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The article presents the possibilities of improvements the crankcase delivery ratio in small two-stroke engines by modification of the inlet system by means of an additional side volume connected with the inlet pipe. The results of calculations from numerical simulation of gas physical parameters, taking into account thermodynamic phenomena in the inlet system and crankcase, are closed to those obtained during experiments. Influence of different geometrical parameters of the inlet system on the crankcase delivery ratio is considered. The application of such system increases engine delivery ratio and improves air-fuel ratio over the whole range of engine speed, especially with part-throttle openings and higher engine rotational speed. Simulation and experimental variations of pressure and delivery ratio for various systems have been presented. Good correlation between theory and experiment makes possible a selection of this system at the early stage of design.

A Kohler 725cc air-cooled engine originally designed to operate on gasoline has been modified to run on either gasoline or propane (LPG and still meet current small engine emissions standards. The fuel system being discussed allows the end user, by means of a switch to operate the engine on either propane or gasoline. The paper will discuss a pre-emission dual fuel system and the changes required to meet emission standards and improve performance.

Recently, utilization of CFD (Computational Fluid Dynamics) at the initial stage of motorcycle development is increasing the importance and is becoming indispensable to environment matters. This paper describes a CFD system, which was developed based on PCC (Partial Cells in Cartesian coordinate) method CFD code. The code does not require the mesh generation at each computation. The merit of this system is a full automation after the solid modeling by a 3D-CAD system, such as geometry data transferring, starting of processes, and mailing the results. Moreover, an example of a combination between CFD and DOE (the design of experiment) will be explained. It is an application of an exhaust muffler design of motorcycles. In the past, the decision concerning to the power output during an exhaust muffler design could be done by only a few skilled engineers, but the decision became possible to designers who use this system.

The development of the lightweight and compact EU1000i generator with a maximum output of 1kVA is presented. The technology applied to achieve the required levels of exhaust emission, fuel consumption and noise, and to provide a stable electrical power supply with low waveform distortion is described. The technology comprises of four elements: a high-speed, multi-pole, external rotor type alternator, a microcomputer-controlled sine wave inverter, a compact high-speed 4-stroke engine with electronic speed governing, and a lightweight frame with a two-level noise-damping system. Combination of these four elements of technology has achieved 50% less weight, 25-30% lower fuel consumption, and 7-9dB(A) less noise than the previous model. The emission levels of CO and of NOx + HC are also 30% and 65% lower than the 2000 CARB regulations.

An original multi-body dynamics simulation program for reciprocating engine system with elastically deformable piston skirt was developed in order to understand and examine the secondary motion of piston. This program uses specialized equations of motion using only the rotational degree of freedom of each components taking the valiation of rotating speed of crank into account. In order to validate the practical use of this program, the calculations were compared with the measurements on the piston motion of a two-stroke engine for motorcycles and a four-stroke engine for automobiles, and good agreements were obtained between them.

The purpose of this project was to modify existing small off-road engines to meet ARB's originally proposed 1999 emissions standards. A particular point was to show that compliance could be attained without the need to redesign the base engines. Four high-sales volume, ARB-certified 1997 model engines were selected from the following categories: 1) handheld two-stroke engine, 2) handheld four-stroke engine, 3) non-handheld side-valve engine, and 4) a non-handheld overhead-valve engine. Engines were selected, procured, and baseline emission tested using applicable ARB test procedures. Appropriate emission control strategies were then selected and applied to the four engines. Emission reduction strategies used included air/fuel ratio optimization, and catalytic aftertreatment. Following the development of the four emission-controlled engines, final, certification-quality emissions tests were performed. All four engines met ARB's original 1999 Tier 2 emission standards after development.

Air assisted direct injection systems have been in commercial production for four years having established themselves as a technical breakthrough in the pursuit of low-emission two-strokes, whilst providing the end-user with smooth operation and a significant reduction to fuel consumption. The same core technology has demonstrated significant advantages for automotive direct injected four-stroke engines. For the non-automotive sector, research has since aimed to provide manufacturers with alternate cost-function options, thus extending market penetration opportunities for low cost air assist DI. By extensively benchmarking the air assisted direct injection system applied to customer marine products, Orbital engineers are developing significantly simplified systems which inherit the most performance-critical aspects of the existing production system, whilst eliminating some of the components required in today's production system.

Time-resolved measurements were made of the gas composition at the exhaust port of a direct-injection two-stroke engine operating at 2000 rpm and an air-fuel ratio of 30:1. A high-speed sampling valve capable of 1.0 ms (12 CAD) time resolution was used to collect samples 1 cm downstream of the exhaust port of the engine. The time-resolved NOx, CO2 and CO concentrations decreased continuously during the scavenging process due to the dilution by short-circuited air. The hydrocarbon emissions, however, behaved significantly differently from the other species. At the time of exhaust port opening the concentration was low, it reached a maximum value by BDC, then decreased slightly in the latter part of the scavenging event. The dilution rates calculated for the hydrocarbon data gave negative values, indicating that there was a significant production of hydrocarbons during the gas exchange period.

This paper shows a design and performance prediction methods for a miniaturized Stirling engine, in order to develop a small portable generator set. First, a 100 W class Stirling engine is designed and manufactured. In order to miniaturize the engine, unique type heat exchangers were applied. A regenerator was located in a displacer piston. For a piston drive mechanism, a Scotch-yoke mechanism which was useful to realize the small-size engine without any lubricating device, was adopted. Next, an analysis model for the miniaturized engine is developed to improve the engine performance efficiently. The pressure in the working space is analyzed by an isothermal analysis which takes into account a gas leakage through a piston ring and pressure loss in the heat exchangers. To estimate a shaft power, the mechanical loss and the buffer loss, which is caused by a pressure change in a crank case are considered on the analysis model.

This paper describes an experimental investigation into the surface heat transfer coefficient of finned metal cylinders in a free air stream. Eight cast aluminium alloy cylinders were tested with three different fin pitches and three different fin lengths. The cylinders and their fins were designed to be representative of those found on a small engine. Each electrically heated cylinder was mounted in a wind tunnel and subjected to a range of air speeds between 12 and 50 m/s. The surface heat transfer coefficient, h, was found primarily to be a function of the air speed and the fin separation, with fin length having little effect.

Using a modified engine with a transparent glass cylinder for motoring equipment, the effects of the structure in the vicinity of the oil ring groove drain back slots of the inside of the piston, the end clearance size of the oil ring side rail gaps and the shape of the top ring gap on the lubricating oil flow were examined. The results indicate that the amount of undesirable oil flow was reduced by utilizing a piston with the covers installed under the drain back slots on the inside of the piston, the side rails with the optimized upper and lower side rail gap size and the top ring with a special joint (triangle step joint) as compared to a standard piston and standard piston rings. Furthermore, the amount of undesirable oil flow was considerably reduced by utilizing the combination of the modified piston and rings.

The extremely advantageous power-to-weight, respectively power-to-bulk ratio of two-stroke engines in comparison with four-stroke engines are determining arguments for their further application in light powered two-wheelers. On the other hand, the disadvantages of actual two-stroke engines regarding high pollutant emission, respectively high bsfc - in conditions of the drastic limitation of the pollutant level in the next years - will hinder such applications, if a new quality of the two-stroke process cannot be achieved. As demonstrates in numerous research works, the scavenging improvement of a two-stroke engine can lead to a restricted amelioration of these values, but not to another level. The gasoline direct injection is considered to have the highest potential for such development.

The benefits of direct cylinder fuel injection to the fuel economy and exhaust emissions of small spark ignited two-stroke engines is well known. The selection of a commercially viable fuel injection solution continues to receive evaluation and scrutiny by the engine manufacturers. This paper describes the development and demonstration of an EDFI solution which is applicable to low cost and high production volume engines in several industries. The system is based on the “accumulator” fuel injection operating principle, which involves pressurizing fuel within an injection nozzle and subsequently releasing the pressurized fuel into the combustion chamber on command. This concept provides very short injection duration throughout the dynamic operating range of the engine as well as high injection frequency capability.

Gasoline direct injection in two-stroke engines has led to even more advantageous results, in comparison with four-stroke engines, as far as unburned hydrocarbon emissions and fuel consumption are concerned. A new electronically controlled injection system has therefore been fitted in a crankcase-scavenged two-stroke engine, previously set up with indirect injection equipment. The comparison between the performance of the two gasoline feeding systems has highlighted the potential of the direct injection strategy. The direct injection system here tested has allowed the optimization of the engine torque characteristic at wide open throttle operating conditions. Moreover, the engine original exhaust system, has been replaced with an expansion-chamber exhaust-pipe system, in order to evaluate the impact of direct gasoline injection also with these optimized exhaust configuration.

A throttle control system has been developed for a small V-twin engine used in a hybrid AC power generation system. The control system utilizes a throttle actuator, a proportional integral derivative (PID) controller and software that determines desired power outputs (engine speeds) based on real-time measurements. The control system forms part of a hybrid power generation system that incorporates two time variable three-phase AC power sources: a wind turbine and an internal combustion engine-generator combination. Initial testing of the control system shows a stable response and a reasonable settling time for speed step changes when a minimum load is applied to the engine. A design methodology for throttle control system optimization is also described.

We have attempted to reduce emissions and improve fuel economy of a small utility engine running with a lean A/F ratio under partial load conditions in the most frequent operating mode. However this caused undesirable hunching and many difficulties for running the engine at a lean A/F ratio. We derived the necessary amount of engine speed changes from the relationship between the spark timing and torque to control the hunching by adjusting the spark timing at various engine speeds. The method improved emissions and fuel economy, and made it possible to run the engine smoothly from low engine speed to higher speeds at a high load rating.

The specific output of 4-cycle engines are generally smaller than that of 2-cycle engines. Increasing engine speed is one method to improve the specific output, however, it contains some disadvantages in application. Hence, improvement in torque with the 4-cycle engine is desirable. Although torque could be improved by super-charging, it seems difficult to apply existing systems for small displacement engines due to problems of their size and cost. We have, therefore, newly developed a super-charging system named Advanced Crankcase Super Charge (hereinafter referred to as ACSC) using a crankcase as a supercharger. In this study, we made a 50cc single cylinder prototype engine with ACSC and carried out the engine unit tests and actual running tests on a scooter. From these tests, the torque that is twice as that of the naturally aspirated engine was obtained.

An extensive digital simulation study on lift devices that interact with human operators in DaimlerChrysler automotive assembly plants has been initiated and deployed. This digital mock-up of human-machine workcells is to scientifically evaluate and further certify a number of typical commercial lift devices that are served in car-assembly operations. The entire model is based on human biomechanical Jacobian relationship, as a fundamental kinematic structure, to predict human body instantaneous joint-torque distribution when the human is working with a certain payload. The developed modeling and simulation system will play a pivotal role in proactive ergonomic prediction, verification and digital certification in car advance manufacturing engineering processes.

New valve control system (HYPER VTEC:Variable Valve Timing and Lift Electronic Control System) having valve inactive mechanism which engine power is made to be united to the environment conservation was developed for motorcycle engines of sport type having higher engine speed. Mass increase in the valve operating system of this system is kept to a minimum with a compact, simple mechanism. The system enables high engine speed up to 13,500 rpm without abnormal motion of valves, having high reliability and durability. In addition, the valve control system has the enhancement of fuel economy and the effect of decreasing the intake and exhaust system sound during 2-valve operation. The switching mechanism part of the operating valve number was manufactured by cold forging, and has decreased costs. This system has been adopted to the sport type motorcycle CB400SF for domestic model in 1999.

In the ANNIE project - Applications of Neural Networks to Integrated Ergonomics - BE96-3433, a tool for integrating ergonomics into the design process is developed. This paper presents some features in the current ANNIE as applied to the design of car interiors. A variant of the ERGOMan mannequin with vision is controlled by a hybrid system for neuro-fuzzy simulation. It is trained by using an Elite system for registration of movements. An example of a trajectory generated by the system is shown. A fuzzy model is used for comfort evaluation. An experiment was performed to test its feasibility and it showed very promising results.