JP2011190996A - Loop type heat pipe, wick, and information processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a loop type heat pipe (LHP) enabling mass production in a form with stable cooling performance (no large variations). <P>SOLUTION: The LHP is equipped with an evaporator which includes a case 12 and a wick 13. The wick 13 made of an elastic material having a hollow cylindrical shape having an outer peripheral face where a plurality of steam discharge grooves 13a extended to the length direction are provided and an inner peripheral face where a plurality of inner grooves 13b extended to the length direction are provided, and having a diameter before storage within the case 12 larger than the inner diameter of the case 12, is press fitted into the case 12 having a columnar inner space. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a loop heat pipe, a wick used as a component of the loop heat pipe, and an information processing apparatus including the loop heat pipe.

  As a device for cooling a heating element such as a CPU, a heat transport device called a loop heat pipe is used.

  As shown in FIG. 9, the loop heat pipe (hereinafter also referred to as LHP) is configured by connecting an evaporator 41 and a condenser 43 in a loop by a vapor pipe 42 and a liquid pipe 44. Is a device in which a predetermined amount of working fluid (a working fluid in a liquid state: not shown) is sealed.

  The steam pipe 42 is a conduit for supplying the working fluid vaporized by the evaporator 41 (details will be described later) to the condenser 43. The condenser 43 is a unit that condenses the vaporized working fluid supplied by the steam pipe 42 by heat radiation. As this condenser 43, the thing which attached the some radiation fin to the pipe | tube (not shown) normally bent so that the meander was used is used. The liquid pipe 44 is a conduit for supplying (returning) the working fluid liquefied by the condenser 43 to the condenser 41.

  The evaporator 41 is a unit that vaporizes the working fluid present therein with heat from the heating element [absorbs heat from the heating element by causing a phase change in the working fluid]. Note that the LHP normally contains the evaporator 41 in a heat transfer block 45 made of metal (usually copper) in order to improve the thermal contact between the evaporator 41 and the heating element. ing.

  Various types of evaporators 41 having different specific configurations have been developed. For example, as the evaporator 41, as shown in FIGS. 10 and 11, a bottomed cylindrical resin wick 52 having a plurality of vapor discharge grooves 52 a provided on the outer peripheral surface is used as a cylindrical evaporator. What was accommodated in the case 51 has been developed. Of these drawings, FIG. 10 is a cross-sectional view of the evaporator 41 and the heat transfer block 45 (cross-sectional view taken along the line BB ′ in FIG. 11). FIG. 11 shows the evaporator 41 and the heat transfer block. FIG. 11 is a transverse sectional view of the block 45 (AA ′ arrow sectional view in FIG. 10).

JP-A-2005-106313 JP 2000-146471 A Japanese Patent Laid-Open No. 10-246583

  Now, in order to obtain LHP with high cooling performance, it is necessary to efficiently transfer heat from the heating element to the wick 52 in the case 51 via the case 51 (and the heat transfer block 45).

Therefore, when manufacturing the evaporator 41, the outer surface (outer peripheral surface) of the wick 52 should be in contact with the inner surface of the case 51 by using the wick 52 having an outer diameter larger than the inner diameter of the case 51. . However, when the outer diameter of the wick 52 is excessively large, the pores near the outer peripheral surface of the wick 52 are crushed as shown schematically in FIG. 12, and as a result, the flow of the hydraulic fluid is inhibited. Become. If the flow of the hydraulic fluid is obstructed, the hydraulic fluid is less likely to evaporate in the evaporator 41 (the performance of the evaporator 41 is reduced), so that the wick 52 used as a constituent element of the evaporator 41 is eventually obtained. The outer diameter has an appropriate value determined from the inner diameter of the case 51 and the like.

  However, when manufacturing the resin wick 52 by mold molding, a considerable manufacturing error occurs. Specifically, the inner diameter of the case 51 is 14 mm, a mold molded product made of PTFE (polytetrafluoroethylene) is used as the wick 52, and an appropriate value of the outer diameter of the wick 52 (hereinafter referred to as a design value). ) Is 14.2 mm.

  In this case, since the dimensional accuracy (manufacturing error) of the outer diameter of the wick 52 is normally about ± 0.2 mm, the wick 52 having an outer diameter in the range of 14.0 mm to 14.4 mm is manufactured. become. Here, when the pressing pressure of the outer surface of the wick 52 on the inner surface of the case 41 in the evaporator 41 manufactured using each wick 52 of each outer diameter is calculated from the size of the wick 52 and various physical property values, When the wick 52 having a diameter of 14.4 mm is used, it can be seen that the evaporator 41 in which the outer surface of the wick 52 is pressed against the inner surface of the case 41 with a pressure of 14400 kPa is obtained. Therefore, in this case, since the pores near the outer peripheral surface of the wick 51 are crushed (see FIG. 12), the evaporator 41 having poor performance is obtained.

  In addition, when the wick 52 having an outer diameter of 14.0 mm is used (when the outer diameter of the wick 52 and the inner diameter of the case 51 match), the pressing pressure is naturally 0 kPa. Therefore, in this case, since the outer surface of the wick 52 is not in good contact with the inner surface of the case 51, the evaporator 41 having poor performance is obtained.

  Thus, the said structure employ | adopted for the evaporator 41 has a problem that the evaporator 41 with the stable performance cannot be mass-produced. This problem occurs if the constituent material of the wick 52 has elasticity, although there is a difference in degree.

  Therefore, the problem of the disclosed technology is that it is possible to mass-produce a loop heat pipe using a wick made of an elastic material and having a stable cooling performance. An object of the present invention is to provide a loop heat pipe that is not above) and a wick capable of realizing such a loop heat pipe.

  Another object of the disclosed technique is to provide an information processing apparatus that can be mass-produced in a form in which the cooling performance of a CPU or the like is stable.

  In order to solve the above problems, a loop heat pipe according to an aspect of the disclosed technology includes an evaporator that vaporizes a working fluid in a liquid state with heat from a heating element, and condenses the working fluid in a gaseous state by heat dissipation. The condenser is connected in a loop with a steam pipe for supplying the working fluid from the evaporator to the condenser and a liquid pipe for supplying the working fluid from the condenser to the evaporator, A case having a space, and a wick made of an elastic material housed in the case and extending in the length direction with an outer peripheral surface provided with a plurality of steam discharge grooves extending in the length direction An evaporator having a hollow cylindrical shape having an inner peripheral surface provided with a plurality of inner grooves and a wick whose diameter before being accommodated in the case is larger than the inner diameter of the internal space of the case is used. It has a configuration.

In order to solve the above-described problem, according to one aspect of the disclosed technique, the wick is a member made of a material having elasticity, and an outer periphery provided with a plurality of steam discharge grooves extending in the length direction. The member has a hollow cylindrical shape including a surface and an inner peripheral surface provided with a plurality of inner grooves extending in the length direction.

  In order to solve the above problems, an information processing apparatus according to an aspect of the disclosed technique includes an electronic component to be cooled and a loop heat pipe as described above during operation. A configuration in which an evaporator of a loop heat pipe is arranged at a position where the electronic component functions as a heating element is employed.

  According to the disclosed technology, a loop heat pipe capable of mass-producing a stable cooling performance (practically having no extremely poor cooling performance is actually manufactured) and a wick capable of realizing such a loop heat pipe In addition, it is possible to provide an information processing apparatus that can be mass-produced with a stable cooling performance such as a CPU.

1 is a schematic configuration diagram of an information processing apparatus according to an embodiment. The cross-sectional view of the evaporator (and heat transfer block) with which the loop heat pipe which concerns on an Example is provided. The longitudinal cross-sectional view of the evaporator (and heat transfer block) in a loop type heat pipe. Explanatory drawing of the shape in the free state of the wick used for the evaporator. Explanatory drawing of the manufacturing procedure of an evaporator. The figure for demonstrating the effect of the structure employ | adopted as the evaporator. Explanatory drawing of the state of the pore of the wick in an evaporator. Explanatory drawing of the shape in the evaporator of a wick whose outer diameter is smaller than a design value. Configuration diagram of existing LHP The longitudinal cross-sectional view of the existing evaporator (and heat-transfer block). The cross-sectional view of the existing evaporator (and heat transfer block). Explanatory drawing of the state of the pore of the wick in the existing evaporator.

  Hereinafter, an example of an information processing apparatus, a loop heat pipe and a wick developed by the present inventors (hereinafter referred to as an information processing apparatus 1, a loop heat pipe 10 and a wick 13 according to an embodiment) will be described with reference to the drawings. Details will be described with reference to FIG.

FIG. 1 shows a schematic configuration of an information processing apparatus 1 according to the embodiment. As illustrated, the information processing apparatus 1 according to the embodiment is a so-called notebook PC (Personal Computer), and includes a printed circuit board 30, a loop heat pipe 10, and the like.

  The printed circuit board 30 is a unit in which the CPU 31 and the like are attached to a printed wiring board. The CPU 31 mounted on the printed circuit board 30 of the information processing apparatus 1 according to the present embodiment has a heat generation amount of about 60W.

  A loop heat pipe 10 (hereinafter also referred to as LHP 10) according to the embodiment is a heat transport device including an evaporator 11, a heat transfer block 18, a steam pipe 15, a condenser 16, and a liquid pipe 17.

  The evaporator 11 vaporizes the working fluid in the liquid state present in the evaporator 11 with heat from the heating element (CPU 31 in this embodiment) [from the heating element by causing a phase change in the working fluid. A cylindrical unit for absorbing heat. Details of the evaporator 11 will be described later.

  The heat transfer block 18 is a member made of a highly heat conductive material (copper in this embodiment). The heat transfer block 18 has a wide hole on one side surface (two parallel side surfaces) of an isosceles trapezoidal member in which a through-hole having substantially the same size as the evaporator 11 is provided perpendicular to the bottom surface (trapezoidal surface). It has a shape (see FIG. 3) in which a flat plate-like member is attached to the side surface. The LHP 10 has the evaporator 11 accommodated in the through-hole of the heat transfer block 18 and has an overall shape (positional relationship of each part) so that the heat transfer block 18 can be positioned on the CPU 31. Has been established. In the information processing apparatus 1, the heat transfer block 18 of the LHP 10 is attached to the upper surface of the CPU 31 via thermal grease.

  The steam pipe 15 is a conduit for supplying the working fluid vaporized by the evaporator 11 to the condenser 16. The condenser 16 is a unit for condensing the working fluid in a gaseous state supplied by the steam pipe 15 by heat radiation. The condenser 16 has a configuration in which a plurality of radiating fins 16a are attached to a tube bent so as to meander (not shown; hereinafter referred to as a condensation tube). In the information processing apparatus 1, a cooling fan 33 (in this embodiment, a fan having a diameter of 90 mm and driven by 12 V) for air-cooling the condenser 16 is provided.

  The liquid pipe 17 is a conduit for supplying the working fluid condensed (liquefied) by the condenser 16 to the evaporator 11. The LHP 10 according to the present embodiment uses copper pipes having an outer diameter of 4 mm, an inner diameter of 3 mm, and a length of about 300 mm as the liquid pipe 17 and the steam pipe 15 respectively, and the condenser pipe has an outer diameter of 4 mm, an inner diameter of 3 mm, and a length. A copper pipe with a length of about 400 mm is used.

  Hereinafter, the configuration of the evaporator 11 included in the LHP 10 will be described in detail with reference to FIGS. 2 to 5. Of these drawings, FIG. 2 is a longitudinal sectional view of the evaporator 11 and the heat transfer block 18 (cross-sectional view taken along the line BB ′ in FIG. 3). FIG. 3 shows the evaporator 11 and the heat transfer block. FIG. 3 is a transverse sectional view of the block 18 (AA ′ arrow sectional view in FIG. 2). FIG. 4 is an explanatory diagram of the shape of the wick 13 in a free state (a state where no force is applied to each part), and FIG. 5 is an explanatory diagram of a manufacturing procedure of the evaporator 11.

  As shown in FIG. 2, the evaporator 11 includes a case 12, a wick 13, and a seal member 14.

  The case 12 is a hollow cylindrical member that forms the outer shell of the evaporator 11. The case 12 includes a case member 12a in which the wick 13 is accommodated and a case member 12b in which the seal member 14 is accommodated. The LHP 10 according to the embodiment uses a copper member having an inner space diameter of about 14 mm and a length of about 50 mm as the case 12.

  The seal member 14 has a diameter at a central portion thereof for defining a liquid storage chamber (a space on the left side of the seal member 14 in FIG. 2) for temporarily storing the working fluid in the evaporator 11. It is a circular flat plate member provided with a through hole of about 6 mm.

  The wick 13 is a member having a shape shown in FIGS. 2 to 4 made of a material having a capillary action.

That is, the wick 13 is a member having a bottomed cylindrical shape (see FIG. 2) with one end opened and the other end closed. However, a portion of the outer peripheral surface of the wick 13 other than the vicinity of the opening end (the left end in FIG. 2) is a steam discharge groove 13a (hereinafter simply referred to as a groove 13a) extending in the length direction of the wick 13. ) Are provided. In addition, a plurality of inner grooves 13 b (hereinafter simply referred to as grooves 13 b) extending in the length direction of the wick 13 are provided on the inner peripheral surface of the wick 13.

  The wick 13 (see FIG. 3) is a member in which the grooves 13a and 13b are alternately provided along the peripheral wall at equal intervals, and the grooves 13a and 13b are referred to as “depth of the groove 13a”. This is a member provided with a V-shaped groove having a shape of “the depth of the groove 13b> the thickness of the peripheral wall> the thickness of the peripheral wall”.

  Further, the wick 13 is designed and manufactured as a member (see FIG. 4) that becomes larger than the inner diameter of the case 12 even when the outer diameter in the free state becomes a small size due to a manufacturing error. Yes. Further, each of the wicks 13 is configured so that the opening width of each groove 13b becomes substantially “0” when the outer diameter thereof is matched with the inner diameter of the case 12 by compression in the radial direction (see FIG. 3). The shape of the groove 13b is determined (designed).

  The wick 13 actually used as a component of the LHP 10 (evaporator 11) according to the example is a PTFE member manufactured using a mold and having the following specifications.

・ Pore diameter: about 10μm
-Porosity: about 40%
・ Outer diameter (free state): about 17mm
・ Inner diameter (free state): about 9mm
・ Total length: 40mm
-Shape of the steam discharge groove 13a (free state):
Number and arrangement of isosceles triangles / steam discharge grooves 13a having a base length (opening width on the outer peripheral surface side) of about 2 mm and a side length of about 2.5 mm:
12 at regular intervals and the shape of the inner groove 13b (free state):
Number and arrangement of isosceles triangles and inner grooves 13b having a base length of about 0.8 mm and a side length of about 2.2 mm:
12 at regular intervals

  And the evaporator 11 is manufactured by the procedure typically shown in FIG. 5 using the wick 13 of the said shape (specification).

  That is, when the evaporator 11 is manufactured (see FIGS. 5A and 5B), first, the wick 13 whose outer diameter is larger than the inner diameter of the case 12 (case member 12a) is compressed in the radial direction (contracted). An operation of releasing the compression is performed after inserting into the case member 12 a of the case 12.

  Since the outer diameter in the free state of the wick 13 is larger than the inner diameter of the case 12, when the wick 13 is inserted into the case member 12a and then released from compression, each part of the wick 13 spreads outward (FIG. 5). (See (C).) Therefore, when the above work is completed, the entire outer peripheral surface of the wick 13 (part other than the steam discharge groove 13a) is in good contact (with a certain pressing pressure) with the inner surface of the case member 12a. Will be formed. In addition, since the wick 13 has the above-described shape (details will be described later), the wick 13 accommodated in the case 12 does not have a collapsed pore on the outer peripheral surface side, and each inner groove 13b is substantially free of crushing. It will take a closed state.

  The evaporator 11 included in the LHP 10 according to the embodiment includes an operation of fixing the seal member 14 to the case member 12b (or the case member 12a) and an operation of fixing the case member 12b to the case member 12a after the above operation. (See FIG. 5D). The LHP 10 according to the embodiment is manufactured by combining the evaporator 11 thus manufactured with the vaporizer 16 and the like and then enclosing the working fluid (ethanol in this embodiment) in a known procedure. It has become.

  As described above, the LHP 10 (evaporator 11) according to the embodiment includes the groove 13a and the groove 13b having a shape in which “the depth of the groove 13a + the depth of the groove 13b> the thickness of the peripheral wall” is established. Are hollow cylinders alternately provided along the peripheral wall (cylindrical wall), and a wick 13 ”whose diameter in a free state is larger than the inner diameter of the case 12 is used.

  In other words, the LHP 10 (evaporator 11) has a smaller size (outer diameter and inner diameter) if the opening width of the inner groove 13b becomes narrower (if the portion sandwiched between the grooves 13a and 13b is inclined). The wick 13 is used.

  The force required for narrowing the opening width of the inner groove 13b of the wick 13 (inclining the portion sandwiched between the groove 13a and the groove 13b) depends on each part in the wick 13 (bulk PTFE). ) Less than the force required for compression. Specifically, the wick 13 in the present embodiment has the shape shown in FIG. 6A, but various forces are required to compress the wick 13 by 0.05 mm in the circumferential direction. When calculated based on the physical property value, it is about 50 kPa. On the other hand, as a force required for compressing each part of the wick 13, a force required to compress the wick having the shape shown in FIG. 6B (that is, a wick having a conventional configuration) by 0.05 mm in the circumferential direction is calculated. About 1800 kPa.

  Thus, the force required to narrow the opening width of the inner groove 13b of the wick 13 is smaller than the force required to compress each part of the wick 13. Therefore, the wick 13 having the above-described shape is such that when the diameter is reduced, the opening width of the inner groove 13b becomes narrow, in other words, the diameter can be reduced without applying a particularly large external force. become.

  When the wick 52 is used, the evaporator 41 (see FIG. 12) in which the pores on the outer peripheral surface side of the wick 52 are crushed is obtained in the circumferential direction on the inner peripheral surface side of the wick 52. An extremely large force is required for compression [the force in the radial direction on the outer peripheral surface side of the wick 52 is larger than the force required to reduce the outer diameter by compression in the circumferential direction on the inner peripheral surface side of the wick 52. This is because the force required to reduce the outer diameter by compression is smaller. Therefore, if the diameter of the wick can be reduced without applying a large external force, it is possible to prevent the pores on the outer peripheral surface side of the wick from collapsing due to housing in the case.

  Since the wick 13 can be reduced in diameter without applying a particularly large external force as described above, the size of the actually manufactured wick 13 is designed in the above configuration adopted for the evaporator 11. Even if there is a slight deviation from the value, “the pores on the outer peripheral surface side of the wick 13 are not crushed (the flow of the hydraulic fluid is not hindered by the crushing of the pores), and the entire outer peripheral surface of the wick 13 is Thus, the evaporator 11 ″ that is in good contact with the inner surface of the case 12 can be manufactured.

In addition, although it thinks that it is already clear from the size of each part of the above-mentioned wick 13, by using the wick 13 and the case 12 having the above-described shape, the evaporator 11 in which all the pores in the wick 13 are not collapsed is realized. It's not possible. Specifically, for example, when the wick 13 having an outer diameter equal to the design value (17 mm) is accommodated in the case 12, the wick 13 is formed in the grooves 13a and 13b as schematically shown in FIG. Only the pores located in the vicinity of the tip end will be crushed. Moreover, also when the wick 13 whose outer diameter is smaller than the design value is accommodated in the case 12, the wick 13 takes the same state. In this case, as shown in FIG. 8, the state of the wick 13 is a state in which the inner groove 13b is not completely closed.

  As described above, in the evaporator 11 in which the wick 13 whose outer diameter is equal to or smaller than the design value is used, only the pores located near the tips of the grooves 13a and 13b in the wick 13 are crushed. It will be a thing. However, the flow of the hydraulic fluid is greatly hindered when all the pores on the path through which the hydraulic fluid can pass are collapsed (see FIG. 12). Even if the hole is crushed, the flow of the hydraulic fluid is not greatly hindered. Therefore, as long as the wick 13 has the above shape, the evaporator 11 in which the flow of the working fluid is not hindered by the collapse of the pores can be realized (manufactured) even if the outer diameter is equal to or less than the design value. .

  Further, when the wick 13 having an outer diameter larger than the design value is accommodated in the case 12, not only the pores located in the vicinity of the tips of the grooves 13a and 13b, but also each of the other fine elements in the wick 13. The hole will also be crushed. However, in the wick 13 having the above shape, each pore is deformed on average. Therefore, as long as the wick 13 has the above shape, the evaporator 11 in which the flow of the working fluid is not hindered by the collapse of the pores can be realized even if the outer diameter exceeds the design value.

  Furthermore, the configuration employed in the evaporator 11 is such that the pressure applied to the inner surface of the case 12 of the wick 13 does not change greatly even if the outer diameter of the wick 13 varies due to manufacturing errors.

  Specifically, as already described, when a PTFE wick is manufactured by molding, a manufacturing error of about ± 0.2 mm occurs. Therefore, when the wick 13 having an outer diameter of 17 mm is manufactured by die molding, the wick 13 having an outer diameter in the range of 16.8 mm to 17.2 mm is manufactured. When the pressing pressure of the 16.8 mm wick 13 against the inner surface of the case 12 is calculated from various physical property values, the pressing pressure is 2600 kPa. Moreover, the pressing pressure against the inner surface of the case 12 of the wick 13 having the maximum outer diameter (17.2 mm) is 3400 kPa.

  This pressing pressure range (2600 to 3400 kPa) is extremely narrower than the pressing pressure range (0 to 14400 kPa) of the wick 52 against the inner surface of the case 51 described above. Therefore, it can be said that the configuration employed in the evaporator 11 does not greatly change the pressure applied to the inner surface of the case 12 of the wick 13 even if the outer diameter of the wick 13 varies due to manufacturing errors. .

  And the LHP 10 says, “Even if the size of the wick 13 changes slightly due to manufacturing errors, the pressure applied to the inner surface of the case 12 of the wick 13 does not change significantly, and the pores are crushed so as to hinder the flow of hydraulic fluid. Evaporator 11 ”that does not occur is provided. Therefore, it can be said that the LHP 10 according to the present embodiment can be mass-produced with stable cooling performance (practically those with extremely poor cooling performance are not manufactured).

  Further, the LHP 10 has higher cooling performance than the LHP provided with the evaporator 41 (see FIGS. 10 and 11).

This is because when the wick 52 is used, the wick 52 having a smaller outer diameter than the inner diameter of the case 51 (the wick 52 that cannot actually be used as a component of the evaporator 41) is not manufactured. 52 must be made larger. When the outer diameter of the wick 52 is large, the pores on the outer peripheral surface side of the wick 52 in the evaporator 41 are crushed (see FIG. 12). Therefore, the cooling performance of the LHP provided with the evaporator 41 is deteriorated as much as the flow of the working fluid in the evaporator 41 is obstructed by the collapse of the pores of the wick 52.

  On the other hand, as described above, the evaporator 11 has a configuration in which the cooling performance is not deteriorated due to the collapse of the pores even if the size of the wick 13 is slightly deviated from the design value. Since the evaporator 11 is used for the LHP 10, it can be said that the LHP 10 has higher cooling performance than the LHP for which the evaporator 41 is used.

  In developing the information processing apparatus 1, an information processing apparatus (hereinafter referred to as a conventional configuration apparatus) in which the LHP 10 of the information processing apparatus 1 is replaced with an LHP provided with an evaporator 41, and the information processing apparatus 1 are Experiments are performed to measure the temperature of the CPU 31 in each device by operating in an environment of 25 ° C. As a result of the experiment, it has been confirmed that the temperature of the CPU 31 in the conventional configuration apparatus rises to 70 ° C., but the temperature of the CPU 31 in the information processing apparatus 1 rises only to 60 ° C. Therefore, it can be said that the LHP 10 according to the example has a cooling performance improved by about 22% [= 100-100 × (60-25) / (70-25)] over the LHP of the conventional configuration. You can also.

<Modification>
Various modifications can be made to the LHP 10, the information processing apparatus 1, and the wick 13 described above. For example, the shape of each inner groove 13b of the wick 13 is determined so that the opening width of each inner groove 13b becomes substantially “0” when the wick 13 is accommodated in the case 12. This is to prevent a large amount of heat from being applied to the working fluid in the wick 13. The heat leak is a phenomenon in which heat is transmitted from the case 12 through the wick 13 to the working fluid in the wick 13.

  However, even if the inner grooves 13b are not completely closed, it is practical that a large amount of heat is added to the hydraulic fluid in the wick 13 by heat leak as long as the opening width of the inner grooves 13b is reduced to a certain extent. It can be prevented at a sufficiently high level. Therefore, the wick 13 can be deformed to have an inner groove 13b that does not completely close when housed in the case 12.

  Further, the wick 13 can be modified to include the groove 13a and the groove 13b having a shape that satisfies the relationship of “depth of the groove 13a + depth of the groove 13b ≦ thickness of the peripheral wall”. However, although the wick 13 deformed in such a manner is easier to reduce the diameter than the wick 52, the wick 13 cannot be easily reduced in diameter like the wick 13 having the above-described shape. For this reason, the wick 13 does not need to have the size of each part as described above, but includes the groove 13a and the groove 13b having a shape in which “depth of the groove 13a + depth of the groove 13b> thickness of the peripheral wall” is established. It is desirable to keep it.

  The shape of each groove 13a, 13b of the wick 13 may be a groove having a shape that is not V-shaped. However, the cooling performance of the LHP 10 is not particularly improved by using non-V-shaped grooves as the grooves 13a and 13b, and the inner groove 13b does not have a space inside when closed. It is desirable to be a thing. Therefore, it is desirable that at least the shape of the inner groove 13b be V-shaped (a complete V-shape or a shape similar to the V-shape).

Further, the wick 13 can be deformed into a shape that does not have a “bottom” (right end portion in FIG. 2) (a shape that is attached to a member that functions as the “bottom” of the wick 13).

  Moreover, although LHP10 which concerns on an Example was what used the condenser 16 provided with the radiation fin 16a as a component, LHP10 is the condenser 16 (thing which is not equipped with the radiation fin 16a etc.) of another structure. It can also be transformed into a component. The information processing apparatus 1 described above is a so-called notebook PC. However, the information processing apparatus 1 can be modified to a tower type PC or an information processing apparatus (such as a copy machine) other than a computer.

DESCRIPTION OF SYMBOLS 1 Information processing apparatus 10 Loop type heat pipe 11, 41 Evaporator 12a, 12b Case member 12, 51 Case 13, 52 Wick 13a Steam discharge groove 13b Inner groove 14 Seal member 15, 42 Steam pipe 16, 43 Condenser 16a Heat radiation Fin 17, 44 Liquid pipe 18, 45 Heat transfer block 30 Printed circuit board 31 CPU
33 Cooling fan

Claims (7)

An evaporator that vaporizes the working fluid in a liquid state by heat from the heating element;
A condenser for condensing the working fluid in a gaseous state by heat radiation;
A vapor pipe for supplying the working fluid from the evaporator to the condenser;
A liquid pipe for supplying the working fluid from the condenser to the evaporator,
The evaporator is
A case having a cylindrical inner space;
A hollow cylinder which is accommodated in the case and has an outer peripheral surface provided with a plurality of steam discharge grooves extending in the length direction and an inner peripheral surface provided with a plurality of inner grooves extending in the length direction. A wick having a diameter before being accommodated in the case is larger than an inner diameter of the internal space of the case;
A loop heat pipe characterized by comprising: Each inner groove of the wick is provided at a portion of the inner peripheral surface where the steam discharge groove is not provided on the outer peripheral surface side, and the depth of the steam discharge groove is reduced from the thickness of the peripheral wall of the wick. The loop-type heat pipe according to claim 1, wherein the loop-shaped heat pipe is a V-shaped groove having a depth exceeding the above value. The loop heat pipe according to claim 1 or 2, wherein each inner groove of the wick has a shape in which an opening width becomes "0" when the wick is accommodated in the case. The loop type heat pipe according to any one of claims 1 to 3, wherein the wick has a shape in which one end is closed. The loop type heat pipe according to any one of claims 1 to 4, wherein the wick is a die-molded member made of a porous resin. A hollow cylindrical shape having an outer peripheral surface provided with a plurality of steam discharge grooves extending in the length direction and an inner peripheral surface provided with a plurality of inner grooves extending in the length direction. And wick. During its operation, electronic components to be cooled,
An evaporator that vaporizes the working fluid in a liquid state with heat from the electronic component, a condenser that condenses the working fluid in a gas state by heat dissipation, and introduces the working fluid from the evaporator into the condenser. As a case where the working fluid from the steam pipe and the condenser is connected in a loop by a liquid pipe for introducing into the evaporator, the evaporator has a case having a cylindrical inner space, and a wick accommodated in the case. A hollow cylindrical shape having an outer peripheral surface provided with a plurality of steam discharge grooves extending in the length direction and an inner peripheral surface provided with a plurality of inner grooves extending in the length direction, A loop heat pipe in which an evaporator including a wick having a diameter before being accommodated in the case is larger than an inner diameter of the internal space of the case;
An information processing apparatus comprising:

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