Trailer and trailer control system

Abstract

A method of controlling brake pressure in a trailer brake system includes a trailer brake module for controlling braking force on one or more wheels on a trailer. The trailer brake module receives data inputs from sensors on the trailer and control pressure from the tractor in the control line. The brake system includes a second ECU configured to receive sensor inputs from sensors on the trailer, in communication with the trailer brake module and the towing vehicle. If the second ECU determines that the control pressure should be increased or decreased, the second ECU sends a request to the tractor to increase or decrease the control pressure accordingly.

Description

Technical Field

[0001] The present invention relates to a trailer and a trailer control system, in particular to a method for controlling brake pressure in a trailer. Background Art

[0002] Electronic brake systems for commercial vehicle trailers and other related applications are becoming increasingly complex with the introduction of additional features. This is also a highly competitive and cost-conscious market. Trailers do not usually have any autonomous power source, but rely on the towing vehicle for power. Trailers are equipped with autonomous braking systems with an independently operable trailer brake control unit. The trailer electronic brake control unit enables the trailer to have stability control, which greatly enhances the safety of the trailer.

[0003] The standard connection between the truck and trailer for braking and running devices is governed by ISO7638 for both 12V and 24V systems. The standard ISO 7638 connector is a 7-pin connector where pin 1 provides power to the trailer brake control valve; pin 2 provides power to the control electronics, pins 3 and 4 are grounds for these pins respectively; pin 5 is used for fault indication, and pins 6 and 7 are used for CAN communication.

[0004] Optionally, a backup electrical connection is provided for the brake light power available on the ISO1185 connector. Light control signals for the trailer are provided on the ISO1185 connector and the ISO3731 connector. ISO12098 defines a 15-way connector that is intended to replace the ISO1185 connector and the ISO3731 connector. The standard ISO12098 connector is a 15-pin connector, where pin 7 provides power to the brake lights and is also used as a backup power supply for the brake system; pin 9 provides optional power and pin 4 is the ground for these pins; pins 14 and 15 are used for CAN communication with a separate ground on pin 13. ISO12098 is not used for brake data or running gear signals, but is used for all other signals, including but not limited to obstacle detection.

[0005] Additional functionality is usually introduced by including the functionality as an auxiliary function in the trailer EBS. GB2395241 discloses an electronic control unit ECU having non-volatile storage memory means for storing vehicle-specific brake-related control parameters and programmable storage means carrying operating data for one or more auxiliary functions of the vehicle. The input and output variables and the control algorithm can then be checked against a predetermined list to protect the brake function from error modes.

[0006] It is also possible to provide an additional trailer electronic control unit co-located with the trailer EBS unit to provide additional intelligence in the trailer brake system in addition to the main trailer EBS control unit. This approach only results in additional cost due to the additional control unit and also increases the cost and difficulty of installation due to the need for additional wiring. This approach has not been commercially successful. Although the additional functions are not purely related to braking behavior, but include, for example, communications, these functions are still referred to as part of the braking system.

[0007] As trailers become more complex and their cost increases, trailer usability will become even more important to operators. This means that safety levels need to be improved compared to existing vehicles, while ensuring the availability and performance of key functions and reducing error rates.

[0008] Technical problems with trailers can be broadly categorized as: pneumatic problems, such as a supply or control line failure, a reservoir rupture or a pneumatic component failure; or alternatively electrical problems, such as a power failure or ECU failure in the trailer.

[0009] In an automated driving use case, any single failure could force the vehicle combination to: come to an immediate and uncontrolled stop (potentially resulting in an accident); severely decelerate and / or stop on a highway; experience a loss of legally required braking functions (ABS, RSP) and a potentially hazardous vehicle situation when emergency braking is required or braking under non-optimal conditions; or ultimately continue driving with an unknown vehicle state and unknown vehicle reactions. Summary of the invention

[0010] The present invention therefore seeks to provide an improved vehicle braking system performance, particularly in the event of an electrical fault.

[0011] According to the present invention, there is provided a method of controlling brake pressure in a trailer brake system, the brake system comprising a trailer brake module, the trailer brake module controlling a brake device capable of generating a braking force on one or more wheels on the trailer, the trailer brake module being adapted to receive data input from a sensor on the trailer and a control pressure in a control line from a tractor, wherein the brake system comprises a second ECU configured to be capable of receiving sensor input from a sensor on the trailer and configured to be capable of communicating with the trailer brake module and with the tractor, wherein if the second ECU determines that the control pressure should be increased or decreased, the second ECU sends a request to the tractor to increase or decrease the control pressure accordingly.

[0012] Preferred aspects of the invention can be found in the dependent claims.

[0013] Therefore, the present invention solves the problem of providing suitable brake system performance in the event of an electrical fault. Generally speaking, in the event of an electrical fault, the mechanical and pneumatic functions of the brake system remain intact.

[0014] The basic principle of the invention is to use the ECU and in addition the trailer brake module and various valves together to control the control pressure (p4) of the brake system, thereby utilizing its relay function, realizing smaller and cheaper valves and / or directly realizing the service brake pressures p21 and p22. In this way, electronically controlled braking, load-dependent braking and stability functions can be provided in the event of an electrical fault.

[0015] Advantageously, in the event of a fault, the main ECU can regulate the input pressure (p4) or the output pressure (p21 / p22) of the trailer brake control module. It can do this directly via a valve located in the tractor, or indirectly via the brake control system in the tractor.

[0016] With the present invention, the electrical faults described above can be handled as the vehicle still has fully graded braking and stability functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings, in which:

[0018] Figure 1 The trailer electronic brake system is shown;

[0019] Figure 2 Schematically illustrates the electrical connections in one embodiment of the present invention;

[0020] Figure 3 shows a sequence diagram outlining a simplified brake activation sequence according to the present invention;

[0021] Figure 4 The arrangement structure of the first embodiment of the brake system of the present invention is shown;

[0022] Figure 5 Shows Figure 4 Another embodiment of;

[0023] Figure 6 Another embodiment with a relay valve is shown. DETAILED DESCRIPTION

[0024] Figure 1A known trailer electronic brake system is shown, in which a utility vehicle trailer has a steerable front axle with front wheels 1, 2 and a rear axle with rear wheels 3, 4. Rotary wheel speed sensors 5-8 are respectively assigned to the front wheels 1, 2 and rear wheels 3, 4 and are connected via electrical wires 9-12 to an electro-pneumatic brake pressure control module 13 (trailer brake module or EBS module) which is primarily assigned to the rear axle brakes. The front wheels 1, 2 and rear wheels 3, 4 are respectively assigned a brake 14-17 which can be applied by brake cylinders 18, 19 of the front axle or spring-loaded brake cylinders 20, 21 of the rear axle.

[0025] The brake system of the trailer can be connected to the brake system of the tractor or another trailer through three connections, specifically a pneumatic supply line connection 22, a pneumatic control line connection 23 and an electrical control connection 24. The electrical control line 24 provides an ISO 11992 CAN data connection.

[0026] The supply line connection 22 is connected to an air brake reservoir 27 via a return valve 25 and a parking valve 26. Pneumatic lines 28, 30 lead from the air brake reservoir 27 to the supply input of the pressure control module 13 and to an ABS valve 32, respectively. In addition, a pneumatic line 29 branches off from the parking valve 26 to the pressure control module 13. A pneumatic line 30 extends between the parking valve 26 and the air brake reservoir 27.

[0027] The ABS valve 32 is assigned to both brake cylinders 18, 19 of the front axle and is connected to the brake cylinder 18 via a pneumatic line 33 and to the brake cylinder 19 via a pneumatic line 34. The ABS valve 32 has two electrical control inputs, which are connected to the pressure control module 13 via "one" electrical line 35, which is only schematically shown here.

[0028] Furthermore, the ABS valve 32 has a pneumatic control input 36, which is connected to the pneumatic control connection 23 via a return valve 37. The pneumatic control input 36 is also connected to a pneumatic control input of the pressure control module 13 via a pneumatic control line 38. The pressure control module 13 has an integrated pressure sensor (not shown) which measures the pressure in the pneumatic control line 38, i.e. the control pressure present at the pneumatic control input 36 of the ABS valve, which is identical to the maximum pressure that can be controlled into the brake cylinders 18, 19.

[0029] The pressure control module 13 has pneumatic outputs 39 - 42 which are connected to the spring brake cylinder 20 or 21 via assigned pneumatic lines.

[0030] Furthermore, pneumatic axle load sensors or air bellows 43, 44 are provided at the rear axle and allow the axle loads, in particular the dynamic axle loads during braking and starting, to be determined. The axle load sensors or air bellows 43, 44 are connected to the pressure control module 13 via pneumatic lines. Correspondingly, the pressure in the airbags 45, 46 provided at the front axle can be detected by sensors 47, the airbags 45, 46 being electrically controlled here. However, the axle load sensors 45, 46 are not absolutely necessary.

[0031] To provide stability control, a lateral acceleration sensor 50 is provided, which may also be integrated with the yaw sensor, and the output of the lateral acceleration sensor is fed to the pressure control module / ECU 13. Typically, the lateral acceleration sensor 50 is integrated into the pressure control module / ECU 13. In the event of lateral acceleration on the trailer being detected, the pressure control module can provide increased braking force at the front and / or rear axle. When the lateral acceleration sensor 50 detects lateral acceleration on the trailer to which it is mounted, the sensor generates a signal which sets the stability control to active.

[0032] Relative to Figure 1 In the described embodiment, the ABS valve 32 can be replaced by an electropneumatic valve, wherein the electric control circuit 35 is composed of a communication device (preferably CAN) and a power supply.

[0033] The pressure control module 13 receives data from wheel speed sensors on the trailer and also receives signals indicating whether the brake pedal in the vehicle cab is depressed, and the brake pressure demand. In addition to the ISO 7638 electrical connections shown, the trailer may also have an ISO 1185 electrical connection for powering indicator lights and trailer brake lights.

[0034] In another embodiment of the braking system, the system is provided with an ISO 7638 connection and an optional ISO 1185 (or alternatively ISO 12098) connection to an electronic control module. The electronic control module may be located at the trailer head plate and receives brake and travel gear control signals from the truck-trailer CAN bus. The trailer electronic module is also connected to a first trailer brake CAN bus to which the trailer brake module (equivalent to the EBS module 13) is connected. The trailer brake module is also connected to wheel speed sensors and auxiliary I / O.

[0035] The electronic control module is also connected to a second trailer brake CAN bus to which the trailer electronic pressure module is connected (equivalent to the single channel brake module 32). The trailer electronic pressure module 306 receives inputs from the wheel sensors and auxiliary I / O inputs.

[0036] Figure 2An alternative embodiment of a braking system in a trailer 400 is shown. The front end of the trailer, represented by a kingpin 401, is provided with a separate ISO 12098 connector 402 and an ISO 7638 connector 403. The ISO 7638 connector 403 is provided with an electronic control unit 404. The electronic control unit 404 is connected to the trailer EBS 406 via electrical and CAN bus connections 405 and to a splitter 408 via electrical connections 407, which is also connected to the ISO 12098 connector 402 and provides a connection to the trailer lighting system. The trailer lighting system is symmetrically arranged on the trailer and includes a tail light group 409 (the group includes brake lights, reverse lights and night lights), top rear marker lights 410 and bottom rear marker lights 411, four side marker lights 412 and front marker lights 413.

[0037] Figure 3 A sequence diagram outlining a simplified brake activation sequence for three situations is shown.

[0038] The first case corresponds to normal operation, where the towed trailer receives an electrical signal from the tractor describing the requested brake pressure. Using the load status, the towed vehicle corrects the requested brake pressure upward or downward to minimize the coupling force and improve the combined stability. The towed vehicle brake control system then implements the brake pressure. In parallel, the tractor sends a pneumatic control signal representing the brake force. If the electrical brake signal is received and implemented, the towed vehicle brake system ignores the pneumatic signal.

[0039] The second case corresponds to pneumatic backup: in this case, the electrical communication line between the towed vehicle and the towing vehicle is interrupted. The towed vehicle performs brake activation according to the pneumatic input signal.

[0040] Figure 4 The connection according to the invention is schematically shown for a third case, in which the towed vehicle requests a brake pressure via an ISO11992 CAN bus connection or equivalent. In this case, the control pressure requested by the towed vehicle can be higher or lower than the control pressure currently supplied by the towing vehicle. The towing vehicle then executes the request via the towing vehicle brake control and supplies a corrected control pressure. The pressure applied to the towed vehicle is regulated by the towing vehicle. From this point on, the control algorithm follows the second case.

[0041] There can also be an intermediate step between case 1 and case 2, where the towed vehicle brake system has power (e.g., via brake lights) but no communication. In this case, the pneumatic control signal can be corrected according to the load state before it is executed as a brake actuation.

[0042] In the simplest case, the present invention can be used, for example, Figure 1However, in this case, only some faults (e.g., one or more pressure control valves are faulty) can be covered, since the communication function of the trailer brake system, and therefore its power supply, is also necessary for other faults.

[0043] Preferably, a second ECU is provided in the towed vehicle / trailer which can communicate with the towing vehicle. Ideally, it should have a second communication channel and a second power supply, as this maximizes the number of faults that can be resolved.

[0044] Figure 4 The arrangement shown in is a compromise embodiment that does not focus on resolving the maximum number of potential faults. This arrangement can resolve all faults within the trailer brake control module, but cannot resolve errors related to the towing vehicle or interface (such as electrical supply failure or connector failure in the towing vehicle).

[0045] Figure 5 Another embodiment of a braking system is shown, in which the control pressure p4 can be increased by a request from the trailer brake control module to the towing vehicle and reduced by a pressure control valve (PCV). The PCV is a combination of two 2 / 2 valves that can adjust the control pressure between ambient pressure and input pressure. Figure 5 In the system, the pressure control valve is placed in the control line between the tractor and the trailer / towed vehicle. The PCV can be electrically actuated by an electrical connection to a second ECU, which is also connected to the Figure 4 The addition of a PCV allows the towed vehicle to reduce pressure, e.g. for ABS control, without the involvement of the towing vehicle. In this way, the pressure reduction can be achieved more quickly, e.g. to enhance ABS performance. The second ECU in use would normally request a constant high pressure from the towing vehicle, while the PCV would reduce the input pressure to the trailer brake module in passive mode.

[0046] Figure 6Another alternative embodiment is shown, in which pressure is requested from the towing vehicle. In this embodiment, the brake system is provided with two relay valves, which are shown here as ABS relay valves. The control pressure p4 can be increased by request to the towing vehicle, and the brake supply pressure p21 / p22 can be reduced by the relay valve. The function of each relay valve is similar to that of the PCV, which can reduce and maintain pressure. Each valve is pneumatically connected to the main power supply and receives a pneumatic control signal from the trailer brake control module. These valves are electrically controlled by the second ECU. The output of the relay valve supplies the brake pressure to the wheel. In addition to the pressure control valve, it also integrates a relay part, so that a larger air mass can be adjusted. This enables the towed vehicle to control the pressure on multiple channels (such as left / right side) individually. Since the control is now located on the output of the trailer brake control module, a larger air mass needs to be controlled, which means using a relay component instead of a simple pressure control valve.

[0047] exist Figure 6 In the embodiment of the invention, a simple valve can be used instead of the relay valve of a single-axle trailer. It is also possible to combine the valves on the output side of the trailer brake module shown into a single electromechanical module, which can have an integrated pressure control. Based on an electronic control signal, it can precisely control its output pressure and process the wheel speed sensor signal. The single-channel electro-pneumatic module has a pneumatic connection to the main supply pressure line and can control the pressure in the control line to the trailer brake control module. This module is electrically controlled by a second ECU.

[0048] Currently, the valid standards are ISO 1185:2003, ISO 7638-1 / 2:2018, ISO 11992:2021 and ISO12098:2020 as well as SAE 560:2020.

Claims

1. A method of controlling brake pressure in a trailer brake system, the brake system comprising a trailer brake module for controlling the braking force on one or more wheels on the trailer, the trailer brake module being adapted to receive data input from a sensor on the trailer and control pressure in a control line from a towing vehicle, wherein the brake system comprises a second ECU configured to be able to receive sensor input from a sensor on the trailer and configured to be able to communicate with the trailer brake module and with the towing vehicle, wherein: If the second ECU determines that the control pressure should be increased or decreased, the second ECU sends a request to the towing vehicle to increase or decrease the control pressure accordingly.

2. The method of controlling brake pressure in a trailer brake system according to claim 1, wherein: The second ECU is provided with a communication channel to the towing vehicle which is independent of the communication channel from the trailer brake module to the towing vehicle.

3. The method for controlling brake pressure in a trailer brake system according to claim 1 or 2, wherein: The second ECU is provided with a power supply which is independent of the power supply for the trailer brake module.

4. A method for controlling brake pressure in a trailer according to any one of claims 1 to 3, wherein: The control circuit is provided with a pressure control valve controllable by the second ECU, the pressure control valve being adapted to reduce the control pressure towards the trailer brake module.

5. A method for controlling brake pressure in a trailer according to any one of claims 1 to 3, wherein: The brake system is provided with a first valve and a second valve, each valve being associated with a brake channel leading to a respective wheel of the trailer, wherein each valve is pneumatically controlled by the trailer brake module and electrically controlled by the second ECU, and each valve is adapted to reduce the pressure supplied to the wheel.

6. The method of controlling brake pressure in a trailer according to claim 5, wherein: The first valve and the second valve are relay valves.

7. A method of controlling brake pressure in a trailer according to claim 5 or 6, wherein: A pressure sensor is provided to measure the pressure output of the relay valve to the wheels, thereby providing an electrical signal to the second ECU.

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