Patent Publication Number: US-2021188026-A1

Title: Truck Trailer Interface

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates to an interface between a trailer and 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. 
     EP 546370 discloses a truck tractor and trailer electrical communication system having one electronic control unit located in the tractor and another electronic control unit located in at least one trailer both respectively controlling the state of a plurality of switching devices to establish the appropriate electrical connection into and out of a standard seven pin tractor/trailer electrical connector where data communication links are used for control and diagnostics. 
     The requirements lead to a certain degree of sluggishness with regard to technological progress in the areas covered by compatibility and interoperability. This is caused by the different age of vehicles in a fleet and the necessity of compatibility and interoperability between all of them. One example of this is the current communication protocol (ISO11992) and its maximum transfer rate of 250 kbit/s. As a consequence, large amounts of data such as those generated by modern sensors for assistance systems cannot be transferred within a given time. This prevents the application of modern sensory equipment and the associated functionality. 
     The non prior published EP3367678 discloses a method of transmitting video signals on a CAN bus. 
     The present invention therefore seeks to provide an interface suitable for a truck trailer combination which enables the use of higher data transmission rates. 
     According to a first aspect of the invention there is provided a communication interface between a towing vehicle and a towed vehicle, wherein the towing vehicle and the towed vehicle each have a connector, which connectors are connected by means of a cable, wherein the connectors are compliant with a standard selected from ISO12098, ISO7638-1/2, ISO1185, ISO3731, ISO11446 and have pins, wherein some of the pins are connected by twisted pairs of wires arranged to carry a digital differential signal. 
     According to a second aspect of the invention there is provided a connector for a standards compliant communication interface between a towing and a towed vehicle comprising an ECU adapted to be connected to a vehicle CAN bus and to vehicle lights, which ECU is configurable for high speed communication, wherein the connector is provided with a digital status detector and a high speed communication protocol driver and means for switching therebetween in dependence on detection of a ECU configurable for high speed communication on a compatible connector on a vehicle to which the connector is connected. 
     Although it would be possible to simply define a new interface, this would be very costly, as new vehicles would require the new interface and additionally the old ones as well. Such interface additions have been performed in Europe in the past and have resulted in redundant sets of standard connectors as a trailer typically requires four connectors under different standards ISO 12098:2004, 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 favors interoperability and simplicity over additional features. In this specification, high speed communication means a maximum transfer rate greater than the maximum permitted by the standard. 
     Exemplary embodiments of the invention will now be described in greater detail with reference to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows schematically the head board of semi-trailer. 
         FIG. 2  shows a flowchart on detection of high speed mode. 
         FIG. 3  shows schematically the arrangement of a connector. 
         FIG. 4  shows schematically digital communication between the towing and towed vehicle. 
         FIG. 5  shows schematically communication between a towing and towed vehicle. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows schematically the head board of a semi-trailer in accordance with European standards having a red line pneumatic connection  1  for emergency braking and a yellow line pneumatic connection  2  for service braking. Four electrical connectors are arranged between the pneumatic connections, namely a 15 pin ISO 12098 connector  3  with CAN bus, a 7 pin ISO 7638-01 connector  4  for EBS functionality, a 7 pin ISO 1185 connector  5  and a 7 pin ISO 3731 connector  6 . 
     In the first exemplary embodiment of the invention, the ISO12098 connector and the IEEE 802.3ab is re-purposed to provide a high speed data connection whilst ensuring backward compatibility. Other connectors and protocol combinations are possible and within the scope of this invention. The ISO12098 connection has 15 wires, although in principle the invention can be implemented in an electrical interface with at least 4 wires. At a level of generality, one wire or more is connected to ground and one or more carries supply voltage. Each wire within the ISO12098 connector currently carries a discrete signal or is connected to ground. However, in the invention at least 2 wires that currently carry discrete signals can be used as one pair, although it would be possible to use more than two wires if available. This pair of wires is then able to carry a digital differential signal, possibly at a lower voltage, which will allow high data rate transfer. The information associated with the discrete signals can be multiplexed on the digital bus and sent at appropriate intervals. In this way the information is not lost. Depending on how many discrete wire pairs are available, different standard physical layers (e.g. IEEE 802, BroadR-Reach) with associated transfer rates can be used 
     The interface cable is modified in such a way that the 8 wires that conduct discrete signals conform to the relevant standard (ANSI/TIA/EIA-568-A) for a category 5 cable. In this way the cable can carry discrete signals and digital differential signals with a transfer rate up to 1 Gbit/s. 
     In order to facilitate digital communication as well as backward compatibility, an ECU or IC is placed close to the connector on the towing and towed vehicle. This component is configured to automatically detect if the connected communications partner is compatible with digital signals or expects discrete signals. Accordingly, it can switch between a “high speed” and “legacy” mode. The legacy mode is also the “safe” mode that the system enters if there should be any fault with the ECU/IC or other relevant components. In its simplest form this can be achieved by circuit of one depletion type and one enhancement type FET for each discrete wire. 
     The pinning of the ISO12098 connector and those wires preferably used for digital signal transmission is shown in the table below 
     
       
         
           
               
               
               
               
               
             
               
                   
               
               
                   
                   
                   
                   
                 Preferably  
               
               
                   
                   
                   
                 Wire 
                 used for 
               
               
                   
                   
                   
                 gauge 
                 digital signal 
               
               
                 # 
                 Signal 
                 Color 
                 mm 2   
                 transmission 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 1 
                 Left Turn Signal 
                 Yellow 
                 1.5 
                 Yes 
               
               
                 2 
                 Right Turn Signal 
                 Green 
                 1.5 
                 Yes 
               
               
                 3 
                 Rear fog lamps 
                 Blue 
                 1.5 
                 Yes 
               
               
                 4 
                 Ground (−) for pin 1-3  
                 White 
                 2.5 
                 No 
               
               
                   
                 and 5-12 
                   
                   
                   
               
               
                 5 
                 Tail lamps, clearance 
                   
                   
                 Yes 
               
               
                   
                 lamps/outline marker  
                 Black 
                 1.5 
                   
               
               
                   
                 lamps, identification  
                   
                   
                   
               
               
                   
                 lamps and registration  
                   
                   
                   
               
               
                   
                 plate lamp left side 
                   
                   
                   
               
               
                 6 
                 Tail lamps, clearance 
                   
                   
                 Yes 
               
               
                   
                 lamps/outline marker  
                 Brown 
                 1.5 
                   
               
               
                   
                 lamps, identification  
                   
                   
                   
               
               
                   
                 lamps and registration  
                   
                   
                   
               
               
                   
                 plate lamp right side 
                   
                   
                   
               
               
                 7 
                 Stop lamps 
                 Red 
                 1.5 
                 Yes 
               
               
                 8 
                 Reversing lamps 
                 Pink 
                 1.5 
                 Yes 
               
               
                 9 
                 +24 V permanent 
                 Orange 
                 2.5 
                 No 
               
               
                 10 
                 Brake wear indicator 
                 Grey 
                 1.5 
                 Yes 
               
               
                 11 
                 Indication of applied  
                 Black/White 
                 1.5 
                 Yes 
               
               
                   
                 parking brake due to  
                   
                   
                   
               
               
                   
                 loss of air pressure 
                   
                   
                   
               
               
                 12 
                 Lift Axle 
                 Blue/White 
                 1.5 
                 Yes 
               
               
                 13 
                 ground (−) for pin  
                 Red/White 
                 2.5 
                 No 
               
               
                   
                 14 and 15 
                   
                   
                   
               
               
                 14 
                 CAN H (ISO11992-3) 
                 Green/White 
                 1.5 
                 No 
               
               
                 15 
                 CAN L (ISO11992-3) 
                 Brown/White 
                 1.5 
                 No 
               
               
                   
               
            
           
         
       
     
     Out of the 15 wires available, 10 can be used as wire pairs for digital transmission. As only 4 pairs are required for the IEEE 802.3ab protocol, either 4 pairs are designed to conform with a category 5 cable (impedances, distance per twist, etc.) and 2 wires are left to carry discrete signals or 5 pairs are designed conform to category 5 cable standards and spare wire pair is used for any cable faults for additional safety. 
     The ground and supply wires remain unchanged as do wires already carrying digital signals, such as those for the ISO11992-3 CAN bus. This bus can be used as a safety relevant bus and potentially be used to determine “high speed” and “legacy”. 
       FIG. 2  shows a flowchart for the determination of whether high speed mode is supported. In the first step  201  after the trailer and truck are connected and power is switched on, an ISO 11992 CAN connection is established over the ISO 12098 connector between truck and trailer. In the second step  202 , the ECU sends a message on the bus to see if high speed mode is supported. The ECU then in step  203  listens for a high speed message supported signal from the counterpart ECU on the truck or trailer, respectively. If, after a predetermined time interval has passed and no confirmation has been received that the counterpart supports a high speed mode, then the ECU selects in step  204  a digital status reading mode. If a signal is received that confirms that high speed mode is supported, then the ECU selected the IEE 802.3ab Driver in step  205 . 
       FIG. 3  shows schematically the arrangement of a connector with the ISO 12098 interface  301  with the CAN bus (ISO 11992-3) lines connecting directing to the ECU  302 . The signal lines from the interface  301  are connected to digital change over  303 , which is connected directly to the ECU  302  as well as indirectly via Digital Status Detection  304  and the IEE 802.3ab Driver  305 , which is arranged in parallel to the Digital Status Detection  304 . The ECU  302  is then further configured to supply control signals to the high power drivers  306  which control the signals to the vehicle lights  308  and to a video decoding and compression unit  307  which receives signals from cameras  309 . 
       FIG. 4  shows schematically digital communication between a towing  401  and towed vehicle  402 . The vehicle combination is provided with respective ISO 12098 connectors  403  and  404 , which are joined by a cable  405 . A first ECU  406  is provided on the towing vehicle  401 , which ECU  406  receives signals such as video and discrete signals, such as for vehicle lights, as well as supply and ground. The ECU  406  is connected to the connector  403  and also connected to the ISO 11992-3 bus  407 . 
     A second ECU  408  is provided on the towed vehicle  402 , which ECU  408  receives signals such as video and discrete signals, such as for vehicle lights, as well as supply and ground. The ECU  408  is connected to the connector  404  and also connected to the ISO 11992-3 bus  409 . 
     In a first variant, the wires on pins 1, 2, 3, 5, 6, 7, 8 and 10 are used to form four twisted pairs, which conform to the Category 5 standard. Wires 11 and 12 remain as with a conventional ISO 12098 connection. 
     In a second variant, wires 11 and 12 are also used to make a fifth twisted pair, which conforms to the Category 5 standard. 
       FIG. 5  shows schematically communication between a towing  501  and towed vehicle  502 . The vehicle combination is provided with respective ISO 12098 connectors  503  and  504 , which are joined by a cable  505 . The towing vehicle is a legacy vehicle without the ECU shown in  FIG. 4 . 
     The trailer is provided with an ECU  508 , which ECU  508  receives signals such as video and discrete signals, such as for vehicle lights, as well as supply and ground. The ECU  508  is connected to the connector  504  and also connected to the ISO 11992-3 bus  509 . However, when the ISO12098 connection is powered, the ECU  508  detects that the towing vehicle is not able to communicate with high speed data and switches to a legacy mode in which the wires in the connection cable are used conventionally.