Brake System for a Land Vehicle and Method for Controlling the Brake System

摘要

A hydraulic brake system for a land vehicle includes a brake pedal; a wheel brake; and a master brake cylinder connected to the brake pedal by a brake booster and a pump. The outlet of the pump is connected to the wheel brake by a supply line and the inlet is connected to the wheel brake by a return line. The pump moves hydraulic fluid to the wheel brake. A temporary store is connected to the inlet of the pump and the wheel brake by the return line. A pressure reduction valve, arranged in the return line of the wheel brake, has a throttling effect in the open state. A control unit compensates for the difference between a total braking torque specified by the brake pedal and a generating braking torque provided by an electric machine by setting the hydraulic braking torque during a regenerative braking process of the vehicle.

主权项

1. Hydraulic brake system for a land vehicle, wherein the hydraulic brake system is adapted to enable a regenerative braking operation of said land vehicle, said system having:
a brake pedal which can be actuated by the driver; a wheel brake which is associated with a wheel of the land vehicle; a master brake cylinder which is connected to the brake pedal via a brake booster and is adapted to displace hydraulic fluid into the wheel brake when the brake pedal is actuated; a pump, the output of which is connected to the wheel brake via a feed line and the input of which is connected to the wheel brake via a return line, wherein the pump is adapted to convey hydraulic fluid to the wheel brake; a temporary store which is connected, via the return line, to the input of the pump and to the wheel brake; a pressure reduction valve which is arranged in the return line of the wheel brake and has a throttling effect in the open state; a control unit which is adapted to compensate, during a regenerative braking operation of the land vehicle, for the difference between a total braking torque set by the driver by actuation of the brake pedal and a generating braking torque provided by an electric machine by adjustment of the hydraulic braking torque, wherein the control unit, for the purpose of adjusting the hydraulic braking torque:
ascertains a difference between the total braking torque and the generating braking torque;ascertains a necessary braking pressure from the difference of the total braking torque and the generating braking torque;estimates volume flows via the pressure reduction valve on the basis of the switching state and the throttling effect of said pressure reduction valve;ascertains an intake of volume by the temporary store on the basis of the estimated volume flow;estimates a current braking pressure on the basis of a displacement of volume, which displacement corresponds to an actuating travel of the brake pedal, from the master brake cylinder to the wheel brake, and on the basis of the ascertained intake of volume by the temporary store; andsets a switching state for the pressure reduction valve in dependence upon the ascertained necessary braking pressure and the current braking pressure.