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Technical Paper

Model Based Engine Speed Evaluation for Single-Cylinder Engine Control

In order to fulfil emission legislation and achieve good drivability of combustion-engine-powered vehicles, information about the air charge and feedback about the engine condition is necessary. In current systems, different sensors are used, e.g. the MAP (manifold air pressure) sensor and a lambda sensor. Aiming at reducing costs, efforts are being made to reduce the number of sensors while still retrieving the necessary information. Various engine speed based functions are state-of-the-art for automotive engines, e.g. for fuel-calibration, misfire-detection etc. Those functions evaluate the engine speed fluctuations during a working cycle induced by combustion. For multiple-cylinder engines, those influences are overlapping, therefore evaluation possibilities are limited. The work presented is based on the effect that at a single-cylinder engine, there is no overlap of combustion influences of various cylinders on the crankshaft.
Journal Article

Data Based Cylinder Pressure Modeling for Direct-injection Diesel Engines

In this article a new zero-dimensional model is presented for simulating the cylinder pressure in direct injection diesel engines. The model enables the representation of current combustion processes considering multiple injections, high exhaust gas recirculation rates, and turbocharging. In these methods solely cycle-resolved, scalar input variables from the electronic control unit in combination with empirical parameters are required for modeling. The latter are adapted automatically to different engines or modified applications using measured cylinder pressure traces. The verification based on measurements within the entire operating range from engines of different size and type proves the universal applicability and high accuracy of the proposed method.
Technical Paper

A New Datadriven Approach to Modeling the Combustion of a Diesel Engine in HCCI Mode

The contribution presents a new data driven modeling approach for diesel HCCI combustion. Input parameters of the combustion model are external actuating variables as for example the start of injection. The model incorporates experimental data of the engine in HCCI mode, in the standard diesel mode and in the transition region between both modes. New disclosed dependencies between characteristic values of the cylinder pressure and the fuel burn rate are used to linearize the combustion model for a given operating point. In this paper the validation of the combustion model is discussed based on dynamic measuring data of the urban part of the NEDC. Finally, the combustion model is integrated in a zero-dimensional diesel engine model.
Technical Paper

GDI: Interaction Between Mixture Preparation, Combustion System and Injector Performance

The development of future engine generations for Gasoline Direct Injection requires sophisticated combustion systems to reach reduced fuel consumption and future emission standards. The design process of these combustion systems has to be based on a fundamental knowledge of the interacting mixture preparation mechanisms. Beside the air motion inside the cylinder mixture preparation is mainly feeded by the fuel spray quality, injector performance respectively. The article therefore presents a fundamental analysis of the GDI mixture preparation and affords an insight into the injector development. Comprehensive experimental studies were performed in high pressure/temperature vessels using Phase Doppler Anemometry, Laser Induced Fluorescence and video techniques to define the significant fuel spray features for GDI. CFD-calculations were additionally applied to study the temporal behavior of the mixture preparation under injection parameter variation.
Technical Paper

IMEP-Estimation and In-Cylinder Pressure Reconstruction for Multicylinder SI-Engine by Combined Processing of Engine Speed and One Cylinder Pressure

In order to optimize the performance and emission of engines, advanced control and diagnostic systems require detailed feedback information about the combustion process. In this context, cost-effective solutions are of interest. The contribution describes a method for reconstructing cylinder-individual features of each combustion cycle by processing the instantaneous fluctuations of the engine speed and the in-cylinder pressure of one cylinder. Model-based torque estimation, analyzing both of the signals simultaneously, provides an accurate estimation of the mean indicated pressure. Using this method, a new algorithm for advanced misfire detection is presented. Furthermore, a new pressure model with a feasible number of parameters is proposed. It is combined with the torque estimation in order to reconstruct the unknown pressure traces of the cylinders not equipped with sensors.
Technical Paper

Ion Current Measurement in Diesel Engines

Contemporary diesel engines are high-tech power plants that provide high torques at very good levels of efficiency. By means of modern injecting-systems such as Common-Rail Injection, combustion noise and emissions could be influenced positively as well. Diesel engine are therefore used increasingly in top-range and sports cars. Today's production ECUs have no or only very low feedback regarding the process in the combustion chamber. As long as this data is missing, the design of the maps in the ECU can only be a compromise, since production tolerances and aging processes have to be considered in advance. Disturbances in the combustion process may not be detected at all. If more knowledge about the course of combustion is provided, especially the start of combustion (SOC), various operating parameters, such as the pilot injection quantity or the beginning of current feed to the injector, could be adjusted more precisely and individually for every cylinder.
Technical Paper

Time Resolved Spray Characterisation in a Common Rail Direct-Injection Production Type Diesel Engine Using Combined Mie/LIF Laser Diagnostics

This study reports on laser-based diagnostics to temporally track the evolution of liquid and gaseous fuel in the cylinder of a direct injection production type Diesel engine. A two-dimensional Mie scattering technique is used to record the liquid phase and planar laser-induced fluorescence of Diesel is used to track both liquid and vaporised fuel. LIF-Signal is visible in liquid and gas phase, Mie scattering occurs only in zones where fuel droplets are present. Distinction between liquid and gaseous phase becomes therefore possible by comparing LIF- and Mie-Signals. Although the information is qualitative in nature, trends of spray evolution are accessible. Within this study a parametric variation of injection pressure, in-cylinder conditions such as gas temperature and pressure as well as piston geometry are discussed. Observations are used to identify the most sensitive parameters and to qualitatively describe the temporal evolution of the spray for real engine conditions.
Technical Paper

In-Cylinder Pressure Estimation from Structure-Borne Sound

We propose a novel method to real-time in-cylinder pressure estimation by processing structure-borne sound measurements. It has been shown that knowledge of the in-cylinder pressure opens the door to robust misfire detection and sophisticated closed loop engine control schemes. However, the costs of such sensors have inhibited their use in production engines. On the other hand, acceleration sensors are of low cost and already mounted on modern production engines for knock detection. Since structure-borne sound is measured on the surface of the engine, all cylinders are simultaneously observed by one sensor. A simple physically based model, describing the speed dependence of the transfer behavior from each in-cylinder pressure to structure-borne sound is developed. Based on this model, a method for identifying the parameterized transfer function speed independently is developed.
Technical Paper

A New MOTRONIC System with 16 Bit Micro Controller

The functionality of engine management systems has grown rapidly over the last few years. The paper presents a new Motronic concept, the engine management control M3. The Motronic family M3 is a modular design destined to control engines with up to eight cylinders individually. The main features of this system and the ECU's concept are discussed.
Technical Paper

Advanced Engine Misfire Detection for SI-Engines

This paper presents a system concept for detecting combustion misfire. The relevant research grew out of the more stringent requirements for On-Board Diagnostic systems (OBDII) mandated by the California Air Resources Board (CARB), effective as of model year 1997 onward. The system concept is based on evaluation of variations in crankshaft speed. Processes using engine roughness are applied in non-critical operating areas and/or on engines with a small number of cylinders. The modulation process is used in more critical areas. Research was done using a 12-cylinder engine and indicated the potential to comply with the California Air Resources Board's regulations for the model year (MY) 1997 and later.
Technical Paper

Common Rail Injection System for Commercial Diesel Vehicles

Common Rail provides additional flexibility for the design and application of a diesel injection system. Contrary to conventional injection systems pressure generation and injection are decoupled in the common rail system. The injection pressure can be selected independent of engine speed and injected fuel quantity within certain limits. The fuel combustion and the corresponding noise can be improved by increasing the fuel pressure up to 1400 bar and introducing pilot injection or multiple injection. Furthermore the common rail system can replace conventional injection systems without requiring major engine modifications. BOSCH will provide this new injection system for the whole range of applications from light duty (30 kW per cylinder) to heavy duty vehicles (50 kW per cylinder).
Technical Paper

Yaw Rate Sensor for Vehicle Dynamics Control System

From the beginning of 1995 on, RB will start the production of the Vehicle Dynamics Control System. A key part of this system is the Yaw Rate Sensor described in this paper. The basic requirements for this sensor for automotive applications are: mass producibility, low cost, resistance against environmental influences (such as temperature, vibrations, EMI), stability of all characteristics over life time, high reliability and designed-in safety. Bosch developed a sensor on the basis of the “Vibrating Cylinder”. The sensor will be introduced into mass production in beginning of 1995.
Technical Paper

Pressure Modulation in Separate and Integrated Antiskid Systems with Regard to Safety

The antiskid systems which have been on the market for some time are characterized by the fact that they are separate from the brake power-assist unit and are positioned between the master cylinder and the wheel brakes (separate configuration). At present, integrated antiskid systems are also being prepared for launching on the market. In these systems the hydraulic brake power-assist unit performs the functions of brake boosting and partly also of ABS pressure modulation. The principles of ABS pressure modulation in separate and integrated antiskid systems are compared and questions concerning safety are discussed. With the separate ABS (plunger system, return system) the brake circuits are closed, i.e. when braking and also during ABS operation the volume of brake fluid between the master cylinders and the wheel brake cylinders is closed and separated from the energy supply of the hydraulic brake power-assist unit.
Technical Paper

The Impact of a Combustion Chamber Optimization on the Mixture Formation and Combustion in a CNG-DI Engine in Stratified Operation

A previous study by the authors has shown an efficiency benefit of up to Δηi = 10 % for stratified operation of a high pressure natural gas direct injection (DI) spark ignition (SI) engine compared to the homogeneous stoichiometric operation with port fuel injection (PFI). While best efficiencies appeared at extremely lean operation at λ = 3.2, minimum HC emissions were found at λ = 2. The increasing HC emissions and narrow ignition time frames in the extremely lean stratified operation have given the need for a detailed analysis. To further investigate the mixture formation and flame propagation und these conditions, an optically accessible single-cylinder engine was used. The mixture formation and the flame luminosity have been investigated in two perpendicular planes inside the combustion chamber.
Technical Paper

Impact of the Injection and Gas Exchange on the Particle Emission of a Spark Ignited Engine with Port Fuel Injection

This study presents a methodology to predict particle number (PN) generation on a naturally aspirated 4-cylinder gasoline engine with port fuel injection (PFI) from wall wetting, employing numerical CFD simulation and fuel film analysis. Various engine parameters concerning spray pattern, injection timing, intake valve timing, as well as engine load/speed were varied and their impact on wall film and PN was evaluated. The engine, which was driven at wide open throttle (WOT), was equipped with soot particle sampling technology and optical access to the combustion chamber of cylinder 1 in order to visualise non-premixed combustion. High-speed imaging revealed a notable presence of diffusion flames, which were typically initiated between the valve seats and cylinder head. Their size was found to match qualitatively with particulate number measurements. A validated CFD model was employed to simulate spray propagation, film transport and droplet impingement.