US 5,769,509 A · Brake unit for motor vehicles with electric drive

Abstract

A brake unit for motor vehicles with electric drive with a hydraulic pressure transducer and hydraulic friction brakes to increase the brake effect applied by the electric drive motor. The cooperation of the electric drive motor with the hydraulic friction brakes is controlled by an electronic controller. To increase the reliability of operation of the brake unit by making possible the buildup of hydraulic pressure in the friction brakes associated with the driven axle in the case of a failure of the electronic controller or of the entire electric system of the vehicle, the pressure transducer is arranged as a two-circuit main brake cylinder, to the first pressure space of which the friction brakes acting on the nondriven axle, and to the second pressure space of which the friction brakes acting on the driven axle are connected, wherein the connection between the second pressure space and the friction brakes acting on the driven axle is by at least one shut-off valve, which can be switched over electrically and is open in the currentless state.

Claims17

Dependent claims

Brake unit for motor vehicles with an electric drive motor and with a driven axle and a nondriven axle, comprising

a) a two-circuit brake pressure actuator, which can be actuated by means of a brake pedal, and to which friction brakes acting on the driven axle as well as on the nondriven axle are connected;
b) an electro-regenerative brake system, which uses the electric drive motor of the motor vehicle for braking and energy recovery;
and
c) an electronic controller,which receives information on the state of actuation of said brake pressure actuator, the brake pressure brought about by the actuation, and the velocity of the vehicle, and evaluates it for controlling both the electric drive motor and said friction brakes acting on the driven axle,
characterized in that:
(a) said friction brakes acting on the nondriven axle are connected to a first pressure space of said brake pressure actuator, and said friction brakes acting on the driven axle are connected to a second pressure space of said brake pressure actuator, wherein the connection between said second pressure space and said friction brakes acting on the driven axle is performed via at least one shut-off valve, which can be switched over electrically and is open in the currentless state, and said friction brakes acting on the driven axle can be connected to a hydraulic energy supply unit or auxiliary pressure source via pressure control units, which can be switched over electrically;
and
(b) a hydraulic connection, which can be shut off by means of a second shut-off valve, which can be switched over electrically, is provided between said friction brakes acting on the driven axle.

5 more elements

A brake unit for a motor vehicle having an electric drive motor, a driven axle and a nondriven axle, said brake unit comprising:

a brake pedal;
a brake pressure actuator actuated by said brake pedal and having a first pressure space and a second pressure space;
a first pair of friction brakes adapted to act on the driven axle;
first connecting means for connecting said first pair of friction brakes to said second pressure space of said brake pressure actuator, said first connecting means including at least one electrically switchable shut-off valve which is open in the currentless state, a hydraulic connection between said friction brakes acting on the driven axle, and a second electrically switchable shut-off valve for closing said hydraulic connection;
a second pair of friction brakes adapted to act on the nondriven axle and connected to said first pressure space of said brake pressure actuator;
a hydraulic energy supply unit;
second connecting means for connecting said second pair of friction brakes to said hydraulic energy supply unit, said second connecting means including first and second electrically switchable pressure control units;
an electro-regenerative brake system for braking and energy recovery;
and
an electronic controller responsive to information on:
(a) the state of actuation of the said brake pressure actuator,
(b) the brake pressure brought about by the actuation, and
(c) the velocity of the vehicle,
for evaluating said information and for controlling:
(a) said friction brakes acting on the driven axle, and
(b) the electric drive motor to actuate said electro-regenerative brake system.

13 more elements

A process for checking the ability of a hydraulic energy supply unit to operate in a brake unit of a motor vehicle having an electric drive motor, a driven axle, and a nondriven axle, and said brake unit having:

a brake pedal,
a brake pressure actuator actuated by said brake pedal and having a first pressure space and a second pressure space,
a first pair of friction brakes adapted to act on the driven axle,
first connecting means for connecting said first pair of friction brakes to said second pressure space of said brake pressure actuator, said first connecting means including at least one electrically switchable shut-off valve which is open in the currentless state,
a second pair of friction brakes adapted to act on the nondriven axle and connected to said first pressure space of said main brake cylinder,
a hydraulic energy supply unit including:
(a) a first circuit,
(b) a hydraulic valve arrangement for connecting said first circuit to said friction brakes acting on the nondriven axle,
(c) a second circuit, and
(d) a high-pressure accumulator connected to said friction brakes acting on the driven axle by said pressure control units,
second connecting means for connecting said second pair of friction brakes to said hydraulic energy supply unit, said second connecting means including first and second electrically switchable pressure control units,
an electro-regenerative brake system for braking and energy recovery, and
an electronic controller responsive to information on:
(a) the state of actuation of the said brake pressure actuator,
(b) the brake pressure brought about by the actuation, and
(c) the velocity of the vehicle,
for evaluating said information and for controlling:
(a) said friction brakes acting on the driven axle, and
(b) the electric drive motor to actuate said an electro-regenerative brake system,
said process including the steps of:
(a) measuring the charging time during each charging process,
(b) comparing the measured charging time with a predetermined desired charging time, and
(c) displaying a deviation of the difference between the measured charging time and the predetermined desired charging time from a preset difference.

20 more elements

Dependencies are inferred from the claim text.

Brake unit for motor vehicles with electric drive

Life of this patent

Brake unit for motor vehicles with electric drive

Life of this patent

Abstract

Claims17