Method for determining a braking variable for a vehicle

Abstract

The invention relates to a method (100) for determining a braking variable (B) for a vehicle (200a), in particular a utility vehicle (200b), wherein the vehicle (200a), in particular utility vehicle (200b), comprises a pneumatic suspension system (260) having a bellows (265) and comprises a pressure sensor (270) for sensing a bellows pressure (pB) of the bellows (265), the method (100) comprising: sensing (110) the bellows pressure (pB); ascertaining (120) a bellows pressure change (pD) on the basis of the bellows pressure (pB); and determining (130) the braking variable (B) on the basis of the bellows pressure change (pD).

Description

[0001] METHOD FOR DETERMINING A BRAKING SIZE FOR A VEHICLE

[0002] The disclosure relates to a method for determining a braking variable for a vehicle, in particular a commercial vehicle, wherein the vehicle, in particular a commercial 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 and a pressure sensor for detecting a bellows pressure of the bellows.

[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 each have a wheel contact patch in contact with the ground. A braking force can be the force acting on each wheel contact patch in the longitudinal direction of the vehicle relative to 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 may be desirable in order to obtain information about the condition or possible defects of a brake generating the braking force, a braked wheel and / or a component of the braked wheel or the brake. In other words, such an onboard measurement may be of interest for monitoring the current braking performance of a vehicle, for example, to carry out an automated driving function, to take prescribed maintenance intervals into account and / or to plan maintenance and / or inspections. The condition can be determined, for example, as part of legally and / or operationally defined checks. However, the condition and possible defects are difficult to detect during ongoing operation.Some processes, such as a change in the brake pad, can occur gradually, which can make it difficult for the driver to perceive. Furthermore, a decrease in the braking effect of one brake can be compensated for by another brake, especially in a multi-unit vehicle.

[0005] It is known from the state of the art to measure the braking force via strain gauges or force sensors, or indirectly via height sensors.

[0006] EP 3 753 794 A1 discloses a method for monitoring the braking performance of a vehicle, in particular a trailer of a commercial vehicle. The method comprises: collecting sensor data from various sensors, the sensor data being associated with braking events; determining at least one braking performance value using the sensor data based on at least one of the following analyses: (i) a statistical analysis based on multiple regression; (ii) a braking force loss analysis based on a comparison of wheel speed values ​​of different wheels; (iii) an air suspension pressure analysis based on a comparison of a change in air suspension pressure during braking. The method further comprises detecting a malfunction of at least one brake of at least one wheel based on the determined at least one braking performance value.The suspension pressure analysis may include: determining the air suspension pressure at one or more wheels based on sensor signals from one or more height sensors for controlling or measuring one or more bellows.

[0007] WO 2016 / 030699 A1 discloses a method for monitoring the braking performance of a vehicle. The method comprises, for at least some of the braking events: determining a braking request; determining a vehicle deceleration; defining a first data set of braking events, each braking event in the data set comprising a particular braking request and a particular vehicle deceleration; applying a statistical trend analysis method to the data set to generate a vehicle deceleration and braking request trend; providing a vehicle deceleration and braking request reference; and comparing at least one trend value with at least one reference value. From this comparison, it is possible to determine whether the braking system is operating within an acceptable limit. An apparatus for implementing the method is also disclosed.The braking events can be categorized into a number of categories based on the vehicle load.

[0008] However, additional sensors result in increased effort, increased weight and increased costs.

[0009] It is also possible to determine the braking force by evaluating the deceleration of a multi-unit vehicle. However, such an evaluation can be subject to errors. Furthermore, such an evaluation cannot differentiate which vehicle in a multi-unit vehicle or combination of vehicles is responsible for excessive or insufficient deceleration relative to a braking request. Continuous braking systems, such as retarders, engine brakes, or even electric drive axles used to recuperate braking energy, can lead to significant deceleration and thus influence the result.

[0010] Direct brake force measurement is also known from the state of the art.

[0011] Patent application DE 10 2022 127 155.2, which had not yet been published on the filing date of the disclosure, describes a method for monitoring the braking effect of a vehicle with chassis, wheels, brakes, and an electronic braking system. A trailer with supporting bellows is disclosed, with a pressure sensor arranged on a supporting bellows, the data from which represents an axle load and is transmitted to the brake control unit. The axle load can be detected to calculate a target braking force. The invention is based on the object of enriching the prior art and enabling an improved determination of a braking variable. In particular, the invention solves the problem of determining the braking variable effectively and reliably, even independently of influences from different vehicle components in a multi-unit vehicle.

[0012] According to one aspect of the invention, a method for determining a braking variable for a vehicle, in particular a commercial vehicle, is provided. The vehicle, in particular a commercial vehicle, comprises a pneumatic suspension system with a bellows and a pressure sensor for detecting a bellows pressure of the bellows. The method comprises: detecting the bellows pressure; determining a bellows pressure change based on the bellows pressure; and determining the braking variable based on the bellows pressure change.

[0013] 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 regulation 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.

[0014] 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 that is particularly vehicle-specific or vehicle type-specific, and / or other contributions can be taken into account to increase accuracy. This enables on-board measurement of the braking force of a vehicle, and in particular 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 avoids 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 can be avoided that, for example, a height measurement has to be carried out and a change in height has to be converted into a change in the volume of the bellows using a complicated relationship in order to determine the braking force.

[0015] Optionally, the bellows pressure change corresponds to a difference between the bellows pressure and a reference bellows pressure at and / or before the braking action. It was recognized that without the braking action, i.e., before a braking operation or braking, the bellows has a bellows pressure that is set to operate the air spring system. The pressure changes due to the braking operation and the braking action. Thus, the bellows pressure at and / or before the braking action can be a suitable reference bellows pressure for determining the bellows pressure change. The bellows pressure change can then be the difference between the detected bellows pressure during the braking operation and the reference bellows pressure.

[0016] Optionally, the braking force can be determined taking into account the length of an axle guide that is rotatably mounted on a vehicle frame and the height of a bearing for the axle guide. It was recognized that the axle guide forms a lever that can transfer the braking force from the wheel to the bellows. The vehicle has the bearing for the rotatable or pivotable bearing of the axle guide. The bearing is arranged at a height above a ground or relative to a wheel contact patch. Based on the length of the axle guide and the height of the bearing, the braking force can be determined as a function of the force acting on the bellows and thus the change in pressure. Alternatively or additionally, the braking force can be determined taking into account the ratio of the length to the height. The height, the length and their ratio or quotient are vehicle-specific or vehicle-type-specific constants.

[0017] Optionally, the braking force can be determined taking into account the effective area of ​​the bellows. It has been recognized that the relationship between the bellows pressure, and thus the change in the bellows pressure, and the force acting on the bellows depends on the effective area of ​​the bellows. The effective area of ​​the air spring bellows can be measured, entered, and / or determined from data from a load-dependent braking force calculation. The corresponding data is typically stored as a relationship between bellows pressure and braking force in a vehicle control unit, for example, a brake control unit of a trailer.

[0018] Optionally, the brake size can be determined taking into account an axle load shift. It has been recognized that an axle load shift can lead to a change in bellows pressure. By taking the axle load shift into account, an additional contribution can be taken into account when determining the brake size, thus increasing the accuracy of the brake size.

[0019] Optionally, the axle load shift is determined taking into account vehicle deceleration, center of gravity height, kingpin braking force acting on a kingpin, kingpin height, number of axles, and / or effective wheelbase. This allows variables relevant to driving dynamics and axle load shift to be considered, effectively increasing the accuracy of the braking value. By considering the kingpin braking force and the kingpin height, the influence of braking on a towing vehicle's axle load shift of a trailer can be taken into account. The number of axles and the effective wheelbase resulting from the wheelbases of potentially multiple axles can simplify the consideration of axle load shift.

[0020] Optionally, the braking amount is determined if a braking operation exceeds a minimum braking duration. This ensures that the braking amount is only determined once the forces acting on the bellows have reached a largely steady state. It was recognized that, even with constant brake pressure, the vehicle oscillates during a braking operation due to its mass. This implies a bellows pressure resulting from the driving dynamics and braking, whereas the bellows pressure after the oscillation is largely determined by the braking. The minimum braking duration can be, for example, 1 s to 3 s, for example 2 s, to enable improved determination of the braking amount. Alternatively or additionally, shorter braking applications can be considered, particularly taking into account the dynamics of the forces and / or moments. For example, brake pressure and bellows pressure gradients and / or higher time derivatives can be evaluated for this purpose.

[0021] Optionally, the braking magnitude can be determined over multiple braking events, and the braking magnitudes associated with the braking events are statistically evaluated. For example, the braking magnitudes of the multiple braking events can be averaged to enable a more precise determination of the braking magnitude.

[0022] Optionally, the braking variable includes a braking force and / or deceleration. The braking force can be the force acting on a wheel contact patch in the longitudinal direction of the vehicle relative to the vehicle speed during braking or deceleration. The deceleration can be the ratio or quotient of the braking force and a load, particularly an axle load. This allows the braking variable to be determined depending on the application.

[0023] Optionally, the vehicle, in particular a commercial vehicle, has a braking system, a control unit for controlling the braking system and a data processing device, wherein the method for determining the braking variable comprises: transmitting the bellows pressure change and / or the bellows pressure from the control unit to the data processing device. In this case, a vehicle-specific and / or vehicle-type-specific constant can be stored in the data processing device and / or the data processing device can be set up for wireless communication and retrieve a vehicle-specific and / or vehicle-type-specific constant from a server external to the vehicle. The braking variable can thus be determined by the data processing device. Alternatively, it is possible for the data processing device to transmit the bellows pressure change and / or the bellows pressure as well as optionally vehicle-specific parameters, such asThe length of the trailing arms and reference forces are transmitted to the vehicle-external server to determine the braking force. In any case, the control unit can be a brake control unit or central control unit. This makes it possible to determine the braking force without great effort even for existing vehicles, thus providing a retrofit option. In the simplest case, such a retrofit can be an update of the data processing device. The data processing device can be a telematics device.

[0024] According to one aspect of the disclosure, a computer program and / or computer-readable medium comprising instructions that, when executed by a computer, cause the program or instructions to perform the method described above and / or the steps of the method described above is provided. Optionally, the computer program and / or computer-readable medium comprises instructions that, when executed by a computer, cause the program or instructions to implement a feature of the method described above described as optional or advantageous in order to achieve an associated technical effect.

[0025] 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, described as optional or advantageous, in order to achieve an associated technical effect.

[0026] Optionally, the control unit for determining the braking variable is configured to transmit 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 then 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.

[0027] Optionally, the data processing device is configured for wireless data transmission. This allows the bellows pressure change and / or the bellows pressure to be transmitted from the data processing device to a server external to the vehicle, whereby the braking variable can be determined by the server external to the vehicle. This allows the control unit and the data processing device to be designed to conserve resources. Furthermore, it enables the possibility of retrofitting an existing vehicle, particularly a commercial vehicle, since only the bellows pressure change and / or the bellows pressure need to be recorded or transmitted to determine the braking variable.

[0028] According to one aspect of the disclosure, a vehicle, in particular a commercial vehicle, is provided with a pneumatic suspension system having a bellows and a pressure sensor for detecting a bellows pressure of the bellows and with a control unit as described above connected to the pressure sensor.

[0029] Optionally, the vehicle, especially a commercial vehicle, is a trailer of a multi-unit vehicle. This means that the braking force is determined in the trailer, especially 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 where the braking torque is transmitted via the air spring bellows.

[0030] Further features of the invention and its technical effects emerge from the figures and the description of the preferred embodiments shown in the figures.

[0031] Fig. 1 is a schematic representation of a vehicle, in particular a commercial vehicle, according to one aspect of the invention; Fig. 2 is a schematic representation of a detail of a vehicle, in particular a commercial vehicle, according to one aspect of the invention;

[0032] Fig. 3 is a schematic representation of a trailer as a vehicle, in particular a commercial vehicle, according to one aspect of the invention;

[0033] Fig. 4 is a schematic representation of a trailer as a vehicle, in particular a commercial vehicle, according to one aspect of the invention;

[0034] Fig. 5 is a schematic representation of a flow chart of a method according to one aspect of the invention;

[0035] Fig. 6 shows braking forces obtained by a method according to one aspect of the invention as a function of the brake pressure; and

[0036] Fig. 7 shows braking forces obtained by a method according to one aspect of the invention as a function of the brake pressure.

[0037] Fig. 1 shows a schematic representation of a vehicle 200a, in particular commercial vehicle 200b, according to one aspect of the invention.

[0038] 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, also referred to as a vehicle combination, and in the example shown comprises a towing vehicle 200d and a trailer 200c coupled to the towing vehicle 200b, also referred to as a trailer vehicle. In another embodiment, the vehicle 200a, 200b can also comprise multiple trailers 200c (not shown).

[0039] Such a vehicle 200a, 200b has a plurality of n schematically indexed 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 during braking or deceleration of the vehicle 200a, 200b. The braking force FB is a braking variable B. Likewise, a braking AB is a braking variable B that characterizes the deceleration of the vehicle 200a, 200b. The braking AB is defined, for example, as the ratio of braking force FB and axle load FA.

[0040] Details of the vehicle 200a, 200b are described with reference to Figs. 2 to 4.

[0041] Fig. 2 shows a schematic representation of a detail of a vehicle 200a, in particular a commercial vehicle 200b, according to one aspect of the invention. Fig. 2 shows an axle construction. An axle construction of this type, or one with a fundamentally similar function, is typical for trailer vehicles.

[0042] 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 frame.

[0043] The pneumatic suspension system 260 comprises, in particular, a bellows 265 or air spring bellows assigned to a wheel 206 and / or an axle 205. The vehicle 200a, 200b comprises 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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 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 Figs. 3 and 4).

[0049] 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 braking 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.

[0050] The forces FBA, FBS, FBB and the bellows pressure pB are in the following relationship: FBA+FBS+FBB = pB x 2 x 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 braking force FBB on the bellows 265 is equal to twice the product of the bellows pressure pB and the effective area Aeff. The number 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.

[0051] The following explains how the individual components of the forces FBA, FBS, FBB acting on the bellows 265 can be calculated.

[0052] 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) xgx 11 / (2 x (pb-pu) x 10), 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.

[0053] 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 x 11 / 10.

[0054] 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.

[0055] The formation of a force or moment sum results in the following equation for the relationship between braking force FB and supporting force FBB on the bellows 265: FB=FBB x 10 / h, i.e. the braking force FB is equal to the supporting force FBB on the bellows 265 multiplied by the length 10 of an axle guide 220 divided by the height h of the bearing 230.

[0056] The calculation rule for the braking force FB, neglecting the axle load shift (see Fig. 3), is then: FB = pD x 2 x Aeff x 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 x Aeff x 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 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.

[0057] 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 invention. 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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 = (- mx D x hM + FBZ x hZ ) x 11 / (nx leff x 10), 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 10 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 pivot braking force FBK and the pivot 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.For example, if multiple axles 205 are equally loaded, the effective wheelbase leff is defined relative to the effective contact point. For example, if there are three equally loaded axles 205, the effective contact point is located on a second, middle axle 205; if there are two equally loaded axles 205, the effective contact point is located exactly between the two axles 205.

[0062] 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. The above equation for the axle load shift clearly shows that the influences of the axle load shift are small due to the long effective wheelbase leff of the semitrailer or trailer 200c relative to the center of gravity height hM and the pivot height hZ.

[0063] 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.

[0064] The vehicle 200a, 200b has a data processing device 255. The data processing device 255 is configured for wireless communication with a server external to the vehicle (not shown). The data processing device 255 is communicatively connected to the control unit 250. The control unit 250 can be configured to determine 130 the braking force FB or the braking variable B and to transmit 135 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 braking variable B according to the method 100 of Fig. 5 and / or transmit the data received from the control unit 250 to the server external to the vehicle, which determines the braking variable B. 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 invention. 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 invention. The method 100 is a method 100 for determining a braking variable B for a vehicle 200a, commercial vehicle 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 comprises: detecting 110 the bellows pressure pB. Determining 120 a bellows pressure change pD based on the bellows pressure pB. The bellows pressure change pD corresponds to a difference between the bellows pressure pB and a reference bellows pressure pRef at and / or before the effect of the braking variable B.

[0072] The braking variable B is determined 130 based on the bellows pressure change pD. The braking variable B is determined 130 taking into account the length L0 of the axle guide 220 and the height h of the bearing 230 of the axle guide 220, as well as a ratio of the length L0 and the height h. The braking variable B is determined 130 taking into account an effective area Aeff of the bellows 265.

[0073] The determination 130 of the braking variable B takes place taking into account an axle load shift S. The axle load shift S is determined taking into account a vehicle deceleration D, a center of gravity height hM, a pin braking force FBZ acting on a kingpin 280, a pin height hZ of the kingpin 280, a number n of axles 205 and / or an effective wheelbase leff.

[0074] The braking variable B is determined 130 when a braking operation exceeds a minimum braking duration. The braking variable B is determined 130 during multiple braking operations, and the braking variables B assigned to the braking operations are statistically evaluated. The quality of the braking can be weighted in terms of its evaluability depending on the length of the braking operation, the continuity, and / or the level of the brake pressure. Braking operations that are easy to evaluate are given a higher weighting in the evaluation. In other words, the braking forces FB are weighted in the statistical evaluation by multiplying them by weights, with more reliable braking forces FB being given a higher weighting than possibly less reliable braking forces FB. The braking variable B comprises a braking force FB and / or a deceleration AB.

[0075] Optionally, to determine 130 the braking variable B, the bellows pressure change pD and / or the bellows pressure pB is transmitted 135 to a data processing device 255 of the vehicle 200a, 200b that is different from the control unit 250. The mechanical brake has a hysteresis of approximately 10%. This means that if a brake pressure BP is reduced or increased by 10% during a braking operation, the braking force FB remains essentially the same due to friction effects. Accordingly, the value of the braking force FB can be different when the brake pressure BP is increased than when the brake pressure BP is decreased. Since the course of the brake pressure BP is known from whether the braking is increased or decreased during braking, this effect can optionally be taken into account in the evaluation as a difference in the braking force FB that defines the hysteresis.

[0076] Fig. 6 shows braking forces FB obtained by a method 100 according to one aspect of the invention as a function of the braking pressure BP.

[0077] The square symbols show a first series of measurements of the braking force FB as a function of the braking pressure BP as reference values ​​for the trailer 200c according to Fig. 1 to 4 with a raised lifting axle, i.e. a number n of two axles 205 contacting the ground. The reference values ​​show a linear relationship between the braking force FB and the braking pressure BP.

[0078] The circular symbols show a second series of measurements of the braking force FB as a function of the braking pressure BP for the trailer 200c according to Figs. 1 to 4 with a raised lift axle, i.e., a number n of two axles 205 contacting the ground. The braking force FB was determined based on the bellows pressure change pD, as described with reference to Figs. 1 to 5. The series of measurements largely shows agreement and also a relationship between the braking force FB and the braking pressure BP that can be described as linear.

[0079] The triangular symbols show a third series of measurements comparable to the second series, but with one of the four brake cylinders disconnected. The trailer 200c thus brakes only with three wheels 206 and not with four. A reduced braking force FB with a disconnected brake cylinder compared to the second series of measurements is clearly visible. This allows, for example, a brake defect to be diagnosed based on the bellows pressure change pD. Fig. 7 shows braking forces FB obtained by a method according to one aspect of the invention as a function of the brake pressure BP.

[0080] The square symbols show a first series of measurements of the braking force FB as a function of the braking pressure BP as reference values ​​for the trailer 200c according to Fig. 1 to 3 with a raised lifting axle, i.e. a number n of two axles 205 contacting the ground. The reference values ​​show a linear relationship between the braking force FB and the braking pressure BP.

[0081] The circular symbols show a second series of measurements of the braking force FB as a function of the braking pressure BP for the trailer 200c according to Figs. 1 to 4. The braking force FB was determined based on the bellows pressure change pD, as described with reference to Figs. 1 to 5. The series of measurements largely shows agreement and also a relationship between the braking force FB and the braking pressure BP that can be described as linear.

[0082] The triangular symbols show a third series of measurements comparable to the second series of measurements, with the third series of measurements showing the braking force FB of the multi-unit vehicle 201, i.e., the towing vehicle 200d and the trailer 200c. It can be seen that the measurements of the braking force FB are relatively independent of the behavior of the towing vehicle 200d, or rather, the behavior of the towing vehicle 200d is comprehensively taken into account.

[0083] il of the description)

[0084] 100 procedures

[0085] 110 Capture

[0086] 120 Investigate

[0087] 130 Determine

[0088] 135 Transmit 00a Vehicle 00b Commercial vehicle 00c Trailer

[0089] 200d towing vehicle

[0090] 201 multi-unit vehicle

[0091] 202 Focus

[0092] 205 Axis

[0093] 206 Wheel

[0094] 207 axle tube

[0095] 210 vehicle frame

[0096] 220 axle guides

[0097] 230 Storage

[0098] 250 control unit

[0099] 255 Data processing device

[0100] 260 pneumatic suspension system

[0101] 265 bellows

[0102] 270 pressure sensor

[0103] 280 kingpins

[0104] 290 braking system

[0105] 295 brake cylinders

[0106] 296 compressed air storage

[0107] 297 Valve

[0108] 298 Communication connection

[0109] 299 Compressed air line

[0110] AB Deceleration Aeff Effective area

[0111] B Brake size

[0112] BP brake pressure

[0113] D Vehicle deceleration

[0114] FA axle load

[0115] FB braking force

[0116] FBA force on bellows, axle load shift

[0117] FBB braking force on bellows

[0118] FBS static force on bellows

[0119] FBZ pivot braking force h height of a bearing hM center of gravity height hZ pivot height leff effective wheelbase

[0120] 10 Length of an axle guide

[0121] 11 Distance between bearing and axis n Number of axes pB Bellows pressure pD Bellows pressure change pRef Reference pressure

[0122] S Axle load shift

Claims

Patent claims 1. Method (100) for determining a braking variable (B) for a vehicle (200a), in particular a commercial vehicle (200b), wherein the vehicle (200a), in particular a commercial vehicle (200b), 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); Determining (120) a bellows pressure change (pD) based on the bellows pressure (pB); and Determine (130) the brake size (B) based on the bellows pressure change (pD).

2. Method (100) according to claim 1, wherein the bellows pressure change (pD) corresponds to a difference between the bellows pressure (pB) and a reference bellows pressure (pRef) at and / or before an effect of the braking variable (B).

3. Method (100) according to claim 1 or 2, wherein the determination (130) of the braking variable (B) takes place taking into account a length (LO) of an axle guide (220) rotatably mounted on a vehicle frame (210) and a height (h) of a bearing (230) of the axle guide (220) and / or a ratio of the length (LO) and the height (h).

4. Method (100) according to one of the preceding claims, wherein the determination (130) of the braking variable (B) takes place taking into account an effective area (Aeff) of the bellows (265).

5. Method (100) according to one of the preceding claims, wherein the determination (130) of the braking variable (B) takes place taking into account an axle load shift (S).

6. The method (100) according to claim 5, wherein the axle load shift (S) is determined taking into account a vehicle deceleration (D), a center of gravity height (hM), a pin braking force (FBZ) acting on a kingpin (280), a pin height (hZ) of the kingpin (280), a number (n) of axles (205) and / or an effective wheelbase (leff).

7. Method (100) according to one of the preceding claims, wherein the determination (130) of the braking quantity (B) takes place when a braking operation exceeds a minimum braking duration.

8. Method (100) according to one of the preceding claims, wherein the braking variable (B) comprises a braking force (FB) and / or a deceleration (AB).

9. Method (100) according to one of the preceding claims, wherein the determination (130) of the braking quantity (B) takes place during a plurality of braking operations and the braking quantities (B) assigned to the braking operations are statistically evaluated.

10. Method (100) according to one of the preceding claims, wherein the vehicle (200a), in particular commercial vehicle (200b), has a braking system (290), a control unit (250) for controlling the braking system (290) and a data processing device (255), wherein the method (100) for determining (130) the braking variable (B) comprises: Transmitting (135) the bellows pressure change (pD) and / or the bellows pressure (pB) from the control unit (250) to the data processing device (255).

11. Computer program and / or computer-readable medium comprising instructions which, when the computer 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 claims 1 to 10.

12. 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 10.

13. Control unit (250) according to claim 12, 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 a commercial vehicle (200b), which is different from the control unit (250).

14. Vehicle (200a), in particular a commercial vehicle (200b), with a pneumatic suspension system (260) with a bellows (265) and a pressure sensor (270) for detecting a bellows pressure (pB) of the bellows (265) and with a control unit (250) connected to the pressure sensor (270) according to claim 12 or 13.

15. Vehicle (200a), in particular commercial vehicle (200b), according to claim 14, wherein the vehicle (200a), in particular commercial vehicle (200b), is a trailer (200c) of a multi-unit vehicle (201).

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