JP5625835B2 - heat pipe - Google Patents

Description

  The present invention relates to a heat pipe including a tubular body having a sealed space inside, and a working fluid sealed in the sealed space.

  It is known that electronic components such as semiconductor elements generate heat as they are driven. Such heat generation may cause problems such as a decrease in efficiency, malfunction, or damage of the electronic component. Therefore, conventionally, it has been proposed to provide a heat pipe as a cooling device in the vicinity of an electronic component.

  As is well known, the heat pipe is obtained by enclosing water or alternative chlorofluorocarbon functioning as a working fluid inside a tubular body that is a sealed space. When one end of the heat pipe is heated by a heating element arranged close to the heat pipe, the enclosed hydraulic fluid is vaporized, and heat is taken in as latent heat (heat of vaporization). Then, the vaporized working fluid moves to the low temperature part, which is the other end of the heat pipe, where it is cooled, returned to the liquid, and releases heat. The liquefied hydraulic fluid moves to the vicinity of the heating element due to an action such as capillary action, and again receives heat from the heating element and vaporizes. Then, by repeating the same cycle thereafter, heat is continuously transferred efficiently and the heating element is cooled.

International Publication No. 2003/050466 Pamphlet

  However, many conventional heat pipes use a metal circular tube as a tube. In such a configuration, heat leaks to the outside in the process of heat transfer, and there are problems such as an increase in ambient temperature and a decrease in exhaust heat efficiency. Further, in the case of a circular tube, it has been difficult to directly place an electronic component which is a heating element and a fin for heat dissipation on the circular tube. For this reason, in order to obtain an installation surface for electronic parts, etc., additional work is required to obtain a flat surface, such as sandwiching the circular tube with a flat plate or inserting the circular tube into a metal block. An increase was incurred.

  In order to avoid such a problem, Patent Document 1 discloses a heat pipe in which a sealed space is formed inside a flat plate by laminating thin plates with grooves and recesses, and a working fluid is sealed in the sealed space. ing. According to such a heat pipe, since a flat surface can be obtained without performing a separate operation, electronic components, fins, and the like can be easily installed.

  However, since the heat pipe described in Patent Document 1 has a configuration in which a plurality of flat plates are laminated, the number of parts increases and the manufacturing process tends to be complicated.

  Therefore, an object of the present invention is to provide a heat pipe that can be manufactured more easily.

The heat pipe of the present invention is a heat pipe including a tubular body having a sealed space inside and a working fluid sealed in the sealed space, and the surface of the tubular body is exposed to the outside. In addition, a flat plate made of a conductive material whose back surface is exposed to the sealed space, a heat generating portion on which the heating element is mounted, and a high heat transfer property whose surface is exposed to the outside and whose back surface is exposed to the sealed space. A flat plate made of a material, which is made of a heat-radiating part that dissipates heat by heat exchange with the outside, and a material that has heat insulation and insulation, and is insulated at least between the heat-generating part and the heat-dissipating part. And the heat generating part, the heat radiating part, and the insulating part are integrally formed by insert molding, and the heat generating part is provided on each of two opposing surfaces of the tubular body, Upper arm element or Serves as an electrode of a semiconductor element that functions as the arm elements, further, made of a conductive material, having an inner member across said enclosed space connecting two heat generating portion provided in each of the two surfaces, that Features.

  In another preferred aspect, a plurality of the internal members are arranged at intervals in a direction orthogonal to the moving direction of the hydraulic fluid. It is also desirable to provide an output electrode made of a conductive material, connecting two heat generating portions provided on each of the two surfaces, and having one end protruding outside the tube. Furthermore, it is also desirable that the heat dissipating part is provided on each of two opposing surfaces of the tubular body.

  According to the present invention, since the heat generating part, the heat radiating part, and the insulating part are integrally formed by insert molding, it is possible to easily obtain a heat pipe of a suitable form.

It is a schematic perspective view of the heat pipe which is embodiment of this invention. It is the schematic of the AA cross section of FIG. It is a schematic sectional drawing of the heat pipe of 2nd embodiment. It is the schematic of the BB cross section of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic perspective view of a heat pipe 10 according to an embodiment of the present invention. 2 is a schematic cross-sectional view taken along the line AA in FIG.

  The heat pipe 10 includes a tube body 12 and a working fluid that is vacuum-sealed inside the tube body 12. As with the conventional heat pipe 10, water or alternative chlorofluorocarbon can be used as the hydraulic fluid. By repeating the cycle of evaporation (vaporization) and condensation (liquefaction) with this hydraulic fluid, the heat generated in the heat generating portion 14 provided near one end of the tube body 12 is effectively released to the outside. .

  That is, the hydraulic fluid absorbs heat generated in the heat generating portion 14 provided near one end of the tube body 12 as latent heat and evaporates (vaporizes). The vaporized working fluid moves to the vicinity of the low-temperature heat dissipating part 16, releases latent heat, and condenses (liquefies). The liquefied hydraulic fluid moves to the vicinity of the heat generating portion 14 by the action of capillary action, gravity, self-excited vibration accompanying the boiling of the hydraulic fluid, and vaporizes again. Thereafter, this evaporation and condensation cycle is repeated, and the heat received from the heat generating part 14 is released to the outside through the heat radiating part 16, so that the heat in the heat generating part 14 is effectively released. .

  The tubular body 12 is a tubular body in which a metal flat plate and a resin are integrally formed by resin insert molding, and a vacuum sealed space 20 in which a working fluid is sealed is formed therein. As is apparent from FIGS. 1 and 2, the tubular body 12 of the present embodiment has a rectangular tube shape with a substantially rectangular cross section, and the upper surface thereof is a flat surface. The tubular body 12 includes a heat generating portion 14 and a heat radiating portion 16 made of a metal flat plate, and an insulating portion 18 made of resin.

  The heat generating part 14 is a part where a semiconductor element or the like that functions as a heat generating element is mounted. The heat generating part 14 is composed of a flat plate made of a highly heat conductive material such as copper, and the flat plate surface is exposed to the outside, and the flat plate back surface is exposed to the sealed space 20 inside the tube body 12.

  The heat radiating part 16 is a part that releases heat to the outside, and is a part where, for example, a cooling fin or the like is installed. The heat radiating portion 16 is also composed of a flat plate made of a highly heat-conductive material such as copper, like the heat generating portion 14, and the surface of the flat plate is exposed to the outside and the back surface is exposed to the sealed space 20 inside the tube body 12. Yes. The heat radiating part 16 is provided at a position separated from the heat generating part 14.

  A portion of the tubular body 12 other than the heat generating portion 14 and the heat radiating portion 16 serves as an insulating portion 18. The insulating portion 18 is made of a material having insulating properties and heat insulating properties, for example, resin or ceramic, and is integrally formed with the heat generating portion 14 and the heat radiating portion 16 by insert molding.

  The operation of the heat pipe 10 configured as described above will be described in comparison with the conventional heat pipe 10. As the conventional heat pipe 10, there are known a circular tube type using a metal circular tube and a laminated type in which flat plates having grooves are laminated.

  In the case of the circular pipe type heat pipe 10, since the upper surface of the tube body 12 is not flat, it is difficult to directly mount the heating element and the fin on the heat pipe 10. Therefore, in the case of the circular pipe type heat pipe 10, the flat part surface for mounting a heating element etc. was ensured by inserting the end part into a metal block or sandwiching the circular pipe with a flat plate. As described above, when a member (metal block or flat plate) other than the heat pipe 10 is interposed between the heat pipe 10 and the heating element or fin, the heat transfer efficiency from the heating element to the working fluid and from the working fluid to the heat radiating unit 16 is improved. As a result, the cooling efficiency is lowered. Further, when such other members are interposed, the manufacturing process becomes complicated, which may increase the cost.

  Further, in the case of the circular pipe type heat pipe 10, parts other than the heat generating part 14 that receives heat and the heat radiating part 16 that releases heat (steam transport part) are also made of a metal having high heat conductivity. Heat leaked from the heat to the outside. Such a heat leak may cause a decrease in temperature in the heat radiating section 16 (a decrease in the amount of heat released from the heat radiating section 16) and an increase in the ambient temperature, resulting in a decrease in cooling efficiency. In addition, since such a heat leak cannot be accurately estimated, the heat radiating fins must be designed to include the heat leak, resulting in poor design efficiency.

  In addition, since the heat generating part 14 and the heat radiating part 16 are connected to each other by a metal, the circular pipe type heat pipe 10 has a heat generating element 14 and a heat generating element 14 mounted with a heat generating element such as a semiconductor element. It was necessary to separately provide insulation between the pipe 10 (the heat generating portion 14). The installation of such insulation is not only troublesome, but also leads to an increase in thermal resistance and consequently a deterioration in cooling efficiency. Further, since the bending angle of the circular pipe is limited, there is a problem that the shape design of the heat pipe 10 is limited.

  In the case of the laminated heat pipe 10, some of these problems can be solved. For example, since the upper surface of the laminated heat pipe 10 is a flat surface, it is not necessary to separately provide a separate member for securing a flat surface for installing a heating element and fins. However, even in the case of the laminated type heat pipe 10, if a metal flat plate is used as a thin plate, problems such as heat leakage and securing insulation arise as in the case of the circular pipe type heat pipe 10. In addition to the copper flat plate, it may be possible to avoid some problems such as heat leaks by constructing a part of the material with insulating and heat insulating materials. A new problem arises that becomes very complex. Moreover, normally, when brazing is used for joining thin plates, inexpensive water cannot be used as the working fluid, resulting in an increase in manufacturing cost of the heat pipe 10.

  Compared to such a conventional heat pipe 10, the heat pipe 10 of the present embodiment is a square pipe shape by insert molding a heat generating portion 14 and a heat radiating portion 16 made of metal and an insulating portion 18 made of an insulating / heat insulating material. Is integrally molded. Therefore, since the upper surface of the heat pipe 10 itself is a flat surface, a flat surface for installing a heating element (such as a semiconductor element) or fins can be easily secured without interposing another member.

  Further, the heat generating portion 14 on which the heat generating body is mounted has its back surface exposed to the sealed space 20 inside the tube body 12. In other words, only the metal plate constituting the heat generating portion 14 exists between the heat generating body and the sealed space 20 in which the hydraulic fluid is enclosed. Similarly, the heat dissipating part 16 on which fins and the like are mounted has its back surface exposed to the sealed space 20, and the heat dissipating part 16 is configured between the fins and the sealed space 20 in which the working fluid is sealed. Only a metal plate exists. As a result, the heat transfer efficiency from the heating element to the working fluid and from the working fluid to the fins and the like is increased, and as a result, the cooling efficiency of the heating element can be improved as compared with the conventional case.

  Further, in the heat pipe 10 of the present embodiment, the insulating part 18 which is a part other than the heat generating part 14 where the heat generating element is mounted and the heat radiating part 16 where the heat is radiated is made of a material having heat insulating properties (for example, resin). It is configured. By adopting such a configuration, a heat leak in which heat leaks to the outside in the process of steam transport (heat transport) is effectively prevented. As a result, while the temperature of the heat radiating part 16 can be kept high, an increase in the ambient temperature can be prevented, and as a result, the cooling efficiency of the heating element can be improved as compared with the conventional case. Moreover, there is an advantage that fins and the like can be designed efficiently by preventing heat leakage.

  Further, an insulating portion 18 made of an insulating material is interposed between the heat generating portion 14 and the heat radiating portion 16 on which the heat generating body is mounted. Therefore, insulation can be ensured for the heating element mounted on the heat generating portion 14 without separately providing an insulating member, and the labor for mounting the heating element can be reduced.

  Furthermore, in this embodiment, the insulating part 18 made of an insulating and heat insulating material, the heat generating part 14 and the heat radiating part 16 made of metal are integrally formed by insert molding. Insert molding is a molding method in which members of different materials are joined during the molding process. Therefore, it is not necessary to join parts by brazing or the like, and inexpensive and safe water can be used as the working fluid. Moreover, since such insert molding has high moldability, the degree of freedom in designing the shape of the heat pipe 10 can be greatly improved as compared with the prior art. Further, the heat pipe 10 according to the present embodiment has the insulating portion 18 that occupies most of the heat pipe 10 made of an inexpensive and lightweight resin. Therefore, the material cost of the heat pipe 10 can be reduced and the weight can be reduced.

  1 and 2 exemplify a heat pipe 10 that is substantially straight when viewed from the top for ease of explanation, the shape of the heat pipe 10 (tube body 12) may be changed as appropriate. . For example, it may have a substantially L shape in a top view, a tubular shape, a meandering shape that repeatedly bends in a hairpin shape, or a loop shape in which a start end and a terminal end are connected. Moreover, the cross-sectional shape of the tubular body 12 is not limited to a substantially rectangular shape, and may be changed as appropriate. For example, the cross section may be L-shaped, convex, or the like, or may have the same cross-sectional substantially rectangular shape or a shape with Rs attached to the corners thereof. However, in order to facilitate installation of the heating element, it is desirable that the cross-sectional shape of the tubular body is a shape in which at least the upper surface of the tubular body has a flat surface. In addition, the movement of the liquefied hydraulic fluid to the heat generating part 14 utilizes capillary action, gravity, self-excited vibration caused by the sudden generation and instantaneous interruption of bubbles accompanying evaporation / condensation of the hydraulic fluid. Also good.

  Next, another embodiment will be described with reference to FIGS. FIG. 3 is a schematic cross-sectional view of the heat pipe 10 of the second embodiment, and FIG. 4 is a schematic cross-sectional view taken along the line BB in FIG. The heat pipe 10 has a particularly suitable configuration for cooling the lower arm element and the upper arm element constituting the inverter and the converter.

  More specifically, the heat pipe 10 is a tube in which a metal heat generating portion 14 and a heat radiating portion 16 and a resin insulating portion 18 are integrally formed by resin insert molding, as in the above-described embodiment. A body 12 is provided. However, unlike the above-described embodiment, in this embodiment, two heat generating portions 14 are provided, one on each of the two opposing surfaces of the tube body 12. In addition, an internal member 22 for connecting the two heat generating portions 14, an output electrode 24 for connecting the two heat generating portions 14 and projecting to the outside are also provided. This will be described in detail below.

  As described above, in this embodiment, a total of two heat generating portions 14 are provided, one on each of the two opposing surfaces of the tube body 12. In the present embodiment, the two heat generating portions 14 are used as electrodes of the lower arm element or the upper arm element. That is, an electrode for receiving power is usually provided in a semiconductor element such as an IGBT constituting the lower arm element or the upper arm element. In the present embodiment, the heat generating portion 14 of the heat pipe 10 is used as an electrode of the upper and lower arm elements. With such a configuration, it is not necessary to separately provide a configuration of the energization portion of the upper and lower arm elements, and the upper and lower arm elements can be directly mounted on the heat generating portion 14. In addition, since the electrodes of the upper and lower arm elements themselves function as the heat generating portion 14 of the heat pipe 10, the electrodes of the upper and lower arm elements can be directly cooled by the heat pipe 10, and the cooling efficiency can be further improved.

  Moreover, by providing the two heat generating portions 14 (the electrodes of the upper and lower arm elements) on the two surfaces facing each other, the two heat generating portions 14 can be uniformly cooled, and the length of the heat pipe 10 can be shortened. . That is, when the two heat generating portions 14 are provided on the same plane, it is naturally necessary to increase the length of the heat pipe 10 accordingly. Moreover, when the two heat generating portions 14 are provided on the same plane, the two heat generating portions 14 are arranged in the moving direction of the hydraulic fluid. In this case, of the two heat generating parts 14, the heat generating part 14 provided at a position far from the heat radiating part 16 is preferentially cooled, and the cooling efficiency of the two heat generating parts 14 becomes non-uniform. There is. On the other hand, when the two heat generating portions 14 are provided at positions facing each other as in the present embodiment, the heat generated in the two heat generating portions 14 is transferred to the hydraulic fluid at the same timing, and as a result The two heat generating portions 14 are uniformly cooled.

  The internal member 22 is a flat plate that connects the two heat generating portions 14 facing each other across the sealed space 20 inside the tube body 12. The internal member is made of a material having heat conductivity and conductivity (for example, a metal such as copper). In the present embodiment, a plurality of the internal members 22 are arranged at intervals in the width direction of the tube body 12. As described above, by disposing the plurality of internal members 22 at intervals in the width direction, the working fluid can smoothly move while increasing the total surface area of the internal members 22. In this embodiment, the moving direction of the hydraulic fluid is the length direction of the tube body 12, and the distance direction between the two surfaces where the two heat generating portions 14 are arranged is the thickness direction, the length direction, and the thickness direction of the tube body 12. A direction orthogonal to the width direction is referred to as a width direction.

  Such an internal member 22 is integrally formed by resin insert molding together with the heat generating portion 14, the heat radiating portion 16, and the insulating portion 18. The internal member 22 may be a separate part from the heat generating part 14, but is preferably the same part integrally molded with the heat generating part 14. In other words, it is desirable that the heat generating portion 14 and the internal member 22 can be handled as the same single component. With this configuration, the number of parts can be reduced.

  Here, the internal member 22 is in physical contact with the two heat generating portions 14 and functions as a bus bar that electrically connects the two heat generating portions 14 (that is, the electrodes of the upper and lower arm elements). By providing the internal member 22 that functions as a bus bar in this manner, it is not necessary to separately provide a power feeding structure, and the mounting work of the upper and lower arm elements can be further simplified.

  Further, since the internal member 22 has a large surface area inside the tube 12 of the heat pipe 10, heat exchange with the hydraulic fluid can be performed efficiently. Therefore, the internal member 22 functions as an evaporation fin that effectively evaporates the working fluid. Thus, by providing the internal member 22 that functions as an evaporation fin, the cooling efficiency can be further improved. Furthermore, the internal member 22 also functions as a thermal mass that accumulates heat. By providing the internal member 22 that functions as such a heat mass, the heat capacity that can be held by the heat generating portion 14 and the internal member 22 connected to the heat generating portion 14 can be increased. As a result, even if the amount of heat generated from the upper and lower arm elements is the same, the temperature rise can be suppressed lower than when the internal member 22 is not provided.

  That is, in this embodiment, by providing the internal members 22 that function as bus bars, evaporation fins, and thermal masses, the mounting work of the upper and lower arm elements can be further simplified, the cooling efficiency can be further improved, and the upper and lower arm elements can be further improved. Temperature rise can be kept low. In the present embodiment, the internal member 22 is a substantially flat plate. However, the shape and number of the internal members 22 may be appropriately changed as long as the two heat generating portions 14 are connected without hindering the movement of the hydraulic fluid. . For example, the internal member 22 may be a corrugated plate material having a substantially meandering cross section. By using the corrugated plate material in this way, the surface area can be increased, and the heat exchange rate with the hydraulic fluid and the heat capacity can be increased. Further, the internal member 22 may be a plurality of bar members that connect the two heat generating portions 14 instead of the plate material. When the rod member is used as the internal member 22, it is desirable that a plurality of the internal members 22 be arranged not only in the width direction of the tube body 12 but also in the length direction.

  The output electrode 24 is a plate member that connects the two heat generating portions 14 (electrodes of the upper and lower arm elements) and protrudes to the outside. The output electrode 24 is made of a conductive material, for example, a metal material such as copper. In the present embodiment, the output electrode 24 is provided at a position farther from the heat radiating portion 16 than the internal member 22, so as not to hinder the movement of the hydraulic fluid between the internal member 22 and the heat radiating portion 16 as much as possible. Yes.

  Similarly to the internal member 22, the output electrode 24 is integrally formed by resin insert molding together with the heat generating portion 14, the heat radiating portion 16, and the insulating portion 18. The output electrode 24 is also preferably the same part integrally formed with the heat generating portion 14 and the internal member 22.

  A total of two heat dissipating portions 16 are also provided, one on each of the two opposing surfaces. By providing the heat dissipating part 16 on the two opposite surfaces, the area of the heat dissipating part 16 can be increased without increasing the size of the tube body 12, and more efficient heat dissipation can be achieved.

  The operation of the heat pipe 10 configured as described above will be described. An upper arm element and a lower arm element that constitute a power conversion device such as an inverter or a converter are mounted on the two heat generating portions 14 of the heat pipe 10. At this time, since the heat generating portion 14 itself functions as an electrode of the upper and lower arm elements, the upper and lower arm elements can be directly mounted.

  When the mounted upper and lower arm elements generate heat as they are driven, the heat is transmitted to the heat generating portion 14 that functions as an electrode and the internal member 22 that functions as a bus bar. At this time, in this embodiment, since the internal member 22 that functions as a heat mass for accumulating heat is present, the temperature rise of the heat generating portion 14 and the upper and lower arm elements mounted on the heat generating portion 14 can be moderately suppressed. .

  The hydraulic fluid enclosed in the tube body 12 is vaporized by receiving heat from the heat generating portion 14 and the internal member 22. At this time, by providing the heat generating part 14 on the two opposite surfaces and providing the internal member 22 that traverses the inside of the tube body 12, the area where the heat retaining portion and the hydraulic fluid come into contact with each other is increased, which is more efficient. Thus, heat can be passed to the hydraulic fluid, and as a result, the cooling efficiency can be improved.

  The vaporized hydraulic fluid moves to the vicinity of the low-temperature heat radiating portion 16 and exchanges heat with the heat radiating portion 16. With this heat exchange, the temperature of the hydraulic fluid decreases and liquefies. The liquefied hydraulic fluid moves again to the vicinity of the heat generating portion 14 (in the vicinity of the internal member 22) by the action of gravity, capillary action, self-excited vibration, or the like. Thereafter, the cycle of vaporization and liquefaction is repeated in the same flow, and the upper and lower arm elements mounted on the heat generating portion 14 are cooled.

  As is apparent from the above description, according to the present embodiment, since the heat generating portion 14 is used as the electrode of the upper and lower arm elements, the upper and lower arm elements can be cooled more efficiently, and the mounting work of the upper and lower arm elements can be simplified. Can be Furthermore, by providing an internal structure for connecting the two heat generating portions 14 (electrode portions of the upper and lower arm elements) across the inside of the tube body 12, it is possible to save the trouble of separately providing a connection bus bar for the upper and lower arm elements. More efficient cooling is possible.

  DESCRIPTION OF SYMBOLS 10 Heat pipe, 12 pipe body, 14 Heat generating part, 16 Heat radiating part, 18 Insulating part, 20 Sealed space, 22 Internal member, 24 Output electrode.

Claims (4)

A heat pipe provided with a tubular body having a sealed space inside, and a working fluid sealed in the sealed space,
The tube is
A heating plate on which a heating element is mounted, the flat plate made of a conductive material whose front surface is exposed to the outside and whose back surface is exposed to the sealed space;
A flat plate made of a highly heat-conductive material whose front surface is exposed to the outside and whose back surface is exposed to the sealed space, and a heat radiating part that radiates heat by heat exchange with the outside,
An insulating part made of a material having a heat insulating property and an insulating property, which is interposed between at least the heat generating part and the heat radiating part and insulates both,
The heat generating part, the heat radiating part, and the insulating part are integrally formed by insert molding ,
The heat generating part is provided on each of two opposing surfaces of the tubular body,
Each heating part functions as an electrode of a semiconductor element that functions as an upper arm element or a lower arm element,
Furthermore, it is made of a conductive material, and has an internal member that connects two heat generating portions provided on each of the two surfaces across the sealed space,
A heat pipe characterized by that. The heat pipe according to claim 1 ,
A plurality of the internal members are arranged at intervals in a direction orthogonal to the moving direction of the hydraulic fluid. The heat pipe according to claim 1 or 2 ,
A heat pipe made of a conductive material, connecting two heat generating portions provided on each of two surfaces, and having an output electrode with one end protruding outside the tube. The heat pipe according to any one of claims 1 to 3 ,
The heat dissipating part is provided on each of two opposing surfaces of the tubular body.

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