| 摘要 |
A partial vacuum type pneumatic servo device includes a housing (16) consisting of a cylinder (32) and a cover (34) and divided into two chambers (18, 20) by a movable wall structure (10) comprising a plate (12) and a flexible diaphragm (14) attached to the housing (16) by a bead (30) formed around its outer peripheral edge, and forming a fold in the space between the plate (12) and the housing (16), said plate (12) being centrally secured to a hub structure containing a valve assembly, and having an extension (40) extending forward form its outer edge. The extension (40) comprises a radial shoulder (42) and the radial distance (D) between the back portion (44) of the extension (40) and the cover (34) is substantially equal to the radial distance (d) between the front portion (46) of the extension (40) and the cylinder (32), less the thickness of the diaphragm (14). |
