Patent Description:
<CIT> discloses an internal combustion engine that has a piston within a cylinder and has a crankcase, defining a combustion chamber and crank volume. <CIT> concerns a crankshaft lubricating device for internal-combustion engine of motor vehicle.

<CIT> and <CIT> relate to internal combustion engines.

It is known to provide an internal combustion engine for powering items such as a vehicle, generator, machinery or the like. Traditional conventional internal combustion engines use a crankshaft, crankpins and connecting rods. However the applicant has identified that there are limitations in noise, smoothness, efficiency and emissions of conventional internal combustion engines.

Examples of the present invention seek to avoid or at least ameliorate the disadvantages of existing internal combustion engines.

In accordance with one aspect of the present invention, there is provided an internal combustion engine according to claim <NUM>. The dependent claims set out particular embodiments of the invention.

There is also disclosed a method according to claim <NUM>.

The invention is further described by way of non-limiting example only with reference to the accompanying drawings, in which:.

<FIG> depict operation of an internal combustion engine in accordance with an example of the present invention.

More specifically, in accordance with an example of the present invention, the applicant has developed an internal combustion engine <NUM>, including a cylinder <NUM>, a piston <NUM> (also reference numeral <NUM> in <FIG>), and an output shaft <NUM>, wherein the piston <NUM> is arranged for reciprocating motion within the cylinder <NUM>, driven by combustion, and the piston <NUM> is coupled to the output shaft <NUM> by a coupling. The engine <NUM> is configured such that said reciprocating motion of the piston <NUM> drives rotation of the output shaft <NUM>. The coupling is arranged such that the piston <NUM> has sinusoidal motion when plotted against rotational angle of the output shaft <NUM>.

In the example depicted in the drawings, the engine <NUM> is in the form of a scotch yoke engine, as shown in <FIG>, and the coupling includes a slider bearing <NUM> (or slider block) which is able to slide along a channel formed between opposed connecting rods <NUM>. The engine <NUM> of the example includes a pair of opposed pistons <NUM> which are mutually rigidly fixed such that movement of one piston in a first direction causes movement of the other piston in a second direction which is opposite to the first direction (see also pistons <NUM> in <FIG>).

With reference to <FIG>, the engine <NUM> is arranged such that, when measured against a conventional crankshaft engine of identical bore and stroke, the motion of the piston <NUM> after top dead centre ("TDC") has a lower displacement, velocity and acceleration such that volumetric difference in the cylinder <NUM>, when compared to the conventional crankshaft engine, peaks at between <NUM>% and <NUM>% between TDC and bottom dead centre ("BDC"). In <FIG>, velocity of the piston <NUM> of the engine <NUM> according to an example of the present invention is shown by line <NUM>, whereas velocity of a piston of a conventional engine having identical bore and stroke (to engine <NUM>) is shown by line <NUM>. In <FIG>, Total Working Unit Cylinder Volume of the engine <NUM> according to an example of the present invention is shown by line <NUM>, whereas Total Working Unit Cylinder Volume of a conventional engine having identical bore and stroke (to engine <NUM>) is shown by line <NUM>. With regard to <FIG>, motion of the piston <NUM> is sinusoidal such that velocity of the piston <NUM> is greater around TDC <NUM> (than for a conventional engine) whereas velocity of the piston <NUM> is less around BDC <NUM> (than for a conventional engine).

Looking specifically at <FIG>, the engine <NUM> is arranged such that, when measured against a conventional crankshaft engine of identical bore and stroke, the motion of the piston <NUM> after TDC <NUM> has a lower acceleration such that volumetric difference in the cylinder <NUM> peaks at between <NUM>% and <NUM>% between TDC <NUM> and BDC <NUM>. In the example shown, the engine <NUM> is arranged such that, when measured against a conventional crankshaft engine of identical bore and stroke, the motion of the piston <NUM> after TDC <NUM> has a lower acceleration such that volumetric difference in the cylinder <NUM> peaks at between <NUM> and <NUM> degrees of output shaft rotation after TDC <NUM>. This peak may, more specifically, be between <NUM> and <NUM> degrees of output shaft rotation after TDC. Even more specifically, this peak may be between <NUM> and <NUM> degrees of output shaft rotation after TDC <NUM>.

The engine <NUM> includes a combustion chamber <NUM> for combustion of the charge, and the combustion chamber <NUM> and/or the coupling is/are arranged to achieve goal volumetric difference characteristics, when compared to a conventional crankshaft engine.

The applicant has, advantageously, identified a method of manufacturing (and, specifically, designing) an engine <NUM>, the method including the steps of measuring and/or modelling charge density in the cylinder <NUM> to obtain data; and using the data to optimise one or more parameter(s) of the engine <NUM> so as to increase maintenance of a gas state with a higher charge density around TDC <NUM>. The method may include the step of using the data to optimise one or more parameter(s) of the engine <NUM>, the parameter(s) including one or more of the coupling, the piston <NUM>, the cylinder <NUM>, the combustion chamber <NUM>, and valves <NUM>.

The method may include the step of using the data to optimise one or more parameter(s) of the engine <NUM> so as to increase maintenance of a gas state with a higher charge density around TDC <NUM> to achieve improved fuel mixing.

As discussed above, with reference to <FIG>, movement of the piston <NUM> in the engine <NUM> is sinusoidal. The movement of the piston <NUM> against crank angle over top dead centre <NUM> and bottom dead centre <NUM> are identical, as shown by the sinusoidal curve of line <NUM> in <FIG>.

In contrast, the crank and connecting rod mechanism of conventional engines produces unequal piston movement in the region of TDC <NUM> and BDC <NUM> (see line <NUM> in comparison to line <NUM>). In the region of TDC <NUM> the piston of the conventional engine moves faster than in the engine <NUM> of present invention and, in the region of BDC <NUM>, the piston of the conventional engine moves slower than in the engine <NUM> of the present invention. For a given engine stoke the difference between these two conditions depends on the length of a con rod. The shorter the con rod, the greater the differences.

The power level for a given piston displacement is very much a function of the amount of air mass captured per cycle affecting the engine volumetric efficiency. Volumetric efficiency depends on several engine design parameters, namely; cam profile, valve timing, manifold tuned length, forced air induction (Turbo/Supercharging) etc. which are optimised for the pressure wave dynamics set by any given piston motion. Therefore, the processes that will be influenced by piston motion can be divided into two categories; induction process and post induction processes.

The present invention focusses on the post induction processes ie. : compression, combustion and expansion, being influenced by the piston motion. The applicant has identified that it is of particular interest to note the production of NOx emissions in the combustion processes and the expansion stroke (post combustion) when the useful work is produced. In orderto understand the advantages of the engine <NUM> of the present invention and, in particular, the advantage of the motion of the piston <NUM> over that of a conventional engine we must first compare an identical volumetric efficiency and piston bore and stroke to have identical induction conditions for both the engine <NUM> of the present invention and a conventional engine.

In the graph shown in <FIG>, two engines of differing piston motion but otherwise identical in other respects (with identical volumetric efficiency and identical bore and stroke) were compared under the same engine speed, load (full power) and air-fuel ratio.

Piston velocity in this unit (mm/degree crank) is independent of engine speed and hence is characteristic of piston motion over the entire speed range. Clearly, the piston <NUM> of the engine <NUM> approaches and goes away from TDC <NUM> at a lower acceleration (rate of change of velocity) than the conventional piston. This means the engine <NUM> will have a lower rate of cylinder volume change around TDC <NUM> and therefore will help maintain a gas state with higher charge density around TDC <NUM>. The applicant has identified that a higher charge density assists the flame to speed up. The lower piston acceleration extends over a considerable part of the gas expansion duration.

When computed over the entire speed range, the cylinder peak pressures are found to be lower in the engine <NUM> than in the conventional engine in most speeds except for the lower speeds of <NUM> and <NUM> r/min where the peak pressures are very similar. However, cylinder pressure during the gas expansion process (i.e. after mass fraction burned has reached <NUM>) remains higher in the engine <NUM> compared with that in the conventional engine providing more useful work (and a higher IMEP) for the engine <NUM>.

The subject of combustion needs far deeper treatment due to other complex engine related parameters, ie: squish velocity (including the geometry of the squish surfaces) and heat losses through surface (influenced by combustion chamber geometry, piston-con rod connection responsible for uniformity of temperature of piston crown around the joint face, cooling water circuit, etc.). But importantly, all of these contribute to the development of the resultant cylinder pressure (profile) which is responsible for the power level and emissions that are achieved.

As shown in <FIG>, there are shown modelling results of the engine <NUM> according to an example of the present invention, depicting the near perfect airflow tumble as it enters and fills the cylinder <NUM> resulting in homogenous fuel mixing giving cleaner combustion, high torque and lower emissions.

The piston <NUM> approaches and goes away from TDC <NUM> at a lower acceleration than the conventional piston with both engines having identical stroke and bore. This means the engine <NUM> will have a lower rate of cylinder volume change around TDC <NUM> and the applicant has identified that this helps maintain a gas state with higher charge density around TDC <NUM>, leading to homogenous fuel mixing resulting in cleaner combustion, more engine knock resistance, high EGR tolerance, high torque and lower emissions.

In one example, the applicant has identified that the engine <NUM> may be used to drive a generator in a hybrid vehicle. More specifically, the applicant has identified that the engine <NUM> may be used to drive a generator in a series hybrid vehicle, possibly with the engine being operated at constant rotational velocity during running of the generator which may be located in a discrete location of the vehicle, such as in the boot/trunk. The efficiency, balance, low vibration and quietness of the engine <NUM> may make the engine <NUM> particularly suitable to such an application.

In many traditional engines, oil pressure is generated by an oil pump driven by the crankshaft. When excess oil pressure and flow is achieved by the oil pump at higher engine speeds, this excess oil is redirected by a pressure regulating device back into the suction port of the pump or back to the sump via an exhaust passage. Normally, in a range extender engine, when the engine is at low engine speeds, the engine has low oil pressure but is also at low load. When the engine speed is increased, so too is the load and correspondingly the oil pressure and flow is also increased to a point where the pump generates excess oil that is not normally used and is redirected back to the engine sump or back to the pump suction port.

With reference to <FIG>, the following invention, outlines several methods of targeting lubrication to the areas of an engine that need it most and a method of using this excess oil to the advantage of the engine by redirecting this excess oil in the first case to other areas of the engine and then if the pump still has excess oil available, only then would the oil be redirected back to the suction port of the pump or to the sump.

This aspect of the patent specification covers the following key areas:.

In addition, the use of a slider block in a scotch yoke engine requires specific targeted lubrication to maintain a boundary layer of oil on the sliding bearing surfaces.

With reference to <FIG>, piston sprays in engine block that are fed from excess oil from slider block. Slider block oil gallery aligns with spray nozzle and supplies oil to jet at the top and bottom of each stroke (jets closed in this view). Turning to <FIG>, Piston Sprays in engine block that are fed from excess oil from slider block. Slider block oil gallery aligns with spray nozzle and supplies oil to jet at the top and bottom of each stroke (top jet open in this view).

<FIG> shows notches in edge of bearing faces (<NUM> shown) to allow oil to leak past the thrust face and out the side of the bearing to lubricate the sides of the bearing and the associated thrust faces. This also applies to the side of the crank flange guide faces.

In many traditional engines, a balance shaft is used to reduce engine vibration. These balance shafts spin at a speed relative to the engine and are driven by the crankshaft. This speed is normally twice engine speed and in the case of a <NUM> cylinder in-line conventional engine two balance shafts are required. These shafts act to dampen engine vibration by inducing an imbalance opposite to the engine induced vibration, normally known as second order forces.

With reference to <FIG>, by virtue of the Sytech engine design, second order forces are minimal, thus only one balance shaft is required and this spins at engine speed, not twice engine speed. The following invention, outlines a balance shaft that is located inside the camshaft of an engine. For reference purposes, the camshaft spins at half engine speed. This Concentric combined camshaft and balance shaft has many benefits to the engine design including:.

In order to make best use of this invention, the camshaft and balance shaft would spin in the same direction so as to minimise the differential bearing speeds between the parts.

With reference to <FIG>, the Sytech engine is an engine that relies on the Scotch Yoke principle of operation in a horizontal, opposed in-line cylinder arrangement. Typically, these engines require very close tolerance of the two opposing cylinders within the cylinder block to ensure alignment and so as not to induce side load of the piston or over-constraint and loading of the slider block on the crankshaft. This results in very tight tolerances and manufacturing cost on the:.

Conventional engines must have a rotating joint between the conrod and the piston to allow for the conrod to follow the circular motion of the crankshaft big-end journal. A Sytech engine does not normally need this rotating joint as the pistons and connecting rod move only in a linear direction and hence have no side forces.

In an effort to reduce manufacturing tolerance sensitivity and reduce the need for "matched" cylinder block halves, we wish to include a floating connection between the connecting rod and the piston and transfer the guidance and alignment of the pistons from the cylinder bore to the crankshaft.

This will allow the piston bores within the cylinder block to be toleranced and aligned in reference to the crankshaft rather than to the opposing cylinder block. The pistons themselves will be free to centre themselves within the cylinder bore via their own minimal, short piston skirt without being held to positional tolerance by the connecting rod. The result is:.

With reference to <FIG>, there is shown an arrangement in which the connecting rods of the internal combustion engine are formed of two like parts, each of the like parts being in the form of an identical C-claw. More specifically, there is shown an internal combustion engine, including a pair of opposed pistons, a pair of opposed cylinders, and an output shaft, wherein each of the pistons is arranged for reciprocating motion within a respective one of the cylinders, driven by combustion, and the pistons are coupled to the output shaft by a coupling such that said reciprocating motion of the pistons drives rotation of the output shaft. The coupling includes a connecting rod coupled to the opposed pistons, the connecting rod being formed from a pair of like parts <NUM>, <NUM> fastened together, one <NUM> of the like parts being reversed relative to the other <NUM> of the like parts prior to fastening.

The connecting rod may have side guides for guiding a slider bearing located for reciprocating movement relative to the connecting rod, and the coupling may further include a crankshaft rotatably mounted within the slider bearing.

With reference to <FIG> and <FIG>, the Sytech engine may have an intake system <NUM> which promotes a cyclonic airflow in a plenum chamber so as to have an effect similar to a ram charging effect. In particular, there is shown an internal combustion engine, including a pair of opposed pistons, a pair of opposed cylinders, and an output shaft, wherein each of the pistons is arranged for reciprocating motion within a respective one of the cylinders, driven by combustion, and the pistons are coupled to the output shaft by a coupling such that said reciprocating motion of the pistons drives rotation of the output shaft, wherein the coupling includes a connecting rod coupled to the opposed pistons, the connecting rod having side guides for guiding a slider bearing located for reciprocating movement relative to the connecting rod. The coupling further includes a crankshaft rotatably mounted within the slider bearing. The internal combustion engine includes an intake system <NUM> arranged to induce cyclonic airflow in a plenum chamber of the intake system.

The firing order of the cylinders may be <NUM>-<NUM>-<NUM>-<NUM>. The intake system may be arranged such that intake conduits leading to the cylinders meet at the plenum chamber and are arranged generally in a circular configuration about the plenum chamber in the firing order of the cylinders. The intake conduits from the plenum chamber to the cylinders may be arranged to promote free flow resulting from the cyclonic airflow in the plenum chamber. In one form, the intake conduits may be directed to capture flow from the cyclonic airflow in the plenum chamber. In particular, the intake conduits may lead tangentially from the plenum chamber so as to efficiently capture momentum of the cyclonic airflow. The plenum chamber may be located centrally in relation to the cylinders of the engine and this may be of particular advantage where the engine is a Scotch Yoke type engine as this may facilitate the central placement of the plenum chamber as well as the tuning of the lengths of the intake conduits. In one form, the intake conduits may each be of equal length. By virtue of the cyclonic airflow in combination with the engine being of scotch yoke type, there is greater opportunity to shape the plenum with an optimal shape such as, for example, a rounded and/or circular shape.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge.

The invention may be used in a wide variety of applications and, in particular, as a low cost and unique solution for modern range extenders.

The inventors have developed a new family of modern opposed piston gasoline engines based on the Scotch Yoke Crankshaft connection principle, called the SYTECH Engine. The engine family consists of modular <NUM> cylinder units that are joined together to create a family of engines. Due to the engine construction, the engine can be modularized in even numbers of cylinders, i. e, <NUM> cylinders, <NUM> cylinders, <NUM> cylinders etc. With this approach, common engine parts and architecture can be employed to reduce engine cost and weight. This paper focusses primarily on the first engine in the family, a <NUM> litre <NUM> cylinder engine identified as the <NUM> engine, where <NUM> represents the number of cylinders and <NUM> represents the <NUM> engine displacement. During the combustion system analysis phase, FEV was responsible for developing an optimized combustion chamber concept with a tailored set of engine geometry parameters which could best leverage the benefits of the Scotch Yoke Principle. In order to do this, 1D engine modelling software (GT-Power) and 3D Computational fluid dynamics software Star CCM+ were used to accurately model the effect of the unique piston motion on the chosen combustion chamber concept respectively. Once this had been performed and the engine combustion modelled, the next step was to determine the necessary technologies and associated costs when using the Scotch Yoke Principle to prepare the engine for future legislative and customer requirements. This paper provides a brief overview of ASFT's new engine family with a focus on the detailed results of the combustion system analysis and engine recommendations leading to the prototype build phase and the upcoming engine testing.

The background of the new engine family is the development of a common core engine structure in the crankshaft and piston connection that can be applied to multiple engine configurations. This enables the engine to be built to suit a wide range of power outputs with maximum commonality while protecting for the application of additional technologies in the future. The benefits of this strategy are that it allows a wide range of engine variants that achieve legislative compliance whilst using as many common parts as possible with the required technology package.

In order to determine the best architecture for the engine, we first modelled the engine construction. The SYTECH engine piston motion is uniquely different to traditional crank/connecting rod engines. Due to the connecting rod arrangement, the SYTECH piston travels in a uniform way following a pure sinusoidal motion. <FIG> shows the SYTECH connecting rod arrangement with the slider block.

A conventional engine has a piston motion that is quite short/sharp at the top of the stroke during combustion, this is a function of the relationship between the connecting rod and crank throw length. The SYTECH mechanism results in a pure sinusoidal piston motion regardless of the connecting rod length as depicted in <FIG>. Although this difference appears to be minor, the net effect is that the combustion process has more time to complete in the end of the compression stroke. In theory this results in more time to burn the fuel, a more uniform piston motion, more uniform piston pressures/forces, less firing force peaks and lower emissions.

The next advantage of the SYTECH piston arrangement is that two opposing pistons share the same crankshaft journal. This makes the engine much shorter than conventional engines and traditional boxer engines. When comparing bore spacing alone and ignoring front and rear engine accessories, a <NUM> cylinder SYTECH engine can be up to <NUM>% shorter than a traditional In-line <NUM> cylinder engine. When comparing a <NUM> cylinder SYTECH opposed piston engine to a <NUM> cylinder boxer engine, the SYTECH engine is up to <NUM>% shorter. This makes the SYTECH engine very easy to package in most engine bays and offers advantages when packaging the engine in other areas of the vehicle like behind the rear seats, under the vehicle etc..

<FIG> shows an engine length comparison of A (inline <NUM>), B (Boxer <NUM>) and C (Sytech <NUM>).

The third advantage of the engine is that due to Scotch yoke mechanism and slider block arrangement, there are almost no out of balance forces and very low piston side forces. This results in a well-balanced engine that is quiet. <FIG>, out-of-balance force comparison, shows the SYTECH engine out of balance forces when compared to other engines. <FIG>, NVH test results, shows the results of testing conducted on early prototypes of the engine developed several years ago. The NVH advantages are highly evident in these results and this is key for Range Extender Vehicles which are primarily a Battery Electric Vehicle with an on-board generator. The generator needs to be quiet and vibration free so as to be as unobtrusive as possible and not negatively impact on the comfort of the vehicle operator when it is running.

The advantages of the SYTECH engine make it an attractive solution for the Range Extender market, so we decided that we would like to build some engines for testing, but only if the engine was able to meet the Performance and Emission targets, especially those of the China market and China 6b emissions.

The first step in designing an engine is to set targets for the engine performance and to then model the engine, specifically in SYTECH's case, model the engine using the SYTECH piston motion along with the resulting combustion in order to optimize the bore, stroke, compression ratio, valve sizes, valve overlap, valve timing and injector requirements to meet the target performance and emission levels. Initial target parameters were set for the engine design and analysis based on a <NUM> low cost, minimum technology package engine.

The design process to be followed was aimed at coming up with a combustion system concept that enabled us to have a family of engines that are based on the same core internal design where all the engines in the family would share the same bore, stroke, compression ratio, crank bearing diameter, connecting rod, piston, slider block, valve sizes/angles and be modular. The outputs would then be expected to be something similar to that shown in the table of <FIG>, "Engine family". This table shows variation in parameters, engine displacement and engine power estimate according to <NUM> cylinder, <NUM> cylinder and <NUM> cylinder versions of the engine.

As a result, if successful, the three engine variants would share;.

and many of the other base engine components. This decreases production complexity, increases common part volumes, improves reliability, decreases manufacturing/tooling and decreases overall engine cost.

Conventional <NUM> cylinder engines have a firing order that is <NUM>-<NUM>-<NUM>-<NUM>; in contrast, the SYTECH opposed piston engine has a firing order that is <NUM>-<NUM>-<NUM>-<NUM>. This change in firing order is not so important when modelling the individual combustion chamber performance but is critical when modelling the Inlet manifold, the plenum chamber and the exhaust system in order to determine the lengths and tuning of these inlet and exhaust systems to optimize the final engine performance.

<FIG> shows that the firing order of the SYTECH engine is <NUM>-<NUM>-<NUM>-<NUM>.

The concept and layout phase of the new engine family was supported by FEV's charge motion design CFD process. This process analyses and compares the geometries of the air guiding surfaces in the cylinder head and the combustion chamber to predict an optimal combination of engine parameters to achieve the design targets. It also considers the interaction between the in-cylinder flow field and the fuel injection for improved and optimized fuel homogenization.

The concept study model was used to determine the optimum bore and stroke for the SYTECH engine. After several early runs in the model, the optimum bore and stroke was determined to be <NUM> stroke and <NUM> bore, this gave us a <NUM> <NUM> cylinder engine. Using a data driven approach, sufficient iterations of the model were then performed, modified and repeated to determine the optimum arrangement of the combustion chamber.

After these modelling iterations, the engine architecture that was decided on moving forward was;.

Further modelling iterations and analysis of the engine yielded valve sizes and angles that were the best match to the piston motion of the SYTECH Engine and were good inputs for the next stage of the engine modelling. Finally, the proposed parameters for the engine were as shown in the table of <FIG>. The names of the proposed parameters according to the reference numerals are explained in the Features List which follows at the end of the detailed description section of this specification.

Following the selection of the proposed parameters, several iterations were run using a detailed CFD modelling approach to assess and optimize the flow guiding surfaces in the combustion system. After these analyses, the present applicant settled on an iteration showing a good compromise between charge motion and flow restriction.

<FIG> shows stationary port flow simulation results and <FIG> shows charge centering close to the centrally located spark plug. <FIG> and <FIG> show two important illustrations of the charge motion design process. <FIG> depicts the simulated intake flow field in the middle of the intake stroke in the valve cut-section of cylinder #<NUM>. It can be seen that the applied high charge motion tumble intake port generates a strong jet of air flow entering the combustion chamber. Within the combustion chamber, this jet is guided by the exhaust side of the combustion chamber roof to transit into a tumble motion. The flat geometry of the piston crown ensures low disturbances during intake and early compression stroke. This enables a good conservation of the tumble flow motion until the late phase of the compression cycle resulting in a good centering of the charge around the centrally located spark plug as can be seen in <FIG>.

All the modelling performed on the engine was with RON <NUM> fuel. It was decided that this was an important consideration for a range extender engine that would need to be flexible and be able to be fueled in even the most remote of locations.

<FIG> shows mass flow distribution over the two inlet valves.

When comparing the results of the engine analysis it is found that the chosen model iteration is located above the performance line of <NUM> other similar engines that were included in the FEV scatterband as shown in <FIG> (Evaluation of Charge motion vs engine scatterband). This proves a best-in-class trade-off between the flow performance is necessary to achieve the rated power and the charge motion resp. tumble to achieve high efficiency in the entire engine map.

The table in <FIG> (Engine design attributes) shows a summary of the resulting technologies that were necessary to achieve the engine parameters that have been set for the engine performance. It can be seen that the core of the proposed SYTECH engine family includes low cost, readily available technology features of common engines, such as fixed intake and exhaust camshaft timing (which is well suited for non-transient REX applications), Port fuel injection and combined Catalytic converter with GPF. As a result, this engine should be a low cost engine with maximum reliability.

Although the engine architecture sounds relatively simple, according to the modelling it is still able to achieve all of the design parameters set for the REX application. In addition, during the design and analysis stage, it was possible to incorporate space for a DI Injector and to design the combustion chamber such as to protect for the future use of a Turbocharger with a common cylinder head base design. For any future boosted application, the ports will have to be optimized for the TC application and machining for DI injector must also be considered but the important note is that the cylinder head has been designed with these options in mind. When we add these features to the engines inherent size, shape, weight and vibration advantages, the applicant has a good solution for range extender vehicles, particularly those requiring higher power outputs.

With relatively basic (common, state of the art) technology, we were able to achieve an engine that was light weight, cost effective, low risk and with the ability to be fitted with a DI injector and/or turbo-charged at a later date with minimal changes.

The table in <FIG> shows performance vales of the <NUM> litre SYTECH engine and <FIG> shows engine performance. <FIG> show the modelled performance results of ASFT's new <NUM> engine with <NUM> kW peak power at <NUM> RPM. As mentioned earlier, the engine is designed to provide a high power output, Normally Aspirated even with RON <NUM> fuel. This target is represented by the peak torque of <NUM> at <NUM> rpm engine speed.

In order to realize this development, FEV and ASFT applied advanced engineering methods to ensure a fast, stable and efficient combustion, while maintaining low friction, good NVH and a lightweight design.

The base design of ASFT's new <NUM> engine needs to be capable of withstanding the forces and loads generated by combustion whilst being reliable, light- weight, low cost and low friction. Friction is a major consideration when designing an efficient engine. As the SYTECH piston-to-crank connection is unique, during the FEV analysis and modelling we had to assume a friction level that was based on previous SYTECH engines. The SYTECH engine should have a lower friction level overall as it has only <NUM> main bearings and two connecting Rod bearings for a <NUM> cylinder engine, as opposed to <NUM> main bearings and <NUM> connecting rod bearings as is the case for most conventional inline <NUM> cylinder engines. The SYTECH engine does have an additional slider bearing but the slider bearing causes the piston to have almost no side forces so the overall piston friction is lower. The focus of engine development after the prototypes are built will be to tune the engine for emissions and power, correlate the analysis models and analyse the overall engine friction which will increase our efficiency and reduce our losses. Small bearing diameters and a light-weight piston group with a low pre-tension ring pack help to reduce the friction in the crank train and have already been included in the engine design.

For the timing drive, a belt has been chosen to combine the benefits of excellent robustness and a state-of-the-art NVH behavior and good serviceability. At the same time, the layout of the complete timing drive has been optimized in close cooperation with the belt drive system supplier to achieve a very low friction level and minimize belt harmonics and whipping.

The valve train uses roller finger followers (RFF) and hydraulic lash adjusters (HLA) for low friction and maintenance free operation. The valve spring design was analyzed and optimized in detail with kinematic and dynamic valve train simulations to ensure safe operation in the complete speed range. The balance shaft on the SYTECH engine runs at engine speed and this is directly chain driven off the crankshaft. The oil pump is located around the crankshaft so that no drive related friction losses need be considered.

Several engines have been built and these are currently being prepared, instrumented and readied for testing at FEV's test facilities to verify the concept, layout and design steps. The engine will be instrumented with water-cooled in-cylinder pressure transducers at all cylinders, exhaust and intake pressure indication at cylinder #<NUM>, comprehensive exhaust gas analysis and thermocouples as well as pressure sensors at all relevant positions on the engine.

The combustion models used in the concept design study will be used for validation purposes and help further identify any areas for combustion system optimization following the first round of Thermodynamic testing.

ASFT Technologies Australia (ASFT) and FEV successfully cooperated in the development of a new family of modern SYTECH gasoline engines. The lead engine of this cooperative development is ASFT's new <NUM> litre opposed piston engine, which is designed for outstanding performance and good fuel efficiency at a low cost using RON <NUM> fuel.

In order to achieve the targeted performance with RON <NUM> fuel, FEV and ASFT focused on the development of a modern SYTECH engine with stable combustion.

ASFT's new engine family does not only provide outstanding performance with minimal technology, but it has also been protected for the application of more sophisticated future technologies such as cooled EGR, Direct Injection and Turbocharging.

Claim 1:
An internal combustion engine (<NUM>) having a horizontally-opposed cylinder arrangement, including at least one pair of pistons (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) associated with a respective pair of opposed cylinders (<NUM>) of the cylinder arrangement, and an output shaft (<NUM>), wherein each of the pistons is arranged for reciprocating motion within a respective one of the cylinders, driven by combustion, and wherein the pistons are coupled to the output shaft by a coupling such that said reciprocating motion of the pistons drives rotation of the output shaft, wherein the coupling includes a connecting rod (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) moveably coupled to a respective pair of pistons such that each piston is permitted to centre within its associated cylinder, a slider bearing (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) that is located for reciprocating movement relative to the connecting rod, and a crankshaft (<NUM>, <NUM>, <NUM>) that is rotatably mounted within the slider bearing, the crankshaft having at least one guide shoulder (<NUM>) for supporting axial location relative to the slider bearing.