A Validated Modular Model for Hydraulic Actuation in a Pushbelt Continuously Variable Transmission

摘要

A reduction in the fuel consumption of a passenger car with a pushbelt continuouslynvariable transmission (CVT) can be established via optimization of the hydraulic actua-ntion system. This requires a model of the dynamic characteristics with low complexity andnhigh accuracy, e.g., for closed-loop control design, for closed-loop simulation, and fornoptimization of design parameters. The hydraulic actuation system includes a large num-nber of hydraulic components and a model of the dynamic characteristics is scarce, whichnis caused by the complexity, the nonlinearity, and the necessity of a large number ofnphysical parameters that are uncertain or unknown. In this paper, a modular model fornthe hydraulic actuation system on the basis of first principles is constructed and vali-ndated, which is characterized by a relatively low complexity and a reasonably highnaccuracy. A modular approach is pursued with respect to the first principles models of thenhydraulic components, i.e., a hydraulic pump, spool valves, proportional solenoid valves,nchannels, and hydraulic cylinders, which reduces complexity and improves transparency.nThe model parameters are either directly provided, directly measured, or identified. Thenmodel of the hydraulic actuation system is composed of the models of the hydraulicncomponents and is experimentally validated by means of measurements that are obtainednfrom a production pushbelt CVT. Several experiment types are considered. The corre-nspondence between the measured and simulated responses is fairly good.