Cooling plate and projectile

Abstract

To obtain a cooling plate that improves heat dissipation of an electronic device.SOLUTION: A cooling plate 7 cools an electronic device 6 provided inside a projectile. The cooling plate 7 includes a metal portion 71 that comes into contact with electronic device 6. The interior of the metal portion 71 includes a porous body 72 with communicating holes. The porous body 72 is in contact with the inner wall surface of the metal portion 71. The porous body 72 is formed such that the pore diameter changes. A refrigerant 8 is placed inside the porous body 72. A discharge port 74 capable of discharging the vaporized refrigerant 8 to the outside of the porous body 72 is formed in the metal portion 71.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a cooling plate and a heat pipe for cooling an electronic device.

Background Art

[0002] An electronic device is mounted inside the heat pipe. The electronic device generates heat by itself during the flight of the heat pipe. In order to keep the temperature inside the electronic device within the guaranteed temperature during a predetermined operation time, the heat pipe is provided with a cooling plate that releases the heat generated by the electronic device. The conventional cooling plate uses boiling cooling due to the phase change of the refrigerant to cool the electronic device (see, for example, Patent Document 1).

[0003] The cooling plate of Patent Document 1 includes a metal part that contacts the electronic device. A plurality of refrigerant flow paths are arranged inside the metal part below the heat dissipation surface where the electronic device is mounted. One end of the refrigerant flow path is connected to the discharge port, and the vaporized refrigerant is discharged from the discharge port to the outside of the refrigerant flow path. The cross-sectional area of the refrigerant flow path expands from one end to the other end, and the refrigerant located on the other end side is supplied to the one end side by capillary action.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the cooling plate of Patent Document 1, the injection amount of the refrigerant is limited to the volume of the refrigerant flow path arranged at a predetermined interval below the heat dissipation surface of the metal part. In addition, the movement of the refrigerant accommodated on the other end side of the refrigerant flow path is limited in one direction, and the volume of the moving refrigerant depends on the cross-sectional area of the refrigerant flow path. Therefore, sufficient liquid refrigerant is not transported toward one end of the refrigerant flow path, resulting in a problem of reduced heat dissipation.

[0006] The present invention has been made in view of the above, and an object thereof is to obtain a cooling plate that enhances the supply capacity of a liquid refrigerant by capillary action and improves the heat dissipation performance of an electronic device per unit area.

Means for Solving the Problems

[0007] The cooling plate according to the present invention includes a metal part that is thermally or mechanically connected to an electronic device, and a porous body provided inside the metal part and having a plurality of communicating pores formed therein. The outer surface of the porous body is in contact with the inner wall surface of the metal part. The porous body has a smaller pore diameter on the inner wall surface side of the metal part than in the central part. A refrigerant is contained inside the porous body, and the metal part is formed with a discharge port capable of discharging the vaporized refrigerant to the outside of the porous body.

Effects of the Invention

[0008] According to the present invention, by providing a porous body that can accommodate more liquid refrigerant inside the metal part and is formed such that the pore diameter is smaller on the inner wall surface side of the metal part than in the central part, the liquid refrigerant is continuously supplied to the vicinity of the heat receiving part, and the heat dissipation performance of the electronic device per unit area is improved.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] The cooling plate and the projectile according to the embodiment of the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited by this embodiment.

[0011] ***Description of the configuration of Embodiment 1*** FIG. 1 is a schematic diagram showing a projectile 1 according to Embodiment 1 of the present invention. The projectile 1 includes a guiding device 2 that guides the projectile 1 to a target, and a propulsion device (not shown) disposed at the rear of the guiding device 2 that applies a propulsion force to the projectile 1. The guiding device 2 includes an outer shell member 3, an antenna 4, and a pressure regulating valve 5.

[0012] The outer shell member 3 is a metal member that forms the outer shell of the guiding device 2. The pressure regulating valve 5 is fixed to the outer shell member 3. The pressure regulating valve 5 covers an outlet (not shown) formed in the outer shell member 3 so as to be openable and closable. The pressure regulating valve 5 has a function of adjusting the pressure inside the projectile 1.

[0013] The antenna 4 is installed inside the outer shell member 3. The antenna 4 has a plurality of electronic devices 6 and a plurality of cooling plates 7. The electronic devices 6 are fixed to a frame (not shown) provided inside the guiding device 2 with bolts or the like.

[0014] FIG. 2 is a diagram showing the electronic device 6 and the cooling plate 7 according to Embodiment 1. The cooling plate 7 is a member that cools the electronic device 6 provided inside the projectile 1. The cooling plate 7 is disposed sandwiched between two electronic devices 6. The cooling plate 7 and the electronic device 6 are fixed with bolts and nuts (not shown). The electronic device 6 is thermally and mechanically connected to the cooling plate 7 in close contact or via a heat dissipating material. The cooling plate 7 includes a metal part 71.

[0015] The metal part 71 is a metal part that contacts the electronic device 6. The metal part 71 serves to transfer the heat 11 generated in the electronic device 6 to the refrigerant 8 described later. The material of the metal part 71 is not particularly limited, but in this embodiment, it is an aluminum alloy. The surface of the metal part 71 where the electronic device 6 is mounted is a smooth and flat heat dissipation surface. An internal space is formed in the metal part 71, and the porous body 72 is accommodated therein. The outer surface of the porous body 72 is in close contact with the inner wall surface in contact with the internal space of the metal part 71. In FIG. 2, the electronic device 6 is mounted on the metal part 71 on the upper surface side and the metal part 71 on the lower surface side of the cooling plate 7.

[0016] FIG. 3 is a cross-sectional view taken along the line III-III shown in FIG. 2. Inside the porous body 72, the pores communicate with each other, and the refrigerant 8 is filled in the pores. The material of the porous body 72 is not particularly limited, but in this embodiment, it is an aluminum alloy of the same quality as the metal part 71. Inside the porous body 72, a gradient is formed in the pore density, with the center part being rough and becoming denser towards the outside. The porous body 72 in the present embodiment shown in FIG. 3 is composed of two types of porous bodies: a first porous body 72a that constitutes the central part of the porous body 72 and a second porous body 72b having a smaller pore diameter than the first porous body 72a. The second porous body 72b is arranged so as to envelop the outside of the first porous body 72a, and its outer surface is in contact with the inner wall surface of the metal part 71. The first porous body 72a has a rectangular parallelepiped block shape. The outer surface of the second porous body 72b has a rectangular shape, and the inner hollow space has a rectangular parallelepiped block shape of the same shape as the first porous body 72a. However, the configuration of the porous body 72 is not particularly limited to this configuration, and it may be composed of three or more types of porous bodies, or may have a configuration in which the pore diameter changes continuously.

[0017] On the side surface of the cooling plate 7, an injection port 73 for injecting the refrigerant 8 into the porous body 72 and a discharge port 74 through which the vaporized refrigerant 8 is discharged as described later are formed. The positions and numbers of the injection port 73 and the discharge port 74 are not particularly limited, but in the present embodiment shown in FIG. 3, the injection port 73 and the discharge port 74 are formed one by one on the mutually facing surfaces. The injection port 73 may have a lid body 73a (not shown) that can be opened and closed in order to prevent the liquid refrigerant 8 from leaking out of the cooling plate 7 during operation. The lid body 73a is attached so as to close the injection port 73 in a watertight and airtight manner, preventing the refrigerant 8 in the liquid phase state and the gas phase state (vapor) from leaking out from the injection port 73 to the outside. As a result, it becomes possible to refill the liquid refrigerant 8 evaporated during the operation test or the like. As shown in FIG. 3, the second porous body 72b having a smaller pore diameter than the first porous body 72a is disposed at a position closer to the electronic device 6 than the first porous body 72a.

[0018] As one of the manufacturing methods of the cooling plate 7 in which the pore diameter changes inside, die-casting technology can be mentioned. In die-casting technology, the metal part 71 that holds the refrigerant 8 and the internal porous body 72 can be manufactured integrally, and mass production is also possible.

[0019] Further, the metal part 71 and the porous body 72 may be manufactured by a metal additive manufacturing technology using a metal 3D printer. The metal additive manufacturing technology is, for example, a laser melting method of melting and solidifying a powder of a metal alloy, or a powder bed method using an electron beam.

[0020] The porous body 72 is composed of, for example, a porous structure. Further, the porous body 72 may have, near the center, a lattice structure in which, for example, a plurality of lattices are periodically arranged. Furthermore, the first porous body 72a may be formed of a lattice structure layer, and the second porous body 72b may be formed of a porous structure layer. The lattice structure can be formed with an interval between adjacent branches forming the lattice having a size of, for example, 1 to 5 mm. The porous structure is preferably formed with a pore radius of 0.5 or less, and preferably 0.04 mm to 0.5 mm.

[0021] The refrigerant 8 is a substance with a specific gravity smaller than that of the metal part 71 and becoming a liquid at normal temperature. Although not particularly limited, the refrigerant 8 is pure water in the present embodiment. The heat 11 generated in the electronic device 6 is transmitted to the refrigerant 8 via the metal part 71. The thinner the metal part 71 located between the electronic device 6 and the porous body 72, the easier it is to transmit the heat 11 from the electronic device 6 to the refrigerant 8. The pore diameter of the porous body 72 and the viscosity of the refrigerant 8 may be appropriately set so that the refrigerant 8 can be filled inside the porous body 72 by utilizing the capillary phenomenon and the refrigerant 8 does not leak outside the porous body 72. Further, as the material of the refrigerant 8, a liquid that vaporizes at a lower temperature such as ethanol (boiling point 80 ° C) other than pure water may be applied. By applying a liquid suitable for a desired temperature range, it is possible to suppress the temperature rise according to the desired temperature of the electronic device 6.

[0022] The aluminum alloy used for the metal part 71 in the present embodiment has a specific heat (J / (g·°C)) of 0.896 J / (g·°C) and a density (g / cm 3 ) of 2.7 g / cm 3 . The heat capacity per unit volume of the aluminum alloy (J / (cm 3 ·°C)) is 2.419 J / (cm 3 ·°C). The pure water used for the refrigerant 8 in the present embodiment has a specific heat (J / (g·°C)) of 4.217 J / (g·°C) and a density (g / cm 3 ) of 1 g / cm 3 . The heat capacity per unit volume of pure water (J / (cm 3 ·°C)) is 4.217 J / (cm 3 ·°C). Since the heat capacity per unit volume of pure water (J / (cm 3 ·°C)) is larger than the heat capacity per unit volume of the aluminum alloy (J / (cm 3 ·°C)), the heat capacity of the cooling plate 7 can be increased as compared with the case where the porous body 72 containing the refrigerant 8 is not formed inside the metal part 71. In addition, increasing the proportion of the refrigerant 8 in the cooling plate 7 compared to the proportion of the metal part 71 can increase the heat capacity of the cooling plate 7. Furthermore, when pure water is used as the refrigerant 8, the latent heat of vaporization from liquid to gas is about 2256 kJ / kg. Therefore, for example, when absorbing about 200 kJ of heat with the latent heat of vaporization, about 90 g of pure water is sufficient. This can contribute to the weight reduction of the flying body 1.

[0023] Next, the operating state of the cooling plate 7 will be described. FIG. 4 is a diagram for explaining the operating state of the cooling plate 7 shown in FIG. 3.

[0024] As shown in FIG. 4, the heat 11 generated in the electronic device 6 is transmitted to the refrigerant 8 through the metal part 71. At this time, since the temperature of the refrigerant 8 is higher in the part of the porous body 72 closer to the electronic device 6, the temperature of the second porous body 72b is higher than that of the first porous body 72a. When the temperature of the refrigerant 8 reaches the boiling point due to the heat transfer from the electronic device 6 to the refrigerant 8, the refrigerant 8 vaporizes and becomes vapor 50. The vapor 50 moves inside the second porous body 72b and is released from the discharge port 74 to the outside of the porous body 72. When the vapor 50 is released from the discharge port 74 to the outside of the porous body 72, the pressure inside the induction device 2 shown in FIG. 1 increases. When the pressure inside the induction device 2 becomes equal to or higher than the threshold value, the pressure regulating valve 5 opens a discharge port (not shown) and gas is discharged from the discharge port to the outside of the induction device 2.

[0025] On the other hand, as shown in FIG. 4, when the vaporized refrigerant 8 is released from the discharge port 74 to the outside of the porous body 72, the refrigerant 8 inside the first porous body 72a flows into the second porous body 72b by capillary action. The refrigerant 8 that reaches the second porous body 72b vaporizes and is released to the outside of the porous body 72. In this way, the refrigerant 8 inside the porous body 72 is released to the outside of the porous body 72 without circulating.

[0026] ***Explanation of the effects of Embodiment 1*** Next, the operational effects of the flying body 1 according to Embodiment 1 will be described.

[0027] In this embodiment, a refrigerant 8 is enclosed in a porous body 72 formed inside a metal part 71 that comes into contact with the electronic device 6 and having a pore diameter that decreases from the center to the outside, and a discharge port 74 for discharging the vaporized refrigerant 8 is formed. When the temperature of the refrigerant 8 reaches the boiling point due to heat transfer from the electronic device 6 to the refrigerant 8, the refrigerant 8 vaporizes. When the refrigerant 8 is pure water, the boiling point is 100°C. The guaranteed temperature of the electronic device 6 is, for example, 120°C. Therefore, the temperature of the refrigerant 8 reaches the boiling point before the temperature of the electronic device 6 reaches the guaranteed temperature. As a result, the amount of heat 11 that can be transferred to the cooling plate 7 can be increased, and the temperature rise of the electronic device 6 can be suppressed.

[0028] In this embodiment, by providing the porous body 72 having pores inside the metal part 7, the space volume ratio inside the metal part 7 becomes higher, and the weight of the structure can be further reduced. In addition, since the refrigerant 8 having a specific gravity smaller than that of the metal part 71 is contained inside the metal part 71, the weight of the cooling plate 7 can be reduced as compared with the case where the porous body 72 for containing the refrigerant 8 is not formed inside the metal part 71.

[0029] In this embodiment, the vaporized refrigerant 8 is discharged from the discharge port 74 to the outside of the porous body 72. At this time, the volume of the refrigerant 8 inside the porous body 72 gradually decreases, but due to capillary action, the liquid refrigerant 8 is sucked up from the first porous body 72a to the second porous body 72b, so that the refrigerant 8 always exists in the surface layer part of the porous body 72 close to the electronic device 6. Therefore, heat can be efficiently dissipated by the vaporization of the refrigerant 8.

[0030] In this embodiment, the refrigerant 8 inside the porous body 72 is discharged to the outside of the porous body 72 without circulating. As a result, a circulation device for circulating the cooling fluid becomes unnecessary, and the weight of the flying object 1 can be reduced.

[0031] In addition, as the vaporized refrigerant 8 is discharged from the discharge port 74 to the outside, the pressure inside the cooling plate 7, particularly near the second porous body 72b, decreases. As a result, the movement of the refrigerant 8 from the first porous body 72a to the second porous body 72b is promoted.

[0032] Furthermore, since the vaporized refrigerant 8 is discharged from the discharge port 74, even when the heat generation of the electronic device 6 is large, it is possible to suppress the inside of the cooling plate 7 from becoming high pressure due to the vaporized refrigerant 8, and prevent damage to the cooling plate 7.

[0033] In the present embodiment, since the second porous body 72b is provided outside the first porous body 72a, the electronic devices 6 can be arranged on both sides of the porous body 72. As a result, it is possible to achieve both weight reduction of the structure and the same heat dissipation performance as when realizing the same heat dissipation performance only on one side of the porous body.

[0034] In the present embodiment, since the second porous body 72b has a higher density than the first porous body 72a, the apparent thermal conductivity becomes higher than that of the first porous body 72a. By adjusting the pore diameters of the first porous body 72a and the second porous body 72b, the heat distribution inside the porous body 72 due to the heat 11 generated in the electronic device 6 can be optimized, and it is possible to achieve both heat dissipation performance and weight reduction of the structure.

[0035] In the present embodiment, when the pressure inside the guiding device 2 becomes equal to or higher than the threshold value as the vaporized refrigerant 8 is discharged from the discharge port 74 to the outside of the porous body 72, the pressure regulating valve 5 opens a discharge port (not shown). As a result, the vaporized refrigerant 8 is discharged from the discharge port to the outside of the guiding device 2, so that the pressure inside the guiding device 2 can be kept constant.

[0036] ***Description of the configuration of Embodiment 2*** FIG. 5 is a view showing the electronic device 6 and the cooling plate 7 of the projectile 1 according to Embodiment 2 of the present invention, and is a view corresponding to a cross-sectional view taken along line III-III shown in FIG. 2. In Embodiment 2, parts overlapping with those in Embodiment 1 described above are denoted by the same reference numerals and the description thereof is omitted.

[0037] The flying body 1 according to Embodiment 2 further includes a buffer tank 75, a porous membrane 76, and a safety valve 9. Inside the cooling plate 7, a hollow buffer tank 75 is provided between the inner wall surface where the discharge port 74 of the metal part 71 is formed and the porous body 72, and the space between the buffer tank 75 and the porous body 72 is separated by a porous membrane 76. The porous membrane 76 is a membrane that cannot permeate the liquid refrigerant 8 but can permeate the vaporized refrigerant 8.

[0038] The safety valve 9, which is a discharge control unit, is installed at the discharge port 74. The safety valve 9 opens the discharge port 74 when the pressure inside the cooling plate 7 becomes equal to or higher than the threshold value due to the vaporized refrigerant 8. The safety valve 9 is, for example, a valve body biased against a valve seat by an elastic force such as a spring to close the discharge port 74. When the internal pressure becomes equal to or higher than the threshold value and overcomes the elastic force, the valve body moves away from the valve seat, and the discharge port 74 opens.

[0039] In this embodiment, in the initial state, the pressure in the buffer tank 75 is below atmospheric pressure. When the electronic device 6 generates heat and the refrigerant 8 vaporizes, the vaporized refrigerant 8 moves to the buffer tank 75 by natural convection. When the gaseous refrigerant 8 accumulated in the buffer tank 75 reaches a certain amount or more, the pressure becomes equal to or higher than the threshold value, the discharge port 74 is opened, and the refrigerant is discharged to the outside of the cooling plate 7.

[0040] ***Explanation of the effects of Embodiment 2*** Also in this embodiment, similar to Embodiment 1, the vaporized refrigerant 8 is supplied to the vicinity of the metal part 71 by capillary action, and there is an effect of improving the heat dissipation performance of the electronic device 6. Further, if the vaporized refrigerant 8 remains as bubbles in the porous body 72, it may inhibit heat conduction and reduce the heat dissipation performance. By setting the pressure in the buffer tank 75 below atmospheric pressure, a pressure difference is generated between the porous body 72 and the buffer tank 75, natural convection occurs inside the cooling plate 7, and the vaporized refrigerant 8 can be efficiently moved to the buffer tank 75. Thereby, it is possible to prevent the vaporized refrigerant 8 from remaining as bubbles in the porous body 72 and inhibiting heat conduction.

[0041] The configurations shown in the above embodiments illustrate an example of the content of the present invention, and it is possible to combine them with other known technologies, and it is also possible to omit or change a part of the configuration without departing from the gist of the present invention.

Description of Reference Numerals

[0042] 1 Projectile, 2 Induction device, 3 Outer shell member, 4 Antenna, 5 Pressure regulating valve, 6 Electronic equipment, 7 Cooling plate, 8 Refrigerant, 9 Safety valve, 11 Heat, 71 Metal part, 72 Porous body, 72a First porous body, 72b Second porous body, 73 Inlet, 73a Cover, 74 Outlet, 75 Buffer tank, 76 Porous membrane.

Claims

1. A metal part that is thermally and mechanically connected to an electronic device, A porous body that is provided inside the metal part, has a plurality of communicating pores formed therein, and is made of metal, Comprising: The outer surface of the porous body is in contact with the inner wall surface of the metal part, Refrigerant is contained inside the porous body, The porous body includes a first porous body that constitutes a central portion, It has a hollow space inside with the same shape as the first porous body, is arranged to surround the first porous body, and has a second porous body with a smaller pore diameter than the first porous body, The metal part is formed with a discharge port capable of discharging the vaporized refrigerant to the outside of the porous body, and a cavity with a pressure inside lower than atmospheric pressure before the electronic device generates heat is provided between the inner wall surface of the metal part where the discharge port is formed and the porous body, A porous membrane is provided between the porous body and the cavity, A cooling plate.

2. A metal part that is thermally and mechanically connected to an electronic device, A porous body that is provided inside the metal part and has a plurality of communicating pores formed therein, Comprising: The porous body is composed of two types of porous bodies, a first porous body that constitutes a central portion and a second porous body with a smaller pore diameter than the first porous body, The second porous body is outside the first porous body, The outer surface of the porous body is in contact with the inner wall surface of the metal part, Refrigerant is contained inside the porous body, The metal part is formed with a discharge port capable of discharging the vaporized refrigerant to the outside of the porous body, and a cavity is provided between the inner wall surface where the discharge port is formed and the porous body, A porous membrane is provided between the porous body and the cavity, a cooling plate.

3. The cooling plate according to claim 1, wherein the porous membrane is a filter that allows only the refrigerant in a gaseous state to pass through without allowing the refrigerant in a liquid state to pass through.

4. The cooling plate according to claim 1, wherein a discharge control part for discharging the refrigerant is installed at the discharge port.

5. The cooling plate according to claim 4, wherein the discharge control part is a valve that opens when the pressure inside the cavity reaches a threshold value or more due to the vaporized refrigerant.

6. The cooling plate according to claim 1, wherein the metal part and the porous body are integrally formed by a die-casting method, a laser melting method, or a powder bed method.

7. The cooling plate according to claim 1, wherein the porous body has a lattice structure.

8. A metal part that is thermally and mechanically connected to an electronic device, A porous body provided inside the metal part and having a plurality of communicating pores formed therein, comprising, the outer surface of the porous body is in contact with the inner wall surface of the metal part, a refrigerant is contained inside the porous body, the porous body includes a first porous body constituting a central portion, a second porous body having a hollow space inside with the same shape as the first porous body, and disposed so as to enclose the first porous body including the first porous body in the hollow space, and having a smaller pore diameter than the first porous body, a discharge port capable of discharging the vaporized refrigerant to the outside of the porous body is formed in the metal part, and a cavity having an internal pressure of less than or equal to atmospheric pressure before the electronic device generates heat is provided between the inner wall surface of the metal part where the discharge port is formed and the porous body, a cooling plate provided with a porous membrane between the porous body and the cavity, an electronic device provided inside the flying object, a flying object comprising.

9. a metal part that is thermally and mechanically connected to an electronic device, a porous body provided inside the metal part and having a plurality of communicating pores formed therein, comprising, the outer surface of the porous body is in contact with the inner wall surface of the metal part, a refrigerant is contained inside the porous body, the porous body includes a first porous body constituting a central portion, a second porous body having a hollow space inside with the same shape as the first porous body, and disposed so as to enclose the first porous body including the first porous body in the hollow space, and having a smaller pore diameter than the first porous body, a discharge port capable of discharging the vaporized refrigerant to the outside of the porous body is formed in the metal part, and a cavity having an internal pressure of less than or equal to atmospheric pressure before the electronic device generates heat is provided between the inner wall surface of the metal part where the discharge port is formed and the porous body, a cooling plate provided with a porous membrane between the porous body and the cavity, an electronic device provided inside the flying object, a pressure regulating valve for regulating the internal pressure of the flying object, a flying object comprising.

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