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Controllability is defined in ISO 26262 as a driver’s ability to avoid a specified harm caused by a malfunction of electrical and electronic systems installed in road vehicles. According to Annex C of Part 12 of ISO 26262, simulation is one of the techniques that the Controllability Classification Panel (CCP) can use to evaluate comprehensively the controllability class (C class) of motorcycles. With outputs of (i) an index for the success of harm avoidance and (ii) the magnitude of the rider’s compensatory control action required to avoid harm, the simulation is useful for evaluating the C class of the degrees of malfunction that cannot be implemented in practice for the sake of the test rider’s safety. To aim at supplying data that the CCP can use to judge the C class, we try to estimate the vehicle behavior and a rider’s compensatory control actions following a malfunction using vehicle dynamics simulations.

The ISO 26262 standard specifies the requirement for functional safety of electrical and electronic systems within road vehicles. We have accumulated case studies based on actual riding tests by subjective judgment of expert riders to define a method for determining the controllability class (C class). However, the wide variety of practical traffic environments and vehicle behaviors in case of malfunction make it difficult to evaluate all C classes in actual running tests. Furthermore, under some conditions, actual riding tests may cause unacceptable risks to test riders. In Part 12 Annex C of ISO/DIS 26262, simulation is cited as an example of a technique for comprehensive evaluations by the Controllability Classification Panel. This study investigated the usefulness of mathematical simulations for evaluating the C class of a motorcycle reproducing a malfunction in either the front or rear brakes.

In applying the ISO 26262 controllability classification for motorcycles in actual riding tests, a subjective evaluation by expert riders is considered to be the appropriate approach from the viewpoint of safety. We studied the construction of an expert-rider-based C class evaluation method for motorcycles and developed some evaluation test cases reproducing various hazardous events. We determined that it was necessary to accumulate more evaluation cases for further representative scenarios and that, to avoid variations in such evaluations, a method in which different expert riders can carry out testing following a common understanding had to be devised. Considering these problems for practical application, this study aimed at establishing an actual riding test method for C class evaluation by expert riders and to develop a deeper understanding of test procedures and management.

For applying ISO 26262 to motorcycles, controllability classification (C class evaluation) by expert riders is considered an appropriate technique. Expert riders have evaluated commercial product development for years and can appropriately conduct vehicle tests while observing safety restrictions (such as avoiding the risk of falling). Moreover, expert riders can ride safely and can stably evaluate motorcycle performance even if the test conditions are close to the limits of vehicle performance. This study aims to construct a motorcycle C class evaluation method based on an expert rider’s subjective evaluation. On the premise that expert riders can rate the C class, we improved a test procedure that used a subjective evaluation sheet as the concrete C class evaluation method for an actual hazardous event.

Controllability (C class) represents the level of the ability to avoid harm and is one of the parameters that determine the Automotive Safety Integrity Level in the ISO 26262 functional safety standard, which applies to the electrical and/or electronic systems. This study aimed to consider an appropriate C class evaluation technique for expert riders in applying ISO 26262 to motorcycles. This study attempted to show a C class evaluation method without deviation by the riders and presented examples of the evaluation of three hazardous events in actual vehicle tests. In addition, riders' comments regarding their understanding of the circumstances that resulted in the evaluation were collected, and the correspondence of these comments was examined. We selected “unintended acceleration” or “unintended deceleration” due to the malfunction of the electronic throttle control system as hazard examples and conducted tests to reproduce hazardous events.

ISO26262 was intended only for passenger cars but can be applied to motorcycles if the Controllability (C) is subjectively evaluated by expert riders. Expert riders evaluate motorcycle performance from the viewpoint of ordinary riders. However, riding maneuvers of ordinary riders have not been confirmed by objective data. For this reason, it is important to understand the basic characteristics of riding maneuvers of both expert and ordinary riders. This study seeks to confirm the compatibility between the riding maneuvers of expert riders and those of ordinary riders. The riding maneuvers and vehicle behavior of four expert riders and 16 ordinary riders were compared using the results of a test assuming normal running.

The government has been imposing a stricter diesel engine efficiency standard to reduce carbon dioxide, NOx and other particulate emissions. Diesel combustion improvement is a major concern, and many researchers have examined diesel combustion and its sprays. One possible method to solve the technical problems is applying the Variable Orifice Nozzle (VON) to fuel injection systems. The VON, which nozzle cross-sectional area is changed continuously, has been developed for direct injection (DI) diesel engines. The orifice changing mechanism is composed mainly of a rotary valve, drive shaft and small pulse motor. The VON's standard deviation (SD) of injection quantity in injection pump operation range is the same as the conventional hole nozzle's due to the rotary valve that is fixed by a spring. The smaller orifice of the VON has produced a higher injection pressure and produced a longer injection duration than that of a larger orifice.

This paper presents the structure, operation principle, and fabrication process of a novel type of flow-velocity sensor. Like the well known classical Pitot (Prandtl) tube, it realizes flow velocity detection by measurement of the pressure difference between stagnant fluid pressure in front of the sensor and static pressure in the flow around the sensor. This difference results in a deflection of a diaphragm suspended boss, that serves as the counter electrode of an integrated capacitor which is directly exposed to the fluid to be measured. Experimental results in the wind tunnel and in the gasoline direct injection experimental set-up confirm the sensor's operation principle and show good time response.

In this paper, an intersection collision warning system using DGPS (Differential Global Positioning System) will be proposed. The system is developed to prevent collisions of vehicles crossing at intersections, especially at well visibility intersections without traffic lights. Two GPS receivers are installed on two vehicles on the move towards the same intersection from different directions. The position and velocity information of the vehicles are measured by on-board GPS receivers, and then transmitted from one vehicle to another by inter-vehicle communication (IVC). Therefore, the relative position and direction of each vehicle and collision judgment coefficient (CJC) which is defined by using the relative position of vehicles are calculated. After taking the crossing position of directions and the variation of CJC into account, the position of the intersection and the possibility of collision can be predicted in advance. Warning will be given to drivers with a prearranged timing.

Reduction of flow resistance in an intake system is essential for increasing the output of a four-stroke engine. Evaluation method regardless engine displacement or number of valves or cylinder must be required in intake system design. This study proposes intake loss coefficient as total evaluation method from flow in an intake port to charging flow into a cylinder. A three-dimensional, general-purpose Computational Fluid Dynamics (CFD) code was used to calculate an intake loss coefficient. A correlation was confirmed between an intake loss coefficient and the engine power output. Intake loss coefficients and the CFD technique may be used for efficient optimization of the shape of an intake system.

The Variable Orifice Nozzle (VON), has been developed to improve diesel combustion by changing the cross-sectional area of the injection hole. The area of the nozzle orifice is continuously controlled by the rotary valve, one component of the VON. The discharge coefficient of the VON was increased by simulating an internal flow in the nozzle tip. The VON performances were evaluated by its rate of injection, injection pressure, spray droplet diameter and instantaneous photographs taken by a high speed camera. These results show that, injection characteristics and spray patterns respond to the nozzle orifice area which is changed by the rotary valve from larger to smaller. The orifice area controlled nozzle provides higher maximum pressure and a longer injection duration than the conventional hole nozzle without full-load point of the injection pump. A smaller nozzle orifice has a wider spray angle compared with larger nozzle orifice.

The motion and distribution of the cloud cavitation in a fuel injection pump are calculated. Numerical code consists of a set of equations in which the radial and transverse motion of bubbles are considered. The computational results examine that bubbles are trapped in the vortex and formed the bubble cloud. These results show qualitatively good agreement with experimental ones. Furthermore collapse of cloud cavitation is simulated numerically. The computational results reveal that the emitted impulsive pressure in the center of cloud exceeds a few GPa and becomes a few hundred times larger than the pressure from a single bubble collapse.

Due to the present demand for further improved emissions and performance of diesel engines, there is a growing need to improve the control of fuel injection quantity and timing, as well as spray properties. We have developed a Micro Turbine Sensor that can measure transient injection rate and timing using micro machining technology. This sensor realizes volumetric flow measurement using a tangential turbine as the sensing element which has an outside diameter of 1mm, and which is located next to the inlet connector of the injection nozzle. The measured results are compared with a Bosch type injection rate meter. Since the tendency of measured injection rate shows fair agreement with results of the reference system, this sensor has potential as a fuel flow meter which is able to measure the injection rate and timing directly and continuously during engine operation.

Monitoring motion parameters are increasingly important in automotive and robotics applications, where cheap sensors are highly desirable. A silicon micromachined structure 0.5X2cm in size was designed and fabricated, which can detect not only translational acceleration, but angular acceleration or rate simultaneously and independently, which has a particular merit since it theoretically allows single point detection of all 6 axis of freedom using only three sensors. This is accomplished by capacitive detection of the displacement and the tilt of the seismic mass, symmetrically suspended by two torsion bars. The expected linear dependencies of the output signal on translational and angular accelerations, as well as quadratic dependency on angular rate could be verified. It is shown, that the dynamic response is improved by vacuum packaging.

An Eulerian model of evaporating transient sprays and a new method to describe air-atomization near the injector exit to predict the mean size and velocity of droplets have been developed to study the influence of operating conditions of an air-assist hollow-cone injector and the influence of fuel atomization on the spray structure. Good agreement between the results of the computation and experiment in terms of spray shape has been achieved. The numerical results show the typical structure of sprays from the air-assisted fuel injector and show the influence of atomization on the structure.

Improvements of interior and exterior noise are important targets in vehicle engineering. There are many reports concerning the reduction of radiator cooling fan noise. But, most of those reports are associated with studies of air flow noise. A radiator cooling fan connected to a crankshaft occasionally radiates structure-borne noise in addition to air flow noise. This structure-borne noise is caused by fan blade vibration excited by torsional vibration of a crankshaft. In this paper, we surveyed the mechanism of the structure-borne noise and discussed some methods for the noise reduction. And, as a result, we developed one of the noise reduction technique aiming at isolation of crankshaft vibration by modifying viscosity of the oil in a fan clutch.

Turbochargers for vehicle use have been utilized for passenger cars and trucks to achieve high power, high torque, low fuel consumption and as a countermeasure for low emission of CO, HC, NOx, etc. Turbochargers are expected to play a major role in future to improve the performance of automobiles. Moreover, life of turbochargers has been increased steadily in spite of severe heat and stress condition due to requirement from engine manufactures. In case of truck use turbochargers, great efforts have been made to increase turbocharger life from 500,000 kms to 1,000,000 kms though the stress of the wheels has been raised due to increased boost pressure. Also, life of passenger-car use turbocharger has been increased in spite of higher exhaust gas temperature. This paper describes our experience of durability problems and our solution.