CN112814873A - Opposed direct-current linear compressor adopting embedded one-way valve and design method - Google Patents

Opposed direct-current linear compressor adopting embedded one-way valve and design method Download PDF

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CN112814873A
CN112814873A CN202110263226.0A CN202110263226A CN112814873A CN 112814873 A CN112814873 A CN 112814873A CN 202110263226 A CN202110263226 A CN 202110263226A CN 112814873 A CN112814873 A CN 112814873A
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coil
plate spring
reed
current
pole shoe
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CN112814873B (en
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党海政
赵永江
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Shanghai Institute of Technical Physics of CAS
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Shanghai Institute of Technical Physics of CAS
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B37/00—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00
    • F04B37/10—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use
    • F04B37/12—Pumps having pertinent characteristics not provided for in, or of interest apart from, groups F04B25/00 - F04B35/00 for special use to obtain high pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
    • F04B39/10—Adaptations or arrangements of distribution members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B39/00—Component parts, details, or accessories, of pumps or pumping systems specially adapted for elastic fluids, not otherwise provided for in, or of interest apart from, groups F04B25/00 - F04B37/00
    • F04B39/12—Casings; Cylinders; Cylinder heads; Fluid connections
    • F04B39/123—Fluid connections

Abstract

The invention discloses an opposed direct-current moving coil linear compressor with an embedded one-way valve and a design method, wherein the integral structure of the compressor adopts an opposed design to counteract the mechanical vibration of a left part and a right part, and an embedded air inlet one-way valve and an exhaust one-way valve are radially designed on a shared base to realize direct-current output; the left part and the right part are respectively composed of a pole shoe, a permanent magnet, a magnetic pole, a current-carrying coil, a coil rack, a piston shaft, a lower supporting plate spring group, an upper supporting plate spring group, a framework and a casing outside the shared base, and the coil in the rotor part does linear motion in the permanent magnet stable magnetic field part, so that the whole linear compressor reduces mechanical loss caused by friction; the one-way reed valve is embedded in the shared base and consists of a sealing end cover, a positioning sleeve, an air inlet limiter, a reed and an air inlet reed base, and the direct current output characteristic is realized. The invention has compact structure, low vibration, high motor efficiency and long service life.

Description

Opposed direct-current linear compressor adopting embedded one-way valve and design method
Technical Field
The invention belongs to the field of refrigeration and low-temperature engineering, relates to a direct-current linear compressor, and particularly relates to an opposed direct-current linear compressor with an embedded one-way valve and a design method.
Background
The linear compressor is one kind of mechanical compressor, and features that the rotor part reciprocates under the action of the linear driving source, and compared with traditional crank-link piston compressor, the linear compressor has greatly reduced mechanical friction loss caused by non-axial force during motion, raised energy converting efficiency and reduced mechanical vibration and noise. The piston of the valveless high-frequency linear compressor is used for outputting alternating high-frequency oscillation pressure waves outwards under reciprocating motion. The pressure wave can not meet the requirements of a J-T refrigerator applied to refrigeration of a liquid helium temperature region, and an air suction valve and a discharge valve structure are required to be designed at the inlet end and the outlet end to ensure that stable flow pressure wave is output, so that the requirements of J-T refrigeration equipment are met. Aiming at the requirement of J-T refrigeration equipment on pressure waves, a technology for realizing direct-current output in a mode of additionally arranging a one-way detection valve at the external pipeline part of a linear compressor is provided at present, but the technology independently designs the one-way valve and the linear compressor, so that pipelines from the linear compressor to the one-way valve part are all clearance volumes in a compression process, the method seriously loses the compression capacity in the compression process, the single-stage compression ratio of the direct-current compressor is reduced, and further optimization design is rare at present.
Disclosure of Invention
Aiming at the defects in the design of the conventional direct current compressor, the invention provides an opposed direct current linear compressor with an embedded one-way valve by adopting an embedded one-way valve, and a design method of the opposed direct current linear compressor.
The opposed direct-current linear compressor with the embedded one-way valve comprises a shared base 1, a left pole shoe 2, a left permanent magnet 3, a left magnetic pole 4, a left current-carrying coil 5, a left coil frame 6, a left piston shaft 7, a left lower support plate spring group 8, a left upper support plate spring group 24, a left framework 23, a left machine shell 9, a right pole shoe 2 ', a right permanent magnet 3', a right magnetic pole 4 ', a right current-carrying coil 5', a right coil frame 6 ', a right piston shaft 7', a right lower support plate spring group 8 ', a right upper support plate spring group 24', a right framework 23 'and a right machine shell 9'.
The whole structure of the compressor adopts an opposite design to offset the mechanical vibration of the left part and the right part, namely the whole structure takes a vertical central line 10 as a symmetry axis, and the design and the assembly mode of the left structure and the right structure are mirror symmetry. Two groups of one-way reed valve structures are embedded in the radial direction of the shared base 1, namely an air inlet one-way reed valve structure 21 and an air outlet one-way reed valve structure 22, and the axes of the two groups of structures are in 180-degree opposite design. The two groups of reed valve structures are non-axisymmetrical structures, the air inlet one-way reed valve structure 21 is composed of a sealing end cover 11, a positioning sleeve 12, an air inlet limiter 13, reeds 14 and an air inlet reed base 15, the reeds 14 are tightly matched with the reed base 15, are tightly matched in an air inlet radial countersunk holes 16 through the limiter 13, and are fastened by screws. The spring 14 is a flexible metal sheet with good bending properties and fatigue resistance. The positioning sleeve 12 and the sealing end cover 11 are used for pressing the air inlet reed valve structure and are fixed on the common base 1 through threads, and the sealing end cover 11 and the common base 1 are sealed through an O-shaped ring to ensure air tightness. The sum of the radial sizes of the whole air inlet reed valve structure 21 is 0.1-0.3 mm larger than the depth of the air inlet radial counter sink 16, and the air tightness of the O-shaped ring sealing structure is guaranteed. The exhaust port reed valve structure 22 is similar to the intake port reed valve structure 21 and comprises a sealing end cover 11, a positioning sleeve 12, an exhaust port limiter 13 ', a reed 14 and an exhaust port reed base 15 ', but the assembly mode, the exhaust port limiter 13 ' and the exhaust port reed base 15 ' are different from the intake port reed structure 21 due to different functions and operation conditions, the exhaust port limiter 13 ' is assembled at the innermost part of the exhaust port radial countersunk hole 17, and the reed 14 is assembled at the exhaust port limiter 13 ' after being embedded in the exhaust port reed base 15 '. In addition, the design dimensions of vent retainer 13 'and vent reed base 15' are different from those of the inlet port, depending on the specific amount of air passing, and are discussed in detail in the design. The left permanent magnet 3 is a cylinder structure, is made of strong magnetic material, is arranged in the left pole shoe 2 through a center hole, and is fixed by the left magnetic pole 4 to form a stable permanent magnet structure. The left pole shoe 2 is a U-shaped body, the diameter of the groove is larger than that of the left permanent magnet 3, and the rest gap is the movement space of the left current-carrying coil 5 and is fixed on the magnet locking platform 18. The maximum stroke of the left current-carrying coil 5 is s in work and is always positioned in the gap of the magnet structure, so that the coil is always under the action of a stable magnetic field in motion. The left part supports leaf spring group 8 and is divided into two sets of front and back, and on the preceding group was fixed in leaf spring locking platform 19, the back group was fixed in on the left part skeleton 23, and every group comprises 3 ~ 4 leaf springs and middle packing ring, through screw locking to support left part piston shaft 7. The rod part of the left piston shaft 7 sequentially penetrates through a left lower supporting plate spring group 8, a left pole shoe 2, a left permanent magnet 3, a left magnetic pole 4, a left coil frame 6, a left framework 23 and a left upper supporting plate spring group 24 from the center to the outside, wherein the left piston shaft 7, the left current-carrying coil 5 and the left coil frame 6 jointly form a left rotor part, the shared base 1, the left pole shoe 2, the left permanent magnet 3, the left magnetic pole 4 and the left framework 23 jointly form a stator part, the rotor and the stator form flexible connection by virtue of the left lower supporting plate spring group 8 and the left upper supporting plate spring group 23, and the rotor part can be ensured to linearly reciprocate under the limitation of the stator. The left machine shell 9 is of a U-shaped bell jar structure, forms sealing with the shared base 1 through an O-shaped ring structure, and is locked through screws. The right structure consists of a right pole shoe 2 ', a right permanent magnet 3', a right magnetic pole 4 ', a right current-carrying coil 5', a right coil frame 6 ', a right piston shaft 7', a right lower supporting plate spring group 8 ', a right upper supporting plate spring group 24', a right framework 23 'and a right machine shell 9', and the right structure and the left structure are mirror images, so that the opposed moving coil direct-current linear compressor is formed.
The design method of the opposed direct-current moving coil linear compressor with the embedded one-way valve is totally divided into seven steps:
the method comprises the following steps: according to actual requirements, determining the performance parameters of the designed compressor facing to the outside, including scavenging volume V and maximum input work PmaxMaximum mass flow rate
Figure BDA0002970957850000031
Etc. where the scavenging volume is set to an initial value is the base point for the entire design process.
Step two: the structural size of the cylinder is determined, and the structural size comprises the diameters d of the left piston shaft 7 and the right piston shaft 7', and the motion stroke s of the two piston shafts. The motion stroke s refers to the piston from the lower dead pointThe displacement when the position reaches the upper dead center position is limited by the structure principle of the plate spring, and the actual value is 0.16Ds～0.20DsIn which D issIs the leaf spring diameter. In the design process, in order to ensure that the gas spring force and the motor force are balanced in the piston operation process, the existence formula [1] of the piston diameter d and the stroke s is usually set]The relationship is:
1.8s＜d＜2.5s [1]
step three: the compressor design optimum operating frequency f is determined. The opposed type direct current linear compressor has an optimal operation frequency which is equal to the resonance frequency of the mover part when the compressor operates stably, and under the frequency, the opposed type direct current linear compressor reaches the maximum operation efficiency and the mechanical loss reaches the minimum. The mover section resonance frequency f is determined by the equation [2 ]:
Figure BDA0002970957850000041
wherein k ismIs the hooke coefficient, k, of the leaf springgThe equivalent hooke coefficient of the gas spring, and m is the weight of the rotor part. The design process is a reverse process of calculating the optimum frequency according to the maximum mass flow rate in the design condition
Figure BDA0002970957850000042
And determining the running frequency of the compressor by the scavenging volume V of the cylinder, and designing structures such as a plate spring and the like to meet the relation that the resonant frequency is close to the design frequency.
Step four: determining structural parameters of the leaf spring, including the thickness t of the leaf springsAnd leaf spring diameter DsAnd the number of leaf springs per group. Leaf spring diameter DsDetermining the stroke of the piston in the second step; leaf spring thickness tsAnd the number of the sheets in each group is determined by the hooke's coefficient k of the leaf spring in the third stepmAnd (4) determining an optimal value, selecting high-fatigue-resistance metal for the plate spring material, and determining the specific thickness and the number of the plates according to the structural characteristic parameters of the selected metal material.
Step five: determining current-carrying coil parameters, including coil diameter Dc andthe number of coil turns n. Determining motor force F according to the vibration vector balance equation of the compressormSize:
Fm＝Fg+Fs+Fa [3]
|Fm|＝BIL [4]
Figure BDA0002970957850000051
Figure BDA0002970957850000052
|Fa|＝2π2f2sm [7]
wherein, FmThe motor force to which the coil is subjected in the magnetic field, FgThe resistance of the gas spring to the movement of the piston, FsIs the elastic force of the plate spring, FaIs inertia force, B is magnetic field intensity, I is current density in coil, L is total coil length, delta P is pressure difference between gas in cylinder and back pressure cavity, D is piston diameter, kmThe plate spring stiffness is shown as s, the piston stroke is shown as f, the operating frequency is shown as m, and the mover mass is shown as m.
The magnetic field intensity B is determined by a left pole shoe 2, a left permanent magnet 3, a left magnetic pole 4, a right pole shoe 2 ', a right permanent magnet 3 ' and a right magnetic pole 4 ', and the value of the magnetic field intensity B is usually within the range of 0.8-1.0T and is measured after magnetization. The current I is determined by input parameters, the maximum value is limited by the current carrying capacity of the coil, and the coil is burnt and damaged when the maximum value exceeds the rated current.
Step six: according to the structural parameter values determined in the steps, the structure and the size of the related fixing piece are designed so as to meet the following assembly requirements: the structure size of the shared base 1, the left pole shoe 2, the left coil former 6, the left framework 23), the left machine shell 9, the right pole shoe 2 ', the right coil former 6', the right framework 23 'and the right machine shell 9'. The main assembly design comprises a threaded connection between the common base 1 and the left pole shoe 2; the left framework 23 is in threaded connection with the left pole shoe 2; the relative position between the left coil former 6 and the left pole piece 2 is fixed.
Step seven: the structural size of the one-way reed valve is designed according to the preset working condition and mainly comprises the diameter D of the air passing hole gapvAnd limiting height h of the reed valve. Diameter D of air gapvThe value is determined by the maximum flow rate, and the value meets the air gap Mach number within the range of 0.1-0.25. Height h of reed is of the formula [8]Determining:
Figure BDA0002970957850000053
due to different gas states of the gas inlet and the gas outlet, the air gap diameter Dv of the inlet reed valve structure 21 and the air gap diameter Dv of the exhaust reed valve structure 22 are slightly different, and the corresponding lift h is also slightly different.
And finally, determining structural parameters of a reed valve fitting, namely the sealing end cover 11 and the positioning sleeve 12 according to the structural size of the reed valve, completing the design of a sealing structure, and ensuring that air flow at an inlet and an outlet only flows in and is exhausted through an air gap. At this point, the design process of the opposed dc linear compressor is completed.
Drawings
FIG. 1 is a schematic cross-sectional view of an opposed DC linear compressor with an embedded check valve according to the present invention;
FIG. 2 is a schematic cross-sectional view of the intake and exhaust check valve;
fig. 3 is a schematic view of the structure of the base shared by the embedded check valves.
Wherein: 1 is a common base; 2 is a left pole shoe, 2' is a left pole shoe; 3 is a left permanent magnet, and 3' is a right permanent magnet; 4 is a left magnetic pole, 4' is a right magnetic pole; 5 is a left current-carrying coil, and 5' is a right current-carrying coil; 6 is a left coil frame, 6' is a right coil frame; 7 is a left piston shaft, and 7' is a right piston shaft; 8 is a left lower support plate spring group, and 8' is a right lower support plate spring group; 9 is a left machine shell, and 9' is a right machine shell; 10 is a vertical central symmetry axis; 11 is a sealing end cover; 12 is a positioning sleeve; 13 is an air inlet limiter, and 13' is an air outlet limiter; 14 is a reed; 15 is an air inlet reed base, and 15' is an air outlet reed base; 16 is a radial countersunk hole of the air inlet; 17 is a radial countersunk hole of the exhaust port; 18 is a magnet locking platform; 19 is a plate spring locking platform; 20 is an air gap channel; 21 is a one-way reed valve structure of an air inlet; 22 is an exhaust port reed valve structure; 23 is a left skeleton, and 23' is a right skeleton; 24 is a left upper support plate spring set and 24' is a right upper support plate spring set.
Detailed Description
The structure and design method of the direct current linear compressor with the embedded check valve will be described in detail with reference to the accompanying drawings.
The opposed direct-current linear compressor with the embedded one-way valve comprises a shared base 1, a left pole shoe 2, a left permanent magnet 3, a left magnetic pole 4, a left current-carrying coil 5, a left coil frame 6, a left piston shaft 7, a left lower support plate spring group 8, a left upper support plate spring group 24, a left framework 23, a left shell 9, a right pole shoe 2 ', a right permanent magnet 3', a right magnetic pole 4 ', a right current-carrying coil 5', a right coil frame 6 ', a right piston shaft 7', a right lower support plate spring group 8 ', a right upper support plate spring group 24', a right framework 23 'and a right shell 9', as shown in the figure I. The structure is characterized in that the whole structure adopts an opposite design to counteract the mechanical vibration of the left part and the right part, namely the whole structure takes a vertical central line 10 as a symmetry axis, and the design and the assembly mode of the left structure and the right structure are mirror symmetry. Two groups of one-way reed valve structures are embedded in the radial direction of the shared base 1, namely an air inlet one-way reed valve structure 21 and an air outlet one-way reed valve structure 22, and the axes of the two groups of structures are in 180-degree opposite design. The two groups of reed valve structures are non-axisymmetrical structures, the air inlet one-way reed valve structure 21 is composed of a sealing end cover 11, a positioning sleeve 12, an air inlet limiter 13, reeds 14 and an air inlet reed base 15, the reeds 14 are tightly matched with the reed base 15, are tightly matched in an air inlet radial countersunk holes 16 through the limiter 13, and are fastened by screws. The spring 14 is a flexible metal sheet with good bending properties and fatigue resistance. The positioning sleeve 12 and the sealing end cover 11 are used for pressing the air inlet reed valve structure and are fixed on the common base 1 through threads, and the sealing end cover 11 and the common base 1 are sealed through an O-shaped ring to ensure air tightness. The sum of the radial sizes of the whole air inlet reed valve structure 21 is 0.1-0.3 mm larger than the depth of the air inlet radial counter sink 16, and the air tightness of the O-shaped ring sealing structure is guaranteed. The exhaust port reed valve structure 22 is similar to the intake port reed valve structure 21 and comprises a sealing end cover 11, a positioning sleeve 12, an exhaust port limiter 13 ', a reed 14 and an exhaust port reed base 15 ', but the assembly mode, the exhaust port limiter 13 ' and the exhaust port reed base 15 ' are different from the intake port reed structure 21 due to different functions and operation conditions, the exhaust port limiter 13 ' is assembled at the innermost part of the exhaust port radial countersunk hole 17, and the reed 14 is assembled at the exhaust port limiter 13 ' after being embedded in the exhaust port reed base 15 '. In addition, the design dimensions of vent retainer 13 'and vent reed base 15' are different from those of the inlet port, depending on the specific amount of air passing, and are discussed in detail in the design. The left permanent magnet 3 is a cylinder structure, is made of strong magnetic material, is arranged in the left pole shoe 2 through a center hole, and is fixed by the left magnetic pole 4 to form a stable permanent magnet structure. The left pole shoe 2 is a U-shaped body, the diameter of the groove is larger than that of the left permanent magnet 3, and the rest gap is the movement space of the left current-carrying coil 5 and is fixed on the magnet locking platform 18. The maximum stroke of the left current-carrying coil 5 is s in work and is always positioned in the gap of the magnet structure, so that the coil is always under the action of a stable magnetic field in motion. The left part supports leaf spring group 8 and is divided into two sets of front and back, and on the preceding group was fixed in leaf spring locking platform 19, the back group was fixed in on the left part skeleton 23, and every group comprises 3 ~ 4 leaf springs and middle packing ring, through screw locking to support left part piston shaft 7. The rod part of the left piston shaft 7 sequentially penetrates through a left lower supporting plate spring group 8, a left pole shoe 2, a left permanent magnet 3, a left magnetic pole 4, a left coil frame 6, a left framework 23 and a left upper supporting plate spring group 24 from the center to the outside, wherein the left piston shaft 7, the left current-carrying coil 5 and the left coil frame 6 jointly form a left rotor part, the shared base 1, the left pole shoe 2, the left permanent magnet 3, the left magnetic pole 4 and the left framework 23 jointly form a stator part, the rotor and the stator form flexible connection by virtue of the left lower supporting plate spring group 8 and the left upper supporting plate spring group 23, and the rotor part can be ensured to linearly reciprocate under the limitation of the stator. The left machine shell 9 is of a U-shaped bell jar structure, forms sealing with the shared base 1 through an O-shaped ring structure, and is locked through screws. The right structure consists of a right pole shoe 2 ', a right permanent magnet 3', a right magnetic pole 4 ', a right current-carrying coil 5', a right coil frame 6 ', a right piston shaft 7', a right lower supporting plate spring group 8 ', a right upper supporting plate spring group 24', a right framework 23 'and a right machine shell 9', and the right structure and the left structure are mirror images, so that the opposed moving coil direct-current linear compressor is formed.
The design method of the opposed direct-current moving coil linear compressor with the embedded one-way valve is totally divided into seven steps:
the method comprises the following steps: according to actual requirements, determining the performance parameters of the designed compressor facing to the outside, including scavenging volume V and maximum input work PmaxMaximum mass flow rate
Figure BDA0002970957850000081
Etc. where the scavenging volume is set to the initial value, which is the base point for the entire design process, e.g. a maximum mass flow rate of 30mg/s, with a scavenging volume of 20cc of linear direct flow compressor.
Step two: the structural size of the cylinder is determined, and the structural size comprises the diameters d of the left piston shaft 7 and the right piston shaft 7', and the motion stroke s of the two piston shafts. The motion stroke s refers to the displacement of the piston from the bottom dead center position to the top dead center position, and is limited by the plate spring structure principle, and the actual value is 0.16Ds～0.20DsIn which D issIs the leaf spring diameter. In the design process, in order to ensure that the gas spring force and the motor force are balanced in the piston operation process, the existence formula [1] of the piston diameter d and the stroke s is usually set]The relationship is:
1.8s＜d＜2.5s [1]
the piston diameter of the opposed linear direct current compressor of 20cc according to the equation [1], was set to 30mm, and the stroke was set to 14.1mm.
Step three: the compressor design optimum operating frequency f is determined. The opposed type direct current linear compressor has an optimal operation frequency which is equal to the resonance frequency of the mover part when the compressor operates stably, and under the frequency, the opposed type direct current linear compressor reaches the maximum operation efficiency and the mechanical loss reaches the minimum. The mover section resonance frequency f is determined by the equation [2 ]:
Figure BDA0002970957850000091
wherein k ismIs the hooke coefficient, k, of the leaf springgThe equivalent hooke coefficient of the gas spring, and m is the weight of the rotor part. The design process is a reverse process of calculating the optimum frequency according to the maximum mass flow rate in the design condition
Figure BDA0002970957850000092
And determining the operation frequency of the compressor by the scavenging volume V of the air cylinder, designing structures such as a plate spring and the like to meet the relation that the resonance frequency is close to the design frequency, wherein the optimal operation frequency in the actual design is 35 Hz.
Step four: determining structural parameters of the leaf spring, including the thickness t of the leaf springsAnd leaf spring diameter DsAnd the number of leaf springs per group. Leaf spring diameter DsDetermining the stroke of the piston in the second step; leaf spring thickness tsAnd the number of the sheets in each group is determined by the hooke's coefficient k of the leaf spring in the third stepmAnd (4) determining an optimal value, selecting high-fatigue-resistance metal for the plate spring material, and determining the specific thickness and the number of the plates according to the structural characteristic parameters of the selected metal material.
Step five: and determining current-carrying coil parameters which mainly comprise the coil diameter Dc and the number n of coil turns. Determining motor force F according to the vibration vector balance equation of the compressormSize:
Fm＝Fg+Fs+Fa [3]
|Fm|＝BIL [4]
Figure BDA0002970957850000101
Figure BDA0002970957850000102
|Fa|＝2π2f2sm [7]
wherein, FmThe motor force to which the coil is subjected in the magnetic field, FgThe resistance of the gas spring to the movement of the piston, FsIs the elastic force of the plate spring, FaIs inertia force, B is magnetic field intensity, I is current density in coil, L is total coil length, delta P is pressure difference between gas in cylinder and back pressure cavity, D is piston diameter, kmThe plate spring stiffness is shown as s, the piston stroke is shown as f, the operating frequency is shown as m, and the mover mass is shown as m.
The magnetic field intensity B is determined by a left pole shoe 2, a left permanent magnet 3, a left magnetic pole 4, a right pole shoe 2 ', a right permanent magnet 3 ' and a right magnetic pole 4 ', and the value of the magnetic field intensity B is usually within the range of 0.8-1.0T and is measured after magnetization. The current I is determined by input parameters, the maximum value is limited by the current carrying capacity of the coil, and the coil is burnt and damaged when the maximum value exceeds the rated current. In practical designs, the current carrying coil current does not reach the input upper limit due to stroke limitations.
Step six: according to the structural parameter values determined in the steps, the structure and the size of the related fixing piece are designed so as to meet the following assembly requirements: the structure size of the shared base 1, the left pole shoe 2, the left coil former 6, the left framework 23), the left machine shell 9, the right pole shoe 2 ', the right coil former 6', the right framework 23 'and the right machine shell 9'. The main assembly design comprises a threaded connection between the common base 1 and the left pole shoe 2; the left framework 23 is in threaded connection with the left pole shoe 2; the relative position between the left coil former 6 and the left pole piece 2 is fixed.
Step seven: the structural size of the one-way reed valve is designed according to the preset working condition and mainly comprises the diameter D of the air passing hole gapvAnd limiting height h of the reed valve. Diameter D of air gapvThe value is determined by the maximum flow rate, and the value meets the air gap Mach number within the range of 0.1-0.25. Height h of reed is of the formula [8]Determining:
Figure BDA0002970957850000111
due to different gas states of the gas inlet and the gas outlet, the air gap diameters Dv of the gas inlet reed valve structure 21 and the gas outlet reed structure 22 are slightly different, the corresponding lift ranges h are also slightly different, and finally the lift range of the gas inlet is determined to be 0.5mm, the lift range of the gas outlet is determined to be 0.6mm, and the thickness of the reed is 0.15 mm.
And finally, determining structural parameters of a reed valve fitting, namely the sealing end cover 11 and the positioning sleeve 12 according to the structural size of the reed valve, completing the design of a sealing structure, and ensuring that air flow at an inlet and an outlet only flows in and is exhausted through an air gap. At this point, the design process of the opposed type dc linear compressor with the scavenging volume of 20cc is completed.

Claims (2)

1. An opposed direct-current linear compressor adopting an embedded one-way valve comprises a shared base (1), a left pole shoe (2), a left permanent magnet (3), a left magnetic pole (4), a left current-carrying coil (5), a left coil frame (6), a left piston shaft (7), a left lower supporting plate spring group (8), a left upper supporting plate spring group (24), a left framework (23), a left machine shell (9), a right pole shoe (2 '), a right permanent magnet (3'), a right magnetic pole (4 '), a right current-carrying coil (5'), a right coil frame (6 '), a right piston shaft (7'), a right lower supporting plate spring group (8 '), a right upper supporting plate spring group (24'), a right framework (23 ') and a right machine shell (9'); it is characterized in that the preparation method is characterized in that,
the integral structure of the compressor adopts an opposed design to counteract the mechanical vibration of the left part and the right part, namely the integral structure takes a vertical central line (10) as a symmetry axis, and the design and the assembly mode of the left structure and the right structure are mirror symmetry; two groups of one-way reed valve structures are embedded in the radial direction of the shared base (1), namely an air inlet one-way reed valve structure (21) and an air outlet one-way reed valve structure (22), and the axes of the two groups of structures are oppositely arranged at 180 degrees; the two groups of reed valve structures are non-axisymmetric structures, the air inlet one-way reed valve structure (21) is composed of a sealing end cover (11), a positioning sleeve (12), an air inlet limiter (13), reeds (14) and an air inlet reed base (15), the reeds (14) are tightly matched with the reed base (15), are tightly matched in an air inlet radial countersunk hole (16) of the shared base (1) through the limiter (13), and are fastened by screws; the reed (14) is a flexible metal sheet and has good bending property and fatigue resistance; the positioning sleeve (12) and the sealing end cover (11) are used for tightly pressing the air inlet reed valve structure and are fixed on the common base (1) through threads, and the sealing end cover (11) and the common base (1) are sealed through an O-shaped ring to ensure air tightness; the sum of the radial dimensions of the whole air inlet reed valve structure (21) is 0.1-0.3 mm larger than the depth of a counter bore of the common base (1), so that the air tightness of the O-shaped ring sealing structure is ensured; the exhaust port reed valve structure (22) is similar to the air inlet reed valve structure (21) and comprises a sealing end cover (11), a positioning sleeve (12), an exhaust port limiter (13 '), reeds (14) and an exhaust port reed base (15 '), but the assembly mode, the exhaust port limiter (13 ') and the exhaust port reed base (15 ') are different from the air inlet reed structure (21) due to different functions and operating conditions, the exhaust port limiter (13 ') is assembled at the innermost part of the exhaust port radial countersunk hole (17), and the reeds (14) are embedded in the exhaust port reed base (15 ') and then assembled in the exhaust port limiter (13 '); besides, the design sizes of the exhaust port limiter (13 ') and the exhaust port reed base (15') are different from those of the air inlet, and are determined by specific air passing amount; the left permanent magnet (3) is of a cylindrical structure, is made of a strong magnetic material, is arranged in the left pole shoe (2) through a central hole, and is fixed by a left magnetic pole (4) to form a stable permanent magnet structure; the left pole shoe (2) is a U-shaped body, the diameter of the groove is larger than that of the left permanent magnet (3), and the rest gap is the movement space of the left current-carrying coil (5) and is fixed on the magnet locking platform (18); the maximum stroke of the left current-carrying coil (5) is s in work and is always positioned in the gap of the magnet structure, so that the coil is always under the action of a stable magnetic field in motion; the left supporting plate spring component is divided into a front group and a rear group, the front group is fixed on a plate spring locking platform (19), the rear group is fixed on a left framework (23), each group consists of 3-4 plate springs and a middle washer, and the left supporting plate spring component is locked by screws to support a left piston shaft (7); a rod part of a left piston shaft (7) sequentially penetrates through a left lower supporting plate spring group (8), a left pole shoe (2), a left permanent magnet (3), a left magnetic pole (4), a left coil frame (6), a left framework (23) and a left upper supporting plate spring group (24) from the center to the outside, wherein the left piston shaft (7), the left current-carrying coil (5) and the left coil frame (6) jointly form a left rotor part, a shared base (1), the left pole shoe (2), the left permanent magnet (3), the left magnetic pole (4) and the left framework (23) jointly form a stator part, the rotor and the stator form flexible connection by virtue of the left lower supporting plate spring group (8) and the left upper supporting plate spring group (23), and the rotor part can perform linear reciprocating motion under the limitation of the stator; the left machine shell (9) is of a U-shaped bell jar structure, forms sealing with the shared base (1) through an O-shaped ring structure and is locked by screws; the right structure consists of a right pole shoe (2 '), a right permanent magnet (3'), a right magnetic pole (4 '), a right current-carrying coil (5'), a right coil frame (6 '), a right piston shaft (7'), a right lower supporting plate spring group (8 '), a right upper supporting plate spring group (24'), a right framework (23 ') and a right machine shell (9'), and the right structure and the left structure are mirror images, so that the opposed moving coil direct current linear compressor is formed.
2. A method for designing an opposed direct-current moving coil linear compressor with an embedded check valve as defined in claim 1, comprising the steps of:
the method comprises the following steps: according to actual requirements, determining the performance parameters of the designed compressor facing to the outside, including scavenging volume V and maximum input work PmaxMaximum mass flow rate
Figure FDA0002970957840000032
And the scavenging volume is a set initial value and is a base point of the whole design process;
step two: determining the structural size of a cylinder, wherein the structural size comprises the diameters d of a left piston shaft (7) and a right piston shaft (7'), and the motion strokes s of the two piston shafts; the motion stroke s refers to the displacement of the piston from the bottom dead center position to the top dead center position, and is limited by the plate spring structure principle, and the actual value is 0.16Ds～0.20DsIn which D issIs the diameter of the leaf spring; during the design process, in order to ensure the gas spring force andthe motor forces are balanced, usually by setting the formula [1] between the piston diameter d and the stroke s]The relationship is:
1.8s＜d＜2.5s [1]
step three: determining the optimal design operating frequency f of the compressor, wherein the optimal operating frequency of the opposed direct-current linear compressor exists, the operating frequency is equal to the resonant frequency of a rotor part when the compressor operates stably, and under the frequency, the opposed direct-current linear compressor achieves the maximum operating efficiency and the mechanical loss is the minimum; the mover section resonance frequency f is determined by the equation [2 ]:
Figure FDA0002970957840000031
wherein k ismIs the hooke coefficient, k, of the leaf springgThe equivalent hooke coefficient of the gas spring is shown, and m is the mass of the rotor part;
the design process is a reverse process of calculating the optimum frequency according to the maximum mass flow rate in the design condition
Figure FDA0002970957840000033
Determining the running frequency of the compressor by the scavenging volume V of the cylinder, and designing structures such as a plate spring and the like to meet the relation that the resonant frequency is close to the design frequency;
step four: determining structural parameters of the leaf spring, including the thickness t of the leaf springsAnd leaf spring diameter DsAnd the number of leaf springs in each group; leaf spring diameter DsDetermining the stroke of the piston in the second step; leaf spring thickness tsAnd the number of the sheets in each group is determined by the hooke's coefficient k of the leaf spring in the third stepmDetermining an optimal value, selecting high fatigue resistance metal for the plate spring material, and determining the specific thickness and the number of pieces according to the structural characteristic parameters of the selected metal material;
step five: determining current-carrying coil parameters which mainly comprise coil diameter Dc and coil turn number n; determining motor force F according to the vibration vector balance equation of the compressormSize:
Fm＝Fg+Fs+Fa [3]
|Fm|＝BIL [4]
Figure FDA0002970957840000041
Figure FDA0002970957840000042
|Fa|＝2π2f2sm [7]
wherein, FmThe motor force to which the coil is subjected in the magnetic field, FgThe resistance of the gas spring to the movement of the piston, FsIs the elastic force of the plate spring, FaIs inertia force, B is magnetic field intensity, I is current density in coil, L is total coil length, delta P is pressure difference between gas in cylinder and back pressure cavity, D is piston diameter, kmThe stiffness of a plate spring is adopted, s is the piston stroke, f is the operating frequency, and m is the rotor mass;
the magnetic field intensity B is determined by a left pole shoe (2), a left permanent magnet (3), a left magnetic pole (4), a right pole shoe (2 '), a right permanent magnet (3 ') and a right magnetic pole (4 '), the value of the magnetic field intensity B is usually in the range of 0.8-1.0T, and the magnetic field intensity B is measured after magnetization; the current I is determined by input parameters, the maximum value is limited by the current carrying capacity of the coil, and the coil is burnt and damaged when the maximum value exceeds the rated current, so that the coil structure is damaged;
step six: according to the structural parameter values determined in the steps, the structure and the size of the related fixing piece are designed so as to meet the following assembly requirements: the structure sizes of a shared base (1), a left pole shoe (2), a left coil former (6), a left framework (23), a left machine shell (9), a right pole shoe (2 '), a right coil former (6'), a right framework (23 ') and a right machine shell (9'); the main assembly design comprises a threaded connection between a shared base (1) and a left pole shoe (2); the left framework (23) is in threaded connection with the left pole shoe (2); the relative position between the left coil frame (6) and the left pole shoe (2) is fixed;
step seven: according to preset working conditionsMeasuring the structural size of a one-way reed valve; including the diameter D of the air gapvThe limiting height h of the reed valve; diameter D of air gapvThe value of the flow rate is determined by the maximum flow rate, and the Mach number of the air gap is in the range of 0.1-0.25; height h of reed is of the formula [8]Determining:
Figure FDA0002970957840000051
the gas states of the gas inlet and the gas outlet are different, so that the gas gap diameters Dv of the inlet reed valve structure (21) and the exhaust reed structure (22) are slightly different, and the corresponding lift ranges h are also slightly different;
and finally, determining structural parameters of a reed valve fitting, namely a sealing end cover (11) and a positioning sleeve (12), according to the structural size of the reed valve, completing the design of a sealing structure, and ensuring that air flow at an inlet and an outlet only flows in and is exhausted through an air gap.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20030044671A (en) * 2001-11-30 2003-06-09 엘지전자 주식회사 Opposed type reciprocating compressor
CN103671000A (en) * 2013-11-21 2014-03-26 中国科学院上海技术物理研究所 Oppositely-arranged moving coil linear compressor adopting long-coil radial magnetization and manufacturing method
CN208718864U (en) * 2018-05-31 2019-04-09 上海朗旦制冷技术有限公司 A kind of oil-free linear compressor of double cylinder opposed type
CN112160895A (en) * 2020-09-15 2021-01-01 中国科学院上海技术物理研究所 Double-cantilever type reed valve for linear direct-current piston compressor and design method thereof
CN112253421A (en) * 2020-11-10 2021-01-22 江苏上骐重工科技有限公司 Wearable air conditioner is with oilless linear drive compressor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20030044671A (en) * 2001-11-30 2003-06-09 엘지전자 주식회사 Opposed type reciprocating compressor
CN103671000A (en) * 2013-11-21 2014-03-26 中国科学院上海技术物理研究所 Oppositely-arranged moving coil linear compressor adopting long-coil radial magnetization and manufacturing method
CN208718864U (en) * 2018-05-31 2019-04-09 上海朗旦制冷技术有限公司 A kind of oil-free linear compressor of double cylinder opposed type
CN112160895A (en) * 2020-09-15 2021-01-01 中国科学院上海技术物理研究所 Double-cantilever type reed valve for linear direct-current piston compressor and design method thereof
CN112253421A (en) * 2020-11-10 2021-01-22 江苏上骐重工科技有限公司 Wearable air conditioner is with oilless linear drive compressor

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