This application is a continuation-in-part of my United States application, Serial No: 696,022, Filed: 29 January 1985, entitled: REGENERATIVE THERMAL ENGINE.

This invention relates generally to thermal piston engines, and more particularly to structural and conceptual improvements that increase the efficiency of such engines.

The regenerating thermal engine of this invention combines unique components to achieve high efficiencies and low engine weights in compact, structurally and thermally integrated units. The primary object of this invention is to devise adiabatic engines which are capable of operating at high pressures and temperatures utilizing the total expansion of the generated gases without the size and weight customarily associated with such engines. Further, the use of exotic materials such as ceramics which add to the expense and complexity of such engines is not necessary in the thermal engines devised, enabling a flexibility in the choice of competing materials for construction of a highly efficient but low cost engine. ^• BACKGROUND ART

The superior characteristics of the piston engine have numerous applications, with both the military and commercial applications in transport and power generation well known. Numerous developmental paths are available for reducing specific fuel consumption, and for reducing the size and weight of the engine. Many of these paths, however, lead to undersized power plants ^• of high complexity and cost.

One main example is the "adiabatic-ceramic" engine. Actualizing this conception would result in an enormous combination of difficult high technology problems and high risk propositions. The implementation of this engine in mass production dictates a

fundamental restructure of the entire engine industry.

The feasibility of the adiabatic turbo-compound engine has been deomnstrated, but not without revealing all the immense problems associated with this technology. For example, the very hot walls (1000°C=1800°F) maintained by the ceramic engine reduced dramatically the volumetric efficiency of the engine. The extremely hot surfaces between the piston and clyinder and the friction resulting from the side thrust of conventionally connected pistons result in the continuous danger of coking of the lubrication oil in customary segment groves of the piston.

A fundamental contradiction in thermal effects results because of the insulation capacity of ceramic and the expansion ratio of a ceramic component in relation to a metallic base in composite material engines. In the same time, the so called "adiabatic" process defined with respect to ceramic engines is a false definition of the real thermodynamic process. To be adiabatic, it is necessary to obtain a continuous identity of the -temperatures of the combustion gases and the cylinder walls, or "zero" thermal difference between these two media, for zero heat transfer.

In general, when using ceramics in the composite design for the metallic diesel engine, the following properties are desired:

- Good heat insulation

- High temperature strength

- Low wear/corrosion/erosion characteristics

- Low friction characteristics

- High Hertz Stress/Fatigue Durability

- Low cost/weight

- Close tolerances and fine finishes

- Good dimensional stability

- Low Density

- Limited plasticity (creep)

- Good thermal shock resi stance

- High fracture toughness

All these desired properties are in a continuous contradiction with respect to available ceramic materials. An enormous financial effort is required to overcome all of these barriers which delays the commerialization of the ceramic adiabatic engine.

The energetically efficient performance of an engine is directly related to four primary parameter contradictions as expressed by the inter-relationship given below:

where:

•fl& -- _e - - specific weight of the air admitted into the cylinder cL = air/Fuel ratio

*iy = volumetric efficiency

X = rotation/min

-Jm = mechanical efficiency

* ₂ = peak pressure of the cycle

The state of the art of existing engines is limited by these four parameter contradictions as follows:

1.) When theA, is raised by high supercharging it is necessary to also raise the o. to maintain the thermal stress within normal limits. In this case, the ____* is essentially maintained constant.

2.) When the rotation 7l , is raised, the volumetric efficiency is reduced, but the product Lfyi _/ x yi f again essentially remains constant.

3.) When the rotation l is raised the mechanical losses also increase, reducing the mechanical efficiency of the engine.ffix^ttl

4.) When the maximum pressure of the the mechanical efficiency n is reduced, and again the

product essentially remains constant. ♦ -£m*føf

Finally, advancing state of the art engines is strongly limited by these contradictions as expressed in the natural reaction of the parameters to change as set forth in the three affected groups of parameters relationships as follows: ^s f [(^) v(* ^ft t)*ft* ^* V* &t)

In fact to resolve these contradictions and to open a new avenue for engine evolution in power, life and efficiency, one must determine the optimum conditions for maximization of these relationships in an unconventional manner as follows:

DISCLOSURE OF INVENTION

The engine embodiments described in this invention integrate select designs and components to achieve the conditions for optimizing the above described parameters. The engine embodiments combine features for adiabatic performance and full spectrum usage of generated high pressures and temperatures for maximum power and minimum weight. The engine constructions embodying these features are described in greater detail in the detailed description of the preferred embodiments hereafter.

In designing a high temperature adiabatic engine, major problems are involved in selection of materials and design of structures capable of withstanding both high temperatures and pressures, and, in particular, formulation of systems that can effectively and fully utilize the expanded pressure spectrum without thermal losses, particularly those losses associated with cooling zones of high temperature.

The following engine features directed to the combustion chamber provide a major solution to the problem of high temperatures in the combustion chamber of reciprocating engines designed to be adiabatic in performance:

a) The cylinder walls and all the hot surfaces of the combustion chamber are structured from regenerative cells in which the compressed air is cyclically infiltrated into the cells and acts like an insulating substance. b) The cyclic process of the intake, compression, expansion, exhaust and scavenging specific to the thermal piston engine activates the continuous movement of the compressed air from inside to outside of these regenerative cells. During this process, the air and the regenerative walls are simultaneously providing the insulation necessary for an actual internal thermal recovery. The energy

that is recovered is the equivalent to the energy that is lost in the cooling process in the normal diesel engine. c) The piston and the regenerative cells constitute an active sealing system in which a staggered labyrinth provides a high quality sealing process. This solution _^ solves the problem of thermal stress and opens the way to maximiz :ιng mβx

<&) d) The piston and the hot surfaces of the regenerative cells are not in contact and by definition, no lubrication is necessary. e) The side thrust of the piston against the cylinder walls in one application is eliminated by support of the piston by an interior zone of the metallic cylinder removed from the combustion zone in which exist low temperatures and a conventional lubrication that is not affected by the high temperatures of the combustion chamber. f) In another application, the side thrust of one piston (or opposed pistons in the same cylinder) is cancelled by an additional side thrust of a parallel side-by-side piston, connected in continuous' dynamic balance by an oppositely rotating dμal crank shaft mechanism. This mechanism is associated with a common combustion chamber in which the evolution of the pressure in both the associated cylinders is continuously equal. g) The piston by definition of its operation in these applications, is an extremely simple linear plunger, without side thrust and segments. This solution solves the problem of high mechanical loss by friction. /.-> A 4> ₂ wia*

h) The association of the regenerative internal process with the thermal cycle of the piston engine is by definition the ideal sequential heat exchange between the compressed, cooled air, and the internal surfaces of the combustion chamber. This process produces, at the same time, insulation, and recovery of the entire heat that is associated with the cooling process.

i) The regenerative thermal engine in one application is associated in an appropriate manner with a four cycle engine, which is convertible to a two cycle engine in the same configuration. This solution solves the problem of maximizing the groups

Cfyt*xf)aιa ^y *** (fn. ^m ) max ^' j) In a second application, the regenerative thermal engine is associated with an opposite piston engine (two pistons in each cylinder). k) The regenerative thermal engine in another application is associated with a mechanism in permanent dynamic balance, which avoids totally the side friction between the piston and the cylinders

1) The regenerative thermal process is not associated with lubrication of hot surfaces which are in contact with hot gases. m) In the regenerative thermal process, the cells of the regenerator are disposed in a particular angular superposition, creating a superimposed stratified heat barrier against heat transfer, in which the alternation of air spaces and the wall spearations (the fins) constitutes a multiple thermal shield. n) In all the applications of the regenerative thermal process, the continuous exchange of the air to the inside and to the outside of the ^■ cells, especially the outside radial movement of the air in the expansion stroke toward the cylinder space, produces a dynamic separation of the hot gases from the cylinder walls. The action produces a suppli entary dynamic air shield insulation, centralizing the hot combustion gases in the cylinder in a real adiabatic separation between the hot sources (combustion gases) and the cylinder walls (regenerative cells). o) The same radial movement of the air from the regenerative cells toward the cylinder central space avoids deposit of carbon particulates on the walls of the regenerator, constituting a continuous air cleaning system. p) In the expansion stroke the radial movement of fresh compressed air, accumulated in the regenerative cells, amplifies

the turbulence and supplies preheated air for the final process of combustion process. This eliminates the problem of heat lost by a cooling system and pollution problems associated with current state of the art engines. q) The embodiment of the regenerative thermal engine in a configuration with pistons in permanent dynamic balance with double counter rotating shafts, with a positive screw expander, is an optimization of all the maximum conditions in the thermodynamics of the engine. All these factors can increase the supercharging to ps £ 10bars

- excess of air to o = 1.2-1.4

- the rotation to n≥ 10,000 RPM

- the peak pressure p 200-250 bars

- the fr %j

These parameters can be increased independently or together. and to reduce the fuel consumption near 9β -sT -tl Jb/ -^

In this case the number of cylinders in an engine to cover all practical power requirements can be reduced to- 2. r) The applications are associated with a ^* no liquid-oil lubrication. Oil lubrication is replaced by air in the combustion zone and a solid suspension composed by micro-particulates of graphite and MoS2, which are injected in the roller bearings and between all the friction surfaces in the cool zones. The cooled compressed air for suspension is supplied by the supercharging system. The recollection of the micro-particulates is assured by a battery of cyclones, and the air partially expanded is recirculated before the high pressure stage of the compression.

The reduction in size and weight and the large power concentration associated with a low-fuel consuming, multi-fuel unpolluting operation are the primary qualities of the regenerative thermal engine. . However, to fully utilize the potential capabilities of the high temperatures and pressures possible with the regenerative

thermal engine, integration of the engine with compatible energy recovery systems is advantageous for maximized efficiency.

The regenerative thermal engine, may be associated in a combined cycle, to produce an internal cogeneration of power and superheated steam of Rankine type. The Rankine cycle develops itself simultaneously on the basis of a utilization of residual energy in the thermal cycle of the reciprocating internal combustion engine.

The regenerative thermal engine with internal combustion in combination with the steam generator and the thermal engine with steam, make up a unique machine. The machine's separate thermal cycles (gases and steam) develop themselves in parallel, simultaneously, recuperatively, compensatorily and integratedly. The working agent is made up in the active phases (expansion and exhaust) by the burnt gases of the internal combustion engine and by the superheated steam, generated by the integrated recuperative regenerator. The mixed burnt gases and superheated steam makes up a homogeneous -working agent that acts on the piston and on a turbine (if used for a supercharged-engine).

The residual energy of the thermal cycle of the internal combustion engine is transferred to the Rankine cycle of the integrated steam generator by a complex heat transfer (conduction, convection, radiation, contact and mixing) which takes place through the walls of the cylinders of the internal combustion engine, towards the cooling fluid that is injected in the regenerative cells, from outside to inside (radially). The cooling fluid passes through the stage of preheating, vaporization and superheating, finally being injected simultaneously with the fuel injection, in the inner cylinder cooling jacket and from here in a chamber, concentric with the combustion chamber, where simultaneously takes place the fuel combustion and the process of vaporization and the final superheating of the steam. The mixing of the two working agents and expansion in the cylinder

of the thermal reciprocating engine, continued in the turbine of gases and steam, allows the complete utilization of the thermal energy (of the gases and steam) by expansion up to the energetically runout thermal parameters, close to the condensation state of the water steam. Final condensation takes place in the noise-absorber with condenser, which finishes thus the route of the working fluid. The recovered water in the condenser (preferably at 80-90 degrees C.) is introduced again in the thermal cycle of the integrated thermal engine with an increase in quantity of the condensated steams resulting from the products of hydrocarbon combustion. The ensemble of the integrated, regenerative thermal cycles, which carries and recuperates all the thermal energy generated in the engine cylinder from outside towards inside, automatically creates an adiabatic state of total elimination of thermal loss and leads to the removal of the cooling system (excepting that of the supercharging air).

In order to effectively utilize the runout thermal energy of the resulting working agent in a compact unit, it is necessary to integrate select components which can most efficiently operate under conditions of low, medium or high pressures. A complete utilization of the thermal energy-developed in the combustion process can be accomplished only in the case of an effective harnessing of the total expansion of the combustion gases, from the highest pressure of the cycle to the lowest pressure of the ambient air, exhausting the working gases at the lowest temperature possible.

However, a super-long expansion in the cylinders of a reciprocating piston engine is possible only in very large engines with t≥ry low rotations. In such engines as the Sulzer and the Burinmeister and Wain naval engines, in which the ratio of stroke to bore reach 3-4, thermal efficiencies exceed 53%.

In the 720° rotation of the crank shaft during the thermal cycle of a four stroke engine, the evolution of the pressure in the

time of the intake, compression, combustion-expansion and exhaust, define various periods of low pressure medium pressure and high pressure. The low and medium pressure periods of the cycle cover 80%-90% of the cycle. Only 10-20% of the cycle or 70% of the 720° cycle rotation is associated with the high pressure period of final compression, combustion and initial expansion. Despite the very short duration of the high pressure period (10-20% of cycle time) engines are constructed to withstand this maximum pressure throughout the 720° rotation cycle. The mass of metal and high strength structure is wasted during the rest of the cycle in which only medium and low pressure is encountered. As a result of this factor, actual engines are big, heavy, expensive and inefficient.

In a basic embodiment of an engine capable of effective utilization of the full spectrum of expansion pressures is an integrated rotary-reciprocal compound engine which developes an equivalent compression ratio to the long stroke engines described. The low and medium pressures are developed in the rotary component and include 40% of the cycle in a rotocompressor for compression and 40% in a rotoexpander for expansion. The high pressures are developed in final compression and initial expansion in the reciprocal piston component.

Conventional engines are limited in peak pressure to approximately 150 bars. This level establishes a practical limit for compression ratios including supercharged engines. Thermal efficiency rises with increases in the compression ratio, but the limited peak pressure for conventional engines limits thermal efficiency. Peak pressure is limited in principle by friction, particularly by friction forces associated with the side thrust of the piston against the cylinder liner from the angular oscillation of the connecting rod, and, inertia, particularly inertia! forces associated with the increase in size and weight of moving parts designed to accommodate increased peak pressures. These adverse

• factors define the limit of evolution of conventional engines.

The rotary reciprocal compound engine accommodates high pressures in a reciprocator component which includes low mass pistons with short dual connecting rods to counterrotating crank shafts that as a unit eliminate side thrust of the piston and hence the thrust associated friction. The result is a small component which provides rotary compression and expansion for 80-90% of the total engine displacement. The reciprocator and rotor are interconnected by a gear box with a transmission ratio adapted for optimum volumetric efficiency. Alternately a gear box with a variable transmission ratio can be utilized to vary the total displacement of the compound engine with variable compression ratio, variable supercharging ratio and variable expansion ratio.

The rotary reciprocal compound engine in one embodiment is characterized by a monocylinder having a single piston connected to two splayed connecting rods each connected to a separate crankshaft in combination with a positive rotary compressor-expander of a screw type or e ^' pifrochoidal type similar to a Wankel engine. This embodiment defines ^* a three stage pressure evolution with a low pressure, rotocompressor stage,- a high pressure reciprocator stage, and a medium pressure rotoexpander stage. The total thermal cycle of such engine defines a superlong compression expansion cycle characterized by a very high efficiency.

A similar embodiment is constructed with a reciprocator component having an efficient uniflow scavenging process in a single cylinder with opposed pistons, each piston similarly connected to two connecting rods and counter rotating crank shaft mechanisms.

Intergrating a Comprex ^® pressure wave converter between the rotor component and the reciprocator component, or between the reciprocator component and another expander further enhances the

efficiency.

For a super power regime, the excess air existing in the combustion gases from the reciprocator component can be used in an afterburner chamber in which the working fluid can be rejected and further expanded in subsequent stages of the engine.

Finally in a wholly integrated system of a rotor-reciprocator, compound engine a thermoenergetic cascade can be developed from selectively connecting or disconnecting the following components: low pressure rotocompressor high pressure reciprocator medium pressure rotoexpander intercombustion chambers - compressor wave converters intercooler and recuperators tubocharger

The thermoenergetic cas ^' cade can operate partially, energetically based on an intercombustion chamber producing combustion gases only for the rotary component with the reciprocator component disconnected. Similarly the cascade can operate partially, energetically based only on the reciprocator component with the rotary component disconnected.

By use of a compound rotary reciprocal engine, peak pressures can be raised from 150 atm to 180 or 200 atm. Because of the extremely high combustion temperatures involved, the cylinder chamber of the reciprocator component utilizes the recuperative regenerator previously described to achieve adiabatic engine performance.

These and other features will become apparent from a consideration of the various exemplar embodiments shown in the drawings and described in the detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of the combustion chamber of a rotary valve, convertible 2 to 4 stroke engine with the regenerative thermal chamber wall.

FIG. 2 is a schematic cycle diagram for the engine of FIG. 1 operating in the four stroke mode with:

2.1 and 2.1.1 showing final exhaust and rotary valve chamber scavenging,

2.2 and 2.2.1 showing admission through the rotary valve and supplemental admission through the ports at the cylinder base,

2.3 and 2.3.1 showing compression and rotary valve scavenging,

2.4 and 2.4.1 showing exhaust through the rotary valve and scavenging through the cylinder base ports,

2.5 and 2.5.1 showing exhaust through the rotary valve,

FIG. 3 is a schematic gas flow diagram for the rotary valve and ports of FIG. 2.

FIG. 4 is a cross sectional view of an embodiment of the combustion section of a turbocharged, convertible 2 to 4 stroke engine.

FIG. 5 is a cross sectional view of an embodiment of a combustion section of a two stroke engine.

FIG. 6 is a cross sectional view of. an embodiment of a combustion and drive section of a convertible, 2 to 4 stroke engine with a differential piston.

FIG. 7 is a cross sectional view of a compound reciprocal-rotary engine with an opposed piston reciprocator unit and a supercharger.

FIG. 8 is an enlarged partial cross sectional view of the regenerator lining for the combustion chamber of the engines disclosed.

FIG. 9 is a schematic view of a typical pressure curve for a four stroke engine.

FIG. 10 is a cross sectional view of an embodiment of the

combustion and drive section of a convertible 2 to 4 stroke engine with dual interconnected pistons and a connected combustion chamber.

FIG. 11 is a schematic view of a compount a reciprocal rotary screw engine.

FIG. 12 is a cross sectional view of the combustion and drive section of a single piston, dual crank engine component.

FIG. 13 is a cross sectional view of the engine component of FIG. 12 in combination with a rotary component.

FIG. 14 is a cross sectional view of the combustion and drive section of an opposed piston dual crank engine component.

FIG. 15 is a cross sectional view of the engine component of FIG. 14 in combination with a rotary component.

FIG. 16 is a cross sectional view of an alternate arrangement of the engine component of FIG. 14 in combination with a rotary component.

FIG. 17 is a schematic illustration of a compound reciprocal rotary engine with an intermediate pressure wave sueprcharger.

FIG. 18 is a schematic illustration of a compound reciprocal with an intermediate intercombuster.

FIG. 19 is a schematic illustration of a compound reciprocal with an intermediate intercombuster and auxiliary turbocharger.

FIG. 20 is a schematic illustration of a compound reciprocal with an intermediate pressure wave supercharger and an auxilliary turbocharger.

FIG. 21 is a schematic illustration of a compound reciprocal with an intermediate pressure wave supercharger and intercombuster and an auxilliary turbocharger.

FIG. 22 is a schematic illustration of a compound reciprocal with an intermediate pressure wave supercharger and intercombuster and an auxilliary pressure wave supercharger and turbocharger.

BEST MODES OF CARRYING OUT INVENTION

Referring now to FIGS. 1 and 4, two similar embodiments of a convertible four and two-stroke engine with integrated thermal cycles are shown running in the four stroke mode. Each engine is made up of a outer block 1, provided with an inner regenerative cells system or regenerator 2, centered on the liner 3, with the working cylinder 3.5 in the interior having circular air grooves 4 on the inner part forming a labyrinth sealing system and discrete pressure cells for heat transfer by regeneration. At the base of the cylinder are ports 5 for supplementary air admission and scavenging, controlled by the piston 6. A unique valve 7 reciprocated in a ratio n/2 by the camshaft 80 is located in the central upper part 50 or crown of the cylinder, being centered in a rotative distributor valve 8, supported by a radial-axial bearing 9 and driven in rotation by a gear 10. The reciprocating motion of the valve is achieved by a cam 11, which actuates a tappet 12, or a rocker 12.1, by the agency of an adjusting plate 13. The springs 14 and the axial bearing 15 assure the continuous operation of the push valve 7 and distributor valve 8.

As shown in FIG. 4, air is absorbed by the compression side of a turbocharger or turbocompressor 16, which blows the compressed air towards an intermediary cooler 17, from where through ports 5 the air enters the base of the engine cylinder. Simultaneously, compressed air reaches the zone of the central valve 7 by the pipe 18 and enters the engine cylinder in the period of time when the rotator distributor valve 8 assures the admission period. The piston 6 is provided with a recessed central combustion chamber 28 for initial combustion. The exhaust gases escape from the cylinder by the central valve 7 and through the rotative distributor valve 8, when it is in its exhaust period, and are led to the exhaust-gas turbine side of the turbocharger 16, from where the gases enter a noise-absorber (8.5). In parallel with the main air-circuit, the

engine is provided with a bypass circuit made up of a pipe 20, a butterfly valve 21, an annexed combustion chamber 22 and an additional pipe 23 for the burned-gases. This provides an auxilliary combustion circuit to initiate air compression by the turbocharger. A similar turbocharging system can be added to the embodiment of FIG. 1.

The regenerative thermal process is based on the penetration, intake and compression inside the cells 4 of the regenerative jacket of the regenerator 2 of freshly cooled, high pressure air, supplied by the intercooled supercharging system during the scavenging process.

In the compression stroke, a part of this air is accumulated and perssurized inside the regenerator cells 4, absorbing the thermal energy accumulated in the walls of the regenerator jacket or regenerator 2.

The accumulation of the compressed air in the cells 4 of the regenerator 2 produces a staggered labyrinth sealing system, whtch forms an active counter-pressure against the _. combustion gases escaping.

At the same time in the expansion stroke, the compressed air accumulated inside the cells 4 expands toward the cylinder space, generating a dynamic, concentric-radial and centripetal flow, which forms an envelope of air surrounding the hot gases, creating a pneumatic insulation between the hot gases and the walls. The heat radiated from the hot gases is in general the principal source of heat transfer to the cylinder walls. Another effect, perhaps the most important, is the expansion of the compressed air, which on being further heated possesses a higher enthalpy, thereby recovering the energy accumulated in the regenerated cell system.

This compressed and preheated air is an ideal ^* additive to the combustion process. The air is supplied from the walls of

the cylinder 3.5 in the final stage of combustion when the concentration of oxygen is reduced. The radial injection of the air to the combustion gases has an additional turbulent effect for aiding complete combustion.

Finally, the air and the regenerative cells together form an ideal insulation and an adiabatic shield against the transfer of thermal energy which is normally lost through the cooling system.

Because the piston 6 is a perfect cylindrical body, without contact with the hot wall zone of the cylinder, lubrication and oil can be completely avoided, including all associated mechanical losses. The piston is guided in the bottom zone of the cylinder, which is a conventional cylinder liner. The bottom zone is very well lubricated and at a very low temperature. It is lubricated, by an air and solid suspension, composed of micro-particulates of graphite and Mos2 (which are injected between the contact surfaces). The same air and solid micro particulates suspensions are injected into all the roll bearings, assuring ^' the lubrication and the removal of the heat generated' in the bearings.

The cooled compressed air for the lubrication is supplied by the supercharging system.

The recollection of the micro-particulates is assured by a group of cyclone traps. The air that is partially expanded and heated by this process is returned before the intercooler of the high stage supercharger for recompression to the final pressure. Alternately, the bottom zone of the cylinder and bearings can be lubricated by conventional means.

The process and the two and four-stroke convertible engine with integrated thermal cycles operates according to the invention as follows:

The turbine driven air compressor 16, electrically driven, begins to deliver compressed air to the combustion chamber 22, which starts and accelerates the turbo air blower at the normal speed delivering the supercharging air.

The engine, being started, can run from the beginning in the maximal working regime.

The functional succession of the strokes in the four-stroke cycle with unified distribution by the single valve 7 and the ports

5 takes place as shown in FIG. 2, illustrations 2.1, 2.2, 2.3, 2.4, 2.5.

Position 2.1 - Exhaust cut-off when the central valve is completely open, the piston 6 is in the top dead center and rotative distributor valve 8 is in the position indicated by illustration 2.1.1, wherein takes place the superior scavenging of the burnt-gases with the fresh compressed air originating in the pipe 18.

Position 2.2 - The air admission takes place by cylinder connection with ^* the pipe 18 while the piston 6 is moving down, the central valve 7 is open and the rotative distributor is in position 2.2.1. The piston 6 opens the air ports 5, by which a supplementary air quantity is delivered. The admission section total can either equal or surpass the piston surface, leading to a fitting of maximum order.

Position 2.3 - The air compression takes place after closing of the air ports 5 at the cylinder base by the piston while the piston

6 is going up. The central valve 7 is closed and the rotative distributor 8 is in position 2.3.1. The fuel injection, and combustion take place at the end of the compression.

Position 2.4 - The expansion takes place while the piston

6 is moving down, up to the momement when the unique valve 7 is opened and produces the free exahust of the burnt gases. At about the same moment the piston opens the savenging ports 5, through which penetrates the scavenging air, which pushes the burnt-gases out of the cylinder. In this moment, the rotative distributor 8 is in position 2.4.1 connecting the cylinder and exhaust ainfold for exhaust of gases to the turbine side of the turbocharger.

Position 2.5 - The piston 6 goes up during the exhaust-phase and expunges the gas mixture toward turbocharger 16. During this phase the unique valve 7 is completely open and the rotative distributor 8 is in position 2.5.1, assuring continued connection between the cylinder and the exhaust-manifold.

In FIG. 3 is illustrated a schematical variation of the chronosections in connection with illustrations 2.1, 2.2, 2.3, 2.4 and 2.5 of FIG. 2, the following conclusions being drawn:

During the preliminary exhaust phase 2.4 the burnt gases are ^" strongly pushed from the ^* cylinder by the force scavenging air through the ports 5, assuring a thorough cleaning of the cylinder of combusted gases, and an inner cooling of the piston surface the cylinder, head and the exhaust valve.

During the exhaust phase 2.5, the mixture of gases and scavenging air that entered the ports 5 is exhausted by the piston 6 as far as the top dead center.

During the upper scavenging phase 2.1, the piston 6 finished the complete gases exhaust and the rotative distributor 8 assures an upper scavenging 2.1.1, which complete the perfect cleaning of the cylinder of useless gases (burnt gases and/or of expansion).

During the admission phase 2.2, the rotative distributor 8 is in position 2.2.1, and the air enters through the valve 7 and

through the ports 5 into the cylinder, completing air fill of the cylinder.

The operation of the convertible engine in the two stroke variant is carried out by changing the rotation ratio (from n/2 to n/1) between the crankshaft and the camshaft 11, which is shifted axially and actuates the proper cam 51 for the two stroke cycle. In this variant the rotative distributor 8 is in the position of permanent exhaust 2.4.1. The fuel injection system (not shown) having an injection cycle synchronized with the camshaft, automatically changes to the new cycle regime. Particularly, the speed governor of the injection pump continues to be driven from the engine camshaft 80 but at twice the rate. In this functional regime the valve 7 becomes the exhaust valve and the ports 5 become the intake and carry out the scavenging and filling of the cylinder.

The two stroke engine with integrated thermal cycles, according to FIG. 5, is made up of a cylinder block 29, provided with an insulated chamber 30. The cylinder block 29 backs a compound material liner 3 with an upper cylindrical regenerator 2 forming the primary cylinder wall of the working combustion chamber and also backs a ceramic annulus 31, which is provided at the lower part of the cylinder with some admission and scavenging ports 31 and some exhausting ports 33. On the central upper part 50 of the ceramic crown is provided a concentric chamber 34, which assures air and steam superheating by contact with the walls of the combustion chamber

35 and with the burned gases, which flow through the upper ducts

36 and by the central nozzle 37 in a flow pattern controlled by the profile 38 of the piston 39. The air being absorbed by the air compressor side of the turbo-blower or turbocharger 40 is sent to the air cooler 41, from where it enters into the engine cylinder through the scavenging ports 32. The turbo-blower 40 is supplied, at the engine start and during heavy-duty conditions, with burnt gases delivered by the combustion chamber 42, which works in a bypass

circuit, controlled by a butterfly valve 43, blowing the burnt gases though the pipe 44 to the inlet of the gas turbine side of the turbo blower 40 from where the expanded gases, mixed with the gases exhausted from the cylinder by the exhausting ports 33, enter the sound absorber

(not shown).

The operation of the two-stroke engine with intake and exhaust distribution through cylinder ports with integrated thermal cycles, according to my invention and to FIG. 5, takes place as follows:

The turbo-blower 40 is driven into rotation by an electrical starter and supplies air from the compressor end of the turbocharger 40 to the combustion chamber 42, which through combustion brings the turbo blower 40 to the normal rotation rate. This operation allows supply of the air necessary for the two stroke engine operation. Simultaneously, the engine is driven by an .electrical starter, which releases its engagement in conditions of normal regime.

The expansion of the homogeneous mixture of steam and burnt gases up to the inlet parameters of the turbine side of the turbo blower 40 and the final expansion in the turbo blower and in the sound absorber where gases are discharged at a termperature of about 120° C. renders an effective utilization of the potential energy of the working fluid.

Referring to the engine embodiment of FIG. 6, a convertible four to two stroke, regenerative thermal engine is shown. The engine includes a block 1 with a valve assembly 84 and fuel injector 85 similar to those of the engine of FIG. 1. The engine is provided with a differential piston 24 having an enlarged cap 86 coupled to a central cross head 25 which is guided in a low temperature guide cylinder 87 in the block 1. The scavenging ports 5 at the base of the combustion chamber are controlled by a sliding valve 26 which can completely close the ports 5. In such case the engine operates

in a four stroke mode without any supplementary intake and scavenging by the ports. This operating regime is specific for the start period, and also for low regimes of the power which doesn't need scavenging because the exhaust gases are at low temperatures.

When the power is increased and the exhaust gas temperatures increase to 500-600° C, the sliding valve is spun on a screw thread by an external mechanism (not shown) in direct relation with the load, providing access to the scavenging air to penetrate and dilute the exhaust gases. This maintains a constant maximum exhaust gas temperature that is permissible for a turbine of a turbocharger (not shown) to operate at the optimum efficiency level.

The enlarged cap 86 is fabricated from a strong, high temperature tolerant material such as stainless steel. The cap 86 is constructed with a depending lip that overlaps a projection of the guide cylinder 87 to form a complex sealing passage during the down stroke. In the up stroke the piston cap newer contacts the regenerative jacket 2 since the regenerative cells 4 provide the equivalent of a complex .labyrinth groove sealing as well as a regenerative cycling of compressed air trapped in the cells during a compression stroke.

The crankshaft 81 and the connecting rod 82 are supported by roller bearings 83, lubricated and cooled by air and graphite + MoS2 particulates. The rest of the components are essentially the same as in the FIGS. 1 and 4.

In all the applications of the regenerator 2 a cogeneration thermal process, may be added by injecting preheated cooling fluid (methonol, liquid Mo2, liquified gases, or water) by an injection system which comprises a series of spaced nozzles 79 around the crown 50 of the combustion chamber which direct an arcuate spray down the walls of the regenerator during the brief period that the piston

is rising in its compression stroke. A liquid injector 78 feeds the nozzles with liquid, usually water in a measured timed pulse. The high velocity spray mist is drawn into the regenerative cells which cover the walls of the combustion chamber by action of the increasing chamber pressure as the piston rises. The heating, evaporating and the super-heating process is accomplished in the time in which the piston is near the top dead point. The flushing of this superheated steam or additional combusted cooling fluid after the peak combustion time occurs as an admixture to the regular combustion gases. In the case of steam there is associated a Rankine cycle with the regenerative, thermal cycle. The homogeneous mixture between combustion gases and superheated steam, and the preheated air expanded from the regenerative cells, are the final working fluid that drives the piston and any exhaust powered auxilliary or integrated component as described with relation to the other engine embodiments.

Referring to the engine embodiment of FIG. 7, the regenerative thermal engine shown comprises a rotary reciprocal compound engine with a two stroke, opposed piston component 88 coupled to a rotary piston component 92. The compound engine includes a turbocharger 97 and two iήtercoolers 96 and 98 between the air compression stages. •

The opposed piston or reciprocator component 88 is similar in construction to the engine embodiment of FIG. 6. Opposed differential pistons 24 drive two crank shafts 81 coupled to the pistons by connecting rods 82. Replacing the head and rotary valve assembly of the FIG. 6- embodiment is a side mounted fuel injector 89. The compound liner 3 includes a central segment comprising the regenerator 2 and end segments forming scavenging ports 5 and exhaust ports 91.

The rotary piston component 92 is a roto-compound system composed of a compressor stage 93 and an expander stage 94. The

compressor stage 93 receives precompressed air from the compresser side of the turbocharger, which is cooled by an intercooler 98. The precompressed and cooled air is further compressed by the positive displacement compressor stage of the rotary component 92 and after cooling by a second intercooler 96, enters the reciprocator component 88 through intake ports 5. The entering air under medium compression is further compressed by the united compression stroke of the two opposed pistons 24 to a substantially higher than usual compression. Fuel injected through an injector 89 ignites in the small core chamber between the piston heads and generates the extremely high pressures herebefore unattainable in piston engines. Because the single combustion chamber is centralized, stresses are localized and confined to a cylindrical structure, a configuration best able to withstand the extraordinary high pressures generated. The piston cap 24 is of special construction and fabricated from a high strength material such as stainless steel, and is coupled to the central cross head 25 which reciprocates in the low temperature cylinder guide 87 of the engine block 1. The short connecting rods 82 and heavy duty cranks 81 absorb the high energy thrust of the pistons 24 and enable a high, torque, high r.p.m. operation. Cooling of the cylinder walls by the regenerator is accomplised as explained with reference to FIGS. 1 and 4. The expanding combustion gases exhaust through ports 91 and enter the expander stage 93 of the roto-compound system 92 powering the rotor-piston component 92.

The positive displacement rotary component 92 is an epitrochoidal - type engine similar in type to the Wankel engine. While it has certain attributes of relative efficiency due to its low inertia, rotary operation, it is not effective at high pressures and temperatures because of sealing problems. However, it is ideally suited to accept the partially expanded gases from the high pressure reciprocator component because of its volumetric efficiency. The rotary component is coupled to the reciprocator component in the proper ratio of rotation for a volumetric exchange that assures a

high pressure ratio for the supercharging and a high expander ratio for the exhaust gases.

The rotary component 92 is provided with a ceramic or an insulated rotative piston 87 and is lubricated and cooled by a graphite/MoS2 dry lubricant supplied pneumatically, to the gear and bearing mechanism. The absence of oil and friction between the rotor piston and the epitrochoidal case prevents any excessive wear at high rotational speeds. Sealing is assured by autoadjusting material of Teflon ^® type impregnated with graphite and MoS2 on the edges of the triangle 99. This same material is provided for the lateral sealing 100.

As noted in the summary of the invention, the unification of the medium pressure rotary component with the high pressure reciprocator component enables a high peak pressure to be developed with only the engine structure in the high pressure zone being necessarily designed to withstand such high peak pressures. Ihis intimate integration enables a substantial reduction in engine size and weight to achieve a desired power output.

Referring to FIG. 8 an enlarged cross sectional schematic of the regenerator is shown. The rising piston 24 creates a pressure wave that is increasing. Low pressure admission air in the chamber is forced into the cells of the regenerator. Because each cell has an incrementally increasing pressure, leakage by the advancing edge of the piston is soon absorbed by a lower cell in the pressure cascade.

In embodiments employing a cogenerator, for example, water injection, the fine droplets of water in the spray are directed at the walls of the regenerator are swept into the cells with the packing air. In the cells the water is vaporized cooling the fins and the vaporized water is released as superheated steam with the compressed air during the power stroke confining the peak temperature gases

of combustion at the center of the chamber. Even without water injection the release of the compressed air in the cells provides a buffer and the hot gas core. A helicoidal passageway 150 between the liner 3 and the wall of the block 1, preheats water which may be alternately injected through the jacket means 151 of the liner by injection ports 152 at the upper end of the cylinder.

FIG. 9 is a schematic illustration of the typical pressure curve over a 720° crank shaft rotation in a four stroke engine. As illustrated only a small band of 70° is associated with pressures exceeding 37 atm and over half of the remaining cycle pressure is less than 6 atm. By staging the components in an integrated unit that is volumetrically balanced, with each component constructed to withstand those pressures and temperatures within its operating range, a boost in the peak pressure can be obtained at the same time a reduction in size and weight is accomplished. For example, a low pressure range can be efficiently handled by a supercharger, a medium pressure range by a positive displacement rotary device, and the high pressure range handled by a specially designed reciprocal piston ^• device.. An efficient thermoenergetical cascade following the pressure curve can be developed by an integrated engine incorporating these exemplar devices.

In the FIG. 10 embodiment, the regenerative thermal engine shown is a convertible four and two stroke device having, a twin arrangement of piston 24 with permanent dynamic balance. The pistons have a common and symetric cycle, by the fact that they are provided with a central, common combustion chamber 101, connected with two tangential channels 102 to cylinders. The two piston mechanisms are connected by a strap 103, which takes the opposed side thrust produced by the two counter-rotating crankshafts 81.1 and 81.2. Both counter-rotating crankshafts are geared outside in a 1/1 ratio, assuring perfect symetry and synchronism of both movements.

This arrangement totally avoids any side thrust between the piston and the cylinder walls, excluding a major source of

mechanical losses, and a close tolerance to be maintained between the pistons 24 and the regenerator 105.

In the schematic FIG. 11, the regenerative thermal engine of FIG. 10 is associated with a conventional screw compressor 103 and a screw-expander 104, connected directly on the both crankshafts of the mechanism in permanent dynamic balance. The counter rotating shafts of the balanced crank mechanism are ideal for a compound screw device of the type made by

The high compressed air is inter-cooled in a heat exchanger 105, and the exhaust gases are transported through the pipe 106 from the cyl nder head to the screw-expander 104.

The screw-expander 104, is provided with ceramic counter-rotating rotors and sealed by auto-adjusting elements made from teflon impregnated with graphite + MoS2.

Referring to FIGS. 12 and 13 the concepts for balanced engine operation disclosed with reference .to FIG. 10, are combined in an advanced compound, reciprocal-rotary engine 108. While the engine embodiment of FIGS. 12 and 13 and ^' the subsequent advanced design embodiments are particularly devised to incorporate the regenerator liner disclosed herein (since such designs advantageously eliminate piston side thrust) the constructions have independent merit and may incorporate other exotic liners, particularly liners demanding that piston and cylinder wall contact be wholly eliminated. The following embodiments, particularly the schematic arrangements disclosed in FIGS. 17-22, disclose variations of integrated components that are configured to achieve a thermal energetical cascade following as closely as practicable idealized pressure curves of the type described with reference to the schematically illustrated curve of FIG. 9, but with substantially elevated peak pressures and temperatures.

In the compound reciprocal-rotary engine of FIG. 12 a single cylinder 110 contains a single reciprocating piston 111. While the piston is shown with external grooves 107 for labyrinth sealing or ring sealing in conjunction with a high temperature cylinder liner

3, it is to be understood that the combustion chamber design is particularly suited for incorporation of the regenerator liner as hereinbefore described.

The large bore, short stroke reciprocator component of the compound engine is designed for high pressures and includes two connecting rods 112 connecting the single piston to two counterrotating, balanced crank shafts 113. The single cylinder 110 has a torroidal adiabatic combustion chamber 114 with a central fuel injector 115. The cylinder has staggered exhaust ports 116 and scavenging ports 117.

The counter-rotating gears 118 interconnect the two crankshafts in a symetrical and •synchoneous movement.- The offset intermediate gear 119, engaging one of th crankshaft gears, integrates the rotary component with the reciprocator component. As shown in FIG. 13, the epitrochoidal compressor-expander 92 is integrally coupled to the reciprocator component. The compressor-expander 92 supplies the combusted chamber of the reciprocal pistons with compressed air, and is simultaneously driven by the partially expanded exhaust gases in the manner previously described.

Referring to the engine embodiment of FIG. 14, a super compact, high pressure reciprocator component 125 is shown. Utilizing the dual rod concept of the embodiment of FIGS. 12 and 13, an opposed piston, single chamber reciprocator is formed with the large bore, short stroke features of the prior embodiment. In this embodiment opposed pistons are arranged in a single combustion chamber 120 with a central liner 122 that preferably is an adiabatic regenerator 122

of the type described. At opposed ends of the combustion chamber are exhaust ports 123 and scavenging ports 124. The dual pistons

111 each have a specially formulated adiabatic cap 121 that preferably comprises a regenerator with cell means such as a micropore structure for absorbing and releasing compressed air and/or pass though liquids and vapors for surface cooling of the piston cap 121 and the preigntion chamber formed by the recessed contour in the cap.

Because the engine embodiment of FIG. 14 is most effectively operable at extremely high pressures, it is primarily suited as a high pressure range component to a compound engine, particularly one integrating a rotary component such as the screw of FIG. 11 or preferably the roto-compressor expander of FIGS. 7 and 13.

One arrangment of this compact engine unit is shown in FIG. 15 which is particularly sized and adapted for use for general applications, where the output shafts can be connected to an appropriate gear box or transmission for separate independent operation. The connection of the reciprocator component 125 above the rotary component ^' 92 is convenient for efficient gas flow, particularly where additional intermediate or auxilliary components are combined to enhance the basic unit. The direct connection connects the compressed air exit port 126 and the combusted gas intake port

127 of the rotary component 92 with the respective intake manifold

128 and exhaust manifold 130 of the reciprocator component 125. A metallic flap valve 95 insures one way passage of compressed gases.

A second arrangement of the compact engine is the front and back positioning shown in FIG. 16. The enlarged rotary component 92 with respect to the reciprocator component 125 is particularly useful in reduced atmosphere conditions or where low pressure turbocharging is restricted.

The basic unit of the compound rotary-reciprocal engine

can as noted include enhancements to enhance efficiency as illustrated in the schematic illustrations of the FIGS. 16-22.

In the schematic of FIG. 17 the reciprocator component

125 has an intervening connection with the rotary component 92.

130 The pressure wave supercharger^ provides additional compression to the air from the rotary component before entry to the reciprocator component and has a tendancy to buffer or smooth pressure pulsing from the periodic positive displacement cycling of both the reciprocal and rotary components. The compression side has intercoolers 96 between the rotary component and the supercharger and the supercharger and the reciprocator component. While the identification fo the reciprocator component is the unit of FIG. 14, including the regenerator liners, the combination is intended to include such engine component without exotic liners or other such engine components disclosed herein with reference to this or the ^* following figures.

Similarly, the rotary component shown is identified as the epichoitroidal type, but described herein, but may also comprise the compound screw compressor-expander of described or other positive displacement rotary compressor expander of the type disclosed.

In the schematic of FIG. 18, the reciprocator component 125 is connected to the rotary component 92 with an intervening intercombustion chamber 131 with a compressed air by-pass circuit 132 with a control valve 133 for regulating supplemental air to the intercombustion chamber 131. A thermal recuperator 140, insure that the added thermal energy to the exhaust gases is recovered in the air-gas supply 134. The fuel supply 135 may also include a preheater 136 to recover waste energy of the exhaust.

In the schematic of FIG. 19, a turbocharger 141 has been added to the thermodynamic cascade of the arrangement of FIG. 18. The turbocharger effectively utilizes the low pressure expansion gases prior to exhaust through recuperator 140, to perform low and

32 compression of the intake air. An intercooler 96 is similarly provided to the compressed air to reduce the volume and temperature added by the compression.

In the schematic of FIG. 20, a Comprex® pressure wave supercharger 130 has been installed between the reciprocator component 125 and the rotary component 92 essentially combining the arrangements of FIG. 17 and FIG. 19 without the intercombustor.

In the schematic of FIG. 21 the intercombuster has been added, which is a bypass circuit 143 allows use of the rotary component or the reciprocator component independent of the other.

In the schematic of FIG. 22 an additional pressure wave supercharger 130 has been installed between the turbocharger 141 and the positive displacement rotary component 92 to boost compression and smooth the pressure pulsing of the rotary component 92. Power for driving the wave guide superchargers 130 are extracted from the combined output drive train of the rotary and reciprocal components whcih both produce positive mechanical work.

Each component in the above described thermo-energetical cascade is designed and constructed for performance with the specific range of its operation. Thus only the reciprocator component is designed to withstand peak pressures. The rotary component and other auxilliary and intermediary components are specifically designed for their respective lower pressure operations.

While in the foregoing embodiments of the present invention have been set forth in considerable detail for the purposes of making a complete disclosure of the invention, it may be apparent to those of skill in the art that numerous changes may be made in such detail without departing from the spirit and principles of the invention.