scholarly journals Research on Transmission Characteristics of Hydromechanical Continuously Variable Transmission of Tractor

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Junyan Wang ◽  
Changgao Xia ◽  
Xin Fan ◽  
Junyu Cai
Keyword(s):  
Power Flow ◽  
Flow Direction ◽  
Transmission Efficiency ◽  
Continuously Variable Transmission ◽  
Simulation Software ◽  
Transmission Scheme ◽  
Compact Structure ◽  
Theoretical Derivation ◽  
Speed Regulation ◽  
Variable Transmission

This paper proposes a new transmission scheme of hydromechanical continuously variable transmission (HMCVT) for tractors. The HMCVT has 4 working ranges in each of the front and rear directions. The speed characteristic and the torque characteristic of HMCVT are theoretically derived. On the basis of HMCVT power flow direction, the Крейнeс formula is used to calculate the transmission efficiency. Then, the image analysis method is used to study the influence of parameters on the transmission efficiency of HMCVT, and the main influencing factors are found. The results of theoretical derivation demonstrate that, by coordinating control of the HST displacement ratio and the engagement conditions of shifting clutches, the stepless speed regulation of HMCVT at the tractor speed of 0–50 km/h can be realized. The proposed HMCVT has the ability to continuously transmit and change torque over all working ranges. The overall transmission efficiency of HMCVT is at a high level. To verify the theoretical derivation, Amesim simulation software is used for the modeling and simulation of HMCVT. The simulation results are consistent with the theoretical analysis results. Therefore, the HMCVT proposed in this paper has the advantages of compact structure and high transmission efficiency, and it is suitable for matching tractors.

Characteristics of the Hydro-Mechanical Continuously Variable Transmission in the Wheeled Tractor

2014 ◽  
Vol 494-495 ◽  
pp. 167-170 ◽  
Author(s):  
Ming Zhu Zhang ◽  
Rui Guo ◽  
Chen Chen
Keyword(s):  
Power Flow ◽  
High Efficiency ◽  
Continuous Variable ◽  
Transmission Efficiency ◽  
Continuously Variable Transmission ◽  
Entire System ◽  
Continuous Variable Transmission ◽  
Variable Transmission

Based on the hydro-mechanical continuous variable transmission (HMCVT) of 400 house-power of Dongfanghong, the synchronization in period of contions to content to multiple period of HMCVT was established by analyzing its transmission principle, and the relation fomulas of power distributing ratio and efficiency was presented. That results showed that the characteristics of power flow at the first half and at the second half were different, when it was within the certain grade to do the boundary of e equaled with zero; while it was each grade in section points, that characters were the same; the more grades, the greater HMCVT system transmitting power and the higher the transmission efficiency of the entire system. The high efficiency features of multiple range hydro-mechanical stepless transmission, meet the requirement of tractor operation.

scholarly journals An Evaluation Method of Mode Switching Quality for Double-Belt Continuously Variable Transmission

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Lanchun Zhang ◽  
Zhongwei Zhu ◽  
Bin Huang ◽  
Tianbo Wang
Keyword(s):  
Evaluation Method ◽  
Evaluation Model ◽  
Subjective Evaluation ◽  
Objective Evaluation ◽  
Transmission Efficiency ◽  
Continuously Variable Transmission ◽  
Mode Switching ◽  
Evaluation Indexes ◽  
Variable Transmission ◽  
Driver’S Intention

In order to improve the transmission efficiency and carrying capacity of conventional single-belt continuously variable transmission (CVT), one new type of dual-belt CVT is proposed in this paper. Under the situation that this new dual-belt CVT should be switched between single- and dual-belt modes frequently according to driver’s intention and road conditions, so five objective evaluation indexes of mode switching quality for the dual-belt CVT are proposed, considering the aspects of vehicle power, comfort, and transmission durability comprehensively. Then, the objective evaluation model of mode switching quality is established by the BP neural network optimized by the genetic algorithm. It is found that the prediction results are consistent with the subjective evaluation. After analyzing the influence of the selected five evaluation indexes on the prediction results, it is obvious that these five evaluation indexes of mode switching quality for dual-belt CVT are reasonable.

Integrated control strategy of tractor hydromechanical continuously variable transmission

2020 ◽  
pp. 095440702095114
Author(s):  
Guang Xia ◽  
Huayu Zong ◽  
Xiwen Tang ◽  
Linfeng Zhao ◽  
Baoqun Sun
Keyword(s):  
Control Strategy ◽  
Integrated Control ◽  
Continuous Variable ◽  
Transmission Efficiency ◽  
Variable Speed ◽  
Speed Regulation ◽  
Continuous Variable Transmission ◽  
Variable Transmission ◽  
Working Resistance ◽  
Transmission Speed

Given the transmission efficiency fluctuation and response lag problem of hydromechanical continuous variable transmission combined with the complex and variable working environment of a tractor, an integrated control strategy of engine throttle compensation–hydromechanical continuous variable transmission speed regulation is adopted for dual-flow transmission control. On the basis of the estimation of working resistance, a fuzzy algorithm is used to design the throttle compensation law. Considering the maximum driving power of a tractor as the target of variable speed control, an hydromechanical continuous variable transmission efficiency model is established, and the control law of an hydromechanical continuous variable transmission displacement ratio with the maximum driving power of the tractor under any working condition is determined. On the basis of the wavelet neural network proportional–integral–derivative algorithm, the control law of the hydromechanical continuous variable transmission speed regulation is designed, and the parameters of proportional–integral–derivative control are corrected in real time during the control process. Based on MATLAB/Simulink modelling and simulation and the real vehicle verification test, results showed that the influence of hydromechanical continuous variable transmission efficiency fluctuation on the driving power of the entire vehicle, the response lag of the pump-controlled motor system, and the effect of the leakage on the variable speed control and the fluctuation of the working resistance are solved by studying the hydromechanical continuous variable transmission variable speed transmission control strategy. This strategy improves the stability of the tractor speed and ensured the quality of the work, thereby improving the ability of the tractor to adapt to complex working environments.

Multi-Range Hydro-Mechanical Continuously Variable Transmission of Tractor

2009 ◽  
Vol 628-629 ◽  
pp. 167-172
Author(s):  
L.Y. Xu ◽  
Zhi Li Zhou ◽  
M.Z. Zhang ◽  
Y. Niu
Keyword(s):  
High Efficiency ◽  
Planetary Gear ◽  
Transmission Efficiency ◽  
Continuously Variable Transmission ◽  
Speed Range ◽  
Displacement Pump ◽  
Variable Transmission ◽  
Variable Displacement ◽  
Wide Speed Range ◽  
Ratio Transmission

In this paper, to improve the transmission ratio discontinuity problem during the gear shift process in the multi-gear fixed step ratio transmission of the tractors, a hydro-mechanical continuously variable transmission (HMCVT) for tractors is developed, which is composed of a single planetary gear differential train, a hydraulic transmission system consisted of the variable displacement pump (PV) and the fixed displacement motor (MF) and a multi-gear fixed step ratio transmission. Its stepless-speed-regulating characteristic, smooth range shifting condition and transmission efficiency are analyzed. The analytical results show that the tractors assembled with HMCVT can gain wide speed range and high transmission efficiency. There are eight high efficiency pure mechanical gears in the whole speed range, which is benefit to improve power and economic capabilities of vehicles.

Optimization of Hydraulic Pressure for Continuously Variable Transmission

2011 ◽  
Vol 317-319 ◽  
pp. 529-532
Author(s):  
Kei Lin Kuo
Keyword(s):  
Torque Converter ◽  
Transmission Efficiency ◽  
Gear Ratio ◽  
Continuously Variable Transmission ◽  
Hydraulic Pressure ◽  
Primary Input ◽  
Input Shaft ◽  
Variable Transmission ◽  
Labview Program ◽  
Set Up

Compared to conventional transmission layouts, Active continuously variable transmission (CVT) provides smoother gear shifting and gear ratio in smaller increments, and is, therefore, more accommodating the needs of both the driver and passengers. A few notable improvements are enhanced passenger comfort, higher transmission efficiency, and improved acceleration. Incorporating all of the above qualities has become a major developmental focus for the automotive industry, and the potential for improvement warrants further investigation. A CVT controls the gear ratio by changing the diameters of the primary (input) and the secondary (output) pulleys by adjusting the hydraulic pressure applied to each using valves. Hydraulic pressure in the channel is developed using a basic pump connected to the input shaft. Excess pressure produced at higher speed is wasted. This study aims to minimize this hydraulic pressure without affecting the transmission’s performance, in order to conserve energy. A user interface was set up and the CVT’s torque converter was modified such that the inner and outer shafts could be operated independently, allowing for full control of hydraulic pressure .This experiment successfully achieved, via a custom LabVIEW program, its goal of controlling the gear ratio between the primary and secondary pulleys whilst operating at lower pressures to those specified by the manufacturer. This proves that it is possible to fully control the CVT whilst operating at a reduced hydraulic pressure.

Power split continuously variable transmission systems with high efficiency

2001 ◽  
Vol 215 (3) ◽  
pp. 357-358 ◽  
Author(s):  
G. Mantriota
Keyword(s):  
Power Flow ◽  
High Efficiency ◽  
Continuously Variable Transmission ◽  
Operating Conditions ◽  
Kinetic Characteristics ◽  
The Past ◽  
Power Split ◽  
Continuously Variable Transmissions ◽  
Variable Transmission ◽  
Functional Solution

Continuously variable transmissions (CVTs) have developed notably in different applications over the past years. This is especially true in the automobile field because of advantages in terms of car handling and efficiency on urban roads. In this work an original functional solution of a power split CVT system is described. The proposed solution allows the generation of a power flow without recirculation. Kinetic characteristics of single-component devices are obtained and the power split CVT system's efficiency is determined by considering how the efficiency of the component devices changes as a function of operating conditions. The advantages for the power split CVT system are therefore shown in terms of power and efficiency in comparison with the single CVT.

scholarly journals Design Principles and Traction Performance of a Novel Zero-spin Rolling Conical Traction Continuously Variable Transmission

2020 ◽  
Author(s):  
Chao Li ◽  
Xiuquan Cao ◽  
Qing-tao Li
Keyword(s):  
Numerical Model ◽  
Computational Models ◽  
Design Principles ◽  
Transmission Efficiency ◽  
Continuously Variable Transmission ◽  
Transmission Ratio ◽  
Variable Transmission ◽  
Contact Models ◽  
Spin Momentum

Abstract In the existing traction continuously variable transmission (CVT), half toroidal CVT (HT-CVT) is considered to have a better traction performance. However, the HT-CVT has the spin losses due to its structural limitations, which significantly influences the traction efficiency. In this paper, the kinematic qualities and contact models of a novel zero-spin rolling conical CVT (RC-CVT) are studied, and then the rollers and conical disks are compactly designed through the proposed design principles. Subsequently, the transmission efficiency is investigated by using a detailed numerical model and compared with HT-CVT. Based on these computational models and parameters, the practical spin ratio, spin momentum and traction efficiency of RC-CVT are calculated and compared with HT-CVT. The results show that the practical spin ratio and spin momentum of RC-CVT are much smaller than that of HT-CVT, and the efficiency on fixed transmission ratio is consequently higher than that of HT-CVT.

Study on Optimal Load for Hydraulic Control System of Continuously Variable Transmission

2012 ◽  
Vol 516-517 ◽  
pp. 665-668
Author(s):  
Kei Lin Kuo
Keyword(s):  
Monitoring Program ◽  
Transmission Efficiency ◽  
Gear Ratio ◽  
Visual Programming ◽  
Continuously Variable Transmission ◽  
Operating Conditions ◽  
Hydraulic Pressure ◽  
Hydraulic Control ◽  
Main Research ◽  
Variable Transmission

In recent years, the main research focus for vehicle transmission systems has been the development of the Continuously Variable Transmission (CVT). CVTs can provide passengers with greater comfort, reduce energy consumption, and offer better transmission efficiency. CVT systems achieve the desired gear ratio by adjusting the hydraulic pressure on the rear and front pulleys using a solenoid valve. Our study aims to increase the efficiency of an existing CVT system, without reducing its performance. In this study have modified the CVT so that we can independently control the external and internal axes electronically. The speed of the hydraulic pump in the gearbox is not affected by the engine speed. In this way, In this study can achieve the lowest possible hydraulic pressure. In our study, In this study use the visual programming language LabVIEW as the human-machine interface for the monitoring program. In addition, a data acquisition system is used to collect experimental parameters, record data in real time, and perform data consolidation. Our system uses varying loads in order to evaluate the improvement in transmission efficiency over many operating conditions. Through the use of solenoids valves acting together, the pipeline hydraulic pressure can be varied. The widths of the front and rear pulleys are thus changed to achieve the goal of continuous variation. Under different loads, the relationships between the measured efficiency and the hydraulic pressure on the rear and front pulleys are used to verify and confirm the increase in efficiency achieved by controlling the hydraulic pressure.

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