GB2531024A

GB2531024A - Fuel delivery control

Info

Publication number: GB2531024A
Application number: GB1417730.7A
Authority: GB
Inventors: Lam Thomas
Original assignee: BTRACK SOLUTIONS Ltd
Current assignee: BTRACK SOLUTIONS Ltd
Priority date: 2014-10-07
Filing date: 2014-10-07
Publication date: 2016-04-13
Also published as: GB201417730D0

Abstract

A method of controlling, in real-time, a supply of a second fuel to a combustion engine supplied with a first fuel is described. The method comprises the steps of: identifying a magnitude of a first operational variable, and adjusting a pre-determined base flow rate of the second fuel with reference to a look-up table. The look up table provides a percentage degree of adjustment for an identified magnitude of the first operational variable to provide a modified base flow rate of the second fuel. The application of such as method is performed by the controller 102. The first fuel may be diesel and second may be liquefied petroleum gas (LPG). The second fuel may be delivered via the air intake manifold 106. A graphical user interface (GUI) 107 such as a touch screen may also be provided to the user to illustrate the status of the engine. The fuel delivery system 101 may be retrofitted to a diesel powered engine or vehicle.

Description

FUEL DELIVERY CONTROL

Reid of the Invention The present invention relates to fuel delivery control, in particular to a method of controlling, and a controller operable to control, the delivery of a secondary fuel (such as liquefied petroleum gas (LPG), compressed natural gas (CNG) or liquefied natural gas (LNG)) into a diesel engine of a vehicle.

Backqround of the Invention Modern trucks and lorries, such as those used in the commercial haulage industry, are mostly powered by diesel engines, which utilise heat from compression to initiate burning of the diesel. Diesel, which is a hydrocarbon fuel, self-ignites towards the centre of the combustion chamber when under high compression, and burns outwardly at a relatively slow rate. Complete and efficient combustion relies on an optimal air-fuel ratio. In areas within the combustion chamber with conditions of insufficient oxygen, carbon monoxide (CO) will be formed during combustion. In areas of the combustion chamber with conditions of insufficient fuel, NOx (mono-nitrogen oxides nitric oxide (NO) and nitrogen dioxide (NO2)) will be formed during combustion. Incomplete combustion, such as may occur in areas of the combustion chamber with conditions of lower temperature, reduces fuel efficiency and increases the level of diesel exhaust, which contains harmful particulate matter (PM).

It is known to add a secondary gaseous fuel, (such as liquefied petroleum gas (LPG), compressed natural gas (CNG) or liquefied natural gas (LNG)) into a standard diesel engine of a vehicle, to enhance combustion. The secondary fuel has a higher research octane number (RON) than diesel. Using a relatively small amount of the secondary fuel in combination with the diesel fuel leads to a faster flame speed, allowing more of the diesel to be fully combusted. The use of the secondary fuel in the diesel injection engine also enables the injection of the diesel to begin sooner, resulting in a longer period available for the diesel fuel to be combusted.

For a given amount of energy required by a diesel engine, the use of the secondary fuel reduces the amount of diesel required due to the improvement in combustion. The improved combustion beneficially reduces the formation of CO, NOx and PM.

However, a problem exists in delivering an optimal amount of the secondary fuel into the diesel engine. Too small an amount will not cause any, and therefore not the desired, effect, and diminishing returns and potential engine damage is found as the amount increases above the optimal ratio to the diesel fuel. It is desirable to ensure that the optimal amount of the secondary fuel is delivered to the diesel engine during the operational cycle.

This will enhance the efficiency and operation of the diesel engine, and overcome problems experienced with dual fuel engines that start up using diesel and then switch to consuming the secondary fuel only or dual fuel simultaneously. such as damaged exhaust valves and, in some cases, damaged pistons due to excessive heat.

Summary of the Invention

According to a first aspect there is provided a method of controlling, in real-time, a supply of a second fuel to a combustion engine supplied with a first fuel, said method comprising the steps of: identifying a magnitude of a first operational variable, and adjusting a pre-deterrnined base flow rate of said second fuel with reference to a look-up table which provides a percentage degree of adjustment for an identified magnitude of said first operational variable to provide a modified base flow rate of said second fuel.

In an embodiment, the second fuel is supplied to the air intake manifold of the combustion engine.

In an embodiment, the pre-determnined base flow rate of the second fuel is one of: a fixed amount, a percentage of the first fuel flow rate.

In an embodiment, the second fuel has a higher research octane number (RON) than the first fuel. In an embodiment, the first fuel is diesel and the second fuel is one of: liquefied petrdleum gas (LPG), compressed natural gas (CNG), liquefied natural gas (LNG).

In an embodiment, the pre-determined base flow rate of the second fuel is determined with reference to one of: first fuel flow rate, mass airflow rate.

In an embodiment, the first operational variable is throttle position.

In an embodiment, the method further comprises the steps of: identifying a magnitude of a second operational variable, and adjusting said modified base flow rate of said second fuel with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said second operational variable to provide a second-stage modified base flow rate of said second fuel.

In an embodiment, the second operational variable is engine load.

In an embodiment, the method further comprises the steps of: identifying a magnitude of a third operational variable, and adjusting said second-stage modified base flow rate of said second fuel with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said third operational variaNe to provide a third-stage modified base flow rate of said second fuel.

In an embodiment, the third operational variable is coolant temperature.

In an embodiment, the method further comprises the steps of: identifying a magnitude of a fourth operational variable, and adjusting said third-stage modified base flow rate of said second fue' with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said third operational variable to provide a fourth-stage modified base flow rate of said second fuel.

In an embodiment, the fourth operational variable is revolutions-per-minute (RPM).

In an embodiment, the method further comprises the steps of: identifying a magnitude of a fifth operational variable, and adjusting said fourth-stage modified base flow rate of said second fuel with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said third operational variable to provide a fifth-stage modified base flow rate of said second fuel.

In an embodiment, the fifth operational variable is mass airflow rate.

According to a second aspect there is provided a computer-readable medium having computer-readable instructions executable by a computer, such that said computer performs the method of the first aspect.

According to a third aspect there is provided a controller for controlling, in real time, a supply of a second fuel to a combustion engine supplied with a first fuel, said controller operable to adjust a pre-determined base flow rate of a second fuel supplied to a combustion engine supplied with a first fuel with reference to an adjustment table which provides a percentage degree of adjustment for an identified magnitude of an operational variable to provide a modified base flow rate of said second fuel.

According to a fourth aspect there is provided a controller operable to perform the method of the first aspect.

According to a fifth aspect there is provided a vehicle comprising a controller according to the fourth aspect.

According to a sixth aspect there is provided a fuel delivery system comprising a controller according to the fourth aspect.

In an embodiment, the second fuel is delivered into the air intake of the combustion engine.

According to a seventh aspect there is provided a vehide comprising a fuel delivery system according to the sixth aspect.

In an embodiment, the controller is in communication with a graphical user interface device.

Different aspects and embodiments of the invention may be used separately or together.

Further particular and preferred aspects of the present invention are set out in the accompanying independent arid dependent claims. Features of the dependent claims may be combined with the features of the independent claims as appropriate, and in combination other than those explicitly set out in the claims.

Brief Descriytion of the Drawings The present invention will now be more particularly described, with reference to the accompanying drawings, in which: Figure 1 is a schematic of features of a fuel delivery system embodying the present invention; Figure 2 shows a main menu screen of a graphical user interface in communication with a controller of the fuel delivery system; Figure 3 shows a calibration screen of the graphical user interface; Figure 4 shows a calibration options screen of the graphical user interface; Figure 5 shows a sensor calibration screen of the graphical user interface; Figure 6 shows an adjustment screen for the base flow rate of the second fuel; Figure 7 shows an adjustment screen for a first variable; Figure 8 shows an adjustment screen for a second variable; Figure 9 shows an operating display screen of the graphical user interface; and Figure 10 illustrates steps in a method of controlling, in real-time, a supply of a second fuel to a combustion engine supplied with a first fue', according to the present invention

Description

A schematic of a fuel delivery system 101 embodying the present invention is shown in Figure 1. The fuel delivery system 101 comprises a controller 102 for controlling, in real time, a supply of a second fuel to a combustion engine supplied with a first fuel, the controller 102 operable to adjust a pre-determined base flow rate of a second fuel supplied to a combustion engine supplied with a first fuel with reference to a look-up table which provides a percentage degree of adjustment for an identified magnitude of an operational variable to provide a modified base flow rate of the second fuel.

In an embodiment, the second fuel has a higher research octane number (RON) than said first fuel.

The fuel delivery system 101 and the controller 102 will now be described in more detail with reference to a specific embodiment in which the first fuel is diesel and the second fuel is liquefied petroleum gas (LPG).

The fuel delivery system 101 further comprises a fuel storage tank 103 for storing LPG, a vaporiser 104 for reducing the pressure of LPG gas received from the storage tank 103, fuel injection apparatus 105 comprising one or more injectors for supplying LPG received from the vaporiser 104 to the air intake manifold 106 of a diesel-powered combustion engine, and a graphical user interface device 107. The controller 102 is in two-way communication with a graphical user interface device 107.

The storage tank 103 has a filling port and an outlet port, and is provided with a fuel level sensor and an outlet port shut-off device, in the form of a solenoid valve, for selectively stopping the delivery of LPG to the vaporiser 104. The controller 102 is in communication with the storage tank 103. The storage tank 103 is connected to the vaporiser 104 via a safety shut-off device 108, also in the form of a solenoid valve, which provides a back-up safety function in the event of malfunction of the outlet port shut-off device of the storage tank 103. The controller 102 is in communication with the storage tank 103, and with the safety shut-off device 108 between the storage tank 103 and the vaporiser 104.

The controller 102 receives inputs from a temperature sensor 109 and from a pressure sensor 110, located between the vaporiser 104 and the fuel injection apparatus 105 to sense the temperature and pressure of the LPG flow. The controller 102 is in communication with the fuel injection apparatus 105 and functions to control the amount of LPG supplied to the diesel-powered combustion engine.

In an embodiment, the fue' delivery system 101 is provided as retrofit apparatus for a diesel-powered engine or vehicle, for example a car, truck, lorry, bus, train, marine engine, generator or any engine that uses diesel.

In a retrofit arrangement, the LPG storage tank 103 is mounted to the vehicle chassis, by use of any suitable mechanical fixing means such as bracketry. The vaporiser 104 is arranged to receiving circulating engine radiator water to prevent it from freezing. The controller 102 is mounted beneath the vehicle dashboard and the graphical user interface device 107 is mounted within the cabin of the vehicle, preferably at a location within sight and easy reach of a driver.

As will be described in further detail, the present invention provides a method of controlling, in real-time, a supply of a second fuel to a combustion engine supplied with a first fuel, the method comprising the steps of: identifying a magnitude of a first operational variable, and adjusting a pre-determined base flow rate of the second fuel with reference to a look-up table which provides a percentage degree of adjustment for an identified magnitude of said first operational variable to provide a modified base flow rate of said second fuel.

Figure 2 shows a main menu screen 201 of the graphical user interface 107 of fuel delivery system 101.

The main menu screen 201 displays user-selectable CALIBRATE' and START' options 202, 203. Preferably, the graphical user interface 107 comprises a touchscreen display device.

In an embodiment, selecting CALIBRATE' takes the user to a secure log-in screen that prompts the user to input a correct password, code or pin number to obtain access to a calibration screen 301 of the graphical user interface 107 of fuel delivery system 101, as shown in Figure 3.

The calibration screen 301 displays a list 302 of user-selectable tables. The table list 302 includes an option for BASE FLOW RATE' 303 and options for one or more operational variables, such as VARIABLE l'option 304 and VARIABLE 2' option 305. The calibration screen 301 also displays user-selectable SENSORS' and CONFIGS' options 306, 307.

Selection of the SENSORS' option 306 takes a user to a screen that lists readings/values for sensors/variables of the fuel delivery system. The readings/values may be obtained or derived from a sensor or from the vehicle CANBUS system.

Selection of the CONFIGS' option 307 takes a user to a calibration options screen 401 as shown in Figure 4.

The calibration screen 401 displays a list 402 of user-selectable sensor calibration options. The options list 402 includes an option for LPG TEMPERATURE' 403, LPG TEMPERATURE' 404, INJECTOR' 405 and TANK LEVEL' 406. It is to be appreciated that other options may be displayed.

Selection of one of the sensor calibration options takes the user to a sensor calibration screen.

Figure 5 shows a sensor calibration screen 501 for the temperature sensor for the option LPG TEMPERATURE' 403 shown in Figure 4.

During the calibration routine, the vehicle is tested on a rolling road, which simulations driving, and a sensor input taken for the selected sensor.

The temperature sensor of this illustrated example can be calibrated against a detected voltage.

A calibration table 502 is displayed, and user-selectable DECREASE' and INCREASE' options 503, 504 are provided for use during the calibration. User-selectable PREVIOUS' and NEXT' table navigation options 505, 506 are provided to allow scrolling through the array of cells of the calibration table 502.

The calibration screen 501 also displays user-selectable TABLES' and MAIN' screen navigation options 507, 508 and user-selectable SAVE' and LOAD' data management options 509, 510. The controller 102 of the fuel delivery system 101 comprises non-volatile memory for persistent data storage.

Figure 6 shows an adjustment screen 601 for the BASE FLOW RATE' 303 table option of Figure 3.

In an embodiment, the base flow rate for the second fuel is determined with reference to flow rate of the first fuel.

Data is compiled for a base flow rate table 602, which associates a second fuel base flow rate value F21, F22. F23 F24 etc. for an associated first fuel flow rate Fl1, Fl2, Fl3 Fl1 etc. The second fuel flow base flow rate value F21. F22. F23 F24 indicates an optimal flow rate of LPG to be supplied to the diesel-powered combustion engine for a particular diesel flow rate Fl1, Fl2. Fl Fl1 etc. The second fuel base flow rate value associated with a particular first fuel flow rate may be a fixed amount of the second fuel, for example 10 cc/mm. Alternatively, the second fuel base flow rate value associated with a particular first fuel flow value may be a percentage of the first fuel flow rate, for example 10%. As a further alternative, the second fuel base flow rate value associated with a particular first fuel flow rate may be a combination of a fixed amount of the second fuel and a percentage of the first fuel flow rate, for example 5 cc/mm plus 1%.

The base flow rate table 602 may have any suitable number of cells. The values of the first fuel flow rate may be of any suitable magnitude and may increase with regular increments or irregular intervals.

The second fuel base flow rate value F21. F22. P23 F24 etc. for any particular associated first fuel flow rate Fl1, Fl2, Fl3 Fl4 etc. is adjustable and user-selectable DECREASE' and INCREASE' options 603, 604 are provided for this purpose. User-selectable PREVIOUS' and NEXT' table navigation options 605, 606 are provided to allow scrolling through the array of cells of the base flow rate

table 602.

The adjustment screen 602 also displays user-selectable TABLES' and MAIN' screen navigation options 607, 608 and user-selectable SAVE' and LOAD' data management options 609, 610.

In an embodiment, a single second fuel base flow rate value is used, for example 10%, for all first fuel flow values. In this case, the adjustment table may have only a single cell or column.

In an alternative embodiment, a base flow rate for the second fuel is determined with reference to mass airflow rate. A single second fuel base flow rate value, or multiple second fuel base flow rate values, may be used as described above. The base flow rate for the second fuel may be a fixed amount, a percentage or a combination as also described above.

As will now be described, the second fuel base flow rate value, indicating an optimal flow rate of second fuel to be supplied to the diesel-powered combustion engine may then be modified with reference to one or more further look-up

tables.

Figure 7 shows an adjustment table screen 701 of the graphical user interface 107 of fuel delivery system 101 for the VARIABLE 1' 304 table option of Figure 3.

Data is compiled for a variable look-up table 702 which associates an output value X0, Y0, Z0 etc. for an associated input value X1, Y1, Z1 etc. of the operational variable. The output value X0. Y0, Z0 etc. of the variable look-up table 702 provides a percentage degree of adjustment of the second fuel base flow rate value F21, F22, F23 P24 etc. of the base flow rate table 602 of Figure 6.

The output value X0, Y0, Z0 etc. of the variable look-up table 702 is multiplied by the second fuel base flow rate value F21, F22. P23 F24 etc. to provide a modified base flow rate of the second fuel.

An output value of 100% would result in no adjustment being made to the base flow rate of the second fuel, an output value of 0% would result in the flow of second fuel being cut, an output value of between 0% and 100% decreases the base flow rate of the second fuel and an output value of over 100% increases the base flow rate of the second fuel.

The operational variable look-up table 702 may have any suitable number of cells, for example the same, less or more than the base flow rate table 602.

The input values X1, Y1, Z1 etc. of the operational variable may be of any suitable magnitude, in terms of a percentage or a unit of measurement, and may increase with regular increments or irregular intervals.

The output value X0 for any particular input value X1 of the operational variable is adjustable and user-selectable DECREASE' and INCREASE' options 703, 704 are provided for this purpose. User-selectable PREVIOUS' and NEXT' table navigation options 705, 706 are provided to allow scrolling through the array of cells of the operational variahle flow rate table 702.

Thus, a magnitude of a first operational variable is identified and a pre-deterniined base flow rate of the second fuel is adjusted with reference to a look-up table which provides a percentage degree of adjustment for an identified magnitude of the first operational variable to provide a modified base flow rate of said second fuel. It is to be appreciated however that in this context the term adjusted' encompasses reducing the base flow rate to zero, decreasing the base flow rate, maintaining the base flow rate or increasing the base flow rate and the term modified' encompasses a base flow rate reduced to zero, a decreased base flow rate, a maintained base flow rate or an increased base flow rate.

Figure 8 shows an adjustment table screen 801 of the graphical user interface 107 of fuel delivery system 101 for the VARIABLE 2' 305 table option of Figure 3.

Data is compiled for an operational variable took-up tahle 802 which associates an output value X2, Y2, 40 etc. for an associated input value X21, Y21. 41 etc. of the operational variable. The output value X20. Y20, Z20 etc. provides a percentage degree of adjustment to the modified base flow rate of the second fuel obtained as described with reference to Figure 7. The output value from the look-up table is multiplied by the modified base flow rate base flow rate of the second fuel to provide a second-stage modified base flow rate of the second fuel.

An output value of 100% would result in no adjustment being made to the modified base flow rate of the second fuel, an output value of 0% would result in the flow of second fuel being cut, an output value of between 0% and 100% decreases the modified base flow rate of the second fuel and an output value of over 100% increases the modified base flow rate of the second fuel.

The operational variable look-up table 802 may have any suitable number of cells, for example the same, less or more than the base flow rate table 602 and the same, less or more than the first operational variable look-up table 702.

The input values X21, Y21. 41 etc. of the operational variable may be of any suitable magnitude, in terms of a percentage or a unit of measurement, and may increase with regular increments or irregular intervals.

The output value X20 for any particular input value X21 of the operational variable is adjustable and user-selectable DECREASE' and INCREASE' options 803, 804 are provided for this purpose. User-selectable PREVIOUS' and NEXT' table navigation options 805, 806 are provided to allow scrolling through the array of cells of the operational variahie flow rate table 802.

Further operational variable look-up tables may be utilised to provide further stages of adjustment to the flow rate of the second fuel, each operating on the result of the previous stage. Each look-up table may provide percentage adjustment values falling within any suitable range. for example between 0% and 300%.

In an embodiment: -The pre-deterrnined base flow rate of the second fuel is determined with reference to FIRST FUEL FLOW RATE' -The pre-determined base flow rate is adjusted with reference to a look-up table for a first operational variable being THROTTLE POSITION' to provide a modified base flow rate -The modified base flow rate is adjusted with reference to a look-up table for a second operational variable being ENGINE LOAD' to provide a second-stage modified base flow rate -The second-stage modified base flow rate is adjusted with reference to a look-up table for a third operational variable being COOLANT TEMPERATURE' to provide a third-stage modified base flow rate -The third-stage modified base flow rate is adjusted with reference to a look-up table for a fourth operational variable being ENGINE SPEED (RPM)' to provide a fourth-stage modified base flow rate -The fourth-stage modified base flow rate is adjusted with reference to a look-up table for a fifth operational variable being MASS AIRFLOW RATE' to provide a fifth-stage modified base flow rate In an alternative embodiment: -The pre-determined base flow rate of the second fuel is determined with reference to MASS AIRFLOW RATE -The pre-detern-iined base flow rate is adjusted with reference to a look-up table for a first operational variable being THROTTLE POSITION' to provide a modified base flow rate -The modified base flow rate is adjusted with reference to a look-up table for a second operational variable being ENGINE LOAD' to provide a second-stage modified base flow rate -The second-stage modified base flow rate is adjusted with reference to a look-up table for a third operational variable being COOLANT TEMPERATURE' to provide a third-stage modified base flow rate -The third-stage modified base flow rate is adjusted with reference to a look-up table for a fourth operational variable being ENGINE SPEED (RPM)' to provide a fourth-stage modified base flow rate As mentioned previously, a sensor input may be obtained directly from the sensor or from the vehicle's CAN (controller area network) bus system.

In addition, it is to be appreciated that upper and lower thresholds, interpolation or a suitable algorithm may be used to determine which output value is to be used for a detected magnitude of an operational variable that falls between magnitudes of stored input values in the look-up table for that operational variable.

The described method of controlling, in real-time, a supply of a second gaseous fuel to a combustion engine supplied with a first fuel provides a convenient and cost-effect solution, in particular, for optimising the amount of additive second fuel to supply to a diesel-powered engine depending on engine/vehicle operational variables. The fuel delivery control method functions to optimise the use of the additive fuel during real-world driving conditions, to improve fuel efficiency and reduce harmful emissions.

The operational variable look-up tables may be used to cut the flow of the second fuel in such conditions as the coolant temperature being too low or too high, when the throttle is not pressed and the engine speed is too low.

Figure 9 shows an operating display screen 901 of the graphical user interface 107.

The screen shown is accessed by selecting the START' option 203 on the main menu screen 201.

During normal operation of the fuel delivery system 101, various informational items are displayed, with some data changing in real-time, for the benefit of the user.

The operating display screen 901 displays a user-selectable STOP option 902 that allows a user to stop the operation of the fuel delivery system 101, for example in instances where readings indicate a system problem or circumstances that could be damaging to the vehicle or dangerous to the user.

The information provided on operating display screen 901 includes the engine speed (RPM), shown at 903, the percentage of LPG flowing to diesel flowing, shown at 904, the percentage capacity of on-board LPG remaining, with tank low warning display, shown at 905, the percentage of air to LPG in the engine air intake, shown at 906, the injector duty percentage, for each fuel injector, as shown at 907, the solenoid status, as shown at 908.

The controller 102 of the fuel delivery system 101 is preferably programmed to perform an automatic control or shut-down operation in response to detecting a pre-determined condition or set of conditions. For example. by knowing the desired flow of LPG and the rating of the LPG injection system, the desired injector duty can be calculated as a percentage. The calculated injector duty can then be compared to a stored maximum injector duty. If the calculated injector duty is greater than the maximum injector duty, the actual flow of LPG can be limited so as not to exceed the maximum injector duty. In other instances, the look-up tables can be used to ensure that flow of LPG is stopped when sensors report extreme or abnormal values or when the engine speed is detected as zero.

An automatic system shut down function may be activated if the LPG tank level is detected as too low.

It is to be appreciated the content provided on any screen displayed by the graphical user interface 107 may vary between applications and may be customisable.

Figure 10 illustrates steps in a method 1001 of controlling, in real-time, a supply of a second fuel to a combustion engine supplied with a first fuel, according to the present invention.

At step 1002, the base flow rate of second fuel is determined. At step 1003, the magnitude of an operational variable is identified and at step 1004 an associated percentage degree of adjustment is identified. At step 1005 a modification calculation is performed, multiplying the base flow rate of second fuel determined at step 1002 with the percentage degree of adjustment identified at step 1004 that is associated with the magnitude of the operational variable identified at step 1003. At step 1006 a question is asked as to whether another magnitude of another operational variable is to be identified. If the question at step 1006 is answered in the affirmative, step 1003 is entered again. If the question at step 1006 is answered in the negative, step 1002 is entered again.

A method of controlling, in real-time, a supply of a second fuel to a combustion engine supplied with a first fuel, is provided. In an embodiment, a computer-readable medium having computer-readable instructions executable by a computer, such that the computer performs the method is provided.

A controller for controlling, in real time, a supply of a second fuel to a combustion engine supplied with a first fuel, is provided. A vehicle comprising the controller is also provided. A fuel delivery system comprising a controller as claimed in further provided.

Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiments shown and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

Claims

Claims 1. A method of controlling, in real-time, a supply of a second fuel to a combustion engine supplied with a first fuel, said method comprising the steps of: identifying a magnitude of a first operational variable, and adjusting a pre-determined base flow rate of said second fuel with reference to a look-up table which provides a percentage degree of adjustment for an identified magnitude of said first operational variable to provide a modified base flow rate of said second fuel.
2. A method as claimed in claim 1, wherein said second fuel is supplied to the air intake manifold of the combustion engine.
3. A method as claimed in claim 1 or claim 2, wherein said pre-determined base flow rate of said second fuel is one of: a fixed amount, a percentage of the first fuel flow rate.
4. A method as claimed in any preceding claim, wherein said second fuel has a higher research octane number (RON) than said first fuel.
5. A method as claimed in claim 4, wherein said first fuel is diesel arid said second fuel is one of: liquefied petroleum gas (LPG). compressed natural gas (CNG), liquefied natural gas (LNG).
6. A method as claimed in any preceding claim, wherein said pre-determined base flow rate of said second fuel is determined with reference to one of: first fuel flow rate, mass airflow rate.
7. A method as claimed in any preceding claim, wherein said first operational variable is throttle position.
8. A method as claimed in any preceding claim, further comprising the steps of: identifying a magnitude of a second operational variable, and adjusting said modified base flow rate of said second fuel with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said second operational variable to provide a second-stage modified base flow rate of said second fuel.
9. A method as claimed in claim 8, wherein said second operational variable is engine load.
10. A method as claimed in any claim 8 or claim 9, further comprising the steps of: identifying a magnitude of a third operational variable, and adjusting said second-stage modified base flow rate of said second fuel with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said third operational variable to provide a third-stage modified base flow rate of said second fuel.
11. A method as claimed in claim 10, wherein said third operational variable is coolant temperature.
12. A method as claimed in any claim 10 or claim 11, further comprising the steps of: identifying a magnitude of a fourth operational variable, and adjusting said third-stage modified base flow rate of said second fuel with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said third operational variable to provide a fourth-stage modified base flow rate of said second fuel.
13. A method as claimed in claim 12, wherein said fourth operational variable is revolutions-per-minute (RPM).
14. A method as claimed in any claim 12 or claim 13, further comprising the steps of: identifying a magnitude of a fifth operational variable, and adjusting said fourth-stage modified base flow rate of said second fuel with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said third operational variable to provide a fifth-stage modified base flow rate of said second fuel.
15. A method as claimed in claim 14, wherein said fifth operational variable is mass airflow rate.
16. A computer-readable medium having computer-readable instructions executable by a computer, such that said computer performs the method of any of claims 1 to 15.
17. A controller for controlling, in real time, a supply of a second fuel to a combustion engine supplied with a first fuel, said controller operable to adjust a pre-determined base flow rate of a second fuel supplied to a combustion engine supplied with a first fuel with reference to an adjustment table which provides a percentage degree of adjustment for an identified magnitude of an operational variable to provide a modified base flow rate of said second fuel.
18. A controller operable to perform the method of any of claims 1 to 16.
19. A vehicle comprising a controller as claimed in claim 18.
20. A fuel delivery system comprising a controller as claimed in claim 18.
21. A fuel delivery system as claimed in claim 20, wherein said second fuel is delivered into the air intake of the combustion engine.
22. A vehicle comprising a fuel delivery system as claimed in claim 20 or claim 21, wherein said controller is in communication with a graphical user interface device.
23. A vehicle comprising a fuel delivery system as claimed in any of claims 20 to 22.
24. A method of controlling, in real-time, a supply of a second fuel to a combustion engine supplied with a first fuel, substantially as described herein with reference to the accompanying drawings.
25. A controller for controlling, in real time, a supply of a second fuel to a combustion engine supplied with a first fuel, substantially as described herein with reference to the accompanying drawings.
26. A vehicle comprising a controller for controlling, in real time, a supply of a second fuel to a combustion engine supplied with a first fuel, substantially as described herein with reference to the accompanying drawings.
27. A fuel delivery system, substantially as described herein with reference to the accompanying drawings.Amendments to the Claims have been filed as follows: Claims 1. A method of controlling, in real-time, a supply of a second, additive fuel to a combustion engine supplied with a first fuel, said method comprising the steps of: a) identifying a base flow rate of said second additive fuel with reference to a first look-up table using first sensor data sensed in real-time; b) identifying a magnitude of a first operational variable using second sensor data sensed in real-time and identifying an associated percentage degree of adjustment with reference to a second look up table, and c) performing a modification calculation to adjust the base flow rate of said O second, additive fuel identified at step a) using the percentage degree of r adjustment identified at step b) to provide a modified base flow rate of saidCC) second, additive fuel.2. A method as claimed in claim 1, wherein said second, additive fuel is supplied to the air intake manifold of the combustion engine.3. A method as claimed in claim 1 or claim 2, wherein the base flow rate of said second, additive fuel identified at step a) is one of: a fixed amount, a percentage of the first fuel flow rate.4. A method as claimed in any preceding claim, wherein said second, additive fuel has a higher research octane number (RON) than said first fuel.5. A method as claimed in claim 4, wherein said first fuel is diesel and said second, additive fuel is one of: liquefied petroleum gas (LPG), compressed natural gas (CNG). liquefied natural gas (LNG).6. A method as claimed in any preceding claim, wherein the base flow rate of said second, additive fuel identified at step a) is determined with reference to one of: first fuel flow rate, mass airflow rate. IC)O A method as claimed in arty preceding claim, wherein said first r operational variable is throttle position.Cis 8. A method as claimed in any preceding claim, further comprising the steps of: (d) identifying a magnitude of a second operational variable, and (e) adjusting said modified base flow rate of said second, additive fuel obtained from step (c) with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said second operational variable to provide a second-stage modified base flow rate of said second, additive fuel.9. A method as claimed in claim 8, wherein said second operational variable is engine load.10. A method as claimed in any claim 8 or claim 9, further comprising the steps of: (f) identifying a magnitude of a third operational variable, and (g) adjusting said second-stage modified base flow rate of said second, additive fuel with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said third operational variable to provide a third-stage modified base flow rate of said second, additive fuel. IC)O 11. A method as claimed in claim 10, wherein said third operational r variable is coolant temperature.Cis 12. A method as claimed in any claim 10 or claim 11. further comprising the steps of: (h) identifying a magnitude of a fourth operational variable, and (i) adjusting said third-stage modified base flow rate of said second, additive fuel with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said third operational variable to provide a fourth-stage modified base flow rate of said second, additive fuel.13. A method as claimed in claim 12, wherein said fourth operational variable is revolutions-per-minute (RPM).14. A method as claimed in any claim 12 or claim 13, further comprising the steps of: (j) identifying a magnitude of a fifth operational variable, and (k) adjusting said fourth-stage modified base flow rate of said second, additive fuel with reference to an adjustment table that provides a percentage degree of adjustment for an identified magnitude of said third operational variable to provide a fifth-stage modified base flow rate of said second, additive fuel. IC)O 15. A method as claimed in claim 14, wherein said fifth operational r variable is mass airflow rate.Cis 16. A computer-readable medium having computer-readable instructions executable by a computer, such that said computer performs the method of any of claims 1 to 15.17. A controller for controlling, in real time, a supply of a second, additive fuel to a combustion engine supplied with a first fuel, said controller operable to adjust a pre-determined base flow rate of a second, additive fuel supplied to a combustion engine supplied with a first fuel with reference to an adjustment table which provides a percentage degree of adjustment for an identified magnitude of an operational variable to provide a modified base flow rate of said second, additive fuel.18. A controller operable to perform the method of any of claims 1 to 16.19. A vehicle comprising a controller as claimed in claim 18.20. A fuel delivery system comprising a controller as claimed in claim 18. IC)O 21. A fuel delivery system as claimed in claim 20, wherein said second, r additive fuel is delivered into the air intake of the combustion engine.Cis 22. A vehicle comprising a fuel delivery system as claimed in claim 20 or claim 21, wherein said controller is in communication with a graphical user interface device.23. A vehicle comprising a fuel delivery system as claimed in any of claims 20 to 22.24. A method of controlling, in real-time, a supply of a second, additive fuel to a combustion engine supplied with a first fuel, substantially as described herein with reference to the accompanying drawings.25. A controller for controlling, in real time, a supply of a second, additive fuel to a combustion engine supplied with a first fuel, substantially as described herein with reference to the accompanying drawings.26. A vehicle comprising a controller for controlling, in real time, a supply of a second, additive fuel to a combustion engine supplied with a first fuel, LI') substantially as described herein with reference to the accompanying drawings. r27. A fuel delivery system, substantially as described herein with C) reference to the accompanying drawings.