JP3982861B2 - Fan motor with rotation abnormality detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fan motor with a rotation abnormality detector.
[0002]
[Prior art]
Conventionally, a fan motor that cools equipment or devices that have parts that generate heat during operation has a predetermined rotation speed or less in order to prevent an abnormal temperature rise in the equipment due to a rotation stop caused by a failure of the fan motor. There is a type having a rotation abnormality detector that sends out a warning signal (alarm) when an alarm occurs.
As shown in FIG. 5, the basic principle of the rotation abnormality detection circuit is to convert an AC voltage from a speed detection generator 103 installed integrally via a fan motor 101 and a rotation shaft 102 into a DC voltage by a rectification and smoothing circuit 104. And the converted DC voltage is compared with the reference voltage V1 to detect an abnormality in the rotational speed. The voltage from the speed detection generator 103 is approximately proportional to the rotational speed of the fan motor 101. As a result, the voltage corresponding to the rotational speed at which the abnormality is to be detected is set as the reference voltage V1, and the comparison circuit 105 is used for comparison. Is detected, and an alarm is generated by the output of the comparison circuit 105. Normally, the abnormality detection rotation speed is approximately 70% of the normal rotation speed, and the normal rotation speed is constant, so the reference voltage V1 corresponding to the abnormality detection rotation speed is also a constant value.
[0003]
[Problems to be solved by the invention]
Recently, a device that generates pseudo alternating current called an inverter has been widely used. By using this inverter, the fan motor can be rotated at an arbitrary rotational speed, and it is most suitable for equipment that uses air volume and noise. Now it can be set in good condition. However, since the abnormality detection rotational speed is a constant value, depending on the operating state, there has been a problem that the rotational speed of the fan motor falls below the abnormality detection rotational speed and it is considered that the fan motor has failed.
[0004]
The above problem occurs when designing a device using a fan motor, because the rotation speed of the fan motor can be set arbitrarily, but the abnormality detection rotation speed is a constant value. . As a countermeasure, for example, a method of comparing a pulse generated every rotation of a fan and a rotation speed monitoring pulse disclosed in Japanese Patent Laid-Open No. 4-252898 is applied, and the rotation speed monitoring pulse is linked with a power supply frequency. If the rotation abnormality detector is configured as described above, a temporary solution can be achieved. However, with this method, it is necessary to configure the power supply part so that rotation abnormality can be detected from the cycle of the pulses generated from the fan motor, the rotation speed monitoring pulse, and the power supply frequency, and this is difficult to realize. there were.
[0005]
The present invention has been made in view of the above circumstances, and its purpose is to monitor the presence or absence of an abnormality in the rotation of a fan motor at an abnormality detection rotational speed suitable for the power supply frequency, and the same applies to conventional devices. An object of the present invention is to provide a fan motor with a rotation abnormality detector that can be used for the above.
[0006]
[Means for Solving the Problems]
The present invention has been made to solve the above-described object, and includes a detection signal output from a speed detector connected to a rotation shaft of a fan motor and a reference signal for determining abnormal rotation of the fan motor. In the fan motor with rotation abnormality detector that is compared by the comparison circuit and generates an alarm from the difference, it is as follows.
The detection signal output from the speed detector is a voltage proportional to the rotational speed of the fan motor, and the reference signal is proportional to the frequency of an AC power source that supplies power to the fan motor to drive the fan motor. This is a fan motor with a rotation abnormality detector that is a voltage that is generated.
The fan motor with a rotation abnormality detector outputs the reference signal from a signal generator as a signal proportional to the frequency of an AC power supply that supplies power to the fan motor to drive the fan motor.
Further, the detection signal output from the speed detector is a voltage proportional to the rotational speed of the fan motor, and the reference signal is the frequency of an AC power supply that supplies power to the fan motor to drive the fan motor. Rotation abnormality detection that generates an alarm when the voltage proportional to the frequency of the fan motor is output from the frequency-voltage conversion circuit and the voltage proportional to the rotation speed of the fan motor falls below the reference signal voltage. It is a fan motor with a vessel.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of a fan motor with a rotation abnormality detector according to the present invention. A speed detection generator 3 installed integrally with the fan motor 1 via the rotating shaft 2 generates an AC voltage having a magnitude proportional to the rotational speed of the fan motor 1. This AC voltage is converted into a DC voltage by the rectification and smoothing circuit 4. Next, the comparison circuit 5 is proportional to the voltage corresponding to the rotational speed at which the abnormality is to be detected, that is, the abnormality detection reference voltage V1, and the rotational speed of the fan motor 1 converted to a DC voltage by the rectifying and smoothing circuit 4. When the voltage having a magnitude proportional to the rotational speed of the fan motor 1 falls below the reference voltage V1 for abnormality detection, an alarm is output. At this time, the abnormality detection reference voltage V1 is conventionally a constant value, but in the present invention, the voltage from the frequency-voltage conversion circuit 7 connected in parallel to the AC power source 6 is used as the abnormality detection reference voltage. Used as V1. The frequency-voltage conversion circuit 7 generates a voltage proportional to the frequency of the power source 6 as the abnormality detection reference voltage V1, while the fan motor 1 rotates at a rotational speed substantially proportional to the frequency of the power source 6. The ratio between the voltage having a magnitude proportional to the rotational speed of the fan motor 1 and the abnormality detection reference voltage V1 is substantially constant regardless of the frequency of the power supply. Therefore, even if the rotation speed at the normal time changes depending on the frequency of the power supply 6, the abnormality detection rotation speed also changes at the same rate. The number can be set as the abnormality detection rotational speed.
[0008]
Here, the frequency-voltage conversion circuit 7 that plays the central role of the present invention will be described in detail based on an example. FIG. 2 shows a configuration using a monostable multivibrator as an example of the frequency-voltage conversion circuit. FIG. 3 is an operation waveform diagram of each part of FIG.
The photocoupler PC connected in parallel to the AC power supply operates the internal transistor only when the power supply voltage is positive. Therefore, the collector voltage of the photocoupler PC connected to the DC power supply via the resistor R2 becomes a pulse b shown in FIG. 3 with respect to the voltage waveform a of the power supply shown in FIG.
[0009]
Next, the pulse b shown in FIG. 3 is converted into a pulse c as shown in FIG. 3 by a differentiating circuit including a capacitor C1 and a resistor R3. That is, when the pulse b in FIG. 3 rises, it is converted into a positive sharp pulse, and when it falls, it is converted into a negative sharp pulse. This positive sharp pulse operates a monostable multivibrator composed of an operational amplifier OP, a capacitor C2, a resistor R4, a diode D1, and resistors R5 and R6 in the subsequent stage to generate a pulse having a certain length.
[0010]
That is, when the voltage waveform c in FIG. 3 exceeds the reference voltage (waveform e shown in FIG. 3) generated by the resistance division composed of the resistors R5 and R6, the operational amplifier OP outputs a voltage substantially equal to the voltage of the DC power supply. . This output returns to the + input side of the operational amplifier OP via the capacitor C2, and the + input side is maintained at a voltage level higher than the reference voltage. On the other hand, a resistor R4 is also connected to the + input side of the operational amplifier OP, and the voltage level on the + input side gradually decreases via the resistor R4. This is the operation waveform d in FIG. The diode D1 is used to prevent the voltage on the input side of the operational amplifier OP from rapidly decreasing through the previous resistor R3. Since the output of the operational amplifier OP stops when the operation waveform d shown in FIG. 3 falls below the waveform e showing the reference voltage, as a result, a constant voltage generated in the period of the power supply voltage as shown in f of FIG. A pulse of length is obtained. When this pulse f is smoothed by an integrating circuit comprising a resistor R7 and a capacitor C3, a DC voltage signal shown in g of FIG. 3 is obtained. Even if the frequency of the power supply changes, the length of the pulse f does not change. Therefore, when the frequency of the power supply is high, the ratio of the time output at f in FIG. The voltage level of g of 3 becomes high.
[0011]
On the other hand, when the frequency of the power source is low, the ratio of the time output at f in FIG. 3 is small, and the voltage level of g in FIG. 3 is low. With the above operation, a voltage g proportional to the frequency of the voltage waveform a of the power supply is obtained.
The above description is an example of a frequency-voltage conversion circuit using an operational amplifier, but this is an example, and for example, digital processing may be performed, and there is no difference in the effect of the present invention.
[0012]
As another embodiment, an example in which an abnormality in the rotational speed of the fan motor 1 is determined based on a triangular wave generated every rotation of the fan motor 1 will be described with reference to FIG. Magnets 8 alternately magnetized in the radial direction that are integrally installed on the rotating shaft 2 of the fan motor 1 rotate in accordance with the rotation of the fan motor 1 and change the magnetic flux density. This change in magnetic flux density is converted into a voltage signal by the Hall element 9 incorporated in the fan motor 1. Since the output from the Hall element 9 is a voltage proportional to the change in the magnetic flux density due to the rotation of the magnet 8, this is converted into a pulse by the comparison circuit 10 and further converted into a sharp pulse output at the rise of the pulse by the differentiation circuit 11. Convert. Based on the sharp pulse output from the differentiating circuit 11, the triangular wave generating circuit 12 generates a predetermined number of triangular waves rising at a predetermined rate for each rotation of the fan motor 1. Next, the monostable multivibrator 13 compares the peak value of the triangular wave with the abnormality detection reference voltage V1, and generates a pulse having a fixed length when the triangular wave peak value exceeds the abnormality detection reference voltage V1. . This pulse serves as an alarm for notifying the rotation abnormality of the fan motor 1, but in the example shown in FIG. 4, it is related to the abnormality of the fan motor 1 due to a low rotation state at the start of the fan motor 1 or malfunction due to noise. In order to prevent alarms that occur without any problems, it has a function to delay the output. That is, a pulse having a certain length generated from the monostable multivibrator 13 is accumulated in the capacitor 14, the terminal voltage of the capacitor 13 and the output delay operation reference voltage V 2 are compared by the comparison circuit 15, and the monostable multivibrator 13 An alarm output is generated when the voltage of the capacitor 14 exceeds the reference voltage V2 due to the output from. At this time, the abnormality detection reference voltage V1 is conventionally set to a constant value, but in the present embodiment, the voltage from the frequency-voltage conversion circuit 7 connected in parallel to the AC power source 6 is used as the abnormality detection voltage. Used as the reference voltage V1. The frequency-voltage conversion circuit 7 generates a voltage proportional to the frequency of the power supply 6 as the abnormality detection reference voltage V1, while the fan motor 1 rotates at a rotational speed substantially proportional to the frequency of the power supply 7. The ratio between the peak value of the triangular wave generated by a predetermined number per rotation of the fan motor 1 and the abnormality detection reference voltage V1 is substantially constant regardless of the frequency of the power source. Therefore, even if the normal rotation speed changes depending on the power supply frequency, the abnormality detection rotation speed also changes at the same rate. It is possible to set the abnormality detection rotation speed.
[0013]
In FIG. 4, the rotation of the fan motor 1 is detected by the magnet 8 and the Hall element 9 fixed to the rotating shaft 2 of the fan motor 1, but for speed detection integrated with the fan motor 1 as shown in FIG. 1. The signal from the generator 3 may be used.
Except for the third aspect of the circuit configuration of FIG. 4, there is no difference in the effects of the present invention even if the details are changed.
In the present embodiment, the axial fan motor has been described as an example. However, it is clear that the same effect can be obtained with either a centrifugal fan or a cross-foo fan, and there is no difference in the effect of the present invention.
And as an effect | action by this invention, it becomes possible by the above-mentioned structure to set abnormality detection rotation speed according to a power supply frequency with a fan motor itself, and to detect rotation abnormality.
[0014]
【The invention's effect】
As described above, according to the fan motor with a rotation abnormality detector according to the present invention, it is possible to set the abnormality detection rotation speed corresponding to the power supply frequency by the fan motor itself and detect rotation abnormality.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a fan motor with a rotation abnormality detector according to the present invention.
FIG. 2 is an example of a frequency-voltage conversion circuit diagram.
3 is an operation waveform diagram of each part of the circuit of FIG. 2;
FIG. 4 is a schematic view showing a fan motor with a rotation abnormality detector according to another embodiment. FIG. 5 is a schematic view showing a conventional fan motor with a rotation abnormality detector.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fan motor 2 Rotating shaft 3 Speed detection generator 4 Rectification and smoothing circuit 5 Comparison circuit 6 Power supply 7 Frequency-voltage conversion circuit 8 Magnet 9 Hall element 10 Comparison circuit 11 Differentiation circuit 12 Triangular wave generation circuit 13 Monostable multivibrator 14 Capacitor 15 Comparison Circuit V1 Abnormality Detection Reference Voltage V2 Output Delay Operation Reference Voltage PC Photocoupler OP Operational Amplifier D1 Diode C1 Capacitor C2 Capacitor C3 Capacitor R1 Resistor R2 Resistor R3 Resistor R4 Resistor R5 Resistor R6 Resistor R7 Resistor

Claims (3)

A comparison circuit compares the detection signal output from the speed detector connected to the rotating shaft of the fan motor and the reference signal for judging the abnormal rotation of the fan motor, and an alarm is generated from the difference. In the fan motor with rotation abnormality detector,
The detection signal output from the speed detector is a voltage proportional to the rotational speed of the fan motor, and the reference signal is proportional to the frequency of an AC power source that supplies power to the fan motor to drive the fan motor. Fan motor with rotation abnormality detector, A comparison circuit compares the detection signal output from the speed detector connected to the rotating shaft of the fan motor and the reference signal for judging the abnormal rotation of the fan motor, and an alarm is generated from the difference. In the fan motor with rotation abnormality detector,
A fan motor with a rotation abnormality detector, characterized in that the reference signal is output from a signal generator as a signal proportional to the frequency of an AC power supply for supplying power to the fan motor to drive the fan motor. The detection signal output from the speed detector connected to the rotation shaft of the fan motor and the reference signal for judging the abnormal rotation of the fan motor are compared by a comparison circuit, and an alarm is generated from the difference signal. In the fan motor with rotation abnormality detector
The detection signal output from the speed detector is a voltage proportional to the rotational speed of the fan motor, and the reference signal is proportional to the frequency of an AC power supply that supplies power to the fan motor to drive the fan motor. As a voltage to be output from the frequency-voltage conversion circuit,
A fan motor with a rotation abnormality detector, wherein the alarm is generated when a voltage proportional to the rotation speed of the fan motor is lower than a voltage of the reference signal in the comparison circuit.

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