The invention relates to a trailer with an interface for connection to a towing vehicle, in particular, but not exclusively an interface between a heavy truck and trailer.

In order to operate in a commercially viable way, logistics operators need to be able to use their trailers in a very flexible way. One very important part of that flexibility is the possibility to pair a trailer with just about any towing vehicle in a fleet or an independent operator. The requirements associated with this flexibility are referred to as compatibility and interoperability within the industry and apply to coupling equipment, pneumatic and electrical connectors as well as communication protocols.

As the existing fleet is large and operators require interoperability, additional functionality has been implemented by the use of additional interfaces on the trailer. Such interface additions in Europe in the past have resulted in redundant set of standard connectors as a trailer typically requires four connectors under different standards ISO 12098:2020, ISO 7638-1/2:2018, ISO 1185:2003 and ISO 3731:2003 as well as 11446- 1/2:2012. The North American market has only a single powerline connector as the market favours interoperability and simplicity over additional features. An example of such a system can be found in US 11097702.

Generally, all electrical connections of an ECU such as the trailer brake control module that are mounted and used in a commercial vehicle need to be protected against contact to water to prevent corrosion. In addition, ongoing corrosion of pins might lead to water ingress into the ECU chamber. The current standard practice is to display a note in the product manual stating that if no connections on the connector are used a blanking plug must be installed to prevent the ingress of moisture to the ECU.

W02020130919 discloses an arrangement for preventing access to live parts in charging contact sockets of a hybrid or electrified vehicle having a plurality of such sockets each connectable to an external source of electric energy through a switch in an electric vehicle supply equipment station by inserting an electric plug in a socket for providing electric energy to batteries comprises blind plugs insertable into the sockets and the sockets are connected to each other and the batteries. A device is configured to sense presence of either an electric plug or a blind plug in each socket and the switch will be closed under the condition that either an electric plug or a blind plug is sensed by the device for all sockets and at least one of these plugs is an electric plug.

GB2574059 discloses a communication interface between a towing vehicle and a trailer, which are connected by a plurality of connectors compliant with standards selected from ISO12098, ISO7638, ISO1185, ISO3731, ISO11446. Digital signals are transmissible between the towing vehicle and the towed vehicle via a ISO11992-3 CAN bus. Pins on the towing vehicles are connected to pins on the towed vehicle by twisted pairs of wires adapted to carry a digital differential signal to provide higher speed data transmission between the vehicles.

In such a solution several connectors will not be used in every vehicle. Therefore only displaying a note in the product manual might not be sufficient since it cannot be ensured that every person dealing with such a trailer brake control module will have access to that documentation.

The present invention therefore seeks to provide a technical solution to the problem of ensuring that connection pins have protection against water ingress.

According to a first aspect of the invention there is provided a blind plug for a trailer connector being part of a trailer electronic braking system, which trailer connector has a plurality of pins, wherein the trailer electronic braking system comprises an ECU, which ECU can detect the presence or absence of an electrical connection, wherein the blind plug is provided with an electrical connector, which connector provides an electrical connection between first and second pins on the trailer connector when the blind plug is in the installed position.

According to a second aspect of the invention there is provided a method of determining whether a blind plug for a trailer connector of a trailer electronic braking system is correctly installed on a trailer, the trailer electronic braking system comprising a brake control module comprising an ECU, which brake control module has a first connector compatible with one of SAE 560:2020, ISO 1185:2003 ISO 7638-1/2:2018, ISO 11992:2021 and/or IS012098:2020 for connecting the brake control module to a towing vehicle, the brake control module having a second connector for connection to further components on the trailer, the connector having a plurality of pins, which ECU can detect the presence or absence of an electrical connection between two of said pins on the second connector, wherein a blind plug is provided, which blind plug provides the electrical connection in the installed position.

Preferably the blind plug is adapted to fit the trailer connector to reduce or substantially eliminate water ingress into the trailer connector.

The expectation is that Trailer OEM's will have an interest of implementing a robust procedure during vehicle production to ensure that all electric ports are closed and that the result of a respective status check during an End-of-Line test can be documented and archived for later reference. In the invention either a function can be installed and/or a blind plug with shorting link to indicate whether the connector is protected.

Advantageously the detection criteria and the system reaction can be recorded and therefore be available for later investigation. The advantage of using such an installation in which the ECU itself can detect whether the installation is complete or incomplete is that the vehicle manufacturer does not need to rely on the individual knowledge of a worker in the production line. Instead of attempting to visually detect any missing blind plug installation such a test could automatically run during the End- of-Line test. It would then be possible for the test result to be automatically documented in a test report which could be archived for later reference.

This enables the trailer ECU to detect if one or more electrical connectors is not fitted with such a blind plug. The ECU can then illuminate or flash the warning light via the CAN bus or Powerline if the trailer is connected to a truck or indicate an open connector through the diagnostics program for testing the ECU installation to a worker in the production phase of the trailer.

The introduction of such an automated blind plug detection should improve the overall reliability of the vehicle manufacturing process and also in operation. It also prevents damage to the electrical connectors should the blind plugs removed for servicing purposes and not refitted.

Exemplary embodiments of the invention will now be described in greater detail with reference to the drawings in which:

Fig. 1 shows a known trailer electronic braking system;

Fig. 2 shows schematically the electrical connection in a further trailer electronic braking system;

Fig. 3 shows a connector for a brake control module Fig. 4 shows schematically a blind plug connector.

Figure 1 shows a trailer electronic braking system in which the utility vehicle trailer has a steerable front axle with front wheels 1, 2 and a rear axle with rear wheels 3, 4. Rotational wheel speed sensors 5-8 are in each case assigned to the front wheels 1, 2 and the rear wheels 3, 4, and are connected by way of electric lines 9-12 with an electropneumatic brake pressure control module 13 (EBS module) which is primarily assigned to the rear axle brakes. One brake 14-17 is in each case assigned to the front wheels 1, 2 and the rear wheels 3, 4, which brake 14-17 can be applied by means of brake cylinders 18, 19 of the front axle or spring-loaded brake cylinders 20, 21 of the rear axle.

The braking system of the trailer vehicle can be connected by way of three connections, specifically a pneumatic supply line connection 22, a pneumatic control line connection 23 and an electric control connection 24, with the braking system of a tractor or a further trailer. The electric control line 24 provides the ISO 11992 CAN data connection.

The supply line connection 22 is connected by way of a return valve 25 and a parking valve 26 with an air brake reservoir 27. From the air brake reservoir 27, a pneumatic line 28, 30 leads to a supply input of the pressure control module 13 and ABS valve 32. In addition, a pneumatic line 29 branches off 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. The ABS valve 32 is assigned jointly to both brake cylinders 18, 19 of the front axle and is connected with the brake cylinder 18 by way of a pneumatic line 33 and with the brake cylinder 19 by way of a pneumatic line 34. The ABS valve 32 has two electric control inputs which are connected by way of "one" electric line 35 shown here only schematically with the pressure control module 13.

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

The pressure control module 13 has pneumatic outputs 39-42 which are connected by way of assigned pneumatic lines with the spring brake cylinders 20 or 21.

Furthermore, pneumatic axle load sensors or air bellows 43, 44 are provided at the rear axle and permit a determination of the axle load, particularly of the dynamic axle load during braking and starting. The axle load sensors or air bellows 43, 44 are connected by way of pneumatic lines with the pressure control module 13. Correspondingly the pressure in airbags 45, 46 provided at the front axle, which here are electrically controlled, may be detected by the transducer 47. However, the axle load sensors 45,46 are not absolutely necessary.

To provide stability control a lateral acceleration sensor 50 is provided, which may also be integrated with a 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 that lateral acceleration on the trailer is detected, the pressure control module can provide for increased brake force at the front and/or rear axles. When the lateral acceleration sensor 50 detects lateral acceleration on the trailer in which it is installed, the sensor generates a signal setting the stability control to active. With respect to the embodiment described to Figure 1, the ABS valve 32 may be replaced with an electro-pneumatic valve where the electric control line 35 consists of a commutation means preferably CAN and an electric power source.

The pressure control module 13 receives data from the wheel speed sensors on the trailer and also receives a signal indicating whether the brake pedal in the vehicle cab is depressed or not, as well as the brake pressure demand. In addition to the ISO 7638 electrical connection shown, trailers can also have an ISO 1185 electrical connection for supplying power to indicator lights and the trailer stop lights.

In an alternative installation of the braking system shown schematically in Figure 2 in a trailer 400. The front end of the trailer, denoted by kingpin 401, is provided with a separate ISO 12098 connector 402 and ISO 7638 connector 403. The ISO 7638 connector 403 is provided with an electronic control unit 404. The electronic control unit 404 is connected by way of an electrical and CAN bus connection 405 to the trailer EBS 406 and by way of electrical connection 407 to a splitter 408, which is also connected to the ISO 12098 connector 402 and which provides the connection to the trailer lighting system. The trailer lighting system The trailer lighting system, which is symmetrically arranged on the trailer, comprises rear light clusters 409, which clusters include the brake, reversing and night lights, top 410 and bottom 411 rear marker lights, four side marker lights 412 and a front marker light 413 the system is provided with the ISO 7638 and, optionally, ISO 1185 (or alternately ISO12098) connections being connected to an electronic control module. The electronic control module can be located at the trailer headboard and receive the brake and running gear control signals from the Truck-Trailer CAN bus. The trailer electronic module is further connected to a first trailer brake CAN bus, to which the trailer brake module (equivalent to EBS module 13) is connected The trailer brake module is further connected to wheel speed sensors and Auxiliary I/O.

In this embodiment, the trailer is provided with an internal CAN bus, in particular a 5V CAN bus, to enable auxiliary devices or functions to be installed such as a trailer information module, tyre pressure monitoring system or trailer access point. The internal bus is connected to the trailer electronic pressure module. The ISO 11992 standard defines a maximum speed on the bus at 125 Kb/s as the signal on that CAN bus has a range from 0 to the truck battery voltage. As trailers are disconnected and reconnected frequently, there is inevitably damage to the connectors resulting in attenuation of the voltage. On the known systems, a 5V CAN bus is unsuitable for connection to a truck due to this damage as the signal will be attenuated from too low a level to provide a reliable signal over the life time of the system.

The connection between the electronic control module and the module and is however permanent upon installation. The absence of any connection damage leads to much reduced signal attenuation on the CAN bus connections so the 5V CAN bus can be used. Moreover, the speed of the data signals on this CAN bus can also be increased to 250Kb/s or higher, which in turn enables much more data to be placed on the CAN bus. This enables the introduction of further functionality on the trailer such as obstruction detection or lane control.

The trailer internal CAN bus enables auxiliary devices or functions to be installed such as a trailer information module, tyre pressure monitoring system or trailer access point such as that disclosed in GB2499459. The trailer internal bus is connected to the electronic control module.

The electronic control module comprises a power management function, the CAN bus connections and the warning light circuit connection. The control logic for the trailer brake system is located in this module rather than in the brake control module.

Figure 3 shows schematically a connector 100 having for a brake control unit such as the pressure control module/ECU 13 described in Figure 1 above. The connector comprises a connector compatible with one of SAE 560:2020^ ISO 1185:2003 ISO 7638-1/2:2018, ISO 11992:2021 and/or IS012098:2020 (or more than one of them) for connecting the brake control module to a towing vehicle. The brake control module having a second connector for connection to further components on the trailer, which may include wheel speed sensors, tyre or airbag pressure sensors or other components on the trailer. The second type of connectors would not follow the same standards as the connector for connections to the towing vehicle but could be industry type connectors such as HDSCS. These connectors have a plurality of pins depending on their purpose, typically 2, 3, 4 or 6 pins.

Figure 4 shows a blind plugs 101 for the connector 100 of Figure 3. The blind plug can be realized by using an automotive standard sealed connector 100 in which electrical contacts 102, 103 are placed in at least two chambers of the connector. The contacts, which may be implemented as crimp contacts, carry a short cable or similar electrically suitable material to establish an electrical connection between first 102 and second pins 103 on the connector. Preferably, the pins are provided with electrical error detection.The blind plug adapter shown in Figure 4 therefore provides electrical shorting links. The ECU 13/404/406 is able to measure the electrical resistance of an established electrical connection. The ECU 13/404/406 is capable of distinguishing between an open circuit and either a short circuit e.g 0 Ohms or a defined other value.

The blind plug needs to be fitted with at least two electrical connections and a shorting link, electrical resistor or other technically useful electrical component between those two connections.

Ideally the electrical resistance differs from typical resistance values of components of a brake & chassis control system which would normally be connected to the respective ECU connector. This may be zero or another value suited for the application.

During parametrization of the ECU 13 or 404/406 each and every electrical connection available will be assigned with its desired functionality, unless that is defined by the design of the ECU in the first place.

The ECU will then test every electrical connection during a so-called End-of-Line test and therefore identify whether the vehicle setup is correct and error free.

On those electrical connectors where no functionality has been programmed, the ECU will then look for the specific electrical resistance of the enhanced blind plug. If that cannot be detected but an open circuit would be detected, the ECU diagnostics program would indicate an open electrical connector. Furthermore, during operation these plugs can be continually monitored, and an optical warning signal can be sent to the driver and logged in the failure memory to warn if the plug has been removed and not refitted e.g. during servicing. This can be either through a direct connection to a warning lamp or via the CAN bus or PLC connection.

At this time, the standards in force are ISO 1185:2003 ISO 7638-1/2:2018, ISO 11992:2021 and 18012098:2020.