WO2007125373A1 - Distributive oscillating transmission mechanism and toroidal hermetic engine as its application - Google Patents

Abstract

Transmission mechanism interconnecting bodies coaxially rotating with variable velocity, being called 'Distributive Oscillating Transmission', and piston variable volume machine cooperating with this mechanism, being called 'Toroidal Hermetic Engine'. Distributive Oscillating Transmission consists of frame (10), bodies (1 ,2 ,3 ,4), carrier (6) and planet (5). Bodies are supported on central shaft via cages, each with two discs interconnected via bars appropriately shaped and spaced along discs periphery, so that to support bodies and to allow their required relative motion. Carrier rotates around same axis, bearing a planet, being called 'poly-planet', because it cooperates with gear fixed on frame and bodies via toothing of variable gear ratio, being called 'odonto-knodax' (cam gear) and deployed spirally both on planet and bodies' bars, so that planet cooperates with all bodies simultaneously and continuously, distributing to them required power. Toroidal Hermetic Engine consists of hollow toroidal shell (10), toroidal pistons (1 ,2 ,3, 4) and Distributive Oscillating Transmission. Shell has units equally spaced along its periphery with ports to transfer mass and/or energy, each unit being called 'stathmos' (station), pistons moving within shell form between them consecutively the volumes required by any thermodynamic, hydrodynamic or refrigeration cycle, a kinematic process, being called 'meta-stathmeusis' (re-stationing), is added to this cycle, via which a cycle completed at a 'stathmos' is forwarded to next 'stathmos', while, because each piston has both faces active and number of pistons is equal to number of strokes of complete cycle, the stroke performed at a piston's rear face is performed afterwards at its front face, so that each stroke is always performed between two pistons and all strokes are performed consecutively between any two pistons, an operation being called 'diadocho-kinesis'. Pistons are supported about machine shaft via cages, 'odonto-knodaces' are arranged on their bars, while introducing only carrier and 'poly-planet' all pistons and machine shaft are interconnected. Applications of this machine are pneumatic or hydraulic, motor or pump, refrigeration machines, Stirling engine being of exceptional interest, and internal combustion engine with a clearly smoother and more efficient operation, while case in which carrier is fixed to stationary frame and shell forms drive shaft is of particular interest since residual energy of exhaust gases is used via reaction.

Description

DISTRIBUTIVE OSCILLATING TRANSMISSION MECHANISM AND TOROIDAL HERMETIC ENGINE AS ITS APPLICATION

The invention relates to variable volume machines and their internal kinematic mechanism in general, wherein a variation of a certain volume in said machines is effected exclusively via the motion of an element which is generally called piston and, therefore, this motion is called piston stroke, but often also displacement or sweep, while said machines are referred to in the international documentation as volumetric machines or positive displacement machines.

In particular, these machines may be:

Machines of chemical volume variation which perform a thermodynamic cycle, the chemical energy of an appropriate air-fuel mixture being directly converted, via combustion, to mechanical work during said cycle. Hereafter they will be referred to as internal combustion engines under the substantial agreement that this term will be restricted solely to the particular category of internal combustion engines which are related to the aforementioned notion of piston stroke.

Machines of mechanical volume variation which use fluid pressure, either hydraulic or pneumatic, as an input and produce mechanical work at their output, hence being called either hydraulic motors or pneumatic motors, respectively, or vice versa, hence being called either hydraulic pumps or pneumatic pumps, respectively, under the substantial agreement that these machines are also in this case related to the aforementioned notion of piston stroke.

Machines of thermal volume variation which either use thermal energy derived from external combustion or other heat sources, like the sun, as an input and produce mechanical work at their output, hence being called Stirling engines, or vice versa, i.e. they consume mechanical work at their inlet and perform a refrigeration cycle, hence being called either refrigeration machines or heat pumps, under the substantial agreement that these machines are also in this case related to the aforementioned notion of piston stroke.

The aforementioned variable volume machines are widely used and especially the internal combustion engines constitute the vast majority of mobile energy production units of any kind, both for terrestrial and for marine use. They are also used in stationary energy production units or in mobile energy production units for aerial use, where reaction engines of any kind undoubtedly prevail.

Further on we will focus on internal combustion engines in particular, since any conclusions reached will also refer to and apply in the other categories of variable volume machines, the latter being clearly simpler, both in construction and in operation, when compared to internal combustion engines.

While there have been numerous, important and quite distinct efforts to produce internal combustion engines even since the era when steam engines prevailed - efforts which are distinguished by their broad vision and intelligence, their revolutionary and creative spirit, their persistence and patience - in our days only two types of such engines have finally prevailed, namely the reciprocating piston engines and the Wankel-type rotary engines.

On the one hand, reciprocating piston engines are distinguished for their incomparable reliability, precisely because they use the already established technology of sealing the piston within the cylinder via sealing rings in grooves and in this way they are able to fulfill for a long time the constantly increasing ecological but also economical requirements of low fuel consumption and low pollution exhaust gases. On the other hand, they face problems of kinematic nature, which consist mainly in undesirable oscillations up to vibrations of marginal tolerance level, because the kinematic solution chosen, this being none other than the use of crank and piston rods, allows neither the totally smooth engine operation nor the flexibility of applying any kinematic improving actions on the thermodynamic cycle itself. On the other hand, rotary engines in general, and Wankel engines in particular, are impressive due to their naturally self-evident design, from a kinematic point of view. Indeed, as far as their application is concerned they appear to have an impressively smooth, almost rotary motion, they do however face severe sealing problems and, as a result, they have an uncertain future due to the aforementioned ecological, but also economical trends, or some extremely complex supplementary arrangements have to be applied, before the main engine in order to improve the combustion and after the main engine in order to refine the exhaust gases. These arrangements distort completely the whole philosophy of simplicity and efficiency distinguishing the initial idea behind this engine. Apart from the two very important and well-established engine categories just mentioned, more specific efforts to compose an even more efficient internal combustion engine have been made, said engine being both piston-bearing and rotary. These efforts have led to engines which met no further development and application, some of said engines resembling the present invention merely as to the fact that they also have a toroidal shell and toroidal pistons. These engines appear in documents with the publication numbers:

WO01/81729, WO86/06786, US3990405, US3670705, and GB367234, but are substantially different from the present invention, mainly because they suffer considerably in the following domains:

- sealing, since they have a peripheral slot in their toroidal shell requiring an additional peripheral sealing element for each group of pistons, this meaning that in the presence of four groups of pistons five peripheral sealing elements are required, whereas in the present invention only two peripheral sealing elements are required for four or for any other number of groups of pistons,

- kinematic flexibility, because they have a limited number of piston groups with differentiated motions, usually only two, and, as a result, they are capable of performing only the most basic of the motions required by a thermodynamic cycle, and, most importantly,

- kinematic interconnection of their moving parts, because they use either cams and followers in various versions, or cranks and rods in various versions, or gears in various configurations, with a very poor progressiveness, or other elements and methods, such as push rods and plungers of temporary connection or immobilization, with a considerably poor kinematic operation which may even develop into a prohibitively knocking behaviour.

The challenge that the technical world is faced with nowadays, as long as it is seriously intended that thermal engines of any kind remain dynamically in the foreground, is to design from the very beginning an engine capable, on the one hand, of combining as many virtues as possible, and, on the other hand, of avoiding as many drawbacks as possible from the ones found in the aforementioned categories of engines. Experience up to now has shown that the design of such an engine should be done literally on a completely new basis. It is proven absolutely necessary to apply the sealing technology of piston engines, but it is strongly questioned whether the quest for an optimal way of power transmission, from its point of production via combustion to the engine output, has been properly based. The exceptional kinematic simplicity of the Wankel-type rotary engines appears to set the absolute standards from this point of view, but, unfortunately, it is absolutely bound to the specific function of this engine and cannot be isolated and applied to another type of engine. Therefore, the systematic application of hybridization principles cannot bear fruit in this case, hence it is absolutely necessary that any available technique for the development of innovative ideas be used, the sole guidelines being the application of optimal sealing and the simplicity of power transmission after its production, and the final aim being definitely a piston-bearing but also most probably a rotary engine, far superior to all engines currently in use. Since, however, an intensive research activity worldwide has already started decades ago and still goes on, with the objective of designing such an engine, and since the proven, via other achievements, most competent scientific minds and the proven, via other successful applications, most efficient scientific and technological institutes, take part in this struggle, with overwhelming technical, design, manufacturing and computational means, yet no satisfactory result has been produced, the following question plausibly arises: is it technically possible to design and, even further, to manufacture such an engine ? The present invention gives a definitely affirmative answer to the previous question, said invention constituting the simplest, and at the same time the most effective, proposal with regard to the aforementioned challenge: The Toroidal Hermetic Engine (THE ) , specially built for close and interactive cooperation with the Distributive Oscillating Transmission (DOT) , is an engine which combines in the best possible manner the advantages of the reciprocating piston engine with those of the rotary engine, on the one hand having indeed pistons and on the other hand being purely rotary, while avoiding almost completely most of the problems these two types of engines have.

In general, this engine consists of a shell which is an almost continuous hollow toroid, either stationary or moving in space, and of pistons which are parts of a solid toroid, of appropriate dimensions so as to cooperate with the shell, each of said pistons having two active faces, said pistons moving within the shell with respect both to the shell and to each other, performing a purely rotary motion, so that the shell's internal surface, on the one hand, and the faces of two successive pistons lying opposite each other, on the other hand, form, consecutively and at the proper position, the volume required at each stroke of a thermodynamic cycle, the complex sequence of these motions being effected via a special planetary mechanism comprising only a few members, wherein said mechanism kinematically connects the pistons to the engine drive shaft and either receives torque from the pistons or transmits torque to the pistons.

For a most clear presentation of the engine's structure and operation and in order to explain some of its peculiarities, it is necessary at this point to proceed to the following agreements, on condition that the engine drive shaft moves in one direction:

- each piston has a "front face" and a "rear face", the meaning of these terms being obvious with regard to the piston's direction of motion, said terms having a permanent character,

- we consider the processes taking place in the space between two, any, successive pistons, said pistons being called a "pair of cooperating pistons", wherein a "leading piston" and a "following piston" are distinguished, the meaning of these terms being obvious with regard to the pistons' direction of motion, said distinction being only temporary and valid so long as reference is made to the specific pair of cooperating pistons.

The shell's internal surface in particular is a toroidal surface, i.e. a surface of revolution, the generating line of this surface being any planar, closed and smooth curve lying completely on one side of and at an adequate, for manufacturing and operational purposes, distance from the revolution axis of construction of the toroidal surface, said axis coinciding with the functional central axis of the engine and being called "main axis", the most appropriate generating line being the ellipse, while the simplest curve suggested is the circle. The shell's external surface may be of any form satisfying any manufacturing requirements.

The continuity of this hollow toroid is interrupted only by a peripheral slot which extends on the whole periphery of the shell, in any position of the generating line of the toroidal surface, preferably on its inner side, i.e. the side lying towards the revolution axis of construction of the toroidal surface, or on its outer side, i.e. the side lying towards the opposite direction, and has an axial width determined by mechanical strength requirements, since said peripheral slot is required for the mechanical connection of each piston to a central, different for each piston, hub via an arm.

In addition, the shell has units of an appropriate number, equally spaced along its periphery, each of said units being called a "stathmos" (station) and having at least one "intake" port, at least one device for effecting "ignition" by any means (via spark or via fuel injection at a self-ignition pressure or otherwise) and at least one "exhaust" port, and possibly also other openings and devices (preheating, cooling and others) for improving the performance of a thermodynamic cycle.

The pistons in particular, identical both in structure and in operation, are parts of a toroid, i.e. a solid of revolution, the external limit of said solid's cross-section being derived from the internal limit of the shell's cross-section via an internal offset by a radial gap, necessary for differentiated expansions, due to different materials or different temperatures during the engine operation. The revolution axes of construction of the pistons and the operational axis of rotation of the pistons coincide with the main axis, resulting in that a most hermetic sealing of the pistons with respect to the cooperating shell walls is achieved, via the already established relevant technology of sealing rings in grooves. Besides, the pistons have appropriate angular dimensions, are of an appropriate number and are distributed along the shell periphery in such a manner, that for each pair of cooperating pistons, the rear face of the leading piston and the front face of the following piston form, consecutively and at the appropriate position, the volumes required at each stroke of the thermodynamic cycle, while all strokes are performed simultaneously.

Moreover, the piston faces have any appropriate shape which favors the most effective production of torque with respect to the rotation axis of the pistons, via the pressure generated by the exhaust gases, said piston faces fitting each other perfectly when the complete expulsion of exhaust gases at each operating cycle of the engine is required, wherein the simplest such shape to be used is the plane and particularly the meridian plane.

Furthermore, each piston has a peripheral rib, i.e. a peripheral extension, said extension being practically part of the toroidal shell's ring which was cut out in order to form the peripheral slot, said peripheral rib having naturally an axial thickness corresponding to the one of the cut out ring and being deployed from an angular position between the piston faces, which lies at an adequate, with regard to mechanical strength, angular distance from the piston rear face, towards the piston rear face, extending outside the piston body boundaries towards the following piston, said peripheral rib having an angular width such as, on the one hand, to cover adequately the opening of the peripheral slot when the following piston is at its maximum distance from said piston, and, on the other hand, to allow for the unobstructed relative motion of the two pistons up to the point where they contact each other, thus ensuring the most hermetic sealing of the pistons with the cooperating shell walls in the peripheral direction, via only two peripheral sealing elements, said sealing elements either having a special meander shape or being spring steel elements or elements of special chemical composition or a combination of these, said sealing elements being located on both sides of said peripheral rib, with regard to the axial direction.

The same as described above configuration may, also, alternatively apply from an angular position between the piston faces, which lies at an adequate, with regard to mechanical strength, angular distance from the piston front face, towards the piston front face, extending outside the piston body boundaries towards the leading piston, if it is necessary considering any structural or operational requirements.

Each piston also has an arm fixed on said peripheral rib on the whole of its axial thickness and extending to an adequate, with regard to mechanical strength, angular width, from the edge of the peripheral rib located between the piston faces to the rear or front face position, depending on the peripheral rib deployment, said arm extending, right after its fixing on the peripheral rib, in parallel to the machine central axis and in both directions to an adequate height with regard to the capacity of receiving any non-axial torque, said arm extending from these two edges in two planes perpendicular to the main axis, up to the area around this axis, where two discs having their centers on said axis are formed, thus creating a hub which receives any non-axial torque, allowing only the unobstructed rotation of the piston, and since all pistons are supported on a central shaft, said pistons always having rotational freedom, it follows that the discs are formed at axially different planes and, therefore, although identical, differ in their axial support position, while having, the same axial height. As far as inertia is concerned, in order to achieve the smallest possible moment of inertia but also the smallest possible centrifugal force of each piston, on the one hand a material of appropriate strength and minimum density should be used and on the other hand it is possible to remove a significant quantity of material from the initial part of the solid toroid, internally or externally, to such an extent that the remaining material has the required mechanical strength and at an adequate distance from the faces, in order to allow space for the sealing grooves, but also from the lateral surface at areas where the presence of this surface is not required for the sealing of the "intake" port and the "exhaust" port.

The performance of all the required motions, with precision and progressiveness but also with an absolutely constant engagement, and without any auxiliary mechanisms for accelerating, decelerating or immobilizing the pistons, is achieved via a special Distributive Oscillating Transmission mechanism of a few members, said mechanism being a combination of planetary systems and in particular consisting of: - a sun, which is a gear fixed on the toroidal shell, its axis coinciding with the main axis, said particular sun being called a "shell-sun", - suns, which are machine elements of a special type, each of said suns being fixed on a respective piston, rotating therefore around the main axis, said particular suns being called "piston-suns",

- a carrier, which also rotates around the main axis in a direction which is either the same or the opposite of the pistons' direction of rotation, when viewed in a complete kinematic cycle, and has a support base for a shaft whose axis is located in parallel to and offset from the main axis and is called "planetary axis", said shaft being, therefore, called "planetary shaft", said carrier receiving or transmitting torque, depending on the direction of the required torque, via its connection to the planetary shaft, and

- a combination of planets, one of said planets being a geared wheel, and the rest, whose number is equal to the number of strokes of the kinematic cycle being performed, being machine elements of special type, said planets being fixed to each other, thus forming the aforementioned planetary shaft, said planets rotating, naturally, around the planetary axis and cooperating appropriately with the respective suns, the geared wheel with the shell-sun and each of the other planets with the respective piston-sun, said combination of planets being called a "poly-planet".

Via the relative motion of the carrier with respect to the shell-sun, the poly-planet is moved by the shell-sun, said motion being called "timing motion", at a constant gear ratio, such that, when the carrier executes a complete revolution with respect to any of the piston-suns, the poly-planet executes an integral number of revolutions around the planetary axis. Hence, when the carrier performs a uniform relative motion with respect to the shell-sun, the poly- planet's motion is also uniform, whereas the motion of each piston-sun has to be of variable velocity, and, as a result, the toothing, via which the piston-suns and the respective planets making up the poly-planet cooperate, is of a special construction and more precisely of variable gear ratio. Consequently, reference is not made to cooperating standard geared wheels but to an application of a combination of their design philosophy to the design philosophy of cams, hence each of these special machine elements may be called "odonto-knodax" (cam gear), while with proper care the fluctuation of the gear ratio's variation is kept within allowable limits, and the pressure angle is, naturally, kept within the limits also found in standard toothings. This result may be even further improved by controlling and adjusting the rest of the design parameters of the toothing per se.

In the general case, if the gear ratio's mean value during the operation of the "odonto-knodaces" (cam gears) is not a rational number, this meaning that an integral number of revolutions of one does not correspond to an integral number of revolutions of the other, and it is required that one from these two special machine elements rotates by more than a complete revolution, then, if the toothings are planar, a part of the one toothing will come across a part of the other toothing with which it is not meant to cooperate, this having certainly disastrous effects.

However, even in the case that the gear ratio's mean value is a rational number, said condition taking place in standard gear applications and also being present in this application, this problem is solved within the plane by juxtaposing the same toothing profile repeatedly, the number of repetitions being derived from the aforementioned gear ratio's mean value, this proposal leading, however, to a great restriction of the angular width within which the gear ratio's variation has to be effected, and finally resulting in that this variation is extremely abrupt and the derived toothing is non-functional or even impossible to manufacture.

On the other hand, the "odonto-knodaces" (cam gears) of the poly-planet cooperate with the "odonto- knodaces" (cam gears) of all piston-suns simultaneously and continuously, so that each piston-sun performs a stroke and the same stroke is afterwards performed by the next, i.e. leading, piston-sun, while the first piston-sun performs the next stroke, being in constant engagement with the poly- planet. Consequently, if the toothings are planar, it is most certain that a part of the poly-planet "odonto-knodax" (cam gear) will at some point come across another "odonto-knodax" (cam gear) part belonging to the same or another piston-sun, said parts not being meant to cooperate, this also having disastrous effects. All the aforementioned undesirable circumstances are caused by an overlap of operating periods. In order to face them, the toothings of both the piston-suns and the cooperating planets which make up the poly-planet, are deployed in axially different positions, either gradually in a stepped mode or continuously, i.e. helically, this deployment, in a generalized form, being called an "overlap avoidance helical configuration", the helix having an appropriate slope so that, on the one hand the piston-suns meet no obstacle in their relative motions and, on the other hand, the axial height of said helical configuration, and therefore the total axial height of the mechanism, are not excessively increased. Remark:

The overlap avoidance helical configuration is in no way related to the currently used helical gearing per se or, more precisely, it is an application of the same, but rather inversed, rules of its construction under a more macroscopic view, meaning that, as for each contact point on a tooth an additional turning angle is imposed, dependent on the axial position and aiming at an overlap of operating periods of successive teeth in the currently used helical gearing, in overlap avoidance helical configuration an axial displacement for each tooth is likewise imposed, either once per tooth or in an absolutely continuous manner, aiming, on the contrary, at the avoidance of an overlap of operating periods. If, for reasons of strength and operation of the toothings, the use of helical gearing is also required, there is no problem in the coexistence of these two different types of helical configuration.

As mentioned above, each piston is held in position by its hub, i.e. the combination of the arm and the discs. However, this way no lateral surface is available for the development of the piston-sun's toothing, hence the introduction of new elements is required, said elements being called bars, said bars interconnecting the discs of the piston they are meant for, being equally spaced along the discs periphery and being identical, both within the same piston and between pistons, their sole differentiation being as to their axial support position, since they go together with the discs of each piston. The cross-section of said bars is part of a circle's sector, defined by an inner circle of appropriate radius, so as to encircle the carrier shaft, or other central shaft, at an adequate, for manufacturing and operating purposes, distance, and by an outer circle of appropriate radius, with regard to mechanical strength, while the combination of their number and cross-section is optimal, so that, on the one hand it is adequate as far as the required mechanical strength is concerned, and on the other hand it allows for the unobstructed relative motions of the pistons. After the introduction of the bars it is necessary to make proper openings on all the discs of all the pistons, excluding the most lower and most upper of all these discs, in order to allow unobstructed relative motions of the bars of a cage and the discs of other cages. This combination of discs and bars is called a "cage".

After the aforementioned effective formation of each piston's cage, the required generalized helical toothings are deployed and connected to the sides of the cage bars. It is recommended, although not necessary, that the helices are continuous and of constant pitch, mainly for reasons of mechanical strength. It is, also, recommended, although not necessary as well, that all helices of the same piston-sun are joined, thus forming a single, unified and robust helix, which considerably enhances the total mechanical strength of the cage. In all cases, despite the fact that the cages of all piston-suns are identical apart from their axial position, the respective toothings for the same stroke of all piston-suns are absolutely identical.

Furthermore and since there are no other elements moving with respect to each other on the poly- planet's side, there are no other requirements except that the toothing on the poly-planet's body is deployed in such a manner that each contact point of the poly-planet's toothing corresponds both angularly and axially to the respective contact point of the cooperating piston-suns' toothing.

In case of using a unified helix, each piston-sun appears only as a single helical "odonto-knodax" (cam gear) and the poly-planet as a combination of a geared wheel and a single helical "odonto- knodax" (cam gear), an arrangement which is similar to the one of a classic planetary system. In this last case the poly-planet, also, looks like a drum of old gramophone of cylindrical type, with the difference that on its helical path is recorded the desired variable rotary motion of the cooperating piston-suns, instead of the desired variable almost radial motion of the head of the gramophone which in turn produces the desired sound or music!

The toothings, on the other hand, may be either all external or a combination of external toothings for all the planets and internal toothings for all the suns, the latter arrangement being advantageous from a topological aspect, but not efficient for considerable and abrupt fluctuations of the gear ratio, or a combination of internal toothings for all the planets and external toothings for all the suns, this last arrangement applying only to special cases, since it causes topological problems and is also not efficient for considerable and abrupt fluctuations of the gear ratio.

Finally, the engagement of each piston-sun with the poly-planet is absolutely constant and when the cooperation of the helical toothings is terminated at one of their two ends, a new cooperation has already started at their other end, with a degree of overlap exactly the same as the toothing's degree of overlap between teeth. It is in fact possible to improve the degree of overlap further, in order to achieve an even smoother and more quiet operation, by applying the currently used helical gearing, and in any case without any mechanism of immobilization or temporary connection. As shown by the detailed presentation of this combination of planetary systems, due to its distributive structure and operation, the new moving parts which have to be introduced to the group of already existing moving parts are only two, the carrier and the poly-planet! As previously, for a most clear presentation of the engine's structure and operation and in order to explain some of its peculiarities, it is necessary at this point to proceed once more to the following agreements, on condition that the engine drive shaft moves in one direction:

- one of the "stathmoi" (stations) will be called the "first stathmos (station)", so that the previous "stathmos" (station) is automatically defined, the meaning of this term being obvious with regard to the drive shaft's direction of rotation, said "stathmos" being called the "last stathmos (station)", this designation being permanent but having no objective basis, since all the "stathmoi" (stations) are identical and equivalent, and

- after all processes have been completed at one "stathmos" (station), the same processes are considered at another "stathmos" (station), which is called the "next stathmos (station)", the meaning of this term being obvious with regard to the drive shaft's direction of rotation, this designation being only temporary and valid so long as reference is made to any two successive "stathmoi" (stations).

This engine is capable of performing any thermodynamic cycle, performing all the required motions with precision and progressiveness, and consequently with the greatest efficiency possible, i.e. it is capable of performing extremely specialized motions of an ideal thermodynamic cycle, such as:

- differentiated angular displacements per each stroke of the thermodynamic cycle, so that the rear face of the leading piston and the front face of the following piston are, consecutively, in surface contact at the beginning of the "induction" stroke, aiming at the intake solely of air-fuel mixture, at some, predetermined by the intended compression ratio, angular distance at the end of the "compression" stroke, at another predetermined angular distance at the end of the "power" stroke, in practice much greater than that of the "induction" stroke and dependent on the requirement of complete or optimal exploitation of the exhaust gas energy, and in surface contact again at the end of the "exhaust" stroke, aiming at the complete expulsion of the produced exhaust gases.

- an additional kinematic process, which is called "meta-stathmeusis" (re-stationing) and via which the purely thermodynamic cycle is repeated again at the next "stathmos" (station). As the "stathmoi" (stations) are located at equal intervals, the complete process, which is called a "complete kinematic cycle", i.e. the purely thermodynamic cycle and the "meta-stathmeusis" (re-stationing) process, may be repeated ad infinitum. It is also possible to impose the incorporation of a parting of the cooperating pistons in the "meta-stathmeusis" (re-stationing) process, at an opening on the shell which lies between the exhaust port of one "stathmos" (station) and the intake port of the next "stathmos" (station), resulting in the most effective cooling and/or cleaning, even via brushes, of the working faces, but also allowing maintenance work, such as the replacement of a spark plug, if said spark plug is located on a piston, without there being need for engine dismantling, which is potentially unsafe and certainly time consuming and costly. The "meta-stathmeusis" (re-stationing) process may either constitute on its own one or more strokes or be incorporated in the already existing strokes, and it is proven extremely useful as it allows for a considerable time interval between the thermodynamically active strokes, so that the stressed materials have a sort of rest and are relieved of critical thermal stresses, and the metallic, ceramic and other natural and synthetic materials are structurally restored. This facilitates cooling, even via air, but also allows for heavier stress on these materials, at higher levels of torque production or higher operating speed.

At this point it should be stressed that the number of pistons is equal to the number of strokes of the complete kinematic cycle, a matter on which no explicit reference had been made before, since a number of crucial questions had to be examined thoroughly prior to this designation, such as which are the required processes for the optimal execution of any operating cycle, how it is possible for all these processes to constitute a unified and unobstructedly repeated operation, and, finally, in which way it is possible to redistribute said processes so that a number of strokes is derived, which allows for the optimal design and manufacture of such an engine.

The "intake" ports, any other required openings and the "exhaust" ports of each "stathmos" (station) are covered, also by lateral sealing, and uncovered, depending on the relevant requirements, solely via the pistons' motion, without there being need for the presence of other elements, resulting in the drastic reduction of the number of moving parts to a minimum. Since the position where the ignition takes place is specific and fixed on the shell, if it is required, an electric circuit is activated on each "stathmos" (station), solely via the pistons' motion as well, without there being need for the presence of other elements, such as the classic electric distributor in other engines, resulting also in the reduction of the number of moving parts to a minimum.

All the piston motions are designed based on an ideal thermodynamic cycle, taking into account all the contact forces and inertial forces, so that both the acceleration and the deceleration of each piston are performed optimally, while it is possible to achieve the oscillating intake of the air-fuel mixture for improved mixing, and its in-motion combustion for an improved combustion, since the placement of the spark plug or of the injection nozzle either on the leading piston or on the following piston and the resulting differentiation of the flame propagation rate inside a compressed air-fuel mixture, said mixture also being subject to the favorable effect of inertial forces, are only a matter of choice. Parallel to the aforementioned pistons' motions, due to the fact that each piston has two active faces and consequently participates in two successive pairs of cooperating pistons, furthermore the other pairs of cooperating pistons also perform consecutively the same motions with the appropriate phase difference, while the whole process is called "diadocho-kinesis " operation and can be repeated ad infinitum.

In the more simplified version of the engine, the shell is stationary in space and the engine output, i.e. the shaft which produces work and is therefore called "drive shaft", is the planetary system carrier, while the introduction of air-fuel mixture and the gas exhaust is achieved by stationary piping fixed on the shell.

In the more advanced version of the engine, the planetary system carrier is stationary in space and the drive shaft is now the shell, while the introduction of air-fuel mixture is effected from the external space on the moving shell via piping and rotary type sealing and the gas exhaust is effected via a specially configured stationary exhaust gas collector. Among the advantages of this arrangement are the even smoother engine operation, but also the drawing off of any residual exhaust gas energy via their aerodynamic reaction on the appropriately curved walls of the exhaust gas collector, said reaction leading to an additional torque on the moving shell.

Application example:

For a most intelligible explanation of the engine's structure and operation, it is deemed necessary to present an application of a gas engine either with a carburetor or with direct or indirect fuel injection, the complete kinematic cycle in said application consisting of four strokes, which are:

Stroke 1: Meta-Stathmeusis (Re-Stationing) - Induction,

Stroke 2: Compression,

Stroke 3: Power, and

Stroke 4: Exhaust.

We assign to the number of strokes of the complete kinematic cycle an equal number of pistons.

We also select the following configuration parameters:

Static parameters: Number of "stathmoi" (stations): three,

Torus cross-section: circle,

Peripheral slot position: inner side,

Piston face: meridian plane,

Sealing rib direction: towards following piston, Type of ignition unit: spark plug,

Position of ignition unit: center of piston's rear face,

Number of bars per piston: three,

Type of sun toothings: external,

Type of planet toothings: external, Piston-sun toothing helix: unified and of constant pitch, and

Poly-planet toothing helix: unified and of variable pitch. Kinematic parameters:

Drive shaft: shell,

Number of revolutions of the poly-planet per stroke: one, and Drive shaft to poly-planet ratio of angular velocities: two to three.

These selections lead to the following numbers of helix turns and numbers of revolutions for performing a complete kinematic cycle at all "stathmoi" (stations):

Poly-planet (fixed center of rotation): helix of four turns and twelve revolutions around the planetary axis

[the number of strokes multiplied by the number of "stathmoi" (stations)],

Piston-sun: helix of three turns and nine revolutions around the main axis, and

Drive shaft: eight revolutions around the main axis.

Due to these selections, a balanced arrangement is achieved between the ratio of the air-fuel mixture induction volume per drive shaft revolution to the total torus volume and the ratio of the exhaust gas expansion volume per drive shaft revolution to the total torus volume on the one hand, and the minimum root width at the most highly loaded point of the "odonto-knodaces" (cam gears), the pressure angle value and, therefore, the toothing efficiency on the other hand. As already mentioned, since the gear ratio mean value is a rational number and in this particular application is equal to three fourths, there is an alternative solution in using repeatedly, covering the whole periphery in both cases, three identical parts of the one "odonto-knodax" (cam gear) on the same plane, and four identical parts of the other "odonto-knodax" (cam gear) on the same plane, too. Consequently, the worst case is when the space within which all the variations of the gear ratio are required to take place is restricted to only one fourth of the periphery.

However, applying the solution of the helical toothing, the space of the one "odonto-knodax" (cam gear) expands to four times the periphery, but now the worst case is when the space within which all the variations of the gear ratio are required to take place has expanded to three times the periphery. Therefore, there has been an improvement by a factor of four multiplied by three, i.e. twelve! This is a good example with figures, showing how the numerical data correlate to the integers which make up the reduced fraction of the gear ratio mean value, a question which could not be explained in a satisfactory manner outside the context of a specific application.

The least favourable position in the complete kinematic cycle, with regard to the variation rate of the gear ratio, is the one where the insertion of the process of parting of the pistons, for cooling and cleaning before the fuel intake, takes place. By using the suggested helical toothing, the worst value of the pressure angle differs from the pressure angle of the standard toothing only about five degrees, while the involute tooth system is used and no other intervention in the rest of the toothing parameters is made. On the other hand, the respective pressure angle in the planar solution diverges by more than seventy degrees and makes it impossible to manufacture the toothing, degrading it to the extremely rare case of a toothing with a ... neutral point!

Thus, apart from the fact that the helical toothing solves the very difficult problem of the simultaneous and continuous cooperation of the poly-planet with all the piston-suns, it also has excellent results in many other applications of motion transmission, by achieving a considerable expansion of the angular spaces within which specific variations of the gear ratio have to be effected.

The engine which corresponds to the aforementioned manufacturing parameters is shown in the attached figures:

In FIGURE 1 the engine is shown in a perspective side view.

In FIGURE 2 the engine is shown in a perspective inclined top-side view, where the base (stationary frame) and the shell of the engine are translucent so that the poly-planet and the pistons without their arms are partially shown. In FIGURE 3 the engine is shown in a perspective inclined bottom-side view, being also called "frog's view", where the base and the shell of the engine are cut so that the poly-planet and the pistons without the lower half of their arms are shown. In FIGURE 4 the engine is shown in an axonometric inclined top-side exploded view, whereby the moving parts it consists of are shown in more detail, while the symbols have the following meaning: 10 - toroidal shell support external body - drive shaft

4 - piston number 4 3 - piston number 3

2 - piston number 2 1 - piston number 1

5 - poly-planet

6 - base - stationary frame

In FIGURE 5 the engine is shown in a top view showing, also, the dividing lines for the cross-section A-AOf the FIGURE 7.

In FIGURE 6 the engine is shown in a side view showing, also, the dividing lines for the cross-section B-B' of the FIGURE 8.

In FIGURE 7 an engine cross-section along line A-A' of FIGURE 5 is shown, said cross-section being of capital importance for the understanding of the engine's structure, while the symbols have the following meaning: upper line:

43 - exhaust gas collector outlet

31 - gas exhaust lateral sealing surface (of any piston) 30 - fuel intake lateral sealing surface (of any piston) 38 - fuel intake port [of any "stathmos" (station)] 33 - poly-planet "odonto-knodax" (cam gear) helical toothing

19 - upper "horizontal" (deployed in the plane of motion) part of piston arm (of any piston)

20 - upper disc of piston arm and upper disc of piston cage (coincidence) (of any piston)

21 - opening of upper disc of piston arm and of upper disc of piston cage (of any piston)

14 - drive shaft (shell) output coupling configuration 42 - fuel supply configuration with rotary type sealing

27 - cage bar side view (of any piston - here of piston number 3)

32 - piston-sun "odonto-knodax" (cam gear) helical toothing (of any piston)

50 - gap (opening) between "stathmoi" (stations) for cooling-cleaning and inspection-maintenance [(for any "stathmoi" (stations)] 9 - toroidal shell

44 - toroidal shell cooling fin [of any "stathmos" (station)] 8 - exhaust gas collector

45 - exhaust gas collector cooling fin lower line: 16 - piston body (of any piston)

17 - shell sealing peripheral rib with meander configuration (of any piston)

18 - "vertical" (axially deployed) support of piston arm (of any piston)

24 - lower "horizontal" (deployed in the plane of motion) part of piston arm (of any piston)

34 - poly-planet gear 5 - poly-planet

22 - lower disc of piston cage (of any piston)

7 - poly-planet carrier fixed on the base (stationary frame) 10 - toroidal shell support external body - drive shaft

6 - base - stationary frame 41 - central fuel supply

23 - opening of lower disc of piston cage (of any piston)

35 - drive shaft (shell) gear

25 - lower disc of piston arm (of any piston)

26 - counterweight for piston static-dynamic balancing, having the shape of a circle's sector (of any piston)

15 - base (stationary frame) fixation leg

46 - support groove for spark plug electric current supply contacts

In FIGURE 7 is shown, also, that in this application example lower disc of piston cage (22) and lower disc of piston arm (25) cannot be connected together since they lay in topological^ separated, by the carrier and the poly-planet, places, but in other embodiments there is no such a structural problem. In FIGURE 8 an engine cross-section along line B-B' of FIGURE 6 is shown, said cross-section being also very important for the understanding of the engine's structure, while the symbols have the following meaning: left column: 13 - "stathmos" (station) number 13 2 - piston number 2 17 - peripheral rib for sealing of toroidal shell (of any piston)

27 - piston cage bar (of any piston)

48 - electric current collecting brush (on the piston) for the spark plug (of any piston) 15 - base (stationary frame) fixation leg

5 - poly-planet

1 - piston number 1

23 - opening of lower disc of piston cage (of any piston) 32 - piston-sun "odonto-knodax" (cam gear) helical toothing (of any piston) 11 - "stathmos" (station) number 11

47 - electric contact for supplying current to the brush for the spark plug [of any "stathmos" (station)] 37 - toroidal shell internal surface right column:

49 - spark plug on the piston (any piston) 29 - piston rear face (of any piston)

38* - fuel intake port (appears on this cross-section for the purpose of explaining the operation of the engine)

50 - gap (opening) between "stathmoi" (stations) for cooling-cleaning and inspection-maintenance [(for any "stathmoi" (stations)] 39 - gas exhaust port [of any "stathmos" (station)]

40 - nozzle configuration at the end of the gas exhaust port [of any "stathmos" (station)] 36 - peripheral slot of toroidal shell 45 - exhaust gas collector cooling fin

8 - exhaust gas collector 3 - piston number 3

12 - "stathmos" (station) number 12 4 - piston number 4

28 - piston front face (of any piston) In FIGURE 9 the engine operation is shown, using a top view of a special cross-section, at the level of the cross-section B-B' of FIGURE 6, intersecting the base (stationary frame), the toroidal shell and only the upper horizontal parts of the piston arms, the successive positions of the toroidal shell, all the pistons and the poly-planet hence being presented in seven phases during the engine operation. In FIGURE 10 the engine operation, also, is shown, using an inclined top-side view of the same as above cross-section where, however, only piston number 1 appears, so that the successive positions of the poly-planet and the cooperating piston-sun are presented in seven phases during the engine operation. It should be noted here that the disposition of the fuel intake port and the gas exhaust port at different angular positions on the toroidal shell cross-section has been selected, so that their sealing may be treated differently, using different materials with different requirements in mechanical, thermal and chemical resistance, since the lateral sealing surfaces of the fuel intake port are never in contact with burning air-fuel mixture or with exhaust gas and the lateral sealing surfaces of the gas exhaust port are never in contact with air-fuel mixture. It should therefore be noted that the fuel intake port, which appears correctly in FIGURE 7 only, also appears in FIGURE 8 and the series of cross-sections of FIGURE 9 and FIGURE 10, for the purpose of explaining the operation of the engine.

With regard to the aforementioned series of sections and in order to examine a complete operating cycle of the engine thoroughly, we consider that the engine drive shaft rotates in the conventionally forward direction in mathematics, i.e. anti-clockwise, hence we assign numbers to the "stathmoi"

(stations) in the conventionally forward direction in mathematics as well. Consequently, after examining the processes at "stathmos" (station) (11) we proceed to examine the same processes at the next "stathmos" (station) (12) and so on, while we assign numbers to the pistons in the conventionally opposite direction in mathematics, hence in the pair of cooperating pistons (1) and (2) the leading piston (1) and the following piston (2) are distinguished, and so on. Therefore, the cycle, conventionally as well, starts with the leading piston (1) and the following piston (2) being in contact and moving at the same velocity as the shell (9), hence remaining stationary with respect to it, so that the rear face (29) of piston (1) and the front face (28) of piston (2) are located at the end of the gas exhaust port (39) of the last "stathmos" (station) (13) (FIGURE 9 - phase A),

From this point they move being constantly in contact up to the point where the front face (28) of piston (2) achieves an adequate sealing of said gas exhaust port (39), then the velocities of said pistons change so that the rear face (29) of piston (1) is separated from the front face (28) of piston (2), until a considerable gap is formed between them, located at an opening of equivalent dimensions on the shell (50), adequate for the purpose of effectively cooling and/or cleaning, even via brushes, of the pistons during engine operation, or for inspection and maintenance work, such as the replacement of the spark plug, without dismantling parts of the engine, during engine switch-off (FIGURE 9 - phase B). Thereafter the velocities of said pistons change again so that the front face (28) of piston (2) approaches the rear face (29) of piston (1) until they come in contact again at a position where the rear face (29) of piston (1 ) still continues to achieve an adequate sealing of the fuel intake port (38) of the next "stathmos" (station), i.e. of the first "stathmos" (station) (11), and from this point they move being constantly in contact until the rear face (29) of piston (1) and the front face (28) of piston (2) reach the beginning of said fuel intake port (38) (FIGURE 9 - phase C).

At this point the following piston (2) moves at the same velocity as the shell (9), hence remaining stationary with respect to it, while the leading piston (1) moves faster until its rear face (29) reaches the end of the induction of the first "stathmos" (station) (11), drawing in solely air-fuel mixture, while towards the end of this motion the following piston (2) also moves slightly with respect to the shell (9), until its front face (28) reaches the end of said fuel intake port (38) and this effects the blockage of it, the "Meta-Stathmeusis (Re-Stationing) - Induction" stroke having been completed at this point (FIGURE 9 - phase D). At this point the leading piston (1) moves at almost the same velocity as the shell (9), hence remaining almost stationary with respect to it, while the following piston (2) moves significantly faster until its front face (28) reaches the end of the compression of the first "stathmos" (station) (11), said compression end being spaced from the induction end by an angular distance which is determined by the specified compression ratio, the "Compression" stroke having been completed at this point (FIGURE 9 - phase E).

At this point the following piston (2) moves at the same velocity as the shell (9), hence remaining stationary with respect to it, while the leading piston (1) moves slightly faster so as to clear itself of the point of locally maximum proximity of the pistons, said point constituting for said kinematic mechanism the so-called "neutral point", which is always present in any mechanical oscillating system. At the proper moment the ignition process is activated, resulting in that the leading piston (1) moves following an optimal kinematic and dynamic design, under the pressure exerted by the exhaust gases, until its rear face (29) reaches the beginning of the gas exhaust port (39) of the first "stathmos" (station) (11), while the following piston (2) also moves, more slowly of course, following a different, but optimal as well, kinematic and dynamic design, said design having taken into account the inertial contribution of the violent motion of the air-fuel mixture's burning mass to the flame propagation. As a result, the combustion is kept almost isovolumic for the time period imposed by the theory of combustion, consequently the air-fuel mixture's chemical energy is turned into mechanical energy on the drive shaft by the applied kinematic mechanism in the most effective possible manner and the "Power" stroke having been completed at this point (FIGURE 9 - phase F).

At this point the leading piston (1) moves until its rear face (29) reaches the end of the gas exhaust port (39) of the first "stathmos" (station) (11), while the following piston (2) moves at a considerably higher velocity until its front face (28) also reaches the end of the gas exhaust port (39) of the first "stathmos" (station) (11). As a result, said faces of said pistons come in contact again, fully expelling the produced exhaust gases, which are led through the gas exhaust port (39), said port ending in the form of an inclined nozzle (40) on the shell's (9) outer side, to the appropriately curved walls of the exhaust gas collector (8), said collector extending to an angular width which is equal to the sum of the two thirds of the periphery and the angular width of the exhaust gas port (39), the shell (9) being thereby also driven by reaction in its direction of motion and the "Exhaust" stroke having been completed at this point (FIGURE 9 - phase G). On the other hand, the parallel operation of the kinematic mechanism which is, practically, exclusively responsible for producing the motions just described, i.e. the operation of the Distributive Oscillating Transmission, under the agreement that by the term poly-planet only the helical toothing of this "odonto-knodax" (cam gear) is here meant, that is (33) instead of (5), and by the term piston-sun only the helical toothing of this "odonto-knodax" (cam gear) is here meant, that is (32) instead of (1) or (2) or (3) or (4), is as follows:

Each piston-sun (32) has a single helix of three complete turns. The poly-planet (33) has a single helix of four complete turns.

Consequently, there are four single helices on the piston-suns' (32) side with twelve complete turns in total, while on the poly-planet's (33) side there is only one single helix with four complete turns, hence the toothing of the poly-planet (33) cooperates simultaneously with four toothings, one per piston-sun (32), and, due to the fact that for a complete kinematic cycle to be performed at all "stathmoi" (stations) the poly-planet (33) executes twelve complete turns, it follows that it cooperates with the toothings of all piston-suns (32) exactly once.

During each complete revolution about its axis the poly-planet (33) will move a piston-sun (32) within one stroke and afterwards the exact same part of the single toothing of the poly-planet (33) will be in the proper position to move the next, that is the leading, piston-sun (32) (FIGURE 10 - phase D, FIGURE 10 - phase E, FIGURE 10 - phase F and, after completion of a full operating cycle at one "stathmos" (station) and return to the first piston-sun, FIGURE 10 - phase G), while the next part of the single toothing of the poly-planet (33) will move the first piston-sun (32) within the next stroke, being continuously engaged to it (all the phases of FIGURE 10), and so on.

Therefore, the engagement of each piston-sun (32) with the poly-planet (33) is absolutely constant and when the cooperation of the helical toothings is terminated at one of their two ends, a new cooperation has already started at their other end, with a degree of overlap exactly the same as the toothing's degree of overlap between teeth (FIGURE 10 - phase A and FIGURE 10 - phase G).

Wherever the relative immobilization or near immobilization of the piston (1, 2, 3, 4) with respect to the shell (9) is required, that is for the following piston (2) during the "Meta-Stathmeusis (Re- Stationing) - Induction" stroke and the "Power" stroke and for the leading piston (1) during the "Compression" stroke and the "Exhaust" stroke, the poly-planet (33) simply rotates the respective piston-sun (32) at exactly or almost the same velocity as the one of the shell (9), respectively, without there being need for the presence of any mechanism, either for immobilization or for temporary connection.

It is thereby proven that the Distributive Oscillating Transmission has the virtues of a constant and self-contained engagement, i.e. the simplicity of operation, the precision and the progressiveness, and allows the design of the engine without limitations, the highest priority being in the satisfaction of the requirements of any thermodynamic cycle per se, from the roughest up to the finest of them. This way a full operating cycle of the engine is completed, which may be repeated in an identical manner at the second "stathmos" (station) (12) (in FIGURE 9 - phase G and FIGURE 10 - phase G the positions of all moving parts are exactly the same as in FIGURE 9 - phase A and FIGURE 10 - phase A, the only exception being that the shell has advanced by one third of the periphery and, consequently, the new "stathmos" (station) to be examined is now "stathmos" (station) number 12, while after two more repetitions of exactly the same cycle, all moving parts will return precisely to their initial positions), and so on.

By observing the positions and the motions of the examined pair of cooperating pistons, it is possible to observe the positions and the motions of all other pairs of cooperating pistons as well, these being repeated consecutively with the relative phase difference, and hence it is possible to follow and fully check the aforementioned "diadocho-kinesis" operation.

Finally, in FIGURE 11 and FIGURE 12 appear two more embodiments of the same central idea as in the application example above, with better topological^ configuration, and more specifically: In FIGURE 11 appears an almost identical with the described in the application example engine, with the difference of using internal toothing for the "odonto-knodaces" (cam gears) of all piston-suns, instead of external one, where, naturally, the rotation of piston-suns and the rotation of poly-planet have the same direction and therefore the corresponding toothings have the same direction of helical deployment.

In FIGURE 12 appears a similar, but not to the same degree as the embodiment of the FIGURE 11 , to the described in the application example engine, with the difference of using the outer side of the toroidal shell for the peripheral slot, instead of the inner one, so the slots for intake and exhaust are in the inner side of the toroidal shell, and all the "odonto-knodaces" (cam gears) are completely outside of the toroidal shell and so the poly-planet, which is sketched in an arbitrary radially reduced scale, lays also outside of the toroidal shell and outside of the cages of the pistons, and is accessible for use as the main drive shaft of the engine, since its carrier is stationary in this engine version. In FIGURE 12 also appears the axis C-C which, with the axis of poly-planet, defines the plane of a side cross-section, so that at left of it a section of the engine at the phase of intake is shown, while at right of it a section of the engine at the phase of exhaust is shown, giving clearer presentation of the corresponding slots deployment and shaping, which are different from these of the aforementioned application example engine. Moreover, after the detailed presentation of the engine's structure and operation, it is rendered clear that the internal combustion engine in question has more features than any other similar suggestion, so that it may claim the title of the sought connecting link between the classic piston-bearing reciprocating engines and the turbine engines, combining some of the advantages of these two categories of engines in the best possible manner, without incorporating their most critical drawbacks at the same time.

As mentioned above, the Distributive Oscillating Transmission is capable of performing any kinematic cycle, performing all the required motions with precision, progressiveness and the greatest efficiency possible in both directions that is either receiving or transmitting torque. Consequently, it can satisfy any thermodynamic or hydrodynamic requirements or a combination of those, and it is capable of performing any cycle, either thermodynamic or hydrodynamic or refrigeration cycle, with the greatest total efficiency possible, hence being the most appropriate kinematic mechanism for the other categories of variable volume machines as well. Therefore, the machine of mechanical volume variation has a structure and operation similar to those previously mentioned, said machine in general also consisting of a shell, which is an almost continuous hollow toroid, has a peripheral slot and some openings, and is either stationary or moving in space, and of pistons, which are parts of a solid toroid, with dimensions corresponding to the ones of the shell, said pistons moving within the shell both with respect to it and with respect to each other, in a purely rotary motion, said pistons being kinematically interconnected via the combination of planetary systems which make up the Distributive Oscillating Transmission. Things are simpler in this particular case, both with regard to manufacture and with regard to operation, because fewer differentiated motions are required, since the total of strokes may be just trie "influx" stroke and the "efflux" stroke, while the "meta-stathmeusis" (re-stationing) process may either constitute on its own one or more strokes or be incorporated in the already existing strokes via an appropriate kinematic design, and, finally, because only the "inlet" port and the "outlet" port, fewer pistons and fewer "stathmoi" (stations) are required.

Besides, the machine of thermal volume variation also has a structure and operation similar to those previously mentioned, said machine in general also consisting of a shell, which is an almost continuous hollow toroid, has a peripheral slot, and is either stationary or moving in space, and of pistons, which are parts of a solid toroid, with dimensions corresponding to the ones of the shell, said pistons moving within the shell both with respect to it and with respect to each other, in a purely rotary motion, said pistons being kinematically interconnected via the combination of planetary systems which make up the Distributive Oscillating Transmission.

Things are even simpler in this particular case, both with regard to manufacture and with regard to operation, because fewer differentiated motions are required, since the total of strokes may be just the "compression" stroke and the "expansion" stroke, while the "meta-stathmeusis" (re-stationing) process may either constitute on its own one or more strokes or be incorporated in the already existing strokes via an appropriate kinematic design, and, finally, because only the "low temperature" area and the "high temperature" area, fewer pistons and fewer "stathmoi" (stations) are required. Remark:

The reciprocating internal combustion engine currently in use, in its four-stroke and four-cylinder version, so that each stroke is performed by a piston at all times, and one piston performs the "Power" stroke and receives the driving pressure of the exhaust gases also at all times, must have one piston, one piston rod, one fuel intake valve and one gas exhaust valve per cylinder, i.e. sixteen moving parts so far, one crankshaft, and, because a different operating frequency is required, one camshaft, different from the crankshaft, so a total of eighteen moving parts. The Wankel-type rotary internal combustion engine currently in use must have one rotor / multi- piston and one shaft, that is only two moving parts.

The piston-bearing rotary internal combustion engine now being suggested must have four pistons, one poly-planet and one carrier, that is six moving parts, a number which happens to be the geometrical mean of the numbers of moving parts of the aforementioned two engines which are currently in use!

Advantages in comparison with piston-bearing reciprocating engines:

The complete absence both of "intake" valves and of "exhaust" valves, since the pistons themselves, through their motion, cover or reveal the respective ports, resulting in the drastic reduction of the number of required moving parts. The fact that these ports are covered via lateral sealing is perfectly acceptable both with regard to manufacture and with regard to operation, since the existing pressures at these positions are kept at practically low levels. The possibility of treating the sealing of the fuel intake port and the gas exhaust port differently, owing to their disposition at different angular positions on the toroidal shell cross-section, via the use of different materials with different requirements in mechanical, thermal and chemical resistance, since the lateral sealing surfaces of the fuel intake port are never in contact with burning air-fuel mixture or with exhaust gas and the lateral sealing surfaces of the gas exhaust port are never in contact with air-fuel mixture.

The absence, as well, of any additional mechanism of electric current distribution, since, as the area where the ignition, if necessary, takes place is specific and fixed on the shell, an electric circuit is activated at the proper moment on each "stathmos" (station) or on the piston itself when the spark plug is located thereon, via the motion of the pistons alone, without there being need for the presence of other parts, this resulting, also, in the reduction of the number of required moving parts.

Advantages in comparison with Wankel-type rotary engines: The existence of an effective surface for converting the total pressure exerted by the exhaust gases on the piston's face into a force on the piston.

The existence of an effective lever arm for converting the total force applied by the exhaust gases on the piston into a torque around the main axis.

The achievement of sealing of optimal quality during the formation of the required volume, especially during the "Power" stroke, when pressures and temperatures of critically high levels are noted. Said quality approaches the quality of the respective piston sealing inside a cylinder via sealing rings in grooves, being slightly inferior, since a slight distortion of the cooperating parts takes place during the transformation from the geometrical shape of the cylinder to the one of the torus.

Advantages in comparison with other piston-bearing rotary engines:

The achievement of a perfectly adequate sealing of the shell's peripheral slot, which is necessary for the mechanical connection of each piston to a central hub, via the peripheral rib of each leading piston, using only two peripheral sealing elements, said sealing elements either having a special meander shape or being spring steel elements or elements of special chemical composition or a combination of these, said sealing elements being located on both sides of said peripheral rib, with regard to the axial direction. The achievement of the smoothest possible operation of the engine, via an arrangement where the number of pistons is equal to the number of strokes of the aforementioned complete kinematic cycle, so that, at all times, the rear face of some piston performs the "Power" stroke and receives the driving pressure of the exhaust gases.

Advantages in comparison with all other machines of chemical volume variation:

An application of maximum simplicity in design, which leads to an unrivalled effectiveness (from this point of view, only the initial idea for the Wankel-type rotary engine is superior to the present proposal, but the embodiment of this initial idea is rather inferior, because of the many problems arising in its application).

The possibility of burning a fuel of very low volatility, since, after each combustion process, and during the engine operation, an adequate gap is formed between the pistons, located at an opening of equivalent dimensions on the shell, the cleaning of the piston faces being effected through said gap, either via air or even via brushes.

The possibility of performing either inspection or even maintenance work, such as the replacement of the spark plug, if said spark plug is located on the piston, without there being need for a difficult, time consuming, costly and even unsafe dismantling of the engine.

Performance of any operating cycle with regard to thermodynamics and kinematics, since it is possible to differentiate the angular displacements of the pistons in each stroke during the design phase, and hence it is possible to perform any improving actions within any thermodynamic cycle, for a better combustion or a more efficient exploitation of the exhaust gases' energy.

Performance of a specific thermodynamic cycle, during which the engine may start with the drawing- in of pure air-fuel mixture, continue with its compression up to a predetermined compression ratio, go on with the expansion of the burning air-fuel mixture producing an angular displacement of the leading piston required for the almost complete exploitation of the exhaust gases' energy, and finish with the complete expulsion of the exhaust gases, said cycle being capable of repetition in an identical manner ad infinitum.

Having accomplished the complete expulsion of the exhaust gases, if desired, which is practically more difficult, it is also possible to achieve the partial expulsion of the exhaust gases, either for the purpose of their complete recombustion or for performing any other improvement process, such as homogeneous charge compression ignition.

The possibility, with minimal limitations, of achieving either a practically isovolumic combustion ^v according to the requirements of the Otto cycle or a practically isobaric combustion according to the requirements of the Diesel cycle, or any other intermediate state.

The possibility of preparing the air-fuel mixture by preheating before or during its introduction, since there is an ample, directly accessible and available for heating lateral surface of the shell, different from the combustion area.

The possibility, as well, of preparing the air-fuel mixture, by its in-motion or oscillating intake and the resulting improved mixing, via the design that takes into account the layers or the turbulences created or simply favoured by inertial forces.

The possibility of in-motion combustion of the air-fuel mixture for its improvement, when the placement of the spark plug or of the injection nozzle either on the leading piston or on the following piston has been selected, since a differentiation of the flame propagation rate inside a compressed air-fuel mixture is achieved, said mixture being subject to the favorable effect of inertial forces due to its violent motion.

The possibility of cooling the combustion area via air, since there is also an ample, directly accessible and available for cooling lateral surface of the shell, other than the area of induction, but, to a great extent, also due to the "meta-stathmeusis" (re-stationing) process, and even more if the insertion of the parting motion of the pistons, for cooling and cleaning, takes place. The achievement of a further improvement in the smoothness of the engine operation in the case where the shell is the drive shaft, since the ratio of the minimum to the maximum angular velocity of the part moving more slowly is considerably improved. The possibility of further improvement of the total efficiency of the engine by the drawing off even of the residual exhaust gas energy in the case where the shell constitutes the drive shaft, the exhaust gases being led through the exhaust port, which terminates in the form of an inclined nozzle on the outer side of the shell, towards the appropriately curved walls of the exhaust gas collector, the shell thus being driven also by reaction in its direction of motion.

Advantages in comparison with other machines of mechanical and thermal volume variation:

The achievement of unique simplicity in operation, both of machines of mechanical volume variation and of machines of thermal volume variation, with an excellent sealing and a minimal number of moving parts. Moreover, several of the aforementioned advantages relate clearly to the machines of mechanical volume variation and the machines of thermal volume variation of the present proposal as well, in comparison with the respective machines being currently in use.

The possibility of disposing the low temperature area and the high temperature area in machines of thermal volume variation at any interval required by the design of such machines, due to the insertion of the "meta-stathmeusis" (re-stationing) process, so that, on the one hand an excellent thermal insulation in the simplest manner is achieved, and on the other hand the refrigeration cycle per se may be optimized, resulting in the feasibility of the design and manufacture of a most efficient machine of thermal volume variation in general, and particularly of a Stirling engine which achieves an efficient power production with the least possible temperature differences between the low temperature area and the high temperature area, this fact constituting a most important advantage.

Advantages in comparison with the transmission mechanisms of all other machines: The achievement of an exceptional simplicity in operation, with any precision specified, and with any progressiveness required during the acceleration and deceleration of any moving parts, and thereby the possibility, without any practical limitations, of designing the machine and satisfying any motion requirements, from the roughest up to the finest. The achievement of an absolutely constant engagement of all toothings, standard and special, with a degree of overlap exactly the same as the toothing's degree of overlap between teeth, and with the possibility of further improving this degree of overlap, in order to achieve an even smoother and more quiet operation, by applying the currently used helical gearing, and in any case without any mechanism of immobilization or temporary connection.

The possibility of controlling and adjusting either the gear ratio variation, if this is allowable, or the rest of the design parameters of the toothing per se, for the purpose of optimizing the value of a particularly crucial quantity, the pressure angle, within limits also found in standard toothings, thus achieving the optimal efficiency of the toothing and thereby the optimal total efficiency of the machine.

The achievement of considerable economy in moving parts, with everything that follows this achievement, due to the distributive structure and operation of the combination of planetary systems, with the introduction of only two new moving parts in addition to those already existing, said parts being the carrier and the poly-planet.

Claims

1 .

Distributive Oscillating Transmission mechanism, which has a planetary system carrier (7), said carrier rotating with respect to the mechanism's frame (10) around a central axis and bearing a planet (5), said planet moving, through its engagement with a gear (35) fixed on the frame, the axis of said gear coinciding with said central axis, via the relative motion of the carrier with respect to the frame, said mechanism interconnecting kinematically a number of elements (1 , 2, 3, 4), which rotate coaxially around said central axis, said mechanism being characterized by the fact that:

- it performs continuously a given kinematic cycle in turn at all elements, on the unique but necessary condition that the ratio of the angular displacement during a kinematic cycle to the whole periphery is a rational number,

- the coaxially rotating elements are supported on the same, unique central shaft, which may be either the carrier or any other coaxial shaft, allowing continuously free rotation, via cooperating cages, each of said cages consisting of two discs (20, 22) coaxial with the central axis and axially spaced from one another, at an axial distance preferably common for all cages, and adequate for receiving any non-axial torque, said discs of each cage being connected via a number of identical, both within the same cage and between cages, bars (27), equally spaced along the discs periphery, said bars being parallel to the central axis, their cross-section being part of a circle's sector with a minimum radius such as to encircle the central shaft at an adequate distance to allow for the unobstructed and continuous relative motion of the bars and the central shaft, the angular width of said sector being such that, the number of bars being taken into account, the unobstructed relative motion of the cages is allowed in a specific angular travel sufficient for the transmission's function, the maximum radius of said sector being such that, the number of bars being taken into account, the mechanical strength requirements for the support of the elements are satisfied, while all discs of all elements, excluding the most lower and most upper of all these discs, have openings of such a cross-section that the unobstructed relative motion of the bars of a cage and the discs of other cages is allowed in the said angular travel, and finally, the cages differ in their axial position on the common central shaft, - the angular velocity of the carrier (7) with respect to the mechanism's frame (10) is such that, when a kinematic cycle is completely performed, the carrier, moving either in the same direction or in a direction opposite to the one of the elements' motion, the latter being viewed within a complete kinematic cycle, performs an integral number of revolutions with respect to any element, - the gear ratio of the gear (34) of the planet (5) to the gear (35) which is fixed on the frame (10) is such that, when a kinematic cycle is completely performed, the planet performs a number of complete revolutions around its axis equal to an integral multiple of the number of elements,

- the planet and each element have complementary toothing profiles of variable gear ratio so that, when the carrier performs a uniform motion around the central axis, and therefore the planet also performs a uniform motion around its own axis, the element moves with variable velocity and according to the aforementioned kinematic cycle, the mean value of the variable gear ratio being such that, after an integral number of complete revolutions of the planet around its axis and a - different, in general - integral number of complete revolutions of the element around the central axis, they return to their initial engagement position and the same kinematic cycle is repeated identically ad infinitum,

- the body of a toothing (32) of the aforementioned profile is fixed on the maximum, when using external toothing, or minimum, when using internal toothing, radius side of the bars of each element's cage, said toothing being deployed so that as the angular position of the profile's formation point changes, its axial position changes, either gradually in a stepped mode or, more preferably, continuously in the form of a helix, or, even more preferably, in the form of a single helix of constant pitch, the produced axial displacement for the respective angular displacement in all these cases being such as to allow the unobstructed relative motion of the elements in a specific angular travel adequate for the transmission's function, while the toothings are absolutely identical for all elements, their axial position inclusive, - the body of a toothing (33) complementary to the one mentioned above is fixed on the poly-planet body, said toothing being also deployed either in a stepped mode or in the form of a single helix depending on the deployment of the cooperating toothing, in an opposite, when all toothings are external, or the same, when a combination of external and internal toothings is used, direction, so that as the angular position of the profile's formation point changes, its axial position changes, according to the axial position of the same formation point on any element's complementary toothing profile,

- both types of toothing described above, are consequently completed after an integral number of turns, the term "turn" having the meaning of the material deployment, different for each type, said toothings having additionally at least half a tooth before their starting point, the profile of said tooth corresponding to the one right before the ending point, and at least half a tooth after their ending point, the profile of said tooth corresponding to the one right after the starting point, so that the engagement of the planet with each of the elements is absolutely constant and the degree of overlap of the toothings, during the transition of their engagement from the ending point to the starting point anew, is the same as the degree of overlap between single teeth, said additions being in accordance with the aforementioned stepped or helical deployment,

- with the application of all the aforementioned, the required synchronization is achieved, so that the planet acts as a power distributor or collector of said mechanism, as its toothing cooperates with the toothings of all elements simultaneously, continuously and ad infinitum.

2 .

Distributive Oscillating Transmission mechanism, according to claim 1 , characterized by the fact that:

- the direction of motion of the carrier (7) with respect to the elements is alternatively and exclusively:

- either the same as the elements' direction of motion, - or opposite to the elements' direction of motion, said elements' direction of motion being viewed within a complete kinematic cycle, in both cases,

- and the toothings (32, 33, 34, 35) being used, are alternatively and exclusively:

- either all external toothings,

- or a combination of external toothing for the poly-planet and internal toothing for all the elements.

3 .

Variable volume machine or else Toroidal Hermetic Engine, via which the strokes of a functional cycle are performed continuously and result in the transformation of energy from one form to another through volume variation, said machine consisting of a hollow shell (9), the internal surface (37) of said shell being toroidal, i.e. a surface of revolution having any planar, closed and smooth curve as its generating line, and of a plurality of pistons (1, 2, 3, 4), said pistons being parts of a toroid of such dimensions as to cooperate with said shell, and moving with respect both to the shell and to each other, the variable volume being defined by the shell's internal surface (37) and the faces (28, 29) of two consecutive pistons, said machine being further characterized by the fact that: - the kinematic interconnection of the pistons is achieved via the Distributive Oscillating Transmission mechanism, according to claim 1 or claim 2,

- the continuity of said toroidal internal surface (37) is interrupted by a peripheral slot (36), said slot extending on the whole periphery of the shell,

- a plurality of units (11, 12, 13) are arranged on the aforementioned shell, equally spaced along the shell periphery, each of said units consisting of openings or areas of intentionally reduced thermal insulation in such a manner that allow the transfer either of mass or of energy or of a combination of both, between the interior and the exterior of the shell, the functional cycle starting at the beginning of each unit and being completed at its end, while each said unit is called a "station", - after the completion of a functional cycle at the end of a station an additional purely kinematic process is interposed, which may either constitute on its own one or more strokes in a so extended functional cycle or be incorporated in the already existing strokes, said process comprising the transition of two consecutive and cooperating pistons to the next station, the pistons resting and being relieved from mechanical, thermal and chemical stresses during said transition and performing thereafter anew and identically the same functional cycle, said process being called "re-stationing",

- the ratio of the angular displacement within an extended functional cycle to the periphery, is a ratio of small integers, resulting in a reasonable number of stations to be constructed, and more specifically it is recommended that the ratio equals the inverse of a small integer, resulting in a number of stations equal to this integer,

- the pistons are structurally and functionally identical, each piston having two limiting faces, the front face (28) and the rear face (29), both taking part in the operation of the machine, being angularly spaced so that the required during the functional cycle volumes are formed between the rear face of one piston and the front face of its following piston, said faces having such shape as to favor the most efficient torque receipt or transmission with respect to the machine central axis, while the simplest such shape to be used is the plane and preferably the meridian plane, each of said pistons having a peripheral rib (17), i.e. a peripheral extension tangential to its body, said extension being part of the toroidal shell's ring which was cut out in order to form the peripheral slot, said peripheral rib having the axial thickness of the cut out ring and being deployed starting from an angular position between the piston faces, which lies at an adequate, with regard to mechanical strength, angular distance from the piston rear face and extending outside the piston body boundaries towards the following piston, said peripheral rib having an angular width such as to cover adequately the opening of the peripheral slot when the following piston is at its maximum distance from said piston and to allow for the unobstructed relative motion of the two pistons up to the point where they contact each other, or the same as described above configuration with the difference that the said peripheral rib is deployed starting from an angular distance from the piston front face extending outside the piston body boundaries towards the leading piston, satisfying any structural and operational requirements, thus ensuring the hermetic sealing of the pistons with the cooperating shell walls in the peripheral direction, via two peripheral sealing elements, said sealing elements either having a special meander shape or being spring steel elements or elements of special chemical composition or a combination of these, said sealing elements being located on both sides of said peripheral rib, with regard to the axial direction, each of said pistons having an arm (18, 19, 24) fixed on said peripheral rib on the whole of its axial thickness and extending to an adequate, with regard to mechanical strength, angular width, from the edge of the peripheral rib located between the piston faces to the rear face position or to the front face position, according to aforementioned peripheral rib deployment, said arm extending, right after its fixing on the peripheral rib, in parallel to the machine central axis and in both directions to an adequate, with regard to the capacity of receiving any non-axial torque, height (18), said arm extending from these two edges in two planes (19, 24) perpendicular to the central axis, until each of these two parts of the arm reaches the central axis and forms its own central supporting arm disc (20, 25), where at least one of the two arm discs is connected to or coincides with the respective cage disc (20 and, possibly, depending on the topology of the specific embodiment, 22) of the Distributive Oscillating Transmission mechanism, each of said pistons being configured in such a manner so that the least possible moment of inertia and centrifugal force are achieved, through the use of a material of adequate strength and minimum density, and also through the removal of a substantial quantity of material from the initial part of solid toroid (16), internally and externally, at such an extent that the remaining material possesses the required mechanical strength, and at an adequate distance from the faces, so that there is available space for the sealing grooves, but also from the lateral surface, at areas where the presence of this surface is not required either for sealing the "intake" / "influx" port (30) and the "exhaust" / "efflux" port (31) or for thermally insulating the "low temperature" area and the "high temperature" area,

- the pistons, finally, move having a differentiated angular displacement at each stroke of the functional cycle, so that said functional cycle is performed in the most efficient possible manner, said pistons being equal in number to the number of strokes of the aforementioned extended functional cycle, and said pistons being arranged within the shell in such a manner that at all times each stroke is performed consecutively within the space defined by the faces of two successive pistons, and because of the fact that the two active faces of each piston take part in two successive pairs of cooperating pistons, it follows that the rest of the cooperating piston pairs perform consecutively the same motions at a relative phase difference, and therefore each stroke being performed at one station, is afterwards performed at the next station, and so on ad infinitum.

4 .

Variable volume machine or else Toroidal Hermetic Engine, according to claim 3, characterized by the fact that the said peripheral slot (36) which interrupts the continuity of said toroidal internal surface (37) lays alternatively and exclusively:

- either on shell inner side, i.e. the side lying towards the machine central axis,

- or on shell outer side, i.e. the side lying to the opposite of the above described direction.

5 .

Machine of chemical volume variation or else, variable volume or piston stroke internal combustion engine, according to claim 3 or claim 4, further characterized by the following:

- the station consists of:

- at least one fuel intake port (38),

- at least one device for causing ignition of the air-fuel mixture by any means, either via spark or via injection of an air-fuel mixture at a self-ignition pressure or via any other method, unless this ignition device is located on each piston (49),

- at least one exhaust gas port (39), as well as

- any other openings or devices, e.g. preheating, cooling and cleaning, aiming at improving the performance of the thermodynamic cycle, - an additional motion has been incorporated into the re-stationing process, that is the parting of the cooperating pistons at an opening (50) of corresponding angular dimensions on the shell, said opening lying between the exhaust port (39) of one station and the intake port (38) of the next station, aiming at the most effective cooling and/or cleaning, even via brushes, of the working faces, during the operation of the engine, but also aiming at allowing inspection and/or maintenance work during engine switch-off, without there being need for engine dismantling.

6 . Machine of chemical volume variation or else, variable volume or piston stroke internal combustion engine, according to claim 5, characterized by the fact that its shell (9) is stationary and its carrier (7) constitutes the machine main drive shaft.

7 .

Machine of chemical volume variation or else, variable volume or piston stroke internal combustion engine, according to claim 5, characterized by the fact that its carrier (7) is stationary and its shell constitutes the machine main drive shaft (9, 10, 14), while the air-fuel mixture introduction is effected from the external space on the moving shell via piping and rotary type sealing (42) and the gas exhaust is effected via a specially configured stationary exhaust gas collector (8), resulting in an even smoother engine operation, but also in the drawing off of any residual exhaust gas energy, as the exhaust gases are led through the exhaust port (39), said exhaust port terminates in the form of an inclined nozzle (40) on the outer side of the shell (9), towards the walls of the exhaust gas collector (8), said walls being shaped in such a manner that the aerodynamic reaction of exhaust gases produces an additional torque on the drive shaft.

8 .

Machine of chemical volume variation or else, variable volume or piston stroke internal combustion engine, according to claim 5 or claim 6 or claim 7, further characterized by the fact that it is capable of performing, alternatively and exclusively and in a manner defined by its construction: - either the Otto cycle, with an approximately isovolumic process,

- or the Diesel cycle, with an approximately isobaric process, in combination with an improved kinematic cycle of increased energy performance but also of increased exhaust gases purity, wherein, during said kinematic cycle, the rear face (29) of the leading piston (1) and the front face (28) of the following piston (2) are situated successively,

- in surface contact at the beginning of the "induction" stroke, aiming at the intake solely of air-fuel mixture,

- at some, predetermined by the intended compression ratio, angular distance at the end of the "compression" stroke,

- at another predetermined angular distance, dependent on the requirement of complete or optimal exploitation of the exhaust gas energy, at the end of the "power" stroke, and

- in surface contact again at the end of the "exhaust" stroke, aiming at the complete expulsion of exhaust gases, while, having accomplished the complete expulsion of the exhaust gases, it is also possible to achieve their partial expulsion, either for their complete recombustion or for performing any other process, such as homogeneous charge compression ignition.

9 .

Machine of mechanical volume variation using either a liquid working medium or a gas working medium, which either produces mechanical work being a hydraulic motor or a pneumatic motor, respectively, or consumes mechanical work being a hydraulic pump or a pneumatic pump, respectively, said machine being defined according to claim 3 or claim 4 and being further characterized by the following:

- the machine shell is either stationary or moving in space, satisfying different operational requirements,

- the station consists of:

- at least one working medium inlet port, and

- at least one working medium outlet port, - the piston faces preferably have a perfect fit, so that, during the "influx" stroke, only working medium of "influx" energy level is admitted and, during the "efflux" stroke, a complete expulsion of working medium of "efflux" energy level takes place.

10 .

Machine of thermal volume variation which either uses thermal energy derived from external combustion or other heat sources, like the sun, as its input and produces mechanical work at its output, hence being called a Stirling engine, or vice versa, consumes mechanical work at its inlet and performs a refrigeration cycle, hence being called a refrigeration machine or heat pump, said machine being defined according to claim 3 or claim 4 and being further characterized by the following:

- the machine shell is either stationary or moving in space, satisfying different operational requirements, while, with regard to heat transfer, it has an effective thermal insulation throughout its whole body thickness,

- the station consists of:

- at least one "low temperature" area, and - at least one "high temperature" area, said areas having intentionally reduced thermal insulation,

- the piston faces have an angular distance between them and either a perfect fit or an almost perfect fit, so that the minimum volume, required when the working medium is in a condensed liquid state during the "compression" stroke, is formed, while, with regard to heat transfer, each piston has an effective thermal insulation throughout its whole body thickness.