Patent Description:
The fundamental theoretical principles of this idea have emerged and evolved from the long and detailed study and thorough scrutiny of structure and components of the internal combustion automotive engines, operation and thermodynamics of steps (strokes) of the 'Air Standard Power Cycles', effect of each stroke and contribution to reasons of the relatively low efficiency of their operation, etc..

Gasoline car engines operating on 'Air standard Otto Cycle' have an efficiency of between <NUM> and <NUM> %.

Diesel car Engines Operating on 'Air standard Diesel Cycle have an efficiency of between <NUM> and <NUM> %.

Large engines such as marine units have a higher efficiency which can reach <NUM>%.

However, two-stroke engines, have a lower efficiency which is seldom above <NUM>%.

A major portion of the energy released in gasoline and diesel engines is lost due to the hot exhaust gases and to the cooling water or cooling air used to cool the engines.

Design, structure and construction materials of the gasoline and diesel conventional engines have been continuously studied and developed for over <NUM> years, to obtain highest efficiency from the used fuels. Quality of fuels and the mode of operation of the two-stroke and four-stroke engines have also been developed and tuned to better control the timings and progress of each stroke and their synchronization (between different cylinders of the same engine).

Significant efforts have been made by many scientists, designers, researchers, inventors, and the like to further improve the efficiency of the internal combustion engines and many patents have been granted worldwide for a variety of claims. Many of them involve better control and timing of the operation, while others involve addition of new complicated parts and components and are difficult or very costly to implement or introduce into the existing engines. Some suggestions weaken the structure of engines and are actually not practical to implement. However, efficiency of the internal combustion engines has continued to generally remain low in terms of utilizing the released fuel energy.

Some example engines are disclosed in <CIT>, <CIT> or <CIT>.

Embodiments of the invention provide ways and means, which can increase extraction of the useful energy from fuels combustion and achieve higher efficiency of conventional engines, but also seek to minimise changes and modifications of their structure, construction, operation, and hence to:.

Embodiments of the invention modify conventional engines (both two-stroke or a four-stroke internal combustion engines) and significantly increase the efficiency and performance of those engines, and also improve the overall environmental effect of the automotive industry on environment.

Embodiments of the invention modify the cam shaft, or any alternate devices with the function of the cam shaft so that the opening and closing of the individual (and all) inlet-outlet portals (suction valves) of the involved engines, to extend (or reduce) opening of the said valves for a calculated and predetermined time, and also reduce the volume of combustion chambers by a predetermined and calculated amount.

Embodiments of the invention can be introduced into existing engines and have the advantages of:.

The modifications can be readily introduced into currently operating engines with acceptable level of costs (as compared with significant savings in the fuels and their costs), which can be confined to only replacing the existing engine cover (head) with another cover comprising embodiments of the invention.

Embodiments of the invention can also be applied to two-stroke engines and could actually increase the efficiency of those types of engines by higher margins and conservatively to above <NUM> %, with huge improvement of their environmental effect.

Embodiments of the invention allow modified engines (gasoline and diesel) to operate with <NUM>% to <NUM> % of the required fuel of unmodified engines, while they achieve more than <NUM> to <NUM> % of the power, as compared with the situation if the same engine is operated on conventional mode with <NUM>% fuel. Embodiments of the invention achieve this by creating conditions of extended expansion ratio of the combustion gases and subsequently reducing pressure and temperature of the exhaust gases from the current levels of over <NUM> Pascal (abs) (<NUM> Bar) to less than <NUM> Pascal (abs) (<NUM> Bar) and the exhaust temperature from the current levels of over <NUM> to less than <NUM>.

According to a first example not claimed, there is provided apparatus for controlling the volume of air inside a combustion chamber and cylinder of an internal combustion engine, comprising an inlet-outlet portal having open and closed states and connected to an air source; and combustion chamber with reduced volume; wherein the inlet-outlet portal is controlled, when open, to permit air to enter the combustion chamber and cylinder and when closed to prevent air from entering or exiting the chamber and cylinder, in which the volume of air located inside the chamber and cylinder when the inlet-outlet portal closes, is less than the volume of the combustion chamber and cylinder defined when the piston is at the bottom dead centre (BDC) position inside the cylinder when the inlet-outlet portal is closed. This embodiment has particular application to engines in which fuel is injected into combustion chamber separately from the air taken into the combustion chamber and cylinder during the intake stroke. Preferably the portal closes during the intake stroke when the piston head has moved to a position of between substantially <NUM>% to substantially <NUM>% of the distance from the top dead centre position towards the bottom dead centre position.

According to a second example not claimed, there is provided apparatus for controlling the volume of air inside a combustion chamber and cylinder of an internal combustion engine, comprising an inlet-outlet portal having open and closed states and connected to an air source; and combustion chamber with reduced volume; wherein the inlet-outlet portal is controlled, when open, to permit air to enter and exit the combustion chamber and cylinder and when closed to prevent air from entering or exiting the chamber and cylinder, in which the volume of air located inside the chamber and cylinder when the inlet-outlet portal closes, is less than the volume of the combustion chamber and cylinder defined when the piston is at the bottom dead centre (BDC) position inside the cylinder when the inlet-outlet portal is closed. This embodiment has particular application to engines in which fuel is injected into combustion chamber separately from the air taken into the combustion chamber and cylinder during the intake stroke. Preferably, the portal closes during the compression stroke of the piston when the piston head has moved to a position of between substantially <NUM>% to substantially <NUM>% of the distance from the bottom dead centre position towards the top dead centre position.

According to a third example not claimed, there is provided apparatus for controlling the volume of air and non-combusted fuel mixture inside a combustion chamber and cylinder of an internal combustion engine, comprising an inlet-outlet portal having open and closed states and connected to air and non-combusted fuel source(s); and combustion chamber with reduced volume; wherein the inlet-outlet portal is controlled, when open, to permit air and non-combusted fuel mixture to enter the combustion chamber and cylinder and when closed to prevent air and non-combusted fuel mixture from entering or exiting the chamber and cylinder, in which the volume of air and non-combusted fuel mixture located inside the chamber and cylinder when the inlet-outlet portal closes, is less than the volume of the combustion chamber and cylinder defined when the piston is at the bottom dead centre (BDC) position inside the cylinder when the inlet-outlet portal is closed. This embodiment has particular application to engines in which an air-fuel mixture is taken into the combustion chamber and cylinder during the intake stroke of the engine. Preferably the portal closes during the intake stroke when the piston head has moved to a position of between substantially <NUM>% to substantially <NUM>% of the distance from the top dead centre position towards the bottom dead centre position.

According to a fourth example not claimed, there is provided apparatus for controlling the volume of air and non-combusted fuel mixture inside a combustion chamber and cylinder of an internal combustion engine, comprising an inlet-outlet portal having open and closed states and connected to air and non-combusted fuel source(s); and combustion chamber with reduced volume; wherein the inlet-outlet portal is controlled, when open, to permit air and non-combusted fuel mixture to enter or enter and exit the combustion chamber and cylinder and when closed to prevent air and non-combusted fuel mixture from entering or exiting the chamber and cylinder, in which the volume of air and non-combusted fuel mixture located inside the chamber and cylinder when the inlet-outlet portal closes, is less than the volume of the combustion chamber and cylinder defined when the piston is at the bottom dead centre (BDC) position inside the cylinder when the inlet-outlet portal is closed. This embodiment has particular application to engines in which an air-fuel mixture is taken into the combustion chamber and cylinder during the intake stroke of the engine. Preferably, the portal closes during the compression stroke of the piston when the piston head has moved to a position of between substantially <NUM>% to substantially <NUM>% of the distance from the bottom dead centre position towards the top dead centre position.

Preferably, the inlet-outlet portal comprises an inlet-outlet valve.

According to a fifth example not claimed, there is provided an internal combustion engine comprising: at least one cylinder; at least one piston; a combustion chamber with reduced volume connected to the or each cylinder; at least one inlet-outlet portal for each combustion chamber having open and closed states and connected to an air or air and non-combusted fuel sources; a rotating cam to control each inlet-outlet portal; in which the cam is offset with respect to the bottom dead centre position of the or its respective piston.

According to a sixth example not claimed, there is provided an internal combustion engine comprising a substantially incompressible member located inside the combustion chamber of an internal combustion engine for reducing the volume of the internal combustion engine.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which:.

Referring to <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG> of the drawings, embodiments of the invention comprise an apparatus for modifying an engine which comprises a piston <NUM> housed within a cylinder <NUM>. However embodiments of the invention can be used to modify existing engines as well as converting conventional engines to operate according to embodiments of the invention, and so need not contain all the features of the engine.

The piston <NUM> is housed within the cylinder <NUM> so that the piston <NUM> is free to move within the cylinder. The piston is pivotally connected a liver <NUM> connection, which is in turn pivotally connected to a crankshaft (not shown). This connection of the piston <NUM> to the crankshaft converts the reciprocating motion of the piston within the cylinder to rotary motion of the crankshaft. This connection also limits the movement of the piston <NUM> within the cylinder between a position in which the piston head <NUM> (the face of the piston exposed to the combusted fuel or fuel and air) is furthest away from the crankshaft. This position is known as Top Dead Centre (TDC). The position of the piston head <NUM> within the cylinder such that it is closest to the crankshaft is known as Bottom Dead Centre (BDC). In reciprocating combustion engines, TDC defines the volume of the combustion chamber, and BDC defines the volume of the combustion chamber plus the volume of the cylinder. The piston is free to travel from the Bottom Dead Centre Position (BDC) to the Top Dead Centre Position (TDC) within the cylinder.

The seal between the piston and cylinder must be sufficiently good so that expanding combusted gases (during the expansion stroke of the engine as the piston moves from TDC to BDC) cannot escape between the piston and cylinder joint. Furthermore, the seal between the piston and cylinder must be sufficiently good so that it can contain the air or air and fuel mixture as this is compressed by the piston in the cylinder during the compression stroke of the engine as the piston moves from BDC to TDC.

The cylinder has a working volume which is equal to the volume traced out by the piston head as the piston head moves between BDC and TDC. Therefore the working volume of the cylinder will be the cross sectional area of the cylinder, for example the area of a circle if the cylinder has a circular cross section, multiplied by the distance between TDC and BDC. The volume of the cylinder is usually used as a measure of the power of the engine.

One end of the cylinder <NUM> is connected to a combustion chamber <NUM>. The combustion chamber is the volume into which air or air and non-combusted fuel is compressed when the piston reaches the TDC position. The combustion chamber has at one end an inlet-outlet portal <NUM>. Preferably the inlet-outlet portal comprises an inlet-outlet valve. The inlet-outlet portal has open and closed states and is connected to an air or air and non-combusted fuel source(s) via a pipe <NUM> preferably a suction pipe. Typically, if the inlet-outlet portal is connected to an air and fuel source, there will be one source for the air and a different source for the fuel. The two components will then be mixed before being supplied to the suction pipe. Also provided at one end of the combustion chamber is an exhaust valve <NUM>, shown in <FIG> in the open position, and a spark plug <NUM>. The exhaust valve <NUM> is connected to an exhaust pipe <NUM> so that combusted gas can be removed from the combustion chamber <NUM>. Usually, cams <NUM> mounted on a camshaft <NUM> will control the inlet-outlet portal <NUM> and exhaust valve <NUM>. However, any other apparatus may be used to control the opening and closing of the inlet-outlet portal <NUM> and exhaust valve <NUM>.

Embodiments of the invention modify the current design and operation of the reciprocating combustion engines, particularly, internal combustion engines (<NUM> stroke or <NUM> stroke) of piston and cylinder type, operating on the principles of 'Air Standard Power Cycles' such as 'Air Standard Otto Cycle' <FIG>, or 'Air standard Diesel Cycle' <FIG>. The said engines may use any of the fuels as the source of energy such as: natural gas, LPG, gasoline, kerosene, diesel fuel, light or heavy vacuum fuel, residue fuel, alcohol, bio fuel, hydrogen, combination of fuels or any other type of fuels. These are referred to as fuel. The modifications allow repeated operation of all the strokes of a full power cycle, for example four strokes (successions of: suction, compression, expansion and exhaustion strokes) in a manner which will result in the improved extraction of useful energy (thermal or mechanical) from the combusted fuels and thus improve efficiency and performance of these types of engines. In order to achieve this, embodiments of the invention modify conventional engines in two ways.

The piston and cylinder will usually be of circular section when viewed along the axis of movement of the piston. However, any shaped piston and cylinder could be used, for example oval or other shape.

Embodiments of the invention change (modify) the existing cam shaft, by increasing (extending) the circular span of the mechanism of the cam shaft (metal humps) or any alternate devices with the function of the cam shaft, in positions that control the opening and closing of individual inlet-outlet ports (suction valves) of the involved engines. Note that only the cams actuating the inlet-outlet ports need to be modified, and the cams actuating exhaust ports remain unmodified. The cams will normally be mounted on a camshaft. The modified cam comprises a portion which is substantially oval in cross section. Preferably, the cross section of the cam is substantially that of a Cartesian oval. The modification should be such to extend opening of each inlet-outlet port for the duration of the movement of the corresponding piston as follows:.

This movement of the piston will fill the said cylinder with air-fuel mixture, or just air in cases of injection type fuel supply, and in the case of pressure charging air-fuel mixture, opening of the inlet-outlet port will allow feeding the cylinder with air-fuel mixture. The air will normally comprise atmospheric air, which has a composition, at <NUM> degrees Celsius and one atmosphere pressure, of approximately <NUM>% Nitrogen, <NUM>% Oxygen, <NUM>% Argon, and less than <NUM>% carbon dioxide, Neon, Methane, Helium, Krypton, Hydrogen and Xenon in descending quantities by volume. However, other compositions of air can be used provided they comprise at least a proportion of Oxygen. c- Continue to keep the inlet-outlet port open while the piston had reached the BDC and turned to move back toward the TDC and covers a distance of, ideally but no necessarily, <NUM>% to <NUM>% of the distance between the BDC and TDC,.

This movement of the piston will evict a proportional volume of air-fuel or just air from the cylinder through the still opened inlet-outlet port back into the air-fuel supply pipe. When cams are used to actuate the inlet-outlet portal, this is achieved by extending the cam as shown in the modified cam in <FIG>, so that it is offset from the BDC position of the piston. In this way, the inlet-outlet portal is controlled so that it is open for at least a portion of the first part of the compression stroke so that air or air and fuel mixture exits the combustion chamber and cylinder through the inlet-outlet portal. As shown in <FIG>, the modified cam is extended so that as it rotates clockwise, the extended hump of the cam shown as Z will force the inlet outlet portal to remain open as the piston moves from BDC to TDC, so that some air or air and fuel exits from the combustion chamber and cylinder. In this embodiment, the modified cam actuating the inlet-outlet portal opens the inlet outlet portal at point Y in <FIG>, at the normal time, which will usually when the piston head reaches TDC at the end of the exhaust stroke.

The evicted air-fuel mixture will not have undergone a noticeable change of composition, (probably with little higher CO<NUM> content and higher temperature). This air-fuel mixture will mix with the other incoming fresh mixture being received from the carburetor or air supply pipe and air filter, and will be fed to the other cylinders of the said operating engine, which are or will be, performing the suction stroke (step),
d- Close inlet-outlet portal when the said piston reaches the predetermined position as per point (c) above,.

The mechanical modification of the cam shaft (or any alternate device with the function of cam) should be able to force the closure of the inlet-outlet portal at the moment corresponding to position of the said piston at the end of covering the predetermined distance described above, which is preferably about <NUM>% to <NUM>% from BTC to TDC.

Effect of the modified cam shaft mechanism (or alternate device) on operation of the <NUM> 'strokes' of the involved engines, is as follows:.

At the moment when the modified cam shaft, or any alternate device will force the closure of (closes) inlet-outlet portal of the said cylinder (as described in item c above), the piston will continue to move from point C toward the TDC and compress air-fuel mixture, or just air in the injection type engines. When the piston reaches TDC of the cylinder, the piston compresses the full volume of air-fuel mixture or just air from the cylinder into the combustion chamber and achieves the predetermined and required 'Compression Ratio' of the air-fuel mixture, or just air.

Referring to <FIG>, for a conventional camshaft, the time duration of operation of the suction valve is about <NUM> angular degrees, while the crank shaft will move <NUM> angular degrees. For the modified cam shaft, time duration of operation of the inlet-outlet port will be approximately <NUM> + <NUM> = <NUM> angular degrees, while crank shaft moves <NUM> angular degrees.

In this manner the inlet-outlet portal is expected to stay open for about <NUM> to <NUM> angular degrees of the full one revolution of the crank shaft, representing items a, b, c and d above.

During the remainder of that revolution (<NUM> to <NUM> angular degrees) inlet-outlet portal (and exhaust valve is in closed position) will be closed and piston will perform compression stage (section) of the compression stroke.

The most suitable distance for the piston to travel and achieve the desired compression ratio, will be optimised by the actual operation experience to achieve the highest efficiency, which could be less than <NUM>% or higher than <NUM>%.

In conventional engines, the expansion ratio is usually equal to the compression ratio, and is mostly:.

Hence, by dividing the working volume (length) of the cylinders of the intended engines between the TDC and BDC into <NUM> sections, namely:.

will provide and create an excellent opportunity to design and control the dividing line of these two sections in the cylinders in a manner to achieve extended economic expansion ratios, which could be:.

While high pressure of the combustion gases will continue to force the involved pistons to travel the full stroke from TDC to BDC (working length of the said cylinder) under favourable positive pressure of those combustion gases,.

In reality the dividing line of the eviction and compression section of cylinders of the intended engines, could be selected to provide Expansion Ratio at over <NUM>. However, the most practical dividing line of the eviction and compression section cylinders would be such, which will yield suitable and economic expansion ratio, highest efficiency and reliable and smooth operation of the said engine.

As the cam shaft in the gasoline <NUM> stroke engines makes one complete revolution for every <NUM> complete revolutions of the crank shaft, then the turning angular relation of these shafts, for the conventional and modified engines (cases) for a full Power Cycle (suction, compression, power stroke (expansion) and exhaustion) will be as follows in the table <NUM> below.

In a further embodiment, the same effect of eviction of air-fuel mixture into the supply pipe can be achieved by closing the inlet-outlet portal before the corresponding piston reaches the BDC by <NUM> to <NUM>%, which will lead to the said piston to move the remainder of the distance to BDC under partial vacuum.

Such a case will also involve modifying the system in a different manner, particularly the cam shaft hump, which controls or actuates the opening and closing inlet-outlet ports, will be reduced rather than to be extended as mentioned above, as shown in <FIG> (alternative).

In this way, the inlet-outlet portal is controlled by offsetting the cam from the BDC position of the piston. The portal is closed before the piston reaches the BDC position during the intake stroke of air or air and fuel. Closing the portal for at least a portion of the last part of the intake stroke means that the volume of air etc taken into the combustion chamber and cylinder when the valve closes is less than the total volume of the combustion chamber and cylinder when the cylinder is at BDC. However the modified cam still opens the portal at the beginning of the intake stroke, shown as point Y in <FIG>.

Of course, the piston will continue to move towards the BDC position even when the valve is closed. When the piston reaches BDC, the cylinder will contain air or air and fuel, with a volume which is equal to that of the volume inside the combustion chamber when the piston is at the bottom dead centre position inside the cylinder, but the pressure of the gas contained within that volume will be at a lower, assuming that this is carried out at constant enthalpy (internal energy). Therefore, the inlet-outlet port is controlled to permit air or air and non-combusted fuel at a pressure P and temperature T to enter or enter and exit the combustion chamber and cylinder, and when closed to prevent air or air and non-combusted fuel from entering or exiting the chamber and cylinder. The volume of air or air and non-combusted fuel located inside the chamber and cylinder at the pressure P and temperature T when the inlet-outlet portal is closed (and remains closed), is less than the volume of the combustion chamber and cylinder when the piston is at the BDC position inside the cylinder.

Referring to <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG> of the drawings, the volume of the combustion chamber is reduced, to restore the compression ratio. In the conventional engines, the compression ratio is the ratio of the volume of the cylinder and combustion chamber when the piston is at the BDC position to the volume of the combustion chamber when the piston is at the TDC position.

As volume of the air-fuel mixture left in the cylinders at the end of the suction and eviction process per modification No. <NUM> above is reduced, then a proportionate reduction in the volume of the relating combustion chamber is required. This restores the predetermined and efficient compression ratio of the air-fuel mixture in the involved cylinder (engine). Referring to <FIG> and <FIG>, this is be achieved by means of, but not limited to, the following measures:.

The materials chosen should have a high Bulk Modulus (incompressibility) and resist high temperatures. Typically, most types of steel will be adequate and usually steel, with a bulk modulus of ~<NUM>×<NUM><NUM> Pascal is sufficiently incompressible and resists higher temperatures. Any of these options provide the necessary conditions, which will allow to achieve the required and predetermined compression ratio for the air-fuel mixture, while the relevant piston will move a predetermined distance from the point (moment) of closure of the inlet-outlet portal (as described in the modification No. <NUM> above) to TDC, which could be about <NUM>% to <NUM>% of the distance between BDC and TDC, such as the distance from point C to TDC - <FIG> and <FIG>.

Compression ratio of the air-fuel mixture is a very important parameter in operation of 'Air Standard Cycles', and is usually selected based on the main objective to achieve the best efficiency (performance) from the fuel used in the intended engine under reasonably acceptable (controlled) operation conditions. The current levels of compression ratios are:.

The required volume reduction of the combustion chambers for any modified engine therefore, should be such that when any piston travels the remainder of the distance of the relating cylinder, from the position where the inlet-outlet portal of that cylinder was closed (as described above) to the TDC (travels about <NUM>% to <NUM>% of the full stroke), will achieve the predetermined compression ratio. The achieved compression ratio should be similar to the compression ratios of operation of the conventional engines (Air Standard Otto Cycles or Air Standard Diesel Cycles).

Determination of the required reduction to a specific combustion chambers of an engine could be estimated as follows:.

By closing the inlet-outlet ports at <NUM>% distance of the relating pistons stroke from BDC to TDC for the modified engines, will mean that the said pistons have evicted about <NUM>% of air-fuel mixture (or just air in cases of injection engines) from the corresponding cylinders back into the feeding pipe, and the cylinders are only half full of the air-fuel mixture. Hence, without the reduction of volumes of the combustion chambers, will mean that when the said pistons had reached the TDC of the relating cylinders, the achieved compression ratio will be only about half of what is required level, as follows: <MAT>.

This is not a good and efficient compression ratio for operating 'Air Standard Otto Cycle' and will result in significant energy losses, particularly with the exhausted combustion gases. The physical reduction required of size of the combustion chamber to restore the compression ratio at <NUM> for an engine of <NUM> cc size with <NUM> cylinders of <NUM> cc working volume each, will need to be reduced to: <MAT>.

Hence, compression ratio (C R) of the modified engine (cylinder) will be restored to: <MAT>.

This compression ratio of the modified cylinder will give a corresponding 'Expansion Ratio' in the same cylinder from TDC to BDC of the cylinder as follows: <MAT>.

This is a significant increase in the expansion ratio and will provide suitable operation conditions to extract significant amount of additional energy (mechanical or thermal) from such a 'Power Cycle'.

To achieve even a higher expansion ratio of the operating engines, it will be required to proportionally and physically reduce the size of combustion chamber, and reduce the volume of the compressed air-fuel mixture in the cylinder.

Fore example, if it is required to have expansion ratio of <NUM>, for the above cylinder, the required physical reductions in the volume of combustion chambers (Vc), will be estimated as:.

Volume of the working air-fuel mixture to achieve compression ratio of <NUM> in this combustion chamber will be calculated from the following equation: <MAT> Vaf - is the working volume of air-fuel mixture in the cylinder, <MAT>.

This amount of air-fuel mixture will be only <MAT>.

Of the full cylinder size (volume), when operated on the conventional mode of operation (without modifications).

By restoring the compression ratio of the gas-fuel mixture in gasoline engines - say to <NUM>, for only half distance of piston movement between the BDC and TDC and half of the working cylinder volume of air-fuel mixture, will allow the combustion gases to achieve an extended expansion ratio of <NUM> to <NUM>, and operate (move) the piston by positive pressure of the combustion gases for much longer distance (time) as compared with the current engines, as follows;.

Operation conditions at this point of operation of the modified engines (when the piston is at the middle part of the cylinder), correspond to the moment of operation of the conventional engines, when the piston approaches BDC of the cylinder and the exhaust valve opens to reject the combustion gases,
ii. However, as the piston is approximately in the middle of the cylinder, it will continue to travel the other half of the cylinder to the BDC, and also under the continued action of high pressure of the combustion gases (very favourable conditions), which will expand further for another expansion ratio of about <NUM> to <NUM> (or even to <NUM>). This will help to extract significant amount of additional useful mechanical energy from the combustion gases and improve the overall engine efficiency and performance.

Pressure and temperature conditions of the combustion gases at the start and the end of this section of the expansion stroke are expected to be as follow:.

Hence, the said engine will operate on only <NUM>% to <NUM> % of the designed amount of the fuel, while it could be capable to achieve <NUM>% to <NUM> % of the designed horse power of the same engine at the same RPM, (if it was working per the conventional power cycle). This entails that the engine will be capable to move the car for which it has been designed for much longer distance per litre of the used fuel (more kms). Embodiments of the invention improve the engine efficiency by more than <NUM>% as compared with the current operation (assuming the reference efficiency of the current gasoline engines as <NUM> %, as will be shown in the example).

Introduction of this modification No <NUM>, (Physical reduction of the Volume of the Combustion Chambers) into both the existing and future engines, could be achieved as follows:.

The modifications are introduced into the existing vehicles by means of:.

The modification issues will be more simple and straight forward. They could be included with skilful engineering designs and measures.

It is important to mention that most of the required modifications could be confined to the cover (head) part of the engine including the cam shaft modification. It is possible to just remove the engine head of the existing vehicle and perform the necessary modifications, or simply replace it with an already similar and modified engine head, and the modified car engine can be operated with significantly improved efficiency.

For the fuel injection type engines, modification of injection mechanism will be required to adjust the fuel injection per the modified operation volume of the air in the combustion chambers.

Embodiments of the invention modify current operating engines (such as gasoline or diesel engines) are not complicated, but rather simple and:.

Theoretically the expansion ratio could be made very high and as high as <NUM>. However practically it should be optimized so that the involved engine will produce the highest mechanical and thermal efficiencies and performances and maintain the smooth operation of the engine,.

According to the available theoretical information, the most economic expansion ratios, are expected be:.

• Extract significant additional useful energy (probably over <NUM>%) from the released energy of the fuel (in the combustion gases), which could increase the Net extracted useful energy (mechanical efficiency) from the current levels:.

To properly explain the novel idea and to show how the improvement in efficiency and performance of the involved 'Air Standard Cycles' is achieved, will require a detailed analysis and explanation of components and operation of a full 'Power Cycle' (for example for a <NUM> stroke gasoline engine) per the following steps:.

Referring to the <FIG> and <FIG>, it should be stressed that description of the <NUM> stroke gasoline engines, carburetor type operating per the 'Air Standard Otto Cycle' is well known in the automotive industry, and the following description, is mainly for the purpose of the necessary comparison between operation of the conventional engines and operation of the same engine with the modifications.

Each function of the <NUM> (four) strokes of the conventional engine is usually completed during a full stroke of the piston (movement of the said piston from one end of the cylinder -say TDC to the other end BDC). These strokes are:.

Hence, piston by reaching the TDC at the end of the exhaust stroke, the full power cycle will be completed and another cycle will start immediately and in the same manner, as described in the steps a to d above. The cycles will repeat over and over during the operation of the said engine and could last sometimes for days or even years.

Due to many factors of operation of the 'Air Standard Otto Cycle' and 'Air Standard Diesel Cycle', and particularly the very high temperature of the combustion gases at the start and during the 'Power Strokes', which could reach (instantaneously) over <NUM> (<NUM>), leads to significant losses of the released thermal energy from fuel combustion. Generally the released thermal energy of the fuel is divided into two major parts, which are:.

Ratio of the used useful energy Eu to the total released energy Et expresses the engine Net efficiency as follows: <MAT>.

Current level of efficiencies ( η ) of the conventional 'Air Standard Power Cycle', operating under favourable conditionals, are:.

This means that a significant portion of the fuel energy (actually the majority portion) is lost during operation of the current conventional gasoline and diesel engines, and could not be used (for example) to move the intended vehicles, and is usually lost is the form of:.

Approximate breakdown (distribution) of the released energy between the outlets (components) in operation of the conventional engine, are usually as follows:.

The above table shows that the major part of the released energy is lost to the exhaust gases and to the cooling water. The medium size gasoline car engines (of <NUM> cc to <NUM> cc) seldom achieve above <NUM> to <NUM> per litre, while the same size diesel cars can achieve about <NUM> to <NUM> per litre. Even in ideal conditions the manufacturers may claim little higher performance.

Hence, an amount of energy equal to moving the same car for about <NUM> to <NUM> per liter is lost mainly to atmosphere (combustion gases and cooling water).

To show, explain and substantiate the expected claimed improvements of engine efficiency and performance, the case will require to analyse the involved thermodynamics, operation and work principles of both the conventional 'Air Standard Otto cycle' and the modified 'Air standard Cycle', explain the modifications and compare the achieved results.

Accordingly, the following description will include and show:.

The principle of compressing air-fuel mixture to the required compression ratio is applicable to both conventional engines and also to engines with the modifications.

For operation of the conventional engines, compression of the air fuel mixture takes place by the movement of the relevant piston from BDC and when the piston reaches TDC, will complete the compression stroke and pushes the entire amount of the air-fuel mixture, or jut air, into the combustion chamber. This process requires significant amount of energy and causes the adiabatic rise of both temperature and pressure. Theoretical pressure increase will be according to the following equation: <MAT> Where:.

Hence, for the 'Air Standard Otto Cycle' with compression ratio of <NUM>, the developed pressure and temperature of the compressed air-fuel mixture at the end of the compression stroke will be:
Pressure P<NUM>: <MAT> <MAT>.

Temperature of the compressed air-fuel mixture will also increase adiabatically, and will be increasing according to the following equation: <MAT>.

Assume the suction temperature (atmospheric Temperature) is <NUM> <NUM>C ( <NUM>), then the theoretical temperature at the end of the compression stroke will be: <MAT> <MAT>.

As could be noticed, this stroke requires significant amount of mechanical energy to increase the pressure and temperature of the compressed air-fuel mixture. The required power is usually provided by the Power Stroke of another cylinder (or fly wheel), but will then be released as part of released power during the subsequent Power Cycle of the said cylinder, which results in a balanced situation, except for some losses.

Compression stroke (process) will be performed for engines with the modifications, in the same manner as described for the 'Air Standard Otto Cycle' with the associated corresponding energy requirement and pressure and temperature increases.

The major difference is in the actual volume of air-fuel mixture in cylinders of exactly the same stroke and bore (same size). As mentioned for the suction stroke (inlet-outlet stroke), the cylinder will be only about <NUM>% full with air-fuel mixture of the full working stroke -plus the combustion chamber.

Hence, if the volume of air-fuel mixture in the conventional cylinder will be twice that of the air-fuel mixture for the modified cylinder and are compressed to the same compression ratio, then obviously the required energy for performing the compression ratio will also be twice for the conventional engine. However, there will be little difference in the net energy requirement, as most of the spent energy for compression is recovered during the subsequent expansion (power) stroke.

As for the pressure and temperature at the end of compression section, they will be similar to the pressure and temperature of the conventional 'Air standard Otto Cycle' as follows (if same compression ratio is applied):.

During this stroke, two simultaneous processes will take place, for both the conventional and the modified engines, they are:.

However, the major differences between 'Air Standard Otto Cycle' and 'Air Standard Diesel Cycle' are:.

Amount of fuel used (supplied to the engine) for the normal operation of 'Internal Combustion Engines' (for speeds of <NUM> to <NUM>/h) is such to produce about <NUM> to <NUM> Joule (<NUM> to <NUM> cal) per litre of air, to achieve air to fuel ratio of about <NUM> to <NUM>).

For analysis of this 'Power Cycle', it is assumed:.

This energy supply to the intended engine is normally related to the weight ratio of air to hydrocarbon fuel mixture at: <MAT>.

This rate is relatively high as compared with the ideal ratio of air to fuel of: (<NUM> to <NUM> ) / <NUM> ; which provides:.

Furthermore, the high air to fuel rate ( <NUM> / <NUM> ) will cause significant energy losses as it means heating additional amounts of air -more than <NUM> to <NUM> % above the ideal rate, from <NUM> to over <NUM> and exhausting to atmosphere.

The supplied thermal energy, assumed at <NUM> Joule (<NUM> cal) per litre, will raise temperature of the compressed (and combusted) gases in the combustion chamber instantaneously and very sharply. Theoretical increase of temperature from combustion of fuel in the combustion chamber (Ticrease), assuming an instantaneous release of energy, will be: <MAT>.

Overall combustion gases temperature (theoretical) at the end of the full combustion of fuel Tth com, assuming ideal conditions, will be : <MAT>.

Note : Theoretical ideal temperature (Tth id) under conditions of ideal air to fuel ratio of <NUM>, will be significantly higher and over <NUM>:
Temperature increase of the combustion gases in the combustion chamber will result in the pressure increase, per the ideal gas equation, under constant volume V : <MAT>.

Hence, the theoretical pressure and temperature after fuel ignition and start of the 'Power Stroke' of the conventional 'Air standard Otto Cycle' will be:.

However, from the practical experience of operation of 'Internal Combustion Engines', both the combustion gas temperature and pressure are significantly lower than these levels, because of:.

Actual highest temperature and pressure of operation of the gasoline engines could be lower by as much as <NUM> to <NUM> % than the theoretical highest values (per the 'Air Standard Otto Cycle'),.

Air-fuel ignition (or auto-ignition in the case of diesel engines), energy release and pressure increase described before, for the 'Air Standard Otto Cycle' will also be performed in the same manner for engines with the modifications.

Again the major difference is in the actual volume of air-fuel mixture in cylinders of exactly the same stroke and bore (same size). As mentioned before the said cylinder will be only about <NUM>% full with air-fuel mixture of the full stroke - plus the combustion chamber.

As for the pressure and temperature after fuel ignition and start of the 'Power Stroke' will be similar to the pressure and temperature of the conventional 'Air standard Otto Cycle'.

The main thermodynamic difference between operation of the conventional and modified engines occur in the expansion stroke as follows.

Expansion of combustion gases for both the conventional and modified engines starts immediately after the piston had passed the TDC and moves toward the BDC. Expansion of the combustion gases will also take place adiabatically and will be per Equations <NUM> and <NUM> (mentioned before).

In reality, the actual temperature at the end of the expansion stroke and the start of exhaust stroke, is significantly higher (by as much as <NUM> to <NUM>%) than both of these temperatures, due to the fact that combustion of the air-fuel mixture could still be in progress, while the piston is close to the BDC.

Assume: Exhaust temperature of the combustion gases is about <NUM> <NUM>K.

Exhausted Energy (Eex) with combustion gases will be: <MAT>.

Note : Specific heat of the combusted gases is expected to be little higher at higher temperatures, <MAT>.

This is a very substantial amount of energy, which is lost with exhaust gases.

A-<NUM> Pressure at the end of the expansion stroke at point E, (PE) with the assumed pressure of <NUM> Pascal (<NUM> Bar) at the start of the expansion stroke (conventional engine), will be per eq. <NUM>: <MAT> <MAT>.

However, the actual pressure at the end of the expansion stroke PD, will be significantly higher due to the very high temperature of the combustion gases at the end of the expansion stroke, and will be: <MAT>.

This is again a very high pressure and could perform proportionate mechanical work, if it could be beneficially utilized, particularly as it is applied to the full volume of the cylinder of combustion gases.

The modification of the engine, addresses this exact issue and try to utilize most of this available (but currently lost) mechanical work (energy), prior to expelling the combustion gases to atmosphere, as explained below.

Points C to D then to E on Figs No <NUM>, <NUM>, <NUM> and <NUM>,.

Combustion gases continue to expand adiabatically, under controlled conditions by another <NUM> times of the size of the combustion chamber (from point D to point E on the <FIG> and <FIG>) starting from the end point of the conventional cycle expansion section. This will assist to complete combustion process of the introduced fuel and significantly reduce the exhaust temperature, as shown below:.

However, the real exhaust temperature will be slightly higher, due to the much longer time of combustion, and could be (conservatively) at about <NUM> to <NUM>.

This is a very significant reduction of the exhaust temperature of the expelled gases and the associated thermal energy. Exhausted energy with combustion gases with the modifications will be (assuming the exhaust temperature at high <NUM>): <MAT> <MAT>.

Saved amount of thermal energy will be : <MAT>.

By all measures and considerations, this is a very significant reduction in the expected exhausted thermal energy, and could be utilized usefully to move the intended vehicles.

B-<NUM> Theoretical pressure at the end of the modified expansion (adiabatic) stroke Pth,mod, will be : <MAT> <MAT>.

B-<NUM> Expected pressure at the end of the modified expansion (adiabatic) stroke Pmod with the assumed initial temperature at the start of expansion stroke of <NUM>, will be : <MAT> <MAT>.

However, the actual pressure at the end of the expansion stroke Pa will be slightly higher than both of these pressures, depending on the exhaust temperature, and conservatively could be at about <NUM> to <NUM> Pascal (<NUM> to <NUM> Bar), due to higher exhaust temperature.

On <FIG> and <FIG> the area from point D to Point E to point F to point A and back to point D represents the additional useful energy, which will be added to the conventional engine useful energy between the point A to point B, to point C, to point D and back to point A. This area could represent a major input and will significantly improve the operation efficiency and parameters of the vehicles.

Note: For injection cars, the injection of fuel will need to be tuned also with the modification of the actual amount of air to fill <NUM>% to <NUM>% of the cylinder size:.

Summary of the temperature and pressure for the two 'Power Cycles' at the end of expansion stroke are:.

The above data show a significant improvement (reduction) in the temperature and pressure of the combustion gases at the end of expansion stroke and start of the exhaust stroke.

The table shows significant increase of thermal efficiency of the modified engine to <NUM>% as compared with efficiency of the conventional engine of <NUM> %, with the increase of about <NUM> %. Reduced temperature of the engine operation by more than <NUM> will in turn reduce the energy lost with cooling water by several percents (probably by more than <NUM>%) and will result in an overall improvement of the gasoline engines operation efficiency by over <NUM>% (of the net energy input) as compared with current operation of the 'Air Standard Otto Cycle'. A near similar improvement in the efficiency in operation of 'Air Standard diesel Cycle' could also be expected.

(This could be tested and further improved in actual experience).

Below is the comparison of distribution of the released energy between the major outlets (components) in operation of the conventional engines and the expected distribution from operation of the modification, is as follows in table <NUM>.

The modifications significantly increase efficiency and performance of the involved engine (even much higher than those shown in the above tables) and subsequently increase the km per litre for the automotive industry. The modifications are very useful in the operation of larger engines, such as the Diesel Power stations, which operate on light and heavy Vacuum Gasoil (ship engines) with cylinder bore and stroke of over <NUM>. The reduced temperature of the exhaustion gases and extended expansion stroke are expected to noticeably improve the engine's efficiency and performance, in terms of:.

The modifications (when introduced into the existing cars) may slightly change engine's power, particularly in achieving very high speeds, of say over <NUM>/h. However, this may be a small price to afford as compared with significant expected savings in the purchase of fuels (LPG, gasoline, diesel, etc). It may also require a little larger 'fly wheel' to ensure a continuous engine operation at low parking RPMs of -say about <NUM> RPM.

The issue of sufficient performance (higher power and speed requirements) for the new engine, could be included directly in the designs, and should not pose a problem for expert designers.

<IMG> Case with Cylinder Filled <NUM>% at the start of compression stroke:.

To show the impact of a lower case of compression ratio, the same above analysis will be performed for a case when the cylinder is filled <NUM>% at the start of compression stroke.

With <NUM>% of the cylinder full of air-fuel mixture at the start of the compression stroke, the new compression ratio will be: <MAT>.

Temperature and pressure at the end of the compression stroke will be: <MAT> <MAT>.

The real exhaust temperature could be (conservatively) about <NUM> to <NUM>,.

This is a very significant reduction of the exhaust temperature of the expelled gases and the associated thermal energy. Exhausted energy with combustion gases with the modifications will be : <MAT>.

Per cent of the exhausted energy will be: <MAT>.

By all measures and considerations, this is also a very significant reduction, and could be utilized usefully to move the intended vehicles.

Theoretical pressure at the end of the modified expansion (adiabatic) stroke Pmod, will be : <MAT> <MAT>.

This pressure is also significantly lower than the experienced pressures with conventional operation of the 'Air standard Otto Cycle' (gasoline engines).

As could be seen, from <FIG> and <FIG>, further energy extraction (mechanical) from the combustion gases (beyond <NUM> compression ratios) within the cylinders may prove negligible or highly costly, as the pressure of the exhaust gases could actually be reduced to less than <NUM> Pascal abs (<NUM> bar) abs with compression ratios of about <NUM> to <NUM>.

Actual experience may prove that this residual positive pressure will be required, which is just enough to avoid creating a vacuum inside the cylinder under low RPM (parking conditions).

These analysis show, that a significant amount of additional energy could be extracted from the combustion gases and used to perform the useful mechanical work (to move the car) as shown in the extended expansion stroke on the PV diagrams <FIG> and <FIG>.

The 'Power Cycle' shown in the <FIG> and <FIG>, is a new type of 'Air Standard Power Cycles', which can significantly extend the expansion stroke of this Power Cycle beyond those of both the conventional 'Air Standard Otto Cycle' and 'Air Standard Diesel Cycle' and is substantially different from both of them.

This new power cycle re-organizes and re-designs the engines operation as follows:.

As could be noticed the new power cycle is substantially different from both of the conventional 'Air Standard Otto Cycle' and 'Air Standard Diesel Cycle'. It has it's own analytical characteristics and approach and of particular importance is the provision of high flexibility of the expansion ratio of the combustion gases. Controlling system and mechanism (cam shaft) could also be further tuned and controlled to have lower expansion ratios with lower RPM of the 'crank shaft' and higher expansion ratios with higher RPM, and also to control the exhaust pressure just above atmospheric pressure.

It is applied to operation of the reciprocating 'internal combustion engines', which have some or all the modifications introduced into their construction, and will provide operation conditions of higher efficiency and performance for the said engines. <FIG>, <FIG>, <FIG>,.

It is only fair that this new applied " Power Cycle " to be named as the: " Air Standard Atalla Modified Cycle ".

Engines operating on this 'Air Standard Atalla Modified Cycle' could be categorized and expressed in the actual practice as:.

And all other selected filling of the cylinders, as:
Atalla Mod <NUM>, Atalla Mod <NUM>, or Atalla Mod <NUM>, or Atalla Mod <NUM>, etc..

These are usually small type of engines and applied to motorcycles (fast moving vehicles). However, the modification could also be successfully applied to the two stroke engines and improve their efficiency, performance and the environmental issues associated with these types of engines.

The modification for 'Air Standard Otto Cycle' or the 'Air Standard Diesel Cycle', could also be applied to the two stroke engines. The modifications comprise also the mechanism on the cam shaft or any alternate devices with the function of the cam shaft, which controls the opening and closing of inlet-outlet portal, and the required reduction of size of the combustion chambers.

However, due to the different mode of operation of the two stroke engines, which could be characterized by: <FIG>,.

Hence, the modification will need to be applied skilfully and carefully to realize the expected improvements. Modification of the mechanism controlling opening and closing of the inlet-outlet portal should be applied (introduced) in a manner to allow the full power cycle (<NUM> strokes - for every one full revolution of the crank shaft) to run smoothly and trouble free also, as compared with the conventional operation, and improve the efficiency of the involved engines.

The increased efficiency of the two-stroke engine could be explained from the operation strokes of the modified engine as compared with the conventional engine, as follows:.

Ignition of the compressed air-fuel mixture commences the fuel combustion and significantly raises temperature and pressure of the combustion gases, which will expand and push the piston down from TDC to point C (<FIG>), or point A to point C on the angular path of the crank shaft (<FIG>),
Expansion ratio: <NUM> to <NUM>.

When piston reaches and exceeds Point C, it will also exceed the top line (edge) of the exhaust slot and the combustion gases still under high pressure and at very high temperature will start to exit (at very high speed) the respective cylinder into the exhaust pipe and then to outside atmosphere. The process will continue while the piston moves and reaches BDC (point D on <FIG>) and returns to move back towards TDC and reaches point D<NUM> (<FIG>) at which point the piston will pass the top edge of the exhaust slot and complete the exhaust process (stroke).

When piston reaches and exceeds Point C, it will also exceed the top line (edge) of the exhaust slot and the combustion gases still under high pressure and at very high temperature will start to exit (at high speed) the respective cylinder into the exhaust pipe and then to outside atmosphere. However, the exit pressure and temperature of the combustion gases are significantly lower that those of the similar conventional two-stroke engine. The process will continue while the piston moves and reaches BDC (point D on <FIG>) and returns to move back towards TDC and reaches point D<NUM> (<FIG>) at which point the said piston will pass the top edge of the exhaust slot and complete the exhaust process (stroke).

Air-Fuel mixture will be charged under positive pressure into the cylinder, and pushes the combustion gases through the exhaust slot into the exhaust pipe and outside. This process will continue until piston reaches point C (<FIG>) point D<NUM> (<FIG>). Although the replacement of the combustion gases will not be complete, but it is expected that most of the combustion gases will be pushed out of the cylinder.

Air-Fuel mixture will be charged under positive pressure into the cylinder, and pushes the combustion gases through the exhaust slot into the exhaust pipe and outside. This process will continue also until piston reaches point C (<FIG>) point D<NUM> (<FIG>). Although the replacement of the combustion gases will not be complete, but it is expected that most of the combustion gases will be pushed out.

This will allow the said piston to evict some air-fuel mixture from the involved cylinder, from point C to point C<NUM> (<FIG>), (from point D<NUM> to point E, <FIG>),.

Piston will compress air-fuel mixture into the combustion chamber and achieve the required compression ratio of <NUM> to <NUM>,.

Piston will compress air-fuel mixture (about <NUM>% to <NUM>% of working size of the conventional cylinders) into the combustion chamber and achieve the required compression ratio of <NUM> to9 (with the reduced volume of the combustion chamber),.

By introducing the modifications, operation of the same revolution will change slightly, but expected to significantly improve the engine's efficiency and performance. Hence, for every full revolution of the Crank Shaft (<NUM> angular degrees), starting from point A (<FIG>) the two strokes of the modified engine, as compared with two strokes of the conventional engine, as shown in table <NUM>.

Embodiments of the invention significantly improve operation of the two stroke engines, and in a similar manner as the modified <NUM> stroke engines, in terms of:.

Ironically, efficiency of the <NUM> stroke engines may be improved even by a higher margin than the <NUM> stroke engines and also significantly improve the environmental aspects of operation of the <NUM> stroke engines, in terms of much reduced noise and emission of CO<NUM> and noxious gases.

Compare performance of a conventional engine operating on 'Air Standard Otto Cycle' and the same engine modified and being operated on the 'Air Standard Atalla Modified Cycle' as per the following:.

Where <NUM>* represents the full <NUM> revolutions of the crank shaft to complete a full one power cycle , <MAT> <MAT>.

Where <NUM> is the conversion factor between the thermal and mechanical energies. m = <NUM> joule (<NUM> cal).

This horsepower is developed with the use of only <NUM>% fuel as compared with the 'Air Standard Otto Cycle'.

Hence, improved performance could be expressed as the achieved power in two 'Power Cycles' with the same size physical engine, for the same amount of fuel, <MAT>.

This is a very encouraging result and is believed to be achievable in practice or could even be further improved with development and selection of the most suitable engineering designs and operation conditions.

Improvement could be shown: If a current conventional car makes -say <NUM> per litre fuel, then with the modifications the same car will make about: <MAT> km per litre fuel.

The same engine (car) with modification will also develop <NUM> horse power (HP), by increasing the RPM from the assumed <NUM> RPM - in the example - to : (indicative only) <MAT>.

The same engine can also develop <NUM>,<NUM> horse power (HP), by increasing the filling the working volume of air-fuel mixture - in the example - to : (indicative only).

Claim 1:
An apparatus for modifying an internal combustion engine, wherein the internal combustion engine is operable to control the volume of air or air and non-combusted fuel mixture inside a combustion chamber (<NUM>) and cylinder (<NUM>) of said internal combustion engine, the internal combustion engine comprising:
(a) an inlet-outlet portal (<NUM>) having open and closed states and connected to air or air and non-combusted fuel source(s);
(b) a combustion chamber (<NUM>);
(c) a cylinder (<NUM>); and
(d) a piston (<NUM>) housed within the cylinder (<NUM>);
characterised in that
the apparatus for modifying the internal combustion engine comprises a cam configured to actuate the inlet-outlet portal (<NUM>) of the engine to be controlled, when open, to permit air or air and non-combusted fuel mixture to enter or enter and exit the combustion chamber (<NUM>) and cylinder (<NUM>) and when closed to prevent air or air and non-combusted fuel mixture from entering or exiting the chamber (<NUM>) and cylinder (<NUM>), in which the volume of air or air and non-combusted fuel mixture located inside the chamber (<NUM>) and cylinder (<NUM>) when the inlet-outlet portal (<NUM>) closes, is less than the volume of the combustion chamber (<NUM>) and cylinder (<NUM>) defined when the piston (<NUM>) is at the bottom dead centre, BDC, position inside the cylinder (<NUM>) when the inlet-outlet portal (<NUM>) is closed so that the compression ratio is reduced and is less than an expansion ratio thereof;
and the apparatus for modifying the internal combustion engine further comprises a substantially incompressible member (<NUM>) configured to be fixedly attached inside the combustion chamber (<NUM>) of the engine to provide a reduction in volume of the combustion chamber (<NUM>);
wherein a volume of the incompressible member (<NUM>) is selected so that the reduction in volume of the combustion chamber (<NUM>) provided by the incompressible member (<NUM>) is proportional to the reduction in volume between the volume of air or air and non-combusted fuel inside the cylinder (<NUM>) when the piston (<NUM>) is at the BDC position and the volume of air or air and non-combusted fuel inside the cylinder (<NUM>) when the inlet-outlet portal (<NUM>) closes.