METHOD FOR OPERATING A BRAKE SYSTEM OF A VEHICLE, CONTROL DEVICE FOR A BRAKE SYSTEM, AND BRAKE SYSTEM

Abstract

A method for operating a brake system of a vehicle. The brake system having: a first and a second actuator for generating a hydraulic pressure in the brake system; a first control device designed to control the first actuator; and a second control device designed to control the second actuator. In the method, the brake system is monitored for emergency braking, wherein the first actuator is controlled by the first control device to generate a first hydraulic pressure for achieving a pre-specified emergency deceleration of the vehicle if emergency braking is detected. The second control device is controlled by the first control device to control the second actuator to generate a second hydraulic pressure when the deceleration that can be or is achieved by means of the first actuator is less than the pre-specified emergency deceleration.

Claims

1-9. (canceled)

10. A method for operating a brake system of a vehicle, the brake system including a first actuator and a second actuator for generating a hydraulic pressure in the brake system, a first control device which is configured to control the first actuator, and a second control device which is configured to control the second actuator, the method comprising the following steps: monitoring the brake system for emergency braking; controlling the first actuator, by the first control device, to generate a first hydraulic pressure for achieving a prespecified emergency deceleration of the vehicle when emergency braking is detected; and controlling the second control device, by the first control device, to control the second actuator to generate a second hydraulic pressure when deceleration that can be or is achieved using the first actuator is less than the pre-specified emergency deceleration.

11. The method according to claim 10, wherein vehicle data of the vehicle are monitored to detect emergency braking.

12. The method according to claim 11, wherein the vehicle data includes an actuating path and a speed of actuation of a brake pedal by a driver, and emergency braking is initiated when the actuating path and the speed both exceed a prespecified limit value.

13. The method according to claim 11, wherein the vehicle data include sensor data from sensors of the vehicle that acquire information about surroundings of the vehicle, and emergency braking is initiated when a dangerous driving situation is identified during the evaluation of the sensor data.

14. The method according to claim 11, wherein an actual deceleration of the vehicle is measured, and that the second actuator is activated only when the actual deceleration is less than the prespecified emergency deceleration.

15. The method according to claim 11, wherein an actual hydraulic pressure in the brake system is measured, and the second actuator is activated only when the actual hydraulic pressure is less than a target hydraulic pressure which is prespecified as a function of the prespecified emergency deceleration.

16. The method according to claim 14, wherein the second actuator is activated to generate a maximum possible hydraulic pressure when no actual deceleration and/or no actual hydraulic pressure can be measured.

17. First and second control devices for a brake system, wherein the brake system includes a first actuator and a second actuator for generating a hydraulic pressure in the brake system, wherein the first control device is configured to control the first actuator, and the second control device is configured to control the second actuator, wherein the first and second control devices are configured to: monitor the brake system for emergency braking; control the first actuator, by the first control device, to generate a first hydraulic pressure for achieving a prespecified emergency deceleration of the vehicle when emergency braking is detected; and control the second control device, by the first control device, to control the second actuator to generate a second hydraulic pressure when deceleration that can be or is achieved using the first actuator is less than the pre-specified emergency deceleration.

18. A brake system of a vehicle, comprising: a first actuator and a second actuator for generating a hydraulic pressure in the brake system; and a first control device and a second control device, the first control device being configured to control the first actuator, and the second control device being configured to control the second actuator, wherein the first and second control devices are configured to: monitor the brake system for emergency braking, control the first actuator, by the first control device, to generate a first hydraulic pressure for achieving a prespecified emergency deceleration of the vehicle when emergency braking is detected, and control the second control device, by the first control device, to control the second actuator to generate a second hydraulic pressure when deceleration that can be or is achieved using the first actuator is less than the pre-specified emergency deceleration.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 shows a brake system in a schematic illustration, according to an example embodiment of the present invention.

[0015] FIG. 2 shows a method for operating the brake system, according to an example embodiment of the present invention.

[0016] FIG. 3 shows characteristic curves of pressure progressions in the brake system, according to an example embodiment of the present invention.

[0017] FIG. 4 shows further characteristic curves of pressure progressions in the brake system, according to an example embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0018] FIG. 1 shows components of a brake system 1 of a vehicle 2 in a schematic illustration. The brake system 1 comprises a first actuator 3 and a second actuator 4. The first actuator 3 and the second actuator 4 are both configured to generate a hydraulic pressure in the brake system 1, so that a brake pressure can be applied to wheel braking devices of the vehicle 2, which are not shown in greater detail. The brake system 1 further comprises a first control device 5 and a second control device 6. The first control device 5 has a communication link with the first actuator 3 and is configured to activate the first actuator 3. The first control device 5 furthermore has a communication link with the second control device 6 and is configured to activate the second control device 6. The first control device 5 also has a communication link with the vehicle 2 such that the brake system 1 can be monitored by the first control device 5 for emergency braking, in particular on the basis of vehicle data of the vehicle 2.

[0019] One advantageous method for operating the brake system 1 of the vehicle 2 is described in the following with reference to FIG. 2. For this purpose, FIG. 2 shows the method using a flow chart. The method in particular ensures that the vehicle 2 is braked safely and quickly to a standstill with a prespecified emergency deceleration, or undergoes full deceleration, when emergency braking is identified.

[0020] In a Step S1, the method starts with the monitoring of the brake system for emergency braking. Preferably, vehicle data of the vehicle 2 are monitored to detect emergency braking. The vehicle data preferably include an actuating path and a speed of actuation of a brake pedal by a driver and/or sensor data from sensors of the vehicle 2 that acquire information about the surroundings of the vehicle 2.

[0021] In a Step S2, the vehicle data is evaluated and checked to determine whether emergency braking has to be initiated. Emergency braking is preferably initiated when the actuating path and speed of actuation of the brake pedal by the driver both exceed a prespecified limit value. Emergency braking is furthermore preferably initiated when a dangerous driving situation is identified during the evaluation of the sensor data from the sensors of the vehicle 2 that acquire information about the surroundings of the vehicle 2. If it is now recognized that there is no need to initiate emergency braking because there is in particular no exceedance of the prespecified limit values in the actuation of the brake pedal nor a dangerous driving situation, the method ends in Step S6.

[0022] However, if it is recognized that emergency braking has to be initiated, the method continues with a Step S3. In Step S3, the first actuator 3 is activated by the first control device 5 to generate a first hydraulic pressure p.sub.1 to achieve a prespecified emergency deceleration of the vehicle 2. The prespecified emergency deceleration is in particular a minimum deceleration specified by law.

[0023] In a Step S4, it is now checked, preferably at a prespecified time after the control of the actuator 3 by the first control device 5, whether the deceleration achieved by the first actuator 3 is less than the prespecified emergency deceleration. An actual deceleration of the vehicle is preferably measured and compared to the prespecified emergency deceleration for this purpose. If the achieved deceleration or the actual deceleration is at least as great as the prespecified emergency deceleration, the method likewise ends in Step S6. This case will be described later with reference to the pressure progressions shown in FIG. 3.

[0024] However, if the deceleration achieved by the first actuator 3 is in fact less than the prespecified emergency deceleration, if the achieved deceleration or the actual deceleration cannot be measured, or if the achievable deceleration is already less than the prespecified emergency deceleration, the method is continued with a Step S5. In Step S5, the second control device 6 is activated by the first control device 5 to control the second actuator 4 to generate a second hydraulic pressure p.sub.2 in order to achieve the prespecified emergency deceleration. This case will be described later with reference to the pressure progressions shown in FIG. 4. The method then ends, preferably with the vehicle 2 achieving full deceleration, in Step S6.

[0025] FIG. 3 shows characteristic curves of pressure progressions in the brake system 1 when emergency braking is identified. The characteristic curves are shown in a diagram in which the x-axis shows the time t and the y-axis shows the pressure p. The pressure progressions depicted in FIG. 3 make it possible to see a method carried out according to the present invention and according to the description for FIG. 2, in which it was recognized in Step S4 that the achieved deceleration is sufficient and the method ends without the hydraulic pressure having to be increased by the second actuator 4.

[0026] At a time t.sub.0, the driver first initiates a braking process in which a brake pressure p.sub.B at the wheel braking devices and a first hydraulic pressure p.sub.1 in the brake system increase linearly and are equal in magnitude. At a time t.sub.1, emergency braking is initiated by the first control device 5, so that a progression of a hydraulic pressure p.sub.H is now specified in order to achieve a prespecified emergency deceleration. At a time t.sub.2, a maximum brake pressure p.sub.Bmax or a locking pressure is achieved at the wheel braking devices.

[0027] An anti-lock braking system now intervenes in a controlling manner in the braking process. If the wheels are about to lock, the anti-lock braking system initially reduces the brake pressure p.sub.B until the tendency to lock is stopped and then increases it again. From the time t.sub.2, therefore, the brake pressure p.sub.B at the wheel braking devices oscillates around the maximum brake pressure p.sub.Bmax.

[0028] After the time t.sub.2, the first hydraulic pressure p.sub.1 continues to increase until it reaches the maximum first hydraulic pressure p.sub.1max, which in the present case is as high as the prespecified hydraulic pressure p.sub.H and higher than the maximum brake pressure p.sub.Bmax, so that the prespecified emergency deceleration is achieved. The generation of a second, higher hydraulic pressure p.sub.2 by the second actuator 4 is therefore not necessary.

[0029] FIG. 4 shows further characteristic curves of pressure progressions in the brake system 1 when emergency braking is identified. The characteristic curves are likewise shown in a diagram in which the x-axis shows the time t and the y-axis shows the pressure p. The pressure progressions depicted in FIG. 4 make it possible to see a method carried out according to the present invention and according to the description for Substitute Specification FIG. 2, in which it was recognized in Step S4 that the achieved deceleration is not sufficient and the hydraulic pressure has to be increased by the second actuator 4.

[0030] As already described for FIG. 3, at a time t.sub.0, the driver initiates a braking process in which the brake pressure p.sub.B at the wheel braking devices and the first hydraulic pressure p.sub.1 in the brake system increase linearly and are equal in magnitude. At the time t.sub.1, emergency braking is again initiated by the first control device 5, so that the progression of a hydraulic pressure p.sub.H is now specified in order to achieve the prespecified emergency deceleration. After the time t.sub.1, the first hydraulic pressure p.sub.1 continues to increase to a maximum first hydraulic pressure p.sub.1max. At a time t.sub.3 it is recognized that the first hydraulic pressure p.sub.1 is less than the maximum brake pressure p.sub.Bmax at the wheel braking devices. The second actuator 4 is then activated to increase the hydraulic pressure p.sub.H to a maximum second hydraulic pressure p.sub.2max, which is higher than the maximum brake pressure p.sub.Bmax, so that the prespecified emergency deceleration can be achieved.

[0031] The brake pressure p.sub.B now continues to increase until the maximum brake pressure p.sub.Bmax is reached at the wheel braking devices. The anti-lock braking system then again intervenes in a controlling manner in the braking process, as described above, so that the brake pressure p.sub.B oscillates around the maximum brake pressure p.sub.Bmax in order to achieve the prespecified emergency deceleration.