Physically based volumetric efficiency model for diesel engines utilizing variable intake valve actuation

2011 ◽  
Vol 13 (2) ◽  
pp. 169-184 ◽  
Author(s):  
L Kocher ◽  
E Koeberlein ◽  
D G Van Alstine ◽  
K Stricker ◽  
G Shaver
Keyword(s):  
Diesel Engines ◽  
Volumetric Efficiency ◽  
Intake Valve ◽  
Physically Based ◽  
Valve Actuation

Control-Oriented Gas Exchange Model for Diesel Engines Utilizing Variable Intake Valve Actuation

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Lyle Kocher ◽  
Ed Koeberlein ◽  
Karla Stricker ◽  
D. G. Van Alstine ◽  
Greg Shaver
Keyword(s):  
Gas Exchange ◽  
Diesel Engines ◽  
Exchange Process ◽  
Exhaust Gas ◽  
Intake Valve ◽  
Physically Based ◽  
Valve Position ◽  
Gas Exchange Process ◽  
And Control ◽  
Valve Actuation

Modeling and control of the gas exchange process in modern diesel engines is critical for the promotion and control of advanced combustion strategies. However, most modeling efforts to date use complex stand-alone simulation packages that are not easily integrated into, or amenable for the synthesis of, engine control systems. Simpler control-oriented models have been developed; however, in many cases, they do not directly capture the complete dynamic interaction of air handling system components and flows in multicylinder diesel engines with variable geometry turbocharging (VGT), high pressure exhaust gas recirculation (EGR), and flexible intake valve actuation. Flexibility in the valvetrain directly impacts the gas exchange process not only through the effect on volumetric efficiency but also through the combustion process and resulting exhaust gas enthalpy utilized to drive the turbomachinery. This paper describes a low-order, five state model of the air handling system for a multicylinder variable geometry turbocharged diesel engine with cooled EGR and flexible intake valve actuation, validated against 286 steady state and 62 transient engine operating points. The model utilizes engine speed, engine fueling, EGR valve position, VGT nozzle position, and intake valve closing (IVC) time as inputs to the model. The model outputs include calculation of the engine flows as well as the exhaust temperature exiting the cylinders. The gas exchange model captures the dynamic effects of the not only the standard air handling actuators (EGR valve position and VGT position) but also IVC timing, exercised over their useful operating ranges. The model's capabilities are enabled through the use of analytical functions to describe the performance of the turbocharger, eliminating the need to use look-up maps; a physically based control-oriented exhaust gas enthalpy submodel and a physically based volumetric efficiency submodel.

Physically-Based Volumetric Efficiency Model for Diesel Engines Utilizing Variable Intake Valve Actuation

2011 ◽  
Author(s):  
Lyle Kocher ◽  
Ed Koeberlein ◽  
D. G. Van Alstine ◽  
Karla Stricker ◽  
Greg Shaver
Keyword(s):  
Diesel Engine ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Intake Valve ◽  
Valve Timing ◽  
Tuning Parameters ◽  
Wide Range ◽  
Physically Based ◽  
Valve Actuation

Advanced diesel engine architectures employing flexible valve trains enable emissions reductions and fuel economy improvements. Flexibility in the valve train allows engine designers to optimize the gas exchange process in a manner similar to how common rail fuel injection systems enable optimization of the fuel injection process. Modulating valve timings directly impacts the volumetric efficiency of the engine. In fact, the control authority of valve timing modulation over volumetric efficiency is three times larger than that due to any other engine actuator. Traditional empirical or regression-based models for volumetric efficiency, while suitable for conventional valve trains, are therefore challenged by flexible valve trains. The added complexity and additional empirical data needed for wide valve timing ranges limit the usefulness of these methods. A physically-based volumetric efficiency model was developed to address these challenges. The model captures the major physical processes occurring over the intake stroke, and is applicable to both conventional and flexible valve trains. The model inputs include temperature and pressure in the intake and exhaust manifolds, intake and exhaust valve timings, bore, stoke, connecting rod length, engine speed and effective compression ratio, ECR. The model is physically-based, requires no regression tuning parameters, is generalizable to other engine platforms, and has been experimentally validated using an advanced multi-cylinder diesel engine equipped with a flexible variable intake valve actuation system. Experimental data was collected over a wide range of the operating space of the engine and augmented with air handling actuator and intake valve timing sweeps to maximize the range of conditions used to thoroughly experimentally validate the model for a total of 217 total operating conditions. The physical model developed differs from previous physical modeling work through the novel application of ECR, incorporation of no tuning parameters and extensive validation on unique engine test bed with flexible intake valve actuation.

Robust Oxygen Fraction Estimation for Diesel Engines Utilizing Variable Intake Valve Actuation*

2012 ◽  
Vol 45 (30) ◽  
pp. 310-317 ◽  
Author(s):  
Lyle E. Kocher ◽  
Karla Stricker ◽  
Daniel G. Van Alstine ◽  
Gregory M. Shaver
Keyword(s):  
Diesel Engines ◽  
Intake Valve ◽  
Oxygen Fraction ◽  
Valve Actuation

Oxygen fraction estimation for diesel engines utilizing variable intake valve actuation

2012 ◽  
Author(s):  
L. E. Kocher ◽  
K. Stricker ◽  
D. G. Van Alstine ◽  
Ed Koeberlein ◽  
G. M. Shaver
Keyword(s):  
Diesel Engines ◽  
Intake Valve ◽  
Oxygen Fraction ◽  
Valve Actuation

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.

Modeling of Variable Intake Valve Timing in SI Engine

2006 ◽  
Author(s):  
S. Ahmad Ghazi Mir Saied ◽  
S. Ali Jazayeri ◽  
Amir H. Shamekhi
Keyword(s):  
Internal Combustion Engines ◽  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Major Influence ◽  
Combustion Engines ◽  
Intake Valve ◽  
Si Engine ◽  
Operating Condition ◽  
Valve Motion ◽  
Engine Map

In internal combustion engines valve events and timings are among the most important parameters which have a major influence on the engine’s operation and volumetric efficiency. By using camless valvetrain strategy, improvement in fuel economy as well as an increase in entering air charge is found throughout the engine map with the largest benefits arising from low speed operating conditions. The system offers a continuously variable and independent control of virtually all parameters of valve motion. This permits optimization of valve events for each operating condition without any compromise. In this paper we describe a phenomenological model for an unthrottled operation of a camless intake process of spark-ignited (SI) engine. Initially the cylinder breathing dynamics is modeled and results are validated with experimental data of a conventional engine with cam-driven valve profile during unthrottled operation. Then we determine the most optimized intake valve profile in order to have the most volumetric efficiency and proper operation for each operating condition based on the existing model and using numerical techniques.

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