FR3132737A1 - ALTERNATIVE THERMAL ENGINE - Google Patents

Abstract

ALTERNATIVE THERMAL ENGINE WITH HOT CYLINDER HEAD AND COLD CYLINDER The reciprocating thermal engine with hot cylinder head and cold cylinder (1) comprises a cooled cylinder block (5) which receives a cold cylinder (6) coated with a film of lubricant (7) and in which translates a piston (2) connected to power transmission means (3) to form a hot chamber of variable volume (11) with a hot cylinder head (10) which is kept pressed but free to expand on said crankcase- cylinder (5) by cylinder head plating means (24), while a hot cap (19) is interposed between said chamber (11) and piston (2) and is kept pinned but free to expand on said piston (2) by means of cap plating (23), the piston (2) comprising a cooled piston sealing ring (37) which has piston sealing means (30). Figure for abstract: Fig. 1

Description

ALTERNATIVE THERMAL ENGINE WITH HOT CYLINDER HEAD AND COLD CYLINDER

The present invention relates to a reciprocating thermal engine with a hot cylinder head and a cold cylinder, said engine being particularly adapted to the implementation of the Brayton thermodynamic cycle with regeneration which is ordinarily carried out by means of centrifugal compressors and turbines.

Regenerative Brayton cycle engines generally comprise separate organs dedicated to each of the phases of said cycle, said phases taking place continuously and simultaneously in said organs unlike reciprocating internal combustion engines with Beau de Rochas cycle, Miller cycle, etc. 'Atkinson or Diesel whose phases are executed successively in a single cylinder.

Consequently, regenerative Brayton cycle engines comprise at least one compressor, at least one regeneration exchanger, at least one burner operating continuously or an internal or external hot source, and at least one expander.

Entrusting each phase of a thermodynamic cycle to a dedicated body has various advantages. In particular, the temperature of the internal walls of each said organ can remain very close to that of the gases during said phase.

For example, the temperature of the internal walls of the compressor of a regenerative Brayton cycle engine can be kept as low as possible, which helps to minimize the compression work and maximize the total thermodynamic efficiency of said engine.

Conversely, the internal walls of the regulator of said engine being in contact with the hot gases coming from the burner, their temperature must be high and in all cases, maintained as close as possible to the average temperature of said gases between the start and the end. end of their relaxation.

Despite these advantages, the maximum thermodynamic efficiency of engines with centrifugal compressors and regenerative Brayton cycle turbines is in practice hardly higher than that of conventional spark ignition engines, and at best, comparable to that of fast diesel engines.

In all cases, said efficiency remains lower than that of slow two-stroke diesel engines of several tens of megawatts used for example for naval propulsion or stationary electricity production.

In addition, engines with centrifugal compressors and regenerative Brayton cycle turbines are poorly suited to low powers, and can only operate over a restricted power range outside of which their efficiency drops drastically.

This is why engines with centrifugal compressors and regenerative Brayton cycle turbines are mainly used for applications where efficiency is not the sole objective, and which require, for example, high specific and volume power, of low acoustic and vibration emissions, long life, or reduced maintenance.

This is the case, for example, of certain military ships equipped, for example, with the “Rolls-Royce WR-21” centrifugal compressor and regenerative Brayton cycle turbine engine, whose efficiency hardly exceeds forty percent, however that of the slow two-stroke diesel engines that equip some ships exceed fifty percent.

This is also the case for certain generators most often operating in cogeneration of electricity and heat such as the “T100” micro turbine from the “Turbec” company, or the “C65” micro turbine from the “Capstone” company. whose electrical efficiencies are of the order of only twenty-eight to thirty percent, but which require little maintenance while offering very long lifespans.

The advantage of these turboshaft engines is that their turbine can withstand temperatures of around one thousand three hundred degrees Celsius. However, their total thermodynamic efficiency remains limited by that of the centrifugal compressors and the turbines which constitute them, the efficiency of said compressors and said turbines hardly exceeding eighty percent over a relatively narrow operating range.

Taking the above into account, it would be particularly interesting to be able to replace the centrifugal compressors and turbines of regenerative Brayton cycle engines with positive displacement piston machines whose efficiency is significantly higher.

This is for example the subject of patent No. US4653269 of March 31, 1987, where the expansion turbine usually found on regenerative Brayton cycle turboshaft engines is replaced by a volumetric piston expansion cylinder.

However, the calculations demonstrate that if the internal walls of said volumetric expander are cooled and maintained for example around one hundred degrees Celsius like the reciprocating engines produced and marketed on a large scale, the thermodynamic efficiency of a Brayton cycle engine at regeneration cannot exceed that of an automobile Diesel engine.

For a regenerated Brayton cycle engine with a volumetric expander to deliver very high thermodynamic efficiencies, it is essential that the internal walls of its expander are maintained at a temperature close to the average temperature of the gases expanded in said expander.

For example, if the hot gases are introduced into the regulator at a temperature of one thousand three hundred degrees Celsius and are expelled from said regulator at the end of expansion at a temperature of six hundred degrees Celsius, the internal walls of said regulator must be maintained approximately at a temperature of nine hundred and fifty degrees Celsius.

The problem is that at such a temperature, it is impossible to keep a film of oil on the walls of the regulator cylinder to lubricate whatever sealing ring a regulator piston may have moving in said cylinder.

Indeed, from around one hundred and sixty degrees Celsius, the oil film on the cylinder begins to coking, then burns above two hundred and fifty degrees Celsius.

Producing a regenerative Brayton cycle engine with high thermodynamic efficiency therefore faces a double impasse.

Indeed, either said engine is made up of centrifugal compressors and turbines resistant to high temperatures, but in this case, the modest efficiency of these organs does not allow it to exceed a total efficiency equivalent to that of an automobile Diesel, or it consists of a volumetric piston expander which, to be watertight, requires a piston fitted with a segmentation sliding on an oil film formed on the surface of a cylinder, the latter having to remain at a temperature not exceeding not around one hundred and twenty degrees Celsius, which also does not allow the total efficiency of said engine to be competitive.

In this context, it would be advantageous to be able to combine the ability of turbines to operate at high temperatures with that of volumetric piston machines to expand gases at high efficiency.

It is with this objective that the heat engine with transfer-expansion and regeneration according to patent WO2016120560 published on August 4, 2016 and belonging to the applicant comprises non-contact piston sealing means consisting of a continuous perforated inflatable ring which, when 'it is subjected to a certain internal pressure, inflates and approaches a few micrometers from the regulator cylinder with which it cooperates without touching said cylinder, this while letting compressed air leak via calibrated orifices which pass through it on both sides part in its radial thickness.

The fluid cushion sealing device which has just been described was also the subject of patent FR 3032252 issued on May 25, 2018 and belonging to the applicant. This device makes it possible to achieve contactless sealing and therefore to no longer use oil to lubricate a segment operating by contact, and therefore to cooperate with a hot regulator cylinder, maintained at a temperature of several hundred degrees. Celsius.

In this context, it therefore effectively becomes possible to use a piston volumetric expander to produce a regenerative Brayton cycle engine, and to maximize the efficiency of said engine to largely surpass that of Diesel cycle engines.

Indeed, calculations and simulations demonstrate that the thermodynamic efficiency of a Brayton cycle engine with piston volumetric regeneration can reach or even exceed seventy percent, which in practice can lead to the production of engines whose energy efficiency to the brake exceeds sixty percent once the inevitable thermal and mechanical irreversibilities due to the very constitution of said motors are deducted.

The problem encountered with the fluid cushion sealing device of patent No. FR 3032252 is that the temperature of the cylinder still remains excessive for the available materials of which the continuous perforated ring can be made.

Indeed, for the efficiency of a Brayton cycle engine with volumetric regeneration with pistons to be significantly higher than that of existing Diesel engines, the gases must be introduced into its expander at a temperature of the order of one thousand three hundred degrees Celsius, under a pressure of around twenty bars.

As a result of these operational conditions, the temperature of the internal walls of the regulator stabilizes around nine hundred and fifty degrees Celsius.

Given that the continuous perforated ring according to patent No. FR 3032252 is close to the cylinder with which it cooperates by only a few microns, in practice, said ring adopts the temperature of approximately nine hundred and fifty degrees Celsius of said cylinder.

However, no material can both make it possible to manufacture said ring and withstand such a temperature.

Even a superalloy such as "Udimet 720", particularly used in aeronautics and the space industry and known for its resistance to extreme temperatures, cannot withstand such a temperature without being subject to creep and while being subject to the swelling stress that requires the continuous perforated ring of the fluid cushion sealing device according to patent No. FR 3032252.

It is in particular for this reason and to use more common materials than ceramics resistant to high temperatures, that the regenerative cooling system according to patent No. EP 3585993 published on April 7, 2021 and belonging to the applicant plans to lower the temperature of the internal walls of the regulator and in particular of the cylinder to practical values of the order of seven hundred degrees Celsius.

For example, the “Udimet 720” superalloy resists creep at a temperature of seven hundred degrees Celsius if it is subjected to a stress not exceeding two hundred and thirty mega Pascals.

The regenerative cooling system according to patent No. EP 3585993 provides a cooling enclosure which envelops the expander while a gas circulation space is left between said enclosure and said expander in which the gases leaving the expander itself circulate at a temperature between five hundred and six hundred degrees Celsius.

Thus, according to the regenerative cooling system according to patent No. EP 3585993, the exhaust gases from the expander maintain the temperature of the internal walls of the expander at a temperature of the order of seven hundred degrees Celsius while the heat exported by said gas is essentially recovered to be reintroduced into the cycle by the regeneration heat exchanger which comprises the reciprocating regenerative Brayton cycle piston engine.

In this context, the fluid cushion sealing device of patent FR 3032252 can be used with a continuous perforated ring, for example made of “Udimet 720” superalloy.

However, in return for this possibility, the cylinder and heads of the regenerative Brayton cycle piston reciprocating engine must be made of materials with a high nickel content such as "Niresist" cast iron which, due to the high volatility and of the high price of nickel, represents an economic disadvantage.

In all cases, we note that the temperature of the regulator remains at least six hundred degrees Celsius higher than that of the rest of the engine and in particular, of the mobile coupling and the transmission casing in which said coupling is housed.

Advantageously, the differential expansions which result from this temperature difference can in particular be managed by the double-acting expansion cylinder with adaptive support which is the subject of patent No. EP3350433 issued on August 7, 2019 and belonging to the applicant.

Said support allows an isotropic or anisotropic expansion of the expansion cylinder which is very different from that of the transmission casing on which it is fixed, this without compromising either the operation of said cylinder, nor that of the piston which evolves in said cylinder.

Said support further keeps the piston centered in the cylinder, transmits the axial forces resulting from the expansion of the gases to the transmission casing, and limits heat transfer from the expander cylinder to said casing.

On reading the above, we understand that no configuration is at this stage fully satisfactory which makes it possible to produce in the best possible conditions a reciprocating piston engine with a regenerative Brayton cycle.

Indeed, the fluid cushion sealing device must be supplied with compressed air by a compressor which consumes part of the work available on the shaft of the regenerative Brayton cycle piston engine, to the detriment of the total efficiency of this last.

This in fact reduces the final energy efficiency of said motor, and all the more so if the latter operates at low power because the quantity of compressed air to be supplied to the fluid cushion sealing device is almost constant, whatever the speed and load of said engine.

Furthermore, to guarantee long-term operation of the fluid cushion sealing device, it is necessary to use the regenerative cooling system according to patent No. EP 3585993, however, said system is not energy neutral.

In fact, said cooling system makes the path of the gases expelled from the expander tortuous and induces pressure losses which reduce the total efficiency of the regenerative Brayton cycle piston engine.

In addition, the heat extracted from the internal walls of the expander by the regenerative cooling system is reintroduced into the Brayton cycle upstream of a burner or a hot source by a regeneration heat exchanger whose efficiency is not one hundred percent.

Part of the heat extracted from the internal walls of the expander is therefore lost, and the power passing through the exchanger increases due to the presence of said cooling system.

In addition, the specific power of the regenerative Brayton cycle piston engine is significantly reduced by the regenerative cooling system according to patent No. EP 3585993, which involves revising upwards the dimensioning of said engine to meet the objectives. power of the application for which it is intended.

We also note that the development of the fluid cushion sealing device of patent No. FR 3032252 remains complex, particularly to ensure its proper functioning in the context of non-stationary applications subject to shock and vibration.

This is why, without excluding any other application in any field whatsoever, the reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention is, among other things, intended to produce reciprocating Brayton cycle piston engines with regeneration whose mainly hot regulator limits thermal losses, while ensuring a robust and durable seal between the piston and the cylinder of said regulator.

• Dont la culasse et la calotte de piston sont maintenus à haute température de sorte à limiter le refroidissement des gaz chauds à leur contact ;
• Dont l’étanchéité entre le piston et le cylindre peut être réalisée au moyen de segments en fonte ou en acier tels que ceux que comprennent les moteurs à combustion interne conventionnels à allumage commandé ou à cycle de Diesel ;
• Qui ne recourt plus au dispositif d’étanchéité à coussin de fluide objet du brevet N° FR 3032252 et donc, qui ne nécessite plus de système de refroidissement régénératif tel que celui que décrit le brevet N° EP 3585993, et donc, qui ne subit ni les pertes de puissance et de rendement liées à l’emploi d’un compresseur d’alimentation dudit dispositif d’étanchéité, ni les pertes de charges additionnelles à l’échappement du détendeur liées à un parcours des gaz plus tortueux, ni les pertes de chaleur dues au rendement inférieur à « un » de l’échangeur thermique de régénération, ni les pertes en puissance spécifique du moteur associées à cette configuration.

In the field of application of reciprocating piston thermal machines in general and thermal engines in particular, the invention results in an reciprocating thermal engine with a hot cylinder head and a cold cylinder:

• Whose cylinder head and piston crown are maintained at a high temperature so as to limit the cooling of the hot gases in contact with them;
• Whose seal between the piston and the cylinder can be achieved by means of cast iron or steel segments such as those included in conventional internal combustion engines with spark ignition or Diesel cycle;
• Which no longer uses the fluid cushion sealing device covered by patent No. FR 3032252 and therefore, which no longer requires a regenerative cooling system such as that described in patent No. EP 3585993, and therefore, which no longer undergoes neither the losses of power and efficiency linked to the use of a supply compressor of said sealing device, nor the additional pressure losses at the exhaust of the regulator linked to a more tortuous gas path, nor the losses of heat due to the efficiency less than “one” of the regeneration heat exchanger, nor the specific power losses of the engine associated with this configuration.

Furthermore, as an alternative to materials with a high nickel content such as “Niresist” cast iron, the hot cylinder head of the reciprocating thermal engine with a hot cylinder head and cold cylinder according to the invention can be made of silicon carbide, a high-strength material. mechanical at high temperatures, abundant and cheap, while the cylinder of said engine can be made of low-cost cast iron such as that ordinarily used to make the cylinder housings of automobile Diesel engines.

In addition, the lower density of silicon carbide and the absence of a regenerative cooling system lead to a lower weight of the reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention and to a lower total heat capacity of said engine, which promotes a rapid rise in temperature of said engine by reducing the energy necessary to reach its operating temperature, and which leads to lower energy consumption of said engine particularly when the latter applies to road, rail, or maritime.

It is understood that the reciprocating heat engine with hot cylinder head and cold cylinder according to the invention can be applied, in addition to heat engines generally stationary or mobile and with internal or external combustion, to any other application similar in its concept and in its nature. principle which could advantageously take advantage of the particular characteristics and functionalities of said engine according to the invention.

• Des moyens de lubrification qui forment un film de lubrifiant qui s’interpose entre le cylindre froid et le piston ;
• Des moyens de refroidissement de carter-cylindre qui refroidissent le carter-cylindre refroidi de sorte à maintenir tout ou partie de la surface interne du cylindre froid à une température suffisamment basse pour que le film de lubrifiant ne vieillisse pas prématurément, ne cokéfie pas, ou ne brûle pas ;
• Au moins une culasse chaude dont la température de fonctionnement est significativement supérieure à celle du carter-cylindre refroidi qu’elle coiffe pour former avec le piston une chambre chaude de volume variable qui renferme un gaz de travail, ladite culasse étant d’une part, maintenue plaquée sur le carter-cylindre refroidi par des moyens de plaquage de culasse qui la laissent libre de se dilater par rapport audit carter-cylindre, et d’autre part, localisée par rapport audit carter-cylindre par des moyens de centrage de culasse ;
• Au moins un anneau d’étanchéité de piston aménagé en périphérie du piston, ledit anneau comportant d’une part, des moyens d’étanchéité de piston qui forment une étanchéité entre le piston et le cylindre froid, et étant d’autre part, refroidi par des moyens de refroidissement d’anneau d’étanchéité ;
• Au moins une calotte chaude qui est interposée entre la chambre chaude de volume variable et le piston et dont la température de fonctionnement est significativement supérieure à celle du carter-cylindre refroidi, ladite calotte étant d’une part, maintenue plaquée sur le piston par des moyens de plaquage de calotte qui laissent ladite calotte libre de se dilater par rapport audit piston, et d’autre part, localisée par rapport audit piston par des moyens de centrage de calotte.

The reciprocating thermal engine with hot cylinder head and cold cylinder comprising a cooled cylinder block in which is arranged at least one cold cylinder in which a piston oriented and/or located by piston guide means can translate, said piston being directly or indirectly connected by power transmission means housed in a transmission housing to at least one rotating or reciprocating power output shaft, comprises

• Lubrication means which form a film of lubricant which is interposed between the cold cylinder and the piston;
• Cylinder case cooling means which cools the cooled cylinder case so as to maintain all or part of the internal surface of the cold cylinder at a sufficiently low temperature so that the lubricant film does not age prematurely, does not coke, or does not burn;
• At least one hot cylinder head whose operating temperature is significantly higher than that of the cooled cylinder block which it covers to form with the piston a hot chamber of variable volume which contains a working gas, said cylinder head being on the one hand, kept pressed against the cooled cylinder block by cylinder head clamping means which leave it free to expand relative to said cylinder block, and on the other hand, located in relation to said cylinder block by cylinder head centering means;
• At least one piston sealing ring arranged on the periphery of the piston, said ring comprising on the one hand, piston sealing means which form a seal between the piston and the cold cylinder, and being, on the other hand, cooled by sealing ring cooling means;
• At least one hot cap which is interposed between the hot chamber of variable volume and the piston and whose operating temperature is significantly higher than that of the cooled cylinder block, said cap being on the one hand kept pressed against the piston by cap-plating means which leave said cap free to expand relative to said piston, and on the other hand, located relative to said piston by cap-centering means.

The reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention comprises sealed thermal insulation means which are interposed between the cooled cylinder block and the hot cylinder head.

The reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention comprises thermal insulation means which are interposed between the hot cap and the piston.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises sealed thermal insulation means and/or thermal insulation means which consist of at least one insulating ring made of a material with low thermal conductivity .

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a material with low thermal conductivity which is mainly made up of zirconium oxide.

The reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention comprises an insulating ring which forms the sealed means of thermal insulation which is directly or indirectly in contact with the cooled cylinder block and/or with the hot cylinder head by the intermediate of at least one contact edge of small surface which prevents the working gas from passing between the cooled cylinder block and the hot cylinder head.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises an insulating ring which forms the thermal insulation means which is directly or indirectly in contact with the hot cap and/or with the piston via at minus a contact edge of small surface area.

The reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention comprises a cylinder head seal which is interposed between the insulating ring which forms the sealed means of thermal insulation and the cooled cylinder block and/or between said ring and hot breech.

The reciprocating heat engine with a hot cylinder head and a cold cylinder according to the invention comprises a piston seal which is interposed between the insulating ring which forms the thermal insulation means and the hot cap and/or between said ring and the piston.

The reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention comprises a hot cylinder head and/or a hot cap which are entirely or partly made of a material resistant to high temperatures.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a material resistant to high temperatures which is mainly made of silicon carbide.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a hot cylinder head which has a concave conical cylinder head surface through which said cylinder head is kept pressed by the cylinder head plating means on a circular contact edge cylinder arranged on the cooled cylinder block, the angle of the concave cone formed by said surface being such that when said surface slides on said edge due to the difference between the thermal expansion of said cylinder head and that of said cylinder block, the axial distance which separates the point of support of the cylinder head plating means on the hot cylinder head of the cooled cylinder block remains approximately constant all other things being equal, while the concave conical surface of the cylinder head and the circular contact edge of cylinder form the cylinder head centering means.

The reciprocating heat engine with a hot cylinder head and a cold cylinder according to the invention comprises a hot cap which has a concave conical cap surface through which said cap is held pressed by the cap plating means onto a circular contact edge. piston arranged on the piston, the angle of the concave cone formed by said surface being such that when said surface slides on said edge due to the difference between the thermal expansion of said cap and that of the piston, the axial distance which separates the point of support of the crown pressing means on the hot piston crown remains approximately constant all other things being equal, while the concave conical surface of the crown and the circular piston contact edge form the crown centering means .

The reciprocating heat engine with a hot cylinder head and cold cylinder according to the invention comprises a hot cap which has an aerodynamic passivation cord at its periphery.

The reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention comprises an exterior of the hot cylinder head which is covered with a thermal insulator.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a piston sealing ring which has piston guiding means consisting of an annular sliding surface.

The reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention comprises a cooled cylinder block which is held between a lower hot cylinder head and an upper hot cylinder head by the cylinder head plating means while the piston is double-acting and comprises on the one hand, a lower piston rod which connects it to the power transmission means and which passes right through the lower hot cylinder head via a lower rod orifice, and on the other hand, a lower hot cap and a upper hot cap to define with the lower and upper hot cylinder heads a lower hot chamber of variable volume and an upper hot chamber of variable volume.

• Au moins un pilier évidé qui est traversé de part en part dans le sens de sa longueur par un tunnel de tige, une première extrémité de pilier dudit pilier reposant directement ou indirectement sur le carter de transmission tandis qu’une deuxième extrémité de pilier dudit pilier supporte la culasse chaude inférieure, ladite première extrémité pouvant pivoter autour d’une liaison rotule et/ou fléchir par rapport audit carter cependant que ladite deuxième extrémité peut pivoter autour d’une liaison rotule et/ou fléchir par rapport à ladite culasse chaude inférieure ;
• Au moins une tige de traction qui forme les moyens de plaquage de culasse et qui est, au moins pour partie, logée dans le tunnel de tige, une première extrémité de tige de ladite tige de traction étant directement ou indirectement arrimée au carter de transmission tandis qu’une deuxième extrémité de tige de ladite tige est directement ou indirectement arrimée à la culasse chaude supérieure, ladite première extrémité pouvant pivoter autour d’une liaison rotule et/ou fléchir par rapport audit carter tandis que ladite deuxième extrémité peut pivoter autour d’une liaison rotule et/ou fléchir par rapport à ladite culasse ;
• Des moyens de centrage de culasse inférieure qui sont solidaires du carter de transmission et qui prennent directement ou indirectement appui sur la culasse chaude inférieure, lesdits moyens laissant ladite culasse libre de se déplacer sur une courte distance parallèlement à l’axe longitudinal du cylindre froid et par rapport au carter de transmission, mais interdisant à ladite culasse de se déplacer dans le plan perpendiculaire audit axe par rapport audit carter ;
• Des moyens de centrage de culasse supérieure qui sont solidaires d’un portique de centrage lequel est rigidement fixé au carter de transmission, lesdits moyens prenant directement ou indirectement appui sur la culasse chaude supérieure, et lesdits moyens laissant ladite culasse libre de se déplacer sur une courte distance parallèlement à l’axe longitudinal du cylindre froid et par rapport au carter de transmission, mais interdisant à ladite culasse de se déplacer dans le plan perpendiculaire audit axe par rapport audit carter.

The reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention comprises:

• At least one hollow pillar which is crossed right through in the direction of its length by a rod tunnel, a first pillar end of said pillar resting directly or indirectly on the transmission casing while a second pillar end of said pillar supports the lower hot cylinder head, said first end being able to pivot around a ball joint and/or flex relative to said casing while said second end can pivot around a ball joint and/or flex relative to said lower hot cylinder head;
• At least one traction rod which forms the cylinder head plating means and which is, at least in part, housed in the rod tunnel, a first rod end of said traction rod being directly or indirectly secured to the transmission casing while that a second rod end of said rod is directly or indirectly secured to the upper hot cylinder head, said first end being able to pivot around a ball joint and/or flex relative to said casing while said second end can pivot around a ball joint and/or flex relative to said cylinder head;
• Lower cylinder head centering means which are integral with the transmission casing and which directly or indirectly bear on the lower hot cylinder head, said means leaving said cylinder head free to move over a short distance parallel to the longitudinal axis of the cold cylinder and relative to the transmission casing, but preventing said cylinder head from moving in the plane perpendicular to said axis relative to said casing;
• Upper cylinder head centering means which are integral with a centering gantry which is rigidly fixed to the transmission casing, said means bearing directly or indirectly on the upper hot cylinder head, and said means leaving said cylinder head free to move on a short distance parallel to the longitudinal axis of the cold cylinder and relative to the transmission casing, but prohibiting said cylinder head from moving in the plane perpendicular to said axis relative to said casing.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a rod cooling tube which sealingly envelops the traction rod over all or part of the length of said rod, a heat transfer liquid coming from a heat source. cooling liquid capable of circulating in a space left between the internal wall of said tube and the external surface of said rod while the greatest possible part of the external surface of said tube does not touch the internal wall of the rod tunnel so as to define with this last wall an empty space.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises at least a first tube feed port which communicates with the interior of the rod cooling tube in the vicinity of the first rod end, and at least one second tube supply orifice communicates with the interior of the rod cooling tube in the vicinity of the second rod end, the heat transfer liquid being able to circulate between the two said orifices.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a rod cooling tube which comprises a tube collar held directly or indirectly clamped by the traction rod either against a fixing ear which the upper hot cylinder head presents, or against the transmission case.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a tube collar which is held tight by the traction rod against the fixing ear via a Banjo connection which comprises at least one radial conduit connection which is connected to the source of coolant on the one hand, and which communicates with the interior of the rod cooling tube on the other hand.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a thermal insulation extension which is interposed between the tube collar and the fixing ear, said extension being crossed right through in the direction of its length by an extension tunnel in which the traction rod is housed and the rod cooling tube which envelops it in a sealed manner, while as much as possible of the external surface of said tube does not touch the internal wall of the extension tunnel raises so as to define an empty space with this last wall.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a rod cooling tube which comprises at least one tube bulge consisting of an axial portion of said tube whose free diameter is substantially equivalent or even slightly greater than that of the stem tunnel in which it is housed.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a rod cooling tube which comprises at least one tube diameter restriction consisting of an axial portion of said tube whose free diameter is substantially equivalent or even slightly less than that of the pull rod body.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a traction rod which is hollow to form an internal rod cooling channel arranged in the length of said rod, said channel opening out axially or radially in the vicinity of each end said rod while a heat transfer liquid coming from a coolant source can circulate in said channel.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a piston cooling and lubrication chamber which is connected to a source of lubricating-cooling fluid and which is fixed on the centering gantry or arranged on or in this last while an upper piston rod which extends the double-acting piston on the side of the hot chamber of upper variable volume passes through the upper hot cylinder head via an upper rod orifice arranged in said cylinder head and via an access orifice to the cooling and lubrication chamber passing through the centering gantry to open into the piston cooling and lubrication chamber so that the end of the upper piston rod which is furthest from said piston always remains immersed in said chamber whatever or the position of said piston.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a lubricating-cooling fluid which can circulate from the cooling and piston lubrication chamber to the transmission casing by passing successively via an internal upper rod channel of piston arranged longitudinally in the upper piston rod, via an internal piston cavity, and via a lower piston rod internal channel arranged longitudinally in the lower piston rod.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a periphery of the internal piston cavity which communicates with the external peripheral face of the piston sealing ring via at least one peripheral ring lubrication orifice which opens axially between at least two piston sealing means, said orifice constituting the lubrication means.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a transmission casing which is covered with a centering and sealing plate pierced with an access orifice to the transmission means through which the rod passes lower piston to be connected to the power transmission means, said plate being rigidly fixed to said casing.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises an access orifice to the cooling and lubrication chamber which comprises rod sealing means providing a seal between said orifice and the upper piston rod.

The reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention comprises an access orifice to the transmission means which comprises rod sealing means providing a seal between said orifice and the lower piston rod.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises means for centering the lower cylinder head and/or means for centering the upper cylinder head which consist of an elastic centering disk which can be pierced in its center. a disc hole through which the lower piston rod or an upper piston rod respectively passes while its periphery constitutes a disc fixing collar fixed in a sealed manner respectively on the transmission casing and/or on the centering gantry.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises a centering and sealing plate which carries the lower cylinder head centering means which consist of an elastic centering disc whose periphery forms a fixing collar disc fixed in a sealed manner on said plate, said disc being pierced in its center with a disc hole through which the lower piston rod passes without touching said disc, the edge of the disc hole having a circular contact pad which is maintained in sealed contact with a centering and sealing cone presented by the lower hot cylinder head, said cone possibly being male or female, and the contact between said shoe and said cone having the effect of deforming the disc axially and from its center centering elastic.

The reciprocating heat engine with hot cylinder head and cold cylinder according to the invention comprises upper cylinder head centering means which consist of an elastic centering disc whose periphery forms a disc fixing collar fixed in a sealed manner on the gantry. centering, said disc being pierced in its center with a disc hole whose edge has a circular contact pad which is maintained in sealed contact with a centering and sealing cone which the upper hot cylinder head presents, said cone being able to be male or female, and the contact between said pad and said cone having the effect of deforming axially and from its center the elastic centering disc.

The reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention comprises an anti-rotation connection which directly or indirectly connects the lower hot cylinder head and/or the upper hot cylinder head and/or the cooled cylinder block to the centering gantry.

The description which follows with reference to the appended drawings and given as non-limiting examples will allow a better understanding of the invention, the characteristics it presents, and the advantages it is likely to provide:

is a schematic sectional view of the reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention, the valves which supply the hot chamber of variable volume of said engine not appearing on said section.

is a three-dimensional view of the reciprocating heat engine with a hot cylinder head and a cold cylinder according to the invention, the piston of which is double-acting, said engine forming a regulator which allows, for example, to implement a Baritone thermodynamic cycle with regeneration.

is a three-dimensional sectional view of the reciprocating thermal engine with a hot cylinder head and a cold cylinder according to the invention, and according to the particular configuration of said engine shown in , the double-acting piston defining, with a lower hot cylinder head and an upper hot cylinder head, a lower hot chamber of variable volume and an upper hot chamber of variable volume.

is a sectional view of the reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention, and according to the particular configuration of said engine shown in Figures 2 and 3.

is a close-up sectional view of the reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention and according to the particular configuration of said engine shown in Figures 2 to 4, said view notably highlighting how the double-acting piston is connected to the means power transmission, and how the seal is created between the lower piston rod and the transmission housing.

is a close-up sectional view of the reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention and according to the particular configuration of said engine shown in Figures 2 to 5, said view notably highlighting how the upper piston rod of the double piston effect opens into the piston cooling and lubrication chamber, and how the seal is achieved between said rod and a centering gantry.

is an exploded three-dimensional view of the reciprocating thermal engine with a hot cylinder head and a cold cylinder according to the invention and according to the particular configuration of said engine shown in .

is a view, partly three-dimensional and partly in schematic section, of a part of the reciprocating heat engine with hot cylinder head and cold cylinder according to the invention and according to the particular configuration of said engine shown in Figures 2 to 7, said view highlighting the main sections which make up the hollowed-out pillars and the pull rods which form the cylinder head plating means of the hot cylinder heads on the cooled cylinder block.

is a close schematic sectional view of the reciprocating thermal engine with hot cylinder head and cold cylinder according to the invention and according to the particular configuration of said engine shown in Figures 2 to 8, said view showing the position and dimensions of the hot caps of the double piston effect and the upper hot cylinder head relative to the cooled cylinder block when said caps and said cylinder head are cold.

is a schematic sectional view similar to that shown in , said view showing the position and dimensions of the hot caps of the double-acting piston and the upper hot cylinder head relative to the cooled cylinder block when said caps and said cylinder head are hot and expand under the effect of temperature.

DESCRIPTION OF THE INVENTION:

We have shown in Figures 1 to 10 the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention, various details of its components, its variants, and its accessories.

The reciprocating thermal engine with hot cylinder head and cold cylinder 1 comprises a cooled cylinder block 5 in which is arranged at least one cold cylinder 6 in which a piston 2 oriented and/or located by piston guide means 29 can translate.

The piston 2 is directly or indirectly connected by power transmission means 3 housed in a transmission housing 42 to at least one rotary or reciprocating power output shaft 4.

The power transmission means 3 can for example take the form of a connecting rod 34 articulated around a crank 48 arranged on a crankshaft 35, said connecting rod 34 being able to be connected to the piston 2 directly by a piston pin or indirectly by the intermediate a stock 49.

Said means 3 can also consist of a cam, a hydraulic transmitting pump, a linear or rotary electricity generator or any other means of transmission known to those skilled in the art.

As seen in Figures 1 to 10, the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention comprises lubricating means 8 which form a film of lubricant 7 which is interposed between the cold cylinder 6 and the piston 2, said means 8 being able for example to consist of bubbling the power transmission means 3 in liquid lubricant contained in the transmission casing 42.

Figures 1, 3, 4, 9 and 10 clearly show that the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention also comprises cylinder crankcase cooling means 9 which are for example made up of a cooling chamber. cooling 27 which envelops the cooled cylinder block 5 while a heat transfer liquid 32 can circulate in said chamber 27, said means 9 cooling the cooled cylinder block 5 so as to maintain all or part of the internal surface of the cold cylinder 6 at a temperature low enough so that the lubricant film 7 does not age prematurely, coking, or burning;

In Figures 1 to 10, it has been shown that the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention also comprises at least one hot cylinder head 10 which can comprise at least one intake valve 31 and at least one valve d exhaust 33 which are controlled by a valve actuator 50.

The operating temperature of the hot cylinder head 10 is significantly higher than that of the cooled cylinder block 5 which it covers to form with the piston 2 a hot chamber of variable volume 11 which contains a working gas 17.

As can be easily seen in Figures 9 and 10, the hot cylinder head 10 is, on the one hand, held pressed against the cooled cylinder block 5 by cylinder head clamping means 24 which leave it free to expand relative to said crankcase. cylinder 5, and on the other hand, located relative to said cylinder block 5 by cylinder head centering means 39 which could for example consist of a centering pin or a support collar.

Furthermore and as shown by and Figures 3 to 10, the reciprocating heat engine with hot cylinder head and cold cylinder 1 comprises at least one piston sealing ring 37 arranged on the periphery of the piston 2, said ring 37 comprising, on the one hand, sealing means piston 30 for example made up of compression rings 44 made of cast iron or steel such as those ordinarily found on the pistons of conventional automobile engines, said means 30 forming a seal between the piston 2 and the cold cylinder 6, and being other part, cooled by sealing ring cooling means 38.

As shown in the and Figures 3 to 10, the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention also comprises at least one hot cap 19 which is interposed between the hot chamber of variable volume 11 and the piston 2 and whose temperature of operation is significantly higher than that of the cooled cylinder block 5.

As clearly illustrated in Figures 9 and 10, said cap 19 is, on the one hand, kept pressed on the piston 2 by cap-plating means 23 which leave said cap 19 free to expand relative to said piston 2, and on the other hand, located relative to said piston 2 by cap centering means 40 which could for example consist of a centering pin or a support collar.

In , in Figures 2 to 7, and in Figures 9 and 10, we see that the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention can comprise sealed thermal insulation means 12 which are interposed between the cylinder block cooled 5 and the hot cylinder head 10, said means 12 being able to – according to a particular embodiment – form an integral part of the cooled cylinder block 5 and/or the hot cylinder head 10.

Likewise and as particularly visible in Figures 9 and 10, thermal insulation means 22 can be interposed between the hot cap 19 and the piston 2, said means 22 being able to form an integral part of the hot cap 19 and/or of the piston 2 .

We also notice in as well as in Figures 3 to 7 and in Figures 9 and 10 that the sealed thermal insulation means 12 and/or the thermal insulation means 22 can consist of at least one insulating ring 13 made of a material with low thermal conductivity 14, said material 14 possibly consisting mainly of zirconium oxide 15.

As particularly shown in Figures 1, 9 and 10, the insulating ring 13 which forms the sealed thermal insulation means 12 can be directly or indirectly in contact with the cooled cylinder block 5 and/or with the hot cylinder head 10 by via at least one contact edge of small surface area 16 which prevents the working gas 17 from passing between the cooled cylinder block 5 and the hot cylinder head 10.

As another variant of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention, particularly visible in Figures 1, 9 and 10, the insulating ring 13 which forms the thermal insulation means 22 can also be directly or indirectly in contact with the hot cap 19 and/or with the piston 2 via at least one contact edge of small surface area 16, this to prevent the working gas 17 from passing between the hot cap 19 and the piston 2.

We also note in Figures 1, 9 and 10 that a cylinder head seal 18 can be interposed between the insulating ring 13 which forms the sealed thermal insulation means 12 and the cooled cylinder block 5 and/or between said ring 13 and the hot yoke 10.

Similarly, a piston seal 36 can be interposed between the insulating ring 13 which forms the thermal insulation means 22 and the hot cap 19 and/or between said ring 13 and the piston 2.

Note that the cylinder head seal 18 and/or the piston seal 36 can for example comprise several metal sheets like the cylinder head gaskets included in modern automobile internal combustion thermal engines, or be made of materials resistant to high temperatures such as “Therma-pur” developed by the company “Garlock”.

It will also be noted that the hot cylinder head 10 and/or the hot cap 19 may in whole or in part be made up of a material resistant to high temperatures 20, the latter possibly being mainly made up of silicon carbide 21.

According to a variant of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention particularly visible in Figures 9 and 10, the hot cylinder head 10 can have a concave conical cylinder head surface 25 by means of which said cylinder head 10 is held plated by the cylinder head plating means 24 on a circular cylinder contact edge 51 provided on the cooled cylinder block 5.

In this case, the angle of the concave cone formed by said surface 25 is such that when said surface 25 slides on said edge 51 due to the difference between the thermal expansion of said cylinder head 10 and that of said cylinder block 5, the axial distance which separates the point of support of the cylinder head plating means 24 on the hot cylinder head 10 from the cooled cylinder block 5 remains approximately constant all other things being equal, while the concave conical surface of cylinder head 25 and the circular edge cylinder contact 51 form the cylinder head centering means 39.

It will be noted that this particular configuration of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention allows the force to which the cylinder head plating means 24 are subjected to remains approximately constant whatever the difference between the thermal expansion of the hot cylinder head 10 and that of the cooled cylinder head 5, said difference resulting from both a temperature and a coefficient of thermal expansion possibly different between those of the hot cylinder head 10 and those of the cooled cylinder head 5.

In addition, said configuration makes it possible to limit the variation in volumetric ratio of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention as a function of its temperature, particularly during the cold start phases of said engine 1.

Note that advantageously, the circular cylinder contact edge 51 can present a spherical contact with the concave conical surface of the cylinder head 25.

As another variant of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention, particularly visible in Figures 9 and 10, the hot cap 19 can also have a concave conical surface of cap 26 through which said cap 19 is kept pressed by the cap plating means 23 on a circular piston contact edge 52 provided on piston 2.

In this case, the angle of the concave cone formed by said surface 26 is such that when said surface 26 slides on said edge 52 due to the difference between the thermal expansion of said cap 19 and that of piston 2, the axial distance which separates the point of support of the cap pressing means 23 on the hot cap 19 of the piston 2 remains approximately constant all other things being equal, while the concave conical surface of the cap 26 and the circular piston contact edge 52 form the cap centering means 40.

Note that this particular configuration of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention allows the force to which the cap plating means 23 are subjected to remains approximately constant whatever the difference between the thermal expansion of the hot cap 19 and that of piston 2.

In addition, said configuration makes it possible to limit the variation in volumetric ratio of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention as a function of its temperature, particularly during the cold start phases of said engine 1.

Note that advantageously, the circular piston contact edge 52 can present a spherical contact with the concave conical surface of the cap 26.

As shown in the , as an alternative embodiment of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention, the hot cap 19 can have at its periphery an aerodynamic passivation cord 53 which limits the turbulence of the working gas 17 in the vicinity of the cold cylinder 6 and which, therefore, limits the convective forcing which increases the loss of part of the heat of said gas 17 by transfer of said heat to said cold cylinder 6.

There also illustrates that the exterior of the hot cylinder head 10 can be covered with a thermal insulator 41 which prevents the heat of said cylinder head 10 from dissipating in the environment of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention .

Said thermal insulator 41 can for example consist of several layers of thin metal sheets comprising pins which leave an air gap between each said sheet, or be any other thermal insulator 41 known to those skilled in the art.

We notice in , in Figures 2 to 7, and in Figures 9 and 10, that the piston sealing ring 37 can have piston guide means 29 consisting of an annular sliding surface 43 which has a barrel shape on contact of the cold cylinder 6, said shape being able to be positioned between two compression segments 44 and adjoining an oil scraper segment 45.

According to a particular configuration of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention shown in Figures 2 to 10, the cooled cylinder block 5 can be held enclosed between a lower hot cylinder head 10 and an upper hot cylinder head 10 by the cylinder head plating means 24 while the piston 2 is double-acting and comprises on the one hand, a lower piston rod 46 which connects it to the power transmission means 3 and which passes right through the lower hot cylinder head 10 via a lower rod orifice 47, and on the other hand, a lower hot cap 19 and an upper hot cap 19 to define with the lower and upper hot yokes 10 a lower hot chamber of variable volume 11 and a hot chamber of variable volume 11 superior.

Still according to this particular configuration, the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention comprises at least one hollowed pillar 101 which can be either completely closed or perforated, said pillar 101 being crossed right through in the direction of its length by a rod tunnel 102.

In this case, a first end of pillar 103 of the hollowed pillar 101 rests directly or indirectly on the transmission casing 42 while a second end of pillar 104 of said pillar 101 supports the lower hot cylinder head 10, said first end 101 being able to pivot around of a ball joint 105 and/or flex relative to said casing 42 while said second end 104 can pivot around a ball joint 105 and/or flex relative to said lower hot cylinder head 10.

It will be noted that the pivoting of said ends 103, 104 can be carried out either by means of a mechanical connection of the pivot or cardan type or by a ball joint 105, or by the bending of all or part of the hollowed pillar 101, or by both.

According to a particular embodiment of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention, the hollowed pillar 101 can be made of zirconium dioxide called "zirconia", this ceramic offering good mechanical resistance at high temperature, a low thermal conductivity, and an expansion coefficient close to that of steel.

Still in this case, at least one traction rod 106 forms the cylinder head plating means 24, said rod 106 being, at least in part, housed in the rod tunnel 102, a first end of rod 107 of said rod 106 being directly or indirectly secured to the transmission casing 42 while a second end of rod 108 of said rod 106 is directly or indirectly secured to the upper hot cylinder head 10, said first end 107 being able to pivot around a ball joint 105 and/or flex relative to said casing 42 while said second end 108 can pivot around a ball joint 105 and/or flex relative to said cylinder head 10, the pivoting of said ends 107, 108 therefore being able to take place either by means of a connection mechanical pivot or cardan type or a ball joint 105, either by the bending of all or part of the traction rod 106, or by both.

As shown in the , we note that to be secured to the upper hot cylinder head 10, the second end of the rod 19 can pass through an ear orifice 144 which includes a fixing ear 117 which said cylinder head 10 has, while either a rod head 145 or a rod nut 147 screwed onto a rod thread 146 arranged on the traction rod 106 bears on said ear 117.

We also note in that the first rod end 107 can be secured to the transmission housing 42 also by means of a rod head 145, or a rod nut 147 screwed onto a rod thread 146.

Alternatively, said rod thread 146 can be screwed into a tapping directly or indirectly made in the transmission housing 42.

According to a particular embodiment of the double-acting expansion cylinder 1 according to the invention, a compression spring 148 can be inserted either between the rod head 145 or the rod nut 147 and the fixing ear 117, or between said head 145 or any other tapped part into which the rod thread 146 is screwed, and any other supporting part.

As illustrated by , said spring 148 may consist of one or more “Belleville” washers.

Such a spring 148 can in particular limit the tension to which the traction rod 106 is subjected when the various members that it holds tight together expand under the effect of their rise in temperature.

Still in the case shown in Figures 2 to 10 where the cooled cylinder block 5 is held enclosed between a hot lower cylinder head 10 and a hot upper cylinder head 10 while the piston 2 is double-acting, the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention comprises lower cylinder head centering means 109 which are integral with the transmission casing 42 and which directly or indirectly bear on the lower hot cylinder head 10, said means 109 leaving said cylinder head 10 free to move on a short distance parallel to the longitudinal axis of the cold cylinder 6 and relative to the transmission casing 42, but preventing said cylinder head 10 from moving in the plane perpendicular to said axis relative to said casing 42.

Similarly, upper cylinder head centering means 110 integral with a centering gantry 127 which is rigidly fixed to the transmission casing 42 bear directly or indirectly on the upper hot cylinder head 10, said means 109 leaving said cylinder head 10 free from move over a short distance parallel to the longitudinal axis of the cold cylinder 6 and relative to the transmission casing 42, but preventing said cylinder head 10 from moving in the plane perpendicular to said axis relative to said casing 42.

In this case, as can be seen in Figures 2, 3, 7 and 8, a rod cooling tube 111 can sealingly envelop the traction rod 106 over all or part of the length of said rod 106, a heat transfer liquid 32 coming from a source of cooling liquid 113 capable of circulating in a space left between the internal wall of said tube 111 and the external surface of said rod 106 while the greatest possible part of the external surface of said tube 111 does not touch the internal wall of the rod tunnel 102 so as to define with this last wall a space empty or filled with atmospheric air, or filled with a gas of any nature whatsoever.

Thus, the heat transfer liquid 32 can cool the traction rod 106 and maintain it at a sufficiently low temperature so that the material constituting said rod 106 maintains its highest mechanical characteristics, while the empty space left between the external surface of the rod cooling tube 111 and the internal wall of the rod tunnel 102 limits the cooling of the hollowed pillar 101.

Note that according to a particular embodiment of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention, only a rod head 145 that the traction rod 106 can present could be cooled, said head 145 being directly or indirectly in contact with the upper hot cylinder head 10.

As was clearly shown in , at least one first tube feed port 114 can communicate with the interior of the rod cooling tube 111 in the vicinity of the first rod end 107, and at least one second tube feed port 115 can communicate with inside the rod cooling tube 111 in the vicinity of the second rod end 108, the heat transfer liquid 32 being able to circulate between the two said orifices 114, 115 while said liquid 32 is colder when it enters the cooling tube of rod 111 only when it comes out.

Note that a fluid pump can be provided to force the heat transfer liquid 32 to circulate in the rod cooling tube 111, said pump being able to continue to operate for a certain time after stopping the thermal machine to which it applies the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention.

This last arrangement makes it possible, for example, to evacuate the heat that the hot lower and upper cylinder heads 10 are likely to continue to transmit, during their cooling, to the traction rod 106.

Note that once it leaves the rod cooling tube 111, the heat transfer liquid 32 can be cooled by a heat exchanger before being reintroduced again into said tube 111, or renewed.

In , we note that the rod cooling tube 111 can include a tube collar 116 which is held directly or indirectly clamped by the traction rod 106 either against a fixing ear 117 which the upper hot cylinder head 10 presents, or against the crankcase transmission 42.

In this context, the tube collar 116 can be held tight by the traction rod 106 against the fixing ear 117 via a Banjo connector 118 which comprises at least one radial connection conduit 119 which is connected to the coolant source 113 on the one hand, and which communicates with the interior of the rod cooling tube 111 on the other hand.

Note that the radial connection conduit 119 can be connected to the source of coolant 113 or to other radial connection conduits 119 that the Banjo connection 118 comprises of other rod cooling tubes 111 by means of a flexible or deformable conduit which can accommodate variations in distance induced by the thermal expansion of the different members which constitute the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention.

Still in this context and as shown in , a thermal insulation extension 120 can be inserted between the tube collar 116 and the fixing ear 117, said extension 120 being crossed right through in the direction of its length by an extension tunnel 121 in which is housed the traction rod 106 and the rod cooling tube 111 which envelops it in a sealed manner, while the greatest possible part of the external surface of said tube 111 does not touch the internal wall of the extension tunnel 121 so as to define with this last wall a space empty or filled with atmospheric air, or filled with a gas of any nature whatsoever.

Note that the thermal insulation extension 120 can advantageously be made of a material resistant to high temperatures and offering low thermal conductivity such as zirconium dioxide.

There also shows that according to a variant embodiment of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention, the rod cooling tube 111 can comprise at least one tube bulge 122 consisting of an axial portion of said tube 111 of which the free diameter is substantially equivalent or even slightly greater than that of the rod tunnel 102 in which it is housed, which makes it possible to center said tube 111 in said tunnel 102 or even to locally produce a seal between said tube 111 and said tunnel 102.

Conversely, the rod cooling tube 111 may include at least one tube diameter restriction 123 consisting of an axial portion of said tube 111 whose free diameter is substantially equivalent or even slightly less than that of the body of the rod. traction 106 which makes it possible to center said tube 111 around said rod 106 or even to locally produce a seal between said tube 111 and said rod 106.

We note that as an alternative or complement and as clearly shown by , the stem cooling tube 111 can receive at least one tube seal 157 made of elastomer or plastic to perfect the seal formed between said tube 111 and the stem tunnel 102.

As a variant not shown, the traction rod 106 could be hollow to form an internal rod cooling channel arranged in the length of said rod 106, said channel opening out axially or radially in the vicinity of each end of said rod 106 while a heat transfer liquid 32 coming from a source of cooling liquid 113 could circulate in said channel and this, to cool the traction rod 106 and maintain it at a sufficiently low temperature so that the material constituting said rod 106 maintains its characteristics highest mechanics.

As illustrated in Figures 4, 6 and 7, a piston cooling and lubrication chamber 125 connected to a source of lubricating-cooling fluid 126 can be fixed on the centering gantry 127 or arranged on or in the latter while 'an upper piston rod 128 which extends the double-acting piston 2 on the side of the upper hot chamber of variable volume 11 passes through the upper hot cylinder head 10 via an upper rod orifice 129 arranged in said cylinder head 10 and via an orifice of access to the cooling and lubrication chamber 130 passing through the centering gantry 127 to open into the piston cooling and lubrication chamber 125 so that the end of the upper piston rod 128 which is furthest from said piston 2 always remains immersed in said chamber 128 whatever the position of said piston 2.

In this case, a lubricating-cooling fluid 139 can advantageously circulate from the piston cooling and lubrication chamber 125 to the transmission casing 42 passing successively via an internal upper piston rod channel 140 arranged longitudinally in the upper rod piston 128, via an internal piston cavity 141, and via an internal lower piston rod channel 142 arranged longitudinally in the lower piston rod 46.

As seen in Figures 3, 9 and 10, the periphery of the internal piston cavity 141 can communicate with the external peripheral face of the piston sealing ring 37 via at least one peripheral ring lubrication orifice 143 which opens axially between at least two piston sealing means 30, said orifice 143 constituting the lubricating means 8 and the sealing ring cooling means 38.

There shows that the transmission casing 42 can be fitted with a centering and sealing plate 131 pierced with an access orifice to the transmission means 132 through which the lower piston rod 46 passes to be connected to the means of power transmission 3, said plate 131 being rigidly fixed to said casing 42 by screws or by any other means known to those skilled in the art.

Alternatively, said plate 131 can form an integral part of said casing 42.

As shown in the , the access orifice to the cooling and lubrication chamber 130 may comprise rod sealing means 133 providing a seal between said orifice 130 and the upper piston rod 128.

There shows for its part that the access orifice to the transmission means 132 can comprise rod sealing means 133 providing a seal between said orifice 132 and the lower piston rod 46.

In Figures 5 and 6, we note that the lower cylinder head centering means 109 and/or the upper cylinder head centering means 110 can consist of an elastic centering disc 134 which can be pierced in its center with a hole of disc 135 through which the lower piston rod 46 or an upper piston rod 128 passes respectively while its periphery constitutes a disc fixing flange 136 fixed in a sealed manner respectively on the transmission casing 42 and/or on the gantry. centering 127.

We notice in that the centering and sealing plate 131 can carry the lower cylinder head centering means 109 which consist of an elastic centering disc 134 whose periphery forms a disc fixing flange 136 fixed in a sealed manner on said plate 131 , said disc 134 being pierced in its center with a disc hole 135 through which the lower piston rod 46 passes without touching said disc 134, the edge of the disc hole 135 having a circular contact pad 137 which is held in tight contact with a centering and sealing cone 138 which the lower hot cylinder head 10 presents, said cone 138 being able to be male or female, and the contact between said shoe 137 and said cone 138 having the effect of deforming axially and from its center the elastic centering disc 134.

Note that the disc fixing collar 136 can be fixed to the centering and sealing plate 131 by means of at least one screw, a clip, or any other fixing means known to those skilled in the art. .

Note that advantageously, the elastic centering disk 134 can be made of a material resistant to high temperatures and offering low thermal conductivity such as zirconium dioxide.

As illustrated by , the upper cylinder head centering means 110 can consist of an elastic centering disc 134 whose periphery forms a disc fixing flange 136 fixed in a sealed manner on the centering gantry 127, said disc 134 being pierced in its center a disc hole 135 whose edge has a circular contact pad 137 which is maintained in sealed contact with a centering and sealing cone 138 which the upper hot cylinder head 10 presents, said cone 138 being able to be male or female, and the contact between said pad 137 and said cone 138 having the effect of deforming axially and from its center the elastic centering disk 134.

Note that the disc fixing flange 136 can be fixed to the centering gantry 127 by means of at least one screw, a clip, or any other fixing means known to those skilled in the art.

Note that if the double-acting piston 2 is extended by an upper piston rod 128, the latter passes through the disc hole 135 without touching the elastic centering disc 134.

We further note that advantageously, the elastic centering disc 134 can be made of a material resistant to high temperatures and offering low thermal conductivity such as zirconium dioxide.

It can also be noted that as an alternative to what has just been described and whether it concerns the lower cylinder head centering means 109 or the upper cylinder head centering means 110, a contact pad similar to that presented the disc hole 135 can be arranged respectively either on the lower hot cylinder head 10, or on the upper hot cylinder head 10, while a centering and sealing cone similar to that present in said cylinder heads 10 is arranged on or in the elastic centering disc 134.

Note that the centering and sealing function provided by the elastic centering disc 134 can be entrusted for example to a split torus or not and made of steel or a superalloy, to an expandable washer consisting or not of multiple folds stacked radially and made of the same piece of metal or ceramic, with at least three needles pushed by a spring, distributed every one hundred and twenty degrees and cooperating with a sealing segment, and in general, to any solution capable of ensuring centering and sealing in the desired functional conditions while limiting heat loss from any hot room to any cold room.

As shown in Figures 2 and 7, an anti-rotation connection 149 can directly or indirectly connect the lower hot cylinder head 10 and/or the upper hot cylinder head 10 and/or the cooled cylinder block 5 to the centering gantry 127, said connection 149 which may for example consist of a pin or a link, and preventing the assembly formed by said cylinder heads 10 and the cooled cylinder block 5 from rotating around the longitudinal axis of the cold cylinder 6.

OPERATION OF THE INVENTION:

The operation of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention can be easily understood in view of Figures 1 to 10.

Said motor 1 may include a single-acting piston 2 as shown in or double-acting as illustrated in Figures 2 to 10. Said engine 1 can execute a Beau de Rochas, Miller, Atkinson, Diesel cycle, or any other thermodynamic cycle known to those skilled in the art. .

According to the particular embodiment of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention shown in Figures 2 to 10, the piston 2 is double-acting while said engine 1 executes a regenerative Brayton cycle which is identical to that carried out by the heat engine with transfer-expansion and regeneration according to patent No. WO2016120560.

In this particular context, the invention only applies to the regulator 28 of said engine 1, also, the other elements of the latter such as one or more compressors, a burner or a regeneration exchanger necessary for the implementation of the Brayton cycle with regeneration, are not shown.

The objective of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention is to limit as much as possible the heat losses of the working gas 17 by bringing as much of the internal wall surface as possible of the regulator 28 to high temperature, this while allowing the piston 2 to achieve a seal with the cold cylinder 6 by using conventional piston sealing means 30, in this case compression rings 44 and an oil scraper ring 45 similar to those which equip mass-produced automobile internal combustion engines.

We note, particularly in Figures 1, 3 and 4, that according to the particular embodiment of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention which is exposed there, the power transmission means 3 which are housed in the transmission casing 42 are provided to transform the back and forth movements carried out by a double-acting piston 2 in the cold cylinder 6, into the continuous rotational movement of a crankshaft 35.

According to this non-limiting example of a particular embodiment of said engine 1 according to the invention, the transmission casing 42 and the power transmission means 3 are maintained at a temperature close to one hundred degrees Celsius.

In Figures 3 and 4 and as an example of an embodiment of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention, we note here that the power transmission means 3 are advantageously made up of a connecting rod 34 which is connected to the double-acting piston 2 by a crosspiece 49 itself connected to said piston 2 by a lower piston rod 46, said connecting rod 34 being articulated around a crank 48 arranged on the crankshaft 35, the latter forming an output shaft of Power 4.

As can be clearly seen in Figures 3 and 4, the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention presented here has for the same cold cylinder 6 a lower hot cylinder head 10 which forms with the double-acting piston 2 a lower hot chamber of variable volume 11, and an upper hot cylinder head 10 which forms with said piston 2 an upper hot chamber of variable volume 11.

As can be understood in Figures 3 and 4, the cooled cylinder block 5 is held axially enclosed between the lower and upper hot cylinder heads 10, while the double-acting piston 2 receives a hot cap 19 on each of its lower and upper axial faces. upper, said caps 19 interposing between said piston 2 and the hot chamber of variable volume 11 with which they cooperate.

We will assume here that the working gas 17 is introduced into the expander 28 via an inlet valve 31 at a temperature of one thousand three hundred degrees Celsius, while the operational equilibrium temperature of the hot cylinder heads 10 and the hot caps 19 is nine hundred and fifty degrees Celsius.

Note that advantageously, the inlet valve 31 and an exhaust valve 33 by which the working gas 17 is expelled from the regulator 28 after having been expanded there can each be autoclaved, and be controlled by a valve actuator 50 regenerative hydraulics as described in patent No. 3071896 dated October 11, 2019 belonging to the applicant.

Unlike the heat engine with transfer-expansion and regeneration according to patent WO2016120560 of which all the internal walls of the expander are maintained at a high temperature of for example nine hundred and fifty degrees Celsius, the internal wall of the cold cylinder 6 of the expander 28 of the heat engine 1 according to the invention is maintained by the cylinder crankcase cooling means 9 at a relatively low temperature of only one hundred degrees Celsius, this temperature being given only by way of example.

In Figures 1, 3, 4, 9 and 10, it has been shown that the cylinder crankcase cooling means 9 can consist of a cooling chamber 27 which envelops the external surface of the cold cylinder 6, a heat transfer liquid 32 - in this case water - circulating in said chamber 27.

Thus and as clearly shown in Figures 3, 6, 9 and 10, practically all the internal walls of the regulator 28 of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention remain hot like those of the thermal engine. with transfer-expansion and regeneration according to patent WO2016120560, with the exception of the cold cylinder 6.

We also note in this respect that to avoid any loss of heat, the regulator 28 shown in Figures 2, 3, 4 and 7 comprises an articulated intake plenum 159 and an articulated exhaust plenum 159 made of silicon carbide 21 , said plenums 159 being arranged according to the principle of patent No. FR 3094416 published on March 5, 2021 and belonging to the applicant.

As such, Figures 2 to 4 clearly show that said plenums 159 are held pressed, on the one hand, on the lower or upper hot cylinder heads 10 depending on the case, and on the other hand, on a gas collector by flanges plenum elastics 158 held tight by screws and elastic plenum flange springs 56.

This particular arrangement allows said plenums 159, which provide the hot cylinder heads 10 and the collectors with a spherical bearing, to freely articulate around said cylinder heads 10 and said collectors to allow the constituent parts of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 to expand. according to the invention.

Likewise, we note in Figures 2, 3, 4 and 7 that the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention and according to a non-limiting exemplary embodiment, the valve actuators 50 are kept pressed on the articulated plenum 159 with which they cooperate by an elastic flange of actuators 54 and by elastic flange springs of actuators 55 with regard to said actuators 50 which control the inlet valve 31 and the exhaust valve 33 of the chamber hot chamber of variable volume 11 upper, and by an elastic actuator pusher 160 with regard to said actuators 50 which control the inlet valve 31 and the exhaust valve 33 of the hot chamber of variable volume 11 lower.

We also note that the elastic actuator pushers 160 are telescopic and are put under pressure by a nut which presses “Belleville” washers.

If, as was said previously, practically all the internal walls of the expander 28 remain hot with the exception of the cold cylinder 6, the remaining hot surfaces are sufficient to obtain a significantly higher thermodynamic efficiency from the regenerative Brayton cycle in practice. than that of the Otto and Diesel cycles.

We note in Figures 3, 4, 9 and 10 that the piston guide means 29 and the piston sealing means 30 of the piston 2 are also maintained at a temperature of the order of one hundred degrees Celsius, close to that of the cold cylinder 6, this in particular to preserve the integrity of the lubricant film 7 which covers the internal wall of said cylinder 6.

We therefore understand that, unlike the heat engine with transfer-expansion and regeneration according to patent WO2016120560, the piston sealing means 30 no longer consist of a fluid cushion sealing device according to patent FR 3032252, but well of a segmentation comparable to that of conventional automobile internal combustion engines, said means 30 being cooled and lubricated in the same way.

This similarity allows the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention to benefit from know-how more than a century old in the field of segmentation of internal combustion engine pistons.

The particular configuration of said engine 1 is justified in that, under the temperature conditions which have just been described, the heat transferred to the cold cylinder 6 by the working gas 17 forms an energy loss comparable or even lower than that induced by a on the one hand, by the fluid cushion sealing device subject to patent FR 3032252 because of the compression means necessary for its compressed air supply, and on the other hand, by the regenerative cooling system according to patent No. EP 3585993 due to the additional exhaust pressure losses that it generates, and the reintroduction into the thermodynamic cycle of the heat extracted from the internal walls of the expander via a regeneration heat exchanger whose efficiency is less than one.

As proof of the merits of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention, we note that if all the internal walls of the regulator 28 shown in Figures 3 to 7 and in Figures 9 and 10 - including the cylinder heads hot 10 lower and upper and the hot caps 19 - were maintained at only one hundred degrees Celsius like the internal walls of mass-produced automobile internal combustion engines, the average surface-specific heat output – for example expressed in kilowatts per square meter - released by the working gas 17 to the cold cylinder 6, would be much lower than that released by said gas 17 to said hot cylinder heads 10 and to said hot caps 19.

Indeed, the surface that the cold cylinder 6 exposes to the working gas 17 is small at the start of expansion of said gas 17, then increases as said gas 17 expands and at the same time, its temperature drops, unlike the hot cylinder heads 10 and hot caps 19 whose surface exposed to the working gas 17 remains constant.

Thus, assuming that said cylinder heads 10 and said caps 19 are voluntarily maintained at one hundred degrees Celsius during expansion, the specific cooling power at the surface would be much lower at the level of the internal walls of the cold cylinder 6 than at the level of those said hot cylinder heads 10 and said hot caps 19.

Furthermore, according to the particular configuration of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 shown in Figures 2 to 10, the piston 2 is double-acting and not single-acting, which minimizes the surface of the cold cylinder 6 relative to the cumulative surface area of the hot cylinder heads 10 and the hot caps 19.

Indeed, the cold cylinder 6 being common to the hot chambers of variable volume 11 lower and upper, its surface is here worth less than thirty percent of the total internal surface of the regulator 28 which comes into contact with the working gas 17.

We also observe that, at identical maximum power, the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention being equipped with a double-acting piston 2 as shown in Figures 2 to 7 and in Figures 9 and 10, and executing a regenerative Brayton cycle, the internal surface presented by its cold cylinder 6 is smaller than the internal surface of the cylinder of a conventional Otto cycle or Diesel engine.

This reduces the relative thermal losses attributable to said cold cylinder 6.

In addition, the maximum temperature reached by the gases in the cylinder of an Otto cycle or conventional Diesel engine is of the order of two thousand five hundred degrees Celsius compared to only around one thousand three hundred degrees Celsius when it comes to of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 executing a regenerative Brayton cycle.

All things being equal, this lower temperature further reduces the heat losses of the working gas 17 in contact with the cold cylinder 6.

Furthermore, it will be noted that unlike the hot cylinder heads 10 and the hot caps 19, the cold cylinder 6 of the reciprocating thermal engine with a hot cylinder head and cold cylinder 1 according to the invention is located in a zone of low turbulence of the working gas 17 during of the introduction of said gas 17 into one or other hot chamber of variable volume 11 via the corresponding inlet valve 31, or during the expulsion of said gas 17 out of said chamber 11 via the exhaust valve 33.

This low intensity turbulence limits the convective forcing and the transfer of heat by the working gas 17 to the cold cylinder 6.

It will also be noted that, unlike conventional Otto or Diesel cycle engines, the turbulence of the gases introduced into the regulator 28 does not need to be forced by movements known to those skilled in the art. under the Anglo-Saxon terms of “tumble”, “swirl” or “squish”, to promote any combustion whatsoever.

Indeed, to the extent that the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention executes a regenerative Brayton cycle - which is its primary purpose - the combustion or reheating of the working gas 17 takes place by means of a hot source located upstream of the regulator 28 and not in said regulator 28, said source being able to consist of a burner, a heat exchanger or even and by way of non-limiting example, of a solar radiation concentration sensor.

The non-need to create voluntary turbulence to promote combustion therefore further reduces the thermal losses of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention executing a regenerative Brayton cycle compared to those of a conventional engine. with an Otto or Diesel cycle, and this, due to less convective forcing between the working gas 17 and the internal wall of the cold cylinder 6.

That being said, to benefit from the advantages of the reciprocating thermal engine with hot cylinder head and cold cylinder 1, we understand that said engine 1 requires the cooperation of hot parts and cold parts distant from each other by only a few millimeters.

To demonstrate how the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention allows this cooperation of hot parts and cold parts very close to each other, we will assume here that the cooled cylinder block 5 is made of cast iron, however, the hot cylinder heads 10 and the hot caps 19 are made of silicon carbide 21, the body of the piston 2 being made of steel with high mechanical characteristics.

Remember that silicon carbide retains its mechanical characteristics up to temperatures of around one thousand four hundred degrees Celsius, and can be used in an oxidizing environment up to these high temperatures.

We will also assume here that the internal diameter of the cold cylinder 6 is two hundred and forty millimeters.

The proximity of hot and cold rooms reveals a double issue linked to differential expansions and the limitation of thermal losses.

Let us take for example the case of the upper hot cylinder head 10 of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention, according to its particular configuration shown in Figures 2 to 10.

Said hot cylinder head 10 and the cold cylinder 6 with which it cooperates are both manufactured at a temperature of around twenty degrees Celsius.

However, in operation, the temperature of the cold cylinder 6 stabilizes at one hundred degrees Celsius while that of the hot cylinder head 10 stabilizes at nine hundred and fifty degrees Celsius.

Taking into account the expansion coefficients of the materials constituting the hot cylinder head 10 of the cold cylinder 6, these temperatures lead to differences in hot diameter between that of the hot cylinder head 10 and that of the cold cylinder 6 of almost a millimeter.

Likewise, under the effect of the temperature, the total height of the lower and upper hot cylinder heads 10 also increases by around a millimeter, such a variation in height being difficult to absorb by the cylinder head plating means. 24 which must also take up the axial forces generated by the pressure of the working gas 17 in the lower and upper hot chambers of variable volume 11.

Furthermore, the close proximity between the lower and upper hot cylinder heads 10 and the cold cylinder 6 is likely to promote heat transfers from said cylinder heads 10 to said cylinder 6, said transfers being harmful to the thermodynamic efficiency of the regenerative Brayton cycle. .

The reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention meets this double need on the one hand, to absorb significant differences in expansion between various parts kept in contact with each other and operating at very different temperatures, and on the other hand, to limit heat exchanges between said parts.

Indeed, as we see in Figures 2 to 4 and in Figures 7 and 8, said motor 1 comprises hollowed out pillars 101 for example made of stainless steel, which are crossed right through in the direction of their length by a tunnel of rod 102, a first end of pillar 103 of said pillar 101 resting on the transmission casing 42 via a ball joint 105 while a second end of pillar 104 of said pillar 101 supports the lower hot cylinder head 10, also by via a ball joint 105.

The hollow pillars 101 being of great length, they form a thermal barrier and limit the transfer of heat by the hot cylinder head 10 lower than the transmission casing 42.

In Figures 1, 2, 7 and 8, we notice the traction rods 106 which form the cylinder head plating means 24, said rods 106 being each partly housed in the rod tunnel 102 of the hollowed pillar 101 with which they cooperate, a first rod end 107 of each said pull rod 106 being secured to the transmission housing 42 by means of a rod thread 146 and a rod nut 147, and via a compression spring 148 here made up of a stack of “Belleville” washers.

Note that a rod cooling tube 111 sealingly envelops each traction rod 106 over most of its length, a heat transfer liquid 32 supplied by a source of cooling liquid 113 at a temperature close to one hundred degrees Celsius circulating in a space left between the internal wall of said tube 111 and the external surface of said rod 106, while the majority of the external surface of said tube 111 does not touch the internal wall of the rod tunnel 102 so as to define with the latter wall an empty space.

As we see in , a first tube feed port 114 communicates with the interior of the rod cooling tube 111 in the vicinity of the first rod end 107 while a second tube feed port 115 communicates with the interior of the tube cooling rod 111 in the vicinity of the second end of the rod 108, the heat transfer liquid 32 being able to circulate between the two said orifices 114, 115.

In , it has been shown that according to the alternative embodiment of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention explained here, the rod cooling tube 111 can advantageously comprise a tube collar 116 held tight by the traction rod 106 and via a thermal insulation extension 120 against a fixing ear 117 which the upper hot cylinder head 10 presents.

As shown in the , the tube collar 116 is here held tight by the traction rod 106 against the fixing ear 117 via a Banjo connection 118 which comprises a radial connection conduit 119 which is connected to the source of liquid cooling 113 on the one hand, and which communicates with the interior of the rod cooling tube 111 on the other hand.

We notice in that the rod cooling tube 111 comprises several tube bulges 122 consisting of an axial portion of said tube 111 whose free diameter is slightly greater than that of the rod tunnel 102 in which it is housed, which makes it possible to center said tube 111 in said tunnel 102.

We notice in zone “D” of the that the rod cooling tube 111 comprises a first tube feed orifice 114 located between two tube bulges 122, said first orifice 114 communicating with the interior of the rod cooling tube 111 in the vicinity of the first rod end 107 on the one hand, and being connected to a source of coolant 113 like that shown in , by channels arranged in the transmission casing 42 on the other hand.

On the side of the first end of rod 107, we note that the rod cooling tube 111 on the contrary comprises a tube diameter restriction 123 consisting of an axial portion of said tube 111 whose free diameter is slightly less than that of the body of the traction rod 106 which makes it possible to center said tube 111 around said rod 106 and to locally produce a seal between said tube 111 and said rod 106.

Advantageously, said tube diameter restriction 123 can be supplemented with an elastomer tube seal 157 or replaced by the latter in order to guarantee a perfect seal between the traction rod 106 and the rod cooling tube 111.

Thus constituted, the traction rod 106 can operate at a temperature close to one hundred degrees Celsius whatever the temperature of the lower and upper hot yokes 10, and be made of a steel with high mechanical characteristics, this without risk of soaking said steel.

In any case, this particular configuration which makes it possible to cool the traction rod 106 may prove useless if the latter is made of a material resistant to high temperatures such as "zirconia", silicon carbide, alumina or any superalloy specifically developed for this type of use.

Advantageously, the ball joints 105 which are in contact with the lower and upper hot yokes 10 can be made of a material with very low thermal conductivity such as Zirconium oxide, this to limit the passage of heat from the lower and upper hot yokes 10 towards the hollowed-out pillars 101 and the traction rods 106.

As can be seen in Figures 1, 2, 7 and 8, thermal insulation extensions 120 can actually be inserted between the traction rods 106 and the upper hot cylinder head 10, in order to reduce the heat flow passing from said cylinder head 10 towards the traction rods 106, the latter being in this case housed in an extension tunnel 121 which passes right through said extensions 120 in the direction of their length.

This particular configuration is specified in , on which we see that each hollow pillar 101 actually has two ball joints 105 around which it is articulated.

We note in zone “D” of said that between the first end of pillar 103 of said pillar 101 and the transmission casing 42 a first ball joint 105 is inserted while the zone “C” of the same shows that between the second end of pillar 104 of said pillar 101 and the lower hot yoke 10 a second ball joint 105 is inserted.

There also shows that each hollow pillar 101 is actually crossed right through in the direction of its length by a rod tunnel 102 in which a traction rod 106 is housed.

As illustrated in zone “D” of said , the first rod end 18 of the traction rod 107 is secured to the transmission housing 42 via a first ball joint 105.

Zone “A” of the recalls for its part that the second end of the rod 108 is indirectly secured to the upper hot cylinder head 10 via a rod head 145, a ball joint 105, and a thermal insulation extension 120 .

The rod head 145 keeps the lower hot cylinder head 10 and the upper hot cylinder head 10 pressed against the cooled cylinder block 5, the latter finding itself sandwiched between the two said cylinder heads 10.

This is made possible in particular thanks to fixing ears 117 which said cylinder heads 10 include, said ears 117 having an ear orifice 144 crossed by the traction rod 106.

Zones “B” and “C” of the illustrate this arrangement in a particularly obvious way.

Thus, the different ball joints 105 around which the four hollow pillars 101 are articulated and the traction rod 106 with which they cooperate allow the lower and upper hot cylinder heads 10 to expand freely, in particular with respect to the transmission casing 42.

This can occur, however, when the hollowed-out pillars 101 transmit traction and compression forces to said casing 42, said forces coming from the pressure exerted by the working gas 17 alternately on the lower hot cylinder head 10, and on the upper hot cylinder head 10 .

As can be seen in Figures 9 and 10, the expansion of the lower and upper hot cylinder heads 10 has little or no influence on the total length of the assembly which together constitutes said cylinder heads 10 and the cooled cylinder block 5.

This results from the fact that said cylinder head 10 each has a concave conical cylinder head surface 25 by means of which said cylinder head 10 is held pressed by the traction rods 106 on a circular cylinder contact edge 51 provided on the cylinder block. cooled 5.

The angle of the concave cone formed by said surface 25 has been previously calculated so that when said surface 25 slides on said edge 51 due to the difference between the thermal expansion of one or the other cylinder head 10 and that of said casing -cylinder 5, the distance which separates the rod head 145 from the cooled cylinder block 5 remains approximately constant, all other things being equal.

Whatever the differential expansion between that of said lower and upper cylinder heads 10 and that of the cooled cylinder block 5, the circular cylinder contact edge 51 and the respective concave conical cylinder head surfaces 25 of said cylinder heads 10 guarantee that the latter always remain centered on the cooled cylinder block 5.

As such, the concave conical cylinder head surface 25 and the circular cylinder contact edge 51 form the cylinder head centering means 39 of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention.

As clearly shown in Figures 9 and 10, the cylinder head centering means 39 and the insulating ring 13 which forms the sealed thermal insulation means 12 can become one, the circular cylinder contact edge 51 forming integral part of said ring 13, the latter constituting a thermal barrier which drastically limits heat transfers from the hot cylinder heads 10 to the cooled cylinder block 5.

Note that the advantageous arrangements which have just been described can only function correctly with the lower cylinder head centering means 109 secured to the transmission casing 42 which are particularly visible in , and with the upper cylinder head centering means 110 as shown in which are also secured to said casing 42 via a centering gantry 127 rigidly fixed to said casing 42.

Said means 109, 110 ensure centering and parallelism with respect to the transmission casing 42 of the assembly formed by the hot lower and upper cylinder heads 10 and the cooled cylinder casing 5.

Said means 109, 110 each consist of an elastic centering disc 134 pierced in its center with a disc hole 135 through which the lower piston rod 46 on the side of the lower hot cylinder head 10 passes without touching said disc 134 , and an upper piston rod 128 on the side of the upper hot cylinder head 10.

As seen in Figures 5 and 6, the periphery of the elastic centering discs 134 forms a disc fixing flange 136 which is fixed in a sealed manner either on the transmission casing 42 or on the centering gantry 127 depending on the case. .

Figures 5 and 6 show that the edge of the disc hole 135 has a male circular contact pad 137 which is maintained in sealed contact with a female centering and sealing cone 138 which the lower and upper hot cylinder heads 10 have, the contact between said shoe 137 and said cone 138 having the effect of slightly axially deforming the elastic centering disc 134 from its center and in its area of elasticity, and of preventing the working gas 17 contained in the hot chambers from variable volume 11 lower and upper to escape from said chambers 11.

In Figures 5 and 6, we will have noticed the relatively large radial length left on the elastic centering disc 134 between its disc fixing flange 136 and its contact pad 137.

This length is necessary so that said disc 134 can deform without damage axially from its center, and is also useful to limit as much as possible the transfer of heat from the centering and sealing cone 138 to said flange 136.

As such, the body of the elastic centering disc 134 is preferably thin, and can be made of zirconium oxide known for its low thermal conductivity.

It will also be noted that the narrow linear contact made between the centering and sealing cone 138 and the contact pad 137 also constitutes in itself an effective thermal barrier.

According to this particular configuration of the reciprocating thermal engine with hot cylinder head and cold cylinder 1 according to the invention, the assembly formed by the lower and upper hot cylinder heads 10 and the cooled cylinder block 5 can substantially expand longitudinally or move relative to the transmission casing 42 over a very short distance parallel to the longitudinal axis of the cold cylinder 6, but said assembly cannot in any case move in the plane perpendicular to said axis relative to said casing 42.

We also note in Figures 2 and 7 the anti-rotation connection 149 which connects the cooled cylinder block 5 to the centering gantry 127, this to prevent said assembly from rotating around the longitudinal axis of the cold cylinder 6.

As we see in , the elastic centering disc 134 of the lower hot cylinder head 10 cooperates with a centering and sealing plate 131 rigidly fixed on the transmission casing 42, said plate 131 being pierced with an access orifice to the transmission means 132 through which the lower piston rod 46 passes to be connected to the power transmission means 3.

Note that the access orifice to the transmission means 132 comprises rod sealing means 133 which here take the form of two cut segments 150 which are held pressed against each other by a clamping spring of segments 156 and whose cuts are offset, said segments 150 providing a seal between said orifice 132 and the lower piston rod 46.

As we see in , the elastic centering disc 134 of the upper hot cylinder head 10 is for its part fixed on the centering gantry 127 which has an access orifice to the cooling and lubrication chamber 130 through which the upper piston rod 128 passes to open into a piston cooling and lubrication chamber 125 connected to a source of lubricating-cooling fluid 126.

On the , we note that the access orifice to the cooling and lubrication chamber 130 also has rod sealing means 133 which also take the form of two cut segments 150 whose cuts are offset, said segments 150 being here also kept pressed against each other by a segment plating spring 156.

As is easily understood from Figures 5 and 6, the lower piston rod 46 and the upper piston rod 128 are respectively lubricated, sealed and cooled by lubricant which resides and/or circulates in the transmission housing 42 and in the piston cooling and lubrication chamber 125.

As shown in Figures 9 and 10, the principles which prevail at the level of the lower and upper cylinder heads 10 and at the level of the cooled cylinder block 5 are also found at the level of the double-acting piston 2.

We note in said figures that the piston sealing ring 37 which is arranged on the periphery of the piston 2 comprises piston sealing means 30 here formed of piston segments 151 similar to those included in conventional internal combustion engines with spark ignition or compression.

The piston seal ring 37 is maintained at a temperature close to one hundred degrees Celsius by a lubricating-cooling fluid 139 - in this case oil - which circulates from the piston cooling and lubrication chamber 125 up to 'to the transmission housing 42 passing respectively via an internal upper piston rod channel 140 arranged longitudinally in the upper piston rod 128, via an internal piston cavity 141, and via an internal lower piston rod channel 142 arranged longitudinally in the lower piston rod 46.

It should be noted that when the reciprocating heat engine with hot cylinder head and cold cylinder 1 as explained here by way of example stops, the source of lubricating-cooling fluid 126 which ensures the circulation of the lubricating-cooling fluid 139 from the piston cooling and lubrication chamber 125 to the transmission casing 42 via the internal piston cavity 141, can continue to circulate said fluid 139 to cool the constituent parts of the double-acting piston 2 and this, as long as the hot cylinder heads 10 and the lower and upper hot caps 19 continue to transmit heat to said organs and risk bringing the lubricating-cooling fluid 139 contained in said organs to coking or even combustion temperature.

We note, particularly in Figures 9 and 10, that the periphery of the internal piston cavity 141 communicates with the external peripheral face of the piston sealing ring 37 via peripheral ring lubrication orifices 143 which open axially between two piston rings 151, while said orifices 143 constitute both the lubricating means 8 and at least part of the sealing ring cooling means 38.

It will be noted that the piston seal ring 37 has - between the two piston rings 151 - piston guide means 29 which guide the piston 2 in the cold cylinder 6, said means 29 here being constituted by a surface of annular sliding 43 in a barrel shape which promotes the hydrodynamic lift of the lubricant film 7 interposed between said surface 43 and said cylinder 6.

We also note - as easily visible in Figures 5, 6, 9 and 10 - that an oil scraper ring 152 can advantageously be interposed between the annular sliding surface 43 and the piston ring 151 which is placed on the side of the lower hot chamber of variable volume 11, the peripheral ring lubrication orifices 143 opening between two lips presented by said scraper segment 152.

The oil scraper segment 152 has the dual function of spreading the lubricating-cooling fluid 139 on the internal wall of the cold cylinder 6, while recovering said fluid 139 present in excess on said wall.

As seen in Figures 9 and 10, the lower and upper hot caps 19 have a concave conical surface of cap 26 through which they are each held pressed by the cap plating means 23 on a circular contact edge of piston 52 fitted on piston 2.

We note in Figures 3, 7, 9, and 10 that the cap plating means 23 are here made up of a double-acting piston axial screw 153 which, on the one hand, fixes the double-acting piston 2 on the stock 49, and which on the other hand, presses the lower and upper hot caps 19 on the piston sealing ring 37 via cap plating tubes 154 and cap plating springs 155, said springs 155 being in this case made up of a stack of “Belleville” washers.

Figures 9 and 10 show that, whether it is the lower or upper hot cap 19, the angle of the concave cone formed by the concave conical surface of the cap 26 has been previously calculated so that when said surface 26 slides on the circular piston contact edge 52 with which it cooperates, due to the difference between the thermal expansion of said cap 19 and that of the piston 2, the distance which separates the head from the double-acting piston axial screw 153 of the point of support of the cap plating means 23 on the hot cap 19 remains approximately constant, all things being equal, so that the cap plating springs 155 find themselves neither more compressed nor more relaxed.

Thus, all things being equal, the tensile force to which the double-acting piston axial screw 153 is subjected remains approximately constant whatever the difference in thermal expansion between that of the lower and upper hot caps 19, and that of piston 2.

According to this particular configuration of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention, the concave conical surface of the cap 26 and the circular piston contact edge 52 form the cap centering means 40.

The possibilities of the reciprocating heat engine with hot cylinder head and cold cylinder 1 according to the invention are not limited to the applications which have just been described and it must also be understood that the preceding description has only been given 'by way of example and that it in no way limits the field of said invention from which one would not escape by replacing the details of execution described by any other equivalent.

Claims (36)

Reciprocating thermal engine with hot cylinder head and cold cylinder (1) comprising a cooled cylinder block (5) in which is arranged at least one cold cylinder (6) in which a piston (2) oriented and/or located by guide means piston (29) can translate, said piston (2) being directly or indirectly connected by power transmission means (3) housed in a transmission housing (42) to at least one rotary power output shaft (4) or alternative,characterized in thatHe understands :

• Lubrication means (8) which form a film of lubricant (7) which is interposed between the cold cylinder (6) and the piston (2);

• Cylinder crankcase cooling means (9) which cools the cooled cylinder crankcase (5) so as to maintain all or part of the internal surface of the cold cylinder (6) at a sufficiently low temperature so that the lubricant film ( 7) does not age prematurely, coking, or burning;
• At least one hot cylinder head (10) whose operating temperature is significantly higher than that of the cooled cylinder block (5) which it covers to form with the piston (2) a hot chamber of variable volume (11) which contains a working gas (17), said cylinder head (10) being on the one hand kept pressed against the cooled cylinder block (5) by means of cylinder head clamping (24) which leave it free to expand relative to said crankcase -cylinder (5), and on the other hand, located relative to said cylinder block (5) by cylinder head centering means (39);
• At least one piston sealing ring (37) arranged on the periphery of the piston (2), said ring (37) comprising on the one hand, piston sealing means (30) which form a seal between the piston ( 2) and the cold cylinder (6), and being on the other hand cooled by sealing ring cooling means (38);
• At least one hot cap (19) which is interposed between the hot chamber of variable volume (11) and the piston (2) and whose operating temperature is significantly higher than that of the cooled cylinder block (5), said cap ( 19) being on the one hand, held pressed against the piston (2) by cap-plating means (23) which leave said cap (19) free to expand relative to said piston (2), and on the other hand , located relative to said piston (2) by cap centering means (40).

Reciprocating thermal engine according to claim 1, characterized in that sealed thermal insulation means (12) are interposed between the cooled cylinder block (5) and the hot cylinder head (10). Reciprocating heat engine according to claim 1, characterized in that thermal insulation means (22) are interposed between the hot cap (19) and the piston (2)). Alternative thermal engine according to claim 2 or 3,characterized in thatthe sealed thermal insulation means (12) and/or the thermal insulation means (22) consist of at least one insulating ring (13) made of a material with low thermal conductivity (14). Reciprocating heat engine according to Claim 4, characterized in that the low thermal conductivity material (14) consists mainly of zirconium oxide (15). Reciprocating thermal engine according to claim 4, characterized in that the insulating ring (13) which forms the sealed thermal insulation means (12) is directly or indirectly in contact with the cooled cylinder block (5) and/or with the hot cylinder head (10) via at least one small surface contact edge (16) which prevents the working gas (17) from passing between the cooled cylinder block (5) and the hot cylinder head (10 ). Reciprocating heat engine according to claim 4, characterized in that the insulating ring (13) which forms the thermal insulation means (22) is directly or indirectly in contact with the hot cap (19) and/or with the piston ( 2) via at least one small surface contact edge (16). Reciprocating thermal engine according to claim 4, characterized in that a cylinder head seal (18) is interposed between the insulating ring (13) which forms the sealed thermal insulation means (12) and the cylinder block cooled (5) and/or between said ring (13) and the hot cylinder head (10). Reciprocating heat engine according to claim 4, characterized in that a piston seal (36) is interposed between the insulating ring (13) which forms the thermal insulation means (22) and the hot cap (19). ) and/or between said ring (13) and the piston (2). Reciprocating heat engine according to claim 1, characterized in that the hot cylinder head (10) and/or the hot cap (19) are entirely or partly made of a material resistant to high temperatures (20). Reciprocating heat engine according to Claim 10, characterized in that the high temperature resistant material (20) consists mainly of silicon carbide (21). Reciprocating heat engine according to claim 1, characterized in that the hot cylinder head (10) has a concave conical cylinder head surface (25) by means of which said cylinder head (10) is kept pressed by the cylinder head plating means ( 24) on a circular cylinder contact edge (51) provided on the cooled cylinder crankcase (5), the angle of the concave cone formed by said surface (25) being such that when said surface (25) slides on said edge (51) due to the difference between the thermal expansion of said cylinder head (10) and that of said cylinder block (5), the axial distance which separates the point of support of the cylinder head plating means (24) on the hot cylinder head (10) of the cooled cylinder block (5) remains approximately constant all other things being equal, while the concave conical cylinder head surface (25) and the circular cylinder contact edge (51) form the centering means cylinder head (39). Reciprocating heat engine according to claim 1, characterized in that the hot cap (19) has a concave conical cap surface (26) by means of which said cap (19) is kept pressed by the cap plating means ( 23) on a circular piston contact edge (52) provided on the piston (2), the angle of the concave cone formed by said surface (26) being such that when said surface (26) slides on said edge (52) due to the difference between the thermal expansion of said cap (19) and that of the piston (2), the axial distance which separates the point of support of the cap plating means (23) on the hot cap (19) of the piston (2) remains approximately constant, all other things being equal, while the concave conical surface of the cap (26) and the circular piston contact edge (52) form the cap centering means (40). Reciprocating heat engine according to claim 1, characterized in that the hot cap (19) has at its periphery an aerodynamic passivation cord (53). Reciprocating heat engine according to claim 1, characterized in that the exterior of the hot cylinder head (10) is covered with a thermal insulator (41). Reciprocating heat engine according to Claim 1, characterized in that the piston sealing ring (37) has piston guiding means (29) consisting of an annular sliding surface (43). Reciprocating thermal engine according to claim 1, characterized in that the cooled cylinder block (5) is held between a lower hot cylinder head (10) and an upper hot cylinder head (10) by the cylinder head plating means (24), however that the piston (2) is double-acting and comprises on the one hand, a lower piston rod (46) which connects it to the power transmission means (3) and which passes right through the hot cylinder head (10) lower via a lower rod orifice (47), and on the other hand, a lower hot cap (19) and an upper hot cap (19) to define with the lower and upper hot yokes (10) a hot chamber of variable volume (11) lower and a hot chamber of variable volume (11) upper. Alternative thermal engine according to claim 17,characterized in that'He understands :

• At least one hollow pillar (101) traversed right through in the direction of its length by a rod tunnel (102), a first pillar end (103) of said pillar (101) resting directly or indirectly on the transmission casing (42) while a second pillar end (104) of said pillar (101) supports the lower hot yoke (10), said first end (101) being able to pivot around a ball joint (105) and/or flex by relative to said casing (42) while said second end (104) can pivot around a ball joint (105) and/or flex relative to said lower hot cylinder head (10);
• At least one traction rod (106) which forms the cylinder head clamping means (24) and which is, at least in part, housed in the rod tunnel (102), a first rod end (107) of said rod traction (106) being directly or indirectly secured to the transmission case (42) while a second rod end (108) of said rod (106) is directly or indirectly secured to the upper hot cylinder head (10), said first end (107) capable of pivoting around a ball joint (105) and/or flexing relative to said casing (42) while said second end (108) can pivot around a ball joint (105) and/or flexing by relative to said cylinder head (10);
• Lower cylinder head centering means (109) integral with the transmission casing (42) and which directly or indirectly bear on the lower hot cylinder head (10), said means (109) leaving said cylinder head (10) free to move on a short distance parallel to the longitudinal axis of the cold cylinder (6) and relative to the transmission casing (42), but preventing said cylinder head (10) from moving in the plane perpendicular to said axis relative to said casing (42) ;
• Upper cylinder head centering means (110) integral with a centering gantry (127) which is rigidly fixed to the transmission casing (42), said means (110) bearing directly or indirectly on the upper hot cylinder head (10) , and said means (109) leaving said cylinder head (10) free to move over a short distance parallel to the longitudinal axis of the cold cylinder (6) and relative to the transmission casing (42), but preventing said cylinder head ( 10) to move in the plane perpendicular to said axis relative to said casing (42).

Reciprocating heat engine according to claim 18, characterized in that a rod cooling tube (111) sealingly envelops the traction rod (106) over all or part of the length of said rod (106), a heat transfer liquid (32) coming from a source of cooling liquid (113) capable of circulating in a space left between the internal wall of said tube (111) and the external surface of said rod (106) while as much of the surface as possible external of said tube (111) does not touch the internal wall of the rod tunnel (102) so as to define with this last wall an empty space. Reciprocating heat engine according to claim 19, characterized in that at least one first tube feed port (114) communicates with the interior of the rod cooling tube (111) in the vicinity of the first rod end (107). ), and at least one second tube feed port (115) communicates with the interior of the rod cooling tube (111) in the vicinity of the second rod end (108), the heat transfer liquid (32) being able to circulate between the two said orifices (114, 115). Reciprocating heat engine according to claim 19, characterized in that the rod cooling tube (111) comprises a tube collar (116) held directly or indirectly clamped by the traction rod (106) either against a fixing ear ( 117) presented by the upper hot cylinder head (10), or against the transmission casing (42). Reciprocating heat engine according to claim 21, characterized in that the tube collar (116) is held tight by the pull rod (106) against the fixing lug (117) via a Banjo connection (118). ) which comprises at least one radial connection conduit (119) which is connected to the source of coolant (113) on the one hand, and which communicates with the interior of the rod cooling tube (111) on the other go. Reciprocating heat engine according to claim 21, characterized in that a thermal insulation extension (120) is inserted between the tube collar (116) and the fixing ear (117), said extension (120) being crossed by part in the direction of its length by an extension tunnel (121) in which is housed the traction rod (106) and the rod cooling tube (111) which envelops it in a sealed manner, while the most large possible part of the external surface of said tube (111) does not touch the internal wall of the extension tunnel (121) so as to define an empty space with this latter wall. Reciprocating heat engine according to claim 19, characterized in that the rod cooling tube (111) comprises at least one tube bulge (122) consisting of an axial portion of said tube (111) whose free diameter is substantially equivalent or even slightly higher than that of the rod tunnel (102) in which it is housed. Reciprocating heat engine according to claim 19, characterized in that the rod cooling tube (111) comprises at least one tube diameter restriction (123) consisting of an axial portion of said tube (111) whose free diameter is substantially equivalent or even slightly lower than that of the body of the traction rod (106). Reciprocating heat engine according to claim 18, characterized in that the traction rod (106) is hollow to form an internal rod cooling channel arranged in the length of said rod (106), said channel opening out axially or radially in the vicinity of each end of said rod (106) while a heat transfer liquid (32) coming from a coolant source (113) can circulate in said channel. Reciprocating heat engine according to claim 18, characterized in that a piston cooling and lubrication chamber (125) connected to a source of lubricating-cooling fluid (126) is fixed on the centering gantry (127) or arranged on or in the latter while an upper piston rod (128) which extends the double-acting piston (2) on the side of the upper hot chamber of variable volume (11) passes through the upper hot cylinder head (10) via a orifice of upper rod (129) arranged in said cylinder head (10) and via an access orifice to the cooling and lubrication chamber (130) passing through the centering gantry (127) to open into the piston cooling and lubrication chamber (125) so that the end of the upper piston rod (128) which is furthest from said piston (2) always remains immersed in said chamber (128) whatever the position of said piston (2). Reciprocating heat engine according to claim 27, characterized in that a lubricating-cooling fluid (139) can circulate from the piston cooling and lubricating chamber (125) to the transmission housing (42) successively via a upper piston rod internal channel (140) provided longitudinally in the upper piston rod (128), via an internal piston cavity (141), and via a lower piston rod internal channel (142) provided longitudinally in the rod lower piston (46). Reciprocating heat engine according to claim 28, characterized in that the periphery of the internal piston cavity (141) communicates with the external peripheral face of the piston sealing ring (37) via at least one peripheral lubrication orifice d ring (143) which opens axially between at least two piston sealing means (30), said orifice (143) constituting the lubrication means (8). Reciprocating heat engine according to claim 18, characterized in that the transmission casing (42) is covered with a centering and sealing plate (131) pierced with an access orifice to the transmission means (132) at the through which the lower piston rod (46) passes to be connected to the power transmission means (3), said plate (131) being rigidly fixed to said casing (42). Reciprocating heat engine according to claim 27, characterized in that the access orifice to the cooling and lubrication chamber (130) comprises rod sealing means (133) providing a seal between said orifice (130) and the upper piston rod (128). Reciprocating heat engine according to claim 30, characterized in that the access orifice to the transmission means (132) comprises rod sealing means (133) providing a seal between said orifice (132) and the lower rod of piston (46). Reciprocating heat engine according to claim 18, characterized in that the lower cylinder head centering means (109) and/or the upper cylinder head centering means (110) consist of an elastic centering disc (134) which can be pierced in its center a disc hole (135) through which respectively passes the lower piston rod (46) or an upper piston rod (128) while its periphery constitutes a disc fixing flange (136) fixed by sealed manner respectively on the transmission casing (42) and/or on the centering gantry (127). Reciprocating heat engine according to claim 30, characterized in that the centering and sealing plate (131) carries the lower cylinder head centering means (109) which consist of an elastic centering disc (134) whose periphery forms a disc fixing collar (136) fixed in a sealed manner on said plate (131), said disc (134) being pierced in its center with a disc hole (135) through which the lower piston rod ( 46) without touching said disc (134), the edge of the disc hole (135) having a circular contact pad (137) which is maintained in sealed contact with a centering and sealing cone (138) which the cylinder head presents hot (10) lower, said cone (138) being able to be male or female, and the contact between said pad (137) and said cone (138) having the effect of deforming axially and from its center the elastic centering disc (134) . Reciprocating heat engine according to claim 18, characterized in that the upper cylinder head centering means (110) consist of an elastic centering disc (134) whose periphery forms a disc fixing collar (136) fixed so sealed on the centering gantry (127), said disc (134) being pierced in its center with a disc hole (135) whose edge has a circular contact pad (137) which is maintained in sealed contact with a cone centering and sealing (138) presented by the upper hot cylinder head (10), said cone (138) being able to be male or female, and the contact between said pad (137) and said cone (138) having the effect of deforming axially and from its center the elastic centering disc (134). Reciprocating thermal engine according to claim 18, characterized in that an anti-rotation connection (149) directly or indirectly connects the lower hot cylinder head (10) and/or the upper hot cylinder head (10) and/or the cooled cylinder block ( 5) to the centering gantry (127).