GB2277619A

GB2277619A - A motor vehicle fuel information system

Info

Publication number: GB2277619A
Application number: GB9308832A
Authority: GB
Inventors: Ian Snares; Matthew David Emberson
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1993-04-29
Filing date: 1993-04-29
Publication date: 1994-11-02
Also published as: GB9308832D0

Abstract

A motor vehicle fuel information system comprises a signal processor 3 adapted to receive signals from a fuel sender 1 and at least one other fuel related sensor, 4, 5, 6, 7 and 8. The signal processor 3 which may be a microcontroller containing pre-installed data related to the vehicle in which the system is to be used, is adapted to process all the input signals received to provide two or more coded digital output signals which are fed on to a serial bus 9. The coded digital output signals are intelligible selectively by two or more devices 10, 11, 12 connected to the serial bus 9, such devices being capable of decoding and utilizing the processed fuel related signals. The devices 10, 11, 12 may be, for example, a trip meter, a fuel gauge and an economy mode shift device. <IMAGE>

Description

A Fuel Information System This invention relates to a fuel information system for a motor vehicle and particularly but not exclusively for a motor car.

In the continued development of the motor car to meet ever increasing demands for a higher degree of instrumentation, the size and the complexity of wiring systems have increased. This has tended to impose a limitation on this area of development.

According to the present invention there is provided a motor vehicle fuel information system comprising a fuel tank sender capable of feeding a primary signal dependent upon the quantity of fuel in the tank to a signal processor wherein the signal processor is adapted to receive the primary signal and one or more secondary signals from at least one other fuel related sensor and to process all the input signals received to provide two or more coded digital output signals which are fed on to a serial bus connected to the signal processor and which output signals are intelligible respectively by two or more devices connected to the serial bus and capable of decoding and utilizing the processed fuel related signals.

This invention enables the size and complexity of motor vehicle wiring systems to be reduced thereby removing the above-mentioned development limitation.

The fuel tank sender may be of a type capable of producing a primary signal which is in digital form but is preferably of a type capable of producing a primary signal which is in analog form. Thus, it is preferred that the fuel sender is of known capacitance, hot wire or potentiometer type but the potentiometer type is most preferred, particularly the potentiometer type employing a single track only.

The signal processor may comprise a microprocessor, microcomputer, microcontroller, or discrete logic system but is preferably a microcontroller.

The secondary signal or signals may be in analog or digital form but are preferably in analog form.

The fuel related sensors other than the fuel tank sender which may be employed to provide the secondary signals include accelerometers, inclinometers, engine revolution counters, fuel flow sensors, fuel injection volume sensors, fuel pump rate sensors, time measurers, distance and speed sensors and engine temperature sensors. It will be appreciated that all such other sensors mentioned above are fuel related either in terms of position of the fuel in the tank, its usage or efficiency of usage. Of-these, preferred sensors include speed sensors, time measurers and fuel injection volume sensors. However it is preferred that the other fuel related sensors include at least two sensors, one of which is a time measurer.

The signal processor preferably provides the digital output signals onto a serial bus. The processing of the input signals by the signal processor may involve the use by the processor of data pre-installed into the signal processor and related to the motor vehicle in which the system is to be used.

The coding of the digital output signals may be by any electrical or electronic labelling of the signals which enables the individual signals to be distinguished by the devices destined to utilize the processed fuel related signals and may therefore be by electronically number tagging for example.

The devices capable of decoding and utilizing the processed fuel related signals may include a trip meter, fuel gauge, low fuel level indicator, a device to effect a shift to an economy mode, for example.

It is preferred that the devices are connected to a serial bus and onto which the signal processor outputs the two or more coded digital output signals.

By serial bus we mean to include single or multiple wire serial data conductors and mean to include commercially available serial circuits coded CAN and that coded by the Ford Motor Company as SCP and the like.

The present invention will now be illustrated by way of example with reference to the accompanying drawings in which: Figure 1 is a block diagram of a motor vehicle fuel information system according to this invention: In Figure 1, 1 is a fuel tank sender comprising a single track potentiometer having a take-off point corresponding to the position of a float in the fuel tank. The sender is connected by the electrical cable 2 to the microcontroller 3 which is a chip selected from the 68H C05 series of microcontrollers manufactured by Motorola Ltd and which is adapted to receive the primary analog signal. The microcontroller 3 is also adapted to receive secondary signals from each of the five other fuel related sensors 4, 5, 6, 7 and 8 comprising respectively an accelerometer, an inclinometer, a fuel injection volume sensor, distance sensor and a clock.

Each of the sensors 4, 5, 6, 7 and 8 is connected to the microcontroller 3 by the corresponding electrical cables 41, 1 1 1 6 , 7 , and 81 and thereby feed analog signals respectively to the microcontroller 3. The microcontroller 3 incorporates an analog to digital converter and has data installed related to the motor vehicle in which the system is to be used. The data installed is data relating to the shape and dimensions of the fuel tank fitted to the vehicle including the effect of weight of fuel on tank shape.

Secondary signals redeived by the microcontroller from the accelerometer 4 and inclinometer 5 control the acceptance or rejection by the microcontroller of the primary signals received from the fuel tank sender so that erroneous primary signals are not processed. Secondary signals from the fuel injection volume sensor, distance sensor and clock are processed by the microcontroller together with accepted primary signals using the pre-installed data to produce coded digital output signals which are fed onto the serial bus 9 comprising a multiple wire serial data conductor identified as a Ford Motor Company SCP serial circuit link.

The eight processed fuel related output signals from the microcontroller are coded by electronic number tagging and comprise signals relating to fuel held, distance run, fuel used, miles per gallon, average speed, distance to run, economy shift on/off. The devices 10, 11 and 12 which comprise a fuel gauge, a trip meter and an economy shift device respectively are connected to a serial communications bus 9 by electrical connectors 101, 111, and 121. Each of the devices is capable of identifying, interpreting and utilizing the processed fuel related signals respectively relevant to its operation. While the fuel gauge provides a display of fuel held, the trip meter provides interswitchable displays between distance run, fuel used, miles per gallon, average speed and distance to run. The economy shift device responds to the on/off signals and electronically controls the economy level of motoring accordingly by controlling the maximum fuel flow rate to the engine and the gear changing for automatic gearboxes.

It will be appreciated that feeding all the primary and secondary signals to the signal processor which then feeds a multiplicity of output signals onto a serial bus to which all the required decoding and output signal utilization devices can be connected, permits considerable simplification and size reduction of wiring systems thereby giving a greater freedom of scope for higher degrees of instrumentation. Further, the fuel information system of the present invention enables the positioning of the signal processor where electrical interference may be reduced, for example near to or on the fuel tank sender.

Claims

1. A motor vehicle fuel information system comprising a fuel tank sender capable of feeding a primary signal dependent upon the quantity of fuel in the tank to a signal processor wherein the signal processor is adapted to receive the primary signal and one or more secondary signals from at least one other fuel related sensor and to process all the input signals received to provide two or more coded digital output signals which are fed on to a serial bus connected to the signal processor and which output signals are intelligible respectively by two or more devices connected to the serial bus and capable of decoding and utilizing the processed fuel related signals.

2. A motor vehicle fuel information system as claimed in Claim 1 wherein the primary signal is in analog form.

3. A motor vehicle fuel information system as claimed in Claim 2 wherein the fuel tank sender is of potentiometer type employing a single track only.

4. A motor vehicle fuel information system as claimed in any one of the preceding claims wherein the signal processor is a microcontroller.

5. A motor vehicle fuel information system as claimed in any one of the preceding claims wherein the secondary signals are in analog form.

6. A motor vehicle fuel information system as claimed in any one of the preceding claims wherein the other fuel related sensors include at least two, one of which is a time measurer.

7. A motor vehicle fuel information system as claimed in any one of the preceding claims wherein the signal processor contains pre-installed data related to the motor vehicle in which the system is to be used.

8. A motor vehicle fuel information system as claimed in any one of the preceding claims wherein the digital output signals are coded by electronically number tagging.

9. A motor vehicle fuel information system as claimed in any one of the preceding claims wherein the two or more devices capable of decoding and utilizing the processed fuel related signals are selected from a trip meter, a fuel gauge, a low fuel level indicator and an economy mode shift device.

10. A motor vehicle fuel information system as claimed in any one of the preceding claims substantially as described herein with reference to the accompanying drawing.