Brake system and method for operating the brake system
Patent Information
- Application Number
- EP2023700612
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-02-22
- Filing Date
- 2023-01-09
- Publication Date
- 2025-01-01
AI Technical Summary
In vehicles with higher levels of automation, especially commercial vehicles, there is a need for an improved braking system that ensures safe operation even when the driver is not monitoring the vehicle, without requiring additional control units, which would increase installation space and costs.
A braking system with wheel speed sensors on multiple axles, including both main and additional axles, where control devices generate and output brake control signals to manage brake pressure, with optimized cabling and data lines allowing for redundant operation and diagnostic capabilities without additional control units, enabling fail-safe operation and expanded diagnostic options.
This solution ensures safe ferry operation by allowing for dynamic brake pressure adjustments on main axles and provides an expanded diagnostic capability through wheel speed monitoring, reducing installation effort and costs by utilizing existing control units and minimizing additional connections, while maintaining reliable braking functions even in fault conditions.
Smart Images
Figure 1.1
Abstract
Description
[0001] Braking system and method for operating the braking system
[0002] The invention relates to a braking system for a vehicle, in particular a commercial vehicle, a method for operating the same and a vehicle, in particular a commercial vehicle, with the braking system.
[0003] In vehicles, especially commercial vehicles with a higher degree of automation, especially Level 3 or higher, it has been shown that improved or expanded diagnostic capabilities must be provided when a driver supervising ferry operations is no longer present to monitor the vehicle's or commercial vehicle's functionality. A number of sensors and control units are already installed in the vehicle, so additional control units, in particular, require additional installation space and also increase integration effort and costs.
[0004] Braking systems, in particular electronic braking systems (EBS), generally have a central first control unit that, during normal operation, outputs electrical brake control signals on the basis of which brake pressures on the wheel brakes on a front and rear main axle of the vehicle can be controlled. In some cases, a second control unit is used that can maintain auxiliary or at least rudimentary braking in the event of a fault in the central first control unit, which is also referred to as a fail operation braking system (FOBS). During normal operation of the braking system, the first control unit can generally perform braking operation including dynamic driving control via the individual wheel brakes on the main axles. In the event of a fault or during backup operation of the braking system, dynamic driving control is at least limited or no longer possible.This is described, for example, in DE 10 2019 106 243 A1. In order to be able to carry out braking operations under driving dynamics aspects in the respective operating modes, the control units rely in particular on wheel speed signals from wheel speed sensors assigned to the brakeable wheels of the main axle. Various wiring options are available between the wheel speed sensors and the respective control unit, for example, branched wiring via a Y-connection, as shown by way of example in DE 10 2017 005 071 A1, or unbranched direct wiring. DE 10 2016 006 763 A1 further describes connecting several speed sensors via several connections to an axle modulator with an internal control unit that evaluates the wheel speed signals.
[0005] The object of the invention is to provide a braking system and a method for operating the braking system, with which safe ferry operation in an automated vehicle can be easily ensured. A further object is to provide a vehicle.
[0006] This object is achieved by a braking system, a method for operating the braking system, and a vehicle according to the independent claims. The subclaims specify preferred developments.
[0007] According to the invention, a braking system is provided for the electronically controlled braking of wheels on at least two main axles of a vehicle via wheel brakes of the braking system, wherein the braking system comprises at least:
[0008] - Wheel speed sensors (active or passive) on the at least two main axles and on at least one further additional axle for outputting wheel speed signals depending on the determined wheel speeds of the brakeable wheels on the at least two main axles and the wheels on the at least one additional axle, i.e. at least one wheel speed sensor is assigned to each of the brakeable wheels of the at least two main axles and the wheels of the at least one additional axle, and
[0009] - at least two (brake) control units for generating and outputting brake control signals, wherein the wheel brakes on the at least two main axles can be controlled as a function of the brake control signals, e.g. using an axle modulator or a pressure control module or a comparable module capable of providing a corresponding brake pressure for the wheels of the respective vehicle axle as a function of the brake control signals, wherein the wheel speed sensors on the at least two main axles, which are assigned to the respective brakeable wheels of the at least two main axles, are signal-conductingly connected to the at least two control units via main data lines in such a way that each control unit can receive a determined wheel speed (or, equivalently, a variable dependent thereon) for each wheel on the at least two main axles to which at least one wheel speed sensor is assigned, via the wheel speed signals,and wherein each wheel speed sensor on the at least one additional axle, which is assigned to the respective wheels of the at least one additional axle, is connected in a signal-conducting manner via an additional data line only to one of the at least two control units, and each control unit is in turn connected to at least one of the wheel speed sensors on the at least one additional axle.
[0010] According to the invention, a method for operating the braking system and a vehicle with the braking system are further provided. In the context of the invention, a main axle is understood to be a vehicle axle of the vehicle whose wheels can be braked, wherein stable driving operation is also ensured via this main axle by adjusting the brake pressure on this main axle in "critical" situations based on driving dynamics, for example as part of an ABS control, ASR control, ESC control or similar stability control. The control units are particularly designed to generate the brake control signals for the wheel brakes as a function of the wheel speed signals from the wheel speed sensors on the main axles. In this case, a wheel brake is preferably assigned to all wheels of the at least two main axles for braking the wheels of the at least two main axles of the vehicle wheel by wheel.In contrast, the “non-critical” additional axle generally does not undergo any dynamic adjustment of the brake pressure; it therefore only serves to provide support, for example as a rolling, load-bearing vehicle axle, in particular a lift axle, whereby the additional axle cannot or does not necessarily have to be actively braked via wheel brakes in ferry operation.
[0011] The invention therefore already achieves the advantage of providing an expanded diagnostic option based on the wheel speed behavior of the additional axle. Based on the wheel speeds detected on the additional axle, the wheel end can be monitored, and the functionality of individual vehicle components related to it can be checked, something that has not been possible in this way to date. Advantageously, by evaluating the wheel speeds on the additional axle, the plausibility check or functionality verification of the braking system for the main axles can also be carried out if, for example, a malfunction occurs in the main axle control due to a common cause error. This can be determined by evaluating the wheel speeds on the additional axles, for example, by comparing the wheel speed signals transmitted by the main axle and the additional axles.
[0012] By using the brake system's control units, installation effort and costs are low, as no additional control units are required. The control units used are already designed to receive and process the wheel speed signals from wheel speed sensors, so the control units only require minor adjustments and the corresponding additional data lines are laid to the additional wheel speed sensors on the additional axle. The additional data lines preferably connect the respective wheel speed sensor to the respective control unit via direct wiring.
[0013] Since the wheel speed sensors on the at least one additional axle are also distributed among the control units, optimized cabling to the next control unit can be selected and, in the event of a fault, the other control unit can at least read the wheel speed sensors connected to it and perform diagnostic functions based on this. By distributing the wheel speed sensors of the at least one additional axle between the two control units, the number of (additional) connections per control unit can also be minimized. In this case, it can preferably also be provided that the at least two control units are connected to one another via an exchange data line for the exchange of signals relating to the wheel speeds, in particular of the at least one additional axle.This means that during normal operation, both control units can access the additional wheel speed information, whereby one of the control units can be selected as the primary control unit.
[0014] Thus, it can preferably be provided that the at least two control units of the braking system are formed by a primary control unit and a secondary control unit, wherein the primary control unit is designed to generate and output primary braking control signals in normal operation of the braking system, for example as a function of the determined and received wheel speeds of the wheels of the at least two main axles, and the secondary control unit is designed to generate and output secondary braking control signals in backup operation of the braking system in which the primary control unit has failed, i.e. has a defect or a malfunction, for example also as a function of the determined and received wheel speeds of the wheels of the at least two main axles, wherein the wheel brakes of the braking system can be controlled in normal operation as a function of the primary braking control signals and in backup operation as a function of the secondary braking control signals.
[0015] Accordingly, two coordinating control units are provided in the braking system, which can stand in for each other depending on their functionality to provide a so-called "fail operation braking system (FOBS)". This is then further developed in such a way that the two control units can also monitor the additional axles in parallel (divided accordingly between them) and can receive and forward or further process the wheel speed signals, preferably evenly divided between them. In the event of a failure of the primary control unit, and provided the wheel speed sensors are evenly distributed, the secondary control unit that is still functioning can still receive and evaluate the wheel speeds from its assigned wheel speed sensor on the additional axle, thus providing additional monitoring is still possible even in the event of a fault.
[0016] It is preferably further provided that at least two additional axles (ie at least one four-axle vehicle) are provided in the braking system, wherein the wheel speed sensors on the at least two additional axles are distributed evenly between the at least two control units, for example in such a way that each of the at least two control units is connected via the additional data lines to the same number of wheel speed sensors on the at least two additional axles, for example axle by axle or wheel by wheel (for example in the case of an odd number of additional axles), without one of the wheel speed sensors on the at least one additional axle being connected to more than one of the at least two control units.In this way, in the event of a fault, the second control unit can still access half (if there is an even number of additional axles) of the additional wheel speed sensors on the additional axles and each control unit then ideally has the same number of additional connections to receive the wheel speed signals or to connect the additional data lines.
[0017] It is preferably further provided that the wheel speed sensors that are assigned to the same additional axle are connected to the same control unit via the additional data lines, ie an axle-wise assignment or distribution to the at least two control units is advantageously selected, and / or at least some of the wheel speed sensors that are assigned to the same additional axle are connected to different control units via the additional data lines for wheel-wise distribution of at least some of the wheel speed sensors to the at least two control units.
[0018] Preferably, it is further provided that at least one of the control units, preferably the primary control unit operating primarily in a FOBS configuration of the braking system during normal operation, is configured to monitor an additional axle status depending on the wheel speed signals from the wheel speed sensors on the at least one additional axle, wherein the additional axle status indicates whether the additional axle is operating faultily or correctly. Accordingly, a diagnosis of the wheel end can be performed based on the wheel rotation behavior of the additional axles, i.e., whether the wheel-side end of the at least one additional axle is behaving as expected.
[0019] For this purpose, it can be provided, for example, that the at least one additional axle is formed by a lifting axle of the vehicle, wherein the lifting axle can be raised and lowered via a lifting axle control, for example depending on the load, wherein at least one of the control units is designed to monitor a lifting axle status by checking the plausibility of the setting of the lifting axle control depending on the wheel speed signals output by the wheel speed sensors on the lifting axle. By monitoring the wheel speeds, it can then be determined, for example, whether a lowering or raising of the lifting axle requested via the lifting axle control is actually implemented, which in this case would be reflected by wheel speeds that are unequal or zero.
[0020] Furthermore, it can be provided, for example, that at least one of the control units is designed to check, depending on the wheel speed signals output by the wheel speed sensors on the additional axle, whether a wheel speed of the wheels on the additional axle matches or deviates from a target wheel speed, in order to determine whether the additional axle is operating faultily or correctly. This makes it possible to detect an impairment in wheel rotation behavior, for example due to a tire blowout, a jammed brake, or other defects at the wheel end of the additional axle. The wheel speeds of other wheels on other axles (other additional axles or main axles) of the vehicle can be used as a good approximation as the target wheel speed.
[0021] Preferably, it is further provided that the at least two control units each have main connections for connecting a wheel speed sensor to a main axle and additional connections for connecting a wheel speed sensor to an additional axle, wherein
[0022] - each wheel speed sensor that is connected to the respective control unit via the main data line is connected to its own or separate main connection of the respective control unit and / or is assigned its own or separate main connection on the respective control unit, and - each wheel speed sensor that is connected to the respective control unit via the additional data line is connected to its own or separate additional connection of the respective control unit and / or is assigned its own or separate additional connection on the respective control unit.
[0023] Accordingly, separate connections can be provided for each wheel speed sensor, ensuring a separate or independent power supply and signal transmission. This allows for electrical decoupling, preventing different wheel speed sensors from interfering with each other during reading and / or power supply.
[0024] Preferably, it is further provided that the main data lines each have a branching y-connection such that a wheel speed sensor arranged on the at least two main axles is connected to the at least two control units simultaneously via the respective y-connection and via the respective main connections. A wheel speed sensor can therefore be read by at least two control units, thereby saving sensors. Alternatively, it can also be provided that a wheel speed sensor arranged on the at least two main axles is connected to the respective control unit via the respective main data line by direct cable via the respective main connection, wherein two wheel speed sensors are assigned to each wheel on the at least two main axles and each of the two wheel speed sensors of a wheel is directly connected to another control unit via the main data line.A redundant design can therefore also be provided, whereby mutual interference during reading and / or power supply via the respective control unit can normally be excluded for each wheel, so that simultaneous reading of the wheel speeds of a wheel can be carried out in an electrically decoupled manner. According to a further development, it is also provided that the at least two control units are configured to be parameterizable and are designed to switch between a first operating mode and a second operating mode for each main connection and each additional connection, wherein.
[0025] - is or can be switched to the first operating mode if the respective main connection or additional connection of a control unit is connected to a wheel speed sensor via a y-connection, and
[0026] - is or can be switched to the second operating mode if the respective main connection or additional connection of a control unit is directly connected to a wheel speed sensor.
[0027] This enables variable operation of the respective control unit, since hardware components and software routines in the respective control unit can be activated or deactivated depending on whether they are actually needed. For example, with a branching y-connection, coordination of the control units via a corresponding software routine is necessary, and the active control unit uses different hardware components for reading and / or supplying power to the respective wheel speed sensor than the deactive control unit. With direct wiring, however, no such coordination is necessary. This design of the control unit is not necessarily limited to receiving and processing wheel speed signals from additional axles and / or having direct wiring between the wheel speed sensors on the additional axle and the respective control unit.
[0028] Preferably, it is further provided that the at least two control units are connected to each other via an exchange data line for exchanging signals relating to the wheel speeds, in particular of the at least one additional axle. During normal operation, the two control units can thus coordinate with each other, and the wheel speed signals of the additional axle can be processed centrally in just one of the control units, preferably the primary control unit.
[0029] The invention is explained in more detail below with reference to the figures. They show:
[0030] Fig. 1 , 2 schematic views of a three-axle and four-axle vehicle respectively.
[0031] Figures 1 and 2 show a schematic of a vehicle 1 having a braking system 2 with wheel brakes 2a and wheel speed sensors 3 on the individual wheels 4. The wheel speed sensors 3 can be operated actively or passively. The wheel speed sensors 3 are assigned to the individual wheels 4 of two main axles H of the vehicle 1, a steerable front main axle Hv and a rear main axle Hh, and at least one additional axle Z, in Fig. 1 a first additional axle Z1 and a second additional axle Z2 and in Fig. 2 only a first additional axle Z1, i.e. they measure a wheel speed N4 of the respectively assigned wheel 4 on the respective main axle H or additional axle Z.
[0032] Based on the measured wheel speeds N4 of the wheels 4 of the main axles H, the brake pressures applied to the individual wheel brakes 2a on the wheels 4 of the main axles H can be specified or adjusted from a driving dynamics perspective, for example, within the framework of an ABS control system, an ASR control system, or an ESC control system. This is ensured here using two control units 5 of the braking system 2: a primary control unit 5a and a secondary control unit 5b. The primary control unit 5a is used in normal operation 2N of the braking system 2, and the secondary control unit 5b is used in a backup operation 2B of the braking system 2 in the event of a fault.Each of the control units 5 is capable of monitoring the braking system 2 and, depending on input signals, in particular wheel speed signals S3 from the wheel speed sensors 3, but also automated braking specifications and signals from other sensors, generating and outputting brake control signals BS (5a: primary brake control signals BSa, 5b: secondary brake control signals BSb). The brake control signals BS can, for example, contain target brake pressures or related variables that are determined by the respective control unit 5 in normal operation 2N or in backup operation 2B. The wheel brakes 2a on the respective main axle H are then controlled depending on these brake control signals BS, i.e. in normal operation 2N via the primary brake control signals BSa and in backup operation 2B via the secondary brake control signals BSb.For this purpose, the control units 5 can control axle modulators 20 (pressure control module) assigned to the main axles H with the respectively generated and output brake control signals BS via control lines 20a, wherein the axle modulators 20 are each designed to control a brake pressure specified via the brake control signals BS to the wheel brakes 2a of the respective main axle H.
[0033] For such wheel speed-based control of the respective wheel brakes 2a, the control units 5 are connected via main data lines 7H to the wheel speed sensors 3 on the two main axles H in order to enable transmission of the wheel speed signals S3 and, for example, when the wheel speed sensors 3 are actively operated, also to ensure that the wheel speed sensors 3 are supplied with power by the respective control unit 5. According to the embodiment shown in Fig. 1 and Fig. 2, branching y-connections 8 are arranged in the main data lines 7H to the respective control unit 5 such that each wheel speed sensor 3 arranged on the main axles H can be signal-conductingly connected to or supplied with power both from the primary control unit 5a (2N in normal operation) and from the secondary control unit 5b (2B in backup operation).
[0034] For this purpose, the primary control unit 5a has primary main connections 9aH, and the secondary control unit 5b has secondary main connections 9bH, to which the branching main data lines 7H are each connected. In order to read a wheel speed sensor 3 on the main axles H and, if necessary, supply it with power, the two control units 5 in this embodiment must be coordinated to avoid mutual interference during signal reception and transmission, as well as during power supply via the y-connection 8.
[0035] Alternatively, two wheel speed sensors 3 can be assigned to each wheel 4 of the main axles H, with each wheel speed sensor 3 of a wheel 4 being connected to a different control unit 5 via an independent, unbranched main data line 7H. Instead of branching through the y-connection 8 (with only one wheel speed sensor 3 per wheel 4), two independent main lines 7H can also run from a wheel 4 or from a wheel speed sensor 3 to the respective control unit 5 (with two wheel speed sensors 3 per wheel 4). In this embodiment, each wheel speed sensor 3 on the main axles H can be read by only one control unit 5, so that there is no mutual influence in the signal reception and transmission or in the power supply, and accordingly no coordination between the two control units 5 is necessary.
[0036] In both described variants (branched and unbranched), each of the two control units 5 (coordinated or uncoordinated) can access the wheel speeds N4 of all wheels 4 on the main axles H and generate brake control signals BS depending on this. This allows driving dynamics control based on the recorded wheel speeds N4 of all wheels 4 of the main axles H to be maintained in normal operation 2N by the primary control unit 5a and, in the event of a failure of the primary control unit 5a, i.e., in the event of a fault or in backup operation 2B, by the still functioning secondary control unit 5b. The secondary control unit 5b can then continue to provide at least rudimentary braking functions in this redundant fallback level, taking driving dynamics into account.
[0037] In contrast, the wheel speed sensors 3 on the additional axles Z are directly connected via an additional data line 7Z to only one of the two control units 5, either axle by axle (see Fig. 1) or wheel by wheel (see Fig. 2). In the three-axle variant according to Fig. 2, the wheel speed sensor 3 on one (right) wheel 4 of the first (only) additional axle Z1 is connected via a secondary additional connection 9bZ, for example, only to the secondary control unit 5b, and the wheel speed sensor 3 on the other (left) wheel 4 of the first (only) additional axle Z1 is connected via a primary additional connection 9aZ, for example, only to the primary control unit 5a. In the four-axle variant according to Fig.1, the wheel speed sensors 3 on both wheels 4 of the first additional axle Z1 are connected via the secondary additional connections 9bZ only to the secondary control unit 5b, and the wheel speed sensors 3 on both wheels 4 of the second additional axle Z2 are connected via the primary additional connections 9aZ only to the primary control unit 5a. Each wheel speed sensor 3 on the additional axles Z can therefore be read and, if necessary, supplied with power by only one control unit 5, so that there is no mutual influence during signal reception and transmission, nor during the power supply via the respective additional connections 9Z. Accordingly, the control units 5 in both embodiments (Fig. 1 and Fig. 2) do not need to be coordinated with one another with regard to these wheel speed sensors 3 on the additional axles Z. At the same time, in both embodiments (Fig. 1 and Fig. 2), each control unit 5 also reads at least one wheel speed sensor 3 on the additional axle(s) Z.In this case, even during normal operation 2N of the braking system 2, data exchange of wheel speed information can take place between the two control units 5 via an exchange data line 7A. This allows the wheel speeds N4 of all wheels 4 of the additional axles Z to be evaluated centrally during fault-free operation of the braking system 2, for example, in the primary control unit 5a, in order to increase the information density. If a fault occurs, in backup operation 2B of the braking system 2, at least the wheel speeds N4 of the wheel speed sensors 3 on the additional axle(s) Z, which are connected to the secondary control unit 5b, can still be used.
[0038] The additional provision of wheel speed sensors 3 on the non-critical additional axle(s) Z, which are normally not considered by the control units 5 for dynamic braking pressure control, enables monitoring of additional axles of vehicle 1 or the determination of an additional axle status ZS, thus increasing the overall diagnostic scope in vehicle 1. This is particularly advantageous for safe ferry operation of vehicles 1 with a higher degree of automation, in particular Level 3 or higher (according to SAE Standard J3016).
[0039] If one of the additional axles Z is, for example, a lifting axle L, a lifting axle status ZSL can be determined based on the wheel speed signals S3 supplied by the wheel speed sensors 3 on this additional axle Z or lifting axle L, i.e. whether a lifting axle control 40, which ensures raising or lowering of the lifting axle L, is functioning or whether, for example, there is a mechanical defect. Depending on the setting of the lifting axle control 40, it can be expected that the wheels 4 on the lifting axle L either do not rotate (lifting axle L raised) or rotate (lifting axle L lowered), which can be verified by evaluating the wheel speed signals S3 supplied by the respective wheel speed sensors 3 on the lifting axle L in the respective control unit 5, wherein the respective control unit 5 is also connected to the lifting axle control 40 in a signal-conducting manner, for example via the vehicle's internal data bus, in particular the CAN bus.
[0040] Furthermore, based on the wheel speed signals S3 supplied by the wheel speed sensors 3 on the respective additional axle Z, it can be determined whether a tire blowout or other impairment at the wheel end (wheel-side end of the respective additional axle Z, e.g., wheel bearing, wheel hub, rim, brake disc, etc.) has occurred, insofar as such an event demonstrably changes the wheel rotation behavior of the respective wheel 4 on the respective additional axle Z compared to the expected normal case. For additional diagnosis or monitoring of the additional axle status ZS, the determined wheel speeds N4 of the wheels 4 on the additional axles Z can be compared with the expected target wheel speeds N4target.
[0041] Accordingly, no additional control unit 5 is required to expand the scope of monitoring or diagnostics of vehicle 1, since the existing control units 5 are used to monitor and control the braking system 2. These existing control units 5 already have interfaces to wheel speed sensors 3 on the main axles H (via the main data lines 7H) and have the respective software routines for processing the wheel speed signals S3, so that the same hardware and software variant for the control unit 5 can be used to read out the wheel speed sensors 3 on the additional axles Z as in a vehicle 1 with a lower degree of automation, for example Level 2 (e.g. without wheel speed sensors 3 on the additional axles Z).Apart from the activation of further additional connections 9Z on control unit 5 and the provision of wheel speed sensors 3 on the respective additional axles Z including the additional data line 7Z, no adaptation is necessary. Furthermore, due to the even distribution of the wheel speed sensors 3 on the additional axles Z among the respective control units 5, optimized cabling can be enabled if the wheel speed sensors 3 are assigned to the next "still free" control units 5 depending on the installation location. Furthermore, not all additional connections 9Z are or need to be provided for the extended monitoring by (only) a single control unit 5, although due to the possibility of data exchange between the control units 5 via the exchange data line 7A, wheel speed information from all available wheel speed sensors 3 on the additional axles Z can still be used, at least during normal operation 2N of the braking system 2.In the event of a fault, the wheel speed sensors 3 connected to the control unit 5 that is still functioning can still be used.
[0042] In order to enable variable use of the control units 5 used here, it is further provided that the control units 5 are designed so that they can be parameterized. For this purpose, the respective control unit 5 can switch for each main connection 9H and also for each additional connection 9Z between a first operating mode B1, which is designed to use a connection branched via the y-connection 8 between the control unit 5 and a wheel speed sensor 3, and a second operating mode B2, which is designed to use an unbranched, directly wired connection between the control unit 5 and a wheel speed sensor 3. This has the advantage that, depending on the electrical connection (branched / unbranched) between the respective wheel speed sensor 3 and the respective control unit 5, a targeted selection can be made as to which hardware components and software routines are used in the respective control unit 5.As already described, mutual coordination of the relevant control units 5 is necessary for reading the wheel speed sensors 3 on the main axles H via the y-connections 8. For this purpose, a software routine determines, according to defined rules, which control unit 5 is authorized to read a wheel speed sensor 3 on the respective main axle H via the respective main connection 9H and, if necessary, to supply it with power. As a rule, it can be specified, for example, that the primary control unit 5a is used in normal operation 2N of the braking system 2 and the secondary control unit 5b is used only in the event of a fault or in backup operation 2B of the braking system 2 on the main axles H.
[0043] In the control unit 5 being used, the respective main connection 9H is then activated by the corresponding software routine, whereby the hardware components in the control unit 5 required to read the respective wheel speed sensor 3 on the main axle H are accessed. In the other control unit 5 not being used, the main connection 9H to the same wheel speed sensor 3 is switched to passive by the corresponding software routine, whereby the hardware components in the control unit 5 required to read the respective wheel speed sensor 3 are "switched off" or deactivated. This allows complete electrical decoupling for the respective wheel speed sensor 3 and prevents mutual interference during signal reception and transmission as well as during the power supply (with actively operated wheel speed sensors 3).
[0044] If no branching y-connection 8 is provided between the control unit 5 and a wheel speed sensor 3, for example in the unbranched variant with two wheel speed sensors 3 per wheel 4 of the main axles H (not shown) and / or on the additional axles Z, the main connections 9H or the additional connections 9Z of the control units 5 can remain permanently active. Mutual interference during signal reception and transmission as well as during the power supply (with actively operated wheel speed sensors 3) is not possible in this case, since electrical decoupling already exists due to the existing direct wiring. Accordingly, no prior coordination via a software routine is necessary for the respective connections 9H or 9Z of the control unit 5.
[0045] To optimize operation, in the first case (if a branching y-connection 8 is present in the main data lines 7H), the main connections 9H of the respective affected control units 5 are switched to the first operating mode B1. In the first operating mode B1, the control units 5 can continue to coordinate with each other through the respective software routine and determine which control unit 5 is authorized (or not authorized) to read the respective connected wheel speed sensor 3 and, as a result, switches the respective main connection 9H to active (passive).
[0046] For the additional connections 9Z of the respective control units 5, however, the second operating mode B2 is switched, as these do not require such coordination and can therefore remain permanently active. In an unbranched variant with two wheel speed sensors 3 per wheel 4 of the main axles H (not shown), the main connections 9H of the respective control units 5 can also be switched to the second operating mode B2 and thus permanently active. List of reference symbols (part of the description)
[0047] 1 Vehicle Brake system a Wheel brakes B Backup operation of the brake system 2 N Normal operation of the brake system 2 Wheel speed sensor Wheels of the vehicle 1 Control unit a Primary control unit b Secondary control unit A Exchange data line
[0048] 7H Main data line
[0049] 7Z additional data line
[0050] 8 y-connection
[0051] 9H main connection
[0052] 9aH Primary main connection
[0053] 9bH Secondary main connection
[0054] 9Z additional connection
[0055] 9aZ primary additional connection
[0056] 9bZ secondary additional connection
[0057] 20 axis modulator
[0058] 20a control cable
[0059] 40 Lift axle control
[0060] B1 first operating mode
[0061] B2 second operating mode
[0062] BS brake control signal
[0063] BSa primary brake control signal
[0064] BSb Secondary brake control signal
[0065] H main axis
[0066] Hv front main axis Hh rear main axis
[0067] L Lift axle
[0068] N4 Wheel speed
[0069] N4Soll Target wheel speed
[0070] S3 wheel speed signal
[0071] Z additional axis
[0072] Z1 first additional axis
[0073] Z2 second additional axis
[0074] ZS additional axis status
[0075] ZSL lift axle status
Claims
Patent claims. Braking system (2) for electronically controlled braking of wheels (4) on at least two main axles (H) of a vehicle (1) via wheel brakes (2a) of the braking system (2), wherein the braking system (2) comprises at least: - Wheel speed sensors (3) on the at least two main axles (H) and on at least one additional axle (Z) for outputting wheel speed signals (S3) depending on determined wheel speeds (N4) of the wheels (4) on the at least two main axles (H) and of the wheels (4) on the at least one additional axle (Z), and - at least two control units (5) for generating and outputting brake control signals (BS), wherein the wheel brakes (2a) on the at least two main axles (H) can be controlled depending on the brake control signals (BS), wherein the wheel speed sensors (3) on the at least two main axles (H) are connected to the at least two control units (5) via main data lines (7H) such that each control unit (5) can receive a determined wheel speed (N4) via the wheel speed signals (S3) for each wheel (4) on the at least two main axles (H) to which at least one wheel speed sensor (3) is assigned, and wherein each wheel speed sensor (3) on the at least one auxiliary axle (Z) is connected via an auxiliary data line (7Z) only to one of the at least two control units (5), and each control unit (5) is in turn connected to at least one of the wheel speed sensors (3) on the at least one auxiliary axle (Z).Brake system (2) according to claim 1, characterized in that the at least two control units (5) of the brake system (2) are formed by a primary control unit (5a) and a secondary control unit (5b), wherein the primary control unit (5a) is formed in one. The secondary control unit (5b) is configured to generate and output primary brake control signals (BSa) in normal operation (2N) of the brake system (2), and to generate and output secondary brake control signals (BSb) in a backup operation (2B) of the brake system (2) in which the primary control unit (5a) has failed, wherein the wheel brakes (2a) of the brake system (2) can be controlled in normal operation (2N) depending on the primary brake control signals (BSa) and in backup operation (2B) depending on the secondary brake control signals (BSb).Braking system (2) according to claim 1 or 2, characterized in that at least two auxiliary axles (Z) are provided in the braking system (2), wherein the wheel speed sensors (3) on the at least two auxiliary axles (Z) are evenly distributed among the at least two control units (5), for example such that each of the at least two control units (5) is connected via the auxiliary data lines (7Z) to the same number of wheel speed sensors (3) on the at least two auxiliary axles (Z), without any of the wheel speed sensors (3) on the at least one auxiliary axle (Z) being connected to more than one of the at least two control units (5).Braking system (2) according to one of the preceding claims, characterized in that the wheel speed sensors (3) assigned to the same auxiliary axle (Z) are connected to the same control unit (5) via the auxiliary data lines (7Z) for axle-wise distribution of the wheel speed sensors (3) to the at least two control units (5) and / or at least some of the wheel speed sensors (3) assigned to the same auxiliary axle (Z) are connected to different control units (5) via the auxiliary data lines (7Z) for wheel-wise distribution of at least some of the wheel speed sensors (3) to the at least two control units (5). Braking system (2) according to one of the preceding claims, characterized in that no wheel brakes (2a) are arranged on the at least one auxiliary axle (Z). Braking system (2) according to one of the preceding claims, characterized in that a wheel brake (2a) is assigned to each wheel (4) of the at least two main axles (H) for braking the wheels (4) of the at least two main axles (H) of the vehicle (1) wheel by wheel. Braking system (2) according to one of the preceding claims, characterized in that at least one of the control units (5) is configured to monitor an auxiliary axle status (ZS) depending on the wheel speed signals (S3) of the wheel speed sensors (3) on the at least one auxiliary axle (Z), wherein the auxiliary axle status (ZS) indicates whether the auxiliary axle (Z) is operating faultily or without fault.Braking system (2) according to claim 7, characterized in that the at least one additional axle (Z) is formed by a lift axle (L), wherein the lift axle (L) can be raised and lowered via a lift axle control unit (40), wherein at least one of the control units (5) is configured to monitor a lift axle status (ZSL) by validating the setting of the lift axle control unit (40) depending on the wheel speed signals (S3) output by the wheel speed sensors (3) on the lift axle (L). Braking system (2) according to claim 7 or 8, characterized in that at least one of the control units (5) is configured to check, depending on the wheel speed signals (S3) output by the wheel speed sensors (3) on the additional axle (Z), whether a wheel speed (N4) of the wheels (4) on the additional axle (Z) corresponds to a The brake system (2) according to one of the preceding claims is characterized in that the respective control unit (5) is configured to generate the brake control signals (BS) depending on the wheel speed signals (S3) of the wheel speed sensors (3) on the main axles (H). The brake system (2) according to one of the preceding claims is characterized in that the at least two control units (5) each have main connections (9H) for connecting a wheel speed sensor (3) to a main axle (H) and auxiliary connections (7Z) for connecting a wheel speed sensor (3) to an auxiliary axle (Z). The brake system (2) according to claim 11 is characterized in that - each wheel speed sensor (S3) that is connected to the respective control unit (5) via the main data line (7H) is connected to its own separate main connection (9H) of the respective control unit (5) and / or has its own separate main connection (9H) assigned to it on the respective control unit (5), and - Each wheel speed sensor (S3), which is connected to the respective control unit (5) via the auxiliary data line (7Z), is connected to its own separate auxiliary connection (9Z) of the respective control unit (5) and / or has its own separate auxiliary connection (9Z) on the respective control unit (5). Brake system (2) according to claim 11 or 12, characterized in that the main data lines (7H) each have a branching y-connection (8) such that a wheel speed sensor (3) arranged on the at least two main axes (H) is connected via the respective y-connection (8) and via the respective main connections (9H) to which at least two control units (5) are connected simultaneously. Braking system (2) according to claim 11 or 12, characterized in that a wheel speed sensor (3) arranged on the at least two main axles (H) is directly wired via the respective main data line (7H) to the respective control unit (5) via the respective main connection (9H), wherein each wheel (4) on the at least two main axles (H) is assigned two wheel speed sensors (3) and each of the two wheel speed sensors (3) of a wheel (4) is directly wired to another control unit (5) via the main data line (7H). Braking system (2) according to one of claims 11 to 14, characterized in that the at least two control units (5) are parameterizable and configured to switch between a first operating mode (B1) and a second operating mode (B2) for each main connection (9H) and for each auxiliary connection (9Z), wherein - is switched to the first operating mode (B1) when the respective main connection (9H) or auxiliary connection (9Z) of a control unit (5) is connected to a wheel speed sensor (3) via a y-connection (8), and - switches to the second operating mode (B2) when the respective main connection (9H) or auxiliary connection (9Z) of a control unit (5) is directly wired to a wheel speed sensor (3). Braking system (2) according to one of the preceding claims, characterized in that the at least two control units (5) are connected to each other via an exchange data line (7A) for exchanging the wheel speeds (N4), in particular the A method for operating a braking system (2) according to one of the preceding claims, wherein wheels (4) on at least two main axles (H) of a vehicle (1) can be braked via wheel brakes (2a) of the braking system (2), wherein brake control signals (BS) are generated and output by at least two control units (5) of the braking system (2), and the wheel brakes (2a) on the at least two main axles (H) are controlled depending on the output brake control signals (BS), wherein wheel speed signals (S3) are output by wheel speed sensors (3) on the at least two main axles (H) and on at least one further additional axle (Z) of the braking system (2), wherein the wheel speed signals (S3) are generated depending on determined wheel speeds (N4) of the wheels (4) on the at least two main axles (H) and of the wheels (4) on the at least one additional axle (Z).wherein each of the at least two control units (5) for each wheel (4) on the at least two main axles (H), to which at least one wheel speed sensor (3) is assigned, can receive a determined wheel speed (N4) via the output wheel speed signals (S3) and generate brake control signals (BS) depending on this, and each control unit (5) receives and processes the determined wheel speeds (N4) of at least one of the wheels (4) on the at least one auxiliary axle (Z) via the output wheel speed signals (S3), wherein simultaneously each determined wheel speed (N4) of a wheel (4) on the at least one auxiliary axle (Z) is received and processed by only one of the at least two control units (5). Method according to claim 17, characterized in that the at least two control units (5) are a primary control unit (5a) and a, secondary control unit (5b) are provided, wherein - in normal operation (2N) of the brake system (2) primary control unit (5a) generates and outputs primary brake control signals (BSa) depending on the received wheel speeds (N4) of the wheels (4) of the at least two main axles (H) and the wheel brakes (2a) on the at least two main axles (H) are controlled in normal operation (2N) depending on the output primary brake control signals (BSa), and - In backup mode (2B) of the brake system (2), secondary brake control signals (BSb) are generated and output by the secondary control unit (5b) depending on the received wheel speeds (N4) of the wheels (4) of the at least two main axles (H), and the wheel brakes (2a) on the at least two main axles (H) are controlled in backup mode (2B) depending on the output secondary brake control signals (BSb). Vehicle (1) with a brake system (2) according to one of claims 1 to 16.