Magnetofluid thermal switch and heat conduction control method

Abstract

The invention relates to a magnetofluid thermal switch and a heat conduction control method. The technical problems that existing space observation equipment is large in refrigeration difficulty, poor in heat dissipation and large in heat dissipation design difficulty are solved. The device comprises a heat conduction mounting plate, a separation heat insulation pad, an annular heat insulation pad, a working area sealing cavity and a storage area sealing cavity; the heat-conducting mounting plate and the separating heat-insulating pad are connected to define a working area; the two ends of the working area are connected with the working area sealing cavity and the storage area sealing cavity through annular heat insulation pads respectively. The working area sealing cavity is provided with a working area sealing cavity communicated with the working area; a working area coil protection layer and a working area magnetic coil are arranged on the inner wall of the working area sealing cavity; the storage area sealing cavity is provided with a storage area sealing cavity communicated with the working area; a storage area coil protection layer and a storage area magnetic coil are arranged on the inner wall of the storage area sealing cavity; the other cavity part of the storage area sealing cavity forms a storage area, and the storage area and a vacuum cavity in the working area are filled with magnetic fluid.

Description

Technical Field

[0001] The invention relates to a thermal switch, in particular to a magnetic fluid thermal switch and a heat conduction control method. Background Art

[0002] With the increasing demand for in-depth research and development in the field of space astronomical observation, observation tasks require high-sensitivity and wide-field observation. Since the target signal energy is weak, the observation instrument needs to have high-sensitivity and low-noise observation performance. For space optical camera detectors, in order to reduce thermal noise interference, they need to be cooled to a lower temperature. At this time, the heat of the detector will be radiated and dissipated through the heat sink.

[0003] In order to obtain target signals with a wide field of view, the space optical camera detector has a certain azimuth and elevation angle, which causes a large amount of heat flux from the sun to the heat sink in some working conditions, thus affecting the cooling and heat dissipation of the detector, and further affecting the detection performance of the optical camera. At this time, if we only rely on increasing the area of ​​the heat sink to meet the cooling temperature, the effect is limited, and this will have an adverse effect on the satellite weight reduction and mechanical fundamental frequency.

[0004] As the requirements for satellite payload functions and performance become higher and higher, the heat generated by electronic equipment on satellites is also increasing. The heat dissipation surfaces on the cabin panels in different directions will be alternately exposed to the sun. While dissipating heat, the heat sink also absorbs solar radiation heat flux, which will also reduce the heat dissipation effect of the heat sink. In addition, electronic equipment on satellites is turned on intermittently. When it is hot, it needs to be cooled by heat conduction. When it is not hot, it needs to be heated by a heater to prevent the temperature of the electronic equipment from being too low. This also has certain requirements for heat dissipation design. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problems of difficult refrigeration, poor heat dissipation and difficult heat dissipation design in existing space observation equipment, and to provide a magnetic fluid thermal switch and thermal conductivity control method.

[0006] The concept of the present invention is to use a thermal switch to control the on and off of the heat transfer path, that is, when the electronic device is turned off and does not generate heat, the heat transfer path is closed and insulated. Specifically, a magnetic fluid thermal switch is designed. When the heat sink on one side is exposed to the sun and the temperature rises, the heat transfer between the heat sink on this side and the heat generating component is suppressed; when the heat sink on this side is not exposed to the sun, after the temperature of the heat sink drops to a certain level, the heat transfer between the heat sink on this side and the heat generating component is improved, thereby meeting the cooling requirements of the detector and the electronic device on the one hand, and reducing the area of ​​the heat sink on the other hand, reducing the difficulty of thermal design and structural design.

[0007] In order to achieve the above objectives and realize the above concepts, the technical solutions provided by the present invention are as follows:

[0008] A magnetic fluid thermal switch, which is special in that:

[0009] It includes two heat-conducting mounting plates, two separate heat-insulating pads, two annular heat-insulating pads, a sealed cavity in a working area, and a sealed cavity in a storage area;

[0010] Two heat-conducting mounting plates are arranged at intervals, and two separation heat-insulating pads are arranged oppositely in the intervals between the two heat-conducting mounting plates to enclose a working area;

[0011] The two ends of the working area are connected to the working area sealed cavity and the storage area sealed cavity through annular heat insulation pads respectively;

[0012] The working area sealed cavity body is provided with a working area sealed cavity located inside thereof and a working area connecting port located on the surface thereof, and the working area sealed cavity is connected with the working area through the working area connecting port; a working area coil protection layer and a working area magnetic coil are provided on the inner wall of the working area sealed cavity away from the working area connecting port;

[0013] The storage area sealed cavity body is provided with a storage area sealed cavity located inside thereof and a storage area connecting port located on the surface, and the storage area sealed cavity is connected with the working area through the storage area connecting port; a storage area coil protection layer and a storage area magnetic coil are provided on the inner wall of the storage area sealed cavity away from the storage area connecting port; the storage area magnetic coil includes a storage area central magnetic coil and at least one storage area edge magnetic coil; the storage area central magnetic coil is close to the storage area connecting port, and the storage area edge magnetic coil is away from the storage area connecting port;

[0014] The remaining cavity of the storage area sealed cavity constitutes the storage area, and the vacuum cavity in the storage area and the working area is filled with magnetic fluid; the working area magnetic coil is insulated from the magnetic fluid by the working area coil protection layer; the storage area magnetic coil is insulated from the magnetic fluid by the storage area coil protection layer;

[0015] The volume V1 of the magnetic fluid, the volume V2 of the storage area and the volume V3 of the working area satisfy the relationship:

[0016] V1 <V2+V3。

[0017] Furthermore, the working area magnetic coil is embedded in the working area coil protection layer; the surface of the working area coil protection layer facing the working area is smooth; the working area coil protection layer fills the working area sealed cavity, and the smooth surface of the working area coil protection layer is flush with the outer edge of the working area connection port;

[0018] The storage area magnetic coil is embedded in the storage area coil protection layer; the surface of the storage area coil protection layer facing the storage area is smooth.

[0019] Furthermore, the cross-sectional area of ​​the storage area sealed cavity parallel to the plane where the storage area connection port is located gradually increases from the storage area connection port inwards.

[0020] Furthermore, V1, V2 and V3 satisfy the relationship: V3 <V1<V2。

[0021] Furthermore, the sealed cavity of the storage area is a rectangular block structure, the storage area connection port is located at the center of one of its largest surfaces, and the plane where the storage area coil protection layer is located is arranged parallel to the largest surface; there are two edge magnetic coils in the storage area, which are located at both ends of the storage area coil protection layer, and the storage area center magnetic coil is located at the storage area coil protection layer corresponding to the storage area connection port.

[0022] Furthermore, the separation insulation pad is a T-shaped structure, with the bottom end of the T facing the working area and sandwiched between two heat-conducting mounting plates.

[0023] Furthermore, the inner surfaces of the heat-conducting mounting plate and the separated heat-insulating pad facing the working area are provided with a gold-plated film or a silver-plated film, and the film meets the condition: infrared emissivity < 0.1.

[0024] Further, the thickness of the thermally conductive mounting plate is 1 mm;

[0025] The heat-conducting mounting plate, the separated heat-insulating pad and the annular heat-insulating pad are all connected by vacuum sealant;

[0026] Magnetic fluid is composed of magnetic metal particles mixed with filling liquid.

[0027] The present invention also provides a magnetic fluid thermal conductivity control method, which is special in that it includes the following steps:

[0028] S0, installing the above-mentioned magnetic fluid thermal switch at the target position, and the two heat-conducting mounting plates correspond to the two ports of the heat transfer path respectively;

[0029] S1, turn on thermal mode

[0030] When heat conduction is required, currents I1, I2, and I3 are respectively passed through the central magnetic coil of the storage area, the edge magnetic coil of the storage area, and the magnetic coil of the working area, where I3>I1, and I2=0;

[0031] S2, conduct heat

[0032] Under the action of the magnetic field, the magnetic fluid flows into the working area;

[0033] When waiting for the magnetic fluid to flow into the working area or fill the working area, the magnetic fluid thermal switch is in the heat conduction mode; at this time, the thermal resistance between the heat conduction mounting plates on both sides of the working area is reduced due to the presence of magnetic fluid, and the temperature difference on both sides is reduced;

[0034] S3, turn on the heat insulation mode

[0035] When thermal insulation is required, currents I1, I2, and I3 are respectively passed through the central magnetic coil of the storage area, the edge magnetic coil of the storage area, and the magnetic coil of the working area, where I2>I1, and I3=0;

[0036] S4, heat insulation

[0037] Under the action of the magnetic field, the magnetic fluid flows into the storage area;

[0038] When waiting for the magnetic fluid to flow into the storage area or fill the storage area, the magnetic fluid thermal switch is in the insulation mode; at this time, the thermal resistance between the heat-conducting mounting plates on both sides of the working area increases due to the vacuum, and the temperature difference on both sides increases, realizing the thermal control of the magnetic fluid.

[0039] Furthermore, after the heat conduction is completed in step S2, the method further includes:

[0040] A. Thermal conductivity and energy saving

[0041] The power-on mode of the magnetic coil in the center of the storage area, the magnetic coil at the edge of the storage area, and the magnetic coil in the working area is changed to intermittent power-on to meet the following conditions: the magnetic fluid does not flow back;

[0042] After the step S4 is completed and the heat insulation is performed, the method further includes:

[0043] B. Heat insulation and energy saving

[0044] The power-on mode of the central magnetic coil in the storage area, the edge magnetic coil in the storage area and the magnetic coil in the working area is changed to intermittent power-on so that the condition is met: the magnetic fluid does not flow back.

[0045] The beneficial effects of the present invention compared with the prior art are as follows:

[0046] 1. The magnetic fluid thermal switch provided by the present invention adopts magnetic fluid in combination with an electromagnetic field to control the on and off of a heat transfer path. Compared with a mechanical contact thermal switch, it has a small size and light weight, and can effectively avoid the problem of thermal switch failure caused by vacuum cold welding.

[0047] 2. A magnetic fluid thermal switch provided by the present invention adopts a structural design of two heat-conducting mounting plates plus two sealed cavities. It is not limited by the size of the mounting interface and can be as small as 5 mm in thickness (where the working area of ​​the magnetic fluid is within 3 mm). It is suitable for use in occasions where the space area of ​​the heat transfer path from the heating equipment to the heat sink is narrow. The space size and shape of the sealed cavity can be flexibly designed according to actual equipment requirements.

[0048] 3. The present invention provides a method for controlling the thermal conductivity of a magnetic fluid, which uses a plurality of adjustable magnetic fields to cooperate with each other to control the flow of the magnetic fluid and realize thermal switching between interfaces, thereby meeting the heat dissipation and thermal insulation requirements of detectors and electronic equipment, and providing the possibility for weight reduction design of heat sinks and the entire satellite.

[0049] 4. The present invention provides a method for controlling the heat conduction of magnetic fluid, which uses an intermittent magnetic field to reduce the power and heat consumption of the magnetic coil while avoiding the backflow of magnetic fluid. When the electronic device is turned off and does not generate heat, the heat transfer path is closed and insulated, which can effectively reduce the insulation compensation power demand when it is turned off and reduce satellite resource consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a structural schematic diagram of an embodiment of a magnetic fluid thermal switch of the present invention;

[0051] Figure 2 yes Figure 1 Exploded diagram of

[0052] Figure 3 Schematic diagram of a half-section of an embodiment of the present invention Figure 1 ;

[0053] Figure 4 Schematic diagram of a half-section of an embodiment of the present invention Figure 2 ;

[0054] Figure 5 Schematic diagram of a half-section of an embodiment of the present invention Figure 3 ;

[0055] Figure 6 yes Figure 5 Exploded diagram of

[0056] Figure 7 yes Figure 5 Cross-sectional view of .

[0057] The following are the descriptions of the accompanying figures:

[0058] 1-heat-conducting mounting plate; 2-separated thermal insulation pad; 3-ring-shaped thermal insulation pad; 4-working area;

[0059] 5-working area sealed cavity, 51-working area sealed cavity, 52-working area connection port; 6-working area magnetic coil; 7-working area coil protection layer;

[0060] 8-storage area sealed cavity, 81-storage area sealed cavity, 82-storage area connecting port; 9-storage area magnetic coil, 91-storage area center magnetic coil, 92-storage area edge magnetic coil; 10-storage area coil protection layer; 11-storage area. DETAILED DESCRIPTION

[0061] The specific technical solutions in the embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0062] The present invention aims to solve the problems that the external heat flux of the heat sink used for heat dissipation of space observation optical cameras and space electronic equipment has a large variation range, solar radiation heating leads to a large design area of ​​the heat sink, and a large compensatory heating power of the electronic equipment, and it is impossible to simultaneously meet the requirements of satellite weight reduction, structural design, thermal design and other indicators. The present invention innovatively adopts magnetic fluid in combination with electromagnetic field control, and utilizes magnetic fluid as the interface filling material between the cold and hot ends of the thermal conductive mounting plate. The flow of magnetic fluid is controlled by changing the magnetic field, thereby regulating the presence or absence of the interface filling material between the cold and hot ends of the thermal conductive mounting plate, and further controlling the switching of the heat transfer path, thereby realizing flexible control of thermal conduction / insulation.

[0063] Figure 1-Figure 7 A magnetic fluid thermal switch provided in an embodiment of the present invention is mainly composed of a sealed cavity in a storage area, a central magnetic coil in the storage area, an edge magnetic coil in the storage area, a magnetic coil in the working area, thermal insulation materials, a coil protection layer and the like. The volume of the storage area is equal to that of the working area, and the thickness of the sealed cavity in the working area is relatively thin (the thinnest is 1mm, which is determined by the area of ​​the thermal conductive mounting plate in the working area. The smaller the area, the thinner the thickness, and the larger the area, the thicker the thickness). The size and shape of the storage area can be flexibly designed according to the available space near the thermal conductive mounting plate. The magnetic coil is insulated from the sealed cavity and the magnetic fluid by the insulating glue of the coil protective layer. The insulating glue of the coil protective layer also plays a role in reducing the resistance of the magnetic fluid during flow. Compared with the insulating skin of the coil itself, it mainly reduces the surface roughness of the coil and reduces the relative resistance of the magnetic fluid during flow. All mounting surfaces have vacuum sealing measures, and the areas inside the cavity without magnetic fluid are in a vacuum state. The specific method is as follows:

[0064] It includes two heat-conducting mounting plates 1, two separated heat-insulating pads 2, two annular heat-insulating pads 3, and a sealed cavity 5 in a working area and a sealed cavity 8 in a storage area, and the cavity is filled with magnetic fluid;

[0065] Workspace

[0066] The working area 4 includes two upper and lower heat-conducting mounting plates 1. The inner surfaces of the heat-conducting mounting plates 1 and the heat-insulating material are plated with a metal film with low infrared emissivity, making "heat-conducting mounting plate - magnetic fluid - heat-conducting mounting plate" the main heat transfer path. Specifically:

[0067] The two heat-conducting mounting plates 1 are spaced apart, and the two separation insulation pads 2 are relatively arranged in the space between the two heat-conducting mounting plates 1 to enclose a working area 4; the two ends of the working area 4 are respectively connected to the working area sealed cavity 5 and the storage area sealed cavity 8 through annular insulation pads 3.

[0068] The separation thermal insulation pad 2 is a T-shaped structure, with the bottom end of the T facing the working area 4, and is sandwiched between two thermally conductive mounting plates 1. The inner surfaces of the thermally conductive mounting plate 1 and the separation thermal insulation pad 2 facing the working area 4 are provided with a gold-plated film or a silver-plated film, and the film meets the condition: infrared emissivity <0.1. The thermally conductive mounting plate also needs to be coated because it is necessary to reduce the radiation heat exchange between the two thermally conductive mounting plates 1 during thermal insulation, and the effect of reducing the radiation heat exchange between the two thermally conductive mounting plates 1 is achieved by reducing the radiation emissivity. The thickness of the thermally conductive mounting plate 1 is 1 mm. The thermally conductive mounting plate 1, the separation thermal insulation pad 2 and the annular thermal insulation pad 3 are connected by vacuum sealant.

[0069] The working area sealed cavity 5 is provided with a working area sealed cavity 51 located inside thereof and a working area connecting port 52 located on the surface thereof, and the working area sealed cavity 51 is connected with the working area 4 through the working area connecting port 52; a working area coil protection layer 7 and a working area magnetic coil 6 are provided on the inner wall of the working area sealed cavity 51 away from the working area connecting port 52, and the working area magnetic coil 6 is embedded in the working area coil protection layer 7 and insulated from the magnetic fluid through the working area coil protection layer 7; the surface of the working area coil protection layer 7 facing the working area 4 is smooth; the working area coil protection layer 7 fills the working area sealed cavity 51, and the smooth surface of the working area coil protection layer 7 is flush with the outer edge of the working area connecting port 52.

[0070] Storage Area

[0071] There are three sets of magnetic coils in the storage area. The positive and negative poles of the magnetic coils pass through the sealed cavity and are connected to the magnetic coil control component. The surface of the coil protection layer in the storage area is smooth, and the edges on both sides of the storage area are sloped, thereby reducing the flow resistance during the flow of magnetic fluid and reducing the required magnetic field. Specifically:

[0072] The storage area sealed cavity 8 is provided with a storage area sealed cavity 81 located inside thereof and a storage area connecting port 82 located on the surface, and the storage area sealed cavity 81 is connected with the working area 4 through the storage area connecting port 82; a storage area coil protection layer 10 and a storage area magnetic coil 9 are provided on the inner wall of the storage area sealed cavity 81 away from the storage area connecting port 82, and the storage area magnetic coil 9 is embedded in the storage area coil protection layer 10 and insulated from the magnetic fluid through the storage area coil protection layer 10; the storage area magnetic coil 9 includes a storage area center magnetic coil 91 and at least one storage area edge magnetic coil 92; the storage area center magnetic coil 91 is close to the storage area connecting port 82, and the storage area edge magnetic coil 92 is away from the storage area connecting port 82; the surface of the storage area coil protection layer 10 facing the storage area 11 is smooth.

[0073] The storage area sealed cavity 8 is a rectangular block structure. The storage area connection port 82 is located at the center of its largest surface. The plane where the storage area coil protection layer 10 is located is parallel to this largest surface. There are two storage area edge magnetic coils 92, which are respectively located at both ends of the storage area coil protection layer 10. The storage area center magnetic coil 91 is located at the position of the storage area coil protection layer 10 corresponding to the storage area connection port 82.

[0074] The cross-sectional area of the storage area sealed cavity 81 parallel to the plane of the storage area connection port 8 gradually increases from the storage area connection port 82 inward, that is, it realizes reducing the flow resistance during the flow of the magnetic fluid, improving the fluidity of the magnetic fluid, and at the same time can reduce the magnetic field required for the magnetic coil to attract the magnetic fluid. The rest of the cavity part of the storage area sealed cavity 81 constitutes the storage area 11. The storage area 11 and the vacuum cavity in the working area 4 are filled with magnetic fluid, and the fluid is composed of magnetic metal particle-doped filling liquid. Most of the magnetic fluid is magnetic metal particles, and the filling liquid of the polymer material only plays the role of filling the gaps between the particles and accounts for a relatively small volume.

[0075] The relationship among the volume V1 of the magnetic fluid, the volume V2 of the storage area 11, and the volume V3 of the working area 4 is satisfied: V3 < V1 < V2. The more the working area 4 filled with magnetic fluid, the better the thermal conductivity. If V1 > V2, there will always be magnetic fluid in the working area 4, which will affect the heat insulation performance.

[0076] The working principle of the embodiment of the present invention is as follows:

[0077] When the thermal switch plays a heat conduction role, a larger current is given to the working area magnetic coil, a smaller current is given to the storage area center magnetic coil, and the storage area edge magnetic coil is not energized. The magnetic fluid will flow from the storage area to the working area under the action of the magnetic field. After all the magnetic fluid flows into the working area, the magnetic fluid fills between the two heat conduction mounting plates on both sides of the working area, the thermal resistance decreases, and the temperature difference between the two sides of the heat conduction mounting plate in the working area decreases significantly. At this time, the power-on mode is changed to intermittent power-on, which can reduce the magnetic coil power and heat consumption while avoiding the backflow of the magnetic fluid;

[0078] When the thermal switch plays a heat insulation role, a larger current is given to the storage area edge magnetic coil, a smaller current is given to the storage area center magnetic coil, and the working area magnetic coil is not energized. The magnetic fluid will flow from the working area to the storage area under the action of the magnetic field. After all the magnetic fluid flows into the storage area, there is no magnetic fluid conduction between the two heat conduction mounting plates on both sides of the working area, the thermal resistance increases, and the temperature difference between the two sides of the heat conduction mounting plate increases significantly. At this time, the power-on mode is changed to intermittent power-on, and the function is the same as above.

[0079] The steps of a magnetic fluid heat conduction control method provided in this embodiment are as follows:

[0080] S0, install a magnetic fluid thermal switch at the target position, and the two heat conduction mounting plates 1 respectively correspond to the two ports of the heat transfer path;

[0081] S1, turn on thermal mode

[0082] When heat conduction is required, currents I1, I2, and I3 are respectively passed through the storage area center magnetic coil 91, the storage area edge magnetic coil 92, and the working area magnetic coil 6, where I3>I1, and I2=0;

[0083] S2, conduct heat

[0084] Under the action of the magnetic field, the magnetic fluid flows into the working area 4;

[0085] When waiting for the magnetic fluid to flow into the working area 4 completely or filling the working area 4, the magnetic fluid thermal switch is in the heat conduction mode; at this time, due to the presence of the magnetic fluid, the thermal resistance between the heat conduction mounting plates 1 on both sides of the working area 4 is reduced, and the temperature difference on both sides is reduced;

[0086] A. Thermal conductivity and energy saving

[0087] The power-on mode of the storage area center magnetic coil 91, the storage area edge magnetic coil 92 and the working area magnetic coil 6 is changed to intermittent power-on so that the conditions are met: the magnetic fluid does not flow back;

[0088] S3, turn on the heat insulation mode

[0089] When thermal insulation is required, currents I1, I2, and I3 are respectively passed through the storage area center magnetic coil 91, the storage area edge magnetic coil 92, and the working area magnetic coil 6, where I2>I1, and I3=0;

[0090] S4, heat insulation

[0091] Under the action of the magnetic field, the magnetic fluid flows into the storage area 11;

[0092] When waiting for the magnetic fluid to flow into the storage area 11 or filling the storage area 11, the magnetic fluid thermal switch is in the heat insulation mode; at this time, the thermal resistance between the heat-conducting mounting plates 1 on both sides of the working area 4 increases due to the vacuum, and the temperature difference on both sides increases;

[0093] B. Heat insulation and energy saving

[0094] The power-on mode of the storage area center magnetic coil 91, the storage area edge magnetic coil 92 and the working area magnetic coil 6 is changed to intermittent power-on so that the condition is met: the magnetic fluid does not flow back.

[0095] The above content is only an embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A magnetic fluid thermal switch, characterized in that: It comprises two heat-conducting mounting plates (1), two separated heat-insulating pads (2), two annular heat-insulating pads (3), a working area sealed cavity (5) and a storage area sealed cavity (8); The two heat-conducting mounting plates (1) are arranged at a distance from each other, and the two separation heat-insulating pads (2) are arranged relatively in the distance between the two heat-conducting mounting plates (1) to enclose a working area (4); The two ends of the working area (4) are respectively connected to the working area sealed cavity (5) and the storage area sealed cavity (8) through the annular heat insulation pad (3); The working area sealed cavity body (5) is provided with a working area sealed cavity (51) located inside thereof and a working area connecting port (52) located on the surface thereof, and the working area sealed cavity (51) is connected with the working area (4) via the working area connecting port (52); a working area coil protection layer (7) and a working area magnetic coil (6) are provided on the inner wall of the working area sealed cavity (51) away from the working area connecting port (52); The storage area sealed cavity body (8) is provided with a storage area sealed cavity (81) located inside the storage area sealed cavity body (8) and a storage area connecting port (82) located on the surface; the storage area sealed cavity (81) is connected to the working area (4) through the storage area connecting port (82); a storage area coil protection layer (10) and a storage area magnetic coil (9) are provided on the inner wall of the storage area sealed cavity (81) away from the storage area connecting port (82); the storage area magnetic coil (9) includes a storage area central magnetic coil (91) and at least one storage area edge magnetic coil (92); the storage area central magnetic coil (91) is close to the storage area connecting port (82), and the storage area edge magnetic coil (92) is away from the storage area connecting port (82); The remaining cavity portion of the storage area sealed cavity (81) constitutes a storage area (11), and the vacuum cavity in the storage area (11) and the working area (4) is filled with magnetic fluid; the working area magnetic coil (6) is insulated from the magnetic fluid by the working area coil protection layer (7); the storage area magnetic coil (9) is insulated from the magnetic fluid by the storage area coil protection layer (10); The volume V1 of the magnetic fluid, the volume V2 of the storage area (11) and the volume V3 of the working area (4) satisfy the relationship: V1 <V2+V3。 2. A magnetic fluid thermal switch according to claim 1, characterized in that: The working area magnetic coil (6) is embedded in the working area coil protection layer (7); the surface of the working area coil protection layer (7) facing the working area (4) is smooth; the working area coil protection layer (7) fills the working area sealed cavity (51), and the smooth surface of the working area coil protection layer (7) is flush with the outer edge of the working area connection port (52); The storage area magnetic coil (9) is embedded in the storage area coil protection layer (10); the surface of the storage area coil protection layer (10) facing the storage area (11) is smooth.

3. A magnetic fluid thermal switch according to claim 2, characterized in that: The cross-sectional area of ​​the storage area sealed cavity (81) parallel to the plane where the storage area connecting port (82) is located gradually increases from the storage area connecting port (82) inwards.

4. A magnetic fluid thermal switch according to any one of claims 1 to 3, characterized in that: The V1, V2 and V3 satisfy the relationship: V3 <V1<V2。 5. A magnetic fluid thermal switch according to claim 4, characterized in that: The storage area sealed cavity (8) is a rectangular block structure, the storage area connection port (82) is located at the center of one of its largest surfaces, and the plane where the storage area coil protection layer (10) is located is arranged parallel to the largest surface; there are two storage area edge magnetic coils (92), which are respectively located at the two ends of the storage area coil protection layer (10), and the storage area center magnetic coil (91) is located at the storage area coil protection layer (10) corresponding to the storage area connection port (82).

6. A magnetic fluid thermal switch according to claim 5, characterized in that: The separation insulation pad (2) is a T-shaped structure, with the bottom end of the T facing the working area (4) and sandwiched between the two heat-conducting mounting plates (1).

7. A magnetic fluid thermal switch according to claim 6, characterized in that: The inner surfaces of the heat-conducting mounting plate (1) and the separation heat-insulating pad (2) facing the working area (4) are provided with a gold-plated film or a silver-plated film, and the film meets the condition that the infrared emissivity is less than 0.

1.

8. A magnetic fluid thermal switch according to claim 7, characterized in that: The thickness of the heat-conducting mounting plate (1) is 1 mm; The heat-conducting mounting plate (1), the separation heat-insulating pad (2) and the annular heat-insulating pad (3) are all connected by vacuum sealant; The magnetic fluid is composed of magnetic metal particles mixed with filling liquid.

9. A method for controlling heat conduction of magnetic fluid, characterized in that: The following steps are involved: S0, installing a magnetic fluid thermal switch according to any one of claims 1 to 8 at a target position, wherein the two heat-conducting mounting plates (1) correspond to two ports of a heat transfer path respectively; S1, turn on thermal mode When heat conduction is required, currents I1, I2, and I3 are respectively passed through the storage area center magnetic coil (91), the storage area edge magnetic coil (92), and the working area magnetic coil (6), wherein I3>I1, and I2=0; S2, conduct heat Under the action of the magnetic field, the magnetic fluid flows into the working area (4); When the magnetic fluid is waiting to flow into the working area (4) completely or the working area (4) is filled, the magnetic fluid thermal switch is in a heat conduction mode; at this time, due to the presence of the magnetic fluid, the thermal resistance between the heat conduction mounting plates (1) on both sides of the working area (4) is reduced, and the temperature difference between the two sides is reduced; S3, turn on the heat insulation mode When heat insulation is required, currents I1, I2, and I3 are respectively passed through the storage area center magnetic coil (91), the storage area edge magnetic coil (92), and the working area magnetic coil (6), wherein I2>I1, and I3=0; S4, heat insulation Under the action of the magnetic field, the magnetic fluid flows into the storage area (11); When waiting for the magnetic fluid to flow into the storage area (11) completely or filling the storage area (11), the magnetic fluid thermal switch is in a heat insulation mode; at this time, due to the vacuum between the heat-conducting mounting plates (1) on both sides of the working area (4), the thermal resistance increases and the temperature difference on both sides increases, thereby achieving magnetic fluid thermal control.

10. A magnetic fluid thermal conductivity control method according to claim 9, characterized in that: After the step S2 is completed to conduct heat, the method further includes: A. Thermal conduction and energy saving The power-on mode of the storage area center magnetic coil (91), the storage area edge magnetic coil (92) and the working area magnetic coil (6) is changed to intermittent power-on mode, so that the conditions are met: the magnetic fluid does not flow back; After the step S4 is completed and the heat insulation is performed, the method further includes: B. Heat insulation and energy saving The energizing mode of the storage area center magnetic coil (91), the storage area edge magnetic coil (92) and the working area magnetic coil (6) is changed to intermittent energization so that the condition is met: the magnetic fluid does not flow back.

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