Alternating Pressure Test Bench Control System Research And Design

Alternating pressure test is a very important testing method to evoluate product fatigue limit for a lot of auto parts and components, especially for automotive air conditioning systems, compressor, condenser, evaporator, and a variety of piping and other accessories. Alternating pressure test is to simulate the actual working condition of these parts, such as simulated actual use conditions of pressure changes of the circulating medium, the temperature of the circulating medium, the ambient temperature, etc.Alternating pressure test function is relatively simple and generally only simulate simple fixed waveform, and therefore can not accurately determine the sample pieces of limit life. With the rapid development of the automotive industry and the increasingly fierce competition, domestic and foreign automobile mainframe manufacturers alternating pressure test more stringent requirements not only need to simulate actual operating conditions the pressure waveform changes, such as sine, triangle, trapezoidal wave or arbitrary waveform, you also need the analog waveform parameters such as frequency, amplitude, In addition, the temperature of the test environment, the temperature of the circulating medium are also strict requirements.The development and application of computer control system, just in time for alternating pressure test function is diverse, complex new requirements. Powerful data processing capability of computer control system to facilitate the implementation of complex control algorithms of the pressure waveform; the use of the interactive features of the computer control system can be easily adjusted for a variety of test parameters; use of the computer control system for a high degree of flexibility, can easily be expanded to a variety of functions. In addition, due to the use of computer control system, the accuracy of the test bed will be further improved.Combined with computer control system for alternating pressure test the new requirements made an in-depth analysis of the works of the alternating pressure test bench.Alternating pressure test bench is a set of mechanical, electrical, hydraulic various technologies into one device, its core actuator is a hydraulic servo valve, and therefore its study the characteristics of great significance. Earlier in this chapter focuses on alternating pressure test rig works and system structure, composition, and working principle of servo valve was introduced byThe focus of this study is the alternating pressure test stand control system. Alternating pressure control system of units is a typical computer control system, divided into two parts of the upper and lower machine.The host computer provide the man-machine interface which is mainly used for the display of test data and for the input of test parameters sets, and real-time communications with lower machine and data interaction.The lower machine is a typical microcomputer measurement and control system with a total of56digital input interface and16digital output interface also includes8-channel analog input interface and4-channel analog output interface. Through these interface circuit, the microcontroller can collect the physical signals of pressure, temperature, and piston position to precise the control of these physical parameters by PID algorithm.