CN108592481B - Multi-temperature-zone refrigerator adopting pulse tube type free piston Stirling refrigerator - Google Patents

Abstract

The multi-temperature zone refrigerator using a pulse-tube free-piston Stirling refrigerator according to the present invention includes a refrigerator box body and a refrigeration system. The refrigerator box body includes a refrigerating room, a freezing room and a changing room, and the refrigerating room is located in the upper half of the refrigerator box body. part, the freezer compartment and the changing room are located in the lower part of the refrigerator; the refrigeration system consists of a compression throttling refrigeration system, a Stirling refrigerator-heat pipe system, and the Stirling refrigerator-heat pipe system includes a pulse tube type free piston Stirling refrigeration Machine, cold-end gravity heat pipe, hot-end gravity heat pipe, cold-conducting copper jacket and heat-conducting copper jacket; It is arranged on the rear wall and left and right walls of the greenhouse. The condensation section of the gravity heat pipe at the cold end is connected to the cold head of the pulse-tube free-piston Stirling refrigerator through the cooling copper jacket, and the evaporation section of the gravity heat pipe at the hot end is connected with the heat-conducting copper jacket. The sleeve is connected to the hot end of the pulse tube type free piston Stirling refrigerator.

Description

Multi-temperature zone refrigerator with pulse-tube free-piston Stirling refrigerator

technical field

The invention belongs to the field of household appliances, and in particular relates to a multi-temperature zone refrigerator adopting a pulse tube type free-piston Stirling refrigerator.

Background technique

With the improvement of people's living standards, the freezing function of ordinary refrigerators (temperature higher than -18°C) is gradually unable to meet people's freezing requirements for some foods. For example, some seafood needs to be better stored below -40°C. Taking meat food as an example, when stored in an ordinary refrigerator, it cannot be refrigerated for more than 2 days at 7°C, 5 days at 0°C, and 1 month when frozen at -18°C. For foods that need to be stored for a long time, the lower the freezing temperature, the more inhibited the growth and reproduction of microorganisms and the activity of enzymes, the less nutrient loss, and the better the preservation of freshness.

Traditional household refrigerator refrigeration generally adopts a single-stage vapor compression throttling refrigeration system, which consists of four basic parts: compressor, condenser, throttling component and evaporator, and each part is connected by pipes to form a closed system. The system is filled with a certain amount of refrigerant, and the refrigerant is cooled in the system through four cycles of compression, condensation, throttling, and evaporation. The refrigerator using vapor compression refrigeration has fast cooling speed, good cooling effect and mature technology, so it has stable performance and long service life. When a refrigerator using vapor compression refrigeration works, the compressor starts and stops intermittently under the control of the thermostat. When the temperature in the refrigerator is higher than the set temperature, the compressor starts to cool, and the temperature in the cabinet decreases until the temperature in the refrigerator reaches a certain critical value below the set temperature, the compressor stops working, and the temperature in the refrigerator begins to rise. When the temperature rises to another critical value higher than the set temperature, the compressor starts to work again. The above process is repeated and repeated. Therefore, even if the refrigerator is in a stable state, the temperature in the box also fluctuates periodically, which is not good for the preservation of some advanced foods like seafood. Moreover, the single-stage vapor compression throttling refrigeration system is also difficult to achieve a refrigeration temperature below -40°C, which cannot meet the temperature requirements for some food preservation.

A heat pipe is a heat transfer element with extremely high thermal conductivity. It transfers heat through the evaporation and condensation of liquid in a fully enclosed vacuum tube, and has high thermal conductivity. Gravity heat pipes can only conduct heat in one direction, and the condensation section must be higher than the evaporation section. When working, the working liquid inside the gravity heat pipe absorbs heat and vaporizes into steam in the evaporation section, and the steam rises to the cooling section to release heat and re-condenses into liquid, and then returns to the evaporation section by gravity. The heat pipe used in the present invention is a two-phase closed thermosiphon (gravity heat pipe).

Stirling refrigeration cycle consists of two isothermal processes and isovolumetric processes, and its theoretical cycle efficiency is Carnot efficiency. Relatively speaking, using Stirling refrigeration technology has higher refrigeration efficiency under low temperature refrigeration conditions. The Stirling refrigerator adopts a closed cycle of gas expansion refrigeration, which is formed by the valveless connection between the compression unit and the expansion unit. The use of helium as the refrigerant will not damage the ozone layer and is an extremely environmentally friendly refrigeration technology. Free-piston Stirling refrigerator has no complicated piping system, compressor and expander are integrated together, with few moving parts, no oil lubrication, not easy to wear, high reliability, long life, compact structure, light weight, refrigeration efficiency It has the advantages of high temperature control, high temperature control accuracy, high efficiency under full load and partial load, and the cooling capacity and cooling temperature can be controlled by adjusting the input voltage.

The invention patent of application number 2016105783878 uses a Stirling refrigerator to realize the functions of high temperature control accuracy, good environmental adaptability, and small humidity and temperature fluctuations in the wine cabinet. The expansion piston still has defects such as pumping loss, shuttle loss and axial heat conduction loss caused by high-frequency motion of the cold and hot ends.

SUMMARY OF THE INVENTION

One of the objectives of the present invention is to provide a multi-temperature zone refrigerator using a novel high-efficiency pulse-tube free-piston Stirling refrigerator. The coaxial pulse-tube free-piston Stirling refrigerator of the present invention cancels the traditional free-piston refrigerator. The long low-temperature expansion piston of the Stirling refrigerator is replaced by a work-recovery expansion piston that operates in a shorter room temperature region. The expansion cylinder of the free-piston Stirling refrigerator becomes the pulse tube of the pulse tube cold finger. The cold end of the pulse tube is arranged with a laminar flow guide, and the hot end is provided with a secondary heat exchanger at the hot end. This change combines the advantages of a free-piston Stirling refrigerator and a pulse-tube refrigerator. By eliminating the high-frequency motion of the expansion piston at the cold and hot ends, the pumping loss, shuttle loss and axial loss caused by the low-temperature expansion piston are eliminated. Thermal loss. The problem of sound power recovery of the pulse tube refrigerator is solved by setting a short room temperature expansion piston at the hot end. Therefore, when the sound power at the cold end is completely recovered, the theoretical efficiency of the new pulse tube free-piston Stirling refrigerator is Carnot. cycle efficiency. At the same time, the cancellation of the low-temperature expansion piston reduces the difficulty of manufacturing the refrigerator and reduces the quality of the whole machine.

The present invention provides a multi-temperature zone refrigerator using a pulse tube type free-piston Stirling refrigerator, which has such features, and includes a refrigerator box and a refrigeration system.

The refrigerator box includes a refrigerator compartment, a freezer compartment and a variable room. The refrigerator compartment is located in the upper half of the refrigerator box, and the freezer compartment and the variable room are located in the lower half of the refrigerator. The refrigeration system consists of a compression throttling refrigeration system and a free-piston Stirling refrigerator. - Composition of heat pipe system, free piston Stirling refrigerator - Heat pipe system includes pulse tube type free piston Stirling refrigerator, cold end gravity heat pipe, hot end gravity heat pipe, cold-conducting copper sleeve and heat-conducting copper sleeve, hot end gravity heat pipe The condensation section pipes of the cold end are arranged upward on the inside of the left wall of the refrigerator shell, the evaporation section pipes of the cold end gravity heat pipe are arranged downward on the rear wall and left and right walls of the greenhouse, and the condensation section of the cold end gravity heat pipe passes through the cooling copper jacket and pulse. The cold head of the tube-type free-piston Stirling refrigerator is connected, and the evaporation section of the hot-end gravity heat pipe is connected to the hot end of the pulse-tube-type free-piston Stirling refrigerator through a heat-conducting copper sleeve. The refrigerator includes a linear motor, a compression unit, an expander unit, and a frame, wherein the frame includes a flange, a piston tube arranged in the flange, and a base, the flange is in the shape of a disc, and one side of the flange is also provided There are concentric small discs, the base is cylindrical, one end is connected to the other side of the flange, the other end is a free end, the center line of the base coincides with the center line of the flange, the piston tube is a straight pipe, and one end is open at the small end. On the outer side of the disc, the opening at the other end is located in the base, and the piston tube has a cylindrical piston cavity for accommodating the compression piston and expansion piston of the refrigerator. The motor includes an outer yoke, an inner yoke and a mover. The outer yoke and the inner yoke are respectively arranged on the frame and there is a gap between the outer yoke and the inner yoke. The mover is arranged in the gap, and the compression unit has a compression unit. Piston and compression piston spring, the compression piston spring is fixedly connected with the frame through the connecting piece, the compression piston is arranged in the piston tube, one end is connected with the mover and is connected with the compression piston spring, and the other end is the free end, the expander unit includes the expansion piston , expansion piston spring, expansion piston rod, primary hot end heat exchanger, secondary hot end heat exchanger, regenerator, pulse tube, cold end heat exchanger, the primary hot end heat exchanger is cylindrical, It is sleeved on the outer wall of the piston tube and arranged on the end face of the small disc. One end of the pulse tube is connected to one end of the outer side of the piston tube, and the other end is connected to the cold end heat exchanger. The regenerator is cylindrical and is arranged on the pulse tube One end is connected to the cold end heat exchanger, the other end is connected to the primary hot end heat exchanger, the secondary hot end heat exchanger is arranged in the pulse tube, the expansion piston is in the piston tube, and the expansion piston spring is connected to the The frame is fixedly connected, one end of the expansion piston rod is connected with the expansion piston, and the other end is connected with the expansion piston spring after passing through the compression piston and the compression piston spring. The compression piston, the expansion piston and the piston cavity constitute the compression cavity. The end heat exchanger and the piston cavity constitute the expansion cavity.

In the multi-temperature zone refrigerator using the pulse tube type free-piston Stirling refrigerator provided by the present invention, it can also have the following characteristics: wherein, the cooling copper sleeve is a circular copper sleeve, and one end is open with a pulse tube type. The cold head of the free-piston Stirling refrigerator is connected. The inner side of the circular copper sleeve and the cold head of the pulse tube-type free-piston Stirling refrigerator are coated with thermally conductive silicone grease. The circular copper sleeve is provided with a circular concave. The grooves make the heat transfer working medium flow in the annular grooves for sufficient heat exchange; the side surface of the circular copper sleeve is provided with two cooling-conducting small holes that communicate with the annular grooves.

In addition, in the multi-temperature zone refrigerator using the pulse tube type free-piston Stirling refrigerator provided by the present invention, it may also have the following characteristics: wherein, the heat-conducting copper sleeve is an annular copper sleeve, and the inner surface of the annular copper sleeve is connected to the pulse tube. The hot end of the free-piston Stirling refrigerator is coated with thermal conductive silicone grease, and the annular copper sleeve is provided with an annular groove, so that the heat transfer medium can flow in the annular groove to fully exchange heat; A small heat conduction hole communicated with the annular groove.

In addition, in the multi-temperature zone refrigerator using the pulse tube type free-piston Stirling refrigerator provided by the present invention, it can also have the following characteristics: wherein the cooling temperature range of the variable room is -60-10°C, and the variable room is made of The pulse tube type free piston Stirling refrigerator provides cooling capacity; the pulse tube type free piston Stirling refrigerator is an integral free piston Stirling refrigerator driven by a linear motor, and the pulse tube type free piston Stirling refrigerator is installed In the left middle part of the refrigerator, a shock absorbing block is fixed at the tail of the pulse tube type free-piston Stirling refrigerator, and the shock absorbing block faces the back plate of the refrigerator box.

In addition, in the multi-temperature zone refrigerator using a pulse-tube free-piston Stirling refrigerator provided by the present invention, it may also have the following feature: wherein the cold-end gravity heat pipe includes a first cold-end heat pipe and a second cold-end heat pipe , the first cold-end heat pipe and the second cold-end heat pipe are respectively connected with the first and second cold-conducting holes on the side of the cooling-conducting copper sleeve, the cold-end gravity heat pipe pipeline is inclined downward at an angle of 15°, and the working medium used inside is R170; The end gravity heat pipe includes a first hot end heat pipe and a second hot end heat pipe. The first hot end heat pipe and the second hot end heat pipe are respectively connected with the first and second heat conducting holes on the side of the heat conducting copper sleeve, and the hot end gravity heat pipe pipeline is downward. Tilt 10°.

In addition, in the multi-temperature zone refrigerator using the pulse tube type free-piston Stirling refrigerator provided by the present invention, it is characterized in that it further comprises a flow guide arranged at one end of the pulse tube and located in the pulse tube.

In addition, the multi-temperature zone refrigerator using the pulse tube type free-piston Stirling refrigerator provided by the present invention may also have the following feature: wherein the cold end heat exchanger and the regenerator are further provided with a first filter The first filter layer is cylindrical and made of stainless steel wire mesh.

In addition, the multi-temperature zone refrigerator using the pulse tube type free-piston Stirling refrigerator provided by the present invention may also have the following feature: wherein the regenerator is cylindrical and made of polyester film.

The role and effect of the invention

Compared with the existing refrigerator, the beneficial effects of the present invention are:

(1) Due to the use of a free-piston Stirling refrigerator, the minimum refrigeration temperature of the refrigerator can reach -60 °C, and the stroke of the compression piston can be adjusted by changing the driving voltage, thereby controlling the refrigeration capacity and refrigeration temperature. Food can be classified and preserved according to the requirements of different freezing temperatures.

(2) Due to the combination of free piston Stirling and gravity heat pipe, the problem of free piston Stirling cooling and heat dissipation is effectively solved, and it is closely combined with the refrigerator box, which increases the efficiency of heat transfer, and the installation is simple and does not Occupies the internal volume of the box.

(3) The coaxial pulse tube free-piston Stirling refrigerator of the present invention cancels the long low-temperature expansion piston of the traditional free-piston Stirling refrigerator, and replaces it with a work-recovery expansion piston operating in a shorter room temperature region. The expansion cylinder of the free-piston Stirling refrigerator becomes the pulse tube of the pulse tube cold finger. The cold end of the pulse tube is arranged with a laminar flow guide, and the hot end is provided with a secondary heat exchanger at the hot end. This change combines the advantages of a free-piston Stirling refrigerator and a pulse-tube refrigerator. By eliminating the high-frequency motion of the expansion piston at the cold and hot ends, the pumping loss, shuttle loss and axial loss caused by the low-temperature expansion piston are eliminated. Thermal loss. The problem of sound power recovery of the pulse tube refrigerator is solved by setting a short room temperature expansion piston at the hot end. Therefore, when the sound power at the cold end is completely recovered, the theoretical efficiency of the new pulse tube free-piston Stirling refrigerator is Carnot. cycle efficiency. At the same time, the cancellation of the low-temperature expansion piston reduces the difficulty of manufacturing the refrigerator and reduces the quality of the whole machine.

Description of drawings

FIG. 1 is an external schematic diagram of the pulse tube type free-piston Stirling refrigerator used in the present invention.

Fig. 2 is a schematic diagram of the cold-conducting copper jacket at the cold end of the pulse tube type free-piston Stirling refrigerator used in the present invention.

Fig. 3 is a schematic diagram of the heat-conducting copper sleeve at the hot end of the pulse tube type free-piston Stirling refrigerator used in the present invention.

4 is a schematic diagram of the combined assembly of the pulse tube type free-piston Stirling refrigerator, the cooling-conducting copper sleeve, and the heat-conducting copper sleeve used in the present invention.

5 is a schematic diagram of the combined assembly of the pulse tube type free-piston Stirling refrigerator and the gravity heat pipe system of the present invention.

6 is a schematic diagram of the combined assembly of the compression and throttling refrigeration system, the pulse tube type free piston Stirling refrigerator and the gravity heat pipe system of the present invention.

FIG. 7 is a front view of the combination of the refrigeration system and the refrigerator box of the present invention.

8 is a rear view of the combination of the refrigeration system and the refrigerator box of the present invention.

FIG. 9 is a schematic diagram of the appearance of the refrigerator of the present invention.

10 is a schematic diagram of the working principle of the multi-temperature zone refrigerator of the present invention.

11 is a schematic cross-sectional view of a pulse-tube free-piston Stirling refrigerator in an embodiment of the present invention.

FIG. 12 is a perspective view of a rack in an embodiment of the present invention.

Fig. 13 is a view from the direction A in Fig. 12 .

FIG. 14 is a C-C cross-sectional view of FIG. 13 .

Detailed ways

In order to make the technical means, creative features, goals and effects achieved by the present invention easy to understand, the following embodiments describe the multi-temperature zone refrigerator using the pulse tube type free-piston Stirling refrigerator of the present invention in detail with reference to the accompanying drawings.

Example

As shown in FIG. 1 to FIG. 9 , a multi-temperature zone refrigerator combined with a Stirling refrigerator and compression and throttling refrigeration includes a refrigerator box 700 and a refrigeration system. The refrigerator box 700 includes a refrigerator casing 706 , a display screen 707 , a refrigerator door 708 , and a heat insulating layer 705 . The interior space of the box has a refrigerating chamber 701 on the upper half of the refrigerator, a freezing chamber 703 on the right side of the lower half of the refrigerator, and a changing room 702 on the left side of the lower half of the refrigerator. The display screen 707 is connected to the controller 800, which can not only display the temperature of each refrigerating room, but also control the operating frequency of the inverter compressor 608 and the input voltage of the free-piston Stirling refrigerator 100, which can effectively control the refrigerating temperature of each room.

The refrigeration system includes a compression throttling refrigeration system 600 and a free-piston Stirling refrigerator-heat pipe system 500 . The compression and throttling refrigeration system 600 includes: an inverter compressor 608 , a condenser 604 , a drying filter 601 , a capillary tube 607 , a freezing chamber liquid collector 606 , a freezing chamber evaporator 605 , a refrigerating chamber liquid collector 603 , and a refrigerating chamber evaporator 602 . The inverter compressor 608 is located at the bottom of the refrigerator, and there are ventilation holes at the position of the inverter compressor on the rear side of the refrigerator, which is convenient for discharging the heat generated by the compressor to the environment; the condenser 604 is located on the right side of the refrigerator and is installed inside the refrigerator shell 706, which can dissipate the heat Passed to the environment through the shell; the drying filter 601 is located at the end of the evaporator 604, connecting the evaporator 604 and the capillary 607; the other end of the capillary 607 is connected to the freezer evaporator 605, and the freezer evaporator 605 is located on the right side of the lower half of the refrigerator The evaporator 605 in the freezer is connected to the evaporator 602 in the refrigerating chamber, and the evaporator 602 in the refrigerating chamber is arranged in the upper part of the refrigerator to provide cooling capacity for the refrigerating chamber 701; the refrigerating chamber collects liquid The collector 603 and the freezer compartment liquid collector 606 are located at the inlet ends of the refrigerator compartment evaporator 602 and the freezer compartment evaporator 605, respectively.

As shown in FIGS. 4 and 5 , the free-piston Stirling refrigerator-heat pipe system 500 is composed of a free-piston Stirling refrigerator system 400 and a heat pipe system. The free-piston Stirling refrigerator system 400 includes a pulse tube-type free-piston heat pipe system. Turling refrigerator 100, cooling copper jacket 200, heat conducting copper jacket 300. The heat pipe system includes a cold end gravity heat pipe and a hot end gravity heat pipe, wherein the cold end gravity heat pipe is composed of a first cold end heat pipe 503 and a second cold end heat pipe 504, and the hot end gravity heat pipe is composed of a first hot end heat pipe 501 and a second heat pipe. The end heat pipe 502 is formed. In order to make it work normally, the pipelines of the first cold-end heat pipe 503 and the second cold-end heat pipe 504 that conduct cooling are inclined downward at an angle of 15°, and the pipelines of the first and second hot-end heat pipes 501 and 502 that conduct heat are downward. Inclined at 10° angle. The pulse tube type free-piston Stirling refrigerator 100 is installed in the left part of the middle of the refrigerator, which can conveniently connect the first hot end heat pipe 501 and the second hot end heat pipe 502 and the first cold end heat pipe 503 and the second cold end heat pipe 504 . The bolts 102 can fix the shock-absorbing block 101 of the refrigerator on the tail of the pulse-tube free-piston Stirling refrigerator 100 .

The working medium used in the first hot-end heat pipe 501 and the second hot-end heat pipe 502 is R600a, which is arranged on the upper half of the left side of the refrigerator, inside the refrigerator shell 706, and the lower end is respectively connected with the first and second heat conducting copper sleeves 300. The small holes 301 and 302 are connected to dissipate heat for the hot end 103 of the free-piston Stirling refrigerator 100; the working medium used in the first cold end heat pipe 503 and the second cold end heat pipe 504 is R170, which is folded and arranged in the changing room The inner side and upper end of 702 are respectively connected with the first and second cooling holes 202 and 203 on the cooling copper jacket, so as to transfer the cooling energy generated by the cold head 104 of the free piston Stirling refrigerator 100 into the variable temperature chamber 702 . Both the cooling-conducting copper sleeve 200 and the heat-conducting copper sleeve 300 have grooves inside, so that the working fluid changes heat in the mobile phase.

As shown in FIG. 2 , the cooling-conducting copper sleeve 200 is a circular copper sleeve, one end of which is opened to connect with the cold head 104 of the free-piston Stirling refrigerator 100 , and the inner side of the circular copper sleeve is connected to the cold head 104 of the free-piston Stirling refrigerator 100 . Thermal grease is coated between the cold heads 104, and a circular groove 201 is arranged in the circular copper sleeve, so that the heat transfer working medium R170 flows in the circular groove 201 to fully exchange heat; the side of the circular copper sleeve is provided with Two first and second cooling holes 202 and 203 communicate with the annular groove 201 .

As shown in FIG. 3 , the thermally conductive copper sleeve 300 is an annular copper sleeve, the inner surface of the annular copper sleeve and the hot end 103 of the free-piston Stirling refrigerator 100 are coated with thermally conductive silicone grease, and an annular groove is provided inside the annular copper sleeve Step 303 , make the heat transfer working medium R600a flow in the annular groove 303 for sufficient heat exchange; two first and second heat conduction holes 301 and 302 communicating with the annular groove 303 are opened on the side of the annular copper sleeve.

As shown in FIG. 10 , in the compression and throttling refrigeration system 600 , the working fluid is compressed by the inverter compressor 608 and becomes a high-temperature and high-pressure gas, which flows into the condenser 604 from the outlet of the compressor 608 , and is condensed and released in the condenser 604 to become a gas with high temperature and high pressure. The low-temperature and high-pressure liquid, after being throttled by the capillary 607, becomes a low-temperature and low-pressure liquid, enters the freezer chamber evaporator 605 to evaporate and absorb heat, and then continues to enter the freezer chamber evaporator 602 to absorb heat to provide cooling capacity for the freezer chamber 703 and the freezer chamber 701. After the evaporation process, the working fluid becomes a low temperature and low pressure gas, which flows into the variable frequency compressor 608 to complete the compression and throttling cycle process. The cold end of the free-piston Stirling refrigerator is connected to the first cold end heat pipe 503 and the second cold end heat pipe 504, and its working fluid is R170, which becomes liquid after condensing in the cooling copper jacket 200, and descends under the action of gravity. Flow, the evaporation section in the variable temperature chamber 702 evaporates and absorbs heat into a gaseous state, and then flows upwards back into the cooling copper jacket 200 to complete the cycle process. The free piston Stirling hot end is connected to the first hot end heat pipe 501 and the second hot end heat pipe 502. The working fluid is R600a, which evaporates into a gas in the thermal conductive copper jacket 300 and flows upward, and turns into a liquid state after condensing and releasing heat in the condensing section , and flow back to the thermal conductive copper sleeve 300 under the action of gravity. The display screen 707 is connected to the controller 800, which can not only display the temperature in each refrigeration room, but also control the operating frequency of the inverter compressor 608 and the input voltage of the free-piston Stirling refrigerator 100, so as to precisely control the refrigeration temperature in each room.

As shown in FIG. 11 , the coaxial pulse tube type free-piston Stirling refrigerator 100 includes a linear motor 1 , a compression unit, an expander unit, a frame 50 , and a casing 60 .

As shown in FIGS. 12 , 13 and 14 , the frame 50 includes a flange 52 , a piston tube 51 disposed in the flange 52 , and a base 53 .

Wherein, the flange 52 is in the shape of a disc, and one side of the flange is further provided with a small concentric disc 521 , and a plurality of connecting through holes are evenly provided on the flange 52 .

The base 53 is cylindrical, one end is connected with one side of the flange 52, the other end is a free end, the center line of the base 53 coincides with the center line of the flange 52, and the free end of the base 53 is provided with a plurality of connection screw holes, In the embodiment, the base 53 is four legs arranged around the centerline of the flange 52 .

The piston tube 51 is a straight tube, which is arranged in the flange 52 and is coaxial with the flange 52. The outer end opening is located outside the small disc 521, and the inner end opening is located in the base 53. The piston tube 51 has a cylindrical piston cavity. , the piston cavity is provided with a plurality of through holes 511 perpendicular to the axis of the piston tube and penetrating the wall of the piston tube.

The linear motor 1 includes an outer yoke 11, an inner yoke 14 and a mover. The outer yoke 11 and the inner yoke 14 are respectively arranged on the frame and there is a gap between the outer yoke and the inner yoke, and the mover is arranged in the gap. Among them, the mover includes a permanent magnet 13 and a permanent magnet support 15 .

As shown in FIG. 11 , the linear motor 1 mainly includes an outer yoke 11, a coil 12, a permanent magnet 13, an inner yoke 14, a permanent magnet support 15, and the mover includes a permanent magnet 13, a permanent magnet support 15, a connector 16, a fixed The nut 18, the compression piston 19 and the compression piston plate spring 17 (only 1/3 of the mass of the plate spring is taken when calculating the mass of the mover), the permanent magnet bracket 15 is connected with the permanent magnet 13, and passes through the compression piston 19 and the connecting piece 16 Threaded connection. The outer yoke 11 and the inner yoke 14 are soft magnetic materials, which are commonly made of materials such as electric power pure iron and silicon steel sheets. The permanent magnet 13 is a permanent magnet material, which is commonly made of RuFeB and AlNiCo permanent magnet materials. The outer yoke 11 , the coil 12 , the permanent magnet 13 and the inner yoke 14 are all annular, and are arranged coaxially. The outer yoke 11 and the inner yoke 14 are respectively arranged on the frame 50 with a gap between the outer yoke and the inner yoke, and the mover is arranged in the gap.

When the coil is fed with direct current, the outer yoke 11 and the inner yoke 14 will form a magnetic loop, thereby generating magnetic poles on the outer yoke 11 and the inner yoke 14 . When the alternating current is passed through the coil, the permanent magnet 13 will be subjected to the alternating electromagnetic force to make a reciprocating linear motion. When the permanent magnet 13 performs the reciprocating linear motion, it will drive the compression piston 19 to perform the reciprocating linear motion, and the compression piston plate spring 17 provides axial reciprocating elastic force and radial support.

The compression unit includes a connecting piece 16 , a compression piston plate spring 17 , a fixing nut 18 , and a compression piston 19 . The compression piston plate spring 17 is connected with the connecting piece 16 through the fixing nut 18, the compression piston plate spring 17 is fixedly connected with the frame 50 through the connecting piece, the compression piston 19 is arranged in the piston cavity, and one end is connected with the mover and with the compression piston spring 17 is connected, and the other end is the free end.

The expander unit includes an expansion piston 21, an expansion piston plate spring 22, a piston rod 23, a primary hot end heat exchanger 26, a secondary hot end heat exchanger 33, a regenerator 25, a pulse tube 31, and a cold end heat exchanger 24, cold finger shell 35.

The first-stage hot-end heat exchanger 26 is cylindrical, and is sleeved on the outer wall of the piston tube 51 and arranged on the end face of the small disc 521. The first-stage hot-end heat exchanger 26 and the frame 50 are of a separate structure. The stage hot end heat exchanger 26 is an interference fit with the outer wall of the piston tube 51 .

One end of the pulse tube 31 is connected to one end outside the piston tube 51 , and the other end is connected to the cold end heat exchanger 24 .

The regenerator 25 is in the shape of a cylinder with an annular cross-section, and is disposed outside the pulse tube 31 . The regenerator 25 is made of any one of polyester film, nylon and polytetrafluoroethylene materials. In the embodiment, the regenerator 25 is made of polyester film, and the thickness of the polyester film is 20- 50μm.

The secondary hot end heat exchanger 33 is arranged in the pulse tube 31, at the connection between the pulse tube 31 and the piston tube 51, the secondary hot end heat exchanger 33 and the frame 50 are separated structures, and the secondary hot end heat exchange The valve 33 is in an interference fit with the inner wall of the piston tube 51 .

The expansion piston 21 is arranged in the piston tube 51, the expansion piston plate spring 22 is fixedly connected with the frame 50 through the connecting piece, one end of the piston rod 23 is connected with the expansion piston 21, and the other end passes through the compression piston 19 and the compression piston plate spring 17. Connected to the expansion piston plate spring 22 .

The compression piston 19, the expansion piston 21 and the piston cavity constitute the compression cavity, the compression piston 19, the secondary hot end heat exchanger 33 and the piston cavity constitute the expansion cavity, and the expansion cavity and the compression cavity are arranged coaxially.

The cold finger shell 35 is arranged outside the primary hot end heat exchanger 26 , the regenerator 25 and the cold end heat exchanger 24 , the outer shell 60 is arranged outside the frame 50 and the expander unit 30 , the outer shell 60 , the cold finger shell 35 and the frame 50 are connected into one body by connecting pieces.

The radiator 27 is located outside the primary hot end heat exchanger 26 and is arranged on the cold finger shell 35. The primary hot end heat exchanger 26 transfers heat to the outer radiator 27 through the cold finger shell 35, and finally releases it to the environment .

The non-damping dynamic vibration absorbing unit 4 is connected to the casing 60 and is disposed outside the casing 60 for shock absorption of the refrigerator.

The movement process of the expansion piston and the compression piston and the gas flow process:

The expansion piston plate spring 22 is fixed with the piston rod 23 , and the expansion piston 21 is connected with the piston rod 23 .

The expansion piston 21 is purely pneumatically driven, and uses the displacement phase difference between the expansion piston 21 and the compression piston 19 to generate a refrigeration effect. Since the linear motor is excited by sinusoidal alternating current, the movement of the expansion piston 21 and the compression piston 19 is also a continuous sinusoidal movement. However, in order to explain its working principle, it is assumed that the expansion piston 21 and the compression piston 19 do intermittent jumping movements according to the cycle law. .

Sonic compression process: the expansion piston 21 stays at the top dead center, and the compression piston 19 moves upward from the bottom dead center. At this time, the acoustic waves in the main compression chamber 29 are compressed and flow into the primary hot end heat exchanger 26 outside the cylinder. , the heat generated during the compression process is released to the first-stage hot-end heat exchanger 26, and the first-stage hot-end heat exchanger 26 transfers the heat to the outer radiator 27 through the outer casing, and finally releases it to the environment. Ideally, it is considered that the cylinder and the outer casing are completely thermally conductive, and at the same time, the heat exchange area between the primary hot end heat exchanger 26 and the radiator 27 is infinite, so the temperature of the working fluid remains unchanged. However, in the actual process, isothermal compression is impossible, and the expansion piston 21 cannot move intermittently. When the compression piston 19 moves upward, the expansion piston 21 has already started to move downward.

The heat release process of the regenerator: the compression piston 19 does not move after moving to the top dead center, and the expansion piston 21 moves downward. At this time, the sound wave passes through the regenerator 25 and fully contacts the filler in the regenerator 25 for heat exchange, releasing the heat. into the regenerator 25, at this time the temperature of the regenerator 25 increases, and the temperature and pressure of the sound wave decrease. However, in the actual heat exchange process, the heat exchange process of the regenerator 25 is not constant volume, and the complete heat exchange between the real sound wave and the filler of the regenerator 25 is not possible.

Acoustic laminar flow process: the gas flows through the cold end heat exchanger 24 and then passes through the deflector 32, and enters the pulse tube 31 in the form of laminar flow, pushing the gas in the pulse tube 31 to the expansion chamber 28. After the gas is squeezed, the pressure and temperature rise. The generated heat is radially transferred to the primary hot end heat exchanger 26 through the secondary hot end heat exchanger 33 , and finally transferred to the radiator 27 and released to the environment. The gas in the expansion chamber 28 expands to do work, which assists in pushing the expansion piston to the bottom dead center, and the work is recovered and the compression chamber becomes smaller, which plays a role in recovering sound work. In the actual working process, the compression piston 19 will not stay at the top dead center all the time, but will move downward together with the expansion piston 21, but it should be pointed out that the two do not move in the same direction, but the expansion piston leads the compression piston a certain phase angle.

Sonic refrigeration process: the expansion piston 21 moves upward from the bottom dead center to the top dead center, the compression piston 19 moves to the bottom dead center, the expansion piston 21 pushes the sound wave in the expansion chamber 28 back into the pulse tube 31, and the gas expands in the pulse tube It absorbs heat, produces a cooling effect, and reaches the lowest cooling temperature at the top of the pulse tube 31 near the deflector 32 . The generated cold energy is exported to the cold environment through the cold end heat exchanger 24 . The sonic working medium returns to the regenerator 25 along the original path and fully contacts the filler for heat exchange. After absorbing the heat in the regenerator 25, it returns to the main compression chamber 29 to wait for the next compression. During this process, the temperature and pressure of the sound wave rise, and the temperature of the regenerator 25 falls. In the actual process, when the compression piston 19 reaches the bottom dead center, the expansion piston 21 does not reach the top dead center, but is in the process of returning to the top dead center, but it still leads the compression piston 19 in displacement wave phase.

This embodiment is suitable for a cooling temperature above 220K (-53°C), and can provide a cooling capacity of 50W-200W.

Action and effect of the embodiment

The pulse-tube free-piston Stirling refrigerator of this embodiment cancels the long low-temperature expansion piston of the traditional free-piston Stirling refrigerator, and replaces it with a work-recovery expansion piston that works in a shorter room temperature region. The expansion cylinder of the free-piston Stirling refrigerator becomes the pulse tube of the pulse tube cold finger. The cold end of the pulse tube is arranged with a laminar flow guide, and the hot end is provided with a secondary heat exchanger at the hot end. This change combines the advantages of a free-piston Stirling refrigerator and a pulse-tube refrigerator. By eliminating the high-frequency motion of the expansion piston at the cold and hot ends, the pumping loss, shuttle loss and axial loss caused by the low-temperature expansion piston are eliminated. Thermal loss. The problem of sound power recovery of the pulse tube refrigerator is solved by setting a short room temperature expansion piston at the hot end. Therefore, when the sound power at the cold end is completely recovered, the theoretical efficiency of the new pulse tube free-piston Stirling refrigerator is Carnot. cycle efficiency. At the same time, the cancellation of the low-temperature expansion piston reduces the difficulty of manufacturing the refrigerator and reduces the quality of the whole machine.

The above embodiments are preferred cases of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (8)

1. A multi-temperature-zone refrigerator adopting a pulse tube type free piston Stirling refrigerator is characterized by comprising:

a refrigerator body and a refrigerating system are arranged in the refrigerator,

the refrigerator body comprises a refrigerating chamber, a freezing chamber and a temperature-changing chamber, wherein the refrigerating chamber is positioned at the upper half part of the refrigerator body, and the freezing chamber and the temperature-changing chamber are positioned at the lower half part of the refrigerator; the refrigerating system consists of a compression throttling refrigerating system and a free piston Stirling refrigerator-heat pipe system, wherein the free piston Stirling refrigerator-heat pipe system comprises a pulse tube type free piston Stirling refrigerator, a cold end gravity heat pipe, a hot end gravity heat pipe, a cold guide copper sleeve and a heat conduction copper sleeve, a condensation section pipeline of the hot end gravity heat pipe is upwards arranged on the inner side of the left wall surface of a refrigerator shell, an evaporation section pipeline of the cold end gravity heat pipe is downwards arranged on the rear wall surface and the left and right wall surfaces in the temperature change chamber, the condensation section of the cold end gravity heat pipe is connected with a cold head of the pulse tube type free piston Stirling refrigerator through the cold guide copper sleeve, the evaporation section of the hot end gravity heat pipe is connected with the hot end of the pulse tube type free piston Stir,

the pulse tube type free piston Stirling refrigerator comprises a linear motor, a compression unit, an expansion unit and a frame,

wherein the frame comprises a flange, a piston pipe arranged in the flange and a base,

the flange is in a disc shape, one side of the flange is also provided with a concentric small disc,

the base is in a cylindrical shape, one end of the base is connected with the other side of the flange, the other end of the base is a free end, the central line of the base is superposed with the central line of the flange,

the piston tube is a straight tube, one end opening is positioned at the outer side of the small disc, the other end opening is positioned in the base, a cylindrical piston cavity is arranged in the piston tube and used for accommodating a compression piston and an expansion piston of the refrigerator, a plurality of through holes penetrating through the tube wall of the piston tube are arranged on the piston cavity,

the linear motor comprises an outer yoke iron, an inner yoke iron and a rotor, the outer yoke iron and the inner yoke iron are respectively arranged on the rack, a gap is arranged between the outer yoke iron and the inner yoke iron, the rotor is arranged in the gap,

the compression unit is provided with a compression piston and a compression piston spring, the compression piston spring is fixedly connected with the rack through a connecting piece, the compression piston is arranged in the piston pipe, one end of the compression piston is connected with the rotor and the compression piston spring, the other end of the compression piston is a free end,

the expansion unit comprises an expansion piston, an expansion piston spring, an expansion piston rod, a primary hot end heat exchanger, a secondary hot end heat exchanger, a heat regenerator, a pulse tube, a cold end heat exchanger and a fluid director,

the first-stage hot end heat exchanger is cylindrical, is sleeved on the outer wall of the piston tube and is arranged on the end surface of the small disc,

one end of the pulse tube is connected with one end of the outer side of the piston tube, the other end of the pulse tube is connected with the cold end heat exchanger,

the fluid director is arranged at one end of the pulse tube and is positioned in the pulse tube,

the heat regenerator is cylindrical and arranged on the outer side of the pulse tube, one end of the heat regenerator is connected with the cold end heat exchanger, the other end of the heat regenerator is connected with the primary hot end heat exchanger,

the secondary hot end heat exchanger is arranged in the pulse tube,

the expansion piston is arranged in the piston pipe, the expansion piston spring is fixedly connected with the frame through a connecting piece, one end of the expansion piston rod is connected with the expansion piston, the other end of the expansion piston rod penetrates through the compression piston and the compression piston spring and then is connected with the expansion piston spring,

the compression piston, the expansion piston and the piston chamber constitute a compression chamber,

the expansion piston, the secondary hot end heat exchanger and the piston cavity form an expansion cavity.

2. The multi-temperature zone refrigerator using the pulse tube type free piston stirling cooler of claim 1, wherein:

the heat-conducting copper sleeve is a circular copper sleeve, an opening at one end of the heat-conducting copper sleeve is connected with the cold head of the pulse tube type free piston Stirling refrigerator, heat-conducting silicone grease is coated between the inner side of the circular copper sleeve and the cold head of the pulse tube type free piston Stirling refrigerator, and a circular groove is formed in the circular copper sleeve so that a heat-conducting working medium flows in the circular groove to fully exchange heat; and two cold-conducting small holes communicated with the annular groove are formed in the side surface of the circular copper sleeve.

3. The multi-temperature zone refrigerator using the pulse tube type free piston stirling cooler of claim 1, wherein:

the heat-conducting copper sleeve is an annular copper sleeve, heat-conducting silicone grease is coated between the inner surface of the annular copper sleeve and the hot end of the pulse tube type free piston Stirling refrigerator, and an annular groove is formed in the annular copper sleeve, so that a heat-transfer working medium flows in the annular groove to fully exchange heat; two heat conduction small holes communicated with the annular groove are formed in the side face of the annular copper sleeve.

4. The multi-temperature zone refrigerator using the pulse tube type free piston stirling cooler of claim 1, wherein:

the refrigerating temperature range of the temperature-changing chamber is-60-10 ℃, and the temperature-changing chamber is provided with cold energy by the pulse tube type free piston Stirling refrigerating machine; the pulse tube type free piston Stirling refrigerator is an integral free piston Stirling refrigerator driven by a linear motor, the pulse tube type free piston Stirling refrigerator is installed in the middle of the left side of the refrigerator, a damping block is fixed at the tail of the pulse tube type free piston Stirling refrigerator, and the damping block faces to a back plate of a refrigerator body.

5. The multi-temperature zone refrigerator using the pulse tube type free piston stirling cooler of claim 1, wherein:

the cold-end gravity heat pipe comprises a first cold-end heat pipe and a second cold-end heat pipe, wherein the first cold-end heat pipe and the second cold-end heat pipe are respectively connected with a first cold guide small hole and a second cold guide small hole on the side surface of a cold guide copper sleeve, a cold-end gravity heat pipe pipeline inclines downwards by an angle of 15 degrees, and a working medium used in the cold-end gravity heat pipe pipeline is R170; the hot end gravity heat pipe comprises a first hot end heat pipe and a second hot end heat pipe, the first hot end heat pipe and the second hot end heat pipe are respectively connected with a first heat conduction small hole and a second heat conduction small hole in the side face of the heat conduction copper sleeve, and a hot end gravity heat pipe pipeline inclines downwards by 10 degrees.

6. The multi-temperature zone refrigerator using a pulse tube type free piston stirling cooler of claim 1 further comprising:

and the fluid director is arranged at one end of the pulse tube and is positioned in the pulse tube.

7. The multi-temperature zone refrigerator using the pulse tube type free piston stirling cooler of claim 1, wherein:

the cold end heat exchanger and the heat regenerator are further provided with a first filter layer, and the first filter layer is cylindrical and made of a stainless steel wire mesh.

8. The multi-temperature zone refrigerator using the pulse tube type free piston stirling cooler of claim 1, wherein:

wherein, the heat regenerator is cylindrical and is made of polyester films.

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