JP2002141451A - Cooler of electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size and cost of a cooler capable of uniformly cooling a plurality of heating components. SOLUTION: A plurality of the heating components (power transistors) 2a to 2n are fixed to a radiator (heat sink) 3. Ventilation holes 4a and 4b are opened at upper and lower parts of a housing 1 in which the radiator 3 is arranged to conduct natural air cooling. When the radiator 3 becomes a predetermined temperature or higher, the temperature is detected by a temperature sensor 12, a fan 7 is driven, forcibly air cooled via a guide plate 11 oppositely disposed to the fins 3a of the radiator 3 to uniformly air cool the components 2a to 2n.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling apparatus for an electronic device having a circuit including a high-temperature electric component such as a power amplifier circuit.

[0002]

2. Description of the Related Art Conventionally, natural air cooling and forced air cooling have been widely used as a cooling method for preventing electric components such as a power supply circuit and a power amplifier circuit in an electronic device from becoming high in temperature.

FIG. 5A is a perspective view of a cooling device showing a natural air cooling method. Heating components 2a and 2b such as a power amplifying transistor in a power amplifying circuit include a radiator 3 (hereinafter referred to as a heat sink). The heat sink 3 is fixed to a chassis or the like (not shown) provided in the housing 1 by fixing the heat sink 3 with an insulating material using screws or the like.

The heat sink 3 is usually cast of aluminum or the like, and is provided with a plurality of fins 3a arranged side by side. Heating component 2a,
The heat generated by the heat sink 2b heats the heat sink 3, and natural air cooling is performed such that outside air flows in from the ventilation hole 4a of the bottom plate 1a and flows out of the ventilation hole 4b of the top plate 1b by natural convection.

Japanese Patent Laid-Open Publication No. Hei 5-259673 discloses a forced air cooling system. FIG. 5B is a perspective view showing the configuration of the heat sink disclosed in the above publication.

FIG. 5B shows a configuration in which the fins 3a of the heat sink are forcibly air-cooled. The bottom plate 5a and the top plate 5b are fixed to the lower surface, and the heat-generating components 2a and 2b are fixed to the surfaces of the left and right heat sinks 3L and 3R where the fins 3a are not formed. A mounting plate 8 to which a fan 7 is fixed is fixed to one opening 6a of the cooling device having a shape, and the fan 7 is driven to
A cooling device is shown in which the size is reduced by forcibly air-cooling the cooling device and the cooling effect is enhanced.

[0007]

In recent years, the functions of electronic device products and the like have been remarkably improved with the diversification of user needs. As an example, AV amplifiers and the like, which are the core of AV equipment products, are equipped with a large number of output channels and the output power is increasing intensely. In the internal space, the required volume of the heat sink 3 and the required opening area for ventilation may not be included. Also, when the fan 7 is used in forced air cooling, a cooling device having a rectangular cylindrical shape as shown in FIG. 5B must be configured to obtain a uniform cooling effect on a plurality of heat generating components. The inlet and outlet for the outside air are required at the front and rear of the heat sink 3, and the heat sink 3 is increased in size.

[0008]

According to the present invention, there is provided a cooling apparatus for an electronic apparatus having a heat sink having a plurality of heat-generating components mounted inside a housing, wherein the heat-generating components are provided. Heat sinks 3 are heat-generating components 2a-2
Within the allowable temperature range of n, natural air cooling is performed by the ventilation holes 4a and 4b provided on the upper and lower surfaces of the housing 1, and the heat-generating component 2a
〜2n is about to exceed the permissible temperature.
To perform forced air cooling.
A cooling device for electronic equipment, comprising: guide plates 11 for directly blowing air to fins 3a of heat sink 3 near a to 2n.

According to a second aspect of the present invention, there is provided the cooling apparatus for electronic equipment according to the first aspect, wherein the detection of the allowable temperature is performed by the temperature sensor 12.

According to the cooling apparatus for an electronic device of the present invention according to the first and second aspects, it is possible to automatically control switching between natural air cooling and forced air cooling.
Only the small space guide plate and the fan can efficiently and uniformly blow external air to the heat-generating component.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a cooling device for electronic equipment according to the present invention will be described below with reference to FIGS.

FIG. 1 is an exploded perspective view of a cooling device for an electronic device according to the present embodiment, FIG. 2 is a perspective view when the cooling device of the present embodiment is incorporated in the electronic device, and FIG. 3 is a temperature used in the present embodiment. FIG. 4 is a characteristic diagram of the sensor, and FIG. 4 is a temperature detection circuit diagram used in this embodiment.

Before describing the cooling device of FIG. 1, the overall assembling structure of the cooling device for electronic equipment of this embodiment will be described with reference to FIG.

In FIG. 2, a plurality of power transistor groups 2 (2a to 2n) for a power amplifying circuit serving as heat-generating components are erected on a printed circuit board 13 in a housing 1 formed in a substantially rectangular parallelepiped box shape. Then, it is fixed to the back surface of the heat sink 3 via an insulating plate or the like. A portion 14 around the printed circuit board 13 indicates a power supply circuit, and a reference numeral 15 indicates a power supply transformer. Each of these circuits also becomes a heat-generating component that generates a lot of heat. Reference numeral 16 denotes a signal system circuit board including an input / output system.

A cooling device according to one embodiment of the present invention is provided with a guide plate 11 and a fan 7 each composed of a plate and a guide, facing a fin 3a of a heat sink 3. The bottom plate 1a and the top plate 1b of the housing 1 have ventilation holes 4a and 4b on the upper and lower surfaces of the fins 3a of the heat sink 3, respectively.
b is pierced.

As shown in the exploded perspective view of FIG. 1, the above-described cooling apparatus has a plurality of heat generating components 2a to 2d including a plurality of power transistors erected on a printed circuit board 13 and erected on the printed circuit board 13. And a temperature sensor 12 such as a thermistor and a plurality of heat generating components 2a to 2d.
And is fixed to the main surface (back surface) 3b.

At a position facing the back surface 3b of the heat sink 3, a plate-like plate 9a is disposed so as to be in contact with the plurality of fins 3a. The plate 9a is provided with a number of through holes 9b corresponding to the number of heat generating components 2a to 2d fixed to the back surface 3b of the heat sink 3, and a plurality of heat generating components 2a to 2d are supplied from the fan 7 supplied through these holes. The stuck back is cooled directly.

The guide 10a has a plurality of passage plates 10b disposed at predetermined intervals between the upper and lower plates 10c and 10d such that the main surfaces thereof are parallel to the upper and lower plates 10c and 10d. The shapes of the upper and lower plates 10c and 10d and the passage plate 10b are, when viewed from a plane, composed of a substantially rectangular tip portion 10e and a flared end portion 10f, such that the shamisen bees are cut in half in the longitudinal direction. The front and right sides are formed in a box shape as a rectangular opening 10g and a square opening 10h.

The longitudinal direction and height direction of the rectangular opening 10g of the guide 10a are the same as the longitudinal direction and height direction of the plate 9a, and the size of two sides of the square opening 10h is The fan 7 is attached to the square opening 10h so that the fan 7 faces the opening, and the front ends of the plurality of passage plates 10b are bent in the height direction and integrated with the lower plate 10d, Further, in the case of FIG. 1, first to fourth passages 10k, 10l, 10m, and 10n are formed by a partition plate 10j fixed between the lower plate 10d and each passage plate 10b substantially in parallel with the bent portions.

The above-mentioned rectangular opening 1 of the guide 10a
0g and the plate 9a is brought into contact with and fixed thereto.
The guide plates 11 for forcibly air-cooling the fins 3a of the heat sink 3 through the through holes 9b are provided for the ventilation from the fourth passages 10k, 10l, 10m, and 10n.

The operation of the cooling device for an electronic device having the above configuration will be described with reference to FIGS.

In the housing 1 of the electronic device shown in FIG. 2, in the normal state, outside air flows in the direction of arrow A from the ventilation holes 4a formed in the bottom plate 1a, and the fins of the heat sinks 3 arranged vertically are arranged. While air-cooling 3a, the warmed air is allowed to flow out from the ventilation holes 4b formed in the top plate 1b of the housing 1 and naturally cooled.

A temperature sensor 12 such as a thermistor provided at a place where the temperature of the heat sink 3 rises most shows a resistance-temperature characteristic curve 17 as shown in FIG. In FIG. 3, the vertical axis represents the resistance change ratio on a logarithmic scale, and the horizontal axis represents the temperature (° C.) on an equally spaced scale. The resistance-temperature characteristic curve 17 indicates that the resistance change ratio is 2
The resistance characteristic shows a value of 7 at 70 ° C. when it is 1 at 5 ° C. In this embodiment, the resistance value is 330Ω at 25 ° C., and the resistance value is 2, 2 KΩ at 70 ° C. , The highest temperature at which the power transistors 2a to 2n of the heat-generating components can be used was 95 ° C.

Temperature sensor 12 attached to heat sink 3
4 exceeds 70 ° C. in the resistance-temperature characteristic curve 17 of FIG.
Operates to drive the motor of the fan 7.

In FIG. 4, the motor of the fan 7 is connected to a B power source (+15 V), and the voltage of the B power source is supplied to a temperature sensor 12 connected in series with a resistor R having a resistance value of 8, 8 KΩ. One end of the sensor 12 is grounded, and supplies a voltage extracted from a connection point between the resistor R and the temperature sensor 12 to a non-inverting input terminal of the comparator 18. Comparator 1
The cathode of a battery (3 V) 19 is connected to the inverting input terminal 8, the anode is grounded, and the reference voltage is input to the comparator 18. The output of the comparator 18 is supplied to one end of the motor of the fan 7.

When the temperature of the temperature sensor 12 attached to the heat sink 3 exceeds 70 ° C. in the circuit diagram described above, the potential of the non-inverting input terminal of the comparator 18 exceeds the reference voltage 3 V of the inverting input terminal of the comparator 18, and Is turned on, the output terminal is electrically connected to the ground, and the motor of the fan 7 connected to the B power supply is driven.

Therefore, the wind from the fan 7 shown in FIG. 1 is sent in the direction of arrow C, and the first to fourth passages 10k, 10l, 10m, 10n of the guide 10a and the plate 9a
The fins 3a of the heat sink 3 are switched to be forcibly air-cooled through the respective through holes 9b to cool the heat generating components 2a to 2n. The wind that has cooled the fins 3a and the back surface 3b of the heat sink 3 is applied to the top plate 1b and the bottom plate 1 of the housing 1 shown in FIG.
The air is sent out of the housing 1 through the ventilation hole 4b formed in a.

[0028]

In the cooling apparatus for electronic equipment of the present invention, natural air cooling is performed, for example, until the temperature of the heat sink 3 reaches 70 ° C.
When a predetermined temperature value exceeding 70 ° C. is reached, the fan 7
Are rotated to perform forced air cooling, thereby preventing heat destruction of the heat-generating components 2a to 2n, and the ventilation holes 4 used during natural air cooling.
Since it is only necessary to attach the guide plate 11 and one fan 7 to the heat sinks a and 4b, a predetermined heat sink size can be set in a small space in the housing 1.
5 also during forced air cooling for driving the motor of the fan 7.
There is no need to provide a large opening 6b as in (B), and since the outside air is directly blown to the back of each of the heat generating components 2a to 2n, the cooling efficiency is good and a large number of heat generating components can be uniformly air-cooled.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of one embodiment of a cooling device for an electronic device of the present invention.

FIG. 2 is a perspective view showing an assembled state of one embodiment of a cooling device for electronic equipment of the present invention.

FIG. 3 is a resistance temperature characteristic curve diagram of a temperature sensor used in an embodiment of a cooling device for electronic equipment of the present invention.

FIG. 4 is a temperature detection circuit diagram used in one embodiment of the cooling device for electronic equipment of the present invention.

FIG. 5 is a perspective view of a conventional cooling device for an electronic device.

[Explanation of symbols]

1 ‥‥ housing, 2a ~ 2n ‥‥ heating parts, 3, 3L, 3R
{Heat radiator (heat sink), 4a, 4b} ventilation hole,
9a plate, 9b through hole, 10a guide,
10k, 10L, 10m, 10n {first to fourth passages, 11} guide plate, 12} temperature sensor (thermistor), 18} comparator,

Claims (2)

[Claims] 1. A cooling device for an electronic device having a radiator having a plurality of heat-generating components mounted inside a housing, wherein the radiator is provided on an upper surface and a lower surface of the housing within an allowable temperature range of the heat-generating components. Natural air cooling is performed by the provided ventilation holes, and when the heat-generating components are about to exceed the allowable temperature, the blower motor is driven to perform forced air cooling. At this time, the fins of the radiator near the plurality of heat-generating components are respectively provided. A cooling device for an electronic device, comprising a guide plate for directly blowing air. 2. The cooling device for an electronic device according to claim 1, wherein said allowable temperature is detected by a temperature sensor.