REDUNDANT PLC SIGNALS EVALUATION

Abstract

The disclosure relates to a method for controlling an electronically controllable pneumatic braking system for a towing vehicle. The towing vehicle has front axle brake actuators and rear axle brake actuators; a primary system with a primary control unit for controlling the front and rear axle brake actuators; a secondary system with a secondary control unit for controlling the front and rear axle brake actuators in the event that a fault is detected in the primary system and the braking system is controlled by the secondary system; a trailer control valve for providing a trailer brake pressure at a trailer brake pressure port; and a PLC connector for receiving PLC signals from a trailer. The method includes: providing PLC signals received at the PLC connection both in the primary system and in the secondary system; and processing PLC signals in both the primary system and the secondary system.

Claims

1. A method for controlling an electronically controllable pneumatic braking system for a towing vehicle of a vehicle combination, wherein the electronically controllable pneumatic braking system includes a first front axle brake actuator and a second front axle brake actuator on a front axle of the towing vehicle and a first rear axle brake actuator and a second rear axle brake actuator on a rear axle of the towing vehicle; the electronically controllable pneumatic braking system further including a primary system and a secondary system, the primary system having a primary control unit at least for controlling the first front axle brake actuator, the second front axle brake actuator, the first rear axle brake actuator, and the second rear axle brake actuator, the secondary system having a secondary control unit at least for controlling the first front axle brake actuator, the second front axle brake actuator, the first rear axle brake actuator, and the second rear axle brake actuator in an event that a fault is detected in the primary system and the electronically controllable pneumatic braking system s controlled at least partially by the secondary system; the electronically controllable pneumatic braking system further including a trailer control valve and a PLC connection, the trailer control valve being configured to be controlled by the primary control unit to provide a trailer brake pressure at a trailer brake pressure port; and wherein the PLC connection is configured to receive PLC signals from a trailer of the vehicle combination; the method comprising: providing PLC signals received at the PLC connection in both the primary system and the secondary system; and, processing PLC signals in both the primary system and the secondary system.

2. The method as claimed in claim 1, wherein said processing the PLC signals in both the primary system and in the secondary system includes: processing the PLC signals in the primary control unit; and, processing the PLC signals in the secondary control unit.

3. The method of claim 1, wherein in an event that the primary system is in a fault-free state, the method further comprises: comparing PLC signals received in the primary system and secondary system.

4. The method of claim 1 further comprising providing the trailer brake pressure at the trailer brake pressure port by at least one of the primary system and the secondary system depending on the received PLC signals.

5. The method of claim 1, wherein the PLC signals include signals representing a trailer ABS status.

6. The method of claim 4, wherein in an event that an ABS function in the trailer is not available, a reliable modulation of the trailer brake pressure is carried out in at least one of the primary system and the secondary system and the reliably modulated trailer brake pressure is provided at the trailer brake pressure port.

7. The method of claim 1, wherein said processing the PLC signals, both in the primary system and in the secondary system, includes: receiving vehicle data via a vehicle bus at the primary system and the secondary system; and, combining the received PLC signals with the received vehicle data.

8. The method of claim 1, wherein in an event that the primary system is in a fault-free condition, the trailer brake pressure is provided by the primary system at the trailer brake pressure port; and, in the event that a fault is detected in the primary system, the trailer brake pressure is provided at the trailer brake pressure port as a trailer redundancy brake pressure by the secondary system.

9. The method of claim 8, wherein the trailer brake pressure provided by the primary system is partially or completely independent of a front axle brake pressure and a rear axle brake pressure; and, the trailer redundancy brake pressure provided by the secondary system is the front axle brake pressure or the rear axle brake pressure or a pressure derived therefrom.

10. An electronically controllable pneumatic braking system for a towing vehicle of a vehicle combination, the electronically controllable pneumatic braking system comprising: a first front axle brake actuator and a second front axle brake actuator on a front axle of the towing vehicle; a first rear axle brake actuator and a second rear axle brake actuator on a rear axle of the towing vehicle; a primary system having a primary control unit configured to control said first front axle brake actuator, said second front axle brake actuator, said first rear axle brake actuator, and said second rear axle brake actuator; a secondary system having a secondary control unit configured to control said first front axle brake actuator, said second front axle brake actuator, said first rear axle brake actuator, and said second rear axle brake actuator in an event that a fault is detected in said primary system and the electronically controllable pneumatic braking system is controlled at least partially by said secondary system; a trailer control valve configured to be controllable by said primary control unit to provide a trailer brake pressure at a trailer brake pressure port; a PLC connection for receiving PLC signals from a trailer of the vehicle combination; and, wherein both said primary system and said secondary system are configured to receive and process the PLC signals provided at said PLC connection.

11. The electronically controllable pneumatic braking system of claim 10, wherein said primary control unit and said secondary control unit are directly or indirectly connected to said PLC connection to receive the PLC signals from said PLC connection.

12. The electronically controllable pneumatic braking system of claim 11, wherein said primary control unit and said secondary control unit are connected to said PLC connection via a Y-cabling.

13. The electronically controllable pneumatic braking system of claim 10, wherein said primary control unit has a primary PLC chip configured to process the PLC signals and said secondary control unit has a secondary PLC chip configured to process the PLC signals.

14. The electronically controllable pneumatic braking system of claim 10, wherein said primary control unit and said secondary control unit are connected to each other via a data bus for exchanging information about processing of the PLC signals.

15. The electronically controllable pneumatic braking system of claim 10 further comprising: a rear axle modulator connected to at least a first compressed air supply or a second compressed air supply, said rear axle modulator being configured to control at least a rear axle brake pressure at said first rear axle brake actuator and said second rear axle brake actuator in dependence upon rear axle brake signals provided by said primary control unit; and, a front axle modulator connected to at least the first compressed air supply or the second compressed air supply, said front axle modulator being configured to control at least a front axle brake pressure at said first front axle brake actuator and said second front axle brake actuator in dependence upon at least one of front axle brake signals provided by said primary control unit and a pneumatic front axle control pressure.

16. The electronically controllable pneumatic braking system of claim 15, wherein in the event that a fault is detected in said primary system which causes that an adjustment by said primary control unit of the front axle brake pressure or the rear axle brake pressure cannot be carried out or cannot be carried out correctly, said secondary system is configured to redundantly control at least one of the front axle brake pressure and the rear axle brake pressure.

17. The electronically controllable pneumatic braking system of claim 16, wherein: said trailer control valve is connected to said primary control unit via an electrical signal line and is configured to receive trailer brake signals from said electrical signal line; said trailer control valve is further configured to provide the trailer brake pressure at the trailer brake pressure port in dependence upon the received trailer brake signals; said trailer control valve has a trailer redundancy port and is configured to redundantly control the trailer brake pressure in dependence upon a trailer redundancy control pressure provided at the trailer redundancy port; and, wherein the trailer redundancy control pressure is provided by said secondary control unit or a foot brake valve, or is a pressure derived from the pressure provided by said secondary control unit or provided by the foot brake valve.

18. The electronically controllable pneumatic braking system of claim 17, wherein said trailer redundancy port of the trailer control valve is preceded by a trailer ABS valve connected by a trailer ABS signal line to said secondary control unit and is configured to receive trailer ABS signals therefrom.

19. The electronically controllable pneumatic braking system of claim 16, wherein: said secondary control unit has a rear axle redundancy control port at which said secondary control unit is configured to control a rear axle redundancy control pressure in dependence upon received brake request signals; said secondary control unit further has a front axle redundancy control port at which said secondary control unit is configured to control a front axle redundancy control pressure in dependence upon received brake request signals; said rear axle modulator has a rear axle redundancy port for receiving the rear axle redundancy control pressure and is configured to redundantly control the rear axle brake pressure based on the received rear axle redundancy control pressure; and, said front axle modulator has a front axle redundancy port for receiving the front axle redundancy control pressure and is configured to redundantly control the front axle brake pressure based on the received front axle redundancy control pressure.

20. The electronically controllable pneumatic braking system of claim 11, wherein said primary control unit and said secondary control unit have a vehicle bus port via which said primary control unit and said secondary control unit are connected to at least one of a unit for autonomous driving and an active electronic steering device.

21. A commercial vehicle comprising: an electronically controllable pneumatic braking system having a first front axle brake actuator and a second front axle brake actuator on a front axle of the vehicle; said electronically controllable pneumatic braking system further having a first rear axle brake actuator and a second rear axle brake actuator on a rear axle of the vehicle; said electronically controllable pneumatic braking system including a primary system, a secondary system, a trailer control valve, and a PLC connection; said primary system having a primary control unit configured to control said first front axle brake actuator, said second front axle brake actuator, said first rear axle brake actuator, and said second rear axle brake actuator; said secondary system having a secondary control unit configured to control said first front axle brake actuator, said second front axle brake actuator, said first rear axle brake actuator, and said second rear axle brake actuator in an event that a fault is detected in said primary system and the electronically controllable pneumatic braking system is controlled at least partially by said secondary system; said trailer control valve being configured to be controllable by said primary control unit to provide a trailer brake pressure at a trailer brake pressure port; said PLC connection being configured to receive PLC signals from a trailer; wherein both said primary system and said secondary system are configured to receive and process PLC signals provided at said PLC connection; at least one of a unit for autonomous driving and an active electronic steering device; and, wherein said electronically controllable pneumatic braking system is configured to provide PLC signals received at said PLC connection in both said primary system and said secondary system, and, to process the PLC signals in both said primary system and said secondary system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The invention will now be described with reference to the drawings wherein:

[0039] FIG. 1 shows a schematic representation of a commercial vehicle with an electronically controllable pneumatic braking system in a first embodiment; and,

[0040] FIG. 2 shows a schematic representation of a commercial vehicle with an electronically controllable pneumatic braking system in a second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] A vehicle combination 1, which includes a towing vehicle 2 and a trailer 3, has an electronically controllable pneumatic braking system 4, which is provided in the towing vehicle 2. The towing vehicle 2 has a front axle VA, a first rear axle HA1 and a second rear axle HA2, which are collectively referred to as the rear axle HA, as they are controlled in the same way. The electronically controllable pneumatic braking system 4 includes a primary system 6 and a secondary system 8, which intervenes when a fault is detected in the primary system 6. A fault in the primary system 6 is in particular a fault that partially or completely prevents the control of a front axle brake pressure pBVA on the front axle VA and/or the control of a rear axle brake pressure pBHA on the rear axle HA. In this respect, the secondary system 8 intervenes in the event of redundancy and this can be described as a so-called fail-operational braking case.

[0042] The electronically controllable pneumatic braking system 4 also includes a rear axle brake circuit 10 and a front axle brake circuit 12. The rear axle brake circuit 10 is supplied by a first compressed air supply 14, while the front axle brake circuit 12 is supplied by a second compressed air supply 16. Both the first and the second compressed air supplies 14, 16 provide a supply pressure pV and are both supplied by an air treatment unit which is not shown here. Such an air treatment unit typically includes a multi-circuit protection valve as well as an air dryer. Although it is shown here that the electronically controllable pneumatic braking system 4 includes a rear axle brake circuit 10 and a front axle brake circuit 12, which are preferably separate circuits, a different division may also be provided, such as in particular a side-by-side division in the towing vehicle 2.

[0043] First and second rear axle brake actuators 18a, 18b are provided on the first rear axle HA1, and corresponding third and fourth rear axle brake actuators 18c, 18d are provided on the second rear axle HA2. If only one rear axle, for example the rear axle HA1, is provided, only first and second brake actuators 18a, 18b are provided on the rear axle HA. Likewise, the front axle VA is equipped with first and second front axle brake actuators 20a, 20b. Both the primary system 6 and the secondary system 8 use the first and second compressed air reservoirs 14, 16 and control the first and second and preferably third and fourth rear axle brake actuators 18a-18d and the first and second front axle brake actuators 20a, 20b, both by the primary system 6 in normal mode and in the case of redundancy by the secondary system 8.

[0044] To control the primary system 6, the electronically controllable pneumatic braking system 4 includes a primary control unit 22. The primary control unit 22 undertakes the task of a central control unit, as is basically known in electronically controllable pneumatic braking systems. The primary control unit 22 is supplied via a first power line 23 from a first voltage source 24. In addition, the primary control unit 22 is connected to a vehicle bus 25, via which it can receive data from a unit for autonomous driving 26, such as a target trajectory TSoll, a target deceleration ZSoll or other data, such as in particular vehicle data DF. The primary control unit 22 can then implement these data, as described in detail later. The primary control unit 22 also receives signals from an active electronic steering device 27 via the vehicle bus 25, such as in particular steering signals SL. These can also be implemented by the primary control unit 22.

[0045] Specifically, the primary control unit 22 controls a rear axle modulator 28, which is integrated into a module in the embodiment shown here together with the primary control unit 22. The primary control unit 22 also controls a front axle modulator 30. For this purpose, the primary control unit 22 is connected to the front axle modulator 30 via a first brake signal line 32. Both the rear axle modulator 28 and the front axle modulator 30 include one or more electromagnetically switchable valves and one or more relay valves or proportional valves. The rear axle modulator 28 or specifically the primary control unit 22 receives supply pressure pV from the first compressed air supply 14 and the front axle modulator 30 receives supply pressure pV from the second compressed air supply 16. Such a configuration is basically known and the exact configuration of front axle and rear axle modulators 30, 28 is also known. Typically, they included, for example, an electropneumatic input control unit with an inlet and outlet valve or a combined inlet/outlet valve and a relay valve. Via the first brake signal line 32, the primary control unit 22 provides front axle brake signals SBVA to the front axle modulator 30. On the one hand, these front axle brake signals SBVA can directly switch electropneumatic valves in the front axle modulator 30, which may then only have power amplifiers for this purpose. However, the front axle brake signals SBVA can also first be converted by intelligence in the form of an electronic control unit provided in the front axle modulator 30 and then provided to electromagnetic valves provided therein. Based on the reception of the front axle brake signals SBVA, the front axle brake pressure pBVA is then controlled by the front axle modulator 30. In a consistent manner, electromagnetic valves of the rear axle modulator 28 are switched by internal signals in the primary control unit 22 in order to control the rear axle brake pressure pBHA. Although four connections for the four rear axle brake actuators 18a-18d are shown in the embodiment shown, it should be understood that the rear axle modulator 28 can still be in single-channel or two-channel form. In the embodiment shown here, the rear axle modulator 28 has a two-channel configuration and controls the rear axle brake pressure pBHA side-appropriately and is thus already ABS-modulated. For this purpose, first to fourth rear axle revolution rate sensors 34a-34d are also provided on the first and second rear axle axles HA1, HA2, which sensors provide the first to fourth rear axle wheel revolution rate signals SDHA1-SDHA4 to the primary control unit 22. Also on the front axle VA, first and second front axle revolution rate sensors 35a, 35b are provided, which provide first and second front axle wheel revolution rate signals SDVA1, SDVA2 to the primary control unit 22. First and second ABS valves 36a, 36b are also provided on the front axle VA, which valves are connected to and switched by the primary control unit 22. In this respect, the front axle modulator 30 is configured here as a single-channel modulator and side-appropriate control of the front axle brake pressure pBVA is realized by the first and second ABS valves 36a, 36b. The corresponding switching signals for the first and second ABS valves 36a, 36b are provided by the primary control unit 22 during normal operation. In this way, the towing vehicle 2 can be operated completely autonomously during normal operation.

[0046] A trailer control valve 40 is provided for controlling the trailer 3. The trailer control valve 40 is supplied with electrical energy by the primary control unit 22. In other embodiments not shown here, the trailer control valve 40 can also be connected directly to the first voltage source or a second voltage source 42. The trailer control valve 40 receives trailer brake signals SBA from the primary control unit 22 via a second brake signal line 44, which can preferably be configured as a LIN-bus line. The trailer control valve 40 is connected here to both the first compressed air supply 14 and the second compressed air supply 16 and provides supply pressure pV via a trailer supply pressure port 45 and trailer brake pressure pBA via a trailer brake pressure port 46 depending on the trailer brake signal SBA controlled by the primary control unit 22. The trailer control valve 40 is coupled to the trailer 3 via the trailer supply pressure port 45 and the trailer brake pressure port 46. In addition, the electronically controllable pneumatic braking system includes a PLC connection (Power-Line Connection connection) 50, via which electrical energy and PLC signals SP can be provided to the trailer 3 and received from it. The PLC connection 50 is also connected to the primary control unit 22 via a first PLC line 52 and provides the received PLC signals SP to this. The primary control unit 22 has a PLC chip 53 for evaluating the PLC signals SP.

[0047] Such PLC signals SP include in particular information about the availability of an ABS system in the trailer 3 (not shown here) and may include further trailer-relevant information and data, such as in particular signals SPABS which represent the trailer ABS status SABS. Depending on these PLC signals SP, the primary control unit 22 can also adjust and vary the trailer brake signal SBA to cause braking of the trailer 3 based on the PLC signals SP.

[0048] The secondary system 8 includes a secondary control unit 60. The secondary control unit 60 is connected via a second power line 61 to one or the second voltage source 42, which is independent of the first voltage source 24. In this way, it can be ensured that in the event that the first voltage source 24 fails, and thus the primary control unit 22 fails, the secondary control unit 60 is still operational. The secondary control unit 60 has a vehicle bus port 65 and is also connected to the vehicle bus 25 via this and receives steering signals SL as well as target trajectories TSoll and target delays ZSoll and other vehicle data DF via the vehicle bus 25 from the unit for autonomous driving 26 and/or the active electronic steering device 27. In this embodiment, the secondary control unit 60 is also directly connected to the PLC connection 50 via a second PLC line 62. The first and second PLC lines 52, 62 are connected to the PLC connector 50 by Y-cabling, so that the PLC signals SP are provided directly at both the primary control unit 22 and the secondary control unit 60. The secondary control unit 60 is also connected to the primary control unit 22 via a bus connection 63, here a CAN-bus connection, so that the primary control unit 22 and the secondary control unit 60 can communicate with each other. Via this bus connection 63, a comparison of the PLC signals SP received at the primary control unit 22 and the secondary control unit 60 can also be carried out as well as a comparison of the processing of the PLC signals SP in the primary control unit 22 and the secondary control unit 60. In this embodiment, the secondary control unit 60 also includes a second PLC chip 64 to be able to process the PLC signals SP directly in the secondary control unit 60.

[0049] The secondary control unit 60 takes over the control of the braking system 4 in the event of a fault F. For example, a fault F can be indicated, for example, by an error signal SF of the primary control unit 22, or if the primary control unit 22 is deenergized, by a timeout signal ST which the secondary control unit 60 provides if it no longer receives signals or responses from the primary control unit 22 for a certain period of time.

[0050] The secondary control unit 60 is connected here to the second compressed air supply 16 but can also be alternatively or additionally connected to the first compressed air supply 14, or to a third compressed air supply which is not shown here. In the embodiment shown here, the secondary control unit 60 is not electrically or electronically connected to the front axle modulator 30 nor to the rear axle modulator 28. In addition, the secondary control unit 60 is not electronically connected to the trailer control valve 40. However, it could also be provided that such electronic lines are provided. In the embodiment shown here, the redundancy level, which is formed by the secondary system 8 and the secondary control unit 60, is of a purely pneumatic form.

[0051] In detail, the secondary control unit 60 has a rear axle redundancy control port 66, at which the secondary control unit 60 can control a rear axle redundancy control pressure pSRHA. It does this depending on the signals received via the vehicle bus. The rear axle redundancy control pressure pSRHA is then provided via a first changeover valve 68, which is configured as a select-high valve, to the primary control unit 22, which, depending on the received rear axle redundancy control pressure pSRHA, can redundantly control the rear axle brake pressure pBHA, which can then also be referred to as the rear axle redundancy brake pressure pRHA. This means that in the event that the secondary system 8 takes over the control, the rear axle brake pressure is controlled purely pneumatically by means of the primary control unit 22 or the rear axle modulator 28 integrated therein.

[0052] The secondary control unit 60 is also connected to the rear axle wheel revolution rate sensors 34a-34d via Y-cabling and can thus carry out slip control. The rear axle redundancy control pressure pSRHA can therefore preferably be provided slip-controlled by the secondary control unit 60.

[0053] In addition, the secondary control unit 60 has a front axle redundancy control port 69, at which the secondary control unit 60 can provide a front axle redundancy control pressure pSRVA. The front axle redundancy control pressure pSRVA is provided via a second changeover valve 70, which is configured as a select-high valve, to the front axle modulator 30, more precisely to a front axle redundancy port 72. There, the front axle redundancy control pressure pSRVA can, for example, act on a control surface of a relay valve, so that the front axle brake pressure pBVA can be redundantly controlled and can also be referred to as the front axle redundancy brake pressure pRVA. The ABS valves 36a, 36b on the front axle VA are also Y-cable connected to the secondary control unit 60, so that they can also be controlled in the event of redundancy, when the secondary control unit 60 takes over the control of the braking system 4. Likewise, the first and second front axle revolution rate sensors 35a, 35b are Y-cable connected to the secondary control unit 60. In the event of redundancy, slip-controlled control of the front axle brake pressure pBVA or the front axle redundancy brake pressure pRVA can also be carried out on the front axle.

[0054] In order to also be able to control the trailer control valve 40 in the event of redundancy, the trailer control valve 40 has a trailer redundancy port 74 and is configured to control the trailer brake pressure pBA or a redundant trailer brake pressure pBAR at the trailer brake pressure port 46 depending on a trailer redundancy control pressure pSRA provided at the trailer redundancy port 74. The trailer redundancy control pressure pSRA can also act on a control surface of a relay valve in the trailer control valve 40 in order to cause control of the trailer brake pressure pBA or the trailer redundancy brake pressure pBAR.

[0055] In the embodiment shown here, the trailer redundancy control pressure pSRA corresponds to the front axle redundancy control pressure pSRVA, since a trailer redundancy pressure line 76 branches from the front axle redundancy pressure line 77 downstream of the second changeover valve 70. However, it may also be provided in other embodiments that the secondary control unit 60 has its own connection for controlling the trailer redundancy control pressure pSRA in order to be able to control it in a trailer-appropriate manner. In the present embodiment, however, it is provided that the trailer 3 is controlled in accordance with the front axle VA.

[0056] Also shown in FIG. 1 is a foot brake valve 80, which has a first electrical output 81, a second electrical output 82 and a pneumatic output 83. The foot brake valve 80 is thus configured as a so-called 1P2E foot brake valve. The foot brake valve 80 provides an electric foot brake signal SBF at the first and second electrical outputs. The first electrical output 81 is connected here to the primary control unit 22, which accordingly receives the foot brake signal SBF. The second electrical output 82 of the foot brake valve 80 is connected to the secondary control unit 60, so that it also receives the foot brake signal SBF. The primary and secondary control units 22, 60 are configured to evaluate the foot brake signal SBF and, based on this, to control the front axle brake pressure pBVA, the rear axle brake pressure pBHA and the trailer brake pressure pBA in a corresponding manner or to request their control. This means that in the event that autonomous operation is not possible or not desired, and accordingly no brake requirement signals, target trajectories, or target decelerations are provided by the autonomous driving unit 26, the braking of the towing vehicle 2 can also be realized by means of the foot brake valve 80. A second redundancy level is also provided by means of the pneumatic output 83 of the foot brake valve 80. At the pneumatic output 83, the foot brake valve provides a pneumatic foot brake pressure pBF, which is provided in the embodiment shown here to both the first and the second changeover valves 68, 70. If this foot brake pressure pBF exceeds the rear axle redundancy control pressure pSRHA at the first changeover valve 68 or the front axle redundancy control pressure pSRVA at the second changeover valve 70, the corresponding foot brake pressure pBF is fed through and consequently provided at the primary control unit 22 or the rear axle modulator 28 and/or the front axle modulator 30 and in the embodiment shown here also via the trailer redundancy pressure line 46 to the trailer control valve 40. If the secondary control unit 60 also fails in addition to the primary control unit 22, purely pneumatic braking of the trailer 3 can still be applied and purely pneumatic braking of the trailer 3 can also be effected by means of the foot brake valve 80.

[0057] Not shown in FIG. 1 is a parking brake circuit, which is typically also provided in the towing vehicle 2. First to fourth parking brake actuators 84a-84d are also provided on the first and second rear axles HA1, HA2 for this purpose in addition to the first to fourth service brake actuators 18a-18d and are configured in particular as spring brake cylinders and are applied by means of a spring force. These parking brake actuators 84a-84d are applied when air is released and are released when air is supplied. A parking brake module which is not shown here is provided for applying air to and venting air from the parking brake actuators 84a-84d and can also be connected to the vehicle bus 25.

[0058] The embodiment shown in FIG. 2 is based on the embodiment shown in FIG. 1 and the same and similar elements are provided with the same reference characters. In this respect, full reference is made to the above description and in particular the differences from the first embodiment (FIG. 1) are described below.

[0059] A first significant difference in the second embodiment (FIG. 2) is that the trailer redundancy port 74 is preceded by a trailer ABS valve 86. The trailer ABS valve 86 is also used to enable control of the trailer 3 by means of the trailer redundancy control pressure pSRA, which is controlled by the secondary control unit 60 or whose control is caused by the secondary control unit 60, in the case of pneumatic control of the trailer 3. The trailer ABS valve 86 is connected to and controlled by the secondary control unit 60 via a trailer ABS line 87. The secondary control unit 60 can determine the availability of an ABS system in the trailer 3 from the PLC data SP. The secondary control unit 60 can preferably also be configured to read the availability of the trailer ABS system of the trailer 3 from the PLC data SP and in a corresponding manner to control the trailer ABS valve 86 by means of trailer ABS signals SABSS so that the trailer redundancy control pressure pSRA is provided in a pulsed form if necessary at the trailer control valve 40 to operate the service brake actuators in the trailer 3 in a pulsed manner.

[0060] Another difference in the second embodiment shown in FIG. 2 is that first and second rear axle ABS valves 88a, 88b are also provided on the first and second rear axles. These are used in particular to brake the rear axles HA1, HA2 under slip control in the redundancy mode, that is, when the secondary system 8 with the secondary control unit 60 takes over the control. During normal operation, the primary control unit 22 can preferably be configured to control the rear axle brake pressure pBHA in a side-appropriate and slip-controlled manner. In this respect, ABS valves and ABS power amplifiers can be integrated into the primary control unit 22. In the embodiment shown in FIG. 2, preferably no ABS valves are provided in the primary control unit 22. Rather, these are formed externally of the primary control unit 22 by the first and second rear axle ABS valves 88a, 88b, so that the rear axle ABS valves 88a, 88b can be controlled independently of both the primary control unit 22 and the secondary control unit 60. Thus, even in the redundancy mode, slip-controlled control of the rear axles HA1, HA2 by the secondary system 6 is possible.

[0061] It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.

REFERENCE CHARACTER LIST (PART OF THE DESCRIPTION)

[0062] 1 Vehicle combination [0063] 2 Towing vehicle [0064] 3 Trailer [0065] 4 Electronically controllable pneumatic braking system [0066] 6 Primary system [0067] 8 Secondary system [0068] 10 Rear axle braking circuit [0069] 12 Front axle braking circuit [0070] 14 First compressed air supply [0071] 16 Second compressed air supply [0072] 18a First rear axle brake actuator [0073] 18b Second rear axle brake actuator [0074] 18c Third rear axle brake actuator [0075] 18d Fourth rear axle brake actuator [0076] 20a First front axle brake actuator [0077] 20b Second front axle brake actuator [0078] 22 Primary control unit [0079] 23 First power line [0080] 24 First voltage source [0081] 25 Vehicle bus [0082] 26 Unit for autonomous driving [0083] 27 Active electronic steering device [0084] 28 Rear axle modulator [0085] 30 Front axle modulator [0086] 32 First brake signal line [0087] 34a First rear axle wheel revolution rate sensor [0088] 34b Second rear axle wheel revolution rate sensor [0089] 34c Third rear axle wheel revolution rate sensor [0090] 34d Fourth rear axle wheel revolution rate sensor [0091] 35a First front axle wheel revolution rate sensor [0092] 35b Second front axle wheel revolution rate sensor [0093] 36a First ABS valve [0094] 36b Second ABS valve [0095] 40 Trailer control valve [0096] 42 Second voltage source [0097] 44 Second brake signal line [0098] 45 Trailer supply pressure port [0099] 46 Trailer brake pressure port [0100] 50 PLC connection [0101] 52 First PLC line [0102] 53 First PLC chip [0103] 60 Secondary control unit [0104] 61 Second power line [0105] 62 Second PLC line [0106] 63 Bus connection [0107] 64 Second PLC chip [0108] 65 Vehicle bus port of the secondary control unit [0109] 66 Rear axle redundancy control port [0110] 68 First changeover valve [0111] 69 Front axle redundancy control port [0112] 70 Second changeover valve [0113] 72 Front axle redundancy port [0114] 74 Trailer redundancy port [0115] 76 Trailer redundancy pressure line [0116] 77 Front axle redundancy pressure line [0117] 80 Foot brake valve [0118] 81 First electrical output [0119] 82 Second electrical output [0120] 83 Pneumatic output [0121] 84a First parking brake actuator [0122] 84b Second parking brake actuator [0123] 84c Third parking brake actuator [0124] 84d Fourth parking brake actuator [0125] 86 Trailer ABS valve [0126] 87 Trailer ABS line [0127] 88a First rear axle ABS valve [0128] 88b Second rear axle ABS valve [0129] DF Vehicle data [0130] F Fault [0131] HA1 First rear axle [0132] HA2 Second rear axle [0133] ISP Information about the processing of PLC signals [0134] pBA Trailer brake pressure [0135] pBF Foot brake pressure [0136] pBHA Rear axle brake pressure [0137] pBVA Front axle brake pressure [0138] pRHA Rear axle redundancy brake pressure [0139] pRVA Front axle redundancy brake pressure [0140] pRHA Rear axle redundancy brake pressure [0141] pSRA Trailer redundancy control pressure [0142] pSRHA Rear axle redundancy control pressure [0143] pSRVA Front axle redundancy control pressure [0144] pV Supply pressure [0145] SABS Trailer ABS Status [0146] SABSS Trailer ABS Signals [0147] SBA Trailer brake signals [0148] SBHA Rear axle brake signals [0149] SBVA Front axle brake signals [0150] SDHA1 First rear axle wheel revolution rate signal [0151] SDHA2 Second rear axle wheel revolution rate signal [0152] SDHA3 Third rear axle wheel revolution rate signal [0153] SDHA4 Fourth rear axle wheel revolution rate signal [0154] SDVA1 First front axle wheel revolution rate signal [0155] SDVA2 Second front axle wheel revolution rate signal [0156] SF Error signal [0157] SL Steering signals [0158] SP PLC Signals [0159] SPABS Signals indicating a trailer ABS status [0160] TS Timeout signal [0161] TSoll Target trajectory [0162] VA Front axle [0163] ZSoll Target deceleration