Method and Brake System for Emergency Stopping of a Commercial Vehicle

Abstract

A method is for the emergency stopping of a commercial vehicle. The vehicle has a pneumatic brake system with a primary service brake system and a parking brake system. The primary service brake system has a primary electronic service brake control unit for controlling the primary service brake system and service brake actuators. The parking brake system has an electronic parking brake control unit for controlling the parking brake system and parking brake actuators on at least one vehicle axle. The pneumatic brake system can receive an emergency stopping signal. The method includes: receiving the emergency stopping signal at the primary electronic service brake control unit; braking the commercial vehicle via the primary service brake system; ascertaining a commercial vehicle speed and, if this speed is below a predetermined speed threshold value and/or after a predetermined emergency stopping time: actuating the parking brake actuators via the parking brake system.

Claims

1. A method for the emergency stopping of a commercial vehicle, the commercial vehicle having a pneumatic brake system with a primary service brake system and a parking brake system, which are supplied by at least one compressed air reservoir, the primary service brake system having a primary electronic service brake control unit for controlling the primary service brake system and a plurality of service brake actuators, the parking brake system having an electronic parking brake control unit for controlling the parking brake system and a plurality of parking brake actuators on at least one vehicle axle, the pneumatic brake system having a plurality of wheel speed sensors, which provide wheel speed signals to the primary electronic service brake control unit and the electronic parking brake control unit, and the pneumatic brake system being configured to receive an emergency stopping signal; the method comprising: receiving the emergency stopping signal at the primary electronic service brake control unit; braking the commercial vehicle via the primary service brake system; and, ascertaining a commercial vehicle speed and, if at least one of the commercial vehicle speed is below a predetermined speed threshold value and a predetermined emergency stopping time has elapsed, actuating the parking brake actuators via the parking brake system.

2. The method of claim 1, wherein the emergency stopping signal is received also at the electronic parking brake control unit and, in an event that braking of the commercial vehicle by the primary service brake system is not possible, braking the commercial vehicle via the parking brake system.

3. The method of claim 1, wherein the pneumatic brake system has a secondary service brake system supplied by the compressed air reservoir or a further compressed air reservoir; the secondary service brake system has a secondary electronic service brake control unit for controlling the secondary service brake system; the emergency stopping signal is also received at the secondary electronic service brake control unit; and, in an event that braking of the commercial vehicle by the primary service brake system is not possible, braking the commercial vehicle by the secondary service brake system.

4. The method of claim 3, wherein, in the event that braking of the commercial vehicle by the secondary service brake system is not possible, braking the commercial vehicle by the parking brake system.

5. The method of claim 2, wherein the commercial vehicle is braked by the parking brake system directly or in steps.

6. The method of claim 2, wherein the commercial vehicle is braked by the parking brake system directly or in steps in a slip controlled, speed dependent or friction coefficient dependent manner.

7. The method of claim 1 further comprising ascertaining the predetermined emergency stopping time on a basis of at least one parameter including at least one of: state variables of the primary service brake system or a secondary service brake system; activity of an ABS function; wheel speed signals; speed of the commercial vehicle; friction coefficient; expected friction coefficient; vehicle weight; learned values or profiles of the brake system.

8. The method of claim 1, wherein the emergency stopping signal is provided from a permanently wired emergency stop switch of the commercial vehicle, wirelessly from a remote transmitter, and/or from a transmitter inside the commercial vehicle.

9. The method of claim 1, wherein the parking brake actuators include at least one spring brake cylinder, which is configured to be opened when aerated and closed when deaerated by a spring force; and, said braking the commercial vehicle by the parking brake system includes a venting of at least one of said at least one spring brake cylinder.

10. The method of claim 1, wherein the parking brake system has a parking brake valve unit; the parking brake valve unit is connected to the compressed air reservoir or a further compressed air reservoir and to the parking brake actuators; and, the electronic parking brake control unit switches one or more valves of the parking brake valve unit in order to actuate the parking brake actuators via the parking brake system.

11. The method of claim 10, wherein the parking brake valve unit is monostable; the parking brake valve unit is configured to be switched into a first switch position in which the parking brake actuators are released via provision of an electrical signal; and, the parking brake valve unit is further configured to be switched in a monostable manner into a second switch position in which the parking brake actuators are closed when the electrical signal ceases.

12. The method of claim 10, wherein the parking brake valve unit is bistable and has a bistable valve and also a monostable holding valve; the bistable valve has a stable release position and a stable closed position; in the release position of the bistable valve, the parking brake actuators are releasable and, in the closed position of the bistable valve, the parking brake actuators are closeable; and, the monostable holding valve is configured to confine a pressure controlled by the bistable valve in the release position; the method further comprising: switching the bistable valve into the release position to release the parking brake actuators; switching the holding valve into an activated switch position to confine the pressure controlled by the bistable valve; and, switching the bistable valve into the closed position.

13. A pneumatic brake system with an emergency stopping function for a commercial vehicle, the pneumatic brake system comprising: a primary service brake system and a parking brake system, which are supplied by at least one compressed air reservoir; said primary service brake system having a primary electronic service brake control unit for controlling the primary service brake system and service brake actuators; said parking brake system having an electronic parking brake control unit for controlling the parking brake system and parking brake actuators on at least one vehicle axle; a plurality of wheel speed sensors configured to provide wheel speed signals to the primary electronic service brake control unit and the electronic parking brake control unit; said primary electronic service brake control unit being configured to receive an emergency stopping signal and, in response to receiving said emergency stop signal, to brake the commercial vehicle via said primary service brake system; and, said electronic parking brake control unit being configured to ascertain the commercial vehicle speed and to at least one of: actuate said parking brake actuators via said parking brake system if the commercial vehicle speed is below a predetermined speed threshold value, and, actuate said parking brake actuators via said parking brake system after a predetermined emergency stopping time.

14. The pneumatic brake system of claim 13, wherein said electronic parking brake control unit is configured to receive said emergency stopping signal and, in an event that braking of the commercial vehicle by said primary service brake system is not possible, to brake the commercial vehicle via the parking brake system.

15. The pneumatic brake system of claim 13 further comprising: a secondary service brake system configured to be supplied by the at least one compressed air reservoir or a further compressed air reservoir; said secondary service brake system having a secondary electronic service brake control unit for controlling said secondary service brake system; and, said secondary electronic service brake control unit being configured to receive said emergency stopping signal and, in an event that braking of the commercial vehicle via said primary service brake system is not possible, braking the commercial vehicle via said secondary service brake system.

16. The pneumatic brake system of claim 15, wherein said electronic parking brake control unit is configured to brake the commercial vehicle in an event that braking of the commercial vehicle via said secondary service brake system is not possible.

17. The pneumatic brake system of claim 14, wherein said electronic parking brake control unit is configured to brake the commercial vehicle directly or in steps.

18. The pneumatic brake system of claim 14, wherein said electronic parking brake control unit is configured to brake the commercial vehicle directly or in steps in a slip controlled, speed dependent or friction coefficient dependent manner.

19. The pneumatic brake system of claim 13, wherein said electronic parking brake control unit is configured to ascertain the predetermined emergency stopping time on a basis of at least one of: state variables of said primary service brake system or of a secondary service brake system; activity of an ABS function; wheel speed signals; speed of the commercial vehicle; friction coefficient; expected friction coefficient; vehicle weight.

20. The pneumatic brake system of claim 13 further comprising a connection for a permanently wired emergency stop switch via which said emergency stopping signal is configured to be triggered.

21. The pneumatic brake system of claim 13 further comprising a wireless receiver for receiving said emergency stopping signal provided by a remote transmitter.

22. The pneumatic brake system of claim 13, wherein said primary electronic service brake control unit is configured to receive said emergency stopping signal from a transmitter inside the commercial vehicle.

23. The pneumatic brake system of claim 13, wherein said parking brake actuators include at least one spring brake cylinder configured to be open when aerated and to close by a spring force when deaerated.

24. The pneumatic brake system of claim 12, wherein said parking brake system has a parking brake valve unit connected to the at least one compressed air reservoir or a further compressed air reservoir and to said parking brake actuators; and, said electronic parking brake control unit is configured to switch one or more valves of said parking brake valve unit in order to actuate said parking brake actuators via said parking brake system.

25. The pneumatic brake system of claim 24, wherein said parking brake valve unit is monostable; said parking brake valve unit being configured to be switched into a first switch position in which said parking brake actuators are released via provision of an electrical signal; and, said parking brake valve unit being further configured to be switched in a monostable manner into a second switch position in which said parking brake actuators are closed when the electrical signal ceases.

26. The pneumatic brake system of claim 24, wherein said parking brake valve unit is bistable and has a bistable valve and also a monostable holding valve; said bistable valve has a stable release position and a stable closed position; in the release position of said bistable valve, said parking brake actuators are releasable and, in the closed position of said bistable valve said parking brake actuators are closeable; and, said holding valve is configured to confine a pressure controlled by the bistable valve in said release position.

27. A commercial vehicle comprising a pneumatic brake system of claim 13.

28. The commercial vehicle of claim 27, wherein the commercial vehicle is an autonomous commercial vehicle.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0033] The invention will now be described with reference to the drawings wherein:

[0034] FIG. 1 shows a schematic depiction of a commercial vehicle including pneumatic brake system;

[0035] FIG. 2 shows a detailed view of a parking brake valve unit; and,

[0036] FIG. 3 shows a schematic sequence of the method in the form of a block diagram.

DETAILED DESCRIPTION

[0037] A commercial vehicle 1, which is preferably formed as an autonomous commercial vehicle 2, has a pneumatic brake system 4, which is electronically controllable. The pneumatic brake system 4 is used in the present case in the commercial vehicle 1, which is shown here heavily schematically and which is shown here with two front wheels 6a, 6b of a front axle VA and rear wheels 8a, 8b of a rear axle HA.

[0038] The pneumatic brake system 4, in the embodiment shown in FIG. 1, has a primary service brake system 10 and a parking brake system 12. In the embodiment shown here (FIG. 1) there is no secondary service brake system provided; in this regard see FIG. 3.

[0039] The primary service brake system 10 includes a primary electronic service brake control unit 14, which controls the primary service brake system and also the service brake actuators 16a, 16b, 16c, 16d associated therewith on the front axle VA and the rear axle HA. The parking brake system 12 has an electronic parking brake control unit 18, which is integrated here together with a parking brake valve unit 20, yet to be described hereinafter in greater detail, in a parking brake module 22. Both the primary electronic service brake control unit 14 and the parking brake control unit 18 are connected via a vehicle BUS 24 to a unit for autonomous driving 25. The unit for autonomous driving 25 provides in particular trajectory signals, which are then implemented by the primary electronic service brake control unit in order to brake the commercial vehicle 1.

[0040] Signals are also provided via the vehicle BUS 24 which originate from the pneumatic brake system 4, specifically in particular also signals from wheel speed sensors 26a, 26b, 26c, 26d. These can then be further processed by the primary electronic service brake control unit 14 or also the unit for autonomous driving 25. The primary electronic service brake control unit 14 controls a rear axle modulator 28 and a front axle modulator 30 in a manner known in principle. The rear axle modulator 28 is connected to a first compressed air reservoir 29 and is fed therefrom with a reservoir pressure, as is known in principle in the prior art. Depending on the brake signals provided at the primary electronic service brake control unit 14, the rear axle modulator 28 provides a rear axle brake pressure pBH at the rear axle service brake actuators 16c, 16d. The front axle modulator 30 is connected similarly to a second compressed air reservoir 31 and is fed therefrom. The front axle modulator 30 likewise receives brake signals from the primary electronic service brake control unit 14 and controls analogously a front axle brake pressure pBV at the service brake actuators 16a, 16b of the front axle VA. In this way, the commercial vehicle 1 can be electronically braked. In order to be able to brake the commercial vehicle 1 also manually, a brake value generator 32 is provided in the embodiment shown here (FIG. 1) and is connected pneumatically both to the first compressed air reservoir 29 and to the second compressed air reservoir 31 and can pneumatically trigger the control of the front axle brake pressure pBV and rear axle brake pressure pBH. This is also known in the prior art and will not be described in greater detail. The brake value generator 32 can also be omitted for autonomous commercial vehicles 2.

[0041] The brake system 4 is configured to receive an emergency stopping signal SN. In the embodiment shown in FIG. 1, three different ways of being able to receive the emergency stopping signal SN are shown by way of example. Firstly, an emergency stop switch 31 is shown schematically, which can be arranged for example on the outside of the commercial vehicle 1 so that it is easily accessible to staff located in the vicinity of the commercial vehicle 1. The emergency stop switch 34 is connected via an emergency stopping signal line 36 to the primary electronic service brake control unit 14 and provides the emergency stopping signal SN thereto. The emergency stop switch 34 may additionally (not shown here) also be connected to the electronic parking brake control unit 18 in order to be able to also provide the emergency stopping signal SN thereto directly. The emergency stop switch 34 could also be connected to the vehicle BUS 24. In the embodiment shown in FIG. 1, the emergency stopping signal SN is received by the primary electronic service brake control unit and is provided therefrom via the vehicle BUS 24 to other elements in the commercial vehicle 1.

[0042] As a second variant, it is shown in FIG. 1 that a wireless emergency stopping signal receiver 38 is provided in the commercial vehicle 1 and is coupled directly to the vehicle BUS 24. The wireless emergency stopping signal receiver 38 can be formed for example as a mobile radio receiver and can receive, via a remote transmitter, an emergency stopping signal SN, which it then provides via the vehicle BUS 24 to the corresponding units of the brake system 4.

[0043] As a further variant it is shown in FIG. 1 that the emergency stopping signal SN can also be a fully internal emergency stopping signal SN and in particular can be provided from the unit for autonomous driving 25. If this identifies that an emergency situation is present, in which an emergency stopping of the commercial vehicle 1 is necessary, it can output the emergency stopping signal SN, which is then received in the shown embodiment via the vehicle BUS 24 by the primary electronic service brake control unit 14 and the electronic parking brake control unit 18.

[0044] It can also be provided that two or all of these three variants are provided in a commercial vehicle 1. The disclosure is explicitly not limited to only one of these three variants or precisely one shown variant being implemented. Rather, it is decisive that the emergency stopping signal SN is received by the brake system 4.

[0045] As soon as the emergency stopping signal SN is received by the primary service brake system 10, specifically in particular by the primary electronic service brake control unit 14, the primary electronic service brake control unit 14 prompts the commercial vehicle 1 to be braked. To this end, it prompts the front axle modulator 30 to provide the front axle brake pressure pBV and the rear axle modulator 28 to provide the rear axle brake pressure pBH. These brake pressures pBV, pBH can be controlled, as is usual, in a slip controlled manner, also with use of ABS valves 40a, 40b, as are provided on the front axle VA. This braking is preferably performed with maximum deceleration, without the commercial vehicle 1 becoming unstable. A stop in lane maneuver is preferably performed in this way. Preferably, no further steering takes place here, in particular no evasive steering or the like. The commercial vehicle 1 is preferably stopped along the planned trajectory.

[0046] As soon as the speed of the commercial vehicle 1, which is ascertained either via the wheel speed sensors 26a d or via further units, such as the unit for autonomous driving 25, drops below a predetermined threshold value, it is assumed that the commercial vehicle 1 has reached a standstill, and the commercial vehicle 1 has been stopped as a result of the parking brake system 12 actuating parking brake actuators 42a, 42b of the parking brake system 12.

[0047] The parking brake system 12 is supplied with compressed air via a third compressed air reservoir 42. The electronic parking brake control unit 18 is connected via the vehicle BUS 24 to the unit for autonomous driving 25 and to the primary electronic service brake control unit 14. The electronic parking brake control unit 18 can additionally also be connected directly to the emergency stop switch 34, although this is not shown in FIG. 1. In order to actuate the parking brake actuators 42a, 42b, which are formed here as spring brake cylinders 43a, 43b, the parking brake module 21, prompted by the electronic parking brake control unit 18, deaerates the spring brake cylinders 43a, 43b, which then close. In driving operation, when the spring brake cylinders 43a, 43b are to be deaerated, the electronic parking brake control unit 18 prompts the control of a parking brake pressure pF at a spring brake connection 46 of the spring brake module 22 provided for this purpose. In the event that the speed of the commercial vehicle 1 does not drop below the predetermined threshold value, it is preferably provided that the parking brake system 12 actuates the parking brake actuators 42a, 42b once a predetermined emergency stop time has elapsed, in order to thus achieve braking of the commercial vehicle 1. The electronic parking brake control unit 18 can perform the deaeration of the spring brake cylinders 43a, 43b, which is required in this case, in a stepped manner so that locking of the rear axle HA can be avoided. To this end, the electronic parking brake control unit 18 can use wheel speed signals SR from the wheel speed sensors 26a 26d.

[0048] Also for the case that the primary electronic service brake control unit 14 cannot perform the braking in response to the emergency stopping signal SN or cannot perform such braking correctly, this is taken over by the electronic parking brake control unit 18. For this purpose, it can again be provided that the primary electronic service brake control unit 14 sends a corresponding request signal to the electronic parking brake control unit 18, or the parking brake control unit 18 determines that the primary electronic service brake control unit 14 is not functioning or is not functioning correctly, because the electronic parking brake control unit 18 receives a time out signal or the like. For this case, the electronic parking brake control unit 18 can carry out the braking of the commercial vehicle 1 in response to the receipt of the emergency stopping signal SN. For this purpose too, the electronic parking brake control unit 18 receives the emergency stopping signal SN.

[0049] The predetermined emergency stopping time can be ascertained on the one hand by the electronic parking brake control unit 18, the primary electronic service brake control unit 14, the unit for autonomous driving 25, or another superordinate or subordinate unit. In particular, the emergency stopping time can be determined on the basis of the speed VF of the commercial vehicle 1 received at the time of the emergency stopping signal SN, wheel speed signals SR from the wheel speed sensors 26a 26d, friction values FE, or other parameters (cf. also FIG. 3).

[0050] In the embodiment of the brake system 4 shown in FIG. 1, a trailer control valve 47 is also provided in addition and is likewise supplied with reservoir pressure from the third compressed air reservoir 42 and, at a trailer coupling head, controls a trailer brake pressure pBA for a potential connected trailer. The trailer control valve 47 may also be formed as a module and may have its own electronic control unit.

[0051] It is also conceivable and preferred that the primary electronic service brake control unit 14 is integrated with the rear axle modulator 28 and/or the front axle modulator 30 and module. It is also conceivable that the primary electronic service brake control unit 14 is integrated with the electronic parking brake control unit 18 in a structural unit, a printed circuit board, or the like. The two electronic control units 14, 18, however, are preferably separate. In the embodiment shown in FIG. 1, the primary electronic service brake control unit 14 and the electronic parking brake control unit 18 are supplied with electrical energy from a common voltage source 48. Here, however, it is conceivable and preferred that two separate voltage sources are provided for the primary electronic service brake control unit 14 and the electronic parking brake control unit 18, so that these can be supplied independently of one another with electrical energy. This is advantageous if one of the two voltage sources should fail, so that in each case the other of the electronic control units 14, 18 can continue to be operated. The parking brake valve unit 20 of the parking brake system 12 can be monostable or bistable.

[0052] FIG. 2 illustrates an example of the parking brake valve unit 20 which is bistable.

[0053] A reservoir connection 49, to which a first main line portion 53.1 of a main line 53 connects, is configured to receive compressed air for the parking brake module 22 and in particular the parking brake valve unit 20. Further along the main line 53, between a second main line portion 53.2 and a third main line portion 53.3, there is arranged a main line check valve 86, which is configured to open in the filling direction, that is, in the direction a filling flow SP flowing from the reservoir connection 49 into the main line 53, and to block in the counter direction.

[0054] The third main line portion 53.3 is adjoined by a relay valve 52 of a main valve unit 50, wherein the relay valve 52 is connected via a second main valve connection 52.2 to the third main line portion 53.3. The relay valve 52 is configured to pneumatically connect the second main valve connection 52.2 and a third main valve connection 52.3 via corresponding application of pressure to a control connection 52.4, in order to provide the parking brake pressure pF at the third main valve connection 52.3. The third main valve connection 52.3 is in turn connected to a fourth main line portion 53.4. Via a second main line branch 81.2, the fourth main line portion 53.4 is connected on the one hand via a sixth main line portion 53.6 to a pressure sensor 92 and on the other hand 11 to provide the parking brake pressure pF 11 via a fifth main line portion 53.5 to a spring brake connection 46.

[0055] The main line 53 has, between its first main line portion 53.1 and the second main line portion 53.2, a first main line branch 81.1, from which a fourth control line portion 82.4 of a control line 82 leads to a first bistable valve connection 72.1 of a bistable valve 72 of a pilot valve assembly 70.

[0056] The bistable valve 72 of the pilot valve assembly 70 is formed as a bistable 3/2 way solenoid valve, which is shown in the present case in a deaeration position 72B. The bistable valve 72 is configured to produce, in an aeration position 72A CI not shown here 11 a pneumatic connection between the first bistable valve connection 72.1 and a third bistable valve connection 72.3.

[0057] The pilot valve assembly 70 has a holding valve 76. The third bistable valve connection 72.3 is connected via a third control line portion 82.3 of the control line 82 to a first holding valve connection 76.1 of the holding valve 76. The pilot valve assembly can also be formed as a structural unit, however, it is also equally possible that the bistable valve 72 and the holding valve 76 are formed as independent components.

[0058] The holding valve 76 in the present case is monostable and is preferably formed as a normally open 2/2 way solenoid valve and is shown in the present case in its holding position 76A. In the holding position 76A, which is present in particular when the holding valve 76 is energized, the pneumatic connection between the first holding valve connection 76.1 and a second holding valve connection 76.2 is separated.

[0059] A second control line portion 82.2 is connected to the second holding valve connection 76.2. The second control line portion 82.2 is then pneumatically connected to a second selection valve connection 54.2 of a selection valve 54 formed in the present case as a shuttle valve 56. The shuttle valve 56 has a bias spring 56.1, which presses a valve body with a spring force against a first selection valve connection 54.1 and thus holds the shuttle valve 54 in a first valve position under a spring bias. In this valve position, the second selection valve connection 54.2 is pneumatically connected to the third selection valve connection 54.3.

[0060] A first control line portion 82.1 is connected to the third selection valve connection 54.3 and is in turn pneumatically connected to the control connection 52.4 of the relay valve 52. By way of the application of the control connection 52.4, the relay valve 52 can be actuated to control the parking brake pressure pF at the third main valve connection 52.3.

[0061] By way of the selection valve unit 54, a further, alternative compressed air source can be connected to the control connection 52.4 for the purpose of actuating the relay valve 52. For this purpose, an auxiliary brake pressure connection 41 is pneumatically connected in the present case via a fifth control line portion 82.5 to the first selection valve connection 54.1. The auxiliary brake pressure can be, in particular, a manually controlled pressure, which serves to manually release the spring brake cylinders once the commercial vehicle 1 has stopped, for example once the emergency stopping signal SN has been received.

[0062] In the embodiment shown here, whichever of the first and second selection valve connections 54.1, 54.2 is at the higher pressure is always pneumatically connected via the shuttle valve 54 to the third selection valve connection 54.3. Here, according to the operating principle of a shuttle valve, the other selection valve connection 54.1, 54.2 is always blocked by the valve body 54.5, so that the pressures applied at both selection valve connections 54.1, 54.2 are not added together, thus avoiding a potentially damaging pressure overload at the control connection 52.4.

[0063] A second bistable valve connection 72.2 of the bistable valve 72 is connected by a first deaeration line portion 84.1 of a deaeration line 84. In a deaeration position 72B of the bistable valve, the third bistable valve connection 72.3 is pneumatically connected to the second bistable valve connection 72.2. In this deaeration position 72B, the third control line portion 82.3 of the control line 82 is thus pneumatically connected to the first deaeration line portion 84.1.

[0064] The first deaeration line portion 84.1 is connected to by a second deaeration line portion 84.2, which is in turn connected to a deaeration connection 23 of the parking brake module 22. A third deaeration line portion 84.3 extends from a first main valve connection 52.1 of the relay valve 52 to a deaeration line junction point wherein the deaeration line junction point 85.1 is arranged in the deaeration line 84 between the first deaeration line portion 84.1 and the second deaeration line portion 84.2.

[0065] An aeration and thus release of the spring brake cylinders 43a, 43b is thus implemented by way of a control of a control pressure pS at the control connection 52.4 of the relay valve, via which at least one spring brake cylinder 43a, 43b is aerated in order to release the parking brake.

[0066] In order to aerate the spring brake cylinders 43a, 43b in normal driving operation and thus release them, the holding valve 76 is initially switched to the release position 76b by providing a signal S1 from the electronic parking brake unit 18. The bistable valve 72 is then switched into the aeration position 72a, not shown in FIG. 2, so that the parking brake pressure pF is controlled at the spring brake connection 46. This is achieved by providing pressure from the reservoir connection 49 via the fourth control line portion 82.4, the bistable valve 72, the third control line portion 82.3, the opened holding valve 76, the second control line portion 82.2 and the first control line portion 82.1 as control pressure pS at the control connection 52.4 of the relay valve 52. This increases the volume of the control pressure pS and provides the volume increased pressure as parking brake pressure pF at the spring brake connection 46. The holding valve 76 can now initially be de energized again in order to thus confine the controlled control pressure pS and allow the parking brake pressure pF to be controlled independently of the switch position of the bistable valve 72. If the bistable valve 72 is now switched again to the deaeration position 72b, in which the second bistable valve connection 72.2 is connected to the deaeration connection 23, the control pressure pS can be removed by de energizing the holding valve 76, and consequently the spring brake connection 46 can likewise be deaerated. In this way, a fail safe configuration can be provided. This arrangement of the pilot unit 70 is understood to be a monostable conversion of the bistable pilot unit 70.

[0067] In the event that the parking brake valve unit 20 is to be fully bistable, the holding valve 76 can simply be omitted. In the event that the parking brake valve unit 20 is to be fully monostable, the holding valve 76 can likewise be omitted and the bistable valve 75 is to be replaced by a conventional 3/2 way valve, which is biased in the deaeration position 72b. The auxiliary brake pressure connection 41 can likewise be omitted, as can also the shuttle valve 54.

[0068] The parking brake valve unit 20 can also be formed without a relay valve 52. In this case, the bistable valve 72 or a corresponding monostable 3/2 way valve would be connected directly to the reservoir connection 49, the deaeration connection 23 and the spring brake connection 46, in order to connect it selectively to the reservoir connection 49 or the deaeration connection 23.

[0069] FIG. 3 now illustrates an overview. The individual elements are shown merely as blocks. Besides the primary service brake system 10, in the embodiment shown here (FIG. 3), a secondary service brake system 100 is also provided. This includes a secondary electronic service brake control unit 102, which for example can be housed in its own electronic control unit, for example the rear axle modulator 28 or the trailer control valve 47, or can be formed as an instance of the primary electronic service brake control unit 14. The secondary service brake system 100 relies on the same compressed air reservoir 29, 31, 42 as the primary service brake system 10 and also actuates the same service brake actuators 16a 16d. The secondary service brake system, however, can also be supplied by a further voltage source independent of the voltage source 48. It can also be provided that the secondary service brake system 100 relies on other additional compressed air reservoirs, not shown here in FIG. 1, or is fed exclusively from the third compressed air reservoir 42.

[0070] In terms of function, the secondary service brake system 102 is connected between the primary service brake system 10 and the parking brake system 12. When, from an emergency stop unit 104, which by way of example represents the emergency stop switch 34, the wireless emergency stop signal receiver 38 or another unit that can provide the emergency stopping signal SN provides the emergency stopping signal SN to all three systems, that is, the primary service brake system 10, the secondary service brake system 100 and the parking brake system 12. It can also be provided that the emergency stop unit 104 provides the emergency stopping signal SN only to one of these systems, and the systems 10, 12, 100 communicate with one another in order to provide the emergency stopping signal SN to all three systems.

[0071] In the embodiment shown here (FIG. 3), the primary service brake system 10 is additionally connected to the secondary service brake system 100 and provides thereto a primary health status SH1 and a primary stability status SB. The secondary service brake system 100 can ascertain on this basis whether the primary service brake system 10 is able to implement the emergency stopping signal SN and brake the commercial vehicle 1. If this is the case, the secondary service brake system 100 is not engaged. If the secondary service brake system 100 ascertains that the primary service brake system 10 is unable to implement the emergency stopping signal, the secondary service brake system 100 implements the emergency stopping signal and brakes the commercial vehicle 1 accordingly. Here too, it is again true that as soon as the speed drops below the speed threshold value VS (cf. FIG. 3), the parking brake system 12 is engaged and actuates the parking brake actuators 42a, 42b. Also if an emergency stopping time TS (cf. FIG. 3) is exceeded, the parking brake system 12 actuates the parking brake actuators 42a, 42b.

[0072] The parking brake system 12 in turn receives a secondary stability status SB2 and a secondary health status SH2 from the secondary service brake system 100 and ascertains, on that basis, whether the secondary service brake system is able to implement the emergency stopping signal SN. If this is not the case, the parking brake system 12 can also implement the braking of the commercial vehicle 1 in response to the receipt of the emergency stopping signal SN, preferably can brake the vehicle in steps, in order to thus perform a stop in lane maneuver. As soon as a standstill has been reached, the parking brake system 12 actuates the parking brake actuators 42a, 42b fully, in order to secure the commercial vehicle 1 in the stationary state. The parking brake system 12 additionally also receives a speed VF of the commercial vehicle 1 and a friction coefficient FE, which may correspond to an expected friction coefficient. The vehicle speed VF is preferably the vehicle speed that is present at the time of receipt of the emergency stopping signal SN. On this basis, the parking brake system 12 can ascertain whether the commercial vehicle 1 is at a standstill and/or whether its speed has dropped below the predetermined speed threshold value VS. The parking brake system 12 can also bring about a stepped braking of the commercial vehicle 1 on the basis of these parameters. The predetermined speed threshold value VS and the predetermined emergency stopping time TN are for this purpose saved in an internal memory of the parking brake system 12 or are ascertained therefrom.

[0073] 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.

List of Reference Sings (Part of the Description)

[0074] 1 commercial vehicle [0075] 2 autonomous commercial vehicle [0076] 4 pneumatic brake system [0077] 6a, 6b front wheels [0078] 8a, 8b rear wheels [0079] 10 primary service brake system [0080] 12 parking brake system [0081] 14 primary electronic service brake control unit [0082] 16a, 16b, 16c, 16d service brake actuators [0083] 18 electronic parking brake control unit [0084] 20 parking brake valve unit [0085] 22 parking brake module [0086] 23 deaeration connection [0087] 24 vehicle BUS [0088] 25 unit for autonomous driving [0089] 26a, 26b, 26c, 26d wheel speed sensors [0090] 28 rear axle modulator [0091] 29 first compressed air reservoir [0092] 30 front axle modulator [0093] 31 second compressed air reservoir [0094] 32 brake value generator [0095] 34 emergency stop switch [0096] 36 emergency stopping signal line [0097] 38 wireless emergency stopping signal receiver [0098] 40b ABS valves [0099] 41 auxiliary brake pressure connection [0100] 42a, 42b parking brake actuators [0101] 43a, 43b spring brake cylinders [0102] 44 third compressed air reservoir [0103] 46 spring brake connection [0104] 47 trailer control valve [0105] 48 voltage source [0106] 49 reservoir connection [0107] 50 main valve unit [0108] 52 relay valve [0109] 52.1 first main valve connection [0110] 52.2 second main valve connection [0111] 52.3 third main valve connection [0112] 52.4 control connection [0113] 53 main line [0114] 53.1 first main line portion [0115] 53.2 second main line portion [0116] 53.3 third main line portion [0117] 53.4 fourth main line portion [0118] 53.5 fifth main line portion [0119] 53.6 sixth main line portion [0120] 54 selection valve [0121] 54.1 first selection valve connection [0122] 54.2 second selection valve connection [0123] 54.3 third selection valve connection [0124] 56 shuttle valve [0125] 56.1 bias spring [0126] 70 pilot valve assembly [0127] 72 bistable [0128] 72.1 first bistable valve connection [0129] 72.1 second bistable valve connection [0130] 72.3 third bistable valve connection [0131] 72A aeration position [0132] 72B deaeration position [0133] 76 holding valve [0134] 76.1 first holding valve connection [0135] 76.2 second holding valve connection [0136] 76A holding position [0137] 76B release position [0138] 81.1 first main line branch [0139] 81.2 second main line branch [0140] 82 control line [0141] 82.1 first control line portion [0142] 82.2 second control line portion [0143] 82.3 third control line portion [0144] 82.4 fourth control line portion [0145] 84 deaeration line [0146] 84.1 first deaeration line portion [0147] 84.2 second deaeration line portion [0148] 84.3 third deaeration line portion [0149] 85.1 deaeration line junction point [0150] 86 main line check valve [0151] 92 pressure sensor [0152] 100 secondary service brake system [0153] 102 secondary electronic service brake control unit [0154] 104 emergency stopping unit [0155] FE friction coefficient [0156] HA rear axle [0157] pBA trailer brake pressure [0158] pBH rear axle brake pressure [0159] pBV front axle brake pressure [0160] pF parking brake pressure [0161] pS pressure controlled by the bistable valve [0162] SB filling flow [0163] SB1 primary stability status [0164] SB2 secondary stability status [0165] SH1 primary health status [0166] SH2 secondary health status [0167] SN emergency stopping signal [0168] SR wheel speed signal [0169] TN predetermined emergency stopping time [0170] VA front axle [0171] VF speed [0172] VS predetermined speed threshold valve