Manufacturing method for evaporator

Abstract

To provide a manufacturing method for an evaporator capable of stably mounting a heating element.SOLUTION: A manufacturing method for an evaporator in the present disclosure comprises: preparing a flat wick having a first space formed therein into which liquid-phase working fluid can flow; executing a process to cover one side of an outer periphery of the wick and increase a surface area of an outer surface of at least one of a plurality of flat cover pieces having a plurality of grooves on an inner surface; arranging the plurality of cover pieces to cover an outer periphery of the wick so that a surface having the grooves is in contact with an outer surface of the wick; and joining the plurality of cover pieces arranged around the outer periphery of the wick.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing an evaporator. [Background technology]

[0002] A loop heat pipe is known as a device for cooling an object, which transfers heat by utilizing a gas-liquid phase change, changing a fluid from liquid to gas in a high-temperature area and from gas to liquid in a low-temperature area (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-181469 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there are more and more opportunities to use electronic components that pass large currents, such as high-brightness LEDs and power modules. Circuit modules that include such electronic components generate a large amount of heat, so they need to be cooled efficiently. For these reasons, the use of loop-type heat pipes such as those described in Patent Document 1 above has been considered.

[0005] When using a loop heat pipe to cool a heat generating body such as a circuit module, it is necessary to attach the heat generating body to the evaporator of the loop heat pipe. It is preferable to attach the evaporator and the heat generating body with as few other members as possible between them in order to maintain high thermal conductivity. In light of this, when attempting to directly attach the heat generating body to the evaporator, it is assumed that an adhesive or the like will be used for attachment. However, since the cover that covers the surface of the evaporator is often made of stainless steel (SUS) or the like, which has a smooth surface, it is difficult to stably bond the heat generating body with an adhesive or the like, and it is also difficult to obtain a high bonding strength.

[0006] In view of the above-mentioned problems, the present disclosure has an object to provide a manufacturing method for an evaporator that enables stable attachment of a heating element. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a manufacturing method for an evaporator according to a first aspect of the present disclosure includes the steps of preparing a flat wick having a first space formed therein into which a liquid-phase working fluid can flow; covering one side of the outer periphery of the wick and performing a process to increase the surface area of ​​the outer surface of at least one of a plurality of flat cover pieces having a plurality of groove-like grooves on their inner surface; arranging the plurality of cover pieces to cover the outer periphery of the wick so that the surface having the grooves abuts the outer surface of the wick; and joining the plurality of cover pieces arranged around the outer periphery of the wick.

[0008] In such a method for manufacturing an evaporator, by subjecting the cover piece to a treatment for increasing its surface area, it becomes possible to attach the heating element to one surface of the evaporator with high bonding strength and stability.

[0009] A method for manufacturing an evaporator according to a second aspect of the present disclosure is the method for manufacturing an evaporator according to the first aspect of the present disclosure, wherein the treatment for increasing the surface area includes at least one of a roughening treatment, a chemical conversion treatment, and a plating treatment.

[0010] In such a method for manufacturing an evaporator, the surface area of ​​the cover piece can be increased in a simple manner.

[0011] The method for manufacturing an evaporator according to a third aspect of the present disclosure is a method for manufacturing an evaporator according to the first or second aspect of the present disclosure, further comprising a step of performing stress relief annealing on the cover piece after performing a step of performing a treatment to increase the surface area of ​​the outer surface.

[0012] In such a method for manufacturing an evaporator, since distortion of the cover pieces can be removed before the cover pieces are joined, poor joining between the cover pieces can be suppressed. Effect of the Invention

[0013] According to the manufacturing method of the evaporator of the present disclosure, the heating element can be stably attached. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing an example of a structure of a loop heat pipe including an evaporator manufactured by a manufacturing method for an evaporator according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Diagram 3] FIG. 3 is a perspective view showing an example of a cover piece of the evaporator shown in FIG. 2. [Figure 4] 4 is a flowchart illustrating an example of a method for manufacturing an evaporator according to an embodiment of the present disclosure. [Diagram 5] 13A to 13C are diagrams showing a schematic diagram of a process for placing a cover piece on the outer surface of a wick. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the manufacturing method of the laminate according to the present disclosure will be described with reference to the attached drawings. Note that the drawings shown in the attached drawings are schematic, and the thickness and width of each part, the ratio of each part, etc. may differ from those actually implemented. In addition, the same or similar symbols are used for the same or corresponding parts in the drawings, and duplicated explanations are omitted. Furthermore, some symbols may be omitted in the drawings for the purpose of making the drawings easier to see.

[0016] FIG. 1 is a schematic diagram showing an example of the structure of a loop heat pipe including an evaporator manufactured by the manufacturing method of an evaporator according to an embodiment of the present disclosure. An evaporator 2 manufactured by the manufacturing method of an evaporator according to the present embodiment can function as a part of the loop heat pipe 1 shown in FIG. 1. As shown in FIG. 1, the loop heat pipe 1 may include at least an evaporator 2, a condenser 3, a vapor pipe 4, and a liquid pipe 5. Furthermore, a working fluid F may be sealed inside these components at a constant pressure. For example, water, ammonia, acetone, alcohol, fluorocarbon, glycol ethers, naphthalene, etc. can be used as the working fluid F.

[0017] The evaporator 2 functions as a heat receiving member that receives heat generated by a heating element 6 (see FIG. 2). A liquid pipe 5 is connected to the upstream side of the evaporator 2, and a steam pipe 4 is connected to the downstream side. The specific configuration of the evaporator 2 will be described in detail later.

[0018] The condenser 3 functions as a heat dissipation member that dissipates heat of the working fluid F to the outside. The condenser 3 is disposed at a position away from the evaporator 2, and can cool the working fluid F, which is mainly in a gas phase and flows in from the upstream side, to change it into a liquid phase working fluid. The specific structure of the condenser 3 is not particularly limited, and for example, the condenser 3 can have a plurality of heat dissipation fins installed around a pipe through which the working fluid F flows. The cooling method of the condenser 3 can be an air-cooling type or a water-cooling type, and a fan or a pump (not shown) can be provided around the condenser 3 depending on the cooling method.

[0019] The steam pipe 4 is a pipe for transporting the working fluid F flowing out from the evaporator 2 to the condenser 3. In this regard, one end of the steam pipe 4 may be connected to the downstream end of the evaporator 2, and the other end may be connected to the upstream end of the condenser 3. The working fluid F transported through the steam pipe 4 may be substantially in a gas phase.

[0020] The liquid pipe 5 is a pipe for transporting the working fluid F flowing out from the condenser 3 to the evaporator 2. In this regard, one end of the liquid pipe 5 may be connected to the downstream end of the condenser 3, and the other end may be connected to the upstream end of the evaporator 2. The working fluid F transported through the liquid pipe 5 may be in a substantially liquid phase. In addition, a tank (not shown) capable of storing the liquid-phase working fluid F may be provided between the downstream end of the liquid pipe 5 and the evaporator 2.

[0021] Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. As shown in Figs. 1 and 2, the evaporator 2 manufactured by the manufacturing method for an evaporator according to the present embodiment includes at least a flat wick 20 having a first space 21 formed therein into which the working fluid F can flow, and a cover 30 covering the outer periphery of the wick 20. In the following description, the X direction shown in Fig. 2 may be defined as the width direction (or left-right direction) of the evaporator 2, the Y direction as the length direction, and the Z direction as the height direction.

[0022] The wick 20 is configured as a flat rectangular parallelepiped having a predetermined thickness, and may be configured as a porous body made of ceramics or the like, as shown in Fig. 2. Inside the wick 20, one or more first spaces 21 may be formed into which the working fluid F, mainly in liquid phase, supplied from the liquid pipe 5 flows. The first space 21 in this embodiment is a cylindrical space extending along the length of the wick 20 as shown in Fig. 2, and a plurality of first spaces 21 (six in Fig. 2) are illustrated as being arranged at predetermined intervals along the left-right direction of the wick 20.

[0023] 1, a liquid pipe connecting member 41 provided at the end of the liquid pipe 5 may be attached to the upstream end of the wick 20 in the flow direction of the working fluid F. Also, a steam pipe connecting member 42 provided at the end of the steam pipe 4 may be attached to the downstream end of the wick 20 in the flow direction of the working fluid F.

[0024] The liquid-phase working fluid F supplied through the liquid pipe connecting member 41 flows into the first space 21. The liquid-phase working fluid F that flows into the wick 20 is carried to the outer surface of the wick 20 by the capillary structure of the wick 20, and is evaporated by the heat of the heating element 6. The evaporated working fluid F flows into the vapor pipe 4 through the groove 32 and the vapor pipe connecting member 42 provided in the cover 30. Note that a metal may be disposed on a part of the outer periphery of the wick 20, for example, to improve thermal conductivity.

[0025] The cover 30 covers the outer periphery of the wick 20, more specifically, the four sides of the left and right end faces and the height end faces of the wick 20. The cover 30 can be made of stainless steel (SUS), copper, or an alloy thereof. In this embodiment, the cover 30 is made of stainless steel. The cover 30 includes four flat cover pieces 31A, 31B, 31C, and 31D. Hereinafter, of the four cover pieces 31A, 31B, 31C, and 31D, the one covering the top surface of the wick 20 will be referred to as the first cover piece 31A, and similarly, the one covering the bottom surface of the wick 20 will be referred to as the second cover piece 31B, and the ones covering the left and right side surfaces of the wick 20 will be referred to as the third and fourth cover pieces 31C, 31D. When these cover pieces are collectively referred to, they will simply be referred to as cover pieces 31.

[0026] The dimensions of the cover piece 31 may be adjusted to match the dimensions of the wick 20. Specifically, the total length of the cover piece 31 in the length direction may be substantially the same as the total length of the wick 20 in the length direction. In addition, the total length of the first and second cover pieces 31A and 31B in the left-right direction may be substantially the same as the total length of the wick 20 in the width direction. Furthermore, the total length of the third and fourth cover pieces 31C and 31D in the height direction may be substantially the same as the total height of the wick 20 and the height of the first and second cover pieces 31A and 31B arranged on the upper and lower surfaces of the wick 20. When the cover piece 31 adjusted to the above-mentioned dimensions is arranged on the outer periphery of the wick 20, the surface on which the groove 32 is formed is in contact with the outer periphery of the wick 20.

[0027] Furthermore, the cover piece 31 may be provided with a plurality of grooves 32 extending in the length direction on the surface facing the wick 20 when the cover piece 31 is disposed so as to cover the outer periphery of the wick 20. The plurality of grooves 32 can function as passages through which the gas-phase working fluid F passes. The grooves 32 can be formed by cutting, etching, or laser processing the cover piece 31.

[0028] In the cover 30 of this embodiment, of the four cover pieces 31A, 31B, 31C, and 31D, the surface of the first cover piece 31A opposite to the surface on which the groove 32 is formed functions as a joint surface 33 on which the heating element 6 is placed. The structure of the joint surface 33 will be described below with reference to FIG. 3. The number of joint surfaces may be multiple depending on the intended use of the loop heat pipe 1. Specifically, for example, one surface of the first cover piece 31A and one surface of the second cover piece 31B may be used as joint surfaces.

[0029] 3 is a perspective view showing an example of a cover piece of the evaporator shown in FIG. 2. The first cover piece 31A, one surface of which functions as a bonding surface 33, can directly bond the heating element 6 to the bonding surface 33, which is the surface opposite to the surface on which the multiple grooves 32 are formed, as shown in FIG. 1. The heating element 6 may include the above-mentioned circuit module, a single electronic component such as a semiconductor chip, or a circuit pattern on which an electronic component is mounted. In addition, a resin composition containing a thermosetting resin, an adhesive, or solder may be used to bond the heating element 6.

[0030] Examples of the thermosetting resin contained in the resin composition include epoxy resin, phenol resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, and cyanate resin. As the thermosetting resin, one type may be used alone, or two or more types may be used in combination. In addition, the resin composition may contain a curing agent, a filler (inorganic filler), a curing accelerator, a solvent, or an additive.

[0031] Here, the first cover piece 31A in this embodiment is made of stainless steel. Therefore, the joining surface 33 is relatively smooth, and it is difficult for the resin composition or adhesive to adhere thereto, so not only is a high joining strength difficult to obtain, but workability is also poor. Therefore, in this embodiment, the surface area of ​​the joining surface 33 is increased to improve the joining strength, workability, and the like.

[0032] The treatment for increasing the surface area of ​​the bonding surface 33 may include at least one of a roughening treatment, a chemical conversion treatment, and a plating treatment. The specific treatment contents of the roughening treatment, the chemical conversion treatment, and the plating treatment are not particularly limited as long as they can increase the surface area of ​​the bonding surface 33.

[0033] In this embodiment, a case where a roughening treatment (e.g., sandblasting) is adopted as a treatment for increasing the surface area of ​​the bonding surface 33 is exemplified. The roughening treatment of the bonding surface 33 may be performed on the entire bonding surface 33, or may be performed on only a part of the bonding surface 33 in accordance with the shape of the heating element 6, etc. The roughened region 35 of the bonding surface 33 that has been roughened has an increased surface area compared to before the roughening treatment. The surface roughness (Ra) of the roughened region 35 is preferably 1.0 μm or more. The upper limit of the surface roughness is not particularly limited, but may be, for example, 20.0 μm or less.

[0034] Furthermore, the left and right end faces of the first cover piece 31A function as cover piece joints 34 that are joined to the third and fourth cover pieces 31C, 31D. The cover pieces can be joined together by welding, for example. The joining method may be appropriately selected from well-known joining methods taking into consideration the material of the cover pieces 31, etc. Furthermore, the cover piece joints 34 are also provided on each of the second to fourth cover pieces 31B, 31C, 31D.

[0035] A method for manufacturing an evaporator having the above-mentioned configuration will be described below mainly with reference to FIG.

[0036] The manufacturing method of the evaporator according to the present embodiment includes at least the steps of preparing a flat wick 20 having a first space 21 formed therein into which a liquid-phase working fluid F can flow (corresponding to step S1 described later), performing a process for increasing the surface area of ​​at least one of the flat cover pieces 31 that cover one surface of the wick 20 and have a plurality of groove-like grooves 32 formed on the inner surface (corresponding to step S2 described later), arranging the cover pieces 31 so as to cover the wick 20 such that the surface on which the grooves 32 are formed abuts against the outer surface of the wick 20 (corresponding to step S4 described later), and joining the cover pieces arranged around the wick 20 (corresponding to step S5 described later). The steps will be described in detail below.

[0037] Fig. 4 is a flow chart showing an example of a manufacturing method of an evaporator according to an embodiment of the present disclosure. In the manufacturing method of an evaporator 2 according to the present embodiment, as shown in Fig. 4, first, a wick 20 is prepared (step S1). The prepared wick 20 may be adjusted in size according to the structure of the loop heat pipe 1 to be manufactured, more specifically, according to the dimensions of the liquid pipe connecting member 41 and the vapor pipe connecting member 42.

[0038] In parallel with the preparation of the wick 20 described above, it is advisable to prepare four cover pieces 31A, 31B, 31C, and 31D capable of covering the outer periphery of the prepared wick 20. A plurality of grooves 32 are formed in advance by cutting or the like on one surface of the four cover pieces 31A, 31B, 31C, and 31D prepared here.

[0039] Next, a roughening treatment is performed on one of the four cover pieces 31A, 31B, 31C, and 31D constituting the cover 30, the first cover piece 31A in detail, the first cover piece 31A being one surface of which constitutes the joining surface 33 (step S2). This roughening treatment may be, for example, sandblasting performed over the entire surface of the joining surface 33.

[0040] Next, stress relief annealing is performed on the first cover piece 31A having the roughened region 35 formed at least on the joining surface 33 (step S3). The stress relief annealing refers to quenching (annealing) for removing distortion inside the cover piece 31 that occurs mainly due to the formation of the groove 32 and the roughened region 35. By performing this stress relief annealing, distortion is removed from the cover piece 31, and the subsequent joining process can be performed stably. As for specific devices for performing stress relief annealing, well-known devices can be used, and detailed explanations thereof will be omitted here.

[0041] 5 is a schematic diagram showing the process of placing the cover pieces on the outer surface of the wick. After the distortion of the cover piece 31 is removed, the four cover pieces 31A, 31B, 31C, and 31D are then placed so as to surround the outer periphery of the wick 20, as shown in FIG.

[0042] When the arrangement of the cover pieces 31 is completed, the cover pieces are joined together by welding the opposing cover piece joints 34 of each cover piece 31A, 31B, 31C, and 31D to each other (step S5). In this embodiment, as shown in FIG. 5, the case where the surfaces constituting the opposing cover piece joints 34 are welded to each other is illustrated, but the arrangement of the joined surfaces is not limited to that shown in FIG. 5, and it can be set on other side surfaces of the cover piece 31. When the cover pieces are joined to each other, the outer periphery of the wick 20 is covered by the cover pieces 31A, 31B, 31C, and 31D. Then, the liquid pipe connecting member 41 and the vapor pipe connecting member 42 are attached to the upstream end and downstream end of the wick 20 in the flow direction of the working fluid F, and the liquid phase working fluid F starts to flow into the first space 21, so that the loop heat pipe 1 can be operated.

[0043] As described above, according to the manufacturing method of the evaporator of this embodiment, by carrying out a treatment for increasing the surface area of ​​the joint surface 33 of the evaporator 2, it is possible to increase the joint area of ​​the joint surface 33 with the resin composition or adhesive used for bonding the heat generating element 6. This makes it possible to directly bond the heat generating element 6 using the resin composition or the like. In addition, it is possible to improve the workability during bonding and realize a high bonding strength.

[0044] Additionally, in the manufacturing method of the evaporator according to the present embodiment, the treatment for increasing the surface area can be performed on the cover pieces 31, which are the divided bodies of the cover 30, improving the workability of the treatment. Also, by performing stress relief annealing on the cover pieces 31, poor bonding caused by strain or the like is less likely to occur when the cover pieces 31 are bonded together.

[0045] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the spirit of the present disclosure described in the claims unless otherwise specifically limited in the above description. Furthermore, the effects of the above embodiment are merely examples of the effects resulting from the present disclosure, and do not mean that the effects of the present disclosure are limited to the above effects. [Explanation of symbols]

[0046] 1 Loop type heat pipe 2. Evaporator 3. Condenser 4 Steam Pipe 5 Liquid Pipe 20 Wick 21 The First Space 30 Cover 31, 31A, 31B, 31C, 31D Cover pieces 32 Groove 33 Joint surface 34 Cover piece joint 35 Roughening area F Working fluid

Claims

1. A step of preparing a flat wick having a first space formed therein into which a liquid-phase working fluid can flow; A process for covering one side of the outer periphery of the wick and increasing the surface area of ​​the outer surface of at least one of a plurality of flat cover pieces having a plurality of grooves on the inner surface; A step of placing a plurality of the cover pieces so as to cover the outer periphery of the wick, with the grooved surface abutting the outer surface of the wick; and joining the cover pieces arranged around the wick to each other. A method for manufacturing an evaporator.

2. The treatment for increasing the surface area includes at least one of a roughening treatment, a chemical conversion treatment, and a plating treatment. A method for manufacturing the evaporator according to claim 1.

3. The method further includes a step of performing stress relief annealing on the cover piece after performing the step of increasing the surface area of ​​the outer surface. A method for manufacturing the evaporator according to claim 1.

Images