Service brake bleeder unit for a reliable parking brake arrangement

Abstract

The invention relates to an electronically controllable pneumatic braking system (200) for a commercial vehicle, comprising a primary service brake pressure modulator (224); a primary electronic brake control unit (214), a secondary electronic brake control unit (242) which controls the first service brake circuit in the event of a fault; a secondary service brake pressure modulator (250) which is connected to the secondary electronic brake control unit (242), wherein the secondary service brake pressure modulator (250) is supplied with reservoir pressure (pV) and has a secondary working connection (250.1) for providing a redundant brake pressure (pBR1); and a parking brake arrangement (1) which is supplied with reservoir pressure (pV) and provides a parking brake pressure (pFS) for spring-loaded brake cylinders (254c-254f) at a parking brake working connection. According to the invention, a vent valve unit (400) is provided which is arranged downstream of the secondary working connection (250).1) and is connected to the secondary electronic brake control unit (242) and is provided to vent the secondary working connection (250.1) in response to a venting signal (SE1) provided by the secondary electronic brake control unit (242) in order to lower a reservoir pressure level in order to then vent the spring brake cylinder (254c-254f).

Description

[0001] The invention relates to an electronically controllable pneumatic braking system for a commercial vehicle, comprising at least one first service brake circuit with a first primary service brake pressure modulator for controlling a first primary service brake pressure to first service brake actuators on a first axle of the commercial vehicle; a primary electronic brake control unit connected via a vehicle bus to a unit for autonomous driving and receiving maneuver-related data therefrom, wherein the primary electronic brake control unit is connected to the first primary service brake pressure modulator and provides first primary switching signals thereto for switching at least one electromagnetic valve of the first primary service brake pressure modulator;a secondary electronic brake control unit connected via the vehicle bus to the autonomous driving unit or a redundant autonomous driving unit, receiving maneuver-related data therefrom, and configured to at least partially control the first service brake circuit in the event of a fault in the primary electronic brake control unit; a first secondary service brake pressure modulator connected to the secondary electronic brake control unit and receiving first secondary switching signals therefrom for switching at least one electromagnetic valve of the first secondary service brake pressure modulator, wherein the first secondary service brake pressure modulator is supplied with reservoir pressure and has a first secondary working port for providing a first redundant brake pressure;and a parking brake arrangement comprising a parking brake valve unit that is supplied with reservoir pressure and provides a parking brake pressure for at least one spring-loaded brake cylinder of the commercial vehicle at a parking brake working connection. The invention further relates to a method for controlling an electronically controllable pneumatic brake system of the above type and to a commercial vehicle comprising an electronically controllable pneumatic brake system of the above type.

[0002] Modern commercial vehicles often feature an electropneumatic or electronically controlled pneumatic braking system. Spring-loaded parking brakes are a component of the braking system. These are also known as parking brakes. Parking brakes operate under spring force and can be released by pressurizing spring-loaded brake cylinders or applied by venting them. Within a service braking system, valves for regulating the service brake pressure are electronically controlled. The valves can be located inside or outside of so-called axle modulators. The axle modulators can be automated or semi-automated and / or electronically controlled by an autonomous unit. The parking brakes are also electronically controlled. For example, the actuation of a solenoid valve can control the pressurization or venting of the spring-loaded brake cylinders.The spring-loaded brake cylinders can be combined with service brake cylinders, so that the spring-loaded brake and service brake act on the same brake pistons. Suitable design measures can be taken to prevent mechanical overload of the brake pistons due to the addition of braking forces from the service brakes and the spring-loaded brakes. If the service brakes are applied while the parking brakes are active, the spring-loaded brake cylinders are simultaneously ventilated to prevent the addition of the braking forces. This function is also known as an "anti-compound function."

[0003] The parking brake must be engageable by the vehicle's driver. In some markets, this is achieved by an electronic parking brake request to the parking brake system. In other markets, for safety reasons, the spring brake cylinders are vented if the reservoir pressure in the service brake system drops. The service brake and parking brake can also be assigned to different brake circuits.

[0004] Safety concepts are highly relevant for electropneumatic braking systems in modern vehicles. Especially in vehicles with automated or partially automated driving functions, braking functions must remain available, at least to a limited extent, even in the event of a fault or power failure of a control unit. This is the only way to guarantee the safety of the vehicle, its occupants, and other road users. For this purpose, it is known to provide redundancy levels that can still provide at least a limited braking function even if a primary system fails.

[0005] A level of redundancy is also desirable for the parking brake, since in most cases, vehicles can only be parked safely with the parking brake engaged. The parking brake is also known to be used as an auxiliary or supplementary brake in cases where a fault has occurred in the service braking system.

[0006] From DE 10 2021 122 497 A1 a method for operating an electropneumatic braking system for a vehicle is known, wherein the braking system comprises a service braking system and a parking braking system, wherein the parking braking system comprises at least one spring-loaded brake cylinder.The method is characterized by the steps: providing a control signal for maintaining a spring-loaded brake pressure that vents the at least one spring-loaded brake cylinder by a control unit; interrupting the provision of the control signal in the event of a fault and / or a power failure and / or a diagnostic situation of the control unit, thereby automatically terminating the maintenance of the spring-loaded brake pressure to vent the at least one spring-loaded brake cylinder; thereby triggering a spring-loaded brake failure of the vehicle by the parking brake system, wherein the venting of the spring-loaded brake pressure is carried out by a service brake venting function of the service brake system. The service brake venting function enables at least one venting path in the service brake system, in particular one that is open continuously or intermittently, for venting the at least one spring-loaded brake cylinder.The service brake venting function is implemented in particular by a valve in the service brake system, preferably an outlet valve and / or another outlet valve.

[0007] Further partially redundant systems are known from DE 10 2022 101 142 A1, DE 10 2021 122 498 A1, DE 10 2021 122 499 A1, DE 10 2020 132 875 A1 and EP 3 145 769 B1.

[0008] Although existing systems already provide a redundant option for engaging a parking brake, there is still room for further improvements. In particular, the current technology in driver-operated vehicles uses a so-called "pumping down" system, in which the driver repeatedly applies the service brake. This significantly increases air consumption, with the goal of lowering the pressure level so much that the vehicle's spring-loaded brake cylinders subsequently engage.

[0009] One problem, however, is how to increase air consumption sufficiently, and on the other hand, in vehicles with higher levels of automation (SAE Level 4 or 5), there is not always a driver who could intervene manually in this way.

[0010] It is therefore desirable to improve the engagement of a parking brake. In particular, the venting of at least one spring brake cylinder should be possible in a reliable manner and with minimal effort.

[0011] This is where the invention comes in, the object of which is to provide an improved electronically controllable pneumatic braking system in which the venting of a spring brake cylinder is possible easily and / or reliably even in the case of redundancy.

[0012] Accordingly, in an electronically controllable pneumatic braking system of the type mentioned above, a first vent valve unit is provided, which is arranged downstream of the first secondary working port and is connected to the secondary electronic brake control unit and is intended to vent the first secondary working port to the environment in response to at least one first vent signal provided by the secondary electronic brake control unit in order to lower the reservoir pressure level and then vent the spring brake cylinder. Preferably, the reservoir pressure level is reduced to such an extent that the at least one spring brake cylinder applies and thus brakes the vehicle. Spring brake cylinders are usually designed in such a way that they overcome a certain pressure level and apply it due to the spring force.The invention therefore proposes, instead of a manual pumping down by a vehicle driver, providing a bleed valve unit which, depending on a signal, which is preferably provided here by the secondary electronic brake control unit, increases the air consumption of the braking system, preferably the secondary braking system, such that the spring-loaded brake cylinders are applied. This can be provided in particular for the case in which the primary electronic brake control unit is not functioning or is not functioning properly, or in which another relevant system is not functioning or is no longer functioning properly, so that the corresponding signal is subsequently provided to the bleed valve unit in order to brake the vehicle safely.

[0013] It should be understood that the electronically controllable pneumatic braking system described herein may have at least one second service brake circuit in addition to the at least one first service brake circuit. For example, the first service brake circuit is a rear axle brake circuit, while a second service brake circuit is a front axle brake circuit. In addition, further brake circuits, such as a trailer brake circuit, or further brake circuits for further axles may be provided. It is also conceivable for brake circuits not to be divided according to axles, but to comprise other subgroups of the braking system, such as the left and right sides of the vehicle. In this respect, in addition to the first primary service brake pressure modulator, a second primary service brake pressure modulator is typically provided in the electronically controllable pneumatic braking system, which controls one or the second axle.Preferably, the primary electronic brake control unit is connected to the second primary service brake pressure modulator and provides second primary switching signals thereto for switching at least one electromagnetic valve of the second primary service brake pressure modulator.

[0014] In addition, a primary level and at least one secondary level are provided, wherein one or more valves or one or more modulators can be structurally assigned to both the primary and secondary levels. The primary level is controlled by the primary electronic brake control unit, while the secondary level is controlled by the secondary electronic brake control unit. The electronically controllable pneumatic brake system is preferably operated in the secondary level if one or more errors occur in the primary level that partially or completely prevent regular control of a service brake pressure in the primary level.

[0015] The vent valve unit preferably vents the first secondary working connection directly to the environment, without the interposition of one or more switchable valves. Direct venting to the environment is also understood if, for example, a line and / or a silencer and / or a reed valve are provided. However, it is not considered direct if one or more additional (switchable) valves are provided, which can also block the venting.

[0016] In a first preferred embodiment, a second secondary service brake pressure modulator is provided, which has a second secondary working port for providing a second redundant brake pressure. In this embodiment, it is preferably further provided that the electronically controllable pneumatic brake system has a second vent valve unit, which is arranged downstream of the second secondary working port and is connected to the secondary electronic brake control unit or another electronic control unit and is provided to vent the second secondary working port to the environment in response to at least one second vent signal.

[0017] The first and second vent valve units can be identical in construction, but can also be configured differently. Both the first and second vent signals can be either the presence or absence of an electrical current. Therefore, the absence of an electrical signal, i.e., the change from a 1 to a 0 signal, is also a vent signal within the meaning of the invention described herein.

[0018] Both the first and second secondary working ports may be connected to one or more service brake actuators, at which the first and second redundancy brake pressures are then received.

[0019] Furthermore, it is preferred that a first voltage source is provided for the electrical supply of the primary electronic brake control unit. Preferably, a second voltage source is also provided for the electrical supply of the secondary electronic brake control unit. The first and second voltage sources are preferably independent of one another, so that the failure of the first voltage source does not lead to the failure of the second voltage source, and vice versa.

[0020] In a preferred development, it is provided that the primary electronic brake control unit is combined with the first primary service brake pressure modulator as a module to form a structural unit. Such a module can also be referred to as a central module or primary central module. Preferably, the secondary electronic brake control unit is combined with the first secondary service brake pressure modulator and / or the second secondary service brake pressure modulator as a module to form a structural unit. Such a module can also be referred to as a secondary or redundant central module. Preferably, the first primary service brake pressure modulator and / or the first secondary service brake pressure modulator are dual-channel axle modulators that can output independent service brake pressures to first and second channels.

[0021] In a further preferred embodiment, the first vent valve unit is combined with the first secondary service brake pressure modulator as a module to form a single structural unit. For example, the first vent valve unit can be integrated into the first secondary service brake pressure modulator. If this is depicted as a secondary central module, the first vent valve unit can also be integrated into the secondary central module.

[0022] The second bleed valve unit, if present, can also be combined with the secondary service brake pressure modulator as a single module. If the secondary service brake pressure modulator is shown as a secondary central module, the second bleed valve unit can also be integrated into the secondary central module.

[0023] The electronically controllable pneumatic brake system preferably has at least a first compressed air supply that supplies the first primary service brake pressure modulator with supply pressure. Preferably, the first compressed air supply also supplies the first secondary service brake pressure modulator with supply pressure. If, for example, the first primary service brake pressure modulator and the first secondary service brake pressure modulator are assigned to a rear axle brake circuit (e.g., first brake circuit), the first compressed air supply supplies the rear axle brake circuit. In such an embodiment, the first vent valve unit then serves to reduce the pressure level in the first brake circuit and thus in the first compressed air supply.

[0024] The electronically controllable pneumatic brake system preferably has at least one second compressed air supply, which can also supply the first secondary service brake pressure modulator with supply pressure. Alternatively and preferably, the second compressed air supply supplies a second secondary service brake pressure modulator and / or a second primary service brake pressure modulator. For example, a second primary service brake pressure modulator is assigned to a second brake circuit, which can be a front axle brake circuit, for example. Here, a second secondary service brake pressure modulator is preferably also provided, which is intended to partially or completely replace the second primary service brake pressure modulator in the event of a fault in the second brake circuit. In this case, the second vent valve unit then serves to reduce the pressure level in the second brake circuit and thus also to vent the second compressed air supply.

[0025] The parking brake valve unit is preferably supplied by at least the first compressed air supply or the second compressed air supply, or a third compressed air supply, but preferably by both the first and second compressed air supplies. For this purpose, the parking brake arrangement can have a push-pull valve or select-high valve that connects both the first and second compressed air supplies to the spring brake cylinders in a pressure-conducting manner. Alternatively, it is also conceivable for the parking brake unit to be supplied with supply pressure directly from an air treatment system.Particularly in electronically controllable pneumatic braking systems such as those used in North America, Canada or partly also in other regions of the world, it is common for spring brake cylinders of a parking brake arrangement to be supplied by two compressed air supplies, such as in particular the first and second compressed air supplies, which are provided for a front axle brake circuit and a rear axle brake circuit.

[0026] According to a further preferred embodiment, it is provided that the first secondary working connection is connected or connectable to a first redundancy connection of the first primary service brake pressure modulator or to a second redundancy connection of one or the second primary service brake pressure modulator.

[0027] Preferably, the second secondary working port is or can be connected to a second redundancy port of the second primary service brake pressure modulator. In the present case, a first or second redundancy port is understood to be a port of a modulator or valve arrangement via which a redundant control pressure can be received and via which a relay valve of the corresponding modulator can then preferably be ventilated in order to control a pressure that would otherwise be electronically controlled at the primary level purely pneumatically and thus redundantly. For example, instead of a control pressure that would otherwise be provided by an inlet-outlet valve combination that is electromagnetically switchable and provides this control pressure, this control pressure is received via the redundancy port and then provided in an otherwise identical manner to a relay piston of a relay valve.Redundancy connections can generally be equipped with, for example, a redundancy valve, which shuts off the redundancy connection during normal operation and only releases the redundancy connection in the event of a fault.

[0028] According to a further preferred embodiment, the first vent valve unit has an electromagnetic vent switching valve which is connected via a branch to a line leading from the first secondary working connection and which has at least one blocking position and one passing position, wherein it can be switched to the passing position when energized and is in the blocking position when de-energized, and wherein the first secondary working connection is vented in the passing position. The electromagnetic vent switching valve is preferably a 2 / 2-way valve. In this way, particularly simple venting of the first secondary working connection is provided. The first vent switching valve preferably has a sufficiently large nominal diameter to effect rapid and effective venting of the first secondary working connection.In a corresponding manner, the second vent valve unit can also have a second electromagnetic vent switching valve which is connected via a branch to a line leading from the second secondary working connection and which has at least one blocking position and one passing position, wherein it can be switched to the passing position when energized and is in the blocking position when de-energized, and wherein the second secondary working connection is vented in the passing position. By having the first and second vent switching valves in the blocking position when de-energized, a safety function is implemented which ensures that the spring brake cylinders are not automatically applied in the de-energized case. The first and second vent switching valves preferably have a nominal diameter in a range of 5 to 7 mm.

[0029] In a further preferred embodiment, the first vent valve unit comprises an ABS valve unit. ABS valve units, as generally known in the prior art, can be advantageously used to vent a specific compressed air path quickly and with a short response time. In this respect, conventionally known ABS valves are particularly suitable for venting the first secondary working port or second secondary working port.

[0030] In this case, it can be provided that the ABS valve unit has a pneumatically switchable inlet valve, a pneumatically switchable outlet valve, an electromagnetic inlet valve, and an electromagnetic outlet valve. According to a further preferred embodiment, the first vent valve unit has an electromagnetic vent switching valve inserted into a line leading from the first secondary working connection. Similarly, the second vent valve unit can also have a second electromagnetic vent switching valve inserted into a line leading from the second secondary working connection.While the vent switching valves mentioned above, which are preferably designed as 2 / 2-way valves, are used in lines that branch off from the line leading from the working connection, i.e. are arranged in parallel in terms of circuitry, the electromagnetic vent switching valves mentioned here are connected in series with the first and second secondary working connection.

[0031] In this case, it can be provided that the electromagnetic bleeder switching valve has a through position and a bleed position, wherein it is de-energized in the through position and connects the first secondary working port to a line leading to a functional unit, and is energized in the bleed position, in which the first secondary working port is vented. The functional unit addressed here is preferably the first primary service brake pressure modulator, or more precisely, the redundancy port of the first primary service brake pressure modulator.

[0032] In a second aspect, the object mentioned at the outset is achieved by a method for controlling an electronically controllable pneumatic brake system, preferably an electronically controllable pneumatic brake system of a preferred embodiment described above according to an electronically controllable pneumatic brake system according to the first aspect of the invention.The method according to the second aspect of the invention preferably comprises the steps of: determining an error that prevents actuation of a parking brake function of the electronically controllable pneumatic brake system by venting spring brake cylinders by switching at least one electromagnetic valve of a parking brake valve unit; issuing an electrical venting signal by a secondary electronic brake control unit to a first vent valve unit for venting a first secondary working connection to the environment to lower a reservoir pressure level and then venting the spring brake cylinders.

[0033] It should be understood that the electronically controllable pneumatic braking system according to the first aspect of the invention and the method according to the second aspect of the invention have identical and similar sub-aspects, as set forth in particular in the dependent claims. In this respect, reference is also made in full to the above description for preferred developments of the method.

[0034] The method preferably comprises the step of controlling a first redundancy brake pressure at the first secondary working port at the instigation of the secondary electronic brake control unit. The first secondary working port is preferably a working port of the first secondary service brake pressure modulator, which is controlled by the secondary electronic brake control unit. The first redundancy brake pressure controlled by the first secondary service brake pressure modulator is vented to the environment via the venting unit activated in the event of a fault, thereby achieving increased air consumption via the first secondary service brake pressure modulator.

[0035] Furthermore, the method preferably further comprises the steps of: increasing a pressure in one or more service brake cylinders; and maintaining the increased pressure in the one or more service brake cylinders. These steps are preferably only carried out if the fault pattern permits it. By maintaining the pressure, it is preferably ensured that the remaining or increased pressure remains in the service brake cylinders and that they remain partially or fully applied. These steps are preferably carried out when the reservoir pressure is falling or low. A related advantage is that the vehicle is still secured against rolling away even when the reservoir pressure is falling. The pressure increase in the service brake cylinders is preferably carried out because during the subsequent "pumping out" no further adjustment can take place in the service brake section, but minor leaks could lead to a decrease in pressure in the service brake cylinders.

[0036] In a third aspect of the invention, the object mentioned at the outset is achieved by a commercial vehicle having at least one front axle, at least one rear axle and an electronically controllable pneumatic braking system according to one of the above-described preferred embodiments of an electronically controllable pneumatic braking system according to the first aspect of the invention.

[0037] Embodiments of the invention will now be described below with reference to the drawings. These are not necessarily intended to represent the embodiments to scale; rather, the drawings are schematic and / or slightly distorted where this is useful for explanation. With regard to additions to the teachings immediately apparent from the drawings, reference is made to the relevant prior art. It should be noted that various modifications and changes to the form and detail of an embodiment can be made without departing from the general idea of ​​the invention. The features of the invention disclosed in the description, the drawings and the claims can be essential for further developing the invention, both individually and in any combination.Furthermore, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of ​​the invention is not limited to the exact form or detail of the preferred embodiments shown and described below, or limited to an object that would be limited compared to the object claimed in the claims. In specified dimensioning ranges, values ​​lying within the stated limits are also intended to be disclosed as limit values ​​and to be used and claimed as desired. For the sake of simplicity, the same reference numerals are used below for identical or similar parts or parts with identical or similar functions.

[0038] Further advantages, features and details of the invention will become apparent from the following description of the preferred embodiments and from the drawings, which show: Fig. 1 is a schematic representation of an electronically controllable pneumatic braking system according to the invention in the form of a block diagram; Fig. 2 shows a more detailed layout of an electronically controllable pneumatic braking system of an embodiment according to the invention; Fig. 3 a first embodiment of a vent valve unit; Fig. 4 a second embodiment of a vent valve unit; and in Fig. 5 a third embodiment of a vent valve unit.

[0039] An electronically controllable pneumatic braking system 200 has an operating level 200a and at least one first redundancy level 200b. In the operating level 200a, the electronically controllable pneumatic braking system 200 comprises a primary system 212 with a primary electronic control unit 214, which controls the electronically controllable pneumatic braking system 200 in the operating level 200a. The primary electronic control unit 214 is connected via an electronic connection, here a vehicle bus 216, to a unit for autonomous driving 218, specifically a primary unit for autonomous driving 218a, and receives maneuver-related data from it, such as braking request signals SA. The primary unit for autonomous driving 218a, as well as a secondary unit for autonomous driving 218b, can be represented as instances in the unit for autonomous driving 218.Furthermore, the primary electronic brake control unit 214 is connected to a first voltage source 222 via a first supply line 220 and is supplied with electrical voltage by the first voltage source 222. The primary electronic brake control unit 214 converts the brake request signals SA and, based thereon, controls first primary switching signals, for example in the form of service brake signals SB, to a first primary service brake pressure modulator 224. The first primary service brake pressure modulator 224 is provided, for example, for a rear axle HA and can thus also be referred to as a primary rear axle service brake pressure modulator or primary rear axle modulator.

[0040] The first primary service brake pressure modulator 224 is connected to a first compressed air supply 206 and receives supply pressure pV therefrom. Based on the received service brake signals SB, the first primary service brake pressure modulator 224 controls a first service brake pressure pB1 at at least one first service brake pressure connection 232.1 and preferably a second service brake connection 232.2 (cf. Fig. 2). At the first and second service brake pressure ports 232.1, 232.2, the first service brake pressure pB1 is preferably controlled in a wheel-specific manner, and the first primary service brake pressure modulator 224 is designed as a dual-channel modulator. In other embodiments, however, the first service brake pressure port 232.1 and the second service brake pressure port 232.2 can also be combined, and the first primary service brake pressure modulator 224 can thus be designed as a single-channel axle modulator that controls the first service brake pressure pB1 in a wheel-specific manner.

[0041] For braking at least one additional axle, the electronically controllable pneumatic braking system 200 comprises, in the operating level 200a, a second primary service brake pressure modulator 236, which is provided, for example, for a front axle VA and can thus also be referred to as a front axle modulator. The second primary service brake pressure modulator 236 receives supply pressure pV from a second compressed air supply 210 and controls at least one third service brake pressure connection 236.1 and preferably a fourth service brake pressure connection 236.2 (see. Fig. 2) applies a second brake pressure pB2 in a manner that is appropriate for the axle, sideways, or wheel. The second primary service brake pressure modulator 236 can also be designed as a single-channel or dual-channel axle modulator and is preferably designed as a dual-channel axle modulator.

[0042] In the redundancy level, the electronically controllable pneumatic braking system 200 includes a secondary electronic brake control unit 242 of a secondary or redundant system 241, which is designed to control the electronically controllable pneumatic braking system 200 in the event that the operating level 200a experiences one or more faults. The secondary electronic brake control unit 242 can thus control the electronically controllable pneumatic braking system 200, for example, in the event of a power failure in the first voltage source 222, an electronic fault in the primary electronic brake control unit 214, or the like.

[0043] The secondary electronic brake control unit 242 is also connected to the autonomous driving unit 218, here to the secondary autonomous driving unit 218b, via the vehicle bus 216 and also receives maneuver-related data from it, such as brake request signals SA or redundant brake request signals SA-R. In contrast to the primary electronic brake control unit 214, the secondary electronic brake control unit 242 is connected to a second voltage source 246 via a second supply line 244 and is supplied with electrical voltage by the latter. The first and second voltage sources 222, 246 are independent of one another, so that a failure in the first voltage source 222 does not lead to a loss of the second voltage source 246, and vice versa. The primary electronic brake control unit 214 and the secondary electronic brake control unit 242 are therefore electrically independent of one another.

[0044] In order to exchange signals, the primary electronic brake control unit 214 and the secondary electronic brake control unit 242 are connected to each other via a redundancy bus 248 (see. Fig. 2). In this way, the secondary electronic brake control unit 242 can determine the availability of the primary electronic brake control unit 214 and only assume control of the electronically controllable pneumatic brake system 200 when the primary electronic brake control unit 214 is not available or not available correctly. However, in variants, communication between the primary electronic brake control unit 214 and the secondary electronic brake control unit 242 can also take place, for example, via the vehicle bus 216.

[0045] In the redundancy level 200b, a first secondary service brake pressure modulator 250 is provided, which is connected to the secondary electronic brake control unit 242 and receives from it first secondary switching signals, for example in the form of redundancy brake signals SR. In the embodiment to be described in more detail according to Fig. 2, the secondary electronic brake control unit 242 is integrated into the first secondary service brake pressure modulator 250. In other variants, however, the secondary electronic brake control unit 242 and the first secondary service brake pressure modulator 250 can also be physically separate units. The first secondary service brake pressure modulator 250 is connected to the second compressed air supply 206, which is independent of the second compressed air supply 210, so that the first compressed air supply 206 can provide supply pressure pV even if the second compressed air supply 210 has failed. In other embodiments, the first secondary service brake pressure modulator 250 can also be connected to the first compressed air supply 206 or to both the first compressed air supply 206 and the second compressed air supply 210, or even be supplied from a third compressed air supply.

[0046] The first secondary service brake pressure modulator 250 controls a first redundancy brake pressure pBR1 at a first secondary working port 250.1 as a function of the redundancy brake signal SR. The first axle, preferably the rear axle, can be braked redundantly and thus in the secondary level 200b via the first redundancy brake pressure pBR1. This can be done in a per-axle or per-wheel manner.

[0047] In the exemplary embodiment shown here, a second secondary service brake pressure modulator 252 is also provided, which is intended in particular to replace the second primary service brake pressure modulator 236. The second secondary service brake pressure modulator 252, like the first secondary service brake pressure modulator 250, receives the redundancy brake signal(s) SR and controls a second redundancy brake pressure pBR2 at a second redundancy brake pressure connection 252.1 as a function of these signals.

[0048] As with reference to Fig. 2, the brake actuators assigned to the wheels of the rear axles HA1, HA2 are designed here as double-acting brake actuators, also referred to as tri-stop cylinders. In addition to the service brake actuators 208c-208f, these each comprise a spring-loaded brake cylinder 254c-254f. The spring-loaded brake cylinders 254c-254f are designed to apply the brakes of the vehicle 300 when they are depressurized or vented. The spring-loaded brake cylinders 254c-254f can thus advantageously be used as a parking brake, since no compressed air needs to be supplied to them to brake the rear axles HA1, HA2. To release the rear wheels, the spring-loaded brake cylinders 254c-254f must be pressurized with a parking brake pressure pFS. This parking brake pressure pFS counteracts the spring brake and releases the brakes of the vehicle 300.

[0049] To provide the parking brake function, the braking system 200 comprises a parking brake assembly 1. This comprises an electropneumatic parking brake valve unit 2, which is supplied with supply pressure pV from the first compressed air supply 206 via a first supply connection 4 and with supply pressure pV from the second compressed air supply 210 via a second supply connection 5. However, the parking brake valve unit 2 could also be supplied with supply pressure only from one of the two compressed air supplies 206, 210 or from a third compressed air supply or directly from an air treatment unit.

[0050] The electropneumatic parking brake valve unit 2 comprises a parking brake control unit 6, which is connected to the autonomous driving unit 218 via the vehicle bus 216. To engage the parking brake, the autonomous driving unit 218 provides a parking brake signal SFS to the parking brake control unit 6 via the vehicle bus 216, which then provides the parking brake pressure pFS at a first spring-loaded connection 8a and a second spring-loaded connection 8b (in Fig. 1 not shown, cf. Fig. 2). The first spring-loaded connection 8a is in Fig. 2 is connected to the spring-loaded brake cylinders 254d, 254f, and the second spring-loaded brake connection 8b is connected to the spring-loaded brake cylinders 254c, 254e. By providing the parking brake pressure pFS, the electropneumatic parking brake valve unit 2 vents the spring-loaded brake cylinders 254c-254f and thus releases the parking brake. To apply the parking brake of the vehicle 300, the electropneumatic parking brake valve unit 2 can vent the spring-loaded brake connections 8a, 8b or the associated spring-loaded brake cylinders 254c-254f. This can occur in response to the receipt of corresponding second parking brake signals at the parking brake control unit 6 or when no more parking brake signals SFS are provided by the parking brake control unit 6.

[0051] In the event that a fault occurs in the braking system that prevents the parking brake from being applied or that requires the parking brake to be applied redundantly, for example, to safely stop the vehicle 300 instead of a non-functioning or improperly functioning service brake, the invention provides at least one first vent valve unit 400, which is arranged downstream of the first secondary working port 250.1 and is connected to the secondary electronic brake control unit 242 and is intended to vent the first secondary working port 250.1 to the environment in response to at least one first vent signal SE1 provided by the secondary electronic brake control unit 242. In this way, air consumption in the braking system 200 is increased, namely via an increase in the air consumption in the secondary level 200b. In the Fig. In the embodiment shown in Figure 1, the arrangement is only schematic, and even if the first vent valve unit 400 is shown graphically parallel to the path of the first redundant brake pressure pBR1, it should be understood that the first vent valve unit 400 is actually arranged downstream of it, namely, for example, by the fact that inside a module not shown in detail here, the lines are connected in such a way that the first secondary working connection 250 can be vented via the first vent valve unit 400. For this purpose, the first vent valve unit 400 has a vent 3, which here opens directly into the environment.

[0052] Furthermore, Fig. 1 that in the embodiment shown there, only the supply pressure level of the first compressed air supply 206 can be reduced via the first vent valve unit 400, but not of the second compressed air supply 210. However, there may be embodiments in which this alone leads to the engagement of the spring brake cylinders 254c - 254f. In the embodiment shown in Fig. In the exemplary embodiment shown in Figure 1, it is additionally provided that a second vent valve unit 402 is connected downstream of the second secondary working connection 252.1 of the second secondary service brake pressure modulator 252 in order to vent it. For this purpose, the second vent valve unit 402 also has a vent 3, which here opens directly into the environment. A second vent switching signal SE2 is provided to the vent valve unit 402 for switching, which here also originates from the secondary electronic brake control unit 242, but could also originate from another electronic control unit of the electronically controllable pneumatic brake system 200.

[0053] It should further be understood that the Fig. The embodiment shown in Figure 1 is merely schematic and depicts the electronically controllable pneumatic braking system 200 using functional blocks. In practice, however, the blocks can optionally be integrated and combined into different modules. Therefore, solid lines around the individual elements do not necessarily indicate a separate housing, even if this may be provided in individual cases.

[0054] Fig. 2 now illustrates a concrete embodiment of the electronically controllable pneumatic braking system 200. Identical and similar elements are provided with the same reference numerals, so that reference is made in full to the above description.

[0055] In the Fig. In the embodiment illustrated in Figure 2, the electronically controllable pneumatic braking system 200 is provided for a vehicle 300, namely, commercial vehicle 302, which, in addition to a front axle VA, also includes a first rear axle HA1 and a second rear axle HA2. However, it should be understood that the electronically controllable pneumatic braking system 200 is equally applicable to vehicles that have only one rear axle, or two front axles, or three or more rear axles.

[0056] The first compressed air supply 206 is provided here for a first brake circuit, which corresponds to a rear axle brake circuit. The second compressed air supply 210 is provided for a second brake circuit, which corresponds to a front axle brake circuit. The electronically controllable pneumatic braking system here has a total of six service brake actuators, namely first and second service brake actuators 208a, 208b on the front axle VA, as well as third, fourth, fifth, and sixth service brake actuators 208c - 208f on the first and second rear axles HA1, HA2. The service brake actuators 208c - 208f on the rear axles HA1, HA2 are combined with the spring-loaded brake cylinders 254c - 254f to form so-called Tri-Stop cylinders.

[0057] The primary electronic brake control unit 214 is combined with the first primary service brake pressure modulator to form a module and is shown as a structural unit. The module can also be referred to as a (primary) central module and has the function of both the primary electronic brake control unit 214 and a primary rear axle modulator, which here controls the first service brake pressure pB1 at the first service brake pressure connection 232.1 and the second service brake pressure connection 232.2. This means that both the first and second rear axles HA1, HA2 are braked in the same direction, but a separate pressure is output for the left and right of the vehicle 300. The primary electronic brake control unit 214 or the central module is connected via an electrical line to the second primary service brake pressure modulator 236, which is designed here as a primary front axle modulator.In the exemplary embodiment shown here, the second primary service brake pressure modulator 236 has no intelligence of its own; rather, the electromagnetic valves provided there in a known manner are switched directly by the primary electronic brake control unit 214 using the service brake signals SB. Depending on the service brake signals SB, a second service brake pressure pB1 is applied to the front axle VA in a manner appropriate to the axle, since the second primary service brake pressure modulator 236 is designed here as a single-channel modulator. To achieve wheel-specific braking, the electronically controllable pneumatic brake system 200 in the exemplary embodiment shown here has first and second ABS valves 238a, 238b, which are controlled in a known manner by the primary electronic brake control unit 214.For this purpose, the primary electronic brake control unit 214 also receives wheel speed signals from first and second wheel speed sensors 239a, 239b on the front axle VA. Wheel speed sensors 239c, 239d, 239e, 239f are also provided on the first and second rear axles HA1, HA2. All wheel speed sensors 239a-239f are wired directly to the primary electronic brake control unit 214 and provide wheel speed signals thereto. The primary electronic brake control unit 214 is as described in . Fig. 1 is connected to the autonomous driving unit 218 via the vehicle bus 216.

[0058] The primary electronic brake control unit 214 and also the first primary service brake pressure modulator 224, i.e., the central module as a whole, are supplied with electrical energy by the first voltage source 222. During normal operation, the primary electronic brake control unit 214 receives maneuver-related data from the autonomous driving unit 218, such as, in particular, brake request signals, trajectory data, and the like, and uses this to determine the service brake pressure to be provided for individual axles or wheels. At the first and second rear axles HA1, HA2, the central module can directly control the first service brake pressure pB1 accordingly; at the front axle VA, the central module provides the brake signals SB to the second primary service brake pressure modulator 236 in order to switch valves there accordingly and control the second service brake pressure pB2.If wheel slip occurs, the central module can react immediately on the rear axles HA1, HA2 and switch the first and second ABS valves 238a, 238b on the front axle VA.

[0059] The secondary electronic brake control unit 242 is provided as a first redundancy level in the secondary system 241. The secondary electronic brake control unit 242 is combined with both the first secondary service brake pressure modulator 250 and the second secondary service brake pressure modulator 252 to form a module, which can be referred to as a secondary or redundant central module.While the (primary) central module, comprising the primary electronic brake control unit 214 and the first primary service brake pressure modulator 224, is only supplied with supply pressure pV from the first compressed air supply 206, since the central module only controls the rear axle brake circuit, the redundant central module, comprising the secondary electronic brake control unit 242, the first secondary service brake pressure modulator 250 and the second secondary service brake pressure modulator 252, is also connected to the second compressed air supply 210, since it also controls the front axle VA.

[0060] The redundant central module is also connected to an autonomous driving unit 218 (for example, to the second instance 218b) via the vehicle bus 216 and receives maneuver-related data, trajectory data, or the like from the autonomous driving unit 218. In the event that the central module does not function or does not function properly, the redundant central module can take over control of the braking system 200.

[0061] This is provided in the embodiment shown here as follows: The first redundancy brake pressure pBR1, which is a control pressure here, is output at a first secondary working port 250.1. The first redundancy brake pressure pBR1 is provided for the first and second rear axles HA1, HA2. The first vent valve unit 400 described above is initially provided downstream of the first secondary working port 250.1. The first redundancy brake pressure pBR1, which is normally passed on by this vent valve unit, is then provided via a first shuttle valve, preferably select-high valve 260, to a first redundancy port 263 of the first primary service brake pressure modulator 224, via which redundancy port the first service brake pressure pBR1 can be output redundantly in the event that the primary electronic brake control unit 214 is de-energized and thus the first primary service brake pressure modulator 224 is also de-energized.The first primary service brake pressure modulator 224 is capable of converting the received first redundancy brake pressure pBR1 purely pneumatically, for example, by supplying it to a relay valve control piston, and, depending thereon, redundantly controlling the first service brake pressure pB1. Likewise, the redundant central module controls a second redundancy brake pressure pBA2 at a second secondary working port 252.1 of the second secondary service brake pressure modulator 252. This second redundancy brake pressure pBA2 is initially provided to the second vent valve unit 402 and is then normally forwarded by the latter and provided via a second select-high valve 262 to a second redundancy port 264 of the second primary service brake pressure modulator 236. The latter is then capable of converting the second redundancy brake pressure pBR2 purely pneumatically and thus controlling the second service brake pressure pB2 purely pneumatically and redundantly.

[0062] The electronically controllable pneumatic braking system 200 shown here also provides a second redundancy level or human redundancy level, in which a driver must intervene. A brake signal transmitter 266 is provided for this purpose, although this can be omitted in higher levels of automation. The brake signal transmitter 266 is electrically connected to both the primary electronic brake control unit 214 and the secondary electronic brake control unit 242 and can provide them with brake signal transmitter signals, so that these two electronic control units can also be capable of implementing braking requests manually initiated by a vehicle driver via the brake signal transmitter 266. The brake signal transmitter 266 is also connected to the second compressed air supply 210 and receives supply pressure pV from the second compressed air supply 210.By actuating a brake pedal of the brake value transmitter 266, a pneumatic brake value transmitter brake pressure pBW is controlled, which is then also provided to the first and second select-high valves 260, 262, so that it can be provided as an alternative to the first and second redundancy brake pressures pBR1, pBR2 at the corresponding first and second redundancy connections 263, 264. Therefore, in the event that the electronically controllable pneumatic brake system 200 is de-energized, but the first and second compressed air reservoirs 206, 210 are still sufficiently filled, a purely pneumatic and manually controlled braking can be achieved via the brake value transmitter 266.

[0063] The parking brake arrangement 1 is in Fig. 2 basically like in Fig. 1. It has a parking brake valve unit 2 and a parking brake control unit 6, wherein the parking brake control unit 6 is connected to the autonomous driving unit 218 via the vehicle bus 216 and can receive parking brake signals from it, for example. However, the primary electronic control unit 214 could also request such parking brake signals via the vehicle bus 216, for example to park the vehicle 300 or to use the parking brake assembly 1 as an additional brake or auxiliary brake. In addition, the parking brake assembly 1 is connected to a so-called push-pull valve 268, via which, in the embodiment shown here, a driver can also electrically request that the spring brake cylinders 254c-254f be vented. For this purpose, the push-pull valve 268 is also electrically connected to the parking brake control unit 6.

[0064] In the embodiment shown, the parking brake assembly 1 comprises a relay valve 8, which is shown separately here and receives the parking brake pressure pFS or a parking brake control pressure derived therefrom from the parking brake valve unit 2. The relay valve 8 can then amplify this pressure and transmit it accordingly to the spring-loaded brake cylinders 254c-254f. For this purpose, the relay valve 8 can additionally be connected to the first and second compressed air reservoirs 206, 210. The first service brake pressure pB1 is also supplied to the relay valve 8 in order to implement an anti-compound function.

[0065] Will now be as with reference to Fig. 1, the first and second vent valve units 400, 402 are switched such that the first secondary working port 250.1 and the second secondary working port 252.1 are vented, the compressed air consumption in the redundancy level is increased such that the supply pressure level drops. Since this affects both the first and the second compressed air supply 206, 210, the supply pressure level drops overall, so that once a certain threshold is undershot, the spring force provided in the spring brake cylinders 254c - 254f exceeds the counterforce built up by the parking brake pressure pFS, thus applying the spring brake cylinders 254c - 254f and braking the vehicle 300.

[0066] In the exemplary embodiment shown here, a trailer control valve 280 is also provided, which in a known manner has a red and a blue or yellow coupling head and is also connected to the first and second compressed air supply 206, 210. The trailer control valve 280 is electrically controlled directly from the primary electronic brake control unit 214 and does not necessarily have to have its own intelligence. It can also be controlled purely pneumatically from the front axle brake circuit and, for this purpose, is also connected to the second select-high valve 262, namely an outlet of the second select-high valve 262, in order to receive the second redundant brake pressure pBR2 or brake signal transmitter pressure pBW in order to also brake the trailer redundantly.To implement a parking brake function in the trailer, the trailer control valve 280 is also connected to the parking brake arrangement 1 and can receive, for example, parking brake pressure pFS from it.

[0067] The Fig. 3 to 4 now show three different embodiments of a first and second vent valve unit 400, 402, respectively. Even if the Fig. 3 to 5 are described only with reference to the first vent valve unit 400, it should be understood that the second vent valve unit 402 can be formed identically.

[0068] In a first in Fig. In the embodiment shown in Figure 3, the first bleed valve unit 400 comprises an electromagnetic bleed switching valve 404, which is connected via a branch 406 to a line 408, which connects the first secondary working connection 250.1 on the one hand and the first select-high valve 260 on the other hand, or the first primary service brake pressure modulator. The line 408 carries the first redundancy brake pressure pBR1. The bleed switching valve 404 is designed here as a 2 / 2-way valve 405 and is de-energized in the Fig. 3. It is energized in the position shown in Fig. 3 not shown, connects the branch 406 with the vent 3. The vent switching valve 404 is controlled by providing the first vent switching signal SE1 from the Fig. 3 shown locking position into the Fig. 3 not shown pass position switched.

[0069] In the Fig. 4, the vent switching valve 404 is inserted directly into the line 408, and not into a branch 406. The vent switching valve 404 is in the embodiment shown in Fig. 4, it is designed as a 3 / 2-way valve 409 and has a through position and a vent position. It is de-energized in the position shown in Fig. 4 and when the vent switching valve SE1 is provided, the 3 / 2-way valve 409 is switched to the vent position in which the first secondary working connection 250.1 is connected to the vent 3.

[0070] In the Fig. The third exemplary embodiment of the vent valve unit 400 shown in Figure 5 includes an ABS valve unit 410. The ABS valve unit 410 is essentially configured as known in the prior art. In the embodiment shown here, it includes a pneumatically switchable inlet valve 412, a pneumatically switchable outlet valve 414, an electromagnetic inlet valve 416, and an electromagnetic outlet valve 418. The electromagnetic inlet and outlet valves 416, 418 can be switched via the first vent switching signals SE1 and are thus also connected to the secondary electronic brake control unit 242. The electromagnetic inlet valve 416 is connected via a first control line 420 to a pneumatic control connection of the pneumatically switchable inlet valve 412 and the electromagnetic outlet valve 418 is connected via a second control line to a pneumatic control connection of the pneumatically switchable outlet valve 414.Both electromagnetic valves 416, 418 are de-energized in the position shown in . Fig. 5, in which the first control line 420 is connected to the vent 3 via the electromagnetic inlet valve 416, while the pneumatic control connection of the pneumatically switchable outlet valve 414 is acted upon by the pressure originating from the first secondary working connection 250.1, in particular the first redundancy brake pressure pBR1, and thus also in the Fig. 5. However, when the first redundancy brake pressure pBR1 is provided, the pneumatically switchable inlet valve 412 is automatically switched to the position shown in Fig.5, so that it is then in the through position and the first redundancy brake pressure pBR1 can be passed through to the first select-high valve 460 or to the first redundancy connection 263. Since the second control line 422 is pressurized with precisely this pressure, the return at the pneumatically switchable outlet valve 414 does not change the switching position, so that the vent 3 remains blocked. If, on the other hand, the electromagnetic outlet valve 418 is energized, no more pressure is output in the second control line 422, so that when the pneumatically switchable inlet valve 412 is open, the pneumatically switchable outlet valve 414 also switches automatically and thus connects the first secondary working connection 250.1 to the vent 3, thereby achieving the increased air consumption described above.This can be stopped by de-energizing the electromagnetic outlet valve 418 or by energizing the electromagnetic inlet valve 416. Reference symbol (part of the description) 1 parking brake assembly 2 parking brake valve unit 3 Ventilation 4 first supply connection of the parking brake valve unit 5 second supply connection of the parking brake valve unit 6 Parking brake control unit 8 Relay valve 200 electronically controllable pneumatic braking system 200a operating level 200b first redundancy level 206 first compressed air supply 210 second compressed air supply 212 Primary System 214 primary electronic brake control unit 216 Vehicle-BUS 218 Unit for Autonomous Driving 218a primary unit for autonomous driving 218b secondary unit for autonomous driving 220 first supply line 222 first voltage source 224 first primary service brake pressure modulator (primary rear axle modulator) 232.1 first service brake pressure connection 232.2 second service brake pressure connection 236 second primary service brake pressure modulator (primary front axle modulator) 236.1 third service brake pressure connection 236.2 fourth service brake pressure connection 238a first ABS valve 238b second ABS valve 241 Secondary system 242 secondary electronic brake control unit 244 second supply line 246 second voltage source 250 first secondary service brake pressure modulator 250.1 first secondary working connection 252 second secondary service brake pressure modulator 252.1 second secondary working connection 254c-254f spring brake cylinder 260 first select-high valve 262 second select-high valve 263 first redundancy connection 264 second redundancy connection 266 brake signal transmitter 268 Push-pull valve 280 Trailer control valve 400 first vent valve unit 402 second vent valve unit 404 vent switching valve 405 2 / 2-way valve 406 branch 408 line 409 3 / 2-way valve 410 ABS valve unit 412 pneumatically switchable inlet valve 414 pneumatically switchable outlet valve 416 electromagnetic inlet valve 418 electromagnetic exhaust valve 420 first control line 422 second control line HA1 first rear axle HA2 second rear axle pB1 first service brake pressure pB2 second service brake pressure pBR1 first redundancy brake pressure pBR2 second redundancy brake pressure pBW brake signal sensor brake pressure pFS parking brake pressure pV reservoir pressure SA brake request signals SA-R redundant brake request signals SB operating brake signals SE1 first venting signal SE2 second venting signal SFS parking brake signal SR redundancy brake signals QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2021 122 497 A1

[0006] DE 10 2022 101 142 A1

[0007] DE 10 2021 122 498 A1

[0007] DE 10 2021 122 499 A1

[0007] DE 10 2020 132 875 A1

[0007] EP 3 145 769 B1

[0007]

Claims

[1] Electronically controllable pneumatic braking system (200) for a commercial vehicle, with - at least one first service brake circuit with a first primary service brake pressure modulator (224) for controlling a first service brake pressure (pB1) to first service brake actuators (208c-208f) on a first axle of the commercial vehicle; - a primary electronic brake control unit (214) which is connected to a unit for autonomous driving (218) via a vehicle bus (216) and receives maneuver-related data from the latter, wherein the primary electronic brake control unit (214) is connected to the first primary service brake pressure modulator (224) and provides first primary switching signals (SB) thereto for switching at least one electromagnetic valve of the first primary service brake pressure modulator (224); - a secondary electronic brake control unit (242) which is connected to the autonomous driving unit (218) or a redundant autonomous driving unit via the vehicle bus (216) and receives maneuver-related data therefrom and is provided to at least partially control the first service brake circuit in the event of a fault in the primary electronic brake control unit (214); - a first secondary service brake pressure modulator (250) which is connected to the secondary electronic brake control unit (242) and receives first secondary switching signals (SR) therefrom for switching at least one electromagnetic valve of the first secondary service brake pressure modulator (250), wherein the first secondary service brake pressure modulator (250) is supplied with reservoir pressure (pV) and has a first secondary working connection (250.1) for providing a first redundancy brake pressure (pBR1); - a parking brake arrangement (1) comprising a parking brake valve unit (2) which is supplied with reservoir pressure (pV) and provides a parking brake pressure (pFS) for at least one spring brake cylinder (254c-254f) of the commercial vehicle at a parking brake working connection; wherein the electronically controllable pneumatic brake system (200) further comprises a first vent valve unit (400) which is arranged downstream of the first secondary working connection (250.1) and is connected to the secondary electronic brake control unit (242) and is provided, as a function of at least one first vent signal (SE1) provided by the secondary electronic brake control unit (242), to vent the first secondary working connection (250.1) to the environment in order to lower a reservoir pressure level in order to then vent the spring brake cylinder (254c-254f). [2] Electronically controllable pneumatic braking system (200) according to claim 1, comprising a second secondary service brake pressure modulator (252) having a second secondary working port (252.1) for providing a second redundancy brake pressure (pBR2), and further comprising a second vent valve unit (402) which is arranged downstream of the second secondary working port (252.1) and is connected to the secondary electronic brake control unit (242) or a further electronic control unit and is provided to vent the second secondary working port (252.1) into the environment in response to at least one second vent signal. [3] Electronically controllable pneumatic brake system (200) according to one of the preceding claims, comprising a first voltage source (222) for electrically supplying the primary electronic brake control unit (214) and a second voltage source (246) for supplying the secondary electronic brake control unit (242). [4] Electronically controllable pneumatic brake system (200) according to one of the preceding claims, wherein the primary electronic brake control unit (214) is combined with the first primary service brake pressure modulator (224) as a module to form a structural unit. [5] Electronically controllable pneumatic brake system (200) according to one of the preceding claims, wherein the secondary electronic brake control unit (242) is combined with the first secondary service brake pressure modulator (250) as a module to form a structural unit. [6] Electronically controllable pneumatic brake system according to one of the preceding claims, wherein the first vent valve unit is combined with the first secondary service brake pressure modulator (250) as a module to form a structural unit. [7] Electronically controllable pneumatic brake system (200) according to one of the preceding claims, comprising at least one first compressed air supply (206) which supplies the first primary service brake pressure modulator (224) and the first secondary service brake pressure modulator (250) with supply pressure (pV). [8] Electronically controllable pneumatic braking system (200) according to one of the preceding claims, comprising at least one second compressed air supply (210) which supplies a second secondary service brake pressure modulator (252) with supply pressure (pV). [9] Electronically controllable pneumatic brake system (200) according to claims 7 and 8, wherein the parking brake valve unit is supplied with supply pressure (pV) from the first compressed air supply (206), the second compressed air supply (210), a third compressed air supply and / or directly from an air treatment unit. [10] Electronically controllable pneumatic brake system (200) according to one of the preceding claims, wherein the first secondary working port (250.1) is connected or connectable to a first redundancy port (263) of the first primary service brake pressure modulator (224) or to a second redundancy port of a second primary service brake pressure modulator (236). [11] Electronically controllable pneumatic brake system (200) according to claim 2, wherein the second secondary working port (252.1) is connected or connectable to a second redundancy port (264) of the second primary service brake pressure modulator (236). [12] Electronically controllable pneumatic brake system (200) according to one of the preceding claims, wherein the first vent valve unit (400) has an electromagnetic vent switching valve (404) connected via a branch (406) to a line (408) leading from the first secondary working connection (250.1), which has at least one blocking position and a passing position, wherein it can be switched into the passing position when energized and is de-energized in the blocking position, and wherein in the passing position the first secondary working connection (250.1) is vented. [13] Electronically controllable pneumatic braking system (200) according to one of the preceding claims, wherein the first vent valve unit (400) comprises an ABS valve unit (410). [14] Electronically controllable pneumatic braking system (200) according to claim 13, wherein the ABS valve unit (410) comprises a pneumatically switchable inlet valve (412), a pneumatically switchable outlet valve (414), an electromagnetic inlet valve (416) and an electromagnetic outlet valve. [15] Electronically controllable pneumatic brake system (200) according to one of the preceding claims, wherein the first vent valve unit (400) comprises an electromagnetic vent switching valve (404) inserted into a line (408) leading from the first secondary working connection (250.1). [16] Electronically controllable pneumatic brake system according to claim 15, wherein the electromagnetic vent switching valve (404) has a passage position and a vent position, wherein it is de-energized in the passage position and connects the first secondary working port (250.1) to a line (408) leading to a functional unit, and is energized in the vent position, in which the first secondary working port is vented (250.1). [17] Method for controlling an electronically controllable pneumatic braking system (200), preferably according to one of the preceding claims, comprising the steps: - Determining an error that prevents actuation of a parking brake function of the electronically controllable pneumatic brake system (200) by venting spring brake cylinders (254c-254f) by switching at least one electromagnetic valve of a parking brake valve unit; - Control of an electrical venting signal by a secondary electronic brake control unit (242) to at least one first venting valve unit for venting a first secondary working connection (250.1) into the environment to lower a reservoir pressure level, and then venting the spring brake cylinders (254c-254f). [18] A method according to claim 17, comprising: - Controlling a first redundancy brake pressure (pBR1) at the first secondary working connection (250.1) at the instigation of the secondary electronic brake control unit (242). [19] A method according to claim 17 or 18, comprising: - Increasing the pressure in one or more service brake cylinders; and - Maintaining the increased pressure in the one or more service brake cylinders. [20] Commercial vehicle (302) with at least one front axle, at least one rear axle and an electronically controllable pneumatic braking system (200) according to one of claims 1 to 16.

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