Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Patent
1997-10-03
2000-03-07
Schwartz, Chris
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
3031132, B60T 844, B60T 834
Patent
active
060330376
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a brake system for automotive vehicles with an actuating unit including a pneumatic brake power booster and a master brake cylinder connected downstream of the booster and connected to wheel brakes, wherein a control valve of the brake power booster is operable irrespective of the driver's wish by a solenoid having an armature that is in force-transmitting connection with one of the sealing seats of the control valve, a deceleration controller to which a signal representative of the vehicle deceleration is sent as an input quantity, wherein the output quantity of the controller influences the position of the control valve and is compared in a first summer with a signal representative of the actual condition of the control valve, and the control difference representative of the result of the comparison is sent to a position controller, which influences the position of the control valve, and the output quantity of which corresponds to an electric current to be supplied to the solenoid.
International patent application WO 95/03196 discloses a brake system of this type. The control difference between a deceleration wish signal and an actual deceleration signal, which corresponds to a quantity proportional to the brake force (brake force nominal or actual value), is sent as an input quantity to the deceleration controller of the above mentioned prior art brake system. In particular the braking pressure, the pressure differential acting in the pneumatic brake power booster, or the rotational speed of at least one vehicle wheel may be used as possible physical parameters. In response to the physical parameter chosen, the deceleration controller is configured as a braking pressure controller, pneumatic differential pressure controller, or wheel deceleration controller. Corresponding to the control difference and the demanded nominal value gradient, the deceleration controller calculates the desired position for the armature of the solenoid which directly influences the opening condition of the control valve of the brake power booster.
The output signals of the deceleration controller, in consideration of sensed actual values for the armature position and the current supplied to the solenoid, are further processed in a position controller having an output quantity which represents the control quantity for actuating the solenoid.
In particular the following problems occur in the state of the art position control of the solenoid: to the non-linear progressive interrelation between the magnetic force and the process parameters `magnetic current` and `armature position`. This means a structurally inherent instability for the solenoid. valve (control valve characteristic curve) is non-linear to a great degree and, in addition, responsive to position and vacuum. After the control valve is opened, the counterforce will be reduced to such an extent as to exert an additional destabilizing effect on the solenoid.
OBJECT OF THE INVENTION
Therefore, an object of the present invention is to disclose measures permitting a control with the following characteristics: msec) directly on the brake power booster
Further, the position controller must be able to accurately position the armature of the solenoid and, thus, a sleeve which carries the mentioned control valve sealing seat even in the unstable range of the brake system characteristics.
SUMMARY OF THE INVENTION
According to the present invention, this object is achieved because the position controller is a comparator connected upstream of which is a second summer wherein the output quantity of the deceleration controller is compared with a weighted signal representative of the speed of the armature, the output quantity of the deceleration controller corresponds to the position of the armature relative to the housing of the solenoid, and the travel signal representative of the actual condition of the control valve represents the actual position of the armature in relation to the housing of the solenoid.
Further
REFERENCES:
patent: 5496099 (1996-03-01), Resch
patent: 5725291 (1998-03-01), Michels
ITT Manufacturing Enterprises Inc.
Schwartz Chris
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