EP0789138A1 - Two stroke engine having a control means for the valve movement - Google Patents

Two stroke engine having a control means for the valve movement Download PDF

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Publication number
EP0789138A1
EP0789138A1 EP97400225A EP97400225A EP0789138A1 EP 0789138 A1 EP0789138 A1 EP 0789138A1 EP 97400225 A EP97400225 A EP 97400225A EP 97400225 A EP97400225 A EP 97400225A EP 0789138 A1 EP0789138 A1 EP 0789138A1
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EP
European Patent Office
Prior art keywords
cylinder
chamber
pressure
valve
engine
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP97400225A
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German (de)
French (fr)
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EP0789138B1 (en
Inventor
Jean-Charles Dabadie
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IFP Energies Nouvelles IFPEN
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IFP Energies Nouvelles IFPEN
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B25/00—Engines characterised by using fresh charge for scavenging cylinders
    • F02B25/26—Multi-cylinder engines other than those provided for in, or of interest apart from, groups F02B25/02 - F02B25/24
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
    • F01L9/10—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic
    • F01L9/16—Pneumatic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B33/00—Engines characterised by provision of pumps for charging or scavenging
    • F02B33/02—Engines with reciprocating-piston pumps; Engines with crankcase pumps
    • F02B33/04—Engines with reciprocating-piston pumps; Engines with crankcase pumps with simple crankcase pumps, i.e. with the rear face of a non-stepped working piston acting as sole pumping member in co-operation with the crankcase
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
    • F02M69/08—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel characterised by the fuel being carried by compressed air into main stream of combustion-air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M69/00—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel
    • F02M69/10—Low-pressure fuel-injection apparatus ; Apparatus with both continuous and intermittent injection; Apparatus injecting different types of fuel peculiar to scavenged two-stroke engines, e.g. injecting into crankcase-pump chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
    • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
    • F02B2075/025—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle two

Definitions

  • the present invention relates to the field of two-stroke engines with controlled pneumatic injection.
  • the present invention relates to the command and control of pneumatic fuel injection, in two-stroke single-cylinder or multi-cylinder engines.
  • a conventional way of controlling pneumatic injection is to connect the valves to a camshaft.
  • This purely mechanical solution is not very flexible to use since each cam requires a precise movement of a valve and moreover, the camshaft supporting several cams, it is a given general movement which is imposed from the outset of all the cams.
  • This technology therefore generates a general command common to all the valves of the camshaft. Adjustment is difficult and a problem with one of the cams and / or the valves can have repercussions on all the other parts involved.
  • More flexible control systems are known, based in particular on pressure variations between different chambers cooperating with the movement of the valve.
  • French patents FR 2 656 653 and FR 2 656 656 describe multi-cylinder two-stroke engines in which the pneumatic fuel injection is carried out thanks to pressure differences between different chambers.
  • This prior art specifically relates to engines having several cylinders since the pressure differences are created thanks to the angular offset existing between the cycles of the different cylinders.
  • the objective of the present invention is to simplify this technology and above all to be able to apply it to single-cylinder engines, which the above-mentioned prior art in no way allows.
  • the object of the invention is to use the various pressure variations inherent in the operation of a cylinder to automatically actuate a pneumatic fuel injection device in this cylinder.
  • this prior solution applies to single-cylinder engines or engines having several cylinders operating completely independently of each other.
  • the connections and the pressure sources used are different.
  • One of the problems underlying the present invention is therefore linked to the control of pneumatic injection. According to the present invention, it is a question of shifting the pneumatic injection and more precisely of delaying it with each engine cycle, with respect to an engine according to the prior art.
  • motors such as for example those described in the patent application EN. 94/10782 cited above or in French application FR 2 656 653, are fitted with a flange placed in the pump housing for controlling the air flow rate necessary for pneumatic injection.
  • flanges are parts added to the engine, which therefore make it more expensive, with the need to have precise adjustments.
  • the present invention offers a simpler solution by not requiring a flange for controlling the air flow.
  • the engine according to the invention further comprises a first connecting means between the second chamber and the cylinder, intended to delay the opening of the valve by controlling the pressure in said chamber.
  • the engine according to the invention further comprises a second connection means between the first chamber and said cylinder, said second connection having a length greater than said first connection.
  • said second link has a branch branch in relation to the first link.
  • said second connection is made between the first chamber of the movement control means of a valve belonging to a first cylinder and a second cylinder.
  • the motor further comprises a second connecting means which opens at one end into said pump housing and through the other end into said first chamber.
  • the motor according to the invention may include a third connection means between the pump housing and the first connection means.
  • a third connection means can be provided between the first and the second connection means.
  • FIG. 1 shows, by a simplified longitudinal section, a two-stroke engine equipped with a means 82 for controlling the movement of a valve. More precisely, the means 82 is placed on the cylinder head of the engine. This means is described. in its structure, for example in the patent application EN. 94/10782.
  • the means 82 essentially comprises, in addition to its envelope (not referenced) fixed on the cylinder head, a flexible membrane 89 which separates two chambers 95a and 95b subjected to different pressures as it will be explained later.
  • the valve 86 the movement of which is controlled by the means 82, has a head resting on its seat in the closed position.
  • the valve stem is connected to the flexible membrane 89 which is itself fixed along its periphery to the interior wall of the envelope.
  • a third conduit 87 (or capacity) opens towards the base of the valve 86 and serves to convey a fuel mixture which is injected into the combustion chamber when the valve 86 opens.
  • a return spring is interposed between the flexible membrane 89 and the upper surface of the cylinder head in order to help the membrane to act against the pressure in the upper chamber 95a and in the capacity 87.
  • a piston 112 moves in the cylinder 111 which comprises a combustion chamber 113.
  • Said cylinder 111 communicates at its lower part with a pump casing 115.
  • the pump housing 115 comprises, in a conventional manner, an air intake nozzle 119 on which a valve 120 is placed.
  • the fresh air introduced into the casing 115 and compressed by the piston 112 is injected into the cylinder 111, by means of transfer conduits such as 121 opening into the cylinder through openings 122.
  • the burnt gases are evacuated from the cylinder 111 by a pipe 123.
  • the conduit 87 opens at its end 127 opposite to that which opens into the control device 82, directly into the pump housing 115.
  • the opening 127 is preferably controlled by a non-return valve or any other means capable of closing this opening as soon as the pressure in the pump casing 115 becomes lower than the pressure in the conduit 87 which is therefore used as storage capacity pressure.
  • the pipe 92 which communicates by one of its ends with the chamber 95b of the device 82, opens into the cylinder 113 by its other end.
  • the pipe 92 opens into the cylinder 113 at a level close to that of the exhaust pipe 123.
  • the opening and closing of the pipe 92 are controlled by the movement of the piston, approximately at the same time as the opening and closing of the exhaust 123.
  • the level depends on the pressure that one wants to obtain in the chambers.
  • the upper chamber 95a is, according to this embodiment, open to admission, therefore at a rather constant pressure. It can also be closed. Its pressure then depends on the position of the membrane 89, that is to say the pressure in the second chamber 95b.
  • the pressure in the lower chamber 95b follows the variations indicated in the figure by the dotted curve B. In this figure also appear the pressure in the cylinder 113 (curve A in solid lines) and the pressure in the capacity 87 (curve C) for the fuel mixture; this latter pressure being close to the maximum pressure prevailing in the pump housing 115.
  • a pressure wave therefore leaves the cylinder and joins the lower chamber 95b, quickly and with little loss of pressure; the length of the pipe 92 is quite short.
  • the valve would begin to open around 120, 130 ° crankshaft. According to the present invention, the valve opens only around 180 ° crankshaft approximately. This delay in opening depends on the level of the stitching of the pipe 92 in the cylinder. It also depends on the length of said pipe: here very short (about 15 cm), in any case shorter than in the prior art.
  • the instant of opening of the valve 86 depends on the dimension (surface) of the membrane 89 and on the force of the associated return spring.
  • the injection ends when the cylinder pressure becomes greater than the pressure in capacity 87.
  • FIG. 3 illustrates an embodiment of the invention which differs from the first by the addition of a pipe 921 which at one end opens into the cylinder 111, for example at the same level as the pipe 92.
  • the length of the pipe 921 is greater than that of the pipe 92 so that the pressure wave, coming from the cylinder 111, arrives in the upper chamber 95a after the arrival in 95b of that of the pipe 92.
  • FIG. 5 illustrates this phenomenon.
  • curve B relates to the variation in pressure in the lower chamber
  • curve D relates to the variation in pressure in the upper chamber.
  • FIG. 5 shows that the arrival of the pressure wave in the lower chamber 95b, which corresponds to the strong rise in pressure, occurs around 120 ° V.
  • the shape of the pressure wave in the upper chamber is different from that in the lower chamber; this is due to the fact that the valve begins to open.
  • the volume of the upper chamber increases significantly (in proportion) and the maximum pressure reached is significantly lower than that of the chamber.
  • the additional line 921 has little influence on the duration of the injection but on the other hand it influences the amplitude of the movement of the valve, since it "adds" a pressure to that of the upper chamber. This additional force is advantageous because it allows the use of a spring of greater stiffness, which facilitates the closing of the valve.
  • FIG. 4 illustrates an embodiment very close to that of FIG. 3, the difference being that the additional line 921 leads to the line 92 instead of the connection to the combustion chamber.
  • the effect is the same as that of FIG. 3.
  • FIG. 5 therefore illustrates the operation of the engine according to FIG. 4. It will not be further discussed.
  • Figures 6 and 7 relate to an embodiment of the invention according to which at least two cylinders are used.
  • the upper chamber 95a of one of the cylinders is connected via a pipe 926 to another cylinder 111 '.
  • This other cylinder is also equipped with means 82 'for assisting the valve, the lower chamber 95b' of which is connected to said cylinder.
  • Figure 7 illustrates the effect of this shift.
  • the pressure wave arrives with a delay of about 90 ° crankshaft with respect to the lower chamber (curved B). This delay is due to the angular offset between the two cylinders.
  • the delay is controllable by the length of the conduit 926 as well as by the position of the tap in the other cylinder 111 '.
  • FIG. 7 shows very well the effect of the length of the conduit on the duration of the signal.
  • the pressure wave of curve E has a shorter duration than the pressure wave of curve D of figure 5.
  • the pressure peak of curve E "lasts" about 60 ° V while in FIG. 5, the pressure peak of curve D extends over 100 ° V.
  • the effect of the speed will be less significant: the travel time of the pressure signal expressed in seconds varies little with the speed, but the variation is significant when it is expressed in crankshaft degree.
  • FIG. 8 shows a two-stroke engine comprising the same elements as that of FIG. 1 and also having an additional pipe 922 opening on the one hand into the upper chamber 95a and on the other hand into the pump housing 115.
  • the pipe additional 922 has a length greater than that of the pipe 92 and the pressure diagram is obtained according to FIG. 9.
  • the latter resembles that of FIG. 2, the curves A, B and C being the same.
  • the curve F which corresponds to the pressure in the upper chamber 95a connected to the pump housing 115.
  • the pressure wave is different from that of the lower chamber.
  • the pressure peak occurs in the lower chamber around 130 ° crankshaft and in the upper chamber around 170 ° crankshaft.
  • the maximum value of the pressure in the upper chamber is around 1.4 bars. It is much lower than the maximum value in the lower chamber (more than 2 bars).
  • the valve 86 begins to open when the pressure in the upper chamber is higher than that in the lower chamber, ie around 180 ° crankshaft. Without this assistance mode, the opening of the valve begins around 140 ° crankshaft.
  • the end of the injection is around 240 ° crankshaft when the pressure in the cylinder becomes significantly higher than the pressure in capacity 87.
  • FIG. 10 illustrates an embodiment close to that of FIG. 8; however a line 923 is added; it connects the pump housing 115 to the pipe 92.
  • FIG. 12 Another embodiment of the invention is illustrated in FIG. 12 with the pressures according to FIG. 13. Basically, this embodiment reproduces that of FIG. 8, it comprises the same pipes.
  • connection 924 between the pipe 92 and the pipe 922.
  • a sharp increase is indeed seen on the curve H pressure around 170 ° crankshaft. This is due to the arrival of the pressure wave coming from the cylinder via the link 924.
  • the opening of the valve begins with the arrival of this wave, ie around 170 ° crankshaft. The time of this opening is determined by the lengths in the different pipes 92, 922, 924.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical & Material Sciences (AREA)
  • Valve Device For Special Equipments (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Reciprocating Pumps (AREA)
  • Fuel-Injection Apparatus (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)
  • Fluid-Driven Valves (AREA)
  • Electrically Driven Valve-Operating Means (AREA)
  • Control Of Transmission Device (AREA)
  • Supercharger (AREA)

Abstract

The engine consists of at least one cylinder (111) containing a reciprocating piston (112). One end of the piston is connected to a crankcase pump (115) containing the engine's crankshaft (114). A pressure pipe (87) has one end connected to the crankcase-pump and the other to the combustion chamber (113), controlled by a valve (86). The valve is actuated by a membrane unit (82) in which a supple membrane (89) separates first and second chambers (95a,95b) and is connected to the valve stem. The engine has a connecting pipe (92) between the second membrane chamber (95b) and the cylinder (111). This pipe is designed to delay the opening of the valve by controlling the pressure in the chamber. It has a second connecting pipe between the first chamber (95a) and the cylinder which is longer than the first connecting pipe and linked to it by a branch.

Description

La présente invention concerne le domaine des moteurs à deux temps à injection pneumatique commandée.The present invention relates to the field of two-stroke engines with controlled pneumatic injection.

Plus précisément la présente invention a trait à la commande et au contrôle de l'injection pneumatique de carburant, dans des moteurs deux temps monocylindre ou multicylindres.More specifically, the present invention relates to the command and control of pneumatic fuel injection, in two-stroke single-cylinder or multi-cylinder engines.

Une façon conventionnelle de commander l'injection pneumatique consiste à relier les soupapes à un arbre à came. Cette solution purement mécanique s'avère d'utilisation peu souple puisque chaque came impose un mouvement précis d'une soupape et de plus, l'arbre à came supportant plusieurs cames, c'est un mouvement général donné qui est imposé dès l'origine de l'ensemble des cames. Cette technologie génère donc une commande générale commune à toutes les soupapes de l'arbre à came. Le réglage est difficile et un problème sur l'une des cames et/ou des soupapes peut avoir des répercutions sur l'ensemble des autres pièces mises en jeu.A conventional way of controlling pneumatic injection is to connect the valves to a camshaft. This purely mechanical solution is not very flexible to use since each cam requires a precise movement of a valve and moreover, the camshaft supporting several cams, it is a given general movement which is imposed from the outset of all the cams. This technology therefore generates a general command common to all the valves of the camshaft. Adjustment is difficult and a problem with one of the cams and / or the valves can have repercussions on all the other parts involved.

Des systèmes de commande plus souples sont connus, basés notamment sur des variations de pressions entre différentes chambres coopérant avec le mouvement de la soupape.More flexible control systems are known, based in particular on pressure variations between different chambers cooperating with the movement of the valve.

Ainsi, les brevets français FR 2 656 653 et FR 2 656 656 décrivent des moteurs deux temps multicylindre dans lesquels l'injection pneumatique de carburant est réalisée grâce à des différences de pression entre différentes chambres. Cet art antérieur concerne spécifiquement des moteurs ayant plusieurs cylindres puisque les différences de pression sont créées grâce au décalage angulaire existant entre les cycles des différents cylindres.Thus, French patents FR 2 656 653 and FR 2 656 656 describe multi-cylinder two-stroke engines in which the pneumatic fuel injection is carried out thanks to pressure differences between different chambers. This prior art specifically relates to engines having several cylinders since the pressure differences are created thanks to the angular offset existing between the cycles of the different cylinders.

L'objectif de la présente invention est de simplifier cette technologie et surtout de pouvoir l'appliquer à des moteurs monocylindre, ce que ne permet nullement l'art antérieur précité.The objective of the present invention is to simplify this technology and above all to be able to apply it to single-cylinder engines, which the above-mentioned prior art in no way allows.

Enoncé d'une façon générale, l'objet de l'invention est d'utiliser les différentes variations de pression inhérentes au fonctionnement d'un cylindre pour actionner de façon automatique un dispositif d'injection pneumatique de carburant dans ce cylindre. En d'autres termes il s'agit, selon l'invention, de commander l'ouverture et la fermeture d'une soupape de façon automatique à chaque tour moteur, à des instants précis et déterminés, sans avoir recours à un moyen de commande mécanique tel qu'un arbre à cames. La demande de brevet français EN. 94/10782. opposable à la présente demande au titre de la nouveauté uniquement, divulgue un moteur ayant notamment cette caractéristique. Cependant de façon différente de la présente invention, cette solution antérieure s'applique à des moteurs monocylindres ou ayant plusieurs cylindres fonctionnant totalement indépendamment les uns des autres. Par ailleurs, comme il va être explicité plus loin, les liaisons et les sources de pression utilisées sont différentes.In general terms, the object of the invention is to use the various pressure variations inherent in the operation of a cylinder to automatically actuate a pneumatic fuel injection device in this cylinder. In other words, it is a question, according to the invention, of controlling the opening and closing of a valve automatically at each engine revolution, at precise and determined moments, without using a mechanical control means such as a camshaft. The French patent application EN. 94/10782. enforceable against this application for the sake of novelty only, discloses an engine having in particular this characteristic. However, differently from the present invention, this prior solution applies to single-cylinder engines or engines having several cylinders operating completely independently of each other. Furthermore, as will be explained below, the connections and the pressure sources used are different.

L'un des problèmes à la base de la présente invention est donc lié au contrôle de l'injection pneumatique. Il s'agit selon la présente invention de décaler l'injection pneumatique et plus précisément de la retarder à chaque cycle-moteur, vis-à-vis d'un moteur selon l'art antérieur.One of the problems underlying the present invention is therefore linked to the control of pneumatic injection. According to the present invention, it is a question of shifting the pneumatic injection and more precisely of delaying it with each engine cycle, with respect to an engine according to the prior art.

Par ailleurs des moteurs tels que par exemple ceux décrits dans la demande de brevet EN. 94/10782 précitée ou encore dans la demande française FR 2 656 653, sont équipés d'un flasque placé dans le carter-pompe pour le contrôle du débit d'air nécessaire à l'injection pneumatique.Furthermore, motors such as for example those described in the patent application EN. 94/10782 cited above or in French application FR 2 656 653, are fitted with a flange placed in the pump housing for controlling the air flow rate necessary for pneumatic injection.

Ces flasques sont des pièces ajoutées au moteur, qui le rendent donc plus coûteux, avec la nécessité d'avoir des réglages précis. La présente invention offre une solution plus simple en ne nécessitant pas de flasque pour le contrôle du débit d'air.These flanges are parts added to the engine, which therefore make it more expensive, with the need to have precise adjustments. The present invention offers a simpler solution by not requiring a flange for controlling the air flow.

En outre les pressions étant prises, selon l'art antérieur précité, dans le carter-pompe, elles ne sont pas toujours suffisantes notamment aux régimes et/ou charges élevés.In addition, the pressures being taken, according to the aforementioned prior art, in the pump housing, they are not always sufficient in particular at high speeds and / or loads.

Vis-à-vis de la demande de brevet EN 94/10782 il existe un problème lié au temps de transit des gaz dans les canalisations reliant le carter-pompe au moyen d'injection, ce problème est d'autant plus aigüe que le régime moteur est plus élevé.With regard to patent application EN 94/10782 there is a problem related to the transit time of the gases in the pipes connecting the pump housing to the injection means, this problem is all the more acute as the speed engine is higher.

Les problèmes évoqués ci-dessus, ainsi que d'autres, peuvent être résolus selon la présente invention.The problems discussed above, as well as others, can be solved according to the present invention.

Ainsi la présente invention concerne un moteur à deux temps comportant au moins :

  • un cylindre dans lequel se déplace un piston et dont l'une des extrémités communique avec un carter-pompe traversé par le vilebrequin du moteur,
  • une capacité sous pression débouchant à une extrémité dans la chambre de combustion du cylindre,
  • une soupape assurant l'obturation intermittente entre la chambre et la capacité.
  • un moyen destiné à carburer le gaz passant dans ladite capacité,
  • un moyen de contrôle du mouvement de ladite soupape comprenant une membrane souple séparant une première et une deuxième chambre, ladite membrane étant reliée à la tige de la soupape.
Thus the present invention relates to a two-stroke engine comprising at least:
  • a cylinder in which a piston moves and one end of which communicates with a pump housing through which the engine crankshaft passes,
  • a pressurized capacity opening at one end into the combustion chamber of the cylinder,
  • a valve ensuring the intermittent obturation between the chamber and the capacity.
  • means for carburizing the gas passing through said capacity,
  • means for controlling the movement of said valve comprising a flexible membrane separating a first and a second chamber, said membrane being connected to the stem of the valve.

Le moteur selon l'invention comprend en outre un premier moyen de liaison entre la deuxième chambre et le cylindre, destiné à retarder l'ouverture de la soupape par un contrôle de la pression dans ladite chambre.The engine according to the invention further comprises a first connecting means between the second chamber and the cylinder, intended to delay the opening of the valve by controlling the pressure in said chamber.

Préférentiellement le moteur selon l'invention comprend en outre un deuxième moyen de liaison entre la première chambre et ledit cylindre, ladite deuxième liaison ayant une longueur supérieure à ladite première liaison.Preferably, the engine according to the invention further comprises a second connection means between the first chamber and said cylinder, said second connection having a length greater than said first connection.

Avantageusement, ladite deuxième liaison présente une branche en dérivation vis-à-vis de la première liaison.Advantageously, said second link has a branch branch in relation to the first link.

Au cas où le moteur selon l'invention comporte plusieurs cylindres, ladite deuxième liaison est réalisée entre la première chambre du moyen de contrôle du mouvement d'une soupape appartenant à un premier cylindre et un deuxième cylindre.If the engine according to the invention has several cylinders, said second connection is made between the first chamber of the movement control means of a valve belonging to a first cylinder and a second cylinder.

Selon une caractéristique intéressante de l'invention, le moteur comprend en outre un deuxième moyen de liaison qui débouche par une extrémité dans ledit carter-pompe et par l'autre extrémité dans ladite première chambre..According to an advantageous characteristic of the invention, the motor further comprises a second connecting means which opens at one end into said pump housing and through the other end into said first chamber.

En outre, le moteur selon l'invention peut comprendre un troisième moyen de liaison entre le carter-pompe et le premier moyen de liaison.In addition, the motor according to the invention may include a third connection means between the pump housing and the first connection means.

Sans sortir du cadre de la présente invention, un troisième moyen de liaison peut être prévu entre le premier et le deuxième moyen de liaison.Without departing from the scope of the present invention, a third connection means can be provided between the first and the second connection means.

L'invension sera mieux comprise à la lecture de la description qui va suivre, faite à titre illustratif et nullement limitatif en référence aux dessins annexés sur lesquels :

  • La figure 1 est une coupe longitudinale simplifiée d'un premier mode de réalisation de l'invention;
  • La figure 2 est un diagramme des pressions obtenues dans un moteur selon la figure 1;
  • La figure 3 est une coupe longitudinale simplifiée d'un deuxième mode de réalisation de l'invention;
  • La figure 4 est une coupe longitudinale simplifiée d'un troisième mode de réalisation de l'invention;
  • La figure 5 est un diagramme des pression obtenues dans un moteur selon les figures 3 ou 4;
  • La figure 6 est une vue simplifiée de deux cylindres d'un moteur selon un autre mode de réalisation de l'invention;
  • La figure 7 est un diagramme des pressions dans un moteur conforme à la figure 6;
  • La figure 8 concerne un moteur selon un mode particulier de réalisation de l'invention;
  • La figure 9 est un diagramme des pressions obtenues dans un moteur selon la figure 8;
  • La figure 10 illustre par une coupe longitudinale simple un mode spécifique de réalisation de l'invention;
  • La figure 11 est un diagramme des pressions pour un moteur selon la figure 10;
  • La figure 12 illustre par une coupe longitudinale un moteur selon l'invention; et
  • La figure 13 est un diagramme des pressions pour un moteur selon la figure 12.
The invention will be better understood on reading the description which follows, given by way of illustration and in no way limiting with reference to the appended drawings in which:
  • Figure 1 is a simplified longitudinal section of a first embodiment of the invention;
  • FIG. 2 is a diagram of the pressures obtained in an engine according to FIG. 1;
  • Figure 3 is a simplified longitudinal section of a second embodiment of the invention;
  • Figure 4 is a simplified longitudinal section of a third embodiment of the invention;
  • Figure 5 is a diagram of the pressures obtained in an engine according to Figures 3 or 4;
  • Figure 6 is a simplified view of two cylinders of an engine according to another embodiment of the invention;
  • Figure 7 is a diagram of the pressures in an engine according to Figure 6;
  • FIG. 8 relates to an engine according to a particular embodiment of the invention;
  • FIG. 9 is a diagram of the pressures obtained in an engine according to FIG. 8;
  • FIG. 10 illustrates by a simple longitudinal section a specific embodiment of the invention;
  • Figure 11 is a pressure diagram for an engine according to Figure 10;
  • FIG. 12 illustrates by a longitudinal section an engine according to the invention; and
  • FIG. 13 is a diagram of the pressures for an engine according to FIG. 12.

La figure 1 montre, par une coupe longitudinale simplifiée un moteur deux temps équipé d'un moyen 82 de contrôle du mouvement d'une soupape. Plus précisément le moyen 82 est placé sur la culasse du moteur. Ce moyen est décrit. dans sa structure, par exemple dans la demande de brevet EN. 94/10782.FIG. 1 shows, by a simplified longitudinal section, a two-stroke engine equipped with a means 82 for controlling the movement of a valve. More precisely, the means 82 is placed on the cylinder head of the engine. This means is described. in its structure, for example in the patent application EN. 94/10782.

Pour la bonne compréhension de l'invention, il est ici rappelé que le moyen 82 comprend essentiellement, outre son enveloppe (non référencée) fixée sur la culasse, une membrane souple 89 qui sépare deux chambres 95a et 95b soumises à des pressions différentes comme il sera expliqué plus loin. La soupape 86, dont le mouvement est commandé par le moyen 82, comporte une tête en appui sur son siège en position fermée. La tige de la soupape est reliée à la membrane souple 89 elle-même fixée selon sa périphérie sur la paroi intérieure de l'enveloppe.For a good understanding of the invention, it is recalled here that the means 82 essentially comprises, in addition to its envelope (not referenced) fixed on the cylinder head, a flexible membrane 89 which separates two chambers 95a and 95b subjected to different pressures as it will be explained later. The valve 86, the movement of which is controlled by the means 82, has a head resting on its seat in the closed position. The valve stem is connected to the flexible membrane 89 which is itself fixed along its periphery to the interior wall of the envelope.

Dans l'une des chambres, 95b encore appelée deuxième chambre ou chambre basse dans la suite de ce texte, débouche un premier moyen de liaison.In one of the bedrooms, 95b, also called the second bedroom or lower bedroom in the rest of this text, opens a first connecting means.

Dans l'autre chambre 95a, encore appelée chambre haute ou première chambre dans la suite de ce texte, débouche un deuxième moyen de liaison.In the other room 95a, also called upper room or first room in the rest of this text, opens a second connecting means.

Un troisième conduit 87 (ou capacité) débouche vers le pied de la soupape 86 et sert à véhiculer un mélange carburé qui est injecté dans la chambre de combustion quand la soupape 86 s'ouvre.A third conduit 87 (or capacity) opens towards the base of the valve 86 and serves to convey a fuel mixture which is injected into the combustion chamber when the valve 86 opens.

Un ressort de rappel est intercalé entre la membrane souple 89 et la surface supérieure de la culasse afin d'aider la membrane à agir contre la pression dans la chambre haute 95a et dans la capacité 87.A return spring is interposed between the flexible membrane 89 and the upper surface of the cylinder head in order to help the membrane to act against the pressure in the upper chamber 95a and in the capacity 87.

De façon classique, un piston 112 se déplace dans le cylindre 111 qui comporte une chambre de combustion 113. Ledit cylindre 111 communique à sa partie inférieure avec un carter-pompe 115.Conventionally, a piston 112 moves in the cylinder 111 which comprises a combustion chamber 113. Said cylinder 111 communicates at its lower part with a pump casing 115.

Le carter-pompe 115 comporte, de manière classique, un ajutage d'admission d'air 119 sur lequel est placé un clapet 120.The pump housing 115 comprises, in a conventional manner, an air intake nozzle 119 on which a valve 120 is placed.

L'air frais introduit dans le carter 115 et comprimé par le piston 112 est injecté dans le cylindre 111, par l'intermédiaire de conduits de transfert tels que 121 débouchant dans le cylindre par des ouvertures 122. Les gaz brûlés sont évacués du cylindre 111 par une conduite 123.The fresh air introduced into the casing 115 and compressed by the piston 112 is injected into the cylinder 111, by means of transfer conduits such as 121 opening into the cylinder through openings 122. The burnt gases are evacuated from the cylinder 111 by a pipe 123.

Le conduit 87 débouche par son extrémité 127 opposée à celle débouchant dans le dispositif 82 de commande, directement dans le carter-pompe 115.The conduit 87 opens at its end 127 opposite to that which opens into the control device 82, directly into the pump housing 115.

L'ouverture 127 est préférentiellement contrôlée par un clapet anti-retour ou tout autre moyen capable d'obturer cette ouverture dès que la pression dans le carter-pompe 115 devient inférieure à la pression dans le conduit 87 qui est donc utilisé comme capacité de stockage de pression.The opening 127 is preferably controlled by a non-return valve or any other means capable of closing this opening as soon as the pressure in the pump casing 115 becomes lower than the pressure in the conduit 87 which is therefore used as storage capacity pressure.

Selon l'invention, la conduite 92, qui communique par l'une de ses extrémités avec la chambre 95b du dispositif 82, débouche dans le cylindre 113 par son autre extrémité.According to the invention, the pipe 92, which communicates by one of its ends with the chamber 95b of the device 82, opens into the cylinder 113 by its other end.

Préférentiellement la conduite 92 débouche dans le cylindre 113 à un niveau voisin de celui du conduit d'échappement 123. Ainsi l'ouverture et la fermeture de la conduite 92 sont contrôlés par le mouvement du piston, à peu près en même temps que l'ouverture et la fermeture de l'échappement 123. Le niveau dépend de la pression que l'on veut obtenir dans les chambres.Preferably, the pipe 92 opens into the cylinder 113 at a level close to that of the exhaust pipe 123. Thus the opening and closing of the pipe 92 are controlled by the movement of the piston, approximately at the same time as the opening and closing of the exhaust 123. The level depends on the pressure that one wants to obtain in the chambers.

La chambre haute 95a est, selon ce mode de réalisation, ouverte à l'admission donc à une pression plutôt constante. Elle peut aussi être fermée. Sa pression dépend alors de la position de la membrane 89, c'est-à-dire de la pression dans la deuxième chambre 95b.The upper chamber 95a is, according to this embodiment, open to admission, therefore at a rather constant pressure. It can also be closed. Its pressure then depends on the position of the membrane 89, that is to say the pressure in the second chamber 95b.

La pression dans la chambre basse 95b suit les variations indiquées sur la figure par la courbe B en pointillés. Sur cette figure apparaissent également la pression dans le cylindre 113 (courbe A en traits pleins) et la pression dans la capacité 87 (courbe C) pour le mélange carburé ; cette dernière pression étant voisine de la pression maximale régnant dans le carter-pompe 115.The pressure in the lower chamber 95b follows the variations indicated in the figure by the dotted curve B. In this figure also appear the pressure in the cylinder 113 (curve A in solid lines) and the pressure in the capacity 87 (curve C) for the fuel mixture; this latter pressure being close to the maximum pressure prevailing in the pump housing 115.

Pour l'ensemble des diagrammes de pression ici divulgués (c'est-à-dire figures 2, 5, 7, 9, 11 et 13) la pression (P) donnée en ordonnées est exprimée en bar tandis que l'angle de rotation du vilebrequin (θ) est exprimé en degré vilebrequins (°V).For all of the pressure diagrams disclosed herein (i.e. Figures 2, 5, 7, 9, 11 and 13) the pressure (P) given on the ordinate is expressed in bar while the angle of rotation of the crankshaft (θ) is expressed in degrees crankshafts (° V).

L'évolution desdites pressions s'explique par le fonctionnement suivant :The evolution of said pressures is explained by the following operation:

Lorsque le piston 112 descend dans le cylindre 111, il découvre la conduite 92, au niveau de son ouverture 92a sur le cylindre : on est alors autour de 105° vilebrequin.When the piston 112 descends into the cylinder 111, it discovers the pipe 92, at its opening 92a on the cylinder: we are then around 105 ° crankshaft.

Une onde de pression part donc du cylindre et rejoint la chambre basse 95b, de façon rapide et avec peu de perte de pression; la longueur de la conduite 92 est assez courte.A pressure wave therefore leaves the cylinder and joins the lower chamber 95b, quickly and with little loss of pressure; the length of the pipe 92 is quite short.

Sans la présente invention, la soupape commencerait à s'ouvrir vers 120, 130° vilebrequin. Conformément à la présente invention, la soupape ne s'ouvre que vers 180° vilebrequin environ. Ce retard à l'ouverture dépend du niveau du piquage de la conduite 92 dans le cylindre. Il dépend aussi de la longueur de ladite conduite : ici très courte (environ 15 cm), de toute façon plus courte que dans l'art antérieur.Without the present invention, the valve would begin to open around 120, 130 ° crankshaft. According to the present invention, the valve opens only around 180 ° crankshaft approximately. This delay in opening depends on the level of the stitching of the pipe 92 in the cylinder. It also depends on the length of said pipe: here very short (about 15 cm), in any case shorter than in the prior art.

Enfin, l'instant d'ouverture de la soupape 86 dépend de la dimension (surface) de la membrane 89 et de la force du ressort de rappel associé.Finally, the instant of opening of the valve 86 depends on the dimension (surface) of the membrane 89 and on the force of the associated return spring.

L'injection se termine lorsque la pression-cylindre devient supérieure à la pression dans la capacité 87.The injection ends when the cylinder pressure becomes greater than the pressure in capacity 87.

La figure 3 illustre un mode de réalisation de l'invention qui diffère du premier par l'ajout d'une canalisation 921 qui par une extrêmité débouche dans le cylindre 111, par exemple au même niveau que la conduite 92.FIG. 3 illustrates an embodiment of the invention which differs from the first by the addition of a pipe 921 which at one end opens into the cylinder 111, for example at the same level as the pipe 92.

La longueur de la canalisation 921 est supérieure à celle de la conduite 92 de sorte que l'onde de pression, issue du cylindre 111, arrive dans la chambre haute 95a après l'arrivée dans 95b de celle de la conduite 92.The length of the pipe 921 is greater than that of the pipe 92 so that the pressure wave, coming from the cylinder 111, arrives in the upper chamber 95a after the arrival in 95b of that of the pipe 92.

La figure 5 illustre ce phénomène. Sur cette figure la courbe B concerne la variation de la pression dans la chambre basse, et la courbe D la variation de la pression dans la chambre haute. La figure 5 montre que l'arrivée de l'onde de pression dans la chambre basse 95b, qui correspond à la forte montée de la pression, intervient vers 120°V. L'arrivée de l'onde de pression dans la chambre haute 95a qui se traduit par une forte augmentation de la pression, se produit seulement vers 160°V. Elle est donc en retard vis à vis de l'onde de pression dans la chambre basse, ce décalage étant notamment dû au fait que la canalisation 921 présente une plus grande longueur que la canalisation 92.Figure 5 illustrates this phenomenon. In this figure, curve B relates to the variation in pressure in the lower chamber, and curve D relates to the variation in pressure in the upper chamber. FIG. 5 shows that the arrival of the pressure wave in the lower chamber 95b, which corresponds to the strong rise in pressure, occurs around 120 ° V. The arrival of the pressure wave in the upper chamber 95a which results in a sharp increase in pressure, occurs only around 160 ° V. It is therefore late with respect to the pressure wave in the lower chamber, this offset being in particular due to the fact that the pipe 921 has a greater length than the pipe 92.

En outre la forme de l'onde de pression dans la chambre haute est différente de celle dans la chambre basse ; ceci est dû au fait que la soupape commence à s'ouvrir.Furthermore, the shape of the pressure wave in the upper chamber is different from that in the lower chamber; this is due to the fact that the valve begins to open.

De ce fait, le volume de la chambre haute augmente de façon importante (en proportion) et la pression maximale atteinte est nettement inférieure à celle de la chambre.Therefore, the volume of the upper chamber increases significantly (in proportion) and the maximum pressure reached is significantly lower than that of the chamber.

La canalisation additionnelle 921 a peu d'influence sur la durée de l'injection mais en revanche elle influe sur l'amplitude du mouvement de la soupape, puisqu'elle "ajoute" une pression à celle de la chambre haute. Cette force supplémentaire est intéressante car elle permet l'utilisation d'un ressort de plus forte raideur, ce qui facilite la fermeture de la soupape.The additional line 921 has little influence on the duration of the injection but on the other hand it influences the amplitude of the movement of the valve, since it "adds" a pressure to that of the upper chamber. This additional force is advantageous because it allows the use of a spring of greater stiffness, which facilitates the closing of the valve.

La figure 4 illustre un mode de réalisation très proche de celui de la figure 3, la différence étant que la canalisation additionnelle 921 débouche sur la canalisation 92 au lieu du piquage sur la chambre de combustion. L'effet est le même que celui de la figure 3. La figure 5 illustre donc le fonctionnement du moteur selon la figure 4. Elle ne sera pas davantage commentée.FIG. 4 illustrates an embodiment very close to that of FIG. 3, the difference being that the additional line 921 leads to the line 92 instead of the connection to the combustion chamber. The effect is the same as that of FIG. 3. FIG. 5 therefore illustrates the operation of the engine according to FIG. 4. It will not be further discussed.

Les figures 6 et 7 concernent un mode de réalisation de l'invention selon lequel au moins deux cylindres sont utilisés.Figures 6 and 7 relate to an embodiment of the invention according to which at least two cylinders are used.

La chambre haute 95a de l'un des cylindres est reliée via une conduite 926 à un autre cylindre 111'. Cet autre cylindre est, lui aussi équipé d'un moyen 82' d'assistance à la soupape dont la chambre basse 95b' est reliée audit cylindre.The upper chamber 95a of one of the cylinders is connected via a pipe 926 to another cylinder 111 '. This other cylinder is also equipped with means 82 'for assisting the valve, the lower chamber 95b' of which is connected to said cylinder.

Plusieurs cylindres peuvent ainsi être mis en liaison. On profite alors du décalage angulaire entre les cylindres.Several cylinders can thus be linked. We then take advantage of the angular offset between the cylinders.

La figure 7 illustre l'effet de ce décalage. Dans la chambre haute (courbe E) l'onde de pression arrive avec un retard d'environ 90° vilebrequin vis-à-vis de la chambre basse (courbé B). Ce retard est dû au décalage angulaire entre les deux cylindres. Le retard est contrôlable par la longueur du conduit 926 ainsi que par la position du piquage dans l'autre cylindre 111'.Figure 7 illustrates the effect of this shift. In the upper chamber (curve E) the pressure wave arrives with a delay of about 90 ° crankshaft with respect to the lower chamber (curved B). This delay is due to the angular offset between the two cylinders. The delay is controllable by the length of the conduit 926 as well as by the position of the tap in the other cylinder 111 '.

L'utilisation de la pression issue d'un autre cylindre permet l'utilisation d'un conduit (926) moins long que dans le cas d'un monocylindre (conduit 921 par exemple).The use of pressure from another cylinder allows the use of a conduit (926) shorter than in the case of a single cylinder (conduit 921 for example).

De ce fait, le signal de pression provenant du cylindre est moins atténué et sa durée est moins grande. La figure 7 montre très bien l'effet de la longueur du conduit sur la durée du signal. L'onde de pression de la courbe E a une durée moins importante que l'onde de pression de la courbe D de la figure 5. Sur la figure 7 le pic de pression de la courbe E "dure" environ 60°V tandis que sur la figure 5, le pic de pression de la courbe D s'étend sur 100°V. De plus, avec un conduit moins long, l'effet du régime sera moins important : le temps de trajet du signal de pression exprimé en seconde varie peu avec le régime, mais la variation est importante lorsqu'il est exprimé en degré vilebrequin.As a result, the pressure signal from the cylinder is less attenuated and its duration is shorter. Figure 7 shows very well the effect of the length of the conduit on the duration of the signal. The pressure wave of curve E has a shorter duration than the pressure wave of curve D of figure 5. In figure 7 the pressure peak of curve E "lasts" about 60 ° V while in FIG. 5, the pressure peak of curve D extends over 100 ° V. In addition, with a shorter duct, the effect of the speed will be less significant: the travel time of the pressure signal expressed in seconds varies little with the speed, but the variation is significant when it is expressed in crankshaft degree.

La figure 8 montre un moteur deux temps comportant les mêmes éléments que celui de la figure 1 et ayant en outre une canalisation additionnelle 922 débouchant d'une part dans la chambre haute 95a et d'autre part dans le carter-pompe 115. La canalisation additionnelle 922 présente une longueur supérieure à celle de la conduite 92 et on obtient le diagramme des pressions selon la figure 9. Ce dernier ressemble à celui de la figure 2, les courbes A, B et C étant les mêmes. Il s'y ajoute la courbe F qui correspond à la pression dans la chambre haute 95a reliée au carter-pompe 115. L'onde de pression est différente de celle de la chambre basse. Le pic de pression se produit dans la chambre basse vers 130° vilebrequin et dans la chambre haute vers 170° vilebrequin. D'autre part la valeur maximale de la pression dans la chambre haute se situe autour de 1,4 bars. Elle est bien inférieure à la valeur maximale dans la chambre basse (plus de 2 bars).FIG. 8 shows a two-stroke engine comprising the same elements as that of FIG. 1 and also having an additional pipe 922 opening on the one hand into the upper chamber 95a and on the other hand into the pump housing 115. The pipe additional 922 has a length greater than that of the pipe 92 and the pressure diagram is obtained according to FIG. 9. The latter resembles that of FIG. 2, the curves A, B and C being the same. Added to this is the curve F which corresponds to the pressure in the upper chamber 95a connected to the pump housing 115. The pressure wave is different from that of the lower chamber. The pressure peak occurs in the lower chamber around 130 ° crankshaft and in the upper chamber around 170 ° crankshaft. On the other hand, the maximum value of the pressure in the upper chamber is around 1.4 bars. It is much lower than the maximum value in the lower chamber (more than 2 bars).

Ainsi, moyennant un dimensionnement adéquate de la membrane et du ressort, la soupape 86 commence à s'ouvrir quand la pression dans la chambre haute est supérieure à celle dans la chambre basse, soit aux environs de 180° vilebrequin. Sans ce mode d'assistance, l'ouverture de la soupape débute vers 140° vilebrequin.Thus, with adequate dimensioning of the diaphragm and the spring, the valve 86 begins to open when the pressure in the upper chamber is higher than that in the lower chamber, ie around 180 ° crankshaft. Without this assistance mode, the opening of the valve begins around 140 ° crankshaft.

La fin de l'injection se situe vers 240° vilebrequin quand la pression dans le cylindre devient nettement supérieure à la pression dans la capacité 87.The end of the injection is around 240 ° crankshaft when the pressure in the cylinder becomes significantly higher than the pressure in capacity 87.

Cette configuration est plus adaptée pour un fonctionnement à régime élevé car :

  • vis-à-vis du mode de réalisation selon les figures 1 et 2, la différence de pression entre la chambre haute et la chambre basse est plus importante;
  • vis-à-vis des modes de réalisation illustrés par les figures 3, 4 et 5, le mode de réalisation selon la figure 8 permet d'avoir des temps de parcours moins importants dans les deuxièmes moyens de liaison.
This configuration is more suitable for high speed operation because:
  • vis-à-vis the embodiment according to Figures 1 and 2, the pressure difference between the upper chamber and the lower chamber is greater;
  • with respect to the embodiments illustrated in FIGS. 3, 4 and 5, the embodiment according to FIG. 8 makes it possible to have shorter travel times in the second connecting means.

La figure 10 illustre un mode de réalisation proche de celui de la figure 8 ; cependant une conduite 923 est ajoutée ; elle relie le carter-pompe 115 à la conduite 92.FIG. 10 illustrates an embodiment close to that of FIG. 8; however a line 923 is added; it connects the pump housing 115 to the pipe 92.

On obtient les évolutions de pressions A, B, C et G selon la figure 11. Ces pressions ressemblent beaucoup à celles obtenues pour la figure 9. On note cependant une diminution du pic de pression dans la chambre basse (courbe B) qui passe d'environ 2 bars à 1,8 bars. De même les résultats expérimentaux montrent une diminution de la température des gaz dans la chambre basse. Ce dernier facteur peut être important pour la durée de vie de la membrane 89.The changes in pressures A, B, C and G are obtained according to FIG. 11. These pressures are very similar to those obtained for FIG. 9. However, there is a decrease in the pressure peak in the lower chamber (curve B) which passes from '' about 2 bars to 1.8 bars. Similarly, the experimental results show a decrease in the temperature of the gases in the lower chamber. This last factor can be important for the life of the membrane 89.

La durée d'injection reste sensiblement la même que dans les cas précédents.The duration of injection remains substantially the same as in the previous cases.

Un autre mode de réalisation de l'invention est illustré à la figure 12 avec les pressions selon la figure 13. Fondamentalement, ce mode de réalisation reprend celui de la figure 8, il comprend les mêmes conduites.Another embodiment of the invention is illustrated in FIG. 12 with the pressures according to FIG. 13. Basically, this embodiment reproduces that of FIG. 8, it comprises the same pipes.

Additionnellement il comprend une liaison 924 entre la conduite 92 et la conduite 922. Ceci modifie l'évolution de la pression dans la chambre haute 95a, correspondant à la courbe H sur la figure 13. On distingue en effet sur la courbe H une brusque augmentation de pression vers 170° vilebrequin. Ceci est dû à l'arrivée de l'onde de pression provenant du cylindre via la liaison 924. L'ouverture de la soupape commence avec l'arrivée de cette onde, soit vers 170° vilebrequin. Le moment de cette ouverture est déterminée par les longueurs dans les différentes canalisations 92, 922, 924.Additionally, it includes a connection 924 between the pipe 92 and the pipe 922. This changes the evolution of the pressure in the upper chamber 95a, corresponding to the curve H in FIG. 13. A sharp increase is indeed seen on the curve H pressure around 170 ° crankshaft. This is due to the arrival of the pressure wave coming from the cylinder via the link 924. The opening of the valve begins with the arrival of this wave, ie around 170 ° crankshaft. The time of this opening is determined by the lengths in the different pipes 92, 922, 924.

L'avantage de ce mode de réalisation vis-à-vis de celui décrit en relation avec les figures 10 et 11 consiste à obtenir une plus grande différence de pression entre la chambre haute et la chambre basse. La force agissant sur la membrane 89 est de ce fait plus grande, d'où la possible utilisation d'un ressort de plus forte raideur.The advantage of this embodiment compared to that described in relation to FIGS. 10 and 11 consists in obtaining a greater pressure difference between the upper chamber and the lower chamber. The force acting on the membrane 89 is therefore greater, hence the possible use of a spring of greater stiffness.

Claims (7)

Moteur à deux temps comportant au moins - un cylindre (111) dans lequel se déplace un piston (112) dont l'une des extrémités communique avec un carter-pompe (115) traversé par le vilebrequin (114) du moteur, - une capacité sous pression (87) débouchant à une extrémité dans ledit carter-pompe, à l'autre extrémité dans la chambre de combustion (113) du cylindre (111), - une soupape (86) assurant l'obturation intermittente entre la chambre (113) et la capacité (87), - un moyen (88) destiné à carburer les gaz passant dans ladite capacité (87), - un moyen (82) de contrôle du mouvement de ladite soupape (86) comprenant une membrane souple (89) séparant une première chambre (95a) et une deuxième chambre (95b), ladite membrane étant reliée à la tige de la soupape, caractérisé en ce qu'il comprend en outre un premier moyen de liaison (92) entre la deuxième chambre (95b) et le cylindre (111), le moyen étant destiné à retarder l'ouverture de ladite soupape (86) par un contrôle de la pression dans ladite chambre (95b).Two-stroke engine with at least - a cylinder (111) in which a piston (112) moves, one end of which communicates with a pump housing (115) through which the engine crankshaft (114) passes, - a pressurized capacity (87) opening at one end into said pump housing, at the other end in the combustion chamber (113) of the cylinder (111), - a valve (86) ensuring intermittent obturation between the chamber (113) and the capacity (87), a means (88) for carburizing the gases passing through said capacity (87), a means (82) for controlling the movement of said valve (86) comprising a flexible membrane (89) separating a first chamber (95a) and a second chamber (95b), said membrane being connected to the valve stem, characterized in that it further comprises a first connecting means (92) between the second chamber (95b) and the cylinder (111), the means being intended to delay the opening of said valve (86) by a control of the pressure in said chamber (95b). Moteur selon la revendication 1, caractérisé en ce qu'il comprend en outre un deuxième moyen de liaison (921) entre la première chambre (95a) et ledit cylindre (111), ladite deuxième liaison ayant une longueur supérieure à ladite première liaison (92).Engine according to claim 1, characterized in that it further comprises a second connection means (921) between the first chamber (95a) and said cylinder (111), said second connection having a length greater than said first connection (92 ). Moteur selon la revendication 2, caractérisé en ce que ladite deuxième liaison (921) présente une branche en dérivation vis-à-vis de la première liaison (92).Motor according to claim 2, characterized in that said second link (921) has a branch branch in relation to the first link (92). Moteur selon la revendication 2, caractérisé en ce que ladite deuxième liaison (926) est réalisée entre la première chambre (95a) du moyen (82) de contrôle d'un premier cylindre et un deuxième cylindre (111').Engine according to claim 2, characterized in that said second connection (926) is formed between the first chamber (95a) of the means (82) for controlling a first cylinder and a second cylinder (111 '). Moteur selon la revendication 1, caractérisé en ce qu'il comprend en outre un deuxième moyen (922) qui débouche par une extrémité dans ledit carter-pompe (115) et par l'autre extrémité dans ladite première chambre (95a).Motor according to claim 1, characterized in that it further comprises a second means (922) which opens at one end into said pump housing (115) and through the other end into said first chamber (95a). Moteur selon la revendication 5, caractérisé en ce qu'il comprend en outre un troisième moyen de liaison (923) entre le carter-pompe (115) et le premier moyen de liaison (92).Motor according to claim 5, characterized in that it further comprises a third connection means (923) between the pump housing (115) and the first connection means (92). Moteur selon la revendication 5, caractérisé en ce qu'il comprend en outre un troisième moyen de liaison (924) entre le premier moyen de liaison (92) et la deuxième liaison (922).Motor according to claim 5, characterized in that it further comprises a third connection means (924) between the first connection means (92) and the second connection (922).
EP97400225A 1996-02-12 1997-01-31 Two stroke engine having a control means for the valve movement Expired - Lifetime EP0789138B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9602048A FR2744764B1 (en) 1996-02-12 1996-02-12 TWO STROKE MOTOR WITH A MEANS OF CONTROL OF THE MOVEMENT OF THE VALVE
FR9602048 1996-02-12

Publications (2)

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EP0789138A1 true EP0789138A1 (en) 1997-08-13
EP0789138B1 EP0789138B1 (en) 2000-04-05

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US (1) US5752477A (en)
EP (1) EP0789138B1 (en)
JP (1) JPH09228847A (en)
CN (1) CN1083932C (en)
AT (1) ATE191541T1 (en)
DE (1) DE69701585T2 (en)
FR (1) FR2744764B1 (en)
TW (1) TW338088B (en)

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Also Published As

Publication number Publication date
FR2744764B1 (en) 1998-04-17
TW338088B (en) 1998-08-11
DE69701585D1 (en) 2000-05-11
ATE191541T1 (en) 2000-04-15
FR2744764A1 (en) 1997-08-14
JPH09228847A (en) 1997-09-02
DE69701585T2 (en) 2001-01-11
US5752477A (en) 1998-05-19
CN1165241A (en) 1997-11-19
CN1083932C (en) 2002-05-01
EP0789138B1 (en) 2000-04-05

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