General background of the application of the CVT:by example of the VDT EcoDrive transmission

A further reduction of fuel consumption, while maintaining or even improving driveability andperformance, is the primary aim of VDT’s EcoDrive project. The general designconsiderations that led to the newest push-belt based CVT forms the topic of the presentpaper. The following items are covered: transmission layout, fuel consumption map, ratiocoverage, variator clamping strategy and engine speed control. Measurements on a testvehicle are presented. This paper is intended to present the relevant results influencing theprimary project targets: fuel consumption and driveability improvement

Slip controller design and implementation in a Continuously Variable Transmission

Continuously Variable Transmissions (CVT) can be used to operate a combustion engine in a more optimal working point. Unfortunately, due to the relatively low efficiency of modern production CVT’s the total efficiency of the driveline is not increased significantly. This low efficiency is mainly caused by losses in the hydraulic actuation system and the variator. Decreasing the clamping forces in the variator greatly improves the efficiency of the CVT. However, lower clamping forces increase the risk of excessive belt slip, which can damage the system. In this paper a method is presented to measure and control slip in a CVT in order to minimize the clamping forces while preventing destructive belt slip. To ensure robustness of the system against torque peaks, a controller is designed with optimal load disturbance response. A synthesis method for robust PI(D)-controller design is used to maximize the integral gain while making sure that the closed loop system remains stable. Experimental results prove the validity of the approach

The Empact CVT: modeling, simulation and experiments

This paper shows the implementation of a simulation model for newelectromechanically actuated metal V-belt type continuously variabletransmission (CVT), referred to as the Empact CVT. An analysis ofthe dynamics of the actuation system and of the driveline shows thatthe eigenfrequencies of the system depend on both the CVT ratio andthe slip in the variator. An accurate variator model is required to incorporateall characteristic dynamics. The implemented variator modelis an explicit formulation of a model which gives an estimation of thetension forces and compression forces in the pushbelt. The simulationmodel also includes slip, shifting losses based on transient variator modelsand friction. Simulations are compared to measurements, showinggood results

Experimental Assessment of an Energy Management Strategy on a Fuel Cell Hybrid Vehicle

Fuel cell hybrid power trains comprise an energy storage to supply peaks in the power demand and to facilitate regenerative braking. In terms of control systems, the presence of storage provides additional freedom to minimize the vehicle’s fuel consumption. In a previous paper [1] an analytical solution to the energy management problem for fuel cell hybrid propulsion systems was derived and compared with existing strategies like the Equivalent Consumption Minimization Strategy (ECMS) [1–4]. An experimental study has been carried out on a Fiat Doblo, which was converted from a regular gasoline powered vehicle into a fuel cell hybrid vehicle. The fuel cell drive train comprises a 10kW proton exchange membrane fuel cell stack connected by means of a DC/DC converter to a Li-ion battery. The aforementioned analytical energy management strategy was used during the experiments. The experiments were carried out on a roller test bench and on the road. The experiments were conducted not only to validate the energy management strategy and the underlying models but also to establish its practical value. The paper shortly reviews the energy management problem and solution. Next the vehicle and its fuel cell hybrid drive train are presented as well as the experimental setup. The paper finishes by stating the experimental results and the conclusions

Simulation of the PEM fuel cell hybrid power train of an automated guided vehicle and comparison with experimental results

At HAN University research has been started into the development of a PEM fuel cell hybrid power train to be used in an automated guided vehicle. For this purpose a test facility is used with the possibility to test all important functional aspects of a PEM fuel cell hybrid power train. In this paper the first experimental results of the testing of the power train are presented, driving a drive cycle designed especially for this automated guided vehicle. Experimental results are compared to results for this specific drive cycle from the simulation of the power train with the QSS-toolbox, using a simple battery model of our specific energy storage situation. Further some recommendations for improvement of the test facility are given, resulting from restrictions encountered during the experiments