Search Results

Increasingly stringent tailpipe emissions regulations have prompted renewed interest in catalyst heating technology – where an integrated device supplies supplemental heat to accelerate catalyst ‘light-off’. Bosch and Boysen, following a collaborative multi-year effort, have developed a Rapid Catalyst Heating System (RCH) for gasoline-fueled applications. The RCH system provides upwards of 25 kW of thermal power, greatly enhancing catalyst performance and robustness. Additional benefits include reduction of precious metal loading (versus a ‘PGM-only’ approach) and avoidance of near-engine catalyst placement (limiting the need for enrichment strategies). The following paper provides a technical overview of the Bosch/Boysen (BOB) Rapid Catalyst Heating system – including a detailed review of the system’s architecture, key performance characteristics, and the associated impact on vehicle-level emissions.

Under the proposed Green Deal program, the European Union will aim to achieve zero net greenhouse gas (GHG) emissions by 2050. The interim target is to reduce GHG by 55% by 2030. In the current debate concerning CO2-neutral powertrains, bio-fuels and e-fuels could play an immediate and practical role in reducing lifecycle engine emissions. Hydrogen however, is one of the few practical fuels that can result in near zero CO2 emissions at the tailpipe, which is the main focus of current legislation. Compared to gasoline, hydrogen presents a higher laminar flame speed, a wider range of flammability and higher auto-ignition temperatures, making it among the most attractive of fuels for future engines. As a challenge, hydrogen requires a very low ignition energy. This may imply an increased susceptibility to Low Speed Pre-Ignition (LSPI), surface ignition and back-fire phenomena. In order to exploit hydrogen’s potential, the injection system plays an extremely important role.

Historically, whenever the automotive solutions’ state of art reaches a saturation level, the integration of new verticals of technology has always raised new opportunities to innovate, enhance and optimize automotive solutions. The predictive powertrain solutions using connectivity elements (e.g., navigation unit, e-Horizon or cloud-based services) are one of such areas of huge interest in automotive industry. The prior knowledge of trip destination and its route characteristics has potential to make prediction of powertrain modes or events in certain order and therefore it can add value in various application areas such as optimized energy management, lower fuel consumption, superior safety and comfort, etc.

For electric vehicles the ability for regenerative braking reduces the use of friction brakes. Particularly on the rear axle of vehicles with reduced dynamic requirements such as urban vehicles, this can offer a potential for downsizing or, in extreme cases, even the elimination of the friction brakes on the rear axle. Due to the fact that the rear axle service brakes also represent the typical parking brake location in SoA (State-of-Art) vehicles, a rigorous rethinking of the parking brake concept is necessary to incorporate safe vehicle standstill management for such novel brake system topology. This research study introduces a novel parking brake design that covers SoA but also legal requirements while retaining potentials associated with the elimination of the rear service brakes such as cost and packaging.

In order to optimize spray layouts of commonly used high-pressure injectors for gasoline direct injection (GDI) engines featuring multi-hole valve seats, a detailed understanding of the cause-effect relation between inner spray hole geometries and inner flow conditions, initializing the process of internal mixture formation, is needed. Therefore, a novel measurement setup, capable of determining spray hole individual mass flow rates, is introduced and discussed. To prove its feasibility, a 2-hole configuration is chosen. The injected fuel quantities are separated mechanically and guided to separate pressure tight measurement chambers. Each measurement chamber allows for time resolved mass flow rate measurements based on the HDA measurement principle (German: “Hydraulisches Druck-Anstiegsverfahren”).

India has one of the highest growth rates of individual mobility in the world, as well as one of the largest numbers of road casualties. Modern active safety systems are slowly becoming established in the Indian passenger car market. The intension of this study is to investigate the effectiveness of the car safety feature Electronic Stability Control (ESC) for India. The Indian accidents has to be analysed to identify the reliable root cause. For this purpose, passenger car Loss of Control accidents were investigated in more detail with the aim of estimating the safety potential of ESC for India. A methodology is developed to extrapolate the in-depth accident database of Road Accident Sampling System for India (RASSI) to the entire accident situation in India. Loss of Control accidents are analysed with regard to their root causes, crash consequences and contributing factors.

Future emission norms in India (BS6) necessitates the 2 wheeler industry to work towards emission optimization measures. Engine operation at stoichiometric Air-Fuel Ratio (AFR) would result in a good performance, durability and least emissions. To keep the AFR close to stoichiometric condition, an Oxygen sensor is placed in the exhaust system, which detects if air-fuel mixture is rich (λ<1) or lean (λ>1) and provides feedback to fuel injection system for suitable fuel control. O2 sensor has a ceramic element, which needs to be heated to a working temperature for its functioning. The ceramic element would break (thermal shock) if water in liquid form comes in contact with it when the element is hot.

Particulate emissions from Gasoline Direct Injection (GDI) engines have been an important topic of recent research interest due to their known environmental effects. This review paper will characterise the influence of different gasoline direct injection fuel systems on particle number (PN) emissions. The findings will be reviewed for engine and vehicle measurements with appropriate driving cycles (especially real driving cycles) to evaluate effects of the fuel injection systems on PN emissions. Recent technological developments alongside the trends of the influence of system pressure and nozzle design on injector tip wetting and deposits will be considered. Besides the engine and fuel system it is known that fuel composition will have an important effect on GDI engine PN emissions. The evaporation qualities of fuels have a substantial influence on mixture preparation, as does the composition of the fuel itself.

The success of model-based ECU-functions relies on precise and efficient modeling of the behavior of combustion engines. Due to the limited computing power, usually a combination of physical models and calibration parameters is preferred for engine modeling in ECU. The parameters can be scalars, 1 or 2-dimensional empirical models, such as look-up table for volumetric efficiency and effective area of the exhaust gas recirculation (EGR). A novel algorithm is proposed to automatically calibrate the look-up tables characterizing stationary functional relationships in ECU-function of the air system of a diesel engine with minimum calibration cost. The algorithm runs in the framework of online design of experiment (DoE), in which Gaussian process model (GPM) is adopted to approximate the relationships of interest.

A major source for soot particle formation in Gasoline-Direct-Injection (GDI) engines are fuel-rich zones near walls as a result of wall wetting during injection. To address this problem, a thorough understanding of the wall film formation and evaporation processes is necessary. The wall temperature before, during and after fuel impingement is an important parameter in this respect, but is not easily measured using conventional methods. In this work, a recently developed laser-based phosphor thermography technique is implemented for investigations of spray-induced surface cooling. This spatially and temporally resolved method can provide surface temperature measurements on the wetted side of the surface without being affected by the fuel-film. Zinc oxide (ZnO) particles, dispersed in a chemical binder, were deposited onto a thin steel plate obtaining a coating thickness of 17 μm after annealing.

The fuel spray behavior in the near nozzle region of a gasoline injector is challenging to predict due to existing pressure gradients and turbulences of the internal flow and in-nozzle cavitation. Therefore, statistical parameters for spray characterization through experiments must be considered. The characterization of spray velocity fields in the near-nozzle region is of particular importance as the velocity information is crucial in understanding the hydrodynamic processes which take place further downstream during fuel atomization and mixture formation. This knowledge is needed in order to optimize injector nozzles for future requirements. In this study, the results of three experimental approaches for determination of spray velocity in the near-nozzle region are presented. Two different injector nozzle types were measured through high-speed shadowgraph imaging, Laser Doppler Anemometry (LDA) and X-ray imaging.

The ongoing changes in the development of new power trains and the requirements due to driver assistance systems and autonomous driving could be the enabler for completely new brake system configurations. The shift in the brake load collective has to be included in the systems requirements for electric vehicles. Many alternative concepts for hydraulic brake systems, even for decentralized configurations, can be found in the literature. For a decentralized system with all state of the art safety functionalities included, four actuators are necessary. Therefore, the single brake module should be as cost-effective as possible. Previous papers introduced systems which are for example based on plunger-like concepts, which are very expensive and heavy due to the needed gearing and design. In this paper a comparison between a state of the art hydraulic brake system using an electromechanical brake booster, and a completely new decentralized hydraulic brake concept is presented.

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.

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.

The introduction of stricter emission legislation and the demand of increased power for small two-wheelers lead to an increase of technical requirements. Especially the introduction of liquid-cooling over air-cooling allows the introduction of higher compression ratios, which improves power output as well as thermodynamic efficiencies and thereby fuel consumption. But an increase in compression ratio also introduces further challenges during transient behavior especially close to idling. In order to keep the two-wheeler specific responsiveness of the vehicle, the overall rotational inertia of the engine must be kept low. But the combination of low inertia and high compression ratio can lead to a stalling of the engine if the throttle is opened and closed very quickly in idle operation. The fast opening and closing of the throttle is called a throttle blip.

Engine management systems combined with fuel injectors allow a precise fuel metering for a robust combustion process. Stricter emission legislations increase the requirements for these port fuel injection systems (PFI), whereas the price is still the main driver in the emerging low cost 2-wheeler market. Therefore, a holistic mechatronic approach is developed by Bosch, which allows an improved fuel metering over life time and furthermore provides new possibilities for diagnosis without changing the injector itself. This example of an intelligent software solution provides the possibility to further improve the accuracy of the fuel metering of an injector. By use of the information contained in the actuation voltage and current, the opening and closing times of the injector are derivable.

To satisfy future emission classes, e.g. EU6c, the particulate number (PN) of Direct-Injection Spark-Ignition (DISI) engines must be reduced. For these engines, different components influence the combustion process and thus also the formation of soot particles and deposits. Along with other engine components, the injector nozzle influences the particulate number and deposits in both fuel spray behavior and nozzle “tip wetting”. In case of non-optimized nozzle layouts, fuel may impinge on the piston and the liner in an unfavorable way, which implies low-oxygen diffusive combustion by retarded vaporizing wall films. For the tip wetting, wall films are present on the actual surface of the nozzle tip, which is also caused by unadapted nozzles. For non-optimized nozzles, the latter effect can become quite dominant. This paper deals with systematic nozzle development activities towards low-deposit nozzle tips and thus decreasing PN values.

New technologies like alternative power trains and driver assistance systems have a big impact on brake system development. Most of the development work aims at the improvement of the actuation and modulation components of the brake system. The basic hydraulic network remained nearly the same over decades and still has to meet these new requirements. Previous papers have focused mainly on studying the behavior of single components, like for example the brake hose fluid consumption in detail. Other papers studied the complete system but simplified it extremely, so that some relevant effects are neglected. In this work, one focus is to study the influence of single relevant components, like the hydraulic unit and the hoses on the overall system performance. For this measurements with a complete hydraulic brake system, including a state of the art electromechanical brake booster and single component measurements for identification, are conducted.

Anti-lock Braking Systems (ABS) for motorcycles have already contributed significantly to the safety of powered two-wheelers (PTW) on public roads by improving bike stability and controllability in emergency braking situations. In order to address further riding situations, another step forward has been achieved with Motorcycle Stability Control (MSC) system. By combining ABS, electronically combined braking system (eCBS), traction control and inertial sensors even in situations like braking and accelerating in corners the riders' safety can be improved. The MSC system controls the distribution of braking and traction forces using an algorithm that takes into account all available vehicle information from wheels, power train and vehicle attitude. With its ability to control fundamental vehicle dynamics, the MSC system will be a basis for further development and integration of comprehensive safety systems.

In the Indian two-wheeler market, legislation and customers demand for a reduction of emissions and an increase of fuel efficiency. For two-wheelers with engine management systems, a cost-efficient approach for this trend exploits that the periodical fluctuation of the engine speed of single cylinder engines contains useful information about its operating conditions. The present article focuses on the quality of the estimation of combustion phasing and air-fuel ratio of a 125cc single cylinder motorcycle engine, obtained from the evaluation of these fluctuations. The robustness of an oxygen sensor-less port fuel injection system can be increased by using the estimated air-fuel ratio to adapt the parameters of the fuel injection algorithm.