Patent Application
20240198996
The disclosure relates to an electronically controllable pneumatic braking system for a vehicle which is preferably a utility vehicle. The electronically controllable pneumatic braking system has a first control unit for a primary system and a second control unit for a first fallback level, wherein the first control unit and the second control unit are supplied with energy independently of one another and/or can at least partially replace one another in terms of their function. Moreover, a monostable fail-safety valve unit is provided, the monostable fail-safety valve unit pneumatically connecting a main port, which provides a first pressure, and a failure brake port, wherein the fail-safety valve unit is connected both to the first control unit and to the second control unit and in a fault situation and/or power failure and/or diagnostic situation of the first control unit and the second control unit provides a failure brake pressure on the failure brake port. In a second aspect, the disclosure also relates to a vehicle having such an electronically controllable pneumatic braking system.
Safety concepts are very relevant in electropneumatic braking systems for modern vehicles. In particular, in vehicles with automated or partially automated driving functions, concepts for triggering a failure braking operation in a fault situation or a power failure of a control unit contribute significantly to the safety of the vehicle, the occupants thereof and other traffic users. Such concepts permit safe braking and stopping of the vehicle in a fault situation, such as for example a power failure.
In principle, there are concepts which implement a failure braking operation via a service braking system and those which implement this via a holding braking system. Braking systems frequently also implement both concepts in order to provide two or more fallback levels which are then based on the different concepts. In the case of concepts based on a holding braking system, in principle there is the advantage that by venting a pretensioned spring brake cylinder a secure hold of the vehicle can be achieved without having to pressurize a brake actuator with compressed air.
Thus DE 10 2019 131 930 A1 already describes an electropneumatic holding brake module for an electronically controllable pneumatic braking system for a vehicle with a supply port for receiving a supply pressure, at least one holding brake port for connecting at least one spring brake cylinder, a main valve unit which receives the supply pressure and which is configured to modulate a spring mechanism pressure on the holding brake port as a function of a control pressure, and a pilot valve arrangement receiving the supply pressure for providing the control pressure, wherein the pilot valve arrangement has a bistable valve which can be switched between a first ventilation position and a second venting position and a control unit for providing first and second switching signals to the pilot valve arrangement.
In the electropneumatic holding brake module disclosed in DE 10 2019 131 930 A1 the pilot valve arrangement has a monostable holding valve which is connected pneumatically in series to the bistable valve and is arranged in a control line of the main valve unit, wherein the holding valve is opened in the de-energized state in an open position, and the control unit is configured to hold the holding valve in the holding position for holding the control pressure via the first switching signal, and a selector valve unit is arranged in the control line between the holding valve and a control port of the main valve unit with a first selector valve port for receiving an auxiliary control pressure provided at an auxiliary brake pressure port, wherein the selector valve unit has a non-return characteristic at the first selector valve port such that the first selector valve port opens in a direction of flow from the auxiliary brake pressure port via a third selector valve port to the control port and is blocked counter to the direction of flow.
A fail-safety valve unit for a failure braking function of an electronically controllable pneumatic braking system, which also serves to permit safe stopping of the vehicle when redundant systems, subsystems or levels of the braking system fail, is disclosed in US 2022/0274573. The braking system disclosed therein has a first control unit and a second control unit which are supplied with energy independently of one another and/or can at least partially replace one another in terms of their function. The fail-safety valve unit has a first failure brake valve configured as a monostable valve, and a second failure brake valve configured as a monostable valve, as well as a valve main line which pneumatically connects a main port providing a first pressure and a failure brake port. In the disclosure therein, the first failure brake valve and the second failure brake valve are pneumatically connected in series in the valve main line. The first failure brake valve is controllable by the first control unit and the second failure brake valve is controllable by the second control unit. The failure brake valves are opened in the inactivated, in particular de-energized, state in an open position, such that the first pressure applied to the main port is provided as failure brake pressure at the failure brake port such that in a fault situation and/or power failure and/or diagnostic situation of the control units a failure braking operation of the vehicle is triggered by the provision of the failure brake pressure at the failure brake port by the braking system.
This system functions very well in principle and, in particular, the fail-safety valve unit has proved advantageous. However, with this solution there is still the need to optimize further the stability of the system, the reaction speed and the pipework.
Other systems for implementing pneumatic redundancies are disclosed, for example, in US 2019/0152459, DE 10 2018 205 957 A1, EP 2 090 481 A1, DE 103 57 373 A1, US 2019/0248351, US 2020/0023827 and US 2019/0337503. Thus, for example, an electronically controllable pneumatic braking system with at least two brake circuits is disclosed in US 2019/0152459, wherein at least one of the at least two brake circuits is assigned an electronically and pneumatically controllable control valve and another of the at least two brake circuits is assigned an electrically controllable parking brake valve, in order to predetermine brake pressures for activating wheel brakes of the respective brake circuit. A first control unit is provided, the first control unit being configured to activate electrically the respective control valve as a function of an automatically requested target vehicle deceleration or an actuation predetermined by the driver via an actuating device, and a second control unit is provided, the second control unit being configured to control electrically the parking brake valve as a function of the automatically requested target vehicle deceleration, when an electrical activation of the respective control valve is prevented. According to this disclosure at least one bypass valve is also provided, the bypass valve being assigned to the control valve and being configured to activate pneumatically the assigned control valve, wherein the pneumatic activation takes place as a function of the automatically requested target vehicle deceleration or as a function of the actuation of the actuating device predetermined by the driver when an electrical activation of the respective control valve is prevented, in order to increase the electronically pneumatically controlled redundancy.
It is the object of the present disclosure to specify an electronically controllable pneumatic braking system of the type mentioned in the introduction which is improved in terms of stability, which is less prone to faults and/or can permit shorter or more efficient pipework.
The object is achieved in an electronically controllable braking system of the type mentioned in the introduction, in that in order to provide the failure brake pressure for triggering a failure braking operation of the vehicle, the failure brake port is connected to the primary system and/or the first fallback level upstream of a functional pneumatic unit of the primary system and/or the first fallback level, in such a way that both front axle service brake actuators and rear axle service brake actuators have a brake pressure applied thereto in order to implement the failure braking operation.
While in the prior art according to US 2022/0274573 the failure brake port for providing the failure brake pressure for triggering the failure braking operation is coupled via a second shuttle valve into the front axle brake circuit, and namely specifically into a line which leads to a redundancy pressure port of a front axle modulator, the present disclosure provides that, on the one hand, the failure brake port is connected to the primary system or to the fallback level upstream of a functional pneumatic unit of the primary system and/or the first fallback level and, on the other hand, when the failure brake pressure is provided both the front axle service brake actuators and the rear axle service brake actuators can have a brake pressure applied thereto. In the prior art according to US 2022/0274573, in a failure braking operation only spring brake cylinders can be actuated on the rear axle, and no service brake actuators. When spring brake cylinders are actuated for implementing redundant braking, other control parameters are required and reaction times differ from those of the service brake actuators, so that in principle it is desirable to use service brake actuators for implementing redundant braking.
The coupling of the failure brake pressure upstream of a functional pneumatic unit of the primary system and/or the first fallback level leads to greater stability and availability of the system. A functional pneumatic unit of the primary system and/or the first fallback level are understood to mean, in particular, such units which can be activated pneumatically and/or electrically and can modulate a pressure pneumatically provided thereto. Examples thereof are axle modulators, parking brake modules, trailer control valves, air conditioning systems, brake pedals, and the like.
The stability of the system can be enhanced by additionally using already existing systems, namely in particular functional pneumatic units of the primary system and/or the first failure fallback level, the failure brake pressure being input upstream thereof. In comparison with US 2022/0274573, in particular, a shuttle valve can be dispensed with. As a result, not only is one component saved but also additional sources of faults can be avoided and thereby the stability of the system enhanced.
According to a first embodiment, it is provided that the fail-safety valve unit has a first failure brake valve configured as a monostable valve, a second failure brake valve configured as a monostable valve, and a valve main line, wherein the first failure brake valve and the second failure brake valve are pneumatically connected in series in the valve main line. Preferably, the first failure brake valve is controllable by the first control unit and the second failure brake valve is controllable by the second control unit. Preferably, the failure brake valves in the inactivated state are in an open position, such that the first pressure applied to the main port or a pressure derived therefrom is provided as failure brake pressure at the failure brake port. If the failure brake valves are activated by two different control units, that is, in each case are assigned to one control unit, the failure brake valves are held in each case in a blocked state by different control units in the activated state independently of one another by a control signal. The control units are supplied with energy, in particular, independently of one another. The fact that the control units can at least partially replace one another in terms of their function means, in particular, that if the first control unit should fail, the second control unit can provide functions of the first control unit redundantly in the sense of a fallback level. In the case of a multiple fault, that is, a fault which relates to a plurality of control units, and in particular a double fault which relates to the primary system with the first control unit and a first fallback level with the second control unit, due to the monostable de-energized opening behavior of the failure brake valves in the inactivated state, that is, when the control signal is absent for the failure brake valves, the fail-safety valve unit can provide a first pressure applied to a main port as failure brake pressure at the failure brake port for the braking system. The embodiment includes the knowledge that with a plurality of subsystems of a braking system, in each case with independent control units, a fault can be advantageously manifested by the absence of a control signal for the respective failure brake valve assigned to the control unit. This can be the case, for example, in a power failure, that is, if the power supply for the control unit malfunctions. The control unit can also be configured such that in the case of an exceptional fault, in particular a case in which the control logic can no longer ensure the safety of the vehicle, a zero signal is emitted as a control signal for the failure brake valve and thus an absence of the control signal is simulated. If this is the case, that is, if a fault is present on both subsystems, in particular in the form of an exceptional fault or power failure, the fail-safety valve unit ensures a safe deceleration of the vehicle by the provision of the failure brake pressure. A double fault here represents a special case of the multiple fault, in which two subsystems are affected at the same time by one fault.
Within the scope of this embodiment, three or more failure brake valves connected in series can also be provided in order to take into account further fallback levels or other systems. Further control units can also be connected to the failure brake valves in order to be able to represent the presence of different multiple faults. It is also possible that two or more control units are connected to a failure brake valve and provide signals thereto. It can also be provided that a control unit outputs a corresponding signal to a plurality of failure brake valves.
According to an embodiment, the electronically controllable pneumatic braking system has a front axle modulator which is electronically connected to the first control unit and which receives front axle service brake signals from the first control unit, and in response thereto provides a front axle service brake pressure on a first front axle service brake actuator and a second front axle service brake actuator on a front axle of the vehicle. The braking system also has a rear axle modulator which is electronically connected to the first control unit and which receives rear axle service brake signals from the first control unit, and in response thereto provides a rear axle service brake pressure on at least one first rear axle service brake actuator and a second rear axle service brake actuator on the rear axle of the vehicle. The front axle modulator and the rear axle modulator can be provided as separate structural units in the braking system. It can also be provided that the first control unit is integrated with the front axle modulator or the rear axle modulator in one structural unit, in order to form a module in this manner. The front axle modulator and the rear axle modulator can be connected to the first control unit both via a bus system and via direct cabling in order to receive the front axle service brake signals and rear axle service brake signals therefrom. If direct cabling is provided, the front and rear axle modulators preferably include output stages.
Preferably, the first control unit is connected via a vehicle bus to a unit for autonomous driving and receives braking request signals therefrom and on the basis thereof provides the front axle service brake signals and/or rear axle service brake signals. The first control unit is provided to implement the braking request signals of the unit for autonomous driving and to provide the corresponding front axle service brake signals and rear axle service brake signals for the front axle modulator and the rear axle modulator. If the pneumatic braking system also includes a trailer control unit, the first control unit preferably also provides service brake signals for the trailer control unit which then can activate a trailer connected to the vehicle in accordance therewith.
Preferably, a front axle redundancy pressure line, into which a front axle redundancy pressure can be input for the redundant braking of the front axle, is provided. A rear axle redundancy pressure line, into which a rear axle redundancy pressure can be input for the redundant braking of at least one rear axle, is preferably also provided. The vehicle can also have two or more axles, wherein the rear axle redundancy pressure is preferably provided for the two or more rear axles. The front axle redundancy pressure line can be connected, for example, to a redundancy port of the front axle modulator which then can pneumatically implement the front axle redundancy pressure received thereon and output the front axle brake pressure as a function of the received front axle redundancy pressure. It can also be provided that the front axle redundancy pressure is directly output to the front axle service brake actuators, in order to brake the front axle redundantly. In a similar manner, the rear axle redundancy pressure line can be connected to the rear axle modulator, preferably to a redundancy port of the rear axle modulator, which then can implement the received rear axle redundancy pressure pneumatically and output the rear axle brake pressure as a function of the rear axle redundancy pressure. It is also conceivable that the rear axle redundancy pressure line is connected directly to the rear axle service brake actuators in order to brake the rear axle redundantly.
According to an embodiment, the braking system includes a redundancy valve unit which is activated by the second control unit. Preferably, the second control unit is integrated with the redundancy valve unit in one structural unit, preferably as a module.
The redundancy valve unit is preferably constructed in the manner of a modulator. It is preferably provided to input the front axle redundancy brake pressure into the front axle redundancy pressure line. It is also preferably provided to input the rear axle redundancy pressure into the rear axle redundancy pressure line. The redundancy valve unit can be configured, for example, in the manner of a two-channel modulator in order to output both the front axle redundancy pressure and the rear axle redundancy pressure. To this end, the redundancy valve unit preferably has one or more electrically switchable solenoid valves. The signals required for switching the solenoid valves are provided by the second control unit. In this manner, the redundancy valve unit forms with the second control unit a fallback level in the braking system since the second control unit is independent of the first control unit and can at least partially replace this first control in terms of function. The redundancy valve unit can then output both the front axle redundancy pressure and the rear axle redundancy pressure which is then implemented on the front and rear axle in order to brake the vehicle.
Preferably, the second control unit is connected via a vehicle bus or the vehicle bus to a unit or the unit for autonomous driving and receives braking request signals therefrom. On the basis of the braking request signals, the second control unit switches valves of the redundancy valve unit and the front and rear axle redundancy pressure are output, either in a manner which is appropriate for each axle or uniformly. In this manner, the second control unit can replace the first control unit entirely or virtually entirely.
According to a further embodiment, it is provided that the redundancy valve unit has a failure control port which can be connected or is connected to the failure brake port, wherein the redundancy valve unit is configured to output the front axle redundancy pressure and/or rear axle redundancy pressure pneumatically on the basis of the failure brake pressure. Preferably, the redundancy valve unit is provided only in a fault situation and/or power failure and/or diagnostic situation of the second control unit to output the front axle redundancy pressure and/or rear axle redundancy pressure on the basis of the pressure received on the failure control port from the failure brake port. In this embodiment, the failure brake port is thus connected upstream of the redundancy valve unit to the braking system. In this embodiment, the redundancy valve unit is thus a functional pneumatic unit of the type mentioned in the introduction. In terms of its function blocking the failure brake pressure, the redundancy valve unit replaces one of the shuttle valves as are provided according to US 2022/0274573. The second control unit undertakes the control of the electronically controllable pneumatic braking system in the event that the first control unit does not function or does not function correctly. If the second control unit also does not function or does not function correctly, the front axle and the rear axle can be braked on the basis of the failure brake pressure, which in this case is preferably pneumatically processed by the redundancy valve unit.
According to a further embodiment, the electronically controllable pneumatic braking system includes a brake value encoder with at least one brake value encoder-brake pressure port for providing a brake value encoder-brake pressure. The brake value encoder-brake pressure port is preferably connected or can be connected to the front axle redundancy pressure line and/or the rear axle redundancy pressure line. This concept, which is known in principle, makes it possible to feed the brake value encoder-brake pressure into the front or rear axle redundancy pressure line via the brake value encoder, so as to be able to brake the vehicle manually in this manner.
In an embodiment, the brake value encoder has a brake value encoder-redundancy port which is connected to the failure brake port, wherein the brake value encoder is configured to output the brake value encoder-brake pressure pneumatically on the basis of the failure brake pressure. In this embodiment, the failure brake port is connected upstream of the brake value encoder to the braking system, so that the brake value encoder in this case represents a functional pneumatic unit according to the embodiment described in the introduction. The brake value encoder is arranged between the failure brake port, that is, also between the fail-safety valve unit and in this case the front axle and rear axle modulator. In the event that the first and the second control unit are functioning, the brake value encoder can also be used to block out the failure brake pressure and thus to prevent braking on the basis of the failure brake pressure.
In a preferred manner, the brake value encoder-brake pressure port is connected to a fail-safety valve unit-control port of the fail-safety valve unit, wherein in the absence of the fault situation and/or power failure and/or diagnostic situation of the first control unit and the second control unit, the fail-safety valve unit is configured to connect the fail-safety valve unit-control port to the failure brake port for activating the brake value encoder-brake pressure. This embodiment is in contrast to the previous embodiment, namely such that the brake value encoder is arranged upstream of the fail-safety valve unit. However, the fail-safety valve unit and the failure brake port are still upstream of the front axle modulator and thus upstream of a functional pneumatic unit of the primary system. However, in this case the fail-safety valve unit can block out the brake value encoder-brake pressure as long as the first and second control unit are functioning. Only when the first and the second control unit do not function or do not correctly function does the fail-safety valve unit activate the brake value encoder-brake pressure and provide this or a pressure derived therefrom as failure brake pressure at the failure brake port which in turn can then be connected, for example, to a redundancy port, for example, of a front axle modulator.
The disclosure is developed by the first failure brake valve and the second failure brake valve being configured as 3/2-way solenoid valves. In such an embodiment in which the failure brake valves are configured in each case as 3/2-way solenoid valves, it is possible to achieve advantageously the effect according to the described concept that the failure brake valve does not automatically switch into an open position in the inactivated state, since the magnetic part of the valve remains de-energized in the inactivated state and thus the valve is moved back into the open position, preferably by a restoring spring.
Preferably, a bistable valve is provided, the bistable valve being arranged in the valve main line and being configured for switching between a first position blocking the valve main line or connecting to a third bistable valve port and a second position connecting the valve main line. The third bistable valve port is preferably connected to a vent. Via such a bistable valve, the fail-safety valve unit can advantageously be operated both in a mode suitable for automatic operation of the vehicle and a mode suitable for manual operation of the vehicle. In particular, the bistable valve is configured such that in the first position blocking the valve main line, the valve main line is pneumatically connected at a first bistable valve port to a vent of the bistable valve, and the valve main line is blocked at a second bistable valve port, and in a second position pneumatically connecting the valve main line, the valve main line is pneumatically connected between the first and second bistable valve port and the vent of the bistable valve is blocked.
If the bistable valve is in a first position blocking the valve main line, a provision of a failure brake pressure at the failure brake port of the fail-safety valve unit is prevented per se, irrespective of the position of the failure brake valves. In this first position, a failure braking operation, which would be caused by a double fault, is prevented. This can be advantageously the case, in particular, with a manual operation of the vehicle, in particular when a human driver is intended to keep control of the vehicle. In contrast thereto, the bistable valve can be switched into a second position pneumatically connecting the valve main line, and thus—if all failure brake valves of the fail-safety valve unit are in an open position, the failure brake pressure can be provided at the failure brake port for triggering a failure braking operation of the vehicle. According to the concept of a bistable valve, it remains in its switched position and even in the de-energized state and, in particular, irrespective of any potential faults in the braking system. The bistable valve is preferably controlled via a valve control unit which in turn is connected to a control unit of the braking system and/or to a vehicle bus with signal and power transmission capability.
In an embodiment, the fail-safety valve unit-control port is connected to the third bistable valve port so that the brake value encoder-brake pressure can be provided at the third bistable valve port. This variant is particularly preferred if the brake value encoder is arranged upstream of the fail-safety valve unit and the fail-safety valve unit is thus arranged downstream of the brake value encoder. The fail-safety valve unit on the input side has two ports, namely the fail-safety valve unit-control port and the main port. The bistable valve mutually connects the main port and the fail-safety valve unit-control port to the valve main line of the fail-safety valve unit, so that either the first pressure P1 provided at the main port or the brake value encoder-brake pressure provided by the brake value encoder can be output into the valve main line.
Further preferably, the electronically controllable pneumatic braking system, preferably the fail-safety valve unit, includes a pressure control valve which is configured for limiting the first pressure and/or the failure brake pressure. Via the pressure control valve, a first pressure provided at the main port or a first pressure forwarded from the main port to the valve main line can be limited to a failure brake pressure which is suitable, in particular, for a failure braking operation. Typically, a vehicle should not be braked immediately with a maximum available pressure, since this can lead to the axles locking. This is to be avoided. The maximum pressure to be output can be dependent on the vehicle type, load status, speed, road conditions and similar parameters. For example, a low pressure limit can be provided with a heavily loaded vehicle, while a greater limit has to be provided with a lightly loaded or empty vehicle in order to prevent the axles locking.
In a further embodiment, the main port for receiving an output holding brake pressure or a pressure derived therefrom as first pressure is pneumatically connected to a holding brake function. The embodiment includes the knowledge that a permanent hold of the braked state of the vehicle is important for the safety of the vehicle. After a failure braking operation by the fail-safety valve unit, a leakage can occur in the service brake circuit carrying out the failure braking operation, in particular in a control line of a pneumatic front axle service brake circuit or on a front axle modulator or at a different point in a separate activation branch in which the fail-safety valve unit is arranged. In the case of such a leakage, if the connected compressed air supply continues to be emptied, it can lead to a drop in the failure brake pressure and thereby to a reduction in the effect of the failure braking operation.
As the main port is pneumatically connected to a holding brake function for receiving an output holding brake pressure as first pressure, it is advantageously achieved that in the case of a leakage occurring after a failure braking operation carried out by the fail-safety valve unit, the at least one spring brake cylinder is also pneumatically connected to the leaking part. In the described embodiment, a leakage thus leads to an actuation of the spring brake cylinder and thereby to a secure hold of the braked state of the vehicle. The actuation of the spring brake cylinder is achieved by the venting of the spring brake cylinder. Via a fail-safety valve unit configured according to the embodiment, therefore, the pneumatic connection of a service brake circuit carrying out the failure braking operation, such as for example the front axle brake circuit, is used with an output holding brake pressure in a targeted manner in order to compensate for the decreasing effect of the failure braking operation by the action of the deployed holding brake if there is a pressure loss in the service brake circuit. This process can be relatively slow, in the region of hours or even days, depending on the extent of the leakage. In various embodiments, however, it can also be provided that the spring-type cylinder is emptied immediately for implementing the failure braking operation and thus an actuation of the spring brake cylinders is achieved at the same time as the braking of the vehicle via the failure braking operation.
According to a further embodiment, the fail-safety valve unit has a selector valve with a first port which is pneumatically connected, in particular, to the holding brake function for receiving the first pressure, with a second port which is pneumatically connected to a further compressed air supply for receiving a further supply pressure as second pressure, and with a third port which is pneumatically connected to the failure brake valve, wherein the selector valve is configured to connect pneumatically to the third port that of the first and second port at which the higher pressure prevails. An embodiment with a selector valve which is preferably configured as a so-called select-high valve includes the knowledge that a redundant supply of compressed air to the fail-safety valve unit advantageously enhances the safety of the vehicle. Via a selector valve with a first port, which is pneumatically connected to a holding braking system for receiving the first pressure, it is advantageously possible to provide the availability of a first compressed air source for providing a failure brake pressure which, in particular, is independent of the compressed air source of the brake circuit used in normal operation, in particular a service brake circuit to which the failure brake pressure is provided. Thus a redundancy is already advantageously achieved by using a separate brake circuit. Via a second port of the selector valve, which is pneumatically connected to a further compressed air supply for receiving a further supply pressure as second pressure, advantageously a further compressed air source, which is present independently of the holding braking system, is provided as a further redundancy. The further compressed air supply can be, in particular, a compressed air supply of the service braking system. As the failure brake valve has a third port which is pneumatically connected to the failure brake valve, and the failure brake valve is configured to connect pneumatically to the third port that of the first and second port at which the higher pressure prevails (select-high valve), advantageously even with a failure of a compressed air source at one of the first and second ports, the other available compressed air source is automatically connected to the failure brake valve.
In a second aspect, the object mentioned in the introduction is achieved by a vehicle having a front axle, at least one rear axle and an electronically controllable pneumatic braking system according to one of the above-described preferred embodiments of an electronically controllable pneumatic braking system according to the first aspect of the disclosure.
The invention will now be described with reference to the drawings wherein:
In the primary system B1 the electronically controllable pneumatic braking system 204 includes a first control unit 410 which is also configured as a central module 412 or is integrated in such a module, and which is connected via a vehicle bus 460 to a unit for autonomous driving 464 and receives braking request signals SBA therefrom. The first control unit 410 is supplied with electrical energy via a first supply line 414 from a first voltage source 416.
On the front axle VA the electronically controllable pneumatic braking system 204 includes a front axle modulator 220 which is configured in this case as a single-channel modulator and receives supply pressure pV from a first compressed air supply 6. To this end, the front axle modulator 220 includes in the known manner a front axle supply port 222 which is connected by pipework to the first compressed air supply 6. The front axle modulator 220 is connected via a front axle signal line 224 to the first control unit 410 and receives therefrom front axle brake signals SBVA which bring about a switching of one or more electromagnetic valves (not shown) of the front axle modulator 220, wherein as a result the front axle modulator 220 outputs a front axle brake pressure pBVA which is output via first and second ABS valves 226, 227 in a manner which is appropriate for each wheel on a first front axle service brake actuator 440a and a second front axle service brake actuator 440b. The front axle signal line 224 can be implemented, on the one hand, as direct cabling of the electromagnetic valves of the front axle modulator 220 to the first control unit 410, so that preferably output stages for electromagnetic valves of the front axle modulator 220 are integrated in the first control unit 410. Alternatively, the front axle signal line 224 can also be configured as a bus connection (CAN-BUS), in particular if the front axle modulator 220 has a separate intelligence.
The electronically controllable pneumatic braking system 204 also includes a rear axle modulator 230 which in this case is integrated in the central module 412 together with the first electronic control unit 410. The rear axle modulator 230 receives supply pressure pV from a second compressed air supply 7. The first electronic control unit 410 implements the braking request signals SBA received via the vehicle bus 206 in the rear axle brake signal SBH and switches one or more electromagnetic valves, not shown here in detail, of the rear axle modulator 230, thereby generating a rear axle service brake pressure pBHA which is output on first and second rear axle service brake actuators 442a, 442b on the first rear axle HA1 and on third and fourth rear axle service brake actuators 442ca, 442d on the second rear axle HA2. The rear axle service brake pressure pBHA in this case is output in a manner which is appropriate for each side and in this regard the rear axle modulator 230 is a two-channel modulator.
Additionally, the electronically controllable pneumatic braking system 204 shown here includes a parking brake unit 240 for forming a holding brake function FFS of the vehicle 200 which is also connected to the vehicle bus 460 and the first voltage source 416 and receives electrical energy therefrom. The parking brake unit 240 in this case is connected both to the first and to the second compressed air supply 6, 7 and receives supply pressure pV from both. The layout shown in
The parking brake unit 240 is provided to output a holding brake pressure pFS via a spring accumulator port 264 on first and second spring brake cylinders 242a, 242b on the first rear axle HA1 and third and fourth spring brake cylinders 242c, 242d on the second rear axle HA2.
The electronically controllable pneumatic braking system 204 is also provided for supplying a trailer and to this end has a trailer control unit 250 which also receives supply pressure pV both from the first compressed air supply 6 and from the second compressed air supply 7. The trailer control unit 250 is connected to the first control unit 410 and receives trailer brake signals SBT therefrom via a trailer signal line 252. In this regard, the trailer control unit 250 is also supplied by the first voltage source 416. As a function of the received trailer brake signal SBT, the trailer control unit 250 outputs a trailer brake pressure pBT at a trailer brake pressure port 251. It is possible to transmit via the trailer brake signal SBT, for example, a normal service brake signal, an anti-jack-knife brake signal for implementing an anti-jack-knife braking function or a trailer parking signal for parking the trailer.
For forming a first redundancy level B2 which in this case is electrically configured, the electronically controllable pneumatic braking system 204 includes a secondary brake module 421 in which the second electronic control unit 420 is also integrated. The secondary brake module 421 can be configured in a similar manner to, or include, a single-channel or double-channel axle modulator, as the redundancy valve unit 10 shown in the embodiment. The secondary brake module 421 in this case is also connected to the first compressed air supply 6 and receives supply pressure pV therefrom. The secondary brake module 421 is also connected to the vehicle bus 460 and receives braking request signals SBA thereby. The secondary brake module is supplied via a second supply line 424 from a second voltage source 426 which is independent of the first voltage source 416. The second electronic control unit 420 is able to process the braking request signals SBA and to activate the redundancy valve unit 10 in order to output a front axle redundancy pressure pRVA at a first redundancy brake pressure port 8 and a rear axle redundancy brake pressure pRHA at a second redundancy brake pressure port 9. The front axle redundancy pressure pRVA in this case is provided to the front axle VA, and the rear axle redundancy brake pressure pRHA is provided in this case to the rear axle HAL HA2. More specifically, the first front axle redundancy pressure pRVA is output in a manner known in principle via a first shuttle valve 433 at a front axle redundancy port 256 of the front axle modulator 220. The front axle modulator 220 then implements the front axle redundancy pressure pRVA received thereon and on the basis thereof outputs the front axle brake pressure pBVA redundantly. To this end, the front axle modulator 220 can have, in a manner known in principle, a monostable redundancy valve and a relay piston or a pneumatically switchable main valve in order to output the front axle redundancy pressure pRVA provided at the front axle redundancy port 256 with greater volume. The front axle redundancy pressure pRVA is also output at a trailer redundancy port 253 of the trailer control valve 250 in order to permit a redundant braking of a trailer.
Accordingly, the rear axle modulator 230, or the central module 412 in which the rear axle modulator 230 is integrated, has a rear axle redundancy port 258 at which the rear axle redundancy brake pressure pRHA can be provided via a second shuttle valve 260.
The secondary brake module 421 thus outputs the front axle redundancy brake pressure pRVA and the rear axle redundancy brake pressure pRHA in a manner which is appropriate for each axle and thus in turn can be denoted as a two-channel modulator. The central module 412 is configured in turn to output the rear axle brake pressure pBHA on the basis of the received rear axle redundancy brake pressure pRHA. To this end, the central module 412 can have, in a manner known in principle, a redundancy valve and a relay piston or a pneumatically switchable main valve in order to output the rear axle redundancy brake pressure pRHA as rear axle brake pressure pBHA with a greater volume. In this manner, an electronically controllable fallback level can be provided, in this case the first fallback level B2.
The electronically controllable pneumatic braking system 204 shown in
A third redundancy level which in this case is configured according to the disclosure as a fail-safe level, however, is formed by a fail-safety valve unit 1 which in this first embodiment (
In the embodiment shown in
The second embodiment shown in
The main difference in the second embodiment, in comparison with the first embodiment, is that the failure control line 23 is connected to the brake value encoder 436 rather than to the redundancy valve unit 10, the brake value encoder in this case forming a functional pneumatic unit 430. The brake value encoder 436 is configured as a so-called 1P2E-foot brake pedal which means that it has a pneumatic port, namely a brake value encoder-brake pressure port 14 and a first electrical port 438 and a second electrical port 439, wherein the first electrical port 438 is connected to the first electronic control unit 410 and the second electrical port 439 is connected to the second electrical control unit 420. Foot brake signals SFB can be provided thereby to the first and second control units 410, 420 in order to cause the first and second control units to provide corresponding front axle brake signals SBVA and rear axle brake signals SBHA.
The brake value encoder 436 according to the second embodiment (
A third embodiment (
The fail-safety valve unit 1 has a first monostable failure brake valve 40 and a second monostable failure brake valve 60.
The first failure brake valve 40 is connected via the first control line 411 with signal and power capability to a first control unit 410. The first control unit 410 is assigned to a primary system B1 of the braking system 204. The second failure brake valve 60 is connected via the second control line 422 to the second control unit 420 with signal and power transmission capability. The second control unit 420 is assigned to a first fallback level B2 of the braking system 204.
The two failure brake valves 40, 60 are pneumatically connected in series in a valve main line 30 of the fail-safety valve unit 1. The valve main line 30 extends from the main port 20 to the failure brake port 22.
Both failure brake valves 40, 60 are shown in the present case in a non-activated and de-energized state, in which they are respectively in an open position 40A, 60A. In the first open position 40A, a pneumatic connection is produced between a first valve port 40.1 and a second valve port 40.2 of the first failure brake valve 40. In the second open position 60A, a pneumatic connection is produced between a first valve port 60.1 and a second valve port 60.2 of the second failure brake valve 60. If both failure brake valves 40, 60 are respectively in the open position 40A, 60A, a pressure can be output from the main port 20 to the failure brake port 22 for the purpose of providing a failure brake pressure pN.
By providing a first control signal S1 via the first control line 412, the first failure brake valve 40 can be switched from the open position 40A counter to the resistance of a first restoring spring 41 into a first blocked position 40B. In the blocked position 40B a pneumatic connection is produced between the first valve port 40.1 and a first venting port 40.3. By providing a second control signal S2 via the second control line 422, the second failure brake valve 60 can be switched from the open position 60A counter to the resistance of a second restoring spring 61 into a second blocked position 60B. In the blocked position 60B a pneumatic connection is produced between the first valve port 60.1 and a second venting port 60.3.
In normal operation of the vehicle 200, in particular, it is provided that the two failure brake valves 40, 60 are in their respective blocked position 40B, 60B. In this state, therefore, there is no pneumatic connection between the main port 20 and the failure brake port 22 since the pneumatic connection is interrupted on at least two points, namely on the first failure brake valve 40 and on the second failure brake valve 60.
In the case of a multiple fault FM, in particular a double fault FD, that is, when both a first control signal S1 and a second control signal S2 are absent at the same time, and a first magnetic part 40.4 of the first failure brake valve 40 and a second magnetic part 60.4 of the second failure brake valve 60 are thus de-energized, both the first failure brake valve 40 and the second failure brake valve 60 return automatically into their open position 40A, 60A by the restoring force generated by the respective restoring spring 41, 61.
Such a double fault FD can arise, for example, due to a simultaneous power failure FS both in the primary system B1 and in the first fallback level B2, when both the first control unit 410 and the second control unit 420 are without a energy supply. In the case of such a simultaneous power failure, accordingly no control signal S1, S2 can be forwarded to the failure brake valves 40, 60.
Moreover, a double fault FD can also be manifested by an exceptional fault FA occurring both in the first control unit 410 and in the second control unit 420, and a zero signal is switched from the respective control unit 410, 420 as a fault measure (in particular in the absence of other program alternatives) and thus the control signals S1, S2 are deliberately set to 0 for switching the failure brake valves 40, 60 into the open position 40A, 60A. Different types of fault can be present in the individual control units 410, 420 for the presence of a multiple fault FM, for example in the case of a double fault FD a power failure FA can be present in a control unit 410, 420 and an exceptional fault FA can be present in the respective other control unit 410, 420.
The fail-safety valve unit 1 also has a pressure control valve 34 which in the present case is arranged in the valve main line 30 between the main port 20 and the second failure brake valve 60, such that a first pressure p1 prevailing at the main port 20 is limited to a fixed value set manually on the pressure control valve 34, before it is provided at the failure brake port 22 as failure brake pressure pN. The value set manually on the pressure control valve 34 is generally set once or is in a preset delivery state and in this case is not changed again during the operation of the braking system.
The fail-safety valve unit 1 also has a bistable valve unit 70 with a bistable valve 72 which is arranged in the valve main line 30. The bistable valve 72 is shown in the present case in a second position 72B in which a pneumatic connection is produced between a first bistable valve port 72.1 and a second bistable valve port 72.2. In a first position 72A of the bistable valve 72 the second bistable valve port 72.2 is blocked and a pneumatic connection is produced between the first bistable valve port 72.1 and a third bistable valve port 72.3 which in this case is connected to a vent 3. The bistable valve 72 is activated via a third switching signal S3 which is provided in this case by the first control unit 410. For the autonomous operation of the vehicle 200, the bistable valve 72 is preferably moved into the second switching position 72B, while in manual operation of the vehicle 200 the bistable valve is in the first switching position 72A. In this manner, the output of the failure brake pressure pN can be prevented in manual operation. If such a changeover is not desired, the bistable valve 72 can also be dispensed with.
The fail-safety valve unit 1 can have a pressure sensor, not shown here, in particular for checking the function of the failure brake valves 40, 60 for plausibility.
The second embodiment shown in
In the third embodiment of the fail-safety valve unit 1 (
The essential difference is in the configuration of the parking brake unit 240 and the trailer control unit 250. The parking brake unit 240 has, in contrast to
A further difference is that the main port 20 in this case is connected to a third shuttle valve 466 which, on the one hand, is connected to the holding brake function FFS and receives holding brake pressure pFS and, on the other hand, is connected to the first compressed air supply 6 and receives supply pressure pV therefrom. The third shuttle valve 466 outputs in each case the higher of the holding brake pressure pFS and the supply pressure pV at the main port 20.
The fifth embodiment (
It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 122 501.9 | Aug 2021 | DE | national |
This application is a continuation application of international patent application PCT/EP2022/071541, filed Aug. 1, 2022, designating the United States and claiming priority from German application 10 2021 122 501.9, filed Aug. 31, 2021, and the entire content of both applications is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2022/071541 | Aug 2022 | WO |
| Child | 18589123 | US |
