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US 5,312,170 AGranted
Anti-lock brake system
AssigneeRobert Bosch GmbH
InventorsAndreas Erban, Harald Michi, Matthias Volkert, Chi-Thuan Cao
Life of this patent
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Abstract
The ABS described has phases of regulation to a setpoint slip value and phases of brake pressure control in the case of instabilities of the wheel. The setpoint slip is determined from a fixed maximum friction coefficient .mu.max and the brake pressure introduced is determined from the slip value when .mu.max occurs.
Claims18
Anti-lock brake system for a vehicle wheel, comprising:
- means for determining a wheel speed VR and a brake pressure PB at a wheel brake of a vehicle wheel;
- means, responsive to the wheel speed VR and a reference speed VRef, for forming slip actual values S and wheel deceleration values BR;
- a slip regulator means for using the slip actual values S to regulate the brake pressure PB at the wheel brake;
- control means for causing regulating phases and brake pressure control phases to alternate;
- means for continuously determining a friction coefficient .mu. from the brake pressure PB and the wheel deceleration values BR;
- means for determining during each regulating phase a maximum value .mu.max of the friction coefficient and the slip value SK when the maximum value of the friction coefficient is reached;
- means for using the slip value SK during each regulating phase to form a somewhat smaller slip setpoint value Sdes. which is specified as the slip setpoint value for the slip regulator means in the following regulating phase;
- and said control means is responsive to the wheel slip S rising during the regulating phases above a predetermined value SB, for switching the system over to a brake pressure control phase, during which said control means controls a pressure control means to initially introduce a reduced brake pressure Pmin and then to introduce an increased brake pressure PS relative to Pmin after the slip S has fallen below the below SB, and for subsequently brining the slip regulator into effect with the new setpoint slip Sdes. when the slip S becomes smaller than SK.
5 more elements
A method of controlling an anti-lock brake system for a vehicle wheel comprising:
- determining a wheel speed VR and a brake pressure PB at a wheel brake of a vehicle wheel;
- forming slip actual values S and wheel deceleration values BR from the wheel speed VR and a reference speed VRef;
- using the slip actual values S to control a slip regulator to regulate the brake pressure PB at the wheel brake;
- causing regulating phases and brake pressure control phases to alternate by:
- during the regulating phases, continuously determining a friction coefficient .mu. from the brake pressure PB and the wheel deceleration values BR;
- determining during each regulating phase a maximum value .mu.max of the friction coefficient and the slip value SK when the maximum value of the friction coefficient is reached;
- using the slip value SK during each regulating phase to form a somewhat smaller slip setpoint value Sdes. which is specified as a slip setpoint value for a slip regulator in the following regulating phase;
- if the wheel slip S rises during the regulating phases above a predetermined value SB, switching the system over to brake pressure control, during which a reduced brake pressure Pmin initially is introduced and then an increased brake pressure PS relative to Pmin in introduced after the slip S has fallen below the value SB;
- and, subsequently bringing the slip regulator into effect with the new setpoint slip Sdes. when the slip S becomes smaller than SK.
6 more elements
Dependencies are inferred from the claim text.