JPS6223304A - Force air cooler - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a forced air cooling system that uses a fan to circulate cooling air through a closed power distribution board, thereby cooling heat-generating components within the power distribution board. It is something that can be done.

B2 Summary of the Invention The present invention provides a forced air cooling device in which a heating element is cooled by the cooling air that is circulated along a circulating air path by a cooling fan and heat exchanged in a radiator. By providing a bypass air path so that the air returns to the heat generating element without passing through the radiator, and by adjusting the passing air tl of the bypass air path so as to obtain the optimum cooling efficiency, while obtaining high cooling efficiency, This has the advantage of having a small number of parts, being economical, and having excellent maintainability.

C1 Conventional technology FIG. 6 is a diagram showing a conventional forced air cooling system, in which 1 is a cubicle in a sealed power distribution board, 2 is a heating element, such as a heat-generating component in a power distribution board, 31-r radiator, and 4 is a cooling device. Fan, 5 is a cooling air circulation path. In such a device, a cooling fan 4 circulates cooling air along a circulation air path 5 as shown by an arrow, and the heating element 2 is cooled by the cooling air with which heat is exchanged in a radiator 3 .

In order to obtain higher cooling efficiency with the above V:, lf,
It is desirable that the cooling air be passed through the heating element 2 while keeping the ambient temperature (temperature of the cooling air) of the heating element 2 low. By the way, the head loss seen from the cooling fan 4 is a combination of the head losses of the radiator 3 and the heating element 2.

FIG. 7 is a graph showing this situation, where L is a graph showing the capacity of the fan, and xl and x2n are the head losses of the heating element 2 and the cooling fan 4, respectively. Therefore, in order to keep the ambient temperature low, if the ventilation area of the radiator 3 is increased and the head loss is decreased, the at of the radiator 3 (2) will increase, but the air volume in the heating element 3 will decrease and the cooling of the heating element 2 will be insufficient. On the other hand, if we reduce the ventilation area of the radiator 3 in order to reduce the air volume in the heating element 2 and increase its head loss, the heat exchange capacity will decrease.
The ambient temperature will rise. In order to solve this problem, in the past, a booster fan or the like was added, thereby increasing the wind erosion on the heating element 3 and cooling it while maintaining the heat exchange capacity.

D9 Problems to be Solved by the Invention However, the use of a booster fan and the like has problems in that the number of parts increases, which is uneconomical, and the structure becomes complex, making maintenance difficult.

An object of the present invention is to provide a forced air cooling device that can solve these problems while achieving high cooling efficiency.

Means for Solving Problem E1 The present invention provides a heating element to be cooled, a radiator, and a cooling fan in a circulating air path, and the cooling air that has passed through the heating element 1 returns to the heating element without passing through the radiator. A bypass air passage is provided, and adjustment means for adjusting the ventilation area of the bypass air passage is provided.

F1 action As the ventilation area of the bypass air passage increases.

The amount of cooling air passing through the heating element increases, which lowers the temperature of the heating element, but if the ventilation area exceeds a certain size, the temperature of the cooling air becomes too high and the temperature of the heating element decreases. It will rise. Therefore, the ventilation area of the bypass air passage is adjusted by the adjustment means so that the temperature of the heating element is lowered.

G. Embodiment FIG. 1 is a configuration diagram showing an embodiment of the present invention. In this embodiment, a bypass air channel 6 is provided between the air channel from the cooling fan 4 to the inlet of the radiator 3 and the outlet of the radiator 3. In addition, an adjusting means for adjusting the ventilation area l of the bypass air passage 6, such as a damper or a slide member (not shown), is also provided. Therefore, the cooling air that has passed through the heating element 21 flows along the circulation air passage 5 by the cooling fan 4, but a part of it does not pass through the radiator 3, but returns to the heating element 2 through the bypass air passage 61.

In such a configuration, the heating element 2, the radiator 3,
The wind t passing through the bypass air passage 61 is QT, QR, QB.
If the temperature of the cooling air passing through the heating element 2 is YTT, and the temperature of the cooling air at each outlet of the radiator 3 and the bypass air passage 6 is TR1TB, the following equations (1) and (2) hold true.

QT=QB+QR(yy//min),,
(1) Here, since the ventilation area of the heating element 2 is constant, increasing QT increases the speed of the cooling air passing through the heating element 2, increasing the cooling efficiency. @ Solid line m in figure 2
is a graph showing the relationship between thermal resistance and wind speed when cooling air passes through the heating element 2. From this graph, it can be understood that as the wind speed increases, the thermal resistance decreases and the cooling efficiency increases. On the other hand, the wind iQR passing through the radiator 3 is determined by the heladros of the radiator 3 according to the capacity of the phantom cooling fan 4. Therefore, after determining the cooling fan 4 and radiator 3, in order to increase QT''', the air volume passing through the bypass air passage 6 can be increased. When QB, QR
, is a graph showing how QT changes, and the solid two-dot line and the chain line represent QT, respectively.

Qp, QBl-, are the corresponding ones. From this graph, it is understood that in order to increase QT, the ventilation area of the bypass air passage 6 should be increased to increase QB. Figure @4 is a graph showing the performance characteristics of the C fan like Figure 7, t is a graph showing the fan capacity, and x1+x2 are the heating element 2 and cooling fan 4 when there is no bypass air path 6, respectively.
Heradrus, X'1. X'2 is each bypass air passage 7
This is the head loss of the heating element 2 and cooling fan 4 when there is. From this figure, it can be seen that by increasing QB and decreasing QR, the radiator 3 is lowered and the operating point of the fan 4 is moved to the right (in the direction in which QT increases).

By the way, since the cooling air that has passed through the bypass air passage 6 is not cooled by the radiator 3, its temperature TB is equal to the ambient temperature, and naturally the temperature T of the cooling air that has passed through the radiator 3 is equal to the ambient temperature.
Since it is higher than R, if the air volume QB of the bypass air passage 6 is increased too much, the temperature TT of the cooling air passing through the heating element 2 will rise too much, resulting in poor cooling efficiency.

FIG. 5 is a graph showing this situation, and the solid line n represents how the fin temperature of the heating element 2 changes depending on the ventilation area of the bypass air passage 6. This graph 1
: To explain it, it's bypass style'#! As the ventilation area 16 increases, the amount of cooling air flowing through the fins of the heating element 2 increases, and the temperature of the fins decreases due to the relationship between wind speed and thermal resistance shown in FIG. During this time, the temperature TT of the cooling air passing through the heating element 2 increases, but the degree of decrease in the thermal resistance of the fins is greater, so the overall temperature of the fins decreases. However, when the ventilation area of the bypass air passage 6 exceeds a certain area So, the degree of decrease in the thermal resistance of the fins is smaller than the degree of increase in the temperature TT of the cooling air, and the temperature of the fins increases overall. For this reason, instead of simply increasing the amount of air passing through the heating element 2, QT, the bypass air passage 6 is designed to increase QT and lower TT so that the temperature of the fins of the heating element 2 is as low as possible. It is necessary to adjust the ventilation area. Therefore, in this embodiment, the ventilation area of the bypass air passage 6 is adjusted to the optimum area (
5th medium So) to obtain maximum cooling efficiency.

Incidentally, such adjustment can also be made on the cooling fins of the radiator 3 or heating element 2, but each time the fugiator 3
, fan 4, etc. must be designed. On the other hand, if the adjustment is made using an air volume adjusting means such as a damper, there is no need to design the radiator or the like each time. Furthermore, even if the bypass air passage 6 is not provided, depending on the design of the radiator 3, high cooling efficiency can be obtained by, for example, making the air volume of the radiator 3 and the heating element 2 equal. There is a problem in that Heladros's small fin spacing requires a radiator with a large spacing, resulting in an increase in size of the radiator. On the other hand, if a bypass air path is provided, high cooling efficiency can be obtained without increasing the size of the radiator.

H9 Effects of the Invention As described above, according to the present invention, the temperature of the heating element is kept as low as possible by providing a bypass air passage and adjusting the ventilation air volume, so additional parts such as a booster fan are not required. High cooling efficiency can be obtained without using. Therefore, it is economical because the number of parts is small, and the structure is simple, so it is easy to maintain.

[Brief explanation of the drawing]

Figure 1 is a structural diagram showing an example, Figure 2 is a graph showing the characteristics of cooling efficiency, Figure 3 is a graph showing the relationship between the ventilation area of the bypass air path and air volume, and Figure 4 is a graph showing the example. Fig. 5a is a graph showing characteristics of cooling efficiency, Fig. 6 is a structural diagram of a conventional device, and Fig. 7 is a capacity characteristic diagram of a cooling fan according to a conventional device. DESCRIPTION OF SYMBOLS 1... Cubicle, 2... Heating element, 3... Radiator, 4... Cooling fan, 5... Circulating air path, 6...
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Claims (1)

[Scope of Claims] A heating element to be cooled, a radiator, and a cooling fan are provided in a circulating air path, and the cooling fan circulates cooling air along the circulating air path, and the cooling air with heat exchanged by the radiator. In a forced air cooling device that cools a heating element, a bypass air path is provided so that the cooling air that has passed through the heating element returns to the heating element without passing through the radiator, and the ventilation area of this bypass air path is adjusted. A forced air cooling device characterized by being provided with a means.