WO2005064144A1

WO2005064144A1 - Compression ignition engine improvements

Info

Publication number: WO2005064144A1
Application number: PCT/AU2004/001805
Authority: WO
Inventors: Uli Kruger
Original assignee: Kruger Ventures Pty Ltd
Priority date: 2003-12-30
Filing date: 2004-12-23
Publication date: 2005-07-14

Abstract

An arrangement for delivering output power through a compression ignition engine characterised in that there are means (1) to effect a supply of combustible gas into the air supply (4) of the engine in such a way that there is maintained a relatively consistent and constant quantity of gas as a proportion of liquid fuel being injected into the engine, sensor means (2) responsive either to the manifold pressure. Or outlet temperature of the engine and effecting an output electrical signal proportional to said manifold pressure or said exhaust temperature, means (23) receiving such electrical signal and effecting a change in such signal which are adapted to effect a control in response to such modified signal in respect of the rate of liquid fuel being injected into the engine.

Description

TITLE

COMPRESSION IGNITION ENGINE IMPROVEMENTS

TECHNICAL FIELD

This invention relates to compression ignition engine improvements and in particular to an arrangement incorporating a compression ignition engine, a method of effecting control of a compression ignition engine, and means facilitating control of a compression ignition engine.

BACKGROUND ART

The problem to which this invention is directed relates to difficulties associated with compression ignition engine where these may have an arrangement for additional alternate fuel to be provided through their air intake.

The invention has particular application to compression ignition engine which have additional compression applied to their air inlet supply.

This arrangement is usually referred to as a "turbo charge" system.

Attempts have been made in the past to provide additional alternate fuel in the form of a combustible gas which is introduced with the air supply into the engine.

In one case, there is provided passage of air through a restricted passageway whereby to effect a lowering of the pressure of the gas by causing it to proceed faster through the restricted are and using such restricted pressure to effect a draw in of gas supply.

A number of problems exist with such an arrangement.

A first of these is that as the quantity of gas drawn into the air supply is an approximate proportion of the air velocity, and given that changes in engine load on a compression ignition engine does not significantly vary the revolution rate of the engine and therefore the air velocity, it is very difficult in such a case to maintain any sensible relationship of the quantity of gas as a factor in relation to the load requirements of the engine. In practice then, in order to avoid causing mixture ratios which are simply uneconomic to use or will cause pre-ignition, the proportion of gas to air is kept very low indeed and it is highly questionable as to whether there is therefore any economic benefit by introducing gas as a supplementary fuel in this way.

A further difficulty is however that by introducing gas into the air fuel mixture where the further fuel is for instance diesel, will change the burn characteristics and therefore the power curves in relation to an engine.

In some instances, by adding gas, at a given engine speed, the available output power may be increased significantly by adding gas but if at a given engine speed, the proportion of gas is above a relatively small ratio as compared to diesel, it is found that there is no economic or output power benefit achieved at all.

The problem to which this invention is addressed then is the problem associated with the difficulty of achieving a more economical cost of running of compression ignition engines.

A further problem to which the invention is directed relates to achieving improved economics, especially by providing gas supplementation.

DISCLOSURE OF THE INVENTION

In one form, the invention may be said to reside in a method of controlling a compression ignition engine of a type including engine control means adapted to control the power output of the engine at least in part by controlling the rate of supply of liquid fuel to the engine in response to information signals from at least one sensor, said signals being informational as to the load being placed on the engine, the method including providing a supplementary fuel supply by effecting a supply of combustible gas into the air supply of the engine in such a way that there is maintained a relatively constant quantity of gas as a proportion of liquid fuel being supplied to the engine, receiving said signals from the sensor and effecting a control by the engine control means in response to said signals such that the engine performance is substantially the same as in the absence of the supplementary fuel supply.

In preference there are intermediate means adapted to intercept the signals from the sensor and to modify said signals such that the control effected by the engine control means in response to the modified signal is such that the engine performance is substantially the same as in the absence of the supplementary fuel supply.

In preference, the sensor is adapted to sense an inlet manifold pressure.

In the alternative, the sensor is adapted to sense an outlet temperature of the engine.

In a further form of the invention there is provided an apparatus adapted to control a compression ignition engine including engine control means adapted to control the power output of the engine at least in part by controlling the rate of supply of liquid fuel to the engine in response to information signals from at least one sensor, said signals carrying information as to the load being placed on the engine, fuel supply means adapted to provide a supplementary fuel supply by effecting a supply of combustible gas into the air supply of the engine in such a way that there is maintained a relatively constant quantity of gas as a proportion of liquid fuel being supplied to the engine, control means adapted to effect a control by the engine control means in response to said signals such that the engine performance is substantially the same as in the absence of the supplementary fuel supply.

In preference, the control means includes an intermediate processor adapted to receive said electrical signals and to modify said signals such that the control effected by the engine control means in response to the modified signal is such that the engine performance is substantially the same as in the absence of the supplementary fuel supply.

In preference, the intermediate processor has an operational mode in which the electrical signals coming from the inlet manifold sensor are passed straight through to the engine control means without modification and in addition, there is effected then a closure so as to stop the supplementary fuel supply being introduced into the air inlet.

In preference, the engine control means is an engine control unit.

In preference, the intermediate processor further includes externally accessible data storage means where such data storage can be programmed to keep a selection of operating programs, said programs being adapted to effect a modification of the signals such that an operating characteristic of the engine is appropriate to the level of supplementary fuel being supplied.

In one form of this invention, there is proposed an arrangement for delivering output power through a compression ignition engine characterised in that there are means to effect a supply of combustible gas into the air supply of the engine in such a way that there is maintained a relatively consistent and constant quantity of gas as a proportion of liquid fuel being injected into the engine, sensor means responsive either to the manifold pressure or outlet temperature of the engine and effecting an output electrical signal proportional to said manifold pressure or said exhaust temperature, means receiving such electrical signal and effecting a change in such signal which are adapted to effect a control in response to such modified signal in respect of the rate of liquid fuel being injected into the engine.

In preference, the sensor means uses the inlet manifold pressure.

In preference, the arrangement includes compression means to effect an increase in air pressure for inlet air and with this, supplementary gaseous fuel.

In preference, there are intermediate means which are arranged to intercept an electrical signal from the inlet manifold pressure sensor means and effect an output which is according to a preselected output from the apparatus in response to each level of input signal.

In a conventional turbo charged engine, it is known to have an inlet manifold pressure sensor which outputs an electrical signal which directly controls the rate of liquid fuel being injected into the engine at any time.

A conventional engine control unit uses such an input to boost output power appropriately in accordance with other measured performance characteristics of the engine.

Such an electronic control unit applies an appropriate engine management curve in response to all of the engine information but in the event that it does not receive information regarding the inlet manifold pressure, this then is taken to cause the quantity of liquid fuel to be injected to be reduced in accordance with the apparent very low or undetected inlet manifold pressure.

In a sense then, this derates the engine so that it will still maintain a predicted horsepower output curve over a range of engine speeds but where the output power is significantly reduced over the full range of engine speeds.

I have discovered that when I add a gas supplementation where the gas is injected into the air stream and is pulled at a rate that is matching the power requirements of the engine, then because of the different burning characteristics within a respective cylinder of the engine, a different matching of the characteristics of the engine situation evidenced by the inlet manifold pressure should be handled differently through the range and in practice I have found by using this technique that I can return the engine to have engine power characteristics over the range of engine speeds that will be relatively closely matching those that would be expected without gas supplementation.

The advantage however with this is that by using gas supplementation in this way, I have found that as much as 35-40% of the input energy required by the engine at any time can then be supplied by the gas.

In preference, the means intercepting the electrical information arising from the sensor within the inlet manifold to detect pressure is arranged so that it will have two states, one of which is to effect a modification in the output then being further fed to the electronic control unit of the engine so as to have this accord with an appropriate gas supplemented characteristic, and a second state in which the information coming from the inlet manifold sensor is passed straight through to the electronic control unit without modification but in addition, there is effected then a closure so as to stop further gas being introduced into the air inlet.

By having these two states, there is then available a fall back position in the event, for instance that there is a fault detected in the supplementation electronics or software or hardware in which case there can be a characteristic which can be the same identically that the engine would have without gas supplementation.

In other words, by having such a fall back status, especially by being able to switch the gas supplementation off, in conjunction with detecting a fault in the apparatus, means that the engine can be almost instantly returned to a conventional operating system with the disadvantage only that the economy of having gaseous supplementation is no longer being used.

By having an intercepting modifier of the inlet manifold pressure sensor's output, means that in practice, different engine performance characteristics can be set into the engine in anticipation of different working conditions.

As a typical example, if an engine has a capacity to deliver at a certain revolutions per minute, say 600 horsepower, then if all of that horsepower is needed for instance, if it is going to be used to pull a large load such as a B- double trailer fully loaded, then the modifying unit can be programmed to provide this.

However, if the engine is only going to be used to pull say a single trailer load, or even a very lightly loaded unit, then it makes a huge amount of sense to program the unit while keeping the general characteristics of the engine performance consistent, to reduce the overall available engine power by a selected extent for instance, let us say 100 horsepower or 200 horsepower over the range of operating speeds.

In preference then, the unit has externally accessible data storage means where such data storage can be programmed to keep a selection of operating programs.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of this invention, it will now be described in relation to an embodiment which will be described with the assistance of drawings wherein;

Figure 1 is a schematic layout illustrating the respective components that are incorporated in the first embodiment,

Figure 2 illustrates an engine speed versus horsepower curve for a standard operating engine under conventional conditions and the curve of the same engine with gas supplementation without the advantage of the invention; and

Figure 3 is the curves of engine speed versus horsepower in relation to the same engine as shown in Figure 2 in which there is shown both the standard operating curve of the engine without gas supplementation and the features of the embodiment, and in the second curve, an achieved curve of operating conditions of the same engine with gas supplementation but using the modified response to inlet manifold pressure.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring in detail to the drawings, and in particular to figure, there is a natural vortex creator 1 which is positioned in line from an air inlet filter 2 which has a passageway 3 directing air into the vortex creator 1 which thereafter is connected by passage 4 through to manifold 5 of a "diesel" engine 6, in this case a 12 litre DETROIT Series 60 engine.

A low pressure gas (LPG) supply which holds gas in liquid form is shown at 8 and this is connected via conduit 9 through solenoid operated valve 10 to a liquid to gas converter at 11. The liquid to gas converter then supplies gas through conduit 12 at a relatively constant pressure so that this is fed into a low pressure center of any natural vortex that is formed within the vortex creator 1.

Such a vortex which is variously referred to as a centripetal or natural vortex is to be compared with an alternate type vortex which might be called a centrifugal vortex but such an alternate effect generally will not have a low pressure center.

Such distinctions however may be academic in practice where some characteristics of both may be exhibited in a formation. For this reason it is perhaps for the sake of accuracy better to refer to the natural vortex where there is a low pressure centre at its core and where this is being used for the purposes of this invention. Therefore while the term centripetal vortex has been used in some instances it is better to say that the vortex is having its centripetal component being used and we have used the term "natural vortex with a low pressure centre" to distinguish the characteristic required.

The vortex might be distinguished by reference to a centripetal or natural vortex providing a low pressure at its centre.

There are known devices to provide a centripetal vortex but we have described one instance only of this which has been found to provide good effect.

According to this invention and this embodiment in particular however, air is drawn through such a vortex creator so as to cause a low pressure to be caused at the centre of such a vortex, and conduit 12 has its opening so that it will connect with the lowest pressure position of the vortex.

Using this arrangement to effect a control of the degree of mixing of air with gaseous fuel has shown itself to provide significant reliability in respect of such ratio, especially over a reasonable range of power demands and this has had the advantage of being able to maintain performance in a over a range of power demands.

The inlet manifold 5 shown in schematic terms includes a pressure sensor 20 which is arranged to provide an analog output voltage over a range from 0-5 volts in response to the pressure within the manifold 5 and such that the voltage output will vary directly proportionally to the pressure detected by sensor 20 over a selected range of pressures.

Such an output would normally be directed into an electronic control unit (ECU) 21 which is programmed according to conventional processes and by the original manufacturer to accord with conventional use of diesel fuel and to provide reasonable and effective and safe working conditions within the ratings of the engine 6. The output of the ECU 21 drives the fuel injection fuel quantity control which controls the fuel, in this case diesel, to the engine.

Such a performance then, as a turbo charged but without any gas supplementation, is shown in Figure 2 as curve 27 where there is a 240 horsepower output at 1200 revs rising to just above 330 horsepower at 1750 revs per minute. There is then a drop in output, significantly so past 2000 revs per minute.

The output from the inlet manifold pressure sensor 20 is intercepted by Control Module 23 which includes an electronic potentiometer, and additional software programming, details of which will be described later. Thus a matching of the power output when gas supplementation is used is able to be achieved with the significant advantage that it is very much more economic to use gas in many instances than to use all liquid fuel.

However, referring again to Figure 2, if the inlet manifold sensor 20 output is removed from the electronic control unit 21 , then the output characteristics are as shown at 30. This is to say that there is a marginal output at 1200 revs per minute, rising to 150 horsepower at 1300 revs and having a maximum of approximately 230 horsepower at 1900 revs per minute.

While not following precisely the curve at 27, nonetheless, the reduction in power output is now very significant indeed and this occurs because the electronic control unit is no longer boosting supply of liquid fuel in response to the detected inlet manifold pressure.

I now refer to the availability of an arrangement in which the proportion of gaseous fuel will follow closely the quantity of liquid fuel being injected into the engine.

This is achieved by providing that inlet air being drawn or driven into the inlet of the engine shall be caused to follow into a centrifugal vortex where the centre of the vortex is a lowest pressure and the outside of the vortex is at a higher pressure and providing an inlet conduit within the centre of the vortex so that in response to the low pressure provided by such vortex, supplementary gas will be drawn into this to provide the energy supplementing gas for the engine.

An amazing discovery has been that using such an arrangement, that the quantity of gas seems to accord very reliably in proportion not to the quantity of air, which is to say the total quantity of air being drawn in but rather it responds to the load demands of the engine which are of course then reflected in the quantity of fuel being injected into the engine in response to load demands.

In experiences now over some period of time, this arrangement has shown itself to provide a reliable means of providing a high but relatively safe proportion of gaseous fuel as compared to the total quantity of fuel required and being used by a compression ignition engine from time to time.

A particular advantage of this arrangement is that it does not as such require any complex or vulnerable electronic feedback as to controlling the rate of input of the gas and further, by simply switching off the supply of gas, the supply of air, whether or not it is supplied through the vortex, does not of itself alter the conventional operating conditions or characteristics of the engine.

What we then have is a modifier control module 23, which is either internally programmed or in this case, externally programmed so that the input characteristics received from the inlet manifold pressure sensor 20 will now be modified as they are received by an input 31 and then the output 32 is directed through to the electronic control unit 21.

The extent to which the curves can be altered, is of course able to be controlled as required but it is worth now looking at what can be done.

Looking at Figure 2, by simply adding the gas supplementation without changing anything at all, then provides a engine speed horsepower curve as shown at 17 in which the initial power at low speeds is very low and for instance at 1200 revs per minute is perhaps 190 horsepower but at 1900 revs per minute, it is in excess of 390 horsepower.

The problem here is that such an increase in horsepower can be decidedly precarious in terms of demand on engine components and drive trains.

Also, while there is a high deliverable horsepower, this is not necessarily available to provide a most economic output.

However, by essentially intercepting the inlet manifold pressure sensor output, we have been able in one instance, and we are talking about the specific DETROIT engine, to match the output curves without gas supplementation.

One of the problems that can be experienced with engine management situations is that there can be failure of one or more components and this can sometimes lead to very difficult and perhaps dangerous conditions.

It is a significant advantage of this invention that there are means to simply switch off the supply of gas and to effect a straight through transmission of an output from the inlet manifold pressure sensor in the event of a fault condition being detected.

In relation to the intercepting components and the software controlling these, there is now provided a further discussion and explanation of the computer program and operating conditions to effect this.

While we have described one way in which the arrangements can be achieved and significant benefit can be gained, we have previously referred to the fact that the input source can also be the outlet exhaust temperature. This has the disadvantage that it follows with a modest delay the inlet manifold pressure and therefore a response to changing conditions is not as quick.

However, it is known that inlet manifold pressure and exhaust temperatures closely relate one to the other and either can be used as a further control unit to effect engine performance according to a selected input rate of liquid fuel.

From the above, it will now be appreciated that we are able now to apply this invention to a range of various compression ignition engines, especially where they are turbo charged, and it has been shown to be able to provide up to 30% savings in the effective cost of fuel for some point to point journeys.

Further, an important discovery has been that the burning conditions using higher gas content result in significant reduction from conventional engine outputs of pollution components, especially unburnt carbons, NO_x and carbon monoxide.

This is perhaps understandable because of the improved efficiency in any event, but it is of considerable advantage therefore, not only to the operator of diesel engines but to the community by reason of such reduction in pollution.

Throughout this specification the purpose has been to illustrate the invention and not to limit this.

Claims

1. A method of controlling a compression ignition engine of a type including engine control means adapted to control the power output of the engine at least in part by controlling the rate of supply of liquid fuel to the engine in response to information signals from at least one sensor, said signals being informational as to the load being placed on the engine, the method including providing a supplementary fuel supply by effecting a supply of combustible gas into the air supply of the engine in such a way that there is maintained a relatively constant quantity of gas as a proportion of liquid fuel being supplied to the engine, receiving said signals from the sensor and effecting a control by the engine control means in response to said signals such that the engine performance is substantially the same as in the absence of the supplementary fuel supply.

2. The method as in claiml wherein there are intermediate means adapted to intercept the signals from the sensor and to modify said signals such that the control effected by the engine control means in response to the modified signal is such that the engine performance is substantially the same as in the absence of the supplementary fuel supply.

3. The method as in claim 1 or claim 2 wherein the sensor is adapted to sense an inlet manifold pressure.

4. The method as in claim 1 or claim 2 wherein the sensor is adapted to sense an outlet temperature of the engine.

5. An apparatus adapted to control a compression ignition engine including engine control means adapted to control the power output of the engine at least in part by controlling the rate of supply of liquid fuel to the engine in response to information signals from at least one sensor, said signals carrying information as to the load being placed on the engine, fuel supply means adapted to provide a supplementary fuel supply by effecting a supply of combustible gas into the air supply of the engine in such a way that there is maintained a relatively constant quantity of gas as a proportion of liquid fuel being supplied to the engine, control means adapted to effect a control by the engine control means in response to said signals such that the engine performance is substantially the same as in the absence of the supplementary fuel supply.

6. An apparatus as in claim 5 wherein the control means includes an intermediate processor adapted to receive said electrical signals and to modify said signals such that the control effected by the engine control means in response to the modified signal is such that the engine performance is substantially the same as in the absence of the supplementary fuel supply.

7. An apparatus as in claim 5 or claim 6 including compression means to effect an increase in air pressure for inlet air and supplementary gaseous fuel.

8. An apparatus as in claim 6 wherein the intermediate processor has an operational mode in which the electrical signals coming from the inlet manifold sensor are passed straight through to the engine control means without modification and in addition, there is effected then a closure so as to stop the supplementary fuel supply being introduced into the air inlet.

9. An apparatus as in claim 6 or claim 8 wherein the engine control means is an engine control unit.

10. An apparatus as in any one of claims 6 to 9 wherein the intermediate processor further includes externally accessible data storage means where such data storage can be programmed to keep a selection of operating programs, said programs being adapted to effect a modification of the signals such that an operating characteristic of the engine is appropriate to the level of supplementary fuel being supplied.

11. An arrangement for delivering output power through a compression ignition engine characterised in that there are means to effect a supply of combustible gas into the air supply of the engine in such a way that there is maintained a relatively consistent and constant quantity of gas as a proportion of liquid fuel being injected into the engine, sensor means responsive either to the inlet manifold pressure or outlet temperature of the engine and effecting an output signal carrying information as to said manifold pressure or said exhaust temperature, means receiving such signal and effecting a change in such signal which are adapted to effect a control in response to such modified signal in respect of the rate of liquid fuel being injected into the engine.

12. The arrangement of claim 10, further including compression means to effect an increase in air pressure for inlet air and with this, supplementary gaseous fuel.

13. The arrangement of claim 10 wherein there are intermediate means which are arranged to intercept a signal from the inlet manifold pressure sensor means and effect an output which is according to a preselected output from the intermediate means in response to each level of input signal.

14. The arrangement of claim 10 wherein the means intercepting the information arising from the sensor within the inlet manifold to detect pressure is arranged so that it will have two states, one of which is to effect a modification in the output then being further fed to the electronic control unit of the engine so as to have this accord with an appropriate gas supplemented characteristic, and a second state in which the information coming from the inlet manifold sensor is passed straight through to the electronic control unit without modification but in addition, there is effected then a closure so as to stop further gas being introduced into the air inlet.

15. The arrangement of any one of claims 10 to claim 14 wherein the unit has externally accessible data storage means where such data storage can be programmed to keep a selection of operating programs.