| 摘要 |
PURPOSE:To prevent plastic deformation and to correspond to high output by approaching the most throttled portion of a cooling water passage to an opening on a trochoidal inner peripheral face and by providing concave portions on the inner wall of a housing. CONSTITUTION:The portions of cooling water passages 7f, 7g along an ignition plug mounting unit 11b on the leading side and throttled most by the ignition plug mounting unit are approached to an opening 13b of a communicating hole of the leading side on a trochoidal inner peripheral face 2, and concave portions 14c, 14d where cooling water passes smoothly are provided on the inner wall 1 of a rotor housing. Thus, plastic deformation of a portion between a sealed groove on the side portion of the inner wall of the housing and the trochoidal inner peripheral face can be prevented to correspond to high output. |
