EP-4735307-A1 - METHOD FOR OPERATING A BRAKING SYSTEM OF A MOTOR VEHICLE, CONTROL DEVICE, HYDRAULIC BRAKING SYSTEM AND MOTOR VEHICLE

Abstract

The invention relates to a method for operating a braking system of a motor vehicle, wherein a hydraulic pressure in the braking system is monitored and, in the event of a pressure loss, an electric pressure generator is always controlled in such a way that the hydraulic pressure is increased. The invention also relates to an associated control device, an associated hydraulic braking system and an associated motor vehicle.

Inventors

• ULLRICH, THORSTEN
• BAECHLE, MARTIN
• SCHELLER, TOBIAS
• SVENSSON, THOMAS
• FELCH, Hal

Assignees

• AUMOVIO Germany GmbH
• Ford-Werke GmbH

Dates

Publication Date

20260506

Application Date

20240629

Claims (20)

1. 1 . Method for operating a braking system (BS) of a motor vehicle (KF), wherein the motor vehicle (KF) has at least two axles, each with at least one wheel (R), wherein the braking system (BS) has one or more brakes (B), each of which is assigned to at least one wheel (R) for applying braking torque, wherein the braking system (BS) is hydraulic and has at least one electric pressure generator (DE) for building up hydraulic pressure, wherein the motor vehicle (KF) has, in addition to the braking system (BS), a further braking system (WBS) that can be operated independently thereof, wherein the method comprises the following steps: Monitoring a hydraulic pressure in the braking system (BS), and if a pressure loss is detected, always controlling the pressure generator (DE) to generate or increase the hydraulic pressure.
2. 2. The method according to claim 1, wherein the control of the pressure generator (DE) to generate or increase the hydraulic pressure takes place immediately after the detection of a pressure loss or a predetermined time after the detection of a pressure loss.
3. 3. Method according to one of the preceding claims, wherein the control of the pressure generator (DE) for generating or increasing the hydraulic pressure takes place independently of a leak test.
4. 4. Method according to one of the preceding claims, wherein when a pressure loss is detected, between the detection of a pressure loss and the activation of the pressure generator to generate or increase the hydraulic pressure, and/or during the activation of the pressure generator to generate or increase the hydraulic pressure no valves are closed which are fluidically connected between the pressure generator (DE) and the brakes (BE).
5. 5. Method according to one of the preceding claims, wherein when a pressure loss is detected, the pressure generator (DE) always remains or is connected to at least one brake (B), or to some or all of the brakes (B).
6. 6. Method according to one of the preceding claims, wherein the pressure generator (DE) remains connected to all brakes (B) after a pressure loss has been detected at least as long as the pressure generator (DE) is controlled to generate or increase the hydraulic pressure, or remains connected until the braking system (BS) is taken out of operation.
7. 7. Method according to one of claims 1 to 5, wherein the pressure generator (DE) remains connected to at least one brake (B), or to some but not all brakes (B), after a pressure loss has been detected, at least as long as the pressure generator (DE) is controlled to generate or increase the hydraulic pressure, or remains connected until the braking system (BS) is taken out of operation.
8. 8. Method according to one of the preceding claims, wherein when a pressure loss is detected, the braking system (BS) always remains in a mode in which the hydraulic pressure is applied wholly or partly by means of the electrical pressure generator (DE).
9. 9. Method according to one of the preceding claims, wherein the further braking system (WBS) is an electromechanical braking system.
10. 10. Method according to one of the preceding claims, wherein the braking system (BS) has only brakes (B) on one front axle or several front axles of the motor vehicle (KF).
11. 11. Method according to one of claims 1 to 9, wherein the braking system (BS) has only brakes (B) on one rear axle or several rear axles of the motor vehicle (KF).
12. 12. Method according to one of the preceding claims, wherein the braking system (BS) has no brakes (B) on at least one axle of the motor vehicle (KF).
13. 13. Method according to one of the preceding claims, wherein the further braking system (WBS) has one or more brakes (B) on an axle of the motor vehicle (KF) on which the braking system (BS) has no brake (B).
14. 14. Method according to one of the preceding claims, wherein the further braking system (WBS) exclusively has brakes (B) on one or more axles of the motor vehicle (KF), on which or on which the braking system (BS) has no brakes (B).
15. 15. Method according to one of the preceding claims, wherein each axle of the motor vehicle (KF) has at least two wheels (R).
16. 16. A method according to any one of the preceding claims, wherein a pressure loss is detected in response to the hydraulic pressure falling below a predetermined or dynamic threshold.
17. 17. A method according to any one of the preceding claims, wherein a pressure loss is determined in response to the hydraulic pressure remaining below a predetermined or dynamic threshold for at least a predetermined period of time.
18. 18. Method according to one of the preceding claims, which further comprises the following steps in response to the braking system (BS) and/or the motor vehicle (KF) being switched off: determining at least one value of an operating parameter of the braking system (BS), determining whether the value of the operating parameter is in a critical range, and in response to the value of the operating parameter being in a critical range, controlling the pressure generator (DE) to increase the hydraulic pressure.
19. 19. The method according to claim 18, wherein the operating parameter is a temperature of a component of the braking system (BS).
20. 20. Method according to one of claims 18 or 19, which further comprises the following step before, during or after controlling the pressure generator (DE) to increase the hydraulic pressure: controlling one or more valves of the braking system (BS) such that the hydraulic pressure is enclosed in a section of the braking system (BS).

Description

Method for operating a braking system of a motor vehicle, control device, hydraulic braking system and motor vehicle The invention relates to a method for operating a braking system of a motor vehicle, a control device, a hydraulic braking system for a motor vehicle and a motor vehicle with such a braking system. Braking systems are typically used to decelerate motor vehicles in a targeted manner. Typically, many braking systems are operated in such a way that hydraulic pressure can be built up using a manually operated master brake cylinder and/or an electrically operated pressure generator, which can then be used to generate braking pressure in wheel brakes. Modern braking systems typically have a device for measuring pressure in the hydraulic system. However, it can be problematic how to react to a pressure drop that may be measured. It is therefore an object of the invention to provide a method for operating a braking system of a motor vehicle, which is alternative or better than known embodiments, for example shows an improved reaction to a detected pressure drop. It is also an object of the invention to provide a control device and a hydraulic braking system for carrying out such a method. It is also an object of the invention to provide a motor vehicle with such a braking system. This is achieved according to the invention by a method, a control device, a hydraulic brake system and a motor vehicle according to the respective main claims. Advantageous embodiments can be taken, for example, from the respective subclaims. The content of the claims is made part of the content of the description by express reference. The invention relates to a method for operating a braking system of a motor vehicle. The motor vehicle typically has at least two axles, each with at least one wheel. The braking system has one or more brakes, each of which is assigned to at least one wheel for applying braking torque. The braking system is hydraulic and has at least one electric pressure generator for building up hydraulic pressure. In addition to the braking system, the motor vehicle preferably has a further braking system, which can preferably be operated independently of the braking system. The procedure consists of the following steps: Monitoring hydraulic pressure in the braking system and, if a loss of pressure is detected, always controlling the pressure generator to generate or increase the hydraulic pressure. Such a method can be used to react advantageously to a detected pressure loss. It was recognized that if there is an additional braking system that can be operated independently of the braking system, the hydraulic pressure can in principle be generated or increased using the pressure generator, since even if the pressure loss has occurred due to a leak and the hydraulic braking system is therefore expected to run idle, the additional braking system is available and can brake the vehicle. There is therefore no loss of safety associated with the basic generation or increase of hydraulic pressure. In particular, measures that ensure the functionality of the braking system even if a leak has occurred in the braking system can be dispensed with. In particular, the method can be implemented in a braking system or its control device in such a way that no other reaction to a pressure loss than that specified is possible. In other words, the reaction when a pressure loss is detected takes place in response to the detection of a pressure loss. The two axles can typically be a front axle and a rear axle. A motor vehicle can in principle have more than one axle at the front and/or rear; for example, vehicles such as trucks or buses can have two rear axles. In a multi-track motor vehicle, an axle typically has at least two wheels. It can be provided that there is only one wheel on each side of the motor vehicle. However, it is also possible to provide several wheels on each side, for example with twin tires. In a single-track motor vehicle, each axle typically has only one wheel. This corresponds, for example, to the typical design of a motorcycle. However, mixed forms are also possible, for example in a trike, which has only one wheel at the front and two wheels at the rear. A brake can be designed as a friction brake, for example as a drum brake or as a disc brake. If it is assigned to just one wheel, it can brake that wheel. If it is assigned to several wheels, for example both wheels of a twin tire system, it can brake those wheels. The hydraulic braking system typically has a certain volume of hydraulic fluid, for example brake fluid. This can be pressurized by the pressure generator. The pressure can typically be used in the brakes to build up braking force or braking torque. Valves are typically present for this purpose, which can control the pressure build-up on the respective brakes. The pressure generator is in particular electric, so it generates the pressure without the use of human muscle power. The addition