Failsafe bypass valve arrangement and braking system comprising a failsafe bypass valve arrangement

Abstract

The invention relates to a failsafe bypass valve arrangement (1) for a pneumatic parking brake unit (120) of an electronically controllable pneumatic braking system (100), having: - a first path (2) with an electromagnetic monostable valve (6); - a second path (4) with a bistable valve unit (12); and - a relay valve (10); wherein the first path (2) and the second path (4) receive a primary parking brake pressure (pPA) of the pneumatic parking brake unit (120), wherein, in a first stable switching position of the bistable valve unit (12), the primary parking brake pressure (pPA) is controlled at a relay valve control port (10.4) of the relay valve (10) independently of a switching position of the first monostable valve (6), and, in a second stable switching position of the bistable valve unit (12), the relay valve control port (10.4) is vented when the first monostable valve (6) is currentless in order to vent the at least one spring reservoir braking cylinder (125a, 125b).

Description

[0001] Fail-safe bypass valve arrangement and braking system comprising a fail-safe

[0002] Bypass valve arrangement

[0003] The invention relates to a fail-safe bypass valve arrangement for a pneumatic parking brake unit of an electronically controllable pneumatic braking system of a vehicle. The invention further relates to an electronically controllable pneumatic braking system and a commercial vehicle.

[0004] For autonomously operated vehicles, particularly those with automation levels 3 to 5, there is a need to provide a fail-safe system that ensures that the vehicle is parked safely in the event of a serious fault. For example, DE 10 2019 133 010 A1 discloses a system that, after the vehicle has started, switches the parking brake system back to the park state (i.e., venting the spring brake cylinders) after an initial release (i.e., venting the spring brake cylinders). Then, or at the same time, vents the spring brake cylinders via a separately provided monostable release valve. In the event of a fault, the valve then falls into a de-energized switching position, thus returning the spring brake cylinders to a vented state.However, this requires that the parking brake system is vented and thus engaged even while driving, which can potentially lead to plausibility errors in the vehicle. If the status of the parking brake is queried by another system in such a case, the parking brake will be reported as engaged and thus engaged, which can lead to a plausibility error when the vehicle is moving.

[0005] Other systems designed to apply the spring brake cylinders in the event of a serious fault are based on similar functions or use the parking brake directly to engage the spring brake. One problem that arises when the parking brake itself is used to apply the spring brake cylinders in the event of a fault is the bistability typically inherent in the parking brake. To avoid having to constantly energize one or more valves while driving, parking brake modules are typically designed to be bistable, meaning they retain their switched position when de-energized. Therefore, if the parking brake is switched to a drive state while the vehicle is moving, in which the spring brake cylinders are ventilated, this state will also be maintained when the parking brake unit is de-energized. The spring brake cylinders would only apply if there was a fault in the compressed air supply system and the supply pressure drops.Safe parking and braking of the vehicle in the event of a power outage typically cannot be achieved in this way.

[0006] Further systems that are relevant here are disclosed, for example, in DE 10 2018 108 092 A1 , WO 2018 / 172256 A1 , WO 2018 / 172268 A1 ,

[0007] DE 10 2019 106 591 A1, DE 20 2019 106 870 U1 and DE 10 2020 131 688 A1.

[0008] However, there is still a need to ensure that the vehicle is in a safe state in the event of a fault from a released, i.e., ventilated, driving position of the parking brake system. In particular, such a system should be retrofittable, i.e., connectable to existing systems, and, in particular, not lead to plausibility errors in the vehicle.

[0009] The invention solves the problem with a fail-safe bypass valve arrangement of the type mentioned at the outset by the features of claim 1. Accordingly, a first path with at least one electromagnetic first monostable valve, a second path with a bistable valve unit, and a relay valve are provided. According to the invention, the first and second paths are designed and configured to be connected via a Y-piece to a parking brake pressure port of the pneumatic parking brake unit in order to receive a primary parking brake pressure from the pneumatic parking brake unit. The first monostable valve and the bistable valve unit are arranged parallel to one another and connected to a relay valve control port of the relay valve in order to control the primary parking brake pressure received from the pneumatic parking brake unit at the relay valve control port, in particular selectively via the first monostable valve and / or the bistable valve unit.The relay valve has a relay valve working port, which is intended to be connected to at least one spring brake cylinder of the electronically controllable pneumatic brake system in order to apply the primary parking brake pressure received at the relay valve control port to the at least one spring brake cylinder with a volume boost. Furthermore, the invention provides that in a first stable switching position of the bistable valve unit, the primary parking brake pressure is applied independently of the switching position of the first monostable valve, and in a second stable switching position of the bistable valve unit, the relay valve control port is vented when the first monostable valve is de-energized in order to vent the at least one spring brake cylinder.

[0010] The fail-safe bypass valve arrangement proposed here can be integrated into existing systems, namely by connecting the first and second paths via the Y-piece to the parking brake port of an existing pneumatic parking brake unit, which is otherwise connected as usual to the at least one spring brake cylinder and via which the primary parking brake pressure is provided directly to the at least one spring brake cylinder. In a preferred embodiment, the parking brake pressure port is the parking brake working port of the parking brake unit.The term "primary parking brake pressure" refers to the pressure delivered by the parking brake unit, regardless of whether it is a working pressure that can preferably be provided directly to one or more spring brake cylinders, or a control pressure that should first be volume-amplified in order to be provided to the one or more spring brake cylinders. In one embodiment, the parking brake pressure port of the parking brake unit is a port at which a parking brake control pressure is provided. In this embodiment, the primary parking brake pressure is the parking brake control pressure.

[0011] The relay valve of the fail-safe bypass valve arrangement according to the invention is then connected with the relay valve working connection to the at least one spring brake cylinder instead of the parking brake unit, so that the fail-safe bypass valve arrangement is installed between or alternatively parallel to the parking brake unit and the at least one spring brake cylinder. Such a fail-safe bypass valve arrangement can of course already be provided at the factory, but can also be integrated particularly advantageously into existing systems, as described. It is also conceivable for such a fail-safe bypass valve arrangement to be integrated directly into a parking brake module and into the housing of an existing parking brake unit. The pressure controlled by the relay valve on the at least one spring brake cylinder is referred to as the "secondary parking brake pressure."

[0012] In the first stable switching position of the bistable valve unit, the primary parking brake pressure is controlled independently of the switching position of the first monostable valve, preferably controlled at the relay valve control connection, so that in the first stable switching position, the usual operation of the pneumatic parking brake unit is not impaired. Due to the intermediate valves, there is a low latency; however, the primary parking brake pressure controlled by the parking brake unit is equivalently controlled at the at least one spring brake cylinder, so that, if the pneumatic parking brake unit is in a drive position, the at least one spring brake cylinder is released, and if the pneumatic parking brake unit is in a park position, the at least one spring brake cylinder is vented.In the second stable switching position of the bistable valve unit, the relay valve control connection is vented when the first monostable valve is de-energized, and when the first monostable valve is energized, the primary parking brake pressure is preferably controlled at the relay valve control connection. If the first monostable valve is de-energized, regardless of the state of the pneumatic parking brake unit, i.e. regardless of whether the pneumatic parking brake unit is in a drive position or a park position, the relay valve control connection is vented and thus the at least one spring brake cylinder is also vented and thus applies. In this way, a fail-safe function can be implemented via the at least one monostable valve, which leads to the venting of the at least one spring brake cylinder in the event that a serious fault occurs that leads to the de-energization of the at least one first monostable valve.This function can be activated by switching the bistable valve unit to either the first stable switching position or the second stable switching position. While in the first stable switching position of the bistable valve unit the first monostable valve has no influence on the state of the at least one spring brake cylinder, in the second stable switching position of the bistable valve unit the cylinder can be vented via the monostable valve. A driver of the vehicle therefore preferably switches the bistable valve unit to the first stable switching position when the driver himself is driving the vehicle, and switches the bistable valve unit to the second switching position when the vehicle is driving in an automated manner and such a safety function is therefore advantageous or even necessary.

[0013] In a preferred embodiment, an electromagnetic second monostable valve is provided in the first path, which is pneumatically connected in series with the first monostable valve. This allows for further safety enhancement if the first and second monostable valves are connected in such a way that it is sufficient for one of them to be de-energized to vent the at least one spring brake cylinder. Therefore, if one of the two valves is defective and does not vent the relay valve control connection when de-energized, the second monostable valve is still provided for this purpose. The function is thus redundant.

[0014] Furthermore, it is preferred that at least the first monostable valve is de-energized in a venting position. The same preferably also applies to the second monostable valve. Both the first and the second monostable valve are preferably designed as monostable 3 / 2-way valves, alternately connecting a path leading to the relay valve control port with a path originating from the parking brake pressure port or with a vent.

[0015] In a further preferred embodiment, the fail-safe bypass valve arrangement comprises a shuttle valve with a first shuttle valve inlet, a second shuttle valve inlet, and a shuttle valve outlet. The shuttle valve is preferably designed as a select-high valve, which provides the higher of the pressure present at the first and second shuttle valve inlets to the shuttle valve outlet. The first shuttle valve inlet is preferably connected directly or indirectly to the first path, the second shuttle valve inlet to the second path, and the shuttle valve outlet to the relay valve control connection. As an alternative to such a shuttle valve, a corresponding valve arrangement with pneumatically switchable valves can also be provided, which performs the same function.

[0016] Furthermore, it is preferred that the bistable valve unit has a manually operable 3 / 2-way valve. Such a manually operable 3 / 2-way valve can be designed, for example, as a slide valve. It is preferably arranged in the driver's cab so that a vehicle driver can switch between the two modes described above: manual vehicle driving and automated mode.

[0017] Furthermore, it is preferred that the bistable valve unit has pneumatic or electromechanical bistability. Pneumatic bistability can be implemented, for example, by a pneumatically self-locking valve or a valve arrangement with a total of three valves connected in such a way that pneumatic bistability is achieved. Such circuits are known to those skilled in the art. Electromechanical bistability can be achieved, in particular, by an electromagnetic bistable valve, which preferably has a first and second magnet to thereby provide two magnetic detent positions. Such electromagnetic bistable valves are also known to those skilled in the art.

[0018] Furthermore, the fail-safe bypass valve arrangement preferably has at least one first pressure sensor for detecting a pressure that can be supplied to the relay valve control connection. In this way, a signal can be provided that detects the pressure that is or can be controlled at the relay valve control connection and can thus provide the relay valve control pressure to an electronic control unit for checking plausibility and / or for controlling the braking system. Preferably, the fail-safe bypass valve arrangement has a second pressure sensor for detecting a pressure controlled by the relay valve, so that the pressure controlled at at least one spring brake cylinder can also be detected.

[0019] Preferably, the first and / or second monostable valve are connected to a higher-level control unit, preferably a unit for autonomous driving or a control unit that performs functions for autonomous driving, and receive corresponding switching signals from this. It can be provided that, as long as the unit for autonomous driving or the corresponding control unit is functional, the switching signals are provided so that the first or second monostable valve is switched. Only when the unit for autonomous driving is de-energized, for example due to a fault, or is no longer actively outputting a signal, do the first or second monostable valves return to their stable switching positions, preferably spring-loaded, so that the relay valve control connection is subsequently vented. In a second aspect, the invention solves the problem by means of an electronically controllable pneumatic braking system with the features of claim 11.The electronically controllable pneumatic braking system accordingly comprises a parking brake unit that receives supply pressure from a parking brake compressed air supply and is configured to receive an electric or pneumatic parking brake signal and, depending on the parking brake signal, to control a primary parking brake pressure at a parking brake pressure connection. It further comprises at least one spring-loaded brake cylinder on at least one axle, a unit for autonomous driving that is connected at least via a vehicle bus to at least one further electronic brake control unit, and a fail-safe bypass valve arrangement, which is preferably designed according to one of the above preferred embodiments of a fail-safe bypass valve arrangement according to the first aspect of the invention.Both the first path and the second path of the fail-safe bypass valve arrangement are connected to the parking brake pressure port of the parking brake unit and receive the primary parking brake pressure therefrom. The relay valve working port of the bypass valve arrangement is connected to the at least one spring brake cylinder, and the first monostable valve of the fail-safe bypass valve arrangement is connected to the autonomous driving unit and receives switching signals therefrom.

[0020] It is to be understood that the fail-safe bypass valve arrangement according to the first aspect of the invention as well as the electronically controllable pneumatic braking system according to the second aspect of the invention have the same and similar sub-aspects as particularly set out in the dependent claims.

[0021] In the electronically controllable pneumatic braking system, the parking brake unit is preferably provided with a parking brake switch arranged in a driver's cab. Furthermore, the parking brake unit is preferably provided with a manually operable parking brake valve.

[0022] Preferably, the first and second pressure sensors of the bypass valve arrangement are connected to the autonomous driving unit and provide a first and second pressure signal thereto, respectively. In a third aspect, the invention achieves the object stated above by a commercial vehicle according to claim 15, which has a front axle and a 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 second aspect of the invention. It should be understood that the electronically controllable pneumatic braking system according to the second aspect of the invention and the commercial vehicle according to the third aspect of the invention have the same and similar sub-aspects, as set out in particular in the dependent claims. In this respect, reference is made in full to the above description.

[0023] 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 numerous modifications and changes to the form and detail of an embodiment can be made without deviating from the general idea of ​​the invention. The features of the invention disclosed in the description, in the drawings and in the claims can be essential for the further development of 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. For specified dimensioning ranges, values ​​within the stated limits are also intended to be disclosed as limit values ​​and to be usable and claimable 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. 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:

[0024] Fig. 1 shows an electronically controllable pneumatic braking system with a fail-safe bypass valve arrangement in a first embodiment;

[0025] Fig. 2 shows the electronically controllable pneumatic braking system according to Fig. 1 with a fail-safe bypass valve arrangement in a second embodiment;

[0026] Fig. 3 shows another electronically controllable pneumatic braking system with a bypass valve arrangement according to Fig. 1; and in

[0027] Fig. 4 shows the electronically controllable pneumatic braking system according to Fig. 1 with a fail-safe bypass valve arrangement in a third embodiment.

[0028] The figures first describe the common elements, followed by an explanation of the differences between the various embodiments. The similarities are not emphasized further, and it should be understood that, in principle, each of the embodiments can be combined with the other embodiments.

[0029] Fig. 1 illustrates an electronically controllable pneumatic braking system 100 for a vehicle 200, in particular a commercial vehicle 202. The vehicle 200 has a front axle VA and a rear axle HA, whereby this invention also encompasses vehicles 200 with more than one, namely in particular two, three or more rear axles, and also more than one, in particular two, three or four front axles. The electronically controllable pneumatic braking system 100 has a rear axle modulator 102 on the rear axle HA, which receives supply pressure pV from a first compressed air supply 103 and, depending on a braking request signal, controls a rear axle brake pressure pBHA at first and second rear axle brake actuators 104a, 104b in a known manner.Similarly, a front axle modulator 106 is provided on the front axle VA, which receives the supply pressure pV from a second compressed air supply 107 and, in a known manner, controls a front axle brake pressure pBVA to first and second front axle brake actuators 108a, 108b. First and second ABS valves 109a, 109b are also provided on the front axle VA to implement an anti-lock function.

[0030] Both the rear axle modulator 102 and the front axle modulator 106 are connected to a central module 110, which provides brake signals to both the rear axle modulator 102 and the front axle modulator 106 in a known manner. These signals are then converted by the rear axle modulator 102 and the front axle modulator 106, respectively, and provided to electromagnetic valves to thereby control the rear axle brake pressure pBHA and the front axle brake pressure pBVA, respectively. It can also be provided that the central module 110 is directly connected to electromagnetic valves of the rear axle modulator 102 and / or the front axle modulator 106, so that these do not require their own intelligence.

[0031] The electronically controllable pneumatic braking system 100 is designed here, by way of example, so that it can be operated both manually by a driver and automatically. For this purpose, the vehicle 200 initially has a brake value sensor 112 in the form of a brake pedal, which is connected here both to the central module 110 and provides brake value sensor signals thereto, and directly to the front axle modulator 106 and the rear axle modulator 102. This is not mandatory; it can be provided that the brake value sensor 112 is connected only to the central module 110, only pneumatically and / or electrically to the front axle modulator 106 and the rear axle modulator 102, or only pneumatically, for example, to the central module 110 and the front axle modulator 106. The configuration shown here is only an example, and the invention is explicitly not limited thereto.

[0032] On the rear axle HA, the electronically controllable pneumatic braking system 100 also has a parking brake circuit 115 and a parking brake unit 120. The parking brake unit 120 is designed here as a parking brake module 121 and is thus integrated as a single structural unit. However, it can also be provided that the parking brake unit 120 is not designed as a parking brake module 121, but can also be implemented by separately installed valves in the vehicle 200. The parking brake unit 120 operates as known in the prior art and is designed in Fig. 1 as an electropneumatic parking brake unit. It is connected to a parking brake compressed air supply 122 (also called the third compressed air supply) and receives supply pressure pV from this. In the embodiment shown in Fig. 1, the parking brake unit 120 is connected on the one hand to the unit for autonomous driving 113 via the vehicle bus 114 and can thus receive a signal from the unit for autonomous driving 113 for parking or braking.Immobilization of the vehicle 200 is received, and on the other hand, with a parking brake switch 124, which is typically located in the driver's cab and can be operated manually by a vehicle driver. A parking position of the vehicle 200 can also be requested via the parking brake switch 124. For this purpose, the vehicle 200 has first and second spring-loaded brake cylinders 125a, 125b on the rear axle HA, which open when ventilated and apply when de-ventilated in a known manner. For this purpose, the parking brake unit 120 provides a primary parking brake pressure pPA, which can be a parking brake working pressure, to ventilate the spring-loaded brake cylinders 125a, 125b.

[0033] According to the invention, however, the primary parking brake pressure pPA is not provided directly to the first and second spring brake cylinders 125a, 125b on the rear axle HA, but rather, a fail-safe bypass valve arrangement 1 is connected between the parking brake unit 120 and the spring brake cylinders 125a, 125b. In the first exemplary embodiment shown in Fig. 1, the fail-safe bypass valve arrangement comprises a first path 2 and a second path 4, both of which receive the primary parking brake pressure pPA and, in the exemplary embodiment shown here, are connected to the parking brake pressure connection 126 via a Y-piece 5. It is crucial that the first path 2 and the second path 4 receive the same primary parking brake pressure pPA.

[0034] The first path 2 has an electromagnetically acting first monostable valve 6 and a series-connected electromagnetic second monostable valve 8. Both the first and the second monostable valves 6, 8 are de-energized in a venting position, in which the first path 2 is connected to a vent 3, while the first and the second monostable valves 6, 8 are energized in a pass-through position, in which the primary parking brake pressure pPA can be controlled through the first and the second monostable valves 6, 8. For this purpose, both the first and the second monostable valves 6, 8 are designed as 3 / 2-way valves, wherein they are arranged such that the connection of the 3 / 2-way valve downstream of the parking brake unit 120 can be alternately connected to the vent 3 and the connection facing the parking brake unit 120.

[0035] Downstream, the first path 2 is connected to a relay valve 10, which has a relay valve supply port 10.1 connected to the third compressed air supply 122 and receives supply pressure pV, a relay valve working port 10.2 (shown in Fig. 2 as two relay valve working ports, although this is only schematic and either one or two ports can be provided), a relay valve vent port 10.3, and a relay valve control port 10.4. The relay valve working port 10.2 is connected to the first and second spring brake cylinders 125a, 125b, and the relay valve control port 10.4 is connected to the first and second paths 2, 4, respectively, such that it can receive the primary parking brake pressure pPA output via the first and second paths 2, 4, respectively. In the specific embodiment shown in Fig. 1, the relay valve control port is 10.4 is initially connected to a shuttle valve 11, which is preferably designed as a select-high valve. The shuttle valve 11 has a first shuttle valve inlet.

[0036] 11.1 , which is connected to the first path 2, a second shuttle valve input

[0037] 11.2, which is connected to the second path 4, and a shuttle valve output 11.3, which is connected to the relay valve 10, preferably to the relay valve control port 10.4. The shuttle valve 11 controls the higher of the pressures present at the first and second shuttle valve inlets 11.1, 11.2 to the shuttle valve output 11.3.

[0038] The first and second monostable valves 6, 8 are electrically connected to the autonomous driving unit 113 and receive first and second switching signals S1, S2 from it. During normal operation, the first and second switching signals S1, S2 should be provided so that the first and second monostable valves 6, 8 are in the energized, i.e., pass-through, position. In this position, the primary parking brake pressure pPA is output via the first path 2, the first and second monostable valves 6, 8, and the shuttle valve 11 to the relay valve 10, which then amplifies this pressure and provides it as secondary parking brake pressure pPR to the first and second spring-loaded brake cylinders 125a, 125b, so that they are released.If a serious fault now occurs in vehicle 200, the first and / or second switching signals S1, S2 are also lost, so that the first path 2 is vented, since at least one of the first and second monostable valves 6, 8 falls into the vent position and thus connects the relay valve control connection 10.4 to the vent 3. In this case, the first and second spring-loaded brake cylinders 125a, 125b are also vented and thus apply. In this way, a fail-safe function is achieved that enables safe braking and parking of the vehicle 200.

[0039] For manual operation of the vehicle 200, it may be advantageous to bypass or deactivate this fail-safe function, which is implemented via the first and second monostable valves 6, 8. For this purpose, a bistable valve unit 12 is provided in the second path 4, which has at least a first and second stable switching position, wherein in the first stable switching position, which is shown in Fig. 1, the primary parking brake pressure pPA is provided via the second path 4 to the shuttle valve 11, more precisely at the second shuttle valve inlet 11.2, and in a second stable switching position not shown in Fig. 1, the second shuttle valve inlet 11.2 is connected to a vent 3.

[0040] If the first and second monostable valves 6, 8 are energized and in the pass-through position, the switching position of the bistable valve unit 12 has no influence on the pressure output by the relay valve 10. However, if the bistable valve unit 12 is in the first stable switching position shown in Fig. 1, a pass-through position, the switching position of the first and second monostable valves 6, 8 has no influence on the pressure output by the relay valve 10, since in any case the primary parking brake pressure pPA is output via the bistable valve unit 12 to the shuttle valve 11 and is thus also provided at the relay valve control connection 10.4. Only if the bistable valve unit 12 is switched to the second stable switching position (venting position) not shown in Fig. 1 can the fail-safe function be enabled via the first and second monostable valves 6, 8.

[0041] In the embodiment shown in Fig. 1, the bistable valve unit 12 comprises a manually operable 3 / 2-way valve 13, which is shown in Fig. 1 in a through position and can be moved into a blocking or venting position by actuating a handle 13.4. The manually operable 3 / 2-way valve 13 has a first manual valve connection 13.1, which is connected to the second path 4, specifically the part facing the Y-piece 5, and thus receives the primary parking brake pressure pPA controlled by the parking brake unit 120. The manually operable 3 / 2-way valve 13 further has a second manual valve connection 13.2, which is connected downstream to the second path 4 and leads to the relay valve 10, more precisely connected to the second shuttle valve inlet 11.2 in the embodiment shown in Fig. 1. In addition, the manually operated 3 / 2-way valve 13 has a third manual valve connection 13.3, which is connected to a vent 3. In the through position, the first manual valve connection 13.1 is connected to the second manual valve connection 13.2, and in the vent position, the second manual valve connection 13.2 is connected to the third manual valve connection 13.3. The manually operable 3 / 2-way valve 13 is preferably arranged in the driver's cab of the vehicle 200, but can also be located somewhere else on the vehicle.

[0042] Advantageously, a vehicle driver can move the manually operable 3 / 2-way valve 13 into the open position shown in Fig. 1, so that the primary parking brake pressure pPA output by the parking brake unit 120 is always output via the second path 4, regardless of the position of the first and second monostable valves 6, 8 at the relay valve control port 10.4. The first and second spring-loaded brake cylinders 125a, 125b are thus ventilated exactly as specified by the parking brake unit 120. Even if the unit for autonomous driving 113 fails, the position of the first and second spring-loaded brake cylinders 125a, 125b does not change, provided that the primary parking brake pressure pPA output by the parking brake unit 120 also remains the same. The vehicle 200 therefore behaves like a normal manually operated vehicle.A vehicle driver should engage this switching position when driving the vehicle 200 themselves. However, if the vehicle 200 is operated in automated or semi-automated mode, it is advantageous to move the manually operated 3 / 2-way valve 13 into the second switching position not shown in Fig. 1 and thus connect the second shuttle valve inlet 11.2 to the vent 3 by connecting the second manual valve connection 13.2 to the third manual valve connection 13.3. In this switching position, no pressure is transmitted via the second path 4, so that the pressure present at the relay valve control connection 10.4 is always the pressure that is controlled via the first path 2.Thus, if the first and second monostable valves 6, 8 are energized, particularly because the autonomous driving unit 113 is functional and provides the first and second switching signals S1, S2, the spring brake cylinders 125a, 125b are vented again as specified by the parking brake unit 120. However, if a serious error occurs that results in the first and / or second switching signals S1, S2 no longer being provided, the first shuttle valve input 11.1 is also vented, so that the relay valve control connection 10.4 is subsequently also vented, which in turn leads to the venting of the first and second spring brake cylinders 125a, 125b, so that the vehicle stops and is immobilized.

[0043] Fig. 2 now illustrates a second embodiment of the fail-safe bypass valve arrangement 1, wherein identical and similar elements are provided with the same reference numerals, so that reference is made in full to the above description. The essential difference from the first embodiment (Fig. 1) is that instead of the manually operated 3 / 2-way valve 13 in the second embodiment, the bistable valve unit 12 has an electromagnetic bistable valve 14. The electromagnetic bistable valve 14 is connected in the same way as has already been described with regard to the manually operated 3 / 2-way valve 13. The bistable valve 14 has a first bistable valve connection 14.1, which is connected to the second path 4 such that it permanently receives the primary parking brake pressure pPA controlled by the parking brake unit 120. A second bistable valve connection 14.2 is connected to the relay valve 10 orconnected to the second shuttle valve inlet 11.2, and a third bistable valve connection 14.3 is connected to a vent 3. The bistable valve 14 has, in a known manner, two magnetic detent positions, which are implemented here, for example, by a first magnet 15.1 and a second magnet 15.2, which are controlled separately via third and fourth switching signals S3, S4. The bistable valve 14, like the first and second monostable valves 6, 8, is connected to the unit for autonomous driving 113, but can also be connected to a further control unit, in particular one that performs autonomous driving tasks. The exemplary embodiment shown in Fig. 2 is particularly advantageous if, for example, an electrical or electronic switch for switching the autonomous driving operation on or off is provided in the driver's cab of the vehicle 200.For example, in the embodiment shown here, it can be provided that the unit for autonomous driving, when automated operation is requested, switches the bistable valve 14 into the venting position not shown in Fig. 2 in order to activate the fail-safe function via the first and second monostable valves 6, 8.

[0044] The embodiment shown in Fig. 3 differs from the embodiment shown in Fig. 1 only in the electronically controllable pneumatic brake system 100, namely in that no electropneumatic parking brake unit 120 is provided, but rather a purely pneumatic parking brake valve 128, which can be moved, in particular, manually into an engagement and release position. In this case, the parking brake valve 128 controls the primary parking brake pressure pPA, which is then fed into the first and second paths 2, 4 as described above. All other elements are constructed analogously to Fig. 1, and reference is made to the above description.

[0045] The embodiment shown in Fig. 4 is in turn based on the embodiment shown in Fig. 1, with two main differences to be discussed here.

[0046] First, a first pressure sensor 16 and a second pressure sensor 17 are provided, which provide a first pressure signal S5 and a second pressure signal S6, respectively, here specifically to the unit for autonomous driving 113, whereby the first and second pressure signals S5, S6 could also be provided to other electronic control units. The first pressure sensor 16 measures the secondary parking brake pressure pPR output by the relay valve 10, and the second pressure sensor 17, in the embodiment shown here, measures the pressure output by the manually operable 3 / 2-way valve 13 and can thus detect the switching position of the manually operable 3 / 2-way valve. The second pressure sensor 17 can therefore generally be used to detect the state of the bistable valve unit 12. The first pressure sensor 16, on the other hand, detects the state of the spring-loaded brake cylinders.Preferably, a third pressure sensor (not shown here) can detect the pressure output at the parking brake pressure connection 126 in order to detect the state of the parking brake unit. It should be understood that the first pressure sensor 16 and / or second pressure sensor 17 can also be provided in the previously described exemplary embodiments according to FIGS. 1 to 3. Furthermore, the variant according to FIG. 4 dispenses with the shuttle valve 11. Instead, the bistable valve unit 12 and the first and second monostable valves 6, 8 are wired differently in order to still achieve the fail-safe function. Specifically, the second manual valve connection 13.2 is not directly connected to the relay valve 10, but rather to the second monostable valve 8, specifically that connection of the second monostable valve 8 which is connected to the vent 3 in the first embodiment (FIG. 1). In this respect, the first monostable valve 8 can be arranged in the configuration shown in FIG.4, either the first path 2 or the second path 4 can be connected to the relay valve 10. A first monostable valve connection 8.1 is connected to the first monostable valve 6 and can receive the primary parking brake pressure pPA from it. A second monostable valve connection 8.2 is connected to the relay valve 10, more precisely to the relay valve control connection 10.4, and a third monostable valve connection 8.3, which is connected to the vent 3 in Fig. 1, is connected to the second manual valve connection 13.2 in Fig. 4. When de-energized, the second monostable valve 8 is in the switching position shown in Fig. 4 and connects the second manual valve connection 13.2 to the second monostable valve connection 8.2. When energized, the second monostable valve 8 is in the switching position not shown in Fig. 4 and connects the first monostable valve connection 8.1 to the second monostable valve connection 8.2.

[0047] Reference symbol (part of the description)

[0048] 1 Fail-safe bypass valve arrangement

[0049] 2 first path

[0050] 3 Ventilation

[0051] 4 second path

[0052] 5 Y-piece

[0053] 6 first monostable valve

[0054] 8 second monostable valve

[0055] 8.1 first monostable valve connection

[0056] 8.2 second monostable valve connection

[0057] 8.3 third monostable valve connection

[0058] 10 Relay valve

[0059] 10.1 Relay valve supply connection

[0060] 10.2 Relay valve working connection

[0061] 10.3 Relay valve vent connection

[0062] 10.4 Relay valve control connection

[0063] 11 shuttle valve

[0064] 11.1 first shuttle valve inlet

[0065] 11.2 second shuttle valve inlet

[0066] 11.3 Shuttle valve output

[0067] 12 bistable valve unit

[0068] 13 manually operated 3 / 2-way valve

[0069] 13.1 first manual valve connection

[0070] 13.2 second manual valve connection

[0071] 13.3 third manual valve connection

[0072] 13.4 Handle

[0073] 14 electromagnetic bistable valve

[0074] 14.1 first bistable valve connection

[0075] 14.2 second bistable valve connection

[0076] 14.3 third bistable valve connection

[0077] 15.1 first magnet

[0078] 15.2 second magnet

[0079] 16 first pressure sensor 17 second pressure sensor

[0080] 100 electronically controllable pneumatic braking system

[0081] 102 Rear axle modulator

[0082] 103 first compressed air supply

[0083] 104a, 104b Rear axle brake actuators

[0084] 106 front axle modulator

[0085] 107 second compressed air supply

[0086] 108a, 108b Front axle brake actuators

[0087] 109a, 109b ABS valves

[0088] 110 Central module

[0089] 112 brake signal sensor

[0090] 113 Unit for Autonomous Driving

[0091] 114 vehicle bus

[0092] 115 Parking brake circuit

[0093] 120 Parking brake unit

[0094] 121 Parking brake module

[0095] 122 third compressed air supply / parking brake compressed air supply

[0096] 124 Parking brake switch

[0097] 125a, 125b spring brake cylinder

[0098] 126 Parking brake pressure connection

[0099] 128 Parking brake valve

[0100] 200 vehicles

[0101] 202 commercial vehicles

[0102] HA rear axle pBHA rear axle brake pressure pBVA front axle brake pressure pPA primary parking brake pressure pPR secondary parking brake pressure pV reservoir pressure

[0103] 51 first switching signal

[0104] 52 second switching signal

[0105] 53 third switching signal

[0106] 54 fourth switching signal

[0107] 55 first pressure signal S6 second pressure signal

[0108] VA front axle

Claims

Patent claims 1. Fail-safe bypass valve arrangement (1) for a pneumatic parking brake unit (120) of an electronically controllable pneumatic brake system (100) of a vehicle (200), the fail-safe bypass valve arrangement (1) comprising: - a first path (2) with at least one electromagnetic first monostable valve (6); - a second path (4) with a bistable valve unit (12); and - a relay valve (10); wherein the first path (2) and the second path (4) are provided to be connected via a Y-piece (5) to a parking brake pressure connection (126) of the pneumatic parking brake unit (120) in order to receive a primary parking brake pressure (pPA) of the pneumatic parking brake unit (120), wherein the first monostable valve (6) and the bistable valve unit (12) are arranged in parallel and are connected to a relay valve control connection (10.4) of the relay valve (10) in order to control the primary parking brake pressure (pPA) received from the pneumatic parking brake unit (120) at the relay valve control connection (10.4), and wherein the relay valve (10) has a relay valve working connection (10.2) which is provided to be connected to at least one spring brake cylinder (125a, 125b) of the electronically controllable pneumatic brake system (100) in order to the relay valve control connection (10.4) to control the received primary parking brake pressure (pPA) in a volume-amplified manner to the at least one spring brake cylinder (125a, 125b); wherein in a first stable switching position of the bistable valve unit (12), the primary parking brake pressure (pPA) is controlled at the relay valve control connection (10.4) independently of a switching position of the first monostable valve (6), and in a second stable switching position of the bistable valve unit (12), the relay valve control connection (10.4) is vented when the first monostable valve (6) is de-energized in order to vent the at least one spring brake cylinder (125a, 125b).

2. Fail-safe bypass valve arrangement (1) according to claim 1, comprising an electromagnetic second monostable valve (8) in the first path (2) which is pneumatically connected in series with the first monostable valve (6).

3. Fail-safe bypass valve arrangement (1) according to claim 1 or 2, wherein at least the first monostable valve (6) is de-energized in a venting position.

4. Fail-safe bypass valve arrangement (1) according to one of the preceding claims, comprising a shuttle valve (11) with a first shuttle valve inlet (11.1), a second shuttle valve inlet (11.2) and a shuttle valve outlet (11.3), wherein the first shuttle valve inlet (11.1) is connected to the first path (2), the second shuttle valve inlet (11.2) is connected to the second path (4), and the shuttle valve outlet (11.3) is connected to the relay valve control connection (10.4), such that the higher of the pressure applied to the first shuttle valve inlet (11.1) and second shuttle valve inlet (11.2) is provided at the shuttle valve outlet (11.3).

5. Fail-safe bypass valve arrangement (1) according to one of the preceding claims, wherein the bistable valve unit (12) has a manually operable 3 / 2-way valve (13).

6. Fail-safe bypass valve arrangement (1) according to one of the preceding claims, wherein the bistable valve unit (12) has a pneumatic or electromechanical bistability.

7. Fail-safe bypass valve arrangement (1) according to one of the preceding claims, wherein the bistable valve unit (12) comprises an electromagnetic bistable valve (14) with a first magnet (15.1) and a second magnet (15.2).

8. Fail-safe bypass valve arrangement (1) according to one of the preceding claims, comprising at least one first pressure sensor (16) for detecting a pressure that can be supplied to the relay valve control connection (10.4).

9. Fail-safe bypass valve arrangement (1) according to claim 2, wherein the second monostable valve (8) is a second 3 / 2-way valve, and alternately connects the first monostable valve (6) and the bistable valve unit (12) to the relay valve (10).

10. Fail-safe bypass valve arrangement (1) according to one of the preceding claims, wherein the first monostable valve (6) is connected to a unit for autonomous driving (113) or control unit which performs functions for autonomous driving and receives a first switching signal (S1) therefrom. 11 . Electronically controllable pneumatic braking system (100), with - a parking brake unit (120) which receives supply pressure (pV) from a parking brake compressed air supply (122) and is configured to receive an electrical or pneumatic parking brake signal and, in dependence on the parking brake signal, to control a primary parking brake pressure (pPA) at a parking brake pressure connection (126); - at least one spring brake cylinder (125a, 125b) on at least one axle (HA); - a unit for autonomous driving (113) which has at least one vehicle bus (114) is connected to at least one further electronic brake control unit (110); and - a fail-safe bypass valve arrangement (1) according to one of claims 1 to 10, wherein both the first path (2) and the second path (4) are connected to the parking brake pressure connection (126) of the parking brake unit (120) and receive the primary parking brake pressure (pPA) therefrom, wherein the relay valve working connection (10.2) is connected to the at least one spring brake cylinder (125a, 125b), and wherein the first monostable valve (6) is connected to the unit for autonomous driving (113) and receives switching signals (S1) therefrom.

12. Electronically controllable pneumatic braking system (100) according to claim 11, wherein the parking brake unit (120) has a parking brake switch (124) arranged in a driver's cab.

13. Electronically controllable pneumatic braking system (100) according to claim 11, wherein the parking brake unit (120) has a manually operable parking brake valve (126).

14. Electronically controllable pneumatic braking system (100) according to one of claims 11 to 13 and 8, wherein the first pressure sensor (16) is connected to the autonomous driving unit (113) and provides a first pressure signal (S5) thereto.

15. Commercial vehicle (202) with a front axle (VA) and a rear axle (HA) and an electronically controllable pneumatic braking system (100) according to one of claims 11 to 14.

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