Research on Transmission Characteristics of Hydromechanical Continuously Variable Transmission of Tractor

Wang, Junyan; Xia, Changgao; Fan, Xin; Cai, Junyu

doi:10.1155/2020/6978329

Cited by 10 publications

(7 citation statements)

References 9 publications

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“…A closed stepless speed change system is mainly composed of a variable displacement axial piston pump and a fixed displacement axial piston motor, and the efficiency of the system is largely decided by speed, pressure, displacement, and so on [24]. In this paper, we carry out tests using the design schemes of the hydrostatic system test bench and power transmission device test bench [25][26][27]. The efficiency formulas for the pump and motor are obtained according to the test data, which are shown as follows [28][29][30]: Hydrostatic system efficiency can be determined according to the fitting equations:…”

Section: Efficiency Characteristic Analysis Using Empirical Formulasmentioning

confidence: 99%

Optimization Analysis on the Transmission Characteristics of Multipurpose Power Transmission Devices

Zhu,

Zhang,

Chen

et al. 2023

Energies

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Particularly crucial throughout the mode transition procedure is the transmission properties of hydro–mechanical composite transmission devices. This paper describes a multipurpose power transmission device that integrates hydrostatic, hydro-mechanical, and mechanical transmission and mainly discusses the transmission characteristic optimization problem from the perspective of speed regulation characteristics, shift strategy, and efficiency characteristics. The kinematic and dynamic analysis of the transmission system, the assembly scheme, and relevant parameters of the power transmission device are analyzed, and the speed regulation characteristic curve is obtained. The shift strategy of power transmission devices involving clutches and brakes during the whole speed regulation process and the best switch time of each component are found. The efficiency expression of the static pressure system is obtained from the efficiency model of the pump-control-motor system, and the efficiency of the multi-purpose power transmission device is obtained using the efficiency definition method. The fitting curves of hydrostatic system efficiency are determined using experimental data, and the efficiency of the hydro–mechanical composite power transmission system is obtained using the conversion mechanism method. The results show that the shift quality of power transmission devices can be improved greatly by controlling the switch sequence of clutches and brakes reasonably.

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Section: Efficiency Characteristic Analysis Using Empirical Formulasmentioning

confidence: 99%

Optimization Analysis on the Transmission Characteristics of Multipurpose Power Transmission Devices

Zhu,

Zhang,

Chen

et al. 2023

Energies

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show abstract

“…The calculation accuracy can also be improved by modifying the model through experiments. For instance, Wang et al [18] established an HMCVT physical model with Simulation X software, improved the model accuracy through calibration tests, and obtained the relationship between engine speed, load, speed ratio, and transmission efficiency, providing a reference for HMCVT optimization design. Zhu et al [19] established a simulation model for pump-motor efficiency based on Matlab/simulink, analyzed the influence of speed, oil pressure, and displacement ratio on efficiency, and verified it through a test bench, which provided a basis for HMCVT control strategies.…”

Section: Introductionmentioning

confidence: 99%

Research on Transmission Efficiency Prediction of Heavy-Duty Tractors HMCVT Based on VMD and PSO–BP

Lu,

Liang,

Liu

et al. 2024

Agriculture

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Transmission efficiency is a key characteristic of Hydro-mechanical Continuously Variable Transmission (HMCVT), which is related to the performance of heavy-duty tractors. Predicting the HMCVT transmission efficiency is beneficial for the real-time adjustment of transmission ratio during heavy-duty tractor operations, so as to obtain better performance. Aiming at the problems of accurate method, low accuracy, and high noise in the prediction of HMCVT transmission efficiency, this paper proposes a method based on Variational Mode Decomposition (VMD), Particle Swarm Optimization (PSO), and Back Propagation (BP) neural networks to improve the quality of transmission efficiency prediction. Firstly, a simple theoretical model was established to obtain the influencing factors of transmission efficiency. Then, based on these factors, the transmission efficiency was tested on the bench under multiple conditions and the influence degree of each factor on transmission efficiency was divided using Partial Least Squares (PLS) method. Finally, the VMD method was used to denoise the test data, and a BP model, which was improved using the PSO method, was established to predict the processed data. The results showed that transmission efficiency of HMCVT is most affected by output speed, followed by power, and least by input speed. The VMD method can accurately extract effective signals and noise signals from the original data, and reconstruct signals, reducing the noise proportion. Using three conditions, the prediction regression accuracy of the PSO–BP model is 7.02%, 7.88%, and 9.26% higher than that of the BP model, respectively. In the three prediction experiments, the maximum differences in the MAE, the MAPE, and the RMSE of the PSO–BP model are 0.002, 0.463%, and 0.004, respectively, which are 0.006, 0.796%, and 0.003 lower than those of the BP model.

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“…Afterwards, transmission manufacturers began to introduce various concepts of tractor CVTs [8,9], such as the Eccom produced by ZF and the Autopowr produced by John Deere. The above-mentioned transmissions all adopt multi-range technology to achieve continuous speed adjustment [10][11][12], so it is necessary to conduct research to improve the quality of the shift [13][14][15], including changing the gear ratio, the clutch engagement time, and the displacement ratio of the swash plate axial piston units. For tractors with heavy load operations such as plowing as their main operating conditions, while paying attention to their riding comfort we also need to consider issues such as power interruption and clutch damage, all of which are important criteria for evaluating the shifting quality.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Shifting Quality for Hydrostatic Power-Split Transmission with Single Standard Planetary Gear Set

Xu,

Wang,

Yang

et al. 2023

Agriculture

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To improve the driving comfort of continuously variable transmission (CVT) tractors, the shifting quality of hydrostatic power-split transmission with a standard planetary gear set was optimized. Firstly, the powertrain of the CVT and two shift strategies, direct-shift and bridge-shift, were introduced; then, a dynamic model of tractor shifting was constructed, and the models of key components such as wet clutches and proportional pressure valves were experimentally verified. Finally, the control parameters of the above two shifting strategies were optimized, and the acceleration impact and sliding energy loss caused by them were compared. The results showed the following: the minimum peak acceleration of the bridge-shift method was 0.385807 m/s2; the energy consumption of the bridge-shift method was significantly lower than that of the direct-shift method; the sliding friction work of clutches decreased by 14.92% and 75.84%, respectively, while their power loss decreased by 22.82% and 74.48%, respectively.

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Research on Transmission Characteristics of Hydromechanical Continuously Variable Transmission of Tractor

Cited by 10 publications

References 9 publications

Optimization Analysis on the Transmission Characteristics of Multipurpose Power Transmission Devices

Optimization Analysis on the Transmission Characteristics of Multipurpose Power Transmission Devices

Research on Transmission Efficiency Prediction of Heavy-Duty Tractors HMCVT Based on VMD and PSO–BP

Optimization of Shifting Quality for Hydrostatic Power-Split Transmission with Single Standard Planetary Gear Set

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