Electropneumatic parking brake device having a parking brake redundancy unit

Abstract

The invention relates to a parking brake device (1) for feeding air into and discharging air from spring brake cylinders (254c, 254d, 254e, 254f), comprising a parking brake value unit (2) and a parking brake redundancy unit (10) which is designed to connect a parking compressed-air path (12) to an air discharge means (14) independently of the parking brake valve unit (2) in order to discharge air from at least one spring brake cylinder (254c, 254d, 254e, 254f), wherein: the parking brake redundancy unit (10) has a first air discharge path (18) which comprises - a main connection point (16) for receiving a pressure (pFS, pV) of the parking compressed-air path (12), - a first redundancy valve unit (20), - a second redundancy valve unit (22), and - a redundancy air discharge means (14); the first redundancy valve unit (20) can be controlled by a first control unit (26); the second redundancy valve unit (22) can be controlled by a second control unit (28); and the parking brake redundancy unit (10) is designed to connect the main connection point (16) to the redundancy air discharge means (14) in order to discharge air from the main connection point (16). The invention also relates to a brake system (200), to a vehicle (300), and to a method.

Description

[0001] Electropneumatic parking brake system with parking brake redundancy unit

[0002] The invention relates to an electropneumatic parking brake device for pressurizing and venting one or more spring-loaded brake cylinders of an at least partially electronically controllable pneumatic braking system for a vehicle, comprising an electropneumatic parking brake valve unit with a supply connection for receiving supply pressure from a compressed air supply, and a parking brake control unit, wherein the parking brake valve unit is configured to control a parking pressure at at least one spring-loaded connection depending on a parking brake signal. The invention further relates to an electronically controllable pneumatic braking system and a vehicle comprising such a braking system.

[0003] Modern commercial vehicles often feature an electronically controlled pneumatic braking system. The braking system typically includes spring-loaded parking brakes, also known as parking brakes. Parking brakes operate under spring force and can be released or engaged by applying a parking pressure to spring-loaded brake cylinders. To regulate service brake pressure, valves within a service brake system are electronically controlled. The valves can be located inside or outside 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 actuation 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 overloading 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 vented at the same time to prevent the braking forces from adding up. This function is also known as an "anti-compound function." The parking brake must be engageable by the vehicle driver. In some markets, this is achieved by an electronic parking brake request to the parking brake system. In other markets, venting of the spring-loaded brake cylinders is provided for safety reasons 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 a 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] In addition to the service brakes, a redundancy level is also desired for the parking brake, since in most cases vehicles can only be parked safely with the parking brake engaged. In order to expand functionality and, in particular, to be able to ventilate and thus release the corresponding spring-loaded cylinders of the parking brake regardless of the occurrence of a fault on one of the various levels, be it the operating level or a redundancy level of the braking system, it is desirable for the spring-loaded brake cylinders to be able to be controlled via two independent paths in order to vent them. This is intended to increase the range of functions and operational readiness of the vehicle. By providing a redundancy level, the vehicle can be parked safely even in the event of one or more faults in the braking system.

[0006] From DE 102021 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 following 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 event 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 performed by a service brake venting function of the service brake system. The service brake venting function enables at least one venting path, in particular one that is open continuously or intermittently, in the service brake system 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 102022 101 142 A1 , DE 10 2021 122 498 A1 , DE 102021 122 499 A1 , DE 102020 132 875 A1 and EP 3 145 769 B1.

[0008] Even though existing systems already provide a partially redundant option for engaging or releasing a parking brake, there is still room for further improvements. In particular, the aforementioned known options can be complex to assemble and manufacture, as the connection to the service brake system may require long cable runs. Furthermore, the achievable system dynamics may be limited.

[0009] 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 reliably and with minimal effort.

[0010] This is where the invention comes in. Its object is to provide an improved electropneumatic parking brake device that enables the simple and / or reliable venting of a spring-loaded brake cylinder, even in the case of redundancy. In a first aspect, the invention solves this problem with an electropneumatic parking brake device according to claim 1.Starting from an electropneumatic parking brake device of the type mentioned above, an electropneumatic parking brake redundancy unit is further provided, which is designed to connect a parking compressed air path to a vent, independently of the electropneumatic parking brake valve unit, for venting at least one spring brake cylinder. The parking brake redundancy unit has a first vent path comprising a main connection for receiving a pressure of the parking compressed air path, a first electropneumatic redundancy valve unit, a second electropneumatic redundancy valve unit, and a redundancy vent to the environment. The first electropneumatic redundancy valve unit can be controlled by a first control unit, and the second electropneumatic redundancy valve unit can be controlled by a second control unit that is independent of the first control unit.The parking brake redundancy unit is designed to connect the main connection to the redundancy vent via the parking brake redundancy unit's first vent path in order to vent the main connection directly into the environment. In addition to the electropneumatic parking brake valve unit, the parking brake redundancy unit is also designed to vent a spring brake cylinder of the braking system and thus engage the parking brake. For this purpose, the parking brake valve unit can connect a parking compressed air path to a vent, whereby this connection can be made independently of the electropneumatic parking brake valve unit. This allows a spring brake cylinder to be vented even if the electropneumatic parking brake valve unit is faulty, is not supplied with power, or is otherwise limited in its function.The parking compressed air path is a compressed air path assigned to the vehicle's parking brake. This can be a compressed air path directly connected to one or more spring-loaded brake cylinders. For example, the parking compressed air path can be a compressed air path between the spring-loaded connection of the parking brake valve unit and the spring accumulator of the spring-loaded brake cylinder. However, it can also be provided, for example and preferably, that the parking compressed air path is a supply path that connects a compressed air supply of the brake system to the parking brake. The parking brake redundancy unit comprises at least one venting path. The first venting path connects a main connection of the parking brake redundancy unit to a redundancy vent to the environment. The redundancy vent opens directly into the environment.Therefore, no further functional units of a braking system are provided between the redundant venting and the environment. However, it can be provided that the redundant venting comprises one or more passive elements, such as a silencer and / or a line. In particular, no switchable components or modulators are arranged between the redundant venting and the environment. The direct connection of the redundant venting to the environment eliminates further sources of error. In addition, high system dynamics can be achieved. Furthermore, line lengths can be reduced, which can reduce the assembly and manufacturing costs of the parking brake device. The first venting path is preferably parallel to a primary venting path of the parking brake valve unit.The primary venting path connects the spring-loaded connection of the parking brake valve unit to a primary vent of the parking brake valve unit. The first venting path of the parking brake redundancy unit and the primary venting path of the parking brake valve unit are preferably connected to each other at the spring-loaded connection. However, it can also be provided that the first venting path and the primary venting path open into a connecting line to the spring-loaded brake cylinder. In other variants, the first venting path and the primary venting path are completely separate.

[0011] The first electropneumatic redundancy valve unit can be controlled by a first control unit, and the second electropneumatic redundancy valve unit can be controlled by a second control unit. The control units can be control units of the parking brake device, but do not have to be. Preferably, the first control unit and / or the second control unit is a service brake control unit of a braking system. The second control unit is independent of the first control unit. This can further increase the reliability of the parking brake device, since if one of the control units fails, the other control unit can continue to function. In a first preferred development, the first control unit and / or the second control unit is independent of the parking brake control unit. This can ensure that at least one of the control units is independent of the parking brake control unit.In the event that only the parking brake control unit has a fault, at least the first control unit or the second control unit continues to function. Preferably, both the first control unit and the second control unit are independent of the parking brake control unit. However, in variants, it can also be provided that the first control unit or the second control unit is formed by the parking brake control unit, or that the parking brake control unit comprises the first control unit or the second control unit.

[0012] The first electropneumatic redundancy valve unit preferably has a bistable valve unit with a first position and a second position, wherein the first position is a venting position in which the bistable valve unit allows a pneumatic connection of the main connection to the redundancy vent, and wherein the bistable valve unit interrupts the first venting path in the second switching position. In the second switching position, the bistable valve unit interrupts the first venting path and thus prevents air flow through the first venting path. The bistable valve unit can thus prevent, for example, undesired venting of a spring-loaded brake cylinder. In the first position, the bistable valve unit preferably opens the first venting path or at least allows flow through the venting path through the bistable valve unit.The bistable valve unit is stable in the first and second positions and, in particular, remains in the previously assumed position even when de-energized. The bistable valve unit thus enables, for example, switching between an autonomous operating mode and a manual operating mode. For example, the bistable valve unit can only be in the first position in an autonomous operating mode of a braking system. In this case, venting the parking brake path using the redundant valve unit is only possible in autonomous operation, for which redundancy is particularly important. The bistable valve unit can have one or more valves that provide the bistable functionality.In a preferred embodiment, the bistable valve unit is or comprises a bistable valve, preferably an electrically switchable bistable valve, particularly preferably an electrically switchable solenoid-operated bistable valve. In other variants, however, the bistable function of the bistable valve unit can also be achieved by suitable interconnection of several valves, which do not necessarily have to be designed as bistable valves.

[0013] The first electropneumatic redundant valve unit preferably has a first monostable holding valve, which is connected in series along the first venting path with the bistable valve unit, in particular with a bistable valve of the bistable valve unit. The first monostable holding valve has only one stable state. In the de-energized state, the monostable holding valve switches to this stable state. Preferably, the monostable holding valve opens the first venting path in the de-energized state or in the stable state. In the de-energized state, the monostable holding valve then allows flow through it or is open. Preferably, the first holding valve can be switched to a closed state by the first control unit. For example, and preferably, the first holding valve can be a solenoid valve that can be switched to a closed position by energizing an electromagnet.The first control unit can then switch the first holding valve depending on the operating situation to release or close the first venting path. In the event of a fault in the first control unit, the first holding valve automatically switches to the open state, thus allowing the parking brake to be engaged or the parking brake path to be vented even in the event of a fault (provided any other valves along the first venting path also allow flow through the same).

[0014] In a preferred variant, the second electropneumatic redundancy valve unit comprises a second monostable holding valve, which is connected in series along the first venting path with the bistable valve unit, in particular a bistable valve of the bistable valve unit. The second monostable holding valve can preferably be designed analogously to the first monostable holding valve. Preferably, the first monostable holding valve of the first electropneumatic redundancy valve unit and the second monostable holding valve of the second electropneumatic redundancy valve unit are each biased to an open state and / or open in the de-energized state. In this case, the holding valves release the first venting path when they are de-energized. The parking brake redundancy unit then advantageously remains controllable even in the event of a partial fault.For example, if the first control unit experiences a fault and therefore does not supply electrical voltage to the first monostable holding valve of the first electropneumatic redundancy valve unit, the first holding valve switches to the open state and releases the section of the first vent path passing through the first holding valve. The second control unit, which continues to function in this scenario, can then, by appropriately controlling the second monostable holding valve, release or not release the first vent path in order to connect the main port to the redundancy vent and thus direct the pressure of the locking compressed air path received at the main port into the environment.

[0015] In a preferred development of a variant of the electropneumatic parking brake device, the second monostable holding valve is arranged along the first venting path between the bistable valve unit, in particular a bistable valve of the bistable valve unit, and the first monostable holding valve.

[0016] The parking brake redundancy unit preferably comprises at least one pressure sensor. The pressure sensor is designed to detect a pressure in the first venting path. The pressure sensor is preferably connectable to the first control unit and / or the second control unit in order to provide signals corresponding to the detected pressure in the venting path for the first control unit and / or the second control unit. The pressure sensor allows a status diagnosis for the parking brake redundancy unit. For example, a first control unit connected to the pressure sensor can use the pressure sensor to determine whether or not pressure is present at the main connection of the parking brake redundancy unit. If the main connection is connected, for example, to a spring-loaded brake cylinder, the pressure sensor can be used to determine whether the parking brake is engaged or not. The pressure sensor is preferably designed to determine the pressure at the main connection ordesigned to provide pressure signals corresponding to the pressure at the main connection. However, the pressure sensor can also be used, for example, to determine a pressure upstream or downstream of the bistable valve unit, in particular a bistable valve of the.

[0017] A bistable valve unit can be provided downstream or upstream of the first monostable holding valve or downstream or upstream of the second monostable holding valve. The flow direction is viewed from the main port toward the redundant vent, so that the main port is located upstream of the redundant vent.

[0018] In a further preferred embodiment, the parking brake redundancy unit comprises a second redundancy vent and a second vent path that can be vented via the second redundancy vent, wherein the bistable valve unit can be controlled via the second vent path. It should be understood that only a first valve of the bistable valve unit can be controlled via the second vent path, and that at least one second valve of the bistable valve unit can act on the second vent path to control this first valve of the bistable valve unit, in particular, can release, block, and / or vent the second vent path via the second redundancy vent.

[0019] In a preferred development of the embodiment with first and second venting paths, the bistable valve unit comprises a first electronically switchable monostable holding valve arranged in the second venting path, and a pneumatically switchable third holding valve, in particular a relay valve, arranged in the first venting path and comprising a pneumatic control connection connected to the second venting path. The second electropneumatic redundant valve unit comprises a second electronically switchable monostable holding valve arranged in the first venting path. The third holding valve is preferably open when a control pressure is provided at the pneumatic control connection, which preferably exceeds a pressure limit.

[0020] The parking brake redundancy unit preferably further comprises a return path, wherein the return path connects an outlet port of the third holding valve to the pneumatic control port of the third holding valve. The holding valve can then be self-holding once it has initially been switched to an open state. A throttle and / or a check valve is preferably provided in the return path. The throttle can throttle a compressed air volume flow through the return path. The check valve preferably prevents a compressed air flow from the pneumatic control port to the outlet port of the third holding valve. The throttle can, for example, prevent a high working pressure in the first venting path from preventing venting of the pneumatic control port.Thus, the throttle then ensures, if necessary, that the pneumatic control connection can be vented to interrupt the first venting path, in particular by at least partially venting the second venting path connected to the second control connection.

[0021] The parking brake device preferably further comprises a flow restrictor that limits the maximum volume flow through the parking brake redundancy unit. The flow restrictor can be designed, for example, as a constriction in the first venting path. By limiting the maximum volume flow, the speed at which a parking compressed air path connected to the main connection can be emptied via the parking brake redundancy unit can be reduced, or the time required for emptying can be increased. If, for example, the parking compressed air path is connected to the spring-loaded brake cylinder, the flow restrictor can ensure smooth engagement of the parking brake, since the parking brake cylinder is not suddenly vented. This is particularly advantageous if the parking brake is to be used to brake a moving vehicle in a redundant situation.The flow restrictor can be a passive element, in particular a throttle, or a switchable component, for example an electronically controllable throttle valve.

[0022] In a second aspect, the invention solves the aforementioned problem with an electronically controllable pneumatic braking system for a vehicle, comprising at least one first front axle brake actuator and one second front axle brake actuator for a front axle of the vehicle, and at least one first rear axle brake actuator and one second rear axle brake actuator for a rear axle of the vehicle. The braking system further comprises a primary system with a primary control unit at least for controlling the first front axle brake actuator and the second front axle brake actuator and / or for controlling the first rear axle brake actuator and the second rear axle brake actuator, and an electropneumatic parking brake device according to one of the preferred embodiments described above according to the first aspect of the invention.The at least one spring-loaded connection of the electropneumatic parking brake valve unit is preferably connected to at least one first spring-loaded brake cylinder. The primary system is preferably a service brake system of the vehicle. The primary control unit is typically independent of the parking brake control unit. The electropneumatic parking brake valve unit of the parking brake device is designed to ventilate a parking brake cylinder connected to the spring-loaded connection (releasing the parking brake). Furthermore, the parking brake valve unit is preferably designed to vent the parking brake cylinder connected to the spring-loaded connection. This is preferably done by corresponding signals from the parking brake control unit. The parking brake valve unit therefore typically serves as the primary device for engaging and releasing the vehicle's parking brake.The parking brake redundancy unit preferably provides redundancy for the parking brake valve unit and allows the parking brake to be engaged even if the parking brake valve unit, in particular the parking brake control unit, is faulty. However, it should be understood that the main connection of the parking brake redundancy unit does not need to be connected to the spring brake cylinder for this purpose.

[0023] In a first preferred embodiment of the braking system, however, the first spring brake cylinder is connected to the main connection of the parking brake redundancy unit. The parking brake redundancy unit is preferably switchable to connect the spring brake cylinder to the redundancy venting via the first venting path in order to vent the spring brake cylinder. In this case, the parking compressed air path is therefore a compressed air path connected to at least one spring brake cylinder.

[0024] In an alternative embodiment of the electronically controllable pneumatic brake system, the main connection is connected to a first compressed air supply of the brake system. The parking brake redundancy unit is switchable to connect the compressed air supply to the redundancy vent via the first vent path in order to vent the first compressed air supply. In this variant, the parking compressed air path is therefore a compressed air path connected to a first compressed air supply. The parking brake redundancy unit can connect the compressed air supply to the redundancy vent and thus cause a pressure drop in a supply compressed air path of the brake system. This can then cause the parking brake to be applied. For example, braking systems for the North American market typically feature a so-called push-pull valve that automatically engages the parking brake as soon as the supply pressure or reservoir pressure falls below a predefined pressure level.

[0025] Preferably, the primary control unit is or includes the first control unit. The primary control unit can then control the first electropneumatic redundancy valve unit. Since the primary control unit and the parking brake control unit are typically independent units, the primary control unit can thus form a redundancy level for the parking brake control unit. This is particularly advantageous because an existing control unit can be used as a redundancy level. However, it can also be provided that the first control unit is a separate control unit.

[0026] In a preferred development of the above-described embodiments, the electronically controllable pneumatic brake system further comprises a secondary system with a secondary control unit, wherein the secondary system is designed to control the first front axle brake actuator and the second front axle brake actuator and / or the first rear axle brake actuator and the second rear axle brake actuator. Preferably, the secondary system is designed to control the first front axle brake actuator and the second front axle brake actuator and / or the first rear axle brake actuator and the second rear axle brake actuator if a fault is detected in the primary system. The secondary system then preferably forms a redundancy level for the primary system, which is provided in particular in vehicles with a high degree of automation. The secondary system can therefore also be a redundant service brake system.

[0027] Preferably, the secondary control unit is or includes the second control unit. In this preferred variant, an existing control unit can also be used as a backup for the parking brake control unit.

[0028] In a preferred variant, the electronically controllable pneumatic brake system has a first voltage source and a second voltage source, wherein the first voltage source is provided for supplying the first control unit with electrical voltage, and wherein the second voltage source is provided for supplying the second control unit with electrical voltage. Providing mutually independent voltage sources can further increase the reliability of the brake system, since a failure of a single voltage source does not cause a total failure of the parking brake system. The parking brake control unit can be connected to the first voltage source or to the second voltage source for supplying electrical voltage.

[0029] According to a third aspect of the invention, the object mentioned at the outset is achieved by a commercial vehicle having a front axle, at least one first 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.

[0030] In a fourth aspect, the invention solves the aforementioned problem with a method for operating an electronically controllable braking system for a vehicle. The braking system comprises at least one spring-loaded brake cylinder and an electropneumatic parking brake device according to one of the above-described embodiments of the first aspect of the invention, in which the first electropneumatic redundancy valve unit comprises a bistable valve unit. The spring-loaded brake cylinder connection of the electropneumatic parking brake valve unit is connected to the at least one spring-loaded brake cylinder for supplying the spring-loaded brake cylinder with a parking pressure, and the main connection of the electropneumatic parking brake redundancy unit is connected to a parking pressure air path of the braking system.The method comprises the steps of: determining whether an at least partially autonomous operating mode or a manual operating mode of the braking system is present; switching the bistable valve unit to the venting position if an at least partially autonomous operating mode of the braking system is present; switching the bistable valve unit to the second switching position if the manual operating mode of the braking system is present; and venting the at least one spring-loaded brake cylinder by means of the electropneumatic parking brake valve unit. The bistable valve unit, which is preferably or comprises a bistable valve, is therefore preferably switched, depending on the existing operating mode, to the venting position, in which the bistable valve unit allows a pneumatic connection of the main connection to the redundant venting, or to the second switching position, in which the bistable valve unit interrupts the first venting path.A selection between the manual operating mode and the at least partially autonomous operating mode can be made, for example, manually, by a human user, or automatically by an autonomous driving unit or another control unit of the vehicle. Bleeding the spring brake cylinder is only possible in the at least partially autonomous operating mode, since the bistable valve unit only opens the bleed path in this case. In manual operating mode, a human driver is preferably present, so a redundant bleed function may not be necessary. In manual operating mode, the bistable valve unit can therefore interrupt the first bleed path.

[0031] In a first preferred embodiment, the method, in the event that an at least partially autonomous operating mode of the braking system is present, further comprises the steps of: determining whether there is a fault in the electropneumatic parking brake valve unit, determining whether there is a parking brake request, and at least temporarily interrupting the first venting path by a first holding valve and / or the bistable valve unit if no fault in the electropneumatic parking brake valve unit is detected and no parking brake request is detected; or opening the first holding valve and / or the bistable valve unit if there is a fault in the electropneumatic parking brake valve unit and a parking brake request is detected, in order to at least partially release the first venting path. If the electropneumatic parking brake valve unit has no fault orIf there is no fault in the electropneumatic parking brake valve unit, it can be assumed in many cases that the electropneumatic parking brake valve unit can vent the spring brake cylinder in order to apply the parking brake. Bleeding the parking pressure path through the parking brake redundancy unit is therefore generally not necessary as long as the electropneumatic parking brake valve unit does not have a fault. In the event that the electropneumatic parking brake valve unit has a fault, the first holding valve and / or the bistable valve unit can be opened and at least partially release the vent path. However, the at least partial release preferably only occurs when a parking brake request is provided, for example from a unit for autonomous driving or from a human driver.Even if the first vent valve and / or the bistable valve unit partially releases the first vent path, it can still be provided that a second vent valve interrupts the first vent path.

[0032] In a preferred development, the method comprises the step of at least temporarily interrupting the first venting path by a second holding valve if no fault is detected in the parking brake control unit and no parking brake request is detected, wherein the at least temporary interruption by the second holding valve preferably occurs when the first holding valve releases the first venting path, no fault is detected in the parking brake control unit, and no parking brake request is detected. If no parking brake request is present, the interruption of the first venting path can thus occur alternately by the first holding valve (and / or the bistable valve unit) and the second holding valve, which can have a positive effect on the service life of the holding valves.

[0033] Preferably, the first holding valve and / or the bistable valve unit are controlled by a first control unit to at least temporarily interrupt the first venting path, and the second holding valve is controlled by a second control unit to at least temporarily interrupt the first venting path. The first control unit and the second control unit are preferably connected, in particular via a CAN bus, and are configured to determine whether the respective other control unit opens or interrupts the first venting path.

[0034] It should be understood that the electronically controllable pneumatic braking system according to the second aspect of the invention, the commercial vehicle according to the third aspect of the invention and the method for operating a braking system according to the fourth aspect of the invention have the same and similar sub-aspects as particularly set out in the dependent claims to the first aspect of the invention and to the second aspect of the invention.

[0035] 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 more limited than 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 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.

[0036] 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:

[0037] Fig. 1 is a schematic representation of a commercial vehicle with an electronically controllable pneumatic braking system;

[0038] Fig. 2 is a schematic representation of a first embodiment of a parking brake device;

[0039] Fig. 3 is a schematic representation of a second embodiment of a parking brake device;

[0040] Fig. 4 is a schematic representation of a third embodiment of a parking brake device;

[0041] Fig. 5 is a schematic representation of a fourth embodiment of a parking brake device; and Fig. 6 is a schematic representation of a fifth embodiment of a parking brake device.

[0042] Fig. 1 shows an electronically controllable pneumatic braking system 200 with an electropneumatic parking brake device 1. The electronically controllable pneumatic braking system 200 is used in the present case in a vehicle 300 designed as a commercial vehicle 302, which is shown here highly schematically, in particular with a front axle VA, a first rear axle HA1 and a second rear axle HA2.

[0043] The electronically controllable pneumatic braking system 200 here has first, second, third, fourth, fifth, and sixth service brake actuators 208a-208f, each for a wheel of the vehicle 300. A rear axle brake circuit 202 and a front axle brake circuit 204 are provided to supply the first to sixth service brake actuators 208a-208f with brake pressure. The service brake actuators 208a, 208b are assigned to the front axle VA and are therefore also referred to as front axle brake actuators 208a, 208b. Similarly, the service brake actuators 208c-208f assigned to the rear axles HA1, HA2 are also referred to as rear axle brake actuators 208c-208f. The rear axle brake circuit 202 is supplied by a first compressed air supply 206 and the front axle brake circuit 204 is supplied by a second compressed air supply 210.The commercial vehicle 300 is designed here as a towing vehicle and comprises a trailer brake circuit 207 with a trailer module 209, which is provided for supplying a trailer (not shown) connected to the commercial vehicle 300 with compressed air.

[0044] The electronically controllable pneumatic braking system 200 has an operating level and a first redundancy level. At the operating level, the electronically controllable pneumatic braking system 200 comprises a primary system 212 with an electronic primary control unit 214, which controls the electronically controllable pneumatic braking system 200 at the operating level. The electronic primary control unit 214 is connected to an autonomous driving unit 218 via a vehicle bus 216 and receives braking request signals SA from it. Furthermore, the electronic primary control unit 214 is connected to a first voltage source 222 via a first supply line 220 and is supplied with electrical energy therefrom. The electronic primary control unit 214 converts the braking request signals SA and, based thereon, controls operating braking signals SB at a first operating axle modulator 224.The first operating axle modulator 224 here is a front axle modulator 228 provided for the front axle VA. Alternatively or additionally, brake request signals SA can also be provided by an electronic foot brake pedal 264 on the primary control unit 214.

[0045] The first service axle modulator 224 is connected to the second compressed air supply 210 and receives supply pressure pV therefrom. Based on the received service brake signals SB, the first service axle modulator 224 controls a first service brake pressure pB1 at a first service brake pressure connection 232.1 and a second service brake connection 232.2. At the first and second service brake pressure connections 232.1, 232.2, the first service brake pressure pB1 is preferably controlled in a wheel-specific manner, and the first service axle modulator 224 is designed as a two-channel modulator. In other embodiments, the first service brake pressure connection 232.1 and the second service brake pressure connection 232.2 can also be combined, and the first service axle 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.

[0046] A first wheel speed sensor 234 is also provided on the front axle VA, which provides first wheel speed signals SD to the primary control unit 214. The primary control unit 214 is configured to process the first wheel speed signals SD and provide ABS switching signals to ABS valves 238 of the front axle VA in order to achieve slip control or ABS modulation of the first service brake pressure pB1 and prevent locking of the front wheels of the vehicle 300.

[0047] To brake the first and second rear axles HA1, HA2, the electronically controllable pneumatic braking system 200 comprises, in the operating level, a second operating axle modulator 236, which is provided for the first and second rear axles HA1, HA2 and can thus also be referred to as a rear axle modulator 237. In the exemplary embodiment shown in Fig. 1, the rear axle modulator 237 is installed with the electronic primary control unit 214 to form a module, which is referred to here as the central module 240. However, it should be understood that the rear axle modulator 237 and the primary control unit 214 can also be separate or structurally separated. The primary control unit 214 and the rear axle modulator 237 can then be connected to one another, for example, via a signal line or a BUS line.Internally, the primary electronic control unit 214 controls the rear axle modulator 237 in accordance with the braking request signals SA that the primary control unit 214 has received from the autonomous driving unit 218.

[0048] A supply connection 230 of the second service axle modulator 236 is connected to the first compressed air supply 206 and receives supply pressure pV therefrom. Depending on its control by the primary control unit 214, the rear axle modulator 237 controls at least a second service brake pressure pB2; in the exemplary embodiment shown here, however, it also controls a third service brake pressure pB3. In the exemplary embodiment shown in Fig. 1, the second service brake pressure pB2 is provided for the right side of the vehicle, and the third service brake pressure pB3 is provided for the left side of the vehicle. The rear axle modulator 237 is thus designed here as a two-channel axle modulator. The second service brake pressure pB2 is intended for a fourth and sixth service brake actuator 208d, 208f, while the third service brake pressure pB3 is provided for a third and fifth service brake actuator 208c, 208e.In other variants, the first operating axis modulator 236 can also be designed as a single-channel modulator or as a multi-channel modulator with more than two outputs.

[0049] In the redundancy level, the electronically controllable pneumatic braking system 200 comprises a secondary control unit 242 of a secondary system 241, which is intended to control the electronically controllable pneumatic braking system 200 in the event that the operating level has one or more errors. The secondary control unit 242 can therefore 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 error in the primary control unit 214, or the like. The electronic secondary control unit 242 is also connected to the autonomous driving unit 218 via the vehicle bus 216 and also receives braking request signals SA from it. In contrast to the primary control unit 214, the secondary control unit 242 is connected to a second voltage source 246 via a second supply line 244 and is supplied with electrical energy by the latter.The first and second voltage sources 222, 246 are independent of each other, so that a failure in the first voltage source 222 does not result in a loss of the second voltage source 246, and vice versa. The primary electronic control unit 214 and the secondary electronic control unit 242 are therefore electrically independent of each other.

[0050] To enable signal exchange, the primary control unit 214 and the secondary control unit 242 are connected to each other via a redundancy bus 248. In this way, the secondary control unit 242 can determine the availability of the primary control unit 214 and only assume control of the electronically controllable pneumatic braking system 200 when the primary control unit 214 is not available or is no longer available properly. However, in variants, communication between the primary control unit 214 and the secondary control unit 242 can also take place, for example, via the vehicle bus 216.

[0051] A redundant axle modulator 250 is provided in the redundancy level, which is connected to the secondary control unit 242 and receives redundant brake signals SR from it. In the exemplary embodiment shown in Fig. 1, the secondary control unit 242 is integrated into the redundant axle modulator 250. In other variants, however, the secondary control unit 242 and the redundant axle modulator 250 can also be physically separate units.

[0052] The redundant axle modulator 250 is connected to the second compressed air supply 210, which is independent of the first compressed air supply 206, so that the second compressed air supply 210 can provide supply pressure pV even if the first compressed air supply 206 has failed. In other embodiments, the redundant axle modulator 250 can also be connected to the second compressed air supply 210 or to the first compressed air supply 206 and the second compressed air supply 210. The redundant axle modulator 250 controls a redundant brake pressure pBR1 at a redundant brake pressure connection 252 depending on the redundant brake signals SR. The redundant brake pressure pBR1 controlled at the redundant brake pressure connection 252 is provided to the front axle modulator 228. The redundant axle modulator 250 is shown in Fig.1 is shown as a single-channel axle modulator with only one redundancy brake pressure connection 252, but can also be designed as a multi-channel axle modulator, which can, for example, realize a side-aligned control of redundancy brake pressures.

[0053] The secondary control unit 242 can control the redundant axle modulator 250 such that, in the event of a fault in the primary control unit 214, a brake pressure, namely the redundant brake pressure pBR1, is still provided to the front axle brake actuators 208a, 208b. Unlike what is shown in Fig. 1, the redundancy level can also be provided for braking the first and second rear axles HA1, HA2. This can be implemented using the redundant axle modulator 250 or using a second redundant axle modulator. The secondary control unit 242 can then preferably also be provided for controlling such a second redundant axle modulator.

[0054] The brake actuators assigned to the wheels of the rear axles HA1, HA2 are designed here as double-acting brake actuators, also known as tri-stop cylinders. In addition to the service brake actuators 208c-208f, each of these also includes 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 be advantageously used as a parking brake, which does not require compressed air 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 pressure pFS. This parking pressure pFS counteracts the spring brake and releases the brakes of the vehicle 300.

[0055] To provide the parking brake function, the braking system 200 comprises the parking brake device 1. This comprises an electropneumatic parking brake valve unit 2, which is supplied with supply pressure pV via a supply connection 4. In the illustrated embodiment, the supply connection 4 is connected to the first compressed air supply 206. Here, the parking brake valve unit 2 is additionally supplied with supply pressure pV from the second compressed air supply 210. In other variants, the electropneumatic parking brake valve unit 2 can alternatively or additionally be connected to a third compressed air supply, which is preferably independent of the first compressed air supply 206 and the second compressed air supply 210.It should be understood that the electropneumatic parking brake valve unit 2 can be supplied only from the first compressed air supply 206, only from the second compressed air supply 210, only from the third compressed air supply 206, from at least two compressed air supplies or from the first compressed air supply 206, from the second compressed air supply 210 and from the third compressed air supply.

[0056] 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, the first spring-loaded connection 8a is connected to the spring-loaded brake cylinders 254d, 254f, and the second spring-loaded 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 pressurizes the spring-loaded brake cylinders 254c-254f, thus releasing the parking brake.To engage the parking brake of vehicle 300, the electropneumatic parking brake valve unit 2 can vent the spring-loaded brake ports 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.

[0057] To provide redundancy for the electropneumatic parking brake valve unit 2, the electropneumatic parking brake device 1 further comprises an electropneumatic parking brake redundancy unit 10. The parking brake redundancy unit 10 is designed to vent at least one of the spring brake cylinders 254c-254f independently of the electropneumatic parking brake valve unit 2. This can be done directly or indirectly. Thus, as shown in the exemplary embodiment according to Fig. 1, the parking brake redundancy unit 10 can connect a parking compressed air path 12, which is directly connected to the spring brake cylinders 254c-254f, to a redundancy vent 14. In alternative variants, the parking compressed air path 12 can also be connected to the first compressed air supply 206 and / or the second compressed air supply 210.Furthermore, the parking compressed air path 12 can alternatively or additionally also be connected to a third compressed air supply, which is not shown in Fig. 1. The parking brake redundancy unit 10 then connects this parking compressed air path 12, which is connected to the first compressed air supply 206, the second compressed air supply 210, or a third compressed air supply, to the redundancy vent 14, thereby venting the spring brake cylinders 254c-254f. The parking brake redundancy unit 10 can thus be used to vent only one compressed air supply 206, 210 or to vent multiple compressed air supplies 206, 210.

[0058] The parking brake redundancy unit 10 comprises a main connection 16, which is provided for connection to the parking compressed air path 12. In Fig. 1, the spring-loaded brake cylinders 254c-254f are directly connected to the main connection 16 and the spring-loaded connections 8a, 8b. In the exemplary embodiment shown in Fig. 1, the parking brake redundancy unit 10 therefore receives the parking pressure pFS at the main connection 16 if the parking brake of the vehicle 300 is released or the spring-loaded brake cylinders 254c-254f are vented. The parking brake redundancy unit 10 is designed to connect the main connection 16 to the redundancy vent 14 via a first vent path 18 (see Fig. 2). In the exemplary embodiment according to Fig. 1, the parking pressure pFS can be vented directly to the environment via the first vent path 18.Even if venting via the electropneumatic parking brake valve unit 2 should no longer be possible due to a fault, the parking brake cylinders 254c-254f can be connected to the redundant vent 14 or the environment via the first vent path 18 and thus vented.

[0059] Fig. 1 also schematically shows a first electropneumatic redundancy valve unit 22 and a second electropneumatic redundancy valve unit 24. The first redundancy valve unit 22 can be controlled by a first control unit 26, which in the illustrated embodiment is the primary control unit 214. For this purpose, the first redundancy valve unit 22 is connected to the primary control unit 214 via a first redundancy signal line 256. The second redundancy valve unit 24 can be controlled in a similar manner by a second control unit 28, which here is formed by the secondary control unit 242. The connection between the secondary control unit 242 and the second redundancy valve unit 24 is established via a second redundancy signal line 258.The primary control unit 214 and the secondary control unit 242 are independent of each other and are supplied by separate voltage sources 222, 246, so that by using the primary control unit 214 as the first control unit 26 and the secondary control unit 242 as the second control unit 28, a redundancy level with high reliability can be created in a particularly simple manner.

[0060] In the embodiment shown in Fig. 1, both the first control unit 26 and the second control unit 28 are independent of the parking brake control unit 6. In other embodiments, however, the parking brake control unit 6 can also form or comprise the first control unit 26 or the second control unit 28.

[0061] Fig. 2 now schematically shows a first embodiment of the electropneumatic parking brake device 1, wherein, for the sake of simplicity, the first rear axle HA1 with the associated parking brake cylinders 254c, 254d is also shown. The electropneumatic parking brake valve unit 2 is shown schematically, wherein the spring-loaded connections 8a, 8b are shown here in a simplified manner as a common spring-loaded connection 8. The main connection 16 is also shown only in a highly simplified manner and opens into the parking compressed air path 12, which here is a connecting line between the spring-loaded connection 8 of the parking brake valve unit 2 and the spring-loaded brake cylinders 254c, 254d.

[0062] The first venting path 18 of the parking brake redundancy unit 10 indirectly connects the main connection 16 to the redundancy venting 14. In the first exemplary embodiment shown in Fig. 2, the parking brake redundancy unit 10 comprises a total of three valves. The first redundancy valve unit 22 comprises a bistable valve unit 30, which is designed here as a bistable valve 31, and a first monostable holding valve 32. The second redundancy valve unit 24 here has only a second monostable holding valve 34. The bistable valve 31, the second monostable holding valve 34, and the first monostable holding valve 32 are connected in series along the first venting path 18, with the second holding valve 34 being arranged between the bistable valve 31 and the first holding valve 32. The second monostable holding valve 34 is thus arranged along the first vent path 18 downstream of the bistable valve 1 and upstream of the first monostable holding valve 32.

[0063] In Fig. 2, the first control unit 26 and the second control unit 28 are not shown. However, it should be understood that the bistable valve 1 and the first monostable holding valve 32 of the first redundant valve unit 22 can be controlled by the first control unit 26. The second monostable holding valve 34, however, can be controlled by the second control unit 28.

[0064] Here, the first monostable holding valve 32 and the second monostable holding valve 34 are each designed as electrically switchable solenoid valves. The first holding valve 32 is a 2 / 2-way valve that is biased to an open state, in which the holding valve 32 releases the first venting path 18. In the illustrated embodiment, the first holding valve 32 can be energized by the first control unit 26 to switch the first holding valve 32 to a closed state, in which it interrupts the first venting path 18. Spring-loaded pressure pFS received at the main connection 16 from the parking compressed air path 12 cannot then be vented to the environment via the parking brake redundancy unit 10. As long as the first control unit 26 is functional, it can thus prevent venting of the spring-loaded brake cylinders 254c, 254d.

[0065] The second holding valve 34 is designed as a 3 / 2-way valve. In the state shown in Fig. 2, in which the second holding valve 34 is preloaded, the second holding valve 34 releases the first vent path 18. For this purpose, it connects a first path connection 34.1 with a second path connection 34.2. In the second position not shown in Fig. 2, however, the second path connection 34.2 is connected to a vent 34.3 and the first vent path 18 is interrupted. The vent 34.3 of the second holding valve 34 is shown here as a separate vent, but can also be the redundant vent 14. The second control unit 28 can switch the second monostable holding valve 34 from the open position illustrated in Fig. 2 to the closed position (not shown) by energizing the second holding valve 34 or its electromagnet.The second control unit 28 can thus prevent venting of the locking compressed air path 12 by switching the second monostable holding valve 34 to the closed state. In the closed state, the second path connection 34.2 is connected to the vent 34.3, and the locking compressed air path 12 is interrupted.

[0066] The bistable valve unit 30, which is formed here by the bistable valve 30, has a first position 36, which is also referred to here as the venting position 38, and a second position 40. The first control unit 26 is designed to switch the bistable valve unit 30 between these two positions 36, 40. In the venting position 38, the bistable valve 31 releases the first venting path 18, thus allowing a pneumatic connection of the main connection 16 to the redundant vent 14 if the holding valves 32, 34 are also open. The bistable valve unit 30 is stable in both the first position 36 and the second position 40. If the bistable valve 31 is not controlled by the first control unit 26, it remains in the last position 36, 40 assumed.For example, the bistable valve 31 remains in the venting position 38 even if the second control unit 26 has a fault and can no longer provide switching signals for the bistable valve 31 or the bistable valve unit 30.

[0067] In the illustrated embodiment, the bistable valve unit 30 can be used to switch between a manual operating mode and an autonomous operating mode of the braking system 200. In manual operating mode, a human driver assumes at least some of the control tasks of the vehicle 300. In the event that one of the control units 6, 26, 28, 218 of the braking system 200 fails or has a fault, the human driver can assume the task of this control unit 6, 26, 28, 218. A redundancy level for the parking brake control unit 6 of the parking brake valve unit 2 may then not be necessary. In such cases, the bistable valve 31 can be switched to the second switching position 40. The first venting path 18 is then permanently interrupted by the bistable valve 31, and venting of the parking compressed air path 12 via the parking brake redundancy unit 10 is not possible.

[0068] During (semi-)autonomous operation of the vehicle 300, the parking brake of the braking system 200 should generally be able to be safely engaged even if the parking brake control unit 6 of the parking brake valve unit 2 is faulty and venting of the spring brake cylinders 254c, 254d via the parking brake valve unit 2 is not possible. In this case, the bistable valve 31 of the first redundancy valve unit 22 can be switched to the venting position 38. This occurs, for example, when the vehicle 300 is started up or at the start of the journey. In the venting position 38, the bistable valve 31 releases the first venting path 18 and thus generally allows immediate venting of the parking compressed air path 12 via the parking brake redundancy unit 10.

[0069] Various fault scenarios are conceivable, particularly during autonomous operation of the vehicle 300. If only the parking brake control unit 6 exhibits a fault, the parking pressure air path 12 can be vented via the parking brake redundancy unit 10. For this purpose, the first control unit 26 must open the first holding valve 32, and the second control unit 28 must open the second holding valve 34 while the bistable valve 31 is in the venting position 38. The main connection 16 is then fluidly connected to the redundancy vent 14, and the parking pressure air path 12 can be vented directly into the environment. A functional control unit 26, 28 can prevent the parking pressure air path 12 from being vented by appropriately energizing the first holding valve 32 or the second holding valve 34.

[0070] In the first embodiment shown in Fig. 2, each of the control units 26, 28 can prevent the venting of the locking compressed air path 12 because the first holding valve 32 and the second holding valve 34 are connected in series. Even if, for example, the first control unit 26 fails and the first monostable holding valve 32 switches to the open position shown in Fig. 2, the second control unit 28 can energize the second monostable holding valve 34 and thus still interrupt the first venting path 18.

[0071] In the event that both the first control unit 26 and the second control unit 28 experience a fault, the parking brake redundancy unit 10 in the first exemplary embodiment according to Fig. 2 is also designed to provide an emergency braking function. The first monostable holding valve 32 and the second monostable holding valve 34 are each biased to an open state and therefore release the first vent path 18 as soon as they are not supplied with current from the first control unit 26 or the second control unit 28. If the bistable valve 31 is also in the vent position 38, then in the event of a fault in the first control unit 26 and the second control unit 28, the main connection 16 is automatically fluidically connected to the redundancy vent 14 and the parking compressed air path 12 is immediately vented.In the first exemplary embodiment, the parking pressure pFS is thus vented to the environment, and the spring-loaded brake cylinders 254c, 254d brake the first rear axle HA1. To prevent the wheels of the first rear axle HA1 from locking, a flow restrictor (not shown) can be provided in the first venting path 18. This can prevent a sudden emptying of the spring-loaded brake cylinders 254c, 254d, which could lead to locking of the wheels of the first rear axle HA1.

[0072] Fig. 3 illustrates a second embodiment of the parking brake device 1, the representation being essentially analogous to the first embodiment. In addition to the parking brake valve unit 2 and the parking brake redundancy unit 10, Fig. 3 also shows the first control unit 26 and the second control unit 28. The first control unit 26 is supplied with electrical voltage by the first voltage source 222, which is also shown. The first voltage source 222 is also connected to the parking brake valve unit 2. The second control unit 28, on the other hand, is supplied with electrical voltage by the second voltage source 246. The separate voltage supply to the first control unit 26 and the second control unit 28 prevents a failure of one of the voltage sources 222, 246 from leading to a total failure of the parking brake redundancy unit 10.

[0073] In the second exemplary embodiment (Fig. 3), the first redundancy valve unit 22 and the second redundancy valve unit 24 are designed essentially identically to the first exemplary embodiment (Fig. 2). Here, however, the parking brake redundancy unit 10 further comprises a first pressure sensor 42 and a second pressure sensor 44. Both pressure sensors 42, 44 are designed to detect a pressure of the first venting path 18. Here, the pressure sensors 42, 44 are connected to the second control unit 28 and provide signals corresponding to the respectively detected pressure to the second control unit 28. In other variants of the parking brake device 1, the first pressure sensor 42 and / or the second pressure sensor 44 can also be connected to the first control unit 26. In the second exemplary embodiment according to Fig. 3, the first pressure sensor 42 is provided to detect a pressure present at the main connection 16.The second control unit 28 is designed to determine, using the signals from the first pressure sensor 42, which pressure is present at the main connection 16. In the embodiment shown, the second control unit 28 can thus determine, for example, whether the parking pressure pFS is present at the parking compressed air path 12 or whether the spring brake cylinders 254c, 254d are pressurized or vented. For this purpose, the first pressure sensor 42 is arranged to detect the pressure upstream of the bistable valve 31 of the bistable valve unit 30. The second pressure sensor 44 is designed to determine the pressure downstream of the bistable valve 31. The second control unit 28, which is not provided here for controlling the bistable valve unit 30, can thus determine, using the signals from the first pressure sensor 42 and the second pressure sensor 44, whether the bistable valve unit 30 is in the first switching position 36 or in the second switching position 40.

[0074] Fig. 4 illustrates a third embodiment. The parking brake redundancy unit 10 is designed analogously to the first embodiment. In this variant of the brake system 200, however, the parking compressed air path 12 is not a direct connection between the parking brake valve unit 2 and the spring brake cylinders 254c-254f, but rather a supply path. The main connection 16 is connected to the first compressed air supply 206 and the second compressed air supply 210 via a select-high valve 260. However, it should be understood that the select high valve 258 may also be omitted and / or that the main connection 16 may also be connected only to the first compressed air supply 206, only to the second compressed air supply 210, only to a third compressed air supply and / or to at least two compressed air supplies from the first compressed air supply 206, the second compressed air supply 210 and a third compressed air supply.

[0075] To vent at least one spring brake cylinder 254c-254f of the braking system 200 of the vehicle 300, the parking brake redundancy unit 10 connects the main connection 16 to the redundancy vent 14. The first compressed air reservoir 206 and the second compressed air reservoir 210 are thus immediately vented. As a result, the pressure level of the reservoir pressure pV drops. As soon as the pressure level of the reservoir pressure pV falls below a predefined pressure limit, a push-pull valve 262 shown in Fig. 1 automatically vents the spring brake cylinders 254c-254f. In the third embodiment according to Fig. 4, the parking brake redundancy unit 10 therefore connects the parking compressed air path 12 connected to the first compressed air supply 206 and the second compressed air supply 210 to the vent 14 in order to indirectly vent at least one spring brake cylinder 254c-254f.Alternatively or additionally, a corresponding function within the parking brake valve unit 2 can automatically vent the spring brake cylinders 254c-254f if the pressure level of the reservoir pressure pV falls below the predefined limit value.

[0076] A fourth embodiment of a parking brake device 1 is illustrated in Fig. 5, wherein, analogously to the first and second embodiments, a parking compressed air path 12 and the first rear axle HA1 with the spring brake cylinders 254c, 254d are additionally shown. Analogous to the second embodiment illustrated in Fig. 3, Fig. 5 also shows the first control unit 26, the second control unit 28, the first voltage source 222, and the second voltage source 246.

[0077] In the fourth exemplary embodiment, the first redundancy valve unit 22 comprises only the bistable valve unit 30, which here again only comprises the bistable valve 31. The first monostable holding valve 32 is omitted in this variant. The second redundancy valve unit 24 again comprises only the second monostable holding valve 34. The bistable valve 31 is arranged upstream of the second holding valve 34. To detect a pressure downstream of the bistable valve 31, the second pressure sensor 44 is again provided, which here is connected to the second control unit 28. By providing only one monostable holding valve 34, the parking brake redundancy unit 10 according to the fourth exemplary embodiment can be manufactured cost-effectively.In order to be able to vent the parking compressed air path 12 even in the event of a fault in the first control unit 26 or the first voltage source 222 using the parking brake redundancy unit 10, the bistable valve 31 is preferably switched to the venting position 38 when the brake system 200 is started up. The bistable valve 1 maintains the venting position 38 even if it is de-energized due to a fault in the first control unit 26 or a failure of the first voltage source 222. During fault-free operation, the second control unit 28 keeps the second monostable holding valve 34 in the closed state, thus preventing unintentional venting of the parking compressed air path 12. In the event of a fault in the second control unit 28, the second holding valve 34 automatically switches to the open state and releases the first venting path 18.The still functional first control unit 26 can then, if necessary, switch the bistable valve 31 into the second switching position 36 in order to prevent venting of the locking compressed air path 12.

[0078] Fig. 6 illustrates a fifth embodiment of a parking brake device 1 of a braking system 200, wherein the representation is essentially analogous to Fig. 5. For simplification, the voltage sources 222, 246 have been omitted in Fig. 6.

[0079] The parking brake redundancy unit 10 according to the fifth exemplary embodiment provides functionality essentially analogous to that of the parking brake redundancy unit 10 of the fourth exemplary embodiment illustrated in Fig. 5. However, the bistable valve unit 30 does not include a bistable valve 31, although a bistable valve 31 could in principle be provided. The bistable function of the bistable valve unit 30 is provided in the fifth exemplary embodiment via a plurality of valves 32, 50, 52. The bistable valve unit 30 is illustrated in Fig. 6 by a dashed line around its valves 32, 50, 52.

[0080] The parking brake redundancy unit 10 is also designed to connect the parking compressed air path 12 to a redundancy vent 14. For this purpose, a first vent path 18 is again provided, via which the main connection 16 can be connected to the first redundancy vent 14. This first vent path 18 serves as the primary vent path for venting the parking compressed air path 12. In the fifth exemplary embodiment (Fig. 6), a second vent path 46 is additionally provided. The main connection 16 can be connected to a second redundancy vent 48 via the second vent path 46. A spring brake cylinder 254c-254f can thus, in principle, also be vented via the second vent path 46. However, in the fifth embodiment of the parking brake redundancy unit 10, the second venting path 46 is primarily used to control the bistable function of the bistable valve unit 30.In other embodiments (cf. analogously to Fig. 4), the second venting path 46 can alternatively or additionally also be used to vent a parking compressed air path 12 connected to at least one compressed air supply 206, 210 directly into the environment and thus indirectly vent a spring brake cylinder 254c-254f. The first redundancy valve unit 22 of the fifth exemplary embodiment of a parking brake device 1 illustrated in Fig. 6 comprises the bistable valve unit 30, which has a first monostable holding valve 32, a third holding valve 50, and a fourth electrically electronically switchable holding valve 52. The second redundancy valve unit 24, however, analogously to the fourth exemplary embodiment (Fig. 5), again comprises only the second electronically switchable holding valve 34.

[0081] The fourth holding valve 52 and the first holding valve 32 are each designed as 2 / 2-way valves that are preloaded to a closed state. The second holding valve 34 is also designed as a 2 / 2-way valve, but here preloaded to an open state. The fourth holding valve 52 is designed as a solenoid valve and can be controlled by the first control unit 26. The first control unit 26 also controls the first holding valve 32. The second control unit 28 can energize the second holding valve 32 and thus block the first vent path 18. In the event of a fault in the second control unit 28, the second holding valve 34 releases the first vent path 18, since the second holding valve 34 is de-energized in this case.

[0082] In the exemplary embodiment according to Fig. 6, the bistable valve unit 30 is designed, analogously to the exemplary embodiment according to Fig. 5, to release or block the first venting path 18 running from the main connection 16 to the first redundant vent 14. For this purpose, the bistable valve unit 30, analogous to the bistable valve 31, comprises a venting position 38 and a second switching position 40. In the venting position 38, the third holding valve 50 releases the venting path 18 and connects the main connection 16 to the second holding valve 34 in a fluid-conducting manner. In the second switching position 40, the third holding valve 50 interrupts the first venting path 18. The bistable function of the bistable valve unit 30 can be controlled by the first control unit 26, which controls the first holding valve 32 and the fourth holding valve 52.

[0083] The third holding valve 50 here is a pneumatically switchable valve 54, namely a relay valve 56. The relay valve 56 has an inlet port 56.1, an outlet port 56.2, and a pneumatic control port 56.3. By applying a pneumatic control pressure to the pneumatic control port 56.3, the relay valve 56 can be switched to an open state in which the inlet port 56.1 is fluidly connected to the outlet port 56.2. The relay valve 56 can therefore be switched by providing a pneumatic control pressure at the control port 56.3 so that it releases the first vent path 18. Here, the bistable valve unit 30 is then in the venting position 38. If the second holding valve 34 is also open, the locking compressed air path 12 connected to the main connection 16 can be connected to the first redundant vent 14 and vented via the relay valve 56 and the second holding valve 34.

[0084] The pneumatic control connection 56.3 is connected to the second venting path 46. The relay valve 56 and thus the bistable valve unit 30 can therefore be controlled via the second venting path 46. In the exemplary embodiment shown, the second venting path 46 is essentially used to control the relay valve 56 or to provide the bistable function of the bistable valve unit 30 and can therefore also be referred to as a control path. The pneumatic control pressure of the relay valve 56 can initially be provided via the second venting path 46. The locking pressure pFS present in the locking compressed air path 12 is also provided to the first holding valve 32 via the main connection 16. The first control unit 26 can energize the first holding valve 32 and thus switch it to an open state while keeping the fourth holding valve 52 closed in order to prevent venting of the locking compressed air path 12.The locking pressure pFS thus enters a first path section 58 of the second venting path 46, which connects the first holding valve 32 to the fourth holding valve 52. The pneumatic control port 56.3 of the relay valve 56 is connected to this first path section 58, and the relay valve 56 switches to the open state when the locking pressure pFS is applied. The bistable valve unit 30 is then in the venting position 38.

[0085] In the venting position 38 of the bistable valve unit 30, the locking pressure pFS, which is also present at the inlet port 56.1 via the main port 16, thus passes through the relay valve 56 to the outlet port 56.2. The second control unit 28 energizes the second holding valve 34 and keeps it closed. The locking pressure pFS is therefore enclosed in a second path section 60, which connects the relay valve 56 to the second holding valve 34.

[0086] The second path section 60 of the first vent path 18 is connected to the first path section 58 of the second vent path 46 via a return path 62. The outlet port 56.2 of the relay valve 56 is connected to the control port 56.3 of the relay valve 56 via the return path 62, and the relay valve 56 can maintain itself in the open state. Even if the first control unit 26 closes the first holding valve 32 or the first holding valve 32 automatically switches to the closed state due to an error in the first control unit 26, the relay valve 56 remains in the open switching position because a locking pressure pFS continues to be applied to the pneumatic control port 56.3 via the second path section 60, the return path 62, and the first path section 58.

[0087] The relay valve 56 or the bistable valve unit 30 is thus stable in the venting position 38. By briefly opening the first holding valve 32, particularly when the vehicle 300 starts operating, the relay valve 56 can be brought into a self-holding state, in which the relay valve 56 remains even when the first holding valve 32 is closed again. Even if the first control unit 26 has a fault, venting of the first parking compressed air path 12 via the first venting path 18 is still possible. The second control unit 28, which is still functional, can energize the second holding valve 34 and hold it in the closed state or interrupt the first venting path 18. If the parking brake of the vehicle 300 is to be engaged, the second control unit 28 no longer supplies the second holding valve 34 with electrical voltage, thus switching the second holding valve 34 to the open state.The spring-loaded pressure pFS can then be vented to the environment via the first vent path 18 and the first redundant vent 14.

[0088] If only the second control unit 28 exhibits a fault, the first control unit 26 can control the bistable valve unit 30 to release or block the first vent path 18. Release occurs analogously to the above description by venting the pneumatic control port 56.3 via the first holding valve 32. To block the first compressed air path 18, the first control unit 26 opens the fourth holding valve 52, thus connecting the first path section 58 of the second vent path 46 to the second redundant vent 48. This also vents the pneumatic control port 56.3 of the relay valve 56, and the relay valve 56 closes. The bistable valve unit 30 is then in the second switching position 40.

[0089] In the fifth exemplary embodiment shown, the return path 62 comprises a throttle 64. In addition to or in addition to the throttle 64, a check valve could also be provided, for example. The throttle 64 limits the possible volume flow through the return path 62. The throttle 64 here only allows a small portion of the compressed air flow along the first vent path 18, i.e., a compressed air flow from the main connection 16, via the relay valve 56 and the second holding valve 34 to the first redundant vent 14, to pass through the return path 62. This ensures that the control connection 56.3 of the relay valve 56 can still be vented via the fourth holding valve 52 even when the first compressed air path 18 is open, in order to close the relay valve 56 or switch the bistable valve unit 30 to the second switching position 40, in which the first compressed air path 18 is interrupted.

[0090] If both the first control unit 26 and the second control unit 28 have a fault, the second holding valve 34 also switches to the open state, so that an emergency braking function can also be realized by the parking brake redundancy unit 10 of the fifth embodiment.

[0091] In emergency situations, the main connection 16 can also be connected to the second redundant vent 48 via the second vent path 46 or through the first holding valve 32 and the fourth holding valve 52, and thus vented. This can be advantageous, for example, if the second holding valve 34 has a mechanical failure and can no longer be switched to the open position.

[0092] Reference symbol (part of the description)

[0093] Parking brake device Parking brake valve unit Supply connection Parking brake control unit , 8a, 8b Spring-loaded connections 0 Parking brake redundancy unit 2 Parking compressed air path 4 Redundancy venting 6 Main connection 8 First venting path 2 First redundancy valve unit 4 Second redundancy valve unit 6 First control unit 8 Second control unit 0 Bistable valve unit 1 Bistable valve 2 First monostable holding valve 4 Second monostable holding valve 4.1 First path connection 4.2 Second path connection 4.3 Venting of the second holding valve 6 First switching position 8 Venting position 0 Second switching position 2 First pressure sensor 4 Second pressure sensor 6 Second venting path 8 Second redundancy venting 0 Third holding valve 2 Fourth holding valve 4 Pneumatically switchable valve 6 Relay valve 6.1 Input connection of the relay valve Outlet connection of the relay valve Pneumatic control connection First path section Second path section

[0094] Return path

[0095] Throttle electronically controllable pneumatic braking system

[0096] Rear axle brake circuit

[0097] Front axle brake circuit first compressed air supply

[0098] Trailer brake circuit a-208f Service brake actuators a, 208b Front axle brake actuators c, 208d, Rear axle brake actuators e, 208f

[0099] Trailer module second compressed air supply

[0100] Primary system

[0101] Primary control unit

[0102] Vehicle-BUS

[0103] Autonomous driving unit first supply line first voltage source first operating axle modulator

[0104] Front axle modulator

[0105] Supply connection .1 first service brake pressure connection .2 second service brake pressure connection

[0106] Wheel speed sensor second operating axle modulator

[0107] Rear axle modulator

[0108] ABS valves

[0109] Central module

[0110] Secondary system

[0111] Secondary control unit 244 second supply line

[0112] 246 second voltage source

[0113] 248 Redundancy BUS

[0114] 250 Redundancy Axis Modulator

[0115] 252 Redundancy brake pressure connection

[0116] 254c-254f spring brake cylinder

[0117] 256 first redundancy signal line

[0118] 258 second redundancy signal line

[0119] 260 Select High Valve

[0120] 262 Push-pull valve

[0121] 264 Foot brake pedal

[0122] 300 vehicles

[0123] 302 commercial vehicles

[0124] HA1 first rear axle

[0125] HA2 second rear axle pB1 first service brake pressure pB2 second service brake pressure pB3 third service brake pressure pBR1 redundancy brake pressure pFS parking pressure

[0126] SA brake request signals

[0127] SB operating brake signals

[0128] SD wheel speed signals

[0129] SFS parking brake signal

[0130] VA front axle

Claims

Patent claims 1. Electropneumatic parking brake device (1) for venting and bleeding one or more spring brake cylinders (254c, 254d, 254e, 254f) of an at least partially electronically controllable pneumatic brake system (200) for a vehicle (300), comprising an electropneumatic parking brake valve unit (2) with a supply connection (4) for receiving supply pressure (pV) from a compressed air supply (210), and a parking brake control unit (6), wherein the parking brake valve unit (2) is designed to control a parking pressure (pFS) at at least one spring brake connection (8a, 8b) as a function of a parking brake signal (SP), an electropneumatic parking brake redundancy unit (10) which is designed to vent at least one spring brake cylinder independently of the electropneumatic parking brake valve unit (2). (254c, 254d, 254e, 254f) to connect a locking compressed air path (12) to a vent (14),wherein the parking brake redundancy unit (10) has a first venting path (18) comprising a main connection (16) for receiving a pressure (pFS, pV) of the parking compressed air path (12), a first electropneumatic redundancy valve unit (22), a second electropneumatic redundancy valve unit (24), and a redundancy vent (14) into the environment, wherein the first electropneumatic redundancy valve unit (22) is controllable by a first control unit (26), and wherein the second electropneumatic redundancy valve unit (24) is controllable by a second control unit (28) that is independent of the first control unit (26), and wherein the parking brake redundancy unit (10) is designed to connect the main connection (16) to the redundancy vent (14) via the first venting path (18) of the parking brake redundancy unit (10), to vent the main connection (16) directly into the environment., 2. Electropneumatic parking brake device (1) according to claim 1, wherein the first control unit (26) and / or the second control unit (28) is independent of the parking brake control unit (6).

3. Electropneumatic parking brake device (1) according to claim 1, wherein the parking brake control unit (6) comprises the first control unit (26) or the second control unit (28).

4. Electropneumatic parking brake device (1) according to one of claims 1 to 3, wherein the first electropneumatic redundancy valve unit (22) has a bistable valve unit (30) with a first position (36) and a second position (40), wherein the first position (36) is a venting position (38) in which the bistable valve unit (30) allows a pneumatic connection of the main connection (16) to the redundancy vent (14), and wherein the bistable valve unit (30) interrupts the first venting path (18) in the second switching position (40).

5. Electropneumatic parking brake device (1) according to claim 4, wherein the first electropneumatic redundancy valve unit (22) has a first monostable holding valve (32) which is connected in series with the bistable valve unit (30) along the first venting path (18).

6. Electropneumatic parking brake device (1) according to claim 4 or 5, wherein the second electropneumatic redundancy valve unit (24) has a second monostable holding valve (34) which is connected in series with the bistable valve unit (30) along the first venting path (18).

7. Electropneumatic parking brake device (1) according to claim 5 and 6, wherein the second monostable holding valve (34) is arranged along the first venting path (18) between the bistable valve unit (30) and the first monostable holding valve (32).

8. Electropneumatic parking brake device (1) according to one of claims 4 to 7, further comprising a second redundant vent (48) and a second vent path (46) which can be vented via the second redundant vent (48), wherein the bistable valve unit (30) can be controlled via the second vent path (46).

9. Electropneumatic parking brake device (1) according to claim 8, wherein the bistable valve unit (30) has a first electronically switchable monostable holding valve (32) which is arranged in the second venting path (46), and a pneumatically switchable third holding valve (50, 54), in particular a relay valve (56), which is arranged in the first venting path (18) and comprises a pneumatic control connection (56.3) which is connected to the second venting path (18), wherein the second electropneumatic redundant valve unit (24) has a second electronically switchable monostable holding valve (34) which is arranged in the first venting path (18).

10. Electropneumatic parking brake device (1) according to claim 9, further comprising a return path (62), wherein the return path (62) connects an outlet connection (56.2) of the third holding valve (50, 54) to the pneumatic control connection (56.3) of the third holding valve (50, 54), wherein a throttle (64) and / or a check valve is preferably provided in the return path (62).

11. Electropneumatic parking brake device (1) according to one of claims 1 to 10, wherein the parking brake redundancy unit (10) has at least one pressure sensor (42, 44) for detecting a pressure (pFS) in the first venting path (18).

12. Electropneumatic parking brake device (1) according to one of claims 1 to 11, further comprising a flow limiter which limits a maximum volume flow through the parking brake redundancy unit (10).

13. An electronically controllable pneumatic braking system (200) for a vehicle (300), comprising at least one first front axle brake actuator (208a, 208b) and one second front axle brake actuator (208a, 208b) and at least one first rear axle brake actuator (208c, 208d, 208e, 208f) and one second rear axle brake actuator (208c, 208d, 208e, 208f); a primary system (212) with a primary control unit (214) at least for controlling the first front axle brake actuator (208s, 208b) and the second front axle brake actuator (208a, 208b) and / or for controlling the first Rear axle brake actuator (208c, 208d, 208e, 208f) and the second rear axle brake actuator (208c, 208d, 208e, 208f); and an electropneumatic parking brake device (1) according to one of claims 1 to 12, wherein at least one first spring-loaded brake cylinder (254c, 254d, 254e, 254f) is connected to the at least one spring-loaded brake connection (8) of the electropneumatic parking brake valve unit (2).

14. Electronically controllable pneumatic brake system (200) according to claim 13, wherein at least the first spring brake cylinder (254c, 254d, 254e, 254f) is connected to the main connection (16) of the parking brake redundancy unit (10), wherein the parking brake redundancy unit (10) is switchable to connect the spring brake cylinder (254c, 254d, 254e, 254f) via the first venting path (18) to the redundancy vent (14) in order to vent the spring brake cylinder (254c, 254d, 254e, 254f).

15. Electronically controllable pneumatic brake system (200) according to claim 13, wherein the main connection (16) is connected to a first compressed air supply (206, 210) of the brake system (200), and wherein the parking brake redundancy unit (10) is switchable to connect at least the first compressed air supply (206, 210) via the first venting path (18) to the redundancy vent (14) in order to vent the first compressed air supply (206, 210).

16. Electronically controllable pneumatic braking system (200) according to one of claims 13 to 15, wherein the primary control unit (214) is or comprises the first control unit (26).

17. Electronically controllable pneumatic brake system (200) according to one of claims 13 to 16, further comprising a secondary system (241) with a secondary control unit (242), wherein the secondary system (241) is designed to control the first front axle brake actuator (208a, 208b) and the second front axle brake actuator (208a, 208b) and / or to control the first rear axle brake actuator (208c, 208d, 208e, 208f) and the second rear axle brake actuator (208c, 208d, 208e, 208f) if an error is detected in the primary system (212).

18. The electronically controllable pneumatic braking system (200) of claim 17, wherein the secondary control unit (242) is or comprises the second control unit (28).

19. Electronically controllable pneumatic brake system (200) according to one of claims 13 to 18, comprising a first voltage source (222) and a second voltage source (246), wherein the first voltage source (222) is provided for supplying the first control unit (26) with electrical voltage and wherein the second voltage source (246) is provided for supplying the second control unit (28) with electrical voltage.

20. Vehicle (300), in particular commercial vehicle (302), with at least one front axle (VA), at least one first rear axle (HA1) and an electronically controllable pneumatic braking system (1) according to one of the preceding claims 13 to 19. 21 . A method for operating an electronically controllable pneumatic brake system (200) for a vehicle (300), which comprises at least one spring brake cylinder (254c, 254d, 254e, 254f) and an electropneumatic parking brake device (1) according to claim 4, wherein the spring brake connection (8a, 8b) of the electropneumatic parking brake valve unit (2) is connected to the at least one spring brake cylinder (254c, 254d, 254e, 254f) for ventilating the spring brake cylinder (254c, 254d, 254e, 254f) with a parking pressure (pFS), and wherein the main connection (16) of the electropneumatic parking brake redundancy unit (10) is connected to a parking pressure air path (12) of the brake system (200), the method comprising the steps: Determining whether an at least partially autonomous operating mode or a manual operating mode of the braking system (200) is present; Switching the bistable valve unit (30) to the venting position (38) if an at least partially autonomous operating mode of the braking system (200) is present; switching the bistable valve unit (30) to the second switching position if the manual operating mode of the braking system (200) is present; and Ventilating the at least one spring brake cylinder (254c, 254d, 254e, 254f) by the electropneumatic parking brake valve unit (2).

22. The method according to claim 21, wherein the method, in the event that an at least partially autonomous operating mode of the braking system (200) is present, further comprises: Determine whether there is a fault in the electro-pneumatic parking brake valve unit (2), Determining whether a parking brake request is present and at least temporarily interrupting the first venting path (18) by a first holding valve (32) if no fault of the electropneumatic parking brake valve unit (2) is detected and no parking brake request is detected; or Opening the first holding valve (32) if a fault of the electropneumatic parking brake valve unit (2) is detected and a parking brake request is detected in order to at least partially release the first vent path (18).

23. The method according to claim 22, further comprising at least temporarily interrupting the first venting path (18) by a second holding valve (34) if no error of the parking brake control unit (6) is detected and no parking brake request is detected, wherein the at least temporary interruption by the second holding valve (34) preferably occurs when the first holding valve (32) releases the first venting path (18), no error of the parking brake control unit (6) is detected and no parking brake request is detected.

24. The method according to claim 23, wherein the first holding valve (32) is controlled by a first control unit (26) for at least temporarily interrupting the first venting path (18), wherein the second holding valve (34) is controlled by a second control unit (28) for at least temporarily interrupting the first venting path (18); and wherein the first control unit (26) and the second control unit (28) are connected, in particular connected via a CAN bus, and are designed to determine whether the respective other control unit (26, 28) releases or interrupts the first venting path (18).

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