JP2008130715A - Heatsink, and power converting device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heatsink and a power converting device equipped with it, capable of improving heat conductivity from a base plate to a heat radiation fin by shielding the radiation of heat into a case. <P>SOLUTION: A heatsink 10 comprises a base plate 11 on which a heating body 1 is mounted, and a plurality of heat radiation fins 12 arranged on such side of base plate 11 in a way that they face a heating body mounting surface. A heat conductive body 31 in which a thin, flat closed vessel is formed by dividing into two chambers in thickness direction of the base plate 11, is provided along the heating body mounting surface of the base plate 11, near the position where the heating body is mounted. The heat conductive body 31 consists of a heat pipe 33 in which a condensable operation fluid that transports heat as latent heat of vaporization is sealed up in one chamber of the closed vessel, being counter and contacted to the base plate 11 side, and a heat shielding part 32 in which a non-condensable fluid is sealed up, in degassed state, in the other chamber of the closed vessel. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power conversion device such as an inverter that includes a heating element such as a power module and that mainly operates with a high-voltage power supply, and more particularly to a heat sink for increasing the heat dissipation effect of the power conversion device and a power conversion device using the heat sink. Is.

Conventionally, in a power conversion device such as an inverter that mainly operates with a high-voltage power supply, semiconductor elements such as a power module (PM), a diode module (DM), an IGBT, and an electrolytic capacitor generate heat due to electrical loss during power conversion. These semiconductor elements are generally removed by a cooling device including a heat sink having a heat radiation fin and a cooling fan, and destruction of the elements due to a temperature rise is prevented. An inverter device provided with such a cooling device is, for example, as shown in FIG. 5 (see Patent Document 1 and Patent Document 2).
FIG. 5 is an overall perspective view showing a conventional power converter.
In FIG. 5, 1 is a heating element, 2 is a printed circuit board, 3 is an electrolytic capacitor, 10 is a heat sink, 11 is a base plate, 12 is a radiation fin, and 20 is a housing.
The casing 20 is configured by a rectangular parallelepiped box that constitutes the main body of the power converter, and the heating element 1 such as a power module is accommodated in the casing 20. The heating element 1 is connected to a heat sink 10 via a base plate 11 by screwing or the like. The heat sink 10 includes a large number of radiating fins 12 joined by caulking or the like so as to be orthogonal to the rectangular base plate 11, and is made of a material having high thermal conductivity such as an aluminum alloy.
Further, a printed circuit board 2 on which electronic components are mounted on the heat sink 10 and an electrolytic capacitor 3 are installed in the housing 20 so as to protrude, and further, it is necessary between the heat sink 10 and the upper portion of the housing 2. Accordingly, a cooling fan (not shown) is attached. Then, an intake hole for sucking outside air is provided at the bottom of the housing, and an exhaust hole for exhausting is provided on the side surface.

Next, the operation will be described.
In the power conversion device as described above, first, when a cooling fan (not shown) is driven, outside air as cooling air is sucked from an intake hole (not shown) at the bottom of the housing 20 and then a plurality of electrolytic capacitors. 3 and between the heat sink fins 12 of the heat sink 10 and forcibly exhausted toward the cooling fan (not shown). In that case, the heat generated from one electrolytic capacitor 3 is cooled by the cooling air immediately after being sucked from the intake hole. Further, the heat generated from the other heating element 1 is diffused into the base plate 11 of the heat sink 10 by heat conduction, and then transferred to the heat radiating fins 12 and is radiated from the surface to the cooling air by heat transfer accompanying forced convection. .
Japanese Unexamined Patent Publication No. 2000-232288 (Specification, page 3, FIG. 2)

However, in the conventional power converter, as shown in FIG. 5, the heat generated by the heating element is radiated to the atmosphere via the heat sink, and at the same time, part of the heat is also radiated from the surface of the base plate of the heat sink to the inside of the housing. In addition, since the ambient temperature in the housing is raised, there is a problem in that it affects the operating characteristics (performance) and life (reliability) of the printed circuit board on which electronic components are mounted and the electrolytic capacitor. Therefore, in order to ensure the performance and reliability of the power conversion device, it is necessary to suppress heat dissipation from the surface of the base plate of the heat sink into the housing.
Here, FIG. 6 shows a conventional power converter, in which (a) shows a layout of the heating elements when the heat sink is viewed from above, and (b) shows a temperature distribution diagram on the base plate.
In FIG. 6, the temperature of the surface of the base plate 11 is high in the region A sandwiched between the heating elements 1, but the surface temperature of the base is low in the region B away from the end of the base plate 11 and the heating element 1. Since the surface temperature distribution is non-uniform over the area, the heat radiation to the radiation fins cannot be increased in the region B away from the end of the base plate of the heat sink 10 or the heating element, and from the surface of the base plate 11 to the housing 20. Since the heat radiation to the inside increased, the cooling capacity of the heat sink itself was not fully used.
The present invention has been made in view of such a problem, and it is possible to block heat radiation from the base plate of the heat sink to the inside of the housing 20 and to enhance heat conduction from the base plate to the heat radiating fins. An object is to provide a power conversion device provided.

In order to solve the above problems, the present invention is configured as follows.
The invention according to claim 1 is a heat sink having a base plate on which a heating element is mounted, and a plurality of heat dissipating fins arranged on the side opposite to the heating element mounting surface of the base plate. A thermal conductor formed by dividing a flat sealed container into two chambers in the thickness direction of the base plate is provided in the vicinity of the position along which the heating element is attached. A heat pipe encapsulating a condensable working fluid that transports heat as latent heat of vaporization in one of the chambers, and in contact with the base plate side, and a non-condensable in the other chamber of the sealed container It is characterized by being comprised from the heat insulation part formed by sealing in the state which deaerated the fluid.
According to a second aspect of the present invention, in the heat sink according to the first aspect, the heat insulating portion of the heat conductor is formed by filling a low heat conductive inorganic substance.
According to a third aspect of the present invention, in the heat sink according to the first aspect, the heat generating member is arranged by providing a hole portion slightly larger than the heat generating member in the heat insulating portion of the heat conductor, and the heat generating member is provided in the heat pipe. It is characterized by direct contact.
A fourth aspect of the present invention is the heat sink according to the first aspect, wherein the heat conductor is integrated with a base plate of the heat sink.
According to a fifth aspect of the present invention, in the heat sink according to the first aspect, a thermal compound or thermal conductive grease for improving heat transferability is applied between the thermal conductor and the base plate.
A sixth aspect of the present invention is a power conversion device including the heat sink according to any one of the first to fifth aspects.

According to the first aspect of the present invention, the heat conduction of the base plate can be enhanced by using the heat pipe and the heat dissipation performance of the cooling body can be improved, and the heat insulating portion deaerated and sealed can be used from the surface of the cooling body. Heat dissipation to the inside of the housing can be cut off, and the performance and reliability of the power conversion device can be ensured.
According to the invention described in claim 2, since the heat insulating part does not need to be deaerated, the performance of the heat insulating part can be easily maintained, and the heat insulating performance and cost can be optimized by appropriately selecting an inorganic material to be filled. it can.
According to the third aspect of the invention, it is easy to cover the entire surface of the cooling body, the heat dissipation performance of the entire cooling body can be further enhanced, and heat dissipation into the housing can be further suppressed.
According to the invention described in claim 4, by integrating the heat conductor into the base plate of the heat sink, the number of parts can be reduced and the assembly workability can be improved.
According to the fifth aspect of the present invention, the thermal conduction between the thermal conductor and the base plate can be improved by applying the thermal compound or the thermal conductive grease between the thermal conductor and the base plate.
According to the invention described in claim 6, by applying the heat sink according to any one of claims 1 to 4 to a power conversion device such as an inverter device, a remarkable cooling effect can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a power conversion device according to a first embodiment of the present invention, and FIG. 2 is a side sectional view of plate-like heat conductors 30a and 30b. Note that the description of the same constituent elements of the present invention as those of the prior art will be omitted, and different points will be described. Also, the illustration of the printed circuit board on which the electronic components arranged in the housing are mounted and the electrolytic capacitor is omitted.
In FIG. 1, 30a, 30b and 30c are flat plate heat conductors, 31 is a heat conductor, 32 is a heat insulating part, 33 is a heat pipe, and 34 is a hole part of the heat insulating part.
The present invention is different from the first embodiment as follows.
That is, near the position where the heating element 1 is attached along the heating element mounting surface of the base plate 11, copper, aluminum, or the like formed by dividing a thin flat plate-like sealed container into two chambers in the thickness direction of the base plate 11. The heat conductors 30a, 30b, and 30c made of a metal having good heat conductivity are provided, and the heat conductors 30a, 30b, and 30c are all provided as latent heat of vaporization in one room of the sealed container. A heat pipe 33 that encloses a condensable working fluid that transports heat and is in contact with the base plate 11 side, and the other chamber of the sealed container using a heat evacuation method, a vacuum pump, or the like. And a heat insulating portion 32 that is sealed in a state where a non-condensable fluid is deaerated, and is integrated with each other.
Specifically, the heat conductors 30a, 30b, and 30c are brazed between two U-shaped members formed by an appropriate method such as forging, casting, and machining by cutting, and one flat plate. Alternatively, the sealed container is formed by joining with a heat-resistant adhesive or welding.
In addition, the heat pipe 33 forms a structure that functions as a wick by processing a narrow groove on the inner surface of the sealed container constituting the pipe or inserting a porous thin plate, such as Freon gas, water, ethanol, etc. A condensable fluid is enclosed to increase heat conduction in the longitudinal direction along the base plate 11 of the heat sink 10.
In addition, you may comprise the heat insulation part 32 filled with the inorganic material of low heat conductivity, such as quartz and a glass grain, instead of deaeration.
Further, the flat heat conductor 31 and the surface of the base plate 11 are machined or polished to improve the flatness and the surface roughness, thereby improving the adhesion. Further, the heat between the heat conductor 31 and the base plate 11 is improved. Good compound and grease are applied for the purpose of improving transmission.

Next, the operation will be described.
For example, in the power conversion device such as an inverter shown in FIG. 5, the AC power input to the device is converted into DC by a diode module, smoothed by the electrolytic capacitor 3, and then the IGBT is controlled by an electronic circuit formed on the printed circuit board 2. Then, it operates to convert to AC output. When the heat sink of the present invention shown in FIG. 1 is applied to the power converter shown in FIG. 5, the heat generated from the heating element 1 composed of the semiconductor elements described above is transferred to the base plate 11 and transferred to the base plate 11. When a part of the heat is transmitted to the heat pipes 33 of the plate-like heat conductors 30a and 30b, the heat pipes 33 are operated due to a temperature difference generated therein. Specifically, in FIG. 2, the working fluid evaporates in the heating section (evaporating section) of the heat pipe 33, and the working fluid vapor flows to the cooling section of the heat pipe 33 to dissipate heat, condense, and condense. The liquid is refluxed to the heating part by the capillary action of the wick in the sealed container, whereby heat is transferred from the heating part to the cooling part as latent heat of the working fluid. In this way, the heat transferred to a part of the surface of the base plate 11 is dispersed in the plane direction of the surface of the base plate 11 by the heat transport function of the heat pipe. For this reason, the heat dispersed in the plane direction of the surface of the base plate 11 is radiated over the entire longitudinal direction of the radiating fins 12 without being radiated into the housing, and the heat sink 10 for the power conversion device Effective cooling performance is improved.

Therefore, in the first embodiment of the present invention, the heat conductor composed of the heat pipe and the heat insulating portion is provided in the vicinity of the heating element on the base plate by dividing the flat airtight container into two chambers in the thickness direction. , Heat transfer from the base plate to the heat radiating fins using heat pipes, heat radiation performance can be improved, and heat radiation to the inside of the housing can be blocked using heat insulation parts, ensuring the performance and reliability of the power converter can do.
Also, instead of degassing the heat insulation part, filling with low thermal conductivity inorganic materials such as quartz and glass particles makes it easy to maintain the heat insulation performance and optimizes the heat insulation performance and material cost by selecting the material to be filled appropriately Can be

FIG. 3 is an overall perspective view showing the configuration of the second embodiment of the present invention.
What is different between the second embodiment and the first embodiment. A hole 34 that is slightly larger than the heating element 1 is provided on the heat insulating portion side of the flat plate-like heat conductor 30c to expose the heat pipe 31. A flat heat conductor 30c is attached with the heat pipe 31 side in contact with the base plate 11. The heating element 1 is attached in contact with the heat pipe of the flat heat conductor 30c through the hole 34 of the heat insulating part. By doing so, it becomes easy to cover the entire surface of the base plate 11 without a gap, and the heat dissipation performance of the entire cooling body can be further enhanced, and heat dissipation into the housing can be further suppressed.
FIG. 4 is an enlarged side sectional view of a main part of the heat sink according to the second embodiment.
The heating element 1 is in contact with the heat pipe 11 of the flat plate-like heat conductor 30c through the hole 34 of the heat insulating part. The flat heat conductor 30c is attached with the heat pipe side in contact with the base plate 11, and the heat radiating fins 12 are attached to the base plate 11.
The heat conductor 31 including the heat insulating portion and the heat pipe may be bonded to the base plate 11 of the heat sink as a cooling body by bonding, brazing, or the like, or may be embedded and integrated. The number of points can be reduced and the assembly workability can be improved.

1 is an overall perspective view of a power conversion device according to a first embodiment of the present invention. It is a sectional side view of the flat heat conductor of this invention. It is a whole perspective view which shows the structure of 2nd Example of this invention. It is a sectional side view of the power converter device of 2nd Example. It is a disassembled perspective view of the conventional power converter device. In the conventional power conversion device, (a) shows a layout of heating elements when the heat sink is viewed from above, and (b) shows a temperature distribution diagram on the base plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat generating body 2 Printed circuit board 3 Electrolytic capacitor 10 Heat sink 11 Base plate 12 Radiation fin 20 Case 30a, 30b, 30c Flat plate heat conductor 31 Heat conductor 32 Heat insulation part 33 Heat pipe 34 Hole

Claims (6)

In a heat sink having a base plate for mounting a heating element, and a plurality of heat dissipating fins disposed on the side opposite to the heating element mounting surface of the base plate,
A heat conductor formed by dividing a flat airtight container into two chambers in the thickness direction of the base plate is provided in the vicinity of the position where the heating element is attached along the heating element mounting surface of the base plate, The heat conductor encloses a condensable working fluid that transports heat as latent heat of vaporization in one chamber of the sealed container, and is in contact with the base plate side, and the other of the sealed container A heat sink comprising: a heat insulating portion formed by sealing a non-condensable fluid in a deaerated state in the room.   2. The heat sink according to claim 1, wherein the heat insulating portion of the heat conductor is made of an inorganic material having low heat conductivity.   2. The heating element according to claim 1, wherein the heating element is arranged by providing a hole part slightly larger than the heating element in the heat insulating portion of the heat conductor, and the heating element is directly brought into contact with the heat pipe. heatsink.   The heat sink according to claim 1, wherein the heat conductor is integrated with a base plate of the heat sink.   2. The heat sink according to claim 1, wherein a thermal compound or a thermal conductive grease is applied between the thermal conductor and the base plate to improve heat transferability.   The power converter device provided with the heat sink of any one of Claims 1-5.

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