JPH0244077Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to a cooling fan that air-cools the inside of an apparatus, and particularly relates to a drive device that switches the direction of rotation of the cooling fan.

(b) Technology background In electronic devices, which have been becoming smaller in recent years,
There is a trend toward higher density mounting of electrical components on printed circuit boards, and sufficient measures must be taken against the heat generated by the electrical components. For this reason, forced air cooling is performed in electronic devices. That is, external air is sent into the device and internal air is discharged outside the device. This air flow is generated by a fan. Therefore, if the rotation of the impeller of this fan becomes abnormal for some reason, the temperature inside the device will gradually rise, causing thermal damage to electrical components and the like. In order to prevent this, an alarm means is required to detect abnormal rotation of the fan and stop power supply to the device.

(c) Prior Art and Problems Conventional alarm means generally detect an abnormal rise in temperature using a temperature sensor installed in a fan. Such temperature sensors include those that are integrated with a resistor, a thermomagnet piece (which becomes magnetized when the temperature rises to a predetermined temperature), and a reed switch, and those that are composed of a resistor and a bimetal. For example, considering an alarm means using a temperature sensor with the configuration shown above, a constant current is passed through the resistor and the resistor generates heat, but normally the resistor is cooled by air flow caused by the rotation of the impeller, so the resistor generates heat. There is no action of the magnet piece and the reed switch is in the break state. However, if the rotational speed of the impeller decreases for some reason, the temperature of the resistor increases, and the piece of the thermomagnet in contact with the resistor is heated to a predetermined temperature or higher, and the piece of the thermomagnet is magnetized and makes a reed switch. state. This change in the reed switch from break to make is used as an alarm signal.

In this manner, the temperature sensor provided in the conventional fan, that is, the rotation detection mechanism, is disposed within the airflow region caused by the rotating impeller, and is designed to detect whether or not the rotational state of the impeller is normal.

However, in this type of system, the rotation detection mechanism is installed within the air flow area, and the air flow direction is always constant, so dirt sucked in from outside the device adheres to the rotation detection mechanism and can cause damage to the blades. The problem was that the cooling effect of the car deteriorated, causing an alarm to be activated as if the impeller had stopped, resulting in false detection.

(d) Purpose of the invention In view of the above-mentioned drawbacks of the conventional technology, it is an object of the present invention to provide a cooling fan drive device that can reduce the amount of dust attached to the rotation detection mechanism.

(e) Structure of the device The object of the invention is to provide a cooling fan for cooling the inside of a device such as an electronic device, a rotation detection mechanism disposed within an airflow region generated by the fan, and a rotation detection mechanism for detecting the rotation of the fan. In a mechanism comprising a rotation control section that controls a direction, the rotation control section has a timer and is controlled by the timer, and the rotation direction is such that the fan is rotated in the opposite direction for a predetermined period set in the timer. This is achieved by providing a cooling fan drive device characterized in that it is equipped with a switching means.

(f) Example of implementation of the idea Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The figure is a circuit diagram for explaining the cooling fan drive device of the present invention, where F is the cooling fan, D is the rotation detection mechanism, RC is the rotation control section, and SI is the device power switch.

Further, the rotation control section RC is composed of a timer TM, a timer start switch S2, a changeover switch S3 serving as rotation direction changeover means, and a phase advance capacitor C.

As shown in the figure, the fan F has three terminals, one of which is connected to the power supply V via the power switch S1, and the other two terminals are connected to the fan's rotation direction changeover switch S3 and the phase advance switch. It is connected to a power switch S1 via a capacitor C, and to a power supply V via the power switch S1. On the other hand, a relay R, a timer TM, and a timer start switch S2 are connected in series between the power supply lines.

In the figure, a rotation direction changeover switch S3 is interlocked with a relay R, and when the relay R is on, the contact switches in the direction of the dotted line and the connection of the phase advance capacitor C is switched, thereby reversing the fan. On the other hand, when the relay R is in the OFF state, the contact is returned to the direction of the solid line and rotated normally in the normal forward direction.

Such a cooling fan drive device operates as follows.

When the device power switch S1 is turned on, the fan F
begins to rotate, and the timer start switch S
2 is turned on in conjunction with the power switch S1, and the timer TM starts operating. At this time, the fan rotates in a direction opposite to the normal direction since relay R is turned on and the contact point of the rotation direction changeover switch S3 is switched in the direction of the dotted line. Therefore, the dust attached to the rotation detection mechanism D is blown out of the device. When the timer TM reaches a predetermined setting value, the relay R turns off, and the relay R switches the contact point of the rotation direction changeover switch S3 in the direction of the solid line to change the rotation direction of the fan to the normal forward rotation direction. Change. This state allows the fan to cool the components inside the device.

When the device power switch S1 is turned off, the timer
At the same time that TM is reset, the contact point of the rotation direction changeover switch S3 also returns to the direction of the solid line.

Note that the timer start switch S2 is the power switch S2.
It is also possible to make it possible to turn it on at any time without interlocking with 1, and to rotate it in reverse for a predetermined period of time.

(g) Effect of the invention As explained above, the cooling fan drive device of the invention can generate airflow in the direction of blowing away dust for a predetermined period of time when necessary, so that false detection by the rotation detection mechanism due to dust can be avoided. This has the effect of preventing

[Brief explanation of the drawing]

The figure shows a circuit diagram for explaining a cooling fan driving device according to the present invention. In the figure, F is a cooling fan, D is a rotation detection mechanism, RC is a rotation control unit, C is a phase advance capacitor,
S1 is a device power switch, S2 is a timer start switch, S3 is a rotation direction changeover switch, R is a relay, and TM is a timer.

Claims (1)

[Scope of utility model registration request] A configuration comprising a cooling fan that air-cools the inside of a device such as an electronic device, a rotation detection mechanism disposed within an airflow region generated by the fan, and a rotation control unit that controls rotation of the fan. , wherein the rotation control section has a timer and is controlled by the timer, and includes rotation direction switching means configured to rotate the fan in reverse during a predetermined period of time. .