Method for operating an electropneumatic braking system for a vehicle, in particular a commercial vehicle, computer program and / or computer-readable medium, controller, and vehicle

Abstract

The invention relates to a method (100) for operating an electropneumatic braking system (290) for a vehicle (200a), in particular a commercial vehicle (200b). The vehicle (200a) comprises a pneumatic suspension system (260) having a bellows (265) and a pressure sensor (270) for measuring a bellows pressure (pB) of the bellows (265). The bellows pressure (pB) is measured during braking effected by a braking request (BA) and achieved with a braking pressure (BP). A braking parameter (B) is determined on the basis of the bellows pressure (pB) and / or a bellows-pressure change (pD) that is derivable from the bellows pressure (pB) and a braking parameter difference (BD) between the braking parameter (B) and a target braking parameter (BS) that is determinable on the basis of the braking request (BA) and / or the braking pressure (BP) is determined. A control signal (251) for adapting the braking pressure (BP) is output depending on the braking parameter difference (BD).

Description

[0001] Method for operating an electropneumatic braking system for a vehicle, in particular a commercial vehicle, computer program and / or computer-readable medium, control unit, and vehicle

[0002] The disclosure relates to a method for operating an electropneumatic braking system for a vehicle, in particular a commercial vehicle, wherein the vehicle has a pneumatic suspension system with a bellows and a pressure sensor for detecting a bellows pressure of the bellows. The disclosure 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, having a pneumatic suspension system with a bellows, having an electropneumatic braking system with a brake cylinder, a pressure sensor device for detecting a bellows pressure of the bellows and a brake pressure of the brake cylinder, and having a control unit connected to the pressure sensor device.

[0003] The vehicle, in particular a commercial vehicle, is referred to below as a "vehicle." Such a vehicle has a plurality of wheels. One or more of the wheels contact a surface with a wheel contact patch. A braking force can be the force acting on each wheel contact patch in the longitudinal direction of the vehicle against the driving speed during braking or deceleration of the vehicle. The braking force cannot be precisely determined during operation, i.e., while driving or during braking, because no sensors for measuring the braking force can be arranged on the tire contact patches.

[0004] Monitoring the braking force and / or a braking variable related to the braking force can be desirable in order to obtain information about the condition or possible defects of a brake generating the braking force and / or a component of the brake. In particular, the braking effect of a brake with brake pads assigned to a wheel can decrease over time. This can happen due to the brake pads becoming sleepy due to insufficient temperature introduction. Reasons for this can include: vehicles with wear-free continuous brakes (retarders) which are used instead of brakes with brake pads, electrified vehicles with recuperation systems as wear-free continuous brakes, frequent driving with low axle load so that the braking system only applies low brake pressures taking the axle load into account, and predominantly driving at a constant speed over long distances, for example in long-distance haulage.

[0005] WO 2016 / 030699 A1 discloses a method for monitoring the braking performance of a vehicle. The method comprises, for at least some braking events: determining a braking demand; determining the vehicle deceleration; defining a first data set of braking events, wherein each braking event in the data set includes a determined braking demand and a determined vehicle deceleration; applying a statistical trend analysis method to the data set to generate a vehicle deceleration and braking demand trend; providing a vehicle deceleration and braking demand reference; and comparing at least one trend value with at least one reference value. Based on this comparison, it can be determined whether the braking system is operating within acceptable limits. An apparatus for carrying out the method is also disclosed.

[0006] This is a known method in which the trailer braking effect is monitored by measuring the vehicle deceleration. In other words, an algorithm calculates while driving, based on available sensors (e.g. axle load, wheel speeds and vehicle acceleration), whether and how the deceleration correlates with the vehicle mass due to the current brake pressure. Since such systems are often implemented only in the trailer and their control unit has no information about a continuous brake and / or recuperation system installed in the towing vehicle, defects in individual wheel brakes of the trailer can go undetected. In addition, wheel speed sensors are required on all wheels for improved functionality, which is typically not the case in trailers. In three-axle vehicles, usually only the middle axle is sensored.

[0007] DE 10 2022 127 155.2, which was not yet disclosed on the date of filing, describes a method which issues a warning based on the measured braking force in the event of a deviation from a current target value.

[0008] Other methods require sensors on each individual wheel brake, which can be complex, error-prone and costly.

[0009] The disclosure is based on the object of enriching the state of the art and improving aspects of the prior art. In particular, the disclosure solves the problem of enabling the restoration of a required deceleration in the event of a detected deviation.

[0010] The problem is solved by a method according to claim 1 and the subject matter according to the further independent claims. The subclaims specify further developments of the disclosure.

[0011] According to one aspect of the disclosure, a method is provided for operating an electropneumatic braking system for a vehicle, in particular a commercial vehicle, wherein the vehicle has a pneumatic suspension system with a bellows and a pressure sensor for detecting a bellows pressure of the bellows. The bellows pressure is detected during braking initiated by a braking request and achieved with a braking pressure. A braking variable is determined based on the bellows pressure and / or a bellows pressure change derivable from the bellows pressure, and a braking variable difference between the braking variable and a target braking variable determinable based on the braking request and / or the braking pressure is determined. A control signal for adjusting the braking pressure as a function of the braking variable difference is output.

[0012] It was recognized that the braking force acting on one of the wheels can influence the pressure within the bellows. Braking of a wheel results in a braking torque acting on the wheel, and this braking torque results in a force on the bellows. The bellows is designed to control the position of the wheel relative to, for example, a vehicle frame. The pressure within the bellows can change, for example through pressure control counteracting the force, through compression of the bellows, or through expansion of the bellows. Braking of the vehicle can therefore lead to a change in the bellows pressure. The bellows pressure can be measured by sensors to determine the change in the bellows pressure.

[0013] It has been recognized that there is a relationship between the change in bellows pressure and the force acting on the bellows, and that the force acting on the bellows depends on the braking force. Therefore, the change in bellows pressure can be used to determine the braking force. To determine the braking force, the change in bellows pressure can be multiplied by a constant, particularly one specific to the vehicle or vehicle type, and / or other factors can be considered to increase accuracy.

[0014] This enables on-board measurement of the braking force of a vehicle, and especially of a trailer. Especially with a trailer, the braking force can be determined largely independently of influences from the towing vehicle. Determining the braking force eliminates the need for additional sensors such as height sensors, force sensors, or strain gauges, and enables reliable and effective determination of the braking force. It eliminates the need, for example, to take a height measurement and convert a height change into a volume change of the bellows using a complicated relationship in order to determine the braking force.

[0015] According to the disclosure, the target braking variable can be determined from the braking request and / or the braking pressure. The target braking variable can define a required braking variable, i.e., a required braking force and / or deceleration. The method enables the control signal to adjust the braking pressure in the event of a difference between the braking variable and the target braking variable in order to adjust, in particular, increase or decrease, the braking variable. Thus, the braking variable can be adjusted to the target braking variable through the control signal and thus through the adjustment of the braking pressure. This makes it possible to restore a required braking variable if, for example, a braking force as a braking variable deviates from its specification.

[0016] Optionally, the control signal is output such that the brake pressure is increased or decreased depending on the brake force difference. In other words, a control signal is output to increase the brake pressure depending on the brake force difference. This can ensure that a required brake force can be restored if, for example, a braking force deviates from its specification, e.g. due to damp brake pads, rust on the brake discs / drums and / or a lack of thermal activation of the friction material. This can counteract under-braking of the vehicle. Alternatively, a control signal is output to reduce the brake pressure depending on the brake force difference. This can be particularly relevant for particularly powerful braking systems if the braking force is too strong and needs to be reduced. This can counteract overbraking of the vehicle.

[0017] Optionally, the control signal is output in such a way that the brake pressure is increased if the brake force is less than the target brake force. It has been recognized that an increase in brake pressure typically leads to an increase in the brake force. This allows the brake force to be adjusted to the target brake force. If the brake force is equal to or greater than the target brake force, the control signal can be dispensed with.

[0018] Optionally, the control signal can be output in such a way that the brake pressure is adjusted when the brake force difference exceeds a threshold. It has been recognized that a small brake force difference, i.e., a brake force difference below the threshold, can be compensated for by designing the braking system and its control reserve and / or can be tolerated by setting a minimum brake force difference requirement. Thus, the control signal can be dispensed with if the brake force difference is only small.

[0019] Optionally, the brake pressure is increased to such an extent that at least the target brake value is regulated at the given brake pressure. It was recognized that there is typically a functional relationship between brake pressure and brake value. This functional relationship can be used to regulate the target brake value as the brake value at the given brake pressure.

[0020] Optionally, the brake pressure is adjusted in such a way that a standardized standard brake variable and / or a brake variable within a predetermined brake variable range is regulated at the brake pressure. It was recognized that for a defined brake pressure there is typically a standardized, i.e. a fixed, standard brake variable, optionally with a brake variable range that can be regarded as a tolerance range. This can be used to regulate the standard brake variable as the brake variable and / or a brake variable within the brake variable range at the given brake pressure. If the brake variable deviates relatively significantly from its specification, the increase in braking force can be expanded by not only regulating a specified target brake variable, but by increasing it such that the brake variable is at the maximum, upper end of the brake variable range. This can further increase the thermal input into the brake, which is required for its conditioning.

[0021] Optionally, the method can record an axle load, and the braking variable can be a deceleration determined taking the axle load into account. The deceleration can be a ratio or quotient of a braking force and the axle load. Thus, the braking variable can be a valuable measure of the achievable deceleration through the function of the braking system.

[0022] Optionally, the target braking force is determined based on a sectionally linear relationship between the target braking force and the brake pressure. It was recognized that the braking force typically has a sectionally linear relationship with the brake pressure. For example, the braking force can be constant below a threshold brake pressure and increase with the brake pressure above the threshold. Accordingly, it was recognized that a sectionally linear relationship between the brake pressure and the target braking force is also required and / or expected. This relationship can be used to effectively and unambiguously determine the target braking force when a brake pressure is requested.

[0023] According to one aspect of the disclosure, a computer program and / or computer-readable medium comprising instructions is provided which, when the program or instructions are executed by a control unit, cause the control unit to perform the method described above and / or the steps of the method described above. Optionally, the computer program and / or computer-readable medium comprises instructions which, when the program or instructions are executed by a control unit, cause the control unit to implement a feature of the method described above described as optional and / or advantageous in order to achieve an associated technical effect.

[0024] According to one aspect of the disclosure, 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 implement a feature of the method described above that is described as optional and / or advantageous in order to achieve an associated technical effect.

[0025] Optionally, the control unit for determining the braking variable and / or the braking variable difference is configured to transmit the braking pressure, the braking request, the bellows pressure change, and / or the bellows pressure to a data processing device of the vehicle, in particular a commercial vehicle, that is different from the control unit. The data processing device can thereby manage the determination of the braking variable. This ensures that the control unit, for example a brake control unit or a central control unit of a trailer, only needs to process, in particular record and transmit, data relating to the bellows pressure or the bellows pressure change.According to one aspect of the disclosure, a vehicle, in particular a commercial vehicle, is provided with a pneumatic suspension system having a bellows, an electropneumatic braking system having a brake cylinder, a pressure sensor device for detecting a bellows pressure of the bellows and a brake pressure of the brake cylinder, and a control unit as described above connected to the pressure sensor device. The pneumatic suspension system can have multiple bellows, and the electropneumatic braking system can have multiple brake cylinders. The pressure sensor device can detect a bellows pressure of exactly one, several, or all of the bellows and a brake pressure of exactly one, several, or all of the brake cylinders.Optionally, the vehicle is configured to implement a feature of the method described above that is described as optional or advantageous and / or has one of the features described above as optional and / or advantageous in order to achieve an associated technical effect.

[0026] Optionally, the vehicle, in particular a commercial vehicle, is a trailer of a multi-unit vehicle. This means that the braking force is determined in the trailer, in particular a semi-trailer. However, the method described above is also applicable in principle to towing vehicles or vehicles whose axles have chassis designs comparable to those of trailers and in which the braking torque is supported via the air spring bellows. By applying the method in the trailer, a trailer coordination can be achieved, i.e., a respective braking of the towing vehicle and trailer with as similar braking as possible. This can reduce and / or avoid pushing and / or pulling forces between the towing vehicle and the trailer.

[0027] Further features of the disclosure as well as its technical effects emerge from the figures and the description of the preferred embodiments shown in the figures.

[0028] Fig. 1 shows a schematic representation of a vehicle, in particular a commercial vehicle, according to one aspect of the disclosure; Fig. 2 shows a schematic representation of a detail of a vehicle, in particular a commercial vehicle, according to one aspect of the disclosure;

[0029] Fig. 3 is a schematic representation of a trailer as a vehicle, in particular a commercial vehicle, according to one aspect of the disclosure;

[0030] Fig. 4 is a schematic representation of a trailer as a vehicle, in particular a commercial vehicle, according to one aspect of the disclosure;

[0031] Fig. 5 is a schematic representation of a flowchart of a method according to one aspect of the disclosure;

[0032] Fig. 6 shows a section-wise linear relationship for performing a method according to one aspect of the disclosure; and

[0033] Fig. 7 is a schematic representation of a computer-readable medium according to one aspect of the disclosure.

[0034] Fig. 1 shows a schematic representation of a vehicle 200a, in particular commercial vehicle 200b, according to one aspect of the disclosure.

[0035] 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. The vehicle 200a, 200b is a multi-unit vehicle 201 or a vehicle combination and, in the example shown, comprises a towing vehicle 200d and a trailer coupled to the towing vehicle 200d, or a trailer vehicle 200c. In another embodiment, the vehicle 200a, 200b can also comprise multiple trailer vehicles 200c (not shown) or be formed by a trailer vehicle 200c.

[0036] Such a vehicle 200a, 200b has a plurality of n schematically indexed axles 205. The trailer vehicle 200c can have one (not shown) or more of the axles 205. On each of the axles 205, the vehicle 200a, 200b has wheels 206 assigned to the respective axle 205 (see Fig. 2). One or more of the wheels 206 contact a surface (not shown) with a respective wheel contact patch. A braking force FB (see Figs. 2 to 4) can act as a force acting on each wheel contact patch in the vehicle's longitudinal direction against the driving speed when the vehicle 200a, 200b is braking or decelerating. The braking force FB is a braking quantity B. Likewise, the deceleration AB is a braking quantity B that characterizes the deceleration of the vehicle 200a, 200b. The deceleration AB is defined, for example, as the ratio of the braking force FB to the axle load FA.

[0037] Details of the vehicle 200a, 200b are described with reference to Figs. 2 to 4.

[0038] Fig. 2 shows a schematic representation of a detail of a vehicle 200a, 200b according to one aspect of the disclosure. Fig. 2 shows a

[0039] Axle design. An axle design like this, or one that is essentially similar, is typical for a 200c trailer.

[0040] The vehicle 200a, 200b accordingly has a vehicle frame 210. The vehicle frame 210 is a sheet metal and / or tubular construction, has a load-bearing function, and chassis components are connected to the vehicle frame 210. In particular, the vehicle 200a, 200b has a pneumatic suspension system 260 that has components connected to the vehicle frame 210.

[0041] The pneumatic suspension system 260 comprises in particular a bellows 265 associated with a wheel 206 and / or an axle 205, respectively.

[0042] Air spring bellows. The vehicle 200a, 200b includes a device for providing compressed air for filling the bellows 265 (see Fig. 4). Filling the bellows 265 and / or venting the bellows 265 is possible via valves 297 (see Fig. 4) of the vehicle 200a, 200b.

[0043] The vehicle 200a, 200b comprises an axle tube 207 forming the axle 205. The axle tube 207 is fixedly connected at each side to an axle guide 220 of the vehicle 200a, 200b. The axle guide 220 is rotatably connected to the vehicle frame 210 on one side of the axle guide 220 by a bearing 230 comprising a bolt. On the other side of the axle guide 220, facing away from the bearing 230, there is a bellows 265, with which the vehicle 200a, 200b can be sprung and damped, and the axle 205 can optionally be adjusted in height. For this purpose, the axle guide 220 is connected to the axle tube 207. A distance 11 between the bearing 230 and the axle 205 or the axle tube 207 defines the length of a lever supported on the bearing 230 and acting on the axle 205. The distance 11 between the bearing 230 and the axle 205 can be measured and is a vehicle-specific or vehicle-type-specific constant.

[0044] The vehicle 200a, 200b includes a pressure sensor 270. The pressure sensor 270 is configured to measure a bellows pressure pB. The pressure sensor 270 can be configured to measure bellows pressures pB of multiple bellows 265 (see Fig. 4). The bellows pressure pB is the pressure prevailing in the interior of the bellows 265. The bellows 265 has an effective area Aeff, which, together with the bellows pressure pB, defines a force transmitted by the bellows 265.

[0045] The bearing 230 is arranged at a height h. The height h is defined as the vertical distance between the bearing 230 and the ground and / or the wheel contact patch. The height h can be measured and / or estimated from a radius of the wheel 206. The height h is essentially a vehicle-specific or vehicle-type-specific constant.

[0046] The axle guide 220 has a length I0 of the axle guide 220. The length I0 of the axle guide 220 is defined as the distance between the bearing 230 and the bellows 265 along the axle guide 220. The length I0 of the axle guide 220 thus defines the length of a lever arm supported on the bearing 230 and acting on the bellows 265. The length I0 of the axle guide 220 can be measured and is a vehicle-specific or vehicle-type-specific constant.

[0047] The vehicle 200a, 200b has a braking system 290 (see Fig. 4), not shown in Fig. 2, for braking the wheel 206. The braking system 290 is configured to apply a braking torque to the wheel 206 in order to decelerate the rotational movement of the wheel 206 by a braking force FB acting on the wheel contact patch. Due to the construction shown in Fig. 2, a braking torque acting on the wheel 206 and thus the braking force FB leads to a counterforce on the bellows 265 or to a braking-induced force FBB on the bellows 265. The braking force FB thus leads to a bellows pressure change pD in the bellows 265. The bellows pressure pB and thus the bellows pressure change pD as well as a braking pressure BP, which is applied to the braking system 290, can be measured by the pressure sensor 270 and can be transmitted to a control unit 250 of the vehicle 200a, 200b (see Figures 3 and 4).

[0048] Forces FBA, FBS, FBB act on the bellows 265, which include the following components: a static force FBS on the bellows 265, i.e. a force resulting from a static contribution of the axle load FA; a force FBB from a support of the braking torque, and a force FBA due to an axle load shift S, i.e. a dynamic axle load shift during deceleration or a dynamic contribution of the axle load FA.

[0049] The forces FBA, FBS, FBB and the bellows pressure pB are in the following relationship: FBA+FBS+FBB = pB ■ 2 ■ Aeff. In other words, the sum of the force FBA on the bellows 265 due to the axle load shift S plus the static force FBS on the bellows 265 plus the force FBB on the bellows 265 is equal to twice the product of the bellows pressure pB and the effective area Aeff. The factor two results from the number of bellows 265 per axle 205, is a vehicle-specific or vehicle-type-specific constant and can be a different integer in other embodiments.

[0050] The following explains how the individual components of the forces FBA, FBS, FBB acting on the bellows 265 can be calculated.

[0051] The effective area Aeff of the bellows 265 can be measured or determined from data from a load-dependent braking force calculation, or taken from the data sheets of the bellows or axle manufacturers, and is a vehicle-specific or vehicle-type-specific constant. The corresponding data from the load-dependent braking force calculation are typically stored in a control unit 250, in particular a brake control unit of a trailer vehicle. A relationship between a mass of the vehicle 200a, 200b and the bellows pressure pB is typically stored in the control unit 250.The effective area Aeff is then given as (mb - mu) ■ g ■ 11 / (2 ■ (pb - pu) ■ I0), where mb is the mass of the loaded vehicle 200a, 200b, mu is the mass of the unloaded vehicle 200a, 200b, pb is the bellows pressure pB of the loaded vehicle 200a, 200b, pu is the bellows pressure pB of the unloaded vehicle 200a, 200b, 10 is the length of the axle guide 220, 11 is the distance between the bearing 230 and the axle 205 and g is the location factor.

[0052] The force FBS from the static axle load on the bellows 265 is equal to the product of the static component of the axle load FA, static and the distance 11 between the bearing 230 and the axle 205 divided by the length IO of the axle guide 220: FBS = FA, static ■ 11 / 10.

[0053] By observing and storing the bellows pressure pB at the start of braking, a suitable reference pressure pRef can be created for the bellows pressure change pD, so that only the bellows pressure change pD needs to be evaluated during the braking process. The bellows pressure change pD describes the increase in the bellows pressure pB during braking compared to the bellows pressure pB before braking. The maximum bellows pressure pB during braking can be used to calculate the bellows pressure change pD, which can be used to calculate the bellows pressure change pD using the reference pressure pRef.

[0054] The formation of a force or moment sum results in the following equation for the relationship between braking force FB and supporting force or force FBB on bellows 265: FB = FBB ■ 10 / h, i.e. braking force FB is equal to force FBB on bellows 265 multiplied by the length 10 of an axle guide 220 divided by the height h of bearing 230.

[0055] The calculation rule for the braking force FB, neglecting the axle load shift (see Fig. 3), is then: FB = pD ■ 2 ■ Aeff ■ 10 / h, i.e. the braking force FB is equal to twice the product of the effective area Aeff and the length 10 of the axle guide 220 divided by the height h of the bearing 230. The term 2 ■ Aeff ■ 10 / h is a vehicle-specific or vehicle-type-specific constant. A vehicle-specific or vehicle-type-specific constant can, for example, be stored in the memory of the control unit 250. Especially in the case of a semi-trailer, which typically has several axles 205 combined to form an axle assembly, the bellows 265 of these axles 205 are connected to one another entirely or at least side by side. Thus, the braking force FB of the vehicle 200a, 200b and / or the axle assembly can be determined.

[0056] Fig. 3 shows a schematic representation of a trailer 200c as a vehicle 200a, in particular a commercial vehicle 200b, according to one aspect of the disclosure. One axle 205 or multiple axles 205 and the pneumatic suspension system 260 of the trailer 200c can be configured as described with reference to Fig. 2. Fig. 3 is described with reference to Figs. 1 and 2.

[0057] In order for the trailer 200c to be coupled to the towing vehicle 200d (see Fig. 1 ), the trailer 200c has a kingpin 280 according to Fig. 3, via which forces can be transmitted between the trailer 200c and the towing vehicle 200d.

[0058] In particular, when the towing vehicle 200b brakes, a pivot braking force FBZ, i.e., a force acting on the kingpin 280 via the towing vehicle 200d to the trailer 200c, or in particular its horizontal component, can be transmitted. The pivot braking force FBZ results from the fact that the towing vehicle 200d brakes the mass of the trailer 200c, which rests on a fifth wheel plate of the towing vehicle 200d. The kingpin 280 is arranged at a pivot height hZ as a vertical distance between the kingpin 280 and the ground and / or the wheel contact patch. The pivot height hZ is a vehicle-specific or vehicle-type-specific constant.

[0059] The trailer 200c has a center of gravity 202. To determine the center of gravity 202, a uniform load on the trailer 200c can be assumed. The driving dynamics of the trailer 200c can be characterized by a vehicle deceleration D during a braking operation. The center of gravity 202 is located at a center of gravity height hM, which can be estimated and / or derived from data from the braking calculation of the vehicle 200a, 200b. Deviations from the assumptions, for example, between the assumed and actual center of gravity height hM, lead to only insignificant deviations in the following considerations. The center of gravity height hM is essentially a vehicle-specific or vehicle-type-specific constant.

[0060] If the influences of the axle load shift S during braking are taken into account, the calculation of the braking variable B or the braking force FB and / or the deceleration AB can be improved. For this purpose, assumptions are made, e.g., for the center of gravity height hM and the kingpin force FBZ transmitted by the kingpin 280. The dynamic axle load shift S during braking leads to a reduction in load on the rear axle assembly of the semi-trailer and thus to a force FBA on the bellows 265 due to the axle load shift S.This force FBA on the bellows 265 due to the axle load shift S can be determined taking into account the deceleration D and the center of gravity height hM of the trailer 200c as follows: FBA = (-m ■ D ■ hM + FBZ ■ hZ ) ■ 11 / (n ■ leff ■ I0), so the force FBA on the bellows 265 due to the axle load shift S is equal to the quotient of the distance 11 between the bearing 230 and the axle 205 and the product of the number n of axles 205, the effective wheelbase leff and the length I0 of the axle guide 220 multiplied by the sum of the product of the mass m of the vehicle 200, 200b, the deceleration D and the center of gravity height hM and the product of the journal braking force FBK and the journal height hZ. The effective wheelbase leff is a measure of the horizontal distance between the kingpin 280 and the axles 205 and defines a length of a lever acting on the kingpin 280 and supported by the axles 205.If, for example, several axles 205 are equally loaded, the effective wheelbase leff is defined relative to the effective contact point. For example, with three equally loaded axles 205, the effective contact point is located on a second, middle axle 205; with two equally loaded axles 205, the effective contact point is located exactly between the two axles 205. The deceleration D of the vehicle 200a, 200b can be measured using an acceleration sensor and / or wheel speed sensors. The other geometric data result from the design of the vehicle 200a, 200b and are vehicle-specific or vehicle-type-specific constants.From the above equation for the axle load shift it is clear that the influences of the axle load shift are small due to the long effective wheelbase leff of the semi-trailer or trailer 200c in relation to the centre of gravity height hM and the pivot height hZ.

[0061] The vehicle 200a, 200b has the control unit 250. The control unit 250 is, for example, a central control unit or a brake control unit. The control unit 250 is connectable or connected to the pressure sensor 170 (see Figs. 2 and 4) to detect the bellows pressure pB.

[0062] Control unit 250 is configured to detect a braking request BA. The braking request BA can be defined, for example, by a driver of the towing vehicle 200d and / or by an automated driving function. The braking request BA can include and / or define the brake pressure BP.

[0063] The control unit 250 is configured to determine a target braking variable BS based on the braking request BA and / or the braking pressure BP. The target braking variable BS is determined based on a partially linear relationship 300 between the target braking variable BS and the braking pressure BP (see Fig. 6). The control unit 250 is configured to determine a braking variable difference BD (see Fig. 6) between the braking variable B and the target braking variable BS and, based on this difference, to output a control signal 251 for adjusting, i.e., increasing and / or decreasing, the braking pressure BP.

[0064] The vehicle 200a, 200b has a data processing device 255. The data processing device 255 is configured for wireless communication with a vehicle-external server (not shown). The data processing device 255 is communicatively connected to the control unit 250. The control unit 250 can be configured to determine 120 the braking variable B and / or to determine 130 a braking variable difference BD by transmitting the braking pressure BP, a braking request BA, the bellows pressure change pD, and / or the bellows pressure pB to the data processing device 255, which is different from the control unit 250. The data processing device 255 can determine the control signal 251 according to the method 100 of FIG. 5 and / or transmit the data received from the control unit 250 to the vehicle-external server, which determines the braking variable B and / or the target braking variable BS. The data processing device 255 is, for example, a telematics device.

[0065] Fig. 4 shows a schematic representation of a trailer 200c as a vehicle 200a, in particular a commercial vehicle 200b, according to one aspect of the disclosure. The vehicle 200a, 200b according to Fig. 4 is the vehicle 200a, 200b described with reference to Fig. 3. Fig. 4 is described with reference to Figs. 1 to 3.

[0066] The vehicle 200a, 200b has axles 205 with wheels 206 (not indicated in Fig. 4). Each of the wheels 206 is assigned a brake cylinder 295 as part of the braking system 290. The brake cylinder 295 of a respective wheel 206 can be subjected to the brake pressure BP in order to brake the wheel 206 or to exert a braking torque on the wheel 206. Each of the wheels 206 is assigned a bellows 265 as part of the suspension system 260. The bellows pressure pB is present in the bellows 265 of a respective wheel 206.

[0067] The brake pressure BP and the bellows pressure pB can be measured by the pressure sensor 270. The pressure sensor 270 is a central pressure sensor 270 for measuring the brake pressures BP of a plurality of brake cylinders 295 and for measuring the bellows pressures pB of a plurality of bellows 265. In another embodiment, the vehicle 200a, 200b can have a plurality of pressure sensors 270 for measuring the pressure of one or more brake cylinders 295 and / or bellows 265, respectively.

[0068] The vehicle 200a, 200b has two compressed air lines 299 for conducting air pressure from a towing vehicle 200d (see Fig. 1) to the trailer 200c. For storing and / or adjusting pressures, the vehicle 200a, 200b has two compressed air reservoirs 296 and a plurality of valves 297.

[0069] The vehicle 200a, 200b has a communication link 298. The communication link 298 is configured for data transmission between the towing vehicle 200d and the trailer 200c. The communication link 298 can, for example, be configured according to the ISO 7638-1:2018-05 standard "Road vehicles - Connectors for the electrical connection of towing vehicles and trailers - Part 2: Connectors for braking systems and equipment of vehicles with a nominal voltage of 24 V" of May 2018.

[0070] Fig. 5 shows a schematic representation of a flowchart of a method 100 according to one aspect of the disclosure. The method 100 according to Fig. 5 is a method 100 for operating an electropneumatic braking system 290 for a vehicle 200a, 200b. Such a vehicle 200a, 200b is described with reference to Figs. 1 to 4. Fig. 5 is described with reference to Figs. 1 to 4.

[0071] The method 100 according to Fig. 5 comprises: detecting 110 the bellows pressure pB during a braking operation initiated by a braking request BA and achieved with a braking pressure BP.

[0072] The method 100 comprises: detecting 115 an axle load FA.

[0073] The method 100 comprises: determining 120 a braking variable B based on the bellows pressure pB and / or a bellows pressure change pD derivable from the bellows pressure pB. The braking variable B is a deceleration AB determined taking into account the axle load FA.

[0074] The method 100 comprises: determining 130 a brake variable difference BD between the brake variable B and a target brake variable BS that can be determined based on the brake request BA and / or the brake pressure BP. The target brake variable BS is determined based on a sectionally linear relationship 300 between the target brake variable BS and the brake pressure BP. The method 100 comprises: outputting 140 a control signal 251 for adjusting the brake pressure BP as a function of the brake variable difference BD. The control signal 251 is output such that the brake pressure BP is increased or decreased as a function of the brake variable difference BD. The control signal 251 is output such that the brake pressure BP is increased if the brake variable B is less than the target brake variable BS. Alternatively, the control signal 251 is output such that the brake pressure BP is reduced when the brake quantity B is greater than the target brake quantity BS.The control signal 251 is output such that the brake pressure BP is adjusted when the brake variable difference BD exceeds a threshold value. The brake pressure BP is increased such that at least the target brake variable BS is regulated at the brake pressure BP. The brake pressure BP is adjusted such that a standardized standard brake variable BN and / or a brake variable B within a predetermined brake variable range BB is regulated at the brake pressure BP.

[0075] Fig. 6 shows a sectionally linear relationship 300 for implementing a method 100 according to one aspect of the disclosure. Such a sectionally linear relationship 300 can be used to determine a target braking variable BS based on a braking request BA and / or a braking pressure BP. Fig. 6 is described with reference to Figs. 1 to 5.

[0076] The section-wise linear relationship 300 according to Fig. 6 shows a functional relationship between the braking AB as braking variable B and the braking pressure BP.

[0077] As shown by the dotted line, a braking quantity B can be established in response to a braking pressure BP during braking. The braking quantity B can be determined as described with reference to Figs. 1 to 5.

[0078] In Fig. 6, a sectionally linear relationship 300 with a solid line shows a target braking variable BS as a function of the brake pressure BP. The sectionally linear relationship 300 between the target braking variable BS and the brake pressure BP can, for example, be stored in the control unit 250 in order to determine the target braking variable BS based on the sectionally linear relationship 300 between the target braking variable BS and the brake pressure BP. At a specific brake pressure BP, the target braking variable BS is substantially greater than the braking variable B. For a specific brake pressure BP, a braking variable difference BD can thus be determined between the braking variable B and the target braking variable BS determined based on the braking request BA and / or the brake pressure BP.

[0079] In order for the target brake variable BS to be regulated and / or controlled, the control signal 251 is output 140 to adjust or, according to the example shown, to increase the brake pressure BP depending on the brake variable difference BD. In this case, the brake pressure BP is increased by a brake pressure difference DBP in order to achieve the target brake variable BS for a given performance of the brake system 290. The brake pressure BP is increased by the brake pressure difference DBP in such a way that at least the target brake variable BS is regulated at the brake pressure BP. In this case, the brake pressure BP is increased in such a way that a standardized standard brake variable BN is exceeded and a brake variable B is within a predetermined

[0080] Braking magnitude range BB at which the brake pressure BP is regulated. This is applicable for fully loaded vehicles 200a, 200b, since a maximum reference pressure may not exceed 7 bar, while a pressure level of 8.5 bar prevails in the trailer 200c. Thus, a reserve of approximately 20% is still available. Additionally and alternatively, the braking operations are typically only light partial braking operations in the pressure range around 1 bar. Such braking operations can be easily corrected using method 100.

[0081] The section-by-section linear relationship 300 has a first section 301, a second section 302, and a third section 303. In the first section 301, with a low brake pressure BP, no and / or a low and constant brake variable B is required, since a response pressure must first be exceeded as a threshold value. In the second section 302, the brake variable B, for example the standard brake variable BN, increases with the brake pressure BP according to a first gradient, and in the third section 303, the brake variable B, for example the standard brake variable BN, increases with the brake pressure BP according to a second gradient different from the first gradient.

[0082] The section-by-section linear relationship 300 shown in Fig. 6 is merely exemplary. Additional linear sections may be added, for example, in a drawbar trailer.

[0083] Fig. 7 shows a schematic representation of a computer-readable medium 400 according to one aspect of the disclosure. The computer-readable medium 400 includes instructions (not shown) that, when executed by a control device 250, cause the control device 250 to perform the method 100 and / or the steps of the method 100 according to Fig. 5.

[0084] The instructions can be present as program code in any code or language, in particular in code suitable for motor vehicle control systems. The computer-readable medium 400 can be or include any digital data storage device, such as a USB stick, a hard drive, a CD-ROM, an SD card, or an SSD card. The computer program does not necessarily have to be stored on such a computer-readable storage medium, but can also be accessible via the Internet or otherwise.

[0085] Reference symbol (part of the description)

[0086] 100 procedures

[0087] 110 Detecting a bellows pressure

[0088] 115 Recording an axle load

[0089] 120 Investigate

[0090] 130 Determine

[0091] 140 Issues

[0092] 200a vehicle

[0093] 200b commercial vehicle

[0094] 200c trailer, towed vehicle

[0095] 200d towing vehicle

[0096] 201 multi-unit vehicle

[0097] 202 Focus

[0098] 205 Axis

[0099] 206 Wheel

[0100] 207 axle tube

[0101] 210 vehicle frame

[0102] 220 axle guides

[0103] 230 Storage

[0104] 250 control unit

[0105] 251 Control signal

[0106] 255 Data processing device

[0107] 260 pneumatic suspension system

[0108] 265 bellows

[0109] 270 pressure sensor

[0110] 280 kingpins

[0111] 290 braking system

[0112] 295 brake cylinders

[0113] 296 compressed air storage

[0114] 297 Valve

[0115] 298 Communication connection

[0116] 299 Compressed air line 300 section-wise linear relationship

[0117] 301 first section

[0118] 302 second section

[0119] 303 third section

[0120] 400 computer-readable medium

[0121] AB braking

[0122] Aeff effective area

[0123] B Brake size

[0124] BA brake request

[0125] BB brake size range

[0126] BD brake size difference

[0127] BN standard brake size

[0128] BP brake pressure

[0129] BS target brake size

[0130] D Vehicle deceleration

[0131] DBP brake pressure difference

[0132] FA axle load

[0133] FB braking force

[0134] FBA force on bellows, axle load shift

[0135] FBB force on bellows caused by braking

[0136] FBS static force on bellows

[0137] FBZ pivot braking force h height of a bearing hM center of gravity height hZ pivot height leff effective wheelbase

[0138] 10 Length of an axle guide

[0139] 11 Distance between bearing and axis n Number of axes pB Bellows pressure pD Bellows pressure change pRef Reference pressure

[0140] S Axle load shift

Claims

Patent claims 1. A method (100) for operating an electropneumatic braking system (290) for a vehicle (200a), in particular a commercial vehicle (200b), wherein the vehicle (200a) has a pneumatic suspension system (260) with a bellows (265) and a pressure sensor (270) for detecting a bellows pressure (pB) of the bellows (265), the method (100) comprising: Detecting (110) the bellows pressure (pB) during braking initiated by a braking request (BA) and achieved with a braking pressure (BP); Determining (120) a braking variable (B) based on the bellows pressure (pB) and / or a bellows pressure change (pD) derivable from the bellows pressure (pB); Determining (130) a brake variable difference (BD) between the brake variable (B) and a target brake variable (BS) that can be determined based on the brake request (BA) and / or the brake pressure (BP); and Outputting (140) a control signal (251) for adjusting the brake pressure (BP) as a function of the brake size difference (BD).

2. Method (100) according to claim 1, wherein the control signal (251) is output such that the brake pressure (BP) is increased or decreased depending on the brake size difference (BD).

3. Method (100) according to claim 1 or 2, wherein the control signal (251) is output such that the brake pressure (BP) is increased when the brake quantity (B) is smaller than the target brake quantity (BS).

4. Method (100) according to one of the preceding claims, wherein the control signal (251) is output such that the brake pressure (BP) is adjusted when the brake variable difference (BD) exceeds a threshold value.

5. Method (100) according to one of the preceding claims, wherein the brake pressure (BP) is increased such that at least the target brake variable (BS) is regulated at the brake pressure (BP).

6. Method (100) according to one of the preceding claims, wherein the brake pressure (BP) is adjusted such that a standardized standard brake variable (BN) and / or a brake variable (B) is regulated within a predetermined brake variable range (BB) at the brake pressure (BP).

7. The method (100) according to any one of the preceding claims, wherein the method (100) comprises: detecting (115) an axle load (FA); and the braking variable (B) is a deceleration (AB) determined taking into account the axle load (FA).

8. Method (100) according to one of the preceding claims, wherein the target braking variable (BS) is determined based on a sectionally linear relationship (300) between the target braking variable (BS) and the braking pressure (BP).

9. Computer program and / or computer-readable medium (400), comprising instructions which, when the program or instructions are executed by a control device (250), cause the control device (250) to carry out the method (100) and / or the steps of the method (100) according to one of claims 1 to 8.

10. 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 8.

11. Control unit (250) according to claim 10, wherein the control unit (250) is configured to determine (130) the braking variable (B) for transmitting (135) the bellows pressure change (pD) and / or the bellows pressure (pB) to a data processing device (255) of the vehicle (200a), in particular the commercial vehicle (200b), which is different from the control unit (250).

12. Vehicle (200a), in particular a commercial vehicle (200b), with a pneumatic suspension system (260) with a bellows (265), with an electropneumatic braking system (290) with a brake cylinder (295), a pressure sensor device (270) for detecting a bellows pressure (pB) of the bellows (265) and a brake pressure (BP) of the brake cylinder (295) and with a control unit (250) according to claim 10 or 11 connected to the pressure sensor device (270).

13. Vehicle (200a), in particular commercial vehicle (200b), according to claim 12, wherein the vehicle (200a) is or comprises a trailer vehicle (200c) of a multi-unit vehicle (201).

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