GB2336404A - Auxiliary air valve for i.c. engine fuel mixture control; carbon dioxide exhaust emission reduction system - Google Patents

Abstract

A valve is provided for admitting auxiliary air into an inlet manifold in dependence upon the level of vacuum in the manifold. The valve may comprise a body 10, a cap 20 with an air filter 23, a lock nut 30 and a valve member 40 biassed by a spring 50 against a seat 25 in the cap 20. A frustoconical end face 5 of the body 10 receives a frustoconical face 41 of the valve member 40 in the event of failure of the spring 50. The valve member 40 is made of a lightweight material and is shaped to enable air to flow easily around it so that the valve responds quickly to changes in pressure difference. Preferably, the valve provides a fuel/air ratio of between 14.4:1 and 14.7:1. The valve may be used in conjunction with a carbon dioxide filter, fig.5, placed in-line in the exhaust system and containing plates 103 of granulated lime and a charcoal filter 104.

Description

2336404 1 AN INTERNAL COMBUSTION ENGINE FUEL MIXTURE CONTROL APPARATUS AND

EMISSION REDUCTION SYSTEM The invention generally relates to a combustion mixture control apparatus for internal combustion engines which is achieved using an auxiliary air control mechanism f or controllably admitting air into an inlet manifold and thus the cylinders of an internal combustion engine. The present invention also relates to an exhaust emission control system which utilises the auxiliary air mechanism in combination with an exhaust filtering apparatus which f ilters carbon dioxide f rom the exhaust gas f rom an internal combustion engine.

In conventional spark ignition internal combustion engines, the manifold acts as a reservoir and distribution system for air which will subsequently enter the cylinders of the engine. The level of air entering the manifold is controlled either directly or indirectly by a valve known as a throttle and air entering the manifold will typically be mixed with a combustible mixture of fuel. The---precise method of fuel mixing varies with differing types of engine. However, typical methods of fuel mixing axe by carburettor, single-point or multi- point fuel injector, port fuel injection or a combination of more than one of these. Normally the engine is tuned in an attempt to make the engine operate 4 ball valve devices do not allow sufficiently large volumes of air to pass into the manifold to enable the optimum air-fuel mixture to be obtained.

It is an object of the present invention to provide a combustion mixture control apparatus for an internal combustion engine which reduces fuel consumption by controllably admitting air into the inlet manifold of the engine.

It is also an object of the present invention to reduce the emission of noxious gases utilising an auxiliary air valve and a carbon dioxide filter.

In one aspect of the present invention there is provided a combustion mixture control apparatus for a spark ignition internal combustion engine comprising an auxiliary air valve which is operable in dependence upon a pressure difference across the valve between the manifold and the atmosphere cause the air to fuel ratio taken in by the engine to be in the range of 13:1 to 15:1 and preferably in the range of 14.4:1 to 14.7:1.

Another aspect of the present invention provides an auxiliary air valve for spark ignition internal combustion engines which comprises a housing having a passage for admitting air therethrough to an inlet 3 to improve the combustion mixture during the operation of the engine. There are several devices in existence which attempt to control the fuel- air mixture supplied to the engine during the running of the engine which can be varied to meet the work demanded of the engine. Such devices are disclosed in, for example, GB 2213875, GB 1302565, GB 1519584 and GB 2129869. These devices provide a means whereby a valve controlled port allows additional air to be drawn into the manifold when required such that a suitable air-fuel mixture is obtained. These devices have, however, been found to have limited effectiveness.

Typically the existing devices comprise a tubular body for attachment to an inlet manifold or vacuum servoline of the manifold and a threaded cap which fits over the tubular body and has located within an end thereof a ball valve biased into an engagement with a valve seat by means of a spring. The ball valve is typically set to allow air into the tubular body and hence into the manifold inlet when the pressure within the manifold falls to levels below atmospheric pressure. The problem with the conventional devices is that the ball valve does not operate sufficiently fast to respond to changes in the air pressure in the manifold due to variations in engine operation. This slow response reduces the efficiency gained which can be achieved. Further, the 6 The valve can be formed of any suitable material such as plastic, nylon, acetyl, polymers, aluminium, alloys or a composite material.

In another aspect of the present invention there is provided an auxiliary air valve for a spark ignition internal combustion engine, the valve comprising a housing extending along an axis and having a passage extending therethrough along the axis for admitting air therethrough to an inlet manifold; a cap relatively movably attached to an end of the housing and having an orifice lying on the axis; and a spring loaded valve arranged for controlling the flow of air through the passage and comprising a valve for seating against the cap to seal the orifice and a spring extending along the axis between the housing and the valve for urging the valve away from the housing and against the cap; wherein the valve is arranged to seat against the housing around the passage in the event of failure of the spring.

This aspect of the present invention provides a failsafe arrangement whereby if the spring breaks, in order to avoid any level of vacuum resulting in air being drawn into the manifold thereby changing the fuelair mixture whenever there is a demand i.e. a vacuum created by the cylinders of the engine, the housing is provided with a valve seat and when the spring fails and the valve is not manifold of the engine and a valve means arranged to control the flow of air through the passage in dependence upon a pressure difference across the valve, wherein the valve means comprises a spring biased valve carrying a valve head formed of a low density material to provide the valve means with a low inertia to allow it to rapidly react to changes in pressure difference across the valve.

In one aspect of the present invention the device is provided witha valve biased into sealing engagement with an air inlet valve seat to prevent additional air entering through the air inlet of the device wherein the valve is openable by a reduction in pressure of the manifold inlet which serves to change the pressure of the device and hence draws the valve to an open position to allow a quantity of additional air into the inlet of the manifold. The valve has a main valve body of greater diameter than the diameter of the air inlet and a valve face for engaging the air inlet valve seat.

In addition to being relatively lightweight, the valve body is preferably shaped such as to allow a relatively fast speed of reaction to a change of air pressure within the manifold inlet and to allow for a rapid flow of air therearound.

8 be quickly drawn into the manifold and therefore the cylinders of the engine maintain an optimum fuel-air ratio thereby enhancing efficiency and reducing exhaust emissions.

In an embodiment the device is formed in two portions: a cap portion which comprises an opening defining the valve inlet which has a valve seat and body and a body portion which is provided with the passage allowing the passage of air therethrough. The cap portion of the device is movable in a direction to and away from the passage and a valve is arranged within the cap biased against the valve seat by a spring extending between the cap and the body. The cap portion is movable relative to the body portion in an embodiment by screwing and unscrewing of the cap portion on a screw thread of the body portion. This allows for the adjustment of the spring tension which thereby determines the pressure difference at which the valve will open. A locking means is preferably provided whereby when the cap portion is in the correct position relative to the body portion, it can be locked into position.

Thus the auxiliary air valve of the invention will act as a combustion mixture control apparatus to optimise or near optimise the air-fuel mixture in the manifold and thus the cylinders at all times during the operation of 7 forced away from the housing, it is arranged to be drawn by any vacuum level towards the housing and to seal against the valve seat of the housing thereby preventing the admittance of air into the manifold.

In the present invention the valve preferably comprises a one-way valve which is opened when the pressure in the manifold drops to a predetermined level compared to atmospheric pressure. The passageway through the valve housing in one embodiment preferably has a larger aperture at the valve end compared to the aperture at the end nearest the manifold. Such an arrangement serves to improve the flow of air through the valve and to provide a venturi action. In an embodiment of the present invention such an airflow is improved by the provision of the biasing spring along the axis of the passage. The presence of a helical biasing spring aids the generation of a swirling flow of air down the passage.

The shape and dimensions of the passage, and the valve and the biasing arrangement are such as to allow certain volumes of air to enter the device, and hence the manifold, in relation to the vacuum in the manifold such that the amount of air provided to the manifold by the device will allow the- engine to run at optimum conditions. The use of a lightweight valve designed to allow the free flow of air therearound allows for air to The carbon dioxide filter can comprise any known carbon dioxide filter such as a carbon dioxide "scrubber". Such a device can be provided as a cartridge containing granulated lime. Preferably the granulated lime is formed into plates providing a baffle to provide a large surface area for carbon dioxide absorption. The device can also be provided with activated charcoal to further reduce the emission of any hydrocarbons which have already been reduced by the use of the auxiliary air valve.

Embodiments of the present invention will now be described with reference to the accompanying drawings, in which: 15 Figure 1 is an exploded perspective view of a valve in accordance with an embodiment of the present invention; Figure 2 is a longitudinal sectional view of the valve shown in Figure 1; 20 Figure 3 is a side view of a manifold for an internal combustion engine illustrating the various positions at which the valve can be fitted; Figure 4 is a side view of an adaptor for receiving the valve in accordance with an embodiment of the present invention and which is positioned between the manifold and the vacuum assist system of the engine; and 9 the engine. This in turn will reduce the emissions of unburnt fuel and partially combusted fuel from the exhaust of the engine thus reducing the emissions of carbon monoxide and hydrocarbons into the atmosphere.

In order to further reduce the emissions produced by a spark ignition internal combustion engine, the present invention also provides in combination an auxiliary air valve for admitting air into the manifold of the engine when a predetermined vacuum is obtained in the manifold, and a carbon dioxide filter for filtering the emissions in the exhaust system of the engine.

In accordance with this aspect of the present invention, since the auxiliary air valve significantly reduces the emissions of hydrocarbons and carbon monoxide, i.e. since the majority of the emissions will comprise carbon dioxide, it is possible to contemplate using a carbon dioxide filter to reduce the emission of this gas which is widely attributed to the "greenhouse effect". Because the auxiliary air valve acts to control the fuel-air mixture ratio in the engine in such an efficient manner, the use of an expensive catalytic converter to reduce exhaust emissions is no longer necessary. The total emissions of the internal combustion engine, which will now comprise primarily carbon dioxide, can be reduced by the use of the carbon dioxide filter.

12 The main body 10 is provided with an axial passage 4 extending from an opening at an end adjacent the first threaded portion 1 to a larger opening adjacent the second threaded portion 3. The passage 4 comprises four sections of varying diameters. A first section 4a is of a narrow diameter and this communicates with a second portion between passage spring 50. A third portion 4c is of frustoconical section and acts as a transition portion between the second portion 4b and a fourth portion 4d which is of wider diameter. The fourth portion 4d of the passage 4 forms an opening at an end of the main body 10 adjacent to the second threaded portion 3.

4b which is of a wider diameter. The interface the first and second portions 4a. and 4b of the 4 provides a shoulder for engagement with the An end face 5 of the main body 10 between the opening formed by the fourth portion 4d of the passage 4 and the third threaded portion 3 is of frustoconical section for receiving a frustoconical face 41 of the valve member 40 in the event of failure of the spring 50.

The cap 20 comprises an internal threaded portion 21 for threadable connection to the second threaded portion 3 of the main body 10. The cap 20 is provided with an orifice 22 for the passage of air therethrough around the valve member 40 and into the passage 4. An air filter 11 Figure 5 is a schematic perspective view of the construction of a carbon dioxide filter cartridge in accordance with an embodiment of the present invention.

Referring now to the drawings, shown in Figures 1 and 2 is a valve assembly for controlling the combustion mixture in a spark ignition internal combustion engine in accordance with an embodiment of the present invention.

The device comprises a main body 10, a cap 20 for attachment to the main body 10, a lock nut 30 for locking the cap 20 in position relative to the main body 10, a valve member 40, and a spring 50 for biasing the valve member 40 into a closed position.

The main body 10 is formed of a first threaded portion 1 for threadably engaging either the manifold of the engine or the adaptor 60 of Figure 4 (as will be described hereinafter). The main body 10 also comprises a hexagonal portion 2 to allow for the engagement of a spanner to allow the main body 10 to be tightened into the adaptor 60 or the manifold of the engine. The main body 10 also has a second threaded portion 3 for threadable engagement with the lock nut 30 and the cap 20.

14 The valve member 40 can be formed of any lightweight material such as plastic, acetyl, nylon, polymers, aluminium, alloys or any composite material, and it is shaped to enable air to flow around it easily and thus provide the valve with a quick response to changes in pressure differences across it.

The spring force of the spring 50 will determine the pressure difference across the valve at which the valve will open. The spring force applied by the spring 50 can be adjusted by unscrewing or screwing the cap 20 relative to the main body 10.

In use the valve is adjusted at idling speeds such that the valve just does not open. The cap 20 can then be locked in position using the lock nut 30.

The shape and dimensions of the valve member 40 and the passage 4 have been designed such that air can flow rapidly around the valve member 40 and into the passage 4 and can provide a fuel-air mixture within the cylinders of the engine which is within the range of 14.4: 1 to 14.7:1.

Figure 3 is a diagram of a manifold 80 of an internal combustion engine and indicates the various positions at which the auxiliary air valve can be positioned. The 13 23 is provided in the cap 20 and held in position by a c-clip 24. Within the cap 20 around the orif ice 22 there is provided a valve seat 25 against which the valve member 40 seals when urged by the spring 50. The valve assembly is thus illustrated in its closed position in Figure 2.

The valve member 40 comprises a valve stem 42 arranged on the axis of the valve assembly and of a diameter such that it fits within the spring 50. The spring 50 thus urges against a shoulder portion 43 of the valve 40. A frustoconical portion 41 is provided for engagement with the frustoconical end face 5 of the main body 10 in the event of failure of the spring 50. In this way a failsafe mechanism is provided so that if the spring 50 should fail, any vacuum in the manifold will cause the valve member 40 to move towards the main body 10 such that the frustoconical portion 41 of the valve member 40 seals against the frustoconical end face 5 of the main body 10.

The valve member 40 is also provided with a planar face for engagement with the valve seat 25 of the cap 20. The valve member 40 has a further frustoconical portion 44 arranged within the orifice 22 to help direct the flow of air around the valve member 40 and into the passage 4.

16 emissions contain a higher percentage of carbon dioxide as a result of the use of the auxiliary valve, the inventor has realised that the exhaust emissions of the internal combustion engine can be reduced still further by the use of a suitable carbon dioxide filter instead of an expensive catalytic converter which is required conventionally in order to break down exhaust gases. Such a suitable carbon dioxide filter is illustrated in Figure 5 and this can be placed in-line in the exhaust system in the same way as a catalytic converter is used conventionally. The carbon dioxide filter comprises an inlet port 101 to receive exhaust gases and a deflector plate arrangement 102 which deflects the exhaust gases sideways. The exhaust gases are then made to flow over plates 103 of granulated lime in a baffle arrangement in order to absorb the carbon dioxide. At an outlet port 105 there is placed an activated charcoal filter for the removal of any residual hydrocarbons.

It can thus be seen that using the auxiliary air valve and the carbon dioxide filter in combination provides an emission reduction system for an internal combustion engine.

auxiliary air valve can be f itted to the brake servo vacuum line 81. Alternatively the auxiliary air valve can be directly fitted in a position 83 of the manifold 80. It has been found that it is sufficient to insert the auxiliary air valve at any position in the manifold since the air will rapidly disperse homogenously throughout the manifold. In yet another arrangement four auxiliary air valves can be inserted in the manifold 80 at positions 82a to d. This provides an increased air throughput where necessary in order to meet the demands of the engine.

Figure 4 illustrates another embodiment of the present invention wherein the body 10 of the auxiliary air valve is screwed in to an adaptor 60 which is placed in the vacuum line 70 of the engine. The vacuum line 70 can be secured to ports 61 and 62 of the adaptor 70 using suitable clips 71 and 72. This arrangement provides for a simple I'retro" fit to engines.

Since the auxiliary air valve controls the combustion mixture of the internal combustion engine such that the exhaust emissions contain far less unburnt and partially burnt fuel, the exhaust gases contain far less carbon monoxide as a result of more complete combustion and less carbon dioxide as a result of improved combustion efficiency. Thus having realised that the exhaust 18 wherein said valve means has a low inertia and reacts rapidly to changes in pressure difference thereacross.

5. A combustion mixture control apparatus according to claim 4 including a cap relatively movably attached to said body and having an orifice, wherein said valve head seats in said cap to close said orifice when said valve means is closed, said spring means reacts against said body and acts on said valve head, and the spring force provided by said spring means is adjustable by moving said cap relative to said body.

6. A combustion mixture control apparatus according to claim 5 wherein said spring means, said valve head, said body, said passage and said cap are arranged on a common axis, said cap is movable relative to said body along said axis. said spring means acts along said axis, said valve head has on one side thereof a first face for seating against said cap, and on an opposed side thereof a second face for seating against said body around said passage in the event of said spring means breaking.

7. A combustion mixture control apparatus for an internal combustion engine, the apparatus comprising:

a body having a passage for admitting air therethrough to an inlet manifold of the engine; and 17

Claims (1)

1. CLAIMS:

   1. A combustion mixture control apparatus for an internal combustion engine. the apparatus comprising: 5 a body having a passage for admitting air therethrough to an inlet manifold of the engine; and valve means arranged to control the f low of air through said passage in dependence upon a pressure difference across said valve means to cause the air to fuel ratio taken in by the engine to be in the range of 13:1 to 15:1.

   is 2. A combustion mixture control apparatus according to claim 1 wherein said valve means and said passage are arranged to admit air to cause the air to fuel ratio to be in the range 14:1 to 15:1.

   3. A combustion mixture control apparatus according to claim 1 wherein said valve means and said passage are arranged to admit air to cause the air to fuel ratio to be in the range 14.4:1 to 14.7:1.

   4. A combustion mixture control apparatus according to any preceding claim wherein said valve means comprises a valve head formed of a low density material, and spring means for urging said valve head to a closed position, wherein said valve is arranged to seat against said body around said passage in the event of said spring breaking.

   10. A internal combustion engine fuel mixture and exhaust emission control system comprising: a fuel mixture control valve for admitting air into an inlet manifold of the engine in dependence upon a pressure difference across the valve; and an exhaust emission reduction device for reducing emissions from an exhaust of the engine, the device comprising carbon dioxide removing means for removing carbon dioxide.

   11. A system according to claim 10 wherein said carbon dioxide removing means comprises lime arranged so that the exhaust gases of the engine pass thereover.

   12. A system according to claim 11 wherein said carbon dioxide removing means comprises plates of granulated lime arranged as baffles.

   13. A system according to any one of claims 10 to 12 wherein said fuel mixture control valve comprises the combustion mixture control apparatus of any one of claims 1 to 9.

   19 valve means arranged to control the f low of air through said passage in dependence upon a pressure difference across said valve means; wherein said valve means comprises a valve head f ormed of a low density material and spring means f or urging said valve head to a closed position, and said valve means has a low inertia and reacts rapidly to changes in pressure difference thereacross.

   8. A combustion mixture control apparatus according to claim 7 wherein said valve head is formed of one of plastic, nylon, acetyl, polymers, aluminium, alloys or a composite material.

   9. A combustion mixture control apparatus for an internal combustion engine, the apparatus comprising: a body extending along an axis and having a passage extending therethrough along said axis for admitting air therethrough to an inlet manifold; 20 a cap relatively movably attached to an end of said body and having an orifice lying on said axis; and a spring loaded valve arrangement for controlling the f low of air through said passage and comprising a valve for seating against said cap to seal said orifice and a spring extending along said axis between said body and said valve for urging said valve away from said body and against said cap; 21 14. A system according to any one of claims 10 to 13 wherein said carbon dioxide removing means includes activated charcoal.

   15. An apparatus substantially as hereinbef ore described with reference to any of the accompanying drawings.