Abstract: A method for controlling a hydrogen generation system includes controlling the potentials of an electrode for oxygen generation and an electrode for hydrogen generation included in an electrolyzer so that the potential change is smaller in the electrode for oxygen generation or the electrode for hydrogen generation having a larger deterioration rate than in the electrode having a smaller deterioration rate.

Abstract: A friction clutch device includes clutch plates which are retained through meshing engagement on the inner peripheral surface of an outer case, which is rotatably driven by an engine. Each clutch plate includes a flat, annular pressing element which is pressed against a clutch friction plate for frictional contact therewith. Engagement protrusions are formed on the outer peripheral surface of the pressing element. The engagement protrusions fit into recessed engagement grooves provided on the outer case and mesh with the outer case. Proiectinq portions which project toward the inner peripheral surface of the outer case are formed on the outer peripheral surface of the pressing element.

Abstract: A plate element which can reduce drag torque, a friction clutch device including such a plate element, and a brake device including such a plate element are provided. A friction clutch device 100 includes clutch plates 103 which are retained, through meshing engagement, on the inner peripheral surface 101a of an outer case 101, which is rotatably driven by an engine. Each clutch plate 103 includes a flat, annular pressing element 103a which is pressed against a clutch friction plate 107 for frictional contact therewith. Engagement protrusions 103b are radially formed on the outer peripheral surface of the pressing element 103a. The engagement protrusions 103b are fit into recessed engagement grooves 101b provided on the outer case 101 and are meshed with the outer case 101. Projecting portions 103c which project toward the inner peripheral surface 101a of the outer case 101 are formed between adjacent engagement protrusions 103b on the outer peripheral surface of the pressing element 103a.