Method for determining braking power for a vehicle, in particular a utility vehicle, computer program and / or computer-readable medium, controller, and vehicle

Abstract

The invention relates to a method (100) for determining a braking power for a vehicle (200a), in particular a utility vehicle (200b), the vehicle (200a), in particular utility vehicle (200b), comprising: a pneumatic suspension system (260) having a bellows (265); an electro-pneumatic brake system (290) having a brake cylinder (295); and a pressure sensor (270) for detecting a bellows pressure (pB) of the bellows (265) and a brake pressure (BP) of the brake cylinder (295). The method (100) comprises: detecting (110) the bellows pressure (pB) and the brake pressure (BP) during a braking process; determining (120) a brake variable (B) on the basis of the bellows pressure (pB) and / or a bellows pressure change (PD) that can be derived from the bellows pressure (pB); and determining (130) a braking-process-related control brake variable (B65) for a control brake pressure (P65) on the basis of the brake variable (B) and the brake pressure (PB).

Description

[0001] Method for determining a braking power 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 determining braking performance for a vehicle, in particular a commercial vehicle, wherein the vehicle, in particular a commercial vehicle, has a pneumatic suspension system with a bellows, an electropneumatic braking system with a brake cylinder, and a pressure sensor device for detecting a bellows pressure of the bellows and a braking pressure of the brake cylinder. 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, and having a pressure sensor device for detecting a bellows pressure of the bellows and a braking pressure of the brake cylinder.

[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 braking force and / or deceleration as a braking variable related to braking force may be desirable in order to obtain information about braking performance and thus the condition or possible defects of a brake generating the braking force, a braked wheel, a braked axle, and / or a component thereof. In other words, such an onboard measurement may be of interest for monitoring the current braking performance of a vehicle, for example, to implement an automated driving function, to take prescribed maintenance intervals into account, and / or to plan maintenance and / or inspections.

[0005] The condition can be determined, for example, during legally and / or operationally defined inspections. However, braking performance, condition, and potential 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.

[0006] 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.

[0007] 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. 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, wherein each braking event in the data set includes 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 to at least one reference value.From this comparison, it is possible to determine whether the braking system is operating within acceptable limits. A device for implementing the method is also disclosed. The braking events can be categorized into a plurality of categories based on the vehicle's 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 a chassis, wheels, brakes, and electronic braking system. A trailer with supporting bellows is disclosed, with a pressure sensor arranged on one of the supporting bellows. The data from the pressure sensor represents an axle load and is transmitted to the brake control unit. The axle load can be measured for calculating a target braking force.

[0012] Furthermore, a control braking variable or target braking variable can be specified, for example, as a target deceleration or target braking force at a defined control pressure of the braking device. In other words, the braking variable can be specified by standards and / or legal regulations under a condition of an applied brake pressure. The control braking variable should be able to assess the braking performance under a specific condition, namely the activation of the braking system with a control braking pressure.

[0013] For example, the braking forces (reference values) required for a trailer per axle to achieve the legally prescribed minimum braking rate (semi-trailer 45%, drawbar trailer 50%) are calculated using a braking calculation program and stored in a control unit, such as a brake control unit (EBS electronics) of the trailer, along with the associated braking pressures. For example, the trailer has three axles. At an initial pressure of 1 bar, a braking force of approximately 4500 N should be applied to the first axle, and a braking force of approximately 4750 N should be applied to each of the second and third axles. At a second pressure of 6.6 bar, a braking pressure of approximately 40,000 N should be applied to each axle.

[0014] However, such high brake pressures are rarely applied during operation, so monitoring the braking force and / or deceleration at such pressures is not possible without additional effort. However, monitoring the braking force and / or deceleration at such pressures may be desirable to meet standardized and / or legal requirements or for braking system diagnostics.

[0015] The invention is based on the object of enriching the state of the art and enabling improved determination of a brake line. In particular, the invention solves the problem of being able to provide an effective and reliable comparison of a currently measured brake value with a control brake value.

[0016] According to one aspect of the invention, a method for determining braking performance for a vehicle, in particular a commercial vehicle, is provided. The vehicle, in particular a commercial vehicle, has a pneumatic suspension system with a bellows, an electropneumatic braking system with a brake cylinder, and a pressure sensor device for detecting a bellows pressure of the bellows and a brake pressure of the brake cylinder. The pneumatic suspension system can have more than one bellows, and the electropneumatic braking system can have more than one brake cylinder, so that the pressure sensor device can detect bellows pressures of multiple bellows and brake pressures of multiple brake cylinders. The method can accordingly be applied to the multiple bellows pressures and multiple brake pressures.The method comprises: detecting the bellows pressure and the brake pressure during braking; determining a braking variable based on the bellows pressure and / or a bellows pressure change derivable from the bellows pressure; and determining a control braking variable related to the braking at a control braking pressure based on the braking variable and the brake pressure.

[0017] It was recognized that the braking force acting on one of the wheels can influence the pressure within the bellows. Braking a wheel by applying brake pressure to the braking system 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.

[0018] 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.

[0019] The invention further recognizes that, based on the braking variable, which can be determined from the bellows pressure and / or its change, and the braking pressure, the braking variable can be extrapolated to the control braking variable as the target braking variable at the control braking pressure, for example, as a legally predetermined and / or standardized braking pressure. The control braking variable is a measure of braking performance. This makes it possible to determine braking performance without applying the control braking pressure to the braking device. Based on an assessment of the control braking variable, it is possible to determine whether the vehicle, an axle, or a wheel, is overbraked or underbraked.In addition, it is possible to detect defects such as brake cylinder failures or brake fading, changes in the load on the wheel brake, for example after a change of towing vehicle, as well as long-term changes in the performance of the wheel brakes, for example the brake becoming sleepy due to insufficient load, through simple and repeated inspection.

[0020] Optionally, the control braking variable is a control braking force or a control deceleration. This makes the control braking variable particularly relevant for assessing braking performance. The control braking force is the braking force acting on a wheel, an axle, an axle assembly, and / or the vehicle, assuming the applied control braking pressure. The control deceleration is the ratio of the control braking force to the axle load or the vehicle mass, optionally taking one or more other constants into account.

[0021] For the same reason, the braking variable is optionally a braking force or deceleration. The braking force can be the braking force acting on a wheel, an axle, an axle assembly, and / or the vehicle when the braking device is actuated with the brake pressure. The deceleration can be the ratio of the braking force to the axle load or the vehicle mass, optionally taking into account one or more other constants.

[0022] Optionally, the control braking variable can be determined taking into account the braking system's response pressure. It has been recognized that below a set pressure, typically no braking force can be applied, and thus no deceleration can be induced by the braking system. The response pressure can therefore be understood as a limit value characterizing the braking system or a wheel brake within the braking system. The response pressure is a constant defined by the braking system and is therefore vehicle-specific and / or vehicle-type-specific. By taking the response pressure into account, the control braking variable can be determined more precisely.

[0023] Optionally, the control brake variable is determined assuming a linear relationship between the brake variable and the brake pressure. It was recognized that braking force and deceleration, as examples of the brake variable, typically increase linearly with the brake pressure. This linear relationship can be used to effectively and reliably determine the control brake variable at the control brake pressure based on the brake variable and the brake pressure.

[0024] Optionally, determining the control brake variable includes a linear regression. It has been recognized that it is possible to perform a statistical analysis of multiple brake variables. For this purpose, a set of brake variables can be considered at a specific brake pressure. Based on the set of brake variables and the associated brake pressures, the linear regression can be performed to reliably determine the control brake variable at the control brake pressure.

[0025] Optionally, the bellows pressure and the brake pressure are recorded during a plurality of braking applications, the braking variable is determined for each of the plurality of braking applications, and the method comprises: determining an average control braking variable based on the control braking variables of the plurality of braking applications. This enables effective monitoring of the braking performance. For example, a first average value can be determined over, for example, 10 braking applications and / or 1 hour or less to detect current damage to the braking device, such as a defect in a brake cylinder and / or a wheel brake and / or fading when driving downhill. A second average value over 100 braking applications and / or over 1 day can be determined to detect current damage to the braking device, such as a defect in a brake cylinder and / or a wheel brake.A third average can be determined over 500 braking applications and / or 1 week to detect changes during ongoing operation, such as a change in the towing vehicle with increased retarder use and / or with an electric drive configured for regenerative braking (battery electric vehicle, BEV). Alternatively or additionally, a fourth average can be determined, for example, over 10,000 braking applications and / or 6 months to detect long-term changes in braking performance, such as brake pad wear due to insufficient use in long-distance transport. The control braking variable can thus be averaged over one or more numbers of braking applications and / or over one or more time periods to enable different assessments of braking force.

[0026] Optionally, the average control brake variable is determined taking into account weights that decrease with increasing brake pressure. It was recognized that brake variables at comparatively high brake pressures are subject to less fluctuation, or rather, less fluctuation relative to the brake pressure. By weighting the brake variables at higher brake pressures more heavily during evaluation and / or averaging than brake variables at lower brake pressures, the reliability of the control brake variable can be improved.

[0027] Optionally, the method comprises outputting control information depending on the control braking variable falling below a limit value. The output can comprise an output perceptible to a driver and / or user in order to warn them if the control braking variable falls below the limit value, for example by activating a warning lamp in the driver's cab. Alternatively or additionally, the control information can be sent as an output via a data processing device of the vehicle configured for wireless communication to a server external to the vehicle and used there. Alternatively or additionally, the control information can be stored as an output in an error memory in order to be read out during service or maintenance and to be able to service the brake accordingly. The same limit value and / or different limit values ​​can be defined for each of the aforementioned measures.

[0028] Optionally, the vehicle, in particular a commercial vehicle, has a control unit for controlling the braking system and a data processing device, wherein the method for determining the control braking variable comprises: transmitting the brake pressure and 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 control braking variable can thus be determined by the data processing device. Alternatively, it is possible for the data processing device to transmit the brake pressure and 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 control 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.

[0029] 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 computer 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 computer to implement a feature of the method described above, described as optional or advantageous, in order to achieve an associated technical effect.

[0030] 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 or advantageous in order to achieve an associated technical effect.

[0031] Optionally, the control unit for determining the control brake variable is configured to transmit the brake pressure and 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 control brake 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 brake pressure and the bellows pressure or the bellows pressure change.

[0032] Optionally, the data processing device is configured for wireless data transmission. This makes it possible for the brake pressure and 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 control braking variable can be determined by the external server. This allows the control unit and the data processing device to be designed to conserve resources. Furthermore, it enables the option of retrofitting an existing vehicle, particularly a commercial vehicle, since only the brake pressure and the bellows pressure change and / or the bellows pressure need to be recorded or transmitted to determine the control braking variable.According to one aspect of the disclosure, a vehicle, in particular a commercial vehicle, is provided with a pneumatic suspension system having a bellows, with an electropneumatic braking system having a brake cylinder, a pressure sensor device for detecting a bellows pressure of the bellows and a braking pressure of the brake cylinder, and with a control device as described above connected to the pressure sensor device.

[0033] 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 whose braking torque is transmitted via the air spring bellows.

[0034] In connection with the control unit and the vehicle, as well as for the method described above, the pneumatic suspension system can have more than one bellows and the electro-pneumatic braking system can have more than one brake cylinder, and accordingly, bellows pressures of several bellows and brake pressures of several brake cylinders can be recorded.

[0035] Further features of the invention and its technical effects emerge from the figures and the description of the preferred embodiments shown in the figures.

[0036] Fig. 1 is a schematic representation of a vehicle, in particular a commercial vehicle, according to one aspect of the invention;

[0037] Fig. 2 is a schematic representation of a detail of a vehicle, in particular a commercial vehicle, according to one aspect of the invention;

[0038] Fig. 3 is a schematic representation of a trailer as a vehicle, in particular a commercial vehicle, according to one aspect of the invention;

[0039] Fig. 4 is a schematic representation of a vehicle, in particular a commercial vehicle, according to one aspect of the invention; Fig. 5 is a control braking variable calculated by a method according to one aspect of the invention and a characterization of the relationship between braking variable and braking pressure; and

[0040] Fig. 6 is a schematic representation of a method according to one aspect of the invention.

[0041] Fig. 1 shows a schematic representation of a vehicle 200a, in particular commercial vehicle 200b, according to one aspect of the invention.

[0042] 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).

[0043] 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.

[0044] Details of the vehicle 200a, 200b are described with reference to Figs. 2 to 4.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] The vehicle 200a, 200b includes a pressure sensor device 270. The

[0050] Pressure sensor device 270 is configured to measure a bellows pressure pB and a brake pressure BP. The pressure sensor device 270 can be configured to measure bellows pressures pB of multiple bellows 265 and / or brake pressures BP of multiple brake cylinders 295 (see Fig. 4). The bellows pressure pB is the pressure prevailing in the interior of the bellows 265. The brake pressure BP is the pressure applied to a braking system 290 of the vehicle 200a, 200b. The bellows 265 has an effective area Aeff, which, together with the bellows pressure pB, defines a force transmitted by the bellows 265.

[0051] 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.

[0052] The axle guide 220 has a length 10 of the axle guide 220. The length 10 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 10 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 10 of the axle guide 220 can be measured and is a vehicle-specific or vehicle-type-specific constant.

[0053] 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).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, i.e. a dynamic axle load shift during deceleration or a dynamic contribution of the axle load FA.

[0054] 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 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.

[0055] The following explains how the individual components of the forces FBA, FBS, FBB acting on the bellows 265 can be calculated.

[0056] 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 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, I0 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. 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] Specifically in a semi-trailer, which typically has multiple axles 205 combined to form an axle assembly, the bellows 265 of these axles 205 are connected to one another entirely or at least laterally. Thus, the braking force FB of the vehicle 200a, 200b and / or the axle assembly can be determined. 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.

[0061] 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.

[0062] 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.

[0063] 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 braking. The center of gravity 202 is located at a center of gravity height hM, which can be estimated and / or taken 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, only lead to insignificant deviations in the following considerations. The center of gravity height hM is essentially a vehicle-specific or vehicle-type-specific constant. If the influences of the axle load shift S are taken into account during braking, the calculation of the braking variable B or the braking force FB and / or the braking AB can be improved. For this purpose, assumptions, 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 relief of 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.

[0064] 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.

[0065] 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 device 170 (see Figs. 2 and 4) to detect the bellows pressure pB and the brake pressure BP.

[0066] 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 control braking variable B65 by transmitting 125 the brake pressure BP and 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 braking variable B65 according to the method 100 shown in Fig. 6 and / or transmit the data received from the control unit 250 to the server external to the vehicle, which determines the control braking variable B65. The data processing device 255 is, for example, a telematics device.The data processing device 255 is configured to output 150 a control information item K1 depending on the control braking variable B65 falling below a limit value (see Fig. 5). For this purpose, the data processing device 255 can be configured to output the control information K1 on a vehicle-mounted output device in a manner perceptible to a driver and / or user, to write it to a memory, and / or to transmit it to the vehicle-external server.

[0067] Fig. 5 shows a control braking variable B65 calculated by a method 100 according to one aspect of the invention and a characterization of the relationship between braking variable B and brake pressure BP. Fig. 5 is described with reference to Figs. 1 to 4. Fig. 5 shows, in Fig. 5 (A), the determination of the control braking variable B65 using the example of a control braking force FB65, and in Fig. 5 (B), a relationship between a deceleration AB and the brake pressure BP.

[0068] In Fig. 5 (A), the braking force FB is plotted against the braking pressure BP. The braking force FB can be determined from the bellows pressure pB as described with reference to Figs. 1 to 4. Below a set pressure PTh, no braking force FB can be determined. The set pressure PTh is thus a limit value for the braking pressure BP and defines an ordinate section in the plot, i.e., a shift in the relationship between the braking force FB and the braking pressure BP toward higher braking pressures BP.

[0069] To determine 130 the control brake variable B65, a linear relationship L between the braking force FB and the braking pressure BP is assumed.

[0070] The bellows pressure pB and the brake pressure BP are recorded during a plurality of braking applications in order to determine a braking force FB65 for the majority of braking applications. During each of the braking operations, the maximum brake pressure BP and the associated bellows pressure pB can be recorded in order to characterize the braking performance at maximum brake pressure. The braking forces FB determined from the corresponding bellows pressures pD are illustrated with the brake pressures BP as crosses in Fig. 5 (A). The braking force FB shows a linear relationship with the brake pressure BP, whereby the fluctuation or scatter of the braking force FB decreases around the linear relationship L at higher brake pressures BP relative to the brake pressure BP.

[0071] Determining 130 the control braking variable B65 involves a linear regression. For this purpose, a regression line defining the linear relationship L is placed through the measured values ​​defined by the braking force FB and the braking pressure BP. This allows an average control braking variable mB65 to be determined based on the linear relationship L and the majority of braking applications. Alternatively, assuming the linear relationship L, it is possible to determine the control braking variable B65 based on only one measured value defined by the braking force FB and the braking pressure BP. By repeatedly determining the control braking variable B65 for different braking applications, the average control braking variable mB65 can also be determined. The average control braking variable mB65 can be determined taking into account heavier weights as the braking pressure PB increases.For weighting purposes, the brake variables B can also be divided into pressure ranges, i.e., into ranges of brake pressure BP at which the respective brake variable B was determined. A weight w can be calculated, for example, from the brake pressure BP as w = BP / P65, i.e., the ratio of brake pressure BP to control brake pressure P65. This allows the determined values ​​for the brake force FB in low pressure ranges (control pressure of approximately 1 bar to 3 bar) to be extrapolated to values ​​of the brake force FB at a control pressure of 6.5 bar to assess braking performance.

[0072] The linear relationship shown with a dashed line shows the braking performance, i.e., the relationship between braking force FB and braking pressure PB, with a control braking variable B65 that corresponds to a target, for example, according to a legal standard. A specific braking force FB must be applied at a control braking pressure P65 of 6.5 bar. In the example shown, the measured values ​​indicate underbraking, i.e., a lower control braking force FB65 than specified at the control braking pressure P65.

[0073] In Fig. 5 (B), deceleration AB is plotted against brake pressure BP. The linear relationship shown by a dashed line shows the braking performance, i.e., the relationship between deceleration AB and brake pressure BP, with a control braking variable B65 that corresponds to a target, e.g., according to a legal standard. The linear relationship shown by a dot-dashed line shows the braking performance in the case of under-braking, analogous to Fig. 5 (A). The linear relationship shown by a solid line in Fig. 5 (B) shows the braking performance in the case of over-braking, i.e., a higher braking performance than the target.

[0074] The control deceleration AB65 and the control braking force FB65 can be converted into one another: AB65 = FB65 / (FA xg), i.e., the control deceleration AB65 is equal to the control braking force FB65 divided by the product of axle load FA and location factor g. Fig. 6 shows a schematic representation of a method 100 according to one aspect of the invention. The method 100 is a method 100 for determining a braking power for a vehicle 200a, 200b. Such a vehicle 200a, 200b is described with reference to Figs. 1 to 4. Fig. 6 is also described with reference to Figs. 1 to 5.

[0075] The method 100 comprises: detecting 110 the bellows pressure pB and the brake pressure BP during braking.

[0076] A braking variable B is determined 120 based on the bellows pressure pB and / or a bellows pressure change PD that can be derived from the bellows pressure pB.

[0077] A control braking variable B65 related to the braking is determined 130 at a control braking pressure P65 based on the braking variable B and the braking pressure PB. The control braking variable B65 is a control braking force FB65 or a control braking AB65. Accordingly, the braking variable B is a braking force FB or a braking AB.

[0078] The determination 130 of the control brake variable B65 takes into account a response pressure PTh of the brake system 290.

[0079] The determination 130 of the control brake variable B65 is carried out under the assumption of a linear relationship L between the brake variable B and the brake pressure BP.

[0080] Optionally, the brake pressure BP and the bellows pressure change pD and / or the bellows pressure pB are transmitted 125 from the control unit 250 to the data processing device 255.

[0081] Determining 130 the control braking variable B65 involves a linear regression.

[0082] The bellows pressure pB and the brake pressure BP are recorded during a plurality of braking applications, the braking variable B is determined for each of the plurality of braking applications, and the method 100 comprises: determining 140 an average control braking variable mB65 based on the control braking variables B65 of the plurality of braking applications. The average control braking variable mB65 is determined taking into account weights that decrease with increasing brake pressure PB.

[0083] A control information Kl is output 150 depending on the control braking variable B65 falling below a limit value.

[0084] Reference symbol (part of the description)

[0085] 100 procedures

[0086] 110 Capture

[0087] 120 Determining a brake size

[0088] 125 Submit

[0089] 130 Determining a control braking variable

[0090] 140 Determining an average control braking value

[0091] 150 Issues

[0092] 200a vehicle

[0093] 200b commercial vehicle

[0094] 200c trailer

[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] 255 Data processing device

[0106] 260 pneumatic suspension system

[0107] 265 bellows

[0108] 270 Pressure sensor device

[0109] 280 kingpins

[0110] 290 electropneumatic braking system

[0111] 295 brake cylinders

[0112] AB braking

[0113] AB65 Control braking

[0114] Aeff effective area B brake size

[0115] B65 Control brake variable

[0116] BP brake pressure

[0117] D Vehicle deceleration

[0118] FA axle load

[0119] FB braking force

[0120] FB65 Control braking force

[0121] FBA force on bellows, axle load shift

[0122] FBB braking force on bellows

[0123] FBS static force on bellows

[0124] FBZ Pin braking force h Height of a bearing hM Center of gravity height hZ Pin height

[0125] Kl control information leff effective wheelbase

[0126] 10 Length of an axle guide

[0127] 11 Distance between bearing and axle

[0128] L linear relationship mB65 control brake variable n number of axes

[0129] P65 Control brake pressure pB Bellows pressure pD Bellows pressure change pRef Reference pressure pTh Response pressure

[0130] S Axle load shift

Claims

Patent claims 1. A method (100) for determining a braking performance 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), an electropneumatic braking system (290) with a brake cylinder (295) and a pressure sensor device (270) for detecting a bellows pressure (pB) of the bellows (265) and a braking pressure (BP) of the brake cylinder (295), wherein the method (100) comprises: Detecting (110) the bellows pressure (pB) and the brake pressure (BP) during braking; 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); and determining (130) a control braking variable (B65) related to the braking at a control braking pressure (P65) based on the braking variable (B) and the braking pressure (PB).

2. Method (100) according to claim 1, wherein the control braking variable (B65) is a control braking force (FB65) or a control deceleration (AB65).

3. Method (100) according to claim 1 or 2, wherein the braking variable (B) is a braking force (FB) or a deceleration (AB).

4. Method (100) according to one of the preceding claims, wherein the determination (130) of the control braking variable (B65) takes place taking into account a response pressure (PTh) of the braking system (290).

5. Method (100) according to one of the preceding claims, wherein the determination (130) of the control brake variable (B65) is carried out under the assumption of a linear relationship (L) between the brake variable (B) and the brake pressure (BP).

6. Method (100) according to one of the preceding claims, wherein the determination (130) of the control braking variable (B65) comprises a linear regression.

7. Method (100) according to one of the preceding claims, wherein the bellows pressure (pB) and the brake pressure (BP) are recorded during a plurality of braking operations, the braking variable (B) is determined for each of the plurality of braking operations, and the method (100) comprises: Determining (140) an average control braking quantity (mB65) based on the control braking quantities (B65) of the majority of braking operations.

8. The method (100) according to claim 7, wherein the mean control braking variable (mB65) is determined taking into account weights increasing with increasing brake pressure (PB).

9. Method (100) according to one of the preceding claims, wherein the method (100) comprises: Outputting (150) a control information (Kl) depending on the control braking variable (B65) falling below a limit value.

10. Method (100) according to one of the preceding claims, wherein the vehicle (200a), in particular commercial vehicle (200b), has 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 (125) the brake pressure (BP) and 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) for determining (130) the control brake variable (B65) for transmitting (135) the brake pressure (PB) and the bellows pressure change (pD) and / or the bellows pressure (pB) is set up to be transmitted to a data processing device (255) of the vehicle (200a), in particular the 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), 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) connected to the pressure sensor device (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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