On-line vibration detection device of fan

Abstract

A vibration on-line detection device of a fan is characterized in that current transformers are respectively connected in series in a three-phase current loop of a motor of the fan, when a secondary full-wave rectification voltage Uia of an A-phase current transformer BT1 of the current transformers is zero-crossing, a zero-crossing comparator outputs a zero-crossing signal Uk, so that an electronic switch IC1 and a second electronic switch IC2 are conducted; the operational amplifier A1 compares the secondary rectified voltage Uib of the B-phase current transformer BT2 with the secondary rectified voltage Uic of the C-phase current transformer BT3, and if the two instantaneous values are equal, the output of the operational amplifier A1 is 0, and dynamic balance of the fan is normal; if the instantaneous values are not equal, the output pulse signal of the operational amplifier A1 indicates that the dynamic balance of the fan is abnormal; the beneficial effects are that interference generated by power supply voltage fluctuation can be eliminated, and whether the vibration amplitude of the motor bearing exceeds an allowable range can be accurately determined; the vibration detection device is simple in structure, and the cost can be reduced; the vibration detection device is not mechanically connected with the fan, so that interference of vibration of the fan can be avoided, and installation and debugging are convenient.

Description

Technical Field

[0001] The invention relates to an online vibration detection device for a fan. Background Art

[0002] The structure of the direct-drive fan includes a motor and fan blades. The fan blades are installed on a shaft sleeve, and the shaft sleeve is connected to the main shaft of the motor. It has high transmission efficiency.

[0003] When the fan is running, the dust in the air will adhere to the fan blades unevenly. As the running time increases, the dust attached to the fan blades gradually destroys the dynamic balance of the fan, causing the vibration of the motor bearing to gradually increase. Once the vibration reaches the maximum value allowed by the fan, the fan must be shut down for maintenance. The fan vibration can be detected regularly using a handheld vibration measuring instrument. The handheld vibration measuring instrument cannot reflect the vibration of the fan in time. In addition, when the fan is installed at a high position, manual detection is very inconvenient. The fan vibration can also be detected by installing a vibration measuring instrument on the fan for online detection. The existing vibration measuring instruments are expensive. In addition, the sensor mounting bracket of the vibration measuring instrument must be set separately and cannot be installed on the frame of the fan to avoid interference from the fan vibration during detection. The installation and debugging of the vibration measuring instrument is inconvenient. Summary of the invention

[0004] In view of the above problems, the present invention proposes an online vibration detection device for a fan, which has high reliability, simple structure, low manufacturing cost and is easy to install and debug.

[0005] The technical solution of the present invention is an online vibration detection device for a fan, which includes a motor 201 and a fan blade 202, wherein the fan blade is mounted on a shaft sleeve 203, and the shaft sleeve is connected to a main shaft 204 of the motor, wherein an A-phase current transformer BT1, a B-phase current transformer BT2, and a C-phase current transformer BT3 are respectively connected in series in a three-phase current loop of the motor, wherein the secondary of the A-phase current transformer BT1 is connected to the input end of a bridge rectifier QT1, the negative pole of the output end of the bridge rectifier QT1 is grounded, the positive pole of the output end of the bridge rectifier QT1 is connected to the input end of a zero-crossing comparator, and the output end of the zero-crossing comparator is connected to the control end of a first electronic switch IC1 and the control end of a second electronic switch IC2; The secondary of the B-phase current transformer BT2 is connected to the input end of the bridge rectifier QT2, the negative electrode of the output end of the bridge rectifier QT2 is grounded, the positive electrode of the output end of the bridge rectifier QT2 is connected to one end of the first electronic switch IC1, the other end of the first electronic switch IC1 is connected to the inverting input end of the operational amplifier A1, and the inverting input end of the operational amplifier A1 is grounded through the resistor R4; The secondary of the C-phase current transformer BT3 is connected to the input end of the bridge rectifier QT3, the negative electrode of the output end of the bridge rectifier QT3 is grounded, the positive electrode of the output end of the bridge rectifier QT3 is connected to the non-inverting input end of the operational amplifier A1, and the non-inverting input end of the operational amplifier A1 is grounded through the resistor R6; When the A-phase current passes through zero, if the instantaneous value of the B-phase current is equal to the instantaneous value of the C-phase current, the output of the operational amplifier A1 is 0; if the instantaneous value of the B-phase current is not equal to the instantaneous value of the C-phase current, the output of the operational amplifier A1 outputs a pulse signal; The operating power supply of operational amplifier A1 is provided by positive power supply V+ and negative power supply V-.

[0006] Its working principle is that when the dynamic balance of the fan is normal, the amplitudes of the three-phase currents of the motor are equal. When the A-phase current of the motor passes through zero, the instantaneous values ​​of the B-phase current and the C-phase current of the motor are equal. When the dynamic balance of the fan is destroyed, the vibration of the motor bearing increases, the bearing wears, the rotor and the stator are not concentric, the air gap between the rotor and the stator changes periodically or randomly, and the amplitude of the three-phase current of the motor fluctuates. When the A-phase current of the motor passes through zero, the instantaneous values ​​of the B-phase current and the C-phase current of the motor are not equal. When the A-phase current of the motor passes through zero, the instantaneous values ​​of the B-phase current and the C-phase current of the motor are compared to determine whether the vibration amplitude of the motor bearing exceeds the allowable range.

[0007] Its beneficial effect is that when the A-phase current of the motor passes through zero, by comparing the instantaneous values ​​of the B-phase current and the C-phase current of the motor, the interference caused by the power supply voltage fluctuation can be eliminated, and it can be accurately judged whether the vibration amplitude of the motor bearing exceeds the allowable range; the vibration detection device has a simple structure and can reduce costs; the vibration detection device can be installed on the control box of the motor, and the detection device will not vibrate when the fan rotates, which can avoid the interference of the fan vibration and is easy to install and debug. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a circuit schematic diagram of the present invention.

[0009] Figure 2 for Figure 1 Waveform diagram of relevant points in .

[0010] Figure 3 Another circuit schematic diagram of a zero-crossing comparator.

[0011] Figure 4 This is a schematic diagram of the fan structure. DETAILED DESCRIPTION

[0012] The online vibration detection device of the fan includes a motor 201 and a fan blade 202. The fan blade is mounted on a shaft sleeve 203, and the shaft sleeve is connected to the main shaft 204 of the motor. The primary of the A-phase current transformer BT1 is connected in series in the motor A-phase current Ia loop, the primary of the B-phase current transformer BT2 is connected in series in the motor B-phase current Ib loop, and the primary of the C-phase current transformer BT3 is connected in series in the motor C-phase current Ic loop.

[0013] The secondary of the A-phase current transformer BT1 is connected to the input end of the A-phase bridge rectifier QT1, the negative pole of the output end of the A-phase bridge rectifier QT1 is grounded, the positive pole of the output end of the A-phase bridge rectifier QT1 is connected to the input end of the zero-crossing comparator, and the output end of the zero-crossing comparator is connected to the control end of the first electronic switch IC1 and the control end of the second electronic switch IC2.

[0014] The secondary of the B-phase current transformer BT2 is connected to the input end of the B-phase bridge rectifier QT2, the negative pole of the output end of the B-phase bridge rectifier QT2 is grounded, the positive pole of the output end of the B-phase bridge rectifier QT2 is connected to one end of the first electronic switch IC1, the other end of the first electronic switch IC1 is connected to the inverting input end of the operational amplifier A1, and the inverting input end of the operational amplifier A1 is grounded through the resistor R4.

[0015] The secondary of the C-phase current transformer BT3 is connected to the input end of the C-phase bridge rectifier QT3, the negative pole of the output end of the C-phase bridge rectifier QT3 is grounded, the positive pole of the output end of the C-phase bridge rectifier QT3 is connected to one end of the second electronic switch IC2, the other end of the second electronic switch IC2 is connected to the non-inverting input end of the operational amplifier A1, and the non-inverting input end of the operational amplifier A1 is grounded through the resistor R6.

[0016] The zero-crossing comparator includes a resistor R1, a transistor T1, a transistor T2, and a resistor R2. The positive electrode of the output end of the bridge rectifier QT1 is connected to the base of the transistor T1 through the resistor R1, the emitter of the transistor T1 is grounded, the collector of the transistor T1 is connected to the base of the transistor T2, the emitter of the transistor T2 is grounded, and the collector of the transistor T2 is connected to the positive power supply V+ through the resistor R2; the collector of the transistor T2 is connected to the control end of the first electronic switch IC1 and the control end of the second electronic switch IC2. The connection point of the output end of the resistor R1 bridge rectifier QT1 is the input end of the zero-crossing comparator, and the collector of the transistor T2 is the output end of the zero-crossing comparator.

[0017] like Figure 3As shown, the zero-crossing comparator may also be another structure, which includes an operational amplifier A2, wherein the non-inverting input terminal of the operational amplifier A2 is connected to the input terminal of the bridge rectifier QT1 through a resistor R9, the inverting input terminal of the operational amplifier A2 is grounded through a resistor R10, and the output terminal of the operational amplifier A2 outputs a pulse voltage Uk, wherein the connection point between the resistor R9 and the input terminal of the bridge rectifier QT1 is the input terminal of the zero-crossing comparator, and the output terminal of the operational amplifier A2 is the output terminal of the zero-crossing comparator.

[0018] The operating power supply of operational amplifier A2 is provided by a positive power supply V+ and a negative power supply V-.

[0019] A variable resistor R3 is connected between the other end of the first electronic switch IC1 and the inverting input end of the operational amplifier A1, and a variable resistor R5 is connected between the other end of the second electronic switch IC2 and the non-inverting input end of the operational amplifier A1. When a voltage transformation proportional coefficient error occurs between the C-phase current transformer and the B-phase current transformer due to manufacturing reasons (i.e., the C-phase current and the B-phase current are equal but their output voltages are not equal), the voltage transformation proportional coefficient error can be eliminated by adjusting the variable resistor R3 or the variable resistor R5; in addition, the slopes of the full-wave DC voltage Uib and the full-wave DC voltage Uic waveforms can be changed by adjusting the variable resistor R3 and the variable resistor R5.

[0020] The first electronic switch IC1 and the second electronic switch IC2 are integrated circuits, whose model is CD4016. One end of the first electronic switch IC1 is pin 1 of the integrated circuit CD4016, the other end of the first electronic switch IC1 is pin 2 of the integrated circuit CD4016, and the control end of the first electronic switch IC1 is pin 13 of the integrated circuit CD4016; one end of the second electronic switch IC2 is pin 4 of the integrated circuit CD4016, the other end of the second electronic switch IC2 is pin 3 of the integrated circuit CD4016, and the control end of the second electronic switch IC2 is pin 5 of the integrated circuit CD4016.

[0021] The output end of the operational amplifier is connected to the cathode of the light emitting diode LED1 through the resistor R7, and the anode of the light emitting diode LED1 is grounded. The output end of the operational amplifier is connected to the anode of the light emitting diode LED2 through the resistor R8, and the cathode of the light emitting diode LED2 is grounded.

[0022] The operating power supply of the operational amplifier is provided by the positive power supply V+ and the negative power supply V-.

[0023] The circuit principle is that the A-phase current transformer converts the A-phase current into the corresponding AC voltage, and the full-wave DC voltage Uia (such as Figure 2 b shown in bold line); The B-phase current transformer converts the B-phase current into a corresponding AC voltage, which is rectified by the B-phase bridge rectifier QT2 to output a full-wave DC voltage Uib (such as Figure 2 b as indicated by thin lines); The C-phase current transformer converts the C-phase current into a corresponding AC voltage, which is rectified by the C-phase bridge rectifier QT2 to output a full-wave DC voltage Uic (such as Figure 2 b is shown by the dotted line); The zero-crossing comparator judges the waveform of Uia. When Uia is zero, the zero-crossing comparator outputs a pulse voltage Uk (such as Figure 2 c), the pulse voltage Uk controls the first electronic switch IC1 and the second electronic switch IC2 to turn on, and the full-wave DC voltage Uib and the full-wave DC voltage Uic are sent to the operational amplifier A1 for comparison. When the value of Uib is equal to the value of Uic, the output signal Uo of the operational amplifier A1 is zero; when Uib is greater than Uic, the output signal Uo of the operational amplifier A1 is a negative pulse; when Uib is less than Uic, the output signal Uo of the operational amplifier A1 is a positive pulse.

[0024] When the dynamic balance of the fan is normal, when the A-phase current of the motor passes through zero, the instantaneous values ​​of the B-phase current and the C-phase current of the motor are equal in magnitude and opposite in polarity (such as Figure 2 a), that is, when Uia is zero, the instantaneous value of Uib is equal to the instantaneous value of Uic (as shown in Figure 2 b).

[0025] After the dynamic balance of the fan is destroyed, the vibration of the motor bearing increases, the bearing wears, the rotor and stator are not concentric, the magnetic field air gap between the rotor and the stator changes periodically or randomly, and the current of each phase of the motor fluctuates. When the A-phase current of the motor passes through zero, the instantaneous values ​​of the B-phase current and the C-phase current of the motor will be unequal, such as the B-phase current increases while the C-phase current decreases, or the B-phase current decreases while the C-phase current increases.

[0026] When the dynamic balance of the fan is normal, the output voltage of operational amplifier A1 is 0 volts. When the dynamic balance of the fan is destroyed, operational amplifier A1 outputs positive pulses or negative pulses, making the light-emitting diodes LED1 or LED2 light up, indicating that the dynamic balance of the fan is abnormal. The positive pulses or negative pulses output by operational amplifier A1 can also be used as control signals to stop the motor or for other purposes.

[0027] When the A phase current passes through zero, it can determine whether the instantaneous values ​​of the B phase current and the C phase current are equal, which can eliminate the interference caused by the fluctuation of the power supply voltage and make the judgment accurate. During the operation of the fan, it can timely reflect whether the dynamic balance of the fan is normal. The vibration detection device is installed on the control box of the motor. There is no mechanical connection between the vibration detection device and the fan. When the fan rotates, the detection device will not vibrate, which can avoid the interference of fan vibration and is easy to install and debug.

Claims

1. A vibration online detection device for a fan, comprising a motor and a fan blade, wherein the fan blade is mounted on a shaft sleeve, and the shaft sleeve is connected to the main shaft of the motor, wherein the device is characterized in that: In the three-phase current loop of the motor, an A-phase current transformer BT1, a B-phase current transformer BT2, and a C-phase current transformer BT3 are respectively connected in series, wherein the secondary of the A-phase current transformer BT1 is connected to the input end of the bridge rectifier QT1, the negative electrode of the output end of the bridge rectifier QT1 is grounded, the positive electrode of the output end of the bridge rectifier QT1 is connected to the input end of the zero-crossing comparator, and the output end of the zero-crossing comparator is connected to the control end of the first electronic switch IC1 and the control end of the second electronic switch IC2; The secondary of the B-phase current transformer BT2 is connected to the input end of the bridge rectifier QT2, the negative electrode of the output end of the bridge rectifier QT2 is grounded, the positive electrode of the output end of the bridge rectifier QT2 is connected to one end of the first electronic switch IC1, the other end of the first electronic switch IC1 is connected to the inverting input end of the operational amplifier A1, and the inverting input end of the operational amplifier A1 is grounded through the resistor R4; The secondary of the C-phase current transformer BT3 is connected to the input end of the bridge rectifier QT3, the negative electrode of the output end of the bridge rectifier QT3 is grounded, the positive electrode of the output end of the bridge rectifier QT3 is connected to the non-inverting input end of the operational amplifier A1, and the non-inverting input end of the operational amplifier A1 is grounded through the resistor R6; When the A-phase current passes through zero, if the instantaneous value of the B-phase current is equal to the instantaneous value of the C-phase current, the output of the operational amplifier A1 is 0; if the instantaneous value of the B-phase current is not equal to the instantaneous value of the C-phase current, the output of the operational amplifier A1 outputs a pulse signal; The operating power supply of operational amplifier A1 is provided by positive power supply V+ and negative power supply V-.

2. The online vibration detection device for a fan according to claim 1 is characterized in that: The zero-crossing comparator includes a resistor R1, a transistor T1, a transistor T2, and a resistor R2. The positive electrode of the output end of the bridge rectifier QT1 is connected to the base of the transistor T1 through the resistor R1, the emitter of the transistor T1 is grounded, the collector of the transistor T1 is connected to the base of the transistor T2, the emitter of the transistor T2 is grounded, and the collector of the transistor T2 is connected to the positive power supply V+ through the resistor R2; the collector of the transistor T2 is connected to the control end of the first electronic switch IC1 and the control end of the second electronic switch IC2; wherein the connection point between the resistor R1 and the output end of the bridge rectifier QT1 is the input end of the zero-crossing comparator, and the collector of the transistor T2 is the output end of the zero-crossing comparator. .

3. The online vibration detection device for a fan according to claim 1 is characterized in that: The zero-crossing comparator includes an operational amplifier A2, a non-inverting input terminal of the operational amplifier A2 is connected to an input terminal of a bridge rectifier QT1 through a resistor R9, an inverting input terminal of the operational amplifier A2 is grounded through a resistor R10, and an output terminal of the operational amplifier A2 is connected to a control terminal of a first electronic switch IC1 and a control terminal of a second electronic switch IC2; wherein a connection point between the resistor R9 and the input terminal of the bridge rectifier QT1 is an input terminal of the zero-crossing comparator, and an output terminal of the operational amplifier A2 is an output terminal of the zero-crossing comparator; and a working power supply of the operational amplifier A2 is provided by a positive power supply V+ and a negative power supply V-.

4. The online vibration detection device for a fan according to claim 2 or 3, characterized in that: A variable resistor R3 is connected between the other end of the first electronic switch IC1 and the inverting input end of the operational amplifier A1 , and a variable resistor R5 is connected between the other end of the second electronic switch IC2 and the non-inverting input end of the operational amplifier A1 .

5. The online vibration detection device for a fan according to claim 2 or 3, characterized in that the calculation The output end of the amplifier is connected to the cathode of the light emitting diode LED1 through the resistor R7, and the anode of the light emitting diode LED1 is grounded. The output end of the operational amplifier is connected to the anode of the light emitting diode LED2 through the resistor R8, and the cathode of the light emitting diode LED2 is grounded.

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