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Viewing 1 to 30 of 75
Technical Paper
2014-11-11
Takahiro Masuda, Kouji Sakai, Yuki Yamaguchi, Jun-ichi Kaku, Hirobumi Nagasaka
This paper proposes a novel engine starter system composed of a small-power electric motor and simple mechanical devices. The system makes it possible to design more efficient starter-generators than conventional systems, and especially, it is effective to restart engines equipped with idling stop systems. Recently, several idling stop systems have been proposed for motorcycles to achieve intelligent start-up functions and highly-efficient generation. One of challenges of the idling stop systems is downsizing of starter motors. However, there are real limitations to downsize the motors in the conventional idling stop systems, since the systems utilize forward-rotational torque of the motors to compress mixture gas in cylinders. Our study exceeds the limitations of the downsizing by exploiting combustion energy instead of electric energy to run over a first compression top dead center. The starter system described in this paper consists of (A) an electric motor which can rotate a crank shaft both forward and backward, (B) a cam-train to drive an intake valve during an exhaust stroke in a backward rotation, and (C) a control unit to inject and ignite at arbitrary timing.
Technical Paper
2014-11-11
Tatsuhiko Sato, Hirotaka Kurita, Akemi Ito, Hideyuki Iwasaki
The frictional force generated between an actual monolithic aluminum cylinder block and a piston / a piston-ring in a firing mode was measured with using a newly developed floating liner device for the first case in the world. The improvement of fuel consumption is the most important issue for engine manufactures from the viewpoint of energy and environment conservation. The piston-cylinder system plays quite important role for the reduction of the 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. In order to meet the above-mentioned demand, the renewed floating liner device was developed. In the newly developed floating liner device, the actual cylinder block itself was used as a test specimen, whereas a thin-walled cylindrical sleeve should be used as the test specimen in the conventional floating liner device. The measured single cylinder was an aluminum monolithic type made of hypereutectic Al-17Si alloy using a high pressure die casting process.
Technical Paper
2013-10-15
Mitsuo Hirai, Takashi Ueno, Youhei Iwaki, Shojiro Oohama
This paper presents an approach for efficiently evaluating motorcycle main frame strength using external loads predicted from measured strain data in our development process. The loads are calculated by simple matrix inversion, and can be used as boundary conditions of static analysis that resembles actual phenomena. The advantage of this method is that it allows relatively precise reproduction of actual boundary conditions without the data usually needed for dynamic simulation such as tire and suspension characteristics which often take large amount of time and man-hour to obtain. Although this approach is simple and common practice, there are a lot of things to be concerned for gaining useful results in a broad range of stages in the motorcycle main frame development process. How we effectively make use of this approach is going to be introduced here.
Technical Paper
2013-10-15
Shun-ichi Akama, Yasunori Murayama, Shigeho Sakoda
This paper concerns a torque control of a rear wheel of a motorcycle equipped with a rubber/aramid belt electronically-controlled continuous variable transmission where a primary sheave position is controlled by an electric motor. In particular, the paper discusses a method to calculate a required engine torque and a required primary sheave position, given reference values of a rear-wheel torque and an engine rotational velocity. The method forms a foundation of a hierarchized traction control where a higher control layer decides an optimal motorcycle motion (rear-wheel torque and engine rotational velocity) and a lower control layer realizes the motion by actuators (engine torque and primary sheave position). Difficulties of the control are due to large mechanical compliance of the rubber/aramid belt, which leads to an inevitable lag from the primary sheave position to a speed reduction ratio. Taking into account the compliance, the proposed method compensates rotational kinetic energy and losses of the transmission to improve accuracy of the control.
Technical Paper
2013-10-15
Shun-ichi Akama, Yasunori Murayama, Shigeho Sakoda
This study deals with reduced-order modeling of intake air dynamics in single-cylinder four-stroke naturally-aspirated spark-ignited engines without surge tanks. It provides an approximate calculation method for embedded micro computers to estimate intake manifold pressures in real time. The calculation method is also applicable to multi-cylinder engines with individual throttle bodies since the engines can be equated with parallelization of the single-cylinder engines. In this paper, we illustrate the intake air dynamics, describe a method to estimate the intake manifold pressures, and show experimental results of the method.
Technical Paper
2013-10-15
Hideya Kumagai
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. The sleeveless cylinder block produced by utilizing the thermal spraying technology has successfully reduced the distance between the cylinders, and has contributed to realize smaller and lighter-weight components used in the cylinder block and the related areas.
Technical Paper
2013-10-15
Manabu Fujito, Yasunobu Harazono, Kouji Sakai
Recently, there have been many reports about developing control systems that actuate engines and brakes based on friction circle. We are researching the control system for motorcycles, which adds the return torque of throttle grip based on it for informing the limit of tire grip on the driving wheel. This throttle grip is a haptic display, offers haptic signals by controlling the motor connected to the throttle grip as a HMI. From the results of riding tests, the system was found helpful for riders to control the throttle grip as well as feeling easy about knowing the limit of tire grip. But it is known that the friction circle of a driving wheel depends on the normal force which changes by the gradient of road, acceleration and so on. The compensated control for changing the normal force by gradient was made to improve the throttle grip control system. The results of riding tests with the compensated system, we found that this system is important for the controls based on friction circle and it makes the haptic signals come close to the timing that riders want.
Technical Paper
2013-10-15
Yohei Kuroki, Hiroyuki Tsunekawa, Shunsuke Yukawa
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. Consequently, the advanced propeller damper for reducing the gearshift shock and noise has been developed.
Technical Paper
2013-10-15
Tetsuya Kimura, Yusuke Ando, Eiichiro Tsujii
This paper describes the development of a new concept two-wheel steering system for realizing motorcycle motion control. By considering the whole of the main frame as the rear-wheel steering axis, it was possible to move the rear-wheel steering system from the conventional installation position at the rear arm to the head pipe. As a result, the developed two-wheel steering system is both lightweight and compact. This two-wheel steering system was installed in a motorcycle, and starting and stopping tests were carried out with two people riding on the motorcycle. The test results confirmed that the two-wheel steering system is capable of changing the motion characteristics of the motorcycle in actual riding. Furthermore, by calculating the equivalent wheel alignment of this system, this paper also theoretically demonstrates that these changes in motion characteristics are caused by changes in caster and trail.
Technical Paper
2013-10-15
Akira Kamiya
The propeller blade hydrofoil section is one of the factors that determines the propeller performance. In the development of the hydrofoil, repeatedly performed experiments using many foil models and the cavitation tunnel involve extended time and high cost. This is why there are expectations for the numerical simulation to realize shorter development time and cost cutback. On the other hand, a technique for reproducing the hydrofoil characteristics taking account of the cavitation effect using CFD (Computational Fluid Dynamics) has hardly been established. There is no example of performance prediction especially for a hydrofoil section of the outboard motor propellers in which the trailing edge is cut off. This paper describes the results of the prediction of hydrodynamic characteristics performed in regard to the two differently shaped outboard motor propeller blade hydrofoil sections taking account of the cavitation effect. Calculation was performed by commercial finite volume method CFD code.
Technical Paper
2013-10-15
Hisashi Goto, Takeshi Morikawa, Mineo Yamamoto, Minoru Iida
This paper reports a methodology to estimate combustion pattern and emission by predictive simple simulation with good accuracy on various conditions of PFI engine. 3D-CFD cord VECTIS has been applied for this simulation, its settings and methods are as follows. RANS equation with liner k-epsilon model has been used as the turbulence model. Turbulent burning velocity equation contains not only turbulent velocity term but also laminar burning velocity term. For ignition model, we use a predictive model called DPIK. We iterate cycle calculation until wallfilm behavior is stabilized to get the reasonable mixture formation. We have applied this methodology to 125cc engine of motorcycle. As a result, we have obtained heat release curve and pressure curve with good accuracy on various operating conditions such as engine speed, engine load, air fuel ratio, wall temperature, and spray direction. CO and NOx calculated simultaneously have also been acceptable. CO formation is based on chemical equilibrium, and NOx formation is based on the extended Zeldovich mechanism.
Technical Paper
2013-10-15
Takehiro Uhara, Hirotaka Kurita
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. It is shown that the experimental data of the anti-scuffing property can be evaluated quantitatively by Weibull analysis.
Technical Paper
2013-10-15
Tsuyoshi Kubota
In four-cycle single-cylinder motorcycle engines, high Hertzian stress is generated on and beneath the big-end surface of the connecting rod. If the surface strength would be improved, the diameter of the big-end could be made smaller, making the entire engine smaller and lighter. Therefore, application of carbide dispersion carbonitriding using a vacuum furnace (hereinafter referred to as “vacuum CD carbonitriding”) on the big-end surface was investigated. Vacuum CD carbonitriding was carried out by three processes. The first was a CD carburizing process. This process is done to obtain granular cementite, but in order to avoid decreasing the strength, it is necessary to prevent the formation of coarsened cementite at the grain boundary. The second process was a refining process. This process is done for the purpose of refining the prior austenite grain size. The third process was a carbonitriding process. This process is done for the purpose of increasing hardness in the vicinity of the surface.
Technical Paper
2013-03-25
Nobuo Hara, Pisithsak Surawichai
We introduce a research on steering dampers using MR fluid (Magnetorheological Fluid). In recent years, steering dampers have been used in on-road and off-road motorcycles. Steering dampers stabilize the front end of motorcycles. The advantage of a steering damper is increased stability, but hydraulic steering dampers give rise to the problem of ‘Heavy Steering’. In order to resolve this heavy steering, we need to set the restrictions on the maximum damping force and avoid it from interfering when the rider is steering. However only reducing the damping force will lead to insufficient damping force when the handle, unresponsive because of kickback, shakes. We solved this problem with the development of an electric control damper which generates sufficient damping force at low steering angle rates and also allows for mechanically limiting the maximum damping force. The damper design uses “Direct Shear Mode” and features a steering angle sensor built into the damper, which results in easier and smoother steering.
Technical Paper
2012-10-23
Yuki Hosoi
Any improvements of the fuel economy with engines are always required for all petroleum fuel vehicles. The goal of such improvements must lead to reduce fuel consumption of the engines. However it may cause some deterioration with riding feeling that is one of the most important characteristics of the motorcycles. Yamaha has developed the strong hybrid motorcycle "HV-X"(hereafter the motorcycle). The motorcycle consists of a 4-stroke 250 cm₃ a cylinder engine and two 300V AC motors with a planetary gear set. The motorcycle reduces fuel consumption without severe influence onto the drive performance by utilizing the electric power.
Technical Paper
2012-10-23
Tomoaki Kishi, Toshifumi Uchiyama, Shigeru Fujii
Recently, our research has focused on the weave mode. This is a representative vibration mode of motorcycles and is important when considering maneuverability and stability. In a method of analyzing the weave mode, a disturbance is applied to the handle bars of the motorcycle during running and then the response waveform of the roll angle and other items at that time is used to perform estimations. However, when the motorcycle is driven at low speeds, the steering operations of the rider have a large effect on the running data and this makes estimation difficult. Therefore, it was assumed that weave mode data can be estimated from slalom running data since this possesses almost the same vibration frequency as the weave mode in low speed range. In this research, a simulation was used to investigate the relationship between the weave mode and slalom running. The results of the investigation confirmed that slalom running at a specified speed around pylons placed apart at a specific interval resulted in the same vibration mode as the weave mode in low speed range.
Technical Paper
2011-11-08
Miki Yumoto, Kazuhiro Goto, Shouichi Kato, Minoru Iida
This paper reports visualization of behavior of spray, wall film, and initial flame propagation in an SI engine with port fuel injection system for motorcycle in order to directly investigate their influences on combustion and relations among them. Borescopes were used to visualize the flame propagation in the combustion chamber and wall film in the intake port. Various injection systems and injection parameters were tested: injection direction, timing, and size of droplets to investigate the effect of mixture formation. It is concluded that combustion stability under low load condition is greatly influenced by mixture inhomogeneity in the combustion chamber whose evidence is the luminous emission. It is caused by direct induction of considerable amount of liquid fuel with large size of droplets into combustion chamber or too inhomogeneous mixture in the intake port. Luminous emission in the flame was also seen under wide open throttle condition due to direct introduction of wall film into combustion chamber.
Technical Paper
2011-11-08
Nobuo Hara, Yasunobu Harazono, Masashi Matsuo, Masanori Negoro, Terumi Yachi, Hitoshi Watanabe, Satoshi Ishikawa
In this paper, we introduce a research of Steering Damper using MR fluid (Magnetorheological Fluid). In recent years, Steering Dampers have been used in motocross races on off road courses. Steering Dampers stabilize the front end of motocross bikes that are used in competitive races held on rough terrain. The advantage of a Steering Damper is increased stability, however hydraulic Steering Dampers give rise to the problem of ‘Heavy Steering’. In order to solve this problem, we used MR Fluid and developed an Electronic Control Steering Damper that does not use a valve like hydraulic damper. The damper design uses “Direct Shear Mode” and features a steering angle sensor built into the damper, which results in easier, smoother steering. To test the effectiveness of our new design, we installed our new Steering Damper on the YZ 450F (Yamaha's competition model). We then asked for feedback from riders both in Japan and overseas. From the feedback we received, we were able to confirm the effectiveness and efficiency of our new design as well as its superiority over traditional designs.
Technical Paper
2011-11-08
Daisuke Hirajo, Koji Kobayashi, Tetsuya Kimura
This paper presents a practical simulation model of the rubber V-belt CVT which is widely used as a low cost driveline element for small displacement motorcycles. The characteristic of this CVT is determined by the axial force balance between driver and driven pulleys, and the elastic force of a rubber V-belt. Because these axial and elastic forces are calculated by the kinematic and FEM analysis, a large-scale simulation model which costs long execution time for the calculation is needed to estimate the characteristic of CVT. This calculation uses the one-dimensional simulation model built up with MATLAB and SIMULINK environment, so that it was possible to get the calculation result with relatively low execution time. The elastic deformation of the rubber V-Belt was calculated by a simple spring model which was verified by experiments and FEM. This simulation model can be used to predict CVT characteristic and estimate the performance of vehicle such as acceleration, fuel consumption, and emission.
Technical Paper
2011-08-30
Takuji Murayama
The continuously variable transmission (CVT) with a rubber belt used in scooters is also regarded as a potential automatic transmission mechanism for conventional motorcycles. By making this system more compact and building it into the engine, a motorcycle CVT engine has been developed that is about the same size as a manual transmission (MT) engine. During driving with a CVT, heat is generated by friction at the sheaves, and therefore it was necessary to secure a certain length of belt to ensure that external air flows efficiently to the sheaves. However, making the CVT more compact restricted the belt length, which decreased cooling performance and increased the number of bends in the belt, making it difficult to maintain durability. To address this issue, a plastic resin drive belt and newly designed sheaves were adopted, and durability of more than that of a scooter was achieved.
Technical Paper
2011-08-30
Miki Yumoto, Kazuhiro Goto, Shoichi Kato, Minoru Iida
Mixture formation is one of the most important factors for the combustion in the spark ignition engine with port fuel injection. The relation between combustion and mixture quality, however, is not quantitatively well established. In this study, the connection of combustion and mixture formation was explored with various measurement techniques. Borescopes were used in order to investigate the flame propagation in the combustion chamber and behavior of spray and fuel film on the wall in the intake port. For the purpose of investigation on the effect of mixture formation, various port fuel injection systems and parameters were tested and compared: direction, timing, and size of droplet. An SI engine for small vehicle was used under condition of 4 000 rpm. The investigation by images obtained has shown that inhomogeneity of mixture causes low combustion stability, especially due to direct introduction of fuel droplets into the combustion chamber. Injection timing and direction cause different flame behavior due to difference of mixture and wall film formation.
Technical Paper
2011-05-17
Motokuni Nishiyama
Yamaha Motor Co., Ltd. has developed the new model EC-03 designed and engineered with technology developed under the Company's Smart Power ideal. Launched on the market in September 2010, the Model is an “electric commuter” entry in the personal mobility category that is expected to show increasing demand in the future.
Technical Paper
2009-11-03
Kazuyoshi Furukawa, Yasuyuki Muramatsu, Shuhei Adachi
Yamaha Motor Co., Ltd. has been developing 1kW generator system of direct methanol fuel cell (DMFC). The performance and durability characterization of a 1kW DMFC stack that the weight of the stack was decreased 20% in comparison with that of previous stack was evaluated. The DMFC operation condition was optimized from the design of experiment and the results of the net output. The overall system efficiency of the Yamaha DMFC system using the stack became a maximum in current 20A, was 30%. The stack was generated at 20A under the Daily Start up and Shutdown (DSS) condition for 1500h. This report describes some latest results concerning the durability characterization, which were obtained in the NEDO's project.
Technical Paper
2009-11-03
Yoshitaka Nagai, Katsumi Suzuki, Takanori Tamura, Wataru Ishii, Hiroyuki Tsuzuku
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. As a result of the combustion improvement by this system and the optimization of the engine performance, the developed model (the prototype model) with this system was able to improve the fuel consumption by 22% on the test cycle of ECE R40-01 compared with the production model with a carburetor as reference, while maintaining high performance.
Technical Paper
2009-04-20
Daijiro Tanaka, Hideki Oki, Tetsuji Yamazaki, Akira Miura, Ei Tsukahara
Regarding S.I. gasoline engine, it is one of the most important matters to eliminate cyclic variation of combustion. Especially with high compression ratio and high boosted engine, the difficulties increase more. This paper describes the analysis of combustion process precisely by using many ion-current probes and CFD with the unique approaches. The number of used ion-current probes is 80 and they are mounted on whole combustion chamber wall especially including moving intake and exhaust valve faces. Thus cyclic variations of flame propagation can be measured precisely under high compression ratio and high boosted conditions in a multi-cylinder engine. In addition, CFD combustion simulation is conducted through full four strokes of continuous nine cycles. Moreover air motion and pressure vibration in intake and exhaust manifolds in whole cycles are considered. These unique approaches have made CFD result correspond to the measurement result of cyclic variations of actual combustion. As the result, the principal factor of the cyclic variation of combustion is revealed.
Technical Paper
2008-09-09
Kazuhiro Matsumoto, Hans H. Diebner, Ichiro Tsuda, Yukiharu Hosoi
We focus on the control issue for engine systems from the perspective of chaos theory, which is based on the fact that engine systems have a low-dimensional chaotic dynamics. Two approaches are discussed: controlling chaos and harnessing chaos, respectively. We apply Pyragas' chaos control method to an actual engine system. The experimental results show that the chaotic motion of an engine system may be stabilized to a periodic motion. Alternatively, harnessing chaos for engine systems is addressed, which regards chaos as an essential dynamic mode for the engine.
Technical Paper
2008-09-09
Kouji Takasu, Hisatoshi Kinoshita, Ryusuke Kato
In this study, lean combustion concept was investigated to realize better Fuel Economy (FE) on a single cylinder motorcycle engine. A low-pressure direct injection (DI) system was applied to realize lean stratified combustion concept with good combustion stability. In addition, Exhaust Gas Recirculation (EGR) system applicable to small motorcycle engines was used to attain FE improvement and NOx reduction. EGR gas temperature and EGR return position were focused on and effects on FE and NOx were investigated. Computational Fluid Dynamics (CFD) was used to reveal EGR distribution and air motion in both the intake port and the cylinder. As a result, the influence of the stratified charge, EGR temperature and EGR return position on FE and NOx were explained quantitatively. These techniques were effective in reducing NOx and improving FE for a single cylinder motorcycle engine.
Technical Paper
2007-10-30
Shoichi KATO, Takanori HAYASHIDA, Minoru IIDA
The demands on internal combustion engines for low emissions and fuel consumption are increasing year by year. On the other hand, engines to be used in motorcycles need to provide high output and quick response to meet user desire. In order to realize low fuel consumption while keeping high performance, it is necessary to properly understand cyclic variations during combustion as well as the influence of the injection system on fuel control during transient periods. The current paper reports on the results of a study in the influence of port fuel injection on combustion stability in a small displacement motorcycle engine, using both a series of experiments and CFD. The parameters of the injection systems under study are: (1) injection targeted area, (2) injection timing, and (3) fuel droplet size. The results of the current study show that injection aimed at the upstream wall yielded the best combustion stability. With injection aimed at the intake valve face, combustion stability deteriorated depending on injection timing and coolant temperature.
Technical Paper
2007-10-30
Tsuyoshi KUBOTA, Yasuyuki YAMASHITA, Hiroshi YAMAGATA
This paper describes an experimental method to predict the rolling contact fatigue life of a crankpin in a market vehicle engine. The fatigue life up to pitting was evaluated by two laboratory tests including a fatigue life measurement using a ball-on-disk test machine and a crankpin durability measurement by an engine bench test. The surface observation after the tests revealed that the surface dent triggers pitting in both tests. The Weibull plot of the percent failure vs. cycle to failure as a function of the contact stress was presented. In order to directly evaluate the effect of the contact stress on the lifetime, the lifetime values measured at L50 are plotted in the diagram showing the contact stress vs. cycle to failure. The obtained relation can predict the lifetime under the controlled condition in which the number of maximum torque points is countable. A method to place the lifetime of the market vehicle engine on the Weibull plot of percent failure vs. cycle to failure is developed.
Technical Paper
2007-10-30
Kimihisa MATSUYAMA, Masamitsu SUGI, Noboru YABE
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 a 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 mid 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. As a result, a controllable engine was developed and the development costs were saved lower.
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