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Automatic brake booster

Imported: 24 Feb '17 | Published: 06 Jan '04

Hidefumi Inoue, Naohito Saito

USPTO - Utility Patents

Abstract

An automatic brake booster includes a solenoid and a solenoid plunger which allow a flow path in a valve mechanism to be switched without depression of a brake pedal. The solenoid plunger comprises a rear member on which an atmosphere valve seat is formed, a front member which is disposed to be displaceable with respect to the rear member, and a first spring disposed between the both members. When a current fed to the solenoid is less than a given value, the first spring remains inactive while when the current exceeds the given value, the first spring becomes flexed to reduce a clearance between the rear member and a holder which forms part of a magnetic path of the solenoid together with the rear member. When the booster operates as an automatic brake, a gentle brake operation which allows a precise control with a reduced brake output and a quick brake operation with an increased brake output can be simultaneously achieved in a preferred manner.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section of one embodiment of the invention;

FIG. 2 is an enlarged view of part shown in FIG. 1;

FIG. 3 is a schematic illustration of a phase of operation of the part shown in FIG.

2:

FIG. 4 is a schematic illustration of another phase of operation of the part shown in FIG. 2; and

FIG. 5 graphically shows an output response of an automatic brake.

Claims

1. An automatic brake booster including a valve body slidably disposed in a shell, a power piston mounted on the valve body for partitioning the interior of the shell into a constant pressure chamber and a variable pressure chamber, a valve mechanism mounted on the valve body for switchably controlling a flow path through which a fluid is supplied to or discharged from the variable pressure chamber, an input shaft for switchably operating the valve mechanism, a solenoid mounted on the valve body for switchably operating the valve mechanism, an output shaft for externally transmitting an output from the power piston, and a reaction disc for transmitting a reaction from the output shaft to the valve mechanism; the valve mechanism comprising a vacuum valve seat formed on the valve body, a solenoid plunger slidably mounted in the valve body, an atmosphere valve seat formed on the solenoid plunger, a valve element which can be seated on the vacuum valve seat and the atmosphere valve seat, and a valve plunger slidably mounted on the valve body and coupled to the input shaft for displacing the solenoid plunger forwardly as the input shaft is driven forward to operate the valve mechanism, the solenoid having a magnetic path which is defined in part by the solenoid plunger and a holder mounted on the valve body and located forwardly of the solenoid plunger, the solenoid plunger being displaced forwardly as the solenoid is energized to operate the valve mechanism;

2. An automatic brake booster including a valve body slidably disposed in a shell, a power piston mounted on the valve body for partitioning the interior of the shell into a constant pressure chamber and a variable pressure chamber, a valve mechanism mounted on the valve body for switchably controlling a flow path through which a fluid is supplied to or discharged from the variable pressure chamber, an input shaft for switchably operating the valve mechanism, a solenoid mounted on the valve body for switchably operating the valve mechanism, an output shaft for externally transmitting an output from the power piston, and a reaction disc for transmitting a reaction from the output shaft to the valve mechanism; the valve mechanism comprising a vacuum valve seat formed on the valve body, a solenoid plunger slidably mounted in the valve body, an atmosphere valve seat formed on the solenoid plunger, a valve element which can be seated on the vacuum valve seat and the atmosphere valve seat, and a valve plunger slidably mounted on the valve body and coupled to the input shaft for displacing the solenoid plunger forwardly as the input shaft is driven forward to operate the valve mechanism, the solenoid having a magnetic path which is defined in part by the solenoid plunger and a holder mounted on the valve body and located forwardly of the solenoid plunger, the solenoid plunger being displaced forwardly as the solenoid is energized to operate the valve mechanism;

3. An automatic brake booster including a valve body slidably disposed in a shell, a power piston mounted on the valve body for partitioning the interior of the shell into a constant pressure chamber and a variable pressure chamber, a valve mechanism mounted on the valve body for switchably controlling a flow path through which a fluid is supplied to or discharged from the variable pressure chamber, an input shaft for switchably operating the valve mechanism, a solenoid mounted on the valve body for switchably operating the valve mechanism, an output shaft for externally transmitting an output from the power piston, and a reaction disc for transmitting a reaction from the output shaft to the valve mechanism; the valve mechanism comprising a vacuum valve seat formed on the valve body, a solenoid plunger slidably mounted in the valve body, an atmosphere valve seat formed on the solenoid plunger, a valve element which can be seated on the vacuum valve seat and the atmosphere valve seat, and a valve plunger slidably mounted on the valve body and coupled to the input shaft for displacing the solenoid plunger forwardly as the input shaft is driven forward to operate the valve mechanism, the solenoid having a magnetic path which is defined in part by the solenoid plunger and a holder mounted on the valve body and located forwardly of the solenoid plunger, the solenoid plunger being displaced forwardly as the solenoid is energized to operate the valve mechanism;