GB2480811A

GB2480811A - Towing socket assembly

Info

Publication number: GB2480811A
Application number: GB1009026A
Authority: GB
Inventors: David Morewood
Original assignee: AMBER VALLEY DEVELOPEMENTS Ltd
Current assignee: AMBER VALLEY DEVELOPEMENTS Ltd
Priority date: 2010-05-31
Filing date: 2010-05-31
Publication date: 2011-12-07
Anticipated expiration: 2030-05-31
Also published as: GB201009026D0; GB2480811B

Abstract

An electrical towing socket 1 comprises supply pins for providing electrical power to a trailer is bolted to a housing 2 provided with a supply cable 3 for connection to an electrical system of a vehicle. The supply cable carries supply wires for connection to an auxiliary power source within the vehicle and a group of sensing wires for connection to various lighting circuits. The housing 2 contains switching circuits having a high impedance sensing input connected to a respective sensing wire and which responds to the presence of a voltage on the sensing wire by connecting a respective supply pin to the auxiliary power source via the supply wires. The switching circuits are all sealed within a back housing by means of a settable potting compound and the back housing incorporates guide tubes. The back housing is a separate body and the housing includes a circular back wall surrounded by a cylindrical side wall.

Description

TOWING SOCKET ASSEMBLY

TECHNICAL FIELD OF THE INVENTION

This invention relates o rowing sockets.

BACKGROUND

Vehicles which are equipped o ow trailers are fitted with a towing socket through which lights fitted to the trailer may be operated from the towing vehicle. Many modern vehicles are fitted with a Controller Area Network (often referred o as a WCAN or "CAN bus") which uses an established serial signalling protocol by which microconrollers and devices within the vehicle can communicate with each other. The CAN bus system is also arranged o monitor the current flowing in each circuit. An increase in current generally signals a fault condition which is displayed o the driver as a warning message.

In CAN bus equipped vehicles, the additional current drawn by the trailer would be deeced as a fauft condition by the CAN bus system, so in order o avoid this an interface unit is hard wired into the vehicle, in a location where it is shielded from water, road salt etc. The interface unit reads the voltage on each of the lighting circuits via a high impedance sensing input, and if a voltage is detected it activates the appropriate trailer circuit via an auxiliary power connection from which current can be drawn without triggering a fault condition.

Installing such an interface unit and connecting it up to the towing socket is a major undertaking. A suitable protected location must be found for the interface unit which is accessible by the installer, and there are a large number of connections which must each be made and tested.

The present invention seeks to provide a new and inventive form of towing socket which is compatible with CAN bus vehicles, reliable, and easy to install.

SUMMARY OF THE INVENTION

The present invention proposes a towing socket assembly which includes an electrical socket having supply pins for providing electrical power to a trailer, and a back housing provided with a supply cable for connection to the electrical system of a vehicle, in which the supply cable carries supply wires for connection to an auxiliary power source within the vehicle and a group of sensing wires for connection to various circuits within the vehicle, and the socket assembly includes switching circuits each having a high impedance sensing input connected to a respective sensing wire and which responds to the presence of a voltage on the sensing wire by connecting a respective supply pin to the auxiliary power source via the supply wires, and the switching circuits are all sealed within the back housing.

The back housing is preferably a separate body which incorporates guide tubes which align with apertures in the socket to receive fixing bolts. The back housing is preferably of substantially the same diameter as the adjacent end of the socket, The switching circuits may be carried on a board which is sealed within the back housing, e.g. by means of a settable potting compound.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice.

In the drawings: Figure 1 is a towing socket assembly in accordance with the invention; Figure 2 is a front view of the back housing incorporated in the assembly; Figure 3 is an axial section through the back housing; and Figure 4 is a circuit diagram of a typical switching circuit for use in the socket assembly.

DETAILED DESCRIPTION OF THE DRAWINGS

Although the following description refers particularly o a UK 7-pin socket by way of example i will be appreciated ha the invention is equally applicable o 13-pin Euro sockets, as explained below.

Referring firsdy o Fig. 1, the towing socket assembly includes a socket 1, a back housing 2 and an electrical supply cable 3 for connection o the electrical system of a vehicle. The socket 1 is a conventional 7-pin towing socket comprising a circular housing containing seven electrical supply pins for providing electrical power to the lights of a trailer via an electrical plug which is inserted into the socket upon lifting a spring-loaded cover 11.

Normally, the socket would be mounted directly on a drop plate fixed to the vehicle by means of three boles 12, which are inserted through apertures in the socket and through the drop plate to be secured by back nuts behind the plate. In the present assembly the boles are somewhat longer since they pass through the housing 2 before being inserted through the drop plate as described.

Referring to Fig.s 2 and 3, the back housing 2 is cup-shaped, with a cylindrical side wall 20 and a back wall 21, of the same outer diameter as the adjacent end of the socket 1. Three guide tubes 22 are formed integrally with the back wall 21 inside the wall 20 to receive the bolts 12, and the back wall contains a central aperture 23 through which the supply cable 3 exits. The supply cable 3 contains a group of six sensing wires for connection to different lighting circuits within the vehicle together with a pair of supply wires for connection to an auxiliary power source within the vehicle, normally taken direct from the vehicle battery. Each sensing wire is connected to a high impedance sensing input of a respective switching circuit.

The switching circuits are mounted on a common circuit board 24 contained within the housing 2. Fig. 4 shows a typical circuit diagram of one of the switching circuits by way of example, although it will be appreciated that the switching circuits could be implemented in other ways, e.g. with semiconductor switches and opto-isolators. In Fig. 4 each switching circuit has a high impedance sensing input B connected to one of the sensing wires in cable 3, which supplies a driver transistor TR1 via a resistor Ri. TR1 controls a switching relay RL1 which is connected between the two supply wires of cable 3 which provide a continuous voltage between A and B. Resistor R2 ties the input of TR1 to earth so that when no voltage appears on the sensing input the transistor is biased off. However, when a voltage appears on the vehicle lighting circuit Ri and R2 form a high impedance potential divider from the sensing input B to earth, thus biasing the TR1 "on" to energise the relay. When the relay conacs close they connect the positive supply line A o the appropriate pin of socket 1 via D. The trailer chassis is grounded o E via an earth pin within socket 1.

The following table gives the input connections o the vehicle and the corresponding oupu connections o the trailer through the pins of the socket assembly: Input from Vehicle Socket Trailer Output (Supply Cable) Pin No. LH indicator 1 LH indicator Fog 2 Fog GND 3 Chassis RH indicator 4 RH indicator RH tail 5 RH tail Brake 6 Brake LH tail 7 LH tail +l2vAux(BatX) -- Buzzer + -- Buzzer ---In a 7-pin socket the +12v auxiliary supply is no fed through o the trailer. The wo addiionaI wires, Buzzer + and -, may be used to operate a buzzer o provide confirmation inside the vehicle that the trailer indicator lights are functional. A conventional driver circuit may be incorporated onto the circuit board within the housing 2 o operate the buzzer whenever a voltage appears on one of the wo indicator inputs.

Returning to Fig.s 2 and 3, the circuit board 24 which carries the switching circuits is initially held in the housing by a spider which is a push-fit over the tubes 22. The seven output wires to the trailer socket 1 pass around the sides of the spider.

The switching circuits are then sealed within the housing 1 by means of a settable potting compound which is poured into the housing to completely enclose the circuit board together with the components mounted thereon, making a completely waterproof assembly. It should, however, be noted that whilst this method of sealing is simple, reliable and inexpensive, other means of sealing the switching circuits inside the housing may be employed, e.g. by sandwiching an elastomeric sealing ring between the socket 1 and the housing 2. The seven wires emerge from the set potting compound and are connected to the individual pins at the rear of the socket.

The socket assembly is very easy to fit, inexpensive, reliable and waterproof, being suitable for use in pickup trucks in which waterproofing is a particular requirement. It will be noted that the trailer socket can also be installed in a non CAN bus vehicle, requiring only one additional connection to a suitable auxiliary supply point.

In the case of a 13-pin Euro socket the additional pins are connected through the cable 3 to the appropriate vehicle circuits. The reversing light (pin 8) and fridge supply (pin 10) are be provided with an additional switching circuit incorporated into the back housing 2.

WhiIs the above description places emphasis on the areas which are believed o be new and addresses specific problems which have been identified, i is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the are.

* * * * * * * *

Claims

CLAIMS1. A t:owing socket: assembly which includes an elect:rical socket: having supply pins for providing elect:rical power t:o a t:railer, and a back housing provided with a supply cable for connect:ion t:o the elect:rical syst:em of a vehicle, in which the supply cable carries supply wires for connect:ion t:o an auxiliary power source within the vehicle and a group of sensing wires for connect:ion t:o various circuit:s within the vehicle, and the socket: assembly includes swit:ching circuit:s each having a high impedance sensing input: connect:ed t:o a respect:ive sensing wire and which responds t:o the presence of a voftage on the sensing wire by connect:ing a respect:ive supply pin o the auxiliary power source via the supply wires, and the switching circuits are all sealed within the back housing.
2. A t:owing socket: assembly according t:o Claim 1 in which the socket: is mount:ed on the back housing which is formed as a separate body.
3. A t:owing socket: assembly according t:o Claim 2 in which t:he back housing incorporat:es guide t:ubes which align wit:h apert:ures in t:he socket: t:o receive fixing bolt:s.
4. A t:owing socket: assembly according t:o any preceding claim in which t:he housing includes a circular back wall surrounded by a cylindrical side wall.
5. A towing socket assembly according o any preceding claim in which the housing is of subsanially the same diameter as the adjacent end of the socket.
6. A towing socket assembly according o any preceding claim in which the switching circuits are carried on a board which is sealed within the back housing.
7. A rowing socket assembly according o Claims 6 and 3 in which the board is held by a spider which engages the guide Wbes.
8. A towing socket assembly according o Claim 6 or 7 in which the switching circufts are sealed within the housing by means of a settable potting compound.
9. A towing socket assembly subsanially as described with reference o the drawings.* * * * * * * *