Research On The Key Technology Of Heavy Forklift Truck Automatic Shift

According to WAN Zheng (2009) No.108document on the accelerating the implementationof major scientific and technological projects, the heavy truck automatic transmission was studiedin this paper, at the same time, the paper research work also obtained the financial support ofNational Natural Science Foundation Program of China (No.51205101) that was the integratedcontrol study on the lateral stability of balance forklift chassis system and the Twelfth Five-yearscience and technology Program of Anhui Province (No.12010202032) that was the automatictransmission control system of engineering machinery. The implementation of the project wouldimprove the level of the core components of the domestic forklift and fill the domestic blank inthis field. According to the working characteristics of the forklift truck automatic transmission,much fundamental work was carried out in improving shifting economy, in the study of improvingtorque converter efficiency that play large role of transmission performance especially. At thesame time, the shifting tactics and smoothness, and special working conditions such as the lowadhesion road, ramp and etc. were researched, simulated and tested, the main research contentsand conclusions are as follows:(1) DOE methods was used to study relevant parameters sensitivity of torque converterblades. Based on generalized torus coordinate system of liquid flow, the shape parameters of bladewere calculated and analyzed, the mathematical expression of the blade baseline was put forward,At the same time, the original characteristic expression of new torque converter was furtherdeduced, the converter performance optimization was completed, its efficiency had been improvedand verified by bench test, this method offers a new choice for torque converter research.(2) According to the particularity of forklift work places and conditions, this paper proposeda method of layered hierarchical coordinated control strategy on the intention of a driver, vehicleand road environment, the method can make the analysis, decision-making, control under differentoperating conditions, and optimize the shifting adaptability of the forklift at bad place, and getsatisfactory shifting effect, this will provide a theoretical reference to in-depth study of intelligentcontrol strategy for the truck automatic transmission.(3) The ramp shift is typical operating in forklift driving, the shifting parameters were testedand parameters influence was analyzed to ramp performance in this paper. The ramp statusparameters could been recognized by the error theory of simulating human intelligent control, theautomatic shifting database was established by fuzzy control theory, and ramp automatic shifting test was finished under different loading, the method effectively solved the engine flameout, rampsliding and longer clutch friction time.(4) Forklift starting shift have very important influence on operating performance, byanalyzing the wet clutch movement processes of separation and combination, the clutch shiftingdynamic model was created，its equilibrium equation and the relationship between clutch torqueand binding force were obtained. The hydraulic control system of the transmission was redesignedand the test results indicated that a new control system had better smoothness than the original, aset of forklift starting shift evaluation method was proposed finally.(5) The forklift vehicle transmission system dynamic model was created and then simulatedon MATLAB/simulink，at the same time, the hardware and software of automatic transmissioncontrol unit（TCU）were designed on the ARM7development platform, TCU reliability tests forelectromagnetic compatibility, earthquake-resistant, waterproof and etc. were finished accordingto national standard, then, bench and vehicle tests showed that higher shifting reliability and bettershifting smoothness had met design requirements.Through the study and design of heavy-duty truck automatic transmission, our enterpriseobtained the breakthrough in the key technology, it broke the foreign technology barriers, reducedthe cost, but also improved product performance and increased the core competitiveness.