The speed-regulating motor acts as a drive component to provide power to the entire system to ensure proper operation of the system. Different test systems and different working conditions require different transmission speeds. The speed provided by the speed regulating motor should be smooth and adjustable, and have a large speed adjustment range. The biggest advantage of DC motors compared with AC motors is their good running performance and control characteristics. Therefore, DC motors are still widely used in adjustable electric drives that require high braking torque, fast response and wide speed adjustment range. To implement the DC speed control system of the motor. Although the AC motor has poor speed regulation performance, it is simple in structure, cheap in price and less in failure, and is still used in many applications. Especially in recent years, with the development of power electronics technology, many advanced technologies such as PWM, variable frequency speed regulation, and intelligent control technology have been applied to AC speed regulation, and their performance is close to the DC speed control system. At present, the use of power electronic devices such as thyristors as power components, single-chip microcomputer or microcomputer as the control system of the speed control system has been used in the AC and DC motor speed regulation, and in the speed regulation performance compared with the previous system has a great development of. In the closed mechanical transmission test bench, the AC variable speed motor can basically meet the performance requirements, which is a common choice.
In order to form a closed power flow direction, the transmission mechanism often forms a closed loop by the main test transmission mechanism and the accompanying transmission mechanism and other coupling mechanisms. The total transmission ratio of the system is 1, so that the entire system consumes power equal to all the closed systems. The power consumed by the frictional resistance of the force transmission member is usually about 50% to 70%. Closed systems offer significant energy savings compared to open systems. The sensor is the primary component of the sampling system. It is used to detect the sampling signals required by the computer. These signals are detected by the sensor, amplified, filtered, and shaped by the secondary instrument, and then input into the computer. The computer digitizes these data signals. After that, the analysis software performs signal analysis, draws conclusions, and feeds back to other control systems to implement control of the system.
At least two signals should be detected in the mechanical transmission test rig. One is the magnitude of the torque received by the drive shaft, and the other is the rotational speed of the drive shaft. In addition to this, vibration, temperature, power and other signals are also used for performance or fault testing, which can be detected by the corresponding sensors. The torque is generated by the loader and reflects the magnitude of the transmission load. Because the actual working condition is to be simulated, it is required to control the torque generated by the loader. First, the magnitude of the torque is detected, and the torque signal can be detected by the torque sensor. The speed is also a parameter that must be strictly controlled during the transmission test. It is often used for performance testing and fault detection. It should also be independently adjustable. This signal can be detected by the speed sensor.
Since the signal output from the sensor is very weak and cannot be directly processed by the computer, it is usually necessary to use a secondary meter to amplify and convert the weak signal. Considering the transmission line effect, when the computer input is far away from the test site, the signal of the sensor should be converted into a current signal for transmission, and then input to the computer input and replaced with a voltage signal or other processable signal. Otherwise, the long transmission line will make The voltage signal is attenuated, which affects the accuracy of the data. Many sensors now also process the signal to output a standard voltage and current signal. Such a sensor is also called a transmitter.
The loader is one of the key components of the transmission test rig, which is mainly used to simulate the force of the transmission mechanism under actual working conditions. At present, the loading devices for test benches at home and abroad mainly include mechanical, hydraulic and electrical mechanical types. Among them, mechanical loaders have elastic torsion bars, rocking gear boxes, etc., which are early-use loaders. The elastic torsion bar cannot be loaded during operation. When the load is increased or decreased, it is necessary to stop and disassemble the corresponding coupling, which is time consuming and troublesome. Although the rocking gear box can be loaded during operation, the axis is biased due to the gear box swinging. Move, causing vibration and wear of the coupling.
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