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To comply with increasingly stringent targets for emissions and fuel economy, more and more precise mass airflow sensor technology is required on both gasoline and Diesel engines. On gasoline engines, the mass flow signal is used to more precisely determine engine load. This, in turn, enables more precise fuel metering than can be achieved with traditional indirect load detection methods. The lambda control variations are reduced significantly, and a more precise control of the mixture ratio can be achieved in cases where the lambda probe, i. e., the oxygen sensor, does not yet work perfectly. On Diesel engines, the mass airflow sensor is used for the most precise automatic and independent control of EGR systems, including even the control of map dependent Diesel injection pumps. Backflow conditions on Diesel engines with four or fewer cylinders, especially in combination with EGR, render normal mass air flow meter sensing inadequate.

To reduce the amount of fuel vapor created in the fuel tank, we developed a variable-capacity, plastic bladder fuel tank that is efficient, reliable, and provides permeation prevention performance. This bladder fuel tank changes in shape and total capacity in accordance with the volume of fuel it holds. Thus, in contrast to the conventional fuel tank, it can dramatically reduce the amount of fuel vapor that is ordinarily created in the fuel tank while the vehicle is being refueled, parked, or driven. The bladder fuel tank has been adopted in the Vapor Reducing Fuel Tank System of the North American model Prius, a vehicle that operates under the Toyota Hybrid System (THS), which complies with the SULEV exhaust emission requirement. This paper primarily gives an outline of the technology for manufacturing the bladder fuel tank.

Variable geometry turbines (VGT) are of particular interest to advanced diesel powertrains for future conventional trucks, since they can dramatically improve system transient response to sudden changes in speed and load, characteristic of automotive applications. VGT systems are also viewed as the key enabler for the application of the EGR system for reduction of heavy-duty diesel emissions. This paper applies an artificial neural network methodology to VGT modeling in order to enable representation of the VGT characteristics for any blade (nozzle) position. Following validation of the ANN model of the baseline, fixed geometry turbine, the VGT model is integrated with the diesel engine system. The latter is linked to the driveline and the vehicle dynamics module to form a complete, high-fidelity vehicle simulation.

Engine models are a basis for better controlling combustion process and the exhaust emissions resulting from it. Currently the zero- and quasi-dimensional models are mostly used. These types of models are also addressed in this article. Zero-dimensional models are computationally efficient and show good simulation results concerning the in-cylinder pressure. However, by neglecting multi-zonal resolution they are not able to describe fuel efficiency or the generation of pollutants. It is therefore necessary to enhance combustion process models with phenomenological fuel spray and vaporization models, with a local resolution of at least two zones. The chemical model for the calculating of emissions shall be based on a two-zone model. The amount of mass, which is transferred from the unburned to the burned zone, is entered into a chemical model based on the chemical equilibrium for the OCH-system (oxygen/carbon/hydrogen).

The need for a rigorous systems engineering approach to automotive powertrains has been addressed in this work from the perspective of the diesel engine. A high-fidelity engine simulation has been integrated with a total vehicle model for the purpose of reverse engineering the optimal powerplant for a given vehicle mission. Engine parameters have been coordinated between the simulations to develop a framework for total vehicle design. The design strategies discussed in this paper allow engine researchers to set targets for individual system components and to analyze the tradeoffs associated with different vehicle mission objectives. A detailed case study employing these techniques is presented for a conventional vehicle where the most fuel-efficient engine is found that simultaneously conforms to the desired performance criteria.

A quasi-dimensional, multi-zone, direct injection (DI) diesel combustion model has been developed and implemented in a full cycle simulation of a turbocharged engine. The combustion model accounts for transient fuel spray evolution, fuel-air mixing, ignition, combustion and NO and soot pollutant formation. In the model, the fuel spray is divided into a number of zones, which are treated as open systems. While mass and energy equations are solved for each zone, a simplified momentum conservation equation is used to calculate the amount of air entrained into each zone. Details of the DI spray, combustion model and its implementation into the cycle simulation of Assanis and Heywood [1] are described in this paper. The model is validated with experimental data obtained in a constant volume chamber and engines. First, predictions of spray penetration and spray angle are validated against measurements in a pressurized constant volume chamber.

During the last years a great deal of efforts have been made to reduce pollutant emissions from Direct Injection Diesel Engines. The use of gaseous fuel as a supplement for liquid diesel fuel seems to be one solution towards these efforts. One of the fuels used is natural gas, which has a relatively high auto - ignition temperature and moreover it is an economical and clean burning fuel. The high auto - ignition temperature of natural gas is a serious advantage against other gaseous fuels since the compression ratio of most conventional diesel engines can be maintained. The main aspiration from the usage of dual fuel (liquid and gaseous one) combustion systems, is the reduction of particulate emissions. In the present work are given results of a theoretical investigation using a model developed for the simulation of gaseous fuel combustion processes in Dual Fuel Engines.

The transient operation of a Diesel engine when the turbocharger compressor is driven to its unstable region was examined though detailed simulation. This was accomplished by using a mathematical model, capable of predicting the behavior of a compression system including the case where compressor surging occurs. This model was tested for a simple compression system, and validated against available experimental data. After that, it was incorporated into a detailed reciprocating engine simulation code. Transient engine operation cases in which compressor surging occurred were simulated and the derived results for the behavior of the compressor and engine are presented.

Models often use time rather than strokes (crank-angle) as the independent variable to describe engine dynamics despite the fact that the dynamics of an internal combustion engine are intrinsically linked to the combustion events. In this paper, two models are developed in parallel in which not only the independent variable is changed but the notion of mass flows as well: flows are in [g/s] for the time-based model and in [g/st] for the event-based model. Both models are of the same computational complexity and show the same accuracy in validation. The investigation of the model properties shows that variations in the flow-related parameters are reduced by a factor of two to five for the event-based model. However, those of the crankshaft dynamics are increased. It is concluded that the model should be chosen in context of the control system to be designed.

The purpose of this paper is to present an alternative method to predict the temperature and flow field in a motored internal combustion engine with bowl in piston. For the fluid flow it is used a phenomenological model which is coupled to a computational fluid dynamic method to solve the energy conservation equation and therefore the temperature field. The proposed method has the advantage of simplicity and low computational time. The computational procedure solves the energy conservation equation by a finite volume method, using a simplified air motion model (estimating axial and radial velocities) to calculate the flow field. The finite volume discretization employs the implicit temporal and hybrid central upwind spatial differencing. The grid used contracts and expands following the piston motion, and the number of nodes in the direction of piston motion vary depending on the crank angle.

Combustion instability and white smoke emissions are serious problems during cold starting of diesel engines. In this investigation, a model has been applied to predict misfiring based on an analysis of the autoignition process. The effect of injection timing on combustion instability during the cold start transient, at different ambient temperatures is investigated, both theoretically and experimentally. Maps have been developed to show the zones where misfiring would occur. The experimental work was conducted on a direct injection heavy-duty diesel engine in a cold room. The room temperature covered a range from 21 ° C to -10 ° C. The cycle-by-cycle data analysis was made and results plotted on the developed maps. The experimental results correlated fairly well with the model prediction. Based on the analysis, a new strategy for cold starting can be developed to reduce combustion instability and white smoke emissions.

This paper reviews the emissions from direct injection (DI) diesel engine in the initial period of controlled engine operation following start-up. The tests were undertaken in „cold start” mode (temperature of cooling water and lube oil equal to ambient temperature) and „warm start” mode* (after attaining a state of equilibrium). Both results were compared.

CRT looks promising in achieving clean Diesel emission particularly PM, however, it presents two limits in exhaust gas temperature levels, i.e., at idling to low power region requiring emission temperature 260°C minimum, and at high power region 450°C maximum. These problems can only be solved by the proposed method under the currently available known technologies. At the lower power side, 260°C minimum, can be materialized by the use of “Exhaust Secondary Cam (ESC)”, throttling intake air and exhaust gas lines together with other means like reduction of number of cylinders in operation. At the high power side, 450°C maximum, will easily be cleared by “Hyperbrid supercharging system” invented by the author.

As CO2 emissions from vehicles is gaining a global attention the low fuel consuming power-train is in much greater demand than before. Some alternatives are suggested but the HSDI diesel engine would be the most realistic solution. Vehicle simulation shows that low fuel consuming car can be realized by applying 1∼1.2L HSDI diesel engine in vehicles weighing about 750kg. While the direct injection diesel engine has been researched for a long time enhancement of mixing between air and fuel in a limited space makes it challenging area to develop a small swept volume HSDI diesel engine. We are investigating small HSDI diesel engine combustion technologies as an effort to realize low fuel consuming vehicle. Our main objective in this study is to have a better understanding of the combustion related parameters from such a small size HSDI diesel engine in order to improve engine performance.

In the last years, there has been an increasing concern on the emission of ultrafine particles in the atmosphere. A detailed study of formation and oxidation of these particles in the environment of the diesel cylinder presents many experimental difficulties due to the high temperatures, pressures and extremely reactive intermediate species. In this paper, in order to follow the different phases of diesel combustion process, high temporal and spatial resolution optical techniques were applied in the optically accessible chamber of diesel engine, at 2000 rpm and A/F=80:1 and 60:1. Simultaneous extinction, scattering and flame chemiluminescence measurements from UV to visible were carried out, in order to study the diesel combustion process from the droplet ignition to the formation of soot, through the growth of its precursors.

Time resolved changes in unburned hydrocarbon emissions and their components were investigated in a DI diesel engine with a specially developed gas sampling system and gas chromatography. The tested transient operations include starting and increasing loads. At start-up with high equivalence ratios the total hydrocarbon (THC) at first increased, and after a maximum gradually decreased to reach a steady state value. Reducing the equivalence ratio of the high fueling at start-up and shortening the high fueling duration are effective to reduce THC emissions as long as sufficient startability is maintained. Lower hydrocarbons, mainly C1-C8, were the dominant components of the THC and mainly determined the THC behavior in the transient operations while the proportion of hydrocarbon (HC) components did not significantly change. The unregulated toxic substances, 1,3 butadiene and benzene were detected in small quantities.

A phenomenological or empirical model based on experimental results obtained from various optical measurements is critical for the understanding of DI diesel combustion phenomena as well as for the improvement of its emission characteristics. Such a model could be realized by the application of advanced optical measurement, which is able to isolate a particular phenomenon amongst complicated physical and chemical interactions, to a DI diesel combustion field. The authors have conducted experimental studies to clarify the combustion characteristics of unsteady turbulent diffusion flames in relation to the soot formation and oxidation process in a small-sized DI diesel engine. In the present study, the effect of fuel vapor concentration on the process of early combustion and soot formation has been investigated using several optical measurements.

Experimental investigations relating to the use of producer gas in a spark ignition engine are reported in the proposed paper. The experimental setup consists of a single cylinder diesel engine converted to operate on a spark ignition engine mode coupled to a swinging field electrical dynamometer. A downdraft closed top charcoal gasifier has been used to generate the producer gas. After cooling and cleaning, it is fed to a venturi type gas carburetor, which ensures proper mixing of gas and air before it enters the engine. Testing of the converted engine was carried out under gasoline mode at a specified compression ratio. However subsequent tests on producer gas operation were performed at different compression ratios. The significant outcome of the present investigations include the satisfactory conversion of diesel engine to a spark ignition mode for neat producer gas operation and satisfactory operation of gas carburetor designed and developed for the purpose.

High demands in fuel consumption, efficiency, and low emissions lead to complex control functions for current and future diesel engine management systems. Great effort is necessary for their optimal calibration. At the same time, and particularly for cost reasons, many variants exist on one individual type of diesel engine management system. Not only is it used for several base engines, but these engines are also used in different environments and for different tasks. For optimal deployment, their calibration status must also be optimized individually. Furthermore, the demand for shorter development cycles and enhanced quality lead to a catalogue of new requirements for the calibration process and the affiliated tool. A new calibration system was developed, which optimally reflects the new demands.

The non-uniform character of the torque produced by a reciprocating I.C. engine is reflected in the cyclic variation of the crankshaft's speed. Because the crankshaft is an elastic structure, its response to the different harmonic components of the torque is different and changes with engine speed. The lowest harmonic components of the engine torque do not excite torsional vibrations and correlate fairly well with the corresponding harmonic orders of the crankshaft's speed. Based on a random vector model of the harmonic components of the gas-pressure torque, a statistical correlation is obtained between amplitudes and phases of the same harmonic component of the gas-pressure torque and of the crankshaft's speed. The lowest major harmonic order determines the average IMEP of the engine and the half-order detects if a cylinder is a lesser contributor to the total engine output and identifies the deficient cylinder.