GB2160035A - Junction box for outdoor power supply - Google Patents

Abstract

An electrical junction box for outdoor use in association with a battery pack such as car battery, comprising a sealed casing (10) having a power input connector (12) fitted at its remote end with a fitting (14) adapted to be received in the cigar lighter socket of a car, a plurality of output terminals in the form of jack-receiving sockets (16) providing a power output voltage equal to a power input voltage, and a current limiting fuse (18). <IMAGE>

Description

SPECIFICATION Electrical junction box This invention relates to an electrical junction box.

Current camping trends are for greater sophistication, largely made possible as the camping equipment is carried by car. Larger tenting accommodation, often with more than one room, is not unusual, and portable electrical equipment is taken, including for example portable lights, refrigerators, water heaters and other such items which can be operated from a 12V battery pack. The car battery is frequently used as the battery pack for powering such portable electrical equipment.

Conductors with so-called crocodile clip connectors are common employed to connect the equipment to the car or other battery pack, and two connecting wires are required for each item, one for supply and one for return. Isolated items have been proposed which have a power connector adapted to fit into the cigar lighter socket in a car, but only one such item at a time can be connected in this way.

Crocodile clip connectors are not satisfactory in practical use. Experience has shown that they can easily be inadvertently pulled off from a battery terminal, or can even slip out of position on a greasy terminal. Furthermore, they can be difficult and messy to connect into position, especially in the dark, whilst also giving rise to the risk of electric shock. There is often inadequate protection against overcurrents, and the battery pack can thence be drained flat.

It is an object of this invention to provide an electrical junction box which enables a solution to the above-described difficulties.

According to the invention, there is provided an electrical junction box which comprises a casing having exposed on the exterior thereof a power input connection means and a plurality of output terminals, and circuit means sealed from the exterior within the casing whereby a plurality of power outputs each of voltage corresponding to the power input voltage can be taken from the output terminals, the said circuit means including a current limiting fuse.

A preferred casing is of insulating material, such as a plastics material, with output terminals in the form of sockets for receiving jack-type connectors.

A similar type of input terminal socket may be provided, but preferably the input connection means is a dual conductor cable which emerges directly from the casing and is equipped at its remote end with a connector for fitting into the cigar lighter socket in a car. In one possible embodiment, the said conductor cable is attached within the casing to a retractor reel on to which it can be wound for storage when the junction box is not in use. Said rectractor reel may be of the known spring-loaded kind having an associated ratchet mechanism, the latter being releasable by a push button or the like so as to cause automatic retraction of the cable.

The retractor device may be housed within a compartment of the casing from which the inner end of the cable extends into a sealed part of the casing accommodating the electrical circuitry.

In general, therefore, input and output terminal connections extend through the wall of the casing in sealed manner, for example by means of sealing washers and/or resilient grommets. Alternatively, a part casing may be moulded with the terminal connections embedded in situ, the casing being completed and sealed after the electrical circuit means has been inserted and connected up. Such a casing sealed permanently during manufacture has the advantage that the circuitry is permanently enclosed against tampering or undesirable modification. The casing can be moulded with a small openable or otherwise accessible compartment affording access to the fuse, and/or to a power-on indicator such as a small neon lamp.

A sealed casing is important having regard to the external and possibly wet environment in which the junction box will often be used.

A practical example of electrical junction box in accordance with the invention is shown in the accompanying drawings, in which: Figure 1 is a perspective view of the box; and Figure 2 is a circuit diagram.

Referring to Figure 1, the reference 10 denotes a sealed casing, for example moulded of insulating plastics material. Typically the box may be about 10 cm long by 5 cm wide by 2 cm deep. A power input cable 12 extends into the box through one end wall. This cable 12 is terminated at its remote end by a plug 14 adapted to fit into the cigar lighter socket of a car.

A plurality of output terminal fittings 16 extend through the top wall of the casing 10. Three such fittings 16 are shown, but a smaller or larger number could be provided if desired. These fittings 16 are sockets of the conventional kind adapted to receive jack-type connectors 17. In practice, these jack-type connectors will be mounted to the ends of input cables leading to items of electrical equipment to be powered, one such item per fitting 16.

The other end wall of the casing 10 has a recess at which an overcurrent fuse 18 is accessible, e.g.

for replacement purposes. A neon power-on indicator may also be provided, preferably to indicate that the junction box is connected to a power source rather than to indicate that current is being drawn from an output terminal. The circuit conductors may, if desired, be carried on a printed or integrated circuit board, which also serves as a mount for components connected in the circuit.

Within the box, circuitry connects the power input cable 12 to each of the three terminal fittings, so that at each such terminal an output voltage equal to that of the power source is available. The power source will be a battery pack, typically a 12V pack such as a car battery to which connection can be made via the cigar lighter socket in the car dashboard, as above mentioned.

Figure 2 is a complete circuit diagram of the junction box employing the same references as in Figure 1. The input lines of the input cable are indicated at 20 and 22. One input line 22 is taken via the fuse 18 to one contact 24 of each jack-receiving socket 16; the other input line 20 provides a series connection to the contacts 26 of the jack-receiving sockets 16.

If desired, the input lines 20, 22 may be bridged on the left-hand side of the diagram by a neon lamp serving as a power-on indicator, this lamp being visible and accessible in like manner to the fuse 18. A high value resistor may be connected in series with the neon lamp if necessary. A power on/off switch may also be provided, preferably in line 22. Furthermore, for added security, a thermal overload device may be incorporated in the plug 14 which fits the car lighter socket.

In practice, the casing 10 may be moulded with an open base, and the output terminal fittings 16, together with a grommet for passage of the input cable and a fuse holder, embedded in situ in the appropriate positions in the end and top walls.

After inserting the printed circuit board and/or completing the internal circuit connections, the casing can then be completed and sealed by application of a cover, permanently fixed in position by plastics welding techniques.

A possible modification of the above described and illustrated arrangement is one wherein the input cable is carried by a retractor reel of the well known kind which is spring loaded and has an associated manually releasable ratchet. The retractor reel may be housed within a compartment of the casing into which the cable is retractable to leave only the plug exposed. The inner end of the cable extends into a sealed part of the casing accommodating the above-described electrical circuitry.

Various other modifications of the above-described arrangement are possible within the scope of the invention hereinbefore defined, having regard to the general aim of the invention to provide an electrical junction box which will provide a plurality of optionally usable power outputs each of voltage equal to the input voltage, especially but not exclusively in an outdoor environment such as camping where portable electrical devices and appliances are to be powered from a battery pack such as a car battery.

Claims (14)

1. An electrical junction box comprising a casing having exposed on the exterior thereof a power input connection means and a plurality of output terminals, and circuit means sealed from the exterior within the casing whereby a plurality of power outputs each of voltage corresponding to the power input voltage can be taken from the output terminals, the said circuit means including a current limiting fuse.

2. A junction box according to claim 1, wherein the casing is made of a plastics insulating material.

3. A junction box according to claim 1 or claim 2, having output terminals in the form of sockets for receiving jack-type connectors.

4. A junction box according to claim 1 or claim 2 or claim 3, wherein the input connection means is a dual conductor cable.

5. A junction box according to claim 4, wherein said dual conductor cable has an end fitting adapted to be received in the cigar lighter socket of a vehicle.

6. A junction box according to any of claims 1 to 5, wherein the input and output connections extend through the wall of the casing in sealed relationship to said wall.

7. A junction box according to any of claims 1 to 6, having a moulded casing formed in two parts which are sealed together by plastics welding after completion of electrical circuit connections within one part.

8. A junction box according to any of claims 1 to 7, wherein the circuit conductors and components are carried by a printed circuit board.

9. A junction box according to any of claims 1 to 8, wherein the fuse is accommodated in an accessible compartment of the casing.

10. A junction box according to any of claims 1 to 9, having a power on/off indicator connected in an input conductor.

11. A junction box according to any of claims 1 to 10, having a thermal overload device connected in circuit.

12. A junction box according to any of claims 1 to 11, wherein the power input connection means includes a cable attached within the casing to a retractor reel.

13. A junction box according to claim 12, wherein the retractor reel is housed within a compartment of the casing from which the inner end of the cable extends into a sealed part of the casing accommodating the electrical circuitry.

14. A junction box substantially as hereinbefore described with reference to the accompanying drawings.