Motor vehicle braking system for vehicle combinations

Abstract

The invention relates to a motor vehicle braking system comprising a first brake unit with at least one first brake actuator configured to provide a braking torque to at least one first wheel brake of a towing vehicle and a second brake unit with at least one second brake actuator configured to provide a braking torque to at least one second wheel brake of a trailer which is pulled by the towing vehicle.To achieve the best possible deceleration of the entire vehicle combination, the first brake unit comprises a master control unit and the second brake unit a trailer control unit, which is in a communication link with the master control unit, wherein the master control unit is configured to detect a brake pedal actuation value during normal braking and, based on the brake pedal actuation value, to actuate the first brake actuator, provide a braking torque at a first wheel brake, and, based on the brake pedal actuation value, to determine a wheel-specific and / or axle-specific target deceleration and / or target braking torque and transmit it via the communication link to the trailer control unit, wherein the trailer control unit is configured to actuate at least one second brake actuator, based on the received target deceleration, and provide a braking torque at a second wheel brake.

Description

[0001] The invention relates to a motor vehicle braking system for trailers comprising a first braking unit with at least one first brake actuator configured to provide a braking torque to at least one first wheel brake of a towing vehicle and a second braking unit with at least one second brake actuator configured to provide a braking torque to at least one second wheel brake of a trailer which is pulled by the towing vehicle.

[0002] Braking systems for motor vehicle trailers are typically designed as passive braking systems. For larger trailer loads, trailers are equipped with a so-called overrun brake. The trailer pushes against the towing vehicle, which activates a brake via a corresponding linkage, thus slowing the trailer. Such trailers are typically also equipped with a parking brake, which can be mechanically activated via a lever and thus secures the trailer against rolling away. The trailer only brakes when it hits the towing vehicle. The braking effect is therefore delayed and can only be controlled to a limited extent via the linkage, which can result in dangerous situations in addition to a loss of comfort.

[0003] It is therefore an object of the present invention to provide a motor vehicle braking system which avoids the above disadvantages.

[0004] The object is achieved in that the first brake unit comprises a master control device and the second brake unit comprises a trailer control device which is in a communication connection with the master control device, wherein the master control device is configured to detect a brake pedal actuation variable during normal braking and to control the first brake actuator based on the brake pedal actuation variable, to provide a braking torque at a first wheel brake and to determine a wheel-specific and / or axle-specific target deceleration and / or a target braking torque based on the brake pedal actuation variable and to transmit it to the trailer control device via the communication connection.The trailer control unit receives the corresponding data and is configured to control the at least one second brake actuator based on the received target deceleration and / or the target braking torque and to provide braking torque to a second wheel brake of the trailer. The brake units, or rather their control units, are thus connected to each other in a direct master-slave architecture.

[0005] The conversion of brake pedal actuation into a value for converting vehicle deceleration is referred to as driver request detection and is generated from recorded sensor signals. For this purpose, two different sensors, such as a displacement sensor and a pressure sensor, can be recorded and stored as a characteristic curve. Based on the sensor information and the stored application, a deceleration request, for example, is generated.

[0006] This deceleration request can be transmitted to the actuator of the towing vehicle braking system on the one hand, and on the other hand the request is transmitted to the external actuator of the trailer when the trailer is detected.

[0007] The deceleration request can also be split between the towing vehicle and the trailer. The split can be equal depending on the situation, e.g., in a partially braked state. In the case of greater deceleration requests, the request to the trailer can also be limited to avoid over-braking. In special cases, e.g., in the case of brake fade or a defect or failure of the towing vehicle's braking system, a greater demand can be placed on the trailer's braking system. It is also possible to directly determine two separate deceleration requests based on the brake pedal actuation value.

[0008] In a preferred embodiment of the invention, the communication connection is a bus system, in particular a CAN bus or Flexray bus. This can be routed via a corresponding trailer coupling.

[0009] In a further preferred embodiment of the invention, the first and / or the second brake unit is designed hydraulically and comprises a hydraulic wheel brake with an associated pressure supply device as a brake actuator.

[0010] In a further preferred embodiment of the invention, the first and / or second brake unit is electromechanical. In particular, the first brake unit can be hydraulic and the second brake unit electromechanical.

[0011] In a further preferred embodiment of the invention, the second brake unit with the second brake actuator and the second wheel brake is arranged in the trailer.

[0012] In a further preferred embodiment of the invention, a user interface is provided, which is arranged in the towing vehicle, with which a driver can adjust the trailer braking force. Thus, the proportion of the trailer braking torque to the target torque can be determined.

[0013] In a further preferred embodiment of the invention, the master control device is configured to determine a wheel-specific and / or axle-specific target deceleration and / or target braking torque based on a braking request from an assistance system or a virtual driver and to transmit it to the trailer control device via the communication connection. The trailer control device is configured to control the at least one second brake actuator based on the received target deceleration and / or target braking torque and to provide a braking torque to at least one second wheel brake. Thus, both the towing vehicle and the trailer are braked in a controlled manner not only during driver-induced normal braking but also during automatic braking.

[0014] The object is also achieved by a towing vehicle brake unit having at least one first brake actuator configured to provide a braking torque to at least a first wheel brake of the towing vehicle, wherein a master control device is provided which is configured to detect a brake pedal actuation variable during normal braking and to control the first brake actuator based on the brake pedal actuation variable to provide a braking torque to the first wheel brake and to determine a wheel-specific and / or axle-specific target deceleration and / or target braking torque based on the brake pedal actuation variable and to transmit it to a trailer control device via an interface for a communication connection in order to instruct the trailer control device to control a second brake actuator based on the target deceleration and / or target braking torque to provide a braking torque to a second wheel brake of the trailer.

[0015] The object is also achieved by a trailer brake unit with at least one second brake actuator configured to provide a braking torque to at least one second wheel brake of a trailer which is towed by a towing vehicle, wherein a trailer control device is provided which has an interface for a communication connection with a master control device of a towing vehicle brake unit, wherein the trailer control device is configured to receive a wheel-specific and / or axle-specific target deceleration and / or target braking torque via the interface during normal braking and to control the at least one second brake actuator based on the received target deceleration and / or target braking torque to provide a braking torque to a second wheel brake.

[0016] The object is further achieved by a method for controlling a motor vehicle brake system, characterized in that a master control device of a towing vehicle detects a brake pedal actuation variable during normal braking and, based on the brake pedal actuation variable, controls a first brake actuator to provide a braking torque at a first wheel brake of the towing vehicle and, based on the brake pedal actuation variable, determines a wheel-specific and / or axle-specific target deceleration and / or target braking torque and transmits it to a trailer control device via a communication connection, wherein the trailer control device, based on the received target deceleration and / or target braking torque, controls at least one second brake actuator to provide a braking torque at a second wheel brake of the trailer.

[0017] Further features, advantages, and possible applications of the invention will become apparent from the following description of exemplary embodiments and the drawings. All described and / or illustrated features, both individually and in any combination, are part of the subject matter of the invention, regardless of their summary in the claims or their references. Fig. 1 shows schematically a motor vehicle braking system according to the invention of a first embodiment, Fig. 2 schematically shows a motor vehicle braking system according to the invention of a second embodiment; Fig. 3 shows a flow chart of the method according to the invention, Fig. 4 shows a flow chart of the method according to the invention;

[0018] In Fig. Figure 1 shows an overall braking system for a towing vehicle and a trailer. This comprises a primary braking system 2 having a pedal actuation unit (PAU) 3, a control unit 4, and an actuator 5, which in turn acts on the individual wheel brakes 6 of the towing vehicle. A secondary braking system 7 also comprises a control unit 8 and an actuator 9, which acts on wheel brakes 10 of the trailer.

[0019] The actuators 5, 9 can be designed as hydraulic or electromechanical variants. The same applies to the actuating device 3. The braking system shown has a highly modular design, so that the systems and components can be flexibly integrated into platforms. Various interfaces are provided for implementation in order to be able to control the different actuators 5, 9 and to adapt the braking behavior to specific vehicles and customer requirements. The trailer is equipped with its own brake-by-wire braking system 7, i.e. an active braking system, and is connected to the towing vehicle via a corresponding interface. The towing vehicle and trailer are connected to one another via a bus system 11, via which communication between the towing vehicle and trailer, or rather their control units 4, 8, takes place.

[0020] The brake control unit 4 of the towing vehicle includes a function for controlling external actuators, which, according to the invention, outputs an axle-specific or wheel-specific target braking torque or a target deceleration in order to achieve optimal deceleration behavior of the entire vehicle or the trailer combination, taking into account the current driving situation or operating strategy of the vehicle. The braking system 2 of the towing vehicle operates as a master and actively controls the braking requests of the trailer braking system 7, which acts as a slave. A normal braking function is implemented on the trailer braking system 7, which receives a deceleration request from the towing vehicle and builds up a corresponding braking torque.

[0021] If the driver 1 actuates the brake pedal 3, a brake pedal actuation value is determined on the towing vehicle in the control and regulation unit 4 of the braking system by detecting the driver's request, and from this a target braking torque is generated for the towing vehicle, which is implemented by the corresponding actuator 5 for the towing vehicle. So that the trailer brakes simultaneously and thus contributes to the overall deceleration of the vehicle combination, a target braking torque for the trailer is generated by the same control and regulation unit 4 and sent directly to the trailer's braking system 7. The control and regulation unit 8 of the trailer braking system receives the request and activates the trailer brake. This can, for example, have an actuator 9, which builds up hydraulic pressure and then transmits it to a corresponding wheel brake 10 of the trailer. Alternatively, electromechanical actuators can also be provided.

[0022] The vehicle detects the trailer connected to the towing vehicle. The trailer braking function remains inactive as long as no valid signals are received from the trailer braking system. The trailer braking function is only activated on the towing vehicle once the signals are received from the trailer and the trailer braking system is available. A braking torque is sent to the trailer's control and regulation unit 8 via the interface. Based on the request, deceleration is implemented via the trailer's braking system. In addition, an adaptive mode for the trailer brake is stored in the vehicle menu, which allows the intensity of the braking effect to be adjusted. This allows the driver to adapt the trailer's braking effect depending on the load condition, trailer weight, or personal preferences.

[0023] A second embodiment additionally features a virtual driver (VD) 12. Based on sensor data 13, such as environmental detection and vehicle conditions, the autonomous function generates a braking request. This can take the form of a deceleration request or an equivalent. This request is simply transmitted to the brake control unit 4 of the towing vehicle, which in turn generates a braking torque and sends a request signal to the trailer braking system. Thus, even with autonomous deceleration requests, trailer braking can be implemented.

[0024] The trailer is connected to the towing vehicle and is electrically connected. Thus, the trailer is connected to the vehicle via a BUS system. Fig. 3 and Fig.Figure 4 illustrates the interaction between the braking units using flowcharts. The trailer, or its control and regulation unit of the braking system (Trailer Brake System, TBS), transmits the status and availability of the braking system. The towing vehicle, or its control and regulation unit of the braking system (Primary Brake System, PBS), receives the signals from the TBS and activates the (trailer braking) function. This enables a braking torque, or a request to generate a corresponding braking torque, to be sent to the trailer braking system in the event of driver braking.

[0025] When the driver presses the brake pedal, a deceleration request is generated in the logic of the PBS ECU. If the trailer braking function is enabled, an additional request is sent to the TBS so that the trailer actively brakes. The TBS control unit receives this request and activates the actuator.

[0026] The trailer braking system monitors active braking, e.g., for over- or under-braking, and also monitors the braking system as a whole. As long as the TBS does not report an error, the trailer braking function remains active, and braking torque can be sent to the TBS when the driver brakes. If an error is detected that affects the availability and braking readiness of the TBS, the TBS's availability changes to "unavailable." The status is communicated to the PBS. If the TBS is unavailable, the PBS deactivates the trailer braking function. When the driver brakes, no further braking torque is sent to the TBS.

Claims

[1] Motor vehicle brake system comprising a first brake unit with at least one first brake actuator configured to provide a braking torque to at least one first wheel brake of a towing vehicle and a second brake unit with at least one second brake actuator configured to provide a braking torque to at least one second wheel brake of a trailer which is pulled by the towing vehicle, characterized byin that the first brake unit comprises a master control device and the second brake unit comprises a trailer control device which is in a communication connection with the master control device, wherein the master control device is configured to detect a brake pedal actuation variable during normal braking and to control the first brake actuator based on the brake pedal actuation variable to provide a braking torque at a first wheel brake and to determine a wheel-specific and / or axle-specific target deceleration and / or target braking torque based on the brake pedal actuation variable and to transmit it to the trailer control device via the communication connection, wherein the trailer control device is configured to control the at least one second brake actuator based on the received target deceleration to provide a braking torque at a second wheel brake. [2] Motor vehicle braking system according to claim 1, characterized by that the communication connection is a bus system, in particular a CAN bus or Flexray. [3] Motor vehicle braking system according to one of the preceding claims, characterized by that the first and / or the second brake unit is hydraulic and comprises a hydraulic wheel brake with an associated pressure supply device. [4] Motor vehicle braking system according to one of the preceding claims, characterized by that the first and / or the second brake actuator is electromechanical. [5] Motor vehicle braking system according to one of the preceding claims, characterized by that the second brake unit with the second brake actuator and the second wheel brake is arranged in the trailer. [6] Motor vehicle braking system according to one of the preceding claims, characterized by that a user interface is provided, which is arranged in the towing vehicle, with which a driver can adjust the trailer braking force. [7] Motor vehicle braking system according to one of the preceding claims, characterized by in that the master control device is configured to determine a wheel-specific and / or axle-specific target deceleration and / or target braking torque based on a braking request from an assistance system or a virtual driver and to transmit it to the trailer control device via the communication connection, wherein the trailer control device is configured to control the at least one second brake actuator based on the received target deceleration to provide a braking torque to at least one second wheel brake. [8] A towing vehicle brake unit comprising at least one first brake actuator configured to provide a braking torque to at least one first wheel brake of the towing vehicle, characterized bythat a master control device is provided which is configured to detect a brake pedal actuation variable during normal braking and to control the first brake actuator based on the brake pedal actuation variable to provide a braking torque at the first wheel brake and to determine a wheel-specific and / or axle-specific target deceleration and / or target braking torque based on the brake pedal actuation variable and to transmit it to a trailer control device via an interface for a communication connection in order to instruct the trailer control device to control a second brake actuator based on the target deceleration and / or target braking torque to provide a braking torque at a second wheel brake of the trailer. [9] Trailer brake unit with at least one second brake actuator configured to provide a braking torque to at least one second wheel brake of a trailer which is pulled by a towing vehicle, characterized by that a trailer control device is provided which has an interface for a communication connection with a master control device of a towing vehicle braking system, wherein the trailer control device is designed to receive a wheel-individual and / or axle-individual target deceleration and / or target braking torque via the interface during normal braking and to control the at least one second brake actuator based on the received target deceleration and / or target braking torque to provide a braking torque to a second wheel brake. [10] Method for controlling a motor vehicle braking system characterized bythat a master control device of a towing vehicle detects a brake pedal actuation variable during normal braking and, based on the brake pedal actuation variable, controls a first brake actuator to provide a braking torque at a first wheel brake of the towing vehicle and, based on the brake pedal actuation variable, determines a wheel-specific and / or axle-specific target deceleration and / or target braking torque and transmits it to a trailer control device via a communication connection, wherein the trailer control device, based on the received target deceleration, controls at least one second brake actuator to provide a braking torque at a second wheel brake of the trailer.

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