Fluid-pressure and analogous brake systems – Pulsation neutralizers
Patent
1998-02-23
2000-01-25
Graham, Matthew C.
Fluid-pressure and analogous brake systems
Pulsation neutralizers
138 30, B60T 848
Patent
active
060170999
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a vibration damper for damping fluid vibrations in a hydraulic, slip-controlled brake system for a motor vehicle.
One such vibration damper is already known (German Patent Disclosure DE 43 36 464 A1), having a circular, substantially flat diaphragm. A closure cap that retains the diaphragm in the housing bore acts as a fixed boundary wall for the hollow chamber, which through a bore in the cap communicates with the ambient air.
The vibration damper serves, in the drive slip control mode, to avert longitudinal vibration, caused by the pump type used in the brake system, of the brake fluid in the pump intake line, as well as to avoid vibration cavitation, so that the pump can supply an adequately large volumetric flow for a rapid pressure buildup in the wheel brake cylinders. Another goal of the vibration damper is to reduce the pressure surge that occurs in the line to the master cylinder when the drive slip control mode ends.
To achieve an adequate damping action, it is necessary to furnish sufficiently large spaces on both sides of the diaphragm, so that they can receive correspondingly large volumes of brake fluid and dispense them. The volume of these spaces depends essentially on the line volume between the master cylinder and the reciprocating piston pump, on the stroke volume and rpm of the reciprocating piston pump, and on the hydraulic elasticity of the system induced to vibrate by the pump. Since in modern brake systems the elements located between the master cylinder and the wheel brake cylinders, such valves, pumps, lines and the like, have undergone miniaturization of their structural volume and a tightly packed arrangement in a so-called hydraulic unit, primarily for the sake of saving weight and expense, difficulties arise structurally in disposing the known type of vibration damper, which requires a relatively large installation diameter, in the housing of the hydraulic unit.
ADVANTAGES OF THE INVENTION
The vibration damper of the invention has the advantage over the prior art that the volume required for the vibration damping extends over a chamber of small diameter and of corresponding axial length. This kind of shaping can typically be achieved without difficulties in a housing. Another advantage is that the requisite damping volume is furnished on both sides of the jacket wall of the shaped part forming the diaphragm. The support body advantageously assures that the shaped part will not collapse when pressure is imposed, yet nevertheless, with the aid of the groove in the side face, a sufficient compression volume with low rigidity is available. Finally, the fitting of the shaped part over the support body is advantageous upon assembly and in sealing in the bore of the housing.
By the provision disclosed herein, in cooperation with a flat extension end face and a dimensionally rigid bottom wall of the shaped part, an open communication is always achieved between the interior of the shaped part and the chamber of the extension.
With the refinement of the invention defined by hereinafter, it is advantageously attained that the jacket wall of the shaped part, on pressing against the side faces of the support body, conforms to the inside of the grooves, beginning at the foot of the support body. This prevents the inclusion of air bubbles between the jacket wall and the support body.
With the shaping of the bottom wall of the shaped part, the bore leading to the chamber in the support body is kept open in a simple way.
The provision defined in herein assures sealing among the support body, shaped part and housing bore, and the jacket wall of the shaped part is made taut and its bottom wall is kept in contact with the end face of the support body.
An advantage of the invention is that, a diversion of the hydraulic forces acting upon the support body to the housing is attained over a short distance.
To achieve an adequate damping effect in the intake-side pressure region, the chamber in the extension of the support body communicates with the ambient air.
REFERENCES:
patent: 5460438 (1995-10-01), Hellmann et al.
patent: 5820227 (1998-10-01), Sperd
Alaze Norbert
Haecker Juergen
Hofmann Dirk
Mittwollen Norbert
Pechtold Ulrich
Graham Matthew C.
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
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