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Technical Paper

Enhancement of Thermal Fatigue Strength by the Addition of Calcium to Hypoeutectic Aluminum-Silicon Alloys

2018-10-30
2018-32-0027
Several elements affect the structure of eutectic silicon in hypoeutectic aluminum alloys [1, 2, 3, 4]. Among them, calcium has been investigated to a lesser extent compared to the typically used sodium and strontium. In order to enhance the thermal fatigue strength of a small engine, the morphology of eutectic silicon in hypoeutectic aluminum-silicon alloys is controlled by the addition of calcium. In addition, the castability and mechanical properties are investigated. Hence, samples containing different amounts of calcium are prepared at different cooling rates during solidification. The results revealed that, with the increase in the calcium amount and the cooling rate, eutectic silicon exhibits a fine morphology in cross-sectional images. Particularly, with the addition of at least 62 mass ppm of calcium in a specific range of cooling rates, refined eutectic silicon is obtained.
Technical Paper

Modeling of Quasi-Steady State Heat Transfer Phenomena with the Consideration of Backflow Gas Effect at Intake Manifold of IC Engines and Its Numerical Analyses on 1-D Engine Simulation

2018-10-30
2018-32-0029
An empirical equation was developed for modeling the heat transfer phenomena taking place in an intake manifold which included the backflow gas effect. In literature, heat transfer phenomenon at intake system is modeled based on steady flow assumptions by Colburn analogy. Previously, authors developed an equation with the introduction of Graetz and Strouhal numbers, using a port model experimental setup. In this study, to further improve the empirical equation, real engine experiments were conducted where pressure ratio between the intake manifold and engine cylinder were added along with Reynolds number to characterize the backflow gas effect on intake air temperature. Compared to the experimental data, maximum and average errors of intake air temperature estimated from the new empirical equation were found to be 2.9% and 0.9%, respectively.
Technical Paper

Artificial Neural Network Based Predictive Real Drive Emission and Fuel Economy Simulation of Motorcycles

2018-10-30
2018-32-0030
As the number of different engine and vehicle concepts for powered-two wheelers is very high and will even rise with hybridization, the simulation of emissions and fuel consumption is indispensable for further development towards more environmentally friendly mobility. In this work, an adaptive artificial neural network based predictive model for emission and fuel consumption simulation of motorcycles operated in real world conditions is presented. The model is developed in Matlab and Simulink and is integrated into a longitudinal vehicle dynamic simulation whereby it is possible to simulate various and not yet measured test cycles. Subsequently, it is possible to predict real drive emissions RDE and on-road fuel consumption by a minimum of previous measurement effort.
Technical Paper

Development of a Riding Simulator for Motorcycles

2018-10-30
2018-32-0031
We developed the motorcycles based on RIDEOLOGY (Ride + Ideology) concept. In the past, the “Ride” was studied by a sensory evaluation with actual driving. However, the recent progress in numerical analysis, there have been developed driving simulators. It allows more quantitative measurement in a sensory evaluation. Therefore, we also developed a riding simulator specialized for motorcycles. In order to develop such riding simulator, there are some technical challenges for motorcycles. First, we need to reproduce roll motion height of motorcycles. Compared to four-wheeled vehicles, motorcycles have a higher center of rotation. Second, we need to reproduce vehicle motion control by rider’s changing body position. A rider controls vehicle’s lean by shifting his center of gravity. Therefore, it is necessary to construct a measurement system of rider’s body position. Third, we need to improve senses of speed and reality.
Technical Paper

Development of Coaxial Type Thin Film Temperature Sensor with Improved Measurement Accuracy Based on Principle of Thermoelectromotive Force

2018-10-30
2018-32-0032
In order to verify cooling loss reduction effect of internal combustion engine, method for measuring wall surface temperature and heat flux with high accuracy is required. Various methods have been proposed for measuring the cooling loss from the combustion gas to the combustion chamber wall, newly coaxial type thin-film temperature sensor was developed for wall temperature and heat flux measurement by the authors. This sensor consists of thin-film and body and center wire have three junction positions in the case where three materials are different. Therefore, it is necessary to use the same materials for thin-film and body or thin-film and center wire to make two junction points. In this study, sputtering method that can be formed various kinds of alloy materials and film thickness of 0.1~1μm on the sensor surface was chosen.
Technical Paper

Analysis of Cooling and Warm-Up Performance of Oil-Cooled Engine with Fin-Shaped Oil Jacket

2018-10-30
2018-32-0036
An oil-cooled engine has been developing to achieve better warm-up performance. The oil-cooled engine has an oil jacket that pass through around the exhaust port and the cylinder liner. Fins were installed inside the oil jacket to enhance cooling performance. The result of a bench test shows that the fins enhance the cooling performance with slight loss of warm-up performance. The aim of this study is to clarify effects of the fins. This study conducted two simulations. One is a cooling simulation that was conducted to clarify the reason why the fins enhanced the cooling performance. The other is a warm-up simulation that was conducted to clarify the reason why the fins almost maintained the warm-up performance. The cooling simulation was conducted by steady flow simulation. It simulated a full-load operation of the bench test. It compared converged temperature between the engines with/without the fins. The warm-up simulation was conducted by unsteady flow simulation.
Technical Paper

On the Effect of the Injector Position on Fuel-Air Mixture Preparation in a Two-Stroke GDI Engine

2018-10-30
2018-32-0040
Modern injection systems are characterized by low cost, light weight and diversified components based on a mature technology. In addition, the constant growth of computational resources allows an in-depth understanding and control of the injection process. In this scenario, increasing interest is presently being paid to understand if an application of such technologies to small two-stroke engines could lead to a return to popularity in place of the more widespread use of the four-stroke engine. Indeed, the possibility of achieving a drastic reduction of both specific fuel consumption and pollutant emissions would completely reverse the future prospect of the two-stroke engine. The authors in previous studies developed a low pressure direct injection (LPDI) system for a 300 cm3 two-stroke engine that was ensuring a performance consistent with a standard four-stroke engine of similar size.
Technical Paper

Application of the Newly Developed KLSA Model into Optimizing the Compression Ratio of a Turbocharged SI Engine with Cooled EGR

2018-10-30
2018-32-0037
Owing to the stochastic nature of engine knock, determination of the knock limited spark angle (KLSA) is difficult in engine cycle simulation. Therefore, the state-of-the-art knock modeling is mostly limited to either merely predicting knock onset (i.e. auto-ignition of end gas) or combining a simple unburned mass fraction (UMF) model representative of knock intensity (KI). In this study, a newly developed KLSA model, which takes both predictions of knock onset and intensity into account, is firstly introduced. Multiple variables including the excess air ratio, EGR ratio, cylinder pressure and the end gas temperature are included in the knock onset model. Based on the auto-ignition theory of hot spots in end gas, both the energy density and heat release rate in hot spots are taken into consideration in the KI model.
Technical Paper

Technologies to Achieve Future Emission Legislations with Two Stroke Motorcycles

2018-10-30
2018-32-0042
Increasingly stringent emission regulations force manufacturers of two wheelers to develop low emission motorcycle concepts. Especially for small two-stroke engines with symmetrical port timing structure, causing high HC-emissions due to scavenge losses, this is a challenging demand that can only be met with alternative mixture formation strategies and by intensifying the use of modern development tools. Changing from EU4 to EU5, emission legislation will not only have an impact on the improvement of internal combustion but will also drastically change the after-treatment system. Nowadays, small two-stroke engines make use of a simple carburetor for external mixture preparation. The cylinders are scavenged by air/fuel mixtures. Equipped with exhaust gas after-treatment systems, such as secondary air with two or three catalytic converters, the emission limits for EURO 4 homologation can be achieved with carbureted engines.
Technical Paper

Overview of Different Gas Exchange Concepts for Two-Stroke Engines

2018-10-30
2018-32-0041
The concept of a loop scavenged two-stroke engine, controlling the intake and exhaust port by the moving piston, is a proven way to realize a simple and cheap combustion engine. But without any additional control elements for the gas exchange this concept quickly reaches its limits for current emission regulations. In order to fulfil more stringent emission and fuel consumption limits with a two-stroke engine, one of the most important measures is to avoid scavenging losses of fuel and oil. Additionally, it is necessary to follow a lambda = 1 concept for a 3-way exhaust gas after-treatment. Therefore, using internal mixture preparation systems in combination with different concepts to control the gas exchange process, the two-stroke engine could become a choice for automotive applications, especially as a Range Extender in a Plugin Hybrid Electric Vehicle (PHEV).
Technical Paper

Influence of Ethanol and 2-Butanol Blended Fuels on Combustion and Emissions in a Small Displacement Two Stroke Engine

2018-10-30
2018-32-0044
Small displacement two-stroke engines are cheap and low-maintenance propulsion systems and commonly used in scooters, recreation vehicles and handheld power-tools. The restriction by emission legislation and the increasing environmental awareness of end users as well as decreasing energy resources cause a rethinking in the development of propulsion systems and fuels in these fields. Despite recent improvements of electric powertrains, two stroke engines are the challenged propulsion system in high performance handheld power tools at the moment. The reasons are the extraordinary high power to weight ratio of two-stroke engines, the high energy density of liquid fuels and the reliability of the product with respect to extreme ambient conditions. Nevertheless, further improvements on emissions and fuel consumption of small displacement two-stroke engines can be realized.
Technical Paper

Performance Improvements to a Production, Semi Direct Fuel Injected, 2-Stroke Engine for a Racing Application

2018-10-30
2018-32-0043
The following material presents an overview of using a production 2-stroke engine and transforming it into one for the racing application of Snocross. This paper will explore the changing of engine hardware, engine related hardware and software while staying within the project scope for schedule, tooling capabilities and rules of the governing body for Snocross racing. This conversion process is discussed in detail through analytical calculations, to the experimental validation with dynamometer and airflow bench data.
Technical Paper

Combustion Analysis with Residual Gas as a Design Parameter for Two-Stroke Engines

2018-10-30
2018-32-0045
In a variety of applications, two-stroke engines assert their usage as a propulsion unit, for examples in off-road vehicles, scooters, hand-held power tools and others. The outstanding power to weight ratio is the key advantage for two-stroke engines. Furthermore, two-stroke engines convince with high durability and low maintenance demand. However, an increasing environmental awareness, the protection of health and the shortage of fossil resources are the driving factors to further enhance the internal combustion process of two-stroke engines. The reduction of emissions and fuel consumption with a constant power level is focused on. Developments deal with the optimization of the combustion process itself or the enhancement of the exhaust gas aftertreatment. Especially in very small two-stroke engines an exhaust gas aftertreatment system is rarely applied, due to disadvantages regarding component temperatures and product costs.
Technical Paper

Experimental Investigation on the Potentiality of a GDI System Applied to a Two-Stroke Engine: Analysis on Pollutant Emission and Fuel Consumption Reduction

2018-10-30
2018-32-0047
The small two-stroke engine represents a strategic typology of propulsion system for applications in which lightweight and high power density are required. However, the conventional two-stroke engine will not be compliant with forthcoming legislations about pollutant emissions and new solutions, such as electrification, are seriously taken into account by industry to overcome the two-stroke engine drawbacks. In this scenario, a promising way to allow the two-stroke engine to be competitive is represented by the use of direct injection systems, in order to overcome the long-standing issue of short circuiting fuel. The authors in previous studies developed a low-pressure direct injection (LPDI) system for a 300 cm3 two-stroke engine that was ensuring the same power output of the engine in carbureted configuration and raw pollutant emissions consistent with a four-stroke engine of similar performance.
Technical Paper

Assessing Tire Performance from Vehicle Dynamic Transfer Functions

2018-10-30
2018-32-0048
The aim of this study is to develop techniques which can be used to assess tire performance for a motorcycle in a race track and correlate them with subjective perceptions of race riders. This approach focusses on using vehicle level performance parameters and transfer functions to assess tire performance. A subjective assessment study is performed to understand rider’s perception. Tire behavior is then studied by assessing the dynamic performance of the motorcycle in a race track. Analysis techniques are then developed to interpret the data measured and understand tire performance. Based on these techniques, vehicle dynamic parameters and transfer functions that can be used to asses tire performance are developed. Correlations between objective findings and subjective perceptions are then identified.
Technical Paper

Effects of In-Cylinder Flow and Stratified Mixture on HCCI Combustion in High Load

2018-10-30
2018-32-0016
The purpose of this paper is to find a way to extend the high load limit of homogeneous charge compression ignition (HCCI) combustion. This paper presents the effect of in-cylinder flow and stratified mixture on HCCI combustion by experiments and three-dimensional computer fluid dynamics coupled with a detailed chemical reaction calculation. The first study was conducted using a rapid compression and expansion machine (RCEM) equipped with a flow generation plate to create in-cylinder turbulent flow and with a control unit of in-cylinder wall temperature to create in-cylinder temperature distribution. The study assesses the effect of the turbulent flow and the temperature distribution on HCCI combustion. In the second study, the numerical simulation of HCCI combustion was conducted using large eddy simulation coupled with a detailed chemical reaction calculation. The study analyzes the interaction between in-cylinder turbulent flow and mixture distribution and HCCI combustion.
Technical Paper

Theoretical and Fundamental Consideration to Accord between Self-Steer Speed and Rolling in Maneuverability of Motorcycles

2018-10-30
2018-32-0049
This paper considers the phenomenon that the self-steer speed when riders bank a motorcycle. This paper points out that this phenomenon originates from capsize mode. Further, it is specified that the first order differential equation representing capsize mode is included in the equation of motion of the steering system. Furthermore, it is specified that this differential equation is the first order differential equation for the roll angle. Therefore, as the roll angle increases, the roll angle further increases and the steering angle also changes, which is the mechanism of capsize mode. Finally, as a result of parameter studies, it is stated that the design parameters that most affect capsize mode were front and rear camber stiffness.
Technical Paper

Road Simulation Techniques for Reproducing Vehicle Behavior at Motocross Running on a Track

2018-10-30
2018-32-0051
A Road Simulator was developed with the aim of reproducing actual vehicle behavior while running on motocross (MX) track in a laboratory. Vehicle behavior while running on an MX track is influenced by various inertial forces, such as jump landing, acceleration at full throttle, reduced speed at full braking and so on, and also load input from the rider to handlebars and footrests. As all influences must be considered, these inertial force and external force should be applied to a vehicle in laboratory tests. To reproduce various inertial forces such as falling inertia at jump landing, longitudinal inertia during acceleration or deceleration, and rider body action on the vehicle, Active restraint systems must be added instead of the traditional method of Road Simulator that controls wheel axle’s vertical and longitudinal directions with actuators.
Technical Paper

Preliminary Study on Closed-Loop Acceleration Control of Motorcycles

2018-10-30
2018-32-0050
In this study a preliminary investigation regarding closed-loop acceleration control for motorcycles is presented. Comprehensive considerations for the implementation of such a controller are discussed. Challenges, which are addressed, are a stable and sufficiently accurate measurement with the help of low-cost sensors and the consideration of the varying available maximum acceleration for set point calculation. In case of torque control, the maximum available torque is scaled by the throttle and thus automatically meets the limitation. Using acceleration as control variable, the varying set point limitation must be considered. According to current hypothesis, a precise closed loop control of the motorcycle longitudinal dynamics can be realized on the basis of the reference variable acceleration, yielding new possibilities in drive train control. The current control of the longitudinal dynamics is done by specifying a target output torque.
Technical Paper

Durability Improvement of Cylinder Head in Alternate Fuel Engines

2018-10-30
2018-32-0055
Alternate fuels like LPG and CNG are beneficial in terms of operating cost and emissions as well. They also contribute to reduce CO2 emissions. These gas fuels are known for its problems in engines including wear of parts. Cylinder head valve - seat wear is higher in gas engines. This paper discusses the experimental work on reduction of valve -seat wear in 3 wheeler engine. In the development of new higher power version of the gas engine valve-seat interface wear is observed. Effect of this wear on performance, leak and emissions were studied, qualitative measurements of valve temperatures were studied at different conditions with different fuels. Combustion gas and part temperatures are higher in gas engines. Simulation test cycle is developed for the wear test and various solutions to reduce wear at the valve - seat interface were evaluated. Cost effective solution is implemented with minimum changes in engine.
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