Research On Average Load Valve Test Bench

Average load valve is the core control unit of EMU suspension device, it is used specially to provide an output pressure which is the average of two pilot pressures from the air bellows of the air suspension device,and feedback to empty and load adjustment valve. The empty and load adjustment valve provides a pneumatic signal according to car weight and this signal enters the pilot chamber of the relay valve that drives the brake cylinders. Thus, the reliability and quality of the average load valve will not only affect the reliability of the train brake system, but also impact the railway transportation safety. In order to ensure the driving safety, the average load valve must be performed test for performance, which is need general overhaul or before loading.The test for average load valve needs special equipment, so we need to study for a set of test system for the average load valve testing, namely average load valve test bench, for which the whole control system or driving safety is of great significance.The object of this research is the average load valve test bench, and the test object is the average load valve used in the brake control system for metro Shanghai lines 6 & 8. Firstly, it is introduced of EPAC_LITE (pneumatic scheme) configuration for metro Shanghai line 6 & 8, analyzed of the control mode of the valve and introduced the structure and principle of the average load valve in detail. Then according to the principle and structure of the average load valve, I make a plan for the overall scheme and specification of the test bench. I design test items of average load valve, including tightness test, pressure test, mobility test and flow test, and the parameters of these projects are given.Secondly, according to the test project of the average valve, the pneumatic system of the average load valve is researched and designed.The pneumatic system mainly includes the gas path of each chamber’s tightness test and the function test for average load valve. The principles and functions of the components used in the pneumatic system are analyzed in detail, and complete the selection of related devices, such as filter, pressure regulating valve, relay valve, angle seat valve and solenoid valve. After the completion of the pneumatic system, the test specification for the test procedure of the valve is designed.Then, the hardware system of the average load valve test bench is studied. The hardware system includes the electrical system and the sensing test system. According to the test sensing object for test bench, namely the pressure of gas, a set of sensor testing device is designed. The device comprises a pressure sensor, a terminal plate, a data acquisition card and a computer. Then, in order to better design the electrical system, the pressure sensor, digital display, terminal card and data acquisition card are selected, and their connection mode and performance parameters are understood. After the completion of the selection, the electrical system is studied and designed, and the power supply circuit of the test bench, the power circuit of the gas circuit and the route of the sensing system’s electrical conduction are designed. After the completion of the hardware system, according to the size of the selected components, a reasonable design of the operating panel and the mechanical structure for the test bench.Finally, the software system of the test bench is studied. Based on the visual operating interface of the Basic Visual 6.0 software, the test procedure for the average valve is designed. The whole test bench can achieve the various tests for average load valve, dynamic display of the test results, print test reports, etc.