AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION INNOVATION PATENT Invention title: Electrical Connector The following statement is a full description of this invention, including the best method of performing it known to us: -2 Electrical Connector Field of Invention This invention relates to electrical connectors for electrical connection between a tow vehicle and a towed vehicle. Preferred embodiments of the invention find particularly 5 effective operation when used with vehicle trailers, however, preferred embodiments are equally effectively applied to other kinds of towed vehicle such as caravans and the like. Background 10 Towed vehicles such as for example trailers for road vehicles have various electrical services including lights, such as brake, tail lights and indicator lights. These are generally powered and controlled from a tow vehicle. The electrical connection from the trailer to the tow vehicle is usually via a detachable multi strand cable. Typically the tow vehicle has a socket mounted at its rear into which 15 a plug on the cable of the trailer is inserted. To allow for movement of the trailer relative to the tow vehicle the cable cannot be taut and there must be extra cable, i.e. some slack, to accommodate this relative movement. When the trailer is detached from the tow vehicle the plug is removed from the socket and then hangs from the loose cable. The plug and cable can present a safety hazard 20 when manoeuvring a trailer. For example a person manoeuvring the trailer may trip on the cable. In addition, the plug and cable may be damaged or contaminated with debris, such as dirt. Most single axle trailers are balanced so the trailer hitch rests on the ground when unloaded. The cable and plug are at the hitch end and commonly either rest on the ground, where they can be contaminated or can be crushed by the trailer 25 hitch. Electrical connectors are typically provided in one or two forms. In one form the connector is in a fully assembled form, with the cable permanently attached to the electrical pins or sockets and, usually encased in a moulded shell. The other form is for attachment to a cable at a later date. Permanently attached cables typically are 30 connected to rolled terminals that are crimped to the electrical wire. Connectors for - 3 which the cable is attached later are typically provided with terminals formed of solid metal that has been machined to have a bore for the wire and a threaded side aperture for a screw. Whilst these allow a cable to be attached and detached they are more expensive than rolled terminals. 5 Summarv of the Invention In accordance with one aspect of the present invention there is provided an electrical connector for a towed vehicle, the electrical connector includes: a plug adapted to receive a cable at one end; 10 connector terminals at the other end of the plug, the connector terminals for making electrical connection with cooperating connector terminals on a cooperating electrical connector on a tow vehicle; a first magnet on the plug or in the plug for temporarily securing the electrical connector to the towed vehicle when the electrical connector is not in use. 15 Preferably the electrical connector further includes a second magnet on the plug or in the plug and spaced from the first magnet. Preferably the plug is a moulded plug. Preferably the one or more of the connector terminals in the electrical connector are constructed from sheet metal. Preferably, the one or more terminals are rolled from 20 sheet metal. In another preferred embodiment, the plug includes a multi-part shell which is adapted to house the connector terminals. The plug may be provided with and connected to a cable to form part of the electrical connector. Typically the cable is a multi strand cable. 25 A cooperating structure may be provided in the form of a secondary socket or plug mounted on the towed vehicle into which the plug is inserted and secured. The rolled terminal may include a first portion formed from rolled sheet metal defining a bore for receiving an electrical wire and a first aperture in the wall of the first portion for receiving a screw for clamping the wire between the screw and the wall of the first -4 portion. The first aperture may be sized so the screw is a clearance fit in the aperture. Alternatively, the first aperture may be an interference fit. The material of the wall and the size of the first aperture may be chosen so that the thread of the screw engages 5 the first aperture in a threaded manner. The first aperture may be deformed by the thread of the screw to present a complementary thread or the first aperture may be provided with a complementary thread. The rolled terminal of preferred embodiments of the invention may be located in a plastics carrier that has a second aperture that aligns with the first aperture. The 10 second aperture may be a clearance fit with the screw or may engage the thread of the screw. The second aperture may be provided with a thread with which the screw engages. This may be by way of a separately threaded component, such as a nut, embedded in the plastics material. Alternatively the second aperture may be sized so the screw 15 forms a thread on first use. Alternatively the aperture may be formed with a thread for the screw. The at least one rolled terminal may include at least one plug type rolled terminal, at least one socket type rolled terminal or both at least one plug type rolled terminal and at least one socket type rolled terminal. 20 The screw may engage one or both of the first and second apertures. Preferably the screw only engages either the first or the second aperture. Preferably the rolled terminal includes means to prevent or limit rotation about a longitudinal axis when mounted in the carrier. The means to prevent or limit rotation is preferably a part of the first portion that has a non circular cross section. In one form a 25 part of the wall of the first portion is pressed outwards. Preferably the carrier has a complementary recess into which the part of the wall extends. This enables the terminal to be correctly aligned in the carrier recess so that the first and second apertures align. In use, in embodiments where rolled terminals are provided, when the screw is holding the wire in the terminal, the screw also prevents the terminal being pulled or pushed out 30 of the carrier.
- 5 Brief Descriotion of the Drawings In order to enable a clearer understanding, preferred embodiments of the invention will hereinafter be described with reference to the attached drawings, in which: 5 Figure 1 is a perspective view from below and one side of a plug being one embodiment of the present invention; Figure 2 is a rear elevation view of the embodiment shown in Figure 1; Figure 3 is a plan view from below of the embodiment shown in Figure 1; Figure 4 is a front elevation view of the embodiment shown in Figure 1; 10 Figure 5 is a perspective view from above and one side of the embodiment shown in Figure 1 of the invention; Figure 6 is a schematic plan view of a trailer incorporating the embodiment shown in Figure 1; Figure 7 is a plan view of a rolled terminal which is a component of preferred 15 embodiments of the invention; Figure 8 is a side elevation view of the rolled terminal shown in Figure 7; Figure 9 is a plan view from below of the rolled terminal shown in Figure 7; Figure 10 is a perspective view of the rolled terminal shown in Figure 7; Figure 11 is a plan view of a rolled terminal which is a component of preferred 20 embodiments of the present invention; Figure 12 is a side elevation view of the rolled terminal shown in Figure 11; Figure 13 is a plan view from below of the rolled terminal shown in Figure 11; Figure 14 is a perspective view of the rolled terminal shown in Figure 11; Figure 15 is a cross sectional view of a carrier for a selection of the terminals in Figures 25 7 - 14 being carried; -6 Figure 16 is a plan view of the carrier of Figure 15; Figure 17 is a cross sectional view of the carrier of Figure 15 with a different mix of terminals; Figure 18 is plan view of an electrical connector according to another preferred 5 embodiment of the invention; Figure 19 is an axial cross sectional view of part of the connector of figure 18 taken along line AA of Figure 18; Figure 20 is cross sectional view of the bottom shell part of the connector of Figure 18; Figure 21 is a partial plan cross section taken along line BB of Figure 19; 10 Figure 22 is a side view of a rolled terminal which is a component of a preferred embodiment of the present invention; Figure 23 is a plan view from below of the terminal of Figure 22; Figure 24 is an end elevation view from the rear of the terminal of Figure 22; and Figure 25 is an end elevation view from the front of the terminal of Figure 22. 15 Detailed Description of Preferred Embodiments Referring to Figures 1 to 4 there is shown an electrical connector 10. The connector 10 is typically used on trailers (and other towed vehicles such as caravans and horse floats) to connect the electrical system of the trailer to the electrical system of a tow 20 vehicle. The connector 10 is connected to a multi strand cable 12 which is connected to a moulded plug 16 at one end. To assemble this embodiment, the cable 12 is connected to connector terminals (pins and sockets) 14 prior to moulding of the moulded plug 16, the terminals being disposed generally at the other end of the moulded plug 16 for connection to a cooperating electrical connector, usually mounted 25 on a tow vehicle. The cooperating connector may be a socket type connector. The connector 10 has a magnet 18 secured in the plug 16. The magnet 18 may be secured by moulding the plug around the magnet during manufacture or by providing - 7 the plug with a recess and gluing or otherwise securing the magnet to the plug post manufacture. As seen in Figure 2 the magnet is provided on the bottom of the connector. If desired a second magnet may be provided on the top 20 of the moulded plug 16. 5 In use the plug portion 22 of the connector 10 may be inserted as normal into a corresponding socket mounted on a tow vehicle. When the trailer is not connected to the tow vehicle the connector may be temporarily connected to part of the structure of the trailer, as shown in figure 6. As seen in figure 6, a typical trailer has a hitch portion 24 and one or two draw bars 26, which connect the hitch portion 24 with the rest of the 10 trailer 27. The draw bars are typically steel and so are magnetic. Typically the cable 12 is secured to the draw bars and has a free end portion 28. In prior art systems this allows the connector 10 to hang and, potentially, drag on the ground or trip someone up. As seen in figure 6 the connector may be attached to one of the steel draw bars 26 15 using the magnet 18. The connector may be attached to the draw bar 26 remote from the hitch portion so the cable 12 is reasonably taut. The connector 10 is thus secured and does not drag on the ground, where it can be damaged or the pins contaminated by dirt and the cable 12 is also secured, so reducing the risk of a person tripping or otherwise tangling with the cable. If the connector is contaminated by dirt this can 20 cause a bad electrical connection between the connector and the tow vehicle socket. This can cause one of more of the trailer vehicle lights to be inoperative, which is a safety issue. Dirt contamination can also cause difficulty in the mechanical connection and/or disconnection of the connector and socket. When the trailer is next used the user merely pulls the connector 10 away from the 25 draw bar 26. The connector 10 need not be a moulded connector and may be formed with a multipart shell that is assembled around the cable 12 and electrical connectors after electrical connection of the cable to the pins. Paint on the trailer may result in the magnetic attractive force being marginal or 30 insufficient to secure the connector to the trailer. Accordingly, a second magnet may be provided on the trailer, preferably in a suitable mounting, for permanent attachment to the trailer so as to provide more secure attachment. When the connector 10 is to be -8 attached to the trailer the user merely connects the first magnet on the connector 10 with and second magnet on the trailer together. Whilst provision of one or more magnets on the connector is the preferred way of securing the connector to the trailer, other arrangements may be used. 5 The plug of the connector may be provided with a clip or other structure that engages a corresponding structure on the trailer, or vice versa. Accordingly the trailer may include a clip into which a portion of the plug is received or the clip may be received in a portion of the plug. The connector in Figures 1 to 5 is a plug connector that connects to a corresponding 10 socket on a tow vehicle. The trailer may be provided with a similar socket into which the plug portion of the connecter is inserted when not in use. Preferably such a socket is spaced from the hitch portion so as to reduce the slack in the cable. Where the connector is a socket a corresponding plug portion may be mounted on the trailer. Referring to Figures 7 to 14 there are shown terminals 50 and 52 which are 15 components of preferred embodiments of invention. The terminal 50 is a pin adapted to be inserted into complementary socket terminal 52. The pin 50 includes a connection portion 54, which connects with connection portion 56 of socket 52. The pin terminal 50 has a wire connection portion 58 for receiving an electrical wire or cable. Similarly the socket terminal 52 has wire connection portion 60 for receiving an 20 electrical wire or cable. The pin and socket terminals 50, 52 are formed from sheet metal that has been rolled into a cylindrical form, rather than from a solid piece of metal that has been machined as appropriate. The connection portions 58, 60 have an aperture 62, 64, respectively, that is to allow a 25 screw to pass into the interior of the connection portion and sandwich a cable of wire within between the screw and the opposing wall of the connection portion. The terminals 50 and 52 used with the plug (and corresponding socket) of figures 1 to 6 are relatively large and may be formed of relatively thick sheet metal. A thickness of about 0.8 mm may be used. A thread is formed on the apertures 62 and 64 with which 30 the screw engages. However, as explained later with reference to another -9 implementation, the screw threads on the apertures 62, 64 are not essential. The connection portions 58, 60 are provided with an anti rotation outer surface. In this implementation the connection portions are generally cylindrical but have a portion of the wall pressed outwards to form protrusions 66, 68. 5 The terminals 50 and 52 may also be used in any other kind of electrical connector requiring the ability to attach or detach electrical wires. The terminals are preferably used in a magnetic connector formed of a two part shell. Referring to Figures 15 to 17 there is shown a terminal carrier 70 that carries pin terminals 50 and socket terminals 52. The carrier 70 has through bores 72 in which the 10 terminals 50, 52 are received. Each through bore 72 has a recess 74 into which the protrusions 66, 68 extend, thus locating the terminals and preventing rotation about their longitudinal axes. Each through bore 72 also has a radially extending opening 76 that aligns with the apertures 62, 64. The recess 74 and protrusions 66, 68 align the apertures 62, 64 on 15 the terminals with the corresponding opening 76. The openings 76 extend through the carrier and are open at the exterior of the carrier. Screws not shown are located in the openings 76 and extend into the respective connection portion of the terminals. The threads of the screws engage the surface of the openings and/or the surface of the apertures 62, 64 and are screwed inwards to trap wires (not shown) between 20 themselves and the opposing wall of the terminal. In this embodiment preferably openings 76 are oversize and the thread of the screws does not engage the material of the carrier 70. If desired the openings 76 may be sized so the thread of the screws does engage the material of the carrier 70. The carrier may be formed with a complementary thread on the openings 76. However, if an appropriate 25 material is used for the carrier the screw may cut a thread on first use. Once the screws are inserted into the terminals 50, 52, the terminals are retained in the carrier by the screws being located in the openings 76. Axial force applied to the terminal, such as when connecting and disconnecting -the plug and socket is transferred from the terminal to the carrier via the screw and so pull out or push out of 30 the terminals is inhibited. If desired the carrier may be provided with separate threaded components within the - 10 openings 76 with which the screws engage. If such components are used these may be threaded metal nuts or similar, preferably embedded in the material of the carrier during manufacture. A flat plug 100 according to another embodiment of the invention is shown in Figures 5 18 to 21. The flat plug 100 has number of pin terminals 102 extending side by side and mounted in a bottom shell part 104. The pin terminals 102 are have similar functional features to the pin terminal 50 but are physically smaller and are formed of thinner sheet metal. The plug 100 is provided with a magnet in a similar manner to the plug of Figures 1 to 10 5. The bottom shell part 104 has a series of openings 106 into which the pin terminals 102 are received. As seen in figure 20 each opening 106 has a groove 108 that receives protrusion 110 of pin terminal 102. Protrusion 110 corresponds to protrusion 66 of terminal 50. 15 Each opening 106 also has an opening 112 for receiving a screw 114. When the pin terminal 102 is inserted into the opening 106 the opening 112 aligns with opening 116 in terminal 102. In this embodiment the opening 112 is sized so that the thread of screw 114 engages the opening 112 and screw 114 is retained in the shell 104 by its engagement with the 20 shell 104. The screw is preferably a clearance fit with opening 116 in terminal 102. The screw clamps a wire (not shown) between itself and the opposing wall of the terminal 102 and also retains the terminal within the opening 106 against pull out or push out. In this embodiment the carrier is formed and the formed rolled terminals are inserted into the carrier. The carrier may be moulded or otherwise formed about the rolled 25 terminals, such as in a plastics injection moulding machine. A rolled terminal 120 which can be used in other arrangements is shown in Figures 22 to 25. The terminal 120 is formed from sheet metal that has been rolled into a cylindrical form. The terminal 120 is a pin adapted to be inserted into complementary socket, such as 30 terminal 52 of figures 11 to 14. The pin 120 includes a connection portion 122, which - 11 connects with connection portion 56 of socket 52. The pin terminal 120 has a wire connection portion 124 for receiving an electrical wire or cable. The wire connection portion 124 is provided with an anti-rotation outer surface. In this 5 implementation the connection portion is generally cylindrical but has a portion of the wall pressed outwards to form protrusion 130. The wire connection portion 124 has an aperture 128 that is to allow a screw to pass into the interior of the connection portion and sandwich a cable of wire within between the screw and the opposing wall of the connection portion 124. 10 The connection portion 122 is formed of three arms 132a, b and c. These arms are generally cylindrical and each extends about 1/3 of the way around the circumference. The arms 132 are separated by gaps 134 and thus may flex radially inwards or outwards. This provides a more progressive and more consistent fit between the male and female terminals. Although the preferred implementation has three arms, other 15 numbers of arms may be used, such as 2, 4, 5, 6, etc. Each arm 132 has a portion 136 of its wall pushed radially outwards that engages the inner surface of a corresponding socket. The foregoing features of preferred embodiments of the invention may be combined in any combination of features where features are not mutually exclusive. 20 It will be apparent to those skilled in the art that many modifications and variations may be made to the embodiments described herein without departing from the spirit or scope of the invention. Unless the context clearly requires otherwise, throughout the description and any claims the words 'comprise', 'comprising', and the like are to be construed in an 25 inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".