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Technical Paper

The Relationship Between Port Shape and Engine Performance for Two-Stroke Engines

1999-09-28
1999-01-3333
Measurement using a three-dimensional anemometric-tester was made for the gas flow inside the cylinder of a two-stroke engine while the shape of the transfer port was modified. The relationship between port shape and engine performance was investigated for various factors that characterize the flow in cylinder. In this paper, we focused mainly on two engine running conditions: the maximum output at 11750 rpm and the output at 10000 rpm. As a result, we found that the maximum output is most related to the tangential inclination angles of the main transfer port, and the inner vent radius of the main transfer duct.
Journal Article

The Effect of Surface Morphology of Cylinder Bore Surface on Anti-Scuffing Property made by High Pressure Die-Casting Process using Hyper-Eutectic Al-Si Alloy

2013-10-15
2013-32-9046
A monolithic type aluminum (Al) cylinder made of hypereutectic Aluminum-Silicon alloy has been widely used for motorcycle applications. It has a lightweight structure and a superior cooling ability owing to its material property and surface finishing. Usually the cylinder bore surface of the monolithic type Al cylinder is finished by an etching process or a honing process in order to expose silicon (Si) particles from aluminum (Al) matrix for the improvement of the tribological properties. The morphology of the cylinder bore surface including the exposure of Si particles is supposed to make an important effect on its tribological properties, especially on the anti-scuffing property. In this research, the anti-scuffing property of three kinds of cylinder bore finishing, an etched surface, a Si exposure honed surface and a conventional plateau honed surface is evaluated with using a reciprocated type wear tester. The experimental results are analyzed by using Weibull analysis.
Technical Paper

The Control of the Primary Inertia Force and Moments Produced in Engines with Three Cylinders or Less

1968-02-01
680023
All the primary inertia forces and/or moments generated by engines having three cylinders or less are not normally in balance by themselves and thus may be a great source of vibration for the frame supporting the engine. If the mass distribution of the crankwebs is selected in a proper manner, it is possible to determine arbitrarily the directions and the length ratio of principal axes of ellipses, which are obtained as Lissajous diagrams of inertia force and moment. This method can be effectively applied to reduce vibration in the frames. In this paper the appropriate inertia force and moment ellipse equations are developed and the analysis is outlined for optimizing the engine balance. Also the fundamental properties of the linear vibration systems excited by the elliptical forces as well as some experimental examples of elliptical excitation are detailed.
Technical Paper

Study of bonded valve-seat system (BVS)

2000-06-12
2000-05-0144
The Bonded Valve Seat System is the latest technology to realize drastic reduction in valve temperature in SI engines characterized by the good thermal conductivity of extremely thin valve seats bonded directly on the aluminum cylinder head. A unique and highly rationalized resistance bonding technique was developed to maintain adequate bonding strength and positioning precision in a short bonding period of around one second. Engineering data on optimization of bonding-section geometry, valve seat material and the surface treatment and bonding parameters were presented and discussed regarding the mechanism. The geometry of the bonding section of the cylinder head was optimized by FEM analysis so that the aluminum material should deform to embed the valve seat ring with the action of expelling the surface contamination and the oxide film. The bonding facility was modified so that the electrode axis should move flexibly according to distortion of the cylinder head during bonding.
Technical Paper

Section Flow Improvement of Plasma Spray Cylinder in Outboard Motor

2013-10-15
2013-32-9029
The two-stroke engines were in the main stream of the outboard motors, but they have been replaced with the four-stroke counterparts reflecting the environmental protection movement in recent years. However, the replacement with four-stroke engines involves increased number of components and additional displacement, and the outboard motors tend to be larger and heavier. This represents an issue, since the maneuverability of the boat is degraded due to the inappropriate weight distribution on the boat. Yamaha outboard motors F300B and VF250A, of which the production started in the year 2009, are equipped with four-stroke engines, and yet achieved the light weight equivalent to their two-stroke counterparts. The production volume of these models reached 20,000 units.
Technical Paper

Practical Use of the Engine Testing Dyno with the Vehicle Simulation for the MotoGP Race Engine Development

2007-10-30
2007-32-0043
MotoGP is the pinnacle of motorcycle racing, with the world's top riders racing 800cc prototype machines at leading venues around the world. The riders compete against each other to win the title and show their superiority. The manufacturers have improved the engines every year to gain high power with low-fuel consumption. The percentage of the duration in fully open throttle is less than 20% of the race, but the partial throttle is used as much as 80%. Moreover, when the rider accelerates the machine, the front tire is easy to be lifted from the ground. In the middle of corner, the rider cannot open the throttle fully because of the tire slip. Therefore, it is the most important factor to appropriately control a throttle in the partial area. The Drive-By-Wire (DBW) system is one of the solutions for the force control. The vehicle simulation in the engine dyno test helped efficiently to evaluate the DBW.
Technical Paper

Optimization of Multi-Valve Four Cycle Engine Design-The Benefit of Five-Valve Technology

1986-02-01
860032
THE MULTI-VALVE FOUR STROKE CYCLE engine design trend is Coward increased engine power and higher fuel efficiency. While a four-valve system is the most common direction, problems occur when the valve area is widened by increasing the cylinder bore for a higher engine output. The layout of four larger valves causes the combustion chamber shape to flatten and the combustion time period to increase. In pursuit of the optimum multi-valve engine we have studied four, five, six and seven-valve per cylinder design. Performance targets and design constraints led us toward the successful five-valve engine technology. This technology develops high engine torque and efficient combustion over a wide range of engine speeds.
Technical Paper

Light Body for Small Vehicles Using High-Quality Die-Casting Component

2003-10-27
2003-01-2869
A high-quality die-casting technology has been developed for lightweight aluminum frame structures that produces high-strength aluminum parts that are also weldable. This new technology has been used in casting frames for motorcycles and snowmobiles and has enabled improved frame designs with far fewer component parts than was possible before. This die-casting technology also results in a significant reduction in energy consumption during the manufacturing process.
Technical Paper

Improving the Fuel Consumption of Small Motorcycle Engine with YMJET-FI

2009-11-03
2009-32-0049
A construction of the technology concerning fuel consumption improvement is an important problem not only for the four-wheeled vehicle but also for the motorcycle in recent years when petroleum resources are depleted rapidly. Yamaha originally developed a new fuel injection system (YMJET-FI) and applied the system to a single cylinder, water-cooled and small-displacement engine. In this paper, we would introduce the results of improving the fuel economy with keeping high performance. Improvements were noted in three matters, namely, in the lower load range, 1.Strengthening of in-cylinder flow, 2.Atomization of fuel spray, and 3.Reduction of wall film quantity.
Journal Article

Improvement of the Startability with Reverse Stroke Intake Devices for a Motorcycle Engine

2014-11-11
2014-32-0107
This paper proposes a novel engine starter system composed of a small-power electric motor and a simple mechanical valve train. The system makes it possible to design more efficient starters than conventional systems, and it is especially effective to restart engines equipped with idling stop systems. Recently, several idling stop systems, having intelligent start-up functions and highly-efficient generate capabilities have been proposed for motorcycles. One of challenges of the idling stop systems is the downsizing of electric motors for starting-up. However, there are many limitations to downsize the electric motors in the conventional idling stop systems, since the systems utilize the forward-rotational torque of the electric motors to compress the air-fuel mixture gas in the cylinders. Our studies exceeded the limitations of downsizing the electric motors by mainly using the engine combustion energy instead of the electric energy to go over the first compression top dead center.
Technical Paper

Fuel Cell System for Two-Wheeled Vehicles

2005-10-12
2005-32-0077
Direct methanol fuel cell (DMFC) system is a compact lightweight system as it eliminates the need of a complex reformer unit. Moreover, since the methanol-water-solution used as fuel does not correspond to a flammable substance, it is thought that convenience is high. We have developed the hybrid scooter integrated with the DMFC system and the Li-ion rechargeable batteries, and optimized various parameters related to the performance and the efficiency. The power output of the DMFC system was adjusted to the value necessary for a constant ground run in 30 km/h of a commercial small electric scooter. All the system components had to be constituted in the limited space and under the restricted weight conditions. The net-power-output of the system was examined under various air flow rate, fuel flow rate and methanol concentration conditions.
Journal Article

Friction Measurement of Al-17%Si Monolithic Cylinder with using Newly Developed Floating Liner Device

2014-11-11
2014-32-0052
The improvement of fuel consumption is the most important issue for engine manufactures from the viewpoint of energy and environment conservation. A piston-cylinder system plays an important role for the reduction of an engine friction. For the improvement of the frictional behavior of the piston-cylinder system, it is beneficial to observe and analyze the frictional waveforms during an engine operation. To meet the above-mentioned demand, frictional waveforms were measured with using the renewed floating liner device. In the newly developed floating liner device, an actual cylinder block itself was used as a test specimen. The measured single cylinder was an aluminum monolithic type made of hypereutectic Al-17%Si alloy using a high pressure die casting process. The combined piston was a light weight forged piston and a DLC coated piston ring was used. For the measurement, 110cc air cooled single cylinder engine was used.
Technical Paper

Flow, Combustion and Emissions in a Five-Valve Research Gasoline Engine

2001-09-24
2001-01-3556
The in-cylinder flow, mixture distribution, combustion and exhaust emissions in a research, five-valve purpose-built gasoline engine are discussed on the basis of measurements obtained using laser Doppler velocimetry (LDV), fast spark-plug hydrocarbon sampling, flame imaging and NOx/HC emissions using fast chemiluminescent and flame ionisation detectors/analysers. These measurements have been complemented by steady flow testing of various cylinder head configurations, involving single- and three-valve operation, in terms of flow capacity and in-cylinder tumble strength.
Technical Paper

Development of Pollution-Free Rapid Plating System

1985-11-11
852264
It is in the plating process that the worst bottleneck occurs in plant automation. We, however, have succeeded in making our plating process free from pollution and compact, allowing us to install this system within a production line and consequently establish a continuous production line resulting in a decrease in plating cost to about 1/2 of the previous cost. We have achieved an excellent chrome plating speed of 60µ/min, by placing an anode relatively close to the part to be plated and by sending the plating solution into the space between the two by means of a pump. This provides a plating speed 100 times faster than with conventional methods, while improving the quality of the plating coat considerably. The system is optimum for functional platings, and can be used for the plating of shock absorber rods, engine valves, engine cylinders, etc.
Technical Paper

Development of Magnetostriction-type Load Sensor for Measurement System Using Motorcycle Testing Robot

2002-03-04
2002-01-1073
A control system for auto driving of motorcycle using anthropomorphic robot has been developed to efficiently evaluate a motorcycle with high accuracy, the performance of which is becoming higher. For magnetostriction-type load sensor, which is absolutely necessary for this system, the strain gauge type load cell has been used conventionally. However, the detection sensitivity, strength, and responsibility have not been satisfied completely under engine vibration conditions. To solve this problem, a magnetostriction-type load sensor has been newly developed. As a result of the tests with actual machines, it is found that this magnetostriction-type load sensor satisfies the conditions necessary for the motorcycle drive control system and measurement system.
Journal Article

Development of Fracture-Split Connecting Rods Made of Titanium Alloy for Use on Supersport Motorcycles

2015-11-17
2015-32-0830
A connecting rod made of titanium alloy is effective for lower fuel consumption and higher power output comparing to a steel one because the titanium connecting rod enables to reduce the weight of both of reciprocating and rotating parts in an entire engine substantially. But up to now, it has been adopted only to expensive and small-lot production models because a material cost is high, a processing is difficult and a wear on a sliding area should be prevented. In order to adopt the titanium connecting rods into a more types of motorcycles, appropriate materials, processing methods and surface treatment were considered. Hot forging process was applied not only to reduce a machining volume but also to enhance a material strength and stiffness. And the fracture-splitting (FS) method for the big-end of the titanium connecting rod was put into a practical use.
Technical Paper

Development of Fracture Splitting Method for Case Hardened Connecting Rods

2004-09-27
2004-32-0064
The fracture splitting (FS) method for case hardened connecting rods has been developed to improve engine performance while decreasing production costs. The FS method is widely used for automotive connecting rods because it effectively improves their productivity. Normalized forging steels, microalloyed forging steels and powder metals have generally been used as the material in the FS method as they are easily split due to their brittleness. On the other hand, the materials to be used for high performance motorcycles are case hardened low carbon steels because they allow the connecting rods to be lightweight due to their high fatigue strengths. These materials, which have a hardened area of approx. 0.5mm in depth from the surface, have a ductile texture inside. This texture obstructs the crack propagation and makes the split force too high to split without deforming the bearing area.
Technical Paper

Combustion Noise of Two-Stroke Gasoline Engines and its Reduction Techniques

1989-05-01
891125
In order to obtain more reduction of two-stroke motorcycle engine noise than usual, it becomes necessary to make improvements within the combustion process itself. This study was carried out for two objectives. One is the investigation of the relationship between combustion and noise, and the other one is the development of noise reduction techniques. As the result, it was discovered that there was a significant correlation between engine noise and (dP/dθ)max, called the maximum rate of cylinder pressure rise. Therefore, the reduction of the (dP/dθ) max was recognized to be effective for engine noise reduction. The optimized alteration of combustion chamber shape is the most effective noise reduction technique, because it is able to reduce (dP/dθ) max without any sacrifice of engine power. In fact, the level of noise reduction can be predicted by one of the parameters obtained from the combustion chamber shape.
Technical Paper

Analysis of the Behavior of Liquid in a Fuel Tank

1988-11-01
881782
The behavior of the liquid in the motorcycle fuel tank is an interesting theme from the viewpoint of the fuel meter construction, as effected by variance in the fuel pressure resulting from acceleration or deceleration, etc. It can be assumed that the behavior of the liquid in the fuel tank will be affected by the running pattern, the shape and capacity of the fuel tank, etc. Here is a report on an experiment recently made to observe how the liquid behaves in a partially fully enclosed tank. We simplified the tank shape and the involved conditions (to actually observe the behavior of the inside liquid by the suspension method.) Then we have analized the effectes according to different liquid containers, to different velocities, and to different liquid volumes as well as the time history variance in the internal pressure.
Technical Paper

Analyses of Cycle-to-Cycle Variation of Combustion and In-Cylinder Flow in a Port Injection Gasoline Engine Using PIV and PLIF Techniques

2017-10-08
2017-01-2213
Reduction in the cycle-to-cycle variation (CCV) of combustion in internal combustion engines is required to reduce fuel consumption, exhaust emissions, and improve drivability. CCV increases at low load operations and lean/dilute burn conditions. Specifically, the factors that cause CCV of combustion are the cyclic variations of in-cylinder flow, in-cylinder distributions of fuel concentration, temperature and residual gas, and ignition energy. However, it is difficult to measure and analyze these factors in a production engine. This study used an optically accessible single-cylinder engine in which combustion and optical measurements were performed for 45 consecutive cycles. CCVs of the combustion and in-cylinder phenomena were investigated for the same cycle. Using this optically accessible engine, the volume inside the combustion chamber, including the pent-roof region can be observed through a quartz cylinder.
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