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Catalyzed Particulate Filter Passive Oxidation Study with ULSD and Biodiesel Blended Fuel

2012-06-18
A 2007 Cummins ISL 8.9L direct-injection common rail diesel engine rated at 272 kW (365 hp) was used to load the filter to 2.2 g/L and passively oxidize particulate matter (PM) within a 2007 OEM aftertreatment system consisting of a diesel oxidation catalyst (DOC) and catalyzed particulate filter (CPF). Having a better understanding of the passive NO2 oxidation kinetics of PM within the CPF allows for reducing the frequency of active regenerations (hydrocarbon injection) and the associated fuel penalties. Being able to model the passive oxidation of accumulated PM in the CPF is critical to creating accurate state estimation strategies. The MTU 1-D CPF model will be used to simulate data collected from this study to examine differences in the PM oxidation kinetics when soy methyl ester (SME) biodiesel is used as the source of fuel for the engine.
Technical Paper

The Effects of Natural Aging on Fleet and Durability Vehicle Engine Mounts from a Dynamic Characterization Perspective

2001-04-30
2001-01-1449
Elastomers are traditionally designed for use in applications that require specific mechanical properties. Unfortunately, these properties change with respect to many different variables including heat, light, fatigue, oxygen, ozone, and the catalytic effects of trace elements. When elastomeric mounts are designed for NVH use in vehicles, they are designed to isolate specific unwanted frequencies. As the elastomers age however, the desired elastomeric properties may have changed with time. This study looks at the variability seen in new vehicle engine mounts and how the dynamic properties change with respect to miles accumulated on fleet and durability test vehicles.
Technical Paper

Fuel Evaporation Parameter Identification during SI Cold Start

2001-03-05
2001-01-0552
The stochastic properties of continuous time model parameters obtained through discrete least squares estimation are examined. Particular attention is given to the application of estimating the fuel evaporation dynamics of a V-8 SI engine. The continuous time parameter distributions in this case are biased. The bias is shown to be a function of both measurement noise and sampling rate selection. Analysis and experimental results suggest that for each particular model, there is a corresponding optimum sampling rate. A bias compensation formula is proposed that improves the accuracy of least squares estimation without iterative techniques.
Technical Paper

A Cascade Atomization and Drop Breakup Model for the Simulation of High-Pressure Liquid Jets

2003-03-03
2003-01-1044
A further development of the ETAB atomization and drop breakup model for high pressure-driven liquid fuel jets, has been developed, tuned and validated. As in the ETAB model, this breakup model reflects a cascade of drop breakups, where the breakup criterion is determined by the Taylor drop oscillator and each breakup event resembles experimentally observed breakup mechanisms. A fragmented liquid core due to inner-nozzle disturbances is achieved by injecting large droplets subject to this breakup cascade. These large droplets are equipped with appropriate initial deformation velocities in order to obtain experimentally observed breakup lengths. In contrast to the ETAB model which consideres only the bag breakup or the stripping breakup mechanism, the new model has been extended to include the catastrophic breakup regime. In addition, a continuity condition on the breakup parameters has lead to the reduction of one model constant.
Technical Paper

Test Bench Results of a Torque Pedal Interpretation with a CVT-Equipped Power Train

1997-02-24
970293
This paper presents the implementation of a torque pedal interpretation scheme in the CVT-equipped hybrid car which is currently being developed at the Swiss Federal Institute of Technology (ETH) as project Hybrid III. At partial load, a duty cycle operation mode is used in order to increase fuel efficiency. A flywheel is used to store excess power of the combustion engine as well as when the speed of the vehicle is decreased, recuperating the energy for reacceleration. A third mode, called highway operation, is used whenever the demanded power at the wheel exceeds a certain limit. A hierarchical controller scheme is implemented to maintain a comparable behavior of the vehicle in all operation modes. Beyond simulations, this controller operates successfully under real time conditions on the dynamic test bench. Test cycles with a human driver have successfully proven the effectiveness of the chosen set of controllers.
Technical Paper

Model Identification for the A/F Path of an SI Engine

1997-02-24
970612
Modern model-based control schemes and their application on different engines need mathematical models for the various dynamic subsystems of interest. Here, the fuel path of an SI engine is investigated. When the engine speed and the throttle angle are kept constant, the fuel path is excited only by the fuel injected. Taking the NO concentration of the exhaust gas as a measure for the air/fuel ratio, models are derived for the wall-wetting dynamics, the gas mixture, as well as for the air/fuel ratio sensor. When only the spark advance is excited, the gas flow dynamics can be studied. A very fast NO measurement device is used as reference. Its time constant is below the segment time of one single cylinder (180° crank angle for a 4-cylinder engine), therefore its dynamics are much faster than the time constants of the systems investigated. A model structure considering the muliplexing effects of the discrete operation of an engine is given for the fuel path of a BMW 1.8 liter engine.
Technical Paper

On-Line Identification of Time Delay in the Fuel Path of an SI Engine

1997-02-24
970613
The dynamics of the fuel-path subsystem of an SI engine, between fuel injection command signal and measured air-to-fuel ratio, is modeled approximately by a series connection of a first-order low-pass filter and a time delay element. The three parameters involved in this approximation, i.e., the time constant and the gain factor of the low-pass filter as well as the time delay, depend on the operating point of the engine. In order to design a gain-scheduled controller for the entire operating range of the engine, the parameters are identified for a number of operating points. For the automation of the parameter identification of all operating points desired, an on-line identification based on the recursive least-squares method is used. The algorithm for the decision of whether to increase or decrease the integer part of the current estimated time delay, which is a multiple of the sampling period, is based on an estimation of the fractional part of the time delay at each point.
Technical Paper

A Study of the Vapor- and Particle-Phase Sulfur Species in the Heavy-Duty Diesel Engine EGR Cooler

1998-05-04
981423
To meet future NO, heavy-duty diesel emissions standards, exhaust gas recirculation (EGR) technology is likely to be used. To improve fuel economy and further lower emissions, the recirculated exhaust gas needs to be cooled, with the possibility that cooling of the exhaust gas may form sulfuric acid condensate in the EGR cooler. This corrosive condensate can cause EGR cooler failure and consequentially result in severe damage to the engine. Both a literature review and a preliminary experimental study were conducted. In this study, a manually controlled EGR system was installed on a 1995 Cummins Ml l-330E engine which was operated at EPA mode 9* (1800 rpm and 75% load). The Goksoyr-Ross method (1)** was used to measure the particle-phase sulfate and vapor-phase H2SO4 and SO2 at the inlet and outlet locations of the EGR cooler, obtaining H2SO4 and SO2 concentrations. About 0.5% of fuel sulfur in the EGR cooler was in the particle-phase.
Technical Paper

A New Model for Fuel Supply Dynamics in an SI Engine

1994-03-01
940208
In this paper we introduce an improved model for the fuel supply dynamics in an SI engine. First, we briefly investigate all the thermodynamic phenomena which are assumed to have a significant impact on fuel flow into the cylinder (i.e., fuel atomization, droplet decay, wall-wetting, film evaporation, and mixture flow back). This theoretical analysis results in a basic set of dynamic equations. Unfortunately, these equations are not convenient to use for control purposes. Therefore, we proceed to a simplified formulation. Several unknown parameters remain, describing phenomena which are difficult to quantify, such as heat and material transfer characteristics. These parameters are subject to operating conditions and are not discussed further. In order to validate the model dynamics, we refer to frequency and step response measurements performed on a 4-cylinder, 1.8 liter BMW engine with sequential fuel injection.
Technical Paper

Measurement of the Wall-Wetting Dynamics of a Sequential Injection Spark Ignition Engine

1994-03-01
940447
In this paper the fuel path of a sequentially injected gasoline engine is discussed. Since a fraction of the injected fuel suffers a delay due to the wall-wetting phenomenon, in transient phases a significant deviation of the air-to-fuel ratio from its setpoint can arise. The amount of fuel on the manifold wall and its rate of evaporation cannot be measured directly. Therefore, the effects of the wall-wetting on exhaust lambda and engine torque have to be considered for the identification of the dynamics. The dynamics of the exhaust-gas-oxygen (EGO) sensor is not negligible for the interpretation of the lambda measurement. Since both the dynamics and the statics of a ZrO2 Sensor are very nonlinear, a normal EGO-sensor is not suitable for these investigations. On the other hand, the engine torque is a good measure for the cylinder lambda when all other effects which lead to torque changes can be eliminated.
Technical Paper

Model-Based Adaptive Fuel Control in an SI Engine

1994-03-01
940374
This paper introduces a model-based adaptive controller designed to compensate mixture ratio dynamics in an SI engine. In the basic model the combined dynamics of wall-wetting and oxygen sensor have to be considered because the only information about process dynamics originates from measuring exhaust λ. The controller design is based on the principles of indirect Model Reference Adaptive Control (MRAC). The indirect approach connotes that explicit identification of the system parameters is required for the determination of the controller parameters. Due to nonlinearities and delays inherent in the process dynamics, an adaptive extended Kalman filter is used for identification purposes. The Kalman filter method has already been described in detail within an earlier paper [1]. It proves to be ideally suited to deal with nonlinear identification problems. The estimated parameters are further used to tune an adaptive observer for wall-wetting dynamics.
Technical Paper

Reynolds Stress Components in the Flow Field of a Motored Reciprocating Engine

1995-02-01
950725
Coincident 3-D velocity measurements have been made in a single-cylinder, motored research engine using a six-beam, three-wavelength LDV system. The engine had a pancake combustion chamber, a compression ratio of 8.0 and was operated with a fixed intake shroud valve position. Measurements have been performed at 600, 1000 and 1500 RPM and at three distinct locations within the combustion chamber. Software coincidence filtering and ensemble averaging have been thereby used for data processing.
Technical Paper

Differences in Pre- and Post-Converter Lambda Sensor Characteristics

1996-02-01
960335
The two characteristics of wide-range air/fuel ratio sensors when located in front of and behind a three-way catalytic converter are investigated. Input as well as output gas concentration measurements and sensor readouts are presented. Behind a new converter almost no oxygen can be measured for rich air/fuel ratios. The wide-range sensor's signal is sensitive to changes in the gas composition when keeping the air/fuel ratio constant at a rich value. Since the gas compositions up- and down-stream of the converter differ, the sensor signals are not identical for the same rich air/fuel ratio before and after the converter. The various diffusion coefficients of the exhaust gas species flowing through the porous coating of the sensor combinded with the different up- and downstream gas compositions are responsible for the different sensor characteristics.
Technical Paper

Wall-Wetting Parameters Over the Operating Region of a Sequential Fuel-Injected SI Engine

1998-02-23
980792
In modern engine control applications, there is a distinct trend towards model-based control schemes. There are various reasons for this trend: Physical models allow deeper insights compared to heuristic functions, controllers can be designed faster and more accurately, and the possibility of obtaining an automated application scheme for the final engine to be controlled is a significant advantage. Another reason is that if physical effects can be separated, higher order models can be applied for different subsystems. This is in contrast to heuristic functions where the determination of the various maps poses large problems and is thus only feasible for low order models. One of the most important parts of an engine management system is the air-to-fuel control. The catalytic converter requires the mean air-to-fuel ratio to be very accurate in order to reach its optimal conversion rate. Disturbances from the active carbon filter and other additional devices have to be compensated.
Technical Paper

On-Line Identification Scheme for Various Wall-Wetting Models

1998-02-23
980793
Modern engine management systems increasingly rely on on-line identification schemes. These are used either for self-tuning regulators or the rapid parametrization of controllers. In this paper the on-line parameter identification of the wall-wetting dynamics is studied in detail. The identification is performed by exciting the fuel path dynamics of the engine at a constant operating point. The amount of fuel injected serves as input and the air-to-fuel ratio, which is measured with a linear oxygen sensor, as output. In order to gain precise information about the amount of fuel in the cylinder, a new measurement concept is used. For one, the placement of the lambda sensor close to the exhaust valve minimizes the effects of gas mixing on the measurements. Additionally, by an appropriate collection of the data, the sensor dynamics are bypassed. This is also illustrated by a measurement with a very fast NOx sensor.
Technical Paper

A Comparison of Time-Averaged Piston Temperatures and Surface Heat Flux Between a Direct-Fuel Injected and Carbureted Two-Stroke Engine

1998-02-23
980763
Time-averaged temperatures at critical locations on the piston of a direct-fuel injected, two-stroke, 388 cm3, research engine were measured using an infrared telemetry device. The piston temperatures were compared to data [7] of a carbureted version of the two-stroke engine, that was operated at comparable conditions. All temperatures were obtained at wide open throttle, and varying engine speeds (2000-4500 rpm, at 500 rpm intervals). The temperatures were measured in a configuration that allowed for axial heat flux to be determined through the piston. The heat flux was compared to carbureted data [8] obtained using measured piston temperatures as boundary conditions for a computer model, and solving for the heat flux. The direct-fuel-injected piston temperatures and heat fluxes were significantly higher than the carbureted piston. On the exhaust side of the piston, the direct-fuel injected piston temperatures ranged from 33-73 °C higher than the conventional carbureted piston.
Technical Paper

Controlling a CVT-Equipped Hybrid Car

1995-02-01
950492
In order to achieve maximum fuel efficiency, the SI engine of the new CVT-equipped hybrid car developed at the Swiss Federal Institute of Technology (ETH) is operated in a high power regime (such as highway driving at speeds above 120 km/h) with its throttle in its 100-percent open position. Whenever an engine power which exceeds 11 kWs is demanded, there exists an equilibrium point between the engine torque and the torque induced by the drag. Any regulation of the vehicle speed has to be performed by altering the gear ratio of the CVT. If any acceleration is required, it is necessary to increase the engine speed. This requires that the vehicle has to be slowed down for a certain short period of time. If this characteristic behaviour of the car (which is typical for a non-minimum-phase system) is not accepted by a driver who demands and expects immediate acceleration, it might lead to critical situations.
Technical Paper

Fast NO Measuring Device for Internal Combustion Engines

1994-03-01
940962
A fast, versatile nitric oxide (NO) measuring device applying the principles of chemiluminescence has been developed. This device consists of a small sensor head attachable to the engine exhaust system and a mobile cart containing all the necessary auxiliary aggregates and the signal processing unit. Optimization techniques based on a physico-chemical model and strict miniaturization were applied in the development of this NO measuring device. Subsequent tests utilizing a, solenoid valve and bottled calibration gas con- firmed the predicted dynamic behavior of the instrument. This device now shows an extremely short sampling delay and a higher bandwidth than common NO measuring devices can offer.
Technical Paper

Turbulent Flow Field Characteristics in a Motored Reciprocating Engine

1997-10-01
972833
Coincident 3-d velocity measurements in the flat combustion chamber of a motored single cylinder engine have been performed using Laser-Doppler-Velocimetry. The 3-d LDV System consisted of three beampairs (514nm, 488nm and 476.5nm) and two fiberoptic probes operated in 90° cross-scatter mode obtaining high spatial and temporal resolution as well as high signal quality. Burst Spectrum Analyzers have been thereby used for signal processing. The time histories of the three velocity components have been acquired for moderate engine speeds (600, 1000 and 1500RPM). The swirling motion in the cylinder was also varied by choosing different fixed positions of a shrouded intake valve relative to the intake port. Several measuring locations in the combustion chamber have been studied in order to investigate homogeneity. Mean velocities and fluctuation intensities of the turbulent field were evaluated using ensemble averaging.
Technical Paper

A 2-D Computational Model Describing the Flow and Filtration Characteristics of a Ceramic Diesel Particulate Trap

1998-02-23
980545
A 2-D computational model was developed to describe the flow and filtration processes, in a honeycomb structured ceramic diesel particulate trap. This model describes the steady state trap loading, as well as the transient behavior of the flow and filtration processes. The theoretical model includes the effect of a copper fuel additive on trap loading and transient operation. The convective terms were based on a 2-D analytical flow field solution derived from the conservation of mass and momentum equations. The filtration theory incorporated in the time dependent numerical code included the diffusion, inertia, and direct interception mechanisms. Based on a measured upstream particle size distribution, using the filtration theory, the downstream particle size distribution was calculated. The theoretical filtration efficiency, based on particle size distribution, agreed very well (within 1%) with experimental data for a number of different cases.
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