Patent Abstract:
A vehicle trailer male electrical connector  10,  especially for use with a vehicle tracking or data logging system and which having an array of connector pins  11-17  for interconnecting electrical power between a vehicle trailer and tractor unit, and which includes an electrical switch  43  in an open or closed condition, and which is changed to the other of said open and closed conditions by engagement with a female connector on a tractor unit. The switch  43  is operated by one of said connector pins  11-17  which is axially displaceable on contact with the female connector.

Full Description:
FIELD 
     This invention relates to electrical connections of the type used to couple and uncouple the electrical system of a tractor unit to a trailer. 
     BACKGROUND OF THE INVENTION 
     The electrical connection between truck tractor units and trailers for such services as lights, brake lights, indicators is a standardised 7 pin ISO 1185 (24N) connector and other auxiliary equipment may be connected through a 7 pin ISO 3731 (24S) connector. Most trailers are equipped with both types of connector and additionally some trailers may be equipped with an ISO 7638 connector for the ABS system on trailer if fitted. As an alternative to the latter connector the ABS system can be activated through a stop light pins of the ISO 1185 connector. Recently a new ISO 12098 15 pin connector has been introduced to combine all the features of the other three connectors. 
     With the variety in Make, type and age of trailer the only standard connector which all trailers have is the ISO 1185 connector and even when some trailers have other additional connectors some drivers only make the minima electrical connections between the tractor unit and trailer to operate the lights and indicator, i.e using the ISO 1185 connector, and therefor the trailer has only intermittent electrical power only when the brakes, lights, or indicators are operated and connected through the ISO 1185 connector. 
     It is becoming desirable to install trailer tracking and/or data logging systems in vehicle trailers to report on the trailer locations and/or status e.g coupled or uncoupled to the motor vehicle. An intermittent power supply to a trailer makes it impossible to automatically detect whether the trailer is coupled or uncoupled to a tractor unit by sensing the power supply to the trailer. 
     OBJECTS OF THE INVENTION 
     The object of the present invention is to sense the coupled/uncoupled status of a vehicle trailer independently of the power supply to the trailer, and preferably by using the standard power connectors. 
     STATEMENTS OF THE INVENTION 
     According to the present invention there is provided a vehicle trailer male electrical connector having an array of electrical connector pins for interconnecting electrical power between a vehicle trailer and tractor unit and which includes a switch in one of an open or closed condition and which is operated through one of said pins to change the condition of the switch by axial displacement of said one pin on engagement with a co-operating female connector on the tractor unit. 
     Said one connector pin may be also used as a power connector, but is preferably not utilised as a power connector. The pins may be part of any ISO standard connector e.g. ISO 1185, ISO 3731, ISO 7638 or ISO 12098. 
     The pin at its inner end extends through the body of the connector to operate the switch when the pin is displaced. 
     The pin may include a coaxial extension which seats against, or is proximate to, the switch which may be a proximity switch, or is preferably a push button switch having an internal spring biasing the switch to a open condition. 
     Also according to the invention there is provided a method of activating a trailer tracking and/or data logging system sensing coupling and uncoupling between the tractor unit and a trailer in which method a switch, in an open or closed condition, is located on one half of a power connector which is used for electrically connecting the trailer to the tractor unit, and the condition of the switch is automatically changed when the two halves of the power connector are interconnected, the change in condition of the switch being sensed by said system. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The invention will be described by way of example and with reference to the accompanying drawings in which: 
     FIG. 1 shows a front elevation of the trailer half of a known tractor/trailer electrical connector showing the connector pin array, 
     FIG. 2 shows the front elevation of the trailer half of a second type of known tractor/trailer electrical connector, 
     FIG. 3 shows a section through the trailer (male) half of a connector according to the present invention, 
     FIG. 4 shows a section through a trailer half of a an alternative connector, 
     FIG. 5 shows a section through a trailer half of another connector, and 
     FIG. 6 is a second view of the connector trailer half shown in FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to FIG. 1 there is shown half of a 7 pin standard trailer lighting connector  10  (ISO 1185). ISO stands for International Standards Organisation which aims for world wide interchangeability as is agreed by committees of experts. The seven pins  11 - 17  have various functions, pin  11  is common power return, pins  12  and  16  for the tail lights, pins  13  and  15  are for the direction indicators, pin  14  is for the stop lights and pin  17  in the UK is typically a blank pin, but may be used in other countries for selected auxiliary functions. 
     With reference to FIG. 2 there is shown a known ISO 7638 connector  20  having seven pins  21 - 27  arranged in a different pin array and which is used for connecting the trailer ABS system to the tractor ABS system. In this case the pins  25  and  26  are blank. 
     The blank pins  17 , or  25 ,  26  in either of the above connectors, or a blank pin of the ISO 12098 connector, may be utilised for the present invention, although the invention will be described by way of example, with reference to FIG. 3 which is a section through an ISO 1185 connector which is presently fitted to all trailers. 
     Now with reference to FIG. 3, the housing  31  of the male half of the connector  10  has a cylindrical body  32  with a pin socket  33  located at the inner end of the body  32  with the pins extending away from the socket  33 . The pin  11  is the longest of the pins  11 - 16 , and the blank pin  17  is located at the centre of the socket and is the longest of the pins  12 - 17 . The inner end portion of the pin  17  locates in a cavity  34  in a raised boss  38  on the inner side of the sockets  33  and has a coaxial extension in the form of a smaller diameter shaft  35  which is fixed to its inner end face  39  by any suitable method e.g. screw fixing, adhesive etc. 
     The shaft  35  extends through a hole  36  in the base of the cavity  34  and has a larger diameter head  37  on its distal end. The pin  17  is capable of limited displacement within the cavity  34 , the movement being limited by abutment of the end face  39  of the pin on one side of the cavity base, and abutment of the head  37  on the other side of the cavity base. 
     The inner end of the body  32  is covered by a cap  41 , having a central hollow spigot  42  which houses an on/off switch  43 , preferably a single pole push button switch  43 , which is slidable within the spigot. The switch  43  is biased towards the head  37  by a spring  44 , preferably an external coil spring, acting between the cap  41  and a shoulder  45  on the switch  43 . The relative movement between the switch and cap under the bias of the spring  44  takes out any manufacturing tolerances and biases the switch  43  into contact with the head  37 , which displaces the shaft and pin  17  outwardly until the head is in contact with the boss  38 . The push button switch  43  may have an internal spring which biases the switch to one of an open or closed condition. 
     The spring characteristics of the internal spring and spring  44  are selected such that the spring force of the internal spring is just greater than the spring force of the spring  44 . The components assembled together in such away that there is a constant pre-load on the spring  44  which pre-load is lower than the spring operating load of the switch  43  to keep the pin  17  pushed outwardly to its “at-rest” position without activating the switch. 
     The switch  43  is connected to a tracking or data logging system (not shown) by the electrical wire  46 . 
     When the trailer is connected to a tractor unit the female half of the connector is pushed over the pins  11 - 17  in the direction of arrow A, moving the shaft head  37  inwards against the push button switch  43 . There is an initial axial movement of the head  37  against the bias of spring  44  and the spring load in spring  44  increases changes until the load equals the switching load required for the operation of the switch  43 . Once the switch is activated, the switch remains in an activated state and any further movement is against the bias of the spring  44 , 
     The change of condition of the switch which is sensed by the tracking/data logging system through the wire  46 . The spring  44  ensures that the head  37  permanently retains the switch in an active state once both halfs of the connection has been properly interconnected. 
     In an alternative embodiment (see FIG. 5) the cap  41  may be replaced by a bracket fixed to the body  32 , and the switch  43  may be a two pole on/off switch or a  3  pin change-over switch. A pin in any type of standard connector may be utilised for the present invention. 
     With reference to FIG. 4, there is shown an alternative arrangement in which the spigot  42  housing the switch  43  is mounted resiliently to the cap or bracket  41 . The switch  43  may be adjustably mounted in the spigot  42  by a screw-threaded means  51 . The spigot  42  can be connected to the cap  41  via resilient spring fingers  52  of a belleville type spring as is shown in the upper half of FIG.  4 . Alternatively, as shown in the lower half of FIG. 4, the spigot  42  can be mounted in a rigid plate  53  attached to the cap  41  through spring or elastomeric mountings  54 . 
     In this embodiment, since the position of the switch can be accurately adjusted relative to the head  37  so that “at rest” there is just no contact, the spring characteristics of belleville spring  52  or the resilient mountings  54  should be such that they exert a greater spring load that the internal spring of the switch  43 . 
     With reference to FIGS. 5 &amp; 6, there is shown a third embodiment in which the central pin  17  is a stepped diameter elongate pin having a smaller diameter inner and outer end portions  141 ,  142 , a larger portion  143  adjacent the inner end which is a sliding fit in an aperture  144  in the body  33 , with the largest diameter portion  145  adjacent the outer end. The outer end portion  142  is slidably supported in a bracket  146  and a concentric spring  147  acting between the bracket  146  and one face  148  of the largest diameter portion  145  biases the pin  17  inwardly until the other end face of the largest diameter portion abuts the body  33 . 
     The pin  17  is prevented from rotation in the aperture  144  by co-operating flats on the pin and aperture edge. The largest diameter portion  145  has a diametral bore  149  therein for receipt of a circuit wire which may be held in place a terminal screw  151  normal thereto, The largest diameter portion also has a radial abutment  152  thereon, preferably a radial pin, which contacts an operating arm  153  of a microswitch  154 . The microswitch  154  is mounted on the bracket  146  and its operating is formed from a leaf spring which is permanently in contact with the abutment. 
     The microswitch is operated when the pin  17  moves inwards against the spring  47  when the male half connector is coupled to a female half connector.

Technology Classification (CPC): 7