Method for operating a service brake with respect to an axle in order to brake a wheel of an axle of a vehicle, in particular a utility vehicle

Abstract

The invention relates to a method (100) for operating a service brake (210) with respect to an axle (205) in order to brake a wheel (215) of an axle (205) of a vehicle (200a), in particular a utility vehicle (200b), comprising another axle (205') which differs from the axle (205). The method (100) has the steps of: detecting (110) an input variable (260) related to the other axle (205'); ascertaining (120) a control variable (270) related to the axle using the input variable (260) related to the other axle (205'); and outputting (130) a control signal (280) in order to modify a braking variable (211) of the service brake (210) while taking into consideration the control variable (270) related to the axle.

Description

[0001] Method for operating a service brake related to an axle for

[0002] Braking a wheel of an axle of a vehicle, especially a commercial vehicle

[0003] The invention relates to a method for operating a service brake relative to an axle for braking a wheel of an axle of a vehicle, in particular a commercial vehicle, with a further axle different from the axle. The invention also relates to a computer program and / or computer-readable medium, a control unit for a vehicle, in particular a commercial vehicle, and a vehicle, in particular a commercial vehicle.

[0004] Braking systems for vehicles with an anti-lock braking system (ABS) are known from the prior art. The braking system is designed to apply a braking torque to one or more wheels of the vehicle in order to decelerate the vehicle. ABS reduces or prevents the locking of a wheel braked by the braking system by reducing brake pressure, thus improving braking and driving safety.

[0005] ABS systems are known for detecting the speed of the wheel to be braked and, if the speed changes too abruptly, reducing the brake pressure in order to prevent or stop the wheel from locking.

[0006] Furthermore, centrally controlled braking systems are known which enable brake force distribution and / or vehicle dynamics control, for example using input signals from a yaw rate sensor.

[0007] DE 10 2018 123 996 A1 discloses an at least two-channel electro-pneumatic central pressure control module designed as a structural unit for an electro-pneumatic service brake device of a vehicle, with at least two pressure control channels that can be electrically controlled with respect to a brake pressure.It is provided that a central electronic brake control unit has a circuit board carrying electrical and electronic components, wherein routines for at least brake pressure control and driving dynamics control are implemented in the electrical and electronic components, wherein at least one inertial sensor is arranged on or at the at least one circuit board and is electrically connected to at least some of the electrical and electronic components on the circuit board in such a way that the output signals of the at least one inertial sensor can be fed into the at least some electrical and electronic components for implementing driving dynamics control. Optionally, ABS pressure control valves can also be connected between the central pressure control module as the "central module" and brake cylinders on wheels of a first axle and a second axle, which allow wheel-individual control / regulation of the brake pressure in these brake cylinders.

[0008] The ABS pressure control valves are controlled by the central electronic brake control unit. A state-of-the-art anti-lock braking system for a wheel on an axle controls, regulates, and / or controls the braking of the wheel based on information relating to the wheel and / or axle itself, possibly influenced by an input signal from the central control unit.

[0009] However, such ABS control may lead to repeated axle load shifts and corresponding movement of a vehicle's driver's cab, particularly in the case of certain frictional characteristics of the road or subsoil and specific vehicle configurations.

[0010] The ABS can induce a vibration mode in the vehicle through repeated axle load shifts. This vibration mode can lead to repeated, for example, periodic, shifts in the axle load. This can be unpleasant for the driver and / or vehicle occupants.

[0011] In addition, a normal force acting between the wheels and the ground changes repeatedly.

[0012] An axle load shift during braking with ABS can lead to a deep wheel drop due to, for example, periodically increasing and decreasing normal forces on the vehicle's wheels or axles, i.e. to a comparatively abrupt and high amount of slip on one or more wheels.

[0013] If the axle load shift is comparatively large, it may happen that pressure regulating and / or pressure control devices are too slow to reduce the brake pressure in a brake chamber to such an extent that the locking of one or more wheels can be prevented.

[0014] Another problem can arise in a p-jump scenario (jump friction scenario). The p-jump scenario describes the transition from a surface with a comparatively high coefficient of friction between a wheel and the ground to a surface with a comparatively low coefficient of friction between the wheel and the ground.

[0015] When braking in such a p-step scenario, ABS faces the challenge of abruptly adapting the brake pressure to the change in the friction coefficient. For example, when the surface changes from asphalt to ice, the brake pressure must be abruptly reduced to ensure driving stability. In the opposite case, the brake pressure must be abruptly increased to achieve improved braking performance.

[0016] Furthermore, it is noticeable that ABS pressure control valves, for example, are subject to increasingly stringent requirements regarding their cost-effectiveness. Improving ABS control can therefore offset the effects of such requirements and / or still improve the effectiveness of the ABS.

[0017] The invention is therefore based on the object of enriching the prior art. One embodiment achieves the object of providing improved vehicle stability and / or reducing axle load shift and / or movements of a driver's cab, thus improving safety and comfort, even in a p-jump scenario. This object is achieved by a method according to claim 1 and the subject matter according to the further independent claims. The subclaims specify further developments of the invention.

[0018] According to one aspect of the invention, a method is provided for operating a service brake relative to an axle for braking a wheel of an axle of a vehicle, in particular a commercial vehicle, with a further axle different from the axle. The method comprises: detecting an input variable relative to the further axle; determining an axle-related control variable based on the input variable relative to the further axle; and outputting a control signal for changing a braking variable of the service brake, taking into account the axle-related control variable.

[0019] The vehicle, in particular a commercial vehicle, is referred to below as the "vehicle." The method is thus a method for monitoring or controlling and / or regulating the vehicle's service brake. The vehicle has a plurality of axles, namely at least the axle and the additional axle. For example, the axle is designed as the rear axle, and the additional axle is designed as the front axle.

[0020] To operate the service brake, the input variable related to the additional axle is recorded as a non-axle input variable. The input variable can be a variable related to a wheel of the additional axle, the additional axle, a drive and / or braking component associated with the wheel of the additional axle, and / or the additional axle. The input variable can be recorded using sensors and / or communication technology, for example, via a vehicle bus. The input variable can comprise a variety of different pieces of information. This enables a comprehensive characterization of variables potentially relevant to braking the wheel of the axle.

[0021] The axle-related control variable can be determined based on the input variable relating to the additional axle. The control variable is a variable relating to the axle with the wheel to be braked and / or to the wheel of the axle to be braked. The control variable can relate to the control of the braking of the wheel and / or the wheels of the axle. In other words, the control variable can be a wheel-related control variable, particularly in the case of wheel-specific braking control. It was recognized that the properties and / or characteristics of the additional axle that can influence the driving dynamics and / or driving stability can be used to infer corresponding properties and / or characteristics of the axle.

[0022] Taking the axle-related control variable into account, the control signal can be output to change the braking force of the service brake. The braking force can be adjusted, for example, based on the control variable. The control signal can bring about a predictable change in the control variable. The braking force can be a variable that determines the braking torque of the wheel and / or wheels of the axle, which can be applied to the service brake via the control signal.

[0023] By processing the input variable related to the other axle into the axle-specific control variable, cross-axle use of information within the vehicle is possible. The method can thus achieve cross-axle control of the service brake. This allows the service brake for one axle to be adjusted and / or adjusted based on the service brake of the other axle. For example, an axle load shift caused by a wheel falling off on the other axle can be detected, allowing the system to intervene in the braking of the wheel on that axle.

[0024] Furthermore, the approach enables improved operation of the service brake in the p-jump scenario. For example, during a transition from asphalt to ice, a wheel falling off the front axle can be used as a preventative measure to control braking on the rear axle.

[0025] The invention provides an approach that makes it possible to control the wheel and / or the axle with the service brake depending on information, data or variables that are independent of or only indirectly dependent on the control of the wheel and / or the axle, but relate to the other axle. It was recognized that such a variable can typically describe vehicle dynamics, an environment and / or other circumstances and / or characteristics that can influence the control of the service brake assigned to the axle. Such an approach can also be applied with reference to automated driving functions and / or applications for autonomous driving, since in these cases, meaningful input variables are typically already recorded and / or processed by the vehicle.

[0026] The method can be applied to each individual wheel, i.e., to only one wheel on the axle. Alternatively or additionally, the method can be applied to multiple wheels on the axle and / or to multiple wheels in an axle package comprising multiple axles.

[0027] The service brake optionally includes an anti-lock braking system, and the input variable indicates whether ABS control of the service brake is in effect. It was recognized that intervening in the ABS control, in particular, can improve vehicle stability, as the ABS control can be the reason for repeated axle load shifts and thus vehicle oscillations, and / or the response of the service brake to changes in friction coefficients in the p-step scenario when braking with ABS control can be improved, particularly through cross-axle control. Alternatively or additionally, the input variable includes a slip of the wheel on the other axle, a wheel deceleration of the wheel on the other axle, and / or a control signal for controlling a braking variable for braking the wheel on the other axle.It was recognized that from the previously mentioned variables and their temporal development it can be deduced whether a repeated axle load shift occurs and / or a p-jump scenario is present in combination with an ABS control.

[0028] Optionally, the control signal can be output in such a way that the braking force remains constant or decreases when a normal force acting on the wheel of the other axle decreases, and / or the braking force increases when a normal force acting on the wheel of the other axle increases. This can counteract an oscillating movement of the vehicle. By maintaining or reducing the braking force, a falling of one or more wheels on the axle can be counteracted. By increasing the braking force, braking performance can be improved when the friction coefficient of a surface changes from a low to a high friction coefficient.

[0029] Optionally, the input variable can be used to determine the vibration behavior and / or axle load shift of the vehicle, and the control variable is determined taking the vibration behavior and / or axle load shift into account. For this purpose, a temporal development of the input variable can be recorded and processed. For example, a Fourier transformation or similar method can be used to detect vehicle vibration. If a vibration is detected, the control variable can be adjusted accordingly, for example, repeatedly over time, to suppress vehicle vibration. It was recognized that the vibration behavior and the axle load shift each influence the normal force acting between the wheel and the ground.If the vehicle's weight shifts toward the axle or the axle load shifts toward the axle, the normal force typically increases, which can prevent the wheel from locking. If the vehicle's weight shifts away from the axle or the axle load shifts away from the axle, the normal force typically decreases, which can promote wheel locking. Therefore, it has been recognized that the axle load shift and / or the vibration behavior is a suitable, quantifiable, and effectively measurable parameter that can influence the control of the service brake to improve braking.

[0030] Optionally, the input variable includes a friction coefficient between the wheel of the additional axle and the ground. This allows the input variable to directly provide information about the expected friction coefficient between the wheel of the axle to be braked. This allows a prediction of a change in the friction coefficient to be taken into account when controlling the braking variable. For this purpose, the control variable optionally includes a difference between the friction coefficient between the wheel of the additional axle and the ground and a friction coefficient between the wheel of the axle and the ground. Optionally, the control variable includes a prediction of the friction coefficient between the wheel of the axle and the ground.Based on the prediction of the friction coefficient between the wheel of the axle and the ground, preventive measures can be taken to control the braking force, in particular to avoid wheel slippage and thus improve vehicle stability and / or to improve braking performance.

[0031] According to one aspect of the invention, a computer program and / or a computer-readable medium is provided. The computer program and / or the computer-readable medium comprise instructions which, when the program or instructions are executed by a computer, cause the computer to perform the method according to the invention and / or steps thereof. Optionally, the computer program and / or the computer-readable medium comprises instructions which, when the program or instructions are executed by a computer, cause the computer to perform the method steps described as advantageous or optional in order to achieve an associated technical effect.

[0032] According to one aspect of the invention, a control unit for a vehicle, in particular a commercial vehicle, is provided. The control unit is configured to carry out the method described above. Optionally, the control unit is configured to carry out the method in such a way that one or more of the features described above as optional are implemented in order to achieve an associated technical effect.

[0033] According to one aspect of the invention, a vehicle, in particular a commercial vehicle, comprising a service brake with an anti-lock braking system and the control unit described above is provided. The control unit may have one or more features described as optional in order to achieve an associated technical effect.

[0034] Further advantages and features of the invention, as well as their technical effects, will become apparent from the figures and the description of the preferred embodiments shown in the figures. Figure 1 shows a schematic representation of a vehicle, in particular a commercial vehicle, according to one embodiment of the invention;

[0035] Fig. 2 is a schematic representation of a flow chart of a method according to an embodiment of the invention;

[0036] Fig. 3 shows a time series of wheel speeds and brake pressures of a commercial vehicle according to the prior art; and

[0037] Fig. 4 shows a time series of wheel speeds and brake pressures and a control signal of a commercial vehicle according to an embodiment of the invention.

[0038] Figure 1 shows a schematic representation of a vehicle 200a, in particular commercial vehicle 200b, of an embodiment of the invention.

[0039] The vehicle 200a, in particular the commercial vehicle 200b, is referred to below as the vehicle 200a, 200b. The vehicle 200a, 200b is a land vehicle, for example, a tractor of a multi-unit commercial vehicle.

[0040] The vehicle 200a, 200b is arranged in an environment on a surface 300. The surface 300 is, for example, a roadway with possibly locally varying characteristics. The characteristics of the surface 300 influence a friction value or friction coefficient MU, MU' and thus the driving dynamics of the vehicle 200a, 200b and, in particular, the braking of the vehicle 200a, 200b.

[0041] The vehicle 200a, 200b comprises a plurality of axles 205, 205', for example, two axles 205, 205'. The vehicle 200a, 200b comprises a plurality of wheels 215, 215' assigned to the axles 205, 205', for example, two wheels 215, 215' per axle 205, 205'. In an embodiment not shown, the vehicle 200a, 200b has more than two axles 205, 205' and / or the vehicle 200a, 200b has more than two, for example, four, wheels 215, 215' on at least one of the axles 205, 205'. The vehicle 200a, 200b is arranged with the wheels 215, 215' on the ground 300. This means that the wheels 215, 215' contact the ground 300. The wheels 215, 215' and the ground 300 are operatively connected to one another at a contact surface. The friction coefficient MU, MU' can be defined at the contact surface between the wheels 215, 215' and the ground 300, which characterizes the contact between the respective wheel 215, 215' and the ground 300.The friction coefficient MU, MU' can be different for each of the wheels 215, 215'.

[0042] Due to the contact of the wheels 215, 215' with the ground 300, a normal force FN acts between the wheels 215, 215' and the ground 300. The normal force FN is perpendicular to the contact area between the respective wheel 215, 215' and the ground 300. With a horizontally aligned roadway as the ground 300 and a stationary vehicle 200a, 200b, the normal force FN can act, for example, in a vertical direction. The ground 300 can have a road incline, i.e., the roadway as the ground 300 can have an uphill and / or downhill gradient. The vehicle 200a, 200b has force sensors (not shown) that determine the normal force FN and / or a difference between a normal force FN in a rest position of the vehicle 200a, 200b and an existing normal force FN. The force sensors can, for example, measure a force associated with a deflection of a component of a chassis of the vehicle 200a, 200b.

[0043] The vehicle 200a, 200b includes a service brake 210. The service brake 210 is a pneumatic, hydraulic, and / or electromechanical brake. The service brake 210 is configured to achieve a braking effect for braking the vehicle 200a, 200b. For this purpose, the service brake 210 is configured to decelerate a movement of the wheels 215, 215' or to control and / or regulate a deceleration of the movement of the wheels 215, 215'. The service brake 210 can apply a braking variable 211, for example, a braking torque, a braking force, and / or a braking pressure, to decelerate the wheel(s) 215, 215'. Driving and / or braking the vehicle 200a, 200b results in slippage 262 and wheel deceleration 264 at the wheels 215, 215'. The service brake 210 includes an anti-lock braking system 220.The anti-lock braking system 220 is configured to detect a tendency of the wheels 215, 215' to lock and to prevent the wheels 215, 215' from locking and / or to reduce the tendency of the wheels 215, 215' to lock. For this purpose, the anti-lock braking system 220 is configured to intervene in the braking process and reduce the braking force 211 if, for example, a tendency to lock is detected. Thus, the anti-lock braking system 220 is configured to perform an ABS control 221.

[0044] Braking of the vehicle 200a, 200b can cause an axle load shift 272. In doing so, the vehicle 200a, 200b can tilt. For example, the vehicle 200a, 200b initially tilts forward during braking. The chassis of the vehicle 200a, 200b compresses at the front and extends at the rear. As a result, the normal force FN acting on the wheels 215 of the axle 205, configured as the front axle, increases, and the normal force FN acting on the wheels 215' of the additional axle 205', configured as the rear axle, decreases. When deceleration decreases, for example, when the braking force 211 is reduced, the chassis of the vehicle 200a, 200b compresses at the rear and extends at the front. The normal force FN on the wheels 215 of the axle 205 designed as the front axle decreases and the normal force FN on the wheels 215' of the further axle 205' designed as the rear axle increases.

[0045] The vehicle 200a, 200b comprises a control unit 250. The control unit 250 is configured to carry out the method 100 described with reference to Figure 2.

[0046] The control unit 250 according to Figure 1 is configured to detect an input variable 260 related to the additional axle 205'. The input variable 260 relates to the additional axle 205' and / or the additional wheels 215' of the additional axle 205', or a drive and / or braking system of the additional axle 205'. The input variable 260 indicates whether ABS control 221 is performed by the anti-lock braking system 220 of the service brake 210. Additionally or alternatively, the input variable 260 includes a slip 262 of the wheel 215' of the additional axle 205', a wheel deceleration 264 of the wheel 215' of the additional axle 205', and / or a control signal 211' for controlling a braking variable 211' for braking the wheel 215' of the additional axle 205'. In addition or alternatively to the wheel deceleration 264, the wheel speed 410 can be detected using a speed sensor. For this purpose, the control unit 250 is connected to corresponding sensors and / or a vehicle bus (not shown).In particular, via the vehicle bus, the control unit 250 can retrieve information concerning operating data of the vehicle 200a, 200b as non-axle input variable 260.

[0047] The control unit 250 is configured to determine an axle-related control variable 270 based on the input variable 260 related to the additional axle 205'. Based on the input variable 260, a vibration behavior 201 and an axle load shift 272 of the vehicle 200a, 200b are determined. The control variable 270 is determined taking into account the vibration behavior 201 and the axle load shift 272. Thus, based on the input variable 260, for example, the temporal development of normal forces FN and / or slip 262 or wheel speeds 410 can be deduced (see Figure 4).

[0048] The control unit 250 is configured to output a control signal 280 to the service brake 210 for changing the braking variable 211 of the service brake 210, taking into account the axle-related control variable 270. The control signal 280 is output such that the braking variable 211 remains constant or decreases when a normal force FN acting on the wheel 215' of the additional axle decreases, and / or the braking variable 211 increases when a normal force FN acting on the wheel 215' of the additional axle 205' increases. Such a control signal 280 is shown in Figure 4 and described with reference to Figure 4.

[0049] The control signal 280 is output such that the change in the braking variable 211 occurs alternatively, in addition to, and / or alternately with an ABS control 221 by the anti-lock braking system 220. The control signal 280 is output such that the change in the braking variable 211 and an ABS control 221 by the anti-lock braking system 220 are overlapped.

[0050] The vehicle 200a, 200b is further configured to reduce and / or avoid potential negative effects of an axle load shift 272. A significant axle load shift 272 can cause a wheel 215, 215' to drop abruptly, i.e., an excessive and undesirable increase in slip 262, for example, due to a decreasing normal force FN acting on the wheel 215, 215'. If the axle load shift 272 is too significant, a prior art braking system may not be able to provide the required pressure reduction quickly enough, thus further amplifying the axle load shift 272 (see Figure 3).

[0051] The vehicle 200a, 200b according to Figure 1 is configured to keep the braking variable 211 for the front axle 205 constant or to reduce it when the additional wheel 215' of the additional axle 205', i.e., the rear axle, drops (see Figure 4). This can counteract a drop in the wheel 215 of the front axle 205 during a subsequent rearward axle load shift 272. Alternatively or additionally, the control unit 250 is configured to calculate a model for the axle load shift 272 and / or vibration characteristics 201, predict the axle load shift 272, and change the braking variable 211 according to a prediction of the axle load shift 272.

[0052] In another embodiment, the axle 205 may be designed as a rear axle and the further axle 205' may be designed as a front axle.

[0053] The vehicle 200a, 200b is in a p-jump scenario (jump friction scenario). In the p-jump scenario, the friction coefficient MU of axle 205 is different from the friction coefficient MU' of the further axle 205'. For example, the friction coefficient MU' of the further axle 205' can be determined using the input variable 260. The control variable 270 comprises a difference between the friction coefficient MU' between the wheel 215' of the further axle 205' and the ground 300 and a friction coefficient MU between the wheel 215 of the axle 205 and the ground 300. The control variable 270 comprises a prediction of a friction coefficient MU between the wheel 215 of the axle 205 and the ground 300.

[0054] The p-jump scenario exploits the fact that, when the vehicle 200a, 200b travels forward, the additional axle 205' configured as the front axle has already experienced a change in the friction coefficient MIT compared to the friction coefficient MU of the axle 205 configured as the rear axle. Such a change in the friction coefficient MU will also occur at the rear axle 205. Thus, the future friction coefficient MU of the rear axle 205 can be deduced from the difference between the friction coefficients MU, MU'. Based on this, the operation of the service brake 210 can be preventively adjusted by the control signal 280. When a transition from a high friction coefficient MU, MU' to a low friction coefficient MU, MU' occurs, for example when changing road surface from asphalt to ice, the braking quantity 211 can be maintained, reduced and / or an increase in the braking quantity 211 can be mitigated.If a transition from a low friction coefficient MU, MU' to a high friction coefficient MU, MU' occurs, for example when changing road surface from ice to asphalt, the braking quantity 211 can be increased.

[0055] The vehicle 200a, 200b is configured to perform automated driving functions. This allows the vehicle 200a, 200b to acquire information about the ground 300 along a trajectory to be traveled from other vehicles that have already traveled the trajectory. Based on the vehicle-external data and data relating to the ground 300, a change in the road surface properties, and in particular the friction coefficients, along the trajectory can be predicted, and based on a prediction of the friction coefficients along the trajectory, the braking variable 211 can be adjusted.

[0056] Figure 2 shows a schematic representation of a flow chart of a method 100 according to an embodiment of the invention. The method 100 is a method 100 for operating a service brake 210 relative to an axle 205 for braking a wheel 215 of an axle 205 of a vehicle 200a, in particular a commercial vehicle 200b, with a further axle 205' different from the axle 205. Such a vehicle 200a, 200b is described with reference to Figure 1. Figure 2 is described with reference to Figure 1.

[0057] According to Figure 2, the method 100 comprises: detecting 110 an input variable 260 related to the further axle 205'. The service brake 210 has an anti-lock braking system 220, and the input variable 260 indicates whether ABS control 221 of the service brake 210 is taking place. Additionally or alternatively, the input variable 260 includes a slip 262 of the wheel 215' of the further axle 205', a wheel deceleration 264 of the wheel 215' of the further axle 205', and / or a control signal for controlling a braking variable 211' for braking the wheel 215' of the further axle 205'. Based on the input variable 260, a vibration behavior 201 and an axle load shift 272 of the vehicle 200a, 200b are determined.

[0058] The method 100 comprises: determining 120 an axle-related control variable 270 based on the input variable 260 related to the further axle 205'. The control variable 270 comprises a difference between the friction coefficient MIT between the wheel 215' of the further axle 205' and the ground 300 and a friction coefficient MU between the wheel 215 of the axle 205 and the ground 300. The control variable 270 comprises a prediction of a friction coefficient MU between the wheel 215 of the axle 205 and the ground 300. The control variable 270 is determined taking into account the vibration behavior 201 and the axle load shift 272.

[0059] The method 100 comprises: outputting 130 a control signal 280 for changing a braking variable 211 of the service brake 210 taking into account the axle-related control variable 270. The control signal 280 is output such that the braking variable 211 remains constant or decreases when a normal force FN acting on the wheel 215' of the further axle decreases, and / or the braking variable 211 increases when a normal force FN acting on the wheel 215' of the further axle 205' increases.

[0060] Figure 3 shows a time series 400 of wheel speeds 410 and brake pressures 420 of a commercial vehicle 200b according to the prior art. Figure 3 is described with reference to the terminology used in relation to Figures 1 and 2.

[0061] The time series 400 in Figure 3 are plotted as a function of time t in seconds. In an upper part of Figure 3, the wheel speeds 410 with indices a, b, c, and d and a vehicle speed 411 are shown. In a lower part of Figure 3, the brake pressures 420 are shown as brake variable 211 with indices a, b, c, and d.

[0062] The vehicle speed 411 is shown for reference. The wheel speed 410, labeled a, is the wheel speed 410 of a left wheel 215 of the axle 205 configured as the front axle. The wheel speed 410, labeled b, is the wheel speed 410 of a right wheel 215 of the axle 205 configured as the front axle. The wheel speed 410, labeled c, is the wheel speed 410 of a left wheel 215' of the axle 205' configured as the rear axle. The wheel speed 410, labeled d, is the wheel speed 410 of a right wheel 215' of the axle 205' configured as the rear axle.

[0063] The brake pressure 420 marked with index a is the brake pressure 420 of the left wheel 215 of the axle 205 designed as the front axle. The brake pressure 420 marked with index b is the brake pressure 420 of the right wheel 215 of the axle 205 designed as the front axle. The brake pressure 420 marked with index c is the brake pressure 420 of the left wheel 215' of the axle 205' designed as the rear axle. The brake pressure 420 marked with index d is the brake pressure 420 of the right wheel 215' of the axle 205' designed as the rear axle.

[0064] According to the example in Figure 3, the commercial vehicle 200b is brought to a standstill by emergency braking, starting from a vehicle speed 411 of 50 km / h. ABS control 221 is performed by the anti-lock braking system 220 of the service brake 210. All of the wheels 215, 215' repeatedly and at regular intervals experience deep slippage, which is evident in the upper part of Figure 3 by a sharp drop in the wheel speed 410 compared to the vehicle speed 411. The front axle 205, in particular, is particularly frequently and severely affected. This is due to the axle load shift or axle load shift 272.

[0065] The front axle 205 is particularly affected because the vehicle 200b is fully loaded. As a result, a higher normal force FN acts on the wheels 215' of the rear axle 205' than on the wheels 215 of the front axle 205. Therefore, the wheels 215' of the rear axle 205' are more likely to slip 262.

[0066] The lower part of Figure 3 shows the brake pressures 420. It can be seen that the service brake 210 of the front axle 205 builds up a brake pressure 420 before the wheels 215 of the front axle 205 plunge into deep wheel slip 262. This is followed by an immediate reduction of the brake pressure 420 by venting. However, due to the chassis of the commercial vehicle 200b, the commercial vehicle 200b exhibits an axle load shift 272. Thus, for example, due to a decreasing normal force FN on the wheels 215 of the front axle 205, a pressure reduction can hardly prevent deep wheel slip.

[0067] Figure 4 shows a time series 400 of wheel speeds 410 and brake pressures 420, and a control signal 280, of a commercial vehicle 200b according to an embodiment of the invention. Such a vehicle 200b is described with reference to Figures 1 and 2. Figure 4 is described with reference to Figures 1 to 3. The differences between the time series of Figures 3 and 4 are described. The indexing of the time series 400 of Figures 3 and 4 is identical.

[0068] Compared to Figure 3, Figure 4 has a third part. A control signal 280 is shown below the brake pressures 420, for example. The control signal 280 is represented in binary form. A lower value (zero) indicates that the service brake 210 can be controlled as in the prior art. An upper value (one) indicates that the service brake 210 is subjected to the control signal 280, and the service brake 210 is controlled according to the method 100 of Figure 2.

[0069] From the brake pressures 420 it can be seen that the control signal 280 is output in such a way that the brake pressures 420 at the wheels 215 of the front axle 205 are reduced and then maintained, while a wheel fall is observed at the rear axle 205'.

[0070] Figure 4 accordingly shows a significant improvement in the wheel speeds 410 of the slip 262 of each of the wheels 215, 215' compared to Figure 3. The wheels 215, 215' exhibit hardly any critical slip 262. An occupant in the vehicle 200a, 200b can observe, and it can be determined by measurement, that an oscillatory movement 201 of the vehicle 200a, 200b is suppressed and the vehicle 200a, 200b no longer rocks, since an axle load shift 272 and / or an oscillation mode of the vehicle 200a, 200b can be suppressed.

[0071] Reference symbol (part of the description)

[0072] 100 procedures

[0073] 110 Capture

[0074] 120 Investigate

[0075] 130 Issues

[0076] 200a vehicle

[0077] 200b commercial vehicle

[0078] 201 Vibration behavior

[0079] 205, 205' axis

[0080] 210 Service brake

[0081] 211 , 211' brake size

[0082] 215, 215' wheel

[0083] 220 Anti-lock braking system

[0084] 250 control unit

[0085] 260 Input size

[0086] 262 slip

[0087] 264 Wheel deceleration

[0088] 270 Control variable

[0089] 272 Axle load shift

[0090] 275 Vehicle reference speed

[0091] 280 control signal

[0092] 300 underground

[0093] 400 time series

[0094] 410 wheel speed

[0095] 411 Vehicle speed

[0096] 420 Brake pressure t time

[0097] FN Normal force

[0098] MU, MU' friction coefficient

Claims

Patent claims 1 . Method (100) for operating a service brake (210) related to an axle (205) for braking a wheel (215) of an axle (205) of a vehicle (200a), in particular a commercial vehicle (200b), with a further axle (205') different from the axle (205), the method (100) comprising: - detecting (110) an input variable (260) related to the further axis (205'); - determining (120) an axis-related control variable (270) based on the input variable (260) related to the further axis (205'); and - Outputting (130) a control signal (280) for changing a braking variable (211) of the service brake (210) taking into account the axle-related control variable (270).

2. Method (100) according to claim 1, wherein the service brake (210) comprises an anti-lock braking system (220) and the input variable (260) indicates whether an ABS control (221) of the service brake (210) is taking place, the input variable (260) comprises a slip (262) of the wheel (215') of the further axle (205'), a wheel deceleration (264) of the wheel (215') of the further axle (205') and / or a control signal for controlling a braking variable (211') for braking the wheel (215') of the further axle (205').

3. Method (100) according to one of the preceding claims, wherein the control signal (280) is output such that the braking variable (211) remains constant or decreases when a normal force (FN) acting on the wheel (215') of the further axle decreases, and / or the braking variable (211) increases when a normal force (FN) acting on the wheel (215') of the further axle (205') increases.

4. Method (100) according to one of the preceding claims, wherein a vibration behavior (201) and / or an axle load shift (272) of the vehicle (200a), in particular a commercial vehicle (200b), is determined on the basis of the input variable (260), and the control variable (270) is determined taking into account the vibration behavior (201) and / or the axle load shift (272).

5. Method (100) according to one of the preceding claims, wherein the input variable (260) comprises a friction coefficient (MIT) between the wheel (215') of the further axle (205') and a ground (300).

6. The method (100) according to claim 5, wherein the control variable (270) comprises a difference between the friction coefficient (MU') between the wheel (215') of the further axle (205') and the ground (300) and a friction coefficient (MU) between the wheel (215) of the axle (205) and the ground (300).

7. The method (100) according to claim 5 or 6, wherein the control variable (270) comprises a prediction of a friction coefficient (MU) between the wheel (215) of the axle (205) and the ground (300).

8. Computer program and / or computer-readable medium comprising instructions which, when the program or instructions are executed by a computer, cause the computer to carry out the method (100) and / or the steps of the method (100) according to one of the preceding claims.

9. Control unit (250) for a vehicle (200a), in particular a commercial vehicle (200b), wherein the control unit (250) is configured to carry out the method (100) according to one of claims 1 to 7.

10. Vehicle (200a), in particular a commercial vehicle (200b), comprising a service brake (210) with an anti-lock braking system (220) and the control unit (250) according to claim 9.

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