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In order to improve the performance and fuel economy of a reciprocating engine, it is important to reduce the overall engine frictional losses. In this paper, author conducts an experimental study on the friction characteristics due to pumping loss, valve-train system, piston assembly, auxiliaries and transmission for a 110cc, single cylinder 4-stroke gasoline engine using frictional strip-down analysis. Friction strip-down method is commonly used to investigate the frictional contribution of various engine elements at high speeds and for better understanding of the make-up of the total engine friction. The engine friction measurements for the particular engine are carried out on a motoring test rig at different engine speeds. In addition, the effect of engine operating parameters such as oil temperature and oil quantity in engine sump is also presented in detail.

Recently in North America, natural gas such as shale gas has gained much attention, and industrial SI engines are expected to fit in various fuels such as gasoline, LPG, and natural gas. Also tightened exhaust emissions regulations require industrial SI engines to adopt feedback fuel injection systems with three way catalysts. In response to these requirements of customers, we have developed a bi-fuel engine model which can be operated on any of gasoline, LPG, and natural gas. In this paper, approaches and technologies used for the development of the model are explained. On the gasoline version of the model, the locations of fuel injectors and the design of the inlet manifold with a surge tank were optimized by using Computational Fluid Dynamics (CFD). And we sought the optimum arrangement of an inlet manifold, a fuel delivery pipe, and plug-on type ignition coils.

In this study, a single cylinder diesel engine model is built via the ANSYS FLUENT CFD solver to simulate the phenomenon during each stroke. The initial conditions and boundary conditions are set based on experimental data obtained from a turbo-charged common-rail diesel engine developed by Mitsubishi. The variables that can be observed from the CFD model include cylinder pressure, gas velocity, cylinder temperature, fuel particle tracks, and mass fraction of cylinder gas components. The simulation results display the effects of the fuel injection timings on the combustion heat release process, cylinder pressure and cylinder temperature at different engine operation conditions. The pure diesel (C10H22) is adopted in this simulation study. In the FLUENT setup, k - epsilon is used in the viscous model, and the autoignition model is used to simulate the spontaneous combustion.

A large number of small size gas-fired cogeneration engines operate with homogenous lean air-fuel mixture. It allows for engine operation at high efficiency and low NOx emissions. As a result of the rising amount of installed cogeneration units, however, a tightening of the governmental emission limits regarding NOx is expected. While engine operation with further diluted mixture reduces NOx emissions, it also decreases engine efficiency. This leads to lower mean effective pressure, in particular for naturally aspirated engines. In order to improve the trade-off between engine efficiency, NOx emissions and mean effective pressure, numerical investigations of an alternative combustion process for a series small cogeneration engine were carried out. In a first step, Miller and Atkinson cycles were implemented by advanced or retarded inlet valve closing timings, respectively.

The charge stratification has been thought as one of the ways to reduce the sharp pressure rises of HCCI combustion. The objective of this study is to evaluate the potential of equivalence ratio, initial temperature, and EGR gas stratifications for reducing pressure-rise rate of HCCI combustion. Using rapid compression machine, the stratified pre-mixture is charged, and compressed to analyze the change of in-cylinder gas pressure and temperature traces during compression process. Based on the experiment results, numerical calculations by CHEMKIN are conducted to more specifically analyze the potential of equivalence ratio, initial temperature, and EGR gas stratifications on the reduction of pressure rise rate. Multi-zone model is used to simulate the thermal stratification, fuel stratification and EGR gas stratification of in-cylinder charge as like real engine.

To effectively use Computational Fluid Dynamics (CFD) for engine emission development it is necessary to be able to simulate the scavenging flow in an engine. The CFD model for a stratified charged two-stroke engine is even more complex. This model have been tuned and finally validated with engine tests. A CFD model has been made of the Husqvarna 560XP two-stroke stratified charged chainsaw engine. The model contains piston, cylinder, inlet system ducting and exhaust silencer. The simulation runs with moving deforming mesh with all ports active. The airflow levels have been fine tuned with inlet restrictions similar to those in the air filter holder, which is not completely included in the present model. The results and behaviour of the CFD model has a very good match to the measured values of the finished product. This gives us confidence in the model and several aspects can now be studied that is virtually impossible to capture by other means.

This paper describes the fuel properties, combustion characteristics and exhaust emissions of the methyl esters of saturated fatty acid with 6 to 10 carbons in the molecule chain. The fuels blend (50/50 mass%) of three saturated fatty acid methyl esters (methyl caproate, methyl caprylate, methyl caprate); with methyl laurate as a base fuel are tested using a DI diesel engine. From the experimental results, the blend of saturated fatty acid methyl ester with a lower carbon number has a lower kinematic viscosity, pour point and smoke emission, though having longer ignition delay, the same as long chain saturated fatty acid methyl ester.

In order to comply with the existing emission norms of BSIII in India or EURO III and beyond that also, it is not sufficient to use the catalytic converter technology alone over the wide range of engine operating maps. Different studies across the world have proved that the cost, drivability, operating range against AFR, heat dissipation rate characteristics of catalytic converter limit their use in startup and idling conditions. One common way to tackle this condition is to use the Secondary Air Injection (SAI) system. In this system, small amount of air is injected after the exhaust port to initiate the thermal oxidation of gases. The right amount of air injected at the right time and at right location will reduce the emission by 37-90%. In the following study, SI engine vehicle with single cylinder, 160 cc and having carburetor is used as a test vehicle to evaluate the performance of SAI. The SAI system is modeled in AVL BOOST software and validated against the experimental data.

In this study, the re-starting characteristics of a motorcycle engine with idle-stop were investigated. Generally when turning off the engine, there is; or when restarting engine, the air-fuel mixture will become rich to cause the incomplete combustion. When the restarting period is shortened, the aforementioned phenomena would be improved. The aim of this study was to shorten the engine re-starting time during start-up. In the initial stage of the study, the gear ratio of the starter was changed, and the parameters of the engine speed and cylinder pressure were measured and analyzed. The results showed that supplying the additional fuel injection duration of 3 milliseconds into the combustion chamber before the engine was stopped would give the quicker restarting characteristics.

A novel rotational internal combustion engine is invented and investigated. In this engine, no eccentric rotational component is used, resulting in vibration-free operation. For this characteristics, this engine will be suitable for usage in silent environment, e.g. co-generation house plant, handy-usage and so on. The engine mainly consists of a rotor casing and two types of rotor; cycloid rotor and trochoid rotor. The shape of the cycloid rotor is characterized by epicycloid surface and lobes, and the trochoid rotor also superior-epitrochoid surface and concaves. As mentioned above, fundamental process of intake, compression, ignition, expansion and exhaust for working gas is automatically performed by the constant speed rotation of both of rotors. In this paper, first, the typical configuration including two designing procedure of the rotors are described in detail. Next the cyclic behavior of the working process is explained.

To effectively reduce the greenhouse gas emission, electric scooters have been developed and become a booming green transportation around the world. Most of these electric scooters possess a fixed reduction ratio in the powertrain, which makes them far from satisfactory-you can't have low cost, high performance and efficiency at the same time. However, as a silver bullet, one kind of two-speed transmission is developed. The two-speed transmission will shift automatically according to speed and throttle. An exquisite design with of a one-way clutch as well as a synchronizer effectively reduces the inevitable shocks while shifting. The electric scooter with such two-speed transmission will be launched on the market in 2013. This product successfully reaches the concept of high performance, high efficiency and rather low cost.

Generally, the gearshift mechanism for outboard motors shifts into forward or reverse gear without using the synchromesh arrangement (dog clutch engagement)(See Fig.1). This type of shift mechanism has advantages in simple structure and in saving space and cost, but at the same time, this is often the source of problem due to the abrasion caused by the hitting of gear against the dog clutch before the engagement, as well as large gearshift shock and noise. In addition, the outboard motor horsepower is getting bigger in recent years. As they are equipped with bigger and heavier engines and propellers, the shifting shock and noise tend to become more severe. For this reason, the improvement in this aspect is required. We looked into the way to reduce the shock and noise by means of propellers, because the propeller can be mounted and replaced easily, which allows the effective improvement to be spread to the outboard motors already in the market.

Use of catalyst in engines has entailed a radical increase in the importance of misfire detection. When a misfire occurs, hydrocarbon emissions will increase and the unburned fuel can damage the catalyst by overheating. On-Board Diagnostics II (OBDII) regulations are still not applied to motorcycle or moped yet. However its application is under discussion in European Union. In Taiwan, OBD is scheduled to be implemented soon. Many strategies of misfire detection have been developed, including variation in engine shaft angular speed, spark plug voltage, cylinder pressure, oxygen sensor signal, knowledge based expert system, and neural networks. WE propose a new method to use the real time signals of a wide band oxygen sensor to detect misfire where, misfire was induced on purpose with a misfire generator. The sensor and the misfire trigger signals were recorded simultaneously.

In small vehicle applications in which carburetion and oxidation catalysts are used, a fuel efficient means of engine-out NOx reduction is necessary to avoid the cost of implementing a 3-way catalyst and closed-loop-controlled fuel injection system. Pinnacle Engines' single-cylinder 110cc lean-burn opposed-piston 4-stroke architecture has been tested to gather steady-state fuel consumption, emissions, and combustion stability data over a matrix of speed, load, mixture ratio, and combustion phasing. Contributions to total vehicle fuel usage and emissions production are evaluated using steady-state flow data weighted by time spent at a respective load and speed from a tested WMTC drive cycle. Cumulative emissions and fuel economy impacts are presented for multiple NOx-reducing engine control strategies using control variables of mixture ratio and combustion phasing. Pre-catalyst HC and CO levels are affected by operating strategy and are reported for catalyst load.

Range extender (RE), combined by an engine and a generator, charges the battery on the electric vehicle. Power management strategy of a range extended electric vehicle (REEV) will determine the required charging power according to battery state of charge (SOC) and driver demands. The charging power demand will be further converted into required operation torque and rotational speed demands from engine. Torque-based engine management system (EMS) is, therefore, required to receive the torque command from power management strategy for controlling the engine at required torque. This research develops a torque-based EMS for a RE engine which is a 125cc four-stroke semi-direct injection engine and fueled by liquefied petroleum gas (LPG). The RE engine is operated to provide stable power output for driving generator, so we only select two operating points for this engine. The first operating point is for higher power output and better fuel economy.

In the recent past, the non-geared (step less) transmission scooters are becoming more popular mainly due to ease of driving without gear shift hassle. Typically these scooters transmit the power through a continuously variable transmission commonly called as CVT. The CVT of a scooter is generally air cooled and located in a protective chamber. This chamber reduces the heat transfers between the CVT and the atmosphere. The temperature reached inside the chamber during the operation of the CVT is quite high, especially when the CVT is operated in hot environment. This may reduce the service life of the drive-belt since it generally decreases when the average operating temperature increases. Along with V belt, high temperature inside CVT chamber also deteriorates durability of centrifugal clutch liner, bush, centrifugal rollers and other CVT parts. Therefore, it is necessary to limit the operating temperature of the CVT system.

Reducing the fuel consumption of conventional ICE vehicles are usually achieved from reducing vehicle running resistance, improving engine efficiency, save the idle energy, and recycling the waste energy. About 5-10% of fuel consumption can be saved by engine idle-stop, which strongly depends on fuel cut-off schedule before the vehicle completely stop. However, engine shut-off during vehicle coasting-down always exist strong concerns of safety and drivability issues. Fuel cut-off before vehicle completely stop creates the risk that the driver might change-of-mind (CoM). The driver could request the engine restart during engine running down period, when engine speed between 200-500rpm. With convention starter, the pinion gear is actuated simultaneously with the starter motor energizing. There will be no chance to engage the pinion gear with crankshaft gear when the engine is not still.

A Hybrid electric vehicle saves fuel by four aspects, i.e. engine idle-stop, regenerative braking, engine downsizing, and engine load change. Saving fuel by 5-10% is achievable with optimized fuel cut-off strategy. However, emission and drivability trade-off must be carefully treated. The conventional automatic transmission requires a mechanical pump driven by the engine crankshaft offers hydraulic function, lubrication, and cooling. To stop the engine during vehicle idling, transmission fluid pressure will not be sufficiently maintained for the launch clutch in engaged status. Once the engine restarts, the engine speed profile can cause the transmission fluid pressure uncontrollable, which creates bump during vehicle take-off. In most vehicles equipped with a conventional automatic transmission (AT) as well as start-stop function, an electric oil pump is usually installed to maintain fluid pressure.

Problem of HCCI combustion is knocking due to a steep heat release by the ignition that is occurred in each local area at the same time. It is considered that dispersion of auto-ignition timing at each local area in the combustion chamber is necessary to prevent this problem. One of technique of this solution is to make thermal stratification. It could be made by using two-stage ignition fuel, which has large heat release at low temperature reaction. Dispersion of fuel concentration leads to difference of temperature histories while combustion phasing is dispersed at each local area. Also, EGR gas stratification could make difference of temperature histories at each local area because of that of the characteristics. This study examines the effect of mixing stratification by stratifying the charge of fuel and CO2. A single-cylinder engine equipped with optical access was used in experiments, and numerical analysis was executed.

Since the exhaust emissions of an in-use motorcycle usually increases along its age, the Taiwan Environmental Protection Administration (TEPA) started to adopt useful life and deterioration factors requirements for the emission type approval certification in 1991. Considering the actual travel mileages for most motorcycles in Taiwan, it is necessary to extend the useful life period and mileage requirements for the future emission standards. This change of requirement will increase certification time and costs of new models for manufacturers. To evaluate the feasibility of shortening the accumulated useful life mileage for the regulatory durability test requirement; this study surveyed 105 sets of durability test results to explore the effects of deterioration factors on durability test result calculations.