JPH02115595A - Detection of revolution anomaly of fan - Google Patents

Abstract

PURPOSE:To cut the manufacture cost by a simple circuit constitution in which gear-shaped projections are formed on a detection plate for the rotary shaft of a fan and generating a dc voltage by rectification-smoothing the pulses generated in a coil each time when the projection passes and comparing said dc voltage with a standard voltage. CONSTITUTION:A rotary shaft 18 and blades 10 are revolved by a fan motor 28. The gear-shaped projection 17 of a detection plate 15 passes across the magnetic field of a permanent magnet 16, and generates the pulses in the number of teeth in one revolution in a coil. Said pulse is inputted into a detection circuit in a detection circuit box 14 and rectified in a bridge type all wave rectifying circuit and smoothed by a condenser, and a dc voltage is generated. When the number of revolution of a fan extremely reduces, a standard voltage is not realized, and a zenor diode which is installed so as to yield at the standard voltage does not yield, and an alarm signal is transmitted from a signal harness 25. Therefore, the need of a pulse counter circuit, etc., is obviated, and the circuit constitution is made simple, and the manufacture cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fan rotation abnormality detection method for detecting low rotation of a fan and outputting rotation abnormality to a fan control unit.

[Prior Art] Conventionally, as a fan sensor for detecting abnormal rotation of a fan of this type, the one shown in FIG. 4 is known. Figure 4 (
FIG. 4(a) is a plan view showing a conventional fan sensor made in Japan, and FIG. 4(b) is a side view thereof. In FIG. 4, reference numeral 10 indicates a blade, and the blade 1o is fixed to a rotating shaft 18. A detection plate 12 is provided on a portion of the rotating shaft 18 by one inch, and a protrusion 13 is provided at one edge of the periphery of the detection plate 12. Further, a permanent magnet 16 is installed outside the rotating shaft 18 so as to sandwich the detection plate 12, and the output of a coil (not shown) wound around the permanent magnet 16 is transmitted from the detection circuit box 14 via a signal harness 24. The information is transmitted to a control section (not shown). Note that the detection circuit box 14 is also connected to a DC power supply harness 26 that includes a reset signal line from the control section and a power supply line for the detection circuit. Furthermore, fan motor power harnesses 20 and 22 are connected to the fan motor 28 .

Next, the conventional fan sensor rotation abnormality detection method configured as described above will be explained using FIGS. 5 and 6. The detection plate 12 attached to the zero rotation shaft 18 rotates with the rotation of the fan. . At this time, since the protrusion 13 of the detection plate 12 crosses the magnetic field created by the permanent magnet 16 once per rotation of the fan, the coil (not shown) wound around the permanent magnet is As shown in FIG. 6, one pulse is generated per one rotation of the fan.The pulse generated by the rotation of the detection plate 12 is transmitted to the transistor 30 constituting the detection circuit provided in the detection circuit box 14 shown in FIG. The pulse amplified by the l-transistor 30 is input to the waveform shaping circuit 32 via a resistor.
After being waveform-shaped into a square wave, it is input to the counter circuit 34. The counter circuit 34 counts the number of input pulses and sends this count output to the signal harness 2.
4 to the control unit. At this time, the control section sends a reset signal to the counter circuit 34 at regular intervals of RIu'j via the DC power supply harness 26, and the counter circuit 34 is periodically reset to zero. Therefore, the control unit monitors the number of pulses sent from the counter circuit 34 within a certain period of time, and when the number of pulses within a certain period of time decreases, it determines that the fan is in a low rotation state and issues a fan rotation abnormality detection signal. It operates to output a fan alarm signal.

[Problems to be Solved by the Invention] However, according to the above-described fan rotation abnormality detection method, since the method uses a counter circuit to count the number of pulses generated in proportion to the fan rotation speed, a counter IC, etc. In addition, it requires a lot of wiring, such as a power line (power supply and ground) to the counter circuit in the fan sensor, a reset signal line to the counter circuit, and a signal line to send the output of the counter circuit to the control unit. The cost was high. In addition, it is necessary to create a software program for the control unit to send a reset signal to the counter circuit, determine rotation abnormality based on the number of count pulses transmitted from the counter circuit, and output a fan alarm signal, which is a cumbersome task. Met.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a method for detecting abnormal rotation of a fan, which requires less wiring and is simple! ? To provide a fan rotation abnormality detection method that requires only one configuration, does not require a software program, and can reduce costs.

[Means for Solving the Problems] A method for detecting abnormal rotation of a fan according to the present invention includes a detection plate provided on the rotation shaft of the fan, and a detection plate provided on the periphery of the detection plate. A permanent magnet is installed outside,
The fan is configured to detect abnormal rotation of the fan based on pulses generated from a coil wound around the permanent magnet when the protrusion of the detection plate passes through the magnetic field of the permanent magnet as the fan rotates. - In the rotational abnormality detection method of rn, the protrusion of the detection plate is formed in the shape of a gear, and when the gear-shaped protrusion of the detection plate passes through the magnetic field of the permanent magnet, a plurality of It detects pulses, rectifies and smoothes these pulses, converts them into DC voltage, compares the obtained DC voltage with a preset reference voltage, and generates a fan alarm signal when the DC voltage falls below the reference voltage. It is characterized by outputting.

[Function] According to the method for detecting abnormal rotation of a fan according to the present invention, the protrusions provided on the peripheral edge of the detection plate are gear-shaped, so that the coil that is not wound around the permanent magnet is generates multiple pulses. By converting these multiple pulses generated when the fan is rotating normally into a DC voltage, and setting the converted DC voltage to be the breakdown voltage of the Zener diode, a transistor that receives this breakdown current as input can be It becomes ON state and the detection circuit maintains a low level output which is a normal rotation signal. When the fan rotates abnormally, the number of pulses generated in a certain period of time decreases, so the voltage value of the converted DC voltage also decreases. Therefore, the reference voltage corresponding to the lower limit of normal rotation set by the Zener diode is no longer reached, and the transistor turns off.9 This detects low fan rotation, and the detection circuit outputs a high-level fan alarm signal. be able to.

[Example] Next, regarding the fan rotation abnormality detection method different from the present invention,
A detailed description will be given below with reference to the accompanying drawings.

FIGS. 1(a) and 1(b) are schematic structural diagrams of a fan sensor showing an embodiment of the present invention, in which FIG. 1(a) is a plan view, and FIG.
1) is a side view. In this embodiment, the same reference numerals are given to the same components as in the conventional example shown in FIG. 4, and detailed explanation thereof will be omitted. That is, in FIG. 1, a detection plate 15 having a continuous gear-shaped protrusion 17 is used instead of the detection plate 12 having a protrusion 13 shown in the conventional example, and a gable connected to the detection circuit box 14 is used. This is different from FIG. 4 in that only the signal harness 25 is present.

Next, a method for detecting abnormal rotation of the fan in this embodiment configured as described above will be explained with reference to FIGS. 2 and 3.

When power is supplied from the power harnesses 20 and 22 to the fan motor 28, the rotating shaft 18 and the blades 10 rotate.

At the same time, the detection plate 15 having a gear-shaped protrusion 17 also rotates, and in order to cross the magnetic field created by the permanent magnet 16, the detection plate 15 rotates. As shown in FIG. 2(b), the number of pulses generated is equal to the number of teeth of the gear-shaped protrusion 17 per rotation of the fan.

In this figure, 16 pulses are generated per rotation of the fan. A plurality of pulses generated by the detection plate 15 having the gear-shaped protrusion 17 are input to a detection circuit shown in FIG. 3 provided within the detection circuit Bonus 14. The detection circuit detects multiple input pulses through diodes 40 and 41.
, 42, 43, and then smoothed by a resistor 44 and a capacitor 45 and converted into a DC voltage. This DC voltage is applied to a series circuit of Zener diode 46 and resistors 47 and 48.

In this way, the DC voltage obtained by passing the fi number of pulses generated by the rotation of the detection plate 15 through the advection/smoothing circuit changes relative to the rotation speed of the fan.

Here, a DC voltage obtained by rectification and smoothing when the fan's normal rotational speed is at a lower value is used as a reference voltage, and a detection plate 15 having a gear-shaped protrusion 17 is set so that the Zener diode 116 breaks down at this reference voltage. Set the number of protrusions of the Zener diode 4 or have the breakdown voltage value of the reference voltage.
6 allows the I breakdown current to flow when the fan is rotating normally. As a result, a base current is supplied through the four resistors to the transistor 5o in which the oven collector output has failed, the transistor 50 is turned on, and a low level signal is sent to the control unit through the one-word harness 25.

When the fan is in an abnormal state of low rotation, the number of pulses per unit time decreases, and the DC voltage obtained by rectification and smoothing also decreases and no longer reaches the reference voltage. This lick,
Zener diode 46 does not break down, no current is supplied to the base of transistor 5o, and transistor 50 is turned off.
state, and a high-level fan alarm signal is sent to the control unit through the f-word harness 25. Therefore, the detection circuit can detect abnormal rotation of the fan.

[Effects of the Invention] As is clear from the embodiments described above, according to the present invention,
By making the detection plate for detecting abnormal rotation of the fan gear-shaped and generating multiple pulses per rotation of the fan, the Zener diode breaks down the DC voltage obtained by rectifying and smoothing. Since the voltage can be as high as that of Wires and signal lines are no longer required. In other words, the detection input signal itself uses the fS voltage obtained by rectifying and smoothing the pulse, and the output of the detection circuit has an open collector configuration, so that it is easy to reset the counter circuit from the external power supply line for the detection circuit and the control section. Signal lines become unnecessary.

In addition, instead of counting the number of pulses as in the past, abnormal rotation is detected by the ON/OFF signal of the transistor in the detection circuit itself, and a fan alarm signal is directly output as a detection signal. It is possible to eliminate the need to create a software program for the control unit for detection.

Therefore, according to the present invention, in the method for detecting abnormal rotation of a fan, the number of wires used is small and a simple circuit configuration is required, so that the effect of contributing to reduction of manufacturing costs is extremely large.

Although the preferred embodiment ρ1 of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are schematic diagrams of a fan sensor applied to the fan rotation abnormality detection method according to the present invention,
(a) is a plan view, (b) is a side view, and FIG. 2 (a) is a schematic diagram showing a detection plate having gear-shaped protrusions used in the fan rotation abnormality detection method according to the present invention together with fan blades. ,
FIG. 2(b) is a waveform diagram showing the pulse output per rotation of the fan when the detection plate having the gear-shaped protrusion shown in FIG. 2(a) is used, and FIG. A circuit diagram showing an embodiment of a fan alarm detection/output circuit implementing the rotational abnormality detection method of FIG. (a) is a plan view, (b) is a side view, and Fig. 5 (
a) is a schematic diagram showing a detection plate used in a conventional fan rotation abnormality detection method together with fan blades; FIG. 5(b)
) is a waveform diagram showing the pulse output per rotation of the fan when the detection plate of FIG. 5(a) is used, and FIG. 6 is a fan alarm detection circuit diagram implementing the conventional fan rotation abnormality detection method. . 13... Protrusion 15... Detection plate 17... Gear-shaped protrusion 18... Rotating shaft 24... Signal harness 26... Power supply harness 30... Transistor 34... Counter circuit, 10, 41, 42. 43...Tie 45...Capacitor 50...Transistor 14...Detection port box 1G...Permanent magnet 20, 22...Power harness 25...Signal harness 28 ...Fan motor 32...Waveform shaping circuit 44.47, 48.49.9. Resistor ode 4G... Zener diode 10... Vane 12... Detection plate FIG υ FIG

Claims (1)

[Claims] (1) A detection plate is attached to the rotating shaft of the fan, and a permanent magnet is installed outside the rotating shaft so as to sandwich the protrusion provided on the peripheral edge of the detection plate, and as the fan rotates, the magnetic field of the permanent magnet is generated. A method for detecting rotational abnormality of a fan configured to detect rotational abnormality of a fan based on pulses generated from a coil wound around the permanent magnet when the protrusion of the detection plate passes. The detection plate is formed into a gear shape, and detects a plurality of pulses generated per rotation of the fan when the gear-shaped protrusion of the detection plate passes through the magnetic field of the permanent magnet, and rectifies and smoothes these pulses to generate a DC voltage. A method for detecting abnormal rotation of a fan, characterized in that the obtained DC voltage is compared with a preset reference voltage, and a fan alarm signal is output when the DC voltage becomes equal to or lower than the reference voltage.