement of the magnet  64  is transmitted to the piston  58  via the magnet frame  65 , causing the piston  58  to linearly reciprocate inside the cylinder  54 . 
   According to the linear reciprocating movement of the piston  58 , fluid inside the shell  50  is introduced into the cylinder  54  through the fluid suction port  56  of the back cover  57  to thereby be compressed in the cylinder  54  by means of the piston  58 . The resulting compressed fluid is discharged to the outside of the shell  50  through the discharge unit  58  and the discharge pipe  53 . 
   Meanwhile, vibration generated in the linear compression unit  51  is absorbed by the supporting springs  70 . 
   If excess vibration is generated in the linear compression unit  51 , relative movement is inevitably generated between the supporting springs  70  and the spring coupling portions  76  to thereby generate frictional vibration. However, according to the present invention, the buffers  80  effectively absorb the vibration, thereby preventing the vibration from being transmitted from the spring coupling portions  76  to the shell coupling portions  75 . 
   This consequently prevents the vibration from being transmitted to the shell  50  via the shell coupling portions  75 , resulting in no noise discharge to the outside of the linear compressor. 
     FIG. 4  is an enlarged sectional view illustrating a spring seat of the linear compressor according to a second embodiment of the present invention. 
   The linear compressor according to the second embodiment of the present invention is similar to that of the first embodiment in general configuration and operation except that each buffer, fitted to the outer circumference of one of the shell coupling portions  75 , takes the form of a plate spring assembly  90  having a ring shape. Thus, a detailed description of the linear compressor according to the present embodiment will be omitted, and the same reference numerals are used to denote identical parts. 
   Each plate spring assembly  90  includes a lower plate spring  91  disposed at a lower end of the shell coupling portion  75  to elastically support a lower end of the spring coupling portion  76 , and an upper plate spring  92  disposed at an upper end of the shell coupling portion  75  to elastically support an upper end of the spring coupling portion  76 . 
   The lower plate spring  91  has a lower first conical portion  91   a  having an inclination suitable to absorb vertical vibration of the spring coupling portion  76 , and a lower second conical portion  91   b  bent from an inner circumference of the lower first conical portion  91   a  and having an inclination suitable to absorb horizontal vibration of the spring coupling portion  76 . 
   The lower first conical portion  91   a  is located between the lower end of the spring coupling portion  76  and the shell  50 , and the lower second conical portion  91   b  is located between the inner circumference of the spring coupling portion  76  and the outer circumference of the shell coupling portion  75 . 
   The upper plate spring  92  has an upper first conical portion  92   a  having an inclination suitable to absorb vertical vibration of the spring coupling portion  76 , and an upper second conical portion  92   b  bent from an inner circumference of the upper first conical portion  92   a  and having an inclination suitable to absorb horizontal vibration of the spring coupling portion  76 . 
   The upper first conical portion  92   a  is located between the holding portion  75   a  of the shell coupling portion  75  and an upper end of the spring coupling portion  76 , and the upper second conical portion  92   b  is located between the inner circumference of the spring coupling portion  76  and the outer circumference of the shell coupling portion  75 . 
   As is apparent from the above description, the linear compressor according to the present invention configured as stated above has the following effects. 
   Firstly, the linear compressor according to the present invention is configured such that each shell spring seat includes a shell coupling portion and a spring coupling portion, and a buffer is interposed between the shell coupling portion and the spring coupling portion to absorb vibration, thereby preventing vibration from being transmitted from the spring coupling portion to the shell coupling portion. This consequently prevents noise discharge to the outside of the shell. 
   Secondly, according to the present invention, a buffer is fitted around the outer circumference of the shell coupling portion, and in turn, the spring coupling portion is fitted around the outer circumference of the buffer. This simplified structure facilitates assembly of the buffer. 
   Thirdly, with the use of a compressed holding portion formed at an upper end of the shell coupling portion, there is no risk of separation of the buffer and the spring coupling portion from the shell coupling portion. 
   Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.