Study On Numberical Pressure Control Valve Of Automatic Transmission Based On High-speed Switch Valve

Auto,as the traffic tool of modernization ,has been used in each aspect in life. The vehicle has strong impact on every aspect of human society. It breaks restriction of region, accelerates the flow of materials, and plays a necessary role in the modern society of civilization. At the same time of the fast development of auto , people have also found many questions.The vehicle is facing on more and more requirements ,such as low fuel consumption ,low harmful exhaust emission, high comfort performance. Nowadays more and more manufactures incline to produce automobiles equipped with automatic transmissions.Therefore,the technology of power train is very important .There are several methods to realize automotive transmission shifting. For the moment, Automatic Transmission (AT), Electronically Controlled Automatic Mechanical Transmission (AMT) and Continuously Variable Transmission (CVT) are widely used all round the world. CVT is an ideal transmission device because it can realize the continuous change of transmission ratio, get the optimum matching between the transmission and the engine and improve the whole vehicle's fuel economy, mobility, the handing facility and comfort. Compared with AT and AMT, the efficiency of CVT is higher than that of AT, and the handling facility and comfort of CVT are better than that of AMT. Therefore, automobiles equipped with CVT can meet the requirement of modernization.Metal V-belt type CVT has such merits as bigger power transferring capacity, transmission efficiency and longer life, so it has been the most widely used.Digital controlling technology can meet there quirement of dynamic and static performance of CVT, and has such merits as low cost, strong anti-pollution ability, handling performance, easy automation, simple structure and low energy consumption. On the whole, it is beneficial to research and develop the digital electro-hydraulic controlling module to improve the performance of CVT and reduce its cost.This subject adopts the pulse width digital high-speed switch valve and forms the proportion of digital electric liquid control system. Because the structure of commom servo valve is complicated, and it require the liquid have good purity, price comparatively high, and professional maintenance, bad adaptability to poor vehicle working environment, so there is certain restriction in applying it to engineering vehicles. Digital electro-hydraulic proportion control system has many merits such as excellent repetitiveness, small, cheap, simple structure, good flexibility to pollution, convenient interface with computer, etc., so there are wide application prospects . The high-speed switch valve works on two states: on and off. Ordinary spiral shell pipeline can control it, so the expensive proportion electro-magnet such as the proportion valve can be saved.The control principle of the whole system : the sensor gather the pressure signal and give it to the control module, after computer operation in the control module, produce the PWM signal in need corresponding to the control , export after the power amplification circuit on the automatically controlled module is amplified, drive the high-speed switch to work. When the high-speed switch valve is powered, the controlling hole connects the oil source and the oil enterer the controlled hole, so the controlling pressure is rising. But when the high-speed switch valve is out of power, the controlled hole connect the oil tank, and the oil is flow outwards, the controlled pressure is reducing. When input continuous PWM signals, we can see the average pressure will round a certain invariable value. While when the width of the PWM signal pulse changed, the pressure will be changed too. So we can control pressure by tuning up the width of the PWM signal that drives the high-speed switch valve.Secondly, as High-speed switch valve play an important function in the system, the paper analysis carefully structure and motion course of High-speed switch valve. Then, the paper establishes the static and dynamic model of High-speed switch valve and describes the response characters of it at various phase,According to its characters, we use it in the system.So this paper makes some study on the electro-hydraulic control system for CVT based on digital control technology and its main components. The main work has been completed as follows:1,According on lots of professional documents, the problems the automotive industry confronted, the corresponding solutions, the development and application history and research of CVT nowadays were introduced.and explain that CVT is the important development aspect of auto.2,The structure,principle and the meas of control aim of CVT were introduced.。that establish the foundation of the matching of CVT and engine .3,Introduce the configuration and means of control of high speed on-off valve .Analyse characteristic of control of high speed on-off valve.and design the control and drive circuit . .Analyse several means of creat PWM signal,then design the creat circuit of PWM signal.4,Introduce the configuration and theory of work. The digital valve and its driver were designed, and the math model of the digital valve built and analyzed through computer simulation with MATLAB. Find the rule of parameter which influence the capability of valve .5,Establish the experiment of valve and validate the design and parameter of valve through the date of experiment.The main contribution of the research is that design the proportional valve with digital control for CVT,the drive circuit of high-speed switch valve and the creat circuit of PWM signal. Thereby realize to use the digital control technology in the electro-hydraulic control system of CVT. The test data show that the utility of digital valve brings great improvement in control precision and reliability for the control system and also brings a wide development for CVT.