The Research On Key Technology Of Non-declutch AMT For Heavy Commercial Vehicle

Automated Mechanical Transmission (AMT) was developed on the basis of technical improvements on general Manual Transmission (MT) . Electronic control technology and automatic transmission technology was applied to the structure of dry clutch and fixed-shaft MT, and by transmission control unit (TCU), control with mechanical and electronic integration on clutch, transmission and engine was applied, and auto-shift process was realized. By comparison by other forms of automatic transmission, it not only has advantage of auto-shift, but also has high efficiency, simple structure, compaction, low cost and easy to manufacture, good product inheritance. Especially for heavy commercial vehicle market, AMT is particularly the most suited to our national conditions and thus increasingly subject to the domestic industry and related manufacturers attention and favor a bright future.Combined with the special issue"Automated Mechanical Transmission Development for Heavy Vehicle (2000N ? M)"project, which was belong to"advanced technology vehicle development"subject in the field of"modern transportation technology", "Eleventh Five-Year" National High Technology Research and Development Program ("863"Program) of Ministry of Science, on the summary of researches of domestic and foreign achievements, this paper carried out the basic theory and control technology research on non-declutch AMT for heavy commercial vehicle, especially some key techniques, such as shift decision, control strategy, electric power shift system, engine coordinated control and electronic control unit, and so on. It included six aspects :(1) Program design of non-declutch AMT technologyBy reviewing the historical stage of development of independent and integrated control, and analyzing domestic and abroad heavy commercial vehicle AMT technology products status, the paper took electronic control engine and 12 gears non-synchronous dual intermediate shaft of mechanical transmission as study object, proposed a design scheme of non-declutch, and discussed the working principle and functional components, then determine the research content which provided the premise for smooth development and successful implementation of this project. (2) Shift decision-making systemBy dynamic analysis and theoretical discussion aiming at automotive performance shift decision-making, this paper proposed combined multi-parameter shift decision-making concept and system, and then through simulation method combined multi-parameter shift decision-making system was built, related control algorithm was designed, which provided theoretical foundation for heavy commercial vehicle AMT research.The key technology firstly through researching on power and economy performance and shift decision-making for dynamic analysis and theoretical study, analyzed and compared performance characteristics of single parameter, two parameters, and multi-parameter shift decision-making and proposed combined multi-parameter shift decision-making concept.Then the paper analyzed characteristics of the main control parameters for heavy commercial vehicle shift decision-making and the impact on vehicle performance, and designed shift decision-making system based on the throttle and velocity, velocity and power, which built a combination of multi-parameter shift decision-making system.Using the model of established multi-parameter shift decision-making and vehicle dynamics model, the paper carried out simulation analysis on combined shift decision-making system based on the throttle and velocity, velocity and power, and determined the control algorithms of shift decision-making system through the results of simulation of power and economic performance.(3) Motor-based electric power shift systemMotor-based shift system was proposed for non-declutch AMT, and through study on structure and control technology, the paper developed motor-based shift system and motor control strategy, determined the control parameters, completed the design of motor servo controller, which provided the application basis for heavy commercial vehicles AMT.The key technology study firstly compared and analyzed performance of three kinds of electric shift systems which are electronic control pneumatic power, electronic control hydraulic power and electronic control electric power, then decided took electronic control electric power for non-declutch AMT, i.e. selected the form of motor-based electric shift system.Then according to the structural characteristics of prototype mechanical transmission of combination of 12-speed primary gearbox and 6-speed vice gearbox, this paper proposed that primary gearbox combined with motor and vice gearbox combined with solenoid valve, and completed the mechanism selection and structure design for shift operating mechanism.And then according to the working characteristics of non-declutch, the paper proposed functional requirements of motor control, and made the control strategy of current loop, position loop and speed loop servo motor control system, determine the control parameters of motor servo control system and completed the three closed-loop servo control system motor controller design.(4) Engine Regulation ResearchThe paper proposed the engine coordinated method based on based on CAN bus communication technology and engine speed reduction device, and by analyzing the process characteristics of drop gear shifting, shifting and throttle back stage and made the engine control strategy, which laid the technical foundation for control optimization of non-declutch AMT.The key technology firstly discussed the necessity of engine coordinated control of non-declutch AMT, and reviewed the engine control methods, proposed engine coordinated method based on CAN bus communication technology and engine speed reduction device.Then communication protocol based on the CAN SAEJ1939 standards were discussed and analyzed the SAEJ1939 protocol message frame and message transmission mode, then PGN parameters numbers group and parameters meaning which is closely related to engine regulation were given.Then compared several commonly used methods of engine deceleration, a method of electromagnetic brake as the engine speed reduction device was proposed, and completed the structure selection of the electromagnetic brake and matching with transmission, according to simulation analyzed the control performance of electromagnetic brake.Finally, through the dynamic analysis of drop shifting, shifting and throttle back stage, formulated the corresponding control strategies.(5) Study on Electronic Control UnitThe paper proposed the functional requirements of non-declutch AMT, and according to which, carried out the research on transmission electronic control unit (TCU) , based on structured and modular ideas, designed software and hardware of electronic control unit, and completed development of functional sample.The key technology firstly proposed functional requirements of non-declutch AMT combined with the characteristics of heavy commercial vehicle.Then according to functional requirements, the paper identified the ECU design program. ECU for the system is constructed by the CPU, power supply circuit, input interface circuit, driver circuit and communication circuits and other components. CPU system used XC164CM MCU, 8MHz crystal clock circuit, and using special chips TLE7469 to achieve reset; power supply circuit converted 12V input power to different value that electronic control unit needed to meet different need of electronic control units and peripherals; Input interface circuit included speed signal shaping circuit and switching signal shaping circuit, the input signal is converted to electrical signals can be received CPU system; drive circuit used to control FET IRF1310 current amplification and voltage signal amplification to drive motor; communication circuit with the CAN bus communication and RS232 serial communication in two ways to achieve electronic control units and other electronic equipment, data exchange and information sharingDuring ECU hardware design, the design of electronic control unit software was also completed. Its software included initialization module, real-time task management module, data acquisition module, data analysis and logical judgment module, fuzzy PI control module, drive module, communication module and fault diagnosis and analysis module, which is to realize control strategy and control algorithm, generate the required control signals, and make system fault diagnosis and analysis(6) Test studyCombination of the basic performance bench test, debugging and test of electronic control unit and the AMT system were carried out, and non-declutch AMT system equipped with a heavy commercial vehicle road test was carried out.To study the basic characteristics of transmission and electromagnetic brakes and control effect of electronic control unit, complete control parameter correction and debugging of electronic control unit, the key technology carried out test bench to test the engine idle speed performance, electromagnetic brake performance, engine deceleration performance and process of up and down shifting .Basic performance tests results showed that the AMT system developed had good basic performance, the control performance had met the design requirements, and realized the control objectives, particularly in: motor-based electric shift system can reverse gear, choose gear, shift in accordance with control strategy and prompt action, accurate location; engine coordinated control had good effect based on the communication protocol CAN-based launch and engine speed reduction device electromagnetic brake, in the no-load state minimum rise speed time of 400r/min difference adjustment was 0.5s, minimum falling speed time was reduced from 0.8~1.4s (engine natural deceleration) to 0.6s~0.9s (electromagnetic brake assisting deceleration).Basic performance tests also showed that: ECU hardware circuit can effectively process the input signal, ensure electric shift system drive normally, the software modules were reliable, calculation was accurate, communications was normal, the control algorithm can complete the operation, generate appropriate control signals, and to control the implementation of system to produce movement, finally achieved the non-declutch automatic transmission.The paper also carried out power and economy performance road test on a heavy commercial vehicle which was equipped with non-declutch, including: 2 to 5 speed start-up and 0~70km/h acceleration test, 2 to 4 speed start-up and 0~400m acceleration performance test, and 2 to 4 speed start-up 0~400m fuel consumption test. Test results showed that traction performance increased more than 5% , the economy performance had over 6% improvement, which achieve the expected specifications of this article. Under road test, shift process test was carried out, and the analysis of the process showed that the average shift time was 1.5s, up shift time was(the engine deceleration control) is about 1.24s, a down shift time (engine speed rise control) is about 1.44s.This paper study on theory and application technology i.e. combined multi-parameter shift decision-making system, electrical shift and engine coordinated control of non-declutch AMT, broke through technical barriers of foreign countries, mastering heavy commercial vehicle of AMT system's core technology, resolve hardware and software product development of key issues, ensuring the basis of the shifting smoothness and improved the power and economy performance, the domestic similar function to the advanced level of AMT product and approached the technical level, and not only apply to heavy commercial vehicle AMT system, but also be applied to transmission system of buses and passenger cars, which has important significance and reference value in our own AMT technology development and industrialization promotion.