Abstract: An exhaust pressure control valve to be placed in an exhaust gas passage of a diesel engine for controlling pressure of exhaust gas to be discharged from the engine comprise: a housing formed with a main passage and a bypass passage; a main valve arranged to open and close the main passage; a bypass valve arranged to open and close the bypass passage; and an opening/closing drive device for opening and closing the bypass valve. The opening/closing drive device includes: a positive pressure actuator for opening and closing the bypass valve by pressure upstream of the main passage; and a negative pressure actuator for changing valve opening pressure of the bypass valve.

Abstract: Surface treating methods of a titanium part may include the steps of determining an effective thickness of a hard oxide film to be formed on a surface of the titanium part, determining an effective surface roughness of the hard oxide film, and oxidation treating the surface of the titanium part under a desired treating temperature and a desired treating time such that both of the determined effective thickness and effective surface roughness are satisfied.

Abstract: Surface treating methods of a titanium part may include the steps of determining an effective thickness of a hard oxide film to be formed on a surface of the titanium part, determining an effective surface roughness of the hard oxide film, and oxidation treating the surface of the titanium part under a desired treating temperature and a desired treating time such that both of the determined effective thickness and effective surface roughness are satisfied.