Search Results

When designing engine parts of motor vehicles, it is important to evaluate internal residual stresses that cause crack growth and influence the strength of parts. Internal stresses can be measured nondestructively by the neutron diffraction method. However, it is difficult to apply this method to aluminum alloy castings because they consist of coarse crystal grains. As for cylinder heads, the grain size ranges up to approximately 400 μm and there are few grains contributing to intensity of diffraction in each gauge volume. In the case of X-ray diffraction, "the oscillation method" has been employed for materials with coarse grains. In this study, the applicability of the oscillation method to aluminum alloy castings was investigated with the aim of establishing a method of measuring internal stresses and strains. A related objective was to determine the accuracy of stresses.

Prediction at the drawing stage by implementing CAE with its main feature of the finite element method is effective also for early detection of problems of strength, rigidity, and vibration in the development of motorcycles, and makes a significant contribution to the improved developmental efficiency. Accuracy of simulation is determined by precise analysis models and input conditions analogous to actual tests. Actual tests have been replaced by functional tests of individual unitary components as far as possible to save time. Load conditions due to engine vibration and various road surface reactions, as well as restrictive conditions, are classified by specifications of business and sports, and are used to prepare a database.

We have developed a method by which the oil flow rate can be measured by using a hot-wire sensor that could be installed in the passages of actual engine lubricant oil. This measuring method proves to have a ±5% accuracy and a 40kHz response that enables ‘real time’ function. Thus, observation of (1) the effect of bearing clearance, and (2) the fluctuating mechanism of the oil flow per 1 degree crank angle from the point of engine start-up to 6000r/min and full load can be achieved, and the timing and quantity of intermittent oil-jet from the oil hole in connecting rod were ascertained.

Since the operation of the powertrain system and the engine speed and torque are determined in the ECU in hybrid vehicles, control parameters in these vehicles are more sensitive to a variety of performance factors than those employed in conventional vehicles. The three performance factors acceleration performance, NVH and fuel consumption in particular are in a tradeoff relationship, the calibration of control parameters in order to satisfy these performance targets entail considerable development costs. Given this, it is possible to increase the efficiency of hybrid vehicle development by determining Pareto design solutions for the three performance factors via multi-objective optimization using CAE, and selecting target performance and control parameters based on these Pareto design solutions.