A Model for Simulating the Instantaneous Crank Kinematics and Total Mechanical Losses in a Multi-Cylinder In-Line Engine

Potenza, R, Dunne, J F, Vulli, S and Richardson, D (2007) A Model for Simulating the Instantaneous Crank Kinematics and Total Mechanical Losses in a Multi-Cylinder In-Line Engine. International Journal of Engine Research, 8 (4). pp. 379-397. ISSN 1468-0874

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Abstract

A two-degree-of-freedom dynamic model is constructed to simulate the instantaneous crank kinematics and total mechanical losses arising in a multicylinder gasoline engine coupled to a dynamometer. The simulation model is driven using specified cylinder gas pressures, and loaded by nominal brake torque and total friction losses. Existing semi-empirical torque loss models (based on calibrated single-cylinder diesel engine data) are used to account for the instantaneous friction losses in the piston-ring assembly, in bearings, and in auxiliaries. The model is specialized to the simulation of crank kinematics and matched brake torque for a three-cylinder in-line direct injection spark ignition (DISI) engine, without a gearbox. This allows the total friction loss to be separated from the brake torque for an engine not fitted with the very large number of sensors otherwise needed to calibrate analytical friction models. An equivalent simulation model is also constructed using GT-Crank, which excludes explicit reference to friction. In using both models to simulate steady state operation at a specified mean engine speed, the output torque is matched by iteration. The GT-Crank model necessarily compensates for internal losses by exaggerating the total output torque. Both simulation models are compared with measured crank kinematics and brake torque obtained from a dynamometer-loaded I3 DISI engine. The paper shows that by comparing the matched output torque from simulation with the measured output torque from the engine, the proposed model gives a very good high-speed prediction of the total mechanical losses. At low speed, the instantaneous model is still not accurate. It is also shown, however, that apart from the no-load condition, use of an average torque to compensate for friction (as in GT-Crank) is wholly acceptable for simulating instantaneous crank kinematics. This is the first reported instance of a simulation model (which includes the particu

Item Type: Article
Schools and Departments: School of Engineering and Informatics > Engineering and Design
Depositing User: Julian Dunne
Date Deposited: 06 Feb 2012 19:51
Last Modified: 27 Apr 2012 09:20
URI: http://sro.sussex.ac.uk/id/eprint/22609
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