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Research on the Opening and Closing Characteristics of Fuel Pump Valve and On - line Detection Technology
In the direction of the fuel pump system control valve, safety relief valve is to prevent excessive oil pressure in the pipeline, and the one-way valve is the role of the fuel pump to stop working, the fuel pipeline to maintain a certain hydraulic pressure , So that when the engine starts again in time to fuel and easy to start. In order to improve the reliability of products, to ensure the normal operation of equipment, the valve must be correctly detected whether the failure. For a long time, the valve opening and closing characteristics of the test has been used in the sixties and seventies of the traditional methods - the use of oil testing, and in the testing process is based on manual operation. The traditional method of simulating the fuel pump work, the need to fill the oil pipelines, and then through a few days time to observe the supply of non-return valve leakage. The structure of this inspection system is complex and difficult to meet the requirements of production automation. And its low detection accuracy, manual workload, low test efficiency, and product testing is completed, it is difficult to completely restore the clean. With the rapid development of computer technology, the application of computer technology to hydraulic testing technology has shown the advantages of high testing accuracy, fast testing speed and greatly reduced manual workload. Not long ago, I designed a special set of fuel pump valve opening and closing characteristics of online testing system, the use of gas detection instead of oil, not only solved the existing problems, but also can correctly grasp the valve performance and status. First, the fuel pump valve operating characteristics In any operating conditions, the fuel pump supply system must provide the required amount of fuel to the engine. Fuel pump will continue to suck the fuel from the tank, after the fuel filter, fuel distributor, sent to the electromagnetic injector. The fuel injector injects the precise amount of fuel into the intake of the engine. Excess fuel is returned to the tank through the pressure regulator. The check valve of the fuel pump is mainly used to prevent the reverse flow of the fuel and keep the residual pressure of the pipeline so that the engine can be started next time easily and prevent the air resistance phenomenon of the oil road caused by the high temperature and affect the hot start performance of the engine. Therefore, the performance requirements of the one-way valve are mainly: when the flow of oil through the one-way valve, the resistance to be small, that is, the pressure loss is small; and when the reverse flow of oil, the valve port seal is good, ; Work should not be vibration, shock and noise. When the pump output pressure exceeds the rated value, the safety relief valve will automatically open, high-pressure fuel can be returned to the pump into the oil chamber, and pump and motor circulation, which can be avoided due to blockage caused by oil pressure pipeline Excessive cause ruptured pipe or fuel pump damage and other phenomena. Therefore, the main performance requirements of the relief valve are: large pressure range, small deviation pressure regulator, pressure swing small, sensitive action, over-flow capacity, pressure loss and noise small. The valve spring stiffness and pre-compression of a certain amount, the relief valve from opening to the maximum opening, and from the maximum opening to closing the relationship between flow and pressure, known as the relief valve opening and closing characteristics. Its dynamic performance refers to when the system pressure suddenly exceeds the relief valve setting pressure, the valve pressure changes and the stability process. General pressure overshoot, boost time and voltage regulator time to measure. The following Zhejiang Yuhuan Changzheng Auto Parts Factory fuel pump for the object, look at the work of the fuel valve. In the 12V working voltage, its rated flow Q = 1L / min, redress pressure p = 0.45Mpa ~ 0.63Mpa. Based on the test data, the relief valve opening and closing characteristics and the relief valve dynamic characteristics are shown in Fig.1 and Fig.2. Figure 1 relief valve opening and closing characteristics of Figure 2 relief valve dynamic characteristics During the work, the one-way valve that the flow of liquid that is better, in time to enable the flow of oil in the pipeline, and the tightness of the high, if the one-way valve leakage The amount exceeds the required value, there is not enough oil in the pipeline, will directly affect the car's next launch. The amount of relief valve leakage is a comprehensive performance index, which reflects the manufacturer's manufacturing process and assembly level, the size of the relief valve static and dynamic performance have a significant impact. The opening pressure and closing pressure of the relief valve decrease as the amount of internal leakage increases, resulting in poor opening and closing characteristics. Second, the design of the test system workbench 1. Test System Principle The entire test system consists of the end cap (workpiece) with the outlet, five solenoid valves, a negative pressure generator, a sensor and gas-controlled triplex components. As shown in FIG. 3, the solenoid valve 1 controls the check valve at the oil outlet, the solenoid valves 2 and 3 control the positive pressure source, the solenoid valves 4 and 5 control the negative pressure generator, and the sensor always detects the pressure in the cavity of the workpiece. Figure 3 gas circuit schematic diagram of the workpiece is positioned and sealed in the case of good, from the bottom of the workpiece with electric pressure regulator to achieve a given pressure, the safety relief valve open, the pressure, the computer automatically timer Pressure process to determine the relief valve relief. After packing, by the computer-controlled solenoid valve 1 pressure relief, one-way valve open. Followed by the use of vacuum check one-way valve seal, change the traditional method, with gas detection instead of oil. The measured pressure curve of the valve under test in the theory should be as shown in Fig.4. Figure 4 test valve pressure curve 2 test system table mechanical part of the design test system design includes: mechanical fixture table design, gas detection system design and system control circuit design. Here mainly introduces the design of mechanical fixture table. I Taizhou Yuhuan Changzheng Auto Parts Factory fuel pump for the study of the core, on the basis of the valve opening and closing characteristics of online test system. Design a reasonable workbench, there are several key issues that require special attention: (1) the positioning of the workpiece. (2) cylinder selection. Workpiece * cylinder pressure, and then to the workpiece within the positive pressure detection. Therefore, the required pressure on the workpiece is calculated to meet the requirements of the test device. When the cylinder is selected, we can design the bracket that supports the cylinder, determine the geometric dimensions, calculate the strength and calculate the safety, and improve the safety and reliability of the online testing system. (3) design of all aspects of the sealing problem. 3. Intelligent test system Most valve manufacturers are still using the method of artificial oil test, this method is inefficient, large error, and can only be tested on the static properties of dynamic tests are often powerless. Modern industry and science and technology not only require high static performance of components, but also put forward higher and higher requirements on the dynamic characteristics that directly affect product accuracy. Only with high-speed A / D conversion device and high-precision computer test system can the system platform measure the static characteristics of the components with the specified accuracy. Only the computer test system can accurately measure the dynamic performance of the components and analyze and process the components. From which you can get information about the performance of the components and provide a basis for product design. Compared with the manual test methods, the advantages of computer-aided testing is that it has a powerful data processing capabilities, high test accuracy, to ensure real-time measurement, to prevent human error, compensate for sensor nonlinearity, to achieve the entire test process intelligence Control, strict control of test conditions, and improve test efficiency. The test system control diagram is shown in FIG. 5, which comprises a computer, an I / O converter for receiving the digital signal instruction output by the computer and outputting analog signal instructions to the relay module, for receiving the analog signal of the amplifier module and sending the analog signal to a computer An A / D converter for outputting a digital signal, a relay module for receiving an analog signal and outputting a control signal to a cylinder, an amplifier module for receiving an analog signal outputted from the pressure sensor and adjusting a signal for detecting a fuel pump supply stoppage Valve negative pressure sensor, as well as for the control of the gas circuit of the solenoid valve. Figure 5 test system control diagram where the A / D converter, I / O converter is set in the computer interface card, the computer interface card is set in the computer host computer interface card through the computer's ISA interface with the computer; relay module, amplifier The module, the voltage source that supplies the negative pressure sensor, is mounted on a board. After the signal, the pressure sensor through the amplifier module to amplify the analog signal, and then converted by the I / O converter into the digital signal we need through the computer display. We use the computer, through the D / A conversion signal to control the solenoid valve in each gas, fully intelligent detection. Third, the concluding remark Normal work, check the working pressure of the check valve is lower than the rated working pressure of the check valve, the check valve opening pressure to meet the system requirements should be as low as possible to reduce the pressure loss. Relief valve setting pressure shall not exceed the maximum pressure of the hydraulic system, the maximum flow relief valve to be within its rated flow range. Through the test and practical circuit analysis shows that the test system work *, with high test accuracy and speed and strong data processing capabilities.