GB2167885A - Vehicle wiring signalling systems - Google Patents

Abstract

In a vehicle writing system tone bursts are used as a signalling format to control remote functions from a central controller. <IMAGE>

Description

SPECIFICATION Vehicle wiring signalling systems The present invention relates to vehicle wiring systems and more particularly to signalling systems for use in vehicle wiring systems.

Known designs of vehicle wiring systems involve a complex loom of wires specifically designed to fit a particular model of car. The loom comprises a plurality of wires of various lengths which are terminated at one end with switches normally on the dashboard of the vehicle and at the other end to the desired function to be controlled e.g. headlamps, sidelights, windscreen wiper motors etc.

Recently attempts have been made to simplify the wiring looms and in a known system a ring main approach has been used wherein a multi-core cable (possibly of the flat type) has been "run" round the vehicle and the various functions connected to the multi-core cable.

Additionally in our copending application (84 27637) a wiring system is disclosed in which the vehicle is separated into a number of discrete areas and in which each area is provided with a receiver which receives signals from a central control and in which the receiver is operative to switch on or off functions in that area in response to selected signals.

In vehicles the wiring system has to switch large currents to resistive loads and thus switching can create electrical interference within the loom. In the conventional loom this does not matter (except for radio interference) because each load is directly switched. However in the simplified loom arrangement where signalling is employed this can be a problem.

In a known signalling system of the ring main type digital signals are transmitted on one or more of the wires of the ring main and these are received at all functional locations in the car. Only those functions which are connected to the appropriate wires on which signals are transmitted will respond. If a large number of functions are required then a coded digital signalling system may be used but such a system may be susceptible to interference from the switching of heavy electrical loads.

Such interference can be dangerous if for example an indicator lamp is turned on by mistake even if it is turned off again after a short period of time.

It is an object of the present invention to provide a vehicle wiring signalling system for switching on and off functions in a vehicle which is relatively free from problems of interference and which thereby is reliable in controlling the electrical functions.

According to the present invention there is provided a vehicle wiring signalling system for a vehicle having a central controller and a plurality of remote functions which are controllable by the central controller over a signalling path in which tones are used as the signalling format.

In a preferred embodiment bursts of tones of a single frequency are output from the central controller in selected time slots within a defined frame period to select desired functions.

In a further preferred embodiment multi-frequency tones are used and are output from the central controller in selected time slots within a defined frame period to select the desired functions.

Preferably clock synchronisation tone bursts of a different frequency are also transmitted in one or more time slots.

The central controller preferably comprises a micropressor or multiplexor which determines the tones to be transmitted and the time periods within which such tones are to be transmitted.

Preferably the vehicle wiring system includes a plurality of transmitters connected to the central controller for output of the tones and a plurality of receivers connected to the transmitters via a wiring loom and being at remote locations in the vehicle for receipt of the tones, the receivers interfacing between the wiring loom and one or more functions required for operation of the vehicle.

Embodiments of the present invention will now be described, by way of example with reference to the accompanying drawings, in which: Figure 1 shows a diagrammatic plan view of a car having a wiring system suitable for utilising the tone frequency signalling according to the present invention; Figure 2 shows in block diagrammatic form the circuitry associated with the wiring system of Figure 1; Figure 3 shows waveforms of a typical tone burst format; Figure 4 shows an alternative waveform tone burst format; Figure 5 shows a typical transmitter for transmitting tone bursts according to the present invention; and Figure 6 shows a typical receiver for receiving and decoding tone bursts transmitted by the transmitter of Figure 5.

The invention relating to the use of tones for signalling within the wiring system of a vehicle will now be described with reference to the wiring system shown in Figure 1 which is the subject of our copending British Patent Application No. 84 27637. Tones may be used on other wiring systems where a modified loom is used for example on the ring main wiring system in which a number of functions are operable from a ring main wiring loom, the tone signals being transmitted to all points on the ring main but actuating only those functions which are responsive to particular tones or particular time periods.

With reference now to Figure 1, a vehicle, in this case a car, 10 is shown in outline plan view. The shape of the vehicle shown is exemplary, the invention being equally applicable to most types of road vehicles e.g. light commercial vehicles (vans) estate cars, coaches etc.

The wiring system comprises a number of outstations 1 to 9 situated at selected positions in the car for the control of functions which are local to those positions as follows: Outstations 1, 2, 3 and 4 are located respectively in the front nearside and offside wings and the rear nearside and offside wings for control of the lighting etc functions.

Outstations 5, 6, 7 and 8 are located respectively in the front nearside and offside and rear nearside and offside doors.

Outstation 9 may be located in the boot of the car as shown for control of trailer lighting functions. Alternatively it could be located on the trailer, allowing as will be understood hereinafter a simpler plug and socket trailer connection.

By separating the car into a number of discrete areas it is possible to design a standard outstation capable of controlling N functions.

The value N may be chosen to suit the complexity of control required. In an exemplary embodiment the value of N is chosen to be 16. Thus up to sixteen functions can be controlled at any outstation. Examples of the type of functions which may be controlled are as follows: NEARSIDE FRONT (PASSENGERS) DOOR a) Electric window motor down b) Electric window motor up c) Passenger door mirror up d) Passenger door mirror down e) Passenger door mirror in f) Passenger door mirror out g) Heated drivers mirror h) Central door lock open i) Central door lock close NEARSIDE FRONT WING a) Sidelight b) Flashing indicator c) Dipped beam headlamp d) Main beam headlamp e) Headlamp motor up (for concealed headlamps) f) Headlamp motor down (for concealed headiamps) g) Headlamp wash/wipe Each controlled function at each location will normally be switched on and off using a relay as described hereinafter with reference to Figure 6 such that the power required in the control wire or wires is kept to a minimum. The relay may be of the mechanical or electronic type.

The control system for operation of each relay will now be described with reference to Figure 2.

The control switches on the dashboard which are actuated by the driver or passenger are represented by box 20 which is connected to a matrix or discrete switch arrangement 22.

The matrix 22 can be a standard 4 X 4 or a standard 4 X 5 arrangement giving an allowable sixteen or twenty dashboard functions. A larger matrix could be used if required.

The output of matrix 22 can for example be digital on 5 or 6 wires 24 and the output wires are connected to a central processor 26 which identifies the dashboard switch which has been actuated. Within the microprocessor is a program preferably stored on for example a programmable read only memory, which on receipt of an address on wires 24 can output instructions on appropriate "looms" L1 to L9 to actuate selected power switches PI to P9 in receiver stations 1 to 9 via receivers R1 to R9.

As described hereinbefore each "loom" L1 to L9 may comprise up to four wires. These may be configured as follows.

ONE WIRE SYSTEM. Single wire carries signalling information and 12 volts D.C. power-earth return via car chassis.

TWO WIRE SYSTEM. Signalling carried by both wires (out and return)-12 volt D.C. carried by one of the wires -earth return via car chassis.

THREE WIRE SYSTEM (i). Signalling carried by two of the wires (out and return) 12 volts D.C. carried by separate wire-earth return via car chassis.

THREE WIRE SYSTEM (ii). Signal out carried by one wire, 12 volts D.C. carried by one wire, earth and signal return carried by third wire.

FOUR WIRE SYSTEM. Signalling carried by two of the wires (out and return) 12 volt D.C.

carried by a separate wire. Earth return via fourth wire.

The first system (one wire) may suffer from interference problems dependent on the type of signalling format used to operate the functions. The surge of current present when a large load e.g. headlamp is switched on may cause the signals to be distorted especially where there is a long length of cable run from the central control to the outstation.

The two or three wire systems are preferred since these give better interference rejection and for longer vehicles or for greater security the four wire system may be selected.

In the system described in Figures 5 and 6 two wires are used for signalling and the 12 volt D.C. power is supplied to relay contacts via a separate wire. The earth return may be either through the vehicle chassis or by a separate wire.

With reference now to Figures 3 and 4 two alternative signalling formats are shown. In Figure 3 bursts of tone of a single frequency, preferably in the audio range, are transmitted in selected time slots T1 to T16. The presence of a tone is an instruction for a function at a remote location to be made operative e.g. for a side light to be switched on.

With reference to Figure 3 it may be seen that functions F1 and F2 are "ON" function 3 is "OFF" and function 4 is "ON". Functions F5 to F15 are not shown for ease of drawing and function F16 is "ON". By "ON" or "OFF" it is meant that the function is switched "ON" on receipt of the first (or possibly nth) tone burst and maintained in an "ON" condition providing tone bursts are received in the associated tone slot at predetermined internals. If n associated time slots pass without receipt of a tone burst (n can be equal to one) then the function is switched OFF.Alternatively it can be arranged that the receipt of a tone in a time slot can be latched by the receiver and the function maintained until a further toneburst is received for example of different frequency in the same time slot or in a different time slot.

With reference to Figure 4, clock signals comprising tone bursts of different frequency are interspersed with the function control tone bursts to maintain the synchronisation of transmitter and receiver.

With reference to Figure 5 a transmitter 50 suitable for connection to the central processor 26 of Figure 2 is shown. The transmitter comprises a data tone generator 52 and a clock tone generator 54 the outputs 56, 58 of which are fed to switches 60, 61 which are opened for selected time slots to allow the tone bursts to be fed to an output line driver 62 to feed line output terminals 64, 66. The time intervals during which the tone bursts are switched to the line are determined by a decoder timing circuit 68 which receives control information on lines 70 from the central processor, and by a data out enable line 72.

These control signals open gates 74, or 76 to respectively enable switches 60, 62 to switch data or clock tones to the line. Stable voltages Va, Vb may be generated from the vehicle battery supply by known means. A variable reset circuit 69 is included to set the number of steps for the control signals. Thus preferably sixteen steps are output to control sixteen functions but thirty two steps can be selected by alteration of the setting of reset circuit 69. In the time interval between pulses a voltage output level is output by circuits 63, 65.

With reference now to Figure 6, a receiver is shown which is suitable to receive and decode the tone bursts transmitted by the transmitter of Figure 5. The tone bursts are received at terminals 80, 82 and fed to a data detector circuit 84 and a clock detect circuit 86. A clock regenerator circuit 88 sharpens the clock pulse for use in controlling the synchronism of the receiver. Detected data pulses are output on line 90 and are fed to latches 92, 94 which are controlled by output from a decoder 96 which is clocked by the regenerated clock pulses. The outputs of latches 90, 92 control relays RL 1 to RL 16 via relay drivers 96, 98. The contacts (not shown) of relays RL1 to RL16 may be used to control desired functions.

A reset circuit 100 is included which is controlled by the clock pulses and which may be used to reset the latches 92, 94 to their nonoperative condition in the event of failure of the transmitted clock pulse, thus not allowing any operation or continued operation of any function which might be dangerous.

Instead of a single frequency being used for data transmission a multi-frequency tone may be used for greater selectivity especially in ring main types of wiring systems. The transmitter and receiver circuitry is modified to include additional gating to introduce the additional tone or tones to produce the multi-frequency signal and frequency selective detection in the receiver to decode the additional frequency of tone.

Terminals 102 and 104 are provided to operate functions from 17 up to 32, etc. when variable reset circuit 69 is set to give a tone sequence for the control of more than sixteen functions.

Claims (1)

1. A vehicle wiring signalling system for a vehicle having a central controller and a plurality of remote functions which are controllable by the central controller over a signal path, in which tones are used as signalling format.

2. A vehicle wiring signalling system as claimed in Claim 1, in which burst of tones of single frequency are output from a central controller in selected time slots within a defined frame period to select desired functions.

3. A vehicle wiring signalling system as claimed in Claim 1, in which multi-frequency tones are used which are output from the central controller in selected time slots within a defined frame period to select desired functions.

4. A vehicle wiring signalling system as claimed in any preceding claim, in which clock synchronising tone bursts of a different frequency are transmitted in one or more of the time slots.

5. A vehicle wiring signalling system as claimed in any preceding claim, in which the central controller comprises a microprocessor or multiplexor which determines the tones to be transmitted and the time periods within which such tones are to be transmitted.

6. A vehicle wiring signalling system as claimed in any preceding claim, in which the vehicle wiring system includes a plurality of transmitters connected to the central controller for output of the tones and a plurality of receivers connected to the transmitters via the wiring loom and being at remote locations in the vehicle for receipt of the tones, the receivers interfacing between the wiring loom and one or more functions required for operation of the vehicle.

11. A vehicle wiring signalling system con structed substantially as herein described with reference to the accompanying drawings.