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Particulates are among the most harmful emission components of internal combustion engines (ICE)). Thus, emission limits have been widely introduced, e.g., for light- and heavy-duty vehicles. Although there are still engine applications without particulate limitations, the measurement of particulate mass (PM) and particulate number (PN) emissions is therefore of special interest for the development and operation of ICE. For this purpose, a measurement system for PN consisting of a custom-built sample conditioning and dilution system, and a TSI 3790-A10 [1] condensation particle counter (CPC) as particle number counter (PNC) was designed and built. In this work, we present the conditioning and dilution system, the operational parameters, and results from the particle concentration reduction factor (PCRF) calibration.

This paper presents the results and conclusions from a conceptual design study for a stratified charging concept. The stratified charging engine has a displacement of 64 cm3 and a four-port design with reed valves at two ports to control the bypass air. During the intake stroke of the engine, bypass air is sucked into the transfer ports to purge the air-fuel mixture present in the ports from the previous stroke back into the crankcase. This fills the transfer ports near the exhaust with pure air at the beginning of the scavenging stroke. During scavenging, the bypass air is ejected in the cylinder, shielding the exhaust against the fresh mixture coming from the ports on the intake side. This allows the hydrocarbon emissions to be reduced by over 40 %. The conceptual design study is based on an analysis of the mixture short-circuiting mechanisms and CFD investigations of the scavenging flow with charge stratification.

The hybrid-electric drivetrain permits a multitude of new control strategies like brake energy recuperation, engine start-stop operation, shifting of engine working point, as well as in some situations pure electric driving. Overall this typically allows a reduction of fuel consumption and therefore of carbon dioxide emissions. During the development process of the vehicle various drivetrain configurations have to be considered and compared. This includes decisions regarding the topology - like the position of the electrical machine in the drivetrain (e.g. at the gearbox input or output shaft), as well as the selection of the needed components based on their parameters (nominal power, energy content of the battery, efficiency etc.). To compare the chosen variants, typically the calculated fuel consumption for a given driving cycle is used.

This publication covers investigations on different 3D CFD models for the description of the spray wall and droplet-fluid interaction and the influence of these models on the mixture formation calculation results. Basic experimental investigations in a spray chamber and a flow tunnel as well as the corresponding 3D CFD simulation were conducted in order to clarify the prediction quality of the physical phenomena of spray-wall and spray-fluid interaction by the simulation. Influencing parameters such as the piston top temperature, piston bowl geometry, soot deposits on the piston top as well as flow velocity are investigated. This paper provides a direct link between the underlying simulation models of the mixture formation and actual real world combustion system development processes - underlining the importance of a close interaction of the model calibration and the development process.

To achieve low emission levels, the handicap of the TWC is its light-off characteristic. It achieves a maximum hot efficiency of nearly 100 %, but this requires a temperature in the range of 300 to 450 °C. To improve this time lag after cold start, the TWC needs additional help to reach the targets of future low (LEV) or ultra low emission (ULEV) levels. This paper describes the work on additional devices to reach the ULEV-levels such as: Electrical Heated Catalyst (EHC). Burner Heated Catalyst (BHC) Hydrocarbon Trap (HCT) as external device. Adsorber Coated Substrate (ACS) in the usual converter box. The comparison of these systems was done with a concept car. The low mileage exhaust results demonstrated the principal suitability of all these devices, but there is still much work to be done to meet the ULEV levels with the guaranted durability. The advantages and disadvantages of the systems are discussed, including estimated weight and cost.

Legislative regulations and international agreements like the Paris Agreement have been prepared to enforce the effort to reduce the emission of greenhouse gases (GHGs). Greater environmental awareness among customers and introduction of strict environmental regulations have challenged designers to consider the environmental impact of products together with traditional design objectives in the early stages of product design. An important environmental impact factor is the carbon footprint of a product because carbon dioxide (CO2) emissions are a main cause of the global climate change. An early assessment of the product carbon footprint is beneficial because at this stage, design changes are still possible with little effort and at low cost. Actually, there is no detailed methodology for a CO2 impact estimation in the early design phases available and very few researches have been conducted for the special segment of small powertrains.

Professional users in particular will continue to rely on internal combustion engine drives in the future due to high power requirements and high daily energy consumption. Especially if they have to work in rural areas without the possibility of recharging batteries, such as in forestry or maintenance of road verges or railway lines. For these applications, it must be possible to run sustainable fuels for defossilization and drastically reduced CO2 emissions. This paper provides insights into a possible future fuel market and describes its evolution towards a more sustainable future from the perspective of a handheld equipment manufacturer. As developments in the fuel market are currently difficult to predict, manufacturers of hand-held power tools with combustion engines need to be prepared for changes in the composition of fuels that might become available on the market.

The objective of this experimental investigation was to analyze the effect of various exhaust gas aftertreatment technologies on particulate number emissions (PN) of an MPFI EU5 motorcycle. Specifically, three different aftertreatment strategies were compared, including a three-way-catalyst (TWC) with LS structure as the baseline, a hybrid catalyst with a wire mesh filter, and an optimized gasoline particulate filter (GPF) with three-way catalytic coating. Experimental investigations using the standard test cycle WMTC performed on a two-wheeler chassis dynamometer, while the inhouse particulate sampling system was utilized to gather information about size-dependent filtering efficiency, storage, and combustion of nanoparticles. The particulate sampling and measuring system consist of three condensation particle counters (CPCs) calibrated to three different size classes (SPN4, SPN10, SPN23).

This paper describes the exhaust emission control system designed for the new Mercedes-Benz sports car generation 300 SL and 500 SL, Remarkable features of the catalytic converters are maximum environmental compatibility, i. e. minimum of emission and noise under all driving conditions. By reduced back-pressure, they also contribute greatly to the well known requirements of a sports car: high performance and high torque over the entire engine-speed-range. Apart from an effective exhaust gas aftertreatment, great efforts were made to prevent the formation of pollutants under all driving conditions. This work is done by intelligent motor management consisting of digital spark control, mechanical-electronic injection, variable valve timing and EGR.

Today mankind is using highly sophisticated tools which contribute to maintain the standard of living. Nevertheless, these tools have to be further improved in the near future in order to protect health and environment as well as to ensure prosperity. Two-stroke engines equipped with a carburettor are the most used propulsion technology in hand-held power tools like chain saws and grass trimmers. The shortage of fossil resources and the necessary reduction of carbon dioxide emissions ask for improved engine efficiency. Concurrently, customers demand for an easy usage with high performance at all operating conditions, e.g. varying ambient temperature and pressure and different fuels. Moreover, world-wide emission limits will be even stricter in future. The improvement of the emission level, fuel consumption and customer benefits, while keeping the present advantages of two-stroke engines, like high specific power and simplicity, are the goals of this research work.

One possible path to reduce the CO2 emissions of hand-held power tools are fuels with different amount of renewable content. Within this paper test bench measurements on a small two-stroke engine were carried out. We are trying to reduce CO2 emissions by using fuels which absorbed CO2 from the air during its lifetime or production, so called Zero CO2 fuels The focus was set on the investigation of combustion behaviour, performance and emissions of Zero CO2 fuels in comparison to commonly available fuels. For our measurements we chose a 46 cc serial engine, which was slightly modified for scientific research. This paper shows findings on effects of renewable fuels on engine characteristics. Additionally, the chemical properties of each fuel were investigated in order to form a comprehensive picture, together with the performed dyno measurements.

As alternative to electrification or carbon free fuels such as hydrogen, CO2-neutral fuels have been researched aiming to decrease the impact of fossil energy sources on the environment. Despite the potential benefit of capturing CO2 emission after combustion for own fuel production, the so-called eFuels also benefit by using a green source of energy during their fabrication. Among all the possibilities for eFuels, alcohols, ethers (such as MTBE and ETBE) and alternative hydrocarbons have shown positive impacts regarding emission reduction and performance when compared to standard gasoline. Previously in [1] and [2], synthetic fuels and methanol blends were tested at steady state conditions in order to verify advantages and drawbacks relative to gasoline, for power-sport motorcycles.

Aiming to investigate the influence of methanol blends on the combustion process of a PFI four-stroke boxer engine, four mixtures of pure methanol and oxygen-free gasoline (M0) are prepared. The fuels tested are labelled by M15, M25, M35 and M50, where the number represents the percentual in volume of methanol within the mixture. In order to establish a base for comparisons, standard gas-station gasoline (S95) is also tested. Backwards compatibility is evaluated through test-bed measurements, when the engine operates without any modifications in the ECU. Over the whole operational area of the engine map, M15 and M25 can be used in the motorcycle application. Raw emissions of THC, CO2, CO and NOx decrease with the increase of methanol for almost all the conditions tested. It is observed that knock resistance is higher for higher methanol contents. At WOT, power is increased with the methanol proportion, being M50 and M35 more powerful than standard gasoline.

In the course of the last few years a continuous increase of the injection pressure level of gasoline direct injection systems appeared. Today's systems use an injection pressure up to 200bar and the trend shows a further increase for the future. Although several benefits go along with the increased injection pressure, the disadvantages such as higher system costs and higher energy demand lead to the question of the lowest acceptable injection pressure level for low cost GDI combustion systems. Lowering injection pressure and costs could enable the technological upgrading from MPFI to GDI in smaller engine segments, which would lead to a reduction of CO2 emission. This publication covers the investigation of a low pressure GDI system (LPDI) with focus on small and low cost GDI engines. The influence of the injection pressure on the fuel consumption and emission behavior was investigated using a 1.4l series production engine.

The main target for the development of power sport engines is and will be in future the increase of the power-to-weight ratio. However, the reduction of carbon dioxide emissions is getting more and more important as future legislation and increasing customer demands ask for lower fuel consumption. One possible technology for CO₂ reduction which is widely used in automotive applications is downsizing by reducing the engine capacity and increasing the specific power by charging strategies. Focusing on power sport applications, like motorcycles, the automotive downsizing technologies cannot be transferred without major modifications. The essential difference to automotive applications is the extraordinary response behavior of today's motorcycles, as well as the large engine speed spread. Additionally, packaging and cost reasons exclude the direct transfer of highly complex automotive technology, like two-stage charging, cam-phasing, etc., to motorcycle applications.

Following the recent trend in the automotive industry, hybrid and pure electric powertrain systems are more and more preferred over conventional combustion powertrain systems due to their significant potential to reduce greenhouse-gas emissions. Although electric powertrains do not produce direct emissions during their operational time, the indirect emissions over their whole life cycle have to be taken into consideration. In this direction, the carbon footprint due to the electrification of the hand-held power tool industry needs to be examined in the preliminary design phase. In this paper, after defining the carbon footprint calculation framework, assumptions and simplifications used for the calculations, a direct comparison of the total carbon dioxide equivalent (CO2eq) emissions of three equivalent power and range powertrain systems - a combustion-driven, a hybrid-driven, and a cordless electric-driven - is presented.

This paper reviews the current and new engine technologies that are suitable to be implemented in light-weight outdoor power equipment that is mostly powered by two-stroke engines. It gives insight in the concerns associated with the improvement of known technologies and highlights trends for future engine developments. Among others, the paper covers ways for the conventional scavenging improvement, catalyst development, low pressure mixture injection, direct fuel injection, stratified scavenging and also four-stroke technology. These concepts are assessed with respect to performance, cost, size and weight. Special emphasis is laid on the research and development of a catalyst concept for high-performance two-strokes and direct fuel injection. The catalyst is one of the easiest and most effective ways for emission reduction. However, measures have to be found to overcome the severe thermal difficulties.

Currently, emission regulations for the LVs using standard spark ignited ICEs considering only gaseous pollutants, just as CO, HC and NOx. Following the upcoming legislation for personal vehicles sector, the LVs might also include limits of PN and PM. Regarding fuel injection strategies, the MPFI which was previously excluded from particulate control will be incorporated into the new regulation [1]. In terms of social harm, there will be a necessity to reduce engine particulate emissions, as they are known for being carcinogenic substances [2, 3, 4]. Generally, the smaller the particulate diameter, the more critical are the damages for human health therefore, the correct determination of PN and particulate diameter is essential. Beside future challenges for reducing and controlling particulates, the reduction of fossil fuel usage is also an imminent target, being the replacement by eFuels one of the most promising alternatives.

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.

More and more restrictive regulations, as the pending Euro3 emission legislation, demand for a lowering of exhaust emissions of two stroke engines. The reduction of scavenge losses is one of the key requirements for the development of two-stroke engines. Besides it is important to maintain the excellent torque and power behavior of the two stroke units. This publication gives a summary of previous and present development results of test bench and chassis dynamometer measurements and of 3D CFD simulations. All these results are targeted on a reduction of the scavenge losses and therewith HC-emissions. Therefore the focus is put on different injection strategies, such as semi-direct and air-assisted injection. Additionally, the potential of the high pressure gasoline direct injection is presented, even if this technology is still too expensive for the small capacity engine market, e.g. the European 50 cc scooter class.