JP2012037098A - Loop heat pipe, and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a loop heat pipe that facilitates installation of wicks overlapping in the radial direction.SOLUTION: In this loop heat pipe, an evaporator 101 includes: an evaporator body 103 for evaporating working fluid; a liquid reservoir part 111 for accumulating working fluid in a liquid phase in the inside; an outer periphery wick 129 arranged in the evaporator body 103 for impregnating the working fluid toward the outer periphery by generating capillary force; an inner periphery wick 139 existing from the inside of the liquid reservoir part 111 to the inside of the evaporator body 103, arranged in contact with the inner peripheral surface of the liquid reservoir part 111 and the inner peripheral surface of the outer periphery wick 129, impregnating the working fluid toward the outer periphery wick 129 by generating capillary force, and deformable at least in the radial direction; and a first spring 133 supporting the inner periphery wick 139 to be pressed against the inner peripheral surface of the outer periphery wick 129.

Description

  The present invention relates to a loop heat pipe and an electronic device.

  As the prior art described in the publication, in order to efficiently cool the heat-generating component regardless of the installation angle, it is provided inside the evaporation section, the condensation section, and the liquid return pipe, and has a wick that generates a capillary force. There is a loop heat pipe (Patent Document 1).

JP 2008-215702 A

In the loop heat pipe, the working fluid is evaporated and cooled by using latent heat when vaporized. This working fluid penetrates into the wick in the evaporation section, and is vaporized by receiving heat from the heat-generating component. Therefore, since the working fluid easily penetrates into the wick when the portion where the working fluid and the wick are in contact with each other is wide, liquid transportation is stabilized.
An object of the present invention is to provide a loop heat pipe in which wicks overlapping in the radial direction can be easily installed.

The invention described in claim 1 includes an evaporator 101 that absorbs heat from the outside and evaporates the working fluid from a liquid phase to a gas phase, and condenses the gas phase working fluid led from the evaporator to form a liquid phase. In the loop heat pipe 100 that circulates to the evaporator as a working fluid, the evaporator 101 transmits heat from the outside to the working fluid existing inside, and evaporates the working fluid from the liquid phase to the gas phase. 103 and a liquid reservoir 111 that is connected to an end portion of the evaporation unit and stores a liquid-phase working fluid therein, and is provided inside the evaporation unit 103, and generates a capillary force to bring the working fluid to the outer periphery. A first wick 129 that penetrates toward the inside of the liquid reservoir portion 111 and from the inside of the liquid reservoir portion 111 to the inside of the evaporation portion 103, and contacts the inner peripheral surface of the liquid reservoir portion 111 and the inner peripheral surface of the first wick 129. Established A second wick 139 that allows a working fluid to permeate toward the first wick 129 by generating a capillary force and is deformable at least in the radial direction; and the second wick on the inner peripheral surface of the first wick 129. The loop heat pipe is provided with a support member 133 that supports the 139 so as to press it.
The invention according to claim 2 further includes another support member 135 that supports the second wick 129 so as to press against the inner peripheral surface of the liquid reservoir 111. It is.
The invention according to claim 3 is the loop heat pipe according to claim 2, wherein a pitch in the axial direction of the support member 133 is smaller than a pitch in the axial direction of the other support member 135.
The invention according to claim 4 includes a housing, a heat generating component housed in the housing, and an evaporator 101 that absorbs heat from the heat generating component and evaporates the working fluid from a liquid phase to a gas phase. And an electronic device including a cooling element that condenses the vapor-phase working fluid led from the evaporator and circulates the liquid-phase working fluid to the evaporator as a liquid-phase working fluid. An evaporating unit 103 that transmits the working fluid from the liquid phase to the gas phase, and is connected to an end of the evaporating unit, and a liquid reservoir unit 111 that stores the working fluid in the liquid phase inside; A first wick 129 that is provided inside the evaporating unit and permeates the working fluid toward the outer periphery by generating a capillary force; and exists from the inside of the liquid reservoir 111 to the inside of the evaporating unit 103, and Inner circumference of the liquid reservoir 111 And a second wick 139 which is provided in contact with the inner peripheral surface of the first wick 129 and allows the working fluid to permeate the first wick 129 by generating a capillary force and which can be deformed at least in the radial direction. And a support member 133 for supporting the second wick 139 against the inner peripheral surface of the first wick 129.
In addition, the said code | symbol in this column is attached | subjected illustratively in the description of this invention, and this invention is not reduced by this code | symbol.

  According to the first aspect of the present invention, it is possible to provide a loop heat pipe in which it is easy to install a wick that overlaps in the radial direction as compared with the case where this configuration is not provided.

It is a schematic block diagram which shows the loop type heat pipe which concerns on this Embodiment. It is a schematic block diagram which shows the evaporator which concerns on this Embodiment. It is a schematic block diagram which shows the evaporator which concerns on other embodiment. It is explanatory drawing for demonstrating the other aspect of the liquid groove of an evaporator. It is explanatory drawing for demonstrating the alternative example of the liquid groove of an evaporator. It is a schematic block diagram which shows the evaporator which concerns on 2nd Embodiment. It is explanatory drawing for demonstrating the evaporator which concerns on another aspect.

<First Embodiment>
Hereinafter, this embodiment will be described in detail with reference to the accompanying drawings.
<Overall configuration>
First, the configuration of a loop heat pipe 100 to which the present exemplary embodiment is applied will be described with reference to FIG. Here, FIG. 1 is a schematic configuration diagram showing a loop heat pipe 100 according to the present embodiment.
A loop heat pipe 100 to which the present embodiment is applied includes, for example, an inside of an annular device so as to cool a heating element (for example, a CPU of a computer) provided inside an electronic device or the like without supplying power from the outside. And is configured to circulate the working fluid.

  More specifically, a loop heat pipe 100, which is an example of a cooling element, is vaporized by an evaporator 101 that evaporates the working fluid for cooling using latent heat when the working fluid is vaporized, and the evaporator 101. A condenser 107 that radiates and liquefies the working fluid. The loop heat pipe 100 includes a vapor line 105 that sends the working fluid vaporized by the evaporator 101 to the condenser 107, and a liquid pipe that sends the working fluid liquefied by the condenser 107 to the evaporator 101. (Liquid Line) 109. The working fluid is filled in the loop heat pipe 100 of the present invention. For example, water, alcohol, ammonia or the like is used as the working fluid.

<Configuration of the evaporator 101>
Next, with reference to FIG.1 and FIG.2, the structure of the evaporator 101 with which this Embodiment is applied is demonstrated. Here, FIG. 2 is a schematic configuration diagram showing the evaporator 101 according to the present embodiment, FIG. 2A shows a sectional view in the axial direction of the evaporator 101, and FIG. It is sectional drawing cut | disconnected by the II-II surface of Fig.2 (a).
The evaporator 101 is provided in an electronic device (not shown), and is connected to the evaporator main body 103 and an evaporator main body 103 provided to transmit heat from a heat generator (not shown) such as a CPU of the computer. And a liquid reservoir 111 for storing a liquid-phase working fluid. Further, the evaporator 101 includes a wick 119 that is inserted in contact with the inside of the evaporator main body 103 and the liquid reservoir 111. Further, the front end of the evaporator 101 is connected to the steam pipe 105, and the rear end of the evaporator 101 is connected to the liquid pipe 109.
In the present specification, the front end refers to the end on the side from which the working fluid flows out, and the rear end refers to the end on the side from which the working fluid flows in. For example, the front end of the evaporator 101 shown in FIG. 1 refers to the left end in the figure, and the rear end of the evaporator 101 refers to the right end in the figure.

The evaporator main body 103 which is an example of the evaporation section is made of a hollow tubular metal, and the front end is connected to the steam pipe 105. Further, the evaporator main body 103 is connected to the front end of the liquid reservoir 111 at the rear end. Here, the evaporator main body 103 and the liquid reservoir 111 may be integrally formed.
Further, a gap is formed between the inner peripheral surface of the evaporator main body 103 and a small-diameter portion 119a of the wick 119 described later in order to efficiently discharge the working fluid vaporized in the evaporator main body 103 to the steam pipe 105. The In the present embodiment, a steam groove 124 is provided on the inner peripheral surface of the evaporator main body 103 in order to form this gap. Specifically, a plurality of vapor grooves 124 are formed side by side along the axial direction of the evaporator body 103. Therefore, when observed on a plane intersecting the axial direction of the vapor main body 103, the vapor grooves 124 have an uneven shape formed alternately in the circumferential direction (see FIG. 2B).

  The liquid reservoir 111 is made of a hollow tubular metal, and has a front end connected to the rear end of the evaporator body 103 and a rear end connected to the liquid pipe 109. The liquid reservoir 111 has an inner diameter larger than the inner diameter of the evaporator main body 103, and has a space for storing a liquid-phase working fluid therein. The liquid reservoir 111 stores the working fluid flowing from the liquid pipe 109.

The wick 119 is a member made of a hollow tubular porous metal (porous metal). The wick 119 generates a capillary force in the working fluid and consequently moves the working fluid. The front end 119c of the wick 119 is closed, and the rear end 119d of the wick 119 is opened. The wick 119 of the present embodiment exists from the inside of the liquid reservoir 111 to the inside of the evaporator main body 103. The wick 119 is provided in contact with the inner peripheral surface of the liquid reservoir 111 and the inner peripheral surface of the evaporator main body 103.
Here, a portion of the wick 119 existing inside the evaporator main body 103 is referred to as a small diameter portion 119a. The small diameter portion 119a is provided continuously in the axial direction and is present in the liquid reservoir 111 and has a larger diameter than the small diameter portion 119a. For example, when the wick 119 is inserted into the evaporator main body 103 and the liquid reservoir 111, it can be inserted from the rear end side of the liquid reservoir 111.

Furthermore, the small diameter part 119a and the large diameter part 119b have the liquid groove 121 in each inner peripheral surface. A plurality of the liquid grooves 121 are provided side by side along the inner peripheral surface of the wick 119. Each liquid groove 121 exists in a direction that intersects the axial direction of the hollow tube. In this embodiment, the liquid groove 121 is a circular groove (see FIG. 4A described later). The liquid groove 121 is configured such that the working fluid is guided along the liquid groove 121 by surface tension, and the surface where the working fluid and the wick 119 are in contact with each other is increased. In other words, the liquid groove 121 is configured such that the working fluid rises from the liquid level of the working fluid along the liquid groove 121.
The dimension of the liquid groove 121 differs according to the physical property value of the working fluid, particularly the surface tension. For example, when water, alcohol, or ammonia is used as the working fluid, the width of the liquid groove 121 is preferably 0.1 mm to 2 mm because liquid transportation is improved. In addition, when water, alcohol, or ammonia is used as the working fluid, the depth of the liquid groove 121 is preferably 0.1 mm to 2 mm because liquid transportation is improved.
The effective pore diameter of the wick 119 is 0.1 to 20 μm. The wick 119 is not limited to a porous metal, and may be formed of a ceramic porous material, a resin porous material, a glass porous material, a porous fiber, or the like. The porosity of the wick 119 is 25% to 70%. When a material having low thermal conductivity is used as the wick 119, heat leakage from the evaporator main body 103 to the liquid reservoir 111 can be reduced. In the case of reducing heat leakage, for example, generally, a nonmetal is more preferable than a metal because of its low thermal conductivity.

<Operation of the evaporator 101>
Next, the operation in the loop heat pipe 100 will be described with reference to FIG. Heat generated in a heating element (not shown) is transmitted to the evaporator main body 103 of the evaporator 101 (see arrow C1). In the evaporator main body 103, the working fluid that has absorbed heat is vaporized, passes through the vapor pipe 105 (see arrow A1), and is sent to the condenser 107 (see arrow A2). The working fluid sent to the condenser 107 releases heat (see arrow C2) and liquefies. The liquefied working fluid passes through the liquid pipe 109 (see arrow A3) and is sent again to the evaporator 101 (see arrow A4).

Next, the operation in the evaporator 101 will be described with reference to FIG.
First, the liquid working fluid sent to the evaporator 101 is supplied to the liquid reservoir 111 and held in the liquid reservoir 111, and a part thereof directly flows into the evaporator main body 103. .

  Here, the working fluid that does not flow into the evaporator main body 103 and is held under the liquid reservoir 111 under gravity (downward in FIG. 2) enters the evaporator main body 103 via the wick 119. . Specifically, the working fluid enters the evaporator main body 103 through the wick 119 as follows. First, the working fluid retained in the liquid reservoir 111 penetrates into the large diameter portion 119b of the wick 119 provided in the liquid reservoir 111 (see arrow B1). Then, the working fluid penetrates into the small diameter portion 119a of the wick 119 provided continuously with the large diameter portion 119b, thereby entering the evaporator main body 103 (see arrow B2).

The working fluid that has directly flowed into the evaporator main body 103 from the liquid reservoir 111 penetrates into the small diameter portion 119 a of the wick 119 within the evaporator main body 103.
Then, in the small diameter portion 119a of the wick 119, the working fluid that has permeated from the evaporator main body 103 and the working fluid that has permeated into the evaporator main body 103 via the large diameter portion 119b are sent to the small diameter portion 119a. It penetrates toward the outer peripheral surface (see arrow B3).
The working fluid that has permeated toward the outer peripheral surface of the small-diameter portion 119a is heated and vaporized by the heat of the heating element and enters along the vapor groove 124 (see arrow B4). The gaseous working fluid flowing out of the steam groove 124 enters the steam pipe 105.

  Here, on the outer peripheral surface of the small-diameter portion 119a, as the vaporized working fluid moves to the vapor pipe 105, the liquid working fluid that has permeated the small-diameter portion 119a moves toward the outer peripheral surface of the small-diameter portion 119a. To do. The liquid working fluid that has permeated the outer peripheral surface is heated and moves to the steam pipe 105. In this way, the heat generated in the heating element is transported from the evaporator 101 to the condenser 107 while repeating the above cycle without interrupting the flow of the working fluid on the outer peripheral surface of the small diameter portion 119a.

Here, when the working fluid in the liquid reservoir 111 penetrates into the large-diameter portion 119b, the inside of the large-diameter portion 119b rises due to the surface tension of the working fluid (upward direction in FIG. 2). At this time, the presence of the liquid groove 121 formed on the inner peripheral surface of the large-diameter portion 119b allows the working fluid to penetrate more stably. That is, the working fluid rises along the liquid groove 121 due to the surface tension of the working fluid. Therefore, compared with the case where the liquid groove 121 does not exist, the area | region which a working fluid can infiltrate in the large diameter part 119b can be increased. In other words, as compared with the case where the liquid groove 121 is not present, a larger portion of the large diameter portion 119b can be utilized for the penetration of the working fluid.
As a result, the amount of working fluid entering the evaporator main body 103 by permeation can be increased. As a result, an amount of working fluid necessary for cooling can be stably supplied into the evaporator body 103.

For the same reason, there is a liquid groove 121 formed on the inner peripheral surface of the evaporator main body 103 when the working fluid directly flowing into the evaporator main body 103 from the liquid reservoir 111 penetrates into the small diameter portion 119a. By doing so, the working fluid is more stably permeated.
With the above configuration, when the electronic device including the loop heat pipe 100 is arranged, even if the liquid reservoir 111 is arranged below the evaporator main body 103 in a gravitational environment, the working fluid Liquid transportation is performed stably.

<Pressure loss>
The overall pressure loss ΔP _tot of the conventional loop heat pipe 100 is expressed by the relationship of the following formula (1).

Here, ΔP _groove , ΔP _vap , ΔP _con , ΔP _liq , ΔP _w are friction pressure losses when the fluid passes through the steam groove 124, the steam pipe 105, the condenser 107, the liquid pipe 109, and the wick 119, respectively. is there. ΔP _g is a static pressure loss due to gravity.
The operation of the loop heat pipe 100 is possible because the maximum capillary pressure that can be generated in the wick 119.

が式(1)より大きい場合である。
そして、本実施の形態においては、液溜め部１１１内のウィック１１９である大径部１１９ｂによる圧力損失が加わるため、全体の圧力損失は以下に示す式（３）の関係で表わされる。

Is greater than equation (1).
In the present embodiment, since the pressure loss due to the large diameter portion 119b which is the wick 119 in the liquid reservoir 111 is added, the overall pressure loss is expressed by the relationship of the following formula (3).

ここで、ΔＰ_２ｗは大径部１１９ｂから小径部１１９ａまで作動流体が輸送される際の摩擦圧力損失で、ΔＰ_２ｗの圧力損失増大分により，最大熱輸送能力が低下する。
そして、ΔＰ_２ｗは、以下に示す式（４）の関係で表わされる。

Here, ΔP _2w is a friction pressure loss when the working fluid is transported from the large-diameter portion 119b to the small-diameter portion 119a, and the maximum heat transport capacity decreases due to the increase in the pressure loss of ΔP _2w .
And (DELTA) _P2w is represented by the relationship of the formula (4) shown below.

ここで、ｖ_ｌ、ｍはそれぞれ作動流体の動粘性係数、質量流量である。また、Π_ｗ、Ａ_ｗ、Ｌ_ｗはそれぞれ大径部１１９ｂのガス浸透率、断面積、及び長さであり、Π_２ｗ、Ａ_２ｗ、Ｌ_２ｗは小径部１１９ａのガス浸透率、断面積、及び長さである。さらに、ガス浸透率は、以下に示す式（５）という実験式で表わされることが多い。

Here, v _l and m are the kinematic viscosity coefficient and the mass flow rate of the working fluid, respectively. Further, Π _w , A _w , and L _w are the gas permeability, cross-sectional area, and length of the large-diameter portion 119b, respectively, and Π _2w , A _2w , L _2w are the gas permeability, cross-sectional area of the small-diameter portion 119a, And length. Furthermore, the gas penetration rate is often expressed by an empirical formula (5) shown below.

ここで、ｄ_ｗはウィック１１９の細孔直径、Φ_ｗは空隙率である。
そして、本発明は、以下に示す式（６）が成立する範囲であることが好ましい。

Here, d _w is the pore diameter of wick 119, and Φ _w is the porosity.
And it is preferable that this invention is the range in which Formula (6) shown below is materialized.

<Alternative example>
Next, an alternative example of the present embodiment will be described with reference to FIGS. Here, FIG. 3 is a schematic configuration diagram showing an evaporator 101 according to another embodiment, and FIG. 4 is an explanatory diagram for explaining another aspect of the liquid groove 121 formed in the evaporator 101. 4A shows a circular liquid groove 121a, FIG. 4B shows a helical liquid groove 121b, and FIG. 4C shows an arc-shaped liquid groove 121c. 5A and 5B are explanatory views for explaining an alternative example of the liquid groove 121 of the evaporator 101. FIG. 5A is a mode using the spring 123, and FIG. 5B is a circle of FIG. 5A. 5C is an enlarged view in which the portion shown in FIG. 5 is enlarged, FIG. 5C shows an embodiment using the nonwoven fabric 125, and FIG. 5D shows a cross-sectional view cut along the VV plane in FIG. 5C.

First, as shown in FIG. 3, the wick 119 may be composed of two or more materials having different characteristics. For example, the small diameter part 119a and the large diameter part 119b may be formed of different materials. Specifically, the small diameter portion 119a may be formed of a porous metal, and the large diameter portion 119b may be formed of a porous resin. Or you may form the small diameter part 119a and the large diameter part 119b with the porous metal from which a manufacturing method differs, respectively.
By using materials having different characteristics, for example, the thermal conductivity of the large-diameter portion 119b can be made lower than the thermal conductivity of the small-diameter portion 119a. Thereby, it can reduce that heat transfers from the heat generating body which is not illustrated in the liquid reservoir part 111. FIG. As a result, the cooling efficiency of the loop heat pipe 100 is improved by reducing the operating temperature of the entire loop heat pipe 100.
Further, the effective hole diameter of the large diameter part 119b may be formed to be larger than the effective hole diameter of the small diameter part 119a. For example, the effective hole diameter of the small diameter part 119a is 0.1 to 10 μm, whereas the effective hole diameter of the large diameter part 119b is 1 to 20 μm. Preferably, the effective hole diameter of the small diameter part 119a is 5 to 10 μm, whereas the effective hole diameter of the large diameter part 119b is 10 to 20 μm. Here, the reason why the effective hole diameter of the large diameter part 119b may be larger than the effective hole diameter of the small diameter part 119a is, for example, as follows. That is, the large diameter portion 119b of the wick 119 permeates the working fluid from the large diameter portion 119b to the small diameter portion 119a as described above. On the other hand, the small diameter part 119a of the wick 119 permeates the working fluid toward the outer peripheral surface and vaporizes it by the heat of the heating element. Therefore, compared with the small diameter part 119a, the large diameter part 119b does not require a large capillary force. Furthermore, if a large capillary force is given to the large-diameter portion 119b as compared with the small-diameter portion 119a, the liquid supply may be hindered due to friction loss with the steam that flows oppositely.

Now, it has been described that the liquid groove 121 is formed with a plurality of circular liquid grooves 121 along the inner peripheral surface of the wick 119 in the axial direction (see 121a in FIG. 4A). Not. For example, as shown in FIG. 4B, a spiral liquid groove 121b formed in a spiral shape along the inner peripheral surface of the wick 119, or as shown in FIG. 4C, the inner periphery of the wick 119. An arc-shaped liquid groove 121c formed along the surface may be used.
In the case of the arc-shaped liquid groove 121c, it is desirable that the arc-shaped liquid groove 121c is distributed over the entire inner peripheral surface of the wick 119. As a result, the liquid transport can be further stabilized regardless of the direction in which the loop heat pipe 100 is installed. For example, in the example shown in FIG. 4C, the arc-shaped liquid grooves 121c are provided in different directions so that the cut portions of the arc-shaped liquid grooves 121c are not aligned in the axial direction.

Further, as shown in FIG. 5, the following configuration may be used as an alternative example of the liquid groove 121.
Specifically, as shown in FIG. 5A, the liquid groove 121 may be provided with a fine spring 123 along the inner peripheral surface of the wick 119. The spring 123 is disposed in contact with another one-turn portion 123b continuous with the one-turn portion 123a. The spring 123 is configured by, for example, forming a cylindrical column made of metal having a diameter of 0.3 mm to 1.5 mm into a coil shape.
The spring 123 acts as follows. First, the one winding portion 123 a of the spring 123 and the other adjacent one winding portion 123 b form an inner circumferential space 123 c on the inner circumferential side of the spring 123. Then, along the one-turn portion 123a and the other one-turn portion 123b along the inner circumferential space 123c, the working fluid rises due to surface tension, and the surface where the working fluid contacts the wick 119 increases. That is, the one winding portion 123a of the spring 123 and another adjacent one winding portion 123b act as an alternative to the liquid groove 121 described above. Furthermore, an outer peripheral space 123d formed by the one-turn portion 123a of the spring 123, another adjacent one-turn portion 123b, and the inner peripheral surface of the wick 119 also acts as an alternative to the liquid groove 121 described above. That is, the working fluid rises due to surface tension along the one-turn portion 123a and the other one-turn portion 123b along the outer peripheral space 123d, and the surface where the working fluid and the wick 119 come into contact increases.

  Furthermore, as an alternative example of the liquid groove 121, a non-woven fabric provided along the inner peripheral surface of the wick 119 may be used. When the working fluid permeates through the non-woven fabric provided along the inner peripheral surface, the portion of the wick 119 in contact with the inner peripheral surface increases. That is, the area where the working fluid can permeate can be increased in the large diameter portion 119b.

  Furthermore, as an alternative example of the liquid groove 121, as shown in FIGS. 5C and 5D, a nonwoven fabric provided from the outer periphery of the thin tube 131 provided coaxially with the wick 119 toward the inner periphery of the wick 119. 125 may be formed. When the working fluid permeates through the nonwoven fabric 125 provided in the diametrical direction, the working fluid comes into contact with the wick 119 in the area away from the liquid level of the working fluid in the small diameter portion 119a and the large diameter portion 119b. The area where the working fluid can permeate can be increased.

  Furthermore, a bayonet tube that exists from the rear end of the liquid reservoir 111 to the inside of the evaporator main body 103 and feeds the working fluid directly into the evaporator main body 103 may be provided. By providing the bayonet tube, the bayonet tube directly supplies the working fluid to the evaporator main body 103, so that the working fluid is surely present in the evaporator main body 103, so that the working fluid is circulated more stably. It becomes possible. In the embodiment shown in FIGS. 5B and 5C, the thin tube 131 may be a bayonet tube.

  In the above-described embodiment, it has been described that the vapor groove 124 is formed in the evaporator main body 103, but the present invention is not limited to this. For example, the steam groove 124 may be provided not on the inner periphery of the evaporator main body 103 but on the outer periphery of the wick 109. Alternatively, it may be provided on both the inner periphery of the evaporator main body 103 and the outer periphery of the wick 109.

  Moreover, in the above-mentioned embodiment, although demonstrated using the structure which the outer peripheral surface of the small diameter part 119a of the wick 119 and the inner peripheral surface of the evaporator main body 103 contact directly, it is not limited to this. For example, another wick configured as a separate member may be provided between the wick 119 and the evaporator main body 103. Specifically, the inner peripheral surface of another wick is provided in contact with the outer peripheral surface of the small diameter portion 119a, and the outer peripheral surface of the other wick is provided in contact with the inner peripheral surface of the evaporator main body 103. . That is, the structure which provides a double wick may be sufficient.

  By adopting each of the above-described configurations, the possibility that a liquid-phase working fluid is present in the small-diameter portion 119a can be increased, and the small-diameter portion 119a can be kept wet. Therefore, the start-up and operation of the loop heat pipe 100 are stabilized. This is the same in a microgravity environment, and the startup and operation of the loop heat pipe 100 are stabilized by adopting the above-described configurations.

<Second Embodiment>
<Configuration of the evaporator 101>
Now, there is the following embodiment as a configuration in which double wicks are provided. Hereinafter, the second embodiment will be described with reference to FIGS. 6 and 7.
Here, FIG. 6 is a schematic configuration diagram showing the evaporator 101 according to the second embodiment, and FIG. 6A is a cross-sectional view in the axial direction of the evaporator 101 according to the second embodiment. FIG. 6B is a sectional view in the axial direction of the evaporator 101 from which support members (133, 135) described later are removed. Moreover, FIG. 7 is explanatory drawing for demonstrating the evaporator 101 which concerns on another aspect, FIG. 7 (a) shows the alternative example of the outer periphery wick 129 mentioned later, FIG.7 (b) is support. An alternative example of members (133, 135) is shown.

First, the main difference between the embodiment shown in FIGS. 1 and 2 and the embodiment shown in FIGS. 6 and 7 will be described as follows.
In the embodiment shown in FIGS. 1 and 2, the wick 119 inserted in contact with the inner peripheral surfaces of the evaporator main body 103 and the liquid reservoir 111 has been described. On the other hand, the embodiment shown in FIGS. 6 and 7 has a configuration in which double wicks (see 129 and 139 in FIG. 6) are provided. Specifically, it has an outer peripheral wick 129 inserted in contact with the inside of the evaporator main body 103 and an inner peripheral wick 139 provided in contact with the inside of the outer peripheral wick 129. The inner wick 139 includes a first spring 133 and a second spring 135 that support the inner wick 139.

  Here, the outer peripheral wick 129 which is an example of the first wick is a hollow tubular porous metal. One end portion of the outer peripheral wick 129, that is, the front end 129c is closed, and the other end portion of the outer peripheral wick 129, that is, the rear end 129d is opened. The outer peripheral wick 129 exists inside the evaporator main body 103 and is provided in contact with the inner peripheral surface of the evaporator main body 103. In addition, the outer periphery wick 129 is comprised with the hard material so that it may be used with a normal heat pipe. The outer peripheral wick 129 in the present embodiment is formed by laminating porous fibers in a cylindrical shape. The effective pore diameter of this porous fiber is 0.1 to 10 μm. The porosity of this porous fiber is 25% to 70%.

An inner peripheral wick 139 as an example of the second wick is made of a hollow tubular porous resin and is formed as a soft and flexible member. Examples of the member of the inner peripheral wick 139 include a fabric, a nonwoven fabric, and a sheet-like member. Both end portions of the inner peripheral wick 139 (see 129c and 129d in FIG. 6) are open. The inner peripheral wick 139 exists from the inside of the liquid reservoir 111 to the inside of the evaporator main body 103 and is provided in contact with the inner peripheral surface of the liquid reservoir 111 and the inner peripheral surface of the outer peripheral wick 129.
Further, the inner peripheral wick 139 can be deformed in the radial direction. Specifically, the inner circumferential wick 139 can be enlarged or reduced in the diameter direction. In the present embodiment, the inner peripheral wick 139 can be reduced in the diameter direction of the inner peripheral wick 139. Here, for the reduction in the diameter direction, not only the reduction in the diameter direction while maintaining the shape in the circumferential direction (circular in this example) but also the change in the shape in the circumferential direction, for example, a part of It includes contracting in the diametrical direction by folding. The inner peripheral wick 139 in the present embodiment is formed by making porous fibers into a nonwoven fabric. Specifically, the inner peripheral wick 139 is formed by laminating porous fibers in a cylindrical shape. The effective pore diameter of this porous fiber is 0.1 to 10 μm or less. Further, the porosity of the inner peripheral wick 139 is 25% to 70%. If a material having low thermal conductivity is used as the inner peripheral wick 139, heat leakage from the evaporator main body 103 to the liquid reservoir 111 can be reduced. In the case of reducing heat leakage, for example, generally, a nonmetal is more preferable than a metal because of its low thermal conductivity.

  The first spring 133 which is an example of a support member is a coil spring-shaped member. The first spring 133 is made of, for example, metal or resin. The first spring 133 is arranged inside the evaporator main body 103 so as to sandwich the inner peripheral wick 139 between the inner peripheral surface of the outer peripheral wick 129. That is, the first spring 133 supports the inner circumferential wick 139 so as to press it against the inner circumferential surface of the outer circumferential wick 129. The first spring 133 is configured by, for example, forming a metal member having a wire diameter of 0.3 mm to 1.5 mm in a coil shape. And the distance of the continuous winding part of the 1st spring 133, ie, the pitch, becomes 0.3-5 mm, for example. Preferably, the pitch of the first springs 133 is about twice the wire diameter.

  The second spring 135, which is an example of another support member, is a coil spring-shaped member. The second spring 135 is made of, for example, metal or resin. The second spring 135 is disposed inside the liquid reservoir 111 so as to sandwich the inner peripheral wick 139 between the inner peripheral surface of the liquid reservoir 111. That is, the second spring 135 supports the inner peripheral wick 139 to be pressed against the inner peripheral surface of the liquid reservoir 111. The second spring 135 is configured by, for example, forming a metal member having a wire diameter of 0.3 mm to 1.5 mm into a coil shape. And the distance of the continuous winding part of the 2nd spring 135, ie, the pitch, becomes 3-15 mm, for example. Preferably, the pitch of the second springs 135 is about 10 times the wire diameter.

Here, comparing the first spring 133 and the second spring 135, first, the outer diameter of the coil of the first spring 133 is smaller than the outer diameter of the coil of the second spring 133.
Furthermore, the pitch of the first springs 133 is smaller than the pitch of the second springs 133. That is, the number of portions where the first spring 133 contacts the inner peripheral wick 139 per unit length in the axial direction is the number of portions where the second spring 135 contacts the inner peripheral wick 139 per unit length in the axial direction. Bigger than.
This configuration is for the following reason. First, in the portion of the evaporator main body 103 where the outer peripheral wick 129 and the inner peripheral wick 139 are in contact, the working fluid is permeated from the inner peripheral wick 139 to the outer peripheral wick 129 as described later. On the other hand, in the portion of the liquid reservoir 111 where the liquid reservoir 111 and the inner peripheral wick 139 are in contact, there is no wick on the outer peripheral side, so the working fluid is transferred from the inner peripheral wick 139 to the liquid reservoir 111. Infiltration is not performed.
Therefore, in the evaporator main body 103, the part which the outer periphery wick 129 and the inner periphery wick 139 contact needs to be contacting enough. On the other hand, inside the liquid reservoir 111, there may be a partial gap where the liquid reservoir 111 and the inner peripheral wick 139 come into contact. For this reason, the pitch of the second spring 135 is larger than that of the first spring 133.

<Operation of the evaporator 101>
The movement of the working fluid in the evaporator 101 shown in FIG. 6 is substantially the same as the movement of the working fluid in the evaporator 101 shown in FIG. That is, the working fluid is first supplied to the liquid reservoir 111 and retained in the liquid reservoir 111. The working fluid retained under the liquid reservoir 111 under gravity is sent directly to the evaporator main body 103 through the wick 119 in addition to flowing directly into the evaporator main body 103.

Here, the working fluid retained in the liquid reservoir 111 is permeated into the inner peripheral wick 139 provided in the liquid reservoir 111. Then, the ink is sent by penetrating the inner peripheral wick 139 from the portion provided in the liquid reservoir 111 toward the portion provided in the evaporator main body 103 (see arrow D1).
Now, the working fluid that has flowed directly into the evaporator main body 103 penetrates into a portion of the inner peripheral wick 139 provided in the evaporator main body 103 (see arrow D2).
The working fluid that has permeated from the evaporator main body 103 and the working fluid that has permeated through the portion provided in the liquid reservoir 111 of the inner peripheral wick 139 are continuous with the inner peripheral wick 139 in the diameter direction. It penetrates toward the provided outer peripheral wick 129 (see arrow D3). The working fluid that has permeated toward the outer peripheral surface of the outer peripheral wick 129 is heated and vaporized by the heat of the heating element, and is sent along the vapor groove 124 (see arrow D4).

<Alternative example>
Here, the outer peripheral wick 129 has been described as a hard configuration that maintains a certain shape, but is not limited thereto. As shown in FIG. 7A, for example, the outer peripheral wick 129 may be deformable in the radial direction in the same manner as the inner peripheral wick 139. The outer peripheral wick 129 is formed of a fabric-like or sheet-like member made of a hollow tubular porous resin. By adopting such a configuration, the outer wick 129 can be easily installed.
Further, when the outer peripheral wick 129 can be deformed in the radial direction, a constricted portion 141 can be provided in the evaporator 101 as shown in FIG. By providing this constricted portion 141, heat transfer from a heating element (not shown) into the liquid reservoir 111 can be reduced.
As shown in FIG. 7A, by providing a seal member 137 at the rear end of the outer peripheral wick 129, the vaporized working fluid existing in the steam groove 124 is prevented from moving into the liquid reservoir 111. To do. Furthermore, when the working fluid whose temperature has risen flows into the liquid reservoir 111, heat transfer into the liquid reservoir 111 can be reduced.

  Although the first spring 133 and the second spring 135 have been described as the members that support the inner wick 139 described above, the present invention is not limited to this. The first spring 133 and the second spring 135 may be members that support the inner peripheral wick 139 against the inner peripheral surfaces of the outer peripheral wick 129 and the liquid reservoir 111. For example, as shown in FIG. 7B, umbrella-shaped members (143, 145) may be used. The umbrella-shaped member 145 includes shaft portions 143a and 145a arranged coaxially with the inner peripheral wick 139, and a support portion extending radially outward from the shaft portion 145, that is, toward the inner peripheral surface of the inner peripheral wick 139. 143b, 145b. And this support part 143b, 145b is comprised so that it may go to the rear-end side of the inner periphery wick 139 as it goes to a radial direction outer side. Since the support portions 143b and 145b are configured to be directed toward the rear end side of the inner peripheral wick, the area where the support portions 143b and 145b support the inner peripheral wick 139 is increased, and the inner peripheral wick 139 is reliably secured. Can be supported. Note that the pitch between the support portions 145 b in the liquid reservoir 111 is larger than the pitch between the support portions 143 b in the evaporator main body 103.

Moreover, in the above-mentioned embodiment, although the 1st spring 133 and the 2nd spring 135 were demonstrated as a separate structure, it is not limited to this. For example, the first spring 133 and the second spring 135 may be configured as an integral unit.
Moreover, although the umbrella-bone-shaped members 143 and 145 have been described as separate structures, the present invention is not limited thereto, and may be configured as a single body.

  Further, in the embodiment shown in FIGS. 6 and 7, there is also provided a bayonet tube that exists from the rear end of the liquid reservoir 111 to the inside of the evaporator main body 103 and feeds the working fluid into the evaporator main body 103. May be.

  By adopting the above-described configurations, it is possible to increase the possibility that the liquid-phase working fluid is present in the outer peripheral wick 129 and maintain the wet state of the outer peripheral wick 129. Therefore, the start-up and operation of the loop heat pipe 100 are stabilized. This is the same in a microgravity environment, and the startup and operation of the loop heat pipe 100 are stabilized by adopting the above-described configurations.

DESCRIPTION OF SYMBOLS 100 ... Loop type heat pipe, 101 ... Evaporator, 105 ... Steam pipe, 107 ... Condenser, 109 ... Liquid tank, 119 ... Wick, 121 ... Liquid groove, 129 ... Outer peripheral wick, 139 ... Inner peripheral wick

Claims (4)

It has an evaporator that absorbs heat from the outside and evaporates the working fluid from the liquid phase to the gas phase, condenses the gas phase working fluid led from the evaporator, and returns to the evaporator as a liquid phase working fluid. In the loop heat pipe that
The evaporator is
An evaporating section for transferring heat from the outside to the working fluid existing inside, and evaporating the working fluid from the liquid phase to the gas phase;
A liquid reservoir connected to an end of the evaporating unit and storing a liquid-phase working fluid therein;
A first wick provided inside the evaporating section and allowing a working fluid to permeate toward the outer periphery by generating a capillary force;
It exists from the inside of the liquid reservoir part to the inside of the evaporation part, is provided in contact with the inner peripheral surface of the liquid reservoir part and the inner peripheral surface of the first wick, and generates a capillary force to generate a working fluid. A second wick that penetrates toward the first wick and is at least radially deformable;
A loop heat pipe, comprising: a support member that supports the second wick against the inner peripheral surface of the first wick.   The loop heat pipe according to claim 1, further comprising another support member that supports the second wick to be pressed against an inner peripheral surface of the liquid reservoir.   The loop heat pipe according to claim 2, wherein a pitch in the axial direction of the support member is smaller than a pitch in the axial direction of the other support member. A housing,
A heat generating component housed in the housing;
An evaporator that absorbs heat from the heat-generating component and evaporates the working fluid from the liquid phase to the gas phase and condenses the gas-phase working fluid led from the evaporator to evaporate the liquid as a liquid-phase working fluid. In an electronic device comprising a cooling element that circulates in the vessel,
The evaporator is
An evaporating section for transferring heat from the outside to the working fluid existing inside, and evaporating the working fluid from the liquid phase to the gas phase;
A liquid reservoir connected to an end of the evaporating unit and storing a liquid-phase working fluid therein;
A first wick provided inside the evaporating section and allowing a working fluid to permeate toward the outer periphery by generating a capillary force;
It exists from the inside of the liquid reservoir part to the inside of the evaporation part, is provided in contact with the inner peripheral surface of the liquid reservoir part and the inner peripheral surface of the first wick, and generates a capillary force to generate a working fluid. A second wick that penetrates toward the first wick and is at least radially deformable;
An electronic device comprising: a support member that supports the second wick against the inner peripheral surface of the first wick.

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