Bemessung von Keramikventilen für eine Serienfertigung

The substitution of metal valves by ceramic valves in automobiles promises: I. Reduction of valve weight by about 60 per cent. II. Improvement of driving efficiency of the valve. III. Reduction in fuel consumption and C02 emissions. Ceramic valves have been already used in racing cars. However, the production costs especially the costs for the surface treatment are very high, therefore a mass production of ceramic valves is uneconomical. If a greater tolerance of material defects is permitted and the surface treatments are optimized, economic fabrication is obtainable. In this context, the following informations are required: I.Loading conditions of the valve. II. Endurable fatigue strength (dependent on geometry, loading mode and surface state). III. Models for the determination of loads and fatigue life assessment. IV. Scatter of endurable fatigue strength in mass production. V. Behaviour of valves under service conditions. Based on this background theoretical and experimental invest igations for assessment and series production of ceramics valves are carried out on car engines of Adam Opel AG and Daimler Benz AG.