The present invention addresses the problem of standardizing a front shell of a booster shell of a negative pressure-type booster device by modifying the shape of a reinforcement rib provided to the front shell so as to satisfy the demand for varying the installation pitch and installation angle of tie-rod holes with one and the same front shell. A front shell configuring a booster shell of a negative pressure-type booster device in combination with a rear shell includes a reinforcement rib formed by bending the shells, wherein the reinforcement rib is formed along a virtual ellipse of which the center is located at the center of the front shell, with the major axes of the ellipse disposed on a line connecting the centers of two tie-rod holes provided in the front shell.

A vehicle brake booster includes a brake input member configured to receive a braking input force and a booster housing divided into a first chamber adjacent the brake input member and a second chamber remote from the brake input member. A poppet valve includes a poppet valve body and a poppet seal, the poppet valve operable to maintain separation between pressure and vacuum during assisted braking and further being operable to enable evacuation of the air from the first chamber through one or more side ports of the poppet valve body upon release of the braking input force and completion of the assisted braking A restrictor element provides a predetermined release speed for the booster. The one or more side ports define a total flow resistance of the poppet valve body which is less than an effective total flow resistance of the poppet valve body set by the restrictor element.

A vehicle brake booster includes a brake input member configured to receive a braking input force and a booster housing divided into a first chamber adjacent the brake input member and a second chamber remote from the brake input member. A poppet valve includes a poppet valve body and a poppet seal, the poppet valve operable to maintain separation between pressure and vacuum during assisted braking and further being operable to enable evacuation of the air from the first chamber through one or more side ports of the poppet valve body upon release of the braking input force and completion of the assisted braking A restrictor element provides a predetermined release speed for the booster. The one or more side ports define a total flow resistance of the poppet valve body which is less than an effective total flow resistance of the poppet valve body set by the restrictor element.