Alessandro Picarelli

Detailed Powertrain Dynamics Modelling in Dymola - Modelica

Abstract Two Modelica libraries for engine and powertrain modeling are presented called the Powertrain Dynamics library and the Engines library. Together, these libraries enable the modeling and simulation of powertrain systems including their fluid dynamic, pollutant emission, mechanical and thermal performance in one simulation environment (Dymola). The libraries are defined using the object orientated modelling language Modelica. The libraries are used to study the response of the vehicle and powertrain during dynamic driving events such as vehicle launch, tip-in and tip-out driveability and powertrain nvh. The benefits of using a dynamic torque converter model compared to a steady state model for these applications are presented.

Investigating the Effect of a Sonic Restrictor in the Intake of an Engine

The air induction system is one of the engine subsystems that most influences fuel efficiency and power generation, especially in restricted race engine applications. In this paper, the quasi-1D model of a sonic restrictor is presented, together with its integration in an engine model, in order to investigate the behaviour of the engine power and torque when the choked condition is reached. The study shows how power and torque curves are affected when a sonic restrictor is installed within the intake system and outlines the need of detailed simulations in a restricted engine development process, to avoid steep engine power reductions at high speeds.

Engine thermal shock testing prediction through coolant and lubricant cycling in Dymola

In this work, an acausal multi-domain physical system model is used to study the interaction between an internal combustion engine operation and a range of cooling and lubrication system thermal cycling scenarios. Although the model can be used for modelling a wide range of scenarios, this paper concentrates on the application of engine thermal shock test dynamics prediction through coolant and lubricant cycling. An internal combustion engine is loadcontrolled on a dynamometer. Coolant and lubricant temperature transients are imposed on the engine system. Using freely available and commercial Modelica Libraries within the Dymola environment, the systems integration of the coolant rigs, lubricant rigs and engine is achieved. The rigs and the controllers are validated against test data to create predictive models of such systems for test virtualisation. This allows the user to develop and define control strategies for the tests from desktop, prior to engaging in laboratory tests.

Predicting the effect of powertrain preconditioning on vehicle efficiency

ABSTRACT Under extreme climatic conditions, the vehicle fuel consumption can be far from the certified value. Given the growing concern for polluting emissions, it is necessary to investigate a way to improve the overall vehicle efficiency and thus reduce the emissions and fuel consumption gap. One solution is to pre-warm the gearbox and the engine in order to make it work at an optimal temperature to achieve the best efficiency possible. Indeed, low lubricant temperature is a source of reduced vehicle efficiency due to the lubricant viscosity rising exponentially at very low temperature. Using the Powertrain Dynamics library, a vehicle model with a detailed equation-based gearbox model taking into account the temperature-dependent losses and a map-based engine including temperature-dependent emission models (CO, NOx, HC and particulates) is developed.