GB2300770A - Vehicle electrical power distribution system; preventing battery discharge during vehicle transport or storage - Google Patents

Abstract

The distribution system has a fusebox 30 with a first busbar 35 connected directly to the battery 33, a second busbar 39 connected to battery 33 via an ignition switch 34, and fuse sockets 36A, 36B, 36C to receive a fuse 31A selectively in sockets 36A, 36B or in sockets 36B, 36C, so that a load 32A can be selectively connected either to busbar 35 or to busbar 39 but not to both busbars 35, 39 simultaneously. In order to reduce discharge of the battery 33 during long periods when the vehicle is not in use, eg. during storage or transportation, a load 32A (such as a clock) which would draw a quiescent current if left connected to the battery has its fuse 31A connected to sockets 36B, 36C so that the load 32A is coupled via the ignition switch 34 during such periods of non-use. For normal vehicle use, the fuse 31A is repositioned across sockets 36A, 36B to connect load 32A directly to the battery via busbar 35. Dual fuse positions may only be provided for the loads which would draw a quiescent current and not for other loads which would not draw a quiescent current, such as lights and a horn controlled by switches, (Fig.4), or all load circuits in the fusebox may have such dual fuse positions but in this case loads 32B which do not draw a quiescent current may be left connected via their fuses 31B to the direct busbar 35 during prolonged vehicle non-use.

Description

A Vehicle Electrical System This invention relates to a vehicle electrical system and is particularly useful in a system which provides at least one storage battery, at least one load and at least one fuse box.

Vehicle electrical systems which comprise a storage battery and a means of distributing the power from that battery to services around the vehicle are known. It is common in such systems to provide protection for the load from electrical malfunction by including a fuse in the circuit. A basic arrangement of such a prior art system is shown in Figure 1 and comprises a fusebox 10, fuses llA and llB, electrical loads 12A and 12B, a storage battery 13, a busbar 15, fuse holder connections 16A, 16B, 17A and 17B and a power connection 18. The storage battery is provided as a source of electrical power. This battery is electrically connected to the two loads. The electrical connection to each load is protected by a fuse llA or lIB in series with load 12A or 12B respectively.The series connection is made by bridging the fuse holder connections 16A and 16B or 17A and 17B respectively with a fuse. The fuses are held in the fusebox. When a serviceable fuse is in place the loads are in permanent electrical communication with the battery, whether or not the loads are switched on.

A drawback of known electrical power distribution systems of the aforementioned type is that there is a quiescent current drain on the storage battery because it is in permanent electrical communication with one or more loads which drain low currents to ground even when not in use. If the vehicle is not used for some time, for example because of long transport times or storage periods, this quiescent current drain can lead to a flat battery. The effect of the battery becoming discharged is that starting and normal use of the vehicle are compromised. There may also be long term damage to the battery if it is left in such a discharged state for a long period, resulting in reduced service life and early battery replacement.

To reduce the likelihood of quiescent current drain discharging the battery during transportation or storage, the battery lead may be disconnected. Alternatively, an isolating switch is sometimes included in the circuit to disconnect the battery from the fusebox. A disadvantage of disconnecting the battery lead is the need to handle high current circuits and perform an operation not under the quality control system of the vehicle manufacturer. Battery isolation switches also add complexity and cost to the system.

It is an object of the present invention to provide an electrical system for a motor vehicle which can withstand long periods without use.

Accordingly the present invention provides a vehicle electrical system comprising power supply means, at least one subsystem, first connecting means for providing permanent electrical connection between said at least one subsystem and the power supply means and second connecting means for providing selective electrical connection between said at least one subsystem and the power supply means wherein the connecting means are arranged such that connection of the power supply to said at least one subsystem through one of said connecting means precludes connection of the power supply to said at least one subsystem through the other of said connecting means.

The second connecting means may include switch means for providing said selective electrical connection and the switch means may comprise a vehicle ignition switch.

One of the connecting means may include a pair of contacts which can be connected together by means of a removable connecting member.

Both of the connecting means may include a pair of contacts which can be connected together by means of a removable connecting member and may include one contact which is common to both pairs such that connection of one of said connecting means precludes connection of the other of said connecting means.

The removable connecting member or members may comprise vehicle fuses.

The invention will now be described by way of example with reference to the remainder of the accompanying drawings of which: Figure 2 is a representation of a typical fuse; Figure 3 shows a schematic block diagram of an electrical system in accordance with one embodiment of the invention.

Figure 4 is a representation of a fusebox in accordance with a second embodiment of the invention.

With reference to Figure 2, a common type of automotive fuse comprises a fuse body 20, a fuse element 21 and fuse terminals 26A and 26B. The fuse terminals 26A and 26B are male blade connectors which form their connection by sliding into female terminals moulded into the fusebox.

The female terminals are so constructed as to permit only one male terminal to enter them at a time. The constituent parts of the fuse are held in their respective positions by the fuse body 20.

With reference to Figure 3, a vehicle electrical system comprises a fusebox 30, fuses 31A and 31B, electrical loads 32A and 32B, a storage battery 33, an ignition switch 34, busbars 35 and 39, fuse sockets 36A, 36B, 36C, 37A, 37B and 37C and power connections 38A and 38B.

The storage battery 33 is of the type commonly known in the industry and not described herein. The busbar 35 is in permanent electrical communication with the battery through a power connection 38A which is capable of selective disconnection. Busbar 39 is connected to an output of the ignition switch 34 through a power connection 38B which is capable of selective disconnection. The ignition switch 34 is connected to the battery and is open circuit when the ignition key is not turned "on". Load 32A represents the services which draw a quiescent current when the vehicle is not in use. Load 32B represents the services which do not draw a quiescent current when the vehicle is not in use.

Sockets 36A and 37A are connected to busbar 35, sockets 36B and 37B are connected to loads 32A and 32B respectively and sockets 36C and 37C are connected to busbar 39. The fusebox 30 is constructed to use fuses of the type described above with reference to Figure 2. The female sockets for fuse 31A are arranged such that a fuse can only bridge across sockets 36A and 36B, permanently connecting load 32A to the battery through the busbar 35, or across sockets 36B and 36C, connecting the load 32A to the battery through the selective busbar 39 and the ignition switch 34.

It is not possible to bridge both gaps because the sockets, including socket 36B which is common to both positions of fuse 31A, can only accept one male terminal at a time. In like fashion, there is a mutually exclusive arrangement for fuse 31B to bridge the gap between either sockets 37A and 37B or sockets 37B and 37C connecting load 32B permanently or selectively to the battery 33. By arranging the fuse connections in the manner described above, it is the position of the fuse which dictates which busbar supplies each load.

By implementing a dual busbar fusebox as described above, it is possible to substantially eliminate the quiescent current drain of a vehicle battery over extended periods without use. During such periods, the loads which do not draw a quiescent current are connected to the battery in the usual way through fuse 31B and will not drain it. Loads which would draw a quiescent current are connected to the battery 33 only when the ignition switch 34 is "on" through fuse 31A and isolated at all other times. When ready for normal service, the loads connected to busbar 39 are moved onto busbar 35 by repositioning fuse 31A to its alternative position across sockets 36A and 36B.

Either busbar, or both, may be disconnected from the power source by breaking connection 38A and or 38B as appropriate if, for example, additional isolation is felt necessary.

Referring to Figure 4, in a second embodiment of the invention a fusebox 40 is provided comprising fuse sockets 41A, 41B, 41C, 42A, 42B, 42C, 43A, 43B, 44A, 44B, 45A, and 45B, busbars 46 and 47, fuses 48A, 48B, 49A, 49B, and 49C.

The fusebox 40 is a modified version of the fusebox 30 shown in Figure 3 above. The remainder of the circuit for this embodiment is substantially the same as the circuit for the first embodiment shown in Figure 3.

Busbar 46 is in permanent electrical communication with the vehicle battery (not shown) and busbar 47 is in selective electrical communication with the same battery through the vehicle ignition switch (not shown). Sockets 41A, 42A, 43A, 44A and 45A are connected to busbar 46 and sockets 41C and 42C are connected to busbar 47. Sockets 41B, 42B, 43B, 44B and 45B feed electrical loads (not shown). The fusebox 40 is constructed to use fuses of the type described above with reference to Figure 2. The female sockets for fuse 48A are arranged such that the fuse can only bridge across sockets 41A and 41B permanently connecting the load to the battery through the busbar 46 or across sockets 41B and 41C, connecting the load to the battery through the selective busbar 47 and the ignition switch (not shown).It is not possible to bridge both gaps because the sockets, including socket 41B which is common to both positions of fuse 48A, can only accept one male terminal at a time. In like fashion, there is a mutually exclusive arrangement for fuse 48B to bridge the gap between either sockets 42A and 42B or sockets 42B and 42C connecting its load (not shown) permanently or selectively to the vehicle battery. Sockets 43B, 44B and 45B are connected to individual electrical loads (not shown). The sockets for fuse 49A are arranged such that the fuse can only bridge sockets 43A and 43B, connecting the load supplied by that fuse to busbar 46. In like manner, the sockets for fuses 49B and 49C are arranged such that the fuses can only bridge sockets 44A to 44B and 45A to 45B respectively, connecting their loads (not shown) to busbar 46.During extending periods without use the loads which do not draw a quiescent current are connected to the battery in the usual way through fuses 49A, 49B and 49C and will not drain it. These loads (not shown) would typically include subsystems controlled by switches providing isolation when not in use, such as lights and horn. Loads which would draw a quiescent current, such as a clock, are connected to the battery only when the ignition switch is "on" through busbar 47 and are isolated at all other times.

When ready for normal service, the loads connected to busbar 47 are moved onto busbar 46 by repositioning fuses 48A and 48B to their alternative positions across sockets 41A to 41B and 42A to 42B respectively. In this manner it is possible to provide a fusebox where only the loads which need to be isolated when the vehicle is not in use are provided with a dual socket arrangement as described above.

It will be appreciated by the man skilled in the art that there is ample scope within the bounds of the invention described herein to provide a fusebox with arrangements for connecting all or selected loads to the battery either permanently or selectively. It will be further appreciated that the scope of the invention is not limited by the number or type of fuses chosen, the socket sharing arrangements or the power supply used.

It will also be appreciated by the man skilled in the art that the implementation of a quiescent current reduction system, as disclosed herein, will improve the process of vehicle manufacture. Using such a system, the vehicle manufacturer can produce a vehicle for which the included subsystems can be fully tested with substantially reduced risk of compromising their future integrity by partial disassembly after test.

Claims (8)

1. A vehicle electrical system comprising power supply means, at least one subsystem, first connecting means for providing permanent electrical connection between said at least one subsystem and the power supply means and second connecting means for providing selective electrical connection between said at least one subsystem and the power supply means wherein the connecting means are arranged such that connection of the power supply to said at least one subsystem through one of said connecting means precludes connection of the power supply to said at least one subsystem through the other of said connecting means.

2. An electrical system according to claim 1 wherein the second connecting means includes switch means for providing said selective electrical connection.

3. An electrical system according to claim 2 wherein the switch means comprises a vehicle ignition switch.

4. An electrical system according to any foregoing claim wherein one of the connecting means includes a pair of contacts which can be connected together by means of a removable connecting member.

5. An electrical system according to claim 4 wherein both of the connecting means include a pair of contacts which can be connected together by means of a removable connecting member.

6. An electrical system according to claim 5 including one contact which is common to both pairs such that connection of one of said connecting means precludes connection of the other of said connecting means.

7. An electrical system according to one of claims 4 to 6 wherein the or each removable connecting member comprises a fuse.

8. An electrical system substantially as described herein with reference to Figures 2 and 3 or Figures 2 and 4 of the accompanying drawings.