Redundant braking system and trailer vehicle

Abstract

The invention relates to a redundant braking system (10) with electropneumatic control of service brakes (14-17) for a trailer vehicle, said braking system comprising a first brake circuit (V1, EBS) and a first electropneumatic brake system (EBS, M1) which has a first electronic control unit (EBS) and a first brake modulator (M1) and processes signals from wheel speed sensors (27, 29). Furthermore, the braking system (10) comprises a second brake circuit (V2, VCU) and a second electropneumatic brake system (VCU, M2; VCU, M2a, M2b) which has a second electronic control unit (VCU) and at least one second brake modulator (M2; M2a, M2b) and processes signals from wheel speed sensors (26, 28). In the event of a failure of the first electropneumatic brake system (EBS, M1), the second electropneumatic brake system (VCU, M2; VCU, M2a, M2b) controls the service brakes (14-17) with brake pressure.

Description

[0001] Redundant braking system and trailer

[0002] Description

[0003] The invention relates to a redundant braking system with electropneumatic control of service brakes and a trailer vehicle.

[0004] Modern trailers with electropneumatic braking systems, preferably with multiple axles, feature an electronic control system and a brake modulator. The electronic control system receives an electronic brake signal from a towing vehicle via a trailer interface and controls solenoid valves in the brake modulator to output brake pressure. The brake pressure is applied to the service brakes in the trailer. The electronic control system and brake modulator also perform anti-lock braking and other special braking functions to maintain driving stability. For this purpose, signals from wheel speed sensors and, if necessary, other sensors are processed.

[0005] For autonomous driving, particularly at Level 4 on motorways, trailers and towing vehicles must meet certain safety requirements. If the electronic braking system in the trailer fails, the anti-lock braking system and other functions are no longer available without additional measures. The towing vehicle may no longer drive with the trailer and must wait at the side of the road until repairs can be carried out. A fully redundant braking system in the trailer is required so that if the electronic braking system fails, the service brakes can still be applied and the anti-lock braking system can be implemented to ensure driving stability. WO 2020 / 225168 A1 discloses a braking system for a trailer. Two brake circuits are connected to a modulator device with electronic control. Another electronic control system controls valve devices for regulating brake pressure.

[0006] The object of the present invention is to create a redundant braking system.

[0007] A redundant brake system according to the invention with electropneumatic control of service brakes for a trailer vehicle has the features of claim 1, namely a first brake circuit and a first electropneumatic brake system, which has a first electronic control and a first brake modulator and processes signals from wheel speed sensors, a second brake circuit and a second electropneumatic brake system, which has a second electronic control and at least one second brake modulator and processes signals from wheel speed sensors, wherein in the event of failure of the first electropneumatic brake system, the second electropneumatic brake system controls the service brakes with brake pressure.

[0008] The first brake circuit and the second brake circuit preferably each have their own compressed air supply. Advantageously, only the first electropneumatic brake system is connected to a pneumatic control line with a corresponding coupling head (yellow) for connection to the towing vehicle. The second electropneumatic brake system is part of the second brake circuit. However, any control pressure provided by the towing vehicle is preferably not utilized.

[0009] Optionally and according to the invention, at least one of the following features can be provided: a) the first electropneumatic braking system is connected to a first interface via which an electronic braking signal and a supply voltage are transmitted from a towing vehicle, b) the second electropneumatic braking system is connected to a second interface via which the electronic braking signal and a supply voltage are transmitted from the towing vehicle.

[0010] By connecting the two braking systems to two different interfaces, the redundancy of the braking system can be further improved.

[0011] Optionally and according to the invention, at least one of the following features can be provided: a) the first interface is a plug connection according to ISO 7638, in particular in the version from 2018, b) the second interface is a 1000Base-T interface, in particular according to ISO 23870.

[0012] The interface according to ISO 7638 includes, among other things, a power supply and data transmission via a CAN bus. The interface according to the new ISO 23870 includes, among other things, high-speed data transmission, also via CAN bus, and a power supply.

[0013] Preferably, the first electronic control is connected to the interface according to ISO 7638 and the second electronic control is connected to the interface according to ISO 23870.

[0014] Optionally, and according to the invention, the first electronic control is connected to the second electronic control via a signal line. Depending on signals on the signal line, the second electronic control assumes a failure of the first electropneumatic braking system. In this case, the second electronic control takes over the control of the service brakes with brake pressure. The signals transmitted from the first electronic control to the second electronic control can be different. For example, the first electronic control itself can detect an error and transmit a corresponding error signal. Additionally or alternatively, the first electronic control continuously and / or cyclically transmits a defined signal to indicate its own operating status.If the signal is absent within a defined period of time, the second electronic control assumes a failure of the first electropneumatic braking system. Optionally, and according to the invention, the first electronic control is connected to the second electronic control via an electrical line, specifically for the bidirectional transmission of a supply voltage. This increases redundancy with regard to the provision of the supply voltage via the first and second interfaces.

[0015] Optionally, and in accordance with the invention, the first brake modulator controls the brake pressure via at least two channels via brake pressure connections. This allows the left and right sides of the vehicle to be controlled separately.

[0016] Optionally, and according to the invention, the at least one second brake modulator comprises a brake pressure sensor connected to the second electronic control unit. This allows for a high level of integration while simultaneously fully controlling or actuating the service brakes. The brake pressure sensor can be a pressure transducer (p / U).

[0017] Optionally and inventively, the second electropneumatic braking system has two second brake modulators, one for each side of the vehicle. This allows separate control of each side of the vehicle.

[0018] Optionally and inventively, the second brake modulators are designed with a brake pressure port, a vent port, a supply pressure port, and a control pressure port. Such relay valves, in particular, are cost-effective standard components for vehicle brakes.

[0019] Optionally and inventively, the brake system has the following features: the vent ports of the second brake modulators are connected to brake pressure ports of the first brake modulator; the supply pressure ports and control pressure ports of the second brake modulators are connected to a supply pressure of the second brake circuit; the brake pressure ports of the second brake modulators are connected to the service brakes; the second brake modulators are electrically controlled by the second electronic control system. As a result, the second brake modulator vents via the first brake modulator. This is possible because the first brake modulator vents its brake pressure port in the event of a power failure. The second brake modulator receives the supply pressure of the second brake circuit at its control pressure port.Through appropriately timed valve actuation in the second brake modulator, the supply pressure is converted into a control pressure, which reduces the supply pressure at the supply pressure port to the brake pressure at the brake pressure port. Electronic control is provided directly by the second electronic control unit.

[0020] Optionally and inventively, the brake system has the following features: the supply pressure connections and control pressure connections of the second brake modulators are connected to a supply pressure of the second brake circuit, the brake pressure connections of the second brake modulators are connected to brake pressure connections of the first brake modulator via double check valves, the double check valves are connected to the service brakes, the second brake modulators are electrically controlled by the second electronic control.

[0021] The double check valves are also called OR valves. The double check valves are connected so that the higher brake pressure from the first and second brake modulators is passed to the respective service brake.

[0022] Optionally and according to the invention, the brake system has the following features: the supply pressure connections and control pressure connections of the second brake modulators are connected to a supply pressure of the second brake circuit, the brake pressure connections of the second brake modulators and the brake pressure connections of the first brake modulator are connected to common solenoid valves, wherein the solenoid valves selectively allow the brake pressure of the first brake modulator or the second brake modulators to pass to the service brakes, the solenoid valves are connected to the service brakes, the solenoid valves and the second brake modulators are electrically controlled by the second electronic control.

[0023] In particular, the control can be such that the solenoid valves are normally de-energized, and the service brakes receive the brake pressure from the first brake modulator. If the first electropneumatic brake system fails, in the event of a fault, the second electronic control unit then controls the solenoid valves, so that the brake pressure from the second brake modulators can then be transferred to the service brakes.

[0024] Optionally, and according to the invention, the second electropneumatic braking system has a common second brake modulator for both sides of the vehicle. This simplifies the design effort. The service brakes are then controlled by the second electropneumatic braking system via only one channel.

[0025] Optionally and in accordance with the invention, the second brake modulator is designed with a brake pressure port, a vent port, a supply pressure port, and a control pressure port. In particular, the second brake modulator includes a relay valve.

[0026] Optionally and according to the invention, the braking system has the following features:

[0027] The supply pressure connection and control pressure connection of the second brake modulator are connected to a supply pressure of the second brake circuit, the brake pressure connection of the second brake modulator is connected to brake pressure connections of the first brake modulator via parallel double check valves, the double check valves are connected to the service brakes, the second brake modulator is electrically controlled by the second electronic control system.

[0028] The double check valves are also called OR valves. The higher brake pressure from the first and second brake modulators is applied to the service brakes.

[0029] Optionally and according to the invention, the brake system has the following features: the supply pressure connection and the control pressure connection of the second brake modulator are connected to a supply pressure of the second brake circuit, the brake pressure connection of the second brake modulator is connected via parallel solenoid valves and the brake pressure connections of the first brake modulator are connected to common solenoid valves, wherein the solenoid valves selectively allow the brake pressure of the first brake modulator or the second brake modulator to pass to the service brakes, the solenoid valves are connected to the service brakes, the solenoid valves and the second brake modulator are electrically controlled by the second electronic control.

[0030] If the solenoid valves are de-energized, the brake pressure connections of the first brake modulator are connected to the service brakes, otherwise the brake pressure connection of the second brake modulator is connected.

[0031] Finally, the invention also relates to a trailer vehicle with a braking system according to one of claims 1-16.

[0032] Further features of the invention can be found in the further description and the patent claims. Advantageous embodiments are explained in more detail below with reference to the drawings. They show:

[0033] Fig. 1 shows a simplified electropneumatic circuit diagram of a braking system in a trailer vehicle as a first embodiment,

[0034] Fig. 2 is a circuit diagram of a brake system as a second embodiment, Fig. 3 is a circuit diagram of a brake system as a third embodiment, Fig. 4 is a circuit diagram of a brake system as a fourth embodiment, Fig. 5 is a circuit diagram of a brake system as a fifth embodiment.

[0035] A braking system 10 according to Fig. 1 is provided for a trailer vehicle 11 with two or more axles 12, 13. The braking system 10 includes a first braking circuit with a supply V1, a second braking circuit with a supply V2, and a third braking circuit with a supply VS for an air suspension (not shown). The first braking circuit includes a first electro-pneumatic braking system with a first electronic control system EBS and a first brake modulator M1 for transferring braking pressure to service brakes 14, 15 on a right-hand side of the vehicle and service brakes 16, 17 on a left-hand side of the vehicle. Furthermore, spring-loaded brakes 18-21 are supplied with spring-loaded pressure via the first brake modulator M1.

[0036] In addition to the supply V2, the second brake circuit includes a second electropneumatic braking system with a second electronic control unit (VCU) and two second brake modulators (M2a, M2b) for the right side of the vehicle and two second brake modulators (M2a, M2b) for the left side. The second brake modulators (M2a, M2b) can also supply brake pressure to service brakes 14-17.

[0037] Wheels 22, 23, 24, 25 of axles 12, 13 are each assigned a wheel speed sensor 26, 27, 28, 29. The wheel speed sensors 26, 28 of the front wheels 22, 24 are connected to the second electronic control unit VCU, and the wheel speed sensors 27, 29 of the rear wheels 23, 25 are connected to the first electronic control unit EBS; see electrical lines L1, L2, L3, L4.

[0038] The first electronic control unit (EBS) is combined with the first brake modulator M1 to form a modulator device. The modulator device is a standard electropneumatic component. Control software in the first electronic control unit (EBS) can be customized.

[0039] The second electronic control unit (VCU) is a vehicle control unit that additionally performs brake control as required, and whose software is adapted accordingly. The second electronic control unit (VCU) is connected to a trailer interface (SG), which can be configured here in particular as a Gigabit Ethernet interface, particularly a 1000Base-T interface. Data is transmitted from the towing vehicle to the trailer via this high-speed interface, including via a CAN bus, as well as a supply voltage. The second electronic control unit (VCU) has various inputs and outputs for voltage, data, and signals, also referred to as electrical connections. These are shown in Figs. 1, 2, and 5:

[0040] At the top of the VCU from left to right:

[0041] Pressure signal supply second brake circuit,

[0042] Signal wheel speed sensor,

[0043] Pressure signal spring pressure,

[0044] Voltage bidirectional,

[0045] CAN bus.

[0046] On the left edge from top to bottom:

[0047] supply voltage,

[0048] Supply voltage, 1000Base-T1 - 1 , 1000Base-T1 - 2,

[0049] At the bottom from left to right:

[0050] Pressure signal supply pressure coupling head,

[0051] Signal wheel speed sensor,

[0052] Electric parking brake control,

[0053] Control of electric brake pressure.

[0054] In Figs. 3 and 4, at the bottom edge of the VCU, to the left of the other four connections, there is an additional connection for controlling solenoid valves 40a, 40b, the function of which is explained below in connection with Figs. 3 and 4.

[0055] Another trailer interface SH is designed according to ISO 7368 and transmits, among other things, data via a CAN bus and a supply voltage to the first electronic control unit EBS, see electrical line L5.

[0056] During normal, fault-free operation, the reservoirs V1 and V2 are filled via a red coupling head 30 and a valve assembly 31. The latter prevents, among other things, backflow from the reservoirs V1 and V2 to the coupling head 30, for example, if a pneumatic supply line between the towing vehicle and the trailer 11 breaks. A yellow coupling head 32 is connected to the first electropneumatic braking system (EBS with M1) for the transmission of control pressure.

[0057] A braking request is sent to the first electronic control unit (EBS) via the trailer interface SH. The first brake modulator M1 then outputs a brake pressure via two channels, via brake pressure ports 33a, 33b, to a brake pressure port 34a of the second brake module M2a and to the brake pressure port 34b of the second brake module M2b. Under normal fault conditions, the two brake modules M2a and M2b are connected so that the brake pressure is passed from the brake pressure ports 34a, 34b as inputs and via brake pressure ports 35a, 35b as outputs to the service brakes 14-17.

[0058] In the event of a fault, such as the failure of the first electronic control unit (EBS), the second electronic control unit (VCU) takes over control of the service brakes 14-17. The towing vehicle always sends the braking request via the SG interface. The second electronic control unit controls the second brake modulators M2a, M2b according to the braking request (see line L6), so that a supply pressure from the supply V2 present at control pressure ports 36a, 36b is converted into a control pressure. The brake modulators M2a, M2b contain relay valves (not shown in detail). In these, the control pressure modulates a supply pressure from the supply V2 present at supply pressure ports 37a, 37b to create braking pressures. The braking pressures are delivered to the service brakes 14-17 via the brake pressure ports 35a, 35b.

[0059] For better understanding, the pneumatic connections of the second brake modulator M2a are marked with the numbers usual for pneumatic valves:

[0060] 1 reservoir pressure

[0061] 2 Working pressure (here double)

[0062] 3 Ventilation

[0063] 4 Control input The two brake pressure ports 35a are the ports for working pressure 2. In this case, brake pressure port 34a is the port for venting 3. Control input 4 and supply pressure 1 are connected to the supply V2 of the second brake circuit as control pressure port 36a and supply pressure port 37a, respectively. The ports of the second brake modulator M2b are mirror images of the ports of the second brake modulator M2a.

[0064] The second brake modulators M2a, M2b contain pressure transducers DBa, DBb for sensing the respective brake pressure output and are designed to enable the usual and legally prescribed braking processes, including anti-lock braking and vehicle stability control. The second electronic control unit (VCU) is equipped with appropriate software for this purpose.

[0065] Another pressure transducer D1 detects the pneumatic supply pressure applied to the red coupling head 30 and provides a corresponding pressure value to the second electronic control unit VCU. Another pressure transducer D2 detects the supply pressure provided by the supply V2 and provides a corresponding pressure value to the second electronic control unit VCU. Finally, another pressure transducer DF detects a spring-loaded brake pressure in the spring-loaded brake 18 and provides a corresponding pressure value to the second electronic control unit VCU. The two electronic control units EBS and VCU are connected to each other via data lines and exchange the available data. Instructions, status information, and other data can also be exchanged via these lines.

[0066] The first brake modulator M1 is typically connected to an electronic parking brake (EPB), which is electronically controlled by the second electronic control unit (VCU). A parking release valve (PLV) is arranged upstream of the electronic parking brake (EPB), which can be manually actuated, for example, to release the spring-loaded brakes 18-21, as long as the supply V1 or supply V2 can still supply sufficient pressure. Switching from the first electronic control unit (EBS) to the second electronic control unit (VCU) in the event of a fault can, for example, be performed based on status information. The electronic control unit (EBS) cyclically sends defined status information to the second electronic control unit (VCU) via line L7.If the status information is missing or if an error status is transmitted, the second electronic control unit (VCU) detects an error on the part of the first electronic control unit (EBS) and takes over control of the service brakes 14-17, as previously described. At the same time, as a precautionary measure, the second electronic control unit (VCU) can send an instruction to the first electronic control unit (EBS) to deactivate the first electronic control unit (EBS) or to transition to an inactivity mode. Solenoid valves present in the first brake modulator M1 should no longer be controlled or energized by the first electronic control unit (EBS). As a result, the brake pressure connections 33a, 33b are connected to a vent 38 on the first brake modulator M1.

[0067] To achieve redundancy of the power supply, the electronic controls VCU and EBS are connected to each other via a live line L8.

[0068] In the embodiment shown in Fig. 2, the brake pressure ports 33a, 33b are not connected to the second brake modulators M2a, M2b, but instead each lead to a double check valve 39a, 39b. Likewise, the brake pressure ports 35a, 35b are connected to the double check valves 39a, 39b. The brake pressure ports 34a, 34b are provided here as vents.

[0069] During normal operation, the brake pressure from the first brake modulator M1 flows to the service brakes 14-17 via the double check valves 39a, 39b. The brake pressure ports 35a, 35b are then depressurized.

[0070] In the event of a fault, the brake pressure ports 33a, 33b are depressurized, and brake pressure flows from the second brake modulators M2a, M2b via the double check valves 39a, 39b to the service brakes 14-17. The double check valves 39a, 39b are also referred to as OR valves and pass the higher pressure of the two inputs to the output. In the third embodiment according to Fig. 3, the solenoid valves 40a, 40b are provided instead of the double check valves 39a, 39b shown in the second embodiment. These are de-energized, especially under normal conditions, and allow the brake pressure to flow from the brake pressure ports 33a, 33b to the service brakes 14-17. In the event of a fault, the solenoid valves 40a, 40b are controlled by the second electronic control unit VCU and go into a switching state in which the brake pressure at the brake pressure connections 35a, 35b can be transferred to the service brakes 14-17.The switching logic of the solenoid valves 40a, 40b can also be provided in reverse, namely de-energized in the event of a fault and energized in the normal case.

[0071] In the fourth embodiment, only a second brake modulator M2 is provided, whose brake pressure connection 35 leads to the solenoid valves 40a, 40b analogously to the third embodiment. The third and fourth embodiments therefore differ only in the number of channels when braking via the second electronic control unit VCU.

[0072] In the fifth embodiment shown in Fig. 5, only the single second brake modulator M2 is provided. Its brake pressure port 35 is connected to the double check valves 39a, 39b, similarly to the second embodiment. The second and fifth embodiments therefore also differ only in the number of channels when braking via the second electronic control unit (VCU).

[0073] The first brake modulator M1 features an emergency braking function and overload protection. The overload protection prevents the braking forces from accumulating when the service brakes 14-17 are actuated while the spring-loaded brakes 18-21 are simultaneously applied.

[0074] The second brake modulators M2, M2a, M2b are designed as relay valves with the following properties:

[0075] The supply pressure port 1, 37 has a large nominal diameter, allowing the brake cylinders of the service brakes 14-17 (not shown) to be quickly ventilated. The control pressure port 4, 36 is also connected to the supply pressure from supply V2. Internally, pulsed solenoid valves generate a control pressure from the pressure at the control pressure port 4, 36.

[0076] In the embodiment shown in Fig. 1, the service brakes 14-17 are always vented via the vent ports 34, 34a, 34b, the brake pressure ports 33a, 33b, and the vent 38, normally with the modulator M1 active and in the event of a fault with the modulator M2, M2a, M2b active. In the embodiment shown in Figs. 2 and 5, the venting normally occurs via the double check valves 39a, 39b and the vents 38, 34, 34a, 34b, depending on the pressure conditions in the double check valves 39a, 39b, and also in the event of a fault. In the embodiments of Figures 3 and 4, venting normally takes place via the solenoid valves 40a, 40b and the vent 38, and in the event of a fault via the solenoid valves 40a, 40b and the vent connections 3, 34, 34a, 34b.

[0077]

[0078] Brake system trailer axle

[0079] axis

[0080] Service brake Service brake Service brake Service brake Spring brake Spring brake Spring brake Spring brake Spring brake Wheel Wheel Wheel Wheel

[0081] Wheel speed sensor Wheel speed sensor Wheel speed sensor Wheel speed sensor red coupling head Valve assembly yellow coupling head a Brake pressure connection b Brake pressure connection Bleed connection a Bleed connection b Bleed connection

[0082] Brake pressure connection a Brake pressure connection b Brake pressure connection 36 Control pressure connection

[0083] 36a Control pressure connection

[0084] 36b Control pressure connection

[0085] 37 Supply pressure connection

[0086] 37a Supply pressure connection

[0087] 37b Supply pressure connection

[0088] 38 Ventilation

[0089] 39a Double check valve

[0090] 39b Double check valve

[0091] 40a solenoid valve

[0092] 40b Solenoid valve

[0093] D1 pressure transducer (pressure sensor)

[0094] D2 pressure transducer (pressure sensor)

[0095] DB pressure transducer (pressure sensor)

[0096] DBa pressure transducer (pressure sensor)

[0097] DBb pressure transducer (pressure sensor)

[0098] DF pressure transducer (pressure sensor)

[0099] EBS first electronic control

[0100] EPB electronic parking brake

[0101] L1 electrical line

[0102] L2 electrical line

[0103] L3 electrical line

[0104] L4 electrical line

[0105] L5 electrical cable

[0106] L6 electrical cable

[0107] L7 electrical cable

[0108] L8 electrical cable

[0109] M1 first brake modulator

[0110] M2 second brake modulator

[0111] M2a second brake modulator

[0112] M2b second brake modulator

[0113] PLV parking release valve

[0114] SH first interface

[0115] SG second interface V1 supply first brake circuit

[0116] V2 supply second brake circuit

[0117] VS stock air suspension

[0118] VCU second electronic control

Claims

Patent claims 1. Redundant braking system (10) with electro-pneumatic control of service brakes (14-17) for a trailer vehicle (11), with - a first brake circuit (V1, EBS) and a first electropneumatic brake system (EBS, M1), which has a first electronic control (EBS) and a first brake modulator (M1) and processes signals from wheel speed sensors (27, 29), - a second brake circuit (V2, VCU) and a second electropneumatic brake system (VCU, M2; VCU, M2a, M2b), which has a second electronic control (VCU) and at least one second brake modulator (M2; M2a, M2b) and processes signals from wheel speed sensors (26, 28), - wherein, in the event of failure of the first electropneumatic braking system (EBS, M1), the second electropneumatic braking system (VCU, M2; VCU, M2a, M2b) controls the service brakes (14-17) with brake pressure.

2. Brake system (10) according to claim 1, characterized by at least one of the following features: a) the first electropneumatic brake system (EBS, M1) is connected to a first interface (SH) via which an electronic brake signal and a supply voltage are transmitted, b) the second electropneumatic brake system (VCU, M2; VCU, M2a, M2b) is connected to a second interface (SG) via which the electronic brake signal and a supply voltage are transmitted.

3. Brake system (10) according to claim 2, characterized by at least one of the following features: a) the first interface (SH) is a plug connection according to ISO 7638, b) the second interface (SG) is a 1000Base-T interface.

4. Brake system (10) according to one of the preceding claims, characterized in that the first electronic control (EBS) is connected to the second electronic control (VCU) via a signal line (L7) and that the second electronic control unit (VCU) assumes a failure of the first electro-pneumatic braking system (EBS, M1) depending on signals on the signal line (L7) 5. Brake system (10) according to one of the preceding claims, characterized in that the first electronic control (EBS) is connected to the second electronic control (VCU) via an electrical line (L8), namely for the bidirectional transmission of a supply voltage.

6. Brake system (10) according to one of the preceding claims, characterized in that the first brake modulator (M1) controls brake pressure via at least two channels via brake pressure connections (33a, 33b).

7. Brake system (10) according to one of the preceding claims, characterized in that the at least one second brake modulator (M2; M2a, M2b) has a brake pressure sensor (DB; DBa, DBb) which is connected to the second electronic control unit (VCU).

8. Brake system (10) according to one of the preceding claims, characterized in that the second electropneumatic brake system (VCU, M2a, M2b) has two second brake modulators (M2a, M2b), namely one for each side of the vehicle.

9. Brake system (10) according to one of the preceding claims, characterized in that the second brake modulators (M2a, M2b) are designed with a brake pressure connection (2; 35a, 35b), a venting connection (3; 34a, 34b), a supply pressure connection (1; 37a, 37b) and a control pressure connection (4; 36a, 36b).

10. Brake system (10) according to claim 9, characterized in that - the vent connections (3; 34a, 34b) of the second brake modulators (M2; M2a, M2b) are connected to brake pressure connections (33a, 33b) of the first brake modulator (M1), - the supply pressure connections (1; 37a, 37b) and control pressure connections (4, 36a, 36b) of the second brake modulators (M2; M2a, M2b) are connected to a supply pressure (V2) of the second brake circuit (V2, VCU), - the brake pressure connections (2; 35a, 35b) of the second brake modulators (M2; M2a, M2b) are connected to the service brakes (14-17), - the second brake modulators (M2; M2a, M2b) are electrically controlled by the second electronic control unit (VCU).

11. Brake system (10) according to claim 9, characterized in that - the supply pressure connections (1; 37a, 37b) and control pressure connections (4, 36a, 36b) of the second brake modulators (M2; M2a, M2b) are connected to a supply pressure (V2) of the second brake circuit (V2, VCU), - the brake pressure connections (2; 35a, 35b) of the second brake modulators (M2; M2a, M2b) are connected via double check valves (39a, 39b) to brake pressure connections (33a, 33b) of the first brake modulator (M1), - the double check valves (39a, 39b) are connected to the service brakes (14-17), - the second brake modulators (M2; M2a, M2b) are electrically controlled by the second electronic control unit (VCU).

12. Brake system (10) according to claim 9, characterized in that - the supply pressure connections (1; 37a, 37b) and control pressure connections (4, 36a, 36b) of the second brake modulators (M2; M2a, M2b) are connected to a supply pressure (V2) of the second brake circuit (V2, VCU), - the brake pressure connections (2; 35a, 35b) of the second brake modulators (M2; M2a, M2b) and the brake pressure connections (33a, 33b) of the first brake modulator (M1) are connected to common solenoid valves (40a, 40b), wherein the solenoid valves (40a, 40b) selectively allow the brake pressure of the first brake modulator (M1) or the second brake modulators (M2; M2a, M2b) to pass to the service brakes (14-17), - the solenoid valves (40a, 40b) are connected to the service brakes (14-17), - the solenoid valves (40a, 40b) and the second brake modulators (M2; M2a, M2b) are electrically controlled by the second electronic control unit (VCU).

13. Brake system (10) according to one of claims 1-7, characterized in that the second electropneumatic brake system (VCU, M2) has a common second brake modulator (M2) for both sides of the vehicle.

14. Brake system (10) according to claim 13, characterized in that the second brake modulator (M2) is designed with a brake pressure connection (2; 35), a venting connection (3; 34), a supply pressure connection (1; 37), and a control pressure connection (4; 36).

15. Brake system (10) according to claim 14, characterized in that - supply pressure connection (1; 37) and control pressure connection (4; 36) of the second brake modulator (M2) are connected to a supply pressure (V2) of the second brake circuit (V2, VCU), - the brake pressure connection (2; 35) of the second brake modulator (M2) is connected to brake pressure connections (33a, 33b) of the first brake modulator (M1) via parallel double check valves (39a, 39b), - the double check valves (39a, 39b) are connected to the service brakes (14-17), - the second brake modulator (M2) is electrically controlled by the second electronic control unit (VCU).

16. Brake system (10) according to claim 14, characterized in that - supply pressure connection (1; 37) and control pressure connection (4; 36) of the second brake modulator (M2) are connected to a supply pressure (V2) of the second brake circuit (V2, VCU), - the brake pressure connection (2; 35) of the second brake modulator (M2) and the brake pressure connections (33a, 33b) of the first brake modulator (M1) are connected to common solenoid valves (40a, 40b), wherein the solenoid valves (40a, 40b) selectively allow the brake pressure of the first brake modulator (M1) or of the second brake modulator (M2) to pass to the service brakes (14-17), - the solenoid valves (40a, 40b) are connected to the service brakes (14-17), - the solenoid valves (40a, 40b) and the second brake modulator (M2) are electrically controlled by the second electronic control unit (VCU).

17. Trailer vehicle (11) with a braking system (10) according to one of claims 1-16.

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