Method for operating a brake system of a vehicle, controller for a brake system, and brake system

Abstract

The present invention relates to a method of operating a brake system (1) of a vehicle (2) using first and second actuators (3, 4) for generating hydraulic pressure in the brake system (1), a first controller (5) configured for activating the first actuator (3), and a second controller (6) configured for activating the second actuator (4), the method monitoring the brake system (1) for emergency braking, and if emergency braking is detected, activating the first actuator (3) by the first controller (5) to generate a first hydraulic pressure to bring the vehicle (2) to a predetermined emergency deceleration. [Solution] The method according to the present invention is characterized in that, if the deceleration that can be achieved or has been achieved by the first actuator (3) is less than the preset emergency deceleration, then the second controller (6) is activated by the first controller (5) to activate the second actuator (4) and generate a second hydraulic pressure.

Description

[Technical Field]

[0001] The present invention relates to a method of operating a braking system of a vehicle using first and second actuators for generating hydraulic pressure in the braking system, a first controller configured for activating the first actuator, and a second controller configured for activating the second actuator, wherein the method monitors the braking system for emergency braking, and if emergency braking is detected, then the first actuator is activated by the first controller to generate a first hydraulic pressure to cause the vehicle to reach a preset emergency deceleration.

[0002] The present invention further relates to first and second controllers for a braking system and to a braking system of a vehicle. [Background technology]

[0003] Methods, controllers, and brake systems of the aforementioned type are known from the prior art. In particular, they are known for assisting a vehicle driver in achieving full vehicle deceleration based on a detected emergency braking. When an emergency braking event is detected by an assistance system of the vehicle, in particular a hydraulic brake assist, full vehicle deceleration is initiated until the vehicle comes to a stop. The objective of activating the hydraulic brake assist is to achieve a preset emergency deceleration of the vehicle, in particular the maximum possible deceleration, as quickly as possible. To this end, the controller activates multiple actuators of the vehicle's brake system, in particular hydraulic pumps of an electromechanical brake booster or an electronic stability program, to generate hydraulic pressure in the brake system to achieve the maximum possible deceleration of the vehicle. To this end, the brake pressure at the vehicle's wheel brakes is adjusted, in particular, so that the brake pressure rises within the control range of the anti-lock brake system, i.e., up to the locking pressure or locking limit of each wheel. Summary of the Invention

[0004] The method according to the present invention, which has the features of claim 1, is characterized in that, if the deceleration that can be achieved or has been achieved by the first actuator is less than a predetermined emergency deceleration, the first controller activates the second actuator to generate the second hydraulic pressure. By activating the second controller in this way, the second actuator always ensures that the vehicle's predetermined emergency deceleration is reached. That is, the second controller receives a request to assist the first controller or to initiate emergency braking. Furthermore, the second controller does not need to monitor the brake system for emergency braking; rather, this can be assumed by the first controller. The second controller is preferably part of the vehicle's electronic stability program or anti-lock brake system. The first controller preferably controls a part of the brake system, particularly an electromechanical brake system, that can be activated independently. Preferably, the first controller receives information about the achieved vehicle deceleration and / or information about the control status of the anti-lock brake system, particularly brake slip, from a plurality of sensors, particularly associated with the electronic stability program. Using this information, it is advantageous to first limit the hydraulic pressure to the maximum hydraulic pressure that can be achieved by the first actuator, and only when this hydraulic pressure is insufficient to reach a preset emergency deceleration rate is the second controller activated to activate the second actuator, whereby the preset emergency deceleration rate is preferably a minimum deceleration rate that is legally preset or required, in particular by ECE control.

[0005] According to an advantageous further embodiment of the present invention, vehicle data of a vehicle is monitored to detect emergency braking. By monitoring vehicle data of a vehicle to detect emergency braking, it is advantageously ensured that the need for emergency braking is recognized reliably. In any case, vehicle data of an already existing vehicle is preferably monitored, so that there is no need to assign additional vehicle data or input signals to the brake system.

[0006] According to a further advantageous embodiment of the present invention, the vehicle data includes the distance and speed of the driver's brake pedal actuation, and emergency braking is initiated if the actuation distance and speed exceed preset limits. By monitoring the brake pedal actuation distance and actuation speed in this manner, it is possible to determine using simple decision logic whether emergency braking should be initiated. This monitoring is advantageous because it can also be used in braking systems in which the brake pedal or brake pedal actuation is completely mechanically isolated from the brake circuit, i.e., in braking systems in which the driver intervenes in a pedal power simulator to decelerate the vehicle. Preferably, the simulator pressure and input rod distance resulting from the brake pedal actuation are used to determine the driver's braking request and are used to recognize emergency braking.

[0007] According to an advantageous further aspect of the present invention, the vehicle data includes sensor data from sensors of the vehicle that detect the vehicle's surroundings, and emergency braking is initiated if a dangerous driving situation is recognized upon evaluation of the sensor data. A dangerous driving situation exists, in particular, when the distance to the preceding vehicle is too small or when there is an obstacle on the road, and as a result, the vehicle must slow down to avoid an accident. By monitoring and evaluating the sensor data for recognizing a dangerous driving situation using multiple sensors that detect the vehicle's surroundings, it is advantageously ensured that emergency braking can be initiated in a timely manner, especially even if the driver has not yet expressed a desire to brake by operating the brake pedal, or if the driver has not yet recognized the dangerous driving situation as dangerous. Therefore, the method is advantageously operable even in the case of automatic braking, i.e., without driver intervention.

[0008] According to an advantageous further embodiment of the present invention, the actual deceleration of the vehicle is measured, and the second actuator is activated only if the actual deceleration is less than a preset emergency deceleration. By activating the second actuator only if the measured actual deceleration is insufficient, it is advantageously ensured that the second actuator is not activated unnecessarily or that hydraulic pressure does not increase unnecessarily. Preferably, it is also possible to monitor whether the target of full deceleration has already been achieved, in which case activation of the second actuator by the second controller is also omitted. Furthermore, measuring the actual deceleration of the vehicle advantageously enables reliable recognition of a fault condition in the brake system, particularly due to brake fade, in which activation of the first actuator by the first controller would not achieve the expected deceleration of the vehicle.

[0009] According to an advantageous further embodiment of the invention, the actual hydraulic pressure in the brake system is measured, and the second actuator is activated only if the actual hydraulic pressure is lower than a preset target hydraulic pressure depending on a preset emergency deceleration. By activating the second actuator only if the measured actual hydraulic pressure is insufficient in this way, it is advantageously ensured that the second actuator is not activated unnecessarily or that the hydraulic pressure does not increase unnecessarily.

[0010] According to an advantageous further configuration of the present invention, if the actual deceleration and / or the actual hydraulic pressure cannot be measured, the second actuator is activated to generate the maximum possible hydraulic pressure. This activation of the second actuator to generate the maximum possible hydraulic pressure provides an advantageous fallback level for cases where there is no measurement data for the actual deceleration or the actual hydraulic pressure. This increases the fault tolerance of the brake system, at least insofar as the second controller and the second actuator continue to ensure sufficient deceleration during emergency braking in the event of a sensor device failure.

[0011] The first and second controllers for a braking system according to the invention are characterized in that the controllers are particularly arranged to carry out the method according to the invention, from which the advantages already mentioned are obtained.

[0012] A braking system according to the invention having the features of claim 9 is characterized in that it comprises first and second actuators for generating hydraulic pressure in the braking system and is provided with a controller according to the invention, which provides the advantages already mentioned.

[0013] Further advantageous features and combinations of features are evident from the foregoing and the claims. Next, the present invention will be described in more detail with reference to the drawings. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of a brake system. [Figure 2] FIG. 1 illustrates a method for operating a brake system. [Figure 3] 2 shows a characteristic curve of the pressure profile in the brake system. [Figure 4] 4 shows another characteristic curve of the pressure profile in the brake system. DETAILED DESCRIPTION OF THE INVENTION

[0015] FIG. 1 shows a schematic diagram of components of a brake system 1 of a vehicle 2. The brake system 1 includes a first actuator 3 and a second actuator 4. The first actuator 3 and the second actuator 4 are each configured to generate hydraulic pressure in the brake system 1, thereby applying brake pressure to wheel brake mechanisms of the vehicle 2 (not shown in detail). The brake system 1 further includes a first controller 5 and a second controller 6. The first controller 5 is communicatively coupled to the first actuator 3 and configured to activate the first actuator 3. The first controller 5 is communicatively coupled to the second controller 6 and configured to activate the second controller 6. The first controller 5 is communicatively coupled to the vehicle 2 so that the brake system 1 can be monitored by the first controller 5, in particular with respect to emergency braking, based on vehicle data of the vehicle 2.

[0016] An advantageous method for activating the brake system 1 of a vehicle 2 is explained below with reference to Figure 2. For this purpose, Figure 2 illustrates the method on the basis of a flow chart. In particular, the method ensures that the vehicle 2 is braked safely and quickly to a standstill at a preset emergency deceleration or undergoes full deceleration when it perceives an emergency braking event.

[0017] In step S1, the method begins by monitoring the brake system for emergency braking. To detect emergency braking, vehicle data of vehicle 2 is preferably monitored. The vehicle data preferably includes the distance and speed of brake pedal operation by the driver and / or sensor data from a plurality of sensors of vehicle 2 that sense the surroundings of vehicle 2.

[0018] In step S2, vehicle data is evaluated to determine whether emergency braking should be initiated. It is preferable to initiate emergency braking if the distance and speed of the driver's brake pedal operation exceed preset limits. Furthermore, it is advantageous to initiate emergency braking if a dangerous driving situation is recognized when evaluating sensor data from a plurality of sensors on vehicle 2 that detect the surroundings of vehicle 2. If it is determined that emergency braking is not necessary, particularly since the brake pedal operation does not exceed preset limits and no dangerous driving situation exists, the method ends in step S6.

[0019] However, if it is recognized that an emergency brake must be applied, the method continues with step S3, in which the first controller 5 activates the first actuator 3 in order to generate a first hydraulic pressure p1 to reach a preset emergency deceleration of the vehicle 2, which is in particular a legally preset minimum deceleration.

[0020] Now, in step S4, it is checked, preferably at a predetermined time after activation of the actuator 3 by the first controller 5, whether the deceleration achieved by the first actuator 3 is less than a predetermined emergency deceleration. For this purpose, the actual deceleration of the vehicle is preferably measured and compared with the predetermined emergency deceleration. If the achieved or actual deceleration is at least as great as the predetermined emergency deceleration, the method is likewise terminated in step S6. This case will be explained below based on the pressure curve shown in FIG. 3.

[0021] However, if the deceleration achieved by the first actuator 3 is actually less than the preset emergency deceleration, or if the achieved or actual deceleration cannot be measured, or if the already achievable deceleration is less than the preset emergency deceleration, the method continues with step S5. In step S5, the first controller 5 activates the second controller 6 in order to activate the second actuator 4 and generate the second hydraulic pressure p2, thereby achieving the preset emergency deceleration. This case will be explained below based on the pressure curve shown in Figure 4. The method then ends in step S6, preferably with full deceleration of the vehicle 2 achieved.

[0022] 3 shows characteristic curves of pressure curves in the brake system 1 when an emergency braking is recognized. These characteristic curves are plotted on a graph, with the x-axis representing time t and the y-axis representing pressure p. Using the pressure curves shown in FIG. 3, it can be seen that the method implemented according to the invention is as described for FIG. 2 when it is recognized in step S4 that the deceleration achieved is sufficient and the method ends without the need to increase the hydraulic pressure by the second actuator 4.

[0023] First, at time t0, the driver initiates a braking process, and during the braking process, the brake pressure p B and the first hydraulic pressure p1 in the brake system rise linearly and are equal in magnitude. At time t1, the first controller 5 initiates emergency braking, so that the hydraulic pressure p H At time t2, the maximum braking pressure p Bmax Or locking pressure is achieved.

[0024] At this time, the anti-lock brake system intervenes and controls the braking process. When the wheels are about to lock, the anti-lock brake system first increases the brake pressure p B, and then increase it again. B is the maximum braking pressure p after time t2 Bmax It vibrates around .

[0025] After time t2, the first hydraulic pressure p1 is set to the preset hydraulic pressure p H and the maximum braking pressure p Bmax The maximum primary hydraulic pressure p is greater than 1max , and as a result reaches the preset emergency deceleration. Therefore, generation of the second, higher hydraulic pressure p2 by the second actuator 4 is not required.

[0026] 4 shows further characteristic curves of the pressure curves in the brake system 1 when an emergency braking is recognized. These characteristic curves are likewise plotted on a graph, with the x-axis representing time t and the y-axis representing pressure p. Using the pressure curves shown in FIG. 4, it can be seen that the method implemented according to the invention when it is recognized in step S4 that the achieved deceleration is insufficient and that the hydraulic pressure must be increased by the second actuator 4 is exactly as described for FIG. 2.

[0027] As already mentioned in FIG. 3, the driver initiates a braking process at time t0, and during the braking process, the brake pressure p B and the first hydraulic pressure p1 in the brake system rise linearly and are equal in magnitude. At time t1, the first controller 5 again initiates emergency braking, so that the hydraulic pressure p H The first hydraulic pressure p1 is increased further to the maximum first hydraulic pressure p1 after the time t1. 1max At time t3, the first hydraulic pressure p1 rises to the maximum brake pressure p Bmax Therefore, the hydraulic pressure p H , the maximum brake pressure p Bmax The maximum second hydraulic pressure p is greater than 2max, the second actuator 4 is activated so that a preset emergency deceleration can be reached.

[0028] Now, brake pressure p B is the maximum braking pressure p in the wheel brake mechanism Bmax At this point, as previously mentioned, the anti-lock braking system again intervenes and controls the braking process, resulting in an increase in the braking pressure p B is the maximum braking pressure p to reach the preset emergency deceleration. Bmax vibrates around the [Explanation of symbols]

[0029] 1. Brake system 2 vehicles 3 First Actuator 4 Second Actuator 5 First Controller 6 Second Controller

Claims

1. 1. A method of operating a brake system (1) of a vehicle (2) using first and second actuators (3, 4) for generating hydraulic pressure in the brake system (1), a first controller (5) configured for activating the first actuator (3) and controlling part of an electromechanical brake system, and a second controller (6) configured for activating the second actuator (4) and being part of an electronic stability program or anti-lock brake system, the method comprising: monitoring the brake system (1) by the first controller (5) for emergency braking; and, if emergency braking is detected, activating the first actuator (3) by the first controller (5) to generate a first hydraulic pressure to bring the vehicle (2) to a predetermined emergency deceleration, the method comprising: and activating, by the first controller (5), the second controller (6) to activate the second actuator (4) to generate a second hydraulic pressure, if the deceleration achievable or achieved by the first actuator (3) is less than the preset emergency deceleration.

2. 2. The method of claim 1, further comprising monitoring vehicle data of the vehicle (2) to detect emergency braking.

3. 3. The method of claim 2, wherein the vehicle data includes a distance and a speed of a brake pedal operation by a driver, and the emergency brake is initiated if the operation distance and the operation speed exceed predetermined limits, respectively.

4. 4. The method according to claim 2 or 3, characterized in that the vehicle data includes sensor data of sensors of the vehicle (2) detecting the surroundings of the vehicle (2), and the emergency braking is initiated if a dangerous driving situation is recognized when the sensor data is evaluated.

5. 5. The method according to claim 1, further comprising measuring an actual deceleration of the vehicle (2) and activating the second actuator (4) only if the actual deceleration is less than the preset emergency deceleration.

6. 6. The method according to claim 1, further comprising measuring an actual hydraulic pressure in the brake system, and activating the second actuator only if the actual hydraulic pressure is lower than a predetermined target hydraulic pressure as a function of the predetermined emergency deceleration.

7. 7. A method according to claim 5 or 6, characterized in that if the actual deceleration and / or the actual hydraulic pressure cannot be measured, the second actuator (4) is activated in order to generate the maximum possible hydraulic pressure.

8. First and second controllers (5, 6) for a braking system (1), characterized in that the controllers (5, 6) are arranged to carry out the method according to any one of claims 1 to 7.

9. 9. A vehicle brake system (1) for a vehicle (2) having first and second actuators (3, 4) for generating hydraulic pressure in the brake system (1), characterized in that the brake system (1) is provided with first and second controllers (5, 6) according to claim 8.

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