JP2003198170A - Cooler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooler of electronic component in which dissipation performance of heat generated from an electronic component can be enhanced. <P>SOLUTION: The cooler comprises a suction fan 5 fixed to the side face of a heat sink having a plurality of fins 3 formed on a heat transfer plate 2, and a cover 4 fixed to the upper surface of the heat sink wherein the cover 4 is positioned only in the region of 1/3 to 2/3 of the width of the heat sink from the left end thereof in the widthwise direction of the heat sink to cover the overall length thereof in the longitudinal direction. Since air from the fan 5 spreads to the fins 3 entirely and pressure loss of air flow is reduced, a sufficient volume of air can be ensured and the flow rate of air can be increased resulting in the enhancement of heat dissipation performance. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat sink used for cooling a semiconductor such as a micro processing unit (hereinafter abbreviated as MPU) used in a personal computer or the like which generates heat, or an electronic component having other heat generating portion. And a cooling device that cools the heating element by combining a fan and other blowing means with the heat sink.

[0002]

2. Description of the Related Art In recent years, in electronic equipment, in order to ensure normal operation of electronic parts, the electronic parts such as semiconductors have been highly integrated and the operating clock has been increased in frequency to increase the heat generation amount. How to keep the contact temperature of parts within the operating temperature range has become a big problem. In particular, high integration and high frequency of a micro processing unit (hereinafter abbreviated as MPU) are remarkable, and heat dissipation measures have become an important issue in terms of stability of operation and ensuring of operation life.

In general, a cooling device for cooling a heating element such as an MPU has a heat sink for contacting the heating element and spreading heat from the heating element to efficiently exchange heat with a refrigerant such as air. It is made by a fan with a motor for forcibly sending a refrigerant such as air.
A cooling device in which a fan is attached to a heat sink is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-153573. Here, a fan is attached to the upper surface of the heat sink to cover the outer periphery of the fins for efficient cooling.

An example of another conventional cooling device is shown in FIGS.
It shows in FIG.

FIG. 7 is a perspective view showing a conventional cooling device, and FIG.
Is a velocity distribution diagram of air of the conventional cooling device shown in FIG. 7A, and FIG. 9 is a velocity distribution diagram of air of the conventional cooling device shown in FIG. 7B.

FIG. 7 (a) is a perspective view showing a conventional cooling device having a structure in which a cover is not attached to the upper surface. Further, FIG. 7B is a perspective view showing a conventional cooling device having a structure in which a cover is attached to the entire upper surface.

In FIGS. 7 (a) and 7 (b), reference numeral 2 is a heat transfer plate that contacts a heat generating element (not shown) to spread the heat of the heat generating element, and 3 is a surface of the heat transfer plate 2 that does not contact the heat generating element. It is a fin that has been established from multiple. Here, the combination of the heat transfer plate 2 and the fins 3 is referred to as a heat sink, 5 is a blower fan attached to the side surface of the heat sink to take in air from the outside and send air to between the fins, and 6 take air from between the fins to the outside. A suction fan that sends air,
Reference numeral 4 is a cover attached to the upper surface of the heat sink.

In order to facilitate the description, the heat sink width direction is the X direction, the heat sink length direction is the Y direction, and the heat sink height direction is shown in addition to the partial representation as shown in the drawings. We will also use expressions such as Z direction.

Generally, a heat sink is mainly composed of a material having a high thermal conductivity such as aluminum or copper, and is subjected to a method such as extrusion molding (also called pultrusion molding), cold forging, die casting and thin plate lamination. Is manufactured in. A combination of this heat sink with a fan and a cover is called a cooling device.

In such a cooling device, the heat transfer plate 2
It is used by bringing a heating element into contact with the lower surface of the. The cooling principle of the actual cooling device is that the heat generated in the heating element passes through the heat transfer plate 2 having a high heat transfer property such as aluminum and the fins 3
The heat is transferred to the air sent from the fan on the surfaces of the fins 3 to be dissipated into the air and cooled.

Generally, in a cooling device in which a fan is attached to the side surface of a heat sink, if the fan is a blow-in fan as shown in FIG. 7 (a), a cover is not attached on the upper surface of the heat sink, but as shown in FIG. 7 (b). In the case of a suction fan, the cover is often entirely covered on the upper surface of the heat sink.

[0012]

However, in the case of electronic parts such as semiconductors, the heat generation tends to increase more and more due to the further increase in speed, and when the cooling device of the conventional structure is used, sufficient cooling is achieved. It has become difficult to perform the above, and especially with high heat-generating electronic components such as MPU, the performance cannot be fully exhibited,
Alternatively, thermal runaway or the like occurs, causing problems such as abnormalities in electronic devices. Although a method of increasing the cooling capacity by increasing the cooling device itself as the amount of heat generation increases can be considered, the size and weight of the cooling device are naturally limited by the size of the electronic device itself.

In order to improve the performance of the cooling device, it is most desirable that the air flow generated by the fan be spread over the entire fins so that heat can be radiated from all the fins.

FIG. 8 is an air velocity distribution chart of the conventional cooling device shown in FIG. 7 (a).

FIG. 8 (a) is a front view of a conventional cooling device in which a blower fan is attached to the side surface of the heat sink shown in FIG. 7 (a), and the graph above the front view shows the fin front part (fan FIG. 8 is a velocity distribution diagram in the Z direction at the X coordinate position of the air flowing out from between the fins on the side).

Here, in order to simplify the description, in the following expression, as shown in FIG. 8A, a region from the left end of the heat sink to less than 1/3 of the width (X direction) of the heat sink is located. The space between the fins is referred to as an XL region, the left end to 1/3 or more and less than 2/3 is referred to as an XM region, and the heat sink right end to 1/3 is referred to as an XR region.

FIG. 8 (b) is a Y-1 sectional view of the conventional cooling device shown in FIG. 7 (a) in the Y direction, showing the flow of air between the fins in the XL region. The graph above shows Y of air flowing out from between the fins on the top of the heat sink.
FIG. 7 is a velocity distribution diagram in the Z direction of coordinate positions, and the right graph is a velocity distribution diagram in the Y direction of air flowing out from between the fins on the rear surface of the heat sink (on the side opposite to the fan attachment portion) to the outside.

FIG. 8C is a Y-2 cross-sectional view in the Y direction of the conventional cooling device shown in FIG. 7A, showing the flow of air between the fins in the XR region. The graph above shows the Z of air flowing out from between the fins on the top of the heat sink.
It is a velocity distribution diagram in the direction, and the graph on the right is a velocity distribution diagram in the Y direction of the air flowing out from between the fins on the rear surface of the heat sink to the outside.

Here, the inflow direction of the air flowing between the fan and the fin will be considered with reference to FIG. The rotation direction of the fan is a clockwise direction shown by an arrow, and air is taken in from the outside and blown between the fins. The direction of air flowing from the fan to the space between the fins is roughly XL, X when considering where the fins are located in the fan.
It is classified into three areas, M and XR.

In the XL region, the direction of rotation of the fan located here is from the lower fins to the upper fins, so the air flowing between the fins in this region is in the direction from the lower fins to the upper fins. Further, in the XM region, the direction of rotation of the fan located here is in the direction substantially perpendicular to the fin wall surface (X direction), so the air flowing between the fins in this region is in the heat sink length direction (Y direction). Although it is in the heading direction, the collision with the fin wall surface is repeated and the flow velocity becomes extremely small. Furthermore, in the XR region, the direction of rotation of the fan located here is from the upper fins to the lower fins, so the air flowing between the fins in this region is in the direction from the upper fins to the lower fins.

Considering the velocity in the Z direction of the air flowing outward from between the fins at the front of the fins on the upper surface of the heat sink, the flow velocity is particularly high in the XL region as shown in FIG. Then, the flow velocity suddenly decreases, and X
In the R region, there is a slight inflow direction. In this way, on the outlet side of the blowing fan, a nonuniform flow having a high flow velocity and a strong directivity is partially generated.

On the other hand, considering the flow of air between the fins in the lengthwise direction of the heat sink (Y direction), as shown in FIG. 8B, in the Y1 cross section which is the XL region, the air flowing from the fan to the space between the fins. Since the direction of is diagonally upward, it flows out intensively from the front part of the fin on the upper surface of the heat sink. Further, on the rear surface of the heat sink, the flow velocity at the upper part of the fin is high, and it rapidly decreases as it goes to the lower part of the fin. Therefore, air tends to flow intensively in the upper part of the fin, but it becomes difficult for air to flow in the lower part of the fin near the heating element and at a high temperature, and as a result, the entire radiation fin does not function effectively.

As shown in FIG. 8C, Y which is an XR region
In the two cross sections, the direction of the air flowing from the fan to the space between the fins is obliquely downward, the velocity distribution in the Z direction is almost small on the upper surface of the heat sink, the front direction is the flowing direction, and the rear direction is the flowing direction. Further, on the rear surface of the heat sink, the flow velocity under the fins is high and decreases slightly toward the top of the fins.

Next, a conventional technique when the fan is used for suction will be described. FIG. 9 is a velocity distribution diagram of the air of the conventional cooling device shown in FIG. 7B, and FIG.
Fig. 4 is a front view of the conventional cooling device using the suction fan shown in Fig. 7 in the case where the cover is not attached, and the upper graph is a velocity distribution diagram in the Z direction of the air flowing from the outside to the space between the fins on the upper surface of the heat sink. is there.

FIG. 9B is a cross section in the Y direction when the cover is not attached in the conventional cooling device using the suction fan shown in FIG. 7B, showing the flow of air between the fins. is there. The upper graph is the velocity distribution diagram of the air flowing from the outside to the fins on the top of the heat sink in the Z direction, and the right graph is the velocity distribution diagram of the air flowing from the outside to the fins on the rear face of the heat sink in the Y direction. is there.

Here, when the suction fan is used, XL when the blower fan shown in FIG. 8A is used,
It can be seen that the difference in velocity distribution depending on the location such as XM and XR is small.

FIG. 9C is a cross section in the Y direction when a cover is attached to the conventional cooling device using the suction fan shown in FIG. 7B, showing the flow of air between the fins. is there. The upper graph is the velocity distribution diagram of the air flowing from the outside to the fins on the top of the heat sink in the Z direction, and the right graph is the velocity distribution diagram of the air flowing from the outside to the fins on the rear face of the heat sink in the Y direction. is there.

Here, the inflow direction of the air flowing from the outside into the space between the fins will be considered with reference to FIG. Since the fan takes in air from between the fins and sucks it out to the outside, considering the velocity of the air in the front part of the fin on the upper surface of the heat sink, it does not depend on which area of the fan the fin is located as shown in FIG. 9A. As described above, the flow velocity is small as a whole and a uniform flow is generated in a wide range.

Considering the air flow in the heat sink length direction (Y direction) without the cover attached,
As shown in FIG. 9B, on the upper surface of the heat sink, the flow velocity from the front part is relatively large at the upper part of the fin and is uniform over a wide range. On the rear surface of the heat sink, as shown in the figure, the flow velocity is uniformly low from the upper part to the lower part of the fin, so there is a tendency that air does not spread to the lower part of the fin, which is close to the heating element and has a high temperature. It will not work.

On the other hand, if a cover is attached to the entire upper surface, a relatively large amount of air flow can be generated even under the fins that are close to the heating element and have a high temperature, as shown in FIG. 9C. However, if the entire surface of the heat sink is simply covered, the inflow area of air from the outside into the space between the fins is reduced, and the total inflow air amount of air itself is reduced, so that the cooling performance is deteriorated. Further, even when components such as a condenser are arranged at the rear of the heat sink, if the upper surface of the heat sink is entirely covered, the area where air flows in from the outside to between the fins is reduced and the cooling performance is reduced. In other words, simply arranging the cover on the entire surface is not effective.

As described above, the most important factor is whether or not the air can be efficiently spread over the widest possible range of fins without reducing the flow velocity of air between the fins as described above. It is necessary that a sufficient air inflow / outflow area is secured.

Therefore, even if a sufficient surface area is secured as the heat sink structure, a structure in which a velocity distribution sufficient to secure a sufficient air volume cannot be obtained cannot result in sufficient heat dissipation performance.

The present invention solves the above problems, and an object of the present invention is to provide a cooling device which improves the heat radiation performance of heat generated from a heating element and is excellent in cooling performance.

[0034]

A cooling device of the present invention comprises a heat transfer plate having a heat receiving surface which is in contact with a heating element as a lower surface, and a plurality of ventilation passages projecting to an upper surface opposite to the heat receiving surface. A cooling device comprising a heat sink provided with a plurality of fins to be formed, a fan serving as an air blower provided on a side surface of the heat sink, and a cover arranged to block the ventilation passage on the upper surface of the heat sink. The cover is ⅔ or more of the area of the upper surface of the heat sink and ⅔.
It is characterized by covering the following areas.

Further, in the cooling device of the present invention, the cover has a substantially rectangular shape, and is arranged over a heat sink length direction which is an air flow direction by the fan or a heat sink width direction which is orthogonal to the air flow direction. It is characterized by being

Further, in the cooling device of the present invention, the fan is a fan for blowing air into the heat sink, the cover is arranged over the entire length in the heat sink length direction, and the heat sink is provided. It is characterized in that it covers only the region of 1/3 or more and 2/3 or less of the width of the heat sink from the end portion of the upper surface on the side where the air outflow amount is large.

Further, in the cooling device of the present invention, the cover is arranged over the width of the heat sink, and is 1/3 or more from the mounting end of the fan with respect to the entire length in the length direction of the heat sink. It is characterized in that it covers only a region of 2/3 or less.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 has a heat transfer body having a surface to which a heat generating body can be attached, and a plurality of fins standing on the other surface of the heat transfer body to form an air passage. And a fan that blows along the ventilation path direction, and a cover that faces the standing surface of the fins of the heat transfer body and covers the ventilation path, and the area of the cover is the area of the standing surface of the fins of the heat transfer body. Is less than 1/3 and less than 2/3, and the air between the fins is received from the cover by setting the area of the cover to less than 1/3 and less than 2/3. Since the pressure loss can be reduced and the decrease in the flow rate can be prevented, the heat dissipation characteristics can be improved.

According to a second aspect of the present invention, a heat transfer body having a surface to which a heating element can be attached, a plurality of fins standing on the other surface of the heat transfer body to form a ventilation path, and a ventilation path. A fan that blows along the direction and a cover that faces the standing surface of the fins of the heat transfer body and covers the ventilation passage, and the length of one side of the cover is the side of the heat transfer body at the position where the cover is arranged. Is equal to the length of the heat transfer body and the lengths of the other sides are shorter than the lengths of the sides of the heat transfer body, and the pressure loss that the air flowing between the fins receives from the cover can be reduced and the air flow can be reduced. Since it is smooth and prevents a decrease in the flow rate, it is possible to improve the heat dissipation characteristics.

The invention according to claim 3 is characterized in that one side of the cover is arranged in contact with the fan.
In the described cooling device, the pressure loss that the air between the fins receives from the cover can be reduced and the flow rate can be prevented from decreasing.
The heat dissipation characteristics can be improved.

According to a fourth aspect of the present invention, a heat transfer body having a surface to which a heating element can be attached, a plurality of fins standing on the other surface of the heat transfer body to form a ventilation path, and a ventilation path. It has a fan that blows along the direction, and a cover that faces the standing surface of the fins of the heat transfer body and covers the ventilation passage, and the length of one side of the cover is the ventilation position of the heat transfer body at the position where the cover is arranged. A cooling device, characterized in that it is equal to the length of the side in the road direction, and the length of the other side is 1/3 or more and 2/3 or less of the length of the other side of the heat transfer body, Since the air blown into the space between the fins can be spread to the rear part of the fins, the heat dissipation characteristics can be improved.

The invention according to claim 5 is the cooling device according to claim 4, characterized in that the air blowing direction of the fan is the blowing direction into the ventilation passage formed by the plurality of fins. Since the air blown into the space can be spread to the rear part of the fin, the heat dissipation characteristics can be improved.

According to a sixth aspect of the present invention, there is provided a heat transfer body having a surface to which a heat generating element can be attached, a plurality of fins standing on the other surface of the heat transfer body to form a ventilation path, and a ventilation path. A fan that blows along the direction, and a cover that faces the standing surface of the fins of the heat transfer body and covers the ventilation passage, and the cover covers the entire width of the ventilation passage and the length of the fin in the direction of the ventilation passage. A cooling device characterized in that it is arranged from 1/3 or more of the length and 2/3 or less from the fan side end portion, and in the case of a blower fan, the air blown from the fan to the fins to the entire fins. It can be spread, and in the case of a suction fan, air can be sucked into the entire fin from the outside,
The heat dissipation characteristics can be improved.

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a perspective view of an essential part of a cooling device according to Embodiment 1 of the present invention. FIG.
It is a configuration example of a cover when using a blowing fan,
FIG. 1B is a perspective view of a main part of another cooling device according to the first embodiment of the present invention, in which the fan rotation direction and the cover disposition position are different.

FIG. 2 is a diagram showing the flow of air in the cooling device and the velocity distribution of the air flowing out to the outside in the first embodiment of the present invention. FIG. 2 (a) shows Y in FIG. 1 (a). It is a Y1 sectional view of the direction, and is a figure which shows the flow of the air between fins of XL area | region. The upper graph is the velocity distribution diagram in the Z direction for the air flowing out from between the fins on the top of the heat sink, and the right graph is the velocity distribution diagram in the Y direction for the air flowing out between the fins on the rear face of the heat sink. is there. Further, FIG. 2B is a Y2 cross-sectional view in the Y direction of FIG. 1A, showing an air flow between the fins in the XR region.
The upper graph is the velocity distribution diagram in the Z direction for the air flowing out from between the fins on the top of the heat sink, and the right graph is the velocity distribution diagram in the Y direction for the air flowing out between the fins on the rear face of the heat sink. is there.

1A, 1B, 2A, 2B
In the figure, reference numeral 1 is a heating element attached to the lower surface (surface in the negative Z-axis direction) of the heat transfer plate 2. Here, as the heating element 1, a semiconductor such as an IC, an LSI, an MPU, or an electronic component such as a transistor generates heat. The heat transfer plate 2 is made of a material having good heat conductivity, such as aluminum, aluminum alloy, copper, copper alloy, ceramics,
The heat generating element 1 is closely joined (not shown) to the heat transfer plate 2 substantially in the center thereof with a screw, a clip, an adhesive or the like, and is attached so that the heat of the heat generating element 1 can be efficiently transferred to the heat transfer plate 2. There is. 3 is the upper surface of the heat transfer plate 2 (the heating element 1
The fins 3 are formed on the surface opposite to the surface on which the is attached. The fins 3 transfer the heat of the heating element 1 through the heat transfer plate 2 to radiate the heat to the atmosphere. The fins 3 are plate-shaped and formed in the same direction. The fins 3 may be integrally formed with the heat transfer plate 2 or separately formed and attached together. The fins 3 are formed of a material having good thermal conductivity, such as aluminum, aluminum alloy, copper, copper alloy, ceramics, or the like. In this case, the heat sink is composed of the fins 3 and the heat transfer plate 2. Reference numeral 4 is a cover for covering the upper end surface of the fin 3 of the heat sink. The cover 4 is preferably a thin plate or foil of aluminum, copper, or an alloy thereof having good thermal conductivity, but thermal conductivity of synthetic resin such as plastic is used. Although it is not particularly good, it does not matter if the atmosphere does not leak. In the first embodiment, the cover 4 is arranged so as to cover the upper end surface of the fin 3 along the entire length in the length direction and to cover the half of the width of the heat sink in the heat sink width direction (X direction). It is fixed with a chemical, caulking, or welding. Reference numeral 5 is a blower fan that is attached to the side surface of the heat sink as a blower and blows a gas between the fins 3 along the fins 3. The blower fan 5 is an axial flow type in which the outer peripheral side of the blades is enclosed and is used efficiently between the plurality of fins 3. The atmosphere is blown to.

Considering the flow of air between the fins 3 in the heat sink length direction (Y direction), as shown in FIG. 2A, in the Y1 cross section which is the XL region, the front portion of the fin 3 (blow-in) is blown. Although the air flows diagonally upward on the fan 5 side), since the cover 4 is arranged on the upper surface of the heat sink, the air flow becomes horizontal toward the rear of the fin 3, and the velocity distribution of the air from the upper surface of the heat sink is It becomes zero. Further, on the rear surface of the heat sink, the flow velocity at the upper portion of the fin 3 is high, and gradually decreases toward the lower portion of the fin 3. Therefore, by disposing the cover 4, the flow velocity can be generated even in the lower portion of the fin 3 which is close to the heating element 1 and has a high temperature, and as a result, the entire radiation fin can effectively function.

Further, as shown in FIG. 2B, XR
In the Y2 cross section, which is the region, there is the heat transfer plate 2 that is diagonally downward at the front of the fins 3, but since there is a heat transfer plate 2, horizontal air flows toward the rear of the fins 3 and the velocity distribution in the Z direction on the upper surface of the heat sink. Is almost small, fin 3
The front part is in the suction direction, and the rear part of the fin 3 is in the blowing direction. On the rear surface of the heat sink, the flow velocity at the lower portion of the fin 3 is large, and the flow velocity is slightly reduced toward the upper portion of the fin 3. Cover 4 on top of the heat sink in this area
Is not arranged, the range in which air can flow out from between the fins 3 does not decrease, and since there is no ventilation resistance of air from the cover 4, the total outflowing air volume of air itself does not decrease, Cooling performance does not deteriorate.

FIG. 3 is a diagram showing the relationship between the ratio of the cover length to the width of the heat sink and the temperature of the heating element of the cooling device according to the first embodiment of the present invention. The cover 4 in the width direction of the heat sink from the left end position of the heat sink. The relationship between the ratio of the length to the width of the heat sink and the temperature of the heating element is shown. Cover 4
In the region of 1/3 of the width of the heat sink from the state without the temperature, the temperature sharply drops and the cooling efficiency increases. The cooling performance is constant in a region where the length of the cover 4 is ⅓ or more and ⅔ or less. Further, if the length of the cover 4 is increased, ventilation is deteriorated, so that the temperature slightly rises in the region of 2/3 or more.

Therefore, by setting the length of the cover 4 to be 1/3 or more and 2/3 or less as in the present invention, a small electronic device having high heat conductivity due to good ventilation and excellent heat dissipation characteristics. It is possible to realize a small and lightweight cooling device that can be used in equipment.

In the above description, the cover 4 is arranged when the direction of rotation of the blower fan 5 is clockwise.
In the case of the counterclockwise blower fan 5, as shown in FIG. 1B, the position of the cover 4 covers the entire length of the upper surface of the fin 3 of the heat sink in the length direction, and the heat sink width direction (-X direction) from the right end of the heat sink. By arranging the cover 4 only in a region half the width of the heat sink, the same effect as described above can be obtained. The air flow between the fins in the region where the cover 4 is arranged and the region where the cover 4 is not arranged is similar.

(Embodiment 2) FIG. 4 is a perspective view of an essential part of a cooling device according to Embodiment 2 of the present invention. FIG.
It is a figure which shows the example of a layout of a cover when using the fan for discharge | emission, FIG.4 (b) is Y of the Y direction of FIG.4 (a).
FIG. 1 is a cross-sectional view showing the flow of air between fins in the XL region, and the upper graph is a velocity distribution diagram in the Z direction of air flowing out from between the fins 3 on the upper surface of the heat sink to the outside. FIG. 4 is a velocity distribution diagram in the Y direction of air flowing out from between the fins 3 on the rear surface of the heat sink. Further, FIG. 4C is a Y2 cross-sectional view in the Y direction of FIG. 4A, showing the flow of air between the fins in the XR region.
The upper graph is the velocity distribution diagram in the Z direction of the air flowing out from between the fins 3 on the upper surface of the heat sink, and the right graph is the velocity distribution in the Y direction of the air flowing out from between the fins 3 on the rear face of the heat sink. It is a figure.

In FIGS. 4A to 4C, 3 is a fin formed on the upper part of the heat transfer plate 2, and 1 is heat generated by being attached to the lower part of the heat transfer plate 2 (negative Z-axis direction). It is the body. Reference numeral 5 is a blower fan attached to the side surface of the heat sink as a blowing means. Reference numeral 8 denotes a cover which covers the width of the heat sink (X direction) and is arranged only in an area half the total length of the fan 3 in the length direction of the fan 3 from the mounting end portion of the blowing fan 5 in the length direction of the fan 3 of the heat sink. The above-mentioned parts basically operate in the same manner as in the first embodiment, and detailed description thereof will be omitted.

As shown in FIG. 4B, considering the air flow between the fins 3 in the lengthwise direction of the heat sink (Y direction), in the Y1 cross section which is the XL region, the front of the fins 3 is directed obliquely upward. Since the cover 8 is arranged in front of the fins 3 (on the side of the blower fan 5) on the upper surface of the heat sink, the velocity distribution of the air becomes zero, and the air horizontally oriented toward the rear of the fins 3. Flows out from the rear part of the fin 3 where the cover 8 is not arranged. Further, on the rear surface of the heat sink, the flow velocity at the upper portion of the fin 3 is high, and gradually decreases toward the lower portion of the fin 3. Therefore, by disposing the cover 8, it is possible to generate a flow velocity in the lower portion of the fin 3 which is close to the heating element and has a high temperature, and as a result, the fin 3 as a whole functions effectively for heat dissipation.

As shown in FIG. 4 (c), in the Y2 cross section which is the XR region, there is an oblique downward air flow in the front part of the fin 3, and the cover 8 is arranged in the front part of the fin 3 on the upper surface of the heat sink. Therefore, it is zero and extremely small at the rear part of the fin 3. On the rear surface of the heat sink, the flow velocity at the lower portion of the fin 3 is large, and the flow velocity is slightly reduced toward the upper portion of the fin 3.

Since the cover 8 is not arranged behind the fins 3 on the upper surface of the heat sink, the fins 3 of the heat sink are not provided.
Even if components such as a condenser are arranged on the rear surface, the range in which air can flow out does not decrease, and there is no ventilation resistance of air from the cover 8, so that the total inflow air amount of air itself decreases. And the cooling performance does not deteriorate.

The cover 8 covers the entire length of the fin 3 of the heat sink in the length direction from the mounting end of the blower fan 5.
The relationship between the length ratio and the temperature of the heating element is almost the same as in FIG. 3, and the cooling performance is best in the region where the cover length is 1/3 or more and 2/3 or less.

Therefore, according to the structure of the present invention, it is possible to realize a small and lightweight cooling device which has a high heat conductivity because it has good ventilation and excellent heat dissipation characteristics and which can be used even in a small electronic device. Can be done.

(Embodiment 3) FIG. 5 is a perspective view of an essential part of a cooling device according to Embodiment 3 of the present invention. FIG.
FIG. 5B is a configuration example of a cover when a suction fan is used, and FIG. 5B is a Y1 cross-sectional view in the Y direction of the cooling device according to the third embodiment of the present invention, showing air between fins in the XL region. It is a figure which shows the flow of. The upper graph is the velocity distribution diagram in the Z direction of the air that flows into the fins from the outside on the top surface of the heat sink, and the graph on the right is from the outside to the spaces between the fins on the rear surface of the heat sink (the side opposite to the fan mounting side). It is a velocity distribution diagram of the Y direction of the inflowing air.

In FIGS. 5 (a) and 5 (b), 3 is a fin formed on the upper part of the heat transfer plate 2, and 1 is heat generated attached to the lower part of the heat transfer plate 2 (negative Z-axis direction). A body, 8 is a cover that covers the width of the heat sink and is arranged in a region of half the length of the fan in the length direction of the heat sink from the mounting end of the fan, and 6 is a blower means on the side of the heat sink. It is an attached suction fan.

As shown in FIG. 5B, considering the flow of air between the fins 3 in the length direction (Y direction) of the heat sink, in the Y1 cross section which is the XL region, suction is performed obliquely from the rear of the fins 3. Although the air flow is in the downward direction, since the cover 8 is arranged on the front side of the fins 3 (the suction fan 6 side) on the upper surface of the heat sink, the air flow is in the horizontal direction. On the upper surface of the heat sink, the air velocity distribution is zero because the cover 8 is in front of the fins 3,
Grows in the rear. On the rear surface of the heat sink, the flow velocity is uniformly low from the upper portion of the fin 3 to the lower portion of the fin 3. Therefore, by disposing the cover 8 on the front side of the fins 3, it is possible to generate a flow velocity even under the fins having a high temperature and close to the heating element, and as a result, the entire fins effectively function for heat dissipation. .

Further, since the cover 8 is not arranged at the rear portion of the fin 3, even if a component such as a condenser is arranged at the rear portion of the heat sink, the range in which air can be taken in is not reduced. Further, since there is no ventilation resistance of the air from the cover 8, the total inflow air amount of the air itself does not decrease, and the cooling performance does not decrease.

FIG. 6 is a diagram showing the relationship between the ratio of the cover length to the total length in the length direction of the heat sink and the temperature of the heating element of the cooling device according to the third embodiment of the present invention. 5 shows the relationship between the ratio of the cover length in the heat sink length direction to the total length in the heat sink length direction and the temperature of the heating element. In the region of 1/3 of the state without the cover, the temperature drops sharply and the cooling efficiency increases. The cooling performance is constant in the region where the length of the cover is 1/3 or more and 2/3 or less. Further, if the length of the cover is increased, the ventilation resistance increases, so that the temperature slightly rises in the region of 2/3 or more.

Therefore, with the structure of the present invention, it is possible to realize a small and lightweight cooling device which has a high heat conductivity because it has good ventilation and excellent heat dissipation characteristics and which can be used even in small electronic devices. Can be done.

[0066]

According to the present invention, in the cooling device in which the fan is attached to the side surface of the heat sink and the cover is attached to the upper surface of the heat sink, the cooling device is placed at the optimum position according to the rotating direction of the fan and the inflow / outflow direction of air from the fan. By arranging the cover, it is possible to distribute the air to the whole fin, and by reducing the pressure loss in the area where the cover is not arranged, sufficient air volume is secured, heat dissipation performance is improved and cooling performance is excellent. It is possible to provide a cooling device for electronic components.

[Brief description of drawings]

FIG. 1 is a perspective view of essential parts of a cooling device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a flow of air inside the cooling device and a velocity distribution of air flowing out to the outside according to the first embodiment of the present invention.

FIG. 3 is a relationship diagram of the ratio of the cover length to the width of the heat sink of the cooling device and the temperature of the heating element in the first embodiment of the present invention.

FIG. 4 is a perspective view of a main part of a cooling device according to a second embodiment of the present invention.

FIG. 5 is a perspective view of a main part of a cooling device according to a third embodiment of the present invention.

FIG. 6 is a diagram showing the relationship between the ratio of the cover length to the total length in the heat sink length direction of the cooling device and the temperature of the heating element in the third embodiment of the present invention.

FIG. 7 is a perspective view showing a conventional cooling device.

FIG. 8 is a velocity distribution diagram of air in the conventional cooling device shown in FIG.

9 is a velocity distribution diagram of air in the conventional cooling device shown in FIG. 7 (b).

[Explanation of symbols] 1 heating element 2 Heat transfer plate Three fins 4 cover 5 blowing fan 6 sucking fan 7 Air flow

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5E322 AA01 AA11 FA04                 5F036 AA01 BA24 BB33 BB35 BC03                       BC05

Claims (6)

[Claims] 1. A heat transfer body having a surface to which a heating element can be attached, a plurality of fins standingly provided on the other surface of the heat transfer body to form a ventilation path, and air blown along the ventilation path direction. And a cover that faces the standing surface of the fins of the heat transfer body and covers the ventilation passage, and the area of the cover is 1/3 or more of the area of the standing surface of the fins of the heat transfer body. The cooling device is 2/3 or less. 2. A heat transfer body having a surface to which a heating element can be attached, a plurality of fins standingly provided on another surface of the heat transfer body to form a ventilation path, and air blown along the ventilation path direction. And a cover that faces the standing surface of the fins of the heat transfer body and covers the ventilation passage, and the length of one side of the cover at the position where the cover is arranged is the side of the heat transfer body. And a length of the other side is shorter than a length of the side of the heat transfer body. 3. The cooling device according to claim 2, wherein one side of the cover is arranged in contact with the fan. 4. A heat transfer body having a surface to which a heating element can be attached, a plurality of fins standingly provided on the other surface of the heat transfer body to form a ventilation path, and air blown along the ventilation path direction. And a cover that faces the standing surface of the fins of the heat transfer body and covers the ventilation passage, and the length of one side of the cover at the position where the cover is arranged is the ventilation of the heat transfer body. A cooling device, which is equal to the length of a side in the road direction, and the length of the other side is 1/3 or more and 2/3 or less of the length of the other side of the heat transfer body. 5. The cooling device according to claim 4, wherein the air blowing direction of the fan is a blowing direction into an air passage formed by a plurality of fins. 6. A heat transfer body having a surface to which a heat generating element can be attached, a plurality of fins standingly provided on the other surface of the heat transfer body to form a ventilation path, and air blown along the ventilation path direction. And a cover that faces the standing surface of the fins of the heat transfer body and covers the ventilation passage, and the cover extends over the entire width of the ventilation passage and the length in the direction of the ventilation passage is the fin. The cooling device is arranged at a position of 1/3 or more and 2/3 or less of the length from the fan side end portion.