Application of LabVIEW in the production of wiper motors for Volkswagen Bora A4 sedans

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Application of LabVIEW in the production of wiper motors for Volkswagen Bora A4 sedans [Copy link]

In order to ensure the correctness of the voltage at the motor end, two feedback lines are added to the motor end, which are automatically adjusted by the voltage stabilizer. The voltage stabilizer is also a controllable type, that is, the analog acquisition card outputs a 0-5V variable signal to control the output of the voltage stabilizer. This ensures the correctness of the voltage at the motor end and the controllability of the program.

The magnetic powder brake also uses a controllable voltage-stabilized power supply, and different working voltages are selected for different test torques. Because the magnetic powder brake is a nonlinear element, in order to ensure the correctness of the test torque, engineers installed a calibrated torque sensor under the rotating disk of the motor test end and designed a calibration procedure.

The calibration method is: first install a lever at the motor rotation test end, hang a 500g weight at one end of the lever, and read the electrical signal of the torque sensor as the standard for that point. Then hang different weights such as 1000g, 1500g, and 2000g in turn to read the electrical signals at different points.

Remove the lever and weights, install a motor to be tested on the test fixture and power it on to make it rotate, then gradually increase the input voltage of the magnetic powder brake. At this time, the output electrical signal on the torque sensor also gradually increases. When the electrical signal value of the output point of the above different weights is reached, record the input voltage of the magnetic powder brake respectively. These voltages are the load voltages of these points. Then, according to the binary linear equation, calculate the K and B values between two adjacent points respectively, and you can get the approximate load working voltage value of any point of the magnetic powder brake.

The encoder used for speed test is a product of PEPPERL+FUCHS, with a resolution of 2500 pulses per revolution. The two counting terminals of the analog acquisition card 6024 are used to measure the speed of the motor under test and the angle of the motor. This work is already available in the LabVIEW software example and can be used as long as it is copied.

The current signal is sampled using a 30A/75mV 0.2 level current shunt, which is then converted into a 0~5V voltage through a current transmitter and sent to the analog input terminal of the acquisition card.

The sampling of voltage signal uses 0~30V/0~5V voltage signal isolator, and the 0~5V voltage is sent to the analog input terminal of the acquisition card. The

vibration measurement uses PCB acceleration sensor and amplifier. Each time the measurement is performed, the hanging bag with the sensor is lowered, and the magnet on the sensor is sucked on the motor housing for measurement. The vibration signal is processed by "Hanning window" and "spectrum" analysis and output vibration waveform. The frequency range of 10~4500Hz is divided into four frequency bands, and the vibration amount of each frequency band has different upper and lower limits to detect different defects of the motor.

At the same time, a group of motor vibration signals are continuously measured and identified and analyzed in the time domain. CGM (Case Growl Measurement): It is used to identify the waveform of the pulse signal of the motor rotor during the rotation cycle, and can measure the maximum and minimum values of the vibration signal of the motor rotor in each rotation. It can find many motor defects, such as worm teeth, commutator defects, and scratches on the worm bearing. PRI (Pulse Ratio Index): It can find the runout tolerance of two points on the shaft, shaft bending, and scratches on the commutator surface.

Different motor products and different test methods have different vibration waveforms. Only after accumulating a large amount of experience data can we correctly judge the defects of the motor based on the motor vibration waveform.

LabVIEW software has great advantages in vibration measurement and noise measurement. NI provides vibration and noise measurement software packages, and users can create their own applications by making slight modifications based on their actual conditions.

In order to ensure the accuracy of vibration testing, the acceleration sensor and amplifier should be calibrated regularly. During calibration, enter the vibration calibration program, use a 159.2Hz 1g (9.8m/s2) standard vibration source to apply vibration to the sensor, and read the amplifier signal at the same time to see if it reaches 1g, and make corrections, and save the correction coefficients in a text file for correction when testing the motor.

Storage of test data: During the test, since one motor is subjected to vibration test and the other motor is subjected to performance test at two workstations at the same time, two different files are used for data storage. The files are stored in EXCEL files with the date as the file name. The key here is to correctly determine the serial number of the motor.

Barcode printing: After the motor passes both tests, it is printed by a "Zebra" barcode printer. The barcode records the product model, serial number, date, etc. The serial number is consistent with the test serial number of the motor in the storage file, thereby achieving product traceability.

In practical applications, how to quickly detect equipment faults is a universal problem. In order to detect equipment faults more conveniently and intuitively, you can enter the fault detection subroutine by selecting the "Fault Detection" button on the main panel. The panel of this program places all the analog, digital I/O terminals and counting terminals used by the equipment. (As shown in Figure 2)

Figure 2 Equipment fault detection test interface

The analog input signal uses an oscilloscope display method, the analog output signal uses a knob control output method, the digital input signal uses an indicator light display method, the digital output signal uses a switch control output method, and the counting signal uses a button and digital display method.

This is very intuitive. Any action of the output knob or button will cause the action of the electrical components connected to the corresponding output terminal. At the same time, any changes in the switches and electrical signals connected to the periphery will be displayed on the screen. This is very convenient for equipment maintenance, but one thing that must be noted is that safety must be paid attention to in specific applications. Because some electrical appliances, such as motors and cylinders, can only be operated under specific conditions, otherwise accidents are prone to occur, so it is necessary to impose certain restrictions when applying.