AU2005201319A1 - An Improved Rotary Piston Machine, suitable for a wide range of environmentally friendly fuels - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT An Improved Rotary Piston Machine Suitable for a Wide Range of Environmentally Friendly Fuels.

Title and Contents.

An Improved Rotary Piston Machine Suitable for a Wide Range qf Environmentally Friendly Fuels.

Historical Background.

Theoretical Background.

1-6 Physical Description of the Initial Rotary Piston Machine.

1-8 Improvements to the Initial Rotary Piston Machine.

1 -12 Claims.

1-12.

Diagrams.

1-10 Page 1 2 4 7 9 16-25 An Improved Rotary Piston Machine Suitable for a Wide Range of Environmentally Friendly Fuels.

Historical Background This invention relates to significant new improvements to an extremely efficient positive displacement rotary piston machine whose patent has expired long ago. The basic concepts for either engine or pump were patented in 1930 1931 by Rudolf Schmidt of Liechtenstein. Several other inventors have attempted to adapt the original idea for use specifically as an internal combustion engine. The latest patented use of the basic mechanism has been by Kaare Vatne of Sweden in 2002 still using petrol etc in an internal combustion engine.

None of these inventors have adapted the basic concepts specifically for steam. None of the previous inventors have specially adapted the basic concepts for hydrogen combustion. The internal combustion mechanisms so far proposed have all been relatively complex compared to the simple use of steam power, Previous inventions have involved compression strokes, fuel injectors or carburettors, spark plugs etc. These complexities and resultant inefficiencies have probably contributed to the basic concept not gaining widespread use. Furthermore an over-commitment to fossil fuels has probably prevented previous inventors appreciating the potential of steam. Nowadays with recognition of the non-renewable nature of fossil fuels and the net greenhouse gases they produce, both governments and private enterprise are becoming oblied.to find practical alternatives to fossil fuels.

The present patent application also relates to other specific improvements including a means of eliminating a "dead spot" from the stroke of the basic concept, improving friction, reducing some sealing losses, providing a means of reversing the rotation, adapting the basic mechanism for steam or hydrogen power, and the option of incorporating a gear-box function within the machine itself.

The present patent applicants, a father and son team, Ken Smith and Errol Smith, independently re-derived the initial basic concept while trying to design an extremely efficient engine from first principles. When we realised that it had been invented before we were surprised that it had not gained widespread use, since on paper it seemed an extremely good concept. We made a working model of the initial basic concept and discovered three areas of design weakness and are claiming novel solutions to these weaknesses. We have found our prototypes of the improved rotary piston machine have addressed these three shortcomings without introducing other significant complications, and overall function very well.

We have also adapted the basic concept so that the machine may incorporate gearing without the usual independent clutch and gearbox.

Lastly we have several specific adaptations which best suit the rilachine being a pressurised steam driven engine. Steam enables a great versatility of types of fuels, which may be used. Other advantages of steam over internal combustion include cleaner burning in non-explosive combustion. Being able to use fuels, which are not explosive, includes some fuels, which are green house gas emission neutral, which would not otherwise be practical sources of energy -in particular ethanol, canola, and methane. Hydrogen may also be used as either to heat steam in a non-explosive external combustion or as an explosive fuel in an internal combustion arrangement.

The improved rotary machine functions well as an engine but also a pump if it is driven by external rotary force acting on a fluid.

The present inventors hope that the basic concept of the 1930's can finally reach its potential with the invention of the improved rotary piston machine at a time when people are more conscious of the importance of environmentally friendly fuels.

Theoretical Background In designing a machine to convert pressure to rotary motion, or visa versa, there are a number of features that an inventor tries to optimise. The following points roughly trace the thought processes that we went through in re-deriving the initial basic concept and then improving its weaknesses. The initial rotary piston and improved rotary piston machine fulfil to varying degrees the design features listed below as indicated in the accompanying brief comments.

1. High efficiency of energy conversion due to: a. Using a positive displacement mechanism in contrast to a turbine.

Turbines function inefficiently at low revolutions, and do not entirely confine the pressurised fluid allowing it to escape thus losing energy.

The initial and improved rotary piston machines are both positive displacement mechanisms.

b. Minimising the number of reciprocating parts as energy is wasted in driving reciprocating parts.

The initial and improved rotary piston machine each have no reciprocating or oscillating parts.

c. Minimising the number of moving parts resulting in less risk of jamming, usually associated with less frictional surfaces, and ease of manufacture and assembly.

The initial and improved rotary piston machine each have only two moving 'arts.

d. Minimising the weight of the machine.

The small number of and simplicity of the components, the near constant pressure (non-explosive) operation allow for a very efficient weight to power design of both the rotary piston and improved rotary piston machine itself. The major weight in many practical applications as an engine would be in the generation of pressurised fluid, for example a steam boiler etc. However the nature of the boiler etc is not the subject of this patent and others inventors are working on developing more efficient boilers.

e. Maximising the torque produced by applying the pressure source at right angles to the axis of the rotating drive shaft.

The initial and improved rotary piston engine each have the pressure applied to the driving piston face at only a few degrees off 90 degrees to the shaft axis.

f. Maximising the proportion of the power stroke. This is equivalent to minimising the non-driving portion, or dead spot" of the stroke.

The initial rotary piston machine has a constant power stroke for over of the action. The improved rotary piston machine can have the residual small percentage of "dead spot" operating with at least power. This enables the machine to operate without a clutch even if it happens to stop or start at a relative non-power portion of the stroke.

g. Operating at constant torque.

The initial rotary piston has a small percentage of its stroke being almost zero power, otherwise it produces a near constant torque, unlike the action of even the power stroke of a reciprocating piston and crankshaft, which varies from zero to near 100% in an quasi-sinusoidal manner.

h. Minimising leakage of the pressurised gas through any sealing interfaces and valves etc.

The initial rotary piston machine has an area near the centre of the mechanism, which is difficult to seal well. See diagram 3, area "B"I The other surfaces are relatively easy to seal. The improved rotary piston machine has several mechanisms, which may be used individually, on in combination, which greatly improve the sealing at the central region.

I. Minimising friction.

Generally speaking both machines have neat fitting smoothly curved or flat large surfaces that are moving parallel to one another and are not load-bearing, hence can be machined to a close tolerance with little or no touching of the adjacent surfaces. Neither machine is suitable for piston rings which reduces the sliding friction, although does pose some limits of the leakage ofpressurised fluid past the piston, this is mitigated by have very long pistons.

The initial rotary piston machine generates considerable friction on one side of fhe main bearing of the driving shaft. The improved rotary piston ma'chine has a novel mechanism which reduces this particular load bearing friction many-fold. However this introduces a separate non load-bearing surface which requires sealing. Overall friction is reduced because non load-bearing surfaces generate less friction than load bearing surfaces.

2. Minimising vibration and unbalanced torques.

a. Very little vibration is developed due to the absence of reciprocating or oscillating components.

b. The rotation of each piston occurs at a uniform rate, since there is an approximately constant supply of pressure to the piston face.

There is almost constant angular velocity throughout the cycle.

c. The moment of inertia of each individual rotating piston may be individually balanced further reducing sources of vibration.

d. There is no unbalanced torque in the machine itself since it comprises two equal members rotating in opposite directions on parallel axes. Even during acceleration there is no net torque developed by the machine housing itself, although any rotating external load would inevitably generate an unbalanced torque on acceleration.

3. Maximising ease and mi.nimising expense of manufacture a. Simplicity of design.

b. Few parts.

c. No exotic materials or manufacturing techniques.

d. Minimal pollution involved in manufacturing.

4. Maximising robustness, durability, compactness, and minimising maintenance.

a. No flimsy components. Unlike vane motors and many other systems with valves under pressure, and unlike the piston ring sealing difficulties of Wankel engines.

b. Given low friction good durability, there should be good wear characteristics, particularly if a lubricant is used.

Apart from cleaning deposits related to the possible use of lubricant in the pressurised fluid, no regular maintenance of the machine itself.

d. Compactness is very good due to the simplicity etc., the least compact part are the steam generators and condensers.

Maximiging-the range of fuels applicable.

There is a very wide range of fuels that can generate pressurised fluid suitable for use in the rotary piston engine and improved rotary piston.

Both internal and external combustion, explosive and non-explosive reactions are possible. One is thus able to choose the fuels that are least polluting, least toxic, least expensive, most available in the situation one the user finds him or herself in.

Hydrogen fuels can be used explosively or non-explosively and are, non-polluting. One could use explosive "fossil fuels", but this seems undesirable environmentally and is unsustainable. Renewable fuels like ethanol, canola, bio-diesel and methane etc are possible, and their advantage is that they can be used effectively either explosively or non-explosively. When coupled to a steam boiler the same engine could use just about any flammable fuel. Ethanol etc have a high energy to weight of fuel ration, are overall green house gas neutral, and less polluting in terms of sulphur compounds etc, than are some other renewable flammable fuels like wood or non renewable fuels like coal. The most practical arrangements for many engines involved in transportation would seem to be a steam engine power by ethanol, biodiesel, methane etc or a mixture of these fuels.

6. Minimising noise.

The use of non-explosive fuels is probably the biggest factor, hence the advantage of steam. Minimising vibration is also important see above.

Physical Description of the Initial Rotary Piston Machine.

The basic mechanism of the previously patented rotary piston machine is readily seem in diagrams 1-5, and are described under points 1-8 here below.

The features of the improved rotary piston machine can be seen in diagrams 6- and will be discussed and described later under "Improvements 1 -11.

The relevant features to observe when the initial rotary piston machine functions as an engine, as distinct to a pump, are as follows: 1. A fixed, solid, enclosed housing with pressure inlet, and exhaust outlet.

2. Two rotating pistons, of equal size and shape as indicated in diagram 1.

These rotary pistons, (or "rotors" in the diagram), are mounted solidly on two parallel axies and intersect within the housing in the central region. The axels of each rotary piston are supported by bearings and/or bushes, attached solidly to the housing. There are circular seals between the flat surfaces of each rotor and the housing. The diameter of the seals needs to be less than the smaller of the two diameters of the rotors so that the seals do not interfere with the meshing of the two rotors. Only one of four similar seals is illustrated.

3. One piston turns clockwise and the other anticl6ckwise. The speed of rotation of each piston is kept equal and synchronised by two equal gear wheels, solidly attached to each axel as in diagram 1. The gear wheels mesh outside the housing and rotate at the same rate as the pistons inside the chamber.

4. The pressurised fluid input exerts force at right angles to all the surfaces that confine it as governed by usual fluid dynamics. The pressure exerted against the smaller radius half of each rotary piston is directed towards the centre of each axel and is taken by the bearings or bushes. Depending on the efficiency of the bearings or bushes this inwards pressure has some effect on the rotation of the pistons, in addition to whatever friction is developed in the bearings or bushes without pressure applied. This is discussed later under improvements to the initial rotary piston machine. Fortunately the major effect is due to the pressure exerted on the face of the piston. This force is nearly at right angles to the rotational axis of the piston, the divergence from degrees being indicated by the small angle on diagram 1. The torque is: Torque =Pressure x Surface Area of face x average radius at face x cos(A) For this reason the shape of the faces are designed have as close to zero degrees as possible while still providing smooth meshing of both rotating pistons and minimising the space between the almost touching two pistons throughout the cycle of operation. The involute shape of the face is the same as that of one of the cogs of an ideal set of rotating equal geared wheels.

Typical values of cos(A) are approximately 0.95,- a high degree of efficiency.

The area near the centre of the mechanism where the larger convexity of one piston almost touches tangentially the smaller convexity of the other piston deserves special consideration. It is the area where pressure fluid can most easily escape and efficiency be lost. See area on diagram 3 for a typical situation.

Firstly the separation between these two surfaces needs to be kept as small as possible because pressurised fluid can more easily escape via this route than around the space between the greater convexity and housing since the distance the close approach is much shorter. In an idealised mathematical construction the tangent exists at merely one point.

Secondly the close separation of the two surface at area B can be able to be accurately machined at one temperature but result in jamming or significant leakage at other temperatures, given the wide range of temperatures from a cold start to peak performance with most fuels or pressurised fluids. Not using superheated fluids or explosive fuels is no doubt useful but not a sufficient solution to this sealing problem at area B.

Of course this problem could be minimised by intelligent design in matching the thickness of the housing and piston components, and by appropriate choice of materials with regard to their thermal coefficients of expansion, but there would always be some compromise in these design aims being fulfilled.

Further variations due -to compensating for rapid or gradual changes in temperature that would frustrate any ideal design solution.

One cannot attempt to overcome the leakage problem by having the smooth curved surfaces physically touch with any significant pressure since the robust nature of the pistons would immediately transfer any pressure to the main bearings or bushes with significant increases in friction.

Other solutions involving small adjustments to the separation at area B by changing the distance between the two generally fixed axes of each piston would necessarily involve compensatory changes in the housing and although theoretically conceivable would be highly impractical.

One could possibly attempt a mechanical solution to the problem by covering both the surfaces of the greater and lesser curvatures with small intermeshing cogs, as in diagram 9. However the subsequent frictional loss due to the meshing of the gears would probably be counter-productive. Nevertheless this is one novel solution which the present inventors are claiming, though not the best solution to the sealing of area B.

The best novel solutions to this problem that we have found will be discussed later under improvements to the Initial Rotary Piston Machine.

6. Two significant features of the basic rotary piston mechanism are firstly the almost 100% power stroke, and secondly a near constant torque. In both respects contrasting most favourably with both reciprocating pistons and crankshafts, and Wankel type mechanisms.

The near 100% power stroke can be understood by reference to the series of diagrams illustrating the complete cycle. Observe that the crossover from one piston being active to being passive takes place over only a few degrees, hence the nearly continuous power stroke.

The nearly constant torque is delivered because of the constant cross section of the surface area of the piston at its face, being exposed to the constant pressure source. This is unlike the variable surface area exposed to the input pressure in many "gear pump" and Wankel mechanisms.

7. An important feature of this rotary piston machine is the alternation of each piston being the active driving member or passive member. See the progressive diagrams 2 to 5. Note the movement of the raised portion of each rotating piston directs the pressure in the direction desired for rotation. Note also that the raised portion of each rotary piston acts like a valve in this respect. There is very little "dead spot" between the change over from one piston being active to the other being active. This dead spot does occur when the tangential seal between the pistons is most variable and most likely to leak. See area"'8n diagram 3 lf the initial rotary piston machine happened to stop at the dead spot it would be difficult to start again, especially against a load. This is an area of design weakness that the present inventors will later claim two novel solutions.

8. There are no piston rings. The geometry of the rotary piston mechanism makes piston rings almost impossible. Adequate sealing requires a sturdy construction with close tolerances in machining, and a relatively narrow range of operating temperatures more possible with the use of steam than with explosive fuels. The use of materials with low coefficients of thermal expansion, and the careful matching of thicknesses of materials of the housing and pStons so that both expand similarly with temperature are important: Improvements to the Initial Rotary Piston Machine.

01. The first improvement is the specific adapting of steam power to the Initial Rotary Piston Machine. This involves a boiler and pressure monitoring, fuel input and controls, throttles, steam collection condensation and recycling.

C These items and arrangement of them are certainly not new in themselves but the use of these in this application is being claimed as new.

2. This second improvement addresses the so-called "dead spot" that occurs when the pistons mesh and the driving piston becomes the passive piston as described in section 7 of the "Physical Description.." above. The second Simprovement overcomes the zero torque for these few degrees of the cycle by having at least two'chambers and at least two pairs of rotary pistons mounted CI together. One of the axels is shared by all pairs of pistons. This axel is the v' obvious choice for the common driving axel.

c The important feature is that the sets of pistons are out of phase. See diagram 6 which illustrates a twin chamber set up as an example of multiple chambers.

When one uses two chambers the pistons are ideally 90 degrees out of phase, if one uses three chambers each is 60 degrees out of phase etc.

When one set of pistons enters the dead spot of its cycle at least one of the other sets of pistons is midway through its stroke. There is always about half the maximum torque at all points of the cycle with a twin chamber engine, and two-thirds maximum torque with a triple chamber engine etc.

3. A third impr6vement is also relevant to the stage of the cycle in which the faces of the rotary pistons intermesh and the active piston becomes passive.

This is a stage of poor efficiency due to increased potential for leakage given the very small area in which the two surfaces are in close approximation.

One can eliminate leakage and thus inefficiency by have a switching mechanism that cuts off all pressure to the chamber at this stage of the cycle and reconnects it as soon as the inefficient portion is passed. In a single chamber this pressure is reserved or stored briefly in the pressure capacitance of the input system. With multiple chamber designs the pressure is effectively diverted if the input pressures are arranged in parallel.

4. The fourth improvement addresses the friction developed in the central bearing of each piston when it is the active, driving piston. This friction is maximal at the end of the active stroke, see diagram 2. The use of high performance, low friction bearings or bushes, with the use of an appropriate lubrication system etc, is an obvious way to minimise this friction. However, the present inventors are claiming a further novel way of reducing this friction which may be used in conjunction with the above obvious methods.

Considering the origin of the frition is due to the pressure applied to the smaller convex surface in diagram 2, if one can reduce this surface area then the friction can be reduced. Now if one designs the cross section of the piston and housing in a shape, (or similar variant), as in diagram 7, (left lower comer of diagram), then the pressure on the bearings is reduced by the ratio X Y, where X and Y are the proportions shown in diagram 7. The ratio X Y depends on the strength of the materials used, but could easily exceed a O factor of about 5: 1. This proposal does introduce an additional surface which is similar to the large curvature of the housing, and requires close tolerances but does not require other sealing. Surface is not a load bearing surface as was the central bearing. Therefore one is exchanging the Shigh friction between two load bearing surfaces in contact for a much lower friction between two very close surfaces but not in direct contact. Overall there C, is a net reduction in friction with this improvement to the rotary piston machine.

The fifth improvement addresses the problem of the mere tangential sealing at the point where the greater curvature of one piston approaches the smaller curvature of the other piston. Recall diagram 3, area and the ticussion at section 5 of physical description of Initial Rotary Piston Machine.

A Hovel solution to this problem only became apparent while Ken Smith was i c6nstructing a working model that incorporated the fourth improvement described aboye. Serendipity follows hard work! It is less easy to visualise in two dimensions than the other improvements but careful study of diagrams 7 and 8 should demonstrate its features. In'diagram 8 One can preserve the size and shape of the rotary pistons in the narrow entre portion of the "T" shaped cross section, but one can increase the diameter of the lateral portions of the and enlarge the corresponding chamber for the lateral portions. This produces a short arc in which the lateral portions move, rather than approaching the other piston at a tangent. Only at the lateral arms of the cross section does this surface to surface sealing rather than tangential point sealing occur, and not at the central point of the which remains the same as in diagram 7. Given that the ratio of the central to lateral portion, X Y can be at least 5: 1, this is improved sealing for 80% of the area 6. Another second novel approach to sealing at the central tangential approach of the two pistons can be accomplished through the use of small intermeshing cogs arranged on the greater and lesser curvatures as in diagram 9. This introduces more friction due to the meshing of the surfaces but may, depending on the exact characteristics of the gearing be offset by the improved sealing. It introduces the possibility of eliminating the two equal uniformly geared wheels, external to the housing, relying on the small cogs in the rotary pistons themselves to maintain synchrony.

7. A third approach to sealing at the central tangential approach of the two pistons is applicable to steam engines or other similar pressurised gas. It involves the injection of the liquid phase of the gas into the chamber at points D1 and D2 on diagram 10. Because the liquid is more viscous than the gas there is less tendency for it be blown past the tangential approach of the two pistons at the central region. One could also inject a gas with an added slightly lubricant, such as so called "steam oil" which would form a dual function as lubricant and partial sealant.

This injection of either gas or liquid would require a small auxiliary pump probably driven indirectly by the main active mechanism, able to inject small amounts of liquid into the already pressurised chamber. There are many similar arrangements in existing fuel injection mechanisms that are able to titrate the amount of fluid injected to the needs of the system. There may be overall advantages of improved sealing over the energy loss due to the driving an additional injector system.

If the liquid vaporised while in the relatively hot chamber that would not be a problem since it would merely create more gas though at a slightly lower temperature.

If there was a build up of liquid due to a mismatch in the injector control the fluid would tend to be blown out along the usual path of the gases, but would probably add to the friction due to the increased viscosity of any excess fluid compared to merely gas.

8. The eighth possible improvements to the initial rotary piston mechanism does arise from any particular design weakness in the initial basic concept, but rather seeks to incorporate the function of a gearbox within the machine itself. Both these improvements eliminate an independent gearbox and thus eliminate all the energy losses associated with multiple gear races and gear changing mechanisms. The clutch is also redundant saving energy through a reduction in the number of moving parts, and eliminating the energy lost via heat generated by the friction mechanism of most clutches. In many applications instead of the engine idling awaiting engagement of the clutch and gearbox, the engine could be completely stationary and not wasting energy tuming'over with no load. In the example of a steam engine, the energy input to the boiler while "idling", would merely add to the head of steam ready for rapid acceleration when the engine does start.

The eighth improvement introduces gearing into the rotary piston mechanism via the hydraulic principle that the force on a given surface from a given reservoir of fluid under pressure is proportional to the surface area to which the force is applied. In other words in the rotary piston set up the torque can be changed by changing the surface area of the face of the rotary piston.

One way this can be accomplished is by having a multi-chamber rotary piston engine, each with a set of rotary pistons, staggered as in the arrangement described in improvement number 1. If all chambers are exposed to the pressure source there would be a relatively large surface area of piston involved and a high torque low rev's gear would be accomplished. This is especially appropriate when in most situations such a "low" gear is beneficial for starting from a stationary position and the dead spot problem, (addressed by improvement number is optimally addressed by having all staggered chambers in use. As the engine gains speed and angular momentum, the need for the dead spot to be specifically eliminated is reduced since the angular momentum is sufficient to carry the machine through the relatively small portion of the dead spot. As the rate of rotation increases it become possible to cut off the pressure to one of the chambers and concentrate it on the remaining piston face(s), thus increasing changing to a "higher" gear.

~iI Note that this is not merely adjusting the throttle by constricting the pressure flow, but a genuine hydraulic gearing mechanism.

The number of chambers, each with a set of rotary pistons determines the number of gear ratios available. If each set of rotary pistons is exactly the same depth, then one gets a gearbox with evenly distributed gear ratios. In practice this is not usually the most practical system in most applications and one may have a set of rotary pistons of variable depth as in diagram. This variation allows an even greater number of gear ratios than at first suspected since there are N factorial plus one combinations of different total gear ratios form a N-chambered engine if one chooses the depth of each piston appropriately and is able to cut off each chamber independently.

For example, with a two chambered machine with piston surface areas, and 0.5 square units respectively, there are actually three gear settings corresponding to surface areas; 0.5, 1.0, With three chambers with surface areas 1.0, 0.3, 0.4 square units, one has 7 gear settings corresponding to surface areas; 0.3, 0.4, 0.7, 1.0, 1.3, 1.4, 1.7.

The exact depth of each piston can be varied to suit the application.

The construction of multiple chambers of variable depth mounted in line on the one common driving axel does however increase the frictional surfaces compared to a non-hydraulically geared machine of the same capacity. In order to minimise these losses, in addition to the methods discussed above one may redue the pressure in the non-active chambers to a near vacuum.

This would reduce the friction between all the surfaces between the rotary pistons and housing, these areas are closely machined to very close tolerances and are not touching. The friction generated between these surfaces is primarily due to turbulence in any gas or liquid that is trapped between the surfaces. The surfaces are not close enough to be significantly effected by Van der Waal's forces and magnetic eddy currents could be reduced by choice of materials.

One problem associated with the use of varying combinations of a multichamber rotary piston engine is that there would be differing amounts of load and hence wear. However the advantages of having a multi-speed gearbox integrated within the engine itself with very little extra weight added, probably outweigh the use of an external clutch and gearbox, each with its own weight and energy loss in transmission.

9. A ninth improvement which is fairly obvious but has not been specified by previous inventions involving the basic rotary piston concept is the reversal of the direction of rotation by merely reversing the pressure inputs and outputs.

This would need to be accompanied by opening and closing appropriate sized ports in the inlet and outlet regions to enable the depressurised gas to escape more readily.

A tenth improvement relates to the practical issue of finely synchronising the rotary pistons and toothed gear wheels during manufacture and maintenance. Fine adjustment can be supplied by elongated holes with screws through which the timing gears are bolted to flanges connected to the axles or drive shafts.

11. An eleventh improvement is the inclusion of an optional second exhaust as illustrated on diagram 3. The diagram shows well how this works.

12. A twelfth possible improvement is the use of hydrogen, not just as a fuel to heat steam, but directly into the inlet port and exploded with the assistance of an ignition device, probably some sort of spark plug.

Claims (10)

1. The specific use of steam power to drive the Initial Rotary Piston Machine described in the basic concept sections, or the Improved Rotary Piston Machine incorporating any or all of the improvements numbered 2 to 10 listed above.

2. The use of multiple chambers and multiple pairs of rotary pistons to overcome the dead spot of the stroke as described in improvement 2.

3. The use of synchronised switching of pressure to reduce the power lost at the dead point of the stroke as described in improvement 3.

4. The or similar shaped cross section of the rotary piston which reduces the friction developed in the main axel bearings as described in improvement 4. The use of differing diameters of the shaped cross sectioned pistons and appropriate recessing of the housing to enable better sealing of the tangential approach of the pistons as described in improvement

6. The use of intermeshing cogs on the large and small curvatures of each rotary piston enabling better sealing of the tangential approach of the pistons as described inimprovement 6.

7. The specific use of viscous lubricants in the pressurised gas in a rotary piston engine,4he.lubricant being concentrated at the tangential approach of the pistons, enabling better sealing as described in improvement 7.

8. A variable speed gear box, using a multiple chamber arrangement in various combinations, the chambers being of either the same capacity or different capacity, as described in improvement 8.

9. A reversing switch as described in improvement 9. Oine adjustment of the rotary pistons and synchronising gear wheels as de, bed in improvement

11. The use of extra exhaust port(s) as described in improvement 11.

12. The use of hydrogen as an internal combustion fuel as described in improvement 12. Ken Smith 29 t h March 2005 Errol Smith