WO2008131490A1 - Method and apparatus for external combustion engine - Google Patents

Abstract

The present invention relates to external combustion engines (ECE) and heat exchange. One particular aspect of invention relates to a high performance steam engine for cars. One embodiment provides an ECE comprising: an engine body (10) having an inlet (2) and an outlet (3) for the passage of a heated working fluid into and out of an expansion zone (34) wherein the body of the engine (10) is configured as a heat exchanger for heated working fluid exhausted through the outlet (3). Another embodiment provides a boiler tube arrangement for an ECE comprising at least one wound tube (12) forming a radially inwardly directed path for combustion gases and the at least one wound tube (12) is adapted for transporting a working fluid in a radially outwardly directed path to exchange heat with combustion gases. Other embodiments provide air delivery arrangements, an acoustic outlet, valve control for ECE's, and means for determining mass flow rate of steam for controlling an ECE.

Description

METHOD AND APPARATUS FOR EXTERNAL COMBUSTION ENGINE RELATED APPLICATIONS

This application claims priority to Australian Provisional Patent Application No. 2007902269 in the name of Palms Institute Pty Ltd, which was filed on 1 May 2007, entitled "Method and Apparatus for External combustion Engine" and, the specification thereof is incorporated herein by reference in its entirety and for all purposes. FIELD OF INVENTION

The present invention relates to the field of external combustion engines. In one form, the invention relates to improvements in the operating efficiency of an external combustion engine. In one particular aspect the present invention is suitable for use in a steam engine for land vehicles and it will be convenient to hereinafter describe the invention in relation to a high performance steam engine for cars, however, it should be appreciated that the present invention is not limited to that use, only.

BACKGROUND OF INVENTION

The discussion throughout this specification comes about due to the realisation of the inventor and/or the identification of certain related art problems by the inventor. By way of background, steam powered cars have been produced since the beginning of the automotive vehicle industry and have often been associated with high performance vehicles. For example, it has been reported that in 1899 a Stanley "Steamer", driven by F.O. Stanley, became the first car to reach the summit of Mount Washington, New Hampshire, USA. F.O. Stanley was one of the Stanley twins, founders of the Stanley Motor Company, which specialized in steam-driven automobiles. These particular steamers not only climbed mountains, but were often known to beat larger, gasoline/petrol-powered cars in races. For instance, in 1906, a Stanley Steamer, piloted by Fred Marriot, broke the world record for the fastest mile when it reached a recorded 127 miles per hour (rnph). As noted by "The Steam Car Club of Great Britain" (http://www.steamcar.net/pat-farrell.html), the following year at the annual automobile speed trials in 1907, conducted at Ormond Beach, Florida, a Stanley Steamer called "The Flying Teapot" reportedly reached a speed of 197 miles per hour. Unfortunately, just before reaching a reported 200 mph it hit a bump, "took off like a bird" and according to Glenn Curtiss, who may be considered as one of America's foremost manufacturers of record breaking motorcycles and aeroplanes was quoted in Scientific American of 9 February 1907, "the floor then became an aeroplane". The result being that the vehicle crashed on the beach, "a total wreck". Nonetheless, no petrol/gasoHne-driven car was known to have reached 100 mph at those 1907 trials. In fact, the record set by the Stanley vehicle was not broken by a petrol/gasoline machine until 1927, and then by a four ton model with two twelve-cylinder airplane engines. In general terms, a steam engine is an external combustion engine (ECE - the fuel is combusted outside the engine's cylinders), as opposed to an internal combustion engine (ICE - the fuel is combusted within the engine's cylinders). Petrol/gasoline-powered ICE cars may have a fuel efficiency of about 35%, which may drop off sharply with movement away from an optimum operating point. Steam engines per se have been considered capable of around 40% efficiency. Whiie steam powered cars may have a lower peak efficiency rating than ICE cars, ie lower than about 35%, this rating may remain relatively constant over a wide power range making overall fuel economy comparable to that of ICE powered vehicles. An additional benefit of the ECE is that the fuel is burned at atmospheric pressure and so may not produce carbon monoxide and nitrogen oxide, thus significantly avoiding this kind of pollution. As opposed to ICE powered vehicles, steam-powered cars (and even electric cars) outsold petrol/gasoline powered cars in many U.S. states prior to the invention of the electric starter. By way of explanation, before the electric starter was put into production by General

Motors™, internal combustion powered cars were started by hand-crank, which was difficult and occasionally dangerous, as improper cranking could cause a

'backfire' with compressive forces capable of breaking the arm of the operator.

It is considered that the first usabie steam car appeared in 1899 from the Locomobile Company of Bridgeport, Connecticut, USA, which manufactured several thousand of its 'Runabout™' model in the period 1899 - 1905, designed around a motor design leased from the Stanley Steamer Company. Most early steam cars basically had a boiler with a large quantity of water to be heated, and a non-condensing, single-expansion, steam engine, permanently geared to the drive wheels (reversing was normally accomplished with valving in the engine). Accordingly, these vehicles had a large thermal storage capacity, which could be useful in operation to minimize boiler control problems, however because of this, they coutd take some time to start from cold, but once fully fired up and working pressure was attained, they could be effectively instantly driven off. The landmark Doble Steam Car shortened the starting time very noticeably by incorporating a flash steam generator which heated a much smaller quantity of water as required in addition to lessening the severity of a steam leak to the smaller volume of stored steam. Accordingly, the Dobfe designs were considered to be almost completely condensing but still consumed a lot of water. By 1923, Abner Doble had developed an automatic boiler and burner which allowed his steam cars to be started with the turn of a key and driven off in around 40 seconds or less. In addition, the Doble cars managed to achieve 15 miles per gallon of kerosene despite weighing in excess of 5,000 ibs.

A useful overview of steam car design summarizing developments from the early era into the modern period is found in a paper by James L, Dooley and Allan F Bell of McCulloch Corp entitled "Description of a Modern Automotive Steam Powerplant" for the Society of Automotive Engineers, Inc, Los Angeles Section 22 January 1962, in relation to the Paxton Phoenix™ automobile styled by Brooks Stevens and making use of and improvements to Abner Doble's designs. Whilst the Paxton steam car development may be considered technically successful, it was discontinued in 1954 reportedly due to business and economic considerations that placed the state of the art at the time of ICEs and automatic transmissions well ahead of steam car technology.

In more modern times, as a result of the 1973 oil crisis, interest was rekindled in steam powered vehicles for the road. For example, SAAB™ started a project in 1974 headed by Dr. Ove Plateϊl which made a prototype steam powered car. It used an electronically-controlled 28 pound multi parallel circuit steam generator with 1 millimeter bore tubing and 16 gph (gallons per hour) firing rate which was intended to produce about 160 horsepower, and was about the same size as a standard car battery. Lengthy start-up times were circumvented by a system using compressed air that was stored when the car was running and which powered the car upon starting until adequate steam pressure was built up. The engine used a conical rotary valve made from pure boron nitride. To conserve water, a hermetically sealed water system was attempted. A company called Enginion AG had since 1996 been developing a system which they have named SteamCell™. It reportedly produces steam almost instantly without an open flame, and takes 30 seconds to reach maximum power from a cold start. Their third prototype, ZEE03, was fitted in Volkswagen™ and Skoda Fabia™ automobiles. The ZEE03 was a two-stroke of IOOOcc displacement, producing up to about 220 hp (500 nm). Exhaust emissions were reportedly far below the SULEV (Super Ultra Low Emission Vehicle) standard. Since the water was recirculated, the engine used steam instead of oil as a lubricant. However, Enginion found that, at that particular time, the market was not ready for steam cars, so they opted instead to produce power generators based on the same technology. Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material forms a part of the prior art base or the common general knowledge in the relevant art in Australia or elsewhere on or before the priority date of the disclosure and claims herein. SUMMARY OF THE INVENTION

It is an object of the embodiments described herein to overcome or alleviate at least one of the drawbacks of related art systems or to at least provide a useful alternative to related art systems.

In a first aspect of embodiments described herein there is provided an engine assembly comprising: an engine body having an iniet and an outlet for the admission of a heated working fluid into and out of an expansion zone wherein the body further comprises a heat exchange zone for the heated fluid. The heat exchange zone at least in part may surround the expansion zone. The heat exchange zone comprises a condensation and/or cooling zone adapted to transfer heat from the working fluid to the engine assembly.

In a preferred aspect of embodiments described herein there is also provided an engine assembly comprising: an engine body having a plurality of cylinders adapted to facilitate the expansion of a heated working fluid wherein the body comprises at least one heat exchange zone disposed within the body adjacent the cylinders. The heat exchange zone may comprise a plurality of heat extraction chambers aligned in correspondence with the cylinders.

In another preferred aspect of the embodiments described herein there is provided an engine comprising: an engine body having an iniet and an outlet for the passage of a heated working fluid into and out of an expansion zone wherein the body of the engine is configured as a heat exchanger for heated working fluid exhausted through the outlet. The heat exchanger may comprise one or a combination of. an engine block; at least one cylinder; an engine head; a rocker cover; a sump; engine oil; a cylinder head; a gear box; exhaust pipes; whole engine. In yet another preferred aspect there is provided a method of operating an external combustion engine comprising the steps of: heating a fluid; inputting the heated fluid into an engine; expanding the heated fluid; using at least a portion of the engine assembly to exchange heat with the heated fluid exhausted there through.

In a further preferred aspect there is provided an engine arrangement comprising: an engine body; and an inlet for the admission of heated working fluid into an expansion zone within the body; wherein the inlet is adapted to insulate the heated working fluid from the body so that the working fluid substantially maintains its temperature to the point of its admission into the inlet to the expansion zone: In another preferred aspect there is provided an engine arrangement comprising: an engine body operatively associated with an inlet for the admission of heated working fluid into an expansion zone provided by the body where the inlet comprises a passageway extending directly into a valve arrangement within the body for admitting heated working fluid into the expansion zone.

In still a further preferred aspect there is provided a manifold for an engine assembly wherein the manifold comprises a plurality of passages for directing heated working fluid into at least one expansion zone within the engine assembly, the manifold being adapted to insulate the heated working fluid so that the heated working fluid substantially maintains its temperature to the point of its admission into the expansion zone.

In another preferred aspect there is provided a valve having a valve body configured to be mounted in an engine assembly and a stem moveable within the body, the body comprising insulating material to minimise heat loss from working fluid passing there within.

In another aspect of embodiments described herein there is provided a heat exchanger comprising a combustion chamber and a combustion arrangement wherein the combustion arrangement is adapted to direct hot combustion gases formed adjacent outer walls of the chamber inwardly toward a heat exchange region. The combustion arrangement may comprise a boiler tube configuration within the chamber arranged so that upon combustion, combustion gases are directed inwardly over the boiler tube configuration forming the heat exchange region.

In a further preferred aspect there is provided a heat exchanger comprising a generally radially configured chamber and a combustion arrangement comprising an inlet gas collection zone and an outlet gas collection zone spaced radially inwardly from the inlet gas collection zone wherein the arrangement is adapted to provide combustion between the respective gas collection zones.

In yet another preferred aspect there is provided a heat exchanger comprising a combustion zone operatively associated with the periphery of the heat exchanger and adapted to cause combustion gases to flow inwardly from the periphery. In still another preferred aspect there is provided a heat exchanger comprising a generally radially configured chamber and at least one wound tube adapted for transporting a working fluid in a generally radially outwardly directed path through a heat exchange region. In another preferred aspect there is provided a method of using a heat exchanger having a combustion chamber comprising at least one or a combination of the following steps: igniting a fuel adjacent at least one peripheral wall of the combustion chamber; directing combustion gases inwardly towards an exhaust zone and over a heat exchange region intermediate the peripheral wail and the exhaust zone; providing a generally radially outwardly directed flow path for a working fluid from adjacent the exhaust zone of the combustion gases towards the peripheral wall of the combustion chamber; exchanging heat between the combustion gases and the working fluid within the heat exchange region.

In preferred aspects the heat exchanger may be adapted for one or more of a: boiler for an external combustion engine; a residential water service; an industrial water service; a commercial water service,

In another preferred aspect still there is provided a boiler tube arrangement for an external combustion engine comprising at least one wound tube forming a radially inwardly directed path for combustion gases.

In yet another preferred aspect there is provided a fuel inlet system comprising a plurality of inlets for the admission of fuel into a combustion zone wherein the inlets are arranged around the periphery of the combustion zone.

In another aspect of embodiments described herein there is provided an air delivery arrangement for an external combustion engine comprising a blower element; a coupling configured to connect the blower element and an engine as well as the blower element and an independent drive source. Preferably, the blower element forms part of a boiler for supplying a heated working fluid to the engine.

In another preferred aspect there is provided an air delivery system for an engine comprising a first energy source adapted to drive a blower; a second energy source adapted to drive.the blower; and an air delivery means for directing external air directly to a combustion zone; wherein the first and second energy means are operatively connected to the blower such that the blower is engaged by the energy source with the greatest operational speed.

In yet another preferred aspect there is provided a mechanical arrangement comprising: a blower for a boiler; a first hub element for being mounted to an engine operatively associated with the boiler; a second hub element for being mounted to an independent drive source; and a coupling for connecting the first and second hub elements and the blower wherein one of first and second hub elements is free wheeling such that either the engine or the independent drive source is able to drive the blower via the coupling.

In another preferred aspect there is provided an air delivery arrangement for an external combustion engine comprising a blower element arranged to receive air via the ram effect; a coupling configured to connect the blower element and an engine as well as the blower element and an independent drive source.

In another aspect of embodiments described herein there is provided an external combustion engine comprising; a boiler and at least one fuel/air inlet wherein the at least one fuel/air inlet comprises at least one fuel injector for injecting atomized fuel by pumping under high pressure into a combustion zone of the boiler; the fuel injector being coupled to control logic for controlling the fuel in accordance with predetermined air and fuel criteria.

In still another aspect of embodiments described herein there is provided an acoustic outlet for an external combustion engine comprising a steam bypass arrangement where the bypass arrangement directs steam from at least one engine cylinder to atmosphere.

Another preferred aspect comprises an acoustic outlet wherein the bypass comprises a three way valve operatively connected to one or a combination of engine cylinder, condenser and atmosphere. A further preferred aspect comprises an acoustic outlet configured for direct coupling to an external combustion engine for producing an exhaust sound from heated working fluid.

Another preferred aspect comprises an external combustion engine wherein a sound outlet is directly coupled to the engine for the generation of a sound from heated working fluid issuing therefrom.

Yet another preferred aspect comprises an external combustion system having an engine and a radiator wherein a sound outlet comprising a multi-way way valve is coupled to both the engine and the radiator. A further preferred aspect provides an engine comprising a body having a plurality of exhaust chambers and an outlet operatively associated therewith to produce a low frequency sound from at least one or a combination of the chambers,

In another aspect of embodiments described herein there is provided a method of controlling the operation of an externa! combustion engine, the engine comprising a plurality of combustion zones, the method comprising delivering fuel into at least one of the zones for ignition; igniting the fuel; and thereafter delivering fuel into one or a combination of the remaining zones for ignition.

A further preferred aspect provides a method of controlling a steam engine, comprising the steps of: monitoring the speed of the engine; monitoring the pressure and temperature of the steam issued by the boiler; monitoring the pressure of the steam entering the expansion chambers in the engine; determining a value indicative of the mass flow rate of steam consumed by the engine on the basis of at least one of said monitoring steps; and using the value determined to control one' or a combination of: (i) water delivered into the boiler of the steam engine and (ii) the amount of fuel ignited in the boiler. In yet a further aspect of embodiments described herein there is provided a valve control mechanism for an engine comprising a pivot element and a rocker operably connected to the pivot element, wherein the pivot element is movable between a first position and a second position to provide the valve control mechanism with at least two modes of operation for the engine.

In another preferred aspect there is provided an engine having a vaive control mechanism comprising a rocker having a pivot region wherein the pivot region is movable between a first position and a second position to provide the valve control mechanism with a first valve timing when the engine is operating and a second valve timing when the engine has stopped.

Yet another preferred aspect provides an engine having a valve control mechanism comprising a rocker having a pivot region wherein the pivot region is movable between a first position and a second position to provide the valve control mechanism with a first valve timing for when the engine is operating and a second valve timing for starting engine.

A further preferred aspect provides an external combustion engine comprising a body having a plurality of expansion zones each comprising a piston comprising insulating material for preventing the loss of heat from the expansion zone through the piston into the remainder of the engine.

Preferred aspects and embodiments described herein contemplate use of apparatus adapted to operate an external combustion engine, said apparatus comprising: processor means adapted to operate in accordance with a predetermined instruction set, said apparatus, in conjunction with said instruction set, being adapted to perform at least one or more of the method steps as described herein.

Further preferred aspects and embodiments described herein contemplate use of a computer program product comprising: a computer usable medium having computer readable program code and computer readable system code embodied on said medium for operating an external combustion engine within a data processing system, said computer program product comprising: computer readable code within said computer usable medium for performing at least one or more of the method steps as described herein. Other aspects and preferred aspects are disclosed in the specification and/or defined in the appended claims, forming a part of the description of . embodiments of the invention.

In the context of the present application the term "fluid" is meant to apply to any material that displays or possesses either liquid-like or gas-like behaviour or physical properties, which may make the material suitable for use as a working

'fluid' in an external combustion engine and, where the fluid may be in a gaseous state, ie compressible or in a liquid state. For example, a common candidate for such fluids is water; however, other more exotic fluids may be considered, for instance, fluids such as mercury/mercury vapour.

In essence, many embodiments of the present invention stem from the realization that rather than following the path of hitherto energy inefficient designs it may be possible to make use of existing engine space and components in conventional car designs be they ICE or ECE to provide a high performance external combustion engine as a power plant for available car designs.

Advantages provided by the embodiments disclosed herein comprise the following:

• By way of isolating an incoming working fluid from an engine head, heat loss to the engine is minimised. Further, such isolation means that there is no need for insulating the engine cylinder heads or cylinders per se and/or heating the cylinders/heads with a jacket. Additionally, the engine assembly itself when used and/or functioning as part of the condenser allows the condenser per se to be more compact saving space whilst being able to convert a greater percentage of steam to water for its recovery. This leads to better fuel economy, greater re-use of water, and a more compact power plant that is less costly to manufacture;

• With the boiler structure and design of embodiments disclosed herein, it follows that for a given boiler volume a relatively large burner plate area is provided resulting in lower flow velocities of air/fuel mixture through the burner plate. Accordingly, as the amount of air/fuel flowing is governed by the power required, the larger the burner plate the more holes there are for the air/fuel to ffow through;

• Air delivery systems in accordance with embodiments disclosed herein provide large volumes of air to the boiier nominally at relatively low pressures, which are delivered by a small and compact air delivery system. Accordingly, less energy is expended in the process of aspirating the boiler for its combustion purposes, the system is lighter in weight, cheaper and occupies less volume;

• A fuel injection system as disclosed by embodiments herein for external combustion engines provides air/fuel ratios that may be altered 'on the fly' to suit various operating conditions and incorporates cheap, reliable and compact hardware;

• An exhaust outlet providing an acoustic or sound effect as disclosed by embodiments herein for an external combustion engine vehicle, allows a driver, at their discretion and whilst operating the vehicle to attain a classic low frequency 'chuff', 'chuff sound commonly associated with steam powered vehicles but without the losses that usually result;

• A boiler control system as disclosed by embodiments herein results in smaller fluctuations in boiler steam pressure and temperature and thus allows for higher nominal ratings for the system operating values. By way of explanation, in any steam engine there may be a ceiling on the pressure and temperature of the steam that can be used, for example, material and lubrication limitations. That said, the higher the pressure and temperature of the steam used, the more power the engine can deliver and the higher the thermal efficiency of the system. For instance, if an engine control system can maintain the output steam to +/- 100° C then the nominal or set point of the system will need to be 100° C less than the ceiling set by the designer. If a control system is better and can say hold the boiler output to +/- 20° C, then the nominal set point could be 80° C higher than that previously identified, or, 20° C less than the ceiling value. The less variation that is built into the system the closer the engine can "sail to the wind" in its operation. Accordingly, embodiments described herein comprise design values rated at about 70 bar and about 500° C; • A smaller boiler may be used in an EC engine. The use of a

'normaliser' may be obviated with resulting savings in cost, weight, packaging of the engine components of a vehicle, and reliability.

• Boiler tubing layout may be optimised for thermal efficiency without a need to be concerned about response time. • A valve control system as disclosed by embodiments herein provides a simple design with low moving mass, which allows the engine to rev relatively high. Good breathing is allowed up to maximum engine revs. High thermal efficiency is provided in a compact design. A self starting engine is provided by way of the optimised valve timing of preferred embodiments described herein;

• An engine comprising embodiments described herein is unusual in that it is self starting yet can rev very high. Preferred designs are capable of at least about 5,000 rpm.

• A steam engine's pistons each present a large cold surface area to the incoming hot steam. By insulating piston components there is a reduction in the heat lost to the piston, which provides a corresponding increase in efficiency of the engine. However, there is also a requirement for efficiency to minimise any weight added to engine parts since this may be all moving or reciprocating mass. A notable feature of engines of embodiments herein is the ability to rev at high values. Given that more moving mass reduces this, the piston designs of preferred embodiments herein obviate the need for increased moving mass when attempting to insulate piston components and the insulation provided maintains the advantageous feature of a high revving engine.

Further scope of applicability of embodiments of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure herein will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

Further disclosure, objects, advantages and aspects of preferred and other embodiments of the present application may be better understood by those skilled in the relevant art by reference to the following description of embodiments taken in conjunction with the accompanying drawings, which are given by way of illustration only, and thus are not limitative of the disclosure herein, and in which:

Figure 1 is a perspective view of an assembled external combustion engine in accordance with a preferred embodiment;

Figure 2 is a perspective and inverted view taken in the direction of arrow A in figure 1 of the head of the engine of figure 1 showing the structure of the head from a front side of the engine in accordance with a preferred embodiment;

Figure 3 is a zoom view of figure 2 showing a working fluid inlet to a cylinder in accordance with a preferred embodiment;

Figure 3a is a zoom and rear side view of figure 2 showing exhaust working fluid outlets from the cylinders of the engine in accordance with a preferred embodiment;

Figure 4 is a perspective and inverted view taken in the direction of arrow A in figure 1 of the head of the engine of figure 1 showing a headplate from a front side of the engine in accordance with a preferred embodiment; Figure 5 is a perspective view of an assembled boiler in accordance with a preferred embodiment (showing one air manifold removed for clarity of description);

Figure 6 is a central longitudinal cross sectional view of the boiler assembly of figure 5 in accordance with a preferred embodiment; Figure 7 is transverse cross sectional view of the boiler assembly of figure

5 in accordance with a preferred embodiment;

Figure 8a is a perspective partial view of an example of an inner portion of a boiler tubing bundle with conductive fins suitable for use in the boiler of figure 5; Figure 8b is an end view of an example of a complete boiler tubing bundle with conductive fins shown in place for the inner three coils of the tubing bundle and which is suitable for use in the boiler of figure 5;

Figure 8c is a perspective view of the example boiler tubing bundle of figure 8a (showing some fins removed for clarity of description) and suitable for use in the boiler of figure 5;

Figure 8d is another perspective partial view of an example boiler tubing bundle (showing some fins and one coil removed for clarity of description) illustrating a grading in tube diameter and which is suitable for use in the boiler of figure 5;

Figure 9 is a perspective view of a boiler fuel/air inlet including an example butterfly valve inlet and which is suitable. for use within the boiler of figure 5;

Figure 10a and 10b shows graphical representations of exemplary operating temperature profiles of the boiler of figure 5; Figure. 11 is a schematic diagram of an exemplary external combustion engine in accordance with preferred embodiments;

Figures 12a to 12c show a cross sectional view of an external combustion engine in accordance with a preferred embodiment illustrating three operational conditions in which a variable valve timing mechanism of a preferred embodiment is utilised;

Figures 13a to 13c show a schematic illustration of a variable valve timing scheme suitable for normal and self starting operating conditions of an external combustion engine in accordance with a preferred embodiment. DETAILED DESCRIPTION The inventor has identified a number of drawbacks of which one or more may be common to external combustion engines. For example, in the context of a steam engine, incoming steam to an engine may be considered to be always at a higher temperature than the head of the engine. This may result in the transfer of heat from the steam to the head resulting in a loss of energy that would otherwise be transferred to the engine's pistons from the working fluid. In related art systems a solution for this has been to insulate the cylinder heads and cylinders of the engine to reduce heat loss to the atmosphere. Some engines have also heated the cylinders with a jacket, which may be filled with steam bled from the boiler. Another drawback comprises engines that attempt to be fully condensing. With a fully condensing compact power plant, transient power requirements, for example when accelerating from a stand still, produce rapid increases in demand for steam, which needs to be condensed upon its use. To handle the surge in steam either a large volume condenser is required in the available space of the vehicle or some of the steam may need to be vented to atmosphere. This in turn makes the power plant partially condensing not fully condensing.

In terms of the radiator, which provides the condensing function, when there is a demand for more power there is a demand for more steam and this may be the cause of increased exhaust steam from the engine. Accordingly, the pressure in the radiator may rise if it cannot condense all the steam arriving at that point in the system, which may require that the excess steam be vented out of the power plant system to atmosphere. The system accordingly loses water which causes a concomitant loss in km range of the power plant.

Figure 1 shows in perspective view an assembled external combustion engine generally indicated at 10 in accordance with preferred embodiments described herein. Major components of the engine shown in figure 1 are an engine head 4, engine block 6, crankshaft 22, boiler 9 with fuei injectors 26 and, air supply system comprising fan belt 19, pulley 21, clutches 23, small motor 17 and fan 27. An overall schematic of the preferred engine assembly and power plant system is shown in Figure 11 and displays the following components discussed herein in relation to preferred aspects of the present invention; boiler 9 comprising heat exchange assembly in the form of tubing 12, flame front (of the boiler) 13, fuei injector(s) 26, butterfly louvre(s) 24, fan 27, temperature sensor 29, first pressure sensor 31 , accelerator 32, second pressure sensor 33, expander 34a comprising cylinders 8 and an associated expansion zone 34, rpm sensor 36, radiator/condenser 38, check valve 37, feed pump 39 and solenoid bypass valve 41. In a first preferred aspect and with reference to figures 2, 3, 3a & 4, there is generally provided a Rankine cycle power plant generally indicated by 10 in the form of a steam engine. Ordinarily such power plants have the working fluid in its superheated form entering an engine at a higher temperature than that of the engine itself resulting in energy losses from the working fluid. Additionally power plants 10 also need to contend with transient power demands that leave excess demands on a condenser or radiator 38, The inventor proposes to tackle problems associated with such power plants in a completely different way to power plant designs that hitherto were energy inefficient. Firstly, in one embodiment the incoming hot steam in the example of a steam engine is isolated from the engine 10 and in particular the head 4 until it reaches the inlet valve 1 as shown best in figure 3 and figures 12a-c. Heat loss associated with incoming or supply steam through the structure of the engine 10 itself is minimised by use of relatively poor thermal conducting material or, more particularly a material of relatively low thermal absorption such as stainless steel for an inlet assembly 50 comprising the valve body 50a, valve 1, inlet 2 and head plate 7. The preferably stainless steel head plate 7 prevents heat loss when the steam is first inputted to an expansion zone 34. It is important that this occur especially when the temperature of the steam is at its hottest. In practice there may be a clearance in the range of about 0mm to about 4mm between the head plate 7 and the piston at top dead centre. A temperature change from about 500° C to about 130° C may occur through the relevant engine cycles that draw steam or working fluid into and out of the cylinders. A clearance volume in the cylinders may be in a range of less than about 5% to about 0% and preferably about 2%. An important factor appears to be that the input into the engine comprising the upper head plate 7 of the cylinder 8 around which the valves 1 seal is adapted to insulate the incoming steam from the engine body 10.

Generally, there is provided an engine arrangement comprising: a body 10; and an inlet 2 for the admission of heated working fluid into an expansion zone 34 within the body 10; wherein the inlet 2 is adapted to insulate the heated working fluid from the body 10 so that the working fluid substantially maintains its temperature from the point of its admission to the expansion zone 34.

Since the engine 10 is now substantially isolated with respect to the incoming supply of steam it does not need to be insulated as was the case in many related art designs that for example blanketed the entire power plant with lagging to keep temperatures of the engine body high in order to attain operating temperatures. In fact, the inventor has realised counter intuitively that the engine itself may now be used as part of the condensing system to draw heat from the exhausted steam of the expansion zone by ducting the exiting or exhaust steam through its structural surrounds. This adds substantial thermal mass and surface area to any pre-existing radiator 38 or condensing system 38. In turn this enables the pre-existing condenser 38 itself to be smaller and/or be able to convert a greater percentage of steam to water with the help of the engine structure as an additional heat exchanger. Advantageously better fuel economy, greater reuse of water, a more compact power plant that is cheaper to build results from this preferred aspect. Figure 2, 3 and 3a shows the head exhaust passages 3 of the engine assembly's structure, which are defined by honeycomb structures 3a at least around the engine head 4 as shown in figures 2, 3, and 3a to provide thermal contact for the exhaust steam with the engine head 4 and most importantly provide an increased surface area for contact of the hot exhaust gases in order to provide optimised heat exchange between these hot gases and the relatively cool engine body 10. The honeycomb structures 3a may also be provided by fins or their structural equivalents as well as equivalent structures to fins. The intention is to use the engine assembly structure, namely, one or a combination of the whole engine, block, head, rocker cover, sump, cylinder head, possibly even the gear box etc as a heat exchanger to draw heat from the steam after its expansion in the engine. Each of these engine assembly parts has useful surface area to exchange energy or heat with the surrounding fluid. The whole engine also may act as a large thermal mass. This in turn should assist cooling large surges in exhaust such as those instigated by rapid accelerations of a vehicle. Further, if the engine structure can be heated to above 100° C then water that has leaked past the piston rings into the sump may be boiled off. Thus it is beneficial to keep the engine above 100° C because this prevents water build up in the sump. Any energy extracted from the exhaust steam is energy that doesn't need to be 'dumped' to the condenser 38. This serves to assist the radiator/condenser 38 which in comparison may have a low thermal mass and generally a narrow operating range with respect to heat exchange for engines. Hence there is a better chance of having a fully condensing engine with minimal or no water loss. Although it may not be necessary to actually condense, simply cooling of the steam in the engine would be advantageous within the overall power plant. Example cooling may be say from about 120° C to about 105° C. However, any condensation of steam this provides would be a bonus for the engine's operating efficiency. Advantageously, by maintaining the condenser pressure at about 1.2 bar the condensing temperature of the exhaust steam may be about 105 deg C. If the engine is at about 103 deg C relatively large amounts of energy associated with the phase change of the steam into water can be exchanged with the engine. This is energy that does not need to be exchanged in the condenser. Since the engine is running at about 103 deg C and the sump pressure is atmospheric, ie 1 bar, the boiling point of water is 100 deg C. Hence any water in the sump will be slowly boiled off. This is highly desirable as the water may otherwise degrade the engine oil over time. A preferred system runs the exhaust steam through the head 4 then out of the engine via exhaust pipes 3. One such exhaust pipe 3 may run down the side of the engine 10 and then thread through the sump to dump more energy into the engine oil. It is furthermore desirable to insulate the expansion zone 34 which comprises the engine's cylinders 8, from the engine block 6 as best as possible. Cavity structures formed around each cylinder 8 for containing isolating voids may assist in this and these may contain air for this purpose. Other fluids could also be used for this purpose, as would be recognised by the person skilled in the art. Insulated cylinder sleeves would also be useful in achieving this. Thermally isolating the piston is also desirable and in one preferred embodiment an insulating coating may be applied to the contact surface of the piston, for example, a ceramic coating.

In a preferred embodiment there is also provided an engine arrangement comprising: a body 10; and an inlet 2 for the admission of heated working fluid into an expansion zone 34 within the body 10; wherein the inlet 2 is adapted to insulate the heated fluid from the body 10 to the extent that the temperature drop through the inlet 2 into the expansion zone 34 is lessened. With reference to figures 12a-c, in operation, the temperature drop of steam through the inlet manifold 42 into a chamber 55 surrounding or behind a poppet valve 1 may be in a range from about 1 deg C to about 30 deg C and preferably less than about 10 deg C when running at full power. The inlet manifold 42 (shown partly in cross section in figure 12) comprises a plurality of passages for directing heated working fluid into at least one expansion zone within the engine assembly, the manifold 42 also being adapted to insulate the heated working fluid so that the heated working fluid substantially maintains its temperature from the point of its admission to the expansion zone. In accordance with the principles identified by the inventor, the manifold 42 may comprise tubular stainless steel material and the engine assembly may comprise material substantially consisting of iron, for example, (cast) iron material and/or aluminium, and/or aluminium alloy, and/or steel, and/or stainless steel. Figure 4 shows the head 4 ready to bolt onto the block 6. A stainless steel head plate 7, shown in figure 4, prevents exposure of the exhaust cavities in the head. The head plate functions to seal the engine cylinders 8 (not shown but their position is indicated in figures 11 and 12) at the head 4. It will need gaskets here just like an IC engine. Actually two gaskets may be required on the head 4. One between the stainless head plate 7 and the block 6 which may be a standard head gasket. Another simpler gasket may be required between the stainless head plate 7 and the "honey combed" aluminium head structures 3a to seal in the exhaust steam for heat exchange.

In related art systems there is a snowball effect with regard to the heating as exhaust working fluid, namely steam, comes out of the engine it absorbs heat from the engine which we try to maintain as hot as possible to make the expansion cycle as efficient as possible. Given that the exhaust steam absorbs heat this precipitates the requirement for more steam and so on. The system of preferred embodiments here is different in the input output cycle as described in order to make use of the natural tendencies that would be seen as adverse in related art systems.

A further drawback relates to boiier design. The inventor has recognised that the design of the boiler, comprising the combustion zone thereof, should be as compact as possible. However, in the particular application of automotive power plants, the boiler output may be considered as a limit on the total plant power. In related art designs, so called compact boilers may have a large open space in which the air/fuel mixture is fed into and burns. This combustion space takes up a lot of valuable engine bay room. Once the combustion is completed the resultant hot gases pass through a heat exchanger containing water and eventually steam. Some boilers have used a more compact arrangement of a burner plate containing a plurality of fine holes. In this arrangement, the air/fuel mixture passes from one side and through the plate containing fine holes and is ignited on the other side. This provides a plurality of small flames, which occupy a reduced volume in comparison to the before mentioned large combustion space. With regard to the burner plate arrangement, the inventor has recognised that there is a need to have enough burner plate area to maintain a sufficiently low flow velocity of the air/fuel mixture passing therethrough and within acceptable limits. This will ordinarily provide a combustion flame that is small in its extent from the burner plate and allow for compact design by way of having the working fluid tubing arrangement closer and more snugly fitting in proximity to the burner plate.

With reference to figures 5 to 10 preferred embodiments enable a significant increase in the power output of a boiler generally indicated at 9 for a given volume. This has been achieved by wrapping a burner plate 11 to form it into a cylindrical tube housing and placing it around a heat exchanger assembly 12 that forms a heat exchange region by use of a tubing arrangement. The air fuel mixture is ducted around the outside of the burner plate within the enclosed boiler assembly 9 within a cavity space or air manifold 14 shown in figures 5 and 7. Preferably, each air manifold 14 is constructed with a series of apertures or perforations as shown in figure 5 such that the air manifold is adapted to evenly distribute air/fuel mixture to the combustion chamber by providing a transverse flow of air/fuel with respect to the burner or burner plate 11 of the heat exchanger. It then flows radially inwards throughout the extent of the plate 11 and is ignited forming a flame front 13 of limited extent as shown in figure 7, The hot combustion gases then continue to flow inwardly through the heat exchanger 12 and out the core 16. The sectors of the burner plate may be lit in sequence, for example, by way of a spark plug 43 or multiple spark plugs (not shown) positioned as required and that may be located on the inner side of the burner plate 11 which provides a large surface area.

The advantageous features of this burner layout is that for a given boiler volume it has a very large burner plate area with resulting low flow velocities therethrough. The layout also makes good use of the space available, which in most if not all engine designs will involve engine bay space generally of a rectangular form. More generally, a fuel inlet system of the boiler may be adapted for a combustion zone defined by the engine bay comprising a rectilinear periphery and the inlets may be each located adjacent an apex of the periphery of the combustion zone. The boiler cross-section shown in figure 7 highlights that the combustion doesn't take place until the air/fuel mixture has passed through the perforated plate 11.

Some indicative measurements of the temperature profile of the operational boiler are shown graphically in figures 10a and 10b. Figure 10a presents a temperature profile of combustion gas and steam temperature with respective scales on each opposing side of the diagram as a function of the coil number within the heat exchange assembly 12 which is comprised of a number of wound coils. The coils in turn comprise tubular or pipe paths for the working fluid with heat exchange fins 28, as shown best in cross section by figure β, attached externally thereto. Figure 10b also provides an indication of the temperature profile of the boiler with curves representing both the combustion gas and working fluid temperatures respectively but shows only a single temperature scale on the left hand side. Table 1 shows data points that relate to figures 10a and 10b with temperature given in degrees Celsius.

Coil No. Gas Temp. Fluid Temp

1 1666 515

2 1068 286

3 531 228

4 317 138

TABLE 1

The 'radially inward firing' of the boiler design is a particularly advantageous feature. The combustion gases travel into the centre of the boiler 9 in a radial fashion. While traveling through the heat exchanger tubes 12 the combustion gases temperature drops as it transfers energy to the tubes 12 carrying working fluid in the opposite radial direction to be superheated. With dropping temperature the combustion gases density increases and it occupies less volume. This matches the decreasing volume available for the combustion gases to travel through as they approach the centre 16 of the boiler. So there is a complimentary relationship between the direction of travel of combustion gases, their dropping temperature and volume to move through as they progress. This compact interworking relationship between the travel path, temperature drop and volume provides a very compact layout that is desirable for a vehicle's operating efficiency.

With respect to the flow direction of the working fluid within the boiler the following may be said. When forming the tubing 12 into coils there is a limit on how tight the coil material can be bent during manufacture and fabrication of the assembly 12. A preferable ratio defining the exemplary structure comprises an inside bend radius in the range of about 5 to about 2 times the tuber diameter and preferably about 3.5 times the tube diameter. It follows that the smaller the tube diameter the tighter it can be coiled. Moreover, when a working fluid such as water flows through a tube there is a corresponding drop in pressure due to friction. This is related to velocity, or more precisely, the square of the velocity. When the water starts to boil its density decreases as its volume increases. Once it turns completely to steam its density continues to decrease and volume increases further. If the frictional losses are to be kept to manageable levels the tube diameter needs to increase with decreasing water/steam density. This is accommodated by a grading in the tube diameter such that the diameter of the tubing comprises occasional increases along its path length. An example tube diameter grading is shown in figure 8d for instance at point 12d. With the proposed boiler layout the above two points tie in nicely such that when the water is at its most dense the tubing 12 is at its smaller diameter. Otherwise the flow velocity of the working fluid may increase causing greater pressure loss by virtue of increased friction between the working fluid and the walls of the tubing. As the working fluid picks up heat on its radially outward journey in the preferred design and its density drops the coils are required and are able to get bigger in diameter so larger tube diameters can be used at these outer portions of the working fluid's path length. Correspondingly, this reduces the fabrication limitations that are inherent causing the tubing manufacture to be a much easier- task.

With respect to the coil wrap direction and with reference to figures 8a to 8d, in order to aid manufacture and compactness the following coil layout has been implemented. The first inner coil is made of the smallest tubing, eg about 12.7 mm diameter. At the end of the coil it changes diameter, both coil and tube (about 15.9 mrn diameter). It then wraps back over itself. At the end of the 2nd coil run it changes coil diameter and reverses direction again and wraps back again. At the end of this coil run, the 3rd coil, it changes coil and tube diameter for the last time, eg about 19 mm diameter. So there are 4 coil runs or 4 coils, one inside the other. If the assembly was unwrapped it would consist of one continuous tube of step variable diameter.

It is envisaged that the design involved with the above burner, burner plate and coil tubing for working fluid may be utilized in many more applications than that of an ECE. For example, the inventor has realised that the embodiments described here may also apply generally to heat exchangers of industrial, commercial or residential use such as hot water services or water heaters.

Yet another drawback relates to air delivery to the engine for aspirating the boiler. Related art boilers may use a blower of some description to deliver air to the burner and these blowers may draw a large amount of power whether this is electric or hydraulic. The power required for these blowers may be up to about

700W or more. By necessity, these motors may be large, expensive and heavy.

Jn accordance with preferred embodiments, an air delivery system for a boiler is provided which comprises a first energy source adapted to drive a blower; a second energy source adapted to drive the blower; and an air delivery means for directing external air directly to a combustion zone; wherein the first and second energy means are όperatively connected to the blower such that the blower is engaged by the energy source with the greatest operational speed.

Preferably, the air delivery system comprises a clutch arrangement to facilitate engagement of the first or second energy source, wherein the clutch arrangement comprises at least one free wheeling hub. Also, the air delivery means is preferably adapted to deliver air by a ram effect.

With reference to figure 1 , in a preferred embodiment air delivery difficulties with ECE may be overcome by advantageously utilising three energy sources in an intelligent fashion for moving air into a boiler. A first independent energy source to be used comprises a small, say 150 W motor 17, to drive a conventional blower fan 18. This fe used when the engine is stationary and the vehicle is not moving. The motor 17 drives the fan via a belt 19, which also picks up a pulley on the engine crankshaft 22. An idler pulley 21 is also shown in figure 1. The motor 17 and the engine 10 both have integral freewheeling or sprag clutches 23. This enables the engine 10 to drive the fan 18 once its rpm is high enough. Thus the engine 10 can provide the higher power levels required. When the engine 10 takes over driving the fan 18, the motor 17 is freewheeling and. can be powered down. To further boost the pressure head delivered by the fan 18, the ram effect of the vehicle can be used. Air is ducted to the fan 18 inlet from the front of the vehicle. The amount of air delivered by a combination of engine driven fan and ram effect is designed so that it is more than is needed. To manage this, a number of butterfly valves 24 best shown in figures 5 and 9, which are controlled by the engine management computer (not shown), throttle the air delivered to the burner 9. Large volumes of air at high pressure can be delivered by a small compact air delivery system using less energy, is light, cheap and small, Still another drawback relates to the engine's requirement to provide a required air/fuel mixture under varying operating conditions. The varying conditions may comprise start up, high and low air/fuel flow rates, changing temperature conditions internally and/or externally, emergency shut downs and fast transitions in air/fuel flow rate. By way of explanation, the air/fuel flow rate corresponds to the amount of energy being released in the boiler. This in turn boils water and turns it into steam. This is then transformed into shaft horse power by the engine. So if more power is needed, for example when towing a caravan up a hill, more air/fuel may be required to be fed into the boiler. By corollary, when driving down a long step hill, the driver might take their foot completely of the accelerator such that there is no need for any power in that moment, and accordingly the air/fuel, flow rate may drop to zero. Hence, air/fuel flow rate is not necessarily linked to vehicle speed, but rather engine power output requirement.

Related art burners may use a number of technologies to address these requirements for air/fuel delivery, such as the following examples. Firstly, there has been use of a 'pressurised vaporising burner', which comprises pressurised fuel being vaporised in a pipe and then injected into the burner. Secondly, a 'carburettor style burner' may be used, which comprises air flowing through a carburettor where it draws in fuel. Thirdly, a 'spinning cup burner' is used in which fuel is pumped into a spinning cup or funnel, . The centrifugal force breaks up the fuel and sprays it into the combustion space. In each of these solutions there may be difficulty in achieving different air/fuel ratios in various operating circumstances or power requirements of the engine.

With reference to figures 1 and 9 there is provided an electronic fuel injection system for an ECE, to the burner system. This means that the air/fuel ratio is now software controlled and by using appropriate sensors various scenarios can be handled. The air/fuel ratio can be altered "on the fly" to suit various conditions. Hardware that is cheap, reliable and compact can also be utilised. A number of fuels in fluid form may be used in the present embodiments comprising one of, petrol, LPG gas, diesei, ethanol, peanut oil and other suitable fuels as would be known to the person skilled in the art. Accordingly, an external combustion engine as described herein may comprise a boiler 9 and at least one inlet 44 as depicted generally in figure 1 , wherein the at least one inlet 44 comprises at least one fuel injector 26 for injecting atomized fuel by pumping under high pressure into at least one air manifold 14 preceding a combustion zone of the boiler 9; the fuel injector(s) 26 being coupled to control logic for controlling the fuel In accordance with predetermined air and fuel criteria. The preferred fuel injection system may comprise at least two and preferably four fuel injectors 26 wherein the fuel injectors 26 are arranged to inject fuel into one or a combination of injection zones around the boiler tube arrangement as described herein and shown in figures 1 and 9 where by virtue of a rectangular cross section the portion of the engine compartment (engine bay) that houses the boiler comprises four vertices each being used as an injection zone. Alternate embodiments may comprise an engine compartment of an unconventional shape, for example, hexagonal or octahedral where six or eight injection zones could be utilised.

In modern steam engines for vehicles a condenser may be utilised to recover some of the exhaust steam from the engine. The exhaust steam may be condensed and fed back into the boiler. While this has greatly extended the operating ranges of steam cars, it may mean that the vehicle is effectively silent. Accordingly, there may be no exhaust beat or sound, such as for instance the sound emitted by a steam train. Such sounds are considered highly desirable for the steam automotive enthusiast. To provide an aesthetically pleasing sound from the vehicle, some drivers of condensing steam cars may remove the condenser (radiator) cap when driving slowly for the fun and entertainment of both passengers of the vehicle and any 'pedestrian' audience nearby. By removing the radiator cap exhaust steam is allowed to escape from the vehicle accompanied by a familiar "chuff-chuffing" sound. However, due to the loss of water that accompanies the venting of steam the sound display may be only a short term option for the driver. Further, the driver may be required to stop and get out of the vehicle to remove and/or replace the radiator cap.

With reference to figures 2, 3, 3a and 11 an acoustic system is shown in which the exhaust from one or more cylinders 8 is isolated. The means for isolation may be facilitated by the honeycombing fins 3a described above. Normally, the fin structures meet flush with the head plate 7 but may be partitioned back to allow passage for exhaust in the acoustic arrangement. As illustrated in figure 2 it can be seen that exhaust outlets 3 may be configured to isolate one, two or three cylinder outlets where isolating one cylinder 8 gives a lower frequency sound than the isofation of two or more cylinders 8. Preferably there is placed a three-way valve between the outlet of the one or more cylinders 8 and at least a condenser 38. The driver, while driving, can operate this valve. The valve has two states, either feeding exhaust steam straight through to the condenser 38 or allowing it to discharge to the atmosphere. The second state creates the classic 'chuff chuff sound of a steam-powered vehicle. By using the exhaust from a sub-set of the total number of cylinders 8, a lower frequency sound can be obtained as noted above. This is more desirable. The frequencies emitted may be is less than about 1 Hz to about 10 Hz.

The driver, at their discretion, can obtain a classic low frequency chuff, chuff sound, even when on the move. In one embodiment, one exhaust pipe leading from the valve and carrying expanded steam may be threaded through the sump to heat the oil, as noted above. Another exhaust pipe from the valve may function as an acoustic port and the third exhaust pipe stemming from the valve goes to the radiator. With reference to examples like the Doble steam car, when using monotube (or "once through", "flash") boilers, control of output steam pressure and temperature may present one of the biggest challenges in building a successful automotive steam power plant. In an automotive application the power output required may vary widely and also quickiy. This means that the steam mass flow rate out of the boiler may also have to vary to match the varying power requirements. At the same time it is desirable that the steam temperature and pressure does not substantially change. If the pressure drops, power delivered by the engine may also decrease. If pressure rises to high it may need to be vented to protect the system. This scenario may result in lost energy and a corresponding drop in efficiency. If the temperature rises too high, damage may be done to the engine. Correspondingly, if the temperature drops too low, power and efficiency may also decrease. Related art steam engines have previously provided a number of solutions to address, or partially address, this problem. These solutions comprise one of: a) Increase the volume (and thus water and steam) contained by the boiler. This means it is less sensitive to sudden demand changes. Examples of this comprise fire tube and water tube boilers. The downside of doing this is that the boiler may require more energy to heat up, may be heavier, bigger and more dangerous and expensive. b) Use a secondary water injection system to cool the steam. This may be referred to as a "Normalizer". If the temperature of the steam is becoming excessive water is sprayed onto/into it. The downside of this is cost and complexity. It may also cause severe thermal shock to surrounding metal surfaces. c) The majority of monotube automotive power plants may monitor the boiler steam output temperature and pressure in a control system. Changes in temperature may be used to manage the volume of feedwater delivered into the boiler. Pressure may be used to manage fuel burnt. Some control systems may interlink temperature and pressure when managing feedwater and fuel burnt. The inventor has identified that none of these have been completely successful. With these control systems, power output may still fluctuate wildly and driver intervention may sometimes be needed. d) One engine built by Scientific Energy Systems used a predictive system. Boiler feedwater and fuel was controlled by a combination of engine speed and valve timing (or cutoff setting). Boiler steam temperature and pressure were used as a feedback signal to trim any errors. Although a significant departure from previous methods, the inventor has again identified that this was not completely successful. In operation, wide fluctuations in pressure and temperature were experienced.

With reference to figure 11 there is shown a systemic view of a power plant utilising external combustion. In accordance with preferred embodiments, the above problems may be overcome by using a mass flow rate predictive system with temperature and pressure feedback for trim. The predictive system described here differs from d) above in that the steam mass flow rate consumed by the engine at any instant may be estimated. This is achieved by utilising predetermined mathematical expressions along with inputs comprising the engine rpm, valve timing, engine steam manifold pressure, differentia! air pressure in burner/burner duct(s) and temperature (steam pressure and temperature entering the engine). This estimate of instantaneous steam consumed is used to manage the amount of feedwater fed into the boiler and corresponding fuel burnt. Any drift in actual pressure or temperature is used as feedback to trim. The preferred systematic boiler control method adopted by the inventor is as follows using the noted sensor parameters.

Sensor Variables

RPM = Engine RPM

Pm - Steam pressure in manifold, ie steam pressure entering the expansion zone or cylinder of the engine.

Tm = Temperature of steam in manifold

Tb = Temperature of steam exiting the boiler

Pb = Steam pressure exiting the boiler

Pa = Differential air pressure In burner duct Constants

Tset = Set point temperature of the boiler

Pset = Set point pressure of the boiler

* Water Management The intention here is to estimate how much water, or steam, the engine is consuming at any moment and pump a matching amount of water into the boiler to make up for this and preferably the temperature of the steam exiting the boiler is used as a feedback trim for this. To calculate the steam mass flow rate through the engine the first step is to calculate the density of the steam entering the engine. This can be done using a polynomial which maps steam properties over the engine's operating envelope. The polynomial will map the graph depicted in figure 11a for a number of steam pressures (Pm) and temperatures (Tm) upon entry into the expansion zone or steam pressures and temperatures within the inlet manifold, which will correspond to resultant densities (specific volumes) as shown. The indicative steam pressures shown are 100bar, 80bar, 60bar, 40bar, 20bar and 10bar.

Density = f(Pm, Tm,) To reduce cost the Tm sensor could be eliminated here and the value of Tb used instead. The introduced error is small Now the mass flow rate of water (or steam) through the engine can be calcuiated

Mf a f(RPM, Density, Volume) = RPM x Density x Cylinder volume at cutoff

So the water we want pumped into the boiler any given point in time is Mp s Mf - Kf x (Tset- Tb) where Kf x (Tset - Tb) is a feedback trim and Kf is the proportional gain. For simplification a simple proportional control has been used here. More sophisticated feedback systems could be used if needed as would be recognised by the person skilled in the art. The engine management system, or computer, would then use the value of

Mp to control the feed pump. Depending on the set-up of the pump this could be done in a number of ways. This may comprise varying the speed that the pump is driven at, say with a servo motor for example. In another embodiment it is envisaged there may also be a clutch which is under pulse width modulated . control, ie drive to the pump is turned on and off. Or the pump can be driven at a fixed ratio from the engine and a solenoid valve 41 used to by-pass excess water back to the condenser by means of Pulse Width Modulated control as shown in figure 11 and which also shows a one way check valve 37 providing working fluid to the boiler. Currently this is a preferred option for managing the pump.

The water flow rate delivered by the pump, M_fp, is given by:

M_fp= f(RPM, Pump displacement). When the by-pass valve is open M_fP is reduced by an amount equivalent to the volume of fluid flowing through valve 41 so by cycling the valve open and closed (Pulse width modulating) the average M_fP delivered over time can be made to equal M_p.

To ensure this is achieved the pump has been sized such that it will always provide more water than is needed under normal operating condition.

Essentially, the above algorithm manages the water

Energy or Heat In,

Along with water the engine management system may also control the heat or energy released in the boiler. Energy is obtained by the combustion of fuel and air. In preferred embodiments, it is facilitated by the use of electronic fuel injection.

The energy required to make up for the steam consumed by the engine is given by.

E iost = MfX KB + K_E (P_Set- Pb) Where KB is a constant representing the energy needed to turn a kg of water into steam. KE (P_Set - Pb) is a proportional controller or feedback trim and KE is the proportiona! gain.

The actual amount of energy needed varies slightly from this due to boiler efficiency. The efficiency is higher at lower power outputs and lower when running at higher power levels. E req = E LOST X f (ELOST)

Where f (E_Losτ) is an expression giving the boiler efficiency at a particular loading or output. To obtain this energy input, E _req . the engine management system or computer, will manage the air delivered to the burner/boiler. The target airflow rate is:

Air req = E req X f(A/F)X KD Where f(A/F) is an expression giving the air/fuel ratio at a particular loading or output. The air/fuel ratio is higher at low loads and lower at higher loads. KD is the energy contained in a kg of fuel.

The actual air flow rate flowing into the burner is Air act = f(temp,Pambι Pa)

Where Temp is the air temperature and Rami, is the atmospheric or ambient air pressure. At low power levels, say under 10% of maximum power, the blower motor can be utilized to provide combustion air.

P_BM = f (Air _req , Air_act) Where P_8M = electrical energy supplied to the blower motor.

When higher power levels are being produced, say above 10% of maximum power, the- engine speed is such that it will take over powering the blower. The blower motor can then be powered down At even higher power levels the ram effect of the vehicle moving forward advantageously may start to contribute to the total air delivered to the burner.

The blower, drive pulley diameters, manifolds etc are sized such that there may always be more air available, than is needed. Hence the louvers are utilized to manage or modulate the air flow rate. So the louvers are utilized to manage Air am. L angle - f(Air _rec, , Air _BOl)

The fuel add is related to the air actually being fed into the boiler.

F,«, = f(Air act) x «A/F)

F_reC! is equal to the energy or heat delivered

A further problem identified by the inventor in related art systems relates to a need for the design of a valve/head/cylinder arrangement which is simple, robust, thermally efficient and capable of 'breathing' efficiently up to engine speeds of about δOOOrpm or higher. By way of explanation, the term 'breathing' is used here in reference to the provision of a low pressure drop of the steam flowing through the manifold and inlet poppet valves at high speed. If the piping and valves "choke" the steam entering the engine then this will cap or restrict the power output of the engine at high speed. Similarly in IC engines designers try to reduce losses of incoming air in the inlet manifold and head. This is to improve "breathing" of the IC engine and corresponds to the inventor's adapted use of the term in relation to EC engines.

Most early steam engines operated on the "counterflow" principle. That is steam enters the cylinder via a valve in the head or top of the cylinder. Generally the valve needs a short port or passage to connect it to the cylinder. A valve in close proximity to an inlet valve controls exhaust timing. Quite often they share the same passage in the head connecting to the cylinder. This means cold exhaust steam may travel through the same passageway as hot inlet steam, although in the reverse or "counterflow" direction. This design is simple to make. However, its disadvantages may include poor thermal efficiency, high thermal head stresses and increased energy dumped to the condenser. Examples of power plants that used the counterflow system include the White, Doble and Stanley engines.

Another related art engine head solution is referred to as the two stroke "uniflow cycle" and most modern, high efficiency expanders work on the uniflow cycle, ie exhausting at the bottom 10% of piston travel and generating high compression on the piston return stroke. This may result in a very efficient mode of operation and may also simplify the engine by not requiring exhaust valves. However, the inventor has identified disadvantages of the uniflow cycle, namely, rough running at low speeds and/or low power levels and less power for a given expander displacement. There may also be difficulty in lubricating the cylinder walls and greater mechanical and thermal losses. Examples of power plants using this scheme are the Prichard, SES and GM SM-101 steam engines. They use a single inlet valve in the cylinder head and exhaust ports in the bottom of the cylinder wall.

Another related art engine head solution makes use of valves. A number of valve types have been used over the years, but when it comes to handling high pressure and temperature steam not many are considered suitable. Sliding valves such as 'D' or Corliss valves are not considered suitable to high pressure steam. Further, valves such as piston valves need large port volumes. Examples of power plants that make use of such valves are the White and Stanley steam engines. In a further related art use of valves, poppet valves have been used previously in steam engines. Disadvantages identified by the inventor for the use of poppet valves include complexity in changing cut off or valve timing and port and cylinder clearance volumes. The Prichard, SES and GM SM-101 steam engines all used poppet valves.

With further reference to the above noted SAE reports, in particular those on the SES and GM engines; there is described a decision process for deciding on the expander operating cycles. In choosing the uniflow cycle the SAE reports both quote heat loss and thermal stresses in the head as a factor. In the SES report a comparison of efficiency versus uniflow and counterflow cycles was conducted. Uniflow came out on top. One of the assumptions made to enable this comparison however, is a clearance volume of 5%.

The inventor has also identified that self starting engines have been available, such as for steam powered vehicles. However, they may tend to be stow revving big 'chunky' engines, such as the likes of the older Stanley and Doble engines. The early Stanley and Doble engines may be considered incapable of operating over about 1000 rpm and at that speed may tend to vibrate violently. The more modern high speed engines like the SES and GH engines were not self starting, as they had starter motors like IC engines. Reference may be made to figures 12 and 13. Due to the disadvantages listed above in the uniflow cycle, the inventor did. not want to implement such a cycle. Using a computer program to simulate the engine, various cycles and variables were explored. What was found was that if the clearance volume was made a variable rather than a constant, the counterflow cycle could in practical terms outperform the uniflow cycle. Preferred solutions noted herein stem from this realisation. So in a preferred engine a design requirement was set for a clearance of 1.5%. This then drove the layout of the engine, materials, valve and head geometry, etc.

The disadvantages listed above may be overcome by applying a number of different technologies together. These are as follows: a) Exhaust and Inlet poppet valves

By using an exhaust poppet valve, compression can be greatly reduced and power output increased. b) Inward opening perpendicular valves

If the valves are co-linear with the cylinder axis and are flush with the head on the piston side, very low cylinder clearance volumes can be achieved. As the clearance volume is reduced the theoretical adiabatic cycle efficiency approaches that of the uniflow cycle. c) Maximum valve lift

To maximise valve lift it is necessary to balance the steam force trying to open the valve 1 with the force required to keep the valve train in contact with the cam 48 at maximum rpm. The magnitude of this force is used to determine the size and type of the valve spring 51 used. This will give the largest valve lift possible and hence maximise breathing for a given layout. d) Minimise Heat Loss

On the head 4 side, for any surface touching inlet steam use of materials which are poor conductors of heat, ie stainless steels may be recommended. This includes manufacture of components such as the head plate 7, poppet valves 1 and valve sleeves. To minimise heat loss through the piston use of ceramic coating is recommended. This minimises the weight increase to the piston as discussed above. e) Change Valve timing For normal running the rocker 52 does not touch the base circle of the cam

48 lobe, ie there is a slight clearance. To change the valve timing, the pivot 46 for the rocker 52 can be lifted slightly, say in a range of about 1mm to about 3mm. A secondary cam profile 49 can then be engaged resulting in different valve timing being enacted. This can be used for giving a longer inlet valve opening to assist in starting for example. The secondary cam profile 49 depicted by shading within figures 12a-c represents material removed from the cam shaft to an extent comprising a range of about 0.3mm to about 1.5mm.

A preferred embodiment is described with reference to figures 12 and 13, which depict a variable valve timing mechanism. The first illustration in figure 12a is .of the head 4 of an external combustion engine in a normal running condition. The second illustration of figure 12b is with a pivot 46 raised forcing the valve 1 open. In the third illustration of figure 12c the pivot 46 is still raised but the cam 48 has rotated 180 deg. The relief in the cam lobe has allowed the valve 1 to shut. In this implementation the aim is the have a self starting engine. Thus raising the pivot 46 is intended only to be used when the engine rpm is low. Hence valve lift only has to be small. To lift the pivot 46 hydraulic pressure is used. The pivot 46 is mounted on a piston 53, which is located in a cylinder 54 formed in the head 4. A solenoid valve operated by the engine management system, or computer, allows water from the boiler inlet to enter this cylinder. It's pressure being similar to the boiler pressure. This will lift the piston 53 and pivot 46 a set distance of about 1.5 mm.

By way of further explanation, reference is made to figures 13a, 13b and 13c. Figure 13a depicts an end view of the crankshaft 22. Referring to figure 13b, in a normal running state, if the engine stops with a crank pin lying in the dashed zone then the engine cannot restart itself without a starter motor because no valve would be open to allow working fluid into the engine's cylinders 8. However, in figure 13c it is shown that at practically any crankshaft position a cylinder/piston on the right hand side of the diagram will receive steam. Thus the engine will be self starting and does not require a starter motor.

In essence this aspect of embodiments described above provides a valve control mechanism for an engine comprising a pivot element and a rocker operably connected to the pivot element, wherein the pivot element is movable between a first position and a second position to provide the valve control mechanism with at least two modes of operation for the engine. The valve control mechanism may comprise a valve having an open condition and a closed condition and movement of the pivot element increases the range of the open condition from a range of about 10 degrees to about 30 degrees before top dead centre to a range of about 30 degrees to about 145 degrees past top dead centre. Alternatively, the above embodiments provide an engine having a valve control mechanism comprising a rocker having a pivot region wherein the pivot region is movable between a first position and a second position to provide the valve control mechanism with a first valve timing when the engine is operating and a second valve timing when the engine has stopped. The embodiments described above also provide an engine having a valve control mechanism comprising a rocker having a pivot region wherein the pivot region is movable between a first position and a second position to provide the valve control mechanism with a first valve timing for when the engine is operating and a second valve timing for starting engine. The valve control mechanism preferably has an inlet valve and an exhaust valve, the first valve timing corresponds with the inlet valve, being open for a much smaller time compared to the exhaust valve, and the second valve timing corresponds with the inlet valve being open for a similar time as compared to the exhaust valve. The first valve timing corresponds with the inlet valve being open over about 40 degrees and the second valve timing corresponds with the inlet valve being open over about 175 degrees.

While this invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification(s). This application is intended to cover any variations uses or adaptations of the invention following in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth.

As the present invention may be embodied in several forms without departing from the spirit of the essential characteristics of the invention, it should be understood that the above described embodiments are not to limit the present invention unless otherwise specified, but rather should be construed broadly within the spirit and scope of the invention as defined in the appended claims. The described embodiments are to be considered in all respects as illustrative only and not restrictive.

Various modifications and equivalent arrangements are intended to be included within the spirit and scope of the invention and appended claims. Therefore, the specific embodiments are to be understood to be illustrative of the many ways in which the principles of the present invention may be practiced. In the following claims, means-plus-function clauses are intended to cover structures as performing the defined function and not only structural equivalents, but also equivalent structures. For example, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface to secure wooden parts together, in the environment of fastening wooden parts, a nail and a screw are equivalent structures. Various embodiments of the invention for example in relation to electronic fuel injection may be embodied in many different forms, including computer program logic for use with a processor (e.g., a microprocessor, microcontroller, digital signal processor, or general purpose computer), programmable logic for use with a programmable logic device (e.g., a Field Programmable Gate Array (FPGA) or other PLD), discrete components, integrated circuitry (e.g., an Application Specific Integrated Circuit (ASIC)), or any other means including any combination thereof. Computer program logic implementing all or part of the functionality where described herein may be embodied in various forms, including a source code form, a computer executable form, and various intermediate forms (e.g., forms generated by an assembler, compiler, linker, or locator). Source code may include a series of computer program instructions implemented in any of various programming languages (e.g., an object code, an assembly language, or a high-level language such as Fortran, C, C++, JAVA, or HTML) for use with various operating systems or operating environments. The source code may define and use various data structures and communication messages. The source code may be in a computer executable form (e.g., via an interpreter), or the source code may be converted (e.g., via a translator, assembler, or compiler) into a computer executable form. The computer program may be fixed in any form (e.g., source code form, computer executable form, or an intermediate form) either permanently or transitorily in a tangible storage medium, such as a semiconductor memory device (e.g. a RAM, ROM, PROM, EEPROM, or Flash- Programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM or DVD-ROM), a PC card (e.g., PCMCIA card), or other memory device. The computer program may be fixed in any form in a signal that is transmittable to a computer using any of various communication technologies, including, but in no way limited to, analog technologies, digital technologies, optical technologies, wireless technologies (e.g., Bluetooth), networking technologies, and inter-networking technologies. The computer program may be distributed in any form as a removable storage medium with accompanying printed or electronic documentation (e.g., shrink wrapped software), preloaded with a computer system (e.g., on system ROM or fixed disk), or distributed from a server or electronic bulletin board over the communication system (e.g., the Internet or World Wide Web). Hardware logic (including programmable logic for use with a programmable logic device) implementing all or part of the functionality where described herein may be designed using traditional manual methods, or may be designed, captured, simulated, or documented electronically using various tools, such as Computer Aided Design (CAD)₁ a hardware description language (e.g., VHDL or AHDL), or a PLD programming language (e.g., PALASM, ABEL, or CUPL). Programmable logic may be fixed either permanently or transitorily in a tangible storage medium, such as a semiconductor memory device (e.g., a RAM, ROM, PROM, EEPROM, or Flash-Programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM or DVD-ROM), or other memory device. The programmable logic may be fixed in a signal that is transmittable to a computer using any of various communication technologies, including, but in no way limited to, analog technologies, digital technologies, optical technologies, wireless technologies (e.g., Bluetooth), networking technologies, and internetworking technologies. The programmable logic may be distributed as a removable storage medium with accompanying printed or electronic documentation (e.g., shrink wrapped software), preloaded with a computer system (e.g., on system ROM or fixed disk), or distributed from a server or electronic bulletin board over the communication system (e.g., the Internet or World Wide Web).

"Comprises/comprising¹¹ when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof." Thus, unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise¹, 'comprising', and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. An engine assembly comprising: an engine body having an inlet and an outlet for the admission of a heated working fluid into and out of an expansion zone wherein the body further comprises a heat exchange zone for the heated fluid.

2. An engine assembly as claimed in claim 1 wherein the expansion zone comprises a chamber and the heat exchange zone is located adjacent the chamber within the engine assembly.

3. An engine assembly as claimed in claim 1 or 2 wherein the heat exchange zone at least in part surrounds the expansion zone.

4. An engine assembly as claimed in any one of claims 1 to 3 wherein at least part of the engine assembly is exposed to the passage of working fluid for the purpose of cooling the heated fluid.

5. An engine assembly as claimed in any one of claims 1 to 4 wherein the heat exchange zone comprises a condensation zone adapted to transfer heat from the working fluid to the engine assembly.

6. An engine assembly as claimed in any one of claims 1 to 5 wherein a portion of the engine assembly comprises a unitary piece of metal into which the inlet extends.

7. An engine assembly comprising: an engine body having a plurality of cylinders adapted to facilitate the expansion of a heated working fluid wherein the body comprises at least one heat exchange zone disposed within the body adjacent the cylinders.

8. An engine assembly as claimed in claim 7 wherein the heat exchange zone comprises a cooling zone for cooling the fluid from about 120⁰C to about 105⁰C.

9. . An engine assembly as claimed in claim 7 or 8 wherein the heat exchange zone comprises a plurality of heat extraction chambers aligned in correspondence with the cylinders.

10. An engine assembly as claimed in any one of claims 7 to 9 wherein the heat exchange zone extends from immediately adjacent a first end of the cylinders.

11. An engine assembly as claimed in any one of claims 7 to 10 wherein the heat exchange zone extends to the outer walls of the engine assembly.

12. An engine comprising: an engine body having an inlet and an outlet for the passage of a heated working fluid into and out of an expansion zone wherein the body of the engine is configured as a heat exchanger for heated working fluid exhausted through the outlet.

13. An engine as claimed in claim 12 wherein the heat exchanger comprises one or a combination of: an engine block; at least one cylinder; an engine head; a rocker cover; a sump; engine oil; a cylinder head; a gear box; exhaust pipes; whole engine.

14. A method of operating an external combustion engine comprising the steps of: heating a fluid; inputting the heated fluid into an engine; expanding the heated fluid; using at least a portion of the engine assembly to exchange heat with the heated fluid exhausted there through.

15. A method as claimed in claim 14 wherein using at least a portion of the engine assembly to exchange heat comprises exposing at least a portion of the engine to a cooling fluid.

16. A method as claimed in claim 15 wherein the cooling fluid is air,

17. A method as claimed in claim 14, 15 or 16 wherein the heated fluid is expanded in an expansion zone and the step of using at least a portion of the engine assembly as a heat exchanger comprises exhausting the heated fluid from the expansion zone into a heat exchange zone within the engine.

18. A method as claimed in any one of claims 14 to 17 wherein the portion of the engine assembly used for heat exchange comprises one or a combination of: the engine block; the engine head; at least one cylinder; a rocker cover; a sump; engine oil; a cylinder head; a gear box; exhaust pipes; whole engine.

19. An engine arrangement comprising: an engine body; and an inlet for the admission of heated working fluid into an expansion zone within . the body; wherein the inlet is adapted to insulate the heated working fluid from the body so that the working fluid substantially maintains its temperature to the point of its admission into the inlet to the expansion zone.

20. An engine arrangement as claimed in claim 19 wherein the inlet comprises one or a combination of: stainless steel material; aluminium; aluminium alloy; steel.

21. An engine arrangement as claimed in claim 19 wherein the body comprises material substantially consisting of iron.

22. An engine arrangement as claimed in claim 19, 20 or 21 wherein the body is unlagged.

23. An engine arrangement as claimed in any one of claims 19 to 22 wherein a chamber of the body provides the expansion zone and is adapted to insulate the heated fluid from the body.

24. An engine arrangement as claimed in claim 23 wherein the chamber is adapted to insulate the heated fluid from the body by one or a combination of: at least one void located at the periphery of the chamber; at least one air void located at the periphery of the chamber; at least one cylinder sleeve located at the periphery of the chamber.

25. An engine arrangement as claimed in any one of claims 19 to 24 wherein the inlet comprises a valve assembly.

26. An engine arrangement comprising: an engine body operatively associated with an inlet for the admission of heated working fluid into an expansion zone provided by the body where the inlet comprises a passageway extending directly into a valve, arrangement within the body for admitting heated working fluid into the expansion zone.

27. An engine arrangement as claimed in claim 26 wherein the passageway provides an insulated conduit for heated fluid into the expansion zone.

28. An engine arrangement as claimed in claim 26 or 27 wherein the passageway comprises one or a combination of: a material of relatively low thermal absorption; a material of relatively low thermal conductivity; stainless steel material.

29. An engine arrangement as claimed in claim 26, 27 or 28 wherein the valve comprises one or a combination of: a material of relatively low thermal absorption; a material of relatively low thermal conductivity; stainless steel material.

30. An engine arrangement as claimed in any one of claims 26 to 29 wherein the body comprises material substantially consisting of iron.

31. An engine arrangement as claimed in any one of claims 26 to 30 having a head sealing plate and valve body comprising one or a combination of: a material of relatively low thermal absorption; a material of relatively low thermal conductivity; stainless steel.

32. An engine arrangement as claimed in any one of claims 26 to 31 wherein a piston is coated in a material comprising one or a combination of: an insulating material; a ceramic.

33. A manifold for an engine assembly wherein the manifold comprises a plurality of passages for directing heated working fluid into at least one expansion zone within the engine assembly, the manifold being adapted to insulate the heated working fluid so that the heated working fluid substantially maintains its temperature to the point of its admission into the expansion zone.

34. A manifold as claimed in claim 33 wherein the manifold comprises tubular stainless steel material and the engine assembly comprises material substantially consisting of iron.

35. A valve having a valve body configured to be mounted in an engine assembly and a stem moveable within the body, the body comprising insulating material to minimise heat loss from working fluid passing there within.

36. A valve as claimed in claim 35 wherein the valve comprises a poppet valve having a cyiindrical body.

37. A valve as claimed in claim 35 or 36 wherein the valve body and stem comprise stainless steel material.

38. A heat exchanger comprising a combustion chamber and a combustion arrangement wherein the combustion arrangement is adapted to direct hot combustion gases formed adjacent outer walls of the chamber inwardly toward a heat exchange region.

39. A heat exchanger as claimed in claim 38 wherein the combustion arrangement comprises a boiler tube configuration within the chamber arranged so that upon combustion, combustion gases are directed inwardly over the boiler tube configuration forming the heat exchange region.

40, A heat exchanger as claimed in any one of claims 38 or 39 wherein the combustion arrangement comprises a plurality of inlet ports spaced radially from a longitudinal central axis of the chamber.

41. . A heat exchanger as claimed in claim 40 wherein the inlet ports each comprise a controllable valve adapted to control the flow of air/fuel mixture from an inlet zone into at least one air manifold adapted to evenly distribute air/fuel mixture to the combustion chamber by providing a transverse flow of air/fuei with respect to a burner of the heat exchanger.

42. A heat exchanger as claimed in claim 41 wherein the controllable valves comprise butterfly valves.

43. A combustion boiler for a steam engine comprising a heat exchanger as claimed in any one of claims 38 to 42.

44. A heat exchanger comprising a generally radially configured chamber and a combustion arrangement comprising an inlet gas collection zone and an outlet gas collection zone spaced radially inwardly from the inlet gas collection zone wherein the arrangement is adapted to provide combustion between the respective gas collection zones.

45. A heat exchanger comprising a combustion zone operatively associated with the periphery of the heat exchanger and adapted to cause combustion gases to flow inwardly from the periphery.

46. A heat exchanger as claimed in claim 45 wherein the combustion zone extends around a heat exchange tube arrangement within the heat exchanger so that upon combustion, gases are directed inwardly over the tube arrangement.

47. A heat exchanger comprising a generally radially configured chamber and at least one wound tube adapted for transporting a working fluid in a generally radially outwardly directed path through a heat exchange region.

48. A heat exchanger as claimed in claim 47 wherein the at least one wound tube forms coils and the heat exchanger further comprises one of: a combustion arrangement as claimed in any one of claims 38 to 40 and 44; a combustion zone as claimed in any one of claims 45 and 46.

49. A method of using a heat exchanger having a combustion chamber comprising at least one or a combination of the following steps: igniting a fuel adjacent at least one peripheral wall of the combustion chamber; directing combustion gases inwardly towards an exhaust zone and over a heat exchange region intermediate the peripheral wall and the exhaust zone; providing a generally radially outwardly directed flow path for a working fluid from adjacent the exhaust zone of the combustion gases towards the peripheral wall of the combustion chamber; exchanging heat between the combustion gases and the working fluid within the heat exchange region.

50. A heat exchanger as claimed in any one of claims 38 to 42 and 44 to 48 wherein the heat exchanger is adapted for one or more of a: boiler for an external combustion engine; a residential water service; an industrial water service; a commercial water service.

51. A boiler tube arrangement for an external combustion engine comprising at least one wound tube forming a radially inwardly directed path for combustion gases.

52. A boiler tube arrangement as claimed in claim 51 wherein the at least one wound tube is adapted for transporting a working fluid in a radially outwardly directed path to exchange heat with the combustion gases.

53. A fuel inlet system comprising a plurality of inlets for the admission of fuel into a combustion zone wherein the inlets are arranged around the periphery of the combustion zone.

54. A fuel inlet system as claimed in claim 53 wherein the combustion zone is bounded externally by a rectilinear periphery and the inlets are each located adjacent an apex of the periphery of the combustion zone.

55. A fuel inlet system as claimed in claim 53 or 54 wherein the inlets comprise one or a combination of: butterfly valves; at least one air/fuel manifold.

56. A fuel inlet system as claimed in any one of claims 53 to 55 wherein the inlets are arranged around a cylindrical burner piate.

57. An air delivery arrangement for an external combustion engine comprising a blower element; a coupling configured to connect the blower element and an engine as well as the blower element and an independent drive source.

58. An air delivery arrangement as claimed in claim 57 wherein the blower element forms part of a boiler for supplying a heated working fluid to the engine.

59. An air delivery arrangement as claimed in claim 57 or 58 wherein the coupling comprises a belt extending between the blower element, the engine and the independent drive source.

60. An air delivery arrangement as claimed in any one of claims 57 to 59 comprising at least one freewheeling hub allowing the engine to drive, the blower element or the independent drive source to drive the blower element.

61. An air delivery arrangement as claimed in any one of claims 57 to 60 wherein the blower element is arranged for receiving a stream of air moving towards the blower element.

62. An air delivery system for an engine comprising a first energy source adapted to drive a blower; a second energy source adapted to drive the blower; and an air delivery means for directing external air directly to a combustion zone; wherein the first and second energy means are operatively connected to the blower such that the blower is engaged by the energy source with the greatest operational speed.

63. An air delivery system as claimed in claim 62 comprising a clutch arrangement to facilitate engagement of the first or second energy source.

64. An air delivery system as claimed in claim 63 wherein the clutch arrangement comprises at least one free wheeling hub.

65. An air delivery system as claimed in claim 62, 63 or 64 wherein the air delivery means is adapted to deliver air by a ram effect.

66. A mechanical arrangement comprising: a blower for a boiler; a first hub element for being mounted to an engine operatively associated with the boiler; a

^• second hub element for being mounted to an independent drive source; and a coupling for connecting the first and second hub elements and the blower wherein one of first and second hub elements is free wheeling such that either the engine or the independent drive source is able to drive the blower via the coupling.

67. An air delivery arrangement for an external combustion engine comprising a blower element arranged to receive air via the ram effect; a coupling configured to connect the blower element and an engine as well as the blower element and an independent drive source.

68. An air delivery arrangement as claimed in claim 67 wherein the independent drive source comprises an electric motor for driving the blower when the external combustion engine is operating at a speed insufficient to drive the blower, and the coupling is arranged to allow the engine to take over from the blower once the engine is operating at a sufficient speed to drive the blower.

69. An air delivery arrangement as claimed in claim 67 or 68 comprising a valve arrangement to control the amount of air delivered by the arrangement.

70. An external combustion engine comprising; a boiler and at least one fuel/air inlet wherein the at least one fuel/air inlet comprises at least one fuel injector for injecting atomized fuel by pumping under high pressure into a combustion zone of the boiler; the fuel injector being coupled to control logic for controlling the fuel in accordance with predetermined air and fuel criteria.

71. An external combustion engine as claimed in claim 70 wherein the fuel injection system comprises at least four fuel injectors as recited in claim 70 wherein the fuel injectors are arranged to inject fuel into one or a combination of air manifolds positioned around a boiler tube arrangement.

72. An external combustion engine as claimed in claim 70 or 71 comprising a steam engine.

73. An acoustic outlet for an external combustion engine comprising a steam bypass arrangement where the bypass arrangement directs steam from at least one engine cylinder to atmosphere.

74. An acoustic outlet as claimed in claim 73 wherein the bypass is further adapted to direct steam to a condenser.

75. An acoustic outlet wherein the bypass comprises a three way valve operatively connected to one or a combination of engine cylinder, condenser and atmosphere.

76. An acoustic outlet configured for direct coupling to an external combustion engine for producing an exhaust sound from heated working fluid.

77. A sound outlet as claimed in claim 76 wherein the sound outlet is adapted to provide at least one relatively low frequency exhaust note.

78. A sound outlet as claimed in claim 77 wherein the frequency is in the range of less than about 1 Hz to about 10 Hz.

79. A sound outlet as claimed in claims 77 or 78 wherein the at least one lower frequency exhaust note is provided as a low frequency steam locomotive sound.

80. An external combustion engine wherein a sound outlet is directly coupled to the engine for the generation of a sound from heated working fluid issuing therefrom.

81. An external combustion engine as claimed in claim 80 wherein the sound outlet comprises a three way valve with a first port thereof directly coupled to the engine, and a second port adapted to generate a sound, and a third port coupled to a condenser.

82. An external combustion system having an engine and a radiator wherein a sound outlet comprising a multi-way valve is coupled to both the engine and the radiator.

83. An engine comprising a body having a plurality of exhaust chambers and an outlet operatively associated therewith to produce a low frequency sound from at least one or a combination of the chambers.

84. An engine as claimed in claim 83 wherein the outlet is coupled to only one of the exhaust chambers.

85, A method of controlling the operation of an external combustion engine, the engine comprising a plurality of combustion zones, the method comprising delivering fuel into at least one of the combustion zones for ignition; igniting the fuel; and thereafter delivering fuel into one or a combination of the remaining zones for ignition.

86. A method of controlling a steam engine, comprising the steps of: monitoring the speed of the engine; monitoring the pressure and temperature of the steam issued by the boiler; monitoring the pressure of the steam entering at least one expansion chamber in the engine; determining a value indicative of the mass flow rate of steam consumed by the engine on the basis of at least one of said monitoring steps; and using the value determined to control one or a combination of: (i) water delivered into the boiler of the steam engine and (ii) the amount of fuel ignited in the boiler.

87. A method as claimed in claim 86 wherein the pressure and temperature are measured adjacent a throttle.

88. A valve control mechanism for an engine comprising a pivot element and a rocker operably connected to the pivot element, wherein the pivot element is movable between a first position and a second position to provide the valve control mechanism with at least two modes of operation for the engine.

89. A valve control mechanism as claimed in claim 88 wherein the valve control mechanism comprises a valve having an open condition and a closed condition and movement of the pivot element increases the range of the open condition from a range of about 10 degrees to about 30 degrees before top dead centre to a range of about 30 degrees to about 145 degrees past top dead centre.

90. A valve control mechanism as claimed in ciaim 89 wherein the valve control mechanism comprises a valve having an open condition and a closed condition and movement of the pivot element increases the duration of the open condition from about 30 degrees past top dead centre to about 145 degrees past top dead centre.

91. An engine having a valve control mechanism comprising a rocker having a pivot region wherein the pivot region is movable between a first position and a second position to provide the valve control mechanism with a first valve timing when the engine is operating and a second valve timing when the engine has stopped.

92. An engine having a valve control mechanism comprising a rocker having a pivot region wherein the pivot region is movable between a first position and a second position to provide the valve control mechanism with a first valve timing for when the engine is operating and a second valve timing for starting the engine.

93. An engine as claimed in claim 92 wherein the valve control mechanism has an inlet valve and an exhaust valve, the first valve timing corresponds with the inlet valve being open for a substantially smaller time compared to the exhaust valve, and the second valve timing corresponds with the inlet valve being open for a similar substantially smaller time as compared to the exhaust valve.

94. An engine as claimed in claim 92 wherein the first valve timing corresponds with the inlet valve being open over about 40 degrees and the second valve timing corresponds with the inlet valve being open over about 175 degrees.

95. An external combustion engine comprising a body having a plurality of expansion zones each comprising a piston comprising insulating material for preventing the loss of heat from the expansion zone through the piston into the remainder of the engine.

96. An external combustion engine as claimed in claim 95 wherein the insulating material of the piston comprises one or a combination of: a ceramic material; stainless steel.

97. Apparatus adapted to operate an external combustion engine, said apparatus comprising: processor means adapted to operate in accordance with a predetermined instruction set, said apparatus, in conjunction with said instruction set, being adapted to perform the method as claimed in any one of claims 14 to 18, 49, and 85 to 87.

98. A computer program product comprising: a computer usable medium having computer readable program code and computer readable system code embodied on said medium for operating an external combustion engine within a data processing system, said computer program product comprising: computer readable code within said computer usable medium for performing the method steps of any one of claims 14 to 18, 49, and 85 to 87.

99. A method or protocol as herein disclosed.

100. An apparatus, component and / or device as herein disclosed.