Brake booster
AssigneeBosch Braking Systems Co., Ltd.
InventorsMasakazu Machida, Yasushi Mori
Life of this patent
Estimating the term…
Abstract
An improvement of a valve plunger 14 used in a brake booster 1. A valve plunger 14 is made up of a rearwardly disposed body 34, and an engaging member 35 mounted on a front portion of the body 34. When a brake pedal is quickly depressed during an emergency brake operation, the engaging member 35 retracts rearward relative to the body 34, whereby the axial size of the entire valve plunger 14 is reduced, thereby increasing the opening of an atmosphere valve during the emergency brake operation as compared with a normal brake operation, allowing an output of an increased magnitude to be rapidly obtained. Thus, the invention allows an output from the brake booster 1 to be rapidly increased in immediate response to a quick depression of a brake pedal.
Claims6
A brake booster including a valve body slidably disposed in a shell, a power piston mounted on the valve body, a constant pressure chamber disposed forwardly of the power piston within the shell, a variable pressure chamber disposed rearwardly of the power piston within the shell, and a valve mechanism for switchably controlling a supply/discharge of a fluid to and from the variable pressure chamber, the valve mechanism including a vacuum valve seat formed on the valve body, a valve plunger connected to an input shaft and disposed within the valve body so as to be axially movable and having an atmosphere valve seat formed on a rear portion thereof, and a valve element including a first seat area which is adapted to be seated on the vacuum valve seat and a second seat area which is adapted to be seated on the atmosphere valve seat;
- the brake booster further comprising length adjusting means for reducing the axial size of the valve plunger when the input shaft has been driven through a given stroke relative to the valve body and for increasing the relative moving distance between the valve body and the input shaft so as to increase an opening of the atmosphere valve provided between the atmosphere valve seat and the second seat area during an emergency braking operation.
Dependencies are inferred from the claim text.