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The purpose of this paper is to propose a control method to reduce acceleration shock in motorcycles. Reducing the acceleration shock is very important in improving driveability of motorcycles. Motorcycles equipped with manual transmission have some backlashes in the transmission, with large backlash especially in dog clutch portions. We have figured out that one of the main causes of the acceleration shock is the collision of the dogs at high relative angular velocity during acceleration. Also, our data analysis has revealed that there is a correlation between a peak value of the longitudinal body acceleration and the relative angular velocity at the moment of the dog collision. A simulation was undertaken to verify this phenomenon, and its results have made it clear that we need to decrease the relative angular velocity at the moment of the dog collision so as to reduce the acceleration shock.

Fuel-efficient motorcycles are essential for energy conservation and environmental load reduction. To achieve low fuel consumption, reducing the weight of the body parts of the motorcycle is important. This study focuses on reducing the weight of the swingarms, a relatively heavy body part. However, reducing the weight of swingarms is challenging owing to the low flexibility in their shape because swingarms are conventionally made of multiple pipes and casting parts welded together. Therefore, we utilized the integral casting technology and examined a new light weight shape. However, creating a new shape manually is difficult. Thus, we examined a new shape using the shape optimization technology, which has been recently used in additive manufacturing. The shapes fabricated using this technology are generally complex and difficult to manufacture by casting. Therefore, we adjusted optimization condition with casting.

We developed the motorcycles based on RIDEOLOGY (Ride + Ideology) concept. In the past, the “Ride” was studied by a sensory evaluation with actual driving. However, the recent progress in numerical analysis, there have been developed driving simulators. It allows more quantitative measurement in a sensory evaluation. Therefore, we also developed a riding simulator specialized for motorcycles. In order to develop such riding simulator, there are some technical challenges for motorcycles. First, we need to reproduce roll motion height of motorcycles. Compared to four-wheeled vehicles, motorcycles have a higher center of rotation. Second, we need to reproduce vehicle motion control by rider’s changing body position. A rider controls vehicle’s lean by shifting his center of gravity. Therefore, it is necessary to construct a measurement system of rider’s body position. Third, we need to improve senses of speed and reality.

1 In the development of motorcycle engines, a strong feeling of power, an element of being fun to ride has continued strong demand. However, demand to meet environmental performance, a conflicting element, has increased dramatically in recent years and a breakthrough technology that achieves both environmental performance and a feeling of power is in demand. Here, the newly developed engine has greatly enhanced feeling of power while clearing stringent environmental restrictions through use of a centrifugal type supercharger. However, there were several problems that had to be resolved with regards to application of a supercharger to a motorcycle engine. In applying a supercharger to a motorcycle, a major problem is the best way to keep the engine size from increasing in size. The engine, which is the heaviest parts on a motorcycle greatly affects motorcycle maneuverability so it must be compact and the mass concentrated.

Owing to the recent developments in sensors with reduced size and weight, it is now possible to install sensors on a body of a motorcycle to monitor its behavior during running. The analysis of maneuverability and stability has been performed based on the data resulted from measurements by these sensors. The tire forces and moments is an important measurement item in maneuverability and stability studies. However, the tire forces and moments is difficult to measure directly, therefore, it is a common practice to measure the force and the moment acting on the center of the wheel. The measuring device is called a wheel forces and moments sensor, and it is widely used for cars. The development of a wheel forces and moments sensor for motorcycles has difficulty particular to motorcycles. First, motorcycles run with their bodies largely banked, which restricts positioning the sensors.

The traction-drive integrated drive generator (T-IDG®) has been developed since 1999 to replace current hydrostatic transmission drive generators mounted on Japanese military aircraft. The T-IDG® consists of a generator and a half-toroidal traction-drive continuously variable transmission (CVT), which maintains a constant output speed of 24000 rpm, that is, a 400 Hz AC power supply. To cope with recent trends of more electric aircraft (MEA) and the need for weight reduction, a high-speed traction-drive CVT is advantageous over other transmissions. The torque on the half-toroidal variator is transmitted through multiple power rollers. The equal load sharing among power rollers is typically controlled by a mechanical hydraulic feedback system, whose stability is one of the main issues for the high-speed traction-drive CVT. Previous studies have shown that insufficient damping and stiffness of the mechanical hydraulic feedback system cause self-induced vibration.

Motorcycle has broad spectrum of developments, such as excellent engine performance, low fuel consumption, emission and noise reduction. As global warming become a serious issue internationally, reduction of fuel consumption is especially of importance. In this study, an evaluation method for the WMTC mode fuel consumption using a one-dimensional engine simulation is investigated. The fuel consumption for the WMTC mode can be predicted in a short time without a complicated vehicle model to simulate transient behavior. The proposed method mostly showed good agreement with measured data for middle-class motorcycle using a chassis dynamometer.

The quality of exhaust sound has become one of the important factors in the motorcycle market. Therefore both an efficient sound quality evaluation method and technology to achieve ideal sound quality have become necessary. Sound qualify evaluation has generally been performed by trial and error through repeated modification of exhaust silencer construction until desired quality was obtained. But it usually took painstaking work and long hours. In order to solve such problems, we established an objective auditory evaluation method. We also applied Principal component analysis to analize the result of the “Semantic Differential Method (SD method)” so as to determine the affecting elements. Through this analysis system, “powerful sound” caused by relatively higher content of the low frequency range and “crispy sound” caused by a cyclic sound pattern were determined to be desirable sounds for “American type” motorcycles.

Motorcycle engines are required to have high output levels but low exhaust gas emission levels. Measuring the combustion condition proves useful for understanding the engine's operating condition. We developed a compact, high-performance combustion analyzer for measuring the combustion condition of motorcycle engines. This newly developed combustion analyzer is capable of analyzing the indicated mean effective pressure at each engine cycle at the engine speeds exceeding 10,000 rpm required of a high-performance motorcycle engine. Its compact size makes it easily applicable for onboard use, allowing measurement in any operating condition, including circuit travel, which has never been possible with conventional combustion analyzers. We used this new combustion analyzer to measure combustion condition not only on a chassis dynamo but also during circuit travel, when the motorcycle and engine are subjected to much harsher operating conditions.

In line with the increase in the output of motorcycle engines, there has been an increase in incidents of the seizure between shift fork and gear because of the increased thrust force. We designed a test method that uses actual shift forks to simulate actual sliding conditions, then used that test method to evaluate the feature of the shift fork sliding and the different shift fork surface treatments. The shift fork slid against the gear not as surface contact but as tilted contact. We selected the candidates from the view that the surface treatment of the shift fork contact surface to give it higher seizure resistance when in tilted contact is required. We evaluated chromium nitride thin film, diamond-like carbon thin film, molybdenum sprayed coating, and sulphonitriding, and molybdenum sprayed coating exhibited the highest seizure resistance. The conformability plays a significant role in the sliding between the shift fork and the gear.

The impact of inlet unstart phenomena on supersonic transport (SST) was investigated by wind tunnel testing. Inlet unstart condition was simulated by controlling the captured mass flow by the inlet. Unsteady pressures on the lower surface of wing and unsteady forces of the wind tunnel model were measured. Unsteady pressure measurement was carried out to detect shock wave motion. Unsteady force measurement by using both internal balance and accelerometers was to estimate axial/angular acceleration of airframe when inlet unstart was occurred. The pressure measurement data revealed that shock location fluctuated with dominant frequency although the controlled mass flow was steady. And it was analytically shown that the dominant frequency is corresponding to the first order frequency of organ pipe resonance.

Since construction machinery manufacturers recommend various brands and types of greases for their machinery, customers would benefit from a standardized grease which can be used in all construction machinery. Furthermore, construction machinery manufacturers have many experiences of field problems caused by commercially available and commonly used EP Lithium greases. Therefore, the Fuels and Lubricants Committee of Japan Construction Mechanization Association (JCMA) has developed a new grease specification called “Japan Construction Mechanization Association Specification (JCMAS) GK,” for construction equipment. The JCMAS GK includes requirements for National Lubrication and Grease Institute (NLGI) No. 1 and No. 2 consistency grades. The JCMAS GK greases have enough lubricating properties for periodical grease fitting of most construction machines, hydraulic excavators, bulldozers and wheel loaders. The JCMAS GK greases are applicable from -20 to +130 degrees Celsius.

The Japanese Quiet Short Take Off and Landing experimental aircraft named ASKA was developed and flight tested during 1977 till 1989. The control system hard and software were examined by the functional mock-up with using the actual hardware. The small longitudinal limit cycle was observed in the closed loop test when the Pitch Control Wheel Steering software was on in the mock-up testing. In this paper, first, the method to analyze and to expect the limit cycle based on the describing function was shown. The limit cycle was induced due to the nonlinearities in the automatic control mechanism. The nonlinearities in the hardware were examined to make the model to simulate the system on the computer. The method was shown effective to predict the limit cycle in the mock-up. Second, with using the flight measured dynamics, the limit cycle was concluded as on border line between existing and not, which coincides with the actual flight result.

Motorcycle configurations, such as CG (center of gravity) location, have come to be fixed to the current ones by trial and error since motorcycle was born. Generally motorcycles' ratio of CG height to wheelbase is relatively higher than four-wheel cars'. We have analyzed the optimal motorcycle CG location with relatively simple formulas, which we have derived to calculate the maximum acceleration with three performance limitations and calculate the maximum speed and the shortest time to run through a course. The results show that the calculated speed is significantly close to actual sport motorcycle's and that the optimal CG locations for various courses are bounded in a certain limited area which is near actual sport motorcycle's.

In this study on the motorcycle engine, we investigated the geometry of the newly developed intake port with an objective of improving the fuel consumption and the torque in practical range. Herein we present the results obtained. We believe that an effective measure for achieving the stated objective is to improve the combustion speed and combustion stability. To realize that, it is necessary to increase the turbulence during combustion and improve the homogeneity of air-fuel mixture. To investigate the feasible shape of the port, the CFD simulation (including fuel spray analysis) was performed and a geometry that improved the turbulent kinetic energy and mixture homogeneity at the time of ignition was selected. For confirming the combustion improvement effect achieved by tumble strengthening, an engine test was conducted with the same amount of intake air as that used in.

This paper describes the predicted results of acoustic transmission loss (T.L.) for a motorcycle muffler. First, the T.L. of a prototype muffler with one expansion chamber was obtained by measuring sound levels at the inlet and outlet ports of the muffler by speaker test. T.L. was then calculated by using a three-dimensional Finite-Element Method (FEM) for acoustic fields in the muffler. There was good coincidence between the calculated T.L. and experimentally observed data. Second, T.L. of the prototype muffler while attached to a motorcycle engine was measured. On this step, however, a similarly calculated T.L. using FEM to consider the effect of exhaust gas temperature in the muffler showed differences from the measured one. It was estimated that muffler body vibration sounds may affect the result. A dynamic analysis of the structure was carried out using FEM to obtain the eigen modes of the muffler body.

In this study, the technology that can predict fatigue life for motorcycle exhaust systems is developed. To predict the fatigue life, analyzing the engine vibration, modeling the vibration characteristics of exhaust systems and evaluating the fatigue damage of welded joints are considered essential. This paper shows an integrated numerical simulation and evaluation method. Furthermore, it is also shown with the result of a component vibration test of the muffler assembly to validate the technology. The results indicate a good correlation between the numerical simulation and the test.

In the modern aircraft manufacturing, the cost reduction, the manufacturing time reduction, and the weight saving of aircraft are strongly demanded. The Refill Friction Spot Joining [1,2](FSJ, in other words FSSW, Friction Stir Spot Welding), which is one of innovative solid-state joining methodologies based on the Friction Stir Welding[3], is a promising technology that can replace rivets and fasteners. This technology is expected to offer cost reduction and weight saving for the aircraft manufacturing. In this study, to make stronger and reliable joints, the shoulder-plunging process of Refill FSJ was employed. The weldability of the Alodine or Chromic Acid Anodize coated materials along with a faying-surface sealant was investigated. The joint properties, such as tensile shear strengths and corrosion resistance, were evaluated.

Machine learning is used for the research and development of ITS services and the rider assistance for on-road motorcycle racing. Meanwhile, rider assistance systems for off-road motorcycles have yet to be developed, partly due to the complexity of the measurement conditions, as described in the previous paper. This research aims to create a reliable AI which is capable of classifying typical jump behaviors in off-road riding by machine learning to create a rider assistance system for off-road motorcycles. Motorcycle manufacturers and certain research institutes use motion sensors to collect data, but the data is obtained from a limited number of vehicles and riders. The creation of a rider assistance system requires a large amount of validation data. Furthermore, it is desirable to achieve the target with data that can be measured in mass-produced vehicles, which will make it possible to collect data even from general users.

Motorcycle engines are operated at an extremely broad range of revolutions, from 1000 min-1 to 10000 min-1 or more. Ideally, the natural frequency of each part should never match the engine excitation frequency at any point over that entire range of revolution speeds, but practically, there are times when resonance cannot be avoided because the range is so broad, and therefore the vibration amplitude at resonance must be kept low. For this reason, it is important to grasp not only the resonance frequency but also the vibration amplitude at that point. This may be achieved by two methods, measurement and analysis. The direct measurement of vibration is generally difficult because the motorcycle muffler system has a complex shape and in addition it gets very high temperature when the engine is operating. For this reason, with the aim of being able to predict muffler vibration at the design stage, we carried out a vibration test and FEM (finite element method) analysis.