Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1998-01-26
2000-02-01
Schwartz, Chris
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
3031141, B60T 1372, B60T 1366
Patent
active
060194405
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION
The present invention relates to a device and a method of adjusting a variable boosting factor of a controlled, independently activatable brake power booster which boosts an input force and converts it into a deceleration of an automotive vehicle.
The boosting factor i, i.e. the ratio between input force and output force, is invariably adjusted in conventional brake power boosters. This factor is fixed in the development of the brake power booster within limits predefined by construction. The output force of the brake power booster acts upon a master brake cylinder and thereby generates a braking pressure which is virtually proportional to the output force, thus providing deceleration of the automotive vehicle.
A disadvantage of brake systems equipped with a brake power booster of this type is that the ratio between pedal force and automotive vehicle deceleration is not constant. The ratio is subject to variable parameters such as vehicle mass, coefficients of friction of linings, and rates of hydraulic efficiency. The driver must acclimate to these variations in the braking behavior. To relieve the driver, it is desirable to adapt the brake system so that a constant ratio between the pedal force of the driver and the vehicle deceleration can be adjusted. This necessitates a brake power booster with a variable boosting factor which permits compensating the influence of variable parameters also during operation.
Further, independently activatable brake power boosters are disclosed in the art, for example, in German patent application No. 43 24 688.5. This publication discloses a vacuum brake power booster wherein a third sealing seat on the poppet valve renders it possible to effect an independent assist braking operation irrespective of the activation by the driver.
SUMMARY OF THE INVENTION
An object of the present invention is to disclose a device and an appropriate method which permits operating a prior art brake power booster with a variable boosting factor.
According to the present invention, this object is achieved by a device including a force sensor for measuring the input force, a variable amplifier for amplifying the output signal of the force sensor by the boosting factor, and an electrical signal-adapting unit for generating a nominal pressure value from the output signal of the booster. It is favorable that the input and output quantities of the system are directly taken into account for the control so that inaccuracies in the system, a plurality of adding, clearance-induced quantities of mechanic components, etc., are taken into account automatically, without the necessity to know them in detail. The exact design of the brake power booster is of secondary importance because the controller controls only the output value, irrespective of how the value is adjusted. The pedal force is introduced into the brake power booster, on the one hand, directly as a mechanical input quantity which is boosted by the invariably predetermined boosting ratio of the brake power booster. On the other hand, the pedal force is introduced into the controller by way of the variable amplification of a nominal value. The result is that the pedal force is boosted at least by the invariably adjusted boosting ratio of the brake power booster, which is possibly overridden by the nominal pressure value on the controller that is amplified to a variably higher amount.
The brake power booster is independently activatable, i.e., irrespective of the pedal application and, thus, irrespective of the driver's wish. When the vacuum brake power booster has a slidable third sealing seat, as disclosed in German patent application No. 43 24 688.5, the solution disclosed, which founds on controlling the boosting factor, has the advantage (compared to an equally possible control of the brake power booster by adjusting the position of the third sealing seat in relation to the control housing) that neither an extremely high accuracy of positioning of the third sealing seat nor an addi
REFERENCES:
patent: 4743072 (1988-05-01), Brearley
patent: 4812777 (1989-03-01), Shivac
patent: 5372409 (1994-12-01), Farr
patent: 5427442 (1995-06-01), Herbel
patent: 5505526 (1996-04-01), Michels
Balz Jurgen
Bill Karlheinz
Bohm Jurgen
Scherer Peter
Semsch Martin
ITT Manufacturing Enterprises Inc.
Schwartz Chris
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