Research On The Numerical Proportional Pressure Regulation Valve For Metal Belt CVT

The most important question which now must be solved of the automobile development is to reduce the automobile energy consumption and waste gas discharges. The metal belt continuously variable transmission is the collection machine, which includes the electricity, the fluid and the control technology. It is a type of ideal transmission for passenger cars. The practice indicated that it is loaded with the metal belt continuously variable automobile, its efficiency, the power and discharges is better than other automatic transmissions and the manual mechanical transmission. Therefore it is developing rapidly for its specialty. There will be also a great developing potentiality and extensive market in China. Affecting the quality of transmission and the car performances such as fuel economy, dynamic performance and emission directly, its electro-hydraulic control system is the key in continuously variable transmission. The electro-hydraulic control system is a complicated system because it integrates transmission mechanism of continuously variable transmission, electronic control technology and hydraulic transmission technology. Now the research in this field in china is in the starting period. There are many obstacles in both transmission theory and actual control system design. Hydraulic micro-executing agencies depend on import for a long time, plug-mounted electro-hydraulic control valve are limiting the development of our high-tech industry.Compare with other proportional relief valve, the digital proportional relief valve has a simple structure and low cost and can be easily controled. It also has some other advantages such as good dynamic reponse, little energy conservation, don't need A/D convertion, strong anti-pollution performance. Therefore, it will be widely used in the field of production.Clamping force control of continuously variable transmission plays a decisive role on the level of transmission efficiency. If the clamping force is too small, the metal belt pulley on the skid will not only reduce the transmission efficiency, but also to speed up the metal belt and pulley wear and tear; if the clamping force is too large, it will increase unnecessary friction losses and also reduce the efficiency of power train. Under the operating conditions of motor vehichles, only to control the clamping force of the small range of the target in order to effectively improve the efficiency of power train. Digital electro-hydraulic control technology which fills the blank between traditional switch-type hydraulic contorl and servo control has become a fluid transmission and control technology in most of a branch of vitality. Therefore, the research on the numercial proportional pressure regulation valve for metal belt continuously variable transmission and its application are even more valuable.The research on the numerical proportional pressure regulation valve for metal belt continuously variable transmission is for the development of our automobile industry and hydraulic industry with high reliability, compact structure, low cost and excellent performance of hydraulic components. It's important to overcome this difficulty for enhancing self-development capacity and shortening the gap with the developed countries. So this paper makes some study on the electro-hydraulic control system for continuously variable transmission based on digital control technology and its main components. The main work has been completed as follows:1. According on many domestic and overseas references, the development and typical structure and work mechanism of continuously variable transmission are elaborated. The transmission mechanism of metal V-belt correlating closely with clamping control and ratio control is emphases. The technology of electro-hydraulic control is simply explained.2. The numerical proportional technology is an important control technology in the field of vehicle control, it has so many advantages such as high control precision, easy achievement, reliably work and good control results which are to meet the increasingly stringent control requirements. I developed the machine-hydraulic control system of the P811 type continuously variable transmission and achieved the design of the numerical proportional pressure regulation valve for metal v-belt continuously variable transmission.3. Analyzed the mathematical mode of the numerical proportional pressure regulation valve with different dampers and different spring stiffness, got the best structure parameters. From the results of the experiment, we can know the steady-state characteristics and dynamic response are good, it also has some other advantages such as simple control, high precision and reliability which are to meet the requirements of practical application.The main contribution of the research is that a proportional valve with digital control for continuously variable transmission is designed to utilize digital control technology in the electro-hydraulic control system of continuously variable transmission. The test data show that the utility of digital opponents brings great improvement in control precision and reliability for the control system. It's also helpful to reduce design cost of the system. So the electro-hydraulic system using digital control technology can satisfy the demands of cars with continuously variable transmission.