Optimization of the transmission characteristics of an HMCVT for a high-powered tractor based on an improved NSGA-II algorithm

Li, Jiang; Zhai, Zhiqiang; Song, Zhansheng; Fu, Shenghui; Zhu, Zhen; Mao, Enrong

doi:10.1177/09544070211067961

Cited by 4 publications

(2 citation statements)

References 28 publications

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“…At present, there is increased interest in research on agricultural tractor wet clutches. Cheng et al [17,18], Sun et al [19], and Li et al [20] have conducted corresponding design, parameter matching, and performance analyses of a tractor with hydraulic mechanical continuously variable transmission (HMCVT) and wet clutches. Current research on wet clutches has focused on improving clutch performance, specifically, mainly including a wet clutch working quality analysis and control strategy formulation.…”

Section: Introductionmentioning

confidence: 99%

Research on Wet Clutch Switching Quality in the Shifting Stage of an Agricultural Tractor Transmission System

2022

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In order to improve the working quality of wet clutch switching in an agricultural tractor, in this paper, we took a power shift system composed of multiple wet clutches as the research object for full-factorial performance measurement, multi-factor analysis of the degree of influence, establishment of a single evaluation index model, formation of a comprehensive evaluation index, and formulation of adjustable factor control strategies. We studied the simulation test platform of an agricultural tractor power transmission system based on the SimulationX software and obtained 225 sets of sample data under a full-use condition. Partial least squares and range analysis were applied to comprehensively analyze the influence of multiple factors on the working quality of wet clutches. In this paper, we proposed a modeling method for a single evaluation index of the wet clutch (combined with polynomial regression and tentative method, the goal is determined in the form of a model with the maximum coefficient of determination) and two control strategy optimization methods for the wet clutch adjustable factors, i.e., Method 1 (integrated optimization) and Method 2 (step-by-step optimization), both methods were based on an improved genetic algorithm. The results showed that oil pressure, flow rate, and load had significant effects on the dynamic load characteristics (the degrees were 0.38, −0.44, and −0.63, respectively, with a negative sign representing an inverse correlation); rate of flow and load had significant effects on speed drop characteristics (the degrees were −0.56 and 0.73, respectively). A multivariate first-order linear model accurately described the dynamic load characteristics (R2 = 0.9371). The accuracy of the dynamic load characteristic model was improved by 5.5037% after adding the second-order term and interaction term of oil pressure. The polynomial model containing the first-order oil pressure, first-order flow rate, second-order flow rate, and interaction terms could explain the speed drop characteristics, with an R2 of 0.9927. If agricultural tractors operate under medium and large loads, the oil pressure and flow rate in their definitional domains should be small and large values, respectively; if operating under small loads, both oil pressure and flow rate should be high. When the wet clutch dynamic load and speed drop characteristics were improved, the sliding friction energy loss also decreased synchronously (the reduction could reach 70.19%).

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Section: Introductionmentioning

confidence: 99%

Research on Wet Clutch Switching Quality in the Shifting Stage of an Agricultural Tractor Transmission System

2022

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“…Scholars such as İNCE E from Tob University of Economics and Technology in Turkey and Rossetti and Antonio from the University of Padua in Italy conducted an analysis based on engine fuel consumption and discussed the advantages of tractors and city buses equipped with HMCVT devices under various working conditions. performance [8] . L. Viktor Larsson of Linköping University in Sweden and others analyzed the dynamic response performance and power distribution rules of the mechanical-hydraulic composite transmission system, and proposed a static decoupling multi-input to multi-output control strategy, which alleviated the cross-coupling phenomenon existing in the transmission mode switching process.…”

mentioning

confidence: 99%

Optimizing the mode switching quality of hybrid tractors equipped with mechanical-hydraulic compound transmission devices

Zhu,

Sheng,

Zhang

et al. 2024

Preprint

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During the mode switching process of a hybrid tractor equipped with a mechanical-hydraulic compound transmission (HMCVT) device, the separation and combination of the clutch will cause transient shocks, affecting the smoothness and driving comfort of the entire vehicle. This article establishes a system dynamics model in SimulationX simulation software and builds a hardware-in-the-loop (HIL) test platform for testing to study the simulation and testing when switching from pure electric drive mode to hybrid speed coupling mode. In order to solve the problem of slow dynamic response of the engine, this study proposes a control strategy of "clutch oil pressure fuzzy control + motor torque compensation” and uses the orthogonal test range analysis method and variance analysis method to optimize the vehicle mode switching quality. Taking the switching timing of the six clutches C0, C2, C3, C4, C6 and C7 involved in this article as the factors A, B, C, D, E and F of the orthogonal test range analysis, the clutch switches 0.5s ahead of time. On-time switching and delayed switching of 0.5s are used as three levels. L27(36) orthogonal table is selected for simulation test. Range method analysis shows that scheme A3B1C3D3E1F2 is the optimal switching scheme, that is, clutches C2 and C6 switch 0.5s in advance, and clutch C7 is on time. Switching, clutches C0, C3 and C4 are switched with a delay of 0.5s, the output shaft speed drop is reduced from 21.875% to 1.63%, the dynamic load coefficient is reduced from 8.473 to 2.72, and the impact degree is reduced from 26.181m/s3 to 7.08m/ s3, the switching time is reduced from 1.345s to 0.35s. A hardware-in-the-loop test platform was built for testing. The hardware-in-the-loop (HIL) test results were consistent with the overall trend of the simulation results, verifying the effectiveness of the proposed control strategy and method.

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Designing Comprehensive Shifting Control Strategy of Hydro-Mechanical Continuously Variable Transmission

Dong²,

Han

et al. 2022

Applied Sciences

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The shift quality is one of the most important criteria for evaluating the operation and transportation of a hydro-mechanical continuously variable transmission (HMCVT) tractor. In this study, a comprehensive shifting control strategy of a hydro-mechanical continuously variable transmission in a high horsepower tractor is investigated for enhancing shift quality. The detailed mathematical model of the transmission assembly components, such as the pump-motor system, the clutch system and the equivalent gear shaft system of the hydro-mechanical continuously variable transmission, are established to analyze the exact shifting process. For different transmission systems, two different control methods are proposed to achieve precise control of the transmission. The double-loop control (PID-Model Predictive Control) is used for the pump-motor hydraulic system, which not only ensures the anti-interference of the control signal when the displacement is a fixed value but also improves the response characteristics and stability of the control output when the displacement ratio is variable. The PID control is used for oil pressure control of the clutch system, and experimental results reveal that a simple method can obtain better control performance. Finally, a comprehensive control strategy in the process of shifting is proposed, and the optimal control strategy is obtained by comprehensively adjusting the pump-motor hydraulic system and the clutch system at the shifting point. The results show that the shift acceleration under the optimal control strategy is 64.4% lower than that without control. The proposed control strategy can effectively reduce shift shock and Improve shift smoothness.

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Optimization of the transmission characteristics of an HMCVT for a high-powered tractor based on an improved NSGA-II algorithm

Cited by 4 publications

References 28 publications

Research on Wet Clutch Switching Quality in the Shifting Stage of an Agricultural Tractor Transmission System

Research on Wet Clutch Switching Quality in the Shifting Stage of an Agricultural Tractor Transmission System

Optimizing the mode switching quality of hybrid tractors equipped with mechanical-hydraulic compound transmission devices

Designing Comprehensive Shifting Control Strategy of Hydro-Mechanical Continuously Variable Transmission

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