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On the majority of motorcycles, the body structure is a framed construction. In the process of structural design for the motorcycle frame, a numerical optimization assisted by computer is vital as effective measure to determine the best design specifications all the time. Conventionally, however, in nearly all of the examples in which sensitivity analysis and optimum design methods were applied to frame structure, the design variables were limited to the cross-sectional dimensions of the members. In the study presented here, a minimum mass design of the motorcycle frame was aimed in which the cross-sectional dimensions of members and even the positions of members could be employed as design variables.

In the development of a new model of cruiser-type motorcycle, the quality of its exhaust sound was tuned up by using the exhaust sound in the opening and closing action of the accelerator. Using samples of exhaust sound taken from such a condition, a sensory evaluation test was conducted by a semantic differential method (SD method). As a result of factor analysis, two factors, deepness factor and distinctness factor, were selected as representative factors for evaluation of the exhaust sound quality of cruisers. By mapping sound samples of these factors, the position of the target exhaust sound for the model under development was identified. The effects of the physical properties of sound on the deepness factor and the distinctness factor were clarified. The mufflers were then adjusted to achieve the target sound quality. This paper reports on this experiment.

The automobile industry presently focuses on improving fuel economy and reducing the weight of vehicles. One part of these efforts is to develop high-performance engines for improved combustion efficiency and lower emissions. Against this background, many high-performance motorcycle engines use forged pistons made of extruded or continuously cast aluminum alloy for high reliability and material properties. The cost of forged pistons is higher than that of gravity die cast pistons. To replace these expensive forged pistons, a low-cost, high-performance piston with increased endurance and thermal resistance has been developed using a newly developed aluminum alloy and a high-quality die casting technology using an oxygen supply system and additional pressure.

A new 660cc turbo-charged Spark-Ignition Direct-Injection (SIDI) engine was developed. The mini-car equipped with this engine is the first mini-car with a turbocharged SIDI engine to receive the Japanese Ultra-Low-Emission-Vehicle (ULEV) certification. The vehicle achieved a 5.7% fuel economy improvement on the Japanese 10-15 mode compared to the mini-car equipped with the baseline port fuel injection (PFI) engine. The baseline engine is currently used for both the mini-car and snow mobile vehicles, and it is feasible to expand the SIDI engine application to also cover snow mobile applications, and achieve the demonstrated benefits of low emission, low fuel consumption and high engine output

An integrated data acquisition system supported by LAN(Local Area Network) technology (“DAS”) was used to develop four-stroke 990cc racing motorcycles. The measurement data provided by DAS enabled high-performance racing motorcycles to be developed in a short time. This paper explains the DAS and introduces a case of racing motorcycle development by using measurement data acquired from each racing track.

In the development of an all-terrain vehicle (ATV), measuring the stress acting on the frame upon landing after a jump is one of the methods for checking the strength of the vehicle body. When the ATV lands on the ground, particularly heavy loads hit the body and the stresses acting on the frame increase accordingly. Therefore, we have developed an efficient method for simulating an ATV landing after a jump so that we can quickly determine the strength of the frame. To develop the simulation method, we conducted ATV jump-landing experiments, calibrated the results of simulation with the data measured in the experiments, and reproduced the behavior of the frame using mechanism analysis. This made it possible to clarify the boundary conditions of the frame upon jump-landing, which were not fully known before, and calculate the stresses by structure analysis.

This paper is to propose the equations of motion in time of steady-state cornering motion, which are derived from the Lagranges's equations. The proposed equation is the nonlinear algebraic equation analyzable the handling torque characteristic, and applicable also to a large bank angle conditions. The amount of this paper is explained under the following four points. 1. The equations of motion in time of steady-state motorcycle cornering motion are derived from applying the Lagranges's equations of motorcycles R.S. Sharp proposed. The experiment value was used in the process to derive from. This new proposed equations include the additional new items which are not used in existing equations of motion in time of steady-state cornering motion, based on the equations of the straight-running stability. 2. The proposed new equations are considered the influence of tire section radius. 3.

In motorcycle market, there is demand for technology that makes it possible to drive fast safely. One such technology has already been commercialized; control that prevents front lift while enabling maximum acceleration performance. We have developed a more accurate version of this control. In order to maximize acceleration performance, it is necessary to keep front lift angle as close to zero as possible. Reducing output driving force helps to keep the front lift angle low, but if output driving force is reduced too much, it will degrade acceleration performance. Feedback control that reduces output driving force when front lift is detected is effective for optimizing this trade off, but increasing feedback gain too much to reduce front lift angle will cause output driving force to change suddenly, making for a less comfortable ride.

Recently, society has demanded better performance from motorcycle regarding comfort, fuel economy, exhaust emission, and safety, in addition to traditional performance indicators. In the development of power trains, therefore, compact and lightweight hardware with improved transmission efficiency has been introduced, along with system technologies that optimize the engine revolution speed range and reduction ratio to suit driving conditions. This approach focuses on improving overall efficiency and addressing the issues of easier drivability and greater active safety. Electronic Controlled Continuously Variable Transmission (ECCVT) with high transmission efficiency is characterized by a Dry Hybrid Belt, in addition to an electronic controlled DC motor-driven shift mechanism, and an Electronic Controlled wet multi-plates Clutch (ECC).

The computational method and the CAE technique have been developed to evaluate durability performance of a motorcycle body. The computational method in this study consists of three parts of simulation. The first is the mode analysis of the body parts. The second is the multi body dynamics simulation, which calculates forces loaded into the frame of a motorcycle body equivalent to actual durability tests. The third is the static structure analysis, which calculates stress distribution using the forces calculated by the multi body dynamics simulation as boundary conditions. Also, two kinds of durability tests, that are the chassis durability test and the falling durability test, are simulated in this study.

The purpose of this study is to evaluate the effect of an exhaust throttle installed in an exhaust pipe in a two-stroke motorcycle engine. In the experimental study, the exhaust-throttle system prevented fresh-gas from short-circuiting and consequently, improved unburnt hydrocarbon emissions and fuel economy, along with enhancing combustion stability. In actual running, in order to minimize HC emission level and stabilize cycle-to-cycle fluctuation of combustion including intermittent misfiring, an air-induction system and a long-duration spark ignition were used in addition to the exhaust throttle system. The control software for the integrated system was also a key point in improving HC and CO emission levels in the ECE-40 operation cycle. For detecting misfiring in the ECE-40 cycle, time-resolved HC variation was measured by a fast-response gas analyzer.

Recent years, ANC (Active Noise Control) technology has been paying attention. However, rather than the noise measures, the noise gives us the impression even running sound for motorcycles. That is, the control method of the engine sound is shifted from the noise reduction to sound design in each manufactures. Therefore, we proposed a method to design the engine sound using Active Sound Quality Control (ASQC) based on the ANC. Specifically, we proposed the algorithm amplifying and reducing the engine specific order components. From the simulation results, the engine specific order components can be amplified and reduced like an equalizer with the proposed algorithm. And, auditory impressions of engine sound controlled by ASQC were investigated using psychoacoustic measurements. 13 stimuli were obtained by applying ASQC for several order components to amplify or reduce their levels.

A motor for an electric vehicle has a stator core and a coil bonded with insulating varnish. The Impregnation of varnish in the stator and at the coil end greatly affects the vibration characteristics of the stator. In this paper, the experimental modal analysis of the sample stator was carried out to measure the vibration characteristics, and a vibration analysis model of the stator with the finite element method was developed. The laminated structure of an electromagnetic steel plate constituting a stator is modeled by anisotropic material properties. The joint stiffness of the varnish which connects the stator and the coil is modeled. We also modeled the varnish applied to the coil end. We carried out eigenvalue analysis and frequency response analysis. The simulation results are basically consistent with the experimental mode shapes and natural frequencies under 1000 Hz.