AU1480300A

AU1480300A - Monitoring the performance of a vehicle

Info

Publication number: AU1480300A
Application number: AU14803/00A
Authority: AU
Inventors: Wilhelm Eugene Ekermans
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-12-11
Filing date: 1999-12-10
Publication date: 2000-06-26
Also published as: EP1155291A1; WO2000034749A1

Description

WO 00/34749 PCT/ZA99/00135 MONITORING THE PERFORMANCE OF A VEHICLE FIELD OF THE INVENTION THIS INVENTION relates to the monitoring of the performance of a vehicle. It also relates to fuel level indicators. BACKGROUND TO THE INVENTION Fuel is a major day-to-day expense in any business which uses vehicles. This is particularly true of trucking operations. Failure properly to account for fuel can impact severely on the profitability of the business. Spilling of fuel at the time of filling, fuel spilling over due to the temperature increase which occurs when the fuel is transferred from a storage tank to the truck's tank, inaccurate recording in the "diesel book" and theft all contribute to fuel losses. Insofar as theft is concerned, it is well known that fuel is often stolen from trucks after they leave their depot. This is particularly true on long hauls where road conditions, traffic volumes and detours can greatly influence the quantity of fuel actually consumed for a journey. Because wide variations in consumption are common place from journey to journey, and from driver to driver on the same route, it is difficult to tell if a quantity of fuel has been taken from the fuel tank. Various devices are available which monitor parameters such as speed, acceleration and deceleration of a vehicle, the time for which the engine is on WO 00/34749 PCT/ZA99/00135 -2 and the time for which the engine is off. These provide useful information on the journey undertaken, and on the driver's performance, but do not contribute to solving the problems involved in accounting for fuel. To enable any fuel usage control system to be implemented, it is necessary to know how much fuel has passed through the fuel tank, and how much fuel is in the tank. Hence the present invention also relates to fuel level indicators for fuel tanks. BRIEF DESCRIPTION OF THE INVENTION According to one aspect of the present invention there is provided a system for monitoring the fuel consumption of an engine fitted to a vehicle which comprises indicator means for producing an output signal indicative of the fuel level in a fuel tank, means for providing a signal representing the distance covered by the vehicle, and a processor to which each of said signals is fed and which processes said signals to provide a result indicative of fuel consumption. Said indicator means can include a visual read out from which the volume of fuel in the tank can be read. Said indicator means can also include a visual read out which can be re-set to zero and which indicates the volume of fuel taken from the tank since the last time the read-out was re-set. In one form said indicator means includes a resistance wire in a circuit WO 00/34749 PCT/ZA99/00135 -3 to which a d.c. voltage is applied and a float which rises and falls with fuel level in the fuel tank, movements of said float varying the length of said resistance wire which is in the circuit and hence the current which flows therethrough. In a specific embodiment the indicator means comprises a first resistance wire, a second resistance wire and a conductive element carried by the float, said element bridging between said wires and sliding up and down the wires as the float moves, those portions of the resistance wires that are above the float being in said circuit. The system can further include means for detecting engine speed and producing a signal indicative of engine speed, and means for feeding the signal indicative of engine speed to said processor. It can also include means for detecting transmission speed and producing a signal indicative of transmission speed, and means for feeding the signal indicative of transmission speed to said processor. The system can also include a manually operated means in the vehicle cab for providing a signal to the processor which signal represents a maximum permitted vehicle speed, the processor having means for comparing said signal representing maximum permitted vehicle speed with the signal indicative of transmission speed and producing an output signal if the transmission speed exceeds the maximum permitted speed, and an audio and/or visual warning device in the vehicle cab to which said output signal is fed. According to another aspect of the present invention there is provided WO 00/34749 PCT/ZA99/00135 -4 a fuel level indicator comprising first and second vertically extending resistance wires which are spaced apart horizontally and extend parallel to one another, an electrically conductive link connecting the lower ends of said resistance wires, a d.c. source connected across the upper ends of said resistance wires, a float the vertical position of which varies in dependence on fuel level in the tank, the float including an electrically conductive bridging element which joins said resistance wires, and means for detecting the changes in current which occurs as the float moves vertically and varies the lengths of the resistance wires which are above the float. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings in which: Figure 1 diagrammatically illustrates a monitoring system for a vehicle. Figure 2 is a diagrammatic plan view of a vehicle with the system of Figure 1 fitted; Figure 3 is a side elevation of the vehicle; Figure 4 is a pictorial view of a fuel level indicator; Figure 5 is a circuit diagram; and Figure 6 is a pulse diagram. DETAILED DESCRIPTION OF THE DRAWINGS WO 00/34749 PCT/ZA99/00135 -5 In Figure 1 an internal combustion engine fitted to a vehicle is designated 10, its power output shaft is designated 12, an automatic gearbox, or clutch and manual gearbox, is designated 14, and the drive shaft to the wheels of the vehicle is designated 16. Sensors 18 and 20 detect the rates at which the shafts 12 and 16 respectively are rotating and, of course, detect when they are static. In the case of the shaft 12 this means that the engine 10 is switched-off and in the case of the shaft 16 it means that the vehicle is stationary. Each sensor 18, 20 can comprise a magnet fixed to the shaft and a magnetically operated switch adjacent the shaft. Thus the switch is opened and closed once per revolution of the shaft, and provides a series of pulses at a rate indicative of shaft speed. Alternatively the sensors can switch a current a number of times per revolution e.g. eight times, thereby generating a number of pulses per revolution. In another form the sensor can generate an a.c. signal having a frequency which varies with the rate of rotation. An interface to convert the a.c. signal to a digital signal is required with this latter construction. The signals from the sensors 18 and 20 are fed to a microprocessor 22 along lines 24 and 26 respectively. The fuel tank of the vehicle is shown at 28. Fuel flows from the tank 28 to the engine 10 along the fuel pipe 30. A fuel level indicator is shown at 32, this WO 00/34749 PCT/ZA99/00135 -6 providing a signal indicative of the fuel level in the tank 28. The output signal from the indicator 32 is fed along a line 34 to the microprocessor 22. If the signal from the indicator 32 is analogue, an interface for converting it to digital form is required between the indicator 32 and the microprocessor 22. The vehicle can, to increase its operating range, have a so-called bulk tank 36 which is above the level of the tank 28. The tanks 28 and 36 are interconnected by a feed pipe 38 having a solenoid operated valve 40 in it. The valve 40 is connected to the microprocessor 22 by a line 42. The tank 36 has, at the upper end thereof, a switch 44 which operates to indicate that the tank 36 is full. The switch 44 is connected to the processor 22 by the line 46. It is preferred that both tanks 28, 36 be filled through a filler opening of the tank 36. In this form it must be possible to hold the valve 40 open whilst the tanks are being filled. Alternatively, each tank 28, 36 can have its own filler opening. A positioning system (such as that referred to as the GPS system) can be fitted to the vehicle. The signal receiving antenna is shown at 48 and its connection to the microprocessor 22 is shown at 50. The information stored in the processor 22 can be downloaded onto a mainframe computer or P.C. via a port 52. The processor 22 itself serves mainly to compact the information being received. Average readings over a period of time, WO 00/34749 PCT/ZA99/00135 -7 and not all the data that is received, are stored in the processor 22. It is also possible to connect the port 52 to a unit which can provide the information to the depot by a radio frequency link for "on the road" monitoring. It is also possible to use a magnetically operated unit, or a unit that uses an infrared link, onto which the information is downloaded for subsequent downloading onto the depot's computer. It is also possible to use mobile phone technology to download the information onto the mobile phone network and thence to the depot's computer. The layout on a mechanical horse of the system described above is illustrated in Figures 2 and 3. Neither the fifth wheel nor the trailer that the horse tows is illustrated. Prior to the start of a journey, the tanks 28, 36 are filled. The indicator 32 provides a signal to the processor 22 which eventually indicates that the tank 28 is full. No indication of how much fuel is in the tank 36 is given until the switch 44 closes indicating that the tank 36 is full. To calibrate the tank 28, bearing in mind that tanks are manufactured in many different shapes, it is possible to feed fuel to the tank through a fuel flow meter which constantly measures the volume which has been fed to the tank. The instantaneous volume read from the meter is compared with the reading being given by the fuel level indicator 32. By storing this information in the microprocessor 22, WO 00/34749 PCT/ZA99/00135 -8 all subsequent readings of the indicator 32 represent fuel volume in the tank even if fuel level and fuel volume are not in a linear relationship due to tank shape. Starting of the engine 10 produces a signal from the sensor 18 and this initiates a cycle during which information is stored in the microprocessor 22. Switching-off of the engine 10 terminates the cycle. In the event that the engine remains on continuously for a predetermined time, for example, 20 minutes, expiry of this period terminates one cycle and commences another. This ensures that the data being recorded can be correlated with the location of the vehicle on the road. This assists in analysis because, for example, a set of readings which looks incorrect may be interpreted in an entirely different manner if it is known the vehicle was in a mountain pass. By using the distance travelled and fuel consumed it is possible to provide consumption figures. By storing consumption figures over a period of time, any extraordinary change in the consumption figure can be detected and repairs made and/or remedial action taken. By storing information obtained from the GPS (Global Positioning System) it is possible to detect that the vehicle departed from its normal route. The processor can also detect over-revving of the engine and when the vehicle has been braked hard.

WO 00/34749 PCT/ZA99/00135 -9 By the end of each cycle, the system has recorded sufficient information to determine the time for which the engine was running, kilometres travelled, average RPM, peak RPM, fuel used, cost of the fuel used during the cycle, a cost with other factors included to give a total cost for the cycle, number of stops exceeding a predetermined length of time etc. All these can be calculated in the depot computer from the information downloaded from the microprocessor 22. When the reading from the indicator 32 shows that the tank 28 is almost empty, the valve 40 is opened and fuel flows from the tank 36 to the tank 28. The indicator 32 detects the increasing level in the tank 28. In the event that the tank 28 refills completely, the signal from the indicator 32 which shows that the tank 28 is full causes the valve 40 to be closed. If the reading from the indicator 32 ceases to indicate that the fuel level in the tank 28 is increasing then, after a short delay, the valve 40 is closed. As soon as the tank 36 has been emptied into the tank 28, the processor 22 is able to calculate how much fuel was on the truck when it commenced its journey. The speed of the vehicle, which can be derived from the rate at which pulses are arriving from the sensor 20, can be displayed in the vehicle cab. The display in the cab can include a facility which enables the drive to input a chosen speed to the processor. The speed inputted will normally be the maximum permitted speed in the zone through which the vehicle is travelling. In the event that vehicle speed, as determined by the sensor 20, exceeds the preset speed, the driver is WO 00/34749 PCT/ZA99/00135 -10 given an audio and/or visual warning in the cab. The fact that the warning has been activated is recorded in the processor. It will be understood that by comparing current information with historical, stored information, any significant deviations from the norm can be detected. The indicator 32 can be of any construction which will provide accurate readings of the fuel level in the tank 28. The indicator 32 shown in Figure 4 works on the basis of movement of a float 54 up and down two vertically extending resistive wires 56. The float 54 is guided by a vertical guide rod 58 which passes through a central hole 60 in the float. The wires 56 pass through slots 62 in the float 54. A pair of electrically conductive bridging elements (not shown) are provided inside the float. These elements are of a resiliently flexible metal and the wires 56 pass between the portion of these elements which are in the slots 62. The resilience of the metal, and the positioning of the elements, causes the elements to bear on the wires 56 to make electrical contact but not with sufficient pressure to inhibit up and down movements of the float. The wires 56 extend down from an upper cap 64 to a bottom bar 64 which are held spaced apart by the rod 58. The wires 56 are anchored to the bar 66 and either the bar 66, or an additional wire (not shown) connected between the wires 56, electrically connects the lower ends of the wires 56 to one another.

WO 00/34749 PCT/ZA99/00135 -11 The wires 56 pass through bushes (not shown) which insulate the wires 56 from the cap 64. Fitted to the cap 64 is an enclosure 68 which contains electronics for recording the output of the indicator 32. The line 34 extends from the enclosure 68 to the microprocessor 22. The enclosure 68 has two displays 70 and 72. The display 70 indicates the volume of fuel in the tank. The display 72 indicates the change in volume since the last reading. This indicates how much fuel has been removed from the tank since the last reading. A re-set button (not shown), preferably only accessible to an authorized person, is provided for resetting the display 72 to zero. The indicator 32 is fitted to the tank 28 with the cap 64 in an opening in the top of the tank (see Figure 3). The rod 58, wires 56 and float 54 are inside the tank 28, and the enclosure 68 is visible from outside the tank 28. A constant current is applied to the wires 56 from a constant current source 58 (see Figure 5). As the float 54 rises and falls, the lengths of the wires 56 which are above the bridge constituted by the bridging elements, and which are thus in the circuit, varies. There is consequently a change in resistance which is proportional to the level of the fuel in the tank and therefore proportional to the volume of fuel in the tank. The wires 56 are represented in Figure 5 by the variable resistance symbol. The change in current which results from the application of a constant voltage to a resistance which varies in magnitude is detected by an amplifier 60. The upper ends of the wires 56 are both connected to the constant WO 00/34749 PCT/ZA99/00135 -12 current source 58. The input point of the amplifier is connected to earth via a capacitor 62. A recent trend is not to have the bulk tank 36 but to have a second main tank which lies ahead of, or to the rear of, the tank 28. These tanks are independent of one another and each must have its own a fuel level indicator. For this layout the system must be capable of processing information on two channels so that information can be received from each tank. Whilst the current in channel 1 is on, as shown by the upper line in Figure 6, the current in channel 2 is off, as shown by the lower line in Figure 6. The current in channel 1 passes through the wires 56 of the detector 32 of one tank and the current of channel 2 passes through the wires 56 of the detector 32 of the other tank. Experimental work has shown that pulsing each channel once per second for a period of up to 10 milliseconds gives acceptable results. It is also desirable to switch the current on and allow the circuit to stabilize for say 6 to 10 microseconds seconds before activating the amplifier and using the voltage at point P as the input to the amplifier. This voltage is amplified and fed along line 34 to the microprocessor via an interface which converts it to digital form. It is also possible, instead of feeding a signal to the amplifier and feeding the amplified signal to the microprocessor 22, to generate a frequency signal proportional to the voltage. The frequency signal is read by the microprocessor as WO 00/34749 PCT/ZA99/00135 -13 an indication of float level. The float 54 is within a vertical housing (not shown) to which the fuel has limited access. Slopping of the fuel in the tank thus has a minimal effect on the level in the tube and consequently the float does not bob up and down if the fuel in the tank slops whilst the truck is moving. It is possible to replace the switch 44 of the tank 36 by a detector 32, or to provide a detector 32 in addition to the switch 44.

Claims

1. A system for monitoring the fuel consumption of an engine fitted to a vehicle which comprises indicator means for producing an output signal indicative of the fuel level in a fuel tank, means for providing a signal representing the distance covered by the vehicle, and a processor to which each of said signals is fed and which processes said signals to provide a result indicative of fuel consumption.

2. A system as claimed in claim 1, wherein said indicator means includes a visual read out from which the volume of fuel in the tank can be read.

3. A system as claimed in claim 2, wherein said indicator means also includes a visual read out which can be re-set to zero and which indicates the volume of fuel taken from the tank since the last time the read-out was re-set.

4. A system as claimed in claim 1, 2 or 3, wherein said indicator means includes a resistance wire in a circuit to which a d.c. voltage is applied and a float which rises and falls with fuel level in the fuel tank, movements of said float varying the length of said resistance wire which is in the circuit and hence the current which flows therethrough.

5. A system as claimed in claim 1, 2 or 3, wherein the indicator means comprises a first resistance wire, a second resistance wire and a conductive element WO 00/34749 PCT/ZA99/00135 -15 carried by a float which rises and falls with fuel level in the tank, said element bridging between said wires and sliding up and down the wires as the float moves, those portions of the resistance wires that are above the float being in said circuit, a d.c. voltage in use being applied to the resistance wires and conductive element.

6. A system as claimed in claim 1 or 2 and including means for detecting engine speed and producing a signal indicative of engine speed, and means for feeding the signal indicative of engine speed to said processor.

7. A system as claimed in claim 1 and including means for detecting transmission speed and producing a signal indicative of transmission speed, and means for feeding the signal indicative of transmission speed to said processor.

8. A system as claimed in claim 7 and including manually operated means in the vehicle cab for providing a signal to the processor which signal represents a maximum permitted vehicle speed, the processor having means for comparing said signal representing maximum permitted vehicle speed with the signal indicative of transmission speed and producing an output signal if the transmission speed exceeds the maximum permitted speed, and an audio and/or visual warning device in the vehicle cab to which said output signal is fed.

9. A fuel level indicator comprising first and second vertically extending resistance wires which are spaced apart horizontally and extend parallel to one WO 00/34749 PCT/ZA99/00135 -16 another, an electrically conductive link connecting the lower ends of said resistance wires, a d.c. source connected across the upper ends of said resistance wires, a float the vertical position of which varies in dependence on fuel level in the tank, the float including an electrically conductive bridging element which joins said resistance wires, and means for detecting the changes in current which occurs as the float moves vertically and varies the lengths of the resistance wires which are above the float.