Linear compressor

Abstract

An embodiment of the present invention can comprise: a shell; a first support device for supporting a first axial side of a main body between the shell and the main body inside the shell; and a second support device for supporting a second axial side of the main body between the shell and the main body inside the shell. The main body includes: a rear cover connected to the first support device; a frame supported by the second support device; a cylinder which is supported inside the frame and into which a piston moving back and forth in the axial direction is inserted; a stator which is fixed to the frame and which has a portion surrounding the cylinder; and a resonant spring placed between the stator and the rear cover, wherein the piston can operate in a region in which the speed coefficient (alpha value) of the electric equation of the compressor is 70% or more.

Description

Linear compressor

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

[0002] In a reciprocating compressor, a compression space for compressing the working gas is formed between the piston and the cylinder, and the piston compresses the refrigerant introduced into the compression space as it moves in a straight line back and forth inside the cylinder.

[0003] Recently, among the aforementioned reciprocating compressors, many linear compressors have been developed that are simple in structure and can improve compression efficiency without mechanical losses occurring when converting the motor's rotational motion into linear motion, by directly connecting the piston to a drive motor that performs reciprocating linear motion.

[0004] Generally, a linear compressor is configured such that a piston moves in a reciprocating linear motion inside a cylinder driven by a linear motor within a sealed shell, drawing in and compressing refrigerant before discharging it. The position of the piston can be determined through calculation. If the calculation error of the piston increases, it causes problems with the operational reliability of the linear compressor.

[0005] The present invention proposes a linear compressor that prevents a decrease in the speed coefficient (alpha value) of the linear compressor.

[0006] The present invention proposes a linear compressor capable of reducing the stroke calculation error by improving the alpha value.

[0007] The present invention proposes a linear compressor that improves the occurrence of collisions between members through stable stroke calculation.

[0008] The present invention proposes a linear compressor having a configuration that enables the linear compressor to operate in the alpha value optimal region.

[0009] The present invention proposes a linear compressor that optimizes the center of the magnet, the initial placement of the magnet, and the stroke area.

[0010] An embodiment of the present invention may include a shell; a first support device that supports a first axial side of a body inside the shell between the shell and the body; and a second support device that supports a second axial side of a body inside the shell between the shell and the body.

[0011] The main body comprises: a rear cover connected to the first support device; a frame supported by the second support device; a cylinder supported inside the frame and into which a piston that reciprocates in the axial direction is inserted; a stator fixed to the frame and having a portion surrounding the cylinder; and a resonant spring placed between the stator and the rear cover, and the piston may be configured to operate in a region where the speed coefficient (alpha value) of the compressor's electrical equation is 70% or more of the maximum alpha value (αmax).

[0012] The region where the permanent magnet reciprocates may have a distance of 0.4 or more between the rear end of the permanent magnet and the center of the pole of the stator.

[0013] The distance between the front end of the permanent magnet and the center of the pole of the stator may be 0.4 or greater.

[0014] The stator may include an outer stator fixed to the frame and positioned to surround the cylinder; and an inner stator spaced apart from the inner side of the outer stator. It may include a permanent magnet located in the space between the outer stator and the inner stator.

[0015] The initial arrangement, which is the distance between the axial center of the permanent magnet and the pole center of the outer stator, may be in the range of 2.00 to 5.00.

[0016] The initial value, which is the distance from the front end of the cylinder to the front end of the piston, may be in the range of 6.0-3.0.

[0017] The stroke of the above piston can be 16 mm to 14.5 mm.

[0018] The length of the magnet frame supporting the above permanent magnet may be 46-49 mm.

[0019] The above piston may have a forward travel distance smaller than the backward travel distance from the initial position.

[0020] The above alpha value can be operated in a region of 80% or more of the maximum alpha value (αmax).

[0021] The region where the above alpha value is 80% or more of the maximum alpha value (αmax) is the alpha value appropriate region, and in the alpha value appropriate region, the alpha value may be a linear region.

[0022] The above alpha value optimal region may be such that the distance from the center of the permanent magnet to the bottom dead center is shorter than the distance from the center of the permanent magnet to the top dead center.

[0023] The distance from the center of the permanent magnet to the bottom dead center may be 7.9 mm. The distance from the center of the permanent magnet to the top dead center may be 8.0 mm.

[0024] The above alpha value may be calculated by the control unit or stored in memory.

[0025] An embodiment may include a rear cover supported on a first side in the axial direction; a frame supported on a second side in the axial direction; a cylinder supported inside the frame and into which a piston reciprocating in the axial direction is inserted; an outer stator arranged to surround the cylinder fixed to the frame; an inner stator spaced apart from the inner side of the outer stator; and a permanent magnet located in the space between the outer stator and the inner stator. The initial arrangement, which is the distance between the axial center of the permanent magnet and the pole center of the outer stator, may be in the range of 2.00 to 5.00.

[0026] The initial value, which is the distance from the front end of the cylinder to the front end of the piston, may be in the range of 6.0 to 3.0. The stroke of the piston may be 16 mm to 14.5 mm. The length of the magnet frame supporting the permanent magnet may be 46 to 49 mm.

[0027] The above piston may have a forward travel distance smaller than the backward travel distance from the initial position.

[0028] The above piston can be configured to operate in an appropriate alpha value range where the speed coefficient (alpha value) of the compressor's electric equation is 80% or more of the maximum alpha value (αmax).

[0029] An embodiment may be configured to operate in an appropriate alpha value range where the speed coefficient (alpha value) of the compressor's electrical equation is greater than or equal to a predetermined value by performing a stroke such that the distance from the center of the permanent magnet to the bottom dead center is shorter than the distance from the center of the permanent magnet to the top dead center. The distance from the center of the permanent magnet to the bottom dead center may be 7.9 mm. The distance from the center of the permanent magnet to the top dead center may be 8.0 mm.

[0030] The initial arrangement, which is the distance between the axial center of the permanent magnet and the pole center of the outer stator, may be in the range of 2.00 to 5.00. The initial value, which is the distance between the front end of the cylinder and the front end of the piston, may be in the range of 6.0 to 3.0. The stroke of the piston may be 16 mm to 14.5 mm.

[0031] According to an embodiment of the present invention, by operating the linear compressor with a high alpha value, the advantage of improved operational stability of the linear compressor can be obtained.

[0032] According to the present invention, the calculation error of the stroke is reduced, thereby preventing collision of members and improving the operational reliability of the linear compressor. In particular, there is an advantage in that the calculation error of the piston's bottom dead center is reduced.

[0033] According to the present invention, by limiting the stroke to a first distance from the center of the permanent magnet to the bottom dead center and a second distance from the center of the permanent magnet to the top dead center, the linear compressor can be operated in a stable region. This can be referred to as the alpha value optimal region.

[0034] According to the present invention, the stability of stroke calculation can be high in the alpha value optimal region. Accordingly, the linear compressor can be stably controlled. In the alpha value optimal region, the stroke calculation error is reduced, and collisions between parts can be prevented.

[0035] FIG. 1 is a cross-sectional view of a linear compressor according to an embodiment of the present invention.

[0036] Figure 2 is a cross-sectional view taken along 2-2 of Figure 1.

[0037] FIG. 3 is a perspective view of an assembly in which a resonant spring and a support are connected.

[0038] FIG. 4 is a drawing showing the supporter, where a is an axial plan view, and b and c are perspective views seen from different angles.

[0039] FIG. 5 is a drawing illustrating the alignment direction of the resonant springs, wherein a is a drawing of the first resonant spring viewed in the axial direction (rear), b is a drawing of the second resonant spring viewed in the axial direction (forward), and c is a drawing showing the two covers of the front and rear in a single drawing.

[0040] Figure 6 is a graph showing the relationship between the alpha value and the initial position, where a is a comparative example and the first experimental example, and b is a diagram showing the second experimental example and the third experimental example.

[0041] Figure 7 is a drawing showing the arrangement of the initial batch according to the third experimental example.

[0042] Figure 8 is a graph of alpha values ​​for the distance from the center of the permanent magnet to the top dead center and bottom dead center.

[0043] Figure 9 is a diagram showing the top dead center and bottom dead center of the alpha value of a linear compressor in the 70% region of the maximum alpha value (αmax).

[0044] Figure 10 is a graph explaining the alpha value, where a is a graph comparing the actual stroke and the calculated stroke, and b is a graph of the alpha value.

[0045] Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that in assigning reference numerals to the components of each drawing, the same components are given the same reference numeral whenever possible, even if they are shown in different drawings. Furthermore, in describing the embodiments of the present invention, if it is determined that a detailed description of related known components or functions would hinder understanding of the embodiments of the present invention, such detailed description is omitted.

[0046] In addition, terms such as first, second, A, B, (a), (b), etc., may be used when describing the components of the embodiments of the present invention. These terms are intended only to distinguish the components from other components, and the essence, order, or sequence of the components is not limited by the terms. Where it is stated that a component is "connected," "combined," or "connected" to another component, it should be understood that the component may be directly connected or connected to the other component, but that another component may also be "connected," "combined," or "connected" between each component.

[0047] FIG. 1 is a cross-sectional view of a linear compressor according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along 2-2 of FIG. 1.

[0048] Referring to FIGS. 1 and 2, a linear compressor (10) according to an embodiment of the present invention may include a shell (11) and a first shell cover (12) and a second shell cover (13) coupled to both sides of the shell (11). In a broad sense, the first shell cover (12) and the second shell cover (13) may be understood as components of the shell (11).

[0049] The shell (11) has a roughly cylindrical shape and can be arranged in a horizontally lying position or in an axially lying position. Based on FIG. 1, the shell (11) is extended horizontally and may have a somewhat lower height in the radial direction.

[0050] Since the linear compressor (10) can have a low height, for example, when the linear compressor (10) is installed on the base of the machine room of a refrigerator, there is an advantage that the height of the machine room can be reduced.

[0051] The above linear compressor (10) may include a plurality of pipes that are provided in the shell (11) or shell cover (12, 13) and can suck in, discharge, or inject refrigerant.

[0052] The plurality of pipes may include a suction pipe (14) that allows the refrigerant to be sucked into the interior of the linear compressor (10). The suction pipe (14) may be connected to the first shell cover (12). The refrigerant may be sucked into the interior of the linear compressor (10) along the axial direction through the suction pipe (14).

[0053] The plurality of pipes may further include a discharge pipe (not shown) for allowing compressed refrigerant to be discharged from the linear compressor (10) and a process pipe (not shown) for replenishing refrigerant to the linear compressor (10). For example, the discharge pipe and the process pipe may be connected to the outer surface of the shell (11).

[0054] Support devices (20, 90) that support the main body of the linear compressor (10) may be included on both sides of the shell (11). The support devices (20, 90) may include a first support device (20) that is coupled to the first shell cover (12) and elastically supports the main body of the linear compressor (10).

[0055] Here, the main body of the compressor refers to a component provided inside the shell (11), and may include, for example, a drive unit that moves back and forth and a support unit that supports the drive unit. The drive unit may include a piston (70), a permanent magnet (also called a magnet) (45), a supporter (33), and an intake muffler (25), etc. And, the support unit may include a resonant spring (30), a rear cover (31), a stator cover (32), a first support device (20), and a second support device (90), etc.

[0056] The first support device (20) may include a support bracket (21a) communicating with the suction pipe (14) and a support spring (21b) coupled to the support bracket (21a) and supported by the rear cover (31).

[0057] The above support device may include a second support device (90) that is coupled to the second shell cover (13) and supports the discharge cover assembly.

[0058] The linear compressor (10) may include a frame (50) provided inside the compressor shell (11) and a cylinder (60) inserted inside the frame (50). The cylinder (60) and the frame (50) may be made of a metal material, for example, aluminum or an aluminum alloy.

[0059] The above linear compressor (10) includes a piston (70) that moves in a reciprocating linear motion inside the cylinder (60). The piston (70) can move in an axial direction.

[0060] The above linear compressor (10) may further include a suction muffler (25) coupled to the piston (70) to reduce noise generated from the refrigerant sucked through the suction pipe (14).

[0061] The refrigerant sucked in through the suction pipe (14) flows into the interior of the piston (70) via the suction muffler (25). For example, as the refrigerant passes through the suction muffler (25), the flow noise of the refrigerant can be reduced. The suction muffler (25) may be composed of a plurality of mufflers combined.

[0062] The above linear compressor (10) may include a motor assembly (41, 43, 45) as a linear motor that provides driving force to the piston (70).

[0063] The motor assembly may include an outer stator (41) fixed to the frame (50) and arranged to surround the cylinder (60), an inner stator (43) spaced apart from the inner side of the outer stator (41), and a permanent magnet (45) located in the space between the outer stator (41) and the inner stator (43).

[0064] A stator cover (32) is provided on one side of the outer stator (41). That is, one side of the outer stator (41) is supported by the frame (50), and the other side can be supported by the stator cover (32).

[0065] The permanent magnet (45) can move in a linear reciprocating motion due to the mutual electromagnetic force between the outer stator (41) and the inner stator (43). The permanent magnet (45) may be composed of a single magnet having one pole or may be composed of a plurality of magnets having three poles combined.

[0066] The above permanent magnet (45) can be installed in a magnet frame (46). The magnet frame (46) has a roughly cylindrical shape and can be positioned to be inserted into the space between the outer stator (41) and the inner stator (43).

[0067] The magnet frame (46) is coupled to the piston (70), and when the permanent magnet (45) reciprocates, the piston (70) can reciprocate in the axial direction together with the permanent magnet (45).

[0068] The linear compressor (10) may further include a supporter (33) that supports the piston (70). The supporter (33) is coupled to the rear side of the piston (730), and the muffler (25) may be positioned to pass through the inside thereof. The piston (70), the magnet frame (46), and the supporter (33) may be connected by a fastening member.

[0069] The linear compressor (10) may include a rear cover (31) that is coupled to the stator cover (32), extends rearward, and is supported by a first support device (20). The rear cover (31) may be spring-supported by the supporter (33).

[0070] The rear cover (31) may include a plurality of support legs that are coupled to the rear of the stator cover (32).

[0071] The linear compressor (10) may include an inlet guide (23) coupled to the rear cover (31) to guide the inflow of refrigerant into the intake muffler (25). At least a portion of the inlet guide (23) may be inserted into the inside of the intake muffler (25).

[0072] The above linear compressor (10) may further include a plurality of resonant springs (30) each having an adjusted natural frequency so that the piston (70) can resonate.

[0073] The plurality of resonant springs (30) may include a plurality of first resonant springs supported between the supporter (33) and the stator cover (32), and a plurality of second resonant springs supported between the supporter (33) and the rear cover (31). Through the action of the plurality of resonant springs (30), stable movement of the drive unit reciprocating inside the linear compressor (10) is performed, and vibration or noise generation due to the movement of the drive unit can be reduced.

[0074] The frame (50) is understood as a configuration for fixing the cylinder (60), and, for example, the cylinder (60) can be pressed into the inside of the frame (50). The frame (50) can be arranged to surround the cylinder (60).

[0075] The above frame (50) has a hollow cylindrical shape and includes a frame body (51) that forms a space into which the cylinder (60) is inserted, and a frame flange (52) that extends radially from the front part of the frame body (51).

[0076] A cylinder sealing member (82) may be provided between the frame (50) and the cylinder (60). By means of the cylinder sealing member (82), the adhesion force may be increased during the press-fitting process between the frame (50) and the cylinder (60).

[0077] The cylinder sealing member (82) has a ring shape and can be installed on the inner surface of the frame (50) on which the flange (62) of the cylinder (60) is seated.

[0078] The above frame (50) may have a bearing channel (58) formed therein that extends axially from the frame flange (52) toward the frame body. A refrigerant acting as a gas bearing among the compressed discharge gas may flow through the bearing channel (58).

[0079] The refrigerant acting as the gas bearing is supplied between the cylinder body (61) and the piston (70) of the cylinder (60) to cause the piston (70) to float inside the cylinder (60).

[0080] Defines the direction.

[0081] "Axial direction" can be understood as the direction in which the piston (70) reciprocates, i.e., the up-and-down direction in FIG. 2. Among the "axial directions," the direction from the piston (70) toward the compression space (P) of the cylinder (60), i.e., the direction in which the refrigerant flows, is defined as "forward," and the opposite direction is defined as "rear." When the piston (70) moves forward, the compression space (P) is reduced, and when it moves rearward, the compression space (P) can be expanded.

[0082] On the other hand, "radial direction" is a direction perpendicular to the direction in which the piston (70) reciprocates, and can be understood as the horizontal direction of FIG. 2.

[0083] A compression space (P) in which refrigerant is compressed by the piston (70) may be formed inside the cylinder (60). An intake port for introducing refrigerant into the compression space (P) is formed at the front of the piston (70), and an intake valve (75) for selectively opening the intake port may be provided in front of the intake port.

[0084] The above suction port may be provided in multiple numbers. The multiple suction ports are spaced apart in the circumferential direction of the piston (70), and refrigerant is introduced into the compression space (P) through the multiple suction ports. The suction valve (75) may be connected to the front of the piston (70) by a fastening member (78), such as a screw or a bolt.

[0085] In front of the compression space (P), a discharge cover assembly (100, 200, 300) forming a discharge space for the refrigerant discharged from the compression space (P) may be provided. The discharge cover assembly (100, 200, 300) may be positioned in front of the frame (50).

[0086] The above discharge cover assembly may include a first discharge cover (100) and a second discharge cover (200) supported on the front of the frame (50). The first discharge cover (100) may be positioned inside the second discharge cover (200).

[0087] For example, the first discharge cover (100) can be press-fitted and fixed to the second discharge cover (200). The cover flange (not shown) of the first discharge cover (100) can be press-fitted into the inner circumference of the cover flange (not shown) of the second discharge cover (200). By press-fitting the first discharge cover (100) into the second discharge cover (200), the first and second discharge covers (100, 200) can be firmly fixed.

[0088] The internal space of the first discharge cover (100) and the internal space of the second discharge cover (200) can form a discharge path (also referred to as a "discharge room") for the refrigerant discharged from the compression space (P). For example, the refrigerant discharged from the compression space (P) can flow through the internal space of the first discharge cover (100), be discharged from the first discharge cover (100), and flow into the internal space of the second discharge cover (200).

[0089] The refrigerant flowing through the discharge chamber of the first discharge cover (100) and the discharge chamber of the second discharge cover (200) can be in a high-temperature gaseous state. The high-temperature heat can be transferred to the frame (50) supporting the first and second discharge covers (100, 200).

[0090] If high-temperature heat is excessively transferred to the frame (50), that heat becomes a factor that raises the temperature (suction temperature) of the refrigerant sucked into the compression space (P) of the cylinder.

[0091] If the above suction temperature increases, the volume of refrigerant per unit mass, that is, the specific volume of the refrigerant, increases, causing a decrease in volumetric efficiency, and consequently, a problem may arise in which the compression efficiency of the compressor decreases.

[0092] To prevent such problems, the first discharge cover (100) and the second discharge cover (200) according to an embodiment of the present invention may be composed of a material having a low heat transfer coefficient. The material having a low heat transfer coefficient may be a non-metallic material.

[0093] The first discharge cover (100) and the second discharge cover (200) may include plastic.

[0094] The first discharge cover (100) and the second discharge cover (200) may be made of the same plastic material, for example, polyamide (PA66) as a type of heat-resistant engineering plastic.

[0095] By making the first discharge cover (100) of the above-mentioned first discharge cover (100) of a plastic material, the amount of high-temperature heat within the first discharge cover (100) that is directly transferred to the frame (50) supporting the first discharge cover (100) or transferred to the second discharge cover (200) that is press-fitted to the first discharge cover (100) can be reduced.

[0096] By making the second discharge cover (200) of the above-mentioned second discharge cover (200) of a plastic material, the amount of high-temperature heat within the second discharge cover (200) that is directly transferred to the frame (50) supporting the second discharge cover (200) or transferred to the first discharge cover (100) that is press-fitted to the second discharge cover (200) can be reduced.

[0097] Ultimately, it is possible to prevent excessive transfer of high-temperature heat from the refrigerant present in the discharge chamber within the first and second discharge covers (100, 200) to the frame (50). Accordingly, the suction temperature of the refrigerant can be reduced and the compression efficiency of the compressor can be improved.

[0098] Since the first and second discharge covers (100, 200) are made of a relatively lightweight plastic material, there is a possibility that vibration and noise may occur in the first and second discharge covers (100, 200) due to the high-pressure refrigerant discharged from the compression space (P).

[0099] To prevent such problems, the discharge cover assembly according to the present embodiment may include a damping member (180) for reducing vibration of the first and second covers (100, 200).

[0100] The damping member (180) is mounted in the recess of the first discharge cover (100), and the inner wall of the second discharge cover (200) may be configured to support or press the damping member (180).

[0101] The damping member (180) can offset the magnitude of vibration and noise transmitted from one of the first and second discharge covers (100, 200) to the other. In particular, when the discharge valve (191) is turned on and off, the effect of reducing the magnitude of the valve tapping sound that is frictionally applied to the cylinder (60) can be expected.

[0102] In a structure in which the damping member (180) is mounted on the recess (140) of the first discharge cover (100), the recess (140) and the damping member (180) form a flow path through which refrigerant flows, and the flow path can be understood as defining a pulsation path to reduce pulsation that occurs when high-pressure discharge gas flows.

[0103] The above discharge cover assembly may include a third discharge cover (300) that supports the second discharge cover (200).

[0104] The third discharge cover (300) may have a roughly ring shape and be positioned to surround the rear portion of the second discharge cover (200). The third discharge cover (300) may support the cover flange (250) of the second discharge cover (200).

[0105] The third discharge cover (300) can be supported on the front of the frame (50).

[0106] The third discharge cover (300) is fastened to the frame flange (52) by a fastening member (not shown), and the front surface of the frame flange (52) can come into surface contact with the rear surface of the third discharge cover (300).

[0107] A frame fastening hole (55) into which the fastening member is inserted may be formed in the frame flange (52). Multiple frame fastening holes (55) may be formed. A cover fastening hole (335) may be formed in the third discharge cover (300) at a position corresponding to the frame fastening hole (55).

[0108] The above fastening member can be fastened to the frame fastening hole (55) and the cover fastening hole (335) to fix the frame (50) and the third discharge cover (300).

[0109] The third discharge cover (300) may be made of a material different from the first discharge cover (100) and the second discharge cover (200). The third discharge cover (300) may be made of a material having greater strength than the first discharge cover (100) and the second discharge cover (200).

[0110] The third discharge cover (300) may be made of a metal material, for example, aluminum. Since the third discharge cover (300) is connected to the frame (50) by the fastening member, a failure in connection may occur if the amount of deformation increases due to high heat. Therefore, the third discharge cover (300) may be made of a metal material so that the amount of thermal deformation is not large.

[0111] A frame sealing member (81) capable of increasing bonding strength and preventing refrigerant leakage may be provided at the portion where the second discharge cover (200) and the frame (50) are in surface contact. The frame sealing member (81) has a ring shape and may be installed between the rear surface of the second discharge cover (200) and the front surface of the frame (50).

[0112] The discharge cover assembly may include a discharge valve assembly (190). The discharge valve assembly may include a discharge valve (191) and a spring assembly (193, 195) that provides elastic force to the discharge valve (191) in a direction that brings it into close contact with the front end of the cylinder (60).

[0113] The above spring assembly (193, 195) may include a valve spring (193) composed of a leaf spring and a spring bracket (195) that surrounds the edge of the valve spring (193) to support the valve spring (193).

[0114] The discharge valve (191) is coupled to the central part of the valve spring (193). When the discharge valve (191) is opened, the refrigerant compressed in the compression space (P) of the cylinder (60) is discharged and flows into the internal space of the first discharge cover (100). When the discharge of the refrigerant is completed, the discharge valve (191) can be closed by the restoring force of the valve spring (193).

[0115] The above spring bracket (195) can be seated on the inner surface of the first discharge cover (100).

[0116] A sealing bracket (197) may be installed around the front end of the cylinder (60). For example, the sealing bracket (197) may have a ring shape. The sealing bracket (197) may be seated on the front flange of the cylinder (60) and supported on the rear of the spring bracket (195).

[0117] A bracket sealing member (83) may be provided between the sealing bracket (197) and the flange of the cylinder (60). The bracket sealing member (83) is provided on the contact surface between the sealing bracket (197) and the flange of the cylinder (60), and can prevent refrigerant from leaking through the space between the cylinder (60) and the spring assembly (193, 195).

[0118] Below, a resonant spring and a configuration related to the resonant spring according to an embodiment are described in detail.

[0119] FIG. 3 is a perspective view of an assembly in which a resonant spring and a support are connected.

[0120] Refer to FIG. 3. The resonant spring (30) may include a first resonant spring (301) supported between the supporter (33) and the stator cover (32). The resonant spring (30) may include a second resonant spring (302) supported between the supporter (33) and the rear cover (31). The resonant spring may have a portion extending in the axial direction. The resonant spring may all extend in the axial direction.

[0121] The first resonant spring (301) may include at least two resonant springs that are spaced equally apart in the circumferential direction. Here, the circumferential direction may be based on the center of the axial direction. All elements of the first resonant spring (301) may have the same spacing. An element may refer to each resonant spring that can be provided individually. The first resonant spring (301) may be provided with three elements (301a), (301b), and (301c). The first resonant spring (301) may include three elements of the first resonant spring (301a), (301b), and (301c) provided at equal intervals.

[0122] As explained, the first resonant spring (301) may have all elements spaced equally apart. A typical first resonant spring consists of two springs forming a pair with a narrow first spacing, and three such pairs are provided. The three pairs have a wide second spacing. Consequently, it is difficult to analyze the behavior of the first resonant spring, and wind power loss in the surrounding mechanism may increase. In contrast, the elements of the resonant spring included in the first resonant spring (301) may be provided spaced equally apart in the axial direction. Accordingly, there is an advantage in that the behavior analysis is easy and wind power loss is reduced. This configuration may be the same for the second resonant spring. The prior art may ultimately have 12 springs.

[0123] The second resonant spring may have the same configuration and arrangement as the first resonant spring. For example, the second resonant spring (302) may include elements of three first resonant springs (302a)(302b)(302c) provided at equal intervals.

[0124] The second resonant spring (302) can be aligned axially with the first resonant spring (301). The second resonant spring (302) can support the same mechanical point axially with the first resonant spring (301). The second resonant spring (302) and the first resonant spring (301) can be superimposed on each other when viewed axially.

[0125] The extension axes provided by the extension directions of the first and second resonant springs may be multiple. There may be three extension axes. The extension axes may be arranged at equal intervals in the circumferential direction. All extension axes may be arranged at equal intervals. When viewed in the axial direction, the extension axes may be arranged in an equilateral triangle that is symmetrical to the left and right with respect to the direction of gravity.

[0126] The number of elements of the above-mentioned resonant spring can be reduced to 6 compared to the conventional arrangement of 12. Accordingly, the following technical advantages can be achieved.

[0127] First, by reducing the number of resonant spring elements to six, the structure is simplified and there is an advantage in that behavior analysis is easy.

[0128] Second, it has the advantage of not requiring a complex support structure to support the elements of the 12 conventional resonant springs.

[0129] Third, there is an advantage in that non-price losses (wind power losses) caused by friction between the gas containing the refrigerant and the moving parts are reduced.

[0130] Fourth, the weight of the movable part can be reduced to further reduce the above initial value. Accordingly, the low cooling efficiency can be improved. The movable part may include a supporter (33).

[0131] Fifth, reducing the weight of the moving parts can increase the design freedom of the linear compressor.

[0132] Sixth, if the number of elements in the resonant spring is reduced, the advantage of ultimately reducing material costs can be expected.

[0133] FIG. 4 is a drawing showing the supporter, where a is an axial plan view, and b and c are perspective views seen from different angles.

[0134] Refer to FIG. 4. The supporter (33) can connect the resonant spring (30) and the movable part. The supporter (33) can provide resonant spring seating portions (331)(332)(333). Three resonant spring seating portions can be provided. The rear end of an element of the first resonant spring and the front end of an element of the second resonant spring can each be seated on the resonant spring seating portions. The resonant spring seating portions can be positioned on the same axis as the extension axis that is positioned in the extension direction of the resonant spring.

[0135] The supporter (33) may include a first base (334) adjacent to the movable part. The first base may be directly connected to the movable part. Here, the movable part may include a piston. The base may move as one with the piston. The supporter (33) may provide a second base (335) radially inward of the first base. The supporter (33) may include a reinforcing part (339) connecting the first base and the second base. The first and second bases and the reinforcing part may support dynamic and static loads passing through the resonant spring as a single unit. The single unit may be shortened to "base." The sum of the dynamic load and the static load may be referred to as "load." Here, the single unit may be provided with high strength. The load of the resonant spring may be divided into three parts.

[0136] Each of the above-mentioned resonant spring mounting portions (331)(332)(333) can support the load of the resonant spring by dividing it into three parts. A large force can be applied between the resonant spring mounting portion and the single body. To connect the resonant spring mounting portion and the single body, an extension portion (336) extending in the axial direction may be included. A reinforcing rib connecting the extension portion (336) and the single body may be included. Here, the reinforcing rib may include first and second reinforcing ribs (337)(338).

[0137] The reinforcing ribs (337) (338) may be provided at the circumferential ends of the extension (336). The reinforcing ribs (337) (338) may support the entire force of the resonant spring. If the reinforcing ribs are not present, the extension may be damaged. This is because the entire load of the resonant spring may be applied instantaneously to any one of the three extensions.

[0138] The extension direction of any one of the above reinforcing ribs may not pass through the central axis of the piston. Accordingly, the empty space between the first and second bases can be made larger. Accordingly, the weight of the supporter can be reduced. In addition, the inner end and the outer end of the reinforcing part (339) can be made equal in size. According to this, the load-bearing capacity of the reinforcing part can be increased.

[0139] The two lines extending radially from the first and second reinforcing ribs (337) (338) may not meet in the inner region of the first base (334). The point where the two lines extending radially from the first and second reinforcing ribs (337) (338) meet the first base (334) may have a predetermined gap (W). Accordingly, an optimal combination of the load-bearing capacity of the reinforcing part and the weight of the supporter can be provided.

[0140] FIG. 5 is a drawing illustrating the alignment direction of the resonant springs, wherein a is a drawing of the first resonant spring viewed in the axial direction (rear), b is a drawing of the second resonant spring viewed in the axial direction (forward), and c is a drawing showing the two covers of the front and rear in a single drawing.

[0141] Refer to Fig. 5. The alignment direction of the resonant spring can be defined as being inward from the 6:30 to 8:00 direction when the direction of the side force is defined as the 6:00 direction with respect to a clock. The alignment direction of the resonant spring can be defined as being inward from the 6:30 to 7:30 direction. The alignment direction of the resonant spring can be tilted approximately 30 degrees with respect to the side force.

[0142] With the above configuration, the behavioral stability of the resonant spring due to the side force can be secured.

[0143] The following describes an embodiment for improving the stable operating performance of a linear compressor. The higher the alpha value, the more the operating stability of the linear compressor can be improved.

[0144] The above alpha value is the speed coefficient in the linear compressor electric equation of Equation 1 below. Equation 1 is the stroke calculation formula for the piston.

[0145]

[0146] Here, the alpha value (α) can be a key factor in predicting the stroke of the moving part. Specifically, when calculating the stroke of the piston, the product of the alpha value and the speed is integrated. The alpha value can be calculated in the control unit of the linear compressor or stored in memory. Therefore, the stroke calculation error may increase in proportion to the error of the alpha value. It is advantageous for control for the alpha value to converge to 1 (100%). As the alpha value decreases, it may affect the control stability of the linear compressor.

[0147] Figure 10 is a graph explaining the alpha value, where a is a graph comparing the actual stroke and the calculated stroke, and b is a graph of the alpha value.

[0148] Refer to Fig. 10. A calculation error may occur between the actual stroke and the calculated stroke. Accordingly, it can be seen that the alpha value drops to the level of 0.1 (10%). The alpha value may drop sharply at the vertical dotted line. At the vertical dotted line, the actual stroke and the calculated stroke may start to differ significantly.

[0149] It is desirable for the above alpha value to be within the 80-100% range when designing the motor of a linear compressor. Here, the 80-100% range can be considered a value relative to the maximum alpha value. For example, the maximum alpha value (αmax) during the operation of a linear compressor may be 0.9. In this case, the current alpha value of the linear compressor can be operated within the range of 0.9 to 0.72. Here, 0.72 may be 80% of the maximum alpha value (αmax) of 0.9. If the maximum alpha value (αmax) in the linear compressor is not 0.9, the alpha value within the optimal alpha value range may change. This range can be referred to as the optimal alpha value range. An area outside the optimal alpha value range can be referred to as the poor alpha value range. In the above example, if the alpha value drops below 0.72, it can be referred to as the poor alpha value range. Within the optimal alpha value range, the alpha value may form a linear region. In areas larger than the optimal alpha value range and / or areas smaller than the optimal alpha value range, the alpha value may decrease rapidly. This area may be referred to as an alpha value defect area.

[0150] If the above alpha value falls below 70%, the calculation error of the piston's bottom dead center (BDC) may increase rapidly. Consequently, stable stroke calculation may not be possible, and collisions between components may occur. This issue can cause problems with the operational reliability of the linear compressor.

[0151] This embodiment presents a configuration that enables a linear compressor to operate in the optimal alpha value range. For example, the center of the magnet, the initial placement of the magnet, and the stroke range can be optimized.

[0152] FIG. 6 is a graph showing the relationship between the alpha value and the initial position, where a is a comparative example and the first experimental example, and b is a diagram showing the second experimental example and the third experimental example. FIG. 7 is a diagram showing the arrangement of the initial batch according to the third experimental example.

[0153] Refer to FIGS. 6 and 7. The comparative example has an initial position of 0.8 (unit mm, hereinafter the same) and operates with a stroke of 16. w1 is the stroke range of Comparative Example 1. In the comparative example, it can be seen that the movable part moves not only in the alpha value appropriate area but also in the alpha value defective area. In this case, problems such as stroke calculation failure of the piston, component collision, and reduced operational reliability may occur. The initial position (IP) may refer to the initial position of the permanent magnet. The initial position may refer to the distance from the center of the permanent magnet to the pole center (also called the pole center) of the outer stator (41). The initial position may refer to the distance from the axial center of the permanent magnet (45) to the axial center of the coil (41). At this time, the initial value may be 6.2. When the initial position is the same, if the initial value increases, the cylinder may become longer or the permanent magnet may become shorter.

[0154] Experimental Example 1 has an initial placement of 2.05, a stroke of 14.5, a forward travel distance (TDC direction) of 5.0, and a backward travel distance (BDC direction) of 9.5. w2 is the stroke range of Experimental Example 1. In this case, it can be seen that all areas are located within the appropriate alpha value range. This can be referred to as the alpha value optimal range. In the above alpha value optimal range, the alpha value may be 80% or higher. In the above alpha value poor range, the alpha value may drop sharply. At this time, the initial value may be 5.0.

[0155] Experimental Example 2 has an initial batch of 2.05, a stroke of 14.5, a forward travel distance (TDC direction) of 3.5, and a backward travel distance (BDC direction) of 11. w3 is the stroke range of Experimental Example 2. In this case, it can be seen that some areas in the bottom dead center direction are located in the alpha value defective area. The other areas are the alpha value optimal area, where the alpha value may be 80% or more of the alpha value maximum (αmax). At this time, the initial value may be 3.5.

[0156] Experimental Example 3 has an initial placement (W1) of 3.55, a stroke of 14.5, a forward travel distance (TDC direction) of 3.5, and a backward travel distance (BDC direction) of 11. w4 is the stroke range of Experimental Example 3. In this case, it can be seen that all areas are located within the appropriate alpha value range. This can be referred to as the alpha value optimal range. In the above alpha value optimal range, the alpha value may be 80% or more of the maximum alpha value (αmax). In the above alpha value poor range, the alpha value may drop sharply. At this time, the initial value may be 3.5.

[0157] In the above experimental example, the axial length of the magnet frame (46) may be in the range of 46-49 mm. Preferably, it may be in the range of 48-49 mm. More preferably, it may be in the range of 48.3-48.6 mm. Accordingly, the length of the magnet frame may be sufficiently long. In this case, the distance between the end of the permanent magnet and the pole center (pole center of the outer stator (41)) can be sufficiently secured. Thus, it can accommodate an increase in the stroke in the bottom dead center direction.

[0158] The combination of the above initial batch and the above initial value may further have the following range. The above range may refer to the range in which the linear compressor operates in the alpha value optimal region.

[0159] First, when the initial batch is 1.8, the initial value is 6.2; second, when the initial batch is 2.00, the initial value is 6; and third, when the initial batch is 5.00, the initial value is 3.0. If operated within the above range, the linear compressor can operate in the appropriate alpha value range.

[0160] Figure 8 is a graph of alpha values ​​for the distance from the center of the permanent magnet to the top dead center and bottom dead center.

[0161] Refer to Fig. 8. It can be moved 7.9 mm in the direction of the bottom dead center and 8.0 mm in the direction of the top dead center from the center of the permanent magnet. That is, it can be moved a predetermined distance from the center of the permanent magnet to the bottom dead center and a predetermined distance to the top dead center. This can be called the alpha value optimal region. In the above alpha value optimal region, it can be confirmed that the alpha value is 80% or more of the maximum alpha value (αmax). In the above alpha value optimal region, it can be seen that the alpha value forms a linear region. In regions larger than the above alpha value optimal region and / or regions smaller than the above alpha value optimal region, the alpha value may decrease rapidly. This region can be called the alpha value defective region.

[0162] The above bottom dead center and top dead center may refer to the maximum movement points of the above-mentioned movable part. At the above bottom dead center (BDC) and top dead center (TDC), the piston may cause impact.

[0163] In the above-mentioned optimal alpha value range, the stability of the stroke calculation can be high. Accordingly, the linear compressor can be controlled stably. In the above-mentioned optimal alpha value range, collisions between parts can be prevented.

[0164] The optimal alpha value region may correspond to region A in Fig. 8. In the optimal alpha value region, the stroke calculation is optimal, allowing the linear compressor to operate stably. In the optimal alpha value region, the alpha value may be 80% or more of the maximum alpha value (αmax). The defective alpha value region may correspond to region C in Fig. 8. In the defective alpha value region, the alpha value may be 70% or less of the maximum alpha value (αmax). In the defective alpha value region, the linear compressor cannot operate stably due to stroke calculation errors. The area between the defective alpha value region and the optimal alpha value region may be the control margin region. The control margin region may correspond to region B in Fig. 8. The alpha value in the control margin region may be greater than 70% and less than 80% of the maximum alpha value (αmax). The control margin region may be a section where the slope of the alpha value changes rapidly. The control mode of the linear compressor can be changed by detecting the above control margin area.

[0165] Figure 9 is a diagram showing the top dead center and bottom dead center of a linear compressor in the region of 70% of the maximum alpha value (αmax). Figure 9a is the state of the top dead center (TDC), and Figure 10b is the state of the bottom dead center (BDC).

[0166] Refer to Fig. 9. As shown in a, when the distance between the rear end of the magnet and the pole center is 0.4 or greater, the alpha value may be 70% or greater of the maximum alpha value (αmax). When the distance between the rear end of the magnet and the pole center is less than 0.4 (where the distance may have a negative value), the alpha value may be less than 70% of the maximum alpha value (αmax).

[0167] As shown in b, when the distance between the magnet front end and the pole center is 0.4 or greater, the alpha value may be 70% or greater of the maximum alpha value (αmax). When the distance between the magnet front end and the pole center is less than 0.4 (where the distance may have a negative value), the alpha value may be less than 70% of the maximum alpha value (αmax).

[0168] The linear compressor according to an embodiment of the present invention can ensure stable operating performance. Accordingly, it has great potential for industrial application.

Claims

A cylinder into which a piston that reciprocates axially is inserted, supported inside a frame; A permanent magnet that reciprocates in the axial direction together with the piston; and A stator is included that is fixed to the above frame and has a portion surrounding the cylinder, and A linear compressor in which the region in which the permanent magnet reciprocates is a range in which the distance between the rear end of the permanent magnet and the center of the pole of the stator is 0.4 or greater, and the distance between the front end of the permanent magnet and the center of the pole of the stator is 0.4 or greater. In Article 1, A linear compressor that operates in a region where the above alpha value is 70% or more of the maximum alpha value (αmax). In Article 1, A linear compressor in which the alpha value in the above alpha value optimal region is a linear region. In Article 1, The above piston is a linear compressor in which the forward travel distance from the initial position is smaller than the backward travel distance. In Article 1, A linear compressor in which the stroke of the piston is 16mm-14.5mm. In Article 1, The stator comprises an outer stator fixed to the frame and arranged to surround the cylinder; and an inner stator spaced apart from the inner side of the outer stator. A linear compressor comprising a permanent magnet located in the space between the outer stator and the inner stator. In Article 1, The above piston is a linear compressor configured to operate in a region where the speed coefficient (alpha value) of the compressor's electrical equation is 80% or more of the maximum alpha value (αmax). In Article 7, The length of the magnet frame supporting the above permanent magnet is 46-49 mm, and A linear compressor satisfying at least one of the following: the initial arrangement, which is the distance between the axial center of the permanent magnet and the pole center of the outer stator, is in the range of 2.00 to 5.

00. In Article 7, A linear compressor in which the initial value, which is the distance from the front end of the cylinder to the front end of the piston, is in the range of 6.0 to 3.0.

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