KR20160001055A - A linear compressor - Google Patents

Abstract

The present invention relates to a linear compressor. According to an embodiment of the present invention, a linear compressor comprises: a shell wherein a suction unit is provided; a cylinder provided inside the shell, and forming a compression space of refrigerant; a piston provided to be in a reciprocating movement in an axial direction inside the cylinder; at least one spring inducing resonance motion of the piston; and a guide device formed in an inner circumferential surface of the cylinder, and increasing the degree of freedom with respect to a movement of the spring.

Description

[0001] The present invention relates to a linear compressor,

The present invention relates to a linear compressor.

The cooling system is a system that generates cool air by circulating a coolant, and repeats the process of compressing, condensing, expanding, and evaporating the coolant. To this end, the cooling system includes a compressor, a condenser, an expansion device and an evaporator. The cooling system may be installed in a refrigerator or an air conditioner as a household appliance.

Generally, a compressor is a mechanical device that receives power from a power generating device such as an electric motor or a turbine to increase pressure by compressing air, refrigerant or various other operating gases. .

Such a compressor is broadly classified into a reciprocating compressor that compresses the refrigerant while linearly reciprocating the piston inside the cylinder so as to form a compression space in which a working gas is sucked and discharged between the piston and the cylinder. A rotary compressor for compressing the refrigerant while the roller is eccentrically rotated along the inner wall of the cylinder and a compression space for sucking and discharging the working gas between the roller and the cylinder, a scroll compressor in which a compression space in which an operating gas is sucked and discharged is formed between a fixed scroll and a fixed scroll and the orbiting scroll rotates along the fixed scroll to compress the refrigerant.

In recent years, among the reciprocating compressors, there has been developed a linear compressor in which a piston is directly connected to a driving motor that reciprocates linearly, so that compression efficiency can be improved without mechanical loss due to motion switching and a simple structure is constructed.

Normally, the linear compressor is configured to suck and compress the refrigerant while discharging the refrigerant while moving the piston in the sealed shell by reciprocating linear motion within the cylinder by the linear motor.

The linear motor is configured such that a permanent magnet is positioned between an inner stator and an outer stator, and the permanent magnet is driven to linearly reciprocate by the mutual electromagnetic force between the permanent magnet and the inner (or outer) stator. As the permanent magnet is driven in the state of being connected to the piston, the piston linearly reciprocates in the cylinder, sucks the refrigerant, compresses the refrigerant, and discharges the refrigerant.

Regarding the conventional linear compressor, the present applicant has been registered by applying a patent application (hereinafter referred to as a prior art document).

[Prior Art]

1. Registration No. 10-1307688, Date of Registration: September 5, 2013 Title of invention: Linear compressor

The linear compressor according to the prior art document includes a shell 110 that accommodates a number of components. The height of the shell 110 in the up-and-down direction is somewhat higher, as shown in Fig. 2 of the prior art.

An oil supply assembly 900 capable of supplying oil to the space between the cylinder 200 and the piston 300 is provided in the shell 110.

On the other hand, when the linear compressor is provided in the refrigerator, the linear compressor may be installed in a machine room provided at the rear lower side of the refrigerator.

In recent years, increasing the internal storage space of refrigerators has become a major concern for consumers. In order to increase the internal storage space of the refrigerator, it is necessary to reduce the volume of the machine room, and reducing the size of the linear compressor to reduce the volume of the machine room becomes a major issue.

However, the linear compressor disclosed in the prior art has a relatively large volume, which is not suitable for a refrigerator for increasing internal storage space.

In order to reduce the size of the linear compressor, it is necessary to make the main parts of the compressor small, but in this case, the performance of the compressor may be degraded.

In order to compensate for the problem of the performance degradation of the compressor, it may be considered to increase the operating frequency of the compressor. However, as the operating frequency of the compressor increases, the frictional force due to the oil circulated in the compressor increases, thereby deteriorating the performance of the compressor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a linear compressor with improved operational reliability.

A linear compressor according to an embodiment of the present invention includes: a shell provided with a suction portion; A cylinder disposed inside the shell and forming a compression space for the refrigerant; A piston provided to be axially reciprocable within the cylinder; At least one spring for inducing a resonant motion of the piston; And a guide device formed on an inner circumferential surface of the cylinder and increasing the degree of freedom of movement of the spring.

In addition, the guide device includes a depression that is recessed from the inner circumferential surface of the cylinder.

Further, the compressor further includes a discharge valve provided in a front portion of the cylinder for selectively discharging the refrigerant in the compression space of the refrigerant, and the guide device is formed on the inner peripheral surface of the rear portion of the cylinder.

The inner circumferential surface of the cylinder may have a first inner circumferential surface on which the guide device is formed. And a second inner circumferential surface extending forward from the first inner circumferential surface.

In addition, a nozzle portion formed in the cylinder and introducing at least a part of the refrigerant discharged through the discharge valve into the space between the piston and the cylinder is included.

The shortest distance (C2) between the first inner circumferential surface and the outer circumferential surface of the piston is formed to be larger than the shortest distance (C1) between the second inner circumferential surface and the outer circumferential surface of the piston.

The shortest distance (C3) between the inner circumferential surface of the rear portion of the frame and the outer circumferential surface of the piston is larger than the C1 and C2.

A first chamfered portion extending obliquely in an outer radial direction from a rear end of the depressed portion; And a second chamfer portion provided at a rear portion of the frame and extending obliquely in an outer radial direction.

A motor assembly for generating a driving force; A stator cover for supporting the motor assembly; A supporter for supporting the piston; And a back cover spaced apart from one side of the supporter.

The spring may include a plurality of first springs provided between the stator cover and the supporter; And a plurality of second springs installed between the supporter and the back cover.

The first spring and the second spring each include six springs.

A flow space part formed between the cylinder and the frame and through which at least a portion of the refrigerant discharged through the discharge valve flows; A sealing pocket communicating with the flow space portion; And a sealing member movably installed in the sealing pocket to seal the space between the frame and the cylinder.

Further, the sealing member is formed at an outer circumferential surface of a cylinder to be installed, and an inner circumferential surface of a cylinder in which the guide device is installed, facing each other.

According to another aspect of the present invention, there is provided a linear compressor including: a shell provided with a suction portion; A cylinder disposed inside the shell and forming a compression space for the refrigerant; A piston provided to be axially reciprocable within the cylinder; A discharge valve provided at one side of the cylinder for selectively discharging compressed refrigerant in a compression space of the refrigerant; A flow space part formed between the cylinder and the frame, in which at least a portion of the refrigerant discharged through the discharge valve flows; A nozzle unit formed in the cylinder and introducing the refrigerant in the flow space part to the inside of the cylinder; A plurality of springs for applying an elastic force to the piston; And a depressed portion formed to be recessed on the inner circumferential surface of the cylinder and increasing the tolerance between the inner circumferential surface of the cylinder and the outer circumferential surface of the piston.

In addition, the discharge valve is coupled to the front surface of the cylinder, and the depression is formed in the rear portion of the cylinder.

Further, the radial width (C2) of the depressed portion is formed to be larger than the radial width (C1) of the flow space portion.

In addition, the depression allows the rear portion of the piston to move in the radial direction of the cylinder, thereby increasing the degree of freedom of the plurality of springs.

According to the present invention, it is possible to reduce the size of the machine room of the refrigerator by reducing the size of the compressor including the internal parts, thereby increasing the internal storage space of the refrigerator.

Also, by increasing the operating frequency of the compressor, it is possible to prevent performance deterioration due to the reduced internal parts, and by applying gas bearings between the cylinder and the piston, frictional force that can be generated by the oil can be reduced.

Further, by providing the guide device on the inner peripheral surface of the rear portion of the cylinder, the degree of freedom of the spring can be ensured, thereby reducing the stress acting on the spring, thereby preventing wear and damage of the spring.

Specifically, the guide device may be configured to increase the distance, or tolerance, between the inner circumferential surface of the cylinder and the outer circumferential surface of the piston, including depressions depressed from the inner circumferential surface of the cylinder, thereby alleviating the gas bearing somewhat, Directional motion is generated at a certain level, so that the degree of freedom of the spring can be secured.

Further, by providing a plurality of filter devices inside the compressor, foreign matter or oil can be prevented from being contained in the compressed gas (or discharge gas) flowing from the nozzle of the cylinder to the outside of the piston.

Particularly, since the first filter is provided in the suction muffler, foreign matter contained in the refrigerant can be prevented from flowing into the compression chamber. By providing the second filter at the coupling portion between the cylinder and the frame, foreign matter or oil Can be prevented from flowing to the gas inlet portion of the cylinder.

A third filter may be provided in the gas inflow portion of the cylinder to prevent foreign matter or oil from flowing into the nozzle of the cylinder from the gas inflow portion.

As described above, since foreign matter or oil contained in the compressed gas acting as a bearing can be filtered through the plurality of filter devices provided in the compressor and the dryer, it is possible to prevent the nozzle portion of the cylinder from clogging due to foreign matter or oil have.

By preventing the clogging of the nozzle of the cylinder, the action of the gas bearing can be effectively performed between the cylinder and the piston, thereby preventing the wear of the cylinder and the piston.

1 is a sectional view showing a configuration of a linear compressor according to an embodiment of the present invention.
2 is a cross-sectional view showing a configuration of a suction muffler according to an embodiment of the present invention.
3 is a cross-sectional view showing a state in which a second filter according to an embodiment of the present invention is disposed.
4 is an exploded perspective view showing a structure of a cylinder and a frame according to an embodiment of the present invention.
FIG. 5 is a cross-sectional view showing a combination of a cylinder and a piston according to an embodiment of the present invention.
6 is an exploded perspective view showing the structure of a cylinder according to an embodiment of the present invention.
Fig. 7 is an enlarged view of "A" in Fig. 5. Fig.
FIG. 8 is a cross-sectional view showing a combination of a cylinder and a frame according to an embodiment of the present invention. FIG.
9 is an enlarged view of "B" in FIG.
10 is a view showing a coupling structure of a motor assembly and a frame according to an embodiment of the present invention.
11 is a view showing a coupling structure of a back cover and a spring according to an embodiment of the present invention.
12 is a view showing a coupling structure of a supporter and a spring according to an embodiment of the present invention.
13 is a cross-sectional view illustrating a refrigerant flow of a linear compressor according to an embodiment of the present invention.
14 is a view showing the operation of the cylinder and the piston when the linear compressor according to the embodiment of the present invention is operated.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. It is to be understood, however, that the spirit of the invention is not limited to the embodiments shown and that those skilled in the art, upon reading and understanding the spirit of the invention, may easily suggest other embodiments within the scope of the same concept.

1 is a sectional view showing a configuration of a linear compressor according to an embodiment of the present invention.

Referring to FIG. 1, a linear compressor 100 according to an embodiment of the present invention includes a substantially cylindrical shell 101, a first cover 102 coupled to one side of the shell 101, And a second cover 103 is provided. The first cover 102 is disposed on the right side of the shell 101 and the second cover 103 is disposed on the left side of the shell 101. [ Can be combined.

In a broad sense, the first cover 102 and the second cover 103 can be understood as a constitution of the shell 101. [

The linear compressor 100 is provided with a cylinder 120 provided inside the shell 101, a piston 130 linearly reciprocating in the cylinder 120, and a driving force applied to the piston 130 A motor assembly 140 is included as a linear motor.

When the motor assembly 140 is driven, the piston 130 can reciprocate at a high speed. The operating frequency of the linear compressor 100 according to the present embodiment is approximately 100 Hz.

In more detail, the linear compressor 100 includes a suction unit 104 through which refrigerant flows and a discharge unit 105 through which refrigerant compressed in the cylinder 120 is discharged. The suction unit 104 may be coupled to the first cover 102 and the discharge unit 105 may be coupled to the second cover 103.

The refrigerant sucked through the suction portion 104 flows into the piston 130 through the suction muffler 150. In the course of the refrigerant passing through the suction muffler 150, the noise can be reduced. The suction muffler 150 is constructed by combining a first muffler 151 and a second muffler 153. At least a portion of the suction muffler 150 is located within the piston 130.

The piston 130 includes a substantially cylindrical piston body 131 and a piston flange portion 132 extending radially from the piston body 131. The piston body 131 reciprocates within the cylinder 120 and the piston flange 132 can reciprocate outside the cylinder 120.

The piston 130 may be made of an aluminum material (aluminum or aluminum alloy) which is a non-magnetic material. The piston 130 is made of an aluminum material to prevent the magnetic flux generated in the motor assembly 140 from being transmitted to the piston 130 and leaking to the outside of the piston 130. The piston 130 may be formed by a forging method.

Meanwhile, the cylinder 120 may be made of an aluminum material (aluminum or aluminum alloy) which is a nonmagnetic material. The material composition ratio of the cylinder 120 and the piston 130, that is, kind and composition ratio, may be the same.

Since the cylinder 120 is made of an aluminum material, the magnetic flux generated in the motor assembly 200 can be prevented from being transmitted to the cylinder 120 and leaking to the outside of the cylinder 120. The cylinder 120 may be formed by an extrusion rod processing method.

The piston 130 and the cylinder 120 are made of the same material (aluminum), so that the coefficients of thermal expansion are equal to each other. Since the piston 130 and the cylinder 120 have the same thermal expansion coefficient during the operation of the linear compressor 100 and the inside of the shell 100 has a high temperature (about 100 ° C) And the cylinder 120 can be thermally deformed by the same amount.

As a result, since the piston 130 and the cylinder 120 are thermally deformed in different sizes or directions, interference between the piston 130 and the cylinder 120 can be prevented.

The cylinder (120) is configured to receive at least a portion of the suction muffler (150) and at least a portion of the piston (130).

A compression space P in which the refrigerant is compressed by the piston 130 is formed in the cylinder 120. A suction hole 133 for introducing a refrigerant into the compression space P is formed in a front portion of the piston 130. The suction hole 133 is selectively provided in front of the suction hole 133, A suction valve 135 is provided. At a substantially central portion of the suction valve 135, a fastening hole to which a predetermined fastening member is coupled is formed.

A discharge cover 160 for forming a discharge space or a discharge path for the refrigerant discharged from the compression space P and a discharge cover 160 coupled to the discharge cover 160 and disposed in front of the compression space P, A discharge valve assembly (161, 162, 163) for selectively discharging compressed refrigerant is provided.

The discharge valve assembly 161 is provided with a discharge valve 161 that opens when the pressure in the compression space P becomes equal to or higher than the discharge pressure and causes the refrigerant to flow into the discharge space of the discharge cover 160, A valve spring 162 provided between the discharge cover 161 and the discharge cover 160 for applying an elastic force in the axial direction and a stopper 163 for limiting the amount of deformation of the valve spring 162.

Here, the compression space P is understood as a space formed between the suction valve 135 and the discharge valve 161. The suction valve 135 is formed at one side of the compression space P and the discharge valve 161 may be provided at the other side of the compression space P, have. The discharge valve 161 may be movably provided at the front end of the cylinder 120.

The "axial direction" can be understood as a direction in which the piston 130 reciprocates, that is, a lateral direction in FIG. In the "axial direction", the direction from the suction portion 104 toward the discharge portion 105, that is, the direction in which the refrigerant flows is referred to as "forward" and the opposite direction is defined as "rearward".

On the other hand, "radial direction" can be understood as a direction perpendicular to the direction in which the piston 130 reciprocates, and in the longitudinal direction of Fig.

The stopper 163 may be seated in the discharge cover 160 and the valve spring 162 may be seated in the rear of the stopper 163. The discharge valve 161 is coupled to the valve spring 162 and the rear or rear surface of the discharge valve 161 is positioned to be supported on the front surface of the cylinder 120.

The valve spring 162 may include a plate spring, for example.

When the pressure in the compression space P is lower than the discharge pressure and the suction pressure is lower than the suction pressure in the reciprocating linear motion of the piston 130 in the cylinder 120, the suction valve 135 is opened, Is sucked into the compression space (P). On the other hand, when the pressure in the compression space P becomes equal to or higher than the suction pressure, the refrigerant in the compression space P is compressed while the suction valve 135 is closed.

On the other hand, when the pressure in the compression space P becomes equal to or higher than the discharge pressure, the valve spring 162 is deformed to open the discharge valve 161. The refrigerant is discharged from the compression space P, And is discharged into the discharge space of the cover 160.

The refrigerant flowing in the discharge space of the discharge cover 160 flows into the loop pipe 165. The loop pipe 165 is coupled to the discharge cover 160 and extends to the discharge part 105 to guide the compressed refrigerant in the discharge space to the discharge part 105. For example, the loop pipe 178 has a round shape extending in a predetermined direction, and is coupled to the discharge unit 105.

The linear compressor (100) further includes a frame (110) coupled to the outside of the cylinder (120). The frame 110 is configured to fix the cylinder 120 and may be fastened to the cylinder 200 by a separate fastening member. The frame 110 is disposed to surround the cylinder 120. That is, the cylinder 120 may be positioned to be received inside the frame 110. The discharge cover 160 may be coupled to the front surface of the frame 110.

On the other hand, at least a portion of the gaseous refrigerant in the high-pressure gas refrigerant discharged through the opened discharge valve 161 flows through the space of the portion where the cylinder 120 and the frame 110 are coupled to the outer peripheral surface side of the cylinder 120 Can flow.

The refrigerant flows into the cylinder 120 through the gas inlet 122 (see FIG. 7) formed in the cylinder 120 and the nozzle 123 (see FIG. 7). The introduced refrigerant may flow into the space between the piston 130 and the cylinder 120 so that the outer circumferential surface of the piston 130 is spaced from the inner circumferential surface of the cylinder 120. Accordingly, the introduced refrigerant can function as a "gas bearing " which reduces friction with the cylinder 120 during reciprocation of the piston 130. [

The motor assembly 140 includes outer stator 141, 143 or 145 fixed to the frame 110 and arranged to surround the cylinder 120, an inner stator 148 (not shown) And permanent magnets 146 positioned in the space between the outer stator 141, 143, 145 and the inner stator 148.

The permanent magnets 146 can reciprocate linearly by mutual electromagnetic forces between the outer stator 141, 143, 145 and the inner stator 148. The permanent magnet 146 may be formed of a single magnet having one pole or a magnet having three poles. A plurality of the permanent magnets 146 may be provided on the outer side of the inner stator 148.

The permanent magnet 146 may be coupled to the piston 130 by a connecting member 138. In detail, the connecting member 138 may be coupled to the piston flange portion 132 and may be bent and extended toward the permanent magnet 146. As the permanent magnet 146 reciprocates, the piston 130 can reciprocate axially together with the permanent magnet 146 by the connecting member 138.

The motor assembly 140 further includes a fixing member 147 for fixing the permanent magnet 146 to the connecting member 138. The fixing member 147 may be formed by mixing glass fiber or carbon fiber with resin. The fixing member 147 is provided so as to surround the inside and the outside of the permanent magnet 146 to firmly maintain the state of engagement between the permanent magnet 146 and the connecting member 138.

The outer stator 141, 143, 145 includes the coil winding bodies 143, 145 and the stator core 141.

The coil winding bodies 143 and 145 include a bobbin 143 and a coil 145 wound around the bobbin 143 in the circumferential direction. The end face of the coil 145 may have a polygonal shape, and may have a hexagonal shape, for example.

The stator core 141 is formed by stacking a plurality of laminations in a circumferential direction, and may be arranged to surround the coil winding bodies 143 and 145.

A stator cover 149 is provided at one side of the outer stator 141, 143, 145. One side of the outer stator 141, 143, 145 may be supported by the frame 110 and the other side may be supported by the stator cover 149.

The inner stator 148 is fixed to the outer periphery of the frame 110. The inner stator 148 is formed by laminating a plurality of laminations in the circumferential direction from the outside of the frame 110.

The linear compressor 100 further includes a supporter 137 for supporting the piston 130 and a back cover 170 spaced from one side of the supporter 137 and spring-coupled to the supporter 137 do.

The supporter 137 is coupled to the piston flange portion 132 and the connecting member 138 by a predetermined fastening member.

A suction guide portion 155 is coupled to the front of the back cover 170. The suction guide part 155 guides the refrigerant sucked through the suction part 104 into the suction muffler 150.

The linear compressor 100 includes a plurality of springs 176 whose natural frequencies are adjusted so that the piston 130 can resonate.

The plurality of springs 176 are provided with a first spring 176a (see FIG. 12) supported between the supporter 137 and the stator cover 149 and a second spring 176b between the supporter 137 and the back cover 170 And a second spring 176b (see Fig. 12) supported.

The linear compressor 100 further includes leaf springs 172 and 174 which are provided on both sides of the shell 101 to allow the internal parts of the compressor 100 to be supported by the shell 101.

The leaf springs 172 and 174 include a first leaf spring 172 coupled to the first cover 102 and a second leaf spring 174 coupled to the second cover 103. For example, the first leaf spring 172 can be fitted to a portion where the shell 101 and the first cover 102 are coupled, and the second leaf spring 174 can be engaged with the shell 101, 2 cover 103 is engaged.

2 is a cross-sectional view showing a configuration of a suction muffler according to an embodiment of the present invention.

Referring to FIG. 2, a suction muffler 150 according to an embodiment of the present invention includes a first muffler 151, a second muffler 153 coupled to the first muffler 151, 151 and a first filter 310 supported by a second muffler 153. [

The first muffler 151 and the second muffler 153 are formed with a flow space portion in which the refrigerant flows. The first muffler 151 extends from the inside of the suction portion 104 toward the discharge portion 105 and at least a part of the first muffler 151 is connected to the inside of the suction guide portion 155 . The second muffler 153 extends from the first muffler 151 to the interior of the piston body 131.

The first filter 310 is installed in the flow space portion and is understood as a configuration for filtering foreign matters. The first filter 310 is made of a material having magnetism, so that foreign matters, particularly metal dirt, contained in the refrigerant can be easily filtered.

For example, the first filter 310 may be made of a stainless steel material, and may have a predetermined magnetic property and may be prevented from rusting.

As another example, the first filter 310 may be coated with a magnetic material or may be configured to have a magnet attached to the surface of the first filter 310.

The first filter 310 may be a mesh type having a plurality of filter holes, and may have a substantially disc shape. The filter hole may have a diameter or a width of a predetermined size or less. For example, the predetermined size may be about 25 [mu] m.

The first muffler 151 and the second muffler 153 can be assembled by press-fitting. The first filter 310 may be fitted to the first muffler 151 and the second muffler 153 by press-fitting.

For example, one of the first muffler 151 and the second muffler 153 may have a groove portion and the other may include a protrusion portion into which the groove portion is inserted.

The first filter 310 may be supported by the first and second mufflers 151 and 153 while both side portions of the first filter 310 are interposed between the groove and the protrusion.

More specifically, the first muffler 151 and the second muffler 153 move in a direction in which the first filter 310 is positioned between the first and second mufflers 151 and 153, The both sides of the first filter 310 can be fitted and fixed between the groove and the protrusion.

As described above, the first filter 310 is provided in the suction muffler 150, so that the foreign matter having a predetermined size or more of the refrigerant sucked through the suction unit 104 can be filtered by the first filter 310 . Accordingly, the foreign matter is contained in the refrigerant acting as the gas bearing between the piston 130 and the cylinder 120, and can be prevented from flowing into the cylinder 120.

Further, since the first filter 310 is firmly fixed to the press-fitted portion of the first and second mufflers 151 and 153, the suction muffler 150 can be prevented from being separated from the first filter 310.

FIG. 3 is a cross-sectional view showing a state in which a second filter according to an embodiment of the present invention is disposed, and FIG. 4 is an exploded perspective view showing a structure of a cylinder and a frame according to an embodiment of the present invention.

3 and 4, a linear compressor 100 according to an embodiment of the present invention is provided with a high-pressure gas refrigerant pipe (not shown) provided between a frame 110 and a cylinder 120 and discharged through a discharge valve 161, And a second filter 320 for filtering the input signal.

The second filter 320 may be positioned at a portion where the frame 110 and the cylinder 120 are coupled to each other or at a coupling surface.

Specifically, the cylinder 120 includes a substantially cylindrical cylinder body 121 and a cylinder flange portion 125 extending radially from the cylinder body 121.

The cylinder body 121 includes a gas inflow portion 122 into which the discharged gas refrigerant flows. The gas inlet 122 may be recessed in a substantially circular shape along the outer circumferential surface of the cylinder body 121.

A plurality of gas inflow portions 122 may be provided. The plurality of gas inlet portions 122 are provided with gas inlet portions 122a and 122b (see FIG. 6) located at one side from the axial center portion of the cylinder body 121 and gas inlet portions (See Fig. 6).

The cylinder flange portion 125 is provided with a coupling portion 126 to be engaged with the frame 110. The coupling portion 126 may be configured to protrude outward from the outer circumferential surface of the cylinder flange portion 125. The fastening portion 126 may be coupled to the cylinder fastening hole 118 of the frame 110 by a predetermined fastening member.

The cylinder flange portion 125 includes a seating surface 127 that is seated on the frame 110. The seating surface 127 may be a rear portion of the cylinder flange 125 extending radially from the cylinder body 121.

The frame 110 includes a frame body 111 surrounding the cylinder body 121 and a cover coupling part 115 extending in the radial direction of the frame body 111 and coupled to the discharge cover 160. [ .

The cover engaging portion 115 is provided with a plurality of cover engaging holes 116 into which the engaging members engaged with the discharge cover 160 are inserted and a plurality of cylinder engaging portions And a fastening hole 118 is formed. The cylinder fastening hole 118 is formed at a position slightly recessed from the cover engaging portion 115.

The frame 110 is provided with an insertion portion 117 which is recessed rearward from the cover engagement portion 115 and into which the cylinder flange portion 125 is inserted. That is, the insertion portion 117 may be disposed so as to surround the outer circumferential surface of the cylinder flange portion 125. The recessed depth of the insertion portion 117 may correspond to the front and rear widths of the cylinder flange portion 125.

A predetermined refrigerant flow space may be formed between the inner circumferential surface of the insertion portion 117 and the outer circumferential surface of the cylinder flange portion 125. The high-pressure gas refrigerant discharged from the discharge valve 161 can flow toward the outer circumferential surface of the cylinder body 121 via the refrigerant flow space. The second filter 320 may be installed in the refrigerant flow space to filter the refrigerant.

In detail, a seating part provided stepwise is formed at the rear end of the insertion part 117, and a ring-shaped second filter 320 can be seated in the seating part.

When the cylinder 120 is coupled to the frame 110 in a state where the second filter 320 is seated in the seating part, the cylinder flange 125 is positioned in front of the second filter 320, The second filter 320 is pressed. That is, the second filter 320 may be interposed between the seating portion of the frame 110 and the seating surface 127 of the cylinder flange portion 125.

The second filter 320 blocks the foreign matter from the high-pressure gas refrigerant discharged through the opened discharge valve 161 from flowing into the gas inlet 122 of the cylinder 120, As shown in FIG.

For example, the second filter 320 may include a nonwoven fabric made of PET (Polyethylene Terephthalate) fiber or an absorbent. The PET has an advantage of excellent heat resistance and mechanical strength. It is also possible to block foreign matter of 2 mu m or more in the refrigerant.

The high-pressure gas refrigerant that has passed through the space between the inner circumferential surface of the insertion portion 117 and the outer circumferential surface of the cylinder flange portion 125 passes through the second filter 320 and the refrigerant is filtered .

The linear compressor 100 is provided with a sealing member 200 which is provided between the outer circumferential surface of the cylinder body 121 and the inner circumferential surface of the frame body 111 and seals a space between the cylinder 120 and the frame 110, ). A sealing pocket 220 (see FIG. 9) for receiving the sealing member 200 is formed between the outer circumferential surface of the cylinder body 121 and the inner circumferential surface of the frame body 111.

The sealing member 200 may have a ring shape (O-ring). The sealing member 200 is disposed to surround the outer circumference of the first inclined portion 128 provided at the rear portion of the cylinder body 121 and is provided movably along the first inclined portion 128 .

FIG. 5 is a cross-sectional view showing a combined state of a cylinder and a piston according to an embodiment of the present invention, FIG. 6 is a view showing a configuration of a cylinder according to an embodiment of the present invention, Fig.

5 to 7, a cylinder 120 according to an embodiment of the present invention includes a cylinder body 121 having a substantially cylindrical shape and defining a first body end 121a and a second body end 121b. And a cylinder flange portion 125 extending radially outward from the second body end portion 121b of the cylinder body 121. [

The first body end 121a and the second body end 121b form both ends of the cylinder body 121 with respect to the axial center 121c of the cylinder body 121. [ The first body end 121a defines a rear end of the cylinder body 121 and the second body end 121b defines a front end of the cylinder body 121. [

The cylinder body 121 is formed with a plurality of gas inflow portions 122 through which at least a part of the high-pressure gas refrigerant discharged through the discharge valve 161 flows. A third filter 330 as a "filter member " may be disposed in the plurality of gas inflow portions 122.

The plurality of gas inlet portions 122 are configured to be recessed from the outer peripheral surface of the cylinder body 121 by a predetermined depth and width. The refrigerant may be introduced into the cylinder body 121 through the plurality of gas inlet portions 122 and the nozzle portion 123.

The introduced refrigerant is positioned between the outer circumferential surface of the piston 130 and the inner circumferential surface of the cylinder 120 and functions as a gas bearing for the movement of the piston 130. That is, the outer circumferential surface of the piston 130 is kept spaced from the inner circumferential surface of the cylinder 120 by the pressure of the introduced refrigerant.

The plurality of gas inlet portions 122 are provided with a first gas inlet portion 122a and a second gas inlet portion 122b located at one side from the axial center portion 121c of the cylinder body 121, And a third gas inflow portion 122c located on the other side from the direction center portion 121c.

The first and second gas inflow portions 122a and 122b are located closer to the second body end portion 121b with respect to the axial center portion 121c of the cylinder body 121, The first body portion 122c may be located closer to the first body end 121a with respect to the axial center portion 121c of the cylinder body 121. [

That is, the plurality of gas inlet portions 122 are arranged in an asymmetric number with reference to the axial center portion 121c of the cylinder body 121.

Referring to FIG. 1, the internal pressure of the cylinder 120 is higher at the side of the second body end 121b closer to the discharge side of the compressed refrigerant, as compared with the side of the first body end 121a close to the suction side of the refrigerant. A larger number of gas inlet portions 122 are formed on the second body end portion 121b side to enhance the function of the gas bearing and a relatively small gas inlet portion 122 on the first body end portion 121a side ) Can be formed.

The cylinder body 121 further includes a nozzle part 123 extending from the plurality of gas inflow parts 122 toward the inner circumferential surface of the cylinder body 121. The nozzle unit 123 is formed to have a width or a size smaller than the gas inlet 122.

A plurality of nozzle portions 123 may be formed along the gas inlet portion 122 extending in a circular shape. The plurality of nozzle units 123 are disposed apart from each other.

The nozzle unit 123 includes an inlet 123a connected to the gas inlet 122 and an outlet 123b connected to the inner circumferential surface of the cylinder body 121. The nozzle unit 123 is formed to have a predetermined length from the inlet 123a toward the outlet 123b.

The refrigerant flowing into the gas inlet 122 is filtered by the third filter 330 and then flows to the inlet 123a of the nozzle 123. The refrigerant flows into the cylinder 123 along the nozzle 123, (120). The refrigerant flows into the inner space of the cylinder 120 through the outlet portion 123b.

The piston 130 is moved away from the inner circumferential surface of the cylinder 120 by the pressure of the refrigerant discharged from the outlet portion 123b, that is, from the inner circumferential surface of the cylinder 120. That is, the pressure of the refrigerant supplied to the inside of the cylinder 120 provides the lifting force or floating pressure to the piston 130.

The cylinder 120 further includes a first inclined portion 128 extending obliquely rearward from the cylinder body 121. The first inclined portion 128 may be inclined in a direction in which the outer diameter of the cylinder 120 gradually decreases.

Therefore, the outer diameter of the cylinder 120 in which the first inclined portion 128 is formed may be smaller than the outer diameter of the cylinder body 121.

The cylinder 120 includes an inner circumferential surface 121d (see Fig. 8) having a substantially constant inner diameter. That is, the inner circumferential surface 121d of the cylinder 120 is formed to have a substantially constant inner diameter from the cylinder body 121 to the first inclined portion 128.

The cylinder 120 is formed with a depression 300 that is depressed radially outward from the inner circumferential surface 121d. In other words, a depression 300 is formed in at least a part of the inner circumferential surface 121d.

The clearance between the inner circumferential surface 121d of the cylinder 120 and the piston 130 can be adjusted by the configuration of the depressed portion 300 in the inner circumferential surface 121d where the depressed portion 300 is formed The first clearance C2 (see Fig. 14) is formed larger than the second clearance C1 (see Fig. 14) at the other inner circumferential surface 121d.

FIG. 8 is a cross-sectional view showing a combined state of a cylinder and a frame according to an embodiment of the present invention, and FIG. 9 is an enlarged view of "B" in FIG.

8 and 9, between a cylinder 120 and a frame 110 according to an embodiment of the present invention, a flow space (not shown) in which at least a part of the refrigerant discharged through the discharge valve 161 flows, A portion 210 is formed.

The flow space portion 210 starts from a space between the cover engaging portion 115 of the frame 110 and the cylinder flange portion 125 of the cylinder 120 and extends rearward, And a space between the rear end of the cylinder body 121 and the first end 121a of the cylinder body 121. [

The refrigerant flowing in the flow space 210 may flow toward the inner circumferential surface of the cylinder 120 via the gas inlet 122 and the nozzle 123. [

The linear compressor 100 includes a sealing pocket 220 communicating with the flow space portion 210 and having a sealing member 200 installed therein.

The sealing pocket 220 is a space in which the sealing member 200 can be installed and is formed between the inner circumferential surface of the frame body 111 and the outer circumferential surface of the cylinder body 121. The sealing pockets 220 may be formed at the rear of the frame 110 and the cylinder 120. The flow cross sectional area of the sealing pocket 220 is formed to be larger than the flow cross sectional area of the flow space 210 based on the flow direction of the refrigerant.

In detail, the rear portion of the frame body 111 includes a pocket forming portion 112 configured to be depressed radially outward from the inner circumferential surface of the frame body 111. [ The pocket forming part 112 forms at least one side of the sealing pocket 212.

The frame body 111 further includes a second inclined portion 113 extending obliquely rearward inward from the pocket forming portion 112.

The cylinder body 121 includes a first inclined portion 128 for forming the sealing pocket 220. The first inclined portion 128 constitutes at least one surface of the sealing pocket 220.

The first inclined portion 128 extends obliquely rearward inward from the first body end 121a of the cylinder body 121. [ The first inclined portion 128 may extend from the inside of the pocket forming portion 112 to a point corresponding to the inside of the second inclined portion 113.

Due to the recessed structure of the pocket forming portion 112 and the inclined structure of the first inclined portion 128, the height of the sealing pocket 220 in the radial direction may be larger than the diameter of the sealing member 200 have. The length of the sealing pocket 220 in the axial direction may be greater than the diameter of the sealing member 200.

That is, the sealing pocket 220 may have a size such that the sealing member 200 is movable without being interfered with the frame body 111 or the cylinder body 121.

The spacing or distance between the rear portion of the first inclined portion 128 and the rear portion of the second inclined portion 113 is smaller than the diameter of the sealing member 200. Therefore, during operation of the linear compressor 100, when the refrigerant flows backward along the flow space portion 210, the sealing member 200 moves backward due to the pressure of the refrigerant, .

Since the sealing member 200 is interposed between the cylinder 120 and the frame 110 to seal the flow space 210, the refrigerant in the flow space 210 flows into the frame 110 It is possible to prevent leakage to the outside.

When the sealing member 200 is movably provided in the sealing pocket 220 and the refrigerant flows in the flow space part 210 by driving the compressor, It is possible to prevent the cylinder 120 from being deformed due to the pressing force of the sealing member 200 because the sealing member 200 is pressed against the cylinder 120 and the frame 110.

The sealing member 200 is movably installed on one circumferential surface of the cylinder 120 and the depressed portion 300 is located at a position corresponding to the outer circumferential surface of the cylinder 120 on which the sealing member 200 is installed, Is formed on one inner circumferential surface of the cylinder (120). That is, one outer circumferential surface and one inner circumferential surface of the cylinder 120 may be formed at positions facing each other.

A predetermined gas pressure acts between the inner circumferential surface 121d of the cylinder 120 and the outer circumferential surface of the piston 130 due to the refrigerant gas flowing through the nozzle unit 123, The movement of the piston 130 in the radial direction is restricted and the forward and backward movement of the piston 130 can be guided.

At this time, the plurality of springs 176 perform a compression or tension movement in the forward and backward directions. A side force or a torsion moment may be applied to the plurality of springs 176. Here, the lateral force is a force acting in the radial direction, and the torsional moment can be understood as a moment rotating about the axial direction. As a result, axial compression force and lateral force (or torsional moment) in the rotational direction are applied to the plurality of springs 176.

The plurality of springs 176 are supported between the supporter 137 and the stator cover 149 and between the supporter 137 and the back cover 170 in the circumferential direction As shown in FIG.

The ends of the plurality of springs 176 may be arranged to face each other and to be positioned at the same distance from the center of the piston 130 in order to cancel the lateral force.

Meanwhile, since the piston 130 is tightly supported by the gas bearing inside the cylinder 120, the plurality of springs 176 may not move smoothly. When the plurality of springs 176 do not move smoothly while the action force of the piston 130 is transmitted to the plurality of springs 176, stress is applied to the plurality of springs 176, Or breakage may occur.

Therefore, the plurality of springs 176 need to have a certain degree of freedom in order to prevent the stresses between the operations of the compressors. The present embodiment is characterized in that the provision of the depressed portion 300 on the inner peripheral surface of the rear portion of the cylinder 120 allows the tolerance C2 between the inner peripheral surface of the rear portion of the cylinder 120 and the outer peripheral surface of the piston 130, And the degree of freedom of the spring 176 is ensured by slightly alleviating the gas bearing accordingly.

More specifically, when a lateral force or a torsional moment acts on the plurality of springs 176 in the process of compression or tension of the plurality of springs 176, at least one spring of the plurality of springs 176 is moved in a predetermined direction A bending motion may occur. At this time, the rear portion of the piston 130 can be moved in the radial direction at a position corresponding to the tolerance C2. In this process, the freedom of movement of the spring 176 is secured.

Particularly, since the gas bearing is formed on the front portion of the cylinder 120 forming the relatively high pressure and relatively small on the rear portion thereof, the movement of the piston 130 due to the degree of freedom of the spring 176, Can be made more easily at the rear side of the housing 120.

A first chamfered portion (301) for securing the degree of freedom of the spring (176) is formed at a rear portion of the cylinder (120). The first chamfered portion 301 extends obliquely outwardly in the radial direction from the rear end of the depressed portion 300. The inner diameter of the cylinder 120 in which the first chamfered portion 301 is formed is larger than the inner diameter of the cylinder 120 in which the depressed portion 300 is formed.

At the rear portion of the frame 110, a second chamfered portion 114 is formed. The second chamfered portion 114 is formed to be inclined from the frame 110 in the outer radial direction.

The depressed portion 300, the first chamfered portion 301 and the second chamfered portion 114 are provided on the inner circumferential surface of the cylinder 120 corresponding to the rear portion of the piston 130, It is possible to secure the degree of freedom of the piston 176 and to allow the piston 130 to move over a certain level, thereby reducing the stress applied to the spring 176 and preventing wear and tear. Therefore, the depressed portion 300 can be referred to as a "guide device" for securing the degree of freedom of the spring 176. [

FIG. 10 is a view showing a coupling structure of a motor assembly and a frame according to an embodiment of the present invention, FIG. 11 is a view showing a coupling structure of a back cover and a spring according to an embodiment of the present invention, 1 is a view showing a coupling structure of a supporter and a spring according to an embodiment.

10 to 11, a linear compressor 100 according to an embodiment of the present invention includes a cylinder 120, a cylinder 120 disposed to surround the cylinder 120, A motor assembly 140 disposed to surround the outer side of the frame body 111 of the frame 110 and a stator cover 149 supporting the motor assembly 140 .

The motor assembly 140 includes outer stator 141, 143, 145 fixed to the frame 110 so as to surround the cylinder 120. The outer states 141, 143, and 145 may be spaced apart from each other.

The stator cover 149 is integrally formed with the cover main body 149a and the cover main body 149a and extends between the plurality of outer stator 141, And a first support leg 149b supported by the first support legs 115.

The linear compressor 100 further includes a supporter 137 for supporting the piston 130 and a back cover 170 spring-coupled to the supporter 137.

The plurality of springs 176 are provided with a first spring 176a provided between the supporter 137 and the stator cover 149 and a second spring 176b provided between the supporter 137 and the back cover 170 A second spring 176b is included. For example, six of the first springs 176a may be provided, and six of the second springs 176b may be provided.

The first spring 176a may be supported on one side of the supporter 137 and the second spring 176b may be supported on the other side of the supporter 137. [ For example, the one surface may be the front surface of the supporter 137, and the other surface may be the back surface of the supporter 137.

The supporter 137 includes a first spring engagement portion 137a to which the first spring 176a and the second spring 176b are coupled.

The stator cover 149 is provided with a second support leg 149c protruding from the cover body 149a in the other direction and coupled to the back cover 170 and a second support leg 149c provided on the cover body 149a, And a second spring engaging portion 149d to which the one spring 176a is engaged. The first support leg 149a and the second support leg 149c may extend in opposite directions from the cover body 149a.

The back cover 170 includes a third spring coupling portion 170a to which the second spring 176b is coupled.

The plurality of first springs 176a extending to the stator cover 149 and the plurality of second springs 176b extending to the back cover 170 are provided on the basis of the supporter 137, A resonance motion of the piston 130 can be induced.

Hereinafter, the flow of the refrigerant and the action of the piston during operation of the linear compressor will be described.

FIG. 13 is a cross-sectional view illustrating a refrigerant flowing state of a linear compressor according to an embodiment of the present invention, and FIG. 14 is a view showing a state of operation of a cylinder and a piston when a linear compressor according to an embodiment of the present invention is operated.

First, referring to FIG. 13, the refrigerant flow in the linear compressor according to the present embodiment will be briefly described.

Referring to FIG. 13, the refrigerant flows into the interior of the shell 101 through the suction portion 104 and flows into the suction muffler 150 through the suction guide portion 155.

The refrigerant flows into the second muffler 153 via the first muffler 151 of the suction muffler 150 and flows into the interior of the piston 130. [ In this process, the suction noise of the refrigerant can be reduced.

On the other hand, the refrigerant can be filtered through the first filter 310 provided in the suction muffler 150, and the foreign matter having a predetermined size (25 mu m) or more can be filtered.

The refrigerant passing through the suction muffler 150 and existing in the piston 130 is sucked into the compression space P through the suction hole 133 when the suction valve 135 is opened.

When the refrigerant pressure in the compression space P becomes equal to or higher than the discharge pressure, the discharge valve 161 is opened and the refrigerant is discharged to the discharge space of the discharge cover 160 through the opened discharge valve 161, Flows to the discharge portion 105 through the loop pipe 165 coupled to the compressor 160 and is discharged to the outside of the compressor 100.

At least a portion of the refrigerant in the discharge space of the discharge cover 160 flows through the space existing between the cylinder 120 and the frame 110, that is, the flow space 210. The refrigerant flows toward the outer peripheral surface of the cylinder body 121 via the flow space formed between the inner peripheral surface of the insertion portion 117 of the frame 110 and the outer peripheral surface of the cylinder flange portion 125 of the cylinder 120 Can flow.

The refrigerant can pass through the second filter 320 interposed between the seating surface 127 of the cylinder flange portion 125 and the seating portion 113 of the frame 110. In this process, (2 탆) or more can be filtered. The oil in the refrigerant can be adsorbed to the second filter 320.

The refrigerant having passed through the second filter 320 flows into a plurality of gas inflow portions 122 formed on the outer circumferential surface of the cylinder body 121. As the refrigerant passes through the third filter 330 provided in the gas inlet 122, the foreign matter having a predetermined size (1 μm or more) contained in the refrigerant can be filtered, and the oil contained in the refrigerant can be adsorbed have.

The refrigerant that has passed through the third filter 330 flows into the cylinder 120 through the nozzle unit 123 and is positioned between the inner circumferential surface of the cylinder 120 and the outer circumferential surface of the piston 130, 130) from the inner circumferential surface of the cylinder 120 (gas bearing).

The diameter of the inlet portion 123a of the nozzle portion 123 is larger than the diameter of the outlet portion 123b so that the sectional area of the refrigerant flowing in the nozzle portion 123, . For example, the diameter of the inlet portion 123a may be at least two times the diameter of the outlet portion 123b.

As such, the high-pressure gas refrigerant acts as a bearing for the reciprocating piston 130 bypassed into the cylinder 120, thereby reducing wear between the piston 130 and the cylinder 120 . By not using the oil for the bearing, even if the compressor 100 is operated at a high speed, friction loss due to oil can be prevented.

Further, by providing a plurality of filters on the path of the refrigerant flowing in the compressor 100, the foreign matter contained in the refrigerant can be removed, thereby improving the reliability of the refrigerant serving as the gas bearing. Accordingly, it is possible to prevent a phenomenon that the piston 130 or the cylinder 120 is abraded by foreign matter contained in the refrigerant.

Further, by removing the oil contained in the refrigerant by the plurality of filters, frictional loss due to oil can be prevented from occurring.

On the other hand, the refrigerant flowing in the flow space part 210 acts on the sealing member 200. That is, the pressure of the refrigerant acts on the sealing member 200, and the sealing member 200 moves from the sealing pocket 220 to the first inclined portion 128 of the cylinder 120 and the frame 110, To the point between the second inclined portions 113 of the second inclined portion 113.

The sealing member 200 is in close contact with the cylinder 120 and the frame 110 so that the spacing space between the cylinder 120 and the frame 110, Thereby sealing the space between the second inclined portions 113. Therefore, the refrigerant in the flow space 210 can be prevented from leaking to the outside through the spaced space between the cylinder 120 and the frame 110.

When the driving of the linear compressor 100 is stopped, the pressure of the refrigerant acting on the sealing member 200 is released, so that the adhesion between the sealing member 200 and the cylinder 120 and the frame 110 . As a result, the sealing member 200 is freely movable in the sealing pocket 220, for example, in a state of being spaced apart from the first inclined portion 128 and the second inclined portion 113 ).

According to such an operation, since the sealing member 200 can be brought into close contact with the cylinder 120 and the frame 110 only when the compressor 100 is driven to perform the sealing of the flow space portion 210, The force applied to the cylinder 120 from the member 200 can be reduced. Therefore, deformation of the cylinder 120 can be prevented.

Since the sealing member 200 can be moved in the sealing pocket 220, interference between the sealing member 200 and the frame 110 can be prevented when the cylinder 120 and the frame 110 are assembled. . As a result, assembly of the cylinder 120 and the frame 110 can be facilitated.

A shortest distance between the outer circumferential surface of the piston 130 and the depression 300, that is, a first tolerance C2, is formed in the inner circumferential surface of the cylinder 120, That is, the second clearance C1, from the inner circumferential surface of the cylinder 120 where the piston 300 is not provided, to the outer circumferential surface of the piston 130. [ The inner circumferential surface of the inner circumferential surface of the cylinder 120 in which the depressed portion 300 is formed is referred to as a "first inner circumferential surface ", a portion where the depressed portion 300 is not formed, Quot; second inner peripheral surface ".

The shortest distance between the inner circumferential surface of the rear portion of the frame 110 and the outer circumferential surface of the piston 130 or the third tolerance C3 may be larger than the first and second tolerances C1 and C2 . The diameter of the inner circumferential surface of the rear portion of the frame 110 in which the third tolerance C3 is formed may be larger than the diameter of the inner circumferential surface of the rear portion of the cylinder 120 in which the second tolerance C2 is formed have.

The gas bearing can be somewhat alleviated by the configuration of the depression 300 and the first and second chamfered portions 301 and 114 and the tolerance of the frame 110 to the piston 130, A certain degree of radial movement is generated inside the cylinder 120 and the degree of freedom of the spring 176 can be secured. As a result, stress acting on the spring 176 can be reduced, and abrasion or breakage can be prevented.

100: Linear compressor 101: Shell
110: frame 111: frame body
112: pocket forming portion 113: second inclined portion
115: cover coupling portion 117:
120: cylinder 121: cylinder body
122: gas inlet part 123: nozzle part
123a: inlet portion 123b: outlet portion
125: cylinder flange part 127: seat face
128: first inclined portion 130: piston
140: Motor assembly 149: State cover
150: Suction muffler 160: Discharge cover
161: Discharge valve 162: Valve spring
170: back cover 171, 172: leaf spring
176: spring 200: sealing member
210: flow space part 220: sealing pocket
300: depression 310: first filter
320: second filter 330: third filter

Claims (17)

A shell provided with a suction portion;
A cylinder disposed inside the shell and forming a compression space for the refrigerant;
A piston provided to be axially reciprocable within the cylinder;
At least one spring for inducing a resonant motion of the piston; And
And a guide device formed on an inner circumferential surface of the cylinder to increase the degree of freedom of movement of the spring. The method according to claim 1,
In the guide device,
And a depression that is recessed from the inner circumferential surface of the cylinder. The method according to claim 1,
Further comprising a discharge valve provided in a front portion of the cylinder for selectively discharging the refrigerant in the compression space of the refrigerant,
And the guide device is formed on the inner peripheral surface of the rear portion of the cylinder. The method according to claim 1,
On the inner peripheral surface of the cylinder,
A first inner circumferential surface on which the guide device is formed; And
And a second inner circumferential surface extending forward from the first inner circumferential surface. 5. The method of claim 4,
The shortest distance (C2) between the first inner circumferential surface and the outer circumferential surface of the piston,
(C1) between the second inner peripheral surface and the outer peripheral surface of the piston. 6. The method of claim 5,
Wherein the shortest distance (C3) between the inner peripheral surface of the rear portion of the frame and the outer peripheral surface of the piston is larger than the C1 and C2. 3. The method of claim 2,
A first chamfered portion extending obliquely in an outer radial direction from a rear end of the depressed portion; And
And a second chamfered portion provided at a rear portion of the frame and extending obliquely in an outer radial direction. The method according to claim 1,
And a nozzle portion formed in the cylinder and introducing at least a part of refrigerant discharged from the discharge valve through a space between the piston and the cylinder. 9. The method of claim 8,
A motor assembly for generating a driving force;
A stator cover for supporting the motor assembly;
A supporter for supporting the piston; And
Further comprising a back cover provided on one side of the supporter. 10. The method of claim 9,
In the spring,
A plurality of first springs provided between the stator cover and the supporter; And
And a plurality of second springs provided between the supporter and the back cover. 11. The method of claim 10,
Wherein the first spring and the second spring each include six springs. The method according to claim 1,
A flow space part formed between the cylinder and the frame, in which at least a portion of the refrigerant discharged through the discharge valve flows;
A sealing pocket communicating with the flow space portion; And
And a sealing member movably installed in the sealing pocket for sealing a space between the frame and the cylinder. 13. The method of claim 12,
Wherein the outer peripheral surface of the cylinder in which the sealing member is installed and the inner peripheral surface of the cylinder in which the guide device is installed are formed at positions facing each other. A shell provided with a suction portion;
A cylinder disposed inside the shell and forming a compression space for the refrigerant;
A piston provided to be axially reciprocable within the cylinder;
A discharge valve provided at one side of the cylinder for selectively discharging compressed refrigerant in a compression space of the refrigerant;
A flow space part formed between the cylinder and the frame, in which at least a portion of the refrigerant discharged through the discharge valve flows;
A nozzle unit formed in the cylinder and introducing the refrigerant in the flow space part to the inside of the cylinder;
A plurality of springs for applying an elastic force to the piston; And
And a depressed portion formed to be recessed on an inner circumferential surface of the cylinder and increasing the tolerance between the inner circumferential surface of the cylinder and the outer circumferential surface of the piston. 15. The method of claim 14,
Wherein the discharge valve is coupled to a front surface of the cylinder, and the depression is formed in a rear portion of the cylinder. 15. The method of claim 14,
And the radial width (C2) of the depression is formed to be larger than the radial width (C1) of the flow space. 15. The method of claim 14,
Wherein the depression comprises:
Wherein a rear portion of the piston is allowed to move in a radial direction of the cylinder, thereby increasing the degree of freedom of the plurality of springs.

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