Process for regulating a predetermined, changeable brake pressure in the wheel brakes of a braking system

• US 6,234,583 B1
• Filed: 02/09/1998
• Issued: 05/22/2001
• Est. Priority Date: 06/09/1995
• Status: Expired due to Fees

• Current Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Eckert, Alfred
• Primary Examiner(s): SCHWARTZ, CHRISTOPHER P
• Application Number:
  US08/973,235
• Time in Patent Office: 1,198 Days
• Field of Search: 701/70, 701/72, 701/83, 701/78, 303/3, 303/15, 303/140, 303/146, 303/DIG.1, 303/DIG.2, 364/426.016, 364/426.018, 364/426.028, 180/197
• US Class Current: 303/3
• CPC Class Codes: B60T 2270/204 hydraulic model
• CPC Class Codes: B60T 8/175 Brake regulation specially adapted to prevent excessive wheel spin during vehicle acceleration, e.g. for traction control safety devices for propulsion unit control responsive to, or preventing, skidding of wheels B60K28/16
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02

Abstract

The present invention relates to a method of adjusting a predetermined, variable braking pressure in the wheel brakes of a brake system, in which the input quantities which determine the braking pressure in the individual wheel brakes are ascertained in a control and data-processing system, and actuation times of hydraulic valves, setting signals of actuators, etc., are established. These input quantities preferably reproduce the pressure, the pressure fluid volume, or the wheel slip. The input quantities and their time derivatives are weighted for the individual wheels and added in a pressure controller. The sum is further processed in a non-linear transmission element. In consideration of the valve or actuator characteristic, a pressure fluid volume flow is ascertained from which actuation times or setting signals for the hydraulic valves or actuators, which control the pressure decrease and increase in the individual wheel brakes, are established in a valve actuation logic taking account of the valve or actuator characteristic.

Claims

1. A method of adjusting a predetermined, variable braking pressure in wheel brakes of a brake system, including the steps of:

establishing input quantities for determining a braking pressure in the individual wheel brakes in a control and data-processing system and control variables of elements by which the braking pressure is controlled;

input quantities which determine a braking pressure in the individual wheel brakes are ascertained in a control and data-processing system, and control variables of elements, by which the braking pressure is controlled, are established;

weighting the input quantity which determines the braking pressure and the time derivative of said input quantity for each individual wheel brake, and adding said input quantity and the time derivative of said input quantity for each individual wheel brake in a pressure controller to provide a sum;

the input quantity which determines the braking pressure and the time derivative of this input quantity is weighted for each individual wheel brake and the weighted quantities are added in a pressure controller;

communicating said sum to a non-linear transmission element and determining a pressure fluid volume flow from said sum by way of said non-linear transmission element as a function of a valve characteristic; and

the sum is sent to a non-linear transmission element, wherein a pressure fluid volume flow is determined from the sum by way of the non-linear transmission element in dependence on the characteristic of the elements; and

establishing activation times of the elements controlling the pressure increase and decrease as a function of the determined pressure fluid volume flow and the valve characteristic;

establishing actuation times of the elements controlling the pressure increase and the pressure decrease is established as a function of the determined pressure fluid volume flow and the element characteristic.

2. The method as claimed in claim 1, wherein the braking pressure and the time derivative of the braking pressure are determined and sent to the pressure controller as input quantities which define the braking pressure.

3. The method as claimed in claim 1, wherein a pressure fluid volume and the time derivative of the pressure fluid volume is determined and sent to the pressure controller as input quantities which define the braking pressure.

4. The method as claimed in claim 1, wherein a wheel slip and the time derivative of the wheel slip is determined and sent to the pressure controller as input quantities which define the braking pressure.

5. The method as claimed in claim 1, wherein a switch selected from the group consisting of a two-position switch and three-position switch is used as a non-linear transmission element.

6. The method as claimed in claim 1, wherein a three-position switch including a proportional band is used as a non-linear transmission element.

7. The method as claimed in claim 1, wherein a switch including a change-over hysteresis is used as a non-linear transmission element.

8. The method as claimed in claim 1, including a distribution logic that controls the valve switching times of the opening and closing of the hydraulic valves controlling the braking pressure, wherein said valve switching times are established according to the relation $\Delta$



 



Tauf/ab=QQn

 



auf/ab*To

wherein Q is the required pressure fluid volume flow determined by the transmission element;

Q_n is the maximum possible volume flow; and

T_o is the time basis of the control system.

9. The method as claimed in claim 1, wherein the characteristic behavior of the valves is reproduced by a valve characteristic pattern which provides the valve characteristic values for the non-linear transmission element and for a distribution logic.

10. A method for controlling the driving stability of a vehicle, including the steps of:

determining input quantities responsive to a steering angle and a vehicle speed using a vehicle reference pattern established by operands and algorithms;

converting the input quantities into a nominal yaw angle value;

calculating the difference between the nominal yaw angle value and an actual yaw angle value and evaluating said difference according to a predetermined control algorithm functioning as a control law;

generating control quantities;

calculating torque quantities from said control quantities;

processing said toque quantities to effectuate an adjustment signal, wherein said adjustment signal is selected from the group consisting of (i) adjusting the amount of pressure to be adjusted in individual wheel brakes and (ii) determining a corresponding quantity which causes an additional yawing torque that makes a measured yawing value approach the nominal yawing angle value,

sending said adjustment signal to a distribution logic, wherein a pedal force exerted by a vehicle driver and the actual braking pressure or an approximated value thereof are considered,

emitting input quantities to determine the braking pressure in the individual wheel brakes, and sending the input quantities and the time derivative of the input quantities to a pressure controller.

11. The method as claimed in claim 10, wherein the pressure controller weights each input quantity determining the braking pressure and the time derivative of each input quantity;

adds each input quantity and the time derivative of each; and

sends the sum to a non-linear transmission element wherein the pressure fluid volume flow is determined, and wherein in a valve actuation times of pressure-increase valves in a pressure-increase path and pressure-decrease valves in a pressure-decrease path are established as a function of the determined volume flow and the respective maximum values of pressure fluid passage in the pressure-increase path and the pressure-decrease path.

12. The method as claimed in claim 10, wherein the pressure controller generates output signals and such output signals are compared in a priority circuit with signals produced by other part systems of the system and are evaluated in consideration of a predetermined priority.