A linear compressor

Abstract

The present invention relates to the technical field of compressors, and discloses a linear compressor, comprising: a compressor core, the compressor core includes a linear motor, a cylinder, a piston and a leaf spring assembly, the cylinder is arranged in the cylinder of the inner stator of the linear motor, the piston is arranged in the cylinder, the cylinder, the inner stator and the piston are coaxially arranged, leaf spring assemblies are respectively fixedly arranged at both ends of the linear motor, both ends of the piston respectively penetrate out of the cylinder and are supported and connected to the corresponding leaf spring assemblies, so that the piston floats inside the cylinder. The linear compressor provided by the present invention arranges the cylinder and the piston in the cylinder of the inner stator of the linear motor, which can effectively utilize the internal space of the motor and is beneficial to reducing the size of the compressor; in addition, the piston is supported by the bilateral leaf spring assemblies, and the piston floats inside the cylinder, realizing non-contact reciprocating motion of the piston and the cylinder, increasing the reliability during the piston movement, reducing the vibration of the compressor and reducing the vibration noise.

Description

Technical Field

[0001] The present invention relates to the technical field of compressors, and particularly to a linear compressor. Background Art

[0002] In the low-temperature field, the compressors used to drive Stirling refrigerators and pulse tube refrigerators are mainly a type of valve-less linear compressor. The linear compressor is directly driven by a linear motor, eliminating the crank-link mechanism of the traditional reciprocating piston compressor, reducing the motion conversion device, and greatly improving the efficiency of the compressor, thus receiving extensive attention and application.

[0003] Currently, the more widely used is the moving-magnet linear oscillating motor of the Redlich type structure. This type of moving-magnet linear oscillating motor installs magnetic conductive materials on the circumference of the excitation coil to form a magnetic circuit structure with a cylindrical air gap concentric with the excitation coil. The air gap is composed of cylindrical inner and outer stators, and the radially magnetized cylindrical permanent magnet moves reciprocally in the air gap. The Redlich type structure linear motor has the advantages of better magnetic circuit structure design and small magnetic circuit loss.

[0004] The existing technology applications mainly use the cylindrical linear oscillating motor of the Redlich structure as the driver, and mostly use low-cost helical springs or scroll arm leaf springs as supports. The existing compressors have the problems of occupying a large installation size and large overall vibration of the machine, thus restricting the application range. Summary of the Invention

[0005] The present invention provides a linear compressor to solve or partially solve the problems that the existing compressors occupy a large installation size and have large overall vibration of the machine, thus restricting the application range.

[0006] The present invention provides a linear compressor, including: a compressor core, the compressor core includes a linear motor, a cylinder, a piston and a leaf spring assembly. The cylinder is arranged inside the cylinder of the inner stator of the linear motor. The piston is arranged in the cylinder. The cylinder, the inner stator and the piston are coaxially arranged. The leaf spring assemblies are respectively fixedly arranged at both ends of the linear motor. Both ends of the piston respectively penetrate out of the cylinder and are supported and connected to the corresponding leaf spring assemblies, so that the piston floats inside the cylinder.

[0007] According to a linear compressor provided by the present invention, a stepped through-channel is axially arranged inside the cylinder, and the part with a smaller cross-sectional size of the through-channel is arranged at the first end of the cylinder; the piston is configured with a larger cross-sectional size in the middle and smaller cross-sectional sizes at both ends; the middle part of the piston matches the part with a larger cross-sectional size of the through-channel inside the cylinder, and the first end of the piston matches the through-channel at the first end of the cylinder.

[0008] A linear compressor provided according to the present invention, the second end of the piston is connected to a piston bracket, the piston bracket is connected to the corresponding leaf spring assembly, and the piston bracket is connected to the mover of the linear motor.

[0009] A linear compressor provided according to the present invention, the leaf spring assembly includes multiple elastic members stacked axially, and flat washers are provided between adjacent two layers of elastic members; the elastic member has two free ends and is integrally bent or the elastic member has at least three free ends and the free ends are distributed at the edge part; the middle part of the elastic member is connected to the piston.

[0010] A linear compressor provided according to the present invention, fixing seats are respectively provided at both ends of the linear motor, and the leaf spring assembly and the cylinder are respectively connected to the fixing seats.

[0011] A linear compressor provided according to the present invention, a compression chamber is formed between the middle part of the piston and the first end of the cylinder, and at least one exhaust hole communicating with the compression chamber is provided in the circumferential direction on the first end wall surface of the cylinder.

[0012] A linear compressor provided according to the present invention, the compressor core is arranged inside the housing, at least one boss corresponding to the exhaust hole is circumferentially connected to the inner wall of the housing, an intermediate channel communicating with the corresponding exhaust hole is provided inside the boss, an exhaust channel is further arranged inside the housing, the exhaust channel communicates with the intermediate channel, and at least one exhaust port communicating with the exhaust channel is provided on the wall surface of the housing.

[0013] A linear compressor provided according to the present invention, two symmetrically distributed compressor cores are provided inside the housing, and the exhaust holes of the two compressor cores communicate with the exhaust channel.

[0014] A linear compressor provided according to the present invention, the boss is arranged between the two compressor cores, and the corresponding exhaust holes on the two compressor cores are simultaneously communicated with the intermediate channels inside the corresponding bosses.

[0015] A linear compressor provided according to the present invention, a lubricating coating is provided on the outer surface of the piston.

[0016] A linear compressor provided by the present invention has a cylinder and a piston disposed within the cylinder of the inner stator of a linear motor, which can effectively utilize the internal space of the motor, facilitate the reduction of the compressor size, and decrease the system volume. Additionally, a double-sided leaf spring assembly is used to support the piston, suspending the piston within the cylinder to achieve non-contact reciprocating motion between the piston and the cylinder. While ensuring the coaxiality of the piston and the cylinder, it can reduce the friction between the piston and the cylinder, enabling the compressor to operate without oil, increasing the reliability during piston movement, reducing the vibration of the compressor, and lowering the vibration noise. Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a cross-sectional schematic diagram of the linear compressor provided by the present invention;

[0019] Figure 2 It is an external schematic diagram of the linear compressor provided by the present invention;

[0020] Figure 3 It is one of the schematic diagrams of the elastic member provided by the present invention;

[0021] Figure 4 It is another schematic diagram of the elastic member provided by the present invention;

[0022] Figure 5 It is the third schematic diagram of the elastic member provided by the present invention;

[0023] Figure 6 It is the fourth schematic diagram of the elastic member provided by the present invention;

[0024] Figure 7 It is the fifth schematic diagram of the elastic member provided by the present invention;

[0025] Figure 8 It is the specific connection diagram of the fifth schematic diagram of the elastic member provided by the present invention.

[0026] Reference Numerals:

[0027] 1. Cylinder; 2. Central axis; 3. First fixed seat; 4. Inner stator; 5. Piston; 6. Piston bracket; 7. Second fixed seat; 8. Excitation coil; 9. Outer stator; 10. Cylindrical air gap; 11. Ring permanent magnet; 12. Rotor skeleton; 13. Leaf spring assembly; 14. Compression chamber; 15. Flat washer; 16. Right straight arm; 17. Left straight arm; 18. Lower straight arm; 19. Clamping arm part; 20. Through hole of clamping arm part; 21. Central through hole; 22. Left end housing; 23. Right end housing; 24. Middle housing; 25. Left exhaust port; 26. Right exhaust port; 27. Boss; 28. Intermediate channel; 29. Exhaust channel; 30. Exhaust hole. Detailed implementation manners

[0028] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0029] The following Figures 1-8 describes the linear compressor of the present invention.

[0030] Referring to Figure 1 , this embodiment provides a linear compressor, which includes: a compressor core. The compressor core includes a linear motor, a cylinder 1, a piston 5 and a leaf spring assembly 13; the linear motor provides linear reciprocating movement. The cylinder 1 is arranged in the cylinder of the inner stator 4 of the linear motor, the piston 5 is arranged in the cylinder 1, and the cylinder 1, the inner stator 4 and the piston 5 are coaxially arranged; leaf spring assemblies 13 are respectively fixedly arranged at both ends of the linear motor. The leaf spring assembly 13 is in a sheet-like structure and is fixed outside both ends of the linear motor along the axial direction. Both ends of the piston 5 respectively penetrate out of the cylinder 1 and are supported and connected to the corresponding leaf spring assemblies 13, so that the piston 5 floats inside the cylinder 1.

[0031] That is, the piston 5 is supported and fixed by being connected to the leaf spring assembly 13. The cylinder 1 only plays a limiting role around the piston and does not apply a supporting force to the piston 5. The piston 5 is supported and connected to the leaf spring assembly 13, so that there are gaps between the piston 5 and the inner wall of the cylinder 1 in the circumferential direction. Thus, the non-contact reciprocating movement of the piston 5 and the cylinder 1 is realized. While ensuring the coaxiality of the piston 5 and the cylinder 1, the friction between the piston 5 and the cylinder 1 can be reduced, enabling the compressor to operate without oil, increasing the reliability during the piston movement, and reducing the vibration of the compressor.

[0032] A linear compressor provided in this embodiment has a cylinder and a piston disposed within the cylinder of the inner stator of a linear motor, which can effectively utilize the internal space of the motor, facilitate reducing the size of the compressor, and decreasing the volume of the system. Additionally, a double-sided leaf spring assembly is adopted to support the piston, suspending the piston within the cylinder to achieve non-contact reciprocating motion between the piston and the cylinder. While ensuring the coaxiality of the piston and the cylinder, it can reduce the friction between the piston and the cylinder, enabling the compressor to operate without oil, increasing the reliability during piston movement, reducing the vibration of the compressor, and lowering the vibration noise.

[0033] Further, one end of the piston extends out of the cylinder and is also connected to the mover of the linear motor; it is used to perform reciprocating movement under the drive of the mover.

[0034] Based on the above embodiment, further, referring to Figure 1 , a stepped through-channel is axially provided inside the cylinder 1, and the part with a smaller cross-sectional size of the through-channel is disposed at the first end of the cylinder 1; the piston 5 is configured with a larger cross-sectional size in the middle and smaller cross-sectional sizes at both ends; the middle part of the piston 5 matches the part with a larger cross-sectional size of the through-channel inside the cylinder 1, and the first end of the piston 5 matches the through-channel at the first end of the cylinder 1. That is, the middle part of the piston 5 and the part with a larger cross-sectional size of the through-channel inside the cylinder 1 can achieve clearance sealing. The first end of the piston 5 and the through-channel at the first end of the cylinder 1 can achieve clearance sealing. By setting the through-channel inside the cylinder 1 to be stepped, and the piston 5 also to be stepped, a compression chamber is formed between the middle part of the piston 5 and the first end of the cylinder 1, ensuring the normal operation of the piston in the cylinder 1.

[0035] Based on the above embodiment, further, the second end of the piston 5 is connected to the piston support 6, the piston support 6 is connected to the corresponding leaf spring assembly 13, and the piston support 6 is connected to the mover of the linear motor.

[0036] Specifically, referring to Figure 1 , the piston 5 is stepped, composed of three cylinders with unequal diameters, and the middle cylinder section has the largest diameter; the cylinder section with the largest diameter of the piston 5 cooperates with the large end of the stepped cylinder 1, i.e., the part with a larger cross-sectional size of the through-channel, and is reciprocally and movably installed inside the cylinder 1. The middle cylinder section of the stepped piston 5 and the large end of the stepped cylinder 1 form a gas compression chamber 14. One end of the piston 5 cooperates with the small end of the cylinder 1, i.e., the first end, and extends out of the stepped cylinder 1. One end of the piston 5 extending out of the large end of the cylinder 1 is connected to the piston support 6 by screws, and the other end extending out of the small end of the cylinder 1 is connected to the leaf spring assembly 13 by screws, etc.

[0037] On the basis of the above embodiments, further, the leaf spring assembly 13 includes multiple elastic members stacked axially, and flat washers 15 are provided between adjacent two layers of elastic members; the elastic member has two free ends and is integrally in a bent structure, or the elastic member has at least three free ends and the free ends are distributed at the edge portions; the middle portion of the elastic member is connected to the piston.

[0038] On the basis of the above embodiments, further, fixing seats are respectively provided at both ends of the linear motor, and the leaf spring assembly 13 and the cylinder 1 are respectively connected to the fixing seats. Specifically, referring to Figure 1 , at both ends of the stator of the linear motor, a first fixing seat 3 and a second fixing seat 7 are respectively coaxially fixedly installed through threads and the like. The leaf spring assembly can be connected to the fixing seat at the edge portion and to the piston at the middle portion. The outer wall surface of the first end of the cylinder 1 can be threadedly connected to the second fixing seat 7; and a sealing ring is provided at the connection portion.

[0039] There are various forms of connection between the leaf spring assembly and the piston. For example, the middle portion of the leaf spring assembly is connected to the piston, and each free end of the leaf spring assembly is connected to the stator or the fixing seat; or, at least one free end of the leaf spring is connected to the piston, and the other free ends of the leaf spring are connected to the corresponding ends of the stator. The leaf spring assembly includes elastic members distributed in the same plane or near the same plane. The elastic member is a first combined shape formed by sequentially connecting multiple straight segments or curved segments end to end, and free ends are respectively provided at both ends of the first combined shape; that is, the elastic member has two free ends, and the two free ends can be connected by any number of straight segments and any number of curved segments in any bent form. Or, the elastic member is a second combined shape formed by connecting one ends of multiple straight segments and / or curved segments together, and free ends are respectively provided at the other ends of the corresponding straight segments or curved segments in the second combined shape; that is, the elastic member has more than three free ends, and each free end and the central portion are connected by any straight segments and any curved segments in any bent form. In this embodiment, one of the connection methods between the leaf spring assembly and the piston can be selected for installation, and one of the shapes of the elastic members of the leaf spring assembly can also be selected for design, and multiple forms of connection and shape design can be freely arranged and combined.

[0040] It should also be pointed out here that the first combined shape can be formed by bending a spring wire multiple times in the same plane. Obviously, the shape of each bent segment of the first combined shape includes straight segments, curved segments and their combinations, and the cross-section of the spring wire can be circular, oval, square or triangular, which is not specifically limited here. Thus, the combined shape obtained by bending can be an "S" shape, a "C" shape, a "Z" shape, an "L" shape, a "ㄥ" shape, a "V" shape, a "U" shape, an "∠" shape, a "┓" shape, a "く" shape, a "へ" shape, a "J" shape, etc.

[0041] Such as Figure 3As shown, the elastic member of the first combined shape is formed by bending a spring wire with a circular cross-section at least 6 times; its shape includes 5 straight segments, 4 connecting transition arcs (curved segments), and arc-shaped free ends at both the head and tail ends for positioning and installation; thus, the corresponding free ends at both the head and tail ends of the elastic member can be connected and fixed to the edge part of the fixed seat, and the central position of the elastic member can be connected to the corresponding end of the piston 5 to support the reciprocating movement of the piston 5 in the cylinder 1.

[0042] As Figure 4 shown, the elastic member is formed by bending a spring wire with a circular cross-section at least 4 times; its shape includes 3 straight segments (straight line segments), 2 connecting transition arcs (curved segments), and arc-shaped free ends at both the head and tail ends for positioning and installation.

[0043] As Figure 5 shown, the elastic member is formed by bending a spring wire with a circular cross-section at least 22 times; its shape includes 21 straight segments (straight line segments), 20 connecting transition arcs (curved segments), and arc-shaped free ends at both the head and tail ends for positioning and installation.

[0044] As Figure 6 shown, the elastic member is formed by bending a spring wire with a circular cross-section at least 12 times; its shape includes 10 arc segments (curved segments), 1 central connecting segment (straight line segment), and arc-shaped free ends at both the head and tail ends for positioning and installation. Of course, the elastic member of the first combined form also includes other structural forms, which will not be listed one by one here.

[0045] At the same time, the elastic member can also be a second combined shape formed by connecting one end of multiple straight segments or curved segments together, and free ends are respectively provided at the other ends of the corresponding straight segments or curved segments in the second combined shape.

[0046] Thus, the elastic member of this form is arranged radially and obviously includes multiple free ends. As Figure 7 shown, in Figure 7 it discloses a layout structure in which three curved segments in the elastic member are centrosymmetric. Among them, the cross-section of each curved segment is rectangular, and one end of the three curved segments is connected through an annular structure, while the other ends of the three curved segments are set as corresponding free ends, and the free ends are fan-shaped annular structures, and a plurality of fixing holes are provided on the fan-shaped annular structures. Thus, the annular structure at the central position of the elastic member can be connected to the piston, and the fan-shaped annular structures corresponding to each radial end of the elastic member can be connected to the corresponding fixed seats to support the reciprocating movement of the piston in the cylinder.

[0047] Further, mounting holes penetrating the end faces can be provided in the middle of both ends of the piston 5. The middle part of the elastic member of the leaf spring assembly 13 can be connected to the piston 5 through the mounting holes. When the elastic member is in the first combined form, the middle part of the elastic member can be fixedly connected to the end of the piston 5 through a fastener. When the elastic member is in the second combined form, the mounting hole can be a threaded hole, and the elastic member can be connected to the mounting hole of the piston through a bolt.

[0048] Further, a plurality of leaf springs are provided at the corresponding end of the stator. The plurality of leaf springs are stacked at intervals in the axial direction in sequence to form a leaf spring assembly. A flat washer 15 is used to separate each two leaf springs. A plurality of elastic members can be correspondingly arranged and connected to the fixed seat at the same time.

[0049] On the basis of the above embodiments, further, a compression chamber 14 is formed between the middle part of the piston 5 and the first end of the cylinder 1. At least one exhaust hole 30 communicating with the compression chamber is provided in the circumferential direction on the first end wall surface of the cylinder 1. The exhaust hole is used to output the compression and expansion energy of the gas in the compression chamber.

[0050] On the basis of the above embodiments, further, referring to Figure 1 , the compressor core is arranged inside the housing. At least one boss 27 is circumferentially connected to the inner wall of the housing corresponding to the exhaust hole 30. An intermediate passage 28 communicating with the corresponding exhaust hole 30 is provided inside the boss 27. An exhaust passage 29 is also arranged inside the housing. The exhaust passage 29 communicates with the intermediate passage 28. At least one exhaust port communicating with the exhaust passage 29 is provided on the wall surface of the housing. That is, each exhaust hole on the compressor core corresponds to communicate with the exhaust passage 29 through the intermediate passage 28 of a boss 27.

[0051] Further, the exhaust holes 30 on the compressor core can be evenly distributed in the circumferential direction. Air passages communicating with the exhaust holes 30 can be correspondingly arranged on the fixed seat for gas to enter and exit.

[0052] On the basis of the above embodiments, further, most current linear compressors are of single-cylinder structure to realize gas compression in a single cylinder. The effect of improving the energy utilization efficiency of the single-cylinder linear compressor is not significant. When the compressor operates, the vibration generated by the fuselage is relatively large, and when driving the refrigerator, the vibration of the cold head of the refrigerator is relatively large, which limits the application range of the compressor. A linear compressor provided in this embodiment has two symmetrically distributed compressor cores arranged inside the housing. The exhaust holes 30 of the two compressor cores are both communicated with the exhaust passage 29. This is beneficial to improving the energy utilization efficiency and reducing vibration.

[0053] On the basis of the above embodiments, further, the boss 27 is arranged between the two compressor cores. The corresponding exhaust holes 30 on the two compressor cores are simultaneously communicated with the intermediate passage 28 inside the corresponding boss.

[0054] Further, the exhaust passage may be circular and arranged along the cross-section of the housing. This facilitates connection with the intermediate passage in the bosses at different positions and also facilitates the setting of exhaust ports on the housing.

[0055] Based on the above embodiments, further, a lubricating coating is applied to the outer surface of the piston. A wear-resistant self-lubricating coating is applied to the surface of the piston 5. The wear-resistant self-lubricating coating includes any one or a combination of at least two of a graphite-like coating, a polyether ether ketone coating, a polyimide resin coating, a diamond-like coating, a Teflon coating, a molybdenum disulfide coating, a tungsten disulfide coating, a graphite coating, a chromium nitride coating, a titanium aluminum silicon nitride coating, a titanium aluminum nitride coating, a titanium nitride coating, an alumina ceramic coating, and a phosphating coating. By preparing a material coating with self-lubricating and wear-resistant and friction-reducing properties on the surface of the piston 5 in this double linear compressor, the friction between the piston 5 and the cylinder 1 can be reduced, enabling the compressor to operate without oil, increasing the reliability during piston movement, and extending the service life of the compressor.

[0056] Based on the above embodiments, further, this embodiment provides a double-cylinder opposed linear compressor, which includes a housing, a linear motor, a cylinder, a piston, and a compressor core formed by a leaf spring assembly. Two identical linear compressor cores are symmetrically arranged. The linear motor mainly uses electromagnetic force to generate vibration and then combines with mechanical resonance to push the piston to reciprocate and compress gas. The linear motor can be of the moving magnet type, moving coil type, or moving iron type. In this embodiment, the moving magnet type is mainly used as an example for illustration.

[0057] Reference Figure 1 , the cylinder 1 is stepped and consists of two hollow cylinders with unequal diameters. The small end of the cylinder 1, that is, the part with a smaller cross-sectional size of the through passage, is fixed to the second fixing seat 7 by threads. An exhaust hole 30 is opened at the small end of the cylinder 1 for connecting the compression chamber 14 with the exhaust port of the middle housing 24 of the compressor.

[0058] In this embodiment, the middle part of the leaf spring assembly 13 is connected to the piston 5, and the free ends of the leaf spring assembly 13 are connected to the corresponding ends of the stator. This embodiment is used as an example for illustration. As Figure 8 shown, the elastic member includes: a left linear arm 17, a right linear arm 16, a lower linear arm 18, and a clamp arm-shaped part 19. The thickness of each part is the same, and the specific thickness is determined by the required axial stiffness and radial stiffness; the left linear arm 17, the right linear arm 16, and the lower linear arm 18 have the same shape and size and are distributed in a circular pattern; there are 3 uniformly distributed clamp arm-shaped part through holes 20 on the clamp arm-shaped part 19; the leaf spring center through hole 21 is located at the exact center of the leaf spring. The center through hole 21 of the leaf spring assembly 13 is connected to the piston bracket 6 and the piston 5 by threads, and the clamp arm-shaped parts 19 of the leaf spring assembly 13 are fixed to the first fixing seat 3 and the second fixing seat 7 by threads.

[0059] The first fixed seat 3 is fixedly connected through threads to the through hole 20 of the clamp arm-shaped part of the first leaf spring assembly. A cylinder 1 is fixedly installed on the second fixed seat 7 through threads, and the second fixed seat 7 is provided with an exhaust flow passage communicating the exhaust hole of the cylinder 1 and the exhaust port of the middle housing. In this embodiment, with the leaf spring assembly 13 as the support, the piston 5 is suspended inside the cylinder 1 to realize the non-contact reciprocating motion of the piston 5 and the cylinder 1. While ensuring the coaxiality of the piston 5 and the cylinder 1, the radial stiffness and axial stiffness of the compressor are guaranteed.

[0060] Based on the above embodiment, as Figure 1 shown, the stator component of the linear motor includes an inner stator 4 and an outer stator 9 arranged coaxially. There is a cylindrical air gap 10 between the inner stator 4 and the outer stator 9; the mover is installed in the cylindrical air gap 10 and includes a mover skeleton 12 and a ring permanent magnet 11 connected coaxially; the piston 5 is located coaxially inside the mover, and one end of the piston 5 that does not cooperate with the cylinder 1 is connected to the end of the mover skeleton 12 away from the ring permanent magnet 11. The iron cores of the inner stator 4 and the outer stator 9 are both in the shape of a hollow cylinder, and the inner stator 4 and the outer stator 9 form a symmetric magnetic circuit; an excitation coil 8 arranged circumferentially is provided on the outer side wall of the iron core of the inner stator 4 or the inner side wall of the iron core of the outer stator 9. The excitation coil 8 is energized with alternating current to generate a magnetic field; the mover includes a group of ring permanent magnets 11, and the magnetic poles of the ring permanent magnets 11 are arranged radially. Through the symmetric magnetic circuit, a magnetic field alternating in positive and negative directions is formed in the cylindrical air gap 10. Under the action of the magnetic field, the ring permanent magnets 11 generate an axial reciprocating electromagnetic driving force, which further pushes the piston 5 in the cylinder 1 to compress the gas.

[0061] Refer to Figure 1 and Figure 2, in this embodiment, the double-cylinder opposed type oil-free linear compressor further includes a housing, which includes a left-end housing 22, a right-end housing 23, and a middle housing 24. The end housings are provided with a number of uniformly distributed threaded holes to achieve fixed connection with the middle housing 24; O-ring sealing grooves are provided on both the left and right sides of the end housings to achieve the sealing of the entire compressor. The internal space of the middle housing 24 is similar to a cylindrical shape, and there are three bosses evenly distributed in a circle inside the housing. The bosses avoid the arm-like parts 19 of the leaf spring assembly, so that the arm-like parts 19 can be smoothly connected to the fixed seat. Each boss is provided with an intermediate channel, and an O-ring sealing groove is provided around the intermediate channel. The intermediate channel of the boss is used to connect the exhaust hole 30 of the cylinder 1 and the exhaust channel in the middle of the middle housing 24. The boss is fixedly connected to the second fixed seat 7 by a thread. The middle exhaust channel is provided at the position of the central axis 2 of the middle housing 24. The middle housing 24 is provided with a left exhaust port 25, a right exhaust port 26, and a lower exhaust port corresponding to the exhaust hole 30 of the cylinder 1. A power cord wiring hole and a back pressure chamber through hole are also provided on the middle housing 24. The three exhaust ports of the middle housing 24 are externally sealed and connected to an exhaust pipe for exhaust; the power cord wiring hole is used for the power cord of the linear motor to extend outside the middle housing 24 and access the power supply. The back pressure chamber through hole is used to detect the air pressure inside the middle housing 24. Two compressor cores are symmetrically arranged inside both sides of the housing.

[0062] It can be seen from the above embodiments that the double-cylinder opposed type oil-free linear compressor provided in this embodiment includes a housing, a linear motor, a cylinder, a piston, and a compressor core composed of a leaf spring assembly. Since two identical linear compressor cores are symmetrically arranged, and the stepped piston adopts an installation method coaxially located inside the mover, the size is effectively reduced, the volume and weight of the system are reduced, the lateral force generated by the moving parts is reduced, and the vibration and noise of the compressor are reduced. The compression process of the linear compressor is that the working medium, under the action of the linear motor, when the piston assembly supported by the leaf spring assembly reciprocates, suspends the piston inside the cylinder, realizes the non-contact reciprocating motion of the piston and the cylinder, ensures the coaxiality of the piston and the cylinder, and increases the radial stiffness and axial stiffness of the compressor. And a material coating with wear-resistant and friction-reducing properties with self-lubricating characteristics is prepared on the piston surface, which can reduce the friction between the piston and the cylinder, enable the compressor to operate without oil, and increase the reliability during the piston movement. The working medium forms a periodic pressure fluctuation in the compression chamber, that is, periodic compression-expansion, and then the working medium sequentially passes through the cylinder, the second fixed seat, and the exhaust holes of the middle housing from the compression chamber. Finally, the working medium is discharged from the middle housing through the exhaust holes of the middle housing, and the pressure fluctuation enters the Stirling or pulse tube refrigerator assembly through the exhaust pipe connected to the exhaust hole. Therefore, this double-cylinder opposed type oil-free linear compressor can be used to drive a refrigerator.

[0063] A double-cylinder opposed type oil-free linear compressor proposed in this embodiment can effectively improve the axial stiffness and radial stiffness of the compressor while ensuring clearance sealing and oil-free lubrication technologies, achieve high-frequency resonance operation, and improve the operation efficiency; can effectively utilize the internal space of the motor, reduce the size of the compressor, reduce the volume of the system, and realize the miniaturization of the compressor; improve the service life and reliability of the linear compressor, realize the miniaturization of the compressor, reduce the vibration and noise of the existing linear compressor, and realize the characteristic matching between the linear compressor and the cold head of the cryogenic refrigerator.

[0064] In this embodiment, the linear motor mover is supported by double-sided leaf springs, and the stepped piston is installed inside the mover. The compression chamber is arranged inside the motor, which can effectively utilize the internal space of the motor, reduce the size of the compressor, and reduce the volume of the system. To solve the defects of large vibration and short life of the linear compressor, two identical linear compressor cores are symmetrically arranged. The piston assembly supported by the leaf spring assembly reciprocates to suspend the piston inside the cylinder, realizing the non-contact reciprocating motion of the piston and the cylinder. While ensuring the coaxiality of the piston and the cylinder, the radial stiffness and axial stiffness of the compressor are increased.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A linear compressor, characterized in that, Comprising: A compressor core, the compressor core includes a linear motor, a cylinder, a piston and a leaf spring assembly. The cylinder is arranged inside a cylinder of an inner stator of the linear motor. The piston is arranged in the cylinder. The cylinder, the inner stator and the piston are coaxially arranged. Leaf spring assemblies are respectively fixedly arranged at two ends of the linear motor. Two ends of the piston respectively penetrate out of the cylinder and are supported and connected to the corresponding leaf spring assemblies, so that the piston floats inside the cylinder; A stepped through-channel is axially arranged inside the cylinder, and a part with a smaller cross-sectional size of the through-channel is arranged at a first end of the cylinder; The piston is configured with a larger cross-sectional size in the middle and smaller cross-sectional sizes at both ends; The middle part of the piston matches the part with a larger cross-sectional size of the through-channel inside the cylinder, and the first end of the piston matches the through-channel at the first end of the cylinder; A second end of the piston is connected to a piston bracket. The piston bracket is connected to the corresponding leaf spring assembly, and the piston bracket is connected to a mover of the linear motor; The leaf spring assembly includes multiple layers of elastic members stacked axially. A flat washer is arranged between adjacent two layers of elastic members; The elastic member has two free ends and is integrally in a bent structure or the elastic member has at least three free ends and the free ends are distributed at the edge part; The middle part of the elastic member is connected to the piston.

2. The linear compressor according to claim 1, wherein Fixed seats are respectively arranged at two ends of the linear motor. The leaf spring assembly and the cylinder are respectively connected to the fixed seats.

3. The linear compressor according to claim 1, characterized in that, A compression chamber is formed between the middle part of the piston and the first end of the cylinder. At least one exhaust hole communicating with the compression chamber is arranged circumferentially on the first end wall surface of the cylinder.

4. The linear compressor according to claim 3, characterized in that, The compressor core is arranged inside a housing. At least one boss is circumferentially connected to the inner wall of the housing corresponding to the exhaust hole. An intermediate channel communicating with the corresponding exhaust hole is arranged inside the boss. An exhaust channel is also arranged inside the housing. The exhaust channel communicates with the intermediate channel. At least one exhaust port communicating with the exhaust channel is arranged on the wall surface of the housing.

5. The linear compressor according to claim 4, wherein Two symmetrically distributed compressor cores are arranged inside the housing. The exhaust holes of the two compressor cores are both communicated with the exhaust channel.

6. The linear compressor according to claim 5, characterized in that The boss is arranged between the two compressor cores. The corresponding exhaust holes on the two compressor cores are simultaneously communicated with the intermediate channel inside the corresponding boss.

7. The linear compressor according to any one of claims 1 to 6, characterized in that, A lubricating coating is applied to the outer surface of the piston.

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