The Research Of Electrically Controlled System And Control Methods On The Hydraulic Retarder

Recently, with the improvement of road condition and the performance of the vehicle, the load and quantity of commercial vehicle is demanded much more either. The performance of vehicle has been improving, including average velocity and the power of engine, while no perfect breakthrough on the vehicle brake performance all over the world. For the limitation of brake system dimension and cooling system capability, the accumulation of heat produced by brake system is very dangerous to the running vehicle, there may cause big accidents because of the invalidation. The vehicle must be equipped with auxiliary braking system besides the service brake to ensure the well brake performance.As a kind of auxiliary brake system, hydraulic retarder can reduce the load of the service brake, enhance the reliability of the brake system, and extend the service life of the braking system. Hydraulic retarder with long service life, braking power, quality control, suitable for continuous braking, has a wide range of applications. the vehicle hydraulic retarder has been deeply research and extensive application abroad,but theory research and samples development just begin in chinaAccording to the project of the vehicle intelligent hydraulic retarder key technology research and the project of the electronic control hydraulic retarder development, the dissertation mainly focuses on the control system of the hydraulic retarder system.The first part summarizes the working principle and type and merit of all sorts of auxiliary braking devices. The hydraulic retarder has such merits as braking torque, braking stability, noise, long life and small size in structure. Detailed studied the current situation of the hydraulic retarder research and application at home land and abroad. Then put forward to the emphasis of this paper.In the second chapter, it presented the working principle and classification of the hydraulic retarder. It also analyzed the component of the hydraulic retarder. The hydraulic retarder is consisted of the main body, the electronic control devices and operating devices. The main boody of the hydraulic retarder is consisted of the round body, working round, flange, the heat exchanger and the tank. Drive wheels through the transmission shaft and flange connected the round. When the retarder working, the fluid is pumped into the work space by the high pressure air. The work space is consisted by the stator and rotor controlled by the valve. As a result of the liquid impact the stator of the work space and generate the braking torque. The kinetic energy of vehicle is translated into the heat energy of liquid. And then through a certain way of cooling heat energy will be distributed out to the hydraulic retarder. When the retarder is stopping work, the liquid in the space is released into the tank. the retarder will not generate the braking torque. The liquid theory is introduced at first, based on one-dimensional flow theory, braking torque mathematical models of hydraulic retarder is established and the equation between braking torque and rotate speed is deduced, additionally, analyze the liquid flowage quantity in the circler of hydraulic retarder, set up the equation between flow quantity and rotate speed, effects on braking performance from different oil quantity in the circler of hydraulic retarder are discussed either. The loss coefficient selection and calculation were discussed and recommended. It also provided some ideas for the follow retarder research. The main target of the retarder bench test is test the basic performance of retarder. That is the braking torque and the oil pressure of working chamber in different rotate speed and different shift when the hydraulic retarder working. It verified the validity of the hydraulic retarder theoretical by the bench test.The third chapter describes the main electronic control system of the hydraulic retarder electronic control system includes three parts: the hardware system, software system and the fault diagnosis system. Electronic control system is one of the core technologies of the electronically controlled hydraulic retarder system. The hardware and software system will have a direct impact on the performance of the hydraulic retarder. On the basis of the control strategy, we designed electronic control unit of hardware, including microprocessors selected, the power supply circuit designed, the circuit of input and output designed, as well as communications circuit designed. It designed the software control system based on the hardware system. The software introduced the software modular structure of control system and the data processing methods of the control system. The software system also introduced the data acquisition method and the data processing method of the software system. It designed fault diagnostic program according to the hydraulic retarder control system.The unit fault diagnosis unit included the output signal fault diagnosis program, the input signal fault diagnosis program, power circuit failure fault diagnosis and the storage fault code program and so on. The fault diagnosis system will discover. The fault diagnosis systems will discover and classified the failure and preserved the error code when the hydraulic retarder's something is wrong. The control system has the fault tolerance capability. Finally, it introduced the main anti-jamming methods of the control system hardware and software system according to the special working conditions of the automobile electronic system. It is proved by test that the hardware, software and fault diagnosis run stably, the control system of hydraulic retarder can meet the requirements for use.The fourth chapter described the control strategy of the hydraulic retarder. It analyzed and studied the braking dynamic mode of hydraulic retarder, and put forward an intelligent strategy about constant speed control mode and intelligent control model.When the automobile in the long slope, the constant speed control mode used the fuzzy intelligent simulate human control technology. It make the hydraulic retarder braking torque has a small overshoot and a shorter adjustment Time. It also has the better dynamic response and steady state .In the hydraulic retarder foot intelligent control mode, it used the PID parameters of fuzzy self-tuning. The hydraulic retarder of intelligent control mode enables hydraulic retarder produce the braking torque to adapt the driver's intent and the road environment .At last it build a hydraulic brake retarder simulation model by MATLAB/Simulink .The simulation model include the simulation model include hydraulic retarder in the manual mode, which work in a separate stall on a fixed brake and the hydraulic retarder for speed control model when the automobile in the downhill and the intelligent simulation model of the retarder. The simulation test the newly developed hydraulic retarder control system not only meets the requirements of use, but also have the intelligent control which other hydraulic retarder not have.The fifth chapter described the real vehicle test of the hydraulic retarder. There are three targets on the real vehicle test. The first is to test the vehicle speed when the retarder working on fixed shift on the flat road, the second is to test the vehicle speed when the hydraulic retarder working in the constant speed shit to maintain stable speed braking downhill and the last is the hydraulic retarder intelligent control braking test. It is test that control system and control strategy of the hydraulic retarder has been to meet the hydraulic retarder control requirements. It can provide technical support for the hydraulic retarder development int the future.The last chapter summarizes the whole paper. Introduce the main work and research result and the next research direction.Through the hydraulic retarder control system and control strategy studying, It can enhance our self-development capacity of hydraulic retarder and shorten the gap with the foreign countries. It has play important role inthe prosperity and development of China's automobile industry and the promotion of other relevant industry. The industry has played an important role in the prosperity and development and can bring great social and economic benefits. The intelligent foot control model can produce different braking torque base on the intention of driving and road conditions outside world which is the other hydraulic retarder does not have.