Patent ID: 6324845
Filing Date: 2001-12-04
Classification: B60T

Abstract:
A self contained, supplemental vacuum assist unit for use with a vacuum brake booster and a source of vacuum in a motor vehicle, the vacuum brake booster having a vacuum chamber and a working pressure chamber, the unit comprising, in combination:a housing defining an assist vacuum chamber having an opening with a fitting adapted for connection to the vacuum chamber of the vacuum brake booster and further defining an air exhaust chamber having an opening with a fitting adapted for connection to the source of vacuum, the assist vacuum chamber and the air exhaust chamber being separated by a wall;a first opening in the wall having a first unidirectional flow valve permitting air flow only from the assist vacuum chamber to the air exhaust chamber;an electric motor driven air pump in the housing having an inlet from the assist vacuum chamber and an outlet to the air exhaust chamber, the pump having associated therewith a second unidirectional flow valve permitting air flow through the air pump only from the assist vacuum chamber to the air exhaust chamber;an electric circuit board within the assist vacuum chamber having a Hall effect sensor thereon so as to sense a magnetic field of a magnet adjacent the sensor and a control circuit thereon responsive to the Hall effect sensor to control operation of the electric motor driven air pump;the housing further defining an opening from the assist vacuum chamber to a source of air at atmospheric pressure, the opening being closed by a flexible diaphragm;a plunger activated by the diaphragm for axial movement therewith due to changes in pressure across the diaphragm; anda permanent magnet affixed to the plunger adjacent the Hall effect sensor, the permanent magnet generating a magnetic field sensed by the Hall effect sensor and the Hall effect sensor being responsive thereto to generate a signal changing with the position of the permanent magnet and thus with the pressure across the diaphragm.