EP2039813A1 - Thermal engine and procedure for controlling the thermal conductivity of the surface of the combustion chamber - Google Patents

Thermal engine and procedure for controlling the thermal conductivity of the surface of the combustion chamber Download PDF

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Publication number
EP2039813A1
EP2039813A1 EP08163462A EP08163462A EP2039813A1 EP 2039813 A1 EP2039813 A1 EP 2039813A1 EP 08163462 A EP08163462 A EP 08163462A EP 08163462 A EP08163462 A EP 08163462A EP 2039813 A1 EP2039813 A1 EP 2039813A1
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Prior art keywords
thermal conductivity
phase
during
equal
engine
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EP08163462A
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German (de)
French (fr)
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Jean-Bruno Zimmermann
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PSA Automobiles SA
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Peugeot Citroen Automobiles SA
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P9/00—Cooling having pertinent characteristics not provided for in, or of interest apart from, groups F01P1/00 - F01P7/00
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F1/00—Cylinders; Cylinder heads 
    • F02F1/02—Cylinders; Cylinder heads  having cooling means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02F—CYLINDERS, PISTONS OR CASINGS, FOR COMBUSTION ENGINES; ARRANGEMENTS OF SEALINGS IN COMBUSTION ENGINES
    • F02F3/00—Pistons 
    • F02F3/16—Pistons  having cooling means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2251/00—Material properties
    • F05C2251/04—Thermal properties
    • F05C2251/048—Heat transfer

Definitions

  • the field of the invention is that of land, sea or air vehicles comprising a high efficiency heat engine. Optimizing the efficiency of the engine is a significant problem given the rising cost of energy and pollution problems.
  • the consumption of the vehicle becomes today a criterion of purchase of first rank with the consumers and finally a major problem for the car manufacturers.
  • the efficiency of the heat engine is partly related to the heat exchange between the gas mixture in combustion and the walls of the combustion chamber.
  • the gaseous mixture is a fuel mixture and can be of any type of fuel: gasoline, diesel, gas, biofuel for example.
  • the heat exchanges vary throughout this cycle, whether in intensity or in direction, the direction of exchange always remaining consistent with physics, that is to say from hot bodies to cold bodies .
  • the exchange takes place in the direction of the cylinder towards the gases and, during the combustion and exhaust phases, in the direction of the gases towards the walls of the chamber of combustion.
  • Two types of combustion chamber behavior may be desired by the engine manufacturer.
  • the goal may be to obtain the greatest heat exchange possible with the heat transfer liquid, to ensure a minimum rise in the air load and fuel mixture.
  • the goal is to obtain the least heat exchange with the outside of the combustion chamber in order to conserve the maximum energy released during combustion to convert it into work. .
  • the patent whose publication number is JP11236636 describes a material that could be used in an automotive engine and whose thermal conductivity changes in correlation with the change in temperature.
  • the patent proposes a motor concept using a variable conductivity material depending on the temperature that can be used to protect the sensitive parts at a high temperature.
  • the variation of conductivity is not controllable and the device therefore always undergoes heat exchange. In some cases, these variations are detrimental to performance.
  • the subject of the present invention is a heat engine comprising a plurality of combustion chambers, each delimited by the walls of a plurality of elements, characterized in that, at least one of said walls, is constituted by a material , whose thermal conductivity Cp varies, by applying an electric field controlled by a control unit of the motor.
  • the thermal conductivity C p can vary cyclically in phase with the phases of the motor cycles.
  • the principle can be applied locally to only one of these elements or to those of a specific part of the combustion chamber or even to all the elements constituting the combustion chamber.
  • the basic principle is related to the physical fact that thermal conductivity usually goes hand in hand with electrical conductivity. For example, metals that are good conductors of electricity are also good thermal conductors.
  • the type of variable conductivity material used for the present invention is of the type described in the patent applications W02005124790 and W08807224 .
  • the method of the invention can use any type of material whose thermomechanical resistance characteristics are compatible with the constraints specific to the combustion chambers, but whose thermal conductivity is controllable.
  • the first patent describes a material for which the thermal conductivity can vary by the application of an electric field.
  • This external electric field has the effect of orienting the electric dipoles or exciting the mode of vibration of the photons so as to promote the thermal conductivity, or conversely to limit heat exchange.
  • the patent in question refers to a composite material containing a resin of elements reacting to the external fields.
  • the second patent describes a material whose electrical conductivity varies by exposure to light or heat. This action involves a change of structure within the material changing its conductivity properties.
  • the heat engine comprises a plurality of combustion chambers, each delimited by the walls of a plurality of elements, characterized in that, at least one of said walls, is constituted by a material, whose thermal conductivity C p varies, by applying an electric field controlled by a control unit of the motor, this electric field being distinct from one wall to the other.
  • a control unit of the motor for example, it is possible to allow maximum thermal exchange at the walls of the cylinder and both to limit the exchanges at the intake valves to optimize the preparation of the mixture during injection on these hot valves.
  • the present invention also relates to the method for controlling the thermal conductivity of the walls of the combustion chamber of said device.
  • it may be a four-stroke combustion engine whose cycle is divided into four phases: the admission of air by the opening of the intake valve and the descent of the piston, the compression of the air by raising the piston and the closing of the valve, the combustion of the gaseous mixture which pushes the piston and releases a part of the energy, and the exhaust of the gases burned by the opening of the the exhaust valve and the raising of the piston.
  • the control method therefore consists in cyclically varying in phase with these four phases of the engine the thermal conductivity of the walls of the combustion chamber.
  • a first control strategy can be, in the case where one seeks to optimize the yield and limit the transmission of energy to the heat transfer gases, to limit heat exchange during the combustion phase and, in the case where one seeks to keep a maximum of enthalpy to operate the supercharging system, to limit heat exchange during the exhaust phase.
  • the supercharging is to introduce air into the cylinder at a pressure above atmospheric pressure to optimize the efficiency of the engine.
  • we pilot the thermal conductivity of the walls of the chamber. combustion to promote heat exchange during the intake and compression phases.
  • rattling is a phenomenon of unwanted micro-explosions that can appear and damage the engine during combustion.
  • the reasons for their appearance may be too high a temperature of the gas mixture during the admission or the presence of hot spots inside the combustion chamber.
  • This strategy is not limited to a particular type of engine and is applicable to spark ignition engines as well as for diesel engines, the gas mixture of which ignites spontaneously.
  • a second control strategy is this time to limit exchanges during compression and combustion phases and instead to promote them during the intake and exhaust phases. Limiting the exchanges, during the compression phase by reducing the thermodynamic losses associated with the decrease in gas temperature, makes it possible to obtain the highest temperature at the end of compression, which is advantageous for combustion of the self-ignition type. Gasoline or diesel fuel mixtures and, during the combustion phase can increase the yield. On the contrary, favoring exchanges during the intake phase makes it possible to optimize the freshest possible air filling and to avoid any enthalpy during the exhaust.
  • a third strategy for controlling the thermal conductivity similar to the previous one consists in the combustion phase while the thermal conductivity is minimal to allow maximum heat exchange at a specific time, which depends on the engine and the course of combustion.
  • the purpose of the maneuver is to limit the risk of occurrence of knocking phenomenon due to a combustion chamber temperature too high.
  • This invention makes it possible to no longer fully undergo thermal transfers taking place in a motor cycle.
  • the control of the thermal conductivity of the walls of the combustion chamber optimizes the efficiency of the engine by avoiding heat transfer during the phases where the combustion energy must be transformed into work. For the user this results in a gain in vehicle consumption.
  • Another important asset for the engine manufacturer is the possibility of winning on the rattling limit by controlling temperature rises.
  • the rattling limit is usually a limiting factor for motor designers. Indeed, for a given engine, the compression ratio can not be increased indefinitely.
  • the invention also makes it possible to improve the control of the combustion and thus to extend the life of the engine while avoiding the appearance of this phenomenon.
  • By controlling the thermal conductivity to the maximum for the sensitive components they are protected from too high temperatures when the engine is hot and conversely, by limiting the thermal conductivity optimizes the rise in temperature of the engine and the catalyst when the engine is still cold.
  • the Figures 1, 2 , 3 and 4 represent the evolution of the position of the piston P p and that of the thermal conductivity of the walls of the combustion chamber C p of a four-stroke heat engine.
  • all the walls of the elements forming the combustion chamber consists of a material whose thermal conductivity is controlled by the control unit by applying an electric field. This material is of the type described in the patents of the description of the invention.
  • the graphic windows of the Figures 1, 2 , 3 and 4 describe on a motor cycle the displacement of the piston P p and the control of the thermal conductivity of the walls during the four phases of the engine cycle.
  • the four phases of the engine, intake, compression, combustion and exhaust, are delineated on the graphs by the dashed vertical lines.
  • Phase t0 to t1 represents the admission phase.
  • the piston At t0 the piston is in the up position and evolves by a downward movement up to t1 where it reaches its low position.
  • the intake valves are in the open position allowing air to enter.
  • Phase t1 to t2 represents the compression phase.
  • the piston At t1, the piston is in the low position and evolves by an upward movement until t2 where it reaches its high position.
  • the gas mixture is compressed.
  • Phase t2 to t3 represents the combustion phase.
  • the piston At t2 the piston is in the up position and evolves by a downward movement until t3 where it reaches its low position.
  • the gaseous mixture is ignited, either controlled type or auto-ignited type according to the engine.
  • phase t3 to t4 is the exhaust phase.
  • the piston is in the low position and evolves by an upward movement towards its high position.
  • the burned gas mixture is discharged through the opening of the valves to the exhaust duct.
  • the time evolution of the position of the piston Pp is a sinusoidal curve.
  • the control of the thermal conductivity of the walls of the elements constituting the combustion chamber of the engine Cp is such that the thermal conductivity of the walls of the elements constituting the combustion chamber of the engine comprises high constant values and low constant values, so that the temporal variation of the thermal conductivity is a succession of crenellations.
  • This control method makes it possible to limit the rise in temperature of the incoming charge in the engine during admission and compression, which reduces the risk of knocking.
  • the thermal conductivity is minimal in order to increase the efficiency of the transformation of thermal energy into working energy.
  • the driving process of the figure 2 is advantageous for combustion engines of auto-ignited type.
  • the thermal conductivity is minimal to obtain the most isentropic compression possible.
  • controlling the thermal conductivity makes it possible to optimize the filling of fresh air and to release gases at a less harmful temperature, for example for the collector or the catalyst.
  • the process of figure 3 for controlling the thermal conductivity of the walls of the combustion chamber is managed so that at a given moment of the combustion phase, the thermal conductivity, equal to the low value before this moment, becomes high in order to limit the appearance of rattling phenomena.
  • the invention offers the possibility of adjusting the rise in temperature of the combustion chamber according to the characteristics of the engine. It is then possible to approach the rattling limits by acting on the engine's capabilities to limit or promote heat exchange with the outside.
  • variable thermal conductivity material it is possible to apply the variable thermal conductivity material to a part of the elements of the combustion chamber or to the whole of the combustion chamber. Thus, it is conceivable to act on the thermal conductivity specifically at specific locations in the combustion chamber. More generally, the invention can be applied to any type of heat engine, gasoline engine, diesel or biofuel for example. The control of the conductivity is then configurable according to the desired effect.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

The heat engine has a set of combustion chambers defined by walls of a set of mechanical elements. The walls are made of a material whose thermal conductivity (Cp) is varied between high constant value and low constant value and controlled in phase with cyclic phases of engine cycles by applying an electric field controlled by an engine control unit, where the electrical conductivity of the each walls is different from each other. An independent claim is also included for a method for controlling a thermal conductivity of a heat engine.

Description

Le domaine de l'invention est celui des véhicules terrestres, marins ou aériens comprenant un moteur thermique à haut rendement. L'optimisation du rendement du moteur thermique est un problème important compte tenu du coût montant de l'énergie et des problèmes de pollution. La consommation du véhicule devient alors aujourd'hui un critère d'achat de premier rang auprès des consommateurs et finalement une problématique majeure pour les constructeurs automobiles.The field of the invention is that of land, sea or air vehicles comprising a high efficiency heat engine. Optimizing the efficiency of the engine is a significant problem given the rising cost of energy and pollution problems. The consumption of the vehicle becomes today a criterion of purchase of first rank with the consumers and finally a major problem for the car manufacturers.

Le rendement du moteur thermique est en partie lié aux échanges thermiques entre le mélange gazeux en combustion et les parois de la chambre de combustion. Le mélange gazeux est un mélange carburé et peut être de tout type de carburant : essence, diesel, gaz, biocarburant par exemple. Dans un cycle moteur les échanges thermiques varient tout au long de ce cycle, que ce soit en intensité ou en direction, le sens d'échange restant toujours conforme à la physique, c'est-à-dire des corps chauds vers les corps froids. Par exemple, lors des phases d'admission et de compression, l'échange s'effectue dans le sens du cylindre vers les gaz et, lors des phases de combustion et d'échappement, dans le sens des gaz vers les parois de la chambre de combustion. Deux types de comportement de la chambre de combustion peuvent être désirés par le motoriste. Lors de la phase d'admission et de compression, le but peut être d'obtenir des échanges thermiques les plus forts possibles avec le liquide caloporteur, pour assurer une élévation minimale de la charge en air et en mélange carburé. Lors de la phase de combustion et d'échappement, le but est d'obtenir le moins d'échanges thermiques avec l'extérieur de la chambre de combustion afin de conserver le maximum d'énergie dégagée lors de la combustion pour la convertir en travail. Ces échanges thermiques avec les parois constituent une perte d'énergie qui pourrait être utilisée pour générer du travail moteur.The efficiency of the heat engine is partly related to the heat exchange between the gas mixture in combustion and the walls of the combustion chamber. The gaseous mixture is a fuel mixture and can be of any type of fuel: gasoline, diesel, gas, biofuel for example. In a motor cycle the heat exchanges vary throughout this cycle, whether in intensity or in direction, the direction of exchange always remaining consistent with physics, that is to say from hot bodies to cold bodies . For example, during the intake and compression phases, the exchange takes place in the direction of the cylinder towards the gases and, during the combustion and exhaust phases, in the direction of the gases towards the walls of the chamber of combustion. Two types of combustion chamber behavior may be desired by the engine manufacturer. During the intake and compression phase, the goal may be to obtain the greatest heat exchange possible with the heat transfer liquid, to ensure a minimum rise in the air load and fuel mixture. During the combustion and exhaust phase, the goal is to obtain the least heat exchange with the outside of the combustion chamber in order to conserve the maximum energy released during combustion to convert it into work. . These heat exchanges with the walls constitute a loss of energy that could be used to generate motor work.

Le brevet dont le numéro de publication est JP11236636 décrit un matériau qui pourrait être utilisé dans un moteur automobile et dont la conductivité thermique change en corrélation avec le changement de température. Le brevet propose un concept de moteur utilisant un matériau à conductivité variable en fonction de la température pouvant servir à protéger les pièces sensibles à une température élevée. Dans ce dernier concept d'invention, la variation de conductivité n'est pas pilotable et le dispositif subit donc toujours les échanges thermiques. Dans certains cas, ces variations sont préjudiciables au rendement.The patent whose publication number is JP11236636 describes a material that could be used in an automotive engine and whose thermal conductivity changes in correlation with the change in temperature. The patent proposes a motor concept using a variable conductivity material depending on the temperature that can be used to protect the sensitive parts at a high temperature. In this latter concept of invention, the variation of conductivity is not controllable and the device therefore always undergoes heat exchange. In some cases, these variations are detrimental to performance.

Plus précisément, la présente invention a pour objet un moteur thermique comprenant plusieurs chambres de combustion, délimitées chacune par les parois d'une pluralité d'éléments, caractérisé en ce que, au moins l'une des dites parois, est constituée par un matériau, dont la conductivité thermique Cp varie, par application d'un champ électrique piloté par une unité de commande du moteur.More specifically, the subject of the present invention is a heat engine comprising a plurality of combustion chambers, each delimited by the walls of a plurality of elements, characterized in that, at least one of said walls, is constituted by a material , whose thermal conductivity Cp varies, by applying an electric field controlled by a control unit of the motor.

La conductivité thermique Cp peut varier de manière cyclique en phase avec les phases des cycles du moteur. Le principe peut s'appliquer localement à un seul de ces éléments ou à ceux d'une partie spécifique de la chambre de combustion ou même à l'ensemble des éléments constituant la chambre de combustion. Le principe de base est lié au fait physique que, généralement la conductivité thermique va de pair avec la conductivité électrique. Par exemple, les métaux bons conducteurs d'électricité sont aussi de bons conducteurs thermiques. Le type de matériau à conductivité variable utilisé pour la présente invention est de type de ceux décrits dans les demandes de brevet W02005124790 et W08807224 . Le procédé de l'invention peut utiliser tout type de matériau dont les caractéristiques de tenue thermomécaniques sont compatibles avec les contraintes propres aux chambres de combustion, mais dont la conductivité thermique est pilotable.The thermal conductivity C p can vary cyclically in phase with the phases of the motor cycles. The principle can be applied locally to only one of these elements or to those of a specific part of the combustion chamber or even to all the elements constituting the combustion chamber. The basic principle is related to the physical fact that thermal conductivity usually goes hand in hand with electrical conductivity. For example, metals that are good conductors of electricity are also good thermal conductors. The type of variable conductivity material used for the present invention is of the type described in the patent applications W02005124790 and W08807224 . The method of the invention can use any type of material whose thermomechanical resistance characteristics are compatible with the constraints specific to the combustion chambers, but whose thermal conductivity is controllable.

Le premier brevet décrit un matériau pour lequel la conductivité thermique peut varier par l'application d'un champ électrique. Ce champ électrique extérieur a pour effet d'orienter les dipolaires électriques ou d'exciter le mode de vibration des photons de façon à favoriser la conductivité thermique, ou à l'inverse de limiter les échanges thermiques. II s'agit dans le brevet en question d'un matériau composite contenant une résine d'éléments réagissant aux champs extérieur.The first patent describes a material for which the thermal conductivity can vary by the application of an electric field. This external electric field has the effect of orienting the electric dipoles or exciting the mode of vibration of the photons so as to promote the thermal conductivity, or conversely to limit heat exchange. The patent in question refers to a composite material containing a resin of elements reacting to the external fields.

Le deuxième brevet décrit un matériau dont la conductivité électrique varie par exposition à la lumière ou à la chaleur. Cette action implique un changement de structure au sein du matériau modifiant ses propriétés de conductivité.The second patent describes a material whose electrical conductivity varies by exposure to light or heat. This action involves a change of structure within the material changing its conductivity properties.

Dans un mode de mise en oeuvre, le moteur thermique comprend plusieurs chambres de combustion, délimitées chacune par les parois d'une pluralité d'éléments, caractérisé en ce que, au moins l'une des dites parois, est constituée par un matériau, dont la conductivité thermique Cp varie, par application d'un champ électrique piloté par une unité de commande du moteur, ce champ électrique étant distinct d'une paroi à l'autre. Par exemple, il est possible d'autoriser un échange thermique maximal au niveau des parois du cylindre et à la fois de limiter les échanges au niveau des soupapes d'admission pour optimiser la préparation du mélange lors de l'injection sur ces soupapes chaudes.In one embodiment, the heat engine comprises a plurality of combustion chambers, each delimited by the walls of a plurality of elements, characterized in that, at least one of said walls, is constituted by a material, whose thermal conductivity C p varies, by applying an electric field controlled by a control unit of the motor, this electric field being distinct from one wall to the other. For example, it is possible to allow maximum thermal exchange at the walls of the cylinder and both to limit the exchanges at the intake valves to optimize the preparation of the mixture during injection on these hot valves.

La présente invention concerne également le procédé de pilotage de la conductivité thermique des parois de la chambre de combustion dudit dispositif. A titre d'exemple non limitatif, il peut s'agir d'un moteur à explosion à quatre temps dont le cycle est divisé en quatre phases : l'admission d'air par l'ouverture de la soupape d'admission et la descente du piston, la compression de l'air par remontée du piston et la fermeture de la soupape, la combustion du mélange gazeux qui repousse le piston et libère une partie de l'énergie, et l'échappement des gaz brulés par l'ouverture de la soupape d'échappement et la remontée du piston. Le procédé de pilotage consiste donc à faire varier de manière cyclique en phase avec ces quatre phases du moteur la conductivité thermique des parois de la chambre de combustion. Plusieurs types de stratégie peuvent être ainsi appliqués en fonction des effets recherchés.The present invention also relates to the method for controlling the thermal conductivity of the walls of the combustion chamber of said device. By way of non-limiting example, it may be a four-stroke combustion engine whose cycle is divided into four phases: the admission of air by the opening of the intake valve and the descent of the piston, the compression of the air by raising the piston and the closing of the valve, the combustion of the gaseous mixture which pushes the piston and releases a part of the energy, and the exhaust of the gases burned by the opening of the the exhaust valve and the raising of the piston. The control method therefore consists in cyclically varying in phase with these four phases of the engine the thermal conductivity of the walls of the combustion chamber. Several types of strategy can thus be applied depending on the desired effects.

Une première stratégie de pilotage peut être, dans le cas où on cherche à optimiser le rendement et limiter la transmission d'énergie aux gaz caloporteurs, de limiter les échanges thermiques lors de la phase de combustion et, dans le cas où on cherche à garder un maximum d'enthalpie pour faire fonctionner le système de suralimentation, de limiter les échanges thermiques lors de la phase d'échappement. Pour rappel, la suralimentation consiste à introduire de l'air dans le cylindre à une pression supérieure à la pression atmosphérique afin d'optimiser le rendement du moteur. Dans le cas où on cherche à diminuer le réchauffage des gaz frais et limiter le risque de cliquetis, on pilote la conductivité thermique des parois de la chambre de combustion de manière à favoriser les échanges thermiques lors des phases d'admission et de compression. Pour rappel, le cliquetis est un phénomène de micro-explosions indésirables pouvant apparaître et endommager le moteur lors de la combustion. II s'agit d'un comportement que les motoristes cherchent à éviter. Les raisons de leur apparition peuvent être une température trop élevée du mélange gazeux lors de l'admission ou bien la présence de points chauds à l'intérieur de la chambre de combustion Cette stratégie n'est pas limitative à un type de moteur particulier et est applicable aux moteurs à allumage commandé ainsi que pour les moteurs diesels, dont le mélange gazeux s'enflamme spontanément.A first control strategy can be, in the case where one seeks to optimize the yield and limit the transmission of energy to the heat transfer gases, to limit heat exchange during the combustion phase and, in the case where one seeks to keep a maximum of enthalpy to operate the supercharging system, to limit heat exchange during the exhaust phase. As a reminder, the supercharging is to introduce air into the cylinder at a pressure above atmospheric pressure to optimize the efficiency of the engine. In the case where we try to reduce the reheating of fresh gases and limit the risk of knocking, we pilot the thermal conductivity of the walls of the chamber. combustion to promote heat exchange during the intake and compression phases. As a reminder, rattling is a phenomenon of unwanted micro-explosions that can appear and damage the engine during combustion. This is a behavior that engine manufacturers seek to avoid. The reasons for their appearance may be too high a temperature of the gas mixture during the admission or the presence of hot spots inside the combustion chamber. This strategy is not limited to a particular type of engine and is applicable to spark ignition engines as well as for diesel engines, the gas mixture of which ignites spontaneously.

Une deuxième stratégie de pilotage est cette fois de limiter les échanges lors des phases de compression et de combustion et au contraire de les favoriser lors des phases d'admission et d'échappement. Limiter les échanges, lors de la phase de compression en réduisant les pertes thermodynamiques liées à la diminution de température des gaz, permet d'obtenir la température la plus élevée en fin de compression ce qui est avantageux pour les combustions de type auto-inflammation des mélanges carburés essence ou diesel et, lors de la phase de combustion permet d'augmenter le rendement. A l'opposé favoriser les échanges lors de la phase d'admission permet d'optimiser le remplissage en air le plus frais possible et, de ne pas conserver de l'enthalpie lors de l'échappement.A second control strategy is this time to limit exchanges during compression and combustion phases and instead to promote them during the intake and exhaust phases. Limiting the exchanges, during the compression phase by reducing the thermodynamic losses associated with the decrease in gas temperature, makes it possible to obtain the highest temperature at the end of compression, which is advantageous for combustion of the self-ignition type. Gasoline or diesel fuel mixtures and, during the combustion phase can increase the yield. On the contrary, favoring exchanges during the intake phase makes it possible to optimize the freshest possible air filling and to avoid any enthalpy during the exhaust.

Une troisième stratégie de pilotage de la conductivité thermique similaire à la précédente consiste dans la phase de combustion alors que la conductivité thermique est minimale à autoriser des échanges thermiques maximum à un moment spécifique, moment qui dépend du moteur et du déroulement de la combustion. Le but de la manoeuvre étant de limiter les risques d'apparition de phénomène de cliquetis dû à une température de chambre de combustion trop élevée.A third strategy for controlling the thermal conductivity similar to the previous one consists in the combustion phase while the thermal conductivity is minimal to allow maximum heat exchange at a specific time, which depends on the engine and the course of combustion. The purpose of the maneuver is to limit the risk of occurrence of knocking phenomenon due to a combustion chamber temperature too high.

Cette invention permet de ne plus subir totalement les transferts thermiques se déroulant dans un cycle moteur. Avantageusement, le pilotage de la conductivité thermique des parois de la chambre de combustion optimise le rendement du moteur en évitant les transferts thermiques lors des phases où l'énergie de combustion doit être transformée en travail. Pour l'utilisateur cela se traduit par un gain en consommation du véhicule. Un autre atout important pour le motoriste est la possibilité de gagner sur la limite cliquetis en pilotant les montées de température. La limite cliquetis est généralement un facteur limitant pour les concepteurs de moteur. En effet, pour un moteur donné, le taux de compression ne peut être augmenté indéfiniment. L'invention permet aussi d'améliorer le contrôle de la combustion et ainsi d'allonger la durée de vie du moteur en évitant l'apparition de ce phénomène. En pilotant la conductivité thermique au maximum pour les composants sensibles, on les protège des trop fortes températures lorsque le moteur est chaud et à l'inverse, en limitant la conductivité thermique on optimise la montée en température du moteur et du catalyseur lorsque le moteur est encore froid.This invention makes it possible to no longer fully undergo thermal transfers taking place in a motor cycle. Advantageously, the control of the thermal conductivity of the walls of the combustion chamber optimizes the efficiency of the engine by avoiding heat transfer during the phases where the combustion energy must be transformed into work. For the user this results in a gain in vehicle consumption. Another important asset for the engine manufacturer is the possibility of winning on the rattling limit by controlling temperature rises. The rattling limit is usually a limiting factor for motor designers. Indeed, for a given engine, the compression ratio can not be increased indefinitely. The invention also makes it possible to improve the control of the combustion and thus to extend the life of the engine while avoiding the appearance of this phenomenon. By controlling the thermal conductivity to the maximum for the sensitive components, they are protected from too high temperatures when the engine is hot and conversely, by limiting the thermal conductivity optimizes the rise in temperature of the engine and the catalyst when the engine is still cold.

L'invention sera mieux comprise et d'autres avantages apparaîtront à la lecture de la description qui va suivre donnée à titre non limitatif et grâce aux figures annexées parmi lesquelles :

  • La figure 1 représente un premier procédé de pilotage de la conductivité thermique des parois de la chambre de combustion du moteur.
  • La figure 2 représente un second procédé de pilotage de la conductivité thermique des parois de la chambre de combustion du moteur.
  • La figure 3 représente un troisième procédé de pilotage de la conductivité thermique des parois de la chambre de combustion du moteur.
The invention will be better understood and other advantages will become apparent on reading the description which follows given by way of non-limiting example and by virtue of the appended figures among which:
  • The figure 1 represents a first method for controlling the thermal conductivity of the walls of the combustion chamber of the engine.
  • The figure 2 represents a second method for controlling the thermal conductivity of the walls of the combustion chamber of the engine.
  • The figure 3 represents a third method for controlling the thermal conductivity of the walls of the combustion chamber of the engine.

Les figures 1, 2, 3 et 4 représentent l'évolution de la position du piston Pp et celle de la conductivité thermique des parois de la chambre de combustion Cp d'un moteur thermique à quatre temps. A titre d'exemple non limitatif, l'ensemble des parois des éléments formant la chambre de combustion est constitué d'un matériau dont la conductivité thermique est pilotée par l'unité de commande par application d'un champ électrique. Ce matériau est du type de ceux décrits dans les brevets de la description de l'invention. Les fenêtres graphiques des figures 1, 2, 3 et 4 décrivent sur un cycle du moteur le déplacement du piston Pp et le pilotage de la conductivité thermique des parois au cours des quatre phases du cycle moteur. Les quatre phases du moteur, l'admission, la compression, la combustion et l'échappement, sont délimitées sur les graphiques par les droites verticales en pointillées. La phase t0 à t1 représente la phase d'admission. A t0 le piston est en position haute et évolue par un mouvement descendant jusqu'à t1 où il atteint sa position basse. Durant cette phase les soupapes d'admission sont en position ouverte permettant à l'air de rentrer. La phase t1 à t2 représente la phase de compression. A t1, le piston est en position basse et évolue par un mouvement ascendant jusqu'à t2 où il atteint sa position haute. Durant cette phase le mélange gazeux est comprimé. La phase t2 à t3 représente la phase de combustion. A t2 le piston est en position haute et évolue par un mouvement descendant jusqu'à t3 où il atteint sa position basse. Le mélange gazeux est enflammé, soit de type commandé, soit de type auto-enflammé selon le moteur. Le piston est alors repoussé vers le bas. II s'agit de la phase où l'énergie thermique est transformée en énergie de travail. La phase t3 à t4 est la phase d'échappement. A t3 le piston est en position basse et évolue par un mouvement ascendant vers sa position haute. Le mélange gazeux brulé est évacué par l'ouverture des soupapes vers le conduit d'échappement. L'évolution temporelle de la position du piston Pp est une courbe sinusoïdale. Le pilotage de la conductivité thermique des parois des éléments constituant la chambre de combustion du moteur Cp est tel que la conductivité thermique des parois des éléments constituant la chambre de combustion du moteur comporte des valeurs constantes hautes et des valeurs constantes basses, de façon que la variation temporelle de la conductivité thermique soit une succession de créneaux.The Figures 1, 2 , 3 and 4 represent the evolution of the position of the piston P p and that of the thermal conductivity of the walls of the combustion chamber C p of a four-stroke heat engine. By way of nonlimiting example, all the walls of the elements forming the combustion chamber consists of a material whose thermal conductivity is controlled by the control unit by applying an electric field. This material is of the type described in the patents of the description of the invention. The graphic windows of the Figures 1, 2 , 3 and 4 describe on a motor cycle the displacement of the piston P p and the control of the thermal conductivity of the walls during the four phases of the engine cycle. The four phases of the engine, intake, compression, combustion and exhaust, are delineated on the graphs by the dashed vertical lines. Phase t0 to t1 represents the admission phase. At t0 the piston is in the up position and evolves by a downward movement up to t1 where it reaches its low position. During this phase the intake valves are in the open position allowing air to enter. Phase t1 to t2 represents the compression phase. At t1, the piston is in the low position and evolves by an upward movement until t2 where it reaches its high position. During this phase the gas mixture is compressed. Phase t2 to t3 represents the combustion phase. At t2 the piston is in the up position and evolves by a downward movement until t3 where it reaches its low position. The gaseous mixture is ignited, either controlled type or auto-ignited type according to the engine. The piston is then pushed down. This is the phase where the thermal energy is transformed into working energy. Phase t3 to t4 is the exhaust phase. At t3 the piston is in the low position and evolves by an upward movement towards its high position. The burned gas mixture is discharged through the opening of the valves to the exhaust duct. The time evolution of the position of the piston Pp is a sinusoidal curve. The control of the thermal conductivity of the walls of the elements constituting the combustion chamber of the engine Cp is such that the thermal conductivity of the walls of the elements constituting the combustion chamber of the engine comprises high constant values and low constant values, so that the temporal variation of the thermal conductivity is a succession of crenellations.

La figure 1 décrit un premier procédé de pilotage de la conductivité thermique des parois de la chambre de combustion du moteur. La conductivité thermique des parois des éléments constituant la chambre de combustion Cp est pilotée sur une période de cycle du moteur de façon à ce que :

  • • Durant la phase d'admission, la conductivité thermique est égale à la valeur haute.
  • • Durant la phase de compression, la conductivité thermique est égale à la valeur haute.
  • • Durant la phase de combustion, la conductivité thermique est égale à la valeur basse.
  • • Durant la phase d'échappement, la conductivité thermique est égale à la valeur basse.
The figure 1 describes a first method for controlling the thermal conductivity of the walls of the combustion chamber of the engine. The thermal conductivity of the walls of the elements constituting the combustion chamber C p is controlled over a cycle period of the engine so that:
  • • During the intake phase, the thermal conductivity is equal to the high value.
  • • During the compression phase, the thermal conductivity is equal to the high value.
  • • During the combustion phase, the thermal conductivity is equal to the low value.
  • • During the exhaust phase, the thermal conductivity is equal to the low value.

Ce procédé de pilotage permet de limiter l'élévation en température de la charge entrante dans le moteur lors de l'admission et de la compression, ce qui diminue le risque de cliquetis. Lors de la détente et l'échappement la conductivité thermique est minimale afin d'augmenter le rendement de la transformation d'énergie thermique en énergie de travail.This control method makes it possible to limit the rise in temperature of the incoming charge in the engine during admission and compression, which reduces the risk of knocking. During expansion and exhaust, the thermal conductivity is minimal in order to increase the efficiency of the transformation of thermal energy into working energy.

La figure 2 décrit un deuxième procédé de pilotage de la conductivité thermique des parois de la chambre de combustion du moteur. La conductivité thermique des parois des éléments constituant la chambre de combustion est pilotée sur une période de cycle du moteur de la manière suivante :

  • • Durant la phase d'admission, la conductivité thermique est égale à la valeur haute.
  • • Durant la phase de compression, la conductivité thermique est égale à la valeur basse.
  • • Durant la phase de combustion, la conductivité thermique est égale à la valeur basse.
  • • Durant la phase d'échappement, la conductivité thermique est égale à la valeur haute.
The figure 2 discloses a second method of controlling the thermal conductivity of the walls of the combustion chamber of the engine. The thermal conductivity of the walls of the elements constituting the combustion chamber is controlled over a cycle period of the engine as follows:
  • • During the intake phase, the thermal conductivity is equal to the high value.
  • • During the compression phase, the thermal conductivity is equal to the low value.
  • • During the combustion phase, the thermal conductivity is equal to the low value.
  • • During the exhaust phase, the thermal conductivity is equal to the high value.

Le procédé de pilotage de la figure 2 est avantageux pour les moteurs à combustion de type auto-enflammé. Lors de la phase de compression, la conductivité thermique est minimale pour obtenir la compression la plus isentropique possible. Lors des phases d'admission et d'échappement, le pilotage de la conductivité thermique permet d'optimiser le remplissage en air frais et de dégager des gaz à une température moins nocive par exemple pour le collecteur ou le catalyseur.The driving process of the figure 2 is advantageous for combustion engines of auto-ignited type. During the compression phase, the thermal conductivity is minimal to obtain the most isentropic compression possible. During the intake and exhaust phases, controlling the thermal conductivity makes it possible to optimize the filling of fresh air and to release gases at a less harmful temperature, for example for the collector or the catalyst.

La figure 3 décrit un troisième procédé de pilotage de la conductivité thermique des parois de la chambre de combustion du moteur. La conductivité thermique des parois des éléments constituant la chambre de combustion est pilotée sur une période de cycle du moteur de la manière suivante :

  • • Durant la phase d'admission, la conductivité thermique est égale à la valeur haute.
  • • Durant la phase de compression, la conductivité thermique est égale à la valeur basse.
  • • Durant la première moitié de temps de la phase de combustion, la conductivité thermique est égale à la valeur basse.
  • • Durant la deuxième moitié de temps de la phase de combustion, la conductivité thermique est égale à la valeur haute.
  • • Durant la phase d'échappement, la conductivité thermique est égale à la valeur haute.
The figure 3 discloses a third method of controlling the thermal conductivity of the walls of the combustion chamber of the engine. The thermal conductivity of the walls of the elements constituting the combustion chamber is controlled over a cycle period of the engine as follows:
  • • During the intake phase, the thermal conductivity is equal to the high value.
  • • During the compression phase, the thermal conductivity is equal to the low value.
  • • During the first half of the combustion phase, the thermal conductivity is equal to the low value.
  • • During the second half of the combustion phase, the thermal conductivity is equal to the high value.
  • • During the exhaust phase, the thermal conductivity is equal to the high value.

Le procédé de la figure 3 de pilotage de la conductivité thermique des parois de la chambre de combustion est géré de manière à ce qu'à un moment donné de la phase de combustion, la conductivité thermique, égale à la valeur basse avant ce moment, devient haute afin de limiter l'apparition de phénomènes de cliquetis. L'invention offre la possibilité d'ajuster la montée en température de la chambre de combustion en fonction des caractéristiques du moteur. II est alors possible de se rapprocher des limites cliquetis en agissant sur les capacités du moteur à limiter ou favoriser les échanges thermiques avec l'extérieur.The process of figure 3 for controlling the thermal conductivity of the walls of the combustion chamber is managed so that at a given moment of the combustion phase, the thermal conductivity, equal to the low value before this moment, becomes high in order to limit the appearance of rattling phenomena. The invention offers the possibility of adjusting the rise in temperature of the combustion chamber according to the characteristics of the engine. It is then possible to approach the rattling limits by acting on the engine's capabilities to limit or promote heat exchange with the outside.

La figure 4 décrit un quatrième procédé de pilotage de la conductivité thermique des parois de la chambre de combustion du moteur. La conductivité thermique des parois des éléments constituant la chambre de combustion est pilotée sur une période de cycle du moteur de la manière suivante :

  • • Durant la phase d'admission, la conductivité thermique est égale à la valeur haute.
  • • Durant la phase de compression, la conductivité thermique est égale à la valeur basse.
  • • Durant environ la première moitié de temps de la phase de combustion, la conductivité thermique est égale à la valeur basse.
  • • Durant environ la deuxième moitié de temps de la phase de combustion, la conductivité thermique est égale à la valeur haute.
  • • Durant environ les deux tiers de la phase d'échappement, la conductivité thermique est égale à la valeur haute.
  • • Durant environ le dernier tiers de la phase d'échappement, la conductivité thermique est égale à la valeur basse.
The figure 4 discloses a fourth method of controlling the thermal conductivity of the walls of the combustion chamber of the engine. The thermal conductivity of the walls of the elements constituting the combustion chamber is controlled over a cycle period of the engine as follows:
  • • During the intake phase, the thermal conductivity is equal to the high value.
  • • During the compression phase, the thermal conductivity is equal to the low value.
  • • During approximately the first half of the combustion phase, the thermal conductivity is equal to the low value.
  • • During about the second half of the combustion phase, the thermal conductivity is equal to the high value.
  • • During about two-thirds of the exhaust phase, the thermal conductivity is equal to the high value.
  • • During about the last third of the exhaust phase, the thermal conductivity is equal to the low value.

II est possible d'appliquer le matériau à conductivité thermique variable sur une partie des éléments de la chambre de combustion ou à l'ensemble de la chambre de combustion. Ainsi il est envisageable d'agir sur la conductivité thermique spécifiquement à des endroits précis de la chambre de combustion. Plus généralement, l'invention peut s'appliquer à tout type de moteur thermique, moteur essence, diesel ou biocarburant par exemple. Le pilotage de la conductivité est alors configurable en fonction de l'effet recherché.It is possible to apply the variable thermal conductivity material to a part of the elements of the combustion chamber or to the whole of the combustion chamber. Thus, it is conceivable to act on the thermal conductivity specifically at specific locations in the combustion chamber. More generally, the invention can be applied to any type of heat engine, gasoline engine, diesel or biofuel for example. The control of the conductivity is then configurable according to the desired effect.

Claims (8)

Moteur thermique comprenant plusieurs chambres de combustion, délimitées chacune par les parois d'une pluralité d'éléments, caractérisé en ce que, au moins l'une des dites parois, est constituée par un matériau, dont la conductivité thermique Cp varie, par application d'un champ électrique piloté par une unité de commande du moteur.Thermal engine comprising a plurality of combustion chambers, each delimited by the walls of a plurality of elements, characterized in that , at least one of said walls, is constituted by a material whose thermal conductivity Cp varies, by application an electric field driven by a motor control unit. Moteur thermique selon la revendication 1, caractérisé en ce que les parois de plusieurs éléments, sont constituées par un matériau, dont la conductivité thermique Cp varie, par application d'un champ électrique piloté par une unité de commande du moteur, ce champ électrique étant distinct d'une paroi à l'autre.Thermal engine according to Claim 1, characterized in that the walls of several elements consist of a material, whose thermal conductivity Cp varies, by applying an electric field controlled by a control unit of the motor, this electric field being distinct from one wall to another. Moteur thermique selon l'une des revendications 1 ou 2, caractérisé en ce que la conductivité thermique Cp d'une paroi varie entre une valeur constante haute et une valeur constante basse, de façon que la variation temporelle de la conductivité thermique de la paroi soit une succession de créneaux.Thermal engine according to one of claims 1 or 2, characterized in that the thermal conductivity C p of a wall varies between a high constant value and a low constant value, so that the temporal variation of the thermal conductivity of the wall a succession of slots. Moteur thermique selon la revendication 3, caractérisé en ce que le moteur est un moteur à explosion à quatre temps comprenant une phase d'admission, une phase de compression, une phase de combustion et une phase d'échappement.Thermal engine according to claim 3, characterized in that the engine is a four-stroke combustion engine comprising an intake phase, a compression phase, a combustion phase and an exhaust phase. Procédé de pilotage de la conductivité thermique du moteur selon la revendication 4, caractérisé en ce que la conductivité thermique Cp d'au moins une paroi est pilotée sur une période de cycle du moteur de façon que : - Durant la phase d'admission, la conductivité thermique est égale à la valeur haute. - Durant la phase de compression, la conductivité thermique est égale à la valeur haute. - Durant la phase de combustion, la conductivité thermique est égale à la valeur basse. - Durant la phase d'échappement, la conductivité thermique est égale à la valeur basse. A method for controlling the thermal conductivity of the engine according to claim 4, characterized in that the thermal conductivity C p of at least one wall is controlled over a cycle period of the engine so that: - During the intake phase, the thermal conductivity is equal to the high value. - During the compression phase, the thermal conductivity is equal to the high value. - During the combustion phase, the thermal conductivity is equal to the low value. - During the exhaust phase, the thermal conductivity is equal to the low value. Procédé de pilotage de la conductivité thermique du dispositif selon la revendication 4, caractérisé en ce que la conductivité thermique Cp d'au moins une paroi est pilotée sur une période de cycle du moteur de façon que : - Durant la phase d'admission, la conductivité thermique est égale à la valeur haute. - Durant la phase de compression, la conductivité thermique est égale à la valeur basse. - Durant la phase de combustion, la conductivité thermique est égale à la valeur basse. - Durant la phase d'échappement, la conductivité thermique est égale à la valeur haute. A method for controlling the thermal conductivity of the device according to claim 4, characterized in that the thermal conductivity C p of at least one wall is controlled over a cycle period of the motor so that: - During the intake phase, the thermal conductivity is equal to the high value. - During the compression phase, the thermal conductivity is equal to the low value. - During the combustion phase, the thermal conductivity is equal to the low value. - During the exhaust phase, the thermal conductivity is equal to the high value. Procédé de pilotage de la conductivité thermique du dispositif selon la revendication 4, caractérisé en ce que la conductivité thermique Cp d'au moins une paroi est pilotée sur une période de cycle du moteur de façon que : - Durant la phase d'admission, la conductivité thermique est égale à la valeur haute. - Durant la phase de compression, la conductivité thermique est égale à la valeur basse. - Durant environ la première moitié de temps de la phase de combustion, la conductivité thermique est égale à la valeur basse. - Durant environ la deuxième moitié de temps de la phase de combustion, la conductivité thermique est égale à la valeur haute. - Durant la phase d'échappement, la conductivité thermique est égale à la valeur haute. A method for controlling the thermal conductivity of the device according to claim 4, characterized in that the thermal conductivity C p of at least one wall is controlled over a cycle period of the motor so that: - During the intake phase, the thermal conductivity is equal to the high value. - During the compression phase, the thermal conductivity is equal to the low value. - During about the first half of the combustion phase, the thermal conductivity is equal to the low value. - During about the second half of the combustion phase, the thermal conductivity is equal to the high value. - During the exhaust phase, the thermal conductivity is equal to the high value. Procédé de pilotage de la conductivité thermique du dispositif selon la revendication 4, caractérisé en ce que la conductivité thermique Cp d'au moins une paroi est pilotée sur une période de cycle du moteur de façon que : - Durant la phase d'admission, la conductivité thermique est égale à la valeur haute. - Durant la phase de compression, la conductivité thermique est égale à la valeur basse. - Durant environ la première moitié de temps de la phase de combustion, la conductivité thermique est égale à la valeur basse. - Durant environ la deuxième moitié de temps de la phase de combustion, la conductivité thermique est égale à la valeur haute. - Durant environ les deux tiers de la phase d'échappement, la conductivité thermique est égale à la valeur haute. - Durant environ le dernier tiers de la phase d'échappement, la conductivité thermique est égale à la valeur basse. A method for controlling the thermal conductivity of the device according to claim 4, characterized in that the thermal conductivity C p of at least one wall is controlled over a cycle period of the motor so that: - During the intake phase, the thermal conductivity is equal to the high value. - During the compression phase, the thermal conductivity is equal to the low value. - During about the first half of the combustion phase, the thermal conductivity is equal to the low value. - During about the second half of the combustion phase, the thermal conductivity is equal to the high value. - During about two-thirds of the exhaust phase, the thermal conductivity is equal to the high value. - During about the last third of the exhaust phase, the thermal conductivity is equal to the low value.
EP08163462A 2007-09-19 2008-09-02 Thermal engine and procedure for controlling the thermal conductivity of the surface of the combustion chamber Ceased EP2039813A1 (en)

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FR0757662A FR2921112B1 (en) 2007-09-19 2007-09-19 THERMAL MOTOR AND METHOD FOR CONTROLLING THE THERMAL CONDUCTIVE OF THE WALLS OF THE COMBUSTION CHAMBER

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1528160A (en) * 1975-08-08 1978-10-11 Nat Res Dev Silicon nitride based components
US4321898A (en) * 1977-11-16 1982-03-30 Robert Bosch Gmbh Internal combustion engine with temperature controlled combustion chamber walls
GB2148144A (en) * 1983-10-18 1985-05-30 Secr Defence Thermally active coating
WO1988007224A1 (en) 1987-03-18 1988-09-22 Dai Nippon Insatsu Kabushiki Kaisha Material having variable conductivity
JPH11236636A (en) 1998-02-20 1999-08-31 Toyota Central Res & Dev Lab Inc Thermal conductivity variable material
WO2005124790A2 (en) 2004-06-15 2005-12-29 Siemens Power Generation, Inc. High thermal conductivity materials aligned within resins
EP1681454A2 (en) * 2005-01-14 2006-07-19 Fuji Jukogyo Kabushiki Kaisha Cylinder liner and cylinder block
JP2007077951A (en) * 2005-09-16 2007-03-29 Aisin Seiki Co Ltd Piston for internal combustion engine

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1528160A (en) * 1975-08-08 1978-10-11 Nat Res Dev Silicon nitride based components
US4321898A (en) * 1977-11-16 1982-03-30 Robert Bosch Gmbh Internal combustion engine with temperature controlled combustion chamber walls
GB2148144A (en) * 1983-10-18 1985-05-30 Secr Defence Thermally active coating
WO1988007224A1 (en) 1987-03-18 1988-09-22 Dai Nippon Insatsu Kabushiki Kaisha Material having variable conductivity
JPH11236636A (en) 1998-02-20 1999-08-31 Toyota Central Res & Dev Lab Inc Thermal conductivity variable material
WO2005124790A2 (en) 2004-06-15 2005-12-29 Siemens Power Generation, Inc. High thermal conductivity materials aligned within resins
EP1681454A2 (en) * 2005-01-14 2006-07-19 Fuji Jukogyo Kabushiki Kaisha Cylinder liner and cylinder block
JP2007077951A (en) * 2005-09-16 2007-03-29 Aisin Seiki Co Ltd Piston for internal combustion engine

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