EP0980466B1 - Device for varying a piston engine effective volumetric displacement and/or volumetric ratio of during its operation - Google Patents

Abstract

A device for varying an effective volumetric displacement and/or an effective volumetric ratio of an engine which comprises a piston and a cylinder, the device comprising a first device for controlling the effective volumetric ratio of the engine by modifying a starting point of a stroke of the piston with respect to the cylinder, and a second device for controlling the effective volumetric displacement of the engine by discharging into an inlet pipe excess gases let into the cylinder of the engine.

Description

The present invention relates to a device for varying the displacement and / or effective displacement ratio of a piston engine during its operation.

The displacement of an engine usually designates the geometric characteristics of said motor defined by the stroke and the bore. We will retain here the notion of effective displacement represented by the volume of gas at atmospheric precision actually retained by the engine to perform each cycle.

The volumetric ratio is also, according to the usual language, a relation existing between the chamber volume and the volume defined by the stroke multiplied by the bore. We will retain here the volumetric ratio workforce determined by the effective compression ratio of fresh gases.

The maximum efficiency of internal combustion piston engines is general recorded at full load, i.e. throttle valve at full load opening, at speed or range of speed where the average effective pressure of the motor cycle is at its maximum value.

To these operating conditions correspond, for each engine, a defined power and speed. This amounts to saying that as soon as the work asked an engine does not meet these conditions of power and diet, its yield decreases.

The main characteristic of engines which defines their power and speed maximum efficiency, is their displacement.

In current use, particularly in the automotive field, the operating conditions of motors generating optimum efficiency are rarely met. Indeed, the engine displacement is constant and the the power demanded of them by the driver varies considerably.

In general, the more the working conditions imposed on the engine by the driver are away from his maximum performance conditions plus his yield is low.

In use at low power, for example during urban journeys, at even work, large displacement engines consume more energy than large displacement engines, due to a greater distance from their operating conditions generating maximum efficiency. The disadvantages of large displacement engines can become an advantage when conditions of use requiring high power, for example on highway at high speed.

In all cases, the engine power is adjusted mainly by acting on their diet through a box of speeds, and on their load through the throttle valve which controls the inlet pressure by rolling and changes the filling rate of the cylinder (s) and the average effective engine cycle pressure.

Another characteristic of engines determines their general performance: their volumetric ratio. This is defined by the relationship between the volume of the cylinder and the volume of the explosion chamber. This ratio is fixed, it is calculated taking into account the maximum load conditions of the motor and of the fuel used, however, at partial load or when the cylinder is insufficiently filled at high speeds, this ratio could be significantly increased to increase engine efficiency.

If the advantage of adapting the engine displacement to the work required of them is obvious, there are hardly any effective devices today enabling engines, and in particular automobile engines, to obtain this result.

However, devices have been tested which provide in particular for disengage or make passive a certain number of cylinders on engines multi-cylinder.

None of these devices, because of their cumbersome implementation and their relative effectiveness, could not be considered worthy of being reproduced in large number.

If it is advantageous, to maintain an optimal yield, to adapt the ratio volumetric of engines at filling conditions of their cylinder (s), especially at high speeds, no device provides a solution today relevant to achieve such a result.

This is to significantly improve the overall performance of engines internal piston combustion, taking into account their context of use variable, that the device according to the invention provides that any motor which is provided with it has features that distinguish it from an engine as defined according to rules of the prior art.

• Afin de rester à l'optimum de son rendement, le moteur adapte automatiquement sa cylindrée au travail qui lui est demandé, tenant compte des conditions de régime qui lui sont imposées.
• Associé à un dispositif de suralimentation le moteur peut être de plus petites dimensions qu'un moteur conventionnel en conservant une puissance élevée et ceci sans pénaliser le rendement à charge partielle.
• Lors de mauvaises conditions de remplissage de son(ses) cylindre(s), notamment à régime élevé, le moteur adapte son rapport volumétrique auxdites conditions de remplissage afin d'optimiser son rendement soit, il optimise son taux de compression effectif en fonction du régime.
• La puissance maximale du moteur est accrue notamment par amélioration du remplissage de son(ses) cylindre(s) à régime élevé.
• Le rendement du moteur est accru de façon importante sur l'essentiel de sa plage de puissance.
• Le rendement maximal du moteur peut être obtenu sur une plage de régime élargie.
• Les pertes en pompage sont réduites sur l'essentiel de la plage de puissance du moteur.
• Le régime de ralenti peut être abaissé grâce à la réduction des gaz brûlés résiduels.
• Le moteur peut fonctionner à rendement dégradé permettant un réchauffement rapide du catalyseur utilisé à l'échappement pour traiter les polluants.
• Les frottements pistons/cylindres sont réduits grâce au mode de guidage longitudinal du piston.
• Le régime à une moindre incidence sur le frottement.
• Les pièces mécaniques sont particulièrement ramassées et leur vitesse à l'exception du piston est réduite.
• L'ovalisation du(des) cylindre(s) par usure est réduite grâce à l'absence de poussée latérale sur le piston dû à l'obliquité de la bielle.

Thus, the device according to the invention has the following advantages according to a particular embodiment:

• In order to remain at optimum performance, the engine automatically adapts its displacement to the work requested of it, taking into account the operating conditions which are imposed on it.
• Associated with a supercharging device, the engine can be smaller than a conventional engine while retaining a high power and this without penalizing the efficiency at partial load.
• During poor filling conditions of its cylinder (s), in particular at high speed, the engine adapts its volumetric ratio to said filling conditions in order to optimize its performance, either, it optimizes its effective compression ratio as a function of the speed .
• The maximum power of the engine is increased in particular by improving the filling of its cylinder (s) at high speed.
• The efficiency of the engine is increased significantly over most of its power range.
• Maximum engine efficiency can be obtained over a wider speed range.
• Pumping losses are reduced over most of the engine's power range.
• The idle speed can be lowered by reducing the residual burnt gas.
• The engine can operate at degraded efficiency allowing rapid heating of the catalyst used in the exhaust to treat pollutants.
• Piston / cylinder friction is reduced thanks to the piston's longitudinal guide mode.
• The regime has a lesser impact on friction.
• The mechanical parts are particularly picked up and their speed except for the piston is reduced.
• The ovalization of the cylinder (s) by wear is reduced thanks to the absence of lateral thrust on the piston due to the obliquity of the connecting rod.

In addition, the device according to the invention provides in particular that:

At low displacement, the engine cycle exploits a longer expansion stroke than the stroke used to compress the gases, the expansion diagram being then truncated later than on an engine of the same displacement as defined according to prior art.

• Un système permettant de contrôler durant son fonctionnement le rapport volumétrique du moteur. Le système agit par modification de l'origine de la course du piston par rapport au cylindre sans modifier la longueur de ladite course.
• Un système de contrôle de la cylindrée effective du moteur. Le système opère par refoulement dans la tubulure d'admission d'une partie des gaz admis dans le cylindre du moteur grâce au concours d'une soupape d'admission additionnelle. En fonctionnement à cylindrée réduite, la fermeture de la soupape d'admission additionnelle peut être retardée de façon significative afin que le piston refoule durant son ascension dans le cylindre les gaz admis en excès et que le début de compression des gaz ait lieu plus tard durant la course ascensionnelle du piston. Selon une variante du dispositif selon l'invention, la soupape d'admission telle que définie selon l'art antérieur peut elle-même être utilisée à cette tâche, ceci en contrôlant ses diagrammes d'ouverture et de fermeture.

At low displacement, the time necessary for the compression of the gases is reduced, this limits the time of confinement of the gases favorable to the triggering of undesirable detonation effects.
To achieve these results, the device according to the invention comprises, according to a first characteristic:

• A system allowing the volumetric ratio of the engine to be controlled during operation. The system acts by modifying the origin of the stroke of the piston relative to the cylinder without modifying the length of said stroke.
• A system for monitoring the effective displacement of the engine. The system operates by pushing back into the intake manifold part of the gases admitted into the engine cylinder thanks to the assistance of an additional intake valve. In reduced cylinder operation, the closing of the additional intake valve can be significantly delayed so that the piston expels excess inlet gases during its ascent into the cylinder and the start of gas compression takes place later during the upward stroke of the piston. According to a variant of the device according to the invention, the intake valve as defined according to the prior art can itself be used for this task, this by checking its opening and closing diagrams.

• Un piston muni d'une crémaillère montée solidairement de sa partie inférieure, ladite crémaillère constituant l'une des parties d'un système d'engrènement, et étant maintenue dans un système de guidage qui lui autorise un mouvement de translation longitudinale.
• Une crémaillère de commande montée dans une cavité ou sur un guide aménagés dans le bloc moteur qui lui autorisent un mouvement de translation longitudinale, la position de ladite crémaillère de commande étant contrôlée par un dispositif de contrôle.
• Une bielle montée libre sur le vilebrequin du moteur qui comporte en sa partie supérieure un engrenage monté libre, ledit engrenage constituant l'élément de transmission du mouvement entre le piston et ladite bielle.
• Une soupape d'admission additionnelle dont l'arbre à cames qui commande son ouverture/fermeture est asservie à un dispositif qui contrôle son décalage angulaire par rapport au vilebrequin du moteur, ceci permettant de modifier le décalage angulaire du point de fermeture et d'ouverture de ladite soupape par rapport au vilebrequin.

This device according to the invention comprises in particular for a displacement:

• A piston provided with a rack mounted integrally with its lower part, said rack constituting one of the parts of a meshing system, and being held in a guide system which allows it a movement of longitudinal translation.
• A control rack mounted in a cavity or on a guide arranged in the engine block which allows it a longitudinal translational movement, the position of said control rack being controlled by a control device.
• A connecting rod mounted freely on the crankshaft of the engine which comprises in its upper part a free mounted gear, said gear constituting the element for transmitting movement between the piston and said connecting rod.
• An additional intake valve whose camshaft which controls its opening / closing is controlled by a device which controls its angular offset relative to the engine crankshaft, this making it possible to modify the angular offset of the closing and opening point of said valve relative to the crankshaft.

• Des sondes transmettant divers paramètres de fonctionnement du moteur ;
• Un ou plusieurs calculateurs ou dispositifs effectuant le traitement desdits paramètres ;
• Un dispositif de contrôle qui permet d'agir sur la position de la crémaillère de commande tenant compte du résultat du traitement des paramètres en provenance desdites sondes ;
• Un dispositif d'asservissement qui permet d'agir sur le décalage angulaire de l'arbre à cames commandant l'ouverture de la soupape d'admission additionnelle tenant compte du résultat du traitement des paramètres en provenance desdites sondes.

According to a particular embodiment, its operation requires:

• Probes transmitting various engine operating parameters;
• One or more computers or devices processing said parameters;
• A control device which makes it possible to act on the position of the control rack taking account of the result of the processing of the parameters coming from said probes;
• A servo device which makes it possible to act on the angular offset of the camshaft controlling the opening of the additional intake valve taking into account the result of the processing of the parameters coming from said probes.

• Un piston solidaire dans sa partie inférieure d'une crémaillère et qui assure la même fonction que le piston de tout moteur tel que défini selon les règles de l'art antérieur. Seul diffère son mode de transmission mécanique du mouvement au vilebrequin ;
• Une bielle montée libre sur le vilebrequin qui assure la même fonction que la bielle de tout moteur tel que défini selon les règles de l'art antérieur. Seul diffère son mode de liaison mécanique avec le piston ;
• Un engrenage monté libre en la partie supérieure de la bielle et qui est assujetti au déplacement du piston par l'intermédiaire du système d'engrènement qu'il constitue avec la crémaillère solidaire de la partie inférieure dudit piston d'une part, et la crémaillère de commande montée dans une cavité ou sur un guide, aménagés dans le bloc moteur et maintenue en position par son dispositif de contrôle d'autre part. L'engrenage est prévu pour constituer l'organe de transmission du mouvement entre le piston et la bielle ;
• Un dispositif de contrôle qui permet d'agir sur la position de la crémaillère de commande et qui comprend:
• * Au moins un vérin hydraulique ou tout autre système permettant d'imprimer un mouvement de translation à la crémaillère de commande et rendu solidaire de ladite crémaillère de commande par une quelconque liaison mécanique ;
• * Au moins un vérin hydraulique ou tout autre système permettant de constituer un dispositif qui contrôle le décalage angulaire de l'arbre à cames qui commande l'ouverture de la soupape d'admission additionnelle, ledit vérin hydraulique pouvant agir, selon un mode particulier de réalisation et à titre d'exemple non limitatif, sur la position d'une poulie additionnelle faisant ainsi varier la longueur de courroie ou de chaíne située entre la poulie de l'arbre à cames des soupapes d'admission et d'échappement du moteur tel que défini selon l'art antérieur, et la poulie de l'arbre à cames de la soupape d'admission additionnelle ;
• Et un dispositif qui contrôle le décalage angulaire de l'arbre à cames commandant l'ouverture de la soupape d'admission additionnelle et qui n'agit pas nécessairement sur l'arbre à cames commandant les soupapes d'admission et d'échappement du moteur tel que défini selon les règles de l'art antérieur.

Finally, the device according to the invention comprises:

• A piston integral in its lower part with a rack and which performs the same function as the piston of any engine as defined according to the rules of the prior art. The only difference is its mode of mechanical transmission of the movement to the crankshaft;
• A connecting rod mounted freely on the crankshaft which performs the same function as the connecting rod of any engine as defined according to the rules of the prior art. The only difference is its mode of mechanical connection with the piston;
• A gear mounted freely in the upper part of the connecting rod and which is subject to the displacement of the piston by means of the meshing system which it constitutes with the rack integral with the lower part of said piston on the one hand, and the rack control mounted in a cavity or on a guide, arranged in the engine block and held in position by its control device on the other hand. The gear is designed to constitute the member for transmitting the movement between the piston and the connecting rod;
• A control device which makes it possible to act on the position of the control rack and which comprises:
• * At least one hydraulic cylinder or any other system making it possible to impart a translational movement to the control rack and made integral with said control rack by any mechanical connection;
• * At least one hydraulic cylinder or any other system making it possible to constitute a device which controls the angular offset of the camshaft which controls the opening of the additional intake valve, said hydraulic cylinder being able to act, according to a particular mode of embodiment and by way of nonlimiting example, on the position of an additional pulley thus varying the length of belt or chain located between the pulley of the camshaft of the intake and exhaust valves of the engine such as defined according to the prior art, and the pulley of the camshaft of the additional intake valve;
• And a device which controls the angular offset of the camshaft controlling the opening of the additional intake valve and which does not necessarily act on the camshaft controlling the intake and exhaust valves of the engine as defined according to the rules of the prior art.

• Le déplacement et le maintien permanent à la position souhaitée de la crémaillère de commande sont assurés sans pompe hydraulique ;
• Le contrôle de la position de la crémaillère de commande et donc du volume de chambre d'explosion du moteur peut être obtenu avec un dispositif d'asservissement de très faible puissance ;
• Tout transfert de fluide hydraulique nécessaire à tout changement de position de la crémaillère de commande est assuré sans pompe hydraulique auxiliaire. Selon l'invention, le vérin hydraulique utilisé pour effectuer tout changement de position de ladite crémaillère de commande opère lui-même lesdits transferts en utilisant pour cela les changements permanents du sens de l'effort auquel il est soumis ;
• La correction de la position de la crémaillère de commande s'effectue automatiquement et de façon permanente durant le fonctionnement du moteur ;
• Le dispositif est particulièrement robuste et simple à réaliser, il ne fait en outre appel qu'à des techniques de réalisation bien connues de l'art antérieur ;

In order to limit the production cost of the variable displacement engine and to minimize the power consumption of the control device making it possible to act on the position of the control rack, the latter has, according to a particular embodiment, the following advantages:

• The permanent rack is moved and kept in the desired position without a hydraulic pump;
• Control of the position of the control rack and therefore of the volume of the engine's explosion chamber can be obtained with a very low-power servo device;
• Any transfer of hydraulic fluid necessary for any change of position of the control rack is ensured without an auxiliary hydraulic pump. According to the invention, the hydraulic cylinder used to effect any change in position of said control rack itself operates said transfers using for this permanent changes in the direction of the force to which it is subjected;
• The position of the control rack is corrected automatically and permanently during engine operation;
• The device is particularly robust and simple to produce, it also only uses production techniques that are well known in the prior art;

• Le contrôle de la position de la crémaillère de commande est suffisamment précis pour permettre un contrôle précis du rapport volumétrique du moteur ;
• La précision de contrôle de la position de la crémaillère de commande est peu altérée durant toute la durée de vie du moteur, et toute fuite de liquide hydraulique est automatiquement compensée de façon permanente.

The control system provides in particular that:

• The control of the position of the control rack is precise enough to allow precise control of the volumetric ratio of the engine;
• The precision of controlling the position of the control rack is little altered throughout the life of the engine, and any leakage of hydraulic fluid is automatically compensated for permanently.

• Un corps de vérin monté fixe par rapport au bloc moteur parallèlement à la crémaillère de commande ;
• Un couvercle de vérin monté fixe par rapport au corps de vérin ;
• Un piston de vérin, un axe de vérin et un prolongateur d'axe de vérin assemblés avec la crémaillère de commande, qui constituent le système de guidage supérieur de ladite crémaillère de commande du moteur et qui peuvent se déplacer longitudinalement par rapport au corps de vérin;
• Une tige de contrôle positionnée parallèlement à l'axe de vérin comportant un épaulement et pouvant se déplacer longitudinalement, ladite tige de contrôle traversant de part en part le couvercle de vérin, le corps de vérin et le piston de vérin grâce à des orifices aménagés dans lesdits couvercle de vérin, corps de vérin et piston de vérin;
• Des valves logées dans un conduit aménagé dans la masse du piston de vérin, permettant d'autoriser ou d'interdire la circulation du fluide hydraulique entre les chambres supérieure et inférieure du vérin telles que définies par la position du piston de vérin relative au corps de vérin ;
• Un clapet anti-retour logé dans un conduit d'arrivée de fluide hydraulique dont l'orifice débouche dans la partie centrale du corps de vérin ledit clapet anti-retour autorisant l'entrée du fluide hydraulique dans le corps de vérin, mais en interdisant la sortie ;
• Des ressorts assurant le maintien en contact sur leur siège des valves et clapets ;
• Des dispositifs d'étanchéité pouvant être constitués, selon un mode particulier de réalisation selon l'invention, de joints toriques en caoutchouc.

To achieve these results, the control device which acts on the position of the control rack comprises:

• A cylinder body mounted fixed relative to the engine block parallel to the control rack;
• A cylinder cover mounted fixed relative to the cylinder body;
• A cylinder piston, a cylinder axis and a cylinder axis extender assembled with the control rack, which constitute the upper guide system of said engine control rack and which can move longitudinally relative to the cylinder body ;
• A control rod positioned parallel to the cylinder axis having a shoulder and being able to move longitudinally, said control rod passing right through the cylinder cover, the cylinder body and the cylinder piston by means of orifices arranged in said cylinder cover, cylinder body and cylinder piston;
• Valves housed in a conduit arranged in the mass of the cylinder piston, making it possible to authorize or prohibit the circulation of hydraulic fluid between the upper and lower chambers of the cylinder as defined by the position of the cylinder piston relative to the body of cylinder;
• A non-return valve housed in a hydraulic fluid inlet duct, the orifice of which opens into the central part of the cylinder body, said non-return valve allowing the entry of hydraulic fluid into the cylinder body, but by preventing the exit ;
• Springs ensuring the maintenance in contact on their seat of the valves and valves;
• Sealing devices which can be made, according to a particular embodiment according to the invention, of rubber O-rings.

According to a particular embodiment, its operation requires one or more low-power servo means making it possible to act on the longitudinal position of the control rod relative to the cylinder body, holding account of the engine operating requirements.

• Un conduit longitudinal excentré qui est aménagé dans la masse du piston de vérin et qui relie les surfaces circulaires inférieure et supérieure dudit piston de vérin. Le conduit est réalisé de telle sorte qu'il constitue un logement pour les deux valves permettant d'autoriser ou d'interdire la circulation du fluide hydraulique. Le conduit est d'un diamètre supérieur à celui des valves afin de permettre l'écoulement du fluide au travers dudit conduit lorsque lesdites valves sont ouvertes ;
• Un conduit longitudinal excentré qui est aménagé dans la masse du piston de vérin et qui assure le guidage longitudinal de la tige de contrôle ;
• Un piston de vérin qui comporte une cavité sur sa surface cylindrique en regard avec l'orifice d'arrivée de fluide hydraulique débouchant dans la partie centrale du corps de vérin. La cavité est d'une hauteur au moins équivalente à la course maximale du piston de vérin et est reliée au conduit longitudinal excentré aménagé dans la masse du piston de vérin ;
• Des valves qui permettent d'autoriser ou d'interdire la circulation du fluide hydraulique entre les chambres supérieure et inférieure du vérin telles que définies par la position du piston de vérin relative au corps de vérin. Les valves sont constituées de bagues pouvant coulisser autour de la tige de contrôle. Le diamètre intérieur des valves est inférieur au diamètre de l'épaulement de la tige de contrôle. Lorsque les valves ne sont pas maintenues ouvertes par l'épaulement de la tige de contrôle, elles sont maintenues sur leur siège par des ressorts ;
• Un épaulement de la tige de contrôle qui assure le centrage de ladite tige de contrôle dans le conduit longitudinal excentré aménagé dans la masse du piston de vérin. L'épaulement permet de déplacer l'une ou l'autre des valves permettant d'autoriser ou d'interdire la circulation du fluide hydraulique entre les chambres supérieure et inférieure du vérin. L'épaulement est pourvu de rainures ou de gorges autorisant la circulation du fluide au travers du conduit ;
• Un clapet anti-retour qui est logé dans le conduit d'arrivée de fluide hydraulique dont l'orifice débouche dans la partie centrale du corps de vérin et qui peut être constitué, selon un mode particulier de réalisation, d'une bille maintenue sur une portée par un ressort et obturant un orifice ;
• Un conduit d'arrivée de fluide hydraulique dont l'orifice débouche dans la partie centrale du corps de vérin et qui peut être connecté, selon un mode particulier de réalisation, au circuit hydraulique sous pression assurant la lubrification du moteur à cylindrée variable.

The control device making it possible to act on the position of the control rack comprises:

• An eccentric longitudinal duct which is arranged in the mass of the cylinder piston and which connects the lower and upper circular surfaces of said cylinder piston. The duct is designed so that it constitutes a housing for the two valves making it possible to authorize or prohibit the circulation of the hydraulic fluid. The conduit is of a diameter greater than that of the valves in order to allow the flow of the fluid through said conduit when said valves are open;
• An eccentric longitudinal duct which is arranged in the mass of the cylinder piston and which ensures the longitudinal guidance of the control rod;
• A cylinder piston which has a cavity on its cylindrical surface opposite the hydraulic fluid inlet orifice opening into the central part of the cylinder body. The cavity is of a height at least equivalent to the maximum stroke of the jack piston and is connected to the eccentric longitudinal duct arranged in the mass of the jack piston;
• Valves which allow the circulation of hydraulic fluid between the upper and lower chambers of the cylinder to be authorized or prohibited as defined by the position of the cylinder piston relative to the cylinder body. The valves consist of rings which can slide around the control rod. The inside diameter of the valves is less than the diameter of the shoulder of the control rod. When the valves are not kept open by the shoulder of the control rod, they are held in their seats by springs;
• A shoulder of the control rod which centers said control rod in the eccentric longitudinal duct arranged in the mass of the cylinder piston. The shoulder makes it possible to move one or the other of the valves making it possible to authorize or prohibit the circulation of the hydraulic fluid between the upper and lower chambers of the jack. The shoulder is provided with grooves or grooves allowing the circulation of the fluid through the conduit;
• A non-return valve which is housed in the hydraulic fluid inlet pipe, the orifice of which opens into the central part of the jack body and which may consist, according to a particular embodiment, of a ball held on a carried by a spring and closing a hole;
• A hydraulic fluid inlet conduit whose orifice opens into the central part of the jack body and which can be connected, according to a particular embodiment, to the pressurized hydraulic circuit ensuring the lubrication of the variable displacement engine.

• Un premier dispositif permettant de contrôler le rapport volumétrique du moteur en agissant par modification de l'origine de la course du piston par rapport au cylindre sans modifier la longueur de ladite course ;
• Et un second dispositif permettant de contrôler la cylindrée effective du moteur en opérant par refoulement des gaz admis en excès dans le cylindre du moteur dans la tubulure d'admission et par ajustement de la longueur de la course ascensionnelle du piston utilisée pour compresser les gaz.

The device according to the invention making it possible to vary the effective displacement and / or the volumetric ratio of a piston engine during its operation, comprises:

• A first device making it possible to control the volumetric ratio of the engine by acting by modifying the origin of the stroke of the piston relative to the cylinder without modifying the length of said stroke;
• And a second device making it possible to control the effective displacement of the engine by operating by repressing the gases admitted in excess into the cylinder of the engine in the intake manifold and by adjusting the length of the upward stroke of the piston used to compress the gases.

• Une crémaillère solidaire de la partie inférieure du piston et qui est maintenue dans un système de guidage autorisant un mouvement de translation longitudinale à ladite crémaillère ;
• Une crémaillère de commande guidée en translation longitudinale dans le bloc moteur ;
• Un dispositif permettant de contrôler la position de la crémaillère de commande ;
• Et un engrenage monté libre sur une bielle également libre sur un vilebrequin de manière que l'engrenage soit disposé entre les deux crémaillères pour constituer l'élément de transmission du mouvement entre le piston et la bielle.

The device according to the present invention comprises a first device making it possible to control the volumetric ratio of the engine constituted by a gear system which comprises:

• A rack integral with the lower part of the piston and which is held in a guide system allowing a longitudinal translational movement to said rack;
• A control rack guided in longitudinal translation in the engine block;
• A device for controlling the position of the control rack;
• And a gear mounted free on a connecting rod also free on a crankshaft so that the gear is disposed between the two racks to constitute the element for transmitting movement between the piston and the connecting rod.

The device according to the present invention comprises a second device to control the effective displacement of the engine consisting of a valve additional intake and a device that controls its opening / closing and which allows you to modify the angular offset of the closing point and opening of said valve relative to the crankshaft.

The device according to the present invention comprises a second device to control the effective displacement of the engine without valve additional intake consisting of a device that controls the opening and closing of the inlet valve known per se and which makes it possible to modify the angular offset of the point of closure and opening of said valve by compared to the crankshaft.

The device according to the present invention comprises a device controlling opening and closing the additional intake valve which is a camshaft controlled by a device which controls its angular offset by compared to the engine crankshaft.

The device according to the present invention comprises a device controlling opening and closing of the inlet valve known per se which is consisting of an additional camshaft controlled by a device which controls its angular offset from the engine crankshaft, said camshaft additional actuating said valve via a mechanical connection in addition to the movement imparted to said valve by its camshaft.

The device according to the present invention comprises a device controlling the angular offset of the camshaft controlling the opening of the valve additional intake which consists of an intermediate pulley whose position defines the length of the timing belt or chain included between the camshaft pulley of the intake and exhaust valves of the engine and the camshaft pulley which controls the opening of the additional intake valve.

The device according to the present invention comprises a device controlling the position of the control rack which consists of a hydraulic cylinder which acts on said rack by means of a mechanical connection.

The device according to the present invention comprises a device which controls the position of the intermediate pulley consisting of a hydraulic cylinder.

The device according to the present invention comprises a gear having a truncated profile so as to keep only the teeth useful for the transmission of movement between the piston and the connecting rod.

The device according to the present invention comprises rolling surfaces which are fitted respectively on the gear and the racks ensuring the permanent centering of said gear between said racks, while the point of contact between said rolling surfaces is permanently positioned at the level of the gear primitive.

The device according to the present invention comprises a piston, the part of which cylindrical is of sufficient height to accommodate segments, but does not has no skirt ensuring its longitudinal guidance.

• Un vérin hydraulique comportant des moyens pour le prolongement de son axe permettant de conserver un volume de fluide déplacé en fonction de la course du piston de vérin qui est identique pour chacune des chambres supérieure et inférieure dudit vérin.
• Des moyens de contrôle qui permettent de déplacer vers une position déterminée ou de maintenir dans une position déterminée l'axe du vérin par rapport au corps du vérin.

The device making it possible to vary the effective displacement and / or the volumetric ratio of a piston engine comprises a device controlling the position of the control rack which comprises:

• A hydraulic cylinder comprising means for extending its axis making it possible to maintain a volume of fluid displaced as a function of the stroke of the cylinder piston which is identical for each of the upper and lower chambers of said cylinder.
• Control means which make it possible to move towards a determined position or to maintain in a determined position the axis of the jack with respect to the body of the jack.

• Un corps de vérin monté fixe par rapport au bloc moteur parallèlement à la crémaillère de commande, un couvercle de vérin monté fixe par rapport au corps de vérin, un piston de vérin, un axe de vérin et un prolongateur d'axe de vérin assemblés avec la crémaillère de commande, qui constituent le système de guidage supérieur de ladite crémaillère de commande et qui peuvent se déplacer longitudinalement par rapport au corps de vérin ;
• Des moyens de contrôle qui sont constitués d'une tige de contrôle comportant un épaulement et pouvant se déplacer longitudinalement, ladite tige de contrôle étant positionnée parallèlement à l'axe de vérin et traversant de part en part le couvercle de vérin, le corps de vérin et le piston de vérin grâce à des orifices aménagés dans lesdits couvercle de vérin, corps de vérin et piston de vérin, de valves logées dans un conduit placé longitudinalement et de façon excentrée aménagé dans la masse du piston de vérin, lesdites valves permettant d'autoriser ou d'interdire la circulation du fluide hydraulique entre les chambres supérieure et inférieure du vérin telles que définies par la position du piston de vérin relative au corps de vérin, lesdites valves étant constituées de bagues qui peuvent coulisser autour de la tige de contrôle, et leur diamètre intérieur étant inférieur au diamètre de l'épaulement de la tige de contrôle de telle sorte qu'il soit possible de les maintenir ouvertes grâce audit épaulement de ladite tige de contrôle, lorsque lesdites valves ne sont pas maintenues ouvertes par ledit épaulement de ladite tige de contrôle, elles sont maintenues sur leur siège par des ressorts, et d'un clapet anti-retour logé dans un conduit d'arrivée de fluide hydraulique dont l'orifice débouche dans la partie centrale du corps de vérin, ledit clapet anti-retour autorisant l'entrée du fluide hydraulique dans le corps de vérin, mais en interdisant la sortie.

The device according to the present invention comprises a control device which comprises:

• An actuator body mounted fixed relative to the engine block parallel to the control rack, an actuator cover mounted fixed relative to the actuator body, an actuator piston, an actuator axis and an actuator axis extension assembled with the control rack, which constitute the upper guide system of said control rack and which can move longitudinally relative to the cylinder body;
• Control means which consist of a control rod having a shoulder and being able to move longitudinally, said control rod being positioned parallel to the cylinder axis and passing right through the cylinder cover, the cylinder body and the cylinder piston by means of orifices arranged in said cylinder cover, cylinder body and cylinder piston, of valves housed in a conduit placed longitudinally and eccentrically arranged in the mass of the cylinder piston, said valves making it possible to authorize or prohibit the circulation of hydraulic fluid between the upper and lower chambers of the jack as defined by the position of the jack piston relative to the jack body, said valves being made up of rings which can slide around the control rod, and their internal diameter being less than the diameter of the shoulder of the control rod so that it either possible to keep them open thanks to said shoulder of said control rod, when said valves are not kept open by said shoulder of said control rod, they are held in their seats by springs, and of a non-return valve housed in a hydraulic fluid inlet conduit, the orifice of which opens into the central part of the jack body, said non-return valve allowing the entry of hydraulic fluid into the jack body, but preventing the outlet.

The device according to the present invention comprises a control device which comprises a cylinder piston provided with a cavity on its cylindrical surface in look with the orifice of the hydraulic fluid inlet duct opening into the central part of the cylinder body, said cavity being at least a height equivalent to the maximum stroke of said cylinder piston and being connected to the conduit placed longitudinally and eccentrically arranged in the mass of said cylinder piston connecting the lower and upper circular surfaces of said piston cylinder, by a connecting channel.

The device according to the present invention comprises a control device which includes a non-return valve made up of a ball held on a surface by a spring and closing a hole.

The device according to the present invention comprises a control device which includes a hydraulic fluid inlet conduit, one of the ports opens into the central part of the cylinder body and which is connected to the circuit hydraulic under pressure ensuring the lubrication of the displacement engine variable.

The device according to the present invention comprises a control device which has sealing elements made of rubber O-rings.

The device according to the present invention comprises a control device whose the shoulder ensures the centering of the control rod in the duct placed longitudinally and eccentrically arranged in the mass of said piston cylinder, said shoulder having grooves or grooves allowing the circulation of hydraulic fluid through said conduit.

La figure 1 est une vue de face en coupe schématique du dispositif selon l'invention.

La figure 2 est une vue de droite en coupe schématique selon la ligne A-A de la figure 1 du dispositif selon l'invention.

La figure 3 est une vue en coupe schématique du dispositif de commande d'ouverture de la soupape d'admission telle que définie selon l'art antérieur, qui, selon une variante du dispositif selon l'invention, peut être utilisée pour contrôler la cylindrée du moteur.

La figure 4 est une vue en perspective mettant en évidence la disposition des principaux éléments qui constituent le dispositif selon l'invention.

La figure 5 est une vue d'ensemble mettant en évidence le positionnement du dispositif de contrôle selon l'invention qui permet d'agir sur la position de la crémaillère de commande par rapport aux autres éléments constituants le moteur à cylindrée variable, et la représentation d'une variante de réalisation du système d'engrènement.

La figure 6 est une vue de face en coupe schématique du dispositif de contrôle de la crémaillère de commande.

La figure 7 est une vue en perspective mettant en évidence la disposition et l'apparence des principaux éléments qui constituent le dispositif de contrôle de la position de la crémaillère de commande selon l'invention.

Other characteristics and advantages of the present invention will appear better on reading the description which follows, made in relation to the appended drawings in which:

Figure 1 is a schematic sectional front view of the device according to the invention.

Figure 2 is a schematic sectional right view along line AA of Figure 1 of the device according to the invention.

Figure 3 is a schematic sectional view of the opening control device of the intake valve as defined according to the prior art, which, according to a variant of the device according to the invention, can be used to control the displacement of the motor.

Figure 4 is a perspective view showing the arrangement of the main elements which constitute the device according to the invention.

Figure 5 is an overview showing the positioning of the control device according to the invention which allows to act on the position of the control rack relative to the other components of the variable displacement motor, and the representation of an alternative embodiment of the meshing system.

Figure 6 is a schematic sectional front view of the control rack control device.

Figure 7 is a perspective view showing the arrangement and appearance of the main elements which constitute the device for controlling the position of the control rack according to the invention.

As can be seen in the figures, the device according to the invention is inserted in an environment well known from the prior art: piston engines.

In FIGS. 1 to 4, an engine has been shown comprising a piston 1, a cylinder 2, valves 3, 4, 15 or 22, an engine block 5, a cylinder head 6, a crankshaft 7, a spark plug 8 and an explosion chamber 9.

The function of these organs is, according to the invention, unchanged having regard to the state prior art.

The device according to the invention essentially comprises a rack 10 integral with the lower part of the piston 1, a control rack 11 mounted in a cavity or on a guide, arranged in the engine block 5, a device 12 which controls the position of said control rack by report to the engine block. It also includes a connecting rod 13 mounted freely on the crankshaft 7 of the engine and which comprises in its upper part a gear 14 free mounted.

Note that the cylindrical part of the piston 1 is of sufficient height to accommodate segments, but does not have a skirt ensuring its guidance longitudinal (Figure 5).

It is noted that according to a particular embodiment, the gear 14 may have a truncated profile so as to retain only the teeth useful for the transmission of movement between the piston 1 and the connecting rod 13 (Figure 5).
It can be seen that the rolling surfaces are arranged respectively on the gear 14 and the racks 10, 11 ensuring the permanent centering of said gear between said racks, while the point of contact between said rolling surfaces is permanently positioned at the level of the primitive of gear 14 (Figure 5).

The device according to the invention further comprises an intake valve additional 15 whose camshaft 16 controlling its opening is controlled to a device 17 which controls its angular offset relative to the crankshaft 7 of the engine.

According to a variant, the function fulfilled by the additional intake valve 15 can be assumed by the inlet valve 22 as defined according to art anterior as shown in Figure 3.

An additional device then makes it possible to modify the angular offset of the point closing and opening the valve 22 relative to the crankshaft 7. The additional device may include an additional camshaft 21 slaved to a device not shown which controls its angular offset relative to the engine crankshaft. Additional camshaft 21 actuates the valve intake 22 via a mechanical link 23 in addition to movement imparted to said valve by its camshaft 24 as defined according to the prior art.

The device according to the invention can also include various accessories not represented such as probes transmitting various parameters of engine operation, one or more computers or devices performing the processing of information from said probes and a system for securing the device 12 which controls the position of the rack control 11 relative to the engine block 5 and the device 17 which controls the angular offset of the additional intake valve 15 to the result of the processing of information from said probes.

The operation of the device making it possible to vary the displacement and / or the effective displacement ratio of a piston engine is as follows:

Modifying the effective displacement of the engine while keeping a report adequate volumetric is effected by the combined action of devices allowing to control during its operation the volumetric ratio of the engine of a part and the effective displacement of said motor on the other hand.

The engine's volumetric ratio is checked by position control origin of the stroke of the piston 1 relative to the cylinder 2, without modifying the length of said stroke.

The effective displacement of the engine is checked as follows:

The control device 12 of the rack 11 receives the order to move said control rack 11. This order is materialized, for example, by the introduction into a hydraulic cylinder 25 of a certain volume of oil under pressure from a pump (not shown).

The volume introduced is calculated beforehand by the device (s) (not represented) processing information from probes parametric parameters of the engine (not shown). The action of the control system 12 on the control rack 11 via a link mechanical 20 has the effect of printing on said control rack 11 a translational movement parallel to its longitudinal axis.

The control rack 11 constitutes a gear system with the gear 14 mounted freely in the upper part of the connecting rod 13 and the rack 10 secured to the lower part of the piston 1. The displacement of the control rack 11 implies a modification of the point of origin of the stroke of piston 1 relative to cylinder 2. Changing the point of origin of the effect of the stroke is to modify the volume of the explosion chamber 9, the length of said stroke being unchanged, the volumetric ratio of the engine is amended.

The effective displacement of the engine is also checked as follows:

The device 17 which controls the angular offset of the camshaft 16 which controls the opening of the additional intake valve 15 receives the order delay or advance the closing of said intake valve additional 15.

This order is materialized according to a particular embodiment of the device 17 by the introduction into a hydraulic cylinder 26 of a certain volume pressurized oil from a pump (not shown).

The volume introduced is calculated beforehand by the device (s) not represented performing the processing of information from probes parametric parameters of the engine (not shown).

The hydraulic cylinder 26 can act on the position of an intermediate pulley 18 which modifies the length of timing belt 27 or chain between the pulley 28 of the camshaft 24 of the intake 3 and exhaust 4 valves of the engine, and the pulley 29 of the camshaft 16 which controls the opening of the additional intake valve 15.

According to the invention, a delay calculated at the closing of the intake valve additional 15 has the effect of allowing the piston 1 to flow back into the tubing intake 19 a certain quantity of fresh gas admitted in excess on the one hand, and to use only part of the length of the stroke of the piston 1 for compress the gases on the other hand. According to a characteristic of the invention, on multi-cylinder engine, fresh gases being pumped into the intake manifold 19 can be re-aspirated by a neighboring cylinder during the intake phase.

The device according to the invention provides that the ratio between the volume of the explosion chamber defined by the system which controls the volumetric ratio and the length of the piston stroke used to compress the fresh gases may not not remain constant, this in order to allow the engine to work according to the highest possible effective volume ratio authorized by the conditions of operation of said engine.

In operation, the effective displacement of the engine and its ratio effective volumetric are permanently subject to optimization requirements engine performance.

FIGS. 5 to 7 show an alternative embodiment of the device 12 which controls the position of the control rack 11 relative to the block motor 5.

The control device 12 essentially comprises a cylinder body 45 mounted fixed relative to the engine block 5 parallel to the control rack 11, a jack cover 46 mounted fixed relative to the jack body 45, a cylinder piston 47, cylinder axis 48 and cylinder axis extension 49 assembled with the control rack 11, which constitute the upper guide of said control rack 11 and which can be move longitudinally with respect to the cylinder body 45.

In FIGS. 6 and 7 the device 12 has been shown comprising control means 42 which consist of a control rod 50 provided with a shoulder 51 and able to move longitudinally.

The control rod 50 is positioned parallel to the cylinder axis 48 and goes right through the cylinder cover 46, the cylinder body 45 and the piston actuator 47 by means of conduits arranged in said actuator covers 46, cylinder body 45 and cylinder piston 47.

The control means 42 also consist of valves 52, 53 housed in a conduit 54 arranged in the mass of the cylinder piston 47.

The valves 52, 53 allow to authorize or prohibit the circulation of the fluid hydraulic between the upper 40 and lower 41 chambers of the jack such as defined by the position of the cylinder piston 47 relative to the cylinder body 45. The valves 52, 53 consist of rings which can slide around the stem check 50. The inside diameter of the rings is expected to be less than the diameter of the shoulder 51 of the control rod 50 so that it is possible to keep open thanks to the shoulder 51. When the valves 52, 53 do not are not kept open by the shoulder 51, they are kept on their seat by springs 55, 56.

The control means 42 consist of a non-return valve 43 housed in a hydraulic fluid inlet pipe 57, one of the orifices of which opens out in the central part of the cylinder body 45. The non-return valve 43 authorizes the entry of hydraulic fluid into the cylinder body 45, but prohibits the exit. The valve 43 may consist, according to a particular embodiment, of a ball 58 held on a seat by a spring 59 in order to close an orifice 44.

The control means 42 of the device 12 provide that the cylinder piston 47 has a cavity 30 on its cylindrical surface facing the conduit inlet 57 provided in the central part of the cylinder body 45. The cavity 30 is of a height at least equivalent to the maximum stroke of the cylinder piston 47. The cavity 30 communicates with the conduit 54 placed longitudinally and so eccentric to connect the upper and lower circular surfaces of the cylinder piston 47, via a connecting channel 31.

The control means 42 also provide that on the elements in movement 49, 48, 47, 50, 52, 53 are respectively provided elements sealing which may consist of rubber O-rings 32, 33, 34, 35, 36, 37, 38, 39.

The operation of the control device 12 shown in Figures 5 to 7 is the next:

The position of the control rack 11 is checked by through the control rod 50 whose position determines the position of the cylinder piston 47 thanks to the action of the two valves 52, 53.

Valves 52, 53 make it possible to control the volume of trapped oil respectively in the upper 40 and lower 41 chamber of the jack hydraulic.

• Obtention d'une nouvelle position de la crémaillère de commande 11:
  • Le calculateur non représenté qui définit en permanence la hauteur adéquate de la crémaillère de commande 11 tenant compte des conditions de fonctionnement du moteur agit sur la position de la tige de contrôle 50 par l'intermédiaire d'un dispositif d'asservissement pouvant par exemple être constitué d'un moteur électrique pas à pas de faible puissance (non représenté). La nouvelle position de la tige de contrôle 50 par rapport au piston de vérin 47 solidaire de la crémaillère de commande 11, a pour effet d'ouvrir la valve 52, 53 située du côté du sens du déplacement de ladite tige de contrôle 50, la valve étant alors soulevée par l'épaulement 51.
  • Le changement fréquent du sens de l'effort sur le piston de vérin 47, dû au mouvement alternatif des pièces mécaniques qui constituent une partie de l'ensemble mobile inférieur du moteur à cylindrée variable, implique une pression alternativement plus forte au dessus, puis au dessous du piston de vérin 47.
  • Lorsque la pression devient plus importante du côté de la valve 52, 53 maintenue ouverte par la tige de contrôle 50, le fluide hydraulique s'échappe par l'orifice alors ouvert et soulève la valve 52, 53 du côté opposé libre par rapport à la tige de contrôle et maintenue fermée jusqu'alors par un ressort 55, 56. Le fluide hydraulique se déplace alors vers le côté opposé tant que le piston de vérin n'a pas une position telle que la tige de contrôle ne permette plus le maintien en ouverture de ladite valve ouverte.
  • Si un cycle de changement de sens de l'effort n'a pu suffire à obtenir la position désirée, et si le piston de vérin 47 n'est pas arrivé a une position telle que la tige de contrôle 50 ne puisse plus maintenir ouverte la valve 52, 53 ouverte, un ou plusieurs cycle de changement de sens de l'effort supplémentaires peuvent être nécessaires. La valve 52, 53 restée libre par rapport à la tige de contrôle 50 assurant alors un rôle d'anti-retour interdisant au fluide hydraulique stocké de son côté de retourner du côté de la valve 52, 53 est maintenue ouverte par la tige de contrôle 50, et ce jusqu'à obtention de la position désirée du piston de vérin 47 par rapport au corps de vérin 45.
• Maintien permanent à une position définie de la crémaillère de commande 11:
  • Des petites fuites ou des suintements peuvent survenir au niveau des joints d'étanchéité 32 à 39, et cela en raison des pressions importantes qui règnent dans le corps du vérin 45. Pour conserver en position adéquate la crémaillère de commande 11 malgré ces pertes hydrauliques, il est nécessaire de corriger en permanence, même de façon infime, sa position par rapport à la tige de contrôle 50.
  • Ce résultat est obtenu par l'action conjuguée des deux valves 52, 53 qui permettent de contrôler le volume d'huile emprisonné respectivement dans la chambre supérieure 40 et inférieure 41 du vérin hydraulique, et du clapet anti-retour 43 logé dans le conduit 57 d'arrivée de fluide hydraulique dont l'orifice débouche dans la partie centrale du corps de vérin 45.
  • Si une fuite de fluide hydraulique existe dans la chambre supérieure 40 ou inférieure 41 du vérin dont les volumes respectifs sont définis par la position du piston de vérin 47 par rapport au corps de vérin 45, il s'ensuit, lorsque la pression est importante du côté de la chambre qui fuit, un déplacement du piston de vérin 47 dans le sens de ladite chambre qui fuit non autorisé par la position de la tige de contrôle 50. Ce déplacement non autorisé a pour conséquences de maintenir fermée la valve 52, 53 positionnée du côté de la chambre qui fuit, mais d'ouvrir la valve 52, 53 positionnée du côté opposé, ceci étant induit par l'épaulement 51 de la tige de contrôle 50 dont la position par rapport au piston de vérin 47 ne sera plus adéquate. La fermeture et l'ouverture des valves correspondantes a pour effet de remplir la chambre opposée à la chambre qui fuit de fluide hydraulique admis via le clapet anti-retour 43 logé dans le conduit 57. Le fluide hydraulique est acheminé vers la chambre 40, 41 opposée à la chambre qui fuit grâce à la cavité 30 aménagée sur la surface cylindrique du piston de vérin 47 qui est en regard d'une part avec l'orifice du conduit 57 débouchant dans la partie centrale du corps de vérin 45 et d'autre part avec le canal de liaison 31 qui relie ladite cavité 30 au conduit 54, aménagé dans la masse du piston de vérin 47.
  • Lorsque le sens de l'effort appliqué au piston de vérin 47 par la crémaillère de commande 11 s'inverse, le fluide hydraulique admis dans la chambre 40, 41 opposée à la chambre qui fuit est refoulé vers ladite chambre qui fuit jusqu'à ce que la valve 52, 53 maintenue ouverte par l'épaulement 51 de la tige de contrôle 50 repose sur son siège, assurant alors la remise en bonne position de la crémaillère de commande 11.

The control of the position of the control rack 11 operates as follows

• Obtaining a new position of the control rack 11:
  • The computer (not shown) which permanently defines the adequate height of the control rack 11 taking account of the operating conditions of the engine acts on the position of the control rod 50 by means of a servo device which can for example be consisting of a low power stepping electric motor (not shown). The new position of the control rod 50 relative to the cylinder piston 47 integral with the control rack 11, has the effect of opening the valve 52, 53 located on the side of the direction of movement of said control rod 50, the valve then being lifted by the shoulder 51.
  • The frequent change of the direction of the force on the cylinder piston 47, due to the reciprocating movement of the mechanical parts which constitute a part of the lower movable assembly of the variable displacement engine, implies an alternately higher pressure above, then at below the cylinder piston 47.
  • When the pressure becomes greater on the side of the valve 52, 53 kept open by the control rod 50, the hydraulic fluid escapes through the orifice then open and lifts the valve 52, 53 on the opposite side free relative to the control rod and kept closed until then by a spring 55, 56. The hydraulic fluid then moves to the opposite side as long as the cylinder piston does not have a position such that the control rod no longer allows the maintenance in opening of said open valve.
  • If a cycle of change of direction of effort was not sufficient to obtain the desired position, and if the cylinder piston 47 has not arrived at a position such that the control rod 50 can no longer keep open the valve 52, 53 open, one or more cycles of change of direction of the force may be necessary. The valve 52, 53 remained free relative to the control rod 50 then ensuring a non-return role preventing the hydraulic fluid stored on its side from returning to the side of the valve 52, 53 is kept open by the control rod 50, and this until the desired position of the cylinder piston 47 is obtained relative to the cylinder body 45.
• Permanent maintenance at a defined position of the control rack 11:
  • Small leaks or seepage can occur at the seals 32 to 39, and this due to the high pressures prevailing in the body of the jack 45. To keep the control rack 11 in an adequate position despite these hydraulic losses, it is necessary to permanently correct, even in minute detail, its position relative to the control rod 50.
  • This result is obtained by the combined action of the two valves 52, 53 which make it possible to control the volume of oil trapped respectively in the upper chamber 40 and lower 41 of the hydraulic cylinder, and the non-return valve 43 housed in the conduit 57 hydraulic fluid inlet, the orifice of which opens into the central part of the cylinder body 45.
  • If a hydraulic fluid leak exists in the upper 40 or lower chamber 41 of the jack, the respective volumes of which are defined by the position of the jack piston 47 with respect to the jack body 45, it follows, when the pressure is high side of the leaking chamber, a displacement of the cylinder piston 47 in the direction of said leaking chamber not authorized by the position of the control rod 50. This unauthorized displacement has the consequences of keeping the valve 52, 53 positioned closed on the side of the leaking chamber, but to open the valve 52, 53 positioned on the opposite side, this being induced by the shoulder 51 of the control rod 50 whose position relative to the cylinder piston 47 will no longer be adequate . Closing and opening the corresponding valves has the effect of filling the chamber opposite the leaking chamber with hydraulic fluid admitted via the non-return valve 43 housed in the conduit 57. The hydraulic fluid is conveyed to the chamber 40, 41 opposite to the leaking chamber thanks to the cavity 30 arranged on the cylindrical surface of the cylinder piston 47 which is opposite on the one hand with the orifice of the conduit 57 opening into the central part of the cylinder body 45 and on the other part with the connecting channel 31 which connects said cavity 30 to the duct 54, arranged in the mass of the cylinder piston 47.
  • When the direction of the force applied to the cylinder piston 47 by the control rack 11 reverses, the hydraulic fluid admitted into the chamber 40, 41 opposite the leaking chamber is discharged towards said leaking chamber until that the valve 52, 53 kept open by the shoulder 51 of the control rod 50 rests on its seat, then ensuring the return to the correct position of the control rack 11.

According to the invention, the position of the control rod 50 therefore conditions in permanently the position of the control rack 11 relative to the block engine 5, and therefore the volume of the engine's explosion chamber 9. It is so possible to control the engine chamber volume with a device very low power servo control (not shown).

It is noted that, in addition to the advantages inherent in the device itself which, according to the invention makes it possible to vary during their operation the displacement and / or the effective displacement ratio of a piston engine and increase its overall efficiency when used at variable load and speed, the invention presents that of not posing any particular feasibility problem. The invention uses known and proven processes and techniques.

The present invention is not limited to the embodiment which has just been described; on the contrary, it is subject to modifications and variations which will appear to those skilled in the art.

Claims (19)

1. Device for varying the effective cylinder capacity and/or the effective volumetric ratio of a piston engine, while it is running, characterized in that it comprises:

   a first device for controlling the volumetric ratio of the engine which acts by altering the origin of the stroke of the piston (1) with respect to the cylinder (2) without altering the length of the said stroke;

   and a second device controlling the effective cylinder capacity of the engine by discharging into the inlet duct (19) excess gases let into the cylinder (2) of the engine and by adjusting the length of the piston upstroke used to compress the gases.
2. Device according to Claim 1, characterized in that the first device for controlling the volumetric ratio of the engine consists of a system with gears which comprises:

   a rack (10) secured to the lower part of the piston (1) and which is held in a guide system allowing the said rack a longitudinal translational movement;

   an operating rack (11) guided in longitudinal translation in the engine block (5);

   a device (12) for controlling the position of the operating rack (11);

   and a gear (14) mounted freely on a connecting rod (13) which is also free on a crankshaft (7) so that the gear (14) lies between the two racks (10, 11) to form the element that transmits movement between the piston (1) and the connecting rod (13).
3. Device according to Claim 1, characterized in that the second device for controlling the effective cylinder capacity of the engine consists of an additional inlet valve (15) and of a device (16, 17) which controls its opening/closure and allows the angular offset of the point of closure and of opening of the said valve with respect to the crankshaft (7) to be altered.
4. Device according to Claim 1, characterized in that the second device for controlling the effective cylinder capacity of the engine, without an additional inlet valve (15), consists of a device (21) which controls the opening and the closure of an inlet valve (22) known per se and which makes it possible to alter the angular offset of the point of closure and of opening of the said valve with respect to the crankshaft (7).
5. Device according to Claim 3, characterized in that the device which controls the opening and the closure of the additional inlet valve (15) is a camshaft (16) slaved to a device (17) which controls its angular offset with respect to the crankshaft (7) of the engine.
6. Device according to Claim 4, characterized in that the device which controls the opening and the closure of the additional valve (22) known per se consists of an additional camshaft (21) slaved to a device which controls its angular offset with respect to the crankshaft (7) of the engine, the said additional camshaft (21) actuating the said valve via a mechanical link (23) in addition to the movement imparted to the said valve by its camshaft (24).
7. Device according to Claim 5, characterized in that the device (17) which controls the angular offset of the camshaft (16) which opens the additional inlet valve (15) consists of an intermediate pulley (18), the position of which defines the length of timing belt or timing chain between the pulley (28) of the camshaft (24) for the inlet (3) and exhaust (4) valves of the engine and the pulley (29) of the camshaft (16) which opens the additional inlet valve (15).
8. Device according to Claim 2, characterized in that the device (12) which controls the position of the operating rack (11) consists of a hydraulic actuator (25) which acts on the said rack via a mechanical link (20).
9. Device according to Claim 7, characterized in that the device (17) which controls the position of the intermediate pulley (18) consists of a hydraulic actuator (26).
10. Device according to Claim 2, characterized in that the gear (14) has a truncated profile so as to keep only those teeth which are useful in transmitting movement between the piston (1) and the connecting rod (13).
11. Device according to Claim 2, characterized in that running surfaces are formed respectively on the gear (14) and on the rack (10, 11) so that the said gear is constantly centred between the said racks, while the point of contact between the said running surfaces is constantly positioned on the pitch circle of the gear (14).
12. Device according to Claim 2, characterized in that the cylinder part of the piston (1) is tall enough to house rings, but has no skirt for its longitudinal guidance.
13. Device according to Claim 2, characterized in that the control device (12) comprises:

    a hydraulic actuator comprising means (49) for extending its rod (48), making it possible to maintain a displaced fluid volume as a function of the stroke of the actuator piston which is identical for each of the chambers, upper (40) and lower (41), of the said actuator;

    control means (42) that make it possible to move the rod (48) of the actuator into a determined position or to maintain it in a determined position with respect to the body of the actuator (45).
14. Device according to Claim 13, characterized in that the control device (12) comprises:

    an actuator body (45) mounted fixedly with respect to the engine block (5) parallel to the operating rack (11), an actuator cover (46) mounted fixedly with respect to the actuator body (45), an actuator piston (47), an actuator rod (48) and an actuator rod extension (49) which are assembled with the operating rack (11), which constitute the upper guidance system for said operating rack (11) and which can move longitudinally with respect to the actuator body (45);

    control means (42) which consist of a control stem (50) comprising a shoulder (51) and which can move longitudinally, the said control stem (50) being positioned parallel to the actuator rod (48) and passing right through the actuator cover (46), the actuator body (45) and the actuator piston (47) by virtue of orifices made in the said actuator cover (46), actuator body (45) and actuator piston (47), of valves (52, 53) housed in a passage (54) placed longitudinally and eccentrically formed in the mass of the actuator piston (47), the said valves (52, 53) allowing hydraulic fluid to flow or preventing hydraulic fluid from flowing between the upper (40) and lower (41) chambers of the actuator as defined by the position of the actuator piston (47) relative to the actuator body (45), the said valves (52, 53) consisting of rings which can slide around the control stem (50), and their inside diameter being smaller than the diameter of the shoulder (51) of the control stem (50) so that it is possible to keep them open by virtue of the said shoulder (51) of the said control stem (50) when the said valves are not kept open by the said shoulder (51) of the said control stem (50), they are held on their seat by springs (55, 56), and of a nonreturn valve (43) housed in a hydraulic-fluid inlet passage (57), one of the orifices of which opens into the central part of the actuator body (45), the said nonreturn valve allowing hydraulic fluid to enter the actuator body (45) but preventing it from leaving.
15. Device according to Claim 14, characterized in that the actuator piston (47) comprises a cavity (30) on its cylindrical surface facing the orifice of the hydraulic fluid inlet passage (57) opening into the central part of the actuator body (45), the said cavity (30) having a height at least equivalent to the maximum stroke of the said actuator piston (47) and being connected to the passage (54) placed longitudinally and eccentrically formed in the mass of the said actuator piston (47) connecting the lower and upper circular surfaces of the said actuator piston (47), by a connecting channel (31).
16. Device according to Claim 14, characterized in that the nonreturn valve (43) consists of a ball (58) held on a bearing surface by a spring (59) and plugging an orifice (44).
17. Device according to Claim 14, characterized in that the hydraulic fluid inlet passage (57), one of the orifices of which opens into the central part of the actuator body (45), is connected to the pressurized hydraulic circuit that lubricates the variable-displacement engine.
18. Device according to Claim 14, characterized in that it comprises sealing elements consisting of rubber O-rings (32, 33, 34, 35, 36, 37, 38, 39).
19. Device according to Claim 14, characterized in that the shoulder (51) of the control stem (50) centres the said control stem in the eccentric longitudinal passage (54) formed in the mass of the actuator piston (47), the said shoulder has furrows or grooves allowing fluid to flow along the said passage.

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