CN111561437B

CN111561437B - Oil-free linear compressor for heat pump system

Info

Publication number: CN111561437B
Application number: CN202010257746.6A
Authority: CN
Inventors: 周强; 张建伟; 刘思学; 王录; 何江; 范宇峰; 赵欣; 满广龙; 苗建印
Original assignee: Beijing Institute of Spacecraft System Engineering
Current assignee: Beijing Institute of Spacecraft System Engineering
Priority date: 2020-04-03
Filing date: 2020-04-03
Publication date: 2021-09-24
Anticipated expiration: 2040-04-03
Also published as: CN111561437A

Abstract

The invention discloses an oil-free linear compressor for a heat pump system, which comprises: the air cylinder, the air cylinder frame, the linear motor component, the air suction valve plate, the exhaust valve assembly and the shell; the flange plate ends of the two cylinder frames are symmetrically arranged at the two ends of the cylinder; two identical linear motor assemblies are respectively and correspondingly arranged outside the central cylinders of the two cylinder frames; the outer edges of the two air suction valve plates are respectively fixed at the opposite ends of the two pistons; the exhaust valve assembly is arranged in the exhaust cavity; the two shells are respectively arranged outside the two linear motor assemblies, and the opening ends of the shells are fixed on the outer edges of the flange plates of the cylinder frame; the piston is directly driven by the two linear motor assemblies arranged oppositely to reciprocate, so that the compression efficiency of the compressor is improved; the opposite movement of the two pistons can offset most of vibration, so that the vibration quantity of the whole machine is smaller; the oil-free operation can avoid the limitation of system performance, reliability and use scenes caused by lubricating oil, and greatly increase the application range of the oil-free lubricating system.

Description

Oil-free linear compressor for heat pump system

Technical Field

The invention belongs to the technical field of compressors, and particularly relates to an oil-free linear compressor for a heat pump system.

Background

The traditional reciprocating refrigeration compressor usually uses a rotary motor to drive a piston to complete processes of compression, exhaust and the like, so as to realize refrigeration effect, and when rotary motion is converted into reciprocating motion, because of the existence of mechanical structures such as a crank connecting rod and the like, the friction loss of the crank connecting rod structure is large, and the mechanical efficiency is low; the rotational inertia is difficult to balance, and the whole machine has large vibration; in order to ensure the reliability of the friction pair, the lubricating oil of the refrigerating machine is also needed to be lubricated, and the lubricating oil enters a throttling device (particularly a micro-channel) to cause the reduction and even loss of the refrigerating capacity, thereby affecting the performance and the reliability of the system; as the lubricating oil needs to be still at the bottom of the compressor shell, the installation and use angles of the compressor need to be strictly limited during operation, and the use scenes are greatly limited.

The linear compressor sucks refrigerant gas into a cylinder, and compresses the refrigerant gas by reciprocating a piston in the cylinder by a driving force of a linear motor to finally realize a refrigerating effect. The linear compressor has the advantages of less friction points, compact structure, higher efficiency and higher reliability. The linear compressor has the condition of oil-free lubrication operation because the plate spring has excellent radial supporting function. In the existing oil-free operation technology, the following two schemes are mainly adopted:

the first is to use gas bearings to realize oil-free operation, i.e. the rotor part is provided with axial stiffness by a flexible plate spring, and the piston and the cylinder use gas bearings to realize oil-free operation, see fig. 1. Since the gas bearing requires a high-pressure side gas return flow and is throttled into the piston-cylinder gap by means of a throttle device arranged on the piston, the main disadvantages of this solution are:

1. high-pressure side gas is consumed, and the system efficiency is reduced;

2. the single-side plate spring is adopted, so that the radial supporting effect cannot be achieved, the friction still exists between the piston and the cylinder when the compressor is started, and tiny impurities or friction products generated in long-term starting in the compressor easily block the throttling device, so that the gas bearing fails;

3. in order to play a role in supporting the gas bearing gap, the matching surface between the piston and the cylinder is often designed to be longer, which is not beneficial to the miniaturization and the light weight of the whole machine size.

The second kind adopts self-lubricating material to realize not having oil motion, and the active cell part also provides axial rigidity by the flexplate spring promptly, and the piston is provided with self-lubricating material, realizes not having oil operation through reducing the friction, refers to figure 2. Due to the adoption of single-side plate spring support and the realization of oil-free operation by the material with self-lubricating property, the main disadvantages of the scheme are as follows:

1. the single-side plate spring support is difficult to counteract the movement deflection of the rotor component caused by gravity, mainly plays a role in providing axial rigidity, and still has a large abrasion risk after long-term operation.

2. When the material with the self-lubricating property is in operation, frictional foreign matters still can be produced, and a filter is arranged in the whole system, so that the complexity of the system is increased, and the use reliability is reduced.

3. Because the air suction rotor part and the air non-suction rotor part are arranged, the difficulty of controlling the vibration of the whole machine is increased by air suction pulsation and the like.

Disclosure of Invention

In view of this, the present invention provides an oil-free linear compressor for a heat pump system, in which two linear motor assemblies disposed opposite to each other directly drive a piston to reciprocate, so as to improve the compression efficiency of the compressor; the opposite movement of the two pistons can offset most of vibration, so that the vibration quantity of the whole machine is smaller; the oil-free operation can avoid the limitation of system performance, reliability and use scenes caused by lubricating oil, and greatly increase the application range of the oil-free lubricating system.

The invention is realized by the following technical scheme:

an oil-free linear compressor for a heat pump system, comprising: the air cylinder, the air cylinder frame, the linear motor component, the air suction valve plate, the exhaust valve assembly and the shell;

the cylinder is provided with an axial through hole, a radial stepped through hole communicated with the axial through hole and a radial blind hole not communicated with the axial through hole, and two first through holes are formed in the side wall of the radial blind hole; the radial stepped through hole is used as an exhaust cavity, and the radial blind hole is used as an air suction cavity;

the two cylinder frames have the same structure and are both flange-shaped structures, each flange-shaped structure comprises a flange plate and a central cylinder extending out of the middle of the flange plate, and a second through hole is processed in each flange plate; the flange plate ends of the two cylinder frames are symmetrically arranged at the two ends of the cylinder; the central hole of the central cylinder of the cylinder frame is communicated with the axial through hole of the cylinder in a butt joint way, and the central hole of the cylinder frame and the axial through hole of the cylinder form a piston cavity; the second through hole of the cylinder frame is communicated with the first through hole of the cylinder in a butt joint way;

two identical linear motor assemblies are respectively and correspondingly arranged outside the central cylinders of the two cylinder frames; each linear motor assembly includes: an outer stator component, an inner stator component and a rotor component; the outer stator component is arranged outside the central cylinder of the cylinder frame, and the end part of the outer stator component is fixed on a flange plate of the cylinder frame; the inner stator component is sleeved and fixed outside the central cylinder of the cylinder frame; the rotor component is arranged in an annular cavity of the inner circumferential surface of the outer stator component and the outer circumferential surface of the inner stator component, a gap is reserved between the inner circumferential surface of the rotor component and the outer circumferential surface of the inner stator component, a gap is reserved between the outer circumferential surface of the rotor component and the inner circumferential surface of the outer stator component, and two ends of the rotor component are connected with two ends of the outer stator component through a front plate spring group and a rear plate spring group respectively; the rotor component is internally provided with an air suction channel penetrating through a central hole of the cylinder frame, the tail end of the air suction channel is sleeved with a piston, and the outer circumferential surface of the piston is in sliding clearance fit with the inner circumferential surface of the piston cavity; a cavity between the pistons of the two linear motor assemblies is used as a compression cavity, and the compression cavity is communicated with an exhaust cavity; the piston can linearly and repeatedly move along the axial direction under the action of the outer stator part, the inner stator part and the rotor part;

the air suction valve plate is an elastic circular plate A; more than two circular holes which are uniformly distributed along the circumferential direction of the circular plate A and spiral line holes which respectively take the circular holes as starting points and correspond to each other one by one are processed on the circular plate A; the distance between the circle centers of more than two round holes and the circle center of the circular plate A is larger than the sum of the inner diameter of the piston and the radius of the round hole; the outer edges of the two air suction valve plates are respectively fixed at the opposite ends of the two pistons; when the pressure in the compression cavity is smaller than the pressure in the air suction channel, the two air suction valve plates are both in an open state, and the air suction valve plates are not in contact with the end surface of the piston, so that the compression cavity is communicated with the air suction channel through the round holes and the spiral line holes of the air suction valve plates; when the pressure in the compression cavity is greater than or equal to the pressure in the air suction channel, the two air suction valve plates are both in a closed state, and the air suction valve plates are abutted against the end face of the piston, so that the compression cavity is not communicated with the air suction channel;

the exhaust valve assembly is arranged in the exhaust cavity; when the pressure in the compression cavity is greater than a set value, the exhaust valve assembly is in an open state, and the compression cavity is communicated with the exhaust cavity; when the pressure in the compression cavity is smaller than or equal to a set value, the exhaust valve assembly is in a closed state, and the compression cavity is not communicated with the exhaust cavity;

the shell is a cylinder with an opening at one end and a closed end; the two shells are respectively arranged outside the two linear motor components, and the opening ends of the shells are fixed on the outer edge of the flange of the cylinder frame.

Further, the outer stator component includes: the outer stator punching iron core, the two motor coils, the front pressing plate and the rear pressing plate;

the outer stator punching iron core is of a cylindrical structure with openings at two ends, two annular grooves for mounting a motor coil are processed in the side wall of the outer stator punching iron core, and each annular groove is communicated with an inner hole of the outer stator punching iron core;

the two motor coils are respectively arranged in the annular groove of the outer stator punching iron core, an insulating gasket is arranged between the motor coils and the outer stator punching iron core, and the two motor coils are connected in series and have opposite winding directions;

the front pressing plate and the rear pressing plate are respectively fixed at two ends of the outer stator punching iron core; the front pressure plate is fixed on a flange of the cylinder frame;

the inner stator part is an inner stator punching iron core which is of a cylindrical structure with openings at two ends; the inner stator punching iron core is sleeved and fixed outside the small-diameter ends of the two cylinder frames;

the mover member includes: the rotor framework, the two annular magnets, the magnet retaining ring and the magnet retaining sleeve are arranged on the rotor framework;

the rotor framework is a cylinder with one open end and one closed end, a coaxial circular sleeve is arranged in the center of the cylinder, and two ends of the circular sleeve extend out of the cylinder;

the two annular magnets are respectively a first annular magnet and a second annular magnet; the first annular magnet, the magnet retaining ring, the second annular magnet and the magnet retaining sleeve are sequentially and coaxially arranged at the opening end of the cylinder of the rotor framework, and the first annular magnet is in butt joint with the opening end of the cylinder of the rotor framework; and the cylinder of the rotor framework, the two annular magnets, the magnet retaining ring and the magnet retaining sleeve form a magnet sleeve;

the round sleeve of the rotor framework is coaxially arranged in the central hole of the cylinder frame; the magnet sleeve is sleeved between the outer stator punching iron core and the inner stator punching iron core, and the two annular magnets are respectively opposite to the two motor coils one by one; a gap is reserved between the outer circumferential surface of the magnet sleeve and the inner circumferential surface of the outer stator punching iron core, and a gap is reserved between the outer circumferential surface of the magnet sleeve and the outer circumferential surface of the inner stator punching iron core; the rotor framework can do linear reciprocating motion along the axial direction of the cylinder frame;

the closed end of the cylinder of the rotor framework is connected with the rear pressure plate through a rear plate spring group, and the magnet blocking sleeve end of the magnet sleeve is connected with the front pressure plate through a front plate spring group.

Further, a central through hole is machined in the piston; the piston is sleeved and fixed at the end part of the round sleeve of the rotor framework, and the central through hole of the piston is communicated with the central hole of the round sleeve of the rotor framework to form the air suction channel.

Further, the exhaust valve assembly includes: the exhaust valve plate, the exhaust spring and the exhaust valve seat;

the exhaust valve plate is a circular plate B, and a cylindrical boss is processed at the center of the circular plate B; the exhaust valve plate is arranged at the bottom of an exhaust cavity of the cylinder, and a cylindrical boss of the exhaust valve plate faces the side where the piston is located;

an exhaust hole along the axial direction of the exhaust valve seat is processed in the exhaust valve seat; the exhaust valve seat is fixed at the top of an exhaust cavity of the cylinder;

the exhaust spring is arranged in an exhaust cavity of the cylinder, and two ends of the exhaust spring are respectively abutted against the exhaust valve plate and the exhaust valve seat;

when the pressure in the compression cavity is larger than a set value, the exhaust valve plate is in an open state, namely the exhaust valve plate moves upwards to compress the exhaust spring, so that the compression cavity is communicated with the exhaust cavity; when the pressure in the compression cavity is smaller than or equal to a set value, the exhaust valve plate is in a closed state, namely the exhaust valve plate butts against the bottom of the exhaust cavity under the action of the exhaust spring to seal the exhaust cavity, so that the compression cavity is not communicated with the exhaust cavity.

Furthermore, the outer stator punching iron core and the inner stator punching iron core are both made of silicon steel sheets or soft magnetic materials.

Furthermore, the outer circumferential surfaces of the cylinder, the two annular magnets, the magnet retaining ring and the magnet retaining sleeve of the rotor framework are wound with a plurality of layers of carbon fiber cloth pre-impregnated with epoxy resin.

Furthermore, the front plate spring group and the rear plate spring group are both of an annular structure and are composed of more than one plate spring, gaskets are installed between every two adjacent plate springs and separate the more than one plate spring, and the gaskets are distributed on the centers and the outer edges of the plate springs.

Further, the motor coil is a self-adhesive coil.

Further, the piston is made of alloy materials.

Has the advantages that: (1) the invention provides radial support for the rotor component through the radial rigidity of the front plate spring group and the rear plate spring group so as to realize the complete zero-friction clearance operation of the piston in the cylinder without using self-lubricating materials or gas bearings, and can reduce the influence of the weight of the moving component on the clearance, thereby having more reliable operation.

(2) The air suction valve plate is fixed on the end face of the piston through welding, an air suction structure is not required to be arranged on the cylinder, the clearance volume of the cylinder is reduced, and the volume efficiency is improved; compared with the traditional single-cylinder compressor, the two air suction valve plates are arranged oppositely, so that the influence of the operating condition on the vibration of the whole compressor, namely the vibration problem caused by opening or closing of one air suction valve plate, can be furthest realized.

(3) The linear motor assembly is provided with the air suction channel, and when a refrigerant flows through the air suction channel, the linear motor assembly can be cooled; compared with the traditional valveless linear compressor, the invention can cool the heating part by the cold working medium, and solves the problem that the waste heat of the traditional valveless linear compressor is difficult to dissipate.

(4) The compressor adopts the structure of two motor coils and two annular magnets, has less magnetic leakage and less ferromagnetic loss, improves the thrust of piston movement, further improves the running frequency of the compressor, and has smaller and more compact overall quality under the same refrigerating capacity.

(5) The structure of the air suction valve plate provided with the spiral line holes provides the opening rigidity of the air suction valve plate, limits the opening height of the valve plate and is beneficial to prolonging the service life of the valve plate.

Drawings

FIG. 1 is a schematic view of a first construction of a conventional compressor;

FIG. 2 is a schematic view of a second prior art compressor;

FIG. 3 is a structural component diagram of the present invention;

FIG. 4 is a structural assembly diagram of a linear motor assembly;

FIG. 5 is a structural assembly diagram of the mover member;

FIG. 6 is a schematic view of the structure and installation of the suction valve plate;

FIG. 7 is a schematic view of the structure and installation of the exhaust valve plate, exhaust spring and exhaust valve seat;

the motor comprises a motor coil 1, an outer stator punching iron core 2, a ring magnet 3, an inner stator punching iron core 4, a rear plate spring group 5, a rear pressing plate 6, a front pressing plate 7, a front plate spring group 8, a cylinder frame 9, a cylinder 10, a piston 11, an air suction valve plate 12, an air discharge valve plate 13, a rotor frame 14, an air discharge cavity 15, an air suction cavity 16, a shell 17, an air discharge spring 18 and an air discharge valve seat 19.

Detailed Description

The invention is described in detail below by way of example with reference to the accompanying drawings.

The present embodiment provides an oil-free linear compressor for a heat pump system, referring to fig. 3, including: the cylinder 10, the cylinder frame 9, the linear motor assembly, the air suction and exhaust valve assembly and the shell;

the cylinder 10 is provided with an axial through hole, a radial stepped through hole communicated with the axial through hole and a radial blind hole not communicated with the axial through hole, and two first through holes are formed in the side wall of the radial blind hole; the radial step through hole is used as an exhaust cavity 15, the radial blind hole is used as an air suction cavity 16, the air suction cavity 16 is connected with an external refrigerant storage component through a pipeline, and the exhaust cavity 15 is connected with an external refrigeration system through a pipeline;

the two cylinder frames 9 have the same structure and are both flange-shaped structures, each flange-shaped structure comprises a flange plate and a central cylinder extending out of the middle of the flange plate, and a second through hole is processed in the flange plate; the central hole of the central cylinder is a stepped hole, and the inner diameter of the large-diameter end of the central cylinder is the same as that of the axial through hole of the cylinder 10; the flange plate ends of the two cylinder frames 9 are symmetrically arranged at the two ends of the cylinder 10 through screws, namely the two cylinder frames 9 are oppositely arranged; the large-diameter end of the central hole of the cylinder frame 9 is communicated with the axial through hole of the cylinder 10 in a butt joint way, and the large-diameter end of the central hole of the cylinder frame 9 and the axial through hole of the cylinder 10 form a piston cavity; the second through hole of the cylinder frame 9 is communicated with the first through hole of the cylinder 10 in a butt joint way;

two identical linear motor assemblies are respectively and correspondingly arranged outside the central cylinders of the two cylinder frames 9 and are oppositely arranged; referring to fig. 4, each linear motor assembly includes: an outer stator component, an inner stator component and a rotor component;

the outer stator component includes: the stator comprises an outer stator punching iron core 2, two motor coils 1, a front pressing plate 7 and a rear pressing plate 6;

the outer stator punching iron core 2 is of a cylindrical structure with two open ends, two annular grooves for mounting the motor coil 1 are processed in the side wall of the outer stator punching iron core, and each annular groove is communicated with an inner hole of the outer stator punching iron core 2;

the motor coils 1 are self-adhesive coils, the two motor coils 1 are respectively arranged in an annular groove of the outer stator punching iron core 2, an insulating gasket is arranged between the motor coils 1 and the outer stator punching iron core 2, and the two motor coils 1 are connected in series and have opposite winding directions;

the front pressing plate 7 and the rear pressing plate 6 are tightly pressed and fixed at two ends of the outer stator punching iron core 2 through a long screw; the front pressure plate 7 is coaxially fixed on a flange of the cylinder frame 9 through a screw to realize the fixation of the outer stator component;

the inner stator part is an inner stator punching iron core 4, and the inner stator punching iron core 4 is of a cylindrical structure with openings at two ends; the inner stator punching iron core 4 is sleeved and fixed outside the small-diameter ends of the two cylinder frames 9 in an adhesive manner;

the outer stator punching iron core 2 and the inner stator punching iron core 4 both adopt silicon steel sheets or soft magnetic materials; when silicon steel sheets are adopted, a plurality of silicon steel sheets are laminated and combined into a group, and then the plurality of silicon steel sheets are assembled into an annular structure to form an outer stator punching iron core 2 and an inner stator punching iron core 4;

referring to fig. 5, the mover member includes: the device comprises a piston 11, a rotor framework 14, two annular magnets 3, a magnet retaining ring 3-1, a magnet retaining sleeve 3-2, a front plate spring group 8 and a rear plate spring group 5;

the rotor framework 14 is a cylinder with an opening at one end and a closed end, a coaxial circular sleeve is arranged in the center of the cylinder, and two ends of the circular sleeve extend out of the cylinder;

the two annular magnets 3 are respectively a first annular magnet and a second annular magnet; the first annular magnet, the magnet retaining ring 3-1, the second annular magnet and the magnet retaining sleeve 3-2 are sequentially and coaxially arranged at the opening end of the cylinder of the rotor framework 14, and the first annular magnet 3 is in butt joint with the opening end of the cylinder of the rotor framework 14; the outer circumferential surfaces of the cylinder of the rotor framework 14, the two annular magnets 3, the magnet retaining ring 3-1 and the magnet retaining sleeve 3-2 are wound with a plurality of layers of carbon fiber cloth pre-impregnated with epoxy resin, so that the five components are fixedly connected to form the magnet sleeve, and the magnet sleeve after being fixedly connected keeps good coaxiality;

the circular sleeve of the rotor framework 14 is coaxially arranged in the small-diameter end of the central hole of the cylinder frame 9, and the end part of the circular sleeve extends out of the small-diameter end of the central hole of the cylinder frame 9 and is positioned in the large-diameter end of the central hole of the cylinder frame 9; the magnet sleeve is sleeved between the outer stator punching iron core 2 and the inner stator punching iron core 4, and the two annular magnets 3 are respectively opposite to the two motor coils 1 one by one; a gap is reserved between the outer circumferential surface of the magnet sleeve and the inner circumferential surface of the outer stator punching iron core 2, and a gap is reserved between the outer circumferential surface of the magnet sleeve and the outer circumferential surface of the inner stator punching iron core 4 to form a motor air gap; the rotor framework 14 can do linear reciprocating motion along the axial direction of the cylinder frame 9;

the closed end of the cylinder of the rotor framework 14 is connected with the rear pressure plate 6 through an annular rear plate spring group 5, and the end 3-2 of the magnet retaining sleeve of the magnet sleeve is connected with the front pressure plate 7 through an annular front plate spring group 8; the rear plate spring group 5 and the front plate spring group 8 are used for realizing radial support of the rotor framework 14 and the magnet sleeve which are fixedly connected into a whole; the front plate spring group 8 and the rear plate spring group 5 are composed of more than one plate spring, gaskets are arranged between every two adjacent plate springs to separate the more than one plate spring, and the gaskets are distributed on the centers and the outer edges of the plate springs; an inner hole of the annular rear plate spring group 5 is sleeved on the end part, extending out of the closed end of the cylinder, of the rotor framework 14, and the outer edge of the rear plate spring group 5 is fixed on the rear pressing plate 6 through a screw; an inner hole of the annular front plate spring group 8 is sleeved on the magnet blocking sleeve 3-2, and the outer edge of the front plate spring group 8 is fixed on the front pressure plate 7 through a screw;

the piston 11 is provided with a central through hole, and the piston 11 is made of light alloy material; the piston 11 is sleeved and fixed at the end part of the round sleeve of the rotor framework 14, and a central through hole of the piston 11 is communicated with a central hole of the round sleeve of the rotor framework 14 to form an air suction channel; the outer circumferential surface of the piston 11 is in sliding clearance fit with the inner circumferential surface of a piston cavity formed by the large-diameter end of the central hole of the cylinder frame 9 and the axial through hole of the cylinder 10; the cavity between the pistons 11 of the two linear motor assemblies is used as a compression cavity which is communicated with an exhaust cavity 15;

the suction and exhaust valve assembly comprises: an air suction valve plate 12 and an exhaust valve assembly;

referring to fig. 6, the suction valve plate 12 is an elastic circular plate a, and the diameter of the circular plate a is the same as the outer diameter of the piston 11; the circular plate A is provided with three round holes uniformly distributed along the circumferential direction of the circular plate A and three spiral line holes which respectively take the three round holes as starting points; and the distance between the circle centers of the three round holes and the circle center of the circular plate A is larger than the sum of the inner diameter of the piston 11 and the radius of the round hole; the outer edges of the two suction valve plates 12 are fixed at the opposite ends of the two pistons 11 respectively through welding; when the pressure in the compression cavity is smaller than the pressure in the air suction channel, the two air suction valve plates 12 are both in an open state, namely, the two air suction valve plates 12 are both protruded outwards, so that the air suction valve plates 12 are not in contact with the end surface of the piston 11, and the compression cavity is communicated with the air suction channel through three round holes and three spiral line holes of the air suction valve plates 12; when the pressure in the compression cavity is greater than or equal to the pressure in the air suction channel, the two air suction valve plates 12 are in a closed state, namely the air suction valve plates 12 are abutted against the end surface of the piston 11, and the compression cavity is not communicated with the air suction channel because the distance between the circle centers of the three circular holes and the circle center of the circular plate A is greater than the sum of the inner diameter of the piston 11 and the radius of the circular hole;

the discharge valve assembly includes: an exhaust valve plate 13, an exhaust spring 18 and an exhaust valve seat 19;

referring to fig. 7, the exhaust valve plate 13 is a circular plate B, and a cylindrical boss is processed at the center of the circular plate B; the exhaust valve plate 13 is arranged at the bottom of an exhaust cavity 15 of the cylinder 10, and a cylindrical boss of the exhaust valve plate 13 faces to the side of the piston 11;

an exhaust hole along the axial direction of the exhaust valve seat 19 is processed in the exhaust valve seat; the exhaust valve seat 19 is fixed on the top of the exhaust cavity 15 of the cylinder 10;

the exhaust spring 18 is arranged in an exhaust cavity 15 of the cylinder 10, and two ends of the exhaust spring 18 respectively abut against the exhaust valve plate 13 and the exhaust valve seat 19;

when the pressure in the compression cavity is larger than a set value, the exhaust valve plate 13 is in an open state, namely the exhaust valve plate 13 moves upwards to compress the exhaust spring 18, so that the compression cavity is communicated with the exhaust cavity 15; when the pressure in the compression cavity is smaller than or equal to a set value, the exhaust valve plate 13 is in a closed state, namely the exhaust valve plate 13 butts against the bottom of the exhaust cavity 15 under the action of the exhaust spring 18 to seal the exhaust cavity 15, so that the compression cavity is not communicated with the exhaust cavity 15;

the shell 17 is a cylinder with an opening at one end and a closed end; two housings 17 are respectively installed at the outer portions of the two linear motor assemblies, and the open ends of the housings 17 are fixed to the outer edges of the flange of the cylinder frame 9.

The working principle is as follows: when the motor coil 1 is electrified with alternating current, the alternating current generates an excitation magnetic field, and the excitation magnetic field interacts with the magnetic field of the annular magnet 3 to enable the annular magnet 3 to generate reciprocating axial force so as to drive the piston 11 to do reciprocating linear motion;

when the two pistons 11 move towards each other, the volume of a compression cavity between the two pistons 11 is increased, the pressure is reduced, the suction valve plate 12 is in an open state, and the exhaust valve plate 13 is in a closed state; the refrigerant in the external refrigerant storage component is firstly sucked into the suction cavity 16, then enters the inner cavity of the shell 17 through two first through holes on the side wall of the suction cavity 16, and finally enters the compression cavity through the suction channel; at this time, the compressor is in the air suction process;

when the two pistons 11 move relatively, the volume of a compression cavity between the two pistons 11 is reduced, the pressure is increased, the suction valve plate 12 is in a closed state, and the exhaust valve plate 13 is in an open state; the refrigerant in the compression cavity is compressed and enters the exhaust cavity 15, and enters an external refrigerating system from the exhaust cavity 15; at this time, the compressor is in a compression discharge process.

In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An oil-free linear compressor for a heat pump system, comprising: the air cylinder comprises an air cylinder (10), an air cylinder frame (9), a linear motor assembly, an air suction valve plate (12), an exhaust valve assembly and a shell (17);

the cylinder (10) is provided with an axial through hole, a radial stepped through hole communicated with the axial through hole and a radial blind hole not communicated with the axial through hole, and two first through holes are formed in the side wall of the radial blind hole; the radial step through hole is used as an exhaust cavity (15), and the radial blind hole is used as an air suction cavity (16);

the two cylinder frames (9) have the same structure and are both flange-shaped structures, each flange-shaped structure comprises a flange plate and a central cylinder extending out of the middle part of the flange plate, and a second through hole is processed on the flange plate; the flange plate ends of the two cylinder frames (9) are symmetrically arranged at the two ends of the cylinder (10); a central hole of a central cylinder of the cylinder frame (9) is communicated with an axial through hole of the cylinder (10) in a butt joint way, and the central hole of the cylinder frame (9) and the axial through hole of the cylinder (10) form a piston cavity; the second through hole of the cylinder frame (9) is communicated with the first through hole of the cylinder (10) in a butt joint way;

two identical linear motor assemblies are respectively and correspondingly arranged outside the central cylinders of the two cylinder frames (9); each linear motor assembly includes: an outer stator component, an inner stator component and a rotor component; wherein, the external stator component is arranged outside the central cylinder of the cylinder frame (9), and the end part of the external stator component is fixed on a flange of the cylinder frame (9); the inner stator component is sleeved and fixed outside a central cylinder of the cylinder frame (9); the rotor component is arranged in an annular cavity of the inner circumferential surface of the outer stator component and the outer circumferential surface of the inner stator component, a gap is reserved between the inner circumferential surface of the rotor component and the outer circumferential surface of the inner stator component, a gap is reserved between the outer circumferential surface of the rotor component and the inner circumferential surface of the outer stator component, and two ends of the rotor component are connected with two ends of the outer stator component through a front plate spring set (8) and a rear plate spring set (5) respectively; an air suction channel penetrating through a central hole of the cylinder frame (9) is arranged in the rotor component, a piston (11) is sleeved at the tail end of the air suction channel, and the outer circumferential surface of the piston (11) is in sliding clearance fit with the inner circumferential surface of the piston cavity; a cavity between the pistons (11) of the two linear motor assemblies is used as a compression cavity, and the compression cavity is communicated with an exhaust cavity (15); the piston (11) can linearly and repeatedly move along the axial direction under the action of the outer stator component, the inner stator component and the rotor component;

the air suction valve plate (12) is an elastic circular plate A; more than two circular holes which are uniformly distributed along the circumferential direction of the circular plate A and spiral line holes which respectively take the circular holes as starting points and correspond to each other one by one are processed on the circular plate A; the distance between the circle centers of more than two round holes and the circle center of the circular plate A is larger than the sum of the inner diameter of the piston (11) and the radius of the round hole; the outer edges of the two air suction valve plates (12) are respectively fixed at the opposite ends of the two pistons (11); when the pressure in the compression cavity is smaller than the pressure in the air suction channel, the two air suction valve plates (12) are both in an open state, and the air suction valve plates (12) are not in contact with the end face of the piston (11), so that the compression cavity is communicated with the air suction channel through the round holes and the spiral line holes of the air suction valve plates (12); when the pressure in the compression cavity is larger than or equal to the pressure in the air suction channel, the two air suction valve plates (12) are both in a closed state, and the air suction valve plates (12) are abutted against the end surface of the piston (11), so that the compression cavity is not communicated with the air suction channel;

the exhaust valve assembly is arranged in an exhaust cavity (15); when the pressure in the compression cavity is greater than a set value, the exhaust valve assembly is in an open state, and the compression cavity is communicated with the exhaust cavity (15); when the pressure in the compression cavity is smaller than or equal to a set value, the exhaust valve assembly is in a closed state, and the compression cavity is not communicated with the exhaust cavity (15);

the shell (17) is a cylinder with an opening at one end and a closed end; the two shells (17) are respectively arranged outside the two linear motor assemblies, and the opening ends of the shells (17) are fixed on the outer edge of the flange of the cylinder frame (9).

2. An oil-free linear compressor for a heat pump system as claimed in claim 1, wherein the outer stator part comprises: the stator punching sheet comprises an outer stator punching sheet iron core (2), two motor coils (1), a front pressing plate (7) and a rear pressing plate (6);

the outer stator punching iron core (2) is of a cylindrical structure with openings at two ends, two annular grooves for mounting the motor coil (1) are processed in the side wall of the outer stator punching iron core, and each annular groove is communicated with an inner hole of the outer stator punching iron core (2);

the two motor coils (1) are respectively arranged in an annular groove of the outer stator punching iron core (2), an insulating gasket is arranged between the motor coils (1) and the outer stator punching iron core (2), and the two motor coils (1) are connected in series and have opposite winding directions;

the front pressing plate (7) and the rear pressing plate (6) are respectively fixed at two ends of the outer stator punching iron core (2); the front pressure plate (7) is fixed on a flange of the cylinder frame (9);

the inner stator part is an inner stator punching iron core (4), and the inner stator punching iron core (4) is of a cylindrical structure with openings at two ends; the inner stator punching iron core (4) is sleeved and fixed outside the small-diameter ends of the two cylinder frames (9);

the mover member includes: the rotor comprises a rotor framework (14), two annular magnets (3), a magnet retaining ring (3-1) and a magnet retaining sleeve (3-2);

the rotor framework (14) is a cylinder with one end open and one end closed, a coaxial circular sleeve is arranged in the center of the cylinder, and two ends of the circular sleeve extend out of the cylinder;

the two annular magnets (3) are respectively a first annular magnet and a second annular magnet; the first annular magnet, the magnet retaining ring (3-1), the second annular magnet and the magnet retaining sleeve (3-2) are sequentially and coaxially arranged at the opening end of the cylinder of the rotor framework (14), and the first annular magnet (3) is in butt joint with the opening end of the cylinder of the rotor framework (14); and the cylinder of the rotor framework (14), the two annular magnets (3), the magnet retaining ring (3-1) and the magnet retaining sleeve (3-2) form a magnet sleeve;

the round sleeve of the rotor framework (14) is coaxially arranged in the central hole of the cylinder frame (9); the magnet sleeve is sleeved between the outer stator punching iron core (2) and the inner stator punching iron core (4), and the two annular magnets (3) are respectively opposite to the two motor coils (1) one by one; a gap is reserved between the outer circumferential surface of the magnet sleeve and the inner circumferential surface of the outer stator punching iron core (2), and a gap is reserved between the outer circumferential surface of the magnet sleeve and the outer circumferential surface of the inner stator punching iron core (4); the rotor framework (14) can do linear reciprocating motion along the axial direction of the cylinder frame (9);

the closed end of a cylinder of the rotor framework (14) is connected with the rear pressure plate (6) through the rear plate spring group (5), and the end of a magnet blocking sleeve (3-2) of the magnet sleeve is connected with the front pressure plate (7) through the front plate spring group (8).

3. An oil-free linear compressor for a heat pump system as claimed in claim 2, wherein the piston (11) is formed with a central through hole; the piston (11) is sleeved and fixed at the end part of the round sleeve of the rotor framework (14), and the central through hole of the piston (11) is communicated with the central hole of the round sleeve of the rotor framework (14) to form the air suction channel.

4. An oil-free linear compressor for a heat pump system as claimed in claim 1, wherein the discharge valve assembly comprises: an exhaust valve plate (13), an exhaust spring (18) and an exhaust valve seat (19);

the exhaust valve plate (13) is a circular plate B, and a cylindrical boss is machined in the center of the circular plate B; the exhaust valve plate (13) is arranged at the bottom of an exhaust cavity (15) of the cylinder (10), and a cylindrical boss of the exhaust valve plate (13) faces the side of the piston (11);

an exhaust hole along the axial direction of the exhaust valve seat (19) is processed in the exhaust valve seat; the exhaust valve seat (19) is fixed at the top of an exhaust cavity (15) of the cylinder (10);

the exhaust spring (18) is arranged in an exhaust cavity (15) of the cylinder (10), and two ends of the exhaust spring (18) respectively abut against an exhaust valve plate (13) and an exhaust valve seat (19);

when the pressure in the compression cavity is larger than a set value, the exhaust valve plate (13) is in an open state, namely the exhaust valve plate (13) moves upwards to compress the exhaust spring (18), so that the compression cavity is communicated with the exhaust cavity (15); when the pressure in the compression cavity is smaller than or equal to a set value, the exhaust valve plate (13) is in a closed state, namely the exhaust valve plate (13) butts against the bottom of the exhaust cavity (15) under the action of the exhaust spring (18) to seal the exhaust cavity (15), so that the compression cavity is not communicated with the exhaust cavity (15).

5. An oil-free linear compressor for a heat pump system as claimed in claim 2, wherein the outer stator punching iron core (2) and the inner stator punching iron core (4) both adopt silicon steel sheets or soft magnetic materials.

6. An oil-free linear compressor for a heat pump system as claimed in claim 2, wherein the cylinder of the mover frame (14), the two ring magnets (3), the magnet retainer ring (3-1) and the magnet retainer sleeve (3-2) are wound with a plurality of layers of carbon fiber cloth pre-impregnated with epoxy resin on the outer circumferential surfaces thereof.

7. An oil-free linear compressor for a heat pump system as claimed in claim 1, wherein the front plate spring group (8) and the rear plate spring group (5) are of an annular structure and each of the front plate spring group and the rear plate spring group is composed of more than one plate spring, and a spacer is installed between two adjacent plate springs to separate the more than one plate springs, and the spacers are distributed on the centers and the outer edges of the plate springs.

8. An oil-free linear compressor for a heat pump system as claimed in claim 2, wherein the motor coil (1) is a self-adhesive coil.

9. An oil-free linear compressor for a heat pump system as claimed in claim 1, wherein the piston (11) is made of an alloy material.