DE102019108620B4 - Method and control unit for controlling a steering brake function for a vehicle and braking system for a vehicle - Google Patents

Abstract

Method (300) for controlling a steering brake function for a vehicle (100), the method (300) having the following steps: applying (310) a first pressure control valve (152) and a second pressure control valve (154) with compressed air with a pilot control pressure (P1; P4) by means of a first brake control device (130), the first pressure control valve (152) being assigned to a first wheel brake (162) for a first wheel (172) of a steerable axle (170) of the vehicle (100), the second pressure control valve (154 ) is assigned to a second wheel brake (164) for a second wheel (174) of the steerable axle (170) of the vehicle (100), the pilot control pressure (P1; P4) being less than a supply pressure of a compressed air supply (112) of the vehicle (100) is; and actuating (320) the first pressure control valve (152) and the second pressure control valve (154) depending on a steering request signal by means of a second brake control device (140) in order to provide the first wheel brake (162) with a first brake pressure (P2; P5) and the second wheel brake ( 164) to apply a second brake pressure (P3; P6) that is different from the first brake pressure (P2; P5), the steering request signal representing a requested steering angle of the steerable axle (170), the first brake pressure (P2; P5) and the second brake pressure (P3; P6) is less than or equal to the pilot control pressure (P1; P4), the first pressure control valve (152) and the second pressure control valve (154) being subjected to a pilot control pressure (P1; P4) in step (310) of applying , which is less than two thirds or half of the supply pressure, and / or in step (320) of driving, the first pressure control valve (152) and the second pressure control valve (154) are controlled so that a pressure difference between the first brake pressure (P2; P5) and the second brake pressure (P3; P6) is a maximum of 5 bar to a maximum of 1 bar.

Description

The present invention relates to a method for controlling a steering brake function for a vehicle, to a corresponding control unit and to a braking system for a vehicle.

In a vehicle, for example, braking of individual wheels can be used as a redundancy level for lateral guidance of the vehicle. Particularly in brake systems without a pneumatic pressure sensor between a valve for traction control or traction control and the brake cylinder, exact setting of the required wheel brake pressures can be difficult. Conventionally, an attempt can be made to circumvent this through a pressure estimate, which calculates with a fixed pilot pressure that results from an operating pressure of a storage tank. A resolution of small pressure modulations in the brake cylinder of an individual wheel can depend on the supply pressure or a regulation of the valve for traction control or traction control and a minimum activation time of the pressure control valve for the individual wheels.

The DE 10 2017 113 336 A1 discloses an electrical equipment of a vehicle or a vehicle combination consisting of a towing vehicle and at least one trailer vehicle, wherein the electrical equipment includes a service brake device that is electrically controllable and actuated by an electronic brake control device and a driver assistance system or an autopilot device, which controls the service brake device independently of the driver in accordance with a braking effect specification automatically controls or regulates. It is provided that in the event of a failure of the electronic brake control device or its electrical energy source, an additional electronic control device detects brake locking based on data from a sensor device, which is supplied by a redundant energy source and then reduces the brake pressure compared to the brake pressure specification by the driver assistance system or the autopilot device .

Against this background, the object of the present invention is to provide an improved method for controlling a steering brake function for a vehicle, an improved control unit, an improved braking system for a vehicle and an improved computer program.

This task is solved by a method for controlling a steering brake function for a vehicle, by a corresponding control device, by a braking system for a vehicle and by a corresponding computer program according to the main claims.

According to embodiments, in particular an advantageous pressure control for a steering brake function or so-called steer-by-brake function (SBB function) can be implemented for steering redundancy in redundant systems. The physical effect of the steering brake function is that braking a single wheel of a steerable axle can generate a steering torque, which, in conjunction with a positive steering roll radius, can lead to the wheels turning. This can also be used if both wheels of the steerable axle are already braked, whereby a differential pressure can be built up between the wheels, which can have the same effect as purely one-sided braking. According to embodiments, in a vehicle that has at least two brake systems to represent redundancy, a first brake system that can measure a brake pressure at least in circles or axles, for example an electronic brake system, can be connected to a second brake system, for example an anti-lock braking system can carry out valve control on a wheel-by-wheel basis without pressure sensors.

If the steering function is to be taken over by the brake system (SBB function) if the vehicle's electrically controllable steering system fails due to steer-by-brake, the first brake system is used to set low pressures to the valves of the wheel brake cylinders, which ensures precise pressure control Particularly in comparison to the supply pressure, low pressures are made possible, and the second brake system is used to control the valves assigned to the individual wheels or to regulate them with reduced pilot control pressure, depending on the individual wheel pressure requirements.

Advantageously, according to embodiments, the most precise pressure setting possible, in particular at absolute pressure values that are low compared to the supply pressure, can be used for the steering brake function (steer-by-brake), e.g. B. as a fallback level for electrically controllable steering, especially in highly automated driving, can be implemented as optimally as possible. Particularly in brake systems without a pneumatic pressure sensor between a valve for traction control or traction control and the brake cylinder, an exact setting of the required wheel brake pressures can be made possible. A pressure estimate, which calculates with a fixed pilot pressure that results from an operating pressure of a storage tank, can thus be dispensed with. A resolution of small pressure modulations in the brake cylinder of an individual wheel can be improved and made at least partially independent of the supply pressure or a regulation of the valve for traction control or traction control and a minimum control time of the pressure control valve for the individual wheels. Such a joint control or regulation of the steering brake function by both brake control devices via the interconnection of both brake control devices and thus the brake systems can be implemented cost-effectively or offer cost advantages.

• Beaufschlagen eines ersten Drucksteuerventils und eines zweiten Drucksteuerventils mit Druckluft mit einem Vorsteuerdruck mittels eines ersten Bremsensteuergeräts, wobei das erste Drucksteuerventil einer ersten Radbremse für ein erstes Rad einer lenkbaren Achse des Fahrzeugs zugeordnet ist, wobei das zweite Drucksteuerventil einer zweiten Radbremse für ein zweites Rad der lenkbaren Achse des Fahrzeugs zugeordnet ist, wobei der Vorsteuerdruck geringer als ein Vorratsdruck eines Druckluftvorrats des Fahrzeugs ist; und

A method for controlling a steering brake function for a vehicle is presented, the method having the following steps:

• Applying compressed air to a first pressure control valve and a second pressure control valve with a pilot pressure by means of a first brake control device, wherein the first pressure control valve is assigned to a first wheel brake for a first wheel of a steerable axle of the vehicle, wherein the second pressure control valve is assigned to a second wheel brake for a second wheel of the steerable Axle of the vehicle is assigned, wherein the pilot pressure is less than a supply pressure of a compressed air supply of the vehicle; and

Controlling the first pressure control valve and the second pressure control valve depending on a steering request signal by means of a second brake control device in order to apply a first brake pressure to the first wheel brake and a second brake pressure that is different from the first brake pressure to the second wheel brake, wherein the steering request signal represents a requested steering angle of the steerable Axis represents, whereby the first brake pressure and the second brake pressure are less than or equal to the pilot control pressure.

The vehicle can be a motor vehicle for transporting people and/or goods, in particular a passenger car, truck or other commercial vehicle. The steering brake function can also be referred to as a steer-by-brake function (SBB function). The steering brake function can function as a redundant steering system or steering support system in the event of a malfunction in an electrically controllable steering system of the vehicle. The first brake control device and additionally or alternatively the second brake control device can be pneumatically connected or connected to the compressed air supply. The first brake control device can be pneumatically and/or capable of transmitting signals or can be connected to the first pressure control valve and the second pressure control valve. The second brake control device can be pneumatically and/or capable of transmitting signals or can be connected to the first pressure control valve and the second pressure control valve. The first wheel brake may have a first brake cylinder that is pneumatically connectable or connected to the first pressure control valve. The second wheel brake may have a second brake cylinder that is pneumatically connectable or connected to the second pressure control valve.

According to one embodiment, in the actuation step, the first pressure control valve can be actuated by means of pulse width modulation or a modulation similar to pulse width modulation in order to apply the first brake pressure to the first wheel brake. Additionally or alternatively, in the actuation step, the second pressure control valve can be actuated by means of pulse width modulation in order to apply the second brake pressure to the second wheel brake. Each of the pressure control valves may be configured to admit pressure to the respective wheel brake, to exhaust pressure from the respective wheel brake, and to pneumatically lock the respective wheel brake. Such an embodiment offers the advantage that brake pressures for the wheels of the steerable axle can be adjusted individually, precisely and reliably.

Also, in the actuation step, the first pressure control valve and the second pressure control valve can be acted upon with a pilot pressure that is less than two-thirds or half of the supply pressure. Additionally or alternatively, in the actuation step, the first pressure control valve and the second pressure control valve can be actuated such that a pressure difference between the first brake pressure and the second brake pressure is at most 5 bar to at most 1 bar. Such an embodiment offers the advantage that the pilot control pressure, which is reduced compared to the supply pressure, enables precise adjustment of the brake pressures and, additionally or alternatively, small differences between the brake pressures for the different wheels can be set reliably and precisely.

Furthermore, in the actuation step, the first pressure control valve and the second pressure control valve can be acted upon with a pilot control pressure that has a steering brake component that is dependent on the steering request signal, or with a pilot control pressure that has a combination of the steering brake component and a brake component that is dependent on a brake request signal. The pilot pressure can also exclusively include the steering brake component. Such an embodiment offers the advantage that the steering brake function is independent of whether, in addition to a steering request regarding lateral guidance of the vehicle, there is also a braking request regarding a longitudinal guidance of the vehicle can be controlled safely and precisely.

According to one embodiment, the step of applying can be carried out by means of a first brake control device, which is part of an electronic braking system of the vehicle. Additionally or alternatively, the actuation step can be carried out using a second brake control unit, which is part of an anti-lock braking system of the vehicle. The first brake control device can be designed as a control device for the electronic brake system (EBS). The second brake control unit can be designed as a control unit for the anti-lock braking system (ABS). Such an embodiment offers the advantage that systems already present in many vehicles can be used to display the steering brake function, with the interconnection or networking of the brake control devices enabling precise setting of pressures for the individual wheel brakes that are small and different compared to the forward pressure.

In addition, in the actuation step, a third pressure control valve, which can be designed to make the first pressure control valve and the second pressure control valve pressurized with compressed air or to shut them off from compressed air, can be controlled by means of the second brake control device in order to supply the first pressure control valve and the second pressure control valve with compressed air to make it impactable. The third pressure control valve may function as a traction control valve, traction control valve, or the like. Such an embodiment offers the advantage that even with a brake system architecture with such a valve, by opening the same, the steering brake function can be implemented with precisely adjustable brake pressures that are low compared to the supply pressure.

The approach presented here also creates a control unit that is designed to carry out, control or implement the steps of a variant of a method presented here in corresponding devices or units. This embodiment variant of the invention in the form of a control unit can also solve the problem on which the invention is based quickly and efficiently.

For this purpose, the control unit can have at least one computing unit for processing signals or data, at least one storage unit for storing signals or data, at least one interface to a sensor or an actuator, for example at least one valve, for reading in sensor signals from the sensor or for outputting Control signals to the actuator and / or at least one communication interface for reading or outputting data that is embedded in a communication protocol. The computing unit can be, for example, a signal processor, a microcontroller or the like, whereby the storage unit can be a flash memory, an EEPROM or a magnetic storage unit. The communication interface can be designed to read in or output data wirelessly and/or by wire, wherein a communication interface that can read in or output wired data can, for example, read this data electrically or optically from a corresponding data transmission line or output it into a corresponding data transmission line.

In the present case, a control unit can be understood to mean an electrical device that processes sensor signals and/or request signals and, depending on this, outputs control and/or data signals. The control unit can have an interface that can be designed in hardware and/or software. In the case of a hardware design, the interfaces can, for example, be part of a so-called system ASIC, which contains a wide variety of functions of the control unit. However, it is also possible that the interfaces are their own integrated circuits or at least partially consist of discrete components. In the case of software training, the interfaces can be software modules that are present, for example, on a microcontroller alongside other software modules.

• eine Ausführungsform der vorstehend genannten Steuereinheit, wobei die Steuereinheit das erste Bremsensteuergerät und das zweite Bremsensteuergerät aufweist; und
• das erste Drucksteuerventil, das der ersten Radbremse für das erste Rad der lenkbaren Achse des Fahrzeugs zugeordnet ist, und das zweite Drucksteuerventil, das der zweiten Radbremse für das zweite Rad der lenkbaren Achse des Fahrzeugs zugeordnet ist, wobei das erste Bremsensteuergerät und das zweite Bremsensteuergerät der Steuereinheit signalübertragungsfähig und/oder pneumatisch mit dem ersten Drucksteuerventil und dem zweiten Drucksteuerventil verbunden sind.

A braking system for a vehicle is also presented, the braking system having the following features:

• an embodiment of the above-mentioned control unit, the control unit having the first brake control device and the second brake control device; and
• the first pressure control valve, which is assigned to the first wheel brake for the first wheel of the steerable axle of the vehicle, and the second pressure control valve, which is assigned to the second wheel brake for the second wheel of the steerable axle of the vehicle, wherein the first brake control device and the second brake control device Control unit capable of transmitting signals and/or pneumatically connected to the first pressure control valve and the second pressure control valve.

The braking system can be designed to provide the steering brake function. In connection with the braking system, an embodiment of the above-mentioned control unit can be advantageously used or used to To control the steering brake function of the braking system. The first brake control device can be designed as a part or control device of an electronic brake system. The second brake control device can be designed as a part or control device of an anti-lock braking system.

Also advantageous is a computer program product or computer program with program code, which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard drive memory or an optical memory and for carrying out, implementing and / or controlling the steps of the method according to one of the embodiments described above is used, especially if the program product or program is executed on a computer or a control unit.

• 1 eine schematische Darstellung eines Fahrzeugs mit einem Bremssystem gemäß einem Ausführungsbeispiel;
• 2 eine schematische Darstellung eines Fahrzeugs mit einem Bremssystem gemäß einem Ausführungsbeispiel; und
• 3 ein Ablaufdiagramm eines Verfahrens zum Steuern gemäß einem Ausführungsbeispiel.

Exemplary embodiments of the approach presented here are explained in more detail in the following description with reference to the figures. Show it:

• 1 a schematic representation of a vehicle with a braking system according to an exemplary embodiment;
• 2 a schematic representation of a vehicle with a braking system according to an exemplary embodiment; and
• 3 a flowchart of a method for controlling according to an exemplary embodiment.

1 shows a schematic representation of a vehicle 100 with a braking system 110 according to an exemplary embodiment. The vehicle 100 is a motor vehicle, in particular a passenger car, a truck or another commercial vehicle. According to the in 1 In the exemplary embodiment shown, the vehicle 100 is, merely by way of example, a truck or another commercial vehicle with three axles 170, 180 and 190. The vehicle 100 thus has a steerable axle 170, a first further axle 180 and, merely by way of example, a second further axle 190. A first wheel 172 and a second wheel 174 are arranged on the steerable axle 170. The first wheel 172 is a left wheel in relation to a forward direction of travel of the vehicle 100 and the second wheel 174 is a right wheel in relation to the forward direction of travel of the vehicle 100. The steerable axle 170 is a front axle of the vehicle 100, the further axles 180 and 190 Rear axles of the vehicle are 100.

The braking system 110 of the vehicle 100 includes a control unit 120 and a plurality of pressure control valves 152, 154 and 156. The brake system 110 also has a plurality of wheel brakes 162 and 164 with brake cylinders. According to the in 1 In the exemplary embodiment shown, the brake system 110 also has a compressed air supply 112 with, for example, only two containers for compressed air with a supply pressure. The supply pressure is, for example, 8 bar. The compressed air supply 112 serves to supply the control unit 120, the pressure control valves 152, 154 and 156 and the wheel brakes 162 and 164 with compressed air. Furthermore, the brake system 110 according to in 1 illustrated embodiment also has a foot brake module 114, which is pneumatically connected between the compressed air supply 112 and the control unit 120.

A first pressure control valve 152 is assigned to a first wheel brake 162 for the first wheel 172 of the steerable axle 170 of the vehicle 100. A second pressure control valve 154 is assigned to a second wheel brake 164 for the second wheel 174 of the steerable axle 170 of the vehicle 100. The control unit 120 is capable of transmitting signals and/or pneumatically connected to the first pressure control valve 152 and the second pressure control valve 154.

The control unit 120 is designed to control a steering brake function for the vehicle 100. The steering brake function can be implemented by the brake system 110. The braking system 110 can function as a redundancy level for an electrically assisted steering system of the vehicle 100. The control unit 120 has a first brake control device 130 and a second brake control device 140. The first brake control device 130 is pneumatically connected to the first pressure control valve 152 and the second pressure control valve 154. The second brake control device 140 is capable of transmitting signals and/or pneumatically connected to the first pressure control valve 152 and the second pressure control valve 154.

The first brake control device 130 is designed to apply compressed air with a pilot control pressure P1 to the first pressure control valve 152 and the second pressure control valve 154. The pilot pressure P1 is lower than the supply pressure of the compressed air supply 112. The first brake control device 130 is according to the in 1 illustrated embodiment is part of an electronic brake system (EBS) of the vehicle 100. The first brake control unit 130 has a pressure sensor for detecting the pilot control pressure P1.

The second brake control device 140 is designed to control the first pressure control valve 152 and the second pressure control valve 154 depending on a steering request signal in order to achieve the first Wheel brake 162 with a first brake pressure P2 and the second wheel brake 164 with a second brake pressure P3 that is different from the first brake pressure P2. The first brake pressure P2 and the second brake pressure P3 are less than or equal to the pilot control pressure P1. The steering request signal represents a requested steering angle of the steerable axle 170. The second brake control device 140 is according to the in 1 illustrated embodiment is part of an anti-lock braking system (ABS) of the vehicle 100.

More precisely, the first brake control device 130 is according to FIG 1 illustrated embodiment designed to set the pilot pressure P1 to less than half of the supply pressure. Furthermore, according to in 1 illustrated embodiment, the first brake control device 130 is designed to set a pilot pressure P1, which only has a steering brake component that is dependent on the steering request signal. In other words, the steering brake component represents a pressure value that is intended for the steering brake function. The pilot pressure P1 is a controlled or regulated pressure of, for example, 0.9 bar.

The second brake control unit 140 is according to in 1 illustrated embodiment is designed to control the first pressure control valve 152 and the second pressure control valve 154 so that a pressure difference between the first brake pressure P2 and the second brake pressure P3 is at most 1 bar. Here, the second brake control device 140 is designed to open one of the pressure control valves 152 and 154 and to close the other of the pressure control valves 152 and 154. The pressure difference is therefore, for example, 0.9 bar. For example, in order to realize or support a left turn of the vehicle 100 by means of the steering brake function, the second brake control device 140 is designed to open the first pressure control valve 152 and close the second pressure control valve 154. Thus, for example, a first brake pressure P2 of 0.9 bar is applied to the first wheel brake 162, with a second brake pressure P3 of 0 bar applied to the second wheel brake 164.

According to the in 1 In the illustrated embodiment, the brake system 110 also has a third pressure control valve 156. The third pressure control valve 156 is pneumatically connected between the control unit 120 and the first pressure control valve 152 and the second pressure control valve 154. The third pressure control valve 156 is designed to make the first pressure control valve 152 and the second pressure control valve 154 pressurized with compressed air with the pilot control pressure P1 or to shut them off from compressed air. The second brake control device 140 is designed to control the third pressure control valve 156 in order to make the first pressure control valve 152 and the second pressure control valve 154 pressurized with compressed air with the pilot control pressure P1. The third pressure control valve 156 is pneumatically connected to the first brake control device 130 and is capable of signal transmission and/or pneumatically connected to the second brake control device 140. The third pressure control valve 156 functions as a traction control valve.

With regard to the first further axle 180 and the second further axle 190, the brake system 110 has further wheel brakes and pressure control valves, which, however, are again explicitly designated here and described because they are irrelevant for the steering brake function.

In other words, a so-called SteerByBrake control or control of a steering brake function without superimposed braking can be implemented by means of the brake system 110, whereby the pilot control pressure P1, which is low compared to the supply pressure, or brake pressures which are low compared to the supply pressure, can also be precisely regulated by the second brake control device 140 the third pressure control valve 156 opens and one of the first pressure control valve 152 or the second pressure control valve 154 shuts off, while the other of the first pressure control valve 152 or the second pressure control valve 154 is opened, so that the first brake control device 130 directly controls the brake pressures or the brake pressure P2 or P3 in one of the wheels 172 or 174 can be adjusted.

2 shows a schematic representation of a vehicle 100 with a braking system 110 according to an exemplary embodiment. This corresponds to the vehicle 100 including the braking system 110, the mode of operation and the representation in 2 the vehicle including the braking system, the mode of operation and the representation 1 with the exception that, for example, a brake request signal for the control unit 120, in particular the first brake control device 130 of the control unit 120, is generated via the foot brake module 114. The brake request signal can be a pressure level that can be detected by the first brake control device 130.

Thus, according to in 2 illustrated embodiment, the first brake control device 130 is designed to set a pilot pressure P4, which has a combination of the steering brake component and a brake component dependent on a brake request signal. In other words, the braking component represents a pressure value that is intended for a braking function to decelerate the vehicle 100. The one before Control pressure P4 is a controlled or regulated pressure of, for example, 3.2 bar, with the steering brake component being 0.9 bar and the braking component being 2.3 bar. Due to the pilot control pressure P4 being reduced with respect to the supply pressure, the first pressure control valve 152 and the second pressure control valve 154 can advantageously be operated with a low pilot control pressure P4.

Furthermore, according to in 2 In the illustrated embodiment, the second brake control device 140 is designed to control the first pressure control valve 152 or the second pressure control valve 154 by means of pulse width modulation in order to apply different brake pressures P5 and P6 to the wheel brakes 162 and 164. To as in 1 To realize or support a left turn of the vehicle 100 by means of the steering brake function is according to in 2 In the illustrated embodiment, the second brake control device 140 is designed to open the first pressure control valve 152 and to control the second pressure control valve 154 by means of pulse width modulation. Thus, for example, a first brake pressure P5 of 3.2 bar is applied to the first wheel brake 162, with a second brake pressure P6 of 2.3 bar applied to the second wheel brake 164.

In other words, a so-called steer-by-brake control or control of a steering brake function with superimposed braking can be implemented by means of the brake system 110, e.g. B. via deceleration controller, whereby one of the first pressure control valve 152 and the second pressure control valve 154 is opened, while the other of the first pressure control valve 152 and the second pressure control valve 154 is controlled by means of pulse width modulation in order to one of the brake pressures, here the second brake pressure P6, to one lower pressure than the pilot control pressure P4. Here, the lower of the brake pressures P5 and P6 can be precisely modulated in a simple manner by the pulse width modulation, since the pilot control pressure P4 is lower than the supply pressure, the pilot control pressure P4 only being the maximum necessary pressure of the wheels 172 and 174 in view of the steering request signal and the braking request signal on the steerable axle 170 corresponds.

In other words, when operating the brake system 110 according to an exemplary embodiment in a vehicle 100 with a steered front axle or steerable axle 170, it is provided that the steering brake function, as soon as it is activated, makes a decision in a pressure coordinator of the brake system 110 in view of the steering request signal and Optionally, the necessary axle pressure or pilot control pressure P4 is determined in addition to the brake request signal, and this pilot control pressure P4 is set via the first brake control unit 130. In addition, the second brake control device 140 takes into account the calculated maximum pressure for regulating the first pressure control valve 152 and the second pressure control valve 154 via an adapted pressure estimate, while the third pressure control valve 156 remains inactive or is opened.

The third pressure control valve 156 is controlled by the ABS control unit or second brake control unit 140. The EBS control device or first brake control device 130 does not have access to the third pressure control valve 156, but has two valves with pressure sensors, which are not explicitly designated here. In 1 or. 2 A so-called trailer EBS with integrated pressure sensors and valves is shown as an example. According to one exemplary embodiment, these components can be mounted in a block, as in trailer EBS, or independently of one another, as in a so-called truck EBS. The EBS control unit or first brake control unit 130 can only set pressures on a circuit-by-circle basis, not on a wheel-by-wheel basis, but only one pressure on the front/rear axle at a time.

For the case that in 1 is shown, in the event of a steering failure while the first brake control device 130 and the second brake control device 140 are still fully functional, a conventionally necessary activation of the third pressure control valve 156 by the second brake control device 140 can be omitted, since the pilot control pressure P1 is provided by the EBS or z. B. the first brake control unit 130 is provided. The second brake control device 140 does not carry out any control of the first pressure control valve 152 and the second pressure control valve 154 in the event that a deceleration request is not requested at the same time or a brake request signal is present. These are simply controlled, with the valve on the inside of the curve being switched to open and the valve on the outside of the curve being shut off. The pressure in the brake cylinder is therefore regulated exclusively by the EBS, in particular the first brake control unit 130. The EBS can directly measure and/or regulate the pressure of the wheel brake on the inside of the curve using its existing pressure sensor.

In the case of superimposed braking, as in 2 shown and described, the valve on the inside of the curve, here z. B. the first pressure control valve 152, also not regulated by the pressure modulation function of the second brake control device 140, i.e. The first pressure control valve 152 is not activated and is therefore open, only the wheel on the outside of the curve, here the second wheel 174, needs such a control with reduced pilot pressure P4, which is measured by the EBS and is transmitted to the second brake control unit 140, e.g. B. via CAN in order to improve the pressure estimate of the second brake control device 140 or to influence it in a positive way, since the low pressure range, which can otherwise only be roughly adjusted using the first pressure control valve 152 or the second pressure control valve 154, can now be adjusted more finely.

The first pressure control valve 152 or the second pressure control valve 154 is a PCV (Pressure Control Valve) for each wheel brake 162 or 164, which has two coils and thus enables four states, three of which are permitted according to exemplary embodiments, which is achieved by a control -Software in the second brake control unit 140 ensures: CONSTRUCTION, DISMANTLING, HOLD. For pulse width modulation, a pressure level reached by the SETUP or REDUCTION state is maintained by the HOLD state.

The steering effect on steering axles is enhanced by the steering roll radius. Unsteered axles can also be used for the steering brake function, which also offers the advantages of combined pressure control by connecting several brake systems.

3 shows a flowchart of a method 300 for controlling according to an exemplary embodiment. The method 300 for controlling is executable to control a steering brake function for a vehicle. Here, the method 300 for control can be carried out in conjunction with the brake system from one of the figures described above or a similar brake system. The method 300 for controlling can also be carried out by means of or using a control unit from one of the figures described above or a similar control unit.

The method 300 for controlling has a step 310 of applying and a step 320 of driving. The actuation step 310 and the actuation step 320 can be carried out simultaneously or one after the other. The actuation step 310 and the actuation step 320 can also be carried out continuously and/or repeatedly.

In step 310 of pressurization, a first pressure control valve and a second pressure control valve are pressurized with a pilot control pressure using compressed air using a first brake control device. The first pressure control valve is assigned to a first wheel brake for a first wheel of a steerable axle of the vehicle. The second pressure control valve is assigned to a second wheel brake for a second wheel of the steerable axle of the vehicle. The pilot pressure is lower than a supply pressure of a compressed air supply of the vehicle.

In step 320 of the actuation, the first pressure control valve and the second pressure control valve are actuated by means of a second brake control device depending on a steering request signal in order to apply a first brake pressure to the first wheel brake and to apply a second brake pressure to the second wheel brake which is different from the first brake pressure. The first brake pressure and the second brake pressure are each less than or equal to the pilot control pressure. The steering request signal represents a requested steering angle of the steerable axle.

According to an exemplary embodiment, the method 300 for controlling can also have a step of reading in the steering request signal. The reading step can be carried out if a steering system of the vehicle has a fault.

REFERENCE SYMBOL LIST

100

vehicle

110

Braking system

112

Compressed air supply

114

Foot brake module

120

Control unit

130

first brake control unit

140

second brake control unit

152

first pressure control valve

154

second pressure control valve

156

third pressure control valve

162

first wheel brake

164

second wheel brake

170

steerable axle

172

first wheel

174

second wheel

180

first additional axis

190

second additional axis

P1

Pilot pressure

P2

first brake pressure

P3

second brake pressure

P4

Pilot pressure

P5

first brake pressure

P6

second brake pressure

300

Procedure for controlling

310

Pressing step

320

Control step

Claims (9)

Method (300) for controlling a steering brake function for a vehicle (100), the method (300) having the following steps: Actuating (310) a first pressure control valve (152) and a second pressure control valve (154) with compressed air with a pilot pressure (P1; P4) by means of a first brake control device (130), the first pressure control valve (152) being a first wheel brake (162) for a first wheel (172) is assigned to a steerable axle (170) of the vehicle (100), wherein the second pressure control valve (154) is assigned to a second wheel brake (164) for a second wheel (174) of the steerable axle (170) of the vehicle (100) is assigned, wherein the pilot pressure (P1; P4) is less than a supply pressure of a compressed air supply (112) of the vehicle (100); and Controlling (320) the first pressure control valve (152) and the second pressure control valve (154) depending on a steering request signal by means of a second brake control device (140) in order to apply the first wheel brake (162) to a first brake pressure (P2; P5) and the second wheel brake ( 164) to apply a second brake pressure (P3; P6) that is different from the first brake pressure (P2; P5), the steering request signal representing a requested steering angle of the steerable axle (170), the first brake pressure (P2; P5) and the second brake pressure (P3; P6) is less than or equal to the pilot control pressure (P1; P4), wherein in step (310) of applying, the first pressure control valve (152) and the second pressure control valve (154) are acted upon with a pilot pressure (P1; P4) which is less than two-thirds or half of the supply pressure, and/or in step ( 320) of the control, the first pressure control valve (152) and the second pressure control valve (154) are controlled so that a pressure difference between the first brake pressure (P2; P5) and the second brake pressure (P3; P6) is at most 5 bar to at most 1 bar . Procedure (300) according to Claim 1 , characterized in that in step (320) of activation, the first pressure control valve (152) is activated by means of pulse width modulation or a modulation similar to pulse width modulation in order to apply the first brake pressure (P2; P5) to the first wheel brake (162), and / or the second pressure control valve (154) is controlled by means of pulse width modulation in order to apply the second brake pressure (P3; P6) to the second wheel brake (164). Method (300) according to one of the preceding claims, characterized in that in the step (310) of applying, the first pressure control valve (152) and the second pressure control valve (154) are acted upon with a pilot pressure (P1) which has a steering brake component that is dependent on the steering request signal has, or with a pilot control pressure (P4), which has a combination of the steering brake component and a braking component dependent on a brake request signal. Method (300) according to one of the preceding claims, characterized in that the step (310) of applying is carried out by means of a first brake control device (130), which is part of an electronic braking system of the vehicle (100), and / or the step (320 ) of the control is carried out by means of a second brake control device (140), which is part of an anti-lock braking system of the vehicle (100). Method (300) according to one of the preceding claims, characterized in that in the step (320) of controlling a third pressure control valve (156), which is designed to pressurize the first pressure control valve (152) and the second pressure control valve (154) with compressed air make or shut off from compressed air, is controlled by means of the second brake control device (140) in order to make the first pressure control valve (152) and the second pressure control valve (154) pressurized with compressed air. Control unit (120) which is set up to carry out and/or control the steps of the method (300) according to one of the preceding claims in corresponding units (130, 140). Brake system (110) for a vehicle (100), the brake system (110) having the following features: a control unit (120) according to Claim 6 , wherein the control unit (120) has the first brake control device (130) and the second brake control device (140); and the first pressure control valve (152) associated with the first wheel brake (162) for the first wheel (172) of the steerable axle (170) of the vehicle (100), and the second pressure control valve (154) associated with the second wheel brake (164 ) for the second wheel (174) is assigned to the steerable axle (170) of the vehicle (100), the first brake control device (130) and the second brake control device (140) of the control unit (120) being able to transmit signals and/or pneumatically with the first pressure control valve (152) and the second pressure control valve (154). Computer program that is set up to implement a method (300) according to one of Claims 1 until 5 to execute and/or control. Machine-readable storage medium on which the computer program can be written Claim 8 is stored.

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