JPH07297333A - Apparatus and method for latent heat cooling - Google Patents

Abstract

PURPOSE:To keep the temperature of a heat sink constant regardless of the change in ambient temperature. CONSTITUTION:A heat sink 1, wherein a heating element is attached to one surface, is cooled with the latent heat of evaporation of refrigerant 5 in a latent heat cooling apparatus. In this apparatus, the heat sink 1 is vertically provided with respect to the ground. A refrigerant evaporating panel 3 is provided in parallel with the other surface of the heat sink through a space. In the refrigerant evaporating panel 3, porous metal sheets 32 are fixed at both surfaces of an absorbing sheet 31 comprising porous material. Displacement mechanism 4, which changes the space between the refrigerant evaporating panel 3 and the heat sink 1 in response to the temperature change, is provided in the vicinities of both ends of the heat sink l. A refrigerant tank 6, which contains the refrigerant 5 wherein the lower end of the refrigerant evaporating panel 3 is dipped, is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device which utilizes latent heat to remove heat generated from a semiconductor such as an electronic device.

[0002]

2. Description of the Related Art Conventionally, a heat sink is attached to an electronic device or the like having a built-in semiconductor element as a heat source to cool the heat generated from the semiconductor. In particular, in order to enhance the cooling capacity of the heat sink, the heat sink is made of a porous absorbent material, and the heat sink is brought into contact with a liquid coolant made of an organic compound such as water, alcohol, or acetone to intermittently or continuously It is disclosed that a refrigerant liquid is supplied to and vaporized by a blower, and cooling air is blown to a heat sink by a blower in order to promote vaporization, and heat of the heat sink is taken by the heat of evaporation to cool the heat sink. 58-56495). Further, in order to continuously supply the refrigerant liquid, the heat sink is made of a porous metal or ceramics, or a fibrous or knitted organic compound is used so that the refrigerant liquid permeates into the heat sink by capillarity. What has been done is disclosed (for example, JP-A-3-41754).

[0003]

However, the conventional technique has a problem that the power consumption is large because a blower for generating cooling air for promoting vaporization is required. Also, when cooling by natural convection, the cooling air only flows along the surface of the heat sink,
There is a drawback that the temperature of the heat sink changes due to the influence of the change of the ambient temperature, the temperature of the semiconductor element cooled by the heat sink changes, and the operation of the semiconductor element becomes unstable. SUMMARY OF THE INVENTION It is an object of the present invention to provide a latent heat cooling device that improves the cooling effect by a cooling device that uses natural convection without power consumption and that keeps the temperature of a heat sink constant regardless of changes in ambient temperature. It is what

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention relates to a latent heat cooling device for cooling a heat sink having a heating element attached to one surface thereof by latent heat of vaporization of a refrigerant, in which the heat sink is perpendicular to the ground. The heat sink provided, a refrigerant evaporation panel in which a porous metal sheet is fixed to both surfaces of an absorption sheet made of a porous material, and a space provided in parallel with the other surface of the heat sink with a gap, and near both ends of the heat sink. And a displacement mechanism for changing a gap between the refrigerant evaporation panel and the heat sink according to a temperature change, and a refrigerant tank for immersing a lower end of the refrigerant evaporation panel in a refrigerant. Further, in a latent heat cooling device for cooling a heat sink having a heating element attached to one surface by latent heat of vaporization of a refrigerant, the heat sink provided perpendicularly to the ground is fixed in contact with the other surface of the heat sink. , And a refrigerant evaporation panel in which porous metal sheets are fixed on both sides of an absorption sheet made of a porous material, a metallic cooling plate provided in parallel with the refrigerant evaporation panel via a gap, and near both ends of the heat sink And a displacement mechanism for changing the gap between the refrigerant evaporation panel and the cooling plate according to temperature changes, and a refrigerant tank for immersing the lower end of the refrigerant evaporation panel in the refrigerant.

[0005]

According to the above means, when the ambient temperature is high, the displacement mechanism reduces the gap between the heat sink and the refrigerant evaporation panel, or increases the gap between the refrigerant evaporation panel and the cooling plate to prevent the heat sink and the ambient air. Increase the heat transfer coefficient between and. As a result, the cooling effect of the heat sink is increased, and the difference between the temperature of the heat sink and the ambient temperature is reduced. When the ambient temperature is low, the void is operated in the opposite direction to lower the thermal conductivity. As a result, the cooling effect is reduced, increasing the difference between the heat sink temperature and the ambient temperature. In this way, the cooling effect of the heat sink is enhanced when the ambient temperature is high, and the cooling effect of the heat sink is reduced when the ambient temperature is low, so that the temperature of the heat sink is always kept constant.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a side sectional view showing a first embodiment of the present invention, and FIG. 2 is a front view thereof. In the figure, a power module 2 containing a semiconductor element is fixed to one surface of a flat plate-shaped heat sink 1 extending vertically to the ground, and a refrigerant evaporation panel 3 is arranged in parallel on the other surface with a gap G therebetween. Then
The upper and lower ends of the refrigerant evaporation panel 3 are supported by a displacement mechanism 4 that displaces in accordance with changes in temperature. The refrigerant evaporation panel 3 has a mesh-like or porous metal sheet 32 fixed to both surfaces of an absorbent sheet 31 made of a porous material such as paper or cloth. The lower end of the heat sink 1 is provided with a coolant tank 6 for containing a coolant 5 such as water, and the lower end of the absorption sheet 31 is immersed in the coolant 5. The displacement mechanism 4 has one end fixed to the heat sink 1 and the other end pin-coupled to the refrigerant evaporation panel 3 so as to be rotatable.

The principle of the present invention will now be described. When the temperature of the heat sink 1 rises, heat is transferred to the refrigerant evaporation panel 3 and the refrigerant 5 contained in the absorption sheet 31 evaporates. At that time, heat is taken from the air around the heat sink 1 as latent heat of evaporation, so that the heat sink 1 is cooled. By the way, the relationship between the size of the gap G between the flat plate-shaped heat sink 1 extending in the direction perpendicular to the ground and the refrigerant evaporation panel 3 provided in parallel with it, and the size of the heat transfer coefficient between the heat sink 1 and the ambient air is: As shown in FIG. 3, the gap G is 0 to 5 m.
The heat transfer coefficient changes by 50 to 30 (W / m ² ° C) in the range of about m, and the heat transfer coefficient decreases as the gap G increases. Here, the temperature T _D of the semiconductor element is the ambient temperature T
₀ , the difference ΔT between the heat sink temperature T _H and the ambient temperature T _0
1, the difference [Delta] T ₂ between the temperature T _D and the temperature T _H of the heat sink of the semiconductor device, because determined by _{T D = T 0 + ΔT 1} + ΔT 2, as shown in FIG. 4, a constant temperature T _D of the semiconductor element to, in response to changes in ambient temperature T ₀ [Delta] T
You can see that you can control ₁ . Therefore, with the above configuration, when the ambient temperature is high, as shown in FIG.
As shown in, the temperature of the bimetal 41 rises and deforms into a substantially linear shape, and the refrigerant evaporation panel 3 is brought closer to the heat sink 1 to reduce the gap G and increase the heat transfer coefficient. As a result, the cooling effect is increased, and the difference ΔT ₁ between the temperature of the heat sink 1 and the ambient temperature is reduced. When the ambient temperature is low,
As shown in FIG. 1 (b), the temperature of the bimetal 41 is lowered and curved, and the refrigerant evaporation panel 3 is separated from the heat sink 1 to increase the gap G and reduce the heat transfer coefficient. as a result,
The cooling effect decreases, and the difference ΔT ₁ between the temperature of the heat sink 1 and the ambient temperature increases. In this way, the cooling effect of the heat sink is enhanced when the ambient temperature is high, and the cooling effect of the heat sink is reduced when the ambient temperature is low, so that the temperature of the heat sink is always kept constant.

FIG. 5 is a side sectional view showing a second embodiment. In the figure, a power module 2 containing a semiconductor element is fixed to one surface of a flat plate-shaped heat sink 1 extending in the vertical direction to the ground, and a refrigerant evaporation panel 3 is closely arranged on the other surface of the heat sink 1. A cooling plate 7 made of metal such as aluminum is arranged in parallel with the evaporation panel 3 with a gap therebetween. The upper and lower ends of the cooling plate 7 are supported by a displacement mechanism 4 that displaces in response to changes in temperature. The configurations of the refrigerant evaporation panel 3, the displacement mechanism 4, and the refrigerant tank 6 are almost the same as those in the first embodiment. In this case, the relationship between the size of the gap G between the refrigerant evaporation panel 3 and the cooling plate 7 and the size of the heat transfer coefficient from the heat sink 1 to the ambient air is that the gap G is 0 to 0 as shown in FIG. Within about 5 mm, the heat transfer coefficient changes by 50 to 30 (W / m ² ° C), and the heat transfer coefficient increases as the gap G increases. Here, the temperature T _D of the semiconductor element, the ambient temperature T _0, the difference [Delta] T ₁ between the temperature T _H and the ambient temperature T ₀ of the heat sink, the difference [Delta] T ₂ between the temperature T _D and the temperature T _H of the heat sink of the semiconductor element , T _D = T ₀ + ΔT ₁ + ΔT ₂ Therefore, as shown in FIG. 7, in order to keep the temperature T _{D of the} semiconductor element constant, ΔT ₁ should be controlled according to the change in ambient temperature T _0. I know it's good. Therefore, according to the above configuration, when the ambient temperature is high, as shown in FIG.
The temperature of the bimetal 41 rises and becomes substantially curved, and the cooling plate 7 is separated from the refrigerant evaporation panel 3 to enlarge the gap G and increase the heat transfer coefficient. As a result, the cooling effect is increased, and the difference ΔT ₁ between the temperature of the heat sink 1 and the ambient temperature is reduced. When the ambient temperature is low, as shown in FIG. 5A, the temperature of the bimetal 41 decreases and the bimetal 41 deforms linearly,
The cooling plate 7 is brought closer to the refrigerant evaporation panel 3 to reduce the gap G and reduce the heat transfer coefficient. As a result, the cooling effect is reduced and the difference ΔT ₁ between the temperature of the heat sink 1 and the ambient temperature is increased. Thus, as in the first embodiment, when the ambient temperature is high, the cooling effect of the heat sink is enhanced, and when the ambient temperature is low, the cooling effect of the heat sink is reduced,
Keep the heat sink temperature constant at all times. The displacement mechanism 4 is configured by stacking a plurality of shape memory materials having different operating temperatures in series as shown in FIG. 8A in the first embodiment and FIG. 8B in the second embodiment. The displacement member 42 has one end fixed to the heat sink 1 and the other end fixed to the refrigerant evaporation panel 3 or the cooling plate 7, and the position of the refrigerant evaporation panel 3 or the cooling plate 7 is moved according to a change in ambient temperature. However, the size of the gap G may be controlled.

As described above, according to the present invention, an air gap is provided between the heat sink and the refrigerant evaporation panel or between the cooling plate parallel to the refrigerant evaporation panel, and the size of the air gap is set to the ambient temperature. The temperature of the heat sink is constantly kept constant by changing the temperature of the semiconductor element so that the cooling effect using natural convection without power consumption improves the cooling effect and stabilizes the characteristics. There is an effect that it is possible to provide a latent heat cooling device that keeps the temperature constant.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first embodiment of the present invention.

FIG. 2 is a front view of FIG.

FIG. 3 is an explanatory diagram showing a relationship between a void and a heat transfer coefficient according to the first embodiment of this invention.

FIG. 4 is an explanatory diagram showing a relationship between voids and temperature in the first embodiment of the present invention.

FIG. 5 is a side sectional view showing a second embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a relationship between a void and a heat transfer coefficient according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a relationship between voids and temperature according to the second embodiment of the present invention.

FIG. 8 is a side sectional view showing a main part of another embodiment of the displacement mechanism of the present invention.

[Explanation of symbols]

1 Heat Sink, 2 Power Module, 3 Refrigerant Evaporation Panel, 31 Absorption Sheet, 32 Metal Sheet, 4
Displacement mechanism, 41 Bimetal, 42 Displacement member, 5 Refrigerant, 6, Refrigerant tank, 7 Cooling plate

Claims (4)

[Claims] 1. A latent heat cooling device for cooling a heat sink having a heating element attached to one surface thereof by latent heat of evaporation of a refrigerant, wherein the heat sink provided perpendicular to the ground and the other surface of the heat sink are parallel to each other. A refrigerant evaporation panel having a porous metal sheet fixed to both surfaces of an absorption sheet made of a porous material and provided through a gap, and provided near both ends of the heat sink, and between the refrigerant evaporation panel and the heat sink. A latent heat cooling device comprising: a displacement mechanism that changes a gap according to a temperature change; and a coolant tank that stores a coolant in which a lower end of the coolant evaporation panel is immersed. 2. A latent heat cooling device for cooling a heat sink having a heating element attached to one surface thereof with latent heat of evaporation of a refrigerant, wherein the heat sink provided perpendicular to the ground is brought into contact with the other surface of the heat sink. Fixed and
And a refrigerant evaporation panel having porous metal sheets fixed on both sides of an absorbent sheet made of a porous material, a metallic cooling plate provided with a gap in parallel with the refrigerant evaporation panel, and near both ends of the heat sink. And a displacement mechanism for changing a gap between the refrigerant evaporation panel and the cooling plate according to a temperature change, and a refrigerant tank for immersing a lower end of the refrigerant evaporation panel in a refrigerant. Latent heat cooling device. 3. The latent heat cooling method for cooling the heat sink by the latent heat cooling device according to claim 1, wherein a gap between the heat sink and the refrigerant evaporation panel is changed according to a change in ambient temperature, and the heat sink of the heat sink is changed. A latent heat cooling method characterized by maintaining a constant temperature. 4. The latent heat cooling method for cooling the heat sink by the latent heat cooling device according to claim 2, wherein a gap between the cooling plate and the refrigerant evaporation panel is changed according to a change in ambient temperature, and the heat sink is provided. A method for cooling latent heat, characterized in that the temperature of is kept constant.