Motors: expansible chamber type – Working member position feedback to motive fluid control – Follower type
Patent
1990-12-17
1994-06-14
Look, Edward K.
Motors: expansible chamber type
Working member position feedback to motive fluid control
Follower type
92 99, F15B 910
Patent
active
053200241
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a vacuum brake force booster for use with automotive vehicles, comprising a vacuum housing which, through an axially movable partition to which pneumatic differential pressure may be applied, is sealingly subdivided into a vacuum chamber and a working chamber, with the movable partition being formed by a metal diaphragm plate and a rolling diaphragm adjacent thereto, and comprising a mechanically operable control valve for establishing a communication between the working chamber and the vacuum chamber or the atmosphere, respectively, the axially movable control housing of which is formed of a thermoplastic material and comprises a supporting face for the radially inward area of the diaphragm plate exhibiting an annular curvature, as well as a radial groove to accommodate the radially inward area of the rolling diaphragm.
BACKGROUND OF THE INVENTION
A brake force booster of the afore-described type and the way of fixing the movable wall thereof to the control valve housing is known to those skilled in the art. The diaphragm plate of such brake booster, in the radially inward area thereof, comprises a circumferential curvature seated on a rectangular support surface formed on a control valve housing such that in case of a pressure load on the movable partition wall, a rolling movement of the diaphragm plate may take place. The support surface of the diaphragm plate is followed by a groove of rectangular cross-section accommodating a bead correspondingly shaped in the radial-inward area of the rolling diaphragm.
However, in prior known brake force boosters of this type, in predetermined operating conditions, the rolling diaphragm is likely to be detached, thereby substantially affecting the operating safety of the system. This danger occurs especially as a result of stagnation pressure in the brake system through actuation thereof without vacuum and with closed check valve outlets, respectively, since the view of the pressure prevailing in the brake force booster housing force components are formed which act in the radial direction, tending to withdraw the annular bead of the rolling diaphragm from the circumferential groove of the control valve housing and to displace the diaphragm plate in a direction opposite the actuating force, thereby forcing the annular bead out of the groove. This will result in the failure of the brake system the boosting force of which no longer can be built up.
Equally disadvantageous are the material tensions or stresses in the control valve housing particularly high in view of the rectangular configuration of the support face of the diaphragm plate and of the groove accommodating the rolling diaphragm, which tensions, in predetermined circumstances, are likely to destroy the control valve housing.
BRIEF DESCRIPTION OF THE INVENTION
It is, therefore, the object of the present invention to avoid the afore-described disadvantages and to so configure a vacuum brake force booster exhibiting the generic features as to ensure the operating safety thereof, maintaining the type of design and systems characteristics and using the components available.
The problem underlying the invention is solved in that both the contour of the supporting surface and that of the radially inward area (sealing bead (42)) of the rolling diaphragm (18) conforms to the curved shape of the radial-inward area (curvature (34)) of the diaphragm plate (19), and that the groove with the axial dimension thereof extends into the bearing area of the diaphragm plate on the supporting surface.
The afore-described measures will ensure an improved off-rolling of the diaphragm plate on the control valve housing when transmitting the boosting force, a substantial reduction of the material tensions or stresses in the clamping area of the movable partition wall, and a substantially simplified assembly.
The groove, preferably in the area disposed below the supporting face of the diaphragm plate, exhibits a curvature which, in cross-section, is of a circular-segment shape and cooperates wit
REFERENCES:
patent: 2989035 (1961-06-01), Stelzer
patent: 4043251 (1977-08-01), Ohmi
patent: 4453450 (1984-06-01), Horsting
patent: 4587889 (1986-05-01), Ohki et al.
patent: 4671167 (1987-06-01), Endo et al.
patent: 4765226 (1988-08-01), Bequet et al.
patent: 4800799 (1989-01-01), Nishii
patent: 4803912 (1989-02-01), Nishii
patent: 5007329 (1991-04-01), Toepperwien
Graichen Kai-Maichael
Wagner Wilfried
Alfred Teves GmbH
Lewis J. Gordon
Look Edward K.
Nguyen Hoang
Seitter Robert P.
LandOfFree
Vacuum brake force booster for automotive vehicles does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vacuum brake force booster for automotive vehicles, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vacuum brake force booster for automotive vehicles will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1240578