JPS63173969A - Rotational direction detecting system of fan - Google Patents

Abstract

PURPOSE:To enable detection of rotational direction of a fan with a simple construction, by mounting a magnet piece on a rotary member of a fan, and two pickup coils on a fixing section of the fan. CONSTITUTION:A magnet piece 4 is mounted on a rotary member at the rotating section 2 of a fan 1 and two pickup coils 5 and 6 are mounted on a fixing section 3 of the fan 1 at a desired interval not in axial symmetry. Pulses induced by both of pickup coils 5 and 6 are introduced to a comparator circuit 7 to compare relative time intervals of the pulses, thereby detecting the rotational direction of the fan 1.

Description

[Detailed Description of the Invention] [Summary] The present invention is a method for detecting the rotational direction of a fan, which detects the relative relationship between pulses induced by a magnet piece attached to a rotating member of the fan in two pickup coils attached to a fixed part. The comparison circuit compares the target time intervals, detects the rotation of the fan, and prevents air from being blown in a direction opposite to the predetermined direction.

[Industrial application field]

The present invention relates to a fan rotation direction detection method.

In electronic devices, the heat generated by device components is cooled by blowing air from fans, increasing the packaging density of the components and creating compact, high-performance devices.

However, if the fan is installed incorrectly, the direction of the air blowing may be reversed, reducing the cooling effect of the fan and causing damage to components due to temperature rise, which may lead to equipment failure.

Therefore, there is a need for a simple method that detects the direction of air blowing from the fan and prevents back air blowing.

[Conventional technology]

If the fan is driven by a three-phase motor, the fan's air blowing direction is determined by the motor's rotational direction, and the motor's rotational direction is determined by the phase connection of the motor power supply lines, so phase detection is required to electrically detect the phase connection. The equipment was checked to ensure that the predetermined phase connections were made.

I also put my hand on the fan's ventilation hole and watched the direction of the fan's air flow by the feel of my hand.

[Problem that the invention seeks to solve]

In the former method of detecting the air blowing direction described above, even if the phase direction in which power is transmitted is correct, the phase connection at the location of phase detection and the phase connection at the actual fan connection terminal may be different. Even if the detector determines that the phase connection is correct, the fan may not be blowing air in the desired direction.

Also, although the latter method described above is extremely straightforward and simple, this method is not possible unless the location of the fan's ventilation holes is accessible.

The present invention was created in view of these points, and it compares the relative time relationship between the pulses induced in the magnet piece attached to the rotating part of the fan and the two pickup coils. The purpose of this project is to provide a simple method for detecting the direction of air flow.

[Means for solving problems]

In order to achieve the above object, a magnet piece is attached to the rotating member of the rotating part of the fan, and two pickup coils are attached to the fixed part of the fan at arbitrary intervals that are not axially symmetrical.

Then, the pulses induced in each pickup coil are introduced into a comparison circuit, and the relative time intervals of the pulses are compared.

[Effect]

The pulse time of a pulse induced by a magnet piece attached to a rotating member rotating in one direction and passing through a first pink-up coil, and a pulse induced by passing a second pickup coil. interval and
On the other hand, the pulse time interval of the pulse induced by the magnet piece passing through the second pickup coil and the pulse induced by passing the first pickup coil is compared within one rotation of the fan.

The magnitude relationship between these two pulse time intervals is determined by the rotation direction of the rotating part, and when the rotation direction of the fan is reversed, the magnitude relationship between the two pulse time intervals is also reversed.

The direction of rotation is detected by comparing the magnitude relationship between the pulse time intervals using a comparator circuit.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the fan rotation direction detection method of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram illustrating the relative relationship of pulses.

As shown in FIG. 1, a magnet piece 4 is attached to the rotating part 3 of the fan 1, for example, to the tip of one blade, and pickup coils 5 and 6 are attached to two places on the frame around the rotating blade.

In this case, the two pickup coils 5, 6 are installed at positions where the time the magnet pieces 4 take to travel from the pickup coil 5 to the pickup coil 6 is not the same.

That is, the two pickup coils 5 and 6 are mounted so as not to be in symmetrical positions with respect to the rotation axis.

In order to ensure the effectiveness of the present invention, the two pickup coils 5 and 6 are mounted at right angles or at acute angles as shown in FIG.

As the fan 1 rotates, pulses C1 and C2 are induced in the pickup coils 5 and 6, respectively, as shown in FIG.

Then, let T1 be the time when the pulse CI is generated and the pulse C2 is generated, and let T2 be the time when the pulse C2 is generated and the pulse C1 is generated.

When the fan 1 rotates in the direction of the arrow in FIG. 2(a), TI<72 holds true.

Further, when the fan 1 rotates in the direction of the arrow in FIG. 2(b), that is, in the opposite direction to that in FIG. 2(a), TI>72 holds true.

The comparison circuit 7 monitors the magnitude relationship between the pulse time intervals T1 and T2, and if the preset magnitude relationship between T1 and T2 does not hold, it sends a signal to the alarm generation circuit 8 to reverse rotation of the fan l. be notified.

For the purpose of pulse generation, fan 1 is used as shown in Figure 1.
The magnet pieces 4 attached to the blades of the fan 1 are not large enough to disrupt the rotational balance of the fan 1.

Furthermore, the mounting location of the magnet piece 4 is not limited to the tip of the blade of the fan 1, but may also be mounted on a rotating member, for example, around the mounting shaft of the blade, and the position relative to the pickup coil 5.6 may be capable of generating pulses. Needless to say, it's fine.

Furthermore, in the above embodiment, in order to extract the pulse,
Although the explanation was made using a sensor that combines a magnet piece and a pickup coil, combinations with other types of sensors,
For example, it is obvious that a magnet piece and an electromagnetic conversion element, or a metal piece and a metal detector, etc. may be used.

〔Effect of the invention〕

As described above, according to the present invention, by detecting the rotating direction of the fan, in the case of reverse air flow, the cooling effect of the fan on the parts decreases, causing the parts to rise in temperature and be damaged.
Furthermore, the occurrence of burnout accidents can be prevented, which is extremely useful in practical terms.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining one embodiment of the present invention, and FIG.
It is a figure explaining the relative relationship of a pulse. In the figure, l is the fan, 2 is the rotating part, 3 is the fixed part, 4 is the magnet piece, 5.6 is the pickup coil, 7 is the comparison circuit, tb+ 4 pulses tfield 1 1e 9 pieces O concave Fig. 2

Claims (1)

[Claims] A magnet piece (4) attached to a rotating member that rotates together with the rotating part (2) of the fan (1), and a magnet piece (4) that rotates on the fixed part (3) of the fan. A fan (1) comprising two pickup coils (5, 6) installed at arbitrary rotational circumferential positions not symmetrical to the rotational axis of the fan so as to generate induced pulses in opposition; 1) It is equipped with a comparison circuit (7) that compares the time interval between the pulses generated in each pickup coil (5, 6) within one rotation and the pulses generated in other pickup coils as a reference. A fan rotation direction detection method featuring: