WO2016026000A1

WO2016026000A1 - Internal combustion engine ignition plug

Info

Publication number: WO2016026000A1
Application number: PCT/AU2015/050473
Authority: WO
Inventors: Brett DI LELLO
Original assignee: Incontext Enterprises Pty Ltd
Priority date: 2014-08-19
Filing date: 2015-08-19
Publication date: 2016-02-25

Abstract

An combustion initiation plug for an internal combustion engine comprises an electrical connector for connection to an electrical current source and a body supporting a combustion initiator that operates when an electrical current passes through the electrical connector. The body comprises a passage radially extending from a portion of the combustion initiator which is internal to the plug. The plug further comprises an intake for receiving a combustion enhancer. The intake leads through a hollow chamber in the body and the passage to an opening into the combustion chamber to supply the combustion enhancer into the combustion chamber. A one-way valve or solenoid allows the combustion enhancer to flow through the hollow chamber into the passage, but prevents flow in the other direction.

Description

Internal Combustion Engine Ignition Plug

Field of the Invention The present invention relates to a combustion ignition plug, such as spark plug or a glow plug for an internal combustion engine.

Background Internal combustion engines are well-known and find commonplace use in motor vehicles, although they find use in many other applications as well. A common construction of an internal combustion engine comprises an engine block within which is a cylinder. A piston is positioned within the cylinder so as to move in a reciprocating manner under the power of combustion that occurs when a fuel-air mixture is ignited in a combustion chamber formed by the clear area not taken by the piston inside of the cylinder. The piston motivates a crankshaft which carries the power produced by the engine. A head closes the cylinder and comprises an air intake and a combustion exhaust outlet. Fuel is injected into the combustion chamber via the intake or more commonly now by a fuel injector. An intake valve is used to close the intake and an outlet valve is used to close the exhaust outlet.

Depending on the type of fuel used, which is typically either gasoline (petrol) or liquid petroleum gas (LPG), or diesel, different types of combustion initiation plug may be used. In the case of gasoline or LPG, a spark plug is used. In the case of diesel, a glow plug is used. It is known to produce improved combustion results by injecting combustion enhancers into the combustion chamber fuel through the existing fuel/air intake. A common combustion enhancer is nitrous oxide.

Combining of a fuel injector and a spark plug has been disclosed in US 6,955,154, however such fuel injector spark plugs don't seem to have enjoyed any commercial success.

A gaseous or liquid fuel delivery spark plug has been disclosed in US 2010/0012067, however such fuel delivery spark plug also does not seem to have enjoyed any commercial success.

The present pension has been developed in light of the foregoing. In this specification the terms "comprising" or "comprises" are used inclusively and not exclusively or exhaustively. Any references to documents that are made in this specification are not intended to be an admission that the information contained in those documents form part of the common general knowledge known to a person skilled in the field of the invention, unless explicitly stated as such. Summary of the Invention

According to an aspect of the invention there is provided a combustion initiation plug for an internal combustion engine comprising an electrical connector for connection to an electrical current source and a body supporting a combustion initiator that operates when an electrical current passes through the electrical connector, wherein the body comprises a passage radially extending from a portion of the combustion initiator which is internal to the plug, wherein the plug further comprises an intake for receiving a combustion enhancer, wherein the intake leads through a hollow chamber in the body and the passage to an opening into the combustion chamber to supply the combustion enhancer into the combustion chamber, wherein a one-way valve allows the combustion enhancer to flow through the hollow chamber into the passage, but prevents flow in the other direction.

In an embodiment an insulator lines the passageway. In an embodiment a conductor extends between the electrical connector and the combustion initiator, wherein the conductor lines the hollow chamber.

In an embodiment the one-way valve is disposed inside of the body. In an embodiment the one-way valve is disposed inside of the hollow chamber.

According to an aspect of the invention there is provided a combustion initiation plug for an internal combustion engine comprising an electrical connector for connection to an electrical current source and a body supporting a combustion initiator that operates upon an electrical current passing through the electrical connector, wherein the body comprises an intake for receiving a combustion enhancer, wherein the intake leads through a hollow chamber in the body to an opening into the combustion chamber to supply the combustion enhancer into the combustion chamber, wherein a first portion of the hollow chamber is lined with an insulator, wherein the combustion initiator in disposed within the first portion of the hollow chamber, wherein a second portion of the hollow chamber comprises a one-way valve that allows the combustion enhancer to flow through the hollow body into the passage in the threaded end, but prevents flow in the other direction.

In an embodiment a conductor extends between the electrical connector and the combustion initiator, wherein the conductor lines the second portion of the hollow chamber.

In an embodiment an air gap is provided between the insulator and the combustion initiator. In an embodiment the conductor substantially surrounds the one way valve. In an embodiment the intake is positioned at an end of the electrical connecter and extends axially into the connector.

In an embodiment the one-way valve is disposed inside of a threaded portion of the body. In an embodiment hollow body comprises an insulator portion between the threaded body and the electrical connector, wherein the insulator portion is adjacent to an annular inner wall of the threaded body. In an embodiment the one-way valve is disposed inside of the insulator portion.

In an embodiment the hollow chamber comprises a solenoid valve for controlling the flow of combustion enhancer through the hollow chamber.

According to an aspect of the invention there is provided a combustion initiation plug for an internal combustion engine comprising an electrical connector and a body supporting a combustion initiator that operates when an electrical current passes through the electrical connector, wherein the body comprises a passage radially extending from a portion of the combustion initiator which is internal to the plug, wherein the plug further comprises an intake for receiving a combustion enhancer, wherein the intake leads through a hollow chamber in the body and the passage to an opening into the combustion chamber to supply the combustion enhancer into the combustion chamber, wherein a solenoid valve controls the flow of combustion enhancer through the hollow chamber into the passage. According to an aspect of the invention there is provided a combustion initiation plug for an internal combustion engine comprising an electrical connector and a body supporting a combustion initiator that operates upon an electrical current passing through the electrical connector, wherein the body comprises an intake for receiving a combustion enhancer, wherein the intake leads through a hollow chamber in the body to an opening into the combustion chamber to supply the combustion enhancer into the combustion chamber, wherein the hollow chamber comprises a solenoid valve that controls the flow of combustion enhancer through the hollow chamber into the passage in the threaded end. In an embodiment the combustion initiator comprises electrodes and a spark gap for generating a spark wherein the combustion enhancer flows between the electrodes.

In an embodiment the combustion initiator is a heating element. In an embodiment the one-way valve is a check valve comprising a rounded head and a seat on the inside surface of the hollow chamber wherein the rounded head is able to make sealing contact with the seat. In an embodiment of the one-way valve comprises a biasing means for providing a biasing force urging the rounded head to make sealing contact with the seat. In an embodiment the biasing force is able to be overcome by pressurised flow of the combustion enhancer. In embodiment of the seat is provided at a neck of the plug disposed at a transition from the body to the connector.

In an embodiment the hollow chamber comprises a conductor extending from the electrical connector to the combustion initiator, so that the conductor extends around the one-way valve.

In an embodiment the hollow chamber comprises a conductor extending from the electrical connector to the combustion initiator, so that the conductor extends around the solenoid valve.

In an embodiment the combustion initiator comprises a vented connecter for holding the combustion initiator so as to extend through the threaded portion, or to extend from the threaded portion, wherein a vent of the vented connecter allows passage of the combustion enhancer from the hollow chamber to an outlet tube. In an embodiment the outlet tube is comprised of an inside surface of the threaded portion. In an alternative embodiment of the outlet tube extends from the body. In embodiment the combustion initiator extends through the outlet tube.

According to an aspect of the present invention there is provided an internal combustion engine comprising a combustion initiating plug as defined above.

In an embodiment there is an external solenoid valve is used to control the flow of the combustion enhancer to the intake. According to an aspect of the present invention there is provided a method of injecting a fluid combustion enhancer into an internal combustion engine, said method comprising:

receiving a combustion enhancer at an intake of a combustion initiation plug at a flow pressure;

during an intake stroke of the internal combustion engine, forcing a one way vale in a hollow body of the plug to open thereby allowing the combustion enhancer to flow through a gap radially extending from combustion initiator of the plug into the combustion chamber;

during a compression stroke and a power stroke of the internal combustion engine, closing the one way valve to close so as to prevent fluid flow through the plug. In an embodiment the flow of combustion enhancer is independent of the flow of fuel into the combustion chamber.

In an embodiment flow of combustion enhancer is controllable. In an embodiment flow of combustion enhancer is controlled in combination with control of fuel into the combustion chamber.

Summary of the Drawings In order to provide a better understanding, embodiments of the present invention will now be described with reference to the company drawings, by way of example only, in which:

Figure 1 is an elevation of a spark plug according to an embodiment of the present invention; Figure 2 is a cross-section elevation of the spark plug of Figure 1 ; Figure 3 is an elevation of a glow plug according to embodiment of the present invention; Figure 3 is a cross-sectional elevation of the glow plug of Figure 2;

Figure 5 is a schematic cross-section of an internal combustion engine comprising a combustion initiating plug according to an embodiment of the present invention, where the internal combustion engine is in an intake stroke;

Figure 6 is a schematic cross-section of the internal combustion engine of Figure 5 in a compression stroke;

Figure 7 is a schematic cross-section of the internal combustion engine of Figure 5 in a power stroke;

Figure 8 is a schematic cross-section of the internal combustion engine of Figure 5 in an exhaust stroke.

Figure 9 is a cross-sectional elevation of the spark plug according to an embodiment of the present invention; Figure 10 is a cross-sectional view of the spark plug through section A-A of Figure 9;

Figure 1 1 is an end view of the spark plug according to an embodiment of the present invention; Figure 12 is a cross-section elevation of the glow plug according to an embodiment of the present invention;

Figure 13 is an end view of the glow plug according to an embodiment of the present invention;

Figure 14 is a cross-section elevation of the spark plug in communication with an external solenoid valve;

Figure 15 is a cross-section elevation of the glow plug in communication with an external solenoid valve; Figure 16 is a cross-section elevation of the spark plug having a solenoid valve; and

Figure 17 is a cross-section elevation of the glow plug having a solenoid valve. Detailed Description of Embodiments of the Invention

Referring to Figures 1 and 2, there is shown a combustion initiation plug in the form of a spark plug 10 for an internal combustion engine. The plug 10 comprises a body comprising an insulator portion 12, a metal shell portion including a hexagon 14, and a threaded portion 18 for engaging with a combustion chamber head. The plug 10 also comprises an electrical connector 24 for connection to a high tension electrical conductor, and a combustion initiator in the form of a ground electrode 20 and a central electrode 22. The shell portion comprises a gasket 16 for sitting on an end of a threaded opening into the combustion chamber. From the exterior the plug 10 appears mostly the same as a conventional spark plug.

However the connector 24 has an opening 26 and is arranged to receive a hose for carrying a fluid (gas, liquid or combination of both) combustion enhancer.

The body comprises a chamber 28 leading from the opening 26 through the shell portion and the threaded portion 18 to an outlet 46 at the combustion chamber end of the plug 10. Inside the chamber 28 is a one-way valve, such as a check valve or alternatively a poppet valve. In this case the check valve comprises a rounded head 30 and a seat 36 which seals, thereby closing the valve when the head 30 is in contact with the seat 36. Thus the one-way valve is disposed inside of the insulator portion 12. In particular the seat 36 is disposed at a neck formed by a transition from the portion 12 to the connector 24.

A biasing means, in the form of a spring 32, urges the head 30 to contact the seat 36. An end of the spring 32 opposite the head 30 is backed by a plate 34. Plate 34 does not block a fluid flow into a portion 42 of the chamber 28 after the one-way valve.

Extending from the connector 24 to the electrode 22 is an electrical conductor 38. Typically the conductor 38 lines the chamber 28. In effect the conductor 38 may be regarded as a hollowed conventional spark plug, inside of which is the one-way valve. Conductor 38 is electrically connected to the electrode 22. In this embodiment the electrode 22 is positioned in the centre of the threaded portion 18. There is an air gap 44 between the electrode 22 and the metallic threaded portion 18. Figures 9 and 10 show an insulator 126 in the gap 44, wherein the insulator 126 is located at the inner wall of the threated portion 18, however the gap 44 provides a fluid connection between the portion 44 of the chamber 28 and the opening 46. Additionally, the insulator 126 surrounds the conductor 38 and forms the insulator portion 12. In one form the electrode is connected to the conductor 38 by a vented metallic disc 40. It would be appreciated by a person skilled in the art that the electrode 22 may be positioned at any location in the threaded portion 18 as shown in Figure 1 1 where it is offset from the centre of the threaded portion 18.

In operation, an electric current passing through the high tension lead attached to the connector 24 passes from the connector 24, through conductor 38 to electrode 22, which sparks across the gap between electrode 22 and ground electrode 20. Thus the spark plug 10 is intended to electrically operate in the same manner as a conventional spark plug.

Additionally in operation a fluid combustion enhancer is supplied to connector opening 26 which flows into channel 28. In the absence of sufficient back pressure, which will be explained further below, the pressure of the combustion enhancer forces the head 30 away from the seat 36, thereby allowing flow of the combustion enhancer into the channel portion 42 and in turn into gap 44 and then through opening 46 into the combustion chamber. During the compression stroke, the power stroke and in some embodiments during the exhaust stroke, fluid pressure inside chamber 42 substantially matches and then exceeds the fluid flow pressure of the combustion enhancer entering inlet 26. At this point this back pressure is sufficient for the spring 32 to overcome the combustion enhancer pressure causing the head 30 to move to contact the seat 36, thereby closing the valve. Additional back pressure just reinforces the sealing of the valve.

Referring to Figures 3 and 4, there is shown a combustion initiation plug in the form of a glow plug 50 for an internal combustion engine. The plug 50 comprises a body comprising a shell portion 52 including a hexagon 14, and a threaded portion 58 for engaging with a combustion chamber head. The plug 50 also comprises an electrical connector 64 for connection to an electrical conductor, and a combustion initiator in the form of a heating element 60 substantially inside a tube 62. The hexagon 54 is for engaging a hexagon socket spanner and has a seat 56 for sitting on an end of a threaded opening into the combustion chamber. From the exterior the plug 50 appears mostly the same as a conventional glow plug.

However the end of connector 64 has an opening 66 and is arranged to receive a hose for carrying a fluid combustion enhancer. The body comprises a chamber 68 leading from the opening 66 through the shell portion 52 to an outlet 86 at the combustion chamber end of the plug 50. Inside the chamber 68 is a one-way valve, such as a check valve or alternatively a poppet valve. In this case the check valve comprises a rounded head 70 and a seat 76 which seals, thereby closing the valve when the head 70 is in contact with the seat 76. Thus the one-way valve is disposed inside of the shell portion 52. In particular the seat 76 is disposed at a neck formed by a transition from the portion 52 to the connector 64.

A biasing means, in the form of a spring 72, urges the head 70 to contact the seat 76. An end of the spring 72 opposite the head 70 is backed by a plate 74. Plate 74 does not block a fluid flow in a portion 82 of the chamber 68 after the one-way valve.

Extending from the connector 64 to the heating element 60 is an electrical conductor 78. Typically the conductor 78 lines the chamber 68. In effect the conductor 78 may be regarded as a hollowed conventional glow plug, inside of which is the one-way valve. Conductor 78 is electrically connected to the heater element 60. The heater element 60 is positioned in the tube 62 that extends from the shell portion 52. There is an air gap 84 between the element 60 and the tube 62, although the element 60 may or may not extend from the end of the tube 62 as shown. In any case the tube 62 in open at outlet 86 to allow combustion enhancer to exit the gap 84 and enter the combustion chamber. There may fluid flow tubing inside of the tube 62 to facilitate fluid flow along the length of tube 62. Opening 80 allows the fluid to flow from chamber portion 82 into the and through the tube 62. Figure 12 shows an insulator 128 in the gap 84, wherein the insulator 128 is located at the inner wall of the tube 62, however the gap 84 provides a fluid connection between the portion 84 of the chamber 68 and the opening 86. Additionally, the insulator 128 surrounds the conductor 78 and forms the shell portion 52. It would be appreciated by a person skilled in the art that the heater element 60 may be positioned at any location in the tube 62 as shown in Figure 13 where it is offset from the centre of the tube 62.

In operation, an electric current passing through the conductor attached to the connector 64 passes from the connector 64, through conductor 78 to heating element 60, which produces heat, and then though tube 62 to the threaded portion 58. Thus the glow plug 50 is intended to operate electrically in the same manner as a conventional glow plug.

Additionally in operation a fluid combustion enhancer is supplied to connector opening 66 which flows into channel 68. In the absence of sufficient back pressure, the pressure of the combustion enhancer forces the head 70 away from the seat 76, thereby allowing flow of the combustion enhancer into the channel portion 82 and in turn into gap 84 and then through opening 86 into the combustion chamber. During the compression stroke, the power stroke, and in some embodiments during the exhaust stroke, fluid pressure inside chamber 82 substantially matches and then exceeds the fluid flow pressure of the combustion enhancer entering inlet 66. At this point this back pressure is sufficient for the spring 72 to overcome the combustion enhancer pressure causing the head 70 to move to contact the seat 76, thereby closing the valve. Additional back pressure just reinforces the sealing of the valve.

Referring to Figure 5, one cylinder portion of an internal combustion engine 100 is shown. The internal combustion engine 100 comprises an engine block within which is a cylinder. A piston 104 is positioned within the cylinder so as to move in a reciprocating manner under the power of combustion that occurs when a fuel-air mixture is ignited in a combustion chamber 102 formed by the clear area not taken by the piston 104 inside of the cylinder. The piston 104 motivates a crankshaft 1 14 which carries the power produced by the engine 100. A head closes the cylinder and comprises an air intake 106 and a combustion exhaust outlet 108. Fuel is injected into the combustion chamber via the intake 106, or alternatively by a fuel injector. An intake valve 1 10 is used to close the intake and an outlet valve 1 12 is used to close the exhaust outlet 108.

The fuel air mixture in the combustion chamber is ignited by the combustion ignition plug, in this case spark plug 10. In a diesel engine a glow plug would be used.

A combustion enhancer is injected into the internal combustion engine 100 by use of the plug 10. Fluid combustion enhancer 120 is received at the connector opening 26 of the plug 10 at a flow pressure. During an intake stroke shown in Figure 5, the combustion enhancer 120 forces the one way valve in the hollow chamber 28 of the plug 10 to open thereby allowing the combustion enhancer to flow through the plug 10 into the combustion chamber as indicated by 122. It can also be seen that similar to a traditional internal combustion engine, the valve 1 10 is open and a fuel air mixture enters the combustion chamber 102 via the intake 106. Exhaust valve 1 12 is closed.

As shown in Figure 6, valve 1 10 is closed during a compression stroke. Also during the compression stroke the one-way value of plug 10 is close as described above.

As shown in Figure 7, the plug 10 ignites the compress fuel air and enhancer mixture as indicated by 124. The downward motion of the piston drives the crankshaft 1 14. The combustion takes advantage of the addition of the combustion enhancer.

As shown in Figure 8 the exhaust valve 1 12 opens to allow combustion exhaust to exit via exhaust outlet 108. Depending on the configuration of the spring and or the fluid pressure of the combustion enhancer, one-way valve in the plug 10 may open. This may be useful to flush out exhaust. However the pressure caused by the exhaust stroke will typically keep the one-way valve in the plug 10 closed.

Typically the flow of combustion enhancer is independent of the flow of fuel into the combustion chamber and thus may be controlled by separate flow / mixture control mechanisms. In an embodiment flow of combustion enhancer may be controlled in combination with control of fuel into the combustion chamber by an engine management system. The combustion enhancer pressure may be controlled so as to control the delivered enhancer either manually or via an electronic or computer controlled mechanism. This enables specific volumes of combustion enhancer to be delivered to the combustion chamber. The addition of controlled measure of enhancer to the combustion chamber allows increased combustion efficiency and engine performance and or on demand additional engine power. It would be appreciated by a person skilled in the art that an external solenoid valve 130, 132 in communication with the intake 26, 66 via a conduit 134, 136 may be used to control the flow of combustion enhancer as shown in Figures 14 and 15. This has the advantage of preventing combustion enhancer from flowing into the combustion chamber at the bottom of the power stroke and the beginning of the exhaust stoke where the pressure of the combustion enhancer may exceed the pressure in the combustion chamber and the biasing force of the spring 32. The solenoid valve 130, 132 may also be used to meter the amount of combustion enhancer supplied or even whether it is supplied. The present invention applies to four stroke engines, as well as two stroke engines, or other forms of internal combustion engine. The present invention may use a solenoid valve 138, 140 instead of the one-way valve as shown in Figures 16 and 17. The solenoid valve may be in addition to the one way value such that the one way value is able to be robust enough to withstand the repeated pressurisation during compression and power strokes, whereas the solenoid value need only control the flow of combustion enhancer and thus need not be so robust.

The combustion enhancer may be oxidisers, catalysts, accelerants or propellants for mixture with the engines standard fuel within the combustion chamber. The combustion enhancer may be additional or different fuel (for example higher octane fuel) from that provided through the existing fuel / air intake.

The present invention may inhibit high frequency and high pressure backward flow created as a result of an engine's standard combustion process.

The present invention allows delivery of combustion enhancers without injecting them into the engine's standard/ primary fuel intake.

Modifications may be made to the present invention within the context of that described and shown in the drawings. Such modifications are intended to form part of the invention described in this specification.

Claims

1 . A combustion initiation plug for an internal combustion engine comprising an electrical connector for connection to an electrical current source and a body supporting a combustion initiator that operates when an electrical current passes through the electrical connector, wherein the body comprises a passage radially extending from a portion of the combustion initiator which is internal to the plug, wherein the plug further comprises an intake for receiving a combustion enhancer, wherein the intake leads through a hollow chamber in the body and the passage to an opening into the combustion chamber to supply the combustion enhancer into the combustion chamber, wherein a one-way valve allows the combustion enhancer to flow through the hollow chamber into the passage, but prevents flow in the other direction.

2. A combustion initiation plug according to claim 1 , wherein an insulator lines the passageway.

3. A combustion initiation plug according to claim 3, wherein a conductor extends between the electrical connector and the combustion initiator, wherein the conductor lines the hollow chamber.

4. A combustion initiation plug according to any of claims 1 to 3, wherein the one-way valve is disposed inside of the hollow chamber.

5. A combustion initiation plug for an internal combustion engine comprising an electrical connector for connection to an electrical current source and a body supporting a combustion initiator that operates upon an electrical current passing through the electrical connector, wherein the body comprises an intake for receiving a combustion enhancer, wherein the intake leads through a hollow chamber in the body to an opening into the combustion chamber to supply the combustion enhancer into the combustion chamber, wherein a first portion of the hollow chamber is lined with an insulator, wherein the combustion initiator in disposed within the portion of the hollow chamber, wherein a second portion of the hollow chamber comprises a one-way valve that allows the combustion enhancer to flow through the hollow body into the passage in the threaded end, but prevents flow in the other direction.

6. A combustion initiation plug according to claim 5, wherein a conductor extends between the electrical connector and the combustion initiator, wherein the conductor lines the second portion of the hollow chamber.

7. A combustion initiation plug according to claim 2 or 5, wherein an air gap is provided between the insulator and the combustion initiator.

8. A combustion initiation plug according to claim 3 or claim 4, wherein the conductor substantially surrounds the one way valve.

9. A combustion initiation plug according to any of claims 1 to 8, wherein the intake is positioned at an end of the electrical connecter and extends axially into the connector.

10. A combustion initiation plug according to any of claims 1 to 9, wherein the one-way valve is disposed inside of a threated portion of the body.

1 1 . A combustion initiation plug according to claim 10, wherein the hollow body further comprises an insulator portion between the threaded body and the electrical connector, wherein the insulator portion is adjacent to an annular inner wall of the threaded body.

12. A combustion initiation plug according to claim 1 1 , wherein the one-way valve is disposed inside of the insulator portion.

13. A combustion initiation plug according to any of claims 1 to 12, further comprising a solenoid valve for controlling the flow of combustion enhancer through the hollow chamber.

14. A combustion initiation plug for an internal combustion engine comprising an electrical connector and a body supporting a combustion initiator that operates when an electrical current passes through the electrical connector, wherein the body comprises a passage radially extending from a portion of the combustion initiator which is internal to the plug, wherein the plug further comprises an intake for receiving a combustion enhancer, wherein the intake leads through a hollow chamber in the body and the passage to an opening into the combustion chamber to supply the combustion enhancer into the combustion chamber, wherein a solenoid valve controls the flow of combustion enhancer through the hollow chamber into the passage.

15. A combustion initiation plug for an internal combustion engine comprising an electrical connector and a body supporting a combustion initiator that operates upon an electrical current passing through the electrical connector, wherein the body comprises an intake for receiving a combustion enhancer, wherein the intake leads through a hollow chamber in the body to an opening into the combustion chamber to supply the combustion enhancer into the combustion chamber, wherein the hollow chamber comprises a solenoid valve that controls the flow of combustion enhancer through the hollow chamber into the passage in the threaded end.

16. A combustion initiation plug according to any of the previous claims, wherein the combustion initiator comprises electrodes and a spark gap for generating a spark wherein the combustion enhancer flows between the electrodes.

17. A combustion initiation plug according to any of the previous claims, wherein the combustion initiator is a heating element.

18. A combustion initiation plug according to any one of claims 1 to 12, wherein the oneway valve is a check valve comprising a rounded head and a seat on the inside surface of the hollow chamber wherein the rounded head is able to make sealing contact with the seat.

19. A combustion initiation plug according to claim 18, wherein the one-way valve comprises a biasing means for providing a biasing force urging the rounded head to make sealing contact with the seat.

20. A combustion initiation plug according to claim 19, wherein the biasing force is able to be overcome by pressurised flow of the combustion enhancer.

21 . A combustion initiation plug according to claim 20, wherein the seat is provided at a neck of the plug disposed at a transition from the body to the connector.

22. A combustion initiation plug according to any of the previous claims, wherein the combustion initiator comprises a vented connecter for holding the combustion initiator so as to extend through the threaded portion, or to extend from the threaded portion, wherein a vent of the vented connecter allows passage of the combustion enhancer from the hollow chamber to an outlet tube.

23. A combustion initiation plug according to claim 19, wherein the outlet tube is comprised of an inside surface of the threaded portion.

24. An internal combustion engine comprising a combustion initiating plug as claimed in any of the previous claims.

25. An engine according to claim 24, wherein an external solenoid valve is used to control the flow of the combustion enhancer to the intake.

26. A method of injecting a fluid combustion enhancer into an internal combustion engine, said method comprising:

during an intake stroke of the internal combustion engine, forcing a one way vale in a hollow body of the plug to open thereby allowing the combustion enhancer to flow through a gap radially extending from a combustion initiator of the plug into the combustion chamber;

during a compression stroke and a power stroke of the internal combustion engine, closing the one way valve to close so as to prevent fluid flow through the plug.

27. A method according to claim 26, wherein the flow of combustion enhancer is independent of the flow of fuel into the combustion chamber.

28. A method according to claims 26 and 27, wherein the flow of combustion enhancer is controllable.

29. A method according to claim 28, wherein the flow of combustion enhancer is controlled in combination with control of fuel into the combustion chamber.