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Technical Paper

Water Load Determination Approach in Two Wheeler Exhaust System

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.
Technical Paper

Variable Orifice Geometry Verified on the Two-Phase Nozzle (VRD)

Innovative solutions for reducing particulate emissions will be necessary in order to comply with the even more stringent exhaust-gas standards of the future. The potential of a diesel nozzle with variable orifice geometry has long been common knowledge in the area of engine construction. But up to now, a fully functional solution of such a nozzle has not appeared which operates with a reduced orifice at low engine speeds and/or low loads. Here with regard to target costing, the requirements implicit in function and manufacture must also be taken into account. Using calculations on nozzle interior flow and injection-spray investigations, it will be shown which nozzle geometries best fulfill the various requirements. In order to achieve low levels of particulate emission in an engine with a combustion chamber designed for optimum use of a hole-type nozzle, the injection-spray direction and its geometry must to a large extent correspond to those of a hole-type nozzle.
Technical Paper

Traction Control (ASR) Using Fuel-Injection Suppression - A Cost Effective Method of Engine-Torque Control

Traction control (ASR) is the logical ongoing development of the antilock braking system (ABS). Due to the high costs involved though, the widespread practice of reducing the engine power by electronic throttle control (or electronic enginepower control) has up to now prevented ASR from becoming as widely proliferated as ABS. A promising method has now been developed in which fuel-injection suppression at individual cylinders is used as a low-price actuator for a budget-priced ASR. First of all, an overview of the possibilities for influencing wheel-torque by means of intervention at the engine and/or brake as a means of reducing driven wheel slip is presented. Then, the system, the control strategy, and the demands on the electronic engine-management system with sequential fuel injection are discussed. The system's possibilities and its limitations are indicated, and fears of damaging effects on the catalytic converter are eliminated.
Technical Paper

The X-By-Wire Concept: Time-Triggered Information Exchange and Fail Silence Support by New System Services

This paper presents the conceptual model and the fundamental mechanisms for software development in the context of the Brite-EuRam project Safety Related Fault Tolerant Systems in Vehicles (nick-named X-By-Wire). The objective of the X-By-Wire project is to achieve a framework for the introduction of safety related fault tolerant electronic systems without mechanical backup in vehicles. To achieve the required level of fault-tolerance, an X-By-Wire system must be designed as a distributed system comprising a number of fault-tolerant units connected by a reliable real-time communication system. For the communication system, the time-triggered TTP/C real-time communication protocol was selected. TTP/C provides fault-tolerance message transfer, state synchronization, reliable detection of node failures, a global time base, and a distributed membership service. Redundancy is used for masking failures of individual processor nodes and hardware peripherals.
Technical Paper

The Robert Bosch In-Line Pump for Diesel Engines, Type MW, Design, Application and Further Development

The range of Robert Bosch in-line pumps is designed for engines with cylinder outputs of up to 200 kW. Within this family of pumps the MW pump is used in small IDI engines and medium-sized DI engines with cylinder outputs in the region of 30 kW. More stringent exhaust emission legislation and the need to ensure optimum fuel economy call for efficient fuel-injection systems for diesel engines. In both of its designs the new MW pump meets these more exacting requirements and forms the contribution of Robert Bosch GmbH toward developing advanced diesel engines.
Technical Paper

The New Common Rail Fuel System for the Duramax 6600 V8 Diesel Engine

The Bosch Common Rail Fuel Injection System with the new technologies developed for the Duramax 6600 engine offer numerous performance advantages including exhaust emissions control and noise. The layout of the fuel system components and electrical parts is specifically designed to control fuel injection characteristics. The new injector and nozzle technology was integrated to achieve the required system performance. The new 1600bar fuel pump is also a prerequisite for required system performance.
Technical Paper

The Influence of Hydro Grinding at VCO Nozzles on the Mixture Preparation in a DI Diesel Engine

The hydro grinding process can be used for valve covered orifice (VCO) nozzle production. A comprehensive numerical and experimental investigation was performed to determine the influence of hydro grinding (HG) at VCO nozzles on the mixture preparation in pressure charged high speed direct injection diesel engines. Samples of five hole VCO nozzles with defined grades of HG and different sprayhole diameters were selected to ensure a constant mass flow at a fixed feeding pressure for comparable engine tests. The simulation of the internal flow shows a more symmetrical velocity profile indicating less shear flow and lower turbulence intensities at the orifice with increased HG grade. From these results an enhanced atomization at further penetration depth and reduced atomization close to the nozzle could be expected. This was confirmed by measuring the spray momentum distribution and spray tip speed by mechanical and optical probes in high pressure vessels.
Technical Paper

The Development and Performance of the Compact SCR-Trap System: A 4-Way Diesel Emission Control System

The tightening of Heavy Duty Diesel (HDD) emissions legislation throughout the world is leading to the development of emission control devices to enable HDD engines to meet the new standards. NOx and Particulate Matter (PM) are the key pollutants which these emission control systems need to address. Diesel Particulate Filters (DPFs) are already in use in significant numbers to control PM emissions from HDD vehicles, and Selective Catalytic Reduction (SCR) is a very promising technology to control NOx emissions. This paper describes the development and performance of the Compact SCR-Trap system - a pollution control device comprising a DPF-based system (the Continuously Regenerating Trap system) upstream of an SCR system. The system has been designed to be as easy to package as possible, by minimising the total volume of the system and by incorporating the SCR catalysts on annular substrates placed around the outside of the DPF-based system.
Technical Paper

The Challenge of Precise Characterizing the Specific Large-Span Flows in Urea Dosing Systems for NOx Reduction

The reduction of nitrous oxides in the exhaust gases of internal combustion engines using a urea water solution is gaining more and more importance. While maintaining the future exhaust gas emission regulations, like the Euro 6 for passenger cars and the Euro 5 for commercial vehicles, urea dosing allows the engine management to be modified to improve fuel economy as well. The system manufacturer Robert Bosch has started early to develop the necessary dosing systems for the urea water solution. More than 300.000 Units have been delivered in 2007 for heavy duty applications. Typical dosing quantities for those systems are in the range of 0.01 l/h for passenger car systems and up to 10 l/h for commercial vehicles. During the first years of development and application of urea dosing systems, instantaneous flow measuring devices were used, which were not operating fully satisfactory.
Technical Paper

Solenoid-Valve Controlled Diesel Distributor Injection Pump

The electronically-governed diesel distributor injection pump, with the proven sleeve control of injection quantity, has been in production at Bosch since 1987. Long-term development resulted in a solenoid-valve controlled injection pump. The function and component assemblies, consisting of the injection pump, solenoid valve and control unit, provide an even more flexible injection system. Of particular advantage with this type of system are the high dynamics of the fuel quantity, matching of each individual injection and the exact pump-specific fuel quantity compensation at numerous map points. Further advantages are the selection of timing and fuel injection rate independent of each other, as well as the ability to provide the correct timing even at cranking speeds. The entire system, with emphasis on the injection pump and the solenoid valve, are described for IDI engines in this paper.
Technical Paper

Simulation Tool Chain for the Estimation of EMC Characteristics of ECU Modules

Electromagnetic Compatibility (EMC) requirements and the effort to fulfill them are increasing steadily in automotive applications. This paper demonstrates the usage of virtual prototyping to efficiently investigate the EMC behavior of a gasoline direct injection system. While the system worked functionally as designed, tests indicated that current and especially future client-specific EMC limits could not be met. The goal of this investigation was to identify and eliminate the cause of EMC emissions using a virtual software prototype including the controller ASIC, boost converter, pi filter, injection valves and wire harness. Applying virtual prototyping techniques it was possible to capture the motor control system in a simulation model which reproduced EMC measurements in the frequency ranges of interest.
Technical Paper

Secondary Air Injection with a New Developed Electrical Blower for Reduced Exhaust Emissions

Secondary air injection after cold start gives two effects for reduced exhaust emissions: An exothermic reaction at the hot exhaust valves occurs, which increases the temperature of the exhaust gas. It gives sufficient air to the catalyst during the cold start fuel enrichment that is necessary to prevent driveability problems. Handicaps for the wide use of air injection include space constraints, weight and price. An electrical air blower was choosen to best satisfy all these requirements. The development steps are described. The result is a three stage radialblower with extremly high revolutions of about 18000 rpm. The system configuration and the outcome are demonstrated on the new C-Class of Mercedes-Benz. The results show emission reductions higher than 50 %, while also satisfying the development goals of noise, volume, weight and cost requirements.
Journal Article

Procedure for Determining the Allowable Particle Contamination for Diesel Fuel Injection Equipment (FIE)

Increasing injection pressures together with Diesel fuel lubricated Common Rail pumps replacing oil lubricated systems demand a more sophisticated investigation of robustness and durability against particle contamination of fuel. The established way of requiring filtration efficiency levels per lab standard is not significant enough if we look at variable factors like vibration of the fuel filter and viscosity of the fuel. Because these and other factors tremendously influence filtration efficiency, future Diesel FIE cleanliness requirements will need to define an allowable contamination limit downstream of the filter. More precisely, this is not a scalar limit but a contamination collective that considers the varying vehicle filtration and operating environment. This paper describes a procedure for defining allowable contamination limits of the FIE components. The procedure includes sensitivity, robustness and “key life” tests.
Journal Article

Particulate Matter Sensor for On Board Diagnostics (OBD) of Diesel Particulate Filters (DPF)

The emissions legislation in the US and Europe introduces the need for the application of diesel particulate filters (DPF) in most diesel vehicles. In order to fulfill future OBD legislations, which include more stringent requirements on monitoring the functionality of those particulate filters, new sensors besides the differential pressure sensor are necessary. The new sensors need to directly detect the soot emission after DPF and withstand the harsh exhaust gas environment. Based on multi layer ceramic sensor technology, an exhaust gas sensor for particulate matter (EGS-PM) has been developed. The soot-particle-sensing element consists of two inter-digitated comb-like electrodes with an initially infinite electrical resistance. During the sensor operation, soot particles from the exhaust gas are collected onto the inter-digital electrodes and form conductive paths between the two electrode fingers leading to a drop of the electrical resistance.
Technical Paper

On the Evaluation Methods for Systematic Further Development of Direct-Injection Nozzles

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.
Technical Paper

Numerical and Experimental Studies on Mixture Formation with an Outward-Opening Nozzle in a SI Engine with CNG-DI

CNG direct injection is a promising technology to promote the acceptance of natural gas engines. Among the beneficial properties of CNG, like reduced pollutants and CO2 emissions, the direct injection contributes to a higher volumetric efficiency and thus to a better driveability, one of the most limiting drawbacks of today’s CNG vehicles. But such a combustion concept increases the demands on the injection system and mixture formation. Among other things it requires a much higher flow rate at low injection pressure. This can be only provided by an outward-opening nozzle due to its large cross-section. Nevertheless its hollow cone jet with a specific propagation behavior leads to an adverse fuel-air distribution especially at higher loads under scavenging conditions. This paper covers numerical and experimental analysis of CNG direct injection to understand its mixture formation.
Technical Paper

Numerical and Experimental Analysis of the Momentum and Heat Transfer in Exhaust Gas Sensors

Modern zirconia oxygen sensors are heated internally to achieve an optimal detection of the oxygen concentration in the exhaust gas and fast light off time. The temperature of the gas in the exhaust pipe varies in a wide range. The zirconia sensor is cooled by radiation and forced convection caused by cold exhaust gas. If the zirconia temperature falls, the oxygen detection capability of the sensor decreases. To minimize the cooling effects, protection tubes cover the zirconia sensor. However, this is in conflict with the aim to accelerate the dynamics of the lambda sensor. In this paper, the heat transfer at the surface of a heated planar zirconia sensor with two different double protection tubes of a Bosch oxygen sensor is examined in detail. The geometric configuration of the tubes forces different flow patterns in the inner protection tube around the zirconia sensor. The zirconia sensor is internally electrically heated by a platinum heater layer.
Technical Paper

Numerical and Experimental Analysis of the 3D Flow-Pattern in Exhaust Gas Sensors

In new exhaust system specifications such as single cylinder balancing, closed coupled catalyst systems, sensor locations close to the engine, turbo applications, fast light off situations and diesel engine applications the dynamic behavior of the lambda sensor becomes more important. This demands a detailed knowledge and modeling of the relevant parameters. In former analysis of exhaust gas sensors the main focus has been the electrochemical processes in the sensor. The influence of flow structure and protection tubes had lower priority. In this paper we present the numerical and experimental analysis of cold air flowing in a pipe including mounted exhaust sensors. Two double-protection tubes from the Robert Bosch GmbH have been examined named (a) and (b). The predicted results have been compared with values measured with Laser Doppler Anemometry (LDA). The flow pattern in the protection tube type (a) depends on the geometric configuration of the sensor element and the tubes.
Technical Paper

Investigation on Fluid Mechanics of the Regenerative Pump Used in Gasoline Injection Systems

In order to optimize the inner flow of the regenerative pump used in gasoline injection systems, we carry out experimental and numerical flow investigations. A qualitative analysis of spatial flow phenomena in selected regions of the pump is presented by employing the laser light sheet technique. Therefore, a tenfold enlarged water model is built up, where dynamic similarity with the original flow is achieved. The results of the flow analysis have led to improved geometries which are compared with the original design by measured pump characteristic curves. Furthermore, three-dimensional simulations of the fully developed turbulent flow using a finite-element method are presented. The flow with respect to the rotating impeller is calculated by solving the Reynolds equations in connection with the k-ε-turbulence model.
Technical Paper

Integration of Time Triggered CAN (TTCAN_TC)

Time Triggered CAN (TTCAN) is an extension of the well-known CAN protocol, introducing to CAN networks time triggered communication and a system wide global network time with high precision. Time Triggered CAN has been accepted as international standard ISOCD11898-4. The time triggered communication is built upon the unchanged standard CAN protocol. This allows a software implementation of the time triggered function of TTCAN, based on existing CAN ICs. The high precision global time however requires a hardware implementation. A hardware implementation also offers additional functions like time mark interrupts, a stopwatch, and a synchronization to external events, all independent of software latency times. The TTCAN testchip (TTCAN_TC) is a standalone TTCAN controller and has been produced as a solution to the hen/egg problem of hardware availability versus tool support and research.