JP2000223873A - Fanless board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a cooling effect in the same manner when one step is mounted without using a cooling fan by a method wherein there is provided switching means for switching an airflow route between a first state and a second state in a lower part of one board unit out of a plurality of the board units. SOLUTION: Board units 12 of a multi-step are mounted vertically in a unit accommodation part 11a in a casing 11, and these board units 12 are provided with a plurality of circuit boards 13 mounting ICs, etc., respectively. Furthermore, each board unit 12 can pass an air from downward to upward through between the adjacent circuit boards 13. There is provided switching means 14 in a lower part of each board unit 12, and the switching means 14 switches an airflow route between a first state that the air from lower part is flown to the board unit 12 and a second state that the air from lower part is intercepted and the air from a vacant space part 11d is flown to the board unit 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fanless device having no cooling fan for cooling a board unit, such as a control board for electric equipment, in which a plurality of board units are mounted in a housing in multiple stages. It is about the board.

[0002]

2. Description of the Related Art FIG. 8 is a schematic perspective view showing an internal structure of an example of a conventional control panel. In the figure, 1 is an intake port 1a
And a housing 2 having an exhaust port 1b are board units mounted in multiple stages in the housing 1 vertically. These board units 2 are composed of a plurality of circuit boards (printed Substrate 3). Reference numerals 5 and 6 denote cooling fan units provided near the intake port 1a and the exhaust port 1b in the housing 1, respectively.

In such a control panel, by continuously operating the cooling fan units 5 and 6, air is taken into the housing 1 from the intake port 1a and the LSI on the circuit board 3 is
And the IC is forcibly cooled. The cooling air flows upward in the housing 1, and after passing through all the substrate units 2, the cooling air
b to the outside of the housing 1.

[0004]

In the conventional control panel as described above, since the cooling fan units 5 and 6 are constantly operated, the cooling fan units 5 and 6 need to be periodically replaced. The maintenance work is troublesome and the cost is high. On the other hand, if the board unit 2 has only one stage, it is easy to perform natural cooling without performing forced cooling. However, in the case of multi-stage mounting, if the cooling fan units 5 and 6 are simply removed. , LSI and IC may be overheated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. Even when a board unit is mounted in multiple stages, the same cooling as in the single-stage mounting is performed without using a cooling fan. An object is to obtain a fanless board that can ensure the effect.

[0006]

According to a first aspect of the present invention, there is provided a fanless panel having a housing having a unit accommodating portion and a cavity located on a side of the unit accommodating portion. A plurality of board units which are housed side by side in the unit, each having a circuit board, and a plurality of board units which are provided below at least one of the board units, and which allow air from below to flow to the board units. There is provided switching means for switching the air flow path between a state 1 and a second state in which air from below is shut off and air from the gap flows to the substrate unit.

According to a second aspect of the present invention, there is provided a fanless board wherein a temperature sensor is provided on a substrate unit provided with a switching means, and the switching means automatically switches the air flow path in accordance with information from the temperature sensor. It is like that.

According to a third aspect of the present invention, there is provided a fanless board wherein a plurality of substrate units are provided with a temperature sensor and a switching means so that the operating temperatures of the switching means can be individually set.

According to a fourth aspect of the present invention, there is provided a fanless board wherein a plurality of board units are provided with a temperature sensor and switching means, and one of the board units provided with the switching means is provided with a temperature sensor. , All the switching means switch the air flow path simultaneously according to the information from the temperature sensor.

According to a fifth aspect of the present invention, there is provided a fanless board in which an end opposite to the gap is rotatably connected to a lower portion of the substrate unit, and a first opening through which air from below is passed is provided. A bottom plate provided; opening / closing means provided on the bottom plate for opening the first opening in the first state and closing the first opening in the second state; and a lower part of the substrate unit. A bellows mechanism, which is connected between the bottom plate and the bottom plate, and is provided with a second opening through which air from the gap passes. The opening means is opened, and the switching means is used to close the second opening by folding the bellows mechanism in the second state.

A fanless board according to a sixth aspect of the present invention uses an opening / closing means having a slide plate slidable along a bottom plate.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a perspective view schematically showing the internal structure of a fanless board according to Embodiment 1 of the present invention, and FIG. 2 is a perspective view showing a state in which the bellows mechanism of FIG. 1 is folded.

In FIG. 1, reference numeral 11 denotes a metal housing, a unit housing 11a, an air inlet 11b for introducing air into the unit housing 11a, and a unit housing located above the air inlet 11b. An exhaust port 11c for discharging air passing through the unit 11a;
and a void portion 11d located on the side of “a”.

Reference numeral 12 denotes a unit housing portion 11a in the housing 11.
These board units 12 are mounted in multiple stages vertically, and each of these board units 12 has a plurality of circuit boards (printed boards) 13 on which LSIs and ICs are mounted. Further, each board unit 12 is configured so that air can pass from below to above through between adjacent circuit boards 13.

Reference numeral 14 denotes switching means provided at a lower portion of each substrate unit 12 for switching the flow of air for cooling the substrate unit 12. The switching means 14 is a first means for flowing air from below to the substrate unit 12. State (Fig. 2)
The air flow path is switched between the second state (FIG. 1) and the second state (FIG. 1) in which the air from below is blocked and the air from the gap 11d flows to the substrate unit 12.

FIG. 3 is a perspective view showing the switching means 14 of FIG.
FIG. 4 is a bottom view showing the switching means 14 of FIG. 3, and FIG. 5 is a front view of a main part showing the switching means 14 of FIG. In the figure, 1
5 is the substrate unit 1 on the end opposite to the gap 11d side.
The bottom plate 15 is provided with a plurality of first openings 15 a through which air from below passes through the substrate unit 12. Reference numeral 16 denotes an opening / closing means which is provided so as to be reciprocally slidable along the bottom plate 15 and opens and closes the first opening 15a in the first state and closes the first opening 15a in the second state. It is a slide plate.

Reference numeral 17 denotes a lower portion of the substrate unit 12 and the bottom plate 15.
And a bellows mechanism which is expanded and contracted with the rotation of the bottom plate 15.
A plurality of second openings 17a through which air from the air flows are provided. The second opening 17a is opened when the bellows mechanism 17 is extended in the first state, and is closed when the bellows mechanism 17 is folded in the second state. Reference numeral 10 denotes a temperature sensor provided in each substrate unit 12.

FIG. 6 is a circuit diagram partially showing a control circuit of the switching means 14 of FIG. In the figure, reference numeral 21 denotes a driving means for driving the slide plate 16 and the bellows mechanism 17 provided on each switching means 14;
Are connected to each other, and signals from the corresponding temperature sensors 10 are input to these OR gates 22.

Reference numeral 23 denotes an AND gate for simultaneously outputting a signal to all the OR gates 22; 24, a power supply connected to the AND gate 23 via a pull-up resistor 25; 26, a control signal output to the AND gate 23; This is a control signal input unit to be used. Normally, in the control circuit of FIG. 6, the control signal is set to the LOW level, and the circuit gate of the drive transistor (not shown) provided in the drive means 21 is opened by the HIGH signal of the output level of the temperature sensor 10. It has become.

Next, the operation will be described. When the temperature of each board unit 12 is lower than the set value of the temperature sensor 10,
Since the output level from the temperature sensor 10 is at the LOW level, the circuit gate is closed, and the switching means 14 remains in the first state shown in FIG. That is, the first opening 15
a is opened, the bellows mechanism 17 is folded, and the second opening 17a is closed. Therefore, the air that has entered the housing 11 from the intake port 11b passes through the board unit 12 in order from the bottom, and is discharged out of the housing 11 from the exhaust port 11c.

From this state, one of the substrate units 1
When the temperature of 2 rises, the air flowing through the unit accommodating portion 11a is heated, and the air whose temperature has risen flows into the upper substrate unit 12. As a result, when the cooling effect decreases and the junction temperature of the package of the LSI and the IC increases, the reliability of the LSI and the IC is significantly impaired.
Therefore, in the first embodiment, when the temperature of the board unit 12 rises to the set value, the temperature is detected by the temperature sensor 10 and the driving unit 21 is driven to switch the switching unit 14.
Is displaced to the second state shown in FIG.

That is, the first opening 15a is closed by the slide plate 16, and the bottom plate 15 is rotated so that the end on the side of the gap 11d is lowered. Along with this, the bellows mechanism 17 is extended, and the second opening 17a is opened. Therefore, the air sent to each board unit 12 is not the air that has passed through the board unit 12 adjacent below, but the air from the gap 11d. Since the air from the gap 11d does not pass through the other board units 12, the cooling effect is the same as that at the time of single-stage mounting, and the cooling efficiency is improved.

As described above, when the temperature of the substrate unit 12 becomes equal to or higher than the set value, the air flow in the housing 11 is switched by the switching means 14, and the relatively low-temperature air from the gap 11d is released. Therefore, even when the board units 12 are mounted in multiple stages, the same cooling effect as in single-stage mounting can be ensured without using a cooling fan.

Although the switching means 14 can be manually displaced, the first embodiment is automatically operated by a signal from the temperature sensor 10, so that workability is improved.

Embodiment 2 When the temperature sensors 10 are individually provided in each of the board units 12 provided with the switching means 14, the set values of the operating temperatures of the respective switching means 14 may be the same, and the setting values of the LSI and IC may be the same. The set value may be made variable within the allowable range of the joining temperature, and may be individually set. That is, as shown in FIG. 7, for example, the switching unit 14 may be operated at a different temperature for each substrate unit 12. FIG. 7 shows a case where the allowable range of the junction temperature of the LSI and IC in the substrate unit 12 in the lower two stages is low, and the allowable range of the junction temperature of the LSI and IC in the uppermost substrate unit 12 is high.

In addition, one of the plurality of substrate units 12
The temperature sensor 10 is provided only in one substrate unit 12 and 1
All the switching means 14 may be switched at the same time according to the information from the two temperature sensors 10, and the configuration and control can be simplified. For example, the temperature sensor 10
Board unit 12 in which the temperature level of the top is the highest
For example, the control signal of the circuit shown in FIG. 6 may be set to the HIGH level using the temperature signal described above, and the switching means 14 of each stage may be operated collectively.

Further, it is not necessary to provide the switching means 14 in all the substrate units 12, and for example, the switching means 14 of the lowermost substrate unit 12 near the intake port 11b may be omitted.

Further, in the above example, the case where the substrate unit 12 has three stages has been described, but two or four or more stages may be used. Further, in the above-described example, the ventilation-type board structure in which the housing 11 is provided with the intake port 11b and the exhaust port 11c has been described, but the present invention can also be applied to a closed-type board structure.

Here, the means for forming the air flow path may be provided on the housing 11 side. In this case, it is necessary to perform manual processing on the housing 11 in accordance with the number of stages of the substrate unit 12. In addition, the processing cost for the housing 11 increases. On the other hand, in the above example, since the switching means 14 is mounted on the substrate unit 12 side, it is not necessary to process the housing 11 in accordance with the number of stages, and the productivity can be improved.

Considering the cooling surface, the substrate unit 1
2, the cooling efficiency is higher from the vertical lower side than from the side, and when the board units 12 are stacked, the cooling capacity can be expected to be improved by the chimney effect. Therefore, the substrate unit 12 can be efficiently cooled by detecting the threshold value with the temperature sensor 10 or the like and switching the air flow path. That is, it is possible to obtain a fanless board that can flexibly respond to a change in the system configuration and also flexibly respond to a change in the cooling effect within an allowable range of component reliability.

[0031]

As described above, the fanless board according to the first aspect of the present invention has a first state in which air from below flows into the substrate unit, and a state in which air from below is cut off and air from the gap is cut off. Since the switching means for switching the air flow path between the second state and the second state to be supplied to the substrate unit is provided at the lower part of the substrate unit, even when the substrate units are mounted in multiple stages, the cooling unit is not used, and the single-stage mounting is possible. The same cooling effect as described above can be secured.

In a fanless board according to a second aspect of the present invention, a temperature sensor is provided on a board unit provided with switching means,
Since the switching means automatically switches the air flow path in accordance with the information from the temperature sensor, the labor for operating the switching means can be omitted, and the workability can be improved.

In the fanless board according to the third aspect of the present invention, the temperature sensors and the switching means are provided on the plurality of substrate units, and the operating temperatures of the switching means can be individually set, so that the substrate units can be efficiently cooled. it can.

According to a fourth aspect of the present invention, there is provided a fanless board, wherein a temperature sensor and switching means are provided on a plurality of substrate units, and a temperature sensor is provided on one of the substrate units provided with the switching means. Since all the switching means switch the air flow path simultaneously according to the information from the temperature sensor, the configuration and control can be simplified.

According to a fifth aspect of the present invention, there is provided a fanless board in which an end opposite to the gap is rotatably connected to a lower portion of the substrate unit, and a first opening through which air from below is provided. A bottom plate provided on the bottom plate, opening / closing means for opening the first opening in the first state and closing the first opening in the second state, and a lower portion of the substrate unit. A bellows mechanism connected between the bottom plate and a second opening through which air from the gap is provided, and the second bellows mechanism is extended in the first state by the second bellows mechanism being extended. Since the opening is opened and the switching means for closing the second opening by folding the bellows mechanism in the second state is used, the air flow path is more reliably switched with a simple configuration. be able to.

The fanless board of the invention of claim 6 uses the opening and closing means having a slide plate slidable along the bottom plate, so that the first opening can be easily opened and closed.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an internal structure of a fanless board according to Embodiment 1 of the present invention.

FIG. 2 is a perspective view showing a state where the bellows mechanism of FIG. 1 is folded.

FIG. 3 is a perspective view showing the switching means of FIG. 1;

FIG. 4 is a bottom view showing the switching means of FIG. 3;

FIG. 5 is a front view of a main part showing the switching means of FIG. 3;

FIG. 6 is a circuit diagram partially showing a control circuit of the switching means of FIG. 1;

FIG. 7 is a schematic perspective view showing an internal structure of a fanless board according to Embodiment 2 of the present invention.

FIG. 8 is a schematic perspective view showing an internal structure of an example of a conventional control panel.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Temperature sensor, 11 housing | casing, 11a unit accommodating part, 11d air gap part, 12 board units, 13 circuit boards, 14 switching means, 15 bottom plate, 15a 1st opening, 16 slide plate, 17 bellows mechanism, 17a 2nd
Opening.

Claims (6)

[Claims] 1. A housing having a unit accommodating portion and a void portion located on a side of the unit accommodating portion. The housing is vertically arranged in the unit accommodating portion in the housing and has a circuit board. A plurality of substrate units, and a first state in which air from below is provided to the substrate unit, the air being provided below the at least one substrate unit among the substrate units; The air flowing from the section to the substrate unit
A switching means for switching an air flow path between the fanless board and the fanless board. 2. A substrate unit provided with a switching means is provided with a temperature sensor, wherein the switching means comprises:
The fanless board according to claim 1, wherein the air flow path is automatically switched according to information from the temperature sensor. 3. The fanless board according to claim 2, wherein a temperature sensor and a switching means are provided on the plurality of substrate units, and the operating temperatures of the switching means can be set individually. 4. A temperature sensor and a switching means are provided on a plurality of substrate units, and a temperature sensor is provided on one of the substrate units provided with the switching means. 3. The fanless board according to claim 2, wherein the switching unit switches the air flow path simultaneously according to information from the temperature sensor. 5. The switching means comprises: a bottom plate having an end opposite to the gap side rotatably connected to a lower portion of the substrate unit and having a first opening through which air from below is provided. Opening / closing means provided on the bottom plate for opening the first opening in the first state and closing the first opening in the second state; a lower portion of the substrate unit and the bottom plate Connected between
A bellows mechanism provided with a second opening through which air from the gap is provided, and the second opening is formed by extending the bellows mechanism in the first state. The fanless board according to any one of claims 1 to 4, wherein the fan-less board is opened and the second opening is closed by folding the bellows mechanism in the second state. . 6. The fanless board according to claim 5, wherein the opening / closing means has a slide plate slidable along the bottom plate.