Method and device for safely braking a trailer

Abstract

The invention relates to a method for safely braking a trailer (204) of a vehicle combination (200) comprising a motor vehicle (202) and the trailer (204). The motor vehicle (202) has an electronically controllable pneumatic motor vehicle braking system (1) and the trailer (204) has a pneumatic trailer braking system (2). The motor vehicle braking system (1) and the trailer braking system (2) are connected by at least one trailer control line (6) and one trailer supply line (4). The trailer braking system (2) has at least one trailer braking circuit (3) comprising a trailer supply reservoir (8) for providing a trailer supply pressure (pVA) for the trailer braking circuit (3), service brake actuators (10a-10f) and spring-brake actuators (12a-12d). According to the invention, in response to a requirement (SPB) for safe braking of the trailer (204), the motor vehicle (202) reduces the trailer supply pressure (pVA) in the trailer braking circuit (3), so that the spring actuators (12a-12d) of the trailer (204) tighten and safely brake the trailer (204).

Description

[0001] Method and device for safely braking a trailer

[0002] The invention relates to a method for safely braking a trailer of a vehicle combination comprising a motor vehicle and a trailer, wherein the motor vehicle has an electronically controllable pneumatic motor vehicle braking system and the trailer has a pneumatic trailer braking system, wherein the motor vehicle braking system and the trailer braking system are connected by at least one trailer control line and one trailer supply line, and the trailer braking system has at least one trailer braking circuit with a trailer reservoir for providing a trailer reservoir pressure for the trailer braking circuit, service brake actuators, and spring-loaded actuators. The invention further relates to an electronically controllable pneumatic motor vehicle braking system for a motor vehicle of a vehicle combination and to a motor vehicle having an electronically controllable pneumatic motor vehicle braking system.

[0003] The method presented here, both the towing vehicle braking system and the towing vehicle, is aimed at an application in which the towing vehicle has an electronically controllable pneumatic braking system and the trailer, in particular, has a purely pneumatic trailer braking system with an electrified parking brake. When parking trailers of a vehicle combination, they must be secured. This is usually achieved through a two-stage securing mechanism: firstly, by engaging the trailer's spring-loaded actuators or applying the trailer's service brake, and secondly, manually securing them with wedges that are manually placed on the trailer's wheels to prevent the trailer from rolling away.Trailers are typically designed in such a way that either a driver in the towing vehicle can provide a parking brake signal, which then engages the spring-loaded actuators in the trailer, or the supply line between the towing vehicle and trailer is simply released, which in turn activates a pneumatic circuit which in this case either vents the spring-loaded actuators or vents the trailer's service brake actuators in order to immobilize the trailer. If the trailer is to be maneuvered in a yard, for example, trailers typically have a manual switch with which the operator on the trailer can release the spring-loaded actuators or service brake actuators in order to then maneuver the trailer. The manually provided wedges serve as additional security in the event that the spring-loaded actuators or service brake actuators are no longer activated.The trailer's service brake actuators may be released unintentionally, for example by operating the manual switch on the trailer.

[0004] A pneumatic braking device for a commercial vehicle is known from DE 10 2015 119 135 A1. The pneumatic braking device has at least one pneumatically controllable spring-loaded actuator for a parking brake of the commercial vehicle and an electronic parking brake device with at least one control electronics unit, at least one bistable valve unit, at least one first valve unit, by means of which a parking brake of the trailer of the commercial vehicle can be deactivated when the parking brake of the commercial vehicle is activated, and at least one second valve unit, which can be connected in such a way that the parking brake of the trailer can be activated when the system pressure for supplying the parking brake of the trailer drops.This second valve device can, for example, have a pressure sensor, by means of which a pressure drop in the system pressure for the trailer's parking brake below a predetermined threshold can be determined and a signal can be generated, based on which the trailer's parking brake is activated by the control electronics. DE 10 2015 119 135 A1 therefore provides for generating a signal when the system pressure drops, for example due to a prolonged standstill or a fault, and then activating the trailer's parking brake and engaging it to prevent the trailer from rolling away unintentionally when the system pressure rises again. However, this cannot solve the problem of the switch for releasing the trailer's parking brake being inadvertently activated.

[0005] Furthermore, DE 10 2017 118 529 A1 discloses an electronically controlled trailer brake control unit for a trailer of a commercial vehicle. The trailer brake control unit integrates both a modulator valve device, which can be embodied as an EBS control unit, and a spring-loaded brake valve device. The spring-loaded brake valve device can provide spring-loaded brake functions such as a parking function, a release function, an override function, a spring-loaded brake immobilization function, an uncontrolled emergency braking function, a controlled spring-loaded emergency braking function, a reservoir-controlled spring-loaded brake function, an automatic parking brake actuation function, an auxiliary braking function, an anti-skid braking function, a test function, or an emergency braking prevention function.Similar to what has already been described with reference to DE 10 2015 119 135 A1, the emergency braking function includes a functionality whereby emergency braking is automatically initiated if the pressure in the coupling head supply or in the supply line drops.

[0006] The object of the present invention is to improve the securing of the trailer when stationary and, in particular, to prevent the trailer from rolling away unintentionally.

[0007] The invention solves the problem in a method of the type mentioned at the outset in that, in response to a request for safe braking of the trailer, the motor vehicle causes a reduction of the trailer supply pressure in the trailer brake circuit, so that the spring-loaded actuators of the trailer are applied and brake the trailer safely.

[0008] Unlike prior art, the invention utilizes a targeted reduction in the trailer supply pressure in the trailer brake circuit to apply the spring-loaded actuators. Spring-loaded actuators are designed to apply due to spring force and have a pressure chamber that can be pressurized with compressed air to release the brake pads against the spring force. This means that spring-loaded actuators apply when pressure is off, while they open when pressurized. The invention takes advantage of this and specifically reduces the trailer supply pressure to utilize the application of the spring-loaded actuators. If the trailer is parked in this state, even if the release switch on the trailer itself is accidentally activated, no pressure is released, and spring-loaded actuators cannot then be released.In some circumstances, it may be sufficient to park the trailer in this state without additional wheel chocks. Thus, according to the invention, not only is the trailer's parking brake engaged and spring-loaded actuators vented by a valve circuit, but the trailer's system pressure is reduced to such an extent that the spring-loaded actuators are applied regardless of the valve position. This can increase the safety of the parked trailer against rolling away.

[0009] According to the invention, the request for safe braking is issued by the towing vehicle itself. This includes the request for safe braking being provided, for example, manually by a driver in the cockpit by actuating a corresponding switch or automatically by a unit for autonomous driving. It can also be provided, for example, by an electronic air treatment unit or other systems in the towing vehicle. Particularly preferably, the towing vehicle braking system provides the request for safe braking of the trailer, for example when the towing vehicle braking system detects or is requested to stop the entire vehicle combination. It is also conceivable and preferred that the request for safe braking be provided by a backup unit, preferably a backup unit of the towing vehicle braking system, in an emergency.If, for example, normal braking of the trailer is not possible or no longer possible correctly, the requirement for safe braking according to the invention can be provided and, as a result, the trailer supply pressure in the trailer brake circuit can be reduced in order to apply the spring-loaded actuators and to brake the trailer safely.

[0010] Preferably, the trailer pressure is reduced to a value below a minimum pressure, preferably the release pressure of the spring-loaded actuators. The minimum pressure can be 1 bar or less, for example. Other minimum values ​​are also conceivable, but these should always be selected to ensure reliable application of the spring-loaded actuators.

[0011] The trailer braking system can be purely pneumatic, for example, an ABS system, or electronically controlled. In the latter case, an electronic connection (ISO-BUS) is usually provided between the towing vehicle braking system and the trailer braking system, via which signals can also be transmitted.

[0012] In a preferred embodiment, the method comprises the step of preventing pressure control via the trailer supply line to prevent the trailer reservoir from filling. This allows the trailer to maintain its safely braked state, even if, for example, an air pressure treatment unit in the towing vehicle is supplying compressed air. This prevention preferably occurs before the trailer supply pressure in the trailer brake circuit is lowered, so that no pressure is supplied during the lowering process.

[0013] In order to prevent pressure control via the trailer supply line, in a first variant the trailer supply line can be disconnected to prevent the trailer storage tank from filling up. To do this, for example, a driver of the vehicle combination can manually uncouple the supply line. However, it is also preferred that an automated coupling system is provided, which in this case automatically disconnects the trailer supply line. In a further variant, it is provided that the prevention of pressure control via the trailer supply line is implemented by deactivating compressed air supply via the trailer supply line. To do this, for example, a compressor can be deactivated so that refilling of the trailer storage tank is prevented.The towing vehicle braking system preferably deactivates the compressed air supply to a trailer brake circuit on the towing vehicle side or the compressed air reservoir in the towing vehicle that supplies the trailer supply line with compressed air. Typically, a separate reservoir is provided in the towing vehicle to supply the trailer reservoir, which can, for example, be shut off for this purpose. If a separate compressor is provided for the trailer in the towing vehicle, it may be sufficient to deactivate this compressor. The pressure control should be prevented or reduced in such a way that the volume flow consumed in the trailer exceeds, preferably significantly exceeds, the volume flow supplied.

[0014] In a further variant, pressure control via the trailer supply line can be prevented by causing at least one valve arrangement to switch to block, vent, and / or throttle the trailer supply line. Preferably, the switching of the valve arrangement is initiated by the motor vehicle's braking system. Pressure control for filling the trailer reservoir can also be prevented by throttling, since in a throttled state, only a small amount of air is delivered, which is insufficient to fill the trailer reservoir.

[0015] In a preferred embodiment, the valve arrangement that is triggered to switch is a breakaway safety valve of the towing vehicle braking system. Such breakaway safety valves are typically provided in towing vehicle braking systems, for example in a so-called trailer control valve or trailer control module. Breakaway safety valves are designed such that, upon a breakaway of the trailer supply line, they switch pneumatically triggered and block or at least restrict the connection between the corresponding coupling head and the towing vehicle's supply. According to the embodiment proposed here, however, the switching of the breakaway safety valve is triggered or requested by the towing vehicle braking system itself in order to prevent further pressure control to the trailer.In this case, it is not necessary to disconnect the trailer supply line, because the activation of the safety valve also prevents pressure build-up and the trailer's spring-loaded actuators remain securely clamped.

[0016] In a preferred embodiment, the breakaway safety valve is pneumatically switchable, and the motor vehicle braking system applies a breakaway control pressure to the breakaway safety valve in such a way that it switches and prevents pressure from being released via the trailer supply line. Pneumatically switching the breakaway safety valve is a particularly simple option, as these typically feature pneumatic feedback and self-locking, and thus usually have a pneumatic control connection.

[0017] It is further preferred that the valve arrangement comprises an electromagnetic deactivation valve unit that can be controlled by the motor vehicle. The electromagnetic deactivation valve unit can preferably be controlled by the motor vehicle's braking system. The electromagnetic deactivation valve unit can, for example, directly block or throttle the trailer supply line, or else provide the breakaway control pressure for the breakaway safety valve. For this purpose, the electromagnetic deactivation valve unit can receive a supply or other working pressure from a pressure circuit provided in the motor vehicle, such as a compressed air reservoir that is not provided for the trailer or in another system. It is further preferred that the electromagnetic deactivation valve unit is pneumatically connected upstream and / or downstream of a trailer control valve of the motor vehicle's braking system.The electromagnetic deactivation valve unit can, for example, be pneumatically connected upstream of the trailer control valve by connecting the electromagnetic deactivation valve unit between a compressed air reservoir provided for the trailer control valve and the corresponding supply connection provided on the trailer control valve. By switching the electromagnetic deactivation valve unit, it can interrupt the connection between the compressed air reservoir and the supply connection on the trailer control valve, thus preventing compressed air from being supplied from the trailer control valve to the trailer.On the other hand, the electromagnetic deactivation valve unit can also be connected downstream of the trailer control valve of the motor vehicle braking system by being arranged between a corresponding connection of the trailer control valve and the coupling head for connecting the trailer supply line and thus being able to interrupt this connection.

[0018] Further preferably, the valve arrangement can comprise an electromagnetic trailer vent valve in the trailer brake system, which can be controlled by the motor vehicle. Such a trailer vent valve can, for example, be arranged on the trailer reservoir in such a way that it can be vented directly into the environment.

[0019] In a further preferred embodiment of the method, lowering the trailer supply pressure comprises actuating the service brake actuators of the trailer brake system. This allows the trailer to come to a stop more quickly, since service brake actuators can typically react somewhat faster than spring-loaded actuators. At the same time, however, air consumption in the trailer is increased, so that the trailer supply pressure can be lowered more quickly. Preferably, the service brake actuators of the trailer brake system are actuated in such a way that high air consumption is achieved.

[0020] For example, the service brake actuators are actuated in a pulsed manner, namely by alternately pressurizing and venting the service brake actuators. If the service brake actuators are pressurized, vented, and re-pressurized in rapid succession, air consumption is particularly high, and the trailer supply pressure is reduced as quickly as possible. This also allows for particularly rapid trailer braking.

[0021] In a further preferred embodiment, lowering the trailer supply pressure comprises actuating a trailer parking brake.

[0022] Preferably, the trailer parking brake is first applied by venting the spring-loaded actuators, and then the service brakes are applied in a pulsed manner. If the trailer is equipped with an anti-compound circuit, applying the service brakes will simultaneously vent and thus release the spring-loaded actuators to prevent overloading of the actuators. If the service brake actuators are even applied in a pulsed manner in this case, a particularly high air consumption is achieved, allowing the trailer pressure to be reduced particularly quickly.

[0023] Furthermore, it is preferred that lowering the trailer supply pressure comprises actuating an alternative air consumer in the trailer, preferably a level control and / or lift axle. Actuating the alternative air consumer in the trailer is preferably requested by the towing vehicle braking system, for example via the trailer bus. It is preferred that the request for safe braking is provided by the towing vehicle. Preferably, the request for safe braking is initiated by the towing vehicle braking system and particularly preferably by a subsystem of the towing vehicle braking system, such as a service brake system, a parking brake system, an electronic air treatment unit and / or a unit for autonomous driving of the towing vehicle. It is also conceivable that several of these systems can provide the request for safe braking, depending on availability and the event triggering the request.For example, if the entire vehicle combination is shut down and parked, it may be preferable for the request to be provided by the parking brake system of the towing vehicle's braking system. However, if it is an emergency braking in the event of a fault, it may be preferable for a unit for autonomous driving of the towing vehicle to provide this signal.

[0024] It is further preferred that, after the lowering of the trailer stock is complete, the towing vehicle is driven against the safely braked trailer to test the braking effect. For this purpose, the system that also provided the request for safe braking can provide a signal to start the towing vehicle. In this case, it is sufficient if only a very low force or torque is applied to test for the trailer's rolling. The trailer can then be uncoupled and safely parked.

[0025] In a second aspect, the invention achieves the object mentioned at the outset in an electronically controllable pneumatic motor vehicle braking system for a motor vehicle of a vehicle combination in that it comprises: a service braking system with a trailer control valve with a trailer supply connection for connecting a trailer supply line and a trailer brake pressure connection for connecting a trailer control line and at least one motor vehicle-side trailer brake circuit for supplying the trailer control valve with supply pressure, wherein the trailer control valve provides a trailer supply pressure at the trailer supply connection;and a primary brake control unit for controlling the service brake system, the primary brake control unit being connected to an autonomous driving unit and receiving brake request signals therefrom, the motor vehicle braking system being configured to cause the trailer reservoir pressure to drop in response to a request to safely brake a trailer connected to the motor vehicle, so that spring-loaded actuators of the trailer apply and safely brake the trailer.

[0026] It should be understood that the method according to the first aspect of the invention and the electronically controllable pneumatic motor vehicle braking system according to the second aspect have identical and similar sub-aspects, as particularly set forth in the dependent claims. To this extent, it is preferred that the motor vehicle braking system be configured to carry out a method according to one of the above-described preferred embodiments of a method according to the first aspect of the invention.

[0027] The motor vehicle braking system preferably comprises at least one valve arrangement for blocking the trailer supply connection. In a preferred embodiment, the valve arrangement comprises a breakaway safety valve. The breakaway safety valve is preferably pneumatically switchable, and the motor vehicle braking system preferably has an electromagnetic trigger valve unit for controlling a breakaway control pressure at the breakaway safety valve, such that it switches and prevents the pressure from being controlled via the trailer supply line.

[0028] In a preferred embodiment of the motor vehicle braking system, the trigger valve unit is integrated into the trailer control valve or arranged adjacent to it. Integrating the trigger valve unit into the trailer control valve offers space advantages, while an adjacent arrangement, preferably a flanged arrangement of the trigger valve unit to the trailer control valve, can be easily implemented and can also be retrofitted.

[0029] Preferably, the valve arrangement comprises an electromagnetic deactivation valve unit that can be controlled by the motor vehicle's braking system, preferably the primary brake control unit. The electromagnetic deactivation valve unit is pneumatically connected upstream and / or downstream of the trailer control valve. It can also be controlled by a secondary brake control unit or another electronic control unit of the motor vehicle.

[0030] In a preferred embodiment, a trailer brake pressure is applied to the trailer brake pressure port of the trailer control valve to reduce the trailer supply pressure. The trailer brake pressure triggers the activation of the trailer's service brake actuators, resulting in high air consumption in the trailer and rapid reduction of the trailer supply pressure.

[0031] In a third aspect, the invention achieves the object mentioned at the outset by a motor vehicle of the type mentioned at the outset, in particular a commercial vehicle, in that it has an electronically controllable pneumatic motor vehicle braking system according to one of the above-described preferred embodiments of a motor vehicle braking system according to the second aspect of the invention, as well as a unit for autonomous driving.

[0032] Embodiments of the invention will now be described below with reference to the drawings. These are not necessarily intended to represent the embodiments to scale; rather, the drawings are schematic and / or slightly distorted where this is useful for explanation. With regard to additions to the teachings immediately apparent from the drawings, reference is made to the relevant prior art. It should be noted that numerous modifications and changes to the form and detail of an embodiment can be made without deviating from the general idea of ​​the invention. The features of the invention disclosed in the description, in the drawings and in the claims can be essential for the further development of the invention, both individually and in any combination.Furthermore, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of ​​the invention is not limited to the exact form or detail of the preferred embodiments shown and described below, or limited to an object that would be more limited than the object claimed in the claims. For specified dimensioning ranges, values ​​within the stated limits are also intended to be disclosed as limit values ​​and to be used and claimed as desired. For the sake of simplicity, the same reference numerals are used below for identical or similar parts or parts with identical or similar functions.

[0033] Further advantages, features and details of the invention will become apparent from the following description of the preferred embodiments and from the drawings, which show:

[0034] Figure 1 shows a layout of a vehicle combination in a first embodiment;

[0035] Figure 2 is a schematic representation of a valve arrangement in a first embodiment;

[0036] Figure 3 is a schematic representation of a valve arrangement in a second embodiment;

[0037] Figure 4 shows a layout of a vehicle combination in a second embodiment; and in

[0038] Figure 5 shows a layout of a vehicle combination in a third embodiment.

[0039] Fig. 1 initially illustrates a vehicle combination 200 comprising a motor vehicle 202 and a trailer 204. The motor vehicle 202 has a motor vehicle braking system 1, and the trailer 204 has a trailer braking system 2. The motor vehicle braking system 1 is designed as an electronically controllable pneumatic braking system. In a generally known manner, it comprises a primary brake control unit 100, which is connected via a vehicle bus 102 to an autonomous driving unit 40 and receives braking request signals SBA from the latter. The primary brake control unit 100 then provides front axle brake signals SVA to a front axle VA of the motor vehicle 202 and rear axle brake signals SHA to a rear axle HA of the motor vehicle 202. A front axle brake circuit 104 is provided on the front axle VA and a rear axle brake circuit 106 is provided on the rear axle HA. The rear axle brake circuit 106 is fed via a first compressed air supply 108 and supplied with supply pressure pV.Furthermore, a rear axle modulator 110 is provided, which receives the supply pressure pV from the first compressed air supply 108 and, depending on the received rear axle brake signals SHA, controls a rear axle brake pressure pBHA to the first and second rear axle brake actuators 112a, 112b. Similarly, the front axle brake circuit 104 is supplied by a second compressed air supply 114, which also provides supply pressure pV. Furthermore, a front axle modulator 116 is provided on the front axle VA, which receives the supply pressure pV and, depending on the front axle brake signals SVA, provides a front axle brake pressure pBVA to the first and second front axle brake actuators 118a, 118b.

[0040] The primary brake control unit 100, the rear axle modulator 110 and the front axle modulator 116 together with the first and second compressed air supply 108, 114 form the service brake system of the motor vehicle brake system 1.

[0041] In addition, the motor vehicle braking system 1 also includes a parking brake module 120, which receives supply pressure pV from a third compressed air supply 122. The parking brake module 120 belongs to a parking brake system 121 and is connected both to an autonomous driving unit 40 via the vehicle bus 102 and to the primary brake control unit 100 via an internal bus 123. The parking brake module 120 includes its own intelligence and, in the motor vehicle braking system 1 shown here, also acts as a secondary brake control unit, which can partially replace the primary brake control unit 100 in the event of a fault.

[0042] Finally, a trailer control valve 30 is provided, which on the one hand receives supply pressure pV from the third compressed air supply 122, and on the other hand receives trailer brake signals SBT from the primary brake control unit 100. In the embodiment shown here, the trailer control valve 30 does not have its own intelligence, but in other embodiments, its own intelligence can also be provided for the trailer control valve 30.

[0043] The trailer control valve 30 is connected in a known manner to a trailer supply connection 32 and a trailer brake pressure connection 34, to which a trailer supply line 4 and a trailer control line 6 can be connected in a likewise known manner. The trailer supply connection 32 can also be designed as a red coupling head or connected to it, and the trailer brake pressure connection 34 can also be designed as a yellow coupling head or connected to it.

[0044] Supply pressure is provided to the trailer 2 via the trailer supply connection 32, and pneumatic control pressure for actuating the service brakes of the trailer 2 is provided to the trailer 2 via the trailer brake pressure connection 34. In the exemplary embodiment shown in Fig. 1, the motor vehicle braking system 1 also comprises a trailer BUS 124, via which signals can also be provided. In particular, valves in the trailer can be directly switched or other signals can be transmitted via the trailer BUS 124. However, the invention is not limited to this, and purely pneumatic trailers can also be used, which are controlled solely via the trailer supply line 4 and the trailer control line 6.

[0045] The trailer brake system 2 is also shown in Fig. 1 only as an example. The trailer brake system 2 has a trailer brake circuit 3 and a trailer reservoir 8 in which compressed air is pre-stored. The trailer reservoir 8 is fed from the motor vehicle brake system 1 via the trailer control valve 30. For this purpose, the trailer reservoir 8 is connected to the trailer supply line 4 via a protection valve 126 and a basically known so-called parking release safety valve 128. The trailer control line 6 is also then directly connected to a trailer control unit and a trailer parking brake module 132 via the parking release safety valve 128. Service brake actuators 10a - 10f of the trailer brake system 2 and spring-loaded actuators 12a - 12d are controlled in a known manner via the trailer control unit 130 and the trailer parking brake module 132.

[0046] In the prior art, when the trailer 204 is to be parked, for example, the parking brake of the trailer 204 is applied by the trailer parking brake module 132 venting the spring-loaded actuators 12a-12d. A vehicle driver can then use the parking release safety valve 128 to re-vent and thus release the spring-loaded actuators 12a-12d in order to maneuver the trailer 204. To prevent it from accidentally rolling away, wedges are usually placed against the trailer's wheels to mechanically secure it.

[0047] During ferry operation of trailer 204, the spring-loaded actuators 12a - 12d are ventilated and released.

[0048] Within the scope of the method for safely braking the trailer 204, the invention provides that, in response to a request SPB for safely braking the trailer 204, the motor vehicle 202 causes a reduction in the trailer supply pressure pVA in the trailer brake circuit 3. A reduction in the trailer supply pressure pVA in the trailer brake circuit 3 then automatically leads to the spring-loaded actuators 12a-12d of the trailer 204 being applied, thus safely braking the trailer 204. Since the trailer supply pressure pVA is systemically reduced, even upon actuation of the parking release safety valve 128, no further pressure can be applied to the spring-loaded actuators 12a-12f to release them. Rolling away of the trailer 204 is reliably prevented.

[0049] The request SPB for safe braking can, for example, be provided by the autonomous driving unit 40 via the vehicle bus 102 and received and implemented by the primary brake control unit 100. It is also conceivable and preferred for the request SPB to be provided via a parking brake switch 134 of the motor vehicle braking system 1 to, for example, the parking brake module 120, which then implements the request SPB and either immediately causes the trailer supply pressure pVA to be lowered, or first provides a corresponding signal to the primary brake control unit 100, which in turn then controls the trailer control valve 30 accordingly or causes the trailer supply pressure pVA to be lowered in another way.

[0050] To achieve this, on the one hand, the trailer reservoir 8 is vented, and on the other hand, a subsequent supply of reservoir pressure pV from the motor vehicle 202 to the trailer 204 is prevented. The venting of the trailer reservoir 8 can occur either directly, for example, by means of a vent valve provided directly on the trailer reservoir 8, which is switched separately, or by using consumers in the trailer 204, as described in detail below.

[0051] The use of consumers in the trailer 204 to empty the compressed air supply present in the trailer reservoir 8 is preferred because then no further modifications have to be made to the trailer 204 itself, and a motor vehicle 202 equipped with the corresponding motor vehicle braking system 1 can also operate and safely park conventional and unmodified trailers 204 as described herein.

[0052] The prevention of the re-supply of compressed air from the motor vehicle 202 to the trailer 204 can be achieved, for example, by switching off an electronic air treatment unit (not shown in Fig. 1) that feeds the third compressed air supply 122. In the exemplary embodiment shown here (Fig. 1), the third compressed air supply 122 is responsible for supplying the trailer 204 with compressed air. If the third supply 122 is no longer refilled with compressed air by an air treatment unit, the trailer supply tank 8 will not be refilled with compressed air either. Alternatively, the vehicle driver can also detach the trailer supply line 4 manually or by means of an automated uncoupling device, so that the re-supply of compressed air from the third supply tank 122 to the trailer 204 is also prevented in this way.

[0053] In the embodiment shown in Fig. 1, the motor vehicle braking system 1 comprises a valve arrangement 20 that can be switched to block, vent, and / or throttle the trailer supply line 4. In the embodiment shown in Fig. 1, the valve arrangement 20 comprises an electromagnetic deactivation valve unit 24 that can be switched to deactivate the pressure control via the trailer supply line 4. Specifically, the deactivation valve unit 24 in the embodiment shown in Fig. 1 is connected between the third compressed air supply 122 and the trailer control valve 30, more precisely, between the third compressed air supply 122 and a supply connection of the trailer control valve 30. The deactivation valve unit 24 is thus upstream or pneumatically connected upstream of the trailer control valve 30.For this purpose, the electromagnetic deactivation valve unit 24 can, for example, comprise a 2 / 2-way valve or 3 / 2-way valve, which, in a first switching position, establishes the pneumatic connection between the third compressed air supply 122 and the trailer control valve 30, and, in a second switching position, disconnects the connection between the third compressed air supply 122 and the trailer control valve 30 and preferably vents the supply connection of the trailer control valve 30. For this purpose, the electromagnetic deactivation valve unit 24 in the embodiment shown in Fig. 1 is connected to the primary brake control unit 100 and receives a deactivation switching signal SD therefrom. The deactivation switching signal SD is controlled by the primary brake control unit 100 in response to receiving the request SPB for safe braking of the trailer 204.In other embodiments, the deactivation valve unit 24 may also be connected to further electrical control units or even receive the deactivation switching signal directly from the autonomous driving unit 40.

[0054] If the deactivation switching valve 24 is brought into a switching position such that the third compressed air supply 122 is not pneumatically connected to the trailer control valve 30, compressed air cannot be supplied via the trailer supply line 4, and as soon as the pressure in the trailer reservoir 8 has fallen below a minimum pressure, preferably the release pressure of the spring-loaded actuators 12a - 12f, these clamp and cannot be released again as long as the deactivation valve unit 24 separates the third compressed air supply 122 and the trailer control valve 30.

[0055] Alternatively or additionally, it can also be provided that the compressed air supply via the trailer supply line 4 is prevented directly in or at the trailer control valve 30.

[0056] For this purpose, Figs. 2 and 3 show further embodiments. Figs. 2 and 3 each show a schematic circuit diagram of a trailer control valve 30. The trailer control valve 30 (cf. Fig. 2) has, as usual, a supply connection 31 to which supply pressure pV is provided, for example from the third compressed air supply 122 (Fig. 1), a trailer supply connection 32 for controlling trailer supply pressure pVA and a trailer brake pressure connection 34 for providing a trailer brake pressure pBA. Inside, the trailer control valve 30 has, in a known manner, a pilot control unit 35 and a relay valve 36 to convert the trailer brake signals SBT and to control the trailer brake pressure pBA in accordance with the trailer brake signals SBT.

[0057] In a manner that is also fundamentally known, the trailer control valve 30 has a breakaway safety valve 22, which is integrated into the trailer control valve 30 here, but can also be provided separately from it. The breakaway safety valve 22 is switched pneumatically and, for this purpose, has a breakaway safety valve control connection 22.1. In the prior art, this is typically connected to the trailer brake pressure line 34 or a pilot control path of the pilot control unit 35, so that if the trailer supply line breaks, i.e., if the trailer supply connection 32 is vented, the breakaway safety valve 22 is brought into the switching position not shown in Fig. 2, in which the supply connection 31 of the trailer control valve 30 is connected to the trailer supply connection 32 only via the throttle 22.2, but not via a larger cross-section as in the spring-loaded switching position shown in Fig. 2.

[0058] However, in the embodiment shown here (Fig. 2), the breakaway safety valve control port 22.1 is connected to the deactivation valve unit 24. In the embodiment shown in Fig. 2, the deactivation valve unit 24 is designed as a 3 / 2-way valve and has a first deactivation port 24.1, a second deactivation port 24.2, and a third deactivation port 24.3. The deactivation valve unit 24 is de-energized in the switching position shown in Fig. 2, in which the first deactivation port 24.1 is connected to the third deactivation port 24.3. The third deactivation port 24.3 is connected to a vent 7, so that the breakaway safety valve control port 22.1 is also vented. The breakaway safety valve 22 is therefore in the position shown in Fig.2, in which a supply of supply pressure pV from the supply connection 31 via the breakaway safety valve 22 to the trailer supply connection 32 is possible. If, however, the deactivation valve unit 24 is switched by providing the deactivation switching signal SD, the first deactivation connection 24.1 is connected to the second deactivation connection 24.2, which in turn is connected to the supply connection 31. In this way, a breakaway control pressure pSA is controlled at the breakaway safety valve control connection 22.1, which ensures that the breakaway safety valve 22 switches to the switching position not shown in Fig. 2, so that the supply connection 31 and the trailer supply connection 32 are separated or only connected via the throttle 22.2. In this way, a subsequent supply of supply pressure from the third compressed air supply 122 to the trailer 204 can be prevented.

[0059] As can be seen from Fig. 2, when the breakaway safety valve 22 is switched, the supply to the relay valve 36 is simultaneously prevented or only possible via the throttle 22.2, so that the trailer brake pressure pBA for actuating the service brake actuators 10a - 10f of the trailer 204 cannot be controlled. Fig. 3 shows a variant of the circuit from Fig. 2, in which the control of the trailer brake pressure pBA is possible even when the breakaway safety valve 22 has switched. For this purpose, the relay valve 36 is connected to the supply connection 31 of the trailer control valve 30 in such a way that the breakaway safety valve 22 is not connected between the two, but the supply to the relay valve 36 is independent of the switching of the breakaway safety valve 22.

[0060] The advantage that the trailer brake pressure pBA can be controlled even when the breakaway safety valve 22 is in the switching position not shown in Fig. 3 lies in particular in the fact that the service brake actuators 10a - 10f of the trailer 204 can be actuated even when the supply of compressed air to the trailer reservoir 8 is prevented. This makes it possible to consume compressed air in the trailer 204 and to allow the trailer reservoir 8 to drain without further filling it from the towing vehicle.

[0061] Fig. 4 shows a variant of the vehicle combination 200 in a second exemplary embodiment. Identical and similar elements are provided with the same reference numerals and, in this respect, reference is made in full to the above description. The differences from the first exemplary embodiment (Fig. 1) are particularly highlighted below. In the exemplary embodiment shown in Fig. 4, the valve arrangement 20 again comprises a deactivation valve unit 24, which is pneumatically connected between the trailer supply connection 32 and the trailer supply line 4. In particular, the deactivation valve unit 24 can be connected between the trailer supply connection 32 and a red coupling head (not shown here), to which the trailer supply line 4 can then be coupled.

[0062] The deactivation valve unit 24 here comprises a first 2 / 2-way valve 26 and a second 2 / 2-way valve 28, which are interconnected in such a way that the trailer supply connection 32 can be blocked and the trailer supply line 4 or the red coupling head can be vented. In another embodiment, the first and second 2 / 2-way valves 26, 28 can also be replaced by a single 3 / 2-way valve.

[0063] In contrast to the first exemplary embodiment (Fig. 1), the deactivation valve unit 24 is controlled immediately and directly by the unit for autonomous driving 40, which provides the deactivation switching signal SD to it. Alternatively, the deactivation valve unit 24 can also be switched by the primary brake control unit 100 and be directly wired to it. Furthermore, it is conceivable that the unit for autonomous driving 40 provides the request SPB to the primary brake control unit 100, which then controls the deactivation switching signal SD to the deactivation valve unit 24. Further variants are conceivable; in particular, it is conceivable that each control unit that has its own intelligence, such as the rear axle modulator 110, the parking brake module 120, or an electronic air preparation unit (not shown).

[0064] Fig. 5 shows a third embodiment of the vehicle train, and again, identical and similar elements are designated by the same reference numerals as in Figs. 1 and 4. Again, the differences are particularly emphasized below, while similarities will not be discussed further.

[0065] In addition to the deactivation valve unit 24 shown in Fig. 1, the exemplary embodiment according to Fig. 5 is provided with a trailer venting valve 29, which can directly vent the trailer storage tank 8. The trailer storage tank 8 can be vented directly into the environment via the trailer venting valve 29 in order to quickly reduce the trailer storage pressure pVA. For this purpose, the trailer venting valve 29 can comprise one or more switching valves, such as a 3 / 2-way valve or two 2 / 2-way valves, which in the exemplary embodiment shown here can be controlled by a trailer switching signal SA. The trailer switching signal SA is provided via the trailer BUS 124 by the towing vehicle 202, in particular by the towing vehicle braking system 1. Specifically, the trailer switching signal SA is output by the primary brake control unit 100, which controls it in response to receiving the request SPB for safely braking the trailer 204.

[0066] Reference symbol (part of the description):

[0067] 1 motor vehicle braking system

[0068] 2 trailer braking system

[0069] 3 trailer brake circuit

[0070] 4 trailer supply line

[0071] 6 trailer control line

[0072] 8 trailer storage containers

[0073] 20 Valve arrangement

[0074] 22 Safety valve

[0075] 22.1 Safety valve control connection

[0076] 22.2 Throttle

[0077] 24 Deactivation valve unit

[0078] 24.1 first deactivation connection

[0079] 24.2 second deactivation connection

[0080] 24.3 third deactivation connection

[0081] 26 first 2 / 2-way valve

[0082] 28 second 2 / 2-way valve

[0083] 29 Trailer vent valve

[0084] 30 Trailer control valve

[0085] 31 Supply connection

[0086] 32 Trailer supply connection

[0087] 34 Trailer brake pressure connection

[0088] 35 pilot control unit

[0089] 36 Relay valve

[0090] 40 units for autonomous driving

[0091] 100 primary brake control unit

[0092] 102 vehicle BUS

[0093] 104 Front axle brake circuit

[0094] 106 Rear axle brake circuit

[0095] 108 first compressed air supply

[0096] 110 Rear axle modulator

[0097] 112a, 112b first and second rear axle brake actuators 114 second compressed air supply

[0098] 116 front axle modulator

[0099] 118a, 118b first and second front axle brake actuators

[0100] 120 Parking brake module

[0101] 121 Parking brake system

[0102] 122 third compressed air supply

[0103] 123 internal BUS

[0104] 124 trailer BUS

[0105] 126 Protection valve

[0106] 128 Park release safety valve

[0107] 130 trailer control unit

[0108] 132 Trailer parking brake module

[0109] 200 vehicle combinations

[0110] 202 motor vehicles

[0111] 204 Trailer pBHA Rear axle brake pressure pBVA Front axle brake pressure pV Reservoir pressure pVA Trailer reservoir pressure pSA Breakaway control pressure

[0112] SA trailer switching signal

[0113] SBA brake request signal

[0114] SBT trailer brake signals

[0115] SD deactivation switching signal

[0116] SVA front axle brake signal

[0117] SHA rear axle brake signal

Claims

Patent claims:

1. Method for safely braking a trailer (204) of a vehicle combination (200) with a motor vehicle (202) and the trailer (204), wherein the motor vehicle (202) has an electronically controlled pneumatic motor vehicle braking system (1) and the trailer (204) has a pneumatic trailer braking system (2), wherein the motor vehicle braking system (1) and the trailer braking system (2) are connected by at least one trailer control line (6) and one trailer supply line (4), and the trailer braking system (2) has at least one trailer brake circuit (3) with a trailer reservoir (8) for providing a trailer reservoir pressure (pVA) for the trailer brake circuit (3), service brake actuators (10a-1 Of) and spring brake actuators (12a-12d), wherein in response to a request (SPB) for safely braking the trailer (204) the motor vehicle (202) lowers the Trailer reservoir pressure (pVA) in the trailer brake circuit (3) causes,so that the spring-loaded actuators (12a-12d) of the trailer (204) engage and brake the trailer (204) safely.

2. Method according to claim 1, comprising the step: preventing pressure control via the trailer supply line (4) to prevent the trailer reservoir (8) from filling up.

3. Method according to claim 2, wherein the trailer supply line (4) is disconnected to prevent the trailer reservoir (8) from being filled.

4. Method according to claim 2 or 3, wherein the motor vehicle braking system (1 ) deactivates a compressed air supply via the trailer supply line (4).

5. Method according to claim 2, 3 or 4, wherein the motor vehicle braking system (1) causes at least one valve arrangement (20) to switch for locking, venting and / or throttling the trailer supply line (4).

6. Method according to claim 5, wherein the valve arrangement (20) comprises a rupture safety valve (22) of the motor vehicle braking system (1 ).

7. Method according to claim 6, wherein the rupture safety valve (22) is pneumatically switchable and the motor vehicle braking system (1) controls a rupture control pressure (pSA) at the rupture safety valve (22) such that it switches and prevents the pressure control via the trailer supply line (4).

8. Method according to one of claims 5 to 7, wherein the valve arrangement (20) comprises an electromagnetic deactivation valve unit (24) which can be controlled by the motor vehicle (202).

9. Method according to claim 8, wherein the electromagnetic deactivation valve unit (24) is pneumatically connected upstream and / or downstream of a trailer control valve (30) of the motor vehicle braking system (1).

10. Method according to any one of claims 5 to 9, wherein the valve arrangement (20) comprises an electromagnetic trailer venting valve (29) in the trailer brake system (2) which can be controlled by the motor vehicle (202).

11. Method according to one of the preceding claims, wherein lowering the trailer supply pressure (pVA) comprises actuating the service brake actuators (10-1 Of) of the trailer braking system (2).

12. Method according to claim 12, wherein the actuation of the service brake actuators (1 Oa-1 Of) is pulsed, namely by mutually venting and venting the service brake actuators (1 Oa-1 Of).

13. Method according to one of the preceding claims, wherein lowering the trailer supply pressure (pVA) comprises actuating a trailer parking brake (132).

14. Method according to one of the preceding claims, wherein lowering the trailer supply pressure (pVA) is achieved by actuating an alternative air consumer in the trailer (204), preferably a level control (14) and / or lift axle (16).

15. Method according to any of the preceding claims, wherein the requirement (SPB) for safe braking is provided by a service brake system of the motor vehicle braking system (1), a parking brake system (121) of the motor vehicle braking system, an electronic air preparation unit of the motor vehicle braking system and / or an autonomous driving unit (40) of the motor vehicle (202).

16. Method according to one of the preceding claims, comprising the step: driving the motor vehicle (202) towards the safely braked trailer (204) to test the braking effect.

17. Electronically controlled pneumatic motor vehicle braking system (1) for a motor vehicle (202) of a vehicle combination (200), comprising a service brake system with a trailer control valve (30) having a trailer supply connection (32) for connecting a trailer supply line (4) and a trailer brake pressure connection (34) for connecting a trailer control line (6) and at least one motor vehicle-side trailer brake circuit for supplying the trailer control valve (30) with supply pressure (pV), wherein the A trailer control valve (30) at the trailer supply port (32) provides a trailer supply pressure (pVA); and a primary brake control unit (100) for controlling the service brake system, wherein the primary brake control unit (100) is connected to an autonomous driving unit (40) and receives brake request signals (SBA) from it, wherein the motor vehicle brake system (1) is configured to reduce the trailer supply pressure (pVA) in response to a safe braking request (SPB) from a trailer (204) connected to the motor vehicle (202), so that spring brake actuators (12a-12f) of the trailer (204) engage and safely brake the trailer (204).

18. Electronically controllable pneumatic motor vehicle braking system according to claim 17, wherein the motor vehicle braking system (1 ) comprises at least one valve arrangement (20) for locking the trailer supply connection (32).

19. Electronically controllable pneumatic motor vehicle braking system according to claim 18, wherein the valve arrangement (20) comprises a rupture safety valve (22).

20. Electronically controllable pneumatic motor vehicle braking system according to claim 19, wherein the stall safety valve (22) is pneumatically switchable and the motor vehicle braking system (1) has an electromagnetic release valve unit (24) for controlling a stall control pressure (pSA) at the stall safety valve (22) such that it switches and prevents pressure control via the trailer supply line (32).

21. Electronically controllable pneumatic motor vehicle braking system according to claim 19 or 20, wherein the release valve unit (24) is integrated into or arranged adjacent to the trailer control valve (30).

22. Electronically controllable pneumatic motor vehicle braking system according to one of claims 18 to 21, wherein the valve arrangement (20) comprises an electromagnetic deactivation valve unit (24) which can be controlled by the motor vehicle braking system (1), preferably the primary brake control unit (100).

23. Electronically controllable pneumatic motor vehicle braking system according to claim 22, wherein the electromagnetic deactivation valve unit (24) is pneumatically connected upstream and / or downstream of the trailer control valve (30).

24. Electronically controllable pneumatic motor vehicle braking system according to one of the preceding claims 17 to 22, wherein a trailer brake pressure (pBA) is controlled at the trailer brake pressure connection (34) of the trailer control valve (30) to reduce the trailer supply pressure (pVA).

25. Motor vehicle (202), in particular commercial vehicle, with an electronically controlled pneumatic motor vehicle braking system (1 ) according to one of claims 17 to 24 and a unit for autonomous driving (40).

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