WO2025040428A1

WO2025040428A1 - Electro-pneumatic brake pressure modulator

Info

Publication number: WO2025040428A1
Application number: PCT/EP2024/072245
Authority: WO
Inventors: Ingo Fuhrmann; Thooyavan JANAKIRAMAN; Sankarapandiyan Subramanian
Original assignee: Zf Cv Systems Global Gmbh
Priority date: 2023-08-18
Filing date: 2024-08-06
Publication date: 2025-02-27

Abstract

The invention relates to an electro-pneumatic brake pressure modulator (1) comprising an electronic control unit (3), an electro-pneumatic valve assembly (2) connected to the first supply connection (9) for receiving the first supply pressure (pS) and configured to provide the first brake pressure (pB1) to the first channel connection (5), the electropneumatic valve assembly comprising an electro-pneumatic pilot control unit (11), a redundancy valve assembly (15), and a relay valve unit (13), wherein the electropneumatic brake pressure modulator (1) comprises a single housing (29), and wherein the electro-pneumatic pilot control unit (11), the redundancy valve assembly (15) and the relay valve unit (13) are combined within the housing (29). The invention further relates to an electro-pneumatic braking system (200), to a vehicle (300) and to a method (400) for providing a redundancy function of an electro-pneumatic braking system (200).

Description

Electro-pneumatic brake pressure modulator

The invention relates to an electro-pneumatic brake pressure modulator for an electropneumatic braking system, the electro-pneumatic brake pressure modulator comprising an electronic control unit, a first supply connection for connecting a first pressurized air supply providing a first supply pressure, a first channel connection for delivering a first brake pressure, an exhaust connection, and an electro-pneumatic valve assembly connected to the first supply connection for receiving the first supply pressure and configured to provide the first brake pressure to the first channel connection. The invention further relates to an electro-pneumatic braking system, a vehicle and a method for providing a redundancy function of an electro-pneumatic braking system.

Vehicles, in particular commercial vehicles, are regularly equipped with pneumatic braking systems. Electro-pneumatic brake pressure modulators of the type mentioned above are used in such pneumatic brake systems. Pneumatic brake systems for motor vehicles usually have one pneumatically actuated wheel brake for each wheel of the motor vehicle. A pneumatic operating medium, in particular compressed air, for the wheel brakes is provided under static pressure in a reservoir. Such brake systems often comprise a brake signal transmitter which is coupled to a brake pedal operable by the driver of the motor vehicle. Upon movement of the brake pedal, the brake signal transmitter generates a brake request signal. Depending on the brake request signal, a corresponding brake pressure is provided to the wheel brakes. In modern vehicles, the brake signal transmitter can also operate electronically as well as pneumatically, so that a brake request signal is output in particular by controller or the like. This allows for semi- orfully-autonomous brake application. An electronic control unit controls the brake pressure modulator based on the brake requests. To facilitate assembly, the electronic control unit of the electro-pneumatic brake pressure modulator may form the controller providing the electronic brake request or brake request signal.

In particular, the electro-pneumatic brake control module of the present invention is used to receive a brake request signal and then output a corresponding brake pressure at the first channel connection. For example, the first channel connection may be connected to brake actuators of a rear axle of the associated vehicle.

Errors of electronic components may occur due to various reasons. In order to safely decelerate a vehicle, even if an error of an electronic component, in particular a brake signal transmitter or an electric control unit occurs, it is desirable to be able to pneumatically provide a brake pressure to the brake actuators. An electro-pneumatic brake control module for commercial vehicles having a redundancy function is known from US 2021/0070272 A1 of the present applicant. The electro-pneumatic brake control module comprising a supply port for connecting a compressed air supply, a first axle channel port, a pneumatically controlled in let/outlet valve unit for outputting a first braking pressure at the first axle channel port, an electro-pneumatic pilot control unit for outputting at least a first control pressure at the inlet/outlet valve unit, a redundancy pressure port for receiving a redundancy pressure, and a redundancy valve unit connected to the redundancy pressure port for outputting a redundancy braking pressure at the first axle channel port in the event that the electro-pneumatic pilot control unit has an error.

Even if such an electro-pneumatic brake control module functions well, there is still room for improvement, in particular to increase the safety of the vehicle, to facilitate integration of an electro-pneumatic brake pressure modulator into a brake system or a vehicle respectively, to improve reliability, to improve response time and/or to reduce overall cost of an electro-pneumatic brake pressure modulator.

In a first aspect to solve this object, the present invention proposes an electro-pneumatic brake pressure modulator of the aforementioned type, wherein the electro-pneumatic valve assembly comprises an electro-pneumatic pilot control unit for providing a pilot control pressure, wherein the electronic control unit is configured to control the electro-pneumatic pilot control unit, a redundancy valve assembly connected to a redundancy connection for receiving a redundancy pressure and configured to provide a redundancy control pressure when the electro-pneumatic pilot control unit is de-ener- gized, and a relay valve unit configured to receive the supply pressure, the pilot control pressure and the redundancy control pressure, and configured to provide the first brake pressure dependent on the pilot control pressure or the redundancy control pressure, wherein the electro-pneumatic brake pressure modulator comprises a single housing, and wherein the electro-pneumatic pilot control unit, the redundancy valve assembly and the relay valve unit are preferably combined within the housing.

Preferably, the single housing is a formed by a single housing body and a single housing cover for closing an assembly opening of the housing body. The single housing may however also comprise multiple sub-housings attached to each other and/or multiple covers provided on a single housing body or multiple housing bodies. In other embodiments, the electro-pneumatic pilot control unit, the redundancy valve assembly and the relay valve unit may also be arranged in separate housings.

The redundancy control pressure is preferably provided by a brake pedal that may be a purely pneumatic brake pedal or an electro-pneumatic brake pedal. This allows a driver of a vehicle to manually provide a redundancy brake pressure in case the electric control unit malfunctions. The electro-pneumatic brake pressure modulator is preferably configured to receive electronic brake request signals. Further preferred, the electropneumatic pilot control unit is configured to control the electro-pneumatic pilot control unit based on the electronic brake request signals. Preferably, the electro-pneumatic pilot control unit is configured to receive electronic control signals and to transform these electronic control signals into the pilot control pressure.

The relay valve unit is configured to receive the supply pressure, the pilot control pressure and the redundancy control pressure. The pilot control pressure and the redundancy control pressure must not be provided to the relay valve unit at the same time. Preferably, the electro-pneumatic brake pressure modulator is configured such that either the pilot control pressure or the redundancy control pressure is supplied to the relay valve unit. The relay valve unit may comprise multiple control ports or a single control port that is configured to receive the pilot control pressure and/or the redundancy control pressure. The pressure level of the first brake pressure provided by the relay valve unit depends on the pilot control pressure or the redundancy control pressure.

Generally, the first brake pressure directly proportional to pilot control pressure from an Electronic Brake System (EBS) control unit and/or a redundancy control pressure. For example, the relay valve unit may provide first brake pressure of 8 bar when EBS pilot control pressure or redundancy control pressure of 8 bar is supplied thereto. However, in EBS control mode, irrespective of whether the redundancy control pressure is pro- vided or not, the first brake pressure is always directly proportional to the EBS pilot control pressure. It shall be understood that the redundancy control pressure received from a Brake Signal Transmitter (BST) or a brake demand transmitting device associated with a brake pedal may still be different from the corresponding EBS control pressure. For example, the relay valve unit may provide a first brake pressure of 8 bar even when redundancy control pressure of e.g., 4 bar is supplied thereto. But in this case, the EBS control unit itself generates EBS control pilot control pressure of 8 bar with respect to the corresponding brake demand. The relay valve unit may thus only provide a different (usually higher) volume flow than the corresponding volume flow of the pilot control pressure and/or redundancy control pressure.

Preferably, the electro-pneumatic pilot control unit comprises at least one solenoid valve. The electro-pneumatic pilot control unit may be de-energized due to overall power loss of a brake system or the electro-pneumatic brake pressure modulator. In other cases, the electro-pneumatic pilot control unit may be de-energized if the electronic control unit has an error.

According to a first preferred embodiment of the invention, the redundancy valve assembly comprises an electro-pneumatic redundancy valve, wherein the electro-pneumatic redundancy valve is controlled by the electronic control unit. The electronic control unit is then configured to control the electro-pneumatic redundancy valve as well as the electro-pneumatic pilot control unit. Use of the electronic control unit for controlling two electro-pneumatic valves or units respectively reduces overall cost. Moreover, reliability of the brake pressure modulator is increased, since coordination errors of different electronic control units are reduced. The preferred further development may facilitate integration of the brake pressure modulator into a brake system, since less wires or cables need to be run. It shall be noted that the electronic control unit controlling the electropneumatic redundancy valve of the redundancy valve assembly is also preferred for embodiments in which the redundancy valve assembly, the electro-pneumatic pilot control unit and the relay valve unit are not combined within a single housing.

Preferably, the redundancy valve assembly comprises a quick release valve, wherein the quick release valve is configured to connect the electro-pneumatic redundancy valve to the exhaust connection of the electro-pneumatic brake pressure modulator if the redundancy connection is vented and/or if the redundancy pressure provided to the redundancy connection is smaller than a quick release pressure. The exhaust connection is preferably connected to the environment via an exhaust silencer or comprises an exhaust silencer. The exhaust connection is therefore configured to release or discharge pressurized air from the electro-pneumatic brake pressure modulator. Releasing pressurized air is usually required in order to vent out brake actuators connected to the brake channel or to vent out other internal and/or external control connections of the brake pressure modulator. Connecting the electro-pneumatic redundancy valve to the exhaust connection allows for a fast response time of the electro-pneumatic brake pressure modulator even under redundancy conditions. Through this, compressed air may be released quickly and must not travel all the way through a corresponding redundancy conduit to a brake valve or electro-pneumatic foot brake valves or brake signal transmitter. Preferably, the connection of the electro-pneumatic redundancy valve to the exhaust connection is established if the redundancy connection is vented and/or if atmospheric pressure or environmental pressure is provided to the redundancy connection. In other embodiments, the connection is established when a quick release pressure exceeds the redundancy pressure. For example, preferably, the quick release pressure may be the redundancy control pressure. The redundancy control pressure can be fed back to the quick release valve as a pneumatic control pressure of the quick release valve. The pilot control pressure may also form the quick release pressure.

In a preferred further development, the quick release valve is connected to the redundancy connection and configured to provide the redundancy pressure to the electropneumatic redundancy valve if the redundancy pressure is supplied to the redundancy connection. In the context of this application, a redundancy pressure being supplied to the redundancy connection means that pressurized air at a pressure level above the ambient pressure is provided to the redundancy connection. Usually, atmospheric pressure therefore is not a redundancy pressure. Preferably, the quick release valve does not alter the pressure level of the redundancy pressure provided to the redundancy connection. It shall however be noted that small pressure losses may still occur in the quick release valve.

The quick release valve is preferably configured to connect the electro-pneumatic redundancy valve to the exhaust connection if ambient pressure is supplied to the redundancy connection. Preferably, the quick release valve is configured to provide a redundancy pressure above an ambient pressure to the electro-pneumatic redundancy valve if this redundancy pressure above the ambient pressure is supplied to the redundancy connection and to connect the electro-pneumatic redundancy valve to the exhaust connection if ambient pressure and/or a pressure below a first pressure threshold is supplied to the redundancy connection.

Preferably, the quick release valve of the electro-pneumatic brake pressure modulator is a pneumatically actuated valve. A pneumatically actuated valve remains functional even in case of an electronic error. Reliability of the electro-pneumatic brake pressure modulator is increased. Preferably, the quick release valve comprises one or more quick release control ports for receiving one or more quick release control pressures.

In a preferred embodiment, the quick release valve is a pneumatically actuated 3/2-way valve comprising a quick release inlet port connected to the redundancy connection, a quick release working port connected to the electro-pneumatic redundancy valve and a quick release exhaust port connected to the exhaust connection, wherein the quick release valve is pneumatically switchable between a redundancy state and an exhaust state, wherein the quick release working port is connected to the quick release supply port if the quick release valve is in the redundancy state and wherein the quick release working port is connected to the quick release exhaust port if the quick release valve is in the exhaust state. A 3/2-way valve has three main ports and two states. The main ports are the quick release working port, the quick release inlet port and the quick release exhaust port. Depending on the state of the quick release valve, at least two (preferably exactly two) of these main ports are pneumatically connected. It shall be noted that a pneumatically actuated 3/2-way valve may additionally comprise one or more control ports for controlling switching of the valve between its states.

Preferably, the quick release valve comprises a first quick release control port and a second quick release control port wherein the quick release valve is configured to switch to the redundancy state if a pressure supplied to the first quick release control port equals and/or exceeds a pressure supplied to the second quick release port and to switch to the exhaust state if the pressure supplied to the second quick release control port equals and/or exceeds the pressure supplied to the first quick release port, wherein the first quick release control port is preferably connected to the quick release supply port and/or wherein the second quick release control port is preferably connected to the quick release working port. The pressures upstream and downstream of the quick release valve may therefore be used for pneumatic control of the quick release valve. This allows implementing a switching function without an external controller. For example, the quick release valve is switched to the redundancy state if a redundancy pressure is supplied to the quick release supply port via the supply connection and if a pressure level of the quick release working port equals the ambient pressure, since the quick release working port has been connected to the exhaust connection while the quick release valve was in the exhaust state. The redundancy pressure is then supplied to the electro-pneumatic redundancy valve and a brake pressure can be provided to the first brake channel. As soon as the redundancy pressure is no longer supplied to the redundancy connection and the first quick release control port, the quick release valve switches back to the exhaust state, since the redundancy pressure is still provided to the quick release working port and the second quick release control port.

In a preferred embodiment, the electro-pneumatic redundancy valve is a normally open valve. ‘In particularly preferred embodiments, the electro-pneumatic redundancy valve is open, when the electro-pneumatic redundancy valve is de-energized, in particular when the electronic control unit is de-energized. Preferably, the electro-pneumatic redundancy valve comprises a biasing element biasing the electro-pneumatic redundancy valve towards the open position. The biasing element may be a spring. The electropneumatic redundancy valve is preferably open, when a redundancy supply port of the electro-pneumatic redundancy valve is connected to a working port of the electro-pneumatic redundancy valve. An open valve allows a fluid connection or passage of pressurized air respectively. A closed valve may block a fluid flow. Preferably, the electro-pneumatic redundancy valve is a solenoid-valve. Preferably, the solenoid-valve is switched into a closed position when the valve is energized, in particular when the valve is energized by the electronic control unit. When functioning properly, the electronic control unit may then energize a solenoid of the electro-pneumatic redundancy valve to hold it in a closed position. As soon as the electronic control unit is de-energized (e.g., due to an electrical error), the electro-pneumatic redundancy valve is de-energized as well. The electro-pneumatic redundancy valve then automatically returns to the open state and allows a redundancy function to be applied.

Preferably, the electro-pneumatic redundancy valve is an electro-pneumatic 3/2 -way valve having a redundancy supply port, a redundancy working port and a redundancy exhaust port connected to the exhaust connection, wherein the redundancy working port is connected to the redundancy supply port when the electronic control unit is deenergized. The redundancy working port of the electro-pneumatic redundancy valve being connected to the redundancy supply port of the electro-pneumatic redundancy valve in the open state. In the closed state, the redundancy working port may be connected to the redundancy exhaust port while the redundancy supply port is blocked.

According to a preferred further development, the redundancy valve assembly further comprises a by-pass that is configured to establish a fluid connection between the redundancy working port of the electro-pneumatic redundancy valve and the redundancy supply port of the electro-pneumatic redundancy valve and to block a fluid connection from the redundancy supply port of the electro-pneumatic redundancy valve to the redundancy working port of the electro-pneumatic redundancy valve. The bypass can allow fluid, in particular pressurized air, to flow from the redundancy working port to the redundancy supply port but block flow in the opposite direction, i.e., from the redundancy supply port to the redundancy working port. It shall be noted that fluid may still flow from the redundancy supply port to the redundancy working port through the electro-pneumatic redundancy valve. Moreover, flow from the redundancy working port to the redundancy supply port may only happen if a pressure difference exists that drives fluid flow between these two ports. The bypass can decrease a response time of the electro-pneumatic brake pressure modulator. For example, when a control port of a relay valve connected to the electro-pneumatic redundancy valve needs to be vented for releasing brake pressure from brake actuators of a vehicle, pressurized air may flow from the redundancy working port to the redundancy supply port via the electro-pneumatic redundancy valve as well as the bypass so that the control port of the relay valve may be vented in less time.

Preferably, the bypass is only configured to establish the fluid connection between the redundancy working port of the electro-pneumatic redundancy valve and the redundancy supply port of the electro-pneumatic redundancy valve if the electronic control unit is de-energized. Functionality of the bypass can be limited to redundancy cases.

In a particularly preferred further development, the electro-pneumatic redundancy valve and the bypass are integrally formed. The bypass may therefore be part of the electro- pneumatic redundancy valve. For example, the bypass may be formed in or around a valve piston of the electro-pneumatic redundancy valve.

Preferably, the bypass is at least partially formed by a lip-seal of the electro-pneumatic redundancy valve. The bypass may also be formed by a one-way check valve. Preferably, the lip-seal is arranged around a piston of the electro-pneumatic redundancy valve. For example, and preferably, a leg of the lip seal is configured to detach from a sealing surface, when a pressure level on the redundancy working port of the electro-pneumatic redundancy valve exceeds a pressure level on the redundancy supply port by a predefined threshold value (e.g., when the redundancy working port shall be vented). If on the other hand a pressure level on the redundancy supply port exceeds a pressure level on the redundancy working port of the electro-pneumatic redundancy valve, the leg may be configured to abut the sealing surface so that the leg blocks a fluid passage connecting the redundancy supply port and the redundancy working port. Integrally forming the bypass and the electro-pneumatic redundancy valve allows for a compact design, facilitates assembly and/or integration and/or may reduce manufacturing cost.

According to a second aspect of the invention, the above stated problem is solved by an electro-pneumatic braking system for a vehicle, preferably comprising a first brake circuit including one or more brake actuators for braking the vehicle, a first compressed air supply, and an electro-pneumatic brake pressure modulator according to any of the preferred embodiments of the first aspect of the invention. Preferably, the electro-pneumatic brake pressure modulator is connected to the compressed air supply and connected to the first brake circuit for supplying a first brake pressure to one or more of the brake actuators. By having an electro-pneumatic brake pressure modulator according to the first aspect of the invention, the electro-pneumatic braking system incorporates the benefits of the first aspect. Preferred embodiments and benefits of the first aspect of the invention are also preferred embodiments and benefits of the second aspect of the invention and vice versa.

In a third aspect of the invention, the above stated problem is solved by a vehicle comprising an electro-pneumatic braking system according to the second aspect of the invention. In a fourth aspect of the invention, the above stated problem is solved by a method for providing a redundancy function of an electro-pneumatic braking system, preferably an electro-pneumatic braking system according to the second aspect of the invention, the method comprising the steps of: providing a redundancy pressure to a quick release supply port of a quick release valve of an electro-pneumatic redundancy valve assembly, switching the quick release valve from an exhaust state to a redundancy state for enabling fluid communication of the quick release supply port and a quick release working port by providing the redundancy pressure to a first quick release control port of the quick release valve, providing the redundancy pressure from the quick release working port to an electro-pneumatic redundancy valve of the electro-pneumatic redundancy valve assembly, providing a redundancy control pressure from the electro-pneumatic redundancy valve to a relay valve control port of a relay valve unit if the redundancy pressure is provided to the electro-pneumatic redundancy valve by the quick release valve, and providing a brake pressure dependent on the redundancy control pressure by the relay valve unit. Preferably, the method further comprises: switching the quick release valve to the exhaust state for enabling fluid communication of the quick release working port and a quick release exhaust port, if a pressure level at the quick release working port (quick release working pressure) equals and/or exceeds a pressure level at the quick release supply port (quick release supply pressure). Preferably, the step of switching of the quick release valve to the exhaust state only takes place when the quick release working pressure exceeds the quick release supply pressure by a first safety margin.

It shall be understood that the electro-pneumatic braking system according to the second aspect of the invention, the commercial vehicle according to the third aspect of the invention, the method for providing a redundancy function according to the fourth aspect of the invention and the electro-pneumatic brake pressure modulator according to the first aspect of the invention comprise similar and identical embodiments which are in particular described in the dependent claims. In so far, reference is made to the above description of the electro-pneumatic brake pressure modulator according to the first aspect of the invention.

For a more complete understanding of the invention, the invention will now be described in detail with reference to the accompanying drawings. The detailed description will illustrate and describe what is considered as preferred embodiments of the invention. It should of course be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention may not be limited to the exact form and detail shown and described herein, nor to anything less than the whole of the invention disclosed herein and as claimed herein after. Further, the features described in the description, the drawings and the claims disclosing the invention may be essential for the invention considered alone or in combination. In particular, any reference signs in the claims shall not be construed as limiting the scope of the invention. The wording “comprising” or “including” does not exclude other elements or steps. The word “a” or “an” does not exclude the plurality. The wording “a number of” items comprising also the number 1 , i.e. , a single item, and further numbers like 2, 3, 4 and so forth.

In the accompanying drawings:

Fig. 1 shows a schematic layout of a vehicle having an electro-pneumatic braking system;

Fig. 2 shows a schematic layout of an electro-pneumatic brake pressure modulator; and

Fig. 3 shows a schematic block diagram illustrating a method for providing a redundancy function of an electro-pneumatic braking system.

A vehicle 300, in particular a commercial vehicle 302, comprises a front axle FA and preferably a rear axle RA. The vehicle 300 is a tractor vehicle of a tractor vehicle I trailer combination (trailer not shown). For braking the front axle FA and the rear axle RA the tractor vehicle 300 comprises an electro-pneumatic braking system 200.

The electro-pneumatic braking system 200 comprises a second brake circuit 202, which here is a first brake circuit 206, which here is a rear axle brake circuit 208 for the rear axle RA, and preferably a front axle brake circuit 204 for the front axle FA. Furthermore, the electro-pneumatic braking system 200 comprises a trailer control circuit 210. For providing compressed air at a supply pressure pS, the electro-pneumatic braking system 200 comprises a first compressed air supply 218 and second compressed air supply 212. In this embodiment, the second compressed air supply 212 supplies the second brake circuit 202. The electro-pneumatic braking system 200 further has an external hand control valve unit 214 which may be formed as a dash valve 216 and to which the air is provided.

First brake circuit 206 is supplied by the first compressed air supply 218, which also provides compressed air at the supply pressure pS. However, it is also preferred that the second compressed air supply 212 or the first compressed air supply 218 supplies the first or second brake circuit 206, 202, only or that the first and second compressed air supply 218, 212 provide different pressures. Compressed air is provided to the first and second compressed air supplies 218, 212 by an air treatment system, which is not shown.

The electro-pneumatic braking system 200 includes a main electronic control unit 3, which is also referred to as main ECU, for controlling its elements. The main ECU in particular controls an electro-pneumatic valve assembly 2 provided for the rear axle RA. In this embodiment, the electro-pneumatic valve assembly 2 (or brake pressure modulator 2 respectively) and main ECU 3 are formed as an electro-pneumatic brake pressure modulator 1 . A front axle modulator 226 is connected to first and second front axle ABS- modules 228a, 228b which in turn are connected to front axle brake actuators 230a, 230b. The front axle modulator 226 is pneumatically connected to a foot brake module 232. In this embodiment, the foot brake module 232 is formed as an electro-pneumatic foot brake module 234. Upon actuation (represented by arrow 236) by a user or upon electronic actuation by an actuator (not shown) the foot brake module 234 provides a front axle brake pressure pBFA to the front axle modulator 226.

The foot brake module 232 is further connected to the main ECU 3 via a foot brake signal line 238. Upon actuation the foot brake module 232 provides foot brake signals SFB proportional to the actuation. The main ECU 3 controls the electro-pneumatic valve assembly 2 which then provides a corresponding rear axle brake pressure pBRA to rear axle brake actuators 240a, 240b, 240c, 240d of the rear axle RA. The rear axle brake actuators 240a, 240b, 240c, 240d are formed as tristop-cylinders providing a service braking function as well as a park braking function. When the rear axle brake pressure pBRA is supplied to the service side of rear axle brake actuators 240a, 240b, 240c, 240d the tristop-cylinders are closed for braking the rear axle RA. The parking brake portion of the rear axle brake actuators 240a, 240b, 240c, 240d is configured for braking the rear axle RA of the vehicle 300 in a non-pressurized state. During a drive of the vehicle 300 a park brake pressure is supplied to the rear axle brake actuators 240a, 240b, 240c, 240d. When the park brake pressure is supplied, spring elements (not shown) of the rear axle brake actuators 240a, 240b, 240c, 240d, the rear axle brake actuators 240a, 240b, 240c, 240d are opened and the rear axle RA is ready for driving.

The park brake pressure is provided to the rear axle brake actuators 240a, 240b, 240c, 240d by a park brake module 242 which is in fluid communication with the external hand control valve unit 214 via protection line 244. The park brake module 242 receives park brake signals SPB from the main ECU 3 and provides the park brake pressure.

The trailer control circuit 210 further has an electro-pneumatic trailer control module 246. For receiving signals the trailer control module 246 is connected to the main ECU 3 via a signal line. The trailer control module 246 is further connected to a supply coupling head 250 and a control coupling head 252. According to SAE International’s standard J318 the control coupling head 252 is usually referred to as blue coupling head while the supply coupling head 250 is referred to as red coupling head. The supply coupling head 250 is connected to a trailer supply port of the trailer control module 246 for delivering a trailer supply pressure to the trailer via the supply coupling head 250. The control coupling head 252 is connected to a trailer control working port of the trailer control module 246 for providing a trailer control pressure to the trailer via the control coupling head 252.

In this embodiment, the trailer control module 246 comprises a first supply connection 9 fluidically connected to the second compressed air supply 212. A second supply connection of the trailer control module 246 is connected to the first compressed air supply 218.

When the external hand control valve unit 214 is in an external supply state (in general a pushed position if the external hand control valve unit 214 is a push-pull valve), then air at supply pressure pS is preferably supplied to the protection line 244 from the second compressed air supply 212 and/or the first compressed air supply 218 via the external hand control valve unit 214. In a closed state of the external hand control valve unit 214 (in general a pulled position) airflow from the second compressed air supply 212 and the first compressed air supply 218 to the control line 244 is preferably blocked by the external hand control valve unit 214. The external hand control valve unit 214 is further configured to switch from the external supply state to the closed state when a pressure in the protection line 244 drops below a predefined pressure level. If, for example, due to a failure in the protection line 244 or an unintended trailer breakaway, a pressure level in the protection line 244 drops below a the predefined pressure level, the external hand control valve unit 214 automatically blocks the fluid connection of the protection line 244 to the second compressed air supply 212 and the first compressed air supply 218 (the push-pull valve pops out) and thus the supply to the trailer control circuit 210 is blocked and a considerable pressure loss is detected.

As described above, the electro-pneumatic brake pressure modulator 1 is electronically controllable via foot brake signals SFB provided from the foot brake module 232 to the main ECU 3 via foot brake signal line 238. The electro-pneumatic brake pressure modulator 1 is configured to receive the foot brake signals SFB and to provide a corresponding rear axle brake pressure pBRA. In the present embodiment, the rear axle brake pressure is a first brake pressure pB1 . The first brake pressure pB1 is provided at a first channel connection 5 of the electro-pneumatic brake pressure modulator 1 which is connected to the rear axle brake actuators 240a, 240b, 240c, 240d.

Furthermore, the electro-pneumatic brake pressure modulator 1 is connected to the foot brake module 232 via redundancy line 248 for receiving a redundancy pressure pR. In particular, the redundancy line 248 is connected to a redundancy connection 7 of the electro-pneumatic brake pressure modulator 1 . In this embodiment the redundancy pressure pBR equals the front axle brake pressure pBFA. Redundancy pressure pR may be supplied to the electro-pneumatic brake pressure modulator 1 in case the main ECU 3 and/or the foot brake module 232 has an error or the foot brake signal line SFB is damaged. Through this, a first brake pressure pB1 may still be supplied to the rear axle brake actuators 240a, 240b, 240c, 240d in case an electric or electronic error occurs.

Besides the redundancy connection 7 and the first channel connection 5, the electropneumatic brake pressure modulator 1 further comprises a first supply connection 9. In the embodiment shown in Figure 1 , the first compressed air supply 218 is connected to the first supply connection 9 so that compressed air at supply pressure pS is supplied thereto.

Fig. 2 schematically shows an embodiment of the electro-pneumatic brake pressure modulator 1 having the electro-pneumatic valve assembly 2, the main ECU 3, the first channel connection 5, the redundancy connection 7 and the first supply connection 9. The electro-pneumatic valve assembly 2 further comprises two electro-pneumatic pilot control units 11 , two relay valve units 13 and a redundancy valve assembly 15. Moreover, two exhaust connections 17 are provided.

For the sake of simplicity, all rear axle brake actuators 240a, 240b, 240c, 240d are connected to the first channel connection 5 in Fig. 1. It shall be noted that the electro-pneumatic brake pressure modulator 1 may also comprise multiple channel connections, for example, one channel connection for the left side of the vehicle 300 and one channel connection for the right side of the vehicle 300. In Fig. 2, the electro-pneumatic brake pressure modulator 1 comprises four such first channel connections 5a, 5b, 5c, 5d. Each rear axle brake actuator 240a, 240b, 240c, 240d is connected to a specific channel connection 5a, 5b, 5c, 5d. In some embodiments, those connections can be interchangeable.

In the embodiment of Fig. 2, the electro-pneumatic brake pressure modulator 1 is of a twin design having a first sub-channel 19a for providing the first brake pressure pB1 to the right side of the vehicle 300 and a second sub-channel 19b for providing the first brake pressure pB1 to the left side of the vehicle 300. Here, the first sub-channel 19a is configured to provide the first brake pressure pB1 to first channel connections 5a and 5c and the second sub-channel 19b is configured to provide the first brake pressure pB1 to other first channel connections 5b and 5d. It shall be noted that the brake pressures pB1 provided by the sub-channels 19a, 19b to the channel connections 5a, 5b, 5c, 5d may be different from each other or a brake pressure pB1 may be provided by only one of the sub-channels 19a, 19b. Each of the sub-channels 19a, 19b comprises a pilot control unit 11 , relay valve unit 13, a first supply connection 9a, 9b, an exhaust connection 17, 17 and two of first channel connections 5a, 5b, 5c, 5d. The redundancy valve assembly 15 is connected to both sub-channels 19a, 19b. As the two-sub channels 19a, 19b are identical, the functionality of only one of the sub-channels is described in the following. A general reference number will generally be used in the description of an element without an additional character as the description generally fits the respective element of both sub-channels 19a, 19b.

The electro-pneumatic pilot control unit 11 of the electro-pneumatic valve assembly 2 comprises an electro-pneumatic pilot control signal supply valve 21 and a pilot control signal exhaust valve 25. Supply pressure pS is supplied to the first supply connection 9 from the first compressed air supply 218. From the first supply connection 9, supply pressure pS is supplied to a relay valve supply port 23.1 of a relay valve 23 of the relay valve unit 13 and a pilot control port 21.1 of the pilot control signal supply valve 21 . A pilot control working port 21 .2 of the electro-pneumatic pilot control signal supply valve 21 is in direct fluid connection with a relay valve control port 23.2 of the relay valve 23.

The electro-pneumatic pilot control signal supply valve 21 is a 2/2-way solenoid valve connected to the main ECU 3. In the present embodiment, the electro-pneumatic pilot control signal supply valve 21 of the electro-pneumatic pilot control unit 11 is a normally closed valve. The electro-pneumatic pilot control signal supply valve 21 is therefore configured to be closed in a de-energized state. A spring element 21 .3 biases the electropneumatic pilot control signal supply valve 21 to a closed position. In the closed position fluid flow from the pilot control supply port 21.1 to the pilot control working port 21 .2 is blocked. By energizing a solenoid 21 .4 of the electro-pneumatic pilot control signal supply valve 21 , the pilot control signal supply valve 21 can be gradually opened and held in an open position.

The main ECU 3 is configured to control the electro-pneumatic pilot control unit 11 such that a pilot control pressure pPC is provided. In the embodiment shown in Fig. 2, the main ECU 3 energizes the solenoid 21 .4 of the electro-pneumatic pilot control signal supply valve 21 . The pressure level of the pilot control pressure pPC provided to the pilot control working port 21 .2 is controlled by the main ECU 3. The main ECU 3 can control the electro-pneumatic pilot control signal supply valve 21 such that the pilot control pressure pPC corresponds to the electronic braking signals SB or foot brake signals SFB respectively provided to the main ECU from the electro-pneumatic foot brake module 234. The pilot control working port 21 .2 is further connected to a first bleed port 25.1 of a pilot control signal exhaust valve 25 which is a 2/2-way solenoid valve. The pilot control signal exhaust valve 25 is preferably open in a de-energized state. Therefore, the pilot control signal exhaust valve 25 is biased into the open position, in that the first bleed port 25.1 is connected to a second bleed port 25.2 by a spring element 25.3. The second bleed port 25.2 of the pilot control signal exhaust valve 25 is connected to the redundancy valve assembly 15 of the electro-pneumatic brake pressure modulator 1 . The pilot control signal exhaust valve 25 is also connected to the main ECU 3. For closing the pilot control signal exhaust valve 25 or for preventing fluid flow from the first bleed port 25.1 to the second bleed port 25.2, the main ECU 3 energizes a solenoid 25.4 of the pilot control signal exhaust valve 25. If the pilot control signal exhaust valve 25 is opened by the main ECU 3, pressure in a first control line 27 arranged between the pilot control working port 21 .2 and the relay valve control port 23.2 is released through the pilot control signal exhaust valve 25. The first control line 27 can be vented via a the pilot control signal exhaust valve 25.

The relay valve 23 is a pneumatic relay valve, wherein a control signal provided to the relay valve control port 23.2 of the relay valve 23 is a pneumatic control signal. During normal operation, the control signal is the pilot control pressure pPC provided by the electro-pneumatic pilot control signal supply valve 21 . The relay valve 23 modulates the supply pressure pS of compressed air supplied to the relay valve supply port 23.1 such that the first brake pressure pB1 provided at a relay valve working port 23.3 equals a relay valve control pressure pRVC supplied to the relay valve control port 23.2. During a normal braking operation both the electro-pneumatic pilot control signal supply valve 21 and the pilot control signal exhaust valve 25 are energized by the main ECU 3 based on the brake signals SB. The electro-pneumatic pilot control signal supply valve 21 is opened while the pilot control signal exhaust valve 25 is closed. During a normal or electronic braking operation, the pilot control pressure pPC therefore forms the relay valve control pressure pRVC.

It shall be understood that substantially no airflow occurs from the relay valve control port 23.2 to the relay valve working port 23.3. The relay valve control pressure pRVC supplied to the relay valve control port 23.2 only controls the pressure level at the relay valve working port 23.3. Thus, if no compressed air is supplied to the first supply connection 9 no first brake pressure pB1 is supplied first channel connections 5. Furthermore, an air flow through the electro-pneumatic pilot control signal supply valve 21 of the electro-pneumatic pilot control unit 11 is very small or negligible and an accuracy of the pressure generation in the electro-pneumatic pilot control signal supply valve 21 can be increased. Furthermore, the relay valve 23 is purely pneumatic and thus also functions when the electro-pneumatic pilot control unit 11 is in a de-energized state. Preferably, the relay valve 23 further comprises a relay valve bleed port 23.4 for releasing pressure. In the embodiment shown in Fig. 2, the relay valve bleed port 23.4 is connected to the exhaust connection 17. An exhaust silencer may be arranged upstream or downstream of the exhaust connection 17. The exhaust silencer may be arranged in a housing 29 of the electro-pneumatic brake pressure modulator 1 or outside of the housing 29.

For measuring the first brake pressure pB1 supplied to the rear axle brake actuators 240a, 240b, 240c, 240d of the vehicle 300 via the first channel connections 5, the electro-pneumatic brake pressure modulator 1 further comprises a pressure sensor. The pressure sensor is connected to the main ECU 3 and provides signals corresponding to the first brake pressure pB1 to the main ECU 3.

After a braking operation of the vehicle 300 is completed, supply of the first brake pressure pB1 to the first channel connection 5 is no longer necessary. Therefore, the relay valve control pressure pRVC provided to the relay valve control port 23.2 needs to be released from the first control line 27. To this purpose the main ECU 3 de-energizes the electro-pneumatic pilot control signal supply valve 21 and the pilot control signal exhaust valve 25. The pilot control signal exhaust valve 25 then connects the first control line 27 to the redundancy valve assembly 15. The further flow path of relay valve control pressure pRVC to the environment is explained later after the functionality of the redundancy valve assembly 15 has been described.

The redundancy valve assembly 15 comprises an electro-pneumatic redundancy valve 39, a quick release valve 35 and a bypass 37. The redundancy valve assembly 15 is configured to provide a redundancy control pressure pRC to the relay valve control port 23.2 of the relay valve 23 when the electro-pneumatic pilot control unit 11 is de-ener- gized. By providing the redundancy control pressure pRC, a first brake pressure pB1 can be provided to the first channel connections 5 even in case of an electric error. Redundancy pressure pR is supplied to the redundancy port 7 of the redundancy valve assembly 15 via line 248. In the present embodiment, the front axle brake pressure pBFA provided by the electro-pneumatic foot brake module 234 forms the redundancy pressure pR. The front axle brake pressure pBFA or the redundancy pressure pR is provided from the electro-pneumatic foot brake module 234 to the redundancy connection 7 of the electro-pneumatic brake pressure modulator 1 via the redundancy line 248.

The redundancy connection 7 is directly connected to a quick release inlet port 35.1 of the quick release valve 35. The quick release valve 35 is a pneumatically actuated valve. A first quick release control port 35.4 is also directly connected to the redundancy connection 7 so that redundancy pressure pR is supplied to the quick release inlet port 35.1 as well as the first quick release control port 35.4.

The quick release valve 35 is a pneumatically actuated 3/2-way valve having two states and three main ports. Besides the quick release supply port 35.1 , the quick release valve 35 further comprises a quick release working port 35.2 and a quick release exhaust port 35.3. The first quick release control port 35.4 and a second quick release control port 35.5 are provided for switching the quick release valve 35 between its two states. In a redundancy state, the quick release supply port 35.1 is connected to the quick release working port 35.2. In an exhaust state of the quick release valve 35, the quick release working port 35.2 is connected to the quick release exhaust port 35.3. Pressurized air may be discharged from the redundancy valve assembly 15 via the quick release exhaust port 35.3 which is directly connected to an exhaust connection 17.

The state, the quick release valve 35 is in, depends on the pressure provided to the first quick release control port 35.4 and the second quick release control port 35.5. In the embodiment shown in Fig. 2, the quick release valve 35 is switched to the redundancy state when a pressure provided to the first quick release control port 35.4 exceeds a pressure provided to the second quick release control port 35.5. This is usually the case, when a redundancy pressure pR is provided to the redundancy connection 7 of the electro-pneumatic brake pressure modulator 1 . In the redundancy state, the redundancy pressure pR is provided to the quick release working port 35.2 via the quick release supply port 35.1 . In the present embodiment, the quick release working port 35.2 is directly connected to the second quick release control port 35.5. The pressure at the quick release working port 35.2 forms a quick release pressure pQ of the quick release valve 35. Preferably, the quick release valve 35 switches back to the exhaust state from the redundancy state as soon as the redundancy pressure pR is no longer supplied to the redundancy connection 7.

The quick release working port 35.2 is further connected to an electro-pneumatic redundancy valve 39. Preferably and as shown in Fig. 2, the electro-pneumatic redundancy valve 39 is controlled by the main ECU 3. The electro-pneumatic redundancy valve 39 is a 3/2 -way solenoid valve having a redundancy supply port 39.1 , a redundancy working port 39.2 and a redundancy exhaust port 39.3. When a solenoid 39.4 of the electropneumatic redundancy valve 39 is energized by the main ECU 3, the electro-pneumatic redundancy valve 39 is held in an exhaust state in which the redundancy working port

39.2 is connected to the redundancy exhaust port 39.3. The redundancy exhaust port

39.3 is directly connected to an exhaust connection 17 so that pressurized air may be discharged from the redundancy working port 39.2 to the environment via the redundancy exhaust port 39.3 and the exhaust connection 17 when the main ECU 3 energizes the electro-pneumatic redundancy valve 39.

In the embodiment shown in Fig. 2, the redundancy working port 39.2 is directly connected to the second bleed port 25.2 of the pilot control signal exhaust valve 25 of the electro-pneumatic pilot control unit 11 . Pressurized air can therefore be released from the electro-pneumatic pilot control unit 11 or the relay valve control port 23.2 respectively via the electro-pneumatic redundancy valve 39 as long as the main ECU 3 energizes the electro-pneumatic redundancy valve 39.

The electro-pneumatic redundancy valve 39 is biased towards a redundancy state by a spring element 39.4. In this redundancy state, the redundancy working port 39.2 is connected to the redundancy supply port 39.1 . The spring element 39.4 switches the electro-pneumatic redundancy valve 39 to the redundancy state when the solenoid 39.5 of the electro-pneumatic redundancy valve 39 is de-energized. In case of an electrical error, for example if the main ECU 3 has an error or if the line 238 is broken or no electronic braking signal SB can be provided, the main ECU 3 no longer energizes the electro-pneumatic redundancy valve 39, the electro-pneumatic pilot control signal supply valve 21 and the pilot control signal exhaust valve 25. The electro-pneumatic pilot control unit 11 can then no longer supply the pilot control pressure pPC to the relay valve control port 23.2. Without the redundancy valve assembly 15, supply of the first brake pressure pB1 to the rear axle brake actuators 240a, 240b, 240c, 240d would no longer be possible. The redundancy valve assembly 15 provides the required redundancy function. The electro-pneumatic redundancy valve 39 is switched to a redundancy state and the pilot control signal exhaust valve 25 connects the redundancy working port 39.2 to the relay valve control port 23.2 in case of an error, in particular an electrical error. A redundancy control pressure pRC can then be provided to the relay valve control port 23.2 by the redundancy valve assembly 15. A first brake pressure pB1 corresponding to this redundancy control pressure pRC is then provided to the first channel connections 5 and the rear axle brake actuators 240a, 240b, 240c, 240d connected thereto even in case of an electrical error. As long as the main ECU 3 works as intended, it energizes the electro-pneumatic redundancy valve 39 and thus disconnects the redundancy supply port 39.1 from the redundancy working port 39.2 and the relay valve control port 23.2.

In the present embodiment, the redundancy pressure pR forms the redundancy control pressure pRC as the electro-pneumatic redundancy valve 39 and the quick release valve 35 do not substantially alter the redundancy pressure pR. Therefore, in case of an emergency or an electrical error, a first brake pressure pB1 proportional to the front axle brake pressure pBFA which is provided to the rear axle brake actuators 240a, 240b, 240c, 240d as a redundancy control pressure pR via redundancy port 7. When a braking operation is finished and a driver no longer actuates the electro-pneumatic foot brake module 234, the redundancy pressure pR is no longer provided to the redundancy connection 7. The quick release valve switches to the exhaust state and connects the quick release working port 35.2 to the quick release exhaust port 35.3 so that the redundancy control pressure pRC can be released from the relay valve control port 23.2 via the pilot control signal exhaust valve 25 and the electro-pneumatic redundancy valve 39. To accelerate release of the rear axle brake actuators 240a, 240b, 240c, 240d, the redundancy valve assembly further comprises the bypass 37. The bypass allows flow of pressurized air from the redundancy working port 39.2 to the redundancy supply port

39.1 but not in the opposite direction from the redundancy supply port 39.1 to the redundancy working port 39.2. The bypass 37 increases an open cross-section for pressurized air to flow through during release of relay valve control pressure pRVC from the relay valve control port 23.2.

In the embodiment illustrated in Fig. 2, the bypass 37 is formed by a check valve 41 . In particularly preferred embodiments, the bypass 37 is integrally formed with the electropneumatic redundancy valve 39. In particular, the check valve function of the bypass 37 may be formed by a lip seal that abuts a sealing seat when a pressure provided to the redundancy supply port 39.1 exceeds a pressure at the redundancy working port 39.2. If a pressure at the redundancy working port 39.2 exceeds a pressure provided to the redundancy supply port 39.1 , the lip seal can detach from the sealing seat so that an additional cross section is opened that allows fluid flow from the redundancy working port

39.2 to the redundancy supply port 39.1 .

In the present embodiment of the electro-pneumatic brake pressure modulator 1 , the main ECU 3, the electro-pneumatic pilot control unit 11 , the redundancy valve assembly 15 and the relay valve unit 13 are all provided within a single housing 29. Through this, assembly of the electro-pneumatic brake pressure modulator 1 and/or integration of the electro-pneumatic brake pressure modulator 1 into the vehicle 300 are facilitated. Moreover, the main ECU 3 controls the electro-pneumatic pilot control unit 11 as well as the electro-pneumatic redundancy valve 39 of the redundancy valve assembly 15. A single main ECU 3 is therefore used for controlling multiple devices. This may decrease overall cost of the electro-pneumatic brake pressure modulator 1 . Moreover, a redundancy function of the electro-pneumatic brake pressure modulator 1 is ensured, since the redundancy valve assembly 15 is automatically enabled to provide the redundancy control pressure pRC as relay valve control pressure pRVC in case an electrical error occurs and providing the pilot control pressure pPC is no longer possible. It is thus not required to coordinate multiple electronic control units, in particular if only one of these electronic control units malfunctions. Fig. 3 illustrates a method 400 for providing a redundancy function of an electro-pneumatic braking system 200, in particular a braking system 200 as shown in Fig. 1 having an electro-pneumatic brake pressure modulator 1 as shown in Fig. 2. The redundancy function is provided if an electrical error occurs.

In a first step, providing 402 a redundancy pressure pR to a quick release supply port

35.1 of the quick release valve 35 is performed. As discussed above, the redundancy pressure pR is provided to the quick release supply port 35.1 of the quick release valve 35 of the electro-pneumatic redundancy valve assembly 15 by the foot brake module 232. The quick release valve 35 is switched (step switching 404 in Fig. 3) from an exhaust state to a redundancy state for enabling fluid communication of the quick release supply port 35.1 an the quick release working port 35.2. Switching 404 is conducted by providing the redundancy pressure pR to the first quick release control port 35.4 of the quick release valve 35. When the quick release valve 35 is in the redundancy state, a step of providing 406 the redundancy pressure pR from the quick release working port

35.2 to the electro-pneumatic redundancy valve 39 of the electro-pneumatic redundancy valve assembly 15 is performed. In a subsequent fourth step of providing 408, the redundancy control pressure pRC is provided from the electro-pneumatic redundancy valve 39 to the relay valve control port 23.2 of the relay valve 23 of the relay valve unit 13. For the brake system 200 shown in Fig. 1 having the electro-pneumatic brake pressure modulator 1 of Fig. 2, the redundancy pressure pR forms the redundancy control pressure pRC. In a fifth step of the method 400, a brake pressure is provided (providing 410 in Fig. 3) by the relay valve unit 13 dependent on the redundancy control pressure pRC. In the present embodiment, the redundancy control pressure pRC provided by the relay valve 23 is proportional to the redundancy pressure pR.

List of reference signs (Part of the description) electro-pneumatic brake pressure modulator electro-pneumatic valve assembly main electronic control unit (main ECU) , 5a, 5b, 5c, 5d first channel connection redundancy connection first supply connection 1 electro-pneumatic pilot control units 3 relay valve unit 5 redundancy valve assembly 7 exhaust connection 9a, 19b sub-channel 1 electro-pneumatic pilot control signal supply valve1.1 pilot control port 1.2 pilot control working port 1.3 spring element of electro-pneumatic pilot control valve1.4 solenoid of electro-pneumatic pilot control valve3 relay valve 3.1 relay valve supply port 3.2 relay valve control port 3.3 relay valve working port 3.4 relay valve bleed port 5 pilot control signal exhaust valve 5.1 first bleed port 5.2 second bleed port 5.3 spring element of pilot control signal exhaust valve5.4 solenoid of pilot control signal exhaust valve 7 first control line 9 housing 5 quick release valve 5.1 quick release inlet port 5.2 first quick release working port 5.3 first quick release exhaust port 5.4 first quick release control port second quick release control port bypass electro-pneumatic redundancy valve redundancy supply port redundancy working port redundancy exhaust port spring element of the electro-pneumatic redundancy valve solenoid of the electro-pneumatic redundancy valve check valve electro-pneumatic braking system second brake circuit front axle brake circuit first brake circuit rear axle brake circuit trailer control circuit second compressed air supply external hand control valve unit dash valve first compressed air supply front axle modulator a, 228b front axle ABS-modules a, 230b front axle brake actuators foot brake module electro-pneumatic foot brake module foot brake signal line a, 240b, rear axle brake actuators c, 240d park brake module protection line electro-pneumatic trailer control module redundancy line supply coupling head control coupling head vehicle commercial vehicle 400 method 402 step of providing a redundancy pressure to a quick release port 404 step of switching the quick release valve 406 step of providing the redundancy pressure to the electro-pneumatic redundancy valve

408 step of providing the redundancy control pressure to a relay valve control port

410 step of providing a brake pressure FA front axle RA rear axle pB1 first brake pressure pBFA front axle brake pressure pBR redundancy pressure pBRA rear axle brake pressure pQ quick release pressure pPC pilot control pressure pR redundancy pressure pRC redundancy control pressure pRVC relay valve control pressure PS supply pressure SB electronic braking signal

SFB foot brake signals SPB park brake signals

SRA rear axle brake signals

Claims

1 . An electro-pneumatic brake pressure modulator (1 ) for an electro-pneumatic braking system (200), the electro-pneumatic brake pressure modulator (1) comprising an electronic control unit (3); a first supply connection (9) for connecting a first pressurized air supply (218) providing a first supply pressure (pS); a first channel connection (5) for delivering a first brake pressure (pB1); an exhaust connection (17); and an electro-pneumatic valve assembly (2) connected to the first supply connection (9) for receiving the first supply pressure (pS) and configured to provide the first brake pressure (pB1) to the first channel connection (5), wherein the electropneumatic valve assembly comprises an electro-pneumatic pilot control unit (11 ) for providing a pilot control pressure (pPC), wherein the electronic control unit (3) is configured to control the electro-pneumatic pilot control unit (11 ); a redundancy valve assembly (15) connected to a redundancy connection

(7) for receiving a redundancy pressure (pR) and configured to provide a redundancy control pressure (pRC) when the electro-pneumatic pilot control unit (11 ) is de-energized; and a relay valve unit (13) configured to receive the supply pressure (pS), the pilot control pressure (pPC) and the redundancy control pressure (pRC), and configured to provide the first brake pressure (pB1) dependent on the pilot control pressure (pPC) or the redundancy control pressure (pRC); wherein the electro-pneumatic brake pressure modulator (1) comprises a single housing (29), and wherein the electro-pneumatic pilot control unit (11), the redundancy valve assembly (15) and the relay valve unit (13) are combined within the housing (29).

2. The electro-pneumatic brake pressure modulator (1 ) according to claim 1 , wherein the redundancy valve assembly (15) comprises an electro-pneumatic redundancy valve (39), wherein the electro-pneumatic redundancy valve (39) is controlled by the electronic control unit (3).

3. The electro-pneumatic brake pressure modulator (1) according to claim 2, wherein the redundancy valve assembly (15) comprises a quick release valve (35), wherein the quick release valve (35) is configured to connect the electro-pneumatic redundancy valve (39) to the exhaust connection (17) of the electro-pneumatic brake pressure modulator (1) if the redundancy connection (7) is vented and/or if the redundancy pressure (pR) provided to the redundancy connection (7) is smaller than a quick release pressure (pQ).

4. The electro-pneumatic brake pressure modulator (1) according to claim 3, wherein the quick release valve (35) is connected to the redundancy connection (7) and configured to provide the redundancy pressure (pR) to the electro-pneumatic redundancy valve (39) if the redundancy pressure (pR) is supplied to the redundancy connection (7).

5. The electro-pneumatic brake pressure modulator (1) according to claim 4, wherein the quick release valve (35) is a pneumatically actuated valve.

6. The electro-pneumatic brake pressure modulator (1) according to claim 5, wherein the quick release valve (35) is a pneumatically actuated 3/2-way valve comprising a quick release inlet port (35.1 ) connected to the redundancy connection (7), a quick release working port (35.2) connected to the electro-pneumatic redundancy valve (39) and a quick release exhaust port (35.3) connected to the exhaust connection (17), wherein the quick release valve (35) is pneumatically switchable between a redundancy state and an exhaust state, wherein the quick release working port (35.2) is connected to the quick release supply port (35.1) if the quick release valve (35) is in the redundancy state and wherein the quick release working port (35.2) is connected to the quick release exhaust port (35.3) if the quick release valve (35) is in the exhaust state.

7. The electro-pneumatic brake pressure modulator (1) according to claim 6, wherein the quick release valve (35) comprises a first quick release control port (35.4) and a second quick release control port (35.5), wherein the quick release valve (35) is configured to switch to the redundancy state if a pressure supplied to the first quick release control port (35.4) exceeds a pressure supplied to the second quick release control port (35.5) and to switch to the exhaust state if the pressure supplied to the second quick release control port (35.5) exceeds the pressure supplied to the first quick release port (35.4), wherein the first quick release control port (35.4) is connected to the quick release supply port (35.1 ) and wherein the second quick release control port (35.5) is connected to the quick release working port (35.2).

8. The electro-pneumatic brake pressure modulator (1 ) according to any of claims 2 to 7, wherein the electro-pneumatic redundancy valve (39) is a normally open valve that is open, when the electronic control unit (3) is de-energized.

9. The electro-pneumatic brake pressure modulator (1) according to claim 8, wherein the electro-pneumatic redundancy valve (39) is an electro-pneumatic 3/2 -way valve having a redundancy supply port (39.1 ), a redundancy working port (39.2) and a redundancy exhaust port (39.3) connected to the exhaust connection (17), wherein the redundancy working port (39.2) is connected to the redundancy supply port (39.1) when the electronic control unit (3) is de-energized.

10. The electro-pneumatic brake pressure modulator (1) according to claim 9, wherein the redundancy valve assembly (15) further comprises a bypass (37) that is configured to establish a fluid connection between the redundancy working port (39.2) of the electro-pneumatic redundancy valve (39) and the redundancy supply port (39.1 ) of the electro-pneumatic redundancy valve (39) and to block a fluid connection from the redundancy supply port (39.1) of the electro-pneumatic redundancy valve (39) to the redundancy working port (39.2) of the electro-pneumatic redundancy valve (39).

11 . The electro-pneumatic brake pressure modulator (1 ) according to claim 10, wherein the bypass (37) is only configured to establish the fluid connection between the redundancy working port (39.2) of the electro-pneumatic redundancy valve (39) and the redundancy supply port (39.1) of the electro-pneumatic redundancy valve (39) if the electronic control unit (3) is de-energized.

12. The electro-pneumatic brake pressure modulator (1 ) according to claim 10 or 11 , wherein the electro-pneumatic redundancy valve (39) and the bypass (37) are integrally formed, and wherein the bypass (37) is preferably formed by a lip-seal of the electro-pneumatic redundancy valve (39), preferably a lip-seal arranged around a piston of the electro-pneumatic redundancy valve (39).

13. An electro-pneumatic braking system (200) for a vehicle (300), comprising a first brake circuit (206) including brake actuators (240a, 240b, 240c, 240d) for braking the vehicle (300), a first compressed air supply (218), and an electro-pneumatic brake pressure modulator (1) according to any of the preceding claims 1 to 12, wherein the electro-pneumatic brake pressure modulator (1) is connected to the compressed air supply (218) and connected to the first brake circuit (206) for supplying a first brake pressure (pB1) to one or more of the brake actuators (240a, 240b, 240c, 240d).

14. A vehicle (300) comprising an electro-pneumatic braking system (200) according to claim 13.

15. A method (400) for providing a redundancy function of an electro-pneumatic braking system (200), preferably an electro-pneumatic braking system (200) according to claim 13, comprising the steps of:

- providing (402) a redundancy pressure (pR) to a quick release supply port (35.1) of a quick release valve (35) of an electro-pneumatic redundancy valve assembly (15);

- switching (404) the quick release valve (35) from an exhaust state to a redundancy state for enabling fluid communication of the quick release supply port (35.1 ) and a quick release working port (35.2) by providing the redundancy pressure (pR) to a first quick release control port (35.4) of the quick release valve (35);

- providing (406) the redundancy pressure (pR) from the quick release working port (35.2) to an electro-pneumatic redundancy valve (39) of the electro-pneumatic redundancy valve assembly (15);

- providing (408) a redundancy control pressure (pRC) from the electro-pneumatic redundancy valve (39) to a relay valve control port (23.2) of a relay valve unit (13) if the redundancy pressure (pR) is provided to the electro-pneumatic redundancy valve (39) by the quick release valve (35); and

- providing (410) a brake pressure (pB1 ) dependent on the redundancy control pressure (pRC) by the relay valve unit (13).