Brake System for Motor Vehicles. and Method for Operating the Brake System

• US 20140152085A1
• Filed: 04/16/2012
• Published: 06/05/2014
• Est. Priority Date: 05/05/2011
• Status: Active Grant

• Current Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Original Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Inventors: Biller, Harald, Drumm, Stefan A., Besier, Marco, Linkenbach, Stefen, Scharf, Christopher
• Granted Patent: US 9,308,905 B2
• Time in Patent Office: Days
• US Class Current: 303/10
• CPC Class Codes: B60T 13/142 Systems with master cylinder
• CPC Class Codes: B60T 13/161 Systems with master cylinder
• CPC Class Codes: B60T 13/58 Combined or convertible systems
• CPC Class Codes: B60T 13/588 both fluid and mechanical assistance or drive
• CPC Class Codes: B60T 13/66 Electrical control in fluid-pressure brake systems
• CPC Class Codes: B60T 13/686 in hydraulic systems or parts thereof
• CPC Class Codes: B60T 8/4081 Systems with stroke simulating devices for driver input B60T8/4077 takes precedence
• CPC Class Codes: B60T 8/441 using hydraulic boosters B60T8/445, B60T8/446, B60T8/447 take precedence

Abstract

A motor vehicle brake system actuated in brake-by-wire and fallback operating modes, having a brake master cylinder, brake circuits, a pressure medium storage vessel, a brake pedal, a separating valve for separating the brake circuit into a first section connected to the separating valve the master cylinder, and a second section connected to the separating valve and the wheel brakes. A first pressure provision device has a piston actuated by an actuator, a simulation device connected by a simulator release valve to the master cylinder for a pleasant brake pedal feel in the brake-by-wire operating mode. A first electronic control and regulating unit actuates the first pressure provision device, the separating valves and the simulator release valve. A second pressure provision device has a suction connector and a pressure connector per brake circuit being connected to the inlet of the separating valve.

Claims

1. A brake system for motor vehicles, which brake system can be actuated in a brake-by-wire operating mode both by the vehicle driver and independently of the vehicle driver, and is preferably operated in the brake-by-wire operating mode, and can be operated in at least one fallback operating mode, comprising;

a brake master cylinder (2) with a housing (21) and two pistons (15, 16) which delimit two pressure spaces (17, 18) in the housing (21), the pressure spaces (17, 18) each assigned to one of the two brake circuits (I, II) with wheel brakes (8, 9, 10, 11),

a pressure medium storage vessel (4) for storing a pressure medium with at least two chambers which are assigned to the two brake circuits (I, II),

a brake pedal (1) which is coupled to the brake master cylinder for actuating the brake master cylinder (2),

an electrically operable normally open, separating valve (23a, 23b) per each of the two brake circuits (I, II) for separating each brake circuit into two sections including a first section (22a, 22b) which is connected to an inlet connector of the separating valve and being connected to the brake master cylinder (2), and a second section (13a, 13b) which is connected to an outlet connector of the separating valve being connected to the wheel brakes,

a first electrically controllable pressure provision device (5) which is formed by a cylinder and a piston arrangement, the piston (36) actuated by an electromechanical actuator (35),

a simulation device (3) which can be connected hydraulically by means of an electrically actuable simulator release valve (32) to at least one of the pressure spaces (17) of the brake master cylinder (2) and imparts a pleasant haptic brake pedal feeling to the vehicle driver in the brake-by-wire operating mode,

a first electronic control and regulating unit (12) for actuating the first pressure provision device (5), the separating valves (23a, 23b), and the simulator release valve (32), and

a second electrically controllable pressure provision device (49, 149, 249) with a suction connector and a pressure connector for each of the two brake circuits (I, II), the pressure connector being connected to the inlet connector of the separating valve (23a;

23b) which is assigned to each of the two brake circuits (I;

II).

2. The brake system as claimed in claim 1, further comprising in that, for each of the two brake circuits (I, II), the suction connector of the second pressure provision device (49, 149, 249) is connected to the pressure space (17, 18) directly without a valve being connected in between, with the result that the second pressure provision device (49, 249) is arranged hydraulically between the pressure space and the separating valve (23a, 23b).

3. The brake system as claimed in claim 2, further comprising in that, for each of the two brake circuits (I, II), the suction connector is connected to the pressure connector via an electrically actuable normally open, regulating valve (47a, 47b, 247a, 247b), which can be activated in an analog manner and with a nonreturn valve (48a, 48b, 248a, 248b) is connected in parallel which makes a flow of the pressure medium from the pressure space (17, 18) of the brake master cylinder (2) to the separating valve (23a, 23b) possible, independently of the switching state of the regulating valve (47a, 47b, 247a, 247b).

4. The brake system as claimed in claim 1, further comprising in that a pressure detection device (45, 245) is provided which detects the pressure of the pressure medium at a suction connector of the second pressure provision device (49, 249), which suction connector is connected to one of the pressure spaces (17, 18) of the brake master cylinder (2).

5. The brake system as claimed in claim 1, further comprising in that, for each of the two brake circuits (I, II), the suction connector is connected to a pressure medium container (150) directly without a valve being connected in between.

6. The brake system as claimed in claim 5, further comprising in that, for each of the two brake circuits (I, II), the suction connector is connected to the pressure connector via an electrically operated normally closed, overflow valve (147a, 147b).

7. The brake system as claimed in claim 1, in that the second pressure provision device (49, 149, 249) comprises at least two hydraulic pumps (42;

280a, 280b) which are driven by an electric motor (43), pressure connectors of the first and the second pump being connected to the inlet connector of the associated separating valve (23a, 23b).

8. The brake system as claimed in claim 1 in that the second pressure provision device (249) comprises at least four hydraulic pumps (280a, 280b, 281a, 281b) which are driven by an electric motor (43), the pressure connectors of the pumps being to the inlet connector of the associated separating valve (23a;

23b).

9. The brake system as claimed in claim 8, further comprising in that the suction connectors of a third and a fourth pump of the four pumps are connected to the pressure medium storage vessel (4) under atmospheric pressure directly without a valve being connected in between.

10. The brake system as claimed in claim 1 further comprising in that, for each of the two brake circuits, a pressure detection device (145, 250) is provided which detects the pressure at the pressure connector of the second pressure provision device (149, 249).

11. The brake system as claimed in claim 3 further comprising in that the second pressure provision device (49, 149, 249) the pressure detection device or devices (45, 145, 245, 250) and the regulating valves (47a, 47b, 247a, 247b) or overflow valves (147a, 147b), and a second electronic control and regulating unit (39) for actuating the second pressure provision device (49, 149, 249), are arranged in an independent module (40, 140, 240).

12. The brake system as claimed in claim 1 further comprising an electrically operated normally closed, adding valve (26a, 26b) for each of the two brake circuits (I, II) for hydraulically connecting the first pressure provision device (5) to the brake circuit (I, II), an outlet connector of the separating valve (23a, 23b) and an outlet connector of the adding valve (26a, 26b) being connected via the brake circuit second section (13a, 13b) for each brake circuit.

13. A method for operating a brake system comprising the steps of providing a brake master cylinder (2) with a housing (21) and two pistons (15, 16) which delimit two pressure spaces (17, 18) in the housing (21), which pressure spaces (17, 18) are assigned to one of the two brake circuits (I, II) with wheel brakes (8, 9, 10, 11),

a pressure medium storage vessel (4) for a pressure medium with at least two chambers which are assigned to the two brake circuits (I, II),

a brake pedal (1) which is coupled to the brake master cylinder for actuating the brake master cylinder (2),

an electrically operated normally open, separating valve (23a, 23b) for each of the two brake circuits (I, II) for separating the brake circuits into two sections including a first section (22a, 22b) which is connected to an inlet connector of the separating valve being connected to the brake master cylinder (2), and a second section (13a, 13b) which is connected to an outlet connector of the separating valve being connected to the wheel brakes,

a first electrically controllable pressure provision device (5) which is formed by a cylinder and a piston arrangement, the piston (36) of which can be actuated by an electromechanical actuator (35),

a simulation device (3) which can be connected hydraulically by means of an electrically actuable simulator release valve (32) to at least one pressure space (17) of the brake master cylinder (2) and imparts a pleasant brake pedal haptic feeling to the vehicle driver in the brake-by-wire operating mode, and

a first electronic control and regulating unit (12) for actuating the first pressure provision device (5), the separating valves (23a, 23b) and the simulator release valve (32),

a second electrically controllable pressure provision device (49, 149, 249) with a suction connector and a pressure connector for each of the two brake circuits (I, II), the pressure connector per brake circuit being connected to the inlet connector of the separating valve (23a;

23b) which is assigned to the brake circuit (I;

II),

the pressure medium is sucked by means of the second electrically controllable pressure provision device (49, 149, 249) from one of the pressure spaces (17, 18) of the brake master cylinder (2) or from a pressure medium container (4, 150) and is fed into at least one of the brake circuits (I, II), if no pressure build-up or dissipation can be carried out by means of the first pressure provision device (5) and the vehicle driver actuates the brake pedal (1).

14. The method for operating a brake system as claimed in claim 13, further comprising in that the brake system is monitored for a leakage in the region of the second pressure provision device (49, 149, 249) or of the brake master cylinder (2), and in that, if a leakage is detected in one of the two brake circuits (I;

II), the associated separating valve (23a;

23b) is closed and a brake pressure build-up is carried out in the other of the brake circuits (II, I) by means of the first pressure provision device (5).