Device and method for adjusting the pedal characteristic curve of a hybrid braking system during modified braking-force distribution

• US 20050017574A1
• Filed: 05/03/2004
• Published: 01/27/2005
• Est. Priority Date: 05/02/2003
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Weiberle, Reinhard, Schumann, Frank
• Granted Patent: US 7,040,721 B2
• Time in Patent Office: Days
• US Class Current: 303/3
• CPC Class Codes: B60T 13/12 the fluid being liquid
• CPC Class Codes: B60T 13/741 acting on an ultimate actuator
• CPC Class Codes: B60T 2220/04 Pedal travel sensor, stroke sensor; Sensing brake request
• CPC Class Codes: B60T 2270/608 Electronic brake distribution (EBV/EBD) features related thereto
• CPC Class Codes: B60T 8/1766 Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle
• CPC Class Codes: B60T 8/267 for hybrid systems with different kind of brakes on different axles

Abstract

A braking system for a vehicle is described, including a hydraulic service braking system and an electric service braking system having wheel brakes, to which braking pressure is applied when a brake pedal is operated. To maintain essentially constant vehicle braking behavior during a change in the braking-force distribution between the hydraulic and the electric service braking systems, it is proposed to provide a control unit, which is capable of varying the braking-force distribution and to equip the hydraulic service braking system with a braking pressure modulator that is controlled by the control unit and is able to effect a variable braking-force distribution as a function of the control by the control unit.

Claims

1. A braking system for a motor vehicle, comprising:

a hydraulic service braking system;

an electric service braking system including wheel brakes to which braking pressure is applied when a brake pedal is operated;

a control unit capable of changing a braking-force distribution between the electrical service braking system and the hydraulic service braking system; and

a braking pressure modulator situated in the hydraulic service braking system for boosting the braking pressure acting on hydraulic brakes, wherein;

the control unit is able to control an actuating element in the electric service braking system as well as the braking pressure modulator to change the braking-force distribution.

2. The braking system as recited in claim 1, wherein:

the control unit controls the braking pressure modulator in such away that a ratio between a pedal force and a total braking torque remains essentially constant when the braking-force distribution is changed.

3. The braking system as recited in claim 1, wherein:

the braking pressure modulator includes an adjustable vacuum brake booster, a boost level of which may is adjustable via the control unit.

4. The brake system as recited in claim 3, wherein:

the brake booster includes a controllable valve for aerating a working chamber of the brake booster that is controllable by the control unit.

5. The braking system as recited in claim 1, wherein:

the braking pressure modulator includes a hydraulic unit that is capable of varying the braking pressure acting on the hydraulic brakes as a function of a control by the control unit.

6. The braking system as recited in claim 5, wherein:

the hydraulic unit includes a controllable hydraulic pump that is controllable by the control unit.

7. The braking system as recited in claim 1, further comprising:

a device provided in the hydraulic service braking system and via which a ratio between a pedal travel of the brake pedal and the braking pressure acting on the hydraulic wheel brakes is adjustable.

8. The braking system as recited in claim 7, wherein:

the control unit controls the device for adjusting the pedal travel in such a way that a ratio between the pedal travel and a total braking torque remains essentially constant during a change in the braking-force distribution.

9. A method for operating a braking system, including a hydraulic service braking system and an electric service braking system having wheel brakes, comprising:

applying a braking pressure to the wheel brakes when a brake pedal is operated; and

causing a control unit to control a braking pressure modulator situated in the hydraulic service braking system and the electric service braking system in such a way that a ratio between a total vehicle braking torque and at least one of a pedal force and a pedal travel remains essentially constant when a braking-force distribution is changed between the hydraulic service braking system and the electric service braking system.