KR101484326B1 - Linear compressor - Google Patents

Abstract

Since the linear compressor according to the present invention can secure high efficiency while meeting the demand with a low compression capacity and a small installation space, even if a small vibration occurs due to the operation of the linear motor, if the structure moves inside the hermetically sealed container, It gets easier. Accordingly, since the linear compressor of the present invention is provided with the stopper portion that can hit the hermetically sealed container at the back cover located behind the structure, which is the direction in which the refrigerant is sucked, the stopper portion of the back cover hits the hermetically sealed container, It is possible to prevent the parts from being damaged.

Linear compressor, sealed container, structure, linear motor, mechanical spring, buffer spring, back cover, stopper

Description

[0001] LINEAR COMPRESSOR [0002]

The present invention relates to a linear compressor capable of ensuring high efficiency in response to a demand for a low compression capacity and a small installation space, and more particularly to a linear compressor capable of changing the shape of a back cover To a linear compressor capable of buffering without installing additional parts.

BACKGROUND ART [0002] Generally, a reciprocating compressor is constituted such that a compression space in which a working gas is sucked and discharged is formed between a piston and a cylinder, so that the piston linearly reciprocates within the cylinder and compresses the refrigerant.

In recent years, since the reciprocating compressor includes components such as a crankshaft in order to convert the rotational force of the driving motor to the reciprocating linear motion force of the piston, there is a problem that mechanical loss due to the motion conversion is largely generated. A large number of linear compressors are being developed.

In particular, the linear compressor is directly connected to a linear motor in which the piston reciprocates linearly, so that there is no mechanical loss due to the switching of the motion, so that the compression efficiency is improved and the structure is simple. Since the operation can be controlled, the noise is smaller than that of other compressors, and thus it is widely applied to home appliances such as refrigerators used indoors.

1 is a plan sectional view showing an example of a linear compressor according to the prior art.

1, the conventional linear compressor includes a frame 2, a cylinder 3, a piston 4, a suction valve 5, a discharge valve assembly 6, a motor cover (not shown) 7, the supporter 8, the back cover 9, the muffler assembly 10, the eight springs 20, and the linear motor 30 are elastically supported. Of course, the closed container 1 is provided with a suction pipe 1a through which refrigerant is sucked and a discharge pipe 1b through which the compressed refrigerant is discharged.

The springs 20 are installed such that the piston 4 is elastically supported in the axial direction so that four first springs 21 are installed between the motor cover 7 and the supporter 8, (22) is provided between the supporter (8) and the back cover (9). Therefore, when the piston 4 moves in the direction of compressing the refrigerant, the first springs 21 compress and elastically support the piston 4. On the other hand, when the piston 4 moves in the direction of sucking the refrigerant, The second springs 22 are compressed and the piston 4 is elastically supported.

The linear motor 30 is provided so as to maintain an air gap between the inner stator 31 and the outer stator 32 and to allow the permanent magnet 33 to reciprocate linearly therebetween. The permanent magnet 33 Is connected to the piston 4 by the connecting member 34, and reciprocally drives the piston 4. The inner stator 31 is formed in a cylindrical shape in which the lamination is laminated in the circumferential direction. The inner stator 31 is fitted in the outer peripheral surface of the cylinder 3 so that one axial end of the inner stator 31 abuts on one surface of the frame 2, (Not shown). The outer stator 32 is coupled to the coil winding body at a predetermined interval in the circumferential direction at a predetermined interval. The core is installed to surround the outer circumferential surface of the coil winding body, Respectively. Of course, the outer stator 32 is installed so as to maintain a clearance with the outer circumferential surface of the inner stator 31. The outer stator 32 is positioned so as to abut the frame 2 and the motor cover 7 in the axial direction, (7) is bolted to the frame (2). The permanent magnet 33 is provided so that the poles NS are located on the surface facing the inner stator 31 and the surface facing the outer stator 32 and the connecting member 34 And is connected to the piston (4). Therefore, the permanent magnet 33 reciprocates linearly by the mutual electromagnetic force between the inner stator 31, the outer stator 32 and the permanent magnet 33 to operate the piston 4.

Therefore, the moving member composed of the piston 4 and the permanent magnet 33 moves the mechanical spring 20 from both sides with respect to the linear motion direction with respect to the fixed member composed of the cylinder 3 and the stator 31, The MK resonance frequency defined by the mass M of the moving member and the spring constant K of the springs supporting the mass M is calculated and the power frequency applied to the linear motor 30 is set to By designing to follow the MK resonant frequency, the efficiency of the linear compressor can be optimized.

Hereinafter, the operation of the conventional art will be described.

When the power is input to the coil winding hull, the inner stator 31 and the outer stator 32 are ignited alternately with the N / S poles, and the permanent magnet 33 positioned therebetween is interposed between the inner stator 31 and the outer stator 32, And reciprocating linear motion is performed by moving by attraction or repulsion according to the pole change of the rotor 32. At this time, if the center of the permanent magnet 33 deviates from the ends of the two poles of the outer stator 32, the permanent magnet 33 will not be attracted by the attraction force or the external divergence of the electromagnetic field will become large, 31 or the outer stator 32 or the electromagnetic field radiated to the outside of the hermetically sealed container 1 or other components in the hermetically sealed container 1, the operation reliability is lowered. To prevent this, the piston 4), that is, the moving distance of the permanent magnet 33, has been strictly limited to the two pole ends of the outer stator 32 by the center of the permanent magnet 33. For this purpose, a plurality of Mechanical springs have been used to elastically support the moving member as shown in Fig.

When the linear motor 30 is operated as described above, the piston 3 and the muffler assembly 10 connected thereto are linearly reciprocated, and as the pressure in the compression space P changes, the suction valve 5 and the discharge valve assembly The refrigerant flows through the suction holes 1a of the hermetically sealed container 1, the openings of the back cover 9, the muffler assembly 10 and the piston 3, P and is then discharged to the outside through the discharge valve assembly 6, the loop pipe (not shown) and the discharge pipe 1b of the closed container 1. [

Recent linear compressors are being developed not only to be easily applied to low capacity but also to be easily installed in a small space. In the conventional linear compressor and the linear motor applied thereto, the stroke length of the piston 4 is set at a distance that the center of the permanent magnet 33 moves reciprocatingly linearly between the two poles of the outer stator 32, And is not suitable for use in a simple structure of a low capacity because it uses a plurality of springs 20 for this purpose.

Since the components other than the hermetically sealed container 1 are assembled into an assembly with one structure and the assembly is supported by the hermetically sealed container 1 by a plurality of buffer springs (not shown) When vibration or vibration occurs due to operation or external impact, the assembly collides with the closed container 1 while moving. At this time, the stopper 40 is mounted on the inner side surface of the closed container 1. Even if the structure moves, the impact can be buffered by colliding with the stopper 40, so that the internal parts of the structure can be prevented from being directly damaged.

However, since the recently developed linear compressor is developed to be easily installed even in a narrow space, the size of the closed container 1 is reduced, so that a space for mounting the stopper 40 in the closed container 1 can be secured There is a difficult problem. Therefore, when the stopper 40 is removed, the back cover 107 located at the outermost portion of the structure can be directly hit against the closed container 101. Since the back cover 107 has a shape in which the plate is bent at right angles, There is a problem in that the edge of the back cover 107 which keeps the distance is deformed by colliding with the hermetically sealed container or the impact is transmitted to the structure, the alignment of the parts may be broken and the operational reliability is lowered.

An object of the present invention is to provide a linear compressor capable of increasing the efficiency by using a magnetic spring constant, by making the linear motor structure change, by integrating or eliminating the component parts to make it lighter or smaller.

Another object of the present invention is to provide a linear compressor capable of preventing the deformation of a back cover without changing the shape of a back cover even if the structure is shock-absorbed and collapsed with vibration.

According to an aspect of the present invention, there is provided an air conditioner comprising: a sealed container in which a refrigerant is sucked / discharged; A cylinder accommodated in the hermetically sealed container and provided with a compression space therein; A frame having one end fixed to the cylinder; A piston having one end inserted into the cylinder; A linear motor reciprocatingly driving the piston; A motor cover for axially fixing the linear motor to the frame; At least two mechanical springs supporting the piston axially on both sides; A plurality of buffer springs for resiliently supporting the structure in which the parts are assembled except the hermetically sealed container inside the hermetically sealed container; And a back cover coupled to the motor cover and having a cap-shaped stopper portion protruding in the direction of the hermetically sealed container so that one mechanical spring is seated and collides with the hermetically sealed container by vibration, Lt; / RTI >

Further, in the present invention, the stopper portion is formed in the shape of a circular cap at the center of the back cover.

Further, in the present invention, the stopper portion is characterized by having rounded corners.

Further, in the present invention, the stopper portion is characterized in that the plate material is press-formed.

Further, in the present invention, the back cover includes a pair of mounting portions bolted to be symmetrical to the outer circumferential portion of the motor cover, a pair of planar connecting portions extending straight from the mounting portions in the axial direction, And a circular cap-shaped stopper portion protruding axially between the curved surface connecting portions.

Further, in the present invention, the linear motor includes an inner stator provided outside the cylinder, an outer stator provided so as to have a pole between the inner stator and the gap between the inner stator and the stator, Wherein when the plurality of permanent magnets reciprocate linearly in the gap between the inner stator and the outer stator, at the top dead center and the bottom dead point, at least one permanent magnet And a gap space portion between the inner stator and the pole of the outer stator is released.

Further, in the present invention, the mass M of the movable member including the piston and the permanent magnet, the mechanical spring constant K _mechanical defined by the restoring force of the springs, the gas spring constant defined by the operating fluid pressure in the compression space K _gas ), by a magnetic spring constant (K _magnet ) defined by the restoring force that one pole center of the permanent magnet coincides with the pole center of the outer stator during reciprocating linear motion in the gap between the inner stator and the outer stator And is operated using the defined resonance frequency (f _o ).

Further, in the present invention, the mechanical springs consist of a first spring provided between the cylinder and the piston flange, and a second spring provided between the piston flange and the stopper portion of the back cover, and the diameter, And the mechanical spring constant is reduced as the magnetic spring constant increases.

In the linear compressor of the present invention constructed as described above, a linear motor in which two permanent magnets connected in the direction of motion between one pole of the inner stator and one pole of the outer stator reciprocates linearly is employed, and a linear compressor employing such a linear motor Since the mechanical spring constant (K _mechanical ) can be designed to be low by designing the resonance frequency in consideration of the magnetic spring constant (K _magnet ), only two springs can be configured to support the piston, Since the spring directly supports the piston elastically, it is possible to omit the supporter or to simplify the shape of the motor cover, which is advantageous in that the capacity, weight and size can be reduced.

In the linear compressor according to the present invention, even if the hermetically sealed container is small, when the structure moves, the stopper protruding in the shape of a circular cap on the back cover located on the outer surface of the structure collides with the hermetically sealed container, Aling can be prevented, and reliability of operation can be ensured. Furthermore, the buffering effect can be enhanced without any additional parts, thereby reducing the material cost.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a plan view showing an example of a linear compressor according to the present invention, and FIG. 3 is a side sectional view showing an example of a structure of a linear compressor according to the present invention.

2 and 3, the linear compressor according to the present invention includes a hermetically sealed container 101 having a suction pipe 101a and a discharge pipe 101b through which a refrigerant is sucked / discharged, The valve assembly 100 includes a frame 102, a cylinder 103, a piston 104, a suction valve 105 and a discharge valve assembly 106, a motor cover 107, a back cover 108, a suction muffler 110, 120: 121, 122) and the linear motor 130 are elastically supported.

The frame 102 and the cylinder 103 are integrally formed. However, the frame 102 and the cylinder 103 may be formed of a magnetic material due to the characteristics of the linear motor 130 according to the present invention. That is, in the conventional linear compressor, as described above, there are two pawls in the linear motor, and since the magnetic flux leaks through the gap existing in the pole on the cylinder side, the frame is magnetized and therefore one of the frame, cylinder, Should be made of a non-magnetic material such as aluminum. However, in the linear motor 130 according to the present invention, the inner stator 131 and the outer stator 132 of the linear motor 130 abut against each other on the side of the frame 102 and the cylinder 103 It is not necessary to form the frame 102 or the cylinder 103 as a nonmagnetic material and the frame 102 and the cylinder 103 are made of cast iron or the like because there is no fear that the magnetic flux leaks to the outside as a closed loop is formed therebetween. Can be integrally cast.

The cylinder 103 is formed in a cylindrical shape in which the compression space P can be provided. Since the stroke length of the piston is shorter than that of the conventional linear compressor, the cylinder 103 is formed shorter in the axial direction than the conventional cylinder. Is shorter than the axial length of the stator (131, 132) of the linear motor (130).

The piston 104 has a head 104a provided at a closed end of the cylinder and provided with a suction port 104h for sucking the refrigerant into the compression space P, And a portion 104b. In order to prevent leakage of the magnetic force from the linear motor 130, a part of the linear motor 130 may be made of a non-magnetic material. This is because a pole exists in the linear motor 130 according to the present invention toward the flange portion 104b of the piston 104 as will be described later. The magnetic flux leaking through the gap of the pole causes the magnetic member It is because it magnetizes. The head portion 104a of the piston 104 is installed to be inserted into the cylinder 103 and the flange portion 104b of the piston 104 is inserted into the magnet portion 133 of the linear motor 130, And is elastically supported in the axial direction by two springs 120 (121, 122).

Of course, the suction valve 105 is mounted on the head 104a of the piston 104, the discharge valve assembly 106 is mounted on one end of the compression space P of the cylinder 103, And is operated to open and close in accordance with the pressure change.

The motor cover 107 fixes the linear motor 103 to be described later to the frame 102 so that one end in the axial direction of the linear motor 130 is supported on the frame 102, The other end of the motor cover 107 is covered with the motor cover 107, and then the motor cover 107 is bolted to the frame 102. At this time, the outer stator 132 of the linear motor 130 is fixed between the actual frame 102 and the motor cover 107, and the inner stator 131 is also rotated while fixing the outer stator 132 of the linear motor 130 And can be configured to be fixed together, an example of which will be described in detail below.

The back cover 108 is formed by bending the flat plate to accommodate the flange portion 104b of the piston 104 and the suction muffler 110 and has a motor cover 107, respectively. The cap 108a of the back cover 108 may be attached to the closed container 108. The cap 108a of the back cover 108 may protrude from the closed container 108a, It is preferable that the round or the corner portion is rounded so as to serve as a stopper. Of course, the cap 108a of the back cover 108 is provided with an opening 108h for allowing the refrigerant to flow into the suction muffler 110 and is positioned on the straight line with the suction pipe 101a of the closed container 101 desirable.

The suction muffler 110 is fixed to the flange portion 104b of the piston 104 and guides various kinds of noise spaces and noise pipes so that the refrigerant is sucked up to the head portion 104a of the piston 104, (105). Of course, the suction muffler 110 may be formed of a non-magnetic material in part or in whole in order to prevent magnetic leakage of the linear motor 130.

The springs 120 include a first spring 121 supported by the end of the cylinder 103 and the flange 104b of the piston 104 and a second spring 121 supported by the flange 104b of the piston 104 and the cap And a second spring 122 which is supported by the second spring 108b. The first spring 121 is compressed when the piston 104 is moved in the direction to compress the refrigerant while the second spring 122 is compressed when the piston 104 is moved in the direction in which the refrigerant is sucked, The 1,2 springs 121 and 122 behave opposite to each other. In the linear motor 130 described below, since the value of the magnetic spring constant (K _magnet ) can have a meaning, unlike the conventional linear motor, the K _mechanical value can be made relatively small, It is possible to reduce the spring constant, that is, to reduce the total number of springs or to reduce the spring constant of the individual springs, that is, to reduce the diameter D, the diameter d and the length l of the individual springs . Accordingly, only the two springs 120 (121, 122) can be applied. Furthermore, the supporter that has been provided for installing a large number of springs in a more effective space can be omitted, or the spring support portion provided in the motor cover can be eliminated, , It can be lightened.

4 is a side cross-sectional view illustrating an example of the linear motor coupling applied to the linear compressor according to the present invention.

2 to 4, one end of the inner stator 131 and one end of the outer stator 132 in the axial direction are connected to each other, and the other part of the linear motor is maintained in a gap And the magnet portion 133 is disposed between the inner stator 131 and the outer stator 132 so as to reciprocate linearly by electromagnetic force.

The inner stator 131 may be manufactured in the form of lamination lamination in the circumferential direction as in the prior art. In order to be connected to the outer stator 132, the inner stator 131 has a connecting portion 131a extending in the radial direction on the outer circumferential surface at one end in the axial direction And a protrusion 131b having an axially extending outer peripheral surface at one end in the axial direction is provided to increase the electromagnetic force. In this case, since the inner stator 131 is formed to be longer than the axial length of the cylinder 103 (shown in Fig. 2), it is difficult for the inner stator to be fixed to the outer circumferential surface of the cylinder, And fixed by a stator 132, which will be described in detail below.

The outer stator 132 is provided so as to surround a portion of the coil winding body 132A in which the coil is wound in the circumferential direction and a portion of the coil winding body 132A except for the inner circumferential surface at regular intervals in the circumferential direction of the coil winding body 132A The core 132B is configured such that only a part of the lamination in the circumferential direction is laminated such that the side end face of the core 132B is in the shape of "┗┛". At this time, the core 132B has two ends positioned to face the connecting portion 131a and the protruding portion 131b of the inner stator 131, and one end of the core 132B has a connecting portion And a connecting portion 132a protruding in the direction of the inner stator 131 so as to overlap with the outer circumferential surface of the inner stator 131 and the protruding portion 131b of the inner stator 131 are provided at the other end of the core 132B. (132b). Further, the connecting portion 132a of the core 132B is formed so as to press the inner stator 131 by a fastening force that is formed, welded, or axially engaged with the connecting portion 131a of the inner stator 131, The ends of the inner stator 131 and the outer stator 132 are connected to each other to form a closed loop so that there is no possibility that the magnetic flux leaks from the connecting portion of the stator 131 or 132. The pawl 132b of the core 132B has a protruding portion 132b 'which is expanded in both axial directions to widen the area of the surface facing the inner stator 131 in order to increase the electromagnetic force, like the protruding portion 131b of the inner stator 131. [ ) Is preferably formed.

Of course, the core applied to the conventional outer stator is provided with two pawls. In order to increase the electromagnetic force, the area of the pawls facing the inner stator is formed to extend in the axial direction. And two laminated laminated laminated layers having a side cross-sectional shape of '┗' and '┛', respectively. Then, the two core blocks were combined with a coil winding body by using a complex joining member and a joining method The core 132B applied to the outer stator 132 of the present invention is formed of one core block laminated with laminations having a side cross-sectional shape of '┛┛' because only one pole 132b is provided, (132A), so that the manufacturing process can be simplified.

The first and second permanent magnets are connected to the inner stator 131 and the outer stator 132, respectively. The first and second permanent magnets 133 and 132 are connected to the first and second permanent magnets 131 and 132, respectively, And the pawls 132b of the first clutch C1. That is, since one end of the inner stator 131 and the outer stator 132 are connected to each other in the axial direction, an electromagnetic force is generated only between the inner stator 131 and the pole 132b of the outer stator 132, (Not shown) are connected to each other in the axial direction so that the magnet portion 133 reciprocates linearly even if the pole is changed only in one pole 132b of the magnet portion 133. However, It is preferable that the two permanent magnets are connected to each other at different poles.

The linear motor 130 is coupled between the frame 102 and the cylinder 103 and the motor cover 107. The frame 102 is provided with an inner stator 131 for determining the installation position of the inner stator 131, Is provided with a positioning groove 102h in which a part of the fixing protrusion 131a of the positioning groove 102h can be received. Of course, when the connected portions 131a and 132a of the inner stator 131 and the outer stator 132 are seated in the crystal grooves 102h of the frame 102, the frame 102 and the outer stator 132 are spaced apart from each other When the outer stator 132 is engaged with the frame 102 by the motor cover 107 and the outer stator 132 abuts against the frame 102 and the inner stator 131 is rotated with a predetermined force So that the fastening force is kept higher. Since the portions where the inner stator 131 and the outer stator 132 are connected to each other form a closed loop in this manner, even if the diathermal inner stator 131 and the outer stator 132 come into contact with the frame 102, The frame 102 and the cylinder 103 do not need to be made of a nonmagnetic material such as aluminum by injection molding or the like and can be easily formed into a casting body by a cast iron .

5A and 5B are diagrams illustrating an example of the operation of the linear motor applied to the linear compressor according to the present invention.

5A to 5B, as power is input to the coil winding body 132A, the inner stator 131 and the pole 132b of the outer stator 132 alternate with the N-S poles. 5A, when the pole 132b of the outer stator 132 has the N pole, since the S pole of the magnet portion 133 is pulled out and the N pole of the magnet portion 133 is pushed out, The magnet portion 133 moves in the uniaxial direction so that the first permanent magnet 133a is positioned between the inner stator 131 and the pawl 132b of the outer stator 132. The center of the first permanent magnet 133a, The second permanent magnet 133b moves to the extent that it does not deviate from the end of the outer protrusion 132b 'of the inner stator 132. Accordingly, as the outer protrusion 132b' of the outer stator 132 moves away from the inner stator 131, And the pawl 132b of the outer stator 132 is completely deviated from the gap space portion. 5B, when the pole 132b of the outer stator 133 has the S pole, the N pole of the magnet portion 133 is pulled out and the S pole of the magnet portion 133 is pushed out, The magnet portion 133 moves in the opposite direction so that the second permanent magnet 133b is positioned between the inner stator 131 and the pole 132b of the outer stator 132. Similarly, The first permanent magnet 133a moves away from the inner protruding end 132b 'of the outer stator 132 to the extent that the inner stator 131b does not deviate from the inner protruding end 132b' And the pawl 132b of the outer stator 132 are completely deviated from the gap space portion. That is, the moving distance of the magnet portion 133, that is, the stroke of the piston 104 is set such that the center of the first permanent magnet 133a is located at the end of the outer protruding portion 132b 'of the outer stator 132, And the center of the inner protrusion 133b is located at the end of the inner protrusion 132b 'of the outer stator 132. [

In the linear motor according to the present invention as described above, the magnet portion 133 provided with the two permanent magnets 133a and 133b is reciprocated linearly and another restoring force is applied to the magnet portion 133 of the linear motor . This is because one of the permanent magnets 133 of the magnet portion 133 is passed between the protruding portion 131b of the inner stator and the pole 132b of the outer stator as in Figures 5A and 5B, The electromagnetic striking force acts to return to the center of the pole 132b of the outer stator 132 by the electromagnetic force as the pole 132b of the outer stator 132 having the different polarity deviates from the center of the pole 132b, And the restoring force of the springs 120 supporting the moving member composed of the magnet portion 133 and the magnet portion 133. This is called a magnet spring in the present invention, What is defined is called a magnet spring constant (K _magnet ). Of course, the magnetic spring constant (K _magnet ) is set such that the center of the pole 132b of the outer stator 132 having the center of the permanent magnet of one of the magnet portions 133 is different from the center of the pole 132b of the outer stator 132 Lt; / RTI >

Therefore, in the linear compressor employing the linear motor of the present invention, since the mechanical spring constant (K _tmechanical ) is designed to be small considering the magnetic spring constant (K _magnet ), the size of the springs can be reduced. More specifically, in order to operate the linear compressor most efficiently, the power frequency f is designed to be adjusted to the resonance frequency (f _o ). When the linear compressor of the present invention is designed according to the linear motor characteristic of the present invention, It is preferable that the resonance design is performed in consideration of the magnetic spring constant (K _magnet ) as shown in the following equation.

That is, when the power supply frequency f supplied to the linear motor is determined, the mass M of the moving member made up of the piston and the permanent magnet, the number of the springs supporting the piston on both sides in order to adjust the power frequency f to the resonance point (K _mechanical ) defined as the restoring force, a spring constant (K _gas ) defined as the pressure acting on the gas sucked into the compression space, and a restoring force acting as the center of the permanent magnet moves away from the pole center of the stator The magnetic spring constant (K _magnet ) can be adjusted. At this time, the mass M of the moving member is determined for each product and the gas spring constant K _gas is also determined according to the type of the refrigerant. The gas spring constant K _gas is variable depending on the load, ) Of the movable member is maintained at a predetermined value or more, the mass M of the movable member and the gas spring constant (K _gas ) are regarded as fixed values since the influence of the gas spring acting on the movable member can be reduced. Thus, to match the power-supply frequency (f) in resonance, mechanical spring the number (K _mechanical) and magnetic spring constant, it is preferable to adjust the (K _magnet), the magnetic spring constant (K _magnet compared to the conventional as described above, ), It is preferable that the _mechanical spring constant (K _mechanical ) is designed to be smaller than the conventional one. As a result, in the example of the linear compressor according to the present invention, the number n of the springs supporting the piston reciprocating linearly in the both axial directions, the diameter D, the diameter d, and the length l Can be designed to be small, and the parts for supporting the springs can be omitted, thereby making it lightweight and compact.

6 is a perspective view illustrating an example of a back cover applied to the linear compressor according to the present invention.

3, the linear compressor according to the present invention includes a frame 102, a cylinder 103, a piston 104, a suction valve 105 and a discharge valve assembly 106, a motor cover 107, (Not shown) by a cushioning spring (not shown), which is composed of a spring 108, a suction muffler 110, two springs 120 and 121, and a linear motor 130. In order to be installed in a narrow installation space, The closed container 101 becomes smaller than that conventionally applied to the linear compressor. Accordingly, when the linear motor 130 vibrates due to the operation of the linear motor 130 or an external impact, the structure easily shakes even with a small vibration, so that the stopper 108a of the back cover 108 described above collides with the closed container 101, .

6, the back cover 108 is formed by pressing a plate material, and includes a flat portion 108b in which the stopper portion 108a protrudes in the axial direction, a pair of mounting portions 108b provided outside the flat portion 108b, And a pair of planar connecting portions 108d axially connecting the planar portion 108b and the mounting portions 108c. Since the back cover 108 is located at the outermost portion of the structure and the hermetically sealed container 101 (shown in Fig. 2) is formed in an elliptical shape, the back cover 108 is directly attached to the hermetically sealed container 101: Fig. 2). At this time, since the stopper portion 108a of the back cover 108 collides with the hermetic container 101 (shown in Fig. 2), the stopper portion 108a is formed in a circular cap shape in order to increase the buffering effect, It is preferable that it is rounded. Further, the back cover 108 can be effectively installed in the gentle space portion inside the hermetically sealed container 101 (shown in Fig. 2), and the planar portion 108b and the planar connection portions 108c can be inclined The curved surface connecting portions 108d 'are formed to extend from the flat surface portion 108b to the planar connecting portions 108c in the axial direction and the radial direction from the flat surface portion 108b. do.

Therefore, when the plate member is bending or punching at least once through press working, flat connecting portions 108d bent at 90 degrees on both sides of the flat surface portion 108b are made to face in the axial direction, The mounting portions 108c bent 90 占 at the ends of the planar connecting portions 108d are made to face radially and then the stopper portion 108a is axially projected to the plane portion 108b and the plane portions 108b ) And the planar connection portions 108d. Of course, fasteners h for fastening the bolts are separately machined on the mounting portions 108c.

Since the back cover 108 thus manufactured is provided with the rounded corner portion of the stopper portion 108a, that is, the shortest distance from the hermetic container 101 (shown in Fig. 2), the linear motor 130 2), the stopper portion 108a of the back cover 108 collides with the closed container 101 (shown in Fig. 2) even when the structure is vibrated due to the operation of the stopper portion 108a and the curved surface connecting portions Which is buffered by the shaft cover 108d 'to prevent deformation of the back cover 108, and furthermore the alignment of a cylinder, piston, motor cover, back cover, aling can be prevented from being turned off, thereby ensuring operational reliability.

In the foregoing, the present invention has been described in detail by way of examples on the basis of the embodiments of the present invention and the accompanying drawings. However, the scope of the present invention is not limited by the above embodiments and drawings, and the scope of the present invention will be limited only by the content of the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan sectional view showing an example of a linear compressor according to the prior art; Fig.

2 is a plan sectional view showing an example of a linear compressor according to the present invention.

3 is a side sectional view showing an example of a structure of a linear compressor according to the present invention.

4 is a side sectional view showing an example of the linear motor coupling applied to the linear compressor according to the present invention.

5A and 5B are diagrams illustrating an example of operation of a linear motor applied to a linear compressor according to the present invention.

6 is a perspective view showing an example of a back cover applied to a linear compressor according to the present invention.

Claims (8)

A sealed container in which a refrigerant is sucked / discharged; A cylinder accommodated in the hermetically sealed container and provided with a compression space therein; A frame having one end fixed to the cylinder; A piston having one end inserted into the cylinder; A linear motor reciprocatingly driving the piston; A motor cover for axially fixing the linear motor to the frame; At least two mechanical springs supporting the piston axially on both sides; A plurality of buffer springs for resiliently supporting the structure in which the parts are assembled except the hermetically sealed container inside the hermetically sealed container; And, And a back cover coupled to the motor cover and having a cap-shaped stopper protruding in the direction of the hermetically sealed container so that one mechanical spring is seated, The back cover includes a pair of mounting portions that are bolted to be symmetrical with respect to the outer circumferential portion of the motor cover, a pair of planar connecting portions extending straight from the mounting portions in the axial direction, A pair of curved surface connecting portions, and a circular cap-shaped stopper portion protruding axially between the curved surface connecting portions. The method according to claim 1, And the stopper portion is formed in a circular cap shape at the center of the back cover. 3. The method of claim 2, And the stopper portion has a rounded corner portion. The method according to claim 1, Wherein the stopper portion is formed by pressing a plate material. delete 5. The method according to any one of claims 1 to 4, The linear motor includes an inner stator provided outside the cylinder, an outer stator provided so as to have a pole between the inner stator and the gap between the inner stator and the inner stator, and an outer stator provided between the inner stator and the outer stator, A plurality of permanent magnets that linearly move, Characterized in that at the top dead center and the bottom dead point, at least one permanent magnet deviates from the clearance space portion between the inner stator and the pole of the outer stator when the plurality of permanent magnets reciprocate linearly in the gap between the inner stator and the outer stator . The method according to claim 6, A mass M of a movable member including a piston and a permanent magnet, a mechanical spring constant (K _mechanical ) defined by a restoring force of springs, a gas spring constant (K _gas ) defined by a working fluid pressure in the compression space, (F) defined by a magnetic spring constant (K _magnet ) defined by a restoring force that one pole center of the permanent magnet coincides with the pole center of the outer stator during reciprocating linear motion in the gap between the inner stator and the outer stator _o ). < / RTI > 8. The method of claim 7, The mechanical springs comprise a first spring installed between the cylinder and the piston flange, and a second spring provided between the piston flange and the stopper portion of the back cover, Wherein the diameter, the diameter, and the length of the springs are designed so that the mechanical spring constant decreases as the magnetic spring constant increases.

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