Patent Publication Number: US-8109740-B2

Title: Mounting structure of linear compressor

Description:
This application claims priority to international application No. PCT/KR2007/000267 filed on Jan. 16, 2007 which claims priority to Korean Application No. 10-2006-0004639 filed Jan. 16, 2006, both of which are incorporated by reference, as if fully set forth herein. 
     TECHNICAL FIELD 
     The present invention relates to a mounting structure of a linear compressor in which a cylinder, a piston and a linear motor are installed between a frame and a motor cover, and more particularly, to a mounting structure of a linear compressor which can allow a motor terminal for supplying power to a linear motor to be taken out without interference with the other components, reduce assembly deformation by forming a frame and a motor cover in a symmetric shape, and stably support the linear motor. 
     BACKGROUND ART 
       FIG. 1  is a side-sectional view illustrating a part of a usual linear compressor, and  FIG. 2  is a disassembled perspective view illustrating a frame and a motor cover of the conventional linear compressor. 
     Referring to  FIG. 1 , in the usual linear compressor, one end of a piston  4  is inserted into a cylinder  2 , for forming a compression space P, and a linear motor  10  including an inner stator  12 , an outer stator  14  and a permanent magnet  16  linearly reciprocates the piston  4  by a mutual electromagnetic force, thereby a refrigerant is sucked into the compression space P, and compressed and discharged. 
     The structure comprising the cylinder  2 , the piston  4  and the linear motor  10  is installed in a shell (not shown) which is a hermetic space, and elastically supported by buffering springs (not shown). A suction valve  6  is installed on a suction hole  4   h  formed at one end of the piston  4  to communicate with the compression space P. A discharge valve assembly  8  in which a discharge valve  8   a  is elastically supported by a discharge valve spring  8   c  inside a discharge cap  8   b  to be opened and closed is installed at one end of the cylinder  2 . Accordingly, suction and discharge of the refrigerant are controlled according to a pressure inside the compression space P. 
     One end of the cylinder  2  is fixed to the frame  20 . The inner stator  12  is fixedly installed on the outer circumference of the cylinder  2 . The outer stator  14  is bolt-fastened between the frame  20  and the motor cover  30  with an interval from the outer circumference of the inner stator  12 . The permanent magnet  16  is installed between the inner stator  12  and the outer stator  14  with an interval, and connected to the other end of the piston  4 . 
     A supporter (not shown) connected to the other end of the piston  4  is elastically supported in the notion direction by a plurality of springs (not shown) between the motor cover  30  and a main body cover (not shown) installed with an interval from the motor cover  30  in the motion direction. 
     Accordingly, the cylinder  2 , the inner stator  12 , the outer stator  14 , the frame  20 , the motor cover  30  and the main body cover are fixed, and the piston  4 , the permanent magnet  16  and the supporter are linearly reciprocated. As the pressure inside the compression space P is varied, the refrigerant is sucked into the compression space P, compressed, and discharged. 
     As shown in  FIG. 2 , the frame  20  is formed in a flat plate shape. A cylinder mounting hole  24  through which the cylinder  2  is installed is formed at the frame  20 . A motor terminal taking out hole  26  is formed at one side of the frame  20 , so that a motor terminal (not shown) connected to a coil winding body (not shown) of the outer stator  14  can be taken out through the motor terminal taking out hole  26 . 
     Since an interval between the frame  20  and the shell (not shown) is small, the motor terminal taking out hole  26  is formed on the side surface of the frame  20  to take out the motor terminal. Therefore, even if vibration is generated, this configuration prevents an electric wire connected to the motor terminal frame being damaged in contact with the shell (not shown) and the frame  20 . 
     The portion around the motor terminal taking out hole  26  of the frame  20  is formed thick for stably supporting the outer stator  14 , even though the motor terminal taking out hole  26  is formed at one side of the frame  20 . 
     Except the surface  22  of the frame  20  for supporting the outer stator  14 , an unnecessary portion of the frame  20  is removed to reduce the whole volume of the frame  20 . In addition, four bolt holes  22   h  are formed on the frame  20  so that the motor cover  30  can be bolt-fastened to the frame  20 . Accordingly, protruding units  22   a  and  22   b  are protruded from the frame  20  to secure spaces for forming the bolt holes  22   h.    
     Meanwhile, the motor cover  30  is formed in a metal plate shape. One surface  32  of the motor cover  30  supports the outer stator  14 . Bolt holes  32   h  are formed on the motor cover  30  to correspond to the bolt holes  22   h  of the frame  20 , so that the motor cover  30  can be bolt-fastened to the frame  20 . 
     Preferably, a through hole  34  is formed at the center portion of the motor cover  30 , so that the other end of the piston  4  can pass through the through hole  34  for linear reciprocation. 
     The frame  20  and the motor cover  30  are positioned on the same axle. The motor cover  30  is bolt-fastened to the frame  20  in the motion direction of the piston  4 , for supporting and fixing the outer stator  14 . The motor terminal is taken out through the motor terminal taking out hole  26  of the frame  20 , and connected to a power supply source. 
     However, in the conventional mounting structure of the linear compressor, since the motor terminal taking out hole  26  is formed at one side of the frame  20  to take out the motor terminal, the frame  20  is not completely symmetric. When the motor cover  30  is bolt-fastened to the frame  20 , twist deformation may occur due to the fastening force. Accordingly, the cylinder  2  installed between the frame  20  and the motor cover  30  may be deformed to cause an assembly error and an operation error. Furthermore, when the motor terminal taking out hole  26  is formed at the frame  20 , the hole-formed portion of the frame  20  must be formed relatively thick to stably support the outer stator  16 . As a result, the manufacturing process is complicated and the material cost is increased. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     An object of the present invention is to provide a mounting structure of a linear compressor which can allow take out a motor terminal to be taken out for supplying power to a linear motor without interference with the other components, prevent assembly deformation by forming a frame and a motor cover in a symmetric shape, and stably support the linear motor. 
     Technical Solution 
     There is provided a mounting structure of a linear compressor comprising: a cylinder for providing a space for compressing a refrigerant; a piston reciprocated inside the cylinder, for compressing the refrigerant; a linear motor including a motor cover and operating the piston; and a frame to which one end of the cylinder is fixed and the motor cover is bolt-fastened, the frame being left-right symmetric or up-down symmetric. By this configuration, the fastening force is uniformly distributed on the frame, thereby minimizing twisting of the frame in assembly. 
     In another aspect of the present compressor, the frame and the motor cover include corresponding bolt holes, and the bolt holes are up-down symmetric and left-right symmetric. By this configuration, when the frame and the motor cover are fastened by the bolts passing through the bolt holes, respectively, the fastening force is evenly dispersed on the frame and the motor cover, thereby minimizing twisting of the frame and the motor cover. 
     In another aspect of the present invention, the motor cover is up-down symmetric and left-right symmetric. 
     In another aspect of the present invention, the mounting structure of the linear compressor includes a motor terminal taken out through the lower portions of the motor cover and the frame. By this configuration, the motor terminal taking out hole is not formed on the motor cover, thereby evenly dispersing the force applied to the motor cover. In addition, this configuration can omit a complicated process of increasing the thickness of the peripheral region of the motor terminal taking out hole to offset reduction of the strength in the region. 
     In another aspect of the present invention, the motor cover includes a pair of protrusion units which are left-right symmetric, and bolt holes for bolt-fastening the rotor cover to the frame are formed on the protrusion units. By this configuration, the spaces for forming the bolt holes can be prepared without increasing the size of the motor cover. 
     In another aspect of the present invention, the motor cover is formed in any one of a circular shape and an elliptical shape. By this configuration, the bolt fastening force can be uniformly distributed on the whole surface of the motor cover. 
     In another aspect of the present invention, the linear motor includes an inner stator, an outer stator and a permanent magnet, and the outer stator includes a coil winding body and a plurality of core blocks. And the mounting structure of the linear compressor further includes a motor terminal installed in the space between the core blocks. 
     In another aspect of the present invention, the rotor terminal is connected to the coil winding body between the core blocks, and inclined at an angle to a normal line direction of the coil winding body in the connection point. By this configuration, an electric wire connected to the rotor terminal can be taken out through the side surface of the lower structure of the frame without interfering with the lower structure of the frame. 
     In another aspect of the present invention, the length from the coil winding body to the end of the motor terminal is shorter than the length from the coil winding body to the ends of the core blocks. This configuration serves to prevent an impact applied from a shell to the motor terminal. 
     In another aspect of the present invention, the mounting structure of the linear compressor further comprises a shell; support springs for supporting a main body frame inside the shell; a terminal for supplying power to the linear compressor; and an electric wire for connecting the rotor terminal to the terminal. The end of the rotor terminal is placed at a distance from the bottom of the shell, and the electric wire is taken out between the support springs and connected to the terminal. By this configuration, the electric wire can be connected to the terminal without interfering with the other structures of the linear compressor. 
     Advantageous Effects 
     In accordance with the present invention, in the mounting structure of the linear compressor, the frame is formed in a closed loop shape to be left-right symmetric with the motor cover, and the motor terminal for supplying power to the linear motor is taken out through the relatively large space under the frame without interfering with the other peripheral components. In a state where the cylinder, the piston and the linear motor are mounted between the frame and the rotor, even though the frame and the motor cover are bolt-fastened to each other, deformation by the fastening force is prevented to improve assembly efficiency and operation reliability. As the frame is formed in the closed loop shape, it can stably support the linear motor. Furthermore, the whole manufacturing process can be simplified by emitting the motor terminal taking out hole. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side-sectional view illustrating a part of a conventional linear compressor; 
         FIG. 2  is a disassembled perspective view illustrating a frame and a motor cover of the conventional linear compressor; 
         FIG. 3  is a disassembled perspective view illustrating a frame and a motor cover of a linear compressor in accordance with the present invention; 
         FIG. 4  is a perspective view illustrating a state in which a motor terminal is taken out of the linear compressor in accordance with the present invention; and 
         FIG. 5  is a structure view illustrating a state in which the motor terminal is connected to a linear motor of the linear compressor in accordance with the present invention. 
     
    
    
     MODE FOR THE INVENTION 
     The present invention will now be described in detail with reference to the accompanying drawings. 
       FIG. 3  is a disassembled perspective view illustrating a frame and a motor cover of the linear compressor in accordance with the present invention,  FIG. 4  is a perspective view illustrating the linear compressor in accordance with the present invention, and  FIG. 5  is a structure view illustrating an outer stator of a linear motor in accordance with the present invention. In the following description, the same reference numerals are used for the same elements as those of  FIG. 1 . Since a cylinder  2 , a piston  4 , a linear motor  10  and a motor cover  30  are identical to the conventional ones, detailed explanations thereof are omitted. As illustrated in  FIGS. 3 to 5 , in the mounting structure of the linear compressor, the cylinder  2 , the piston  4  and the linear motor  10  are fixedly installed between the frame  50  and the motor cover  30  which are left-right symmetric. The linear motor  10  includes an inner stator  12 , an outer stator  14  and a permanent magnet  16 . The outer stator  14  includes a coil winding body  14   a  and core blocks  14   b . Power is supplied to the coil winding body  14   a  through a motor terminal  60  connected to the coil winding body  14   a , so that the coil winding body  14   a  can generate a mutual electromagnetic force. An electric wire  60   a  of the motor terminal  60  is taken out through a space under the frame  50 , and connected to a terminal  77  installed on a shell  51 . Therefore, the electric wire  60   a  does not interfere with the adjacent components. 
     The frame  50  forms a kind of closed loop. The outer stator  14  is stably supported in the axial direction on one surface  52  of the frame  50 . A cylinder mounting hole  54  is formed at the center portion of the frame  50 , so that the cylinder  2  can pass through the cylinder mounting hole  54 . 
     Four bolt holes  52   h  for bolt-fastening the motor cover  30  to the frame  50  are formed at the frame  50  to be up-down symmetric and left-right symmetric. The smaller the volume of the frame  50  is, the more an eddy current loss is reduced. As the frame  50  is smaller than the motor cover  30 , it may not have sufficient spaces for forming the bolt holes  52   h . In order to obtain the spaces for forming the bolt holes  52   h , a pair of protrusion units  52   a  and  52   b  are formed on the frame  50  to be left-right symmetric. 
     One end of the cylinder  2  is inserted into the cylinder mounting hole  54  of the frame  50 . A discharge valve assembly  8  is mounted on one end of the cylinder  2 . The inner stator  12  is fixed to the outer circumference of the cylinder  2 , and the outer stator  14  is fixed to the inner stator with a interval in the radial direction. In a state where one end of the outer stator  14  is supported by the frame  50  and the other end thereof is supported by the motor cover  30 , the motor cover  30  is bolt-fastened to the frame  50 . 
     A suction valve  6  is mounted on one end of the piston  4 , and the permanent magnet  16  is connected to the other end of the piston  4 . One end of the piston  4  is inserted into the cylinder  2 , for forming a compression space P in the cylinder  2 . The permanent magnet  16  is installed between the inner stator  12  and the outer stator  14  with a gap. 
     The structure comprising the cylinder  2 , the piston  4 , the linear motor  10 , the frame  50  and the motor cover  30  is supported by buffering springs  55  in the shell  51  and installed on the bottom surface of the shell  51 . 
     The terminal  77  is installed at the shell  51 , for supplying external power to the linear motor  10  of the linear compressor. Normally, the terminal  77  includes pins. The electric wire  60   a  is connected between the linear motor  10  and the terminal  77 , for supplying power to the linear motor  10 . 
     The outer stator  14  includes the coil winding body  14   a  formed by winding a coil in the circumferential direction, and the pair of core blocks  14   b  formed by laminating a plurality of laminations, and disposed on the coil winding body  14   a  at intervals in the circumferential direction. The piston  4  is driven by the mutual electromagnetic force induced by the coil winding body  14   a . It is thus necessary to install the motor terminal  60  for supplying power to the coil winding body  14   a . In addition, the motor terminal  60  is connected to the terminal  77  through the electric wire  60   a , for supplying power to the outer stator  14 . 
     When the motor terminal  60  is connected to the coil winding body  14   a  of the outer stator  14 , the motor terminal  60  is inclined at an angle to a normal line direction of the coil winding body  14   a  in the connection point. Accordingly, the electric wire  60   a  is not interfered by the structure disposed at the bottom end of the frame  50 . On the other hand, the motor terminal  60  is disposed between the core blocks  14   b  of the outer stator  14 . Preferably, the angle of the motor terminal  60  is determined so that the electric wire  60   a  does not contact one side of the core blocks  14   b.    
     The electric wire  60   a  of the motor terminal  60  taken out through the space under the frame  50  is connected to the terminal  77  fixed to the inner wall of the shell  51 . The terminal  77  is connected to a control box (not shown), for controlling power supply. 
     As discussed earlier, in accordance with the present invention, the hole for taking out the motor terminal  60  is not formed on the frame  50 , so that the frame  50  can form a relatively narrow closed loop which is left-right symmetric. As a result, when the motor cover  30  is bolt-fastened to the frame  50  to generate the fastening force, even though the frame  50  is thin, the left-right symmetry of the frame  50  serves to reduce fastening deformation and stably support the outer stator  14 . 
     Although the preferred embodiments of the present invention have been described, it is understood that the present invention should not be limited to these preferred embodiments but various changes and modifications can be made by one skilled in the art within the spirit and scope of the present invention as hereinafter claimed.