WO2007006069A1

WO2007006069A1 - Apparatus and method for diesel engine fumigation

Info

Publication number: WO2007006069A1
Application number: PCT/AU2005/001036
Authority: WO
Inventors: Kingsley Songer
Original assignee: Dga (Ip) Pty Ltd
Priority date: 2005-07-14
Filing date: 2005-07-14
Publication date: 2007-01-18
Also published as: TR200802567T2; AU2005334455A1

Abstract

The present invention relates to an apparatus and method for monitoring and controlling the volume of gaseous fuel that is delivered into the air intake stream of a diesel engine in accordance with one or more engine load parameters. The system works by having associated therewith an upper limit fumigation volume that is regulated according to data received from the one or more sensors that is compared with look-up tables so that only a percentage of the upper limit volume is delivered. The fumigation system further allows a user to input a desired fumigation delivery volume at a predetermined engine speed and a predetermined load condition to thereby establish a tailor-made fumigation delivery system.

Description

Apparatus and method for diesel engine fumigation

The present invention relates to an apparatus and method for diesel engine fumigation and, in particular, to an apparatus and method for improving the burn characteristics of a diesel engine by controlling and monitoring the amount of fuel introduced into the air intake stream based on engine load data.

BACKGROUND OF THE INVENTION

Diesel engines are well known. Diesel fuel is typically injected into the engine's combustion chamber when that chamber's piston is near the end of the compression stroke and the high pressure present in the chamber ignites the diesel fuel. Various apparatus and methods exist for increasing the power and torque output of a diesel engine. One such method is known as dual-fuel or fumigation technology. In order to provide for more complete combustion in diesel engines, dual-fuel or fumigation technology involves the introduction of gaseous fuel, such as liquefied petroleum gas (LPG), into the intake air of the engine. When more complete combustion of the diesel fuel is achieved, engine power is increased, as is engine fuel economy, and harmful emissions are reduced. A further benefit in using such technology is that it requires little modification to existing diesel engines.

Diesel engine fumigation systems known to the present inventor typically involve the use of an electronic control unit, a sensing device, and a fuel control valve associated with the air intake manifold of a diesel engine. The sensing device, typically in the form of a transducer, senses a load parameter of the engine and communicates this information to the electronic control unit which in turn signals the fuel control valve to open and close in accordance with the amount of fuel that is required. Typically, the manifold absolute pressure (MAP) or boost pressure within the air intake manifold is the detected parameter.

In such systems, the amount of fuel that is introduced into the intake manifold of the engine is exclusively dependent on this detected load parameter. For example, in a situation where the sensor detects a high MAP, the control unit will recognise that the engine is under considerable load and requires more fuel, and will therefore signal the fuel control valve to open and introduce more fuel into the intake manifold.

The present inventor has recognised that in order to control the amount of fuel made to enter the intake manifold of the engine, measuring this one parameter of engine load exclusively may not necessarily be adequate in maintaining a desired power output under all load conditions. For example, when a vehicle is travelling downhill, the MAP may be detected as being low, but the engine may indeed be running at high revolutions per minute (RPM). In using the abovementioned system, a low MAP detection causes only a small quantity of gaseous fuel to me mixed into the air stream, but because the engine is running at high RPM it actually requires a greater fuel intake for more complete combustion to occur, which it will not receive using the existing technology. In such conditions diesel fuel consumption may increase too. Furthermore, existing fumigation technology does not perform well when used in naturally aspirated engines because MAP readings may be inaccurate.

The present inventor has further recognised that certain individuals may require custom fumigation systems to suit their particular needs and to suit particular driving situations. For example, where one driver may be required to operate their vehicle at low load levels such as when driving a garbage collection truck for example, in which case the engine idles for extended periods of time, another driver may be required to operate their vehicle at constant, high RPM and high loads such as truck drivers who drive long distances at high speeds.

It is therefore an object of the present invention to overcome at least some of the aforementioned problems or to provide the public with a useful alternative.

It is a further object of the present invention to provide an apparatus and method for controlling and monitoring the volume of gaseous fuel introduced into the air intake stream of a diesel engine on the basis of engine load data with respect to one or more parameters including the manifold absolute pressure, the engine speed, the throttle position, the mass air flow, and various other parameters.

It is a still further object of the present invention to provide a method of modifying data obtained from the one or more load parameters so that it corresponds with a particular vehicle's fuel system or a particular user requirement.

SUMMARY OF THE INVENTION

Therefore in one form of the invention there is proposed a fumigation delivery apparatus for use in association with a diesel engine having an air intake stream, said apparatus characterised by: a fuel supply means operable to regulate a predetermined maximum volume of fuel flow into the air intake stream; and a control means adapted to control the fuel supply means such that regulation of the fuel flow is dependent upon at least one load parameter of the engine.

Preferably the regulation of the fuel flow is dependent upon a combination of two or more load parameters of the engine.

In preference the fuel supply means is a valve disposed in the flow path between a fuel supply and the air intake stream. In preference the regulated volume of fuel is a percentage of the predetermined volume of fuel flow.

Preferably the predetermined maximum volume is selectable by a user.

In preference the control means is in the form of an electronic control unit.

In preference each of said load parameters is measured using a corresponding sensor wherein data signals from each sensor are communicated to the electronic control unit that controls the fuel supply means accordingly.

Preferably the load parameter is the absolute pressure in the air stream manifold associated with the engine.

Preferably said load parameter is the speed of the engine.

Preferably said load parameter is the mass air flow through the air intake stream of the engine.

In preference said load parameter is the throttle position.

Preferably said load parameter is the intake air temperature.

In preference said load parameter is the temperature of the engine coolant.

Preferably the control means disables the fuel supply means when the vehicle is braking.

Preferably the control means disables the fuel supply means during gear changing.

In preference the fumigation delivery apparatus further includes a lock-off solenoid disposed between the fuel supply and the fuel supply means, said lock-off solenoid adapted to prevent flow of fuel between the fuel supply and the fuel supply means when the engine is not running.

In preference said valve is in the form of a stepper motor. Alternatively said valve is in the form of a fuel vapour injector.

In a further form of the invention there is proposed a method of delivering fuel into an air intake stream of a diesel engine, said method characterised by: establishing a predetermined maximum volume of fuel flow into the air intake stream; detecting at least one load parameter of the engine; and regulating the predetermined maximum volume of fuel flow into the air intake stream of the engine based on the at least one detected load parameter so that a final flow volume is established that is a percentage of the predetermined maximum volume. In preference the predetermined maximum volume of fuel flow into the air intake stream is selectable by a user.

Preferably the speed of the engine is detected.

In preference a desired final flow volume can be set by a user so that at a predetermined engine speed and a predetermined load the fuel flow into the air intake stream so that the input desired flow volume is achieved.

Preferably said predetermined load relates to a predetermined load parameter of the engine.

Preferably the predetermined load parameter is the absolute pressure in the air stream manifold associated with the engine.

In preference the predetermined load parameter is the mass air flow through the air intake stream of the engine.

Preferably the predetermined load parameter is the throttle position.

In preference the predetermined load parameter is the intake air temperature.

In preference the predetermined load parameter is the temperature of the engine coolant.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings,

Figure 1 illustrates a schematic view of a fumigation system of the present invention when fitted to a turbocharged diesel engine;

Figure 2 illustrates a control setup screen associated with the software of the present invention;

Figure 3 illustrates the control setup screen of Figure 2 including a scroll-down menu of selectable engine types;

Figure 4 illustrates the control setup screen of Figure 2 including a scroll-down menu of selectable load control parameters;

Figure 5 illustrates the control setup screen of Figure 2 including a scroll-down menu of selectable delivery mechanisms; Figure 6 illustrates a visual monitor screen associated with the software of the present invention including indications of engine speed, manifold absolute pressure, throttle position, intake air temperature, engine coolant temperature and the fumigation delivery percentage;

Figure 7 illustrates a chart recorder screen associated with the software of the present invention;

Figure 8 illustrates a load delivery table associated with the software of the present invention;

Figure 9 illustrates compensation tables associated with the software of the present invention relating to Intake Air Temperature, Engine Coolant Temperature and Battery Voltage;

Figure 10 illustrates a first calibration screen associated with the software of the present invention relating to Throttle Position;

Figure 11 illustrates a second calibration screen associated with the software of the present invention relating to Mass Air Flow;

Figure 12 illustrates a third calibration screen associated with the software of the present invention relating to Manifold Absolute Pressure;

Figure 13 illustrates a fourth calibration screen associated with the software of the present invention relating to Intake Air Temperature;

Figure 14 illustrates a fifth calibration screen associated with the software of the present invention relating to Engine Coolant Temperature; and

Figure 15 illustrates a Load/Save Data screen associated with the software of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts.

Illustrated in Figure 1 is a gaseous fuel fumigation system 10 operatively connected to a diesel engine 12 with a turbocharger 14 attached. Briefly, the diesel engine 12 includes a cylinder housing 16, an air intake manifold 18, an exhaust manifold 20, and a fuel pump 22 for pumping diesel fuel from a diesel fuel supply 24 to an injection means (not shown) associated with the cylinders (not shown). In the diesel engine 12, combustion of the fuel/air mixture takes place by way of compression inside the cylinders. The engine 12 further includes an alternator 26, and the turbocharger 14 includes an air inlet pipe 28 and an exhaust pipe 30 associated therewith. As is known in the art, the turbocharger 22 utilises exhaust gases to pressurise the intake air and thereby deliver compressed air to the cylinders, and is typically used in diesel engines for increasing their power output.

It is to be understood that the fumigation system 10 may be fitted to differently configured engines, such as naturally aspirated engines for example. It is to be further understood that the fumigation system 10 is configured so that newly manufactured engines may be equipped with such systems, or they may be retrofit onto existing engines with little modification to the engine.

The fumigation system 10 of the present invention includes a fuel supply tank 32 adapted to store gaseous fuel, such as liquefied petroleum gas (LPG), and a fuel supply valve 34 which is operable to control the volume of gaseous fuel allowed to be supplied to the air intake 18 of the engine 12. The fumigation system 10 further includes an electronic control unit 36 which is adapted to receive information on a particular engine load parameter from one or more transducers positioned at appropriate locations around the engine 12, to thereby controllably operate the fuel supply valve 34 on the basis of the detected information. Each type of transducer, their respective positions in the engine 12, and the method by which the control unit processes the information will be described in more detail shortly.

Associated with the fuel tank 32, as is required by various standards is a lock-off solenoid (not shown) that ensures that if the fuel line is compromised fuel is shut off.

The fuel supply valve 34 may be of the linear valve type, such as a stepper motor, or alternatively, it may be of the vapour injection type. In preference, the stepper motor has micro-stepping capability so as to enable small variations in fuel control. A fuel lock-off solenoid 38 is also present upstream of the fuel supply valve 34 as a safety feature so as to prevent supply of gaseous fuel to the fuel supply valve 34 when the engine is not running. If the vehicle loses ignition the electronic control unit 36 will remove power from the lock-off solenoid 38. Typically the solenoid 38 is associated wit the gas converter (not shown) that causes the gas to change form a liquid to a gad form. This is well known in the art and for the sake of brevity is not discussed in any further detail, the skilled addressee being quite familiar with typical gas converters.

The transducers are positioned according to the type of information and data that is required to be measured and transmitted to the electronic control unit 36. Where in existing fumigation technology, the manifold absolute pressure (MAP) is measured exclusively, the present inventor has realised that in combining information relating to one or more other engine parameters and operating the fuel supply valve 34 accordingly, more complete combustion of diesel fuel can be achieved across a broader range of load conditions. Figure 1 illustrates the location of each sensor that is coupled to the electronic control unit 36 of the fumigation system 10. There is shown a manifold absolute pressure (MAP) transducer 40 as well as an engine speed sensor 42 that is associated with the alternator 26 of the engine. The engine speed sensor 42 detects the number of pulses of the alternator 26 and the engine speed is thereby calculated based on a predetermined ratio between the number of pulses and the revolutions of the engine. This sensor 42 also provides an ignition reference for the lock-off solenoid 38.

In using this additional tacho sensor 42, a more accurate reading of the engine load may be obtained and therefore a more precise amount of gaseous fuel may be supplied to the air intake to ensure complete combustion. This is achieved by regulating an upper limit fuel flow in accordance with the data received by the control unit 36. The upper limit fuel flow may be input into the control unit 36 in a number of different ways, for example, a predetermined amount of steps of a stepper motor may be set to allow for an upper limit of fuel to pass into the air intake. Appropriate software, such as the software described below, may be used to allow a user to simply input such a value. The control unit 36 then regulates the upper limit fuel flow volume according to data obtained from the MAP transducer 40 and engine speed sensor 42 to thereby establish a second fuel flow volume. The second fuel flow volume is calculated as a percentage of the upper limit volume that is obviously taken to be 100% fuel flow.

It is advantageous for the upper limit fuel flow to be regulated according to a number of other engine parameters in addition to the MAP and engine speed data. Figure 1 further illustrates a mass air flow (MAF) transducer 44, a throttle position sensor 46, an intake air temperature sensor 48 and an engine coolant temperature sensor 50. When data obtained from each of these sensors is combined, an extremely accurate indication of engine load is obtained. Using this information, the control unit is able to regulate the volume of gaseous fuel entering the air intake optimally and with improved response. It is to be understood that not all of the abovementioned sensors need to be used in the fumigation system 10 of the present invention, however, the more parameters incorporated into the calculation, the more accurate will be the amount of fuel delivered.

The MAF transducer 44 detects the air flow into the engine and is ideal for use in naturally aspirated engines, whereas the MAP transducer 40 detects the change in boost by measuring the absolute pressure in the air intake and is thus more suitable for use in turbocharged engines. Although both are shown in Figure 1 that is simply for the sake of brevity and normally you would have one or the other transducer depending on the type of engine. The MAF normally goes in line before it gets into the inlet manifold - it is in the air line itself.

The engine coolant temperature sensor 50 may be used to enable fuel delivery only after a predetermined engine temperature has been reached. Alternatively, a timing function could be used. Further sensors associated with the engine 12 are a brake sensor 52 and a clutch sensor 54. When the control unit 36 detects that the vehicle is braking or that a gear change is taking place, fuel delivery will be disabled. It is to be understood that different sensors may be used according to different configurations of engine.

Still further sensors that may be used in the fumigation system 10 include a flow sensor (not shown) associated with the fuel pump 22 of the engine, and a temperature or oxygen sensor (not shown) placed at the exhaust pipe 30 used to obtain additional engine load information.

It should now be apparent to those skilled in the art that the present invention provides a system 10 which effectively measures a parameter of engine load with respect to sensors that are available to an electronic control unit 36. The method by which the electronic control unit 36 processes the information obtained from the various sensors is also important. The detected data is compared with data stored in look-up tables so as to provide an appropriate fuel input into the system. This is easier described -with reference to the software associated with the present system which was also developed by the present inventor.

The software allows for a user to monitor the gaseous fuel supply and further modify the detected data in accordance with a specific engine type or their own personal requirements. Figures 2 to 15 illustrate the screen displays associated with the software of the present invention.

Figures 2-5 illustrate the control setup screen 55 which allows a user to input various information such as the engine type, the load control and the delivery mechanism, into the control unit 36. The Engine Type menu 56 allows for different engine types to be selected such as 4, 6, 8, 10 or 12 cylinder engines for example, the Load Control menu 58 allows for a user to select which load parameter is modifiable as will be described shortly, while the control unit 60 allows a user to select whether the fuel supply valve 34 is of the stepper motor or vapour injector type. Various other options are provided in the control setup screen such as a tick box 62 and 64 for enabling or disabling of the brake and clutch sensors 52 and 54 respectively.

Once the initial information has been entered in the control setup screen 55, one may then view the performance analyser screen 66 which is shown in Figure 6. This screen displays all of the information obtained from the various sensors and also an indication 68 of the calculated fumigation delivery which is displayed as a percentage of the upper limit. The screen 66 includes an engine speed gauge 70 displayed in RPM, a manifold absolute pressure gauge 72 displayed in pounds per square inch (psi), a throttle position gauge 74 displayed as a percentage, as well as indications of intake air temperature 76 and engine coolant temperature 78, both of which are displayed in degrees Celsiαs. Figure 7 provides a real time graphical display 80 of the fumigation delivery with various selectable load parameters 82 on the right hand side of the screen. As mentioned earlier, the detected data is compared with data stored in look-up tables and this controls the percentage amount of fuel that is delivered. The load delivery table 84 of Figure 8 is one such table and in this case, displays mass air flow versus rpm. Mass air flow was the load parameter selected in the control setup screen and this is the reason this particular parameter is shown. For example, if manifold absolute pressure were selected, the table would display manifold absolute pressure versus rpm. Although not shown, each cell 86 of this table will typically be full of standard predetermined fumigation delivery percentages indicative of the optimal amount of fuel to be delivered at a particular rpm and load.

The advantage of this table is that a user may input fumigation delivery percentages so that the amount of fuel that is delivered into the intake air stream may be modified to suit a particular driver's needs or tailored for a specific engine type. If for example at an engine speed of lOOOrpm and a mass air flow of 7g/s, approximately 20% of the upper fuel limit is required, this value may simply be entered into the load delivery table and the stepper motor or fuel injector will be made to work at approximately 20% of the upper limit. Typically, the maximum percentage that will be input will be in the range of 24-25%. Higher percentages may well be input but this will generally waste fuel. When values have been entered into the cells of each fumigation delivery table, that is, each table associated with each detected load parameter, these are each compared and a final fumigation delivery percentage is obtainable. This percentage is the percentage shown in the display screen 68 of Figure 6 and the real time display 80 of Figure 7.

Figure 9 illustrates compensation tables 88, 90 and 92 that are used to modify the final fumigation delivery percentage in accordance with the detected Intake Air Temperature, Engine Coolant

Temperature, and Battery Voltage respectively. For example, in this particular case, if an intake air temperature of 30 degrees Celsius is detected, then 0% compensation is required, but if the intake air temperature is measured at 15 degrees Celsius for example, then the final fumigation delivery percentage needs to be compensated by 2%. Figures 10-14 are transducer calibration tables/graphs 94, 96, 98, 100 and 102 for the load parameters of Throttle Position, Mass Air Flow, Manifold Absolute Pressure, Intake Air Temperature and Engine Coolant Temperature respectively. These tables are used to calibrate the respective transducers according to known data because the information obtained from the transducers may become slightly skewed over time. Finally, Figure 15 illustrates a Load/Save screen 104 associated with the software of the present invention which allows a user to save any changes made to any of the tables, and to further load such information at a future time, as is well known in the art.

The present invention therefore provides an apparatus and method for monitoring and controlling the volume of gaseous fuel that is delivered into the air intake stream of a diesel engine in accordance with one or more engine load parameters. The system 10 works by having associated therewith an upper limit fumigation volume that is regulated according to data received from the one or more sensors that are compared with look-up tables so that only a percentage of the upper limit volume is delivered. The fumigation system 10 further allows a user to modify data stored in the look-up tables to thereby create a tailor-made fumigation delivery system.

Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

In any claims that follow and in the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", i.e. the features specified may be associated with further features in various embodiments of the invention.

Claims

1. A fumigation delivery apparatus for use in association with a diesel engine having an air intake stream, said apparatus characterised by: a fuel supply means operable to regulate a predetermined maximum volume of fuel flow into the air intake stream; and a control means adapted to control the fuel supply means such that regulation of the fuel flow is dependent upon at least one load parameter of the engine.

2. A fumigation delivery apparatus as in claim 1 wherein the regulation of the fuel flow is dependent upon a combination of two or more load parameters of the engine.

3. A fumigation delivery as in claim 1 or claim 2 wherein the fuel supply means is a valve disposed in the flow path between a fuel supply and the air intake stream.

4. A fumigation delivery apparatus as in claim 3 wherein the regulated volume of fuel is a percentage of the predetermined volume of fuel flow.

5. A fumigation delivery apparatus as in any one of the above claims wherein the predetermined maximum volume is selectable by a user.

6. A fumigation delivery apparatus as in any one of the above claims wherein the control means is in the form of an electronic control unit.

7. A fumigation delivery apparatus as in any one of the above claims wherein each of said load parameters is measured using a corresponding sensor wherein data signals from each sensor are communicated to the electronic control unit which controls the fuel supply means accordingly.

8. A fumigation delivery apparatus as in any one of the above claims wherein the load parameter is the absolute pressure in the air stream manifold associated with the engine.

9. A fumigation delivery apparatus as in any one of the above claims wherein said load parameter is the speed of the engine.

10. A fumigation delivery apparatus as in any one of the above claims wherein said load parameter is the mass air flow through the air intake stream of the engine.

11. A fumigation delivery apparatus as in any one of the above claims wherein said load parameter is the throttle position.

12. A fumigation delivery apparatus as in any one of the above claims wherein said load parameter is the intake air temperature.

13. A fumigation delivery apparatus as in any one of the above claims wherein said load parameter is the temperature of the engine coolant.

14. A fumigation delivery apparatus as in any one of the above claims wherein the control means disables the fuel supply means when the vehicle is braking.

15. A fumigation delivery apparatus as in any one of the above claims wherein the control means disables the fuel supply means during gear changing.

16. A fumigation delivery apparatus as in any one of the above claims wherein the fumigation delivery apparatus further includes a lock-off solenoid disposed between the fuel supply and the fuel supply means, said lock-off solenoid adapted to prevent flow of fuel between the fuel supply and the fuel supply means when the engine is not running.

17. A fumigation delivery apparatus as in any one of the above claims wherein said valve is in the form of a stepper motor.

18. A fumigation delivery apparatus as in any one of the above claims wherein said valve is in the form of a fuel vapour injector.

19. A method of delivering fuel into an air intake stream of a diesel engine, said method characterised by: establishing a predetermined maximum volume of fuel flow into the air intake stream; detecting at least one load parameter of the engine; and regulating the predetermined maximum volume of fuel flow into the air intake stream of the engine based on the at least one detected load parameter so that a final flow volume is established that is a percentage of the predetermined maximum volume.

20. A method of delivering fuel into an air intake stream of a diesel engine as in claim 19 wherein the predetermined maximum volume of fuel flow into the air intake stream is selectable by a user.

21. A method of delivering fuel into an air intake stream of a diesel engine as in claim 19 or claim 20 wherein the speed of the engine is detected.

22. A method of delivering fuel into an air intake stream of a diesel engine as in claim 21 wherein a desired final flow volume can be set by a user so that at a predetermined engine speed and a predetermined load the fuel flow into the air intake stream so that the input desired flow volume is achieved.

23. A method of delivering fuel into an air intake stream of a diesel engine as in claim 22 wherein said predetermined load relates to a predetermined load parameter of the engine.

24. A method of delivering fuel into an air intake stream of a diesel engine as in claim 23 wherein the predetermined load parameter is the absolute pressure in the air stream manifold associated with the engine.

25. A method of delivering fuel into an air intake stream of a diesel engine as in claim 23 wherein the predetermined load parameter is the mass air flow through the air intake stream of the engine.

26. A method of delivering fuel into an air intake stream of a diesel engine as in claim 23 wherein the predetermined load parameter is the throttle position.

27. A method of delivering fuel into an air intake stream of a diesel engine as in claim 23 wherein the predetermined load parameter is the intake air temperature.

28. A method of delivering fuel into an air intake stream of a diesel engine as in claim 23 wherein the predetermined load parameter is the temperature of the engine coolant.