Integrated Control of Hydromechanical Variable Transmissions

Abstract

A hydromechanical variable transmission (HMT) has advantages of continuous variation and high efficiency. So it is one of the ideal transmissions of heavy vehicles. The continuous speed varying process involves speed governing in range and range shift. Integrated control strategy of the HMT is proposed in this paper. The algorithm of the asymmetric saturated incremental proportional integral derivative (PID) speed control strategy in range and range shift conditions are derived. And this paper presents the range shift logic and range shift control strategies. A controller model is built in Matlab Simulink and cosimulated with the model of vehicle equipped with a two-range HMT. The HMT prototype hardware-in-the-loop simulation (HILS) platform of the integrated control strategy is built. The HILS results show that the range shift process is smooth and speed fluctuation does not happen. In the throttle stable stage, the engine speed is adjusted to the near optimal speed, and its change rules are in accordance with simulation results. The integrated control strategy is reasonable.

Development of a new sub-shift schedule and control algorithm for a hydro-mechanical transmission

“…[3][4][5][6] Otherwise, the shift shock occurs due to the speed difference between the on-coming and the off-going clutch. In a conventional automotive transmission, the shift point is determined by considering the system efficiency with respect to the vehicle speed and acceleration pedal position.…”

“…For the control of the HMT with multi-speed subshift gears, various studies have been performed including the shift logic and tractor velocity control for the HMT with two-speed sub-shift gears, 3 control architecture of the HMT using proportional-integral (PI) control and current compensation, 4 sub-shift schedule to obtain the maximum driving capacity and to prevent the shift circulation due to the frequent shift, 5 and HSU control for the sub-shift of the HMT with dog clutch. 6 For smooth sub-shift, control strategy of the HMT was investigated based on the orthogonal test.…”

Analysis and experiment of HMT stationary shift control considering the effect of oil bulk modulus

“…2 In order to improve the power and economy of vehicles equipped with HMT, scholars have done a lot of research on the influencing factors, control strategies, and layout structure. [3][4][5][6][7][8][9][10][11][12][13][14] However, the poor dynamic quality of the HMT during the shifting between different ranges affects its wide application in heavy vehicles. Thus, Ni et al, 3 Zhu et al, 4 and Hu et al 5 analyzed the order of the effects of different physical parameters of the transmission on the shift quality by experiments.…”

“…Wang and Wang 8 and other researchers found that the change in the function of hydraulic components during the shift affects the stability of the fixed displacement motor speed as well as the shift quality. To solve the above problems, Zhang, 9 Yang et al, 10 and Yin 11 respectively proposed control strategies for the shifting timing and the shifting time of multiple sets of brakes, and the rationality of the strategies was verified by experiments. Irfan et al, 12 Sung et al, 13 and Zhang et al, 14 respectively, used GT-Suite model, network analysis, and genetic algorithm to optimize the structure of HMT, improving the transmitting efficiency of the system and reducing the fuel consumption.…”

Conceptual Design of Complex Hydromechanical Transmissions

“…Also, the user is allowed to customize and create models with self-developed user code to a greater extent. Examples of studies using popular commercial softwares for detailed simulation of HMTs are for instance [76,77,78].…”