MULTIPLE CRANKSHAFT IC ENGINE

FIELD OF THE INVENTION

The present invention relates to a multiple crankshaft IC engine particularly, although not exclusively, envisaged for use in allowing a relatively large number of engines to be coupled together to form a single composite engine. Typically, each ofthe engines has a relatively large number of relatively small cylinders - although they can have as few as one cylinder. Also, the engines can be existing off-the-shelf engines.

In the context ofthe present invention "relatively large number of engines" means more than 2 engines. Also, "relatively large number of cylinders" means more that about 20 cylinders. Further, "relatively small cylinders" means cylinders with a volume at least 25% ofthe volume of cylinders used in a conventional engine of similar power output.

The present invention also relates to a perfect balance IC engine in which cylinders ofthe IC engine are arranged so that reciprocating forces, translational forces and rotational forces caused by the movement of pistons in the cylinders and the connecting-rods ofthe engine cancel each other out to yield no vibration. This is a state know in the art as "perfect balance".

The present invention further relates to a rotary intake valve for an IC engine particularly, although not exclusively, envisaged for use with multi-cylinder two-stroke IC engines that use crankshaft-case compression for scavenging purposes.

BACKGROUND OF THE INVENTION MULTIPLE CRANKSHAFT IC ENGINE

In the field of IC engines it is generally accepted that in order to get more power from an engine ofa given external physical dimension the engine must be "developed". It is also generally accepted that in order to get more power larger cylinders are needed for a given degree of development ofthe engine.

It is also known by a few engine designers that it is also possible to increase the power output of an engine ofa given external physical dimension by increasing the number of cylinders that the engine has and making those cylinders smaller than normally would be the case. In practice, the number of cylinders is usually less than 10 due to limitations on the crankshaft. Additionally, engines with more than 6 cylinders in line are too long for most vehicles. By using a V formation, such as in the V6, V8, V10, and V12 engines, the designer can keep the engine length to a minimum.

What we have discovered is that it is possible to dramatically increase the power output of

an engine of given external physical dimension by using a very large number of very small cylinders. In practice, such arrangements would not even be contemplated because ofthe engine length and crankshaft limitations.

For example using 32 cylinders instead of 4, The larger number of cylinders having a proportionately smaller volume so that the overall capacity ofthe engine is the same. In a conventional arrangement this would lead to an engine that is four times longer and with an unworkably long crank.

Thus, the problem with using a relatively large number of relatively small cylinders is in how to couple them altogether in a way that will work. To solve this problem we have developed a system of multiple crankshafts which are coupled together to form a single composite engine from three or more individual engines. Generally, we do this by using a number of engine blocks each with output shafts which are couped together to form a single output shaft for the composite engine - which is herein referred to as a multiple crankshaft engine. In the context ofthe present invention we use the term "primary engine" to refer to an individual engine with its own engine block and output shaft. We use the term "secondary engine" to refer to a first level of collection of power from the output shafts ofa plurality ofthe primary engines to a secondary output shaft. And we use the term "tertiary engine" to refer to a second level of collection of power from the output shafts ofa plurality of secondary engines to a main power shaft. Of course this process of "layering" the engines can be done in two or more levels and is not limited to three levels.

Also in the context ofthe present invention we use the term "multiple level engine" to refer to an engine which is formed of one or more primary and/or secondary and/or tertiary engines. That is, the multiple level engine referred to in the present invention can have any number of engines coupled together to form it. Also, the arrangement of these engines need not have the same number of engines in all directions. For example, the multiple level engine may be made up of one primary level engine, two secondary level engines and one tertiary level engine all independently coupled to one output shaft via four pinions.

It has been well known for some time that surface-to-volume effects in engines can have a marked effect on the kW/litre of capacity and power-to- weight ratios. Small cylinder engines have a higher kW/litre of capacity than a large cylinder engine. For example: a typical six cylinder marine two stroke engine (such as the Mercury Mariner) has a power of 150 kW and a capacity of 500 cc/cylinder (3 litres).giving 40 kW/litre, whereas a single cylinder model aircraft two-stroke engine (such as the OS MAX 25 VF-

DF) has a power of 0.8 kW and a capacity of 4 cc giving 200 kW/litre.

Hence, the kW litre ofthe small engine is 5 times greater than the larger engine. In practice, the kW/litre is substantially inversely proportional to stroke length for the same technology engines operating at the same piston speed. The stroke on the Mercury engine is around 85 mm and the stroke on the OS engine is 18 mm, i.e. about 5 times smaller.

It is also true that engine weight is substantially proportional to engine capacity for engines ofthe same technology. Engine weights can range from around 30 kg litre for an air cooled aircraft engine to over 100 kg/litre for a large turbo-charged, water cooled marine engine. With this being the case, it can be seen that power-to-weight ratio will be approximately proportional to kW/litre.

Table 1 illustrates three theoretical two-stroke engines with the same cubic capacity (1012 cc), technology (two-stroke, water cooled), weight (60 kg) and piston speed (12 m/s).

Table 1: Comparison of Engine Outputs etc

Cylinders Power Revolutions Power/Volume Weight/power

(kW) (rpm) (kW L) (kg/k )

1 x 1012 cc 30 3,500 30 2

(prior art)

8 x 128 cc 60 7,000 60 1

(prior art)

64 x 16 cc 120 14,000 120 0.5

(invention)

This is shown graphically in Figures 1.1 to 1.3.

The obvious question arising from this illustration is; if having a large number of very small pistons is able to produce such high performance, then why are not all engines designed this way? The main reasons that they are not is because ofthe limits on crankshafts and engine length and no one appears to have come up with a way to have large numbers of short crankshafts. The maximum number of cylinders per crankshaft is limited by crankshaft wind-up and associated oscillations to around 12 for smaller engines and 18 for very large engines. This is visually apparent from Figure 2

It is known that using more than one crankshaft to drive a single output shaft. Two examples of this are the "Napier" and "Sabre" H engines used shortly after the early 1950s used two parallel crankshafts and a reduction gearbox.

Also, in large marine applications it is known to join multiple engines to a single output shaft via separate reduction gearboxes. This is not known to be in common practice.

Further, there are a number of examples of output systems using gears being located

between the cylinders of motor cycle engines. This takes the form of two parallel cranks coupled to one gearbox.

Still further there have been engines arranged in a planar fashion around a large reduction gear. In conveπtioTial engine design the number of cylinders for an engine of given capacity can be increased by using a reduction gearbox. The problem of using reduction gears with conventional engine configurations is illustrated by the following comparative example which considers the design of an aircraft engine with the following characteristics required to match it to the aircraft's propeller: maximum piston speed = 1800 cm/s shaft speed = 50 cp/s (ie 3,000 RPM) power = 240 kW break mean effective pressure = 600 kPa

Example 1: Direct Drive The stroke ofthe engine is then: stroke = max piston speed / (revolutions/second x pi) - 11.5 cm

The bore ofthe engine is then also 11.5 cm assuming that the engine is square (ie bore and stroke are the same.) The cylinder capacity is then: cylinder capacity = stroke x pi x bore ^κ 2)/4 = 1193 cc The kW/litre required for the engine is then: kWMtre = break mean effective pressure x shaft speed/1000 = 30 kWAitre

The total engine capacity is then: engine capacity = power / kW/litre = 8 L

The number of cylinders required for the engine is then: number of cylinders = engine capacity / cylinder capacity = 6.7

Since the required number of cylinders must be a whole number and preferably an even number, the actual number of cylinders would be 6 in the design ofthe engine for the aircraft using a direct drive form of engine.

Example 2: Reduction Gear Assuming a 2: 1 reduction gear is used then this aircraft would have a crank speed which is twice that ofthe direct drive engine ie 100 cps (6000 RPM).

Then the following applies: stroke = 5.75 cm cylinder capacity = 149 cc kW/litre of capacity/litre = 60 kW L engine capacity = 4 L number of cylinders = 26.85

As before this would be rounded to say 26 cylinders. However, this would be too long and too much for one crankshaft and the design would be abandoned.

So what is required is a new type of engine configuration which allows the use of large numbers of cylinders.

PERFECT BALANCE IC ENGINE

Generally IC engines have an amount of vibration associated with them. The vibration is the result of forces and bending moments produced as the pistons move in the cylinders, the connecting-rods translate and the crankshaft rotates. Techniques used to reduce the vibration tend to typically use counter -weights to attempt to balance up the forces and moments.

We have discovered that by a particular orientation ofthe cylinders and connecting-rods in an IC engine the movement of one piston and its connecting-rod counter the movement of another piston and its connecting-rod so that the nett result is forces and bending moments which are substantially zero. This is true not only of primary forces and moments, but secondary and tertiary ones forces as well. The result is an engine which is in perfect balance.

Perfect balance is particularly important when using large numbers of engines and/or cylinders in a multiple crankshaft engine since without such a feature the composite engine would have an unacceptably high degree of vibration. Also, this is particularly important for use in small aircraft - since existing gas turbine engines (although being of high power- to-weight ratio and low vibration) are too expensive in purchase price and maintenance (and have a very narrow speed of operating range over which they are efficient), and conventional reciprocating engines produce too much vibration and are too low in power- to-weight ratio.

ROTARY INTAKE VALVE

For single cylinder two stroke engines, the main methods of intake valve control are rotary valves and reed valves.

In the rotary valve system, typically found on model aircraft engine, the main shaft is

hollowed out form the crank web to an aperture located on one side ofthe shaft. Then rotation ofthe shaft actively opens and closes the valve each time the shaft rotates. The rotary valve system gives active control ofthe air flow and gives good performance. However, the rotary valve system ofthe prior art is limited in application to single cylinder and twin in-line single cylinders, since the valve uses the main shaft.

The reed valve system is complex that the rotary valve and uses separate reed valves for each crank case. The reed valve is operated by pressure differentials. When the pressure inside the crank case is lower than the pressure ofthe air outside the crank case, the reed valve opens to allow air to flow in. When the crank case pressure is higher than the outside air pressure, the reed valve closes, allowing the crank case to pressurise. The reed valve system is less efficient than the rotary valve system, but is simpler and lower in cost. Also, the reed valve allow any number of cylinders to be joined together and multiple valves per cylinder can also be used.

Other forms of intake valving include rotating discs and cam activated poppet valves. These systems do not limit the number of cylinders, but they add a significant level of complexity and cost to the engine. Typically, where such a level of complexity is required or desired a four-stroke engine configuration is used.

For a two-stroke engine with more than two cylinders, the only practical option is the reed valve.. If the engine is not fuel injected, then multiple independent carburettors are often used to seek to maximise performance, simplify tuning and avoid the use of complex inlet manifolds - then multiple fuel intakes and multiple throttle controls are also required.

We have developed a system where the inlet manifold and the rotating valve are as one unit. This is achieved by making the output drive shaft hollow and locating ports in the shaft at locations appropriate for meeting with the inlet ports ofthe cylinders. This is very simple and can accommodate multiple cylinders.

SUMMARY OF THE INVENTION MULTIPLE CRANKSHAFT IC ENGINE

Therefore it is an object ofthe present invention to provide a multiple crankshaft IC engine which substantially increases the kW/litre of capacity for reciprocating engines by providing a practical engine configuration with a relatively large number of relatively small cylinders.

In accordance with one aspect ofthe present invention there is provided a multiple crankshaft IC engine comprising: eight or more base level engines each having at least one combustion cylinder and a crankshaft, the cylinders driving the crankshafts for providing motive force;

four or more primary level pinions each mounted upon a respective pinion shaft, each end of each one ofthe pinion shafts being connected to the crankshaft of one ofthe base level engines, so that rotation ofthe crankshafts leads to rotation ofthe pinions, a primary level central gear disposed in meshed engagement with the pinions so that rotation ofthe pinions leads to rotation ofthe central gear, the number of pinions enabling the central gear ofa given size and weight to transmit a larger torque than if a lesser number of pinions were used, and the combination ofthe central gear and the pinions allowing a relatively large number of combustion cylinders to be used in the IC engine; and, a primary level output shaft attached to the central gear for rotation with the central gear, the axes ofthe crankshafts ofthe base level engines being substantially parallel to the axis ofthe output shaft; this arrangement constituting a first level engine arrangement which has at least eight cylinders and has a relatively high power-to-weight ratio. Typically, the crankshafts of two ofthe base engines are joined to opposite sides ofthe same pinion for increasing the compactness ofthe resultant multiple crankshaft engine.

PERFECT BALANCE IC ENGINE

Therefore, it is an object ofthe present invention to provide a perfect balance IC engine in which the disposition of pistons and connecting-rods tends to lead to forces produced in the movement ofthe pistons and connecting-rods cancelling each other out to result in perfect balance .

In accordance with another aspect ofthe present invention there is provided a multiple crankshaft IC engine for producing perfect balance and comprising: an engine bank having: two pairs of pistons arranged for reciprocation along two mutually parallel axes, the pistons in each pair of pistons facing in opposing directions, with the top surfaces of said pistons facing away from each other, so that the reaction forces created by the movement ofthe pistons in the two pairs of pistons cancel each other out for removing vibration caused by reciprocation the pistons; four crankshafts disposed in the engine bank, there being one crankshaft associated with each one ofthe pistons, the crankshafts being connected together so that all ofthe crankshafts rotate in unison and in the same direction, crankshaft webs and crank pins of the crankshafts being in the same plane of movement as the pistons and oriented with respect to each other so that one ofthe pairs of pistons is always disposed at 180 degrees

with respect to the other pair of pistons, the combination of pairs of pistons and crankshafts producing reactionary forces that cancel each other out for removing vibration caused by rotation ofthe crankshafts; and, four connecting-rods, there being one connecting-rod connecting one ofthe pistons to its associated crankshaft, the connecting-rods being oriented with respect to each other so that adjacent connecting-rods are always disposed at 180 degrees with respect to each other for producing reactionary forces that cancel each other out for removing vibration caused by the movement ofthe connecting-rods; the resulting combination of pistons, crankshafts and connecting-rods producing reactionary forces that cancel each other out, so that the engine experiences perfect balance.

Typically, the engine has an even number of pistons in excess of two. Such that in the case of four pistons the pistons are oriented in two pairs of opposed reciprocating motion ofthe pistons and two ofthe crankshafts rotate in a clockwise direction and the other two crankshafts rotate in an anti-clockwise direction.

In the case of eight pistons there are two pistons connected to opposite ends of each crankshaft and with the motion ofthe pistons and the crankshafts being the same as for an engine with four pistons.

ROTARY INTAKE VALVE Therefore, it is an object ofthe present invention to provide a rotary intake valve for an IC engine for allowing one carburettor to supply an air/fuel mixture to a plurality of pistons in a multiple crankshaft engine.

In accordance with another aspect ofthe present invention there is provided a rotary intake valve for a multiple crankshaft IC engine having a crank case, an output shaft and a plurality of cylinders each driving the output shaft, the rotary intake valve comprising: an inlet port located in one end ofthe output shaft; and, a plurality ofoutlet ports located along the length ofthe output shaft, the outlet ports being disposed to open for communication into the said cylinders during each rotation of the output shaft so that combustion fluids chosen form air and an air/fuel mixture, can flow along the output shaft, through the outlet ports and into the cylinders.

Typically, the output shaft carries a number ofoutlet ports for any given cylinder, the number ofoutlet ports being equal to the gearing ofthe engine. For example, a 2: 1 gearing has two outlet ports per cylinder so that each cylinder fires twice for each rotation ofthe output shaft.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment ofthe present invention will now be described with reference to the accompanying drawings in which:-

Figures 1.1 to I.i are a comparison of engine piston size and number in relation to their operating speed, power output and weight, the piston of Figure 1.1 being from a typical state ofthe art 3 to 12 cylinder engine (such as a car engine); the piston of Figure 1.2 being from a typical state ofthe art 1 to 2 cylinder engine (such as a motor cycle engine) and the piston of Figure 1.3 being from an engine an accordance with the present invention; Figure 2 is a side view ofa hypothetical 16 cylinder in-line engine piston and crankshaft arrangement;

Figure 3 is a perspective view, seen from above, ofa multiple crank engine incorporating a perfect balance configuration and a rotary intake valve, each in accordance with the present invention, the engine representing eight base engines arranged in two banks of balanced cylinders, crankshafts and connecting-rods.

Figure 4 is a perspective view, seen from above, ofa drive arrangement for the multiple crankshaft engine of Figure 3;

Figure 5 is a perspective view, seen from above, ofa drive arrangement ofa secondary engine in accordance with the present invention - showing 256 cylinders, formed into 8 primary engines each formed of eight, base four cylinder engines, each primary engine consisting of eight banks of balanced pistons, connecting-rods and crankshafts;

Figure 6 is a. conceptual representation ofa power collection system ofthe secondary engine of Figure 5;

Figure 7 is conceptual representation of a fuel/air mixture and spark system ofa secondary engine in accordance with the present invention;

Figure 8.1 is a side view ofa primary, a secondary and a tertiary engine in accordance with the present invention, showing the number of cylinders, power, weight, gearing ratio, operating speed ofthe output shaft, size and estimated cost;

Figure 8.2 is a side and an end view ofa 64 cylinder primary engine using eight off-the- shelf V8 engines;

Figure 8.3 is a side and end view ofa conventional 12 cylinder engine having the same output power as the engine of Figure 8.2, and shown to the same sale;

Figure 9 is a cross-sectional view of an eight cylinder double-bank air cooled, wet sump,

two-stroke engine with external scavenging using a ring reduction gear and common crank wrist pins for pairs of pistons;

Figure 10 is a cross-sectional view ofthe pistons, connecting-rods and crankshafts ofthe engine of Figure 9 in accordance with the present invention, and showing the movement ofthe pistons and connecting-rods and th balance ofthe forces associated therewith;

Figure 11 is a cross-sectional view ofa four cylinder bank in a water cooled, wet sump, externally scavenged two-stroke engine with head mounted poppet valves, incoφorating the multiple crank and perfect balance configurations ofthe present invention;

Figure 12 is a cross-sectional view ofa four cylinder bank in a water cooled, wet sump, four-stroke engine with overhead quad-cam shafts operating poppet valves.

Figure 13 is a cross-sectional view ofthe engine of Figure 3, showing a rotary intake valve in accordance with the present invention; and,

Figure 14 is an exploded view ofthe arrangement of Figure 13.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) In Figure 3 there is shown an 8 cylinder IC engine 10 which embodies each ofthe three main features ofthe present invention, namely, the use of multiple crankshafts (in this case 4 crankshafts), the use of a perfect balance configuration and the use ofa rotary intake valve for reticulation of fuel/air mixture.

The engine 10 has two crank cases 20 and 21, a gearbox 22, eight cylinder cooling cylinder 24, an exhaust system 26, an output shaft 28 and a carburettor 29 (see Figures 13 and 14). The gearbox 22 is located between the two crank cases 20 and 21.

The crank cases 20 and 21 each house four ofthe combustion cylinders 24 and their corresponding cylinder cooling jackets 25, pistons, connecting-rods, crankshafts and gears (as described hereinafter). The crank case 20 houses combustion cylinders "1" to "4" and the crank case 21 houses combustion cylinders "5" to "8". The cylinders "1", "2", "3", and "4" and disposed at 90° to the cylinders "5", "6", "7" and "8".

The exhaust system 26 includes 4 tuned expansion chambers 30 which are coupled to opposing pairs ofthe combustion cylinders "1" and "2", "3" and "4", "5" and "8", and "6" and "7". Each combustion cylinder has a glow plug 32. The engine 10 is actually made up of eight "base engines" 40 ofthe present invention. The combustion cylinders "1", "2", "3", and "4" make up a front balanced bank 42 which constitutes 4 base engines 40 (each having one cylinder "1", "2", "3", or "4"), and the combustion cylinders "5", "6", "7" and "8" make up a rear balanced bank 44 which constitutes 4 more base engines 40 (each having one cylinder "5", "6", "7" or "8"). The

rear balanced bank 44 is disposed at 90° to the axis ofthe output shaft 28 so as to facilitate cooling of all eight ofthe cylinder cooling jackets 25. The base engines 40 are coupled together through the gearbox 22 as described hereinafter. In this regard it is to be noted that in the context ofthe present invention a base engine 40 is taken as having only one crankshaft. Hence, in Figure 3 the four base engines 40 corresponding to combustion cylinders "1", "2", "3", and "4" each share the crank case 20, and the four base engines 40 corresponding to combustion cylinders "5", "6", "7" and "8" each share the crank case 21.

Each ofthe features which make up the engine 10 will now be described in detail.

MULTIPLE CRANKSHAFT IC ENGINE The present invention is essentially a means of dramatically reducing the weight and bulk of engines by using efficient power reticulation. The power reticulation ofthe invention mimics the fluid transport systems found in plants, animals, and in man-made water, sewerage and electricity systems.

Typically, the multiple crankshaft IC engine has a single output shaft which is connected to the main gear in a centralised reduction gearbox. The main gear is connected to three or more pinions, each pinion in turn is connected to two crankshafts attached to the opposing ends ofthe shafts ofthe pinions, with each crankshaft being connected to an engine with one or more cylinders. One arrangement of this is shown in Figure 4.

A more complex example of this principle can be seen in the 256 cylinder arrangement as shown in Figure 5 with one secondary gear meshed with four pinions, eight input shafts connected to eight primary gears, each set with four primary pinions. Each primary pinion has two crankshafts which are attached to base engines, each with four cylinders in-line. This results in a multiple crankshaft engine with about 1/5 the volume and weight ofa comparable power four cylinder motor. Cost savings vary with the size ofthe engine, but costs can be said to follow material cost for most medium to large engines. For two engines ofthe same power, the weight and approximate cost is shown in Table 2.

TABLE 2: Comparison of Size Reductions etc

Cylinders Weight Approx Cost

1 100%

8 35%

64 14%

512 5%

4096 2%

Figure 8.2 shows a basic arrangement ofthe multiple crank engine in comparison ofa conventional engine ofthe same output power shown in Figure 8.3. The more refined

versions ofthe engine have the cylinders, pistons and connecting -rods are arranged in multiples of four in a fully balanced version described under the heading PERFECT BALANCE ENGINE hereinafter.

In an even more advanced two-stroke version the engine uses a rotary valve intake system as described under the heading ROTARY INTAKE VALVE. This can be either with or without the perfect balance engine configuration.

The engine 10 of Figure 3 has a drive arrangement 50 as shown in Figure 4. The drive arrangement 50 has a central gear 52, four pinions 54, four crankshafts 56, eight connecting-rods 58 and eight pistons 60. The central gear 52 is journalled in the gearbox 22 and meshes with each of the four pinions 54, which are also journalled in the gearbox 22. The output shaft 28 is fixed to the gear 52 for rotation with it. The pinions 54 each carry one ofthe crankshafts 56 so that the pinions 54 rotate with the crankshafts 56. The axis of rotation ofthe crankshafts 56 are parallel to the axis of rotation ofthe output shaft 28. The connecting-rods 58 are connected to the crankshafts 56 by crank pins 70 and connected to the pistons 60 by piston pins 72.

As the pistons 60 are driven into and out of their crank cases 20 and 21 by a process of combustion the crankshafts 56 rotate which causes the pinions 54 to rotate and hence the gear 52 and the output shaft 28. The base engine 42, corresponding to cylinders "1", "2", "3", and "4", is connected to the base engine 44, corresponding to the cylinders "5", "6", "7" and "8", via the crankshafts 56. The crankshafts 56 connect cylinder pairs "1" and "5", "2" and "6", "3" and "7", and "4" and "8". Hence, typically base engines 40 come in pairs with the engines 42 and 44 of the pair disposed at 90° to each other. In Figure 5 there is shown a drive arrangement 80 for a "secondary engine" which is made up of eight "primary engines" (for which the drive arrangement is shown and enumerated as 82, with one primary engine being shown behind another primary engine). Each primary engine is made up of eight banks of balanced pistons, connecting-rods and crankshafts. Each primary engine can also be seen as a set of eight, four-cylinders base engines 60. Hence, the total number of cylinders is: total number of cylinders = 8 primary engines x 8 base engines x 4 cylinders

= 256

This could be a practical arrangement for producing a 5 litre engine. In which case each cylinder has a capacity of 20 cc. (Note - 20 cc is considered to be the practical minimum piston displacement. Smaller displacements currently result in relatively high friction

losses and therefore higher fuel consumption.)

Each ofthe primary engine drive arrangements 82 has four primary power pinions 84 which collect power from eight base engines 40, with two base engines 40 per primary power pinion 84, the pairs of base engines 40 being disposed in line and in opposite directions with respect ofthe axis ofthe respective primary power pinion 84. The primary power pinions 84 mesh with a primary gear 86. Each primary engine drive arrangement 82 also has primary engine output shaft 88.

The secondary engine drive arrangement 80 has eight ofthe primary engine drive arrangements 82 and hence has eight primary engine output shafts 88. Each of these output shafts 88 is coupled to a main gear 90 via four secondary power pinions 92. The primary engine drive arrangement 80 also has an output shaft 94 which can be used to provide motive force.

In Figure 6 there is shown a secondary engine power collection system 100 which shows the manner in which the secondary engine drive arrangement 80 of Figure 5 transmits power from the pistons 60 to the output shaft 94. There is shown eight primary engines 102 to form one secondary engine. Each primary engine 102 has eight base power branches 110 leading to one primary power branch 112 (which corresponds to the primary engine output shaft 88). Then the eight primary power branches 112 lead to one main power trunk 114 (which corresponds to the output shaft 94). Figure 6 shows how symmetry is used in the secondary engine. The result of this symmetry is that the secondary engine is very compact. Also, the secondary engine is completely modular which ensures that the paths of power collection are substantially the same length and serves to simplify the process of maintenance and makes the secondary engine more compact. Exhaust gases are collected from the pistons 60 in the same "tree type" manner as the power is collected. Hence, there is not one tuned expansion chamber 30 for each base engine 40. More desirably there is one tuned expansion chamber 30 for each primary engine 102. But there could be just one tuned expansion chamber 30 for the entire secondary engine 102. In Figure 7 there is shown a secondary engine reticulation system 120 which shows the manner in which an air/fuel mixture and spark are delivered to the pistons 60. The reticulation system 120 has a main reticulation trunk 130 which delivers air/fuel and spark to eight primary reticulation branches 132 which in turn each deliver the air/fiiel and spark to eight base reticulation branches 134 in the eight primary engines 102. The effect ofthe reticulation system 120 is that there is substantially equal fluid resistance to the flow ofthe air/fuel mixture and substantially equal resistance to the flow ofthe

spark to each ofthe pistons 60 and hence a single generator of air/fuel mixture and a single generator of spark can be used. This has the effect of simpUfying the external componentry need to operate the secondary engine.

In Figure 8.1 there is shown an examples ofa primary engine 102, a secondary engine 142 and a tertiary engine 144. The statistics for the three engines 102, 142 and 144 are shown in Table 3.

Table 3: Engine Comparisons

Primary Engine Secondary Engine Tertiary Engine cylinders (number) 48 384 3,072 power (kW) 600 4,800 38,000 mass (kg) 300 3,000 20,000 gearing ratio 3:1 4:1 6:1 output speed (rpm) 1,800 450 75 size (m) 0.5 x 0.5 x 0.6 1.2 x 1.2 x 1.5 2.5 x 2.5 x 3.5 cost ($ d/cost) 6,000 50,000 500,000

The engine configuration taught in the present invention is also of advantage in relation to conventional engines. For example, consider the engines of Figures 8.2 and 8.3. The engine shown in Figure 8.2 js made up of 8 conventional marine engines each with 8 cylinders in a V8 arrangement (making a total of 64 cylinders), whereas the engine in Figure 8.3 is a 12 cylinder marine engine in a V12 arrangement. Both ofthe engines have an output power of 2200 kW yet the engine of Figure 8.2 weighs about 3.5 tonnes whereas the engine of Figure 8.3 weighs 7.0 tonnes; and as can be seen in those figures the 64 cylinder engine is about half the size ofthe 12 cylinder engine.

In use, combustion in the cylinders 60 causes the pistons 60 to move in and out ofthe crank cases 20 and 21 of Figure 4. The movement ofthe pistons 60 causes rotation ofthe pinions 54 which leads to rotation ofthe gear 52 and hence rotation ofthe output shaft 28.

The pistons 60 in the engine 10 operate in pairs "1" and "2", "3" and "4", "5" and "8", and "6" and "7" upon 4 crankshafts 56. This has been chosen as a more compact manner of arranging the pistons 60 about the output shaft 28. The secondary engine drive arrangement 80 shown in Figure 5 has base engines 40 each with four pistons 60 upon a crankshaft 56. Combustion in the cylinders 60 has the same effect as in the engine 10. The resultant rotation ofthe crankshafts 56 of each ofthe base engines 40 causes rotation of primary power pinions 84 which causes rotation ofthe primary gears 86. The primary engine output shafts 88 are then caused to rotate which causes rotation ofthe secondary power pinions 90 and hence the main gear 92 and so the

output shaft 94.

In the process of combustion air/fuel mixture and spark is reticulated (that is, distributed) to each ofthe pistons 60 of each ofthe base engines 40 through branching from the main reticulation trunk 130 (which in practice can be a conduit in the main output shaft 94), along the primary reticulation branches 132 (which is practice can be a conduit in the primary engine output shafts 88), along the base reticulation branches 134 (which in practice can be a conduit in the crankshafts 56 of each ofthe base engines 40) and to each ofthe pistons 60.

As a result ofthe combustion process combustion exhaust gases are collected in the manner as shown in Figure 6. Namely, the exhaust cases from the pistons of each base engine 40 of one ofthe primary engines 102 are collected together. At that juncture a tuned expansion chamber 30 can be used to muffle the sound produced from the passage ofthe exhaust gases. Alternatively, the exhaust gases from each ofthe primary engines 102 can be collected together into one tuned expansion chamber 30 for the entire secondary engine 142. The collection ofthe exhaust gases can be similar for the tertiary engine 144.

The advantage ofthe engine configurations ofthe base engine 40, the primary engine 102, the secondary engine 142 and the tertiary engine 144 (and so on) is that a relatively large number of relatively small combustion chambers can be used in a very compact manner. The result of that it is now possible to produce a multiple cylinder engine which has a lower mass and volume for a given amount of power output than conventionally configured engine. The compactness ofthe engine is achieved by the pinions 54, 84 and 90 and the central gears 52, 86 and 92. Even a plurality of conventional engines arranged around such pinions 54, 84 and 90 and gears 52, 86 and 92 results in an improvement in mass and weight for a given power output.

It is envisaged that tertiary engines (such as having 4096 pistons 60) could be used to drive ships and the like, whereas small primary engines (such as having 4 or 8 pistons 60) could be used to drive hand tools, lawn mowers and the like. An engine with say 48 to 256 or more pistons could be used to power a motor vehicle. In the above cases the capacity of the pistons could range from about 20 cc to up to about 500 cc or more. It is also envisaged that when friction losses in pistons are reduced smaller piston capacities will also be useful in the context ofthe present invention.

With the present invention the pistons 60 used typically have a capacity which is less the 25% of those used in conventional engine configurations ofthe same power output and typically at least 3 times as many pistons 60 are used.

It is further envisaged that the supply of lubrication liquids and the collection of used

lubrication liquids could be by a system similar to those shown in Figures 6 and 7.

Another advantage of using a relatively large number of pistons 60 (such as in excess of about 20 pistons 60) s that the power pulses tend to overlap to such an extent that the pressure wave ofthe exhaust gases has a substantially constant pressure. The substantially constant pressure ofthe exhaust pressure wave means that there is substantially no noise produced and so the muffling required in much simplified.

A still further advantage ofthe engine configuration ofthe present invention is that a relatively large number of pistons 60 can be supplied from one carburettor and one spark ignition coil. Similarly, only one oil pump is required and one exhaust muffler. Hence, even though there are many more pistons 60 than would normally be the case there is not a corresponding increase in the complexity ofthe multiple crankshaft engine.

PERFECT BALANCE ENGINE

Basically, the perfect balance engine ofthe present invention is a reciprocating engine in which the moving parts (primarily the pistons, connecting-rods and crankshafts) are arranged so that the forces produced by the moving parts cancel each other out which results in perfect balance as shown in Figures 9 and 10, for an eight cylinder, eight crankshaft engine 150.

The balance ofthe forces is achieved with a minimum of four cylinders in the engine. The four cylinders are arranged in pairs as shown in Figures 11 and 12, for a four cylinder four crankshaft engine 151 A and 15 IB .

Referring to Figures 9 and 10, the engine 150 is similar to the engine 10 and like numerals denote like parts. The engine 150 differs from the engine 10 in that instead ofa central gear 52 the engine 150 has a ring gear 152. The ring gear 152 has the pinions 54 enmeshed with it so that the combustion process causes the ring gear 152 to rotate which causes rotation of an output shaft 154. The engine 150 also differs in that the eight pistons 60 are in a single bank (which is substantially flat) instead of being in two banks 42 and 44 (which is substantially cube shaped). The engine 150 further differs from the engine 10 in that its gearbox 156 is within its crankcase 158. Still further the pairs of pistons "1" and "2", "3" and "4", "5" and "8", and "6" and "7" are connected to the same pinions 54 by wrist pins.

In order to reduce the amount of vibration which the engine 150 generates when in use the pistons 60 are arranged in oppositely located pairs "1" and "2", "3" and "4", "5" and "8", and "6" and "7" so that one piston 60 in a pair of pistons 60 moves in the opposite direction to the other piston 60. For example, the pistons "1" and "2" both fire at the same time and so move towards each other. Hence, the reaction forces produced in the crank case ?? by the movement ofthe piston "1" cancels out the reaction forces produced in the

crank case by the movement ofthe piston "2". This is the same case for the other piston pairs "3" and "4", "5" and "8", and "6" and "7". The balance in the linear forces due to the movement ofthe pistons 60 is achieved by arranging the pistons 60 in a matrix arrangement with opposing pistons 60 being on the same axis and, in the embodiment of Figures 9 and 10.

Balance in the part rotational and part Unear forces ofthe connecting-rods 58 is achieved by arranging the connecting-rods 58 of opposing pairs of pistons "1" and "2", "3" and "4", "5" and "8", and "6" and "7" 180° out of phase with each other so that the connecting- rods 58 ofthe opposing pairs of pistons "1" and "2", "3" and "4", "5" and "8", and "6" and "7" move in opposite directions, particularly as shown in Figure 10.

Balance in the rotational forces ofthe crankshafts 56 is achieved by disposing the crankshafts 56 are disposed in a particular arrangement 180° out of phase with each other so that the connecting-rods 58 of combustion cylinder pairs "1" and "2", "3" and "4", "5" and "8", and "6" and "7" crankshafts 56 move in opposite motion to each other. More specifically, considering combustion cylinder pair "5" and "8", one of their connecting- rods 58 rotates in a clockwise direction whilst the other connecting-rod 58 rotates in an anti-clockwise direction. The crankshafts 56 are further arranged so that the pistons 60 of the combustion chamber pair "5" and "8" move in opposite directions, that is, both travelling into their crank case 21 or both travelling out of their crank case 21. The connecting-rods 58 ofthe cylinder pairs "1" and "5", "2" and "6", "3" and "7", and "4" and "8" are also arranged so that the pistons 60 of those pairs are 180o out of phase with respect to each other. Hence, piston "1" goes into the crankcase 158 (at the completion of a "fire" stroke) as piston "5" goes out ofthe crankcase 158 (at the completion ofa compression stroke) and vice versa. The engines 151A and 151B of Figures 11 and 12 show the above described orientation and timing ofthe pistons 60, the connecting-rods 58 and the crankshafts 56 in relation to four pistons 60 in a single bank.

The engine 151 A is a two-stroke engine and has inlet ports 170, exhaust ports 172 and poppet valve assemblies 174 for opening and closing the exhaust ports 172. A water jacket 176 is also provided. The engine 151 A relies upon a wet sump configuration and external scavenging, such as by a roots blower. The engine 151 A is similar to the engine 10 and like numerals denote like parts.

The engine 15 IB is a four stroke engine with quad-overhead cams 180 driving inlet valves 182 and exhaust valves 184 in inlet ports 186 and exhaust ports 188, respectively. The engine 15 IB also has a water jacket 190. The engine relies upon a wet sump configuration. The engine 15 IB is similar to the engine 10 and like numerals denote like

parts.

In use, the engines 150, 151A and 151B (as well as the engine 10) operate substantially without vibration since the forces generated by the movement ofthe pistons 60, the connecting-rods 58 and the crankshafts 56 all substantially oppose each other and cancel out.

This has the advantage that the engine is substantially without vibration which is most desirable for use as an aircraft engine, or in hand tools or the like. By the arrangement of the moving components in the engine not only primary vibrational forces are balanced out, but so to are secondary vibrational forces and tertiary vibrational forces. ROTARY INTAKE VALVE

In Figures 13 and 14 there is shown a cross-sectional view ofthe engine 10 of Figures 3 & 4. The engine 10 as shown in Figures 13 and 14 also has a fan mandrill 200 for connection to a fan (being the life fan ofa VTOL aircraft for example) or the like. The mandrill 200 is fixed to a free end ofthe output shaft 28. The gearbox 22 has two gearbox housings 210 which are secured between the front and rear balanced banks 42 and 44.

The output shaft 28 has a plurality of ports disposed along its length. The ports include an inlet port 220 which is coupled to the carburettor 29, and four outlet ports 222, 224 , 226 and 228. The outlet port 222 is shown in Figure 13 as communicating between the carburettor 29 and the piston pair "6" and "7". The outlet port 224 communicates between the carburettor 29 and the piston pair "5" and "8" and the outlet ports 226 and 228 correspond to piston pairs "2" and "3", and "1" and "4".

In the arrangement shown in Figure 13 the output shaft 28 is rotated to a location at which air/fuel mixture from the carburettor 29 passes through the middle ofthe output shaft 28 and into the cavity behind the pistons 60 of cylinders "6" and "7". As the output shaft 28 rotates the outlet port 224 matches with the cavity behind the pistons 60 of cylinders "5" and "8", outlet port 226 wit cylinders "2" and "3", and outlet port 228 with cylinders "1" and "4".

Hence, in this configuration the output shaft 28 also serves as a rotary intake valve ofthe present invention. In a non-geared configuration the output shaft 28 has one outlet port 222 to 228 for each cylinder pair "1" and "2", "3" and "4", "5" and "8", and "6" and "7". When the engine 10 is geared, there is provided a number ofoutlet ports corresponding to the gearing. For example, in a 2:1 gearing there is provided two of each ofthe outlet ports 222 to 228 so that each cylinder 24 can fire twice per rotation ofthe output shaft 28. With a reduction gearing of say 3:1 and two balanced banks 42 and 44 the number of ports 222 to 228 in

the output shaft 28 is: number of ports = gearing x number of banks x 2 = 3 x 2 x 2 = 12

In this way the output shaft 28 also acts as an inlet manifold.

In use, fuel and air mix in the carburettor 29, flow through the inlet port 220 and into the output shaft 28. As the output shaft 28 rotates one ofthe outlet ports 222 to 228 matches with the cavity behind its corresponding cylinders "1" and "4", "2" and "3", "5" and "8", or "6" and "7" so as to allow the air/fuel mixture to enter into the cylinder 24 for combustion therein.

The rotary intake valve ofthe present invention has the advantage that it can be used with multiple cylinders and multiple crankshafts 58. Also the rotary intake valve readily facilitates use with geared engines. Also, the rotary intake valve reduces the weight and cost ofthe engine since an intake manifold is not required.. Further the rotary intake valve provides substantially equal resistance to the flow of air/fuel mixture to each ofthe cylinders 24. Still further, the passage ofthe air/fuel mixture though the output shaft 28 has the effect of cooling the output shaft 28 and the gearbox 22.

Modifications and variations such as would be apparent to a skill addressee are considered within the scope ofthe present invention. For example, the base engine 40 could be in accordance with the that shown in Figure 3 or could be an off-the-shelf engine. Also, spark devices other than glow plugs could be used - such as, for example, conventional spark plugs. Further, engine fuels such as petrol, diesel, gas and the like could be used for the IC engine (10).