Chassis Test Cycle Development for Heavy-Duty Engine Emissions Test Compliance

1998 ◽  
Author(s):  
David L. McKain ◽  
Nigel Clark ◽  
Thomas I. McDaniel ◽  
Jennifer A. Hoppie
Keyword(s):  
Heavy Duty ◽  
Test Cycle ◽  
Engine Emissions

Potential of the Variable Valve Actuation (VVA) Strategy on a Heavy Duty CNG Engine

2014 ◽  
Author(s):  
Mirko Baratta ◽  
Roberto Finesso ◽  
Daniela Misul ◽  
Ezio Spessa ◽  
Yifei Tong ◽  
...  
Keyword(s):  
Fuel Consumption ◽  
Operating Conditions ◽  
Intake Valve ◽  
Heavy Duty ◽  
Engine Emissions ◽  
Variable Valve Actuation ◽  
Cng Engine ◽  
Variable Valve ◽  
Working Point ◽  
Valve Actuation

The environmental concerns officially aroused in 1970s made the control of the engine emissions a major issue for the automotive industry. The corresponding reduction in fuel consumption has become a challenge so as to meet the current and future emission legislations. Given the increasing interest retained by the optimal use of a Variable Valve Actuation (VVA) technology, the present paper investigates into the potentials of combining the VVA solution to CNG fuelling. Experiments and simulations were carried out on a heavy duty 6-cylinders CNG engine equipped with a turbocharger displaying a twin-entry waste-gate-controlled turbine. The analysis aimed at exploring the potentials of the Early Intake Valve Closure (EIVC) mode and to identify advanced solutions for the combustion management as well as for the turbo-matching. The engine model was developed within the GT-Power environment and was finely tuned to reproduce the experimental readings under steady state operations. The 0D-1D model was hence run to reproduce the engine operating conditions at different speeds and loads and to highlight the effect of the VVA on the engine performance as well as on the fuel consumption and engine emissions. Pumping losses proved to reduce to a great extent, thus decreasing the brake specific fuel consumption (BSFC) with respect to the throttled engine. The exhaust temperature at the turbine inlet was kept to an almost constant value and minor variations were allowed. This was meant to avoid an excessive worsening in the TWC working conditions, as well as deterioration in the turbocharger performance during load transients. The numerical results also proved that full load torque increases can be achieved by reducing the spark advance so that a higher enthalpy is delivered to the turbocharger. Similar torque levels were also obtained by means of Early Intake Valve Closing strategy. For the latter case, negligible penalties in the fuel consumption were detected. Moreover, for a given combustion phasing, the IVC angle directly controls the mass-flow rate and thus the torque. On the other hand, a slight dependence on the combustion phasing can be detected at part load. Finally, the simulations assessed for almost constant fuel consumption for a wide range of IVC and SA values. Specific attention was also paid to the turbocharger group functioning and to its correct matching to the engine working point. The simulations showed that the working point on the compressor map can be optimized by properly setting the spark advance (SA) as referred to the adopted intake-valve closing angle. It is anyhow worth observing that the engine high loads set a constraint deriving from the need to meet the limits on the peak firing pressure (PFP), thus limiting the possibility to optimize the working point once the turbo-matching is defined.

Optimization of Automotive Engine Fuel Economy and Emissions

1977 ◽  
Vol 99 (2) ◽  
pp. 109-117 ◽  
Author(s):  
R. Prabhakar ◽  
S. J. Citron ◽  
R. E. Goodson
Keyword(s):  
Considerable Improvement ◽  
Exhaust Gas ◽  
Engine Fuel ◽  
Test Cycle ◽  
Engine Emissions ◽  
Control Variables ◽  
Automotive Engine ◽  
Operating Variables ◽  
Vehicle System ◽  
Gas Recirculation

Curve fitting techniques are used to analytically represent experimental data on engine emissions as a function of engine operating variables. A model of the engine-vehicle system is formulated and the optimal control inputs for a given vehicle and specified test cycle are computed. Air-fuel ratio, spark advance, and exhaust gas recirculation are considered as the control variables. The results of the study indicate that considerable improvement over stock car performance can be obtained if the control variables are varied in an optimal manner over the driving cycle.

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