Automatic Transmission Vehicle Research Articles

Mathematical modeling and performance prediction of a clutch actuator for heavy-duty automatic transmission vehicles

With regard to heavy-duty automatic transmission vehicles, precise control and fast response of clutch pressure, as well as transient high flow capacity, are central to shifting performance. In order to reduce fuel consumption and improve shift quality, a novel mathematical model for electro-hydraulic actuator used in heavy-duty automatic transmission is proposed to predict the response performance of a wet clutch in this paper. Firstly, the governing equations of a proportional solenoid valve (PSV) excited by the current of pulse width modulation (PWM), a pressure reducing valve (PRV) pilot operated by PSV and a simplified clutch model are derived by means of integration technology. Moreover the transfer function of PRV to the clutch is deduced to draw Bode plots. Then, the experimental date obtained from a real test bench is compared with the numerical results to validate the applicability of the mathematical model. Finally, simulations are performed on the forces, displacement, velocity, flow rate, clutch pressure, pressure deviation, response deviation and flow force. Numerical results indicate that the proposed model is valuable for the performance analysis and optimization of clutch actuator.

Slope shift strategy for automatic transmission vehicles based on road slope and vehicle mass identification

Road gradient and vehicle mass are estimated using a method with variable forgetting factor, which has strong adaptability and following capability. A control strategy with hierarchical correction is proposed for a vehicle that shifts on a slope. The shifting process is composed of the upper identification decision and lower shift correction executive layers. The upper layer focuses on collecting vehicle parameters, estimating road gradient and vehicle mass, and presenting a modified control decision. The lower layer performs the slope shift schedule from the upper layer. Results of the simulation test are shown. Furthermore, the designed strategy can duly downshift the gear uphill and avoid frequent shifting, thereby reducing the wear of the transmission parts and downshifting the gear timely downhill to utilise the torque characteristics of engine braking and reduce the wear of the braking system.

Slope shift strategy for automatic transmission vehicles based on road slope and vehicle mass identification

Slope shift strategy for automatic transmission vehicles based on road slope and vehicle mass identification

Slope Shift Strategy for Automatic Transmission Vehicles Based on the Road Gradient

Motivated by the development of high-precision digital maps for advanced driver assistance system (ADAS) in recent years, this study provides a new approach to solve the problems of the conventional automatic transmission vehicle travelling on sloping roads. Based on vehicle dynamics, shift problems on hilly roads are analyzed. A novel intelligent shift strategy is proposed, which consists of a dynamic shift schedule for the uphill, a safety shift schedule for the downhill, and a comprehensive economical shift schedule for the gentle slopes. A set of driver-in-loop co-simulation tests was conducted in a driving simulator that is equipped with a MATLAB/Simulink dynamics simulation platform. The test results verified the effectiveness of the new intelligent shift strategy. With the road information provided by a high-precision digital map, busy shifting can be eliminated, and improved dynamic performance can be achieved for a vehicle travelling on the uphill roads; undesired upshift can be prevented, and engine traction resistance can be used to relieve the load of braking system when a vehicle travelling on the downhill roads; also, fuel consumption can be reduced for a vehicle travelling on a gently sloped road. Consequently, this novel intelligent shift strategy offers a reliable and effective solution for improving a vehicle’s driving performance on a hilly road.

Driveline Ratio Selection and Shift Map Optimization for Automatic Transmission Vehicle at Concept Phase through Simulations

Driveline Ratio Selection and Shift Map Optimization for Automatic Transmission Vehicle at Concept Phase through Simulations

Driveline Ratio Selection and Shift Map Optimization for Automatic Transmission Vehicle at Concept Phase through Simulations

Driveline Ratio Selection and Shift Map Optimization for Automatic Transmission Vehicle at Concept Phase through Simulations

Analytical Investigation on the Damping Performance of Atorque Converter in an Automotive Driveline Model

Torque converters are avital part of automatic transmission vehicles. In this paper the influence of a torque converter on the lowest mode of driveline vibrations (shuffle mode) is investigated. The automotive driveline is modelled by lumped parameter models, in which a steady-state torque converter model is inserted between the engine and the gearbox. A detailed mathematical model of a two-degree of freedom and a three-degree of freedom dynamic systemis given. The resulting nonlinear differential equations are linearized to obtain system transfer functions and to study damping characteristics of the torque converter.Additionally, a dynamic system model with nonlinear equations is developed in MATLAB/Simulink to verify the linearized system. The simulations show that the high frequency vibrations from the engine side are damped due to the torque converter and the linearized model predicts the system response accurately.

自動車用ATにおける分数調波振動に関する基礎実験および理論解析

A torque converter is an element to transfer torque from the engine to the gear train in an automatic transmission vehicle. There is a damper spring on the lock-up clutch in the torque converter that reduces the amplitude of vibration caused by engine combustion. The damper is designed using a piecewise-linear spring with three stages in order to address a problem of space limitations. However, the damper causes a nonlinear vibration called subharmonic vibration of order 1/2. The frequency of the subharmonic vibration is half of the engine forced vibration frequency. In this study, in order to clarify the occurrence mechanism of the subharmonic vibration caused by the non-linearity of a piecewise-linear spring, fundamental experiments and numerical analysis were performed. The experimental setup is single-degree-of-freedom system that has two stiffness stages and the numerical analysis was performed under same condition as the experiment by using shooting method. According to the results of the experiments and numerical analysis, it was found that the subharmonic vibration occurs when the excitation frequency is near the twice of the resonance frequency and the equilibrium point is around a switching point of spring stiffness, and the smaller stiffness ratio and larger damping can suppress the subharmonic vibration. Also, the experimental and analytical results were well agreed with each other and the correctness of the experimental results were confirmed.

동력계 시험을 이용한 자동화 수동변속차량의 클러치 토크 분석

Article history: With the rise in oil prices and ongoing concerns about environment, there is an increased amount of interest in automated manual transmission (AMT) vehicles. Torque control in an AMT vehicle is attained by controlling the displacement of the dry-type clutch's actuator. To provide good ride comfort akin to that of an automatic transmission vehicle, the clutch control is vital to an AMT vehicle. In this study, a method of obtaining the clutch torque from a dynamometer test is devised. This method is able to identify the relationship between the displacement of the clutch actuator and the clutch torque. A simulator for estimating the performance of an AMT vehicle is developed using MATLAB Simulink. The results obtained from both the vehicle and simulation exhibit a similar trend.

Shift Quality Analysis of Heavy-Duty Vehicle Automatic Transmission Shift Control Valve

The structural concepts of Switch solenoid valve and proportional solenoid valve were proposed for the hydraulic shift control system of some hydrodynamic mechanical automatic transmissions. Shift oil pressure of stationary combination valve and proportional solenoid valve was modeled, simulated, contrasted and analyzed by dynamic simulation software in order to study the shift quality of heavy-duty vehicle automatic transmission. The results show that proportional solenoid valve is better to control the characteristic of shift oil pressure, reduce shift shock, improve shift quality and comfort than stationary combination valve. The correctness and validity of the model were verified through bench test, which reflected the dynamic characteristics of shift oil pressure of hydrodynamic mechanical automatic transmission. The results can be used to match the performance and predict heavy-duty vehicle shifting process, and to further lay the foundation for the enhancement of shift performance of the system.

Adaptive Gearshift Strategy Based on Generalized Load Recognition for Automatic Transmission Vehicles

Recognizing various driving conditions in real time and adjusting control strategy accordingly in automatic transmission vehicles are important to improve their adaptability to the external environment. This study defines a generalized load concept which can comprehensively reflect driving condition information. The principle of a gearshift strategy based on generalized load is deduced theoretically, adopting linear interpolation between the shift lines on flat and on the largest gradient road based on recognition results. For the convenience of application, normalization processing is used to transform generalized load results into a normalized form. Compared with the dynamic three-parameter shift schedule, the complex tridimensional curved surface is not needed any more, so it would reduce demands of memory space. And it has a more concise expression and better real-time performance. For the target vehicle, when driving uphill with gradient 11%, the vehicle load is about 280~320 Nm; when driving downhill, the value is around −340~−320 Nm. Road tests show that generalized vehicle load keeps near 0 in zero-load condition after calibration, and an 11% grade can be estimated with less than 1.8% error. This method is convenient and easy to implement in control software and can identify the driving condition information effectively.

Fuel consumption and gas emissions of an automatic transmission vehicle following simple eco‐driving instructions on urban roads

Following eco-driving instructions can reduce fuel consumption between 5 to 20% on urban roads with manual cars. The majority of Australian cars have an automatic transmission gear-box. It is therefore of interest to verify whether current eco-driving instructions are e cient for such vehicles. In this pilot study, participants (N=13) drove an instrumented vehicle (Toyota Camry 2007) with an automatic transmission. Fuel consumption of the participants was compared before and after they received simple eco-driving instructions. Participants drove the same vehicle on the same urban route under similar tra c conditions. We found that participants drove at similar speeds during their baseline and eco-friendly drives, and reduced the level of their accelerations and decelerations during eco-driving. Fuel consumption decreased for the complete drive by 7%, but not on the motorway and inclined sections of the study. Gas emissions were estimated with the VT-micro model, and emissions of the studied pollutants (CO2, CO, NOX and HC) were reduced, but no di erence was observed for CO2 on the motorway and inclined sections. The di erence for the complete lap is 3% for CO2. We have found evidence showing that simple eco-driving instructions are e cient in the case of automatic transmission in an urban environment, but towards the lowest values of the spectrum of fuel consumption reduction from the di erent eco-driving studies.

Analysis of the effect of cold start on fuel economy of gasoline automatic transmission vehicle

FTP75 driving cycle is used in many countries for evaluation of vehicle fuel economy. FTP75 has 3 phases, where the Phase 1 and the Phase 3 have a same velocity profile, but the Phase1, which is known as cold start phase, shows lower fuel efficiency than the Phase 3. In order to analyze the difference of fuel economy between Phase 1 and Phase 3, vehicle tests are performed. The test results show that the differences of fuel economy is ranging from 3.9% to 18.5%. The factors of the difference of fuel economy for gasoline automatic transmission vehicles are analyzed in this research. The key factors affecting the difference of fuel economy are engine friction loss, torque converter loss and accessory loss. The quantitative analysis of these factors is performed.

Measurement and Modeling of Perceived Gear Shift Quality for Automatic Transmission Vehicles

Measurement and Modeling of Perceived Gear Shift Quality for Automatic Transmission Vehicles

Research on Application of Wavelet Denoising Method Based on Signal to Noise Ratio in the Bench Test

During the tests of the vehicle automatic transmission bench, the acceleration signal is needed to be denoised. As a means of denoising, wavelet threshold denoising method has small amount of calculation and better filtering effect. However, adopting different wavelet basis functions as well as different threshold rules might have a direct effect on the signal denoising. In this paper, we firstly construct the simulated noisy signal approximated to the observed signal, and then do the signal denoising experiment of parameter matching. Secondly, seven Symlets wavelet basis functions and four classical wavelet threshold rules are selected and tested one by one. Signal to noise ratio (SNR) and root mean square error (RMSE) of the denoised signal, the evaluation indicators, are calculated and carried out in accordance with the merits of denoising effect. Thus the optimal combination of the fixed threshold rule and sym8 wavelet basis function is obtained. Finally, this combination is used in the bench test to denoise the angular acceleration signal, and good filtering effect is achieved.

Research for Cornering Gearshift Strategy of Automatic Transmission Vehicles Based on Fuzzy Inference

Undesired gearshift often occurred when the vehicle was under the curve driving condition. To resolve this problem, this paper proposed a fuzzy correction gearshift strategy under cornering which put the lateral acceleration and lateral acceleration variation rate, the external load and the real-time vehicle speed as parameters. Road test results showed that the undesired gear shift frequency was largely reduced and this method improved driving comfort and security under cornering condition.

Simulation and Analysis on Stationary Combination Valve of Heavy-Duty Vehicle Automatic Transmission

A mathematical model and dynamic characteristics simulation model were established based on working principle of stationary combination valve in order to study shift quality of heavy-duty vehicle automatic transmission. Various parameters on buffer characteristics influence and outer diameter of the clutch hydraulic cylinder, the spring stiffness and preload influenced on the buffer time, starting pressure and termination pressure were gained with using batch function. The results show that the smaller the orifice diameter, spring stiffness and preload is, the longer the buffer time is, and the curve of buffer characteristic is downward translation. The larger the outer diameter of the clutch hydraulic cylinder, spring stiffness and preload is, the shorter the buffer time is, while the initial pressure and the termination pressure are relatively lower.

A New Vehicle Intelligent Shift System

The reasons to develop vehicle intelligent shift system were presented. A new vehicle intelligent shift system was developed, which included the shift subsystem of automatic transmission vehicle on the slope, on the low friction road, and in the turn situation. Also, the shift strategy based on the individual driving operation was developed. Furthermore, a hierarchical architecture of the developed intelligent shift system was proposed.

Study on Shift Schedule of Pure Electric Vehicles Automatic Transmission

This paper puts forward a research design method of pure electric vehicle automatic transmission shift schedule based on the urban road conditions in connection with the problems of the low average speed, the high percentage of idle, and frequently shifting in pure electric vehicle. In order to improve the performance of pure electric vehicle automatic transmission and the using efficiency of the motor, this paper formulates a fuzzy shift schedule in the view of the economy. At the same time, this paper supplies a vehicle simulation in the view of economy through a application instance and the MATLAB / SIMULINK / ADVISOR software. The simulation results show that the fuzzy shift strategy can meet the requirements of the economy very well.

Novel Tensor Product Models for Automatic Transmission System Control

This paper discusses novel tensor product (TP) models for the control of two complex components of the vehicle automatic transmission systems, namely the drive line without clutch and, the valve–clutch. The TP models are obtained by a transformation of the linear parameter-varying models derived from the first principle nonlinear mathematical models of the controlled processes. Experimental results validate the performance of the proposed TP models.