JP4999071B2 - heatsink - Google Patents

Description

  The present invention relates to a cooling device used for cooling an element to be cooled such as a semiconductor element, and more particularly to a heat sink with a piezoelectric element.

  High heat sinks with excellent heat dissipation efficiency are required due to increased heat generation and heat generation density of CPUs, elements, etc., while heat generation used for general-purpose PCs used in offices is large. There is a need for heat sinks that can be easily manufactured at low cost for CPUs that do not. Conventionally, in order to meet this demand, a heat sink is often used to cool a semiconductor element by natural air cooling using an extruded aluminum heat sink. If the cooling performance is insufficient, for example, a heating element is provided on one side. An electric motor equipped with a centrifugal fan on the side or top surface of the heat sink so that the cooling air passes between the heat sink fins with respect to the heat sink formed by joining the heat sink fins to the other surface of the heat receiving plate that is thermally connected A fan was attached and the cooling air was forcibly sent between the radiating fins by the rotation of the fan to dissipate the heat transmitted from the heating element into the atmosphere.

  Furthermore, heat is transferred to a position away from the heat receiving plate to which the heating element is thermally connected by a heat pipe in which one end is thermally connected to the heat receiving plate and a heat radiating fin is attached to the other end. Therefore, an electric fan for forced cooling is attached to the radiating fin, and cooling air is forcibly sent between the radiating fins by the rotation of the fan to dissipate the heat transmitted from the heating element into the atmosphere.

  Further, as disclosed in JP-A-8-330488, there has been proposed a heat sink that uses a piezoelectric element without using a fan.

JP-A-8-330488

  The heat sink using the electric fan described above requires a space to install a fan motor and fan case that blows to the heat radiating fins around the heat sink, and is compatible with environments that are used in a thin and compact state. In order to do so, the space for the radiating fins must be narrowed, and sufficient space for obtaining the required heat radiating performance cannot be taken.

  Furthermore, when the fins are arranged in parallel on the heat receiving plate at a fine pitch, the heat loss of the heat sink increases. Therefore, a large fan is required to flow a predetermined air volume, and thus the apparatus needs to be enlarged, and cannot be adapted to the environment in which it is used, and fan noise increases. Further, in order to flow a predetermined air volume, it is necessary to rotate the fan at a high speed, which causes a problem that fan noise increases.

  In the heat sink disclosed in Japanese Patent Laid-Open No. 8-330488, a piezoelectric fan is separately attached. In this case, a piezoelectric element and a vibration element for generating cooling air are required to configure the fan. Thus, there are problems that the number of members increases and it is difficult to reduce the cost.

  Accordingly, an object of the present invention is to provide a heat sink that is low in noise and excellent in cooling performance and high in reliability while realizing low cost and light weight.

The inventor has conducted extensive research to solve the above-described conventional problems. As a result, one end is connected to the heat receiving plate, and a heat radiating fin (fin plate) is inserted into the other end and fixed to the other end of the heat pipe. By attaching the element and vibrating the heat pipe, the working fluid in the heat pipe can be made to flow easily, heat dissipation efficiency can be improved, and the electric fan can be made to vibrate by oscillating the heat dissipation fin by the vibration element. It was found that the heat dissipation performance was improved without using it.
The present invention has been made based on the research results described above.

According to a first aspect of the heat sink of the present invention, a heat receiving plate in which a heat source is thermally connected to one surface, one end portion is thermally connected to the heat receiving plate, and one end to the other end At least one heat pipe that transfers heat to a portion, a plurality of metal fin plates that are thermally connected to the other end of the heat pipe, and a vicinity of the fin plate where the heat pipe is fixed It is a heat sink provided on the fin plate and provided with a vibration element that vibrates the heat pipe and the fin plate.

  According to a second aspect of the heat sink of the present invention, the one end of the heat pipe is embedded in the heat receiving plate, and a plurality of rectangular fin plates are arranged in parallel at the other end of the heat pipe. It is a heat sink that is inserted and fixed.

A third aspect of the heat sink of the present invention is a heat sink in which two vibration elements are arranged in parallel on one surface of the fin plate so as to contact the upper surface and the lower surface of the heat pipe.

A fourth aspect of the heat sink according to the present invention is a heat sink in which each frequency of the vibration element is adjusted to be approximately a resonance frequency of the fin plate.

A fifth aspect of the heat sink according to the present invention is a heat sink adjusted so that each of the vibration elements operates in the same phase.

A sixth aspect of the heat sink of the present invention is a heat sink in which the vibration element is made of a piezoelectric element such as a piezoelectric element.

A seventh aspect of the heat sink of the present invention is a heat sink further comprising a drive circuit for driving the vibration element.

According to an eighth aspect of the heat sink of the present invention, a thermoelectric conversion element is incorporated between the heat source and the heat receiving plate to form the drive circuit, and power is generated by a temperature difference between the heat source and the heat receiving plate. And a heat sink for driving the vibration element.

According to the heat sink of the present invention, the condensing part of the heat pipe is vibrated by the vibration element, so that the flow of the working fluid in the heat pipe can be facilitated, the heat radiation performance can be enhanced, and the heat radiation fin is vibrated substantially. Since the cooling air is generated, there is no need for a space for installing an electric (cooling) fan for blowing air between the radiating fins, and the space for the radiating fins can be increased accordingly, so that the cooling performance is improved.
Furthermore, since an operating part such as a fan motor for an electric fan is not required, the reliability of the cooling module is improved. Furthermore, since a fan motor for an electric fan is not required, the cooling module can be reduced in size and weight. Furthermore, since a diaphragm for generating cooling air is not required, the number of members is reduced and the configuration is simplified.

The heat sink of the present invention will be described with reference to the drawings.
One aspect of the heat pipe of the present invention includes a heat receiving plate in which a heat source is thermally connected to one surface, one end portion is thermally connected to the heat receiving plate, and one end portion to the other end. At least one heat pipe that transfers heat to a portion, a plurality of metal fin plates that are thermally connected to the other end of the heat pipe, and a vicinity of the fin plate where the heat pipe is fixed It is a heat sink provided with the vibration element which is provided in the part and vibrates the heat pipe and the fin plate.

  One end portion of the heat pipe is embedded in the heat receiving plate, and a plurality of rectangular fin plates are arranged in parallel and fixed to the other end portion of the heat pipe, in the vicinity of the heat pipe to be inserted. It is preferable that the vibration element is provided on the fin plate, and in particular, on one surface of the fin plate, the two vibration elements are arranged in parallel so as to contact the upper surface and the lower surface of the heat pipe.

  FIG. 1 is a perspective view showing one embodiment of the heat sink of the present invention. As shown in FIG. 1, the heat sink of the present invention has a heat receiving plate 2 in which a heat source (not shown) is thermally connected to one surface, and one end portion is thermally connected to the heat receiving plate 2, A heat pipe 3 that transfers heat from one end to the other end (three heat pipes are arranged in parallel in the figure), and a plurality of heat pipes that are thermally connected to the other end of the heat pipe 3 The heat sink includes a metal fin plate 4 and a vibration element 5 that is provided in the vicinity of the fin plate 4 where the heat pipe 3 is fixed and vibrates the heat pipe and the fin plate.

  That is, a heat source (not shown) such as a CPU is provided on one surface of a heat receiving plate 2 made of metal such as copper or aluminum having excellent thermal conductivity through a thermal interface material (TIM) such as thermal conductive grease. Connected. The metal heat receiving plate 2 is formed with a hole that is approximately the same size as the heat pipe, and one end of the heat pipe is embedded in the hole. One end of the heat pipe and the heat receiving plate are thermally connected so that heat conduction is performed well. In order to effectively transfer the heat of the heat receiving plate to the heat pipe, it is preferable that one end of the heat pipe is arranged over the entire heat receiving plate.

  In FIG. 1, the distance between the heat receiving plate 2 and the fin plate is shortened, but the distance between the two can be appropriately selected depending on the arrangement of components and the like so as to suit the situation. At the other end of the heat pipe 3, a plurality of thin plate-like fin plates 4 provided with vibration elements 5 are thermally connected and fixed. In FIG. 1, three heat pipes are arranged in parallel, and the fin plate is inserted in a state where the three heat pipes are arranged in parallel.

  Each fin plate arranged in parallel vibrates the condensing part of the heat pipe to facilitate the flow of the working fluid in the heat pipe, and to vibrate each fin plate to generate cooling air. 5 is provided. In selecting the position where the vibration element is provided in each fin plate, it is preferable that the vibration of the condensing part of the heat pipe and the vibration of the fin plate can be effectively performed.

  A space serving as a flow path for the working fluid is provided inside the heat pipe, and heat is moved by the phase change or movement of the working fluid accommodated in the space such as evaporation and condensation. That is, on the heat absorption side of the heat pipe, the working fluid evaporates due to the heat generated by the parts to be cooled that are conducted through the material of the container constituting the heat pipe, and the vapor moves to the heat radiation side of the heat pipe. To do. On the heat radiating side, the working fluid vapor is cooled and returned to the liquid phase again. The working fluid that has returned to the liquid phase in this way moves (refluxs) again to the heat absorption side. Heat is transferred by such phase transformation and movement of the working fluid.

  During such phase transformation and movement of the working fluid, if a liquid film is formed on the inner wall of the heat pipe, the flow of the working fluid is hindered and heat dissipation performance is degraded. In the heat sink of the present invention, in particular, the condensing part of the heat pipe is vibrated by the vibration element, the liquid film is removed, the flow of the working fluid is facilitated, and the heat radiation performance is improved.

  FIG. 2 is a diagram illustrating details of the fin plate provided with the vibration element. As shown in FIG. 2, a heat pipe is inserted in the center of the fin plate, and a protruding portion 6 is formed in a cylindrical shape by extrusion or the like in order to facilitate heat conduction between the heat pipe and the fin plate. Has been. The contact area with the heat pipe is expanded by the inner wall portion of the protrusion 6. The vibration element 5 is provided in direct contact with the vicinity of the protrusion 6 of the fin plate, preferably the peripheral edge of the protrusion 6. The vibration element 5 is disposed substantially in parallel on both the upper and lower sides of the protrusion 6.

  FIG. 3 is a perspective view for explaining the heat sink in operation. As described with reference to FIG. 1 and FIG. 2, current is applied to the vibration element 5 arranged in parallel above and below the protrusion 6 of the fin plate thermally bonded to the other end of the heat pipe of the heat sink 1. As shown in FIG. 3, the upper end and the lower end of the fin plate 4 vibrate in the major axis direction of the heat pipe 3 due to resonance. At the same time, the condensing part of the heat pipe 3 is vibrated by the vibration element 5 to remove the liquid film formed by the working fluid inside the heat pipe 3, and the working fluid condensed and returned to the liquid phase becomes the heat absorbing part (heat receiving plate 2 Side) to improve the heat dissipation performance.

  The vibration element 5 is an element in which a piezoelectric material (dielectric material) is sandwiched between two electrodes. When an alternating current is passed through the electrodes of the vibration element 5 (or a direct current is passed intermittently (repeated connection / disconnection)), the vibration element 5 vibrates at a predetermined frequency. When the frequency of the vibration element 5 is set to be approximately the same as the resonance frequency of the fin plate 4, the fin plate 4 can be vibrated with a large amplitude with a small amount of electric power. Furthermore, by setting each vibration element 5 to operate in the same phase, the adjacent fin plates 4 can be vibrated so as not to be buffered by vibration.

  In this manner, the fin plate is vibrated by the vibration element, whereby cooling air is generated around the fin plate, and heat from the heat source is radiated through the fin plate by the cooling air. At this time, by designing so that the resonance frequency of the entire heat sink and the resonance frequency of the fin plate are different, by vibrating the fin plate, the entire heat sink resonates to prevent problems such as destruction of the semiconductor element. Can do. Since the fin plate is fixed to the heat pipe at the center, and the vibration elements are arranged at both the upper and lower ends of the heat pipe, the upper end and the lower end of the fin plate operate separately.

  FIG. 4 is a perspective view showing another embodiment of the heat sink of the present invention. In this aspect, the heat sink further includes a drive circuit that drives the vibration element. That is, for example, a thermoelectric conversion element is incorporated between the heat source and the heat receiving plate to form a drive circuit, and electric power is generated by a temperature difference between the heat source and the heat receiving plate to drive the vibration element.

  As shown in FIG. 4, vibration is caused by passing an electric current through the vibration elements 5 arranged in parallel above and below the protrusions 6 of the fin plate 4 thermally joined to the other end of the heat pipe 3 of the heat sink 1. The vibration element 5 and the fin plate 4 are caused to resonate so that the upper end portion and the lower end portion of the fin plate 4 vibrate in the major axis direction of the heat pipe 3. At the same time, the condensing part of the heat pipe 3 is vibrated by the vibration element 5 to remove the liquid film formed by the working fluid inside the heat pipe 3. Thermoelectric conversion elements 8 are arranged between the heat source 7 such as a CPU and the surface of the heat receiving plate 2 and are thermally connected to each other.

  The thermoelectric conversion element 8 is an element using an electromotive force (Seebeck effect) generated by a temperature difference. That is, the thermoelectric conversion element is manufactured by combining a p-type semiconductor material and an n-type semiconductor material, and connects both ends of two types of semiconductor materials, a p-type semiconductor material and an n-type semiconductor material, and keeps both ends at different temperatures. Current flows through the circuit. A thermoelectric conversion element based on the Seebeck effect directly converts thermal energy into electrical energy due to a temperature difference by setting one of a p-type semiconductor element and an n-type semiconductor element to a low temperature and the other to a high temperature. A heat source unit such as a CPU is cooled by driving the vibration element to vibrate by heat absorption of the thermoelectric conversion element and electricity obtained by the thermoelectric conversion element, and vibrating the fin plate by resonance to dissipate heat.

As described above, according to this aspect, the heat source 7 such as the CPU can be cooled only by applying a small amount of electric power from the outside, and can be cooled without using a special control system.
Next, the heat sink of the present invention will be described in more detail by way of examples.
As shown in FIG. 1, one end of three heat pipes was embedded in a heat receiving plate having a size of 40 mm × 40 mm and a thickness of 8 mm, which diffuses heat from a heat source such as a CPU. A 36 W heat source is used, and the heat source and the heat receiving plate are thermally connected to each other through a heat conductive grease. A fin plate with a size of 30 mm x 60 mm and a thickness of 0.5 mm that emits heat is attached to three heat pipes arranged in parallel, and a piezoelectric element that converts electrical signals into vibration is fixed to the heat pipe. It was provided at the upper and lower portions of the protruding portion of the fin plate.

  An alternating current having a power of 500 mW was applied to the piezoelectric element, and the piezoelectric element was vibrated at a frequency of 154 Hz. The piezoelectric element was set to operate in the same phase. Resonating with the vibration of the piezoelectric element, the upper and lower ends of the fin plate vibrate, and cooling air is generated around the fin plate. The heat of the heat source is radiated through the fin plate by the cooling air. At the same time, the condensing part of the heat pipe vibrated to facilitate the flow of the working fluid. As a result, the operating temperature of the heat source could be maintained at 80 ° C. or lower.

Further, another embodiment in which a thermoelectric conversion element is used as power for the vibration element will be described below.
As shown in FIG. 4, one end of three heat pipes was embedded in a heat receiving plate having a size of 40 mm × 40 mm and a thickness of 8 mm that diffuses heat from a heat source such as a CPU. A 36 W heat source is used, and the heat source and the heat receiving plate are thermally connected to each other through a heat conductive grease. A fin plate with a size of 30 mm x 60 mm and a thickness of 0.3 mm for releasing heat is attached to three heat pipes arranged in parallel, and a piezoelectric element that converts an electric signal into vibration is fixed to the heat pipe. It was provided at the upper and lower portions of the protruding portion of the fin plate. Furthermore, a thermoelectric conversion element was disposed between the heat source and the heat receiving plate, and these were thermally connected via a heat conductive grease.

  A circuit was formed between the thermoelectric conversion element and the piezoelectric element, the electric power generated by the thermoelectric conversion element was applied to the piezoelectric element, and the piezoelectric element was vibrated at a frequency of 154 Hz. Resonating with the vibration of the piezoelectric element, the upper and lower ends of the fin plate vibrate, and cooling air is generated around the fin plate. The heat of the heat source is radiated through the fin plate by the cooling air. At the same time, the condensing part of the heat pipe vibrated to facilitate the flow of the working fluid. As a result, the operating temperature of the heat source could be maintained at 80 ° C. or less simply by applying 300 mW of electric power of the piezoelectric element from another power source.

  According to the present invention, there is no need for a space for installing an electric (cooling) fan for blowing air between the radiating fins, and the space for the radiating fins can be increased accordingly, so that the cooling performance is improved. Furthermore, since an operating part such as a fan motor for an electric fan is not required, the reliability of the cooling module is improved. Furthermore, since a fan motor for an electric fan is not required, the cooling module can be reduced in size and weight. Furthermore, since a diaphragm for generating cooling air is not required, the number of members is reduced and the configuration is simplified.

FIG. 1 is a perspective view showing one embodiment of the heat sink of the present invention. FIG. 2 is a diagram illustrating details of the fin plate provided with the vibration element. FIG. 3 is a perspective view for explaining the heat sink in operation. FIG. 4 is a perspective view showing another embodiment of the heat sink of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat sink 2 of this invention Heat receiving plate 3 Heat pipe 4 Fin plate 5 Vibrating element 6 Protrusion part 7 Heat source 8 Thermoelectric conversion element

Claims (8)

A heat receiving plate having a heat source thermally connected to one surface, and at least one heat having one end thermally connected to the heat receiving plate and transferring heat from one end to the other end; a pipe, a plurality of metallic fin plates thermally connected to the other end of the heat pipe, provided in the fin plate in the vicinity of the heat pipe of the fin plate is fixed, the heat A heat sink comprising a pipe and a vibration element that vibrates the fin plate.   The one end portion of the heat pipe is embedded in the heat receiving plate, and a plurality of rectangular fin plates are arranged in parallel and inserted and fixed to the other end portion of the heat pipe. The heat sink according to 1. The heat sink according to claim 1 or 2, wherein two vibration elements are arranged in parallel so as to contact an upper surface and a lower surface of the heat pipe on one surface of the fin plate . The heat sink of Claim 3 adjusted so that each frequency of the said vibration element may become the substantially resonant frequency of the said fin plate . The heat sink according to claim 3 or 4 , wherein each of the vibration elements is adjusted to operate in the same phase . The heat sink according to claim 1, wherein the vibration element is a piezoelectric element such as a piezo element . The heat sink according to any one of claims 1 to 6, further comprising a drive circuit that drives the vibration element . A thermoelectric conversion element is incorporated between the heat source and the heat receiving plate to form the drive circuit, and electric power is generated by a temperature difference between the heat source and the heat receiving plate to drive the vibration element. Item 8. The heat sink according to Item 7 .

Images