EP0945599A1 - Port closing valve and internal combustion engine comprising such a device - Google Patents

Abstract

The valve (C) has a rod (2) attached to a flat valve head (1) which closes an inlet or exhaust passage (3). The rod is at one edge of the valve head, and is driven in rotation to rotate the head from the closed position to an open position. A spring (9) returns the valve to the closed position. An electronic controller can be used to control the time and degree of opening of the valve.

Description

The present invention relates to an assembly comprising a valve associated with a conduit, and a heat engine, in particular with internal combustion, for example a diesel or petrol or gas engine, comprising at least one cylinder comprising at least one such together.

In internal combustion engines, the intake and exhaust are generally controlled by a camshaft, directly or through rocker arms. When opening of a valve, the air passage section, of the air / fuel mixture or exhaust gas is linked to the cam profile, which limits the control of the cylinder opening / closing devices: it is not possible to adjust, as desired, the amount of gas admitted by acting on the opening of the valves according to the parameters of engine operation, in particular, for very low engine speeds motor; this results in low exhaust gas pollution speed, which corresponds to the operation of the engines in the urban conditions of slow traffic. Furthermore, when we wish to reopen an exhaust valve to use energy puffs of exhaust from other engine cylinders so self-supercharging, as suggested, for example, in patent application WO 95/14853, this reopening is linked to a cam control which is relatively rigid in phase.

The invention therefore aims to eliminate the drawbacks aforementioned and proposes to replace conventional engine valves thermal by assemblies each consisting of a valve associated with a duct, each set offering a passage cross-section coefficient more efficient and the ability to adjust the cross sections, and therefore pressure losses at gas passage, at independent parameters of the valve control, in particular parameters of engine operation.

To this end, the invention relates to a set comprising a valve associated with at least one conduit, said valve comprising a rod connected to a shutter to bring the latter against its seat in a closed position of the conduit (s), and move the shutter away from its seat in an open position of the (des) conduit (s), characterized in that the rod is offset by relative to the shutter and intended to be rotated substantially around its axis to move the shutter in circular translation substantially at the right of its seat, in the manner a guillotine. Preferably, the rod is substantially perpendicular to the shutter and the seat is substantially flat, the shutter having, facing its seat, a substantially flat face, the displacement, during the rotation of the rod, takes place substantially in the seat plan. The rod is advantageously a cylindrical rod of circular cross section driven in rotation about its axis.

According to another characteristic, this set includes a means for axially moving the rod for a short distance at less at the start of the opening of the duct in order to take off the shutter from his seat ; this means can be controlled by the rotation of the rod of the valve.

According to yet another characteristic, the set of the invention includes means for holding the shutter slightly axially separated from its seat, until the opening of the drove.

In a particular embodiment, the means for axially move the valve stem consists of a nut immobilized in rotation and an externally threaded portion of the rod engaging through said nut and cooperating with it, the step of respective threads of the nut and of said portion being weak so as not to move the rod only a short distance. The nut is housed in preferably with axial play in a fixed cage used to immobilize rotating the nut. This axial play is preferably less than the axial displacement of the valve stem, so that the nut comes in abutment against the cage when the duct is opened under the effect of a elastic means for returning the valve to its seat, the cage serving then means to keep the valve away from its seat. The step of threads is determined so that the axial displacement of the rod of the valve during its angular movement, i.e. of the order of a few tenths of a millimeter; the angular displacement of the rod of the valve can be of the order of 90 °.

The invention also relates to a heat engine, in particular internal combustion, comprising at least one cylinder associated with at least one intake duct and at least one duct exhaust, characterized in that it comprises, on one at less of its intake or exhaust ducts, a whole valve / conduit as defined above.

In this case, the engine may include a system electronic or electro-hydraulic control defining the laws opening and closing of each valve according to engine operating parameter (s).

The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly on course of the detailed explanatory description which follows in a currently preferred particular embodiment of the invention, given only for illustration and not limitation, with reference to the drawing diagram attached.

• la figure 1 est une vue partielle, en coupe axiale, d'une culasse de moteur dont le conduit d'admission est équipé d'un clapet pour constituer un ensemble selon l'invention ;
• la figure 2 est une vue de dessus suivant la ligne II-II de la figure 1;
• la figure 3 est une vue agrandie de la portion supérieure du clapet de la figure 1 ;
• la figure 4 est une vue schématique de dessus d'un cylindre équipé d'un clapet d'admission selon les figures 1 à 3, cette vue montrant les positions successives de l'obturateur du clapet au cours de la rotation de la tige ; et
• la figure 5 est une vue schématique de dessus montrant un cylindre équipé d'un clapet d'admission et d'un clapet d'échappement et représentant les positions extrêmes du débattement angulaire des deux clapets ;
• les figures 6A à 6G représentent une vue schématique de dessus relative à l'utilisation, pour un même cylindre de moteur, d'une pluralité de clapets selon l'invention ;
• les figures 7A à 7F représentent une vue schématique de dessus relative à l'utilisation, pour un même cylindre de moteur, d'une pluralité de clapets doubles, chaque clapet étant associé à deux conduits qui sont obturés ou ouverts simultanément ;

On this drawing :

• Figure 1 is a partial view, in axial section, of an engine cylinder head whose intake duct is equipped with a valve to form an assembly according to the invention;
• Figure 2 is a top view along the line II-II of Figure 1;
• Figure 3 is an enlarged view of the upper portion of the valve of Figure 1;
• Figure 4 is a schematic top view of a cylinder equipped with an intake valve according to Figures 1 to 3, this view showing the successive positions of the valve shutter during the rotation of the rod; and
• Figure 5 is a schematic top view showing a cylinder equipped with an intake valve and an exhaust valve and showing the extreme positions of the angular movement of the two valves;
• FIGS. 6A to 6G represent a schematic top view relating to the use, for the same engine cylinder, of a plurality of valves according to the invention;
• FIGS. 7A to 7F represent a schematic view from above relating to the use, for the same engine cylinder, of a plurality of double valves, each valve being associated with two conduits which are closed or open simultaneously;

According to the particular example illustrated in the drawings, the valve C of the invention consists of a generally planar shutter and circular 1 secured at its periphery to a control rod 2 extending perpendicular to the shutter 1. The rod 2 of the valve C is eccentric with respect to shutter 1 as well as with respect to a intake duct 3 formed through the cylinder head 4 of a internal combustion. In the position illustrated in Figure 1, the shutter 1 bears against a seat 4a provided on the cylinder head 4 to the lower end of the intake duct 3. The rod 2 of the valve C also passes through the cylinder head 4 perpendicularly to the latter and to distance from intake duct 3.

The lower end of the rod 2, which is connected to the shutter 1, is located on the side of the cylinder of the engine, while the other end of the rod 2 opens on the other side of the cylinder head 4. This other end of the rod 2 has an externally threaded portion 2a, which engages through a nut 5 housed in a cage 6, which secures the nut against rotation relative to the cylinder head. The nut 5 may have fins or radial ribs 5 a which are received in corresponding notches 6a in the cage 6 to immobilize the rotating nut. The cage 6 has a central opening 6 b for the passage of the rod 2 of the valve and a peripheral flange 6 c at its base for its attachment to the cylinder head 4 of the engine, for example by means of a screw 7.

As visible in FIG. 2, the peripheral flange 6 c of the cage 6 comprises, for example, a through groove 8 in the form of an arc of a circle centered on the axis A of the rod 2, a groove through which engages the screw 7 to allow the initial adjustment of the axial clearance "e" between the cylinder head and the nut and of the axial clearance "f" between the nut and the cage (see FIG. 3).

A return spring 9 is interposed between the cage 6 and a cup 10 secured to the upper end of the rod 2; as shown in FIGS. 1 and 3, the cup 10 can carry gear teeth externally in order to ensure the rotational maneuver of the rod 2. The cup 10 can comprise an eccentric mass opposite the valve C so as to balance in rotation the valve-stem-cup assembly and thus reduce the energy necessary for its rotation. The spring 9 bears against this cup 10 by means of a needle bearing 11, or a sliding stop or the like, to avoid torsion of the spring 9 during the rotation of the rod 2 about its axis A The other end of the spring 9 applies the peripheral collar 6c of the cage 6 against the cylinder head. It will easily be understood that this spring 9 exerts an elastic restoring force on the rod 2 in order to apply the shutter 1 against its seat 4a in the closed position of the conduit. The presence of the clearance f ensures that it is the spring 9 which applies the shutter 1 against its seat 4 a . If this clearance f was not provided, the shutter could be prevented from coming into tight contact with the seat 4a, by prior abutment of the nut 5 against the cage 6.

The play e is necessarily linked to the presence of the clearance f to allow adjustment of the latter. Of course, games and f are complementary because they correspond to the difference of axial height between nut 5 and cage 6. Initial clearances e and f can be adjusted thanks to the adjustment groove 8 which makes it possible to make pivot the cage 6 and therefore the nut 5 around the axis A; this movement rotation of the nut 5 is accompanied by an axial displacement of the nut 5 in the cage 6 relative to the rod 2 which remains fixed in rotation during of this setting.

We will now briefly describe how the valve of the invention.

In the initial closed position of the duct, shown in FIGS. 1 and 3, the shutter 1 is in abutment against its seat 4 a , under the action of the return spring 9 and of the possible pressure which prevails in the cylinder chamber 12.

To open the valve C, the rod 2 is rotated around its axis A, which has the effect of simultaneously causing an axial displacement of the rod 2 downward, since the nut 5 is immobilized in rotation. This axial displacement of the rod 2 makes it possible to take off the shutter 1 very slightly from its seat 4 a , and therefore to facilitate the opening of the valve by applying a minimum torque at the level of the rotary control. Indeed, the pitch of the nut 5 and the external thread of the portion 2 has the shaft 2 is very small and just sufficient to slightly off the valve seat.

As soon as the shutter 1 deviates slightly from its seat 4 a in the axial direction, the spring 9 recalls the rod 2 back upwards until the nut 5 abuts against the cage 6 by filling the initial game f. This initial clearance f is therefore preset so that from the start of the opening of the duct, the nut 5 abuts against the cage 6. As the nut 5 can no longer move axially relative to the cage 6, it keeps the shutter 1 slightly axially spaced from the seat 4 has during the subsequent rotation of the rod up to complete opening of the conduit. The return action of the spring 9 is thus neutralized as soon as the opening of the duct begins, and the shutter gradually moves away from its seat until the complete opening.

At the end of the opening stroke, the shutter 1 will have moved over an angle of approximately 90 ° in a plane substantially parallel to the seat 4 a and over a distance of a few tenths of a millimeter in the axial direction.

The detachment of the shutter 1 from its seat 4 a from the start of the opening of the duct makes it possible to eliminate the friction between the shutter and its seat, this friction being able to be considerable, during the opening of a duct exhaust, taking into account the pressure that may exist in the cylinder after combustion of the gases.

To close the valve, simply perform the above operations, in reverse order: the rod 2 is rotated in the opposite direction until the shutter 1 comes into partial contact with its seat 4a moving axially upwards; during this first phase of rotation, the nut 5 remains in abutment against the cage 6; rotation then continues until the shutter 1 moves in rubbing contact against its seat 4 a : the nut 5 then deviates axially from the cage 6 downwards to reconstitute the play f. For closing the valve, it is not inconvenient that the shutter 1 rubs against the seat 4 has end of stroke, since the pressure in the cylinder is then low or close to atmospheric pressure.

There is shown schematically in Figure 5 a cylinder 12 comprising an intake duct 3 and a duct exhaust 13 each provided with a valve according to the invention. The angular movement α of the intake valve can be of the order of 79 ° and the angular movement β of the exhaust valve can be around 86 °. Note that the opening and closing of these two valves must be synchronized to prevent the shutters 1 of these two valves do not interfere with each other due to the limited size of the cylinder (the respective angular travel of the two shutters is shown in phantom in Figure 5).

Of course, several valves of the type described above can be installed per cylinder, for example, one for intake and one for exhaust, two for intake and one for the exhaust, two for the intake and two for the exhaust. In FIGS. 6A to 6G, there is shown, schematically, the possible positioning on the same cylinder of four, three or two valves of the type described above. In FIGS. 7A to 7F, we have shown, for a cylinder with four conduits, the positioning of two double valves relative to these four conduits, the rotation of the stem of a double valve causing the opening or simultaneous closing of two conduits. The shape of the shutter 1 can be a circular sector or any other form of interest in the evolution of the discovery section of the associated duct. The rotation control of the valve stem 2 can be done by a direct current, alternating or stepping electric motor, or by hydraulic servo. In addition, a electronic system defining the opening and closing laws valves according to one or more parameter (s) of engine operation. This order can be made directly on rod 2, or via a pinion system or belts.

• on obtient une section de passage d'air ou de gaz entièrement programmable, et non liée à un profil d'une came, la commande du système pouvant être cartographiée en fonction de la charge et/ou du régime et/ou d'autres paramètres du fonctionnement du moteur, d'où il résulte notamment une réduction des émissions polluantes et de la consommation ;
• l'arbre à cames et sa commande sont supprimés ;
• les commandes de soupapes et leurs systèmes de rattrapage de jeu sont supprimés ;
• le coefficient de section de passage efficace est bien meilleur qu'avec un système soupape/siège de type classique, ce qui est intéressant pour l'admission, mais encore plus pour l'échappement, en raison d'une perte de charge réduite entre l'obturateur et son siège ;
• il devient possible d'inclure facilement un système de rotation de la charge d'air dans le conduit d'admission pour les moteurs à injection directe ;
• on peut supprimer le papillon des gaz à l'admission, car le clapet de l'ensemble selon l'invention le remplace ;
• il est possible de faire fonctionner le moteur à très bas régime, car il est possible de contrôler la quantité d'air, ou de mélange air-carburant, admis en ajustant l'ouverture du clapet en fonction des paramètres de fonctionnement du moteur ;
• on réduit la pollution en ville des moteurs de véhicules automobiles par un fonctionnement à très bas régime dans les phases de ralenti, notamment dans les embouteillages, étant donné que la quantité de gaz émise est directement proportionnelle au régime de rotation, hors de toute diminution des émissions, en raison d'un meilleur contrôle des organes d'ouverture/fermeture du cylindre ;
• on peut entièrement programmer ou annuler la réouverture d'un clapet d'échappement pour l'utilisation de l'énergie des bouffées des autres cylindres en vue d'une autosuralimentation.

Compared to engines fitted with conventional valves, the invention has the following advantages:

• a fully programmable air or gas passage section is obtained, and not linked to a profile of a cam, the control of the system being able to be mapped as a function of the load and / or the speed and / or other parameters engine operation, which results in particular in reducing polluting emissions and consumption;
• the camshaft and its control are deleted;
• valve controls and their backlash systems are removed;
• the coefficient of effective passage section is much better than with a valve / seat system of the conventional type, which is advantageous for the intake, but even more for the exhaust, due to a reduced pressure drop between the shutter and its seat;
• it becomes possible to easily include a rotation system of the air charge in the intake duct for direct injection engines;
• the throttle valve can be eliminated on intake, because the valve of the assembly according to the invention replaces it;
• it is possible to operate the engine at very low speed, since it is possible to control the quantity of air, or air-fuel mixture, admitted by adjusting the opening of the valve according to the operating parameters of the engine;
• the pollution of motor vehicle engines in town is reduced by operating at very low speed in the idling phases, in particular in traffic jams, since the quantity of gas emitted is directly proportional to the rotation speed, out of any reduction in emissions, due to better control of cylinder opening / closing devices;
• you can fully program or cancel the reopening of an exhaust valve to use the energy from the puffs of other cylinders for self-supercharging.

Although the invention has been described in connection with a mode of particular achievement, it is obvious that it is by no means limited and that it includes all the technical equivalents of the means described as well as their combinations, if these fall within the scope of the invention.

Claims (10)

Assembly comprising a valve (C) associated with at least one conduit (3, 13), said valve comprising a rod (2) connected to a shutter (1) to bring the latter against its seat (4 a ) in a closed position of the duct (s), and move the shutter away from its seat in an open position of the duct (s), the rod (2) being eccentric relative to the shutter (1) and intended to be rotated substantially about its axis for moving the shutter in a substantially circular translation to the right of the seat (4a), characterized in that it comprises means (2a, 5) for axially moving the rod (2) over a short distance at least at the start of the opening of the duct in order to take off the shutter from its seat. Assembly according to claim 1, characterized in that the rod (2) is substantially perpendicular to the shutter (1) and the seat (4 a ) is substantially planar, the shutter (1) having opposite from its seat (4a) a substantially plane face of which the displacement during the rotation of the rod, substantially in the plane of the seat (4a). The assembly of claim 1 or 2, characterized in that the means (2a, 5) for axially moving the rod is controlled by the rotation of the shaft (2) of the valve. Assembly according to one of claims 1 to 3, characterized in that it comprises means (6) for holding the shutter (1) slightly axially away from its seat (4 a ) until the complete opening of the conduit (3, 13). Assembly according to one of claims 1 to 4, characterized in that the means for axially moving the rod (2) of the valve consists of a nut (5) immobilized in rotation, and an externally threaded portion (2 a ) of the rod (2) engaging through said nut to cooperate with it, the pitch of the respective threads of the nut (5) and of said portion (2 a ) being small so as not to move the rod (2) only over a short distance. Set according to claims 4 and 5 taken simultaneously, characterized in that the nut (5) is housed with axial clearance (e, f) in a fixed cage (6) used to immobilize in rotation said nut (5). Assembly according to claims 4 and 6 taken simultaneously, characterized in that the axial play (f) is less than the axial displacement of the rod (2) of the valve, so that the nut (5) abuts against the cage (6) at the opening of the conduit, under the effect of resilient means (9) for returning the valve to its seat (4a), the cage (6) then serving as means for holding the removed valve from its headquarters (4 a ). Assembly according to claim 5 taken alone or in combination with one of claims 6 and 7, characterized in that the pitch of the threads of the nut (5) and of the threaded portion (2 a ) of the rod (2 ) is determined so that the axial displacement of the rod (2) of the valve, during an angular displacement of approximately 90 °, is of the order of a few tenths of a millimeter. Heat engine, in particular internal combustion, comprising at least one cylinder (12) associated with at least one conduit intake and at least one exhaust duct, characterized by fact that it understands, on at least one of its intake ducts or exhaust, an assembly according to one of claims 1 to 8. Motor according to claim 9, characterized in that that it includes an electronic control system defining the opening and closing laws of each valve according to engine operating parameter (s).

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