EP1238189B1 - Device for modifying compression rate to optimize operating conditions of reciprocating piston engines - Google Patents

Description

Technical area

The present invention relates to a device, a reagent and consuming very little energy, to continuously optimize the compression ratio including reciprocating piston engines. This invention is especially relevant to improve the fuel efficiency of engines that are not used permanently at maximum load or using multiple fuels different octane numbers. This invention is compatible with a very weak level of pollution and is particularly suitable for reciprocating piston engines whose cylinders are arranged either flat, V or line. In the present document, the denoted "compression ratio" refers to the geometric of compression of an internal combustion engine with reciprocating pistons.

Prior art

Continuous optimization of the compression ratio is relevant to reduce the fuel consumption and the contribution to the greenhouse effect for where the engines are not fully loaded and for engines that use multiple fuels of different octane number.

Combustion in spark ignition engines used at very low loads is more complete when the compression ratio is optimized during the operation. The emissions of mono-carbon monoxide, hydrocarbons and particles are therefore lower.

Continuous optimization of compression ratio is relevant to maintain a compression-ignition mode engine of a premix of oxidizer and fuel. Such a mode of operation, described in particular in WO 99 42718 A, makes it possible to achieve a very low level of oxide emission. nitrogen.

Moreover, the optimization of the compression ratio is compatible with the common systems for reducing emissions of nitrogen oxides, such as exhaust gas recirculation (EGR) or catalysts for nitrogen oxides.

Various solutions to modify the compression ratio of piston engines alternatives are part of the prior art. A summary is presented below.

A known solution for varying the compression ratio is to place a moving part in the breech. WO 99 13206 A describes an example. The sliding of this part must be ensured in the presence of gases in the process of combustion. Interstices should be kept to a minimum to limit unburned. The moving part takes place with the valves in the cylinder head and participates to the shape of the combustion chamber.

US Pat. No. 2,770,224 mentions a motor, whose block divided into two articulated parts makes it possible to vary the distance between each piston and the cylinder head corresponding. WO 93 23664 A discloses a solution for enslaving this type of device. The separation effort of the two parts of the engine block is used to reduce the compression ratio and to store energy. energy stored is then used to increase the compression ratio when the engine load decreases. Operating hysteresis is limited by energy supplied by an actuator. The structure of the engine block is designed and sized to ensure the mechanical strength of the connection between the two articulated parts of the block engine as well as to minimize vibration.

WO 95 29329 A discloses a device comprising two eccentric at the head of each connecting rod. The angular setting of these two eccentrics is a function of the load of the motors and allows to change the distance between each piston and the corresponding cylinder head.

One category of solutions consists in modifying the length of the connecting rod, by example by adding a joint that changes the straightness of the connecting rod. The patents EP 0 520 637 A and DE 195 02 820 A can be classified in this category of solutions. Additional parts that transmit the efforts between crankshaft pistons and crank pins must be designed and sized to consequence to ensure the required reliability.

Another category of solutions, more particularly adapted to line, has eccentrics mounted on the crankshaft bearings to modify the distance between the crankshaft axis and the cylinder head. Patents FR 2,669,676 A, US-A-1 872,856, US-A-4,738,230, DE-A-3,601,528 disclose devices which can be classified in this category. The rigidity of the crankshaft bearings must be Compatible with the required longevity. DE 297 19 343 U discloses a device to ensure alignment of the crankshaft with the transmission. A pinion mounted in The end of the crankshaft meshes with an internal gear mounted on the flywheel. The teeth of these gears must withstand the rotational vibration modes of the crankshaft, ensure the required longevity and silence of operation.

WO 91 10051 A discloses an eccentric placed between the foot of each connecting rod and the crankpin corresponding crankshaft, whose angular setting is obtained through gears. These gears must be designed and constructed to ensure longevity as well as the required operating silence.

The patents JP 7527/90, JP 7528/90, JP 125166/90 and EP 0 438 121 A1 have eccentric, mounted either at the top or at the bottom of each connecting rod, whose position angular is hydraulically actuated and stabilized by a removable finger. This finger must be designed and sized to ensure the required reliability and durability. This device allows a discreet adjustment of the compression ratio.

Presentation of the invention

The subject of the invention is a continuous optimization device the compression ratio, in ranges determined by construction, in particular for engines with cylinders either in line, V or flat. The invention has the advantage as far as the necessary technologies are concerned, to be compatible with current technologies used industrially for cylinder heads, engine blocks, crankshafts and their connections to transmissions. It also has the advantage with regard to its implementation, allow the use of technologies similar to technologies already controlled and reliability on reciprocating piston engines. The particular modes of realization according to the invention has other advantages mentioned later in this description.

The present invention applies to piston internal combustion engines alternative animated by a crankshaft. Each of these engines has one or a plurality of combustion chambers and a housing. The crankcase is defined for the this description and the claims as the part (or rigid assembly of parts) which ensures (s) the connection between the combustion chamber (s) and the fixed parts of the bearings of the crankshaft. The axis of rotation of the trunnions crankshaft is called the axis of the crankshaft. These engines also include a (or more) breech (s) which is (are) distinct or monoblock with the casing.

Each piston is linked to a crankpin crankpin in particular by an axis of piston, a connecting rod and an eccentric placed between the foot of this rod and the crank pin corresponding crankshaft. Changing the compression ratio of each combustion chamber is obtained through the modification of the distance between the axis of the crankshaft and the axis of the connecting rod foot. The modification of each of these distances is controlled by the angular setting of the eccentrics supra. For the description and claims of the present invention, a piston is at the top dead center for every complete revolution of the crankshaft, when the distance is minimal between this piston and the corresponding cylinder head.

• déplacer un point dans un plan orthogonal à l'axe du vilebrequin ;
• maintenir un axe géométrique dans un plan orthogonal à l'axe du vilebrequin et articuler cet axe géométrique autour du point d'intersection de la projection du point cité à l'alinéa précédent avec le plan de rotation de cet axe géométrique ;
• choisir un autre axe géométrique contenu dans un plan également orthogonal à l'axe du vilebrequin et maintenir le parallélisme et une distance fixe entre les deux axes géométriques précités, de sorte que leur direction lorsque le piston est au point mort haut, et la direction du déplacement du point cité au premier alinéa soient distinctes ;
• maintenir une position relative figée entre l'axe géométrique objet du choix cité à l'alinéa précédent, et l'excentrique placé entre le pied de bielle et le maneton du vilebrequin.

The method consists in modifying the compression ratio of each combustion chamber by performing the functions described below, with possible deviations included in tolerances compatible with the good functioning and the possibilities of realization:

• move a point in a plane orthogonal to the crankshaft axis;
• maintain a geometric axis in a plane orthogonal to the axis of the crankshaft and articulate this geometric axis around the point of intersection of the projection of the point cited in the preceding paragraph with the plane of rotation of this geometric axis;
• choose another geometric axis contained in a plane also orthogonal to the axis of the crankshaft and maintain the parallelism and a fixed distance between the two aforementioned geometric axes, so that their direction when the piston is at the top dead center, and the direction of the referred to in the first paragraph are distinct;
• maintain a relative position fixed between the geometric axis object of the choice cited in the previous paragraph, and the eccentric placed between the small end and the crankpin crankshaft.

• le point qui est déplacé dans un plan orthogonal à l'axe du vilebrequin sera appelé le point mobile ;
• le plan orthogonal au vilebrequin dans lequel se déplace le point mobile sera appelé le plan du point mobile ;
• le premier axe géométrique défini dans le procédé selon l'invention sera appelé l'axe articulé ;
• le plan orthogonal à l'axe du vilebrequin qui contient la projection du point mobile qui articule l'axe articulé et dans lequel l'axe articulé est maintenu, sera appelé le plan de projection ;
• la projection du point mobile sur le plan de projection sera appelé le point d'articulation ;
• le second axe géométrique défini dans le procédé selon l'invention sera appelé l'axe fixé à l'excentrique ;
• le plan orthogonal à l'axe du vilebrequin contenant l'axe fixé à l'excentrique sera appelé le plan de levier.

The vocabulary defined hereinafter will be used in the remainder of this description to designate the points, the planes and the geometric axes of the method described in the preceding paragraph:

• the point that is moved in a plane orthogonal to the crankshaft axis will be called the moving point;
• the plane orthogonal to the crankshaft in which the moving point is moving will be called the plane of the moving point;
• the first geometric axis defined in the method according to the invention will be called the articulated axis;
• the plane orthogonal to the axis of the crankshaft which contains the projection of the movable point which articulates the articulated axis and in which the articulated axis is maintained, will be called the projection plane;
• the projection of the moving point on the plane of projection will be called the point of articulation;
• the second geometric axis defined in the method according to the invention will be called the axis fixed to the eccentric;
• the plane orthogonal to the axis of the crankshaft containing the axis attached to the eccentric will be called the plane of the lever.

For engines with multiple combustion chambers, the process according to the invention is applied to each combustion chamber whose modification of the compression ratio is sought.

The process will be better understood when reading the seven paragraphs written below. These seven paragraphs concern the process for changing the compression ratio of a single chamber of combustion of the engine.

The embodiments according to the invention relate to the geometrical characteristics exact cited in the process. However, any realization is made with deviations from the exact values. These possible deviations from exact geometric characteristics are within compatible tolerances with the possibilities of achievements according to the process and allow a good engine operation.

The movable point plane, the projection plane and the lever plane are defined with respect to the axis of the crankshaft. But the crankshaft and its axis do not have possibility of axial translation relative to the housing. The plane of the moving point, the projection plane and the lever plane therefore always have the same positions relative to the housing. The displacements of the articulated axis, of the axis fixed at the eccentric, the moving point and the point of articulation are displacements relative to the crankcase.

• l'axe articulé et l'axe fixé à l'excentrique ont la même direction ;
• tout déplacement de l'axe articulé n'est possible que dans le plan de projection ;
• tout déplacement de l'axe fixé à l'excentrique n'est possible que dans le plan de levier;
• toute translation de l'axe articulé avec une composante perpendiculaire à lui-même entraíne l'axe fixé à l'excentrique selon cette composante ;
• toute translation de l'axe fixé à l'excentrique avec une composante perpendiculaire à lui-même, provoque une translation de l'axe articulé selon cette composante ;
• toute rotation de l'axe articulé autour du point d'articulation provoque une rotation de même angle de l'axe fixé à l'excentrique autour de la projection orthogonale du point d'articulation sur le plan de levier ;
• toute rotation de l'axe fixé à l'excentrique autour de l'axe du maneton correspondant du vilebrequin provoque une rotation identique de l'axe articulé ;
• les translations relatives entre l'axe articulé et l'axe fixé à l'excentrique parallèlement à eux-mêmes ne sont ni interdite ni prescrite par le procédé selon l'invention , deux cas sont donc possibles, soit la réalisation permet les translations citées dans cet alinéa, soit la réalisation ne les permet pas.

The articulated axis and the axis fixed to the eccentric are kept parallel and equidistant from each other. Each of these two axes is contained in a plane orthogonal to the axis of the crankshaft. None of these two axes changes plan during the process. These characteristics have in particular the consequences, obtained in practice with possible deviations compatible with the proper functioning and the possibilities of realization, enumerated below:

• the articulated axis and the axis fixed to the eccentric have the same direction;
• any displacement of the articulated axis is only possible in the projection plane;
• any displacement of the axis fixed to the eccentric is only possible in the plane of the lever;
• any translation of the articulated axis with a component perpendicular to itself leads to the axis fixed to the eccentric along this component;
• any translation of the axis fixed to the eccentric with a component perpendicular to itself, causes a translation of the articulated axis according to this component;
• any rotation of the axis articulated around the articulation point causes a rotation of the same angle of the axis fixed to the eccentric around the orthogonal projection of the articulation point on the lever plane;
• any rotation of the axis fixed to the eccentric around the axis of the crankpin corresponding crankshaft causes an identical rotation of the articulated axis;
• the relative translations between the articulated axis and the axis fixed to the eccentric parallel to themselves are neither prohibited nor prescribed by the method according to the invention, two cases are therefore possible, or the embodiment allows the translations cited in this paragraph, the realization does not allow them.

The method is therefore compatible with devices for which the operation induces a variation of the distance between the point of articulation and the axis of the crankpin corresponding crankshaft.

The method is also compatible with devices which do not allow variation of the distance between the point of articulation and the axis the crankpin corresponding crankshaft.

The angular setting of the eccentric on his crank pin is dependent on angular setting of the axis fixed to the eccentric and the articulated axis with respect to the casing. At two distinct positions of the moving point in the plane of the moving point, the direction between these two distinct positions of the moving point not being parallel to the direction of the articulated axis and the axis attached to the eccentric when the piston is at top dead center, corresponds to two different angular wedges of the articulated axis, the axis attached to the eccentric and the eccentric, relative to the housing. At these two angular wedges corresponds to two different compression ratios except for the cases where these two angular wedges correspond to the same distance between the axis of the crankshaft and the axis of the small end.

This paragraph lists several specific applications of the process data as non-limiting examples. For the first, the point mobile and the point of articulation are in the same plane perpendicular to the axis of the crankshaft. For the second, the moving point is coincident with the point hinge. For these two particular applications, the moving point plane is confused with the projection plane. For the third, the articulated axis and the axis fixed at the eccentric are in the same plane perpendicular to the axis of the crankshaft. For the fourth, the articulated axis and the axis fixed to the eccentric are merged. For these last two particular applications, the projection plane and the lever plane are confused. All possible combinations between applications The aforementioned particulars are applications of the method.

According to another characteristic, the moving point is driven in translation by a point whose displacement has parallel components and perpendicular to the plane of the moving point.

• déplacer un point dans un plan orthogonal à l'axe du vilebrequin ;
• maintenir un axe géométrique dans un plan orthogonal à l'axe du vilebrequin et articuler cet axe géométrique autour du point d'intersection de la projection du point cité à l'alinéa précédent avec le plan de rotation de cet axe géométrique ;
• choisir un autre axe géométrique contenu dans un plan également orthogonal à l'axe du vilebrequin et maintenir le parallélisme et une distance fixe entre les deux axes géométriques précités, de sorte que leur direction lorsque le piston est au point mort haut, et la direction du déplacement du point cité au premier alinéa de cette troisième phase, soient distinctes ;
• maintenir une position relative figée entre l'axe géométrique objet du choix cité à l'alinéa précédent, et l'excentrique placé entre le pied de bielle et le maneton du vilebrequin ;
• contrôler le déplacement du point cité au premier alinéa de cette troisième phase afin de faire converger le taux de compression vers la valeur optimale calculée à la seconde phase.

According to another characteristic, the method is also applicable to internal combustion heat engines also comprising an electronic device for calculating optimum values for controlling the operation of these motors, sensors for measuring the values of physical quantities which characterize the operation of these engines. motors, devices for adjusting controls of the operation of these engines to the values calculated by the calculation device cited above. This method comprises three phases carried out during the operation of the engines, the first phase consists of measuring the values of physical quantities which characterize the operation of these engines, these physical quantities comprising the compression ratio, the second phase consists of calculating, as a function of physical quantities measured in the first phase, the optimal values of engine controlled parameters to maximize the energy efficiency and minimize pollutant discharges, these controlled parameters including the compression ratio, the third phase consists, for each cylinder, in performing the functions described below:

• move a point in a plane orthogonal to the crankshaft axis;
• maintain a geometric axis in a plane orthogonal to the axis of the crankshaft and articulate this geometric axis around the point of intersection of the projection of the point cited in the preceding paragraph with the plane of rotation of this geometric axis;
• choose another geometric axis contained in a plane also orthogonal to the axis of the crankshaft and maintain the parallelism and a fixed distance between the two aforementioned geometric axes, so that their direction when the piston is at the top dead center, and the direction of the referred to in the first paragraph of this third phase, be distinct;
• maintain a relative position fixed between the geometric axis object of the choice cited in the previous paragraph, and the eccentric placed between the small end and the crankpin crankshaft;
• control the displacement of the point mentioned in the first paragraph of this third phase in order to converge the compression ratio towards the optimal value calculated in the second phase.

For the other characteristic of the process described in the preceding paragraph, the compression rate is measured through the measurement of a physical quantity that calculates this compression ratio, for example: displacement measurement of the articulation point. Other physical quantities measured by this process are part of the physical quantities usually taken into account for piloting internal combustion engines with reciprocating pistons. The parameters ordered engine to maximize fuel efficiency and minimize emissions pollutants, other than the compression ratio, are part of the parameters normally used for the control of internal combustion engines reciprocating pistons.

According to another characteristic, the process described above is completed, on the one hand by the calculation in the second phase: quantities of air and allowed fuel for combustion as well as the trigger angle of the according to the values of physical quantities which characterize the operation of the engines measured in the first phase, in particular the compression, on the other hand by the order in the third phase of the devices for obtaining the quantity of air admitted, the quantity of fuel allowed, of the trigger angle of combustion, so as to converge the values of these three parameters ordered to the values calculated in the second phase depending in particular on the compression ratio.

The dosage of the amount of air admitted for light loads has several advantages. The temperature at the end of combustion can be lower and therefore favor mechanical longevity, energy efficiency and the fight against nitrogen oxides. It is also a relevant parameter to maintain an engine in compression ignition mode of an oxidant premix and fuel. It should be noted that the air intake dosage obtained by adjusting the calibration intake valves is relevant to limit pressure drops on admission.

The device according to the invention, integrated with an internal combustion engine with reciprocating pistons driven by a main crankshaft with an eccentric placed between the foot of each connecting rod and the corresponding crankpin crankpin principal is characterized in that each eccentric placed between the foot of each connecting rod and the corresponding crankpin of the main crankshaft is oriented using a rod whose direction is articulated on a pivot.

According to a first list of additional features of the device according to the invention, for each eccentric placed between a small end and the corresponding crankpin of the main crankshaft, the rod is attached to the eccentric and part of this rod slides in an articulated part on the axis of the pivot. This pivot is fixed or articulated, either on a slider or on the arms articulated of a pendulum. The slide or the pendulum is guided by a system of guidance and enslaved in position. The whole is built to respect, during the operation, geometric characteristics within tolerances compatible with the possibilities of realization as well as with the good operation device and motor. These geometric characteristics are as follows: the axis of the sliding part of the rod is in a plane perpendicular to the axis of the main crankshaft, the movements of the pivot, the slider or the articulated arms are made in planes perpendicular to the axis of the main crankshaft, the axis of the pivot is parallel to the axis of the main crankshaft.

According to a second list of additional features of the device according to the invention, for each eccentric placed between a small end and the corresponding crankpin of the main crankshaft, part of the rod slides in a piece of solidarity with the eccentric. This sliding rod is also solidary with an articulated part on the axis of the pivot. This pivot is fixed or articulated, either on a slider, either on the articulated arms of a pendulum. The slide or the pendulum is guided by a guidance system and enslaved in position. The whole is built to respect, during operation, geometrical characteristics within tolerances compatible with the possibilities of realization as well only with the proper functioning of the device and the motor. These features the following are the following: the axis of the sliding part of the rod is in a plane perpendicular to the axis of the main crankshaft, the movements of the pivot, slider or articulated arms are made in planes perpendicular to the axis of the main crankshaft, the axis of the pivot is parallel to the axis of the crankshaft main.

• l'axe d'articulation du châssis est confondu avec l'axe du vilebrequin principal ;
• chaque pivot et l'axe du vilebrequin d'orientation sont parallèles à l'axe du vilebrequin principal ;
• les déplacements de chaque pivot sont réalisé selon des plans perpendiculaires à l'axe du vilebrequin principal ;
• la longueur de levier de chaque maneton du vilebrequin d'orientation est égale à la longueur de levier du maneton correspondant appartenant au vilebrequin principal ;
• le vilebrequin d'orientation est lié en rotation au vilebrequin principal de sorte que les leviers de maneton de ces deux vilebrequins soient toujours parallèles.

According to a third list of complementary features of the device according to the invention, for each eccentric placed between a small end and the corresponding pin of the main crankshaft, the rod is integral with the eccentric and a part articulated by the axis of the pivot. The pivot is fixed on the articulated arms of a pendulum. The assembly formed by all the pivots and all articulated arms of the rockers which guide the integral rods eccentric placed between the connecting rods and the corresponding crank pin of the main crankshaft are arranged to form a crankshaft orientation. Each pivot which articulates the direction of a rod integral with an eccentric forms a crankpin of the crankshaft orientation and each corresponding articulated arm balance forms a lever connecting the crankpin to the corresponding journal of the crankshaft orientation .. The crankshaft orientation is guided and guided by a guidance system. This guidance system comprises a frame articulated on a fixed axis relative to the housing and controlled in position. The fixed parts of the bearings of the crankshaft orientation are integral with this articulated frame. The guide system and the orientation crankshaft are constructed to respect, during operation, geometric characteristics within tolerances compatible with the possibilities of realization as well as with the proper functioning of the device and the engine. These geometric characteristics are as follows:

• the axis of articulation of the chassis is merged with the axis of the main crankshaft;
• each pivot and the axis of the crankshaft orientation are parallel to the axis of the main crankshaft;
• the movements of each pivot are made in planes perpendicular to the axis of the main crankshaft;
• the lever length of each crankpin of the steering crankshaft is equal to the lever length of the corresponding crank pin belonging to the main crankshaft;
• the steering crankshaft is rotatably connected to the main crankshaft so that the crankpin levers of these two crankshafts are always parallel.

According to a variant of the construction of the device according to the invention. each eccentric placed between a small end and the corresponding pin of the main crankshaft is oriented by means of a rod whose direction is articulated on a patella. The other aforementioned features are unchanged.

The device according to the invention or its variant of construction described in preceding paragraph, associated with any of the three lists of characteristics the above-mentioned additional requirements complies with all the requirements of the the invention. Indeed, the guide system, the pivot or the ball, the slider or the pendulum, defined above, comply with the characteristics described in preceded according to the invention for the moving point, the point of articulation, the plane of the moving point and the projection plane. The pivot or the patella forms a point articulation, its movements and movements of the slide or each articulated pendulum arm form planes perpendicular to the axis of the main crankshaft; these plans correspond to the definition of the projection plan and the plane of the moving point. Several points of the slide and the pendulum correspond to the definition of the moving point. The projection of the direction of the stem on the plane of projection corresponds to the definition of the articulated axis. The displacement of any point of the eccentric during the rotation of the Main crankshaft defines a plane that corresponds to the definition of the lever plane. The projection of the direction of the rod on the plane of the lever corresponds to the definition of the axis fixed to the eccentric.

According to a fourth list of additional characteristics of the invention, the engine comprises an electronic computer. The position of slide or articulated arms, for each eccentric placed between a foot of connecting rod and the corresponding crankpin of the main crankshaft, is calculated by the electronic calculator, taking into account in particular the possibilities defined by the mechanical construction of the engine. The fourth list of characteristics described in this paragraph can complete the device according to the invention or its variant of construction, alone or associated with any of the other three lists of complementary features mentioned above.

According to another characteristic, an actuator uses a part of the enthalpy of the exhaust gases to help change the rate of compression.

According to another characteristic, the device according to the invention, in one any of the versions described above, incorporates the characteristic described in previous paragraph.

The use of a part of the enthalpy of the exhaust gas presents the advantage of being able to reduce the energy loss through the muffler, to operate the compression ratio modifier device so improve energy efficiency.

According to another characteristic, at least one turbine powered by gases exhaust is used to change the compression ratio of the engine.

According to another characteristic, the device according to the invention, in one any of the versions described above, incorporates the characteristic described in previous paragraph.

According to another characteristic a hydraulic actuator allows to actuate the device for modifying the compression ratio.

According to another characteristic, a gas cylinder acts on an overpressure jack to provide hydraulic pressure to change the compression ratio of the engine. This design offers a greater choice for placing the gas actuator.

According to another characteristic of the invention, the eccentric placed between the connecting rods and the main crankshaft crank pins are integral with one or several fingers and this or these fingers are all oriented towards a half-space defined by a plane integral with the eccentric, this plane containing the axis of the crankpin.

This design minimizes weight and bulk.

According to another characteristic of the invention, two eccentrics are secured, with an angular offset, so that the axes of their diameter interior are confused.

This design allows you to change the compression ratio of two cylinders coupled on the same crankpin main crankshaft.

Brief description of the drawings

• La figure 1 est un schéma qui illustre les caractéristiques du procédé selon l'invention.
• La figure 2 représente deux vues schématiques en coupes transversales d'un moteur à cylindres disposés en ligne dont le mécanisme de modification du taux de compression comporte une tige solidaire de l'excentrique qui coulisse par rapport à un coulisseau ;
• La figure 3 représente deux vues schématiques en coupes transversales d'un moteur à cylindres disposés en ligne dont le mécanisme de modification du taux de compression comporte une tige solidaire de l'excentrique qui coulisse par rapport à un balancier ;
• La figure 4 représente deux vues schématiques en coupes transversales d'un moteur à cylindres disposés en ligne dont le mécanisme de modification du taux de compression comporte une tige solidaire de l'excentrique qui coulisse par rapport à un vilebrequin d'orientation ;
• Le figure 5 représente un dispositif qui permet de modifier le calage du vilebrequin d'orientation représenté à la figue 3
• La figure 6 représente deux vues schématiques en coupes transversales d'un moteur à cylindres disposés en ligne dont le mécanisme de modification du taux de compression comporte une tige solidaire de l'excentrique et d'une pièce guidée sur le maneton d'un vilebrequin d'orientation ;
• La figure 7 représente deux vues schématiques en coupes transversales d'un moteur à cylindres disposés en ligne dont le mécanisme de modification du taux de compression comporte une tige qui coulisse par rapport à l'excentrique et qui est solidaire d'une pièce guidée par le pivot ;
• La figure 8 représente une vue schématique en coupe transversale d'un moteur à cylindres disposés en V dont le mécanisme de modification du taux de compression comporte une tige solidaire de l'excentrique qui coulisse par rapport à un balancier ;
• La figure 9 représente une vue schématique en coupe transversale d'un moteur à cylindres opposés dont le mécanisme de modification du taux de compression comporte une tige solidaire de l'excentrique qui coulisse par rapport à un coulisseau ;
• La figure 10 représente un vérin à gaz qui actionne un vérin sur-presseur
• La figure 11 à 14 représentent plusieurs variantes de construction de deux excentriques accolés comportant un ou plusieurs doigts situés dans un demi-plan passant par son axe.

The invention will be better understood on reading the following detailed description of certain preferred embodiments given solely by way of purely illustrative examples. In this description, reference is made to the accompanying drawings in which:

• Figure 1 is a diagram that illustrates the characteristics of the method according to the invention.
• FIG. 2 represents two schematic cross-sectional views of an in-line cylinder engine whose mechanism for modifying the compression ratio comprises a rod integral with the eccentric which slides relative to a slide;
• FIG. 3 represents two schematic cross-sectional views of an in-line cylinder engine whose mechanism for modifying the compression ratio comprises a rod integral with the eccentric which slides relative to a rocker;
• FIG. 4 represents two schematic cross-sectional views of an in-line cylinder engine whose mechanism for modifying the compression ratio comprises a rod integral with the eccentric which slides relative to an orientation crankshaft;
• FIG. 5 represents a device that makes it possible to modify the timing of the orientation crankshaft shown in FIG. 3
• FIG. 6 represents two schematic cross-sectional views of an in-line cylinder engine whose mechanism for modifying the compression ratio comprises a rod integral with the eccentric and a part guided on the crankpin of a crankshaft of FIG. orientation;
• FIG. 7 represents two schematic cross-sectional views of an in-line cylinder engine whose mechanism for modifying the compression ratio comprises a rod which slides relative to the eccentric and which is integral with a part guided by the pivot;
• FIG. 8 represents a diagrammatic cross-sectional view of a V-shaped cylinder engine whose mechanism for modifying the compression ratio comprises a rod integral with the eccentric which slides relative to a rocker;
• FIG. 9 is a diagrammatic cross-sectional view of an engine with opposed cylinders whose mechanism for modifying the compression ratio comprises a rod integral with the eccentric that slides relative to a slide;
• FIG. 10 represents a gas cylinder that actuates a super-pressurized cylinder
• Figures 11 to 14 show several construction variants of two eccentric contiguous having one or more fingers located in a half-plane passing through its axis.

Ways to realize the invention

FIG. 1 represents the foot of a connecting rod (6) in which there is a eccentric (8) mounted on a crankpin (5) of the main crankshaft (4) of an engine reciprocating piston. The arms (3) of the main crankshaft (4) connect the crank pin (5) to trunnion (2). The other elements of Figure 1 are constructed following the prescriptions of the method according to the invention. Plans (7), (9) and (10) are positioned perpendicular to the axis (1) of the main crankshaft (4); they did not no possibility of translation relative to the axis (1) of the main crankshaft (4); they respectively represent the lever plane (7), the projection plane (9) and the plane of the moving point (10). Point (12) is placed in the plane of the moving point (10); this point represents the moving point (12). The projection of the moving point (12) in a direction (13) on the projection plane (9) defines the point (14); this point represents the point of articulation (14). The geometric axis (15) is contained in the projection plane (9) at a fixed distance from the point of articulation (14) represented by the line (11); the geometric axis (15) is articulated around the hinge point (14); this geometric axis (15) represents the articulated axis (15). The geometric axis (16) is contained in the lever plane (7); he is parallel to the articulated axis (15) and fixed to the eccentric (8). The geometric axis (16) represents the axis attached to the eccentric (16); its distance from the articulated axis (15) must remain constant during operation. The geometric characteristics described in this paragraph are maintained during operation according to the with deviations within tolerances compatible with the good operation according to the method and the possibilities of realization.

During operation, when the moving point (12) is moved into a direction distinct from the direction of the articulated axis (15), its displacement performs in the plane of the movable point (10) and causes the articulation point (14) in the projection plane (9). This displacement of the articulation point (14) moves the axis articulated (15) according to a radial component to itself; the articulated axis (15) remains parallel and at a constant distance from the axis fixed to the eccentric (16). The articulated axis (15) and the axis fixed to the eccentric (16) thus pivot around the point of articulation (14) and around the crankpin (5) of the main crankshaft (4). As a result, movement of the movable point (12) in a direction distinct from the direction of the articulated axis (15) causes a modification of the angular setting of the eccentric (8).

At two distinct positions of the moving point (12), the direction between these two positions not being parallel to the direction of the articulated axis (15) and the axis the eccentric (16) corresponds to two different compression ratios of the chamber corresponding combustion, except for the particular case where these two positions do not change the distance between the axis (1) of the main crankshaft (4) and the axis of the foot connecting rod (6).

The motor (20) in which the method and the device operate comprises at least one yoke (21), (21a), (21b), a combustion chamber, a main crankshaft (4), a housing (24) which solidarises the chamber or chambers of combustion at the fixed part of the bearings (51) of the main crankshaft (4). The device according to the invention makes it possible to modify the compression ratio of each combustion chamber which comprises a piston (22), (22a), a jacket (23), (23a), (23b), a connecting rod (6), (6a), (6b), an eccentric (8), (8a), (8b) fixed between the crankpin (5) of the main crankshaft (4) and the foot of the ball (6), (6a), (6b).

The preferred way of carrying out the invention is shown in the figures 8, 11 and 14. The device for modifying the compression ratio makes it possible to orient each eccentric (8), (8a), (8b) placed between the foot of a connecting rod (6), (6a), (6b) and the crankpin (5) corresponding to the main crankshaft (4) of the engine (20) using a rod (35) whose direction is articulated on a pivot (29). The rod (35) is integral with the eccentric (8), (8a), (8b), a cheek (50) and a finger (90); this finger (90) is oriented towards a half-space defined by a plane (110) integral with the eccentric (8), (8a), (8b), this plane containing the axis of the crankpin (5) of the crankshaft principal (4). The rod (35) slides in the articulated part (30) fixed to the pivot (29). The pivot (29), represented by a dashed circle in FIG. 8, is hinged in the articulated arms of a pendulum (39). The balance guide system (39) comprises the pivot axis (38) represented by a dashed circle on the 8. The balance (39) pivots during operation around this axis of pivoting (38). The position of the pivot axis (38) allows operation without interference with the moving motor unit (20). The whole is built to respect during the operation of geometric characteristics within tolerances compatible with the possibilities of realization as well only with the proper functioning of the device and the motor. These features the following are the following: the axis of the sliding part of the rod (35) is in a lever plane (7) perpendicular to the axis (1) of the main crankshaft (4), the movements of the pivot (29) and the articulated arms of the balance (39) are realized in projection planes (9) and movable point planes (10) perpendicular to the axis (1) of the main crankshaft (4), the axis of the pivot (29) is parallel to the axis (1) of the main crankshaft (4). The articulated arms of the balance (39) are slaved into position thanks to the device described below. A gear is attached to one of the arms articulated beam (39). The other articulated arms of the balance (39) are secured in rotation to this gear by the sleepers (31). The aforementioned gear meshes the screw (32). The screw (32) is guided in rotation in the housing (24) and coupled in rotation to two turbines (26) and (81) via two speed reducers (27) and (80). The mounting directions of the two turbines (26) and (81) are made so that one of the two turbines (26) provides the screw (32) with a torque in the opposite direction to the torque provided by the other turbine (81). These two turbines (26) and (81) are fed by the exhaust gases of the motor (20) through pipelines and slave valves, not shown. These valves are controlled by a motor calculator (20) in order to converge the compression ratio of the engine (20) to the values calculated by this calculator.

Figure 8 shows the preferred way to realize the applied invention. to a motor whose cylinders are arranged in V. This preferred way for realize the invention also applies to engines whose cylinders are arranged in line, in opposition, or in several V. Figure 3 shows, for an in-line engine, an eccentric orientation device (8) comprising a rod integral with the eccentric (8) articulated on the pivot (29), this pivot (29) being articulated on the articulated arms of a pendulum (39). The mobile crew is balanced by the balancing masses (25).

Another way of guiding each pivot (29) in accordance with the method, consists either in articulating each pivot (29) in a slide (28), or in fasten each pivot (29) in a slider (28). The guidance system of each slider (28) comprises for example a rectilinear guide (33) whose direction of guidance is contained in projection planes (9) and movable point planes (10) perpendicular to the axis (1) of the main crankshaft (4). This other way for guiding the pivot (29) is illustrated in Figures 2 and 9. Figure 9 relates to an engine with opposed cylinders. The rod (35) is integral with the eccentric (8a) and articulated on the ball (91). The ball (91) is guided in the slide (28).

A way of limiting the number of actuators of a motor (20) equipped with several cylinders and a device for modifying the compression ratio with several slides (28), consists in linking the slides (28) to each other by means of sleepers (31). Two slides (28) are each driven by a screw (32). The two screws (32) are connected by a kinematic chain in order to obtain displacements identical for all slides (28).

Another way of orienting the eccentric (8), (8a), (8b) with the rod (35) is to slide the rod (35) into the bore of an orientation piece angular (70) integral with the eccentric (8), (8a), (8b) and to fix the rod (35) to a articulated piece (61) which pivots on the axis of the pivot (29) during operation. Figure 7 illustrates this construction.

Another way to realize the invention is shown in FIG. For each eccentric (8), (8a), (8b) placed between a small end (6) and the crankpin (5) corresponding to the main crankshaft (4), the rod (35) is integral with the eccentric (8) and an articulated part (61) guided in rotation on the axis of the pivot (29a), (29b), (29c). The pivots (29a), (29b), (29c) constitute crank pins of a crankshaft orientation. This orientation crankshaft is formed of pivots (29a), (29b), (29c), the levers (41) connecting the pivots (29a), (29b), (29c) to the trunnions (42) corresponding of this crankshaft orientation. The crankshaft orientation is guided and oriented by a guiding system which comprises an articulated frame (60) around an axis coincident with the axis of the main crankshaft (4). The levels of crankshaft orientation are attached to the frame (60). The guidance system and the crankshaft orientation are built to respect, during operation, geometric characteristics within tolerances compatible with the possibilities of realization as well as with the good functioning of the device and of the motor. These geometric characteristics are as follows: of each pivot (29a), (29b), (29c) are made in the projection plane (9) perpendicular to the axis (1) of the main crankshaft (4), each pivot (29a), (29b), (29c) and the axis of the crankshaft of orientation are parallel to the axis (1) of the crankshaft the main axis (4), the axis of articulation of the chassis coincides with the axis (1) of the main crankshaft (4), the length of the levers (41) of each crankpin crankshaft which constitutes the pivots (29a), (29b), (29c) is equal to the length of the levers (3) of the corresponding crankpin (5) belonging to the crankshaft the main crankshaft (4) is rotatably connected to the main crankshaft (4) so that the levers (41) and (3) of the crank pins of these two crankshafts corresponding to the same combustion chamber are always parallel, this This feature is achieved by the fact that the main crankshaft (4) and the steering crankshaft each have three levers (41) and (3) offset from each other. one hundred and twenty degrees. The three pivots (29a), (29b), (29c) are partially represented in Figure 6.

For all ways of guiding the pivot (29), (29a), (29b), (29c) described above, either the slide (28), the arm-joints of the balance (39), or the frame (60) can be driven by a screw (32) coupled to a single turbine (26) via a speed reducer (27) and a brake (34) driven by the engine calculator. The pitch of the screw (32) is such that the mechanical drive is reversible. The direction of assembly of the turbine (26) makes it possible to increase the rate compression. The thrusts of the connecting rods on the eccentric motorize the decrease in the compression ratio. The brake (34) controls the direction of change the compression ratio or stop this change. The The construction described in this section is illustrated in Figures 2, 3, 6 and 7.

The mechanism for modifying the compression ratio represented on the Figure 9 is driven by a hydraulic cylinder (93). This hydraulic cylinder is fed by the pipes (55) and (56). It is linked to the slide (28) by via the rod (92).

Figures 4 and 5 show another way to realize the invention. For each eccentric (8), (8a), (8b) placed between a small end (6) and the crankpin (5) corresponding to the main crankshaft (4), the rod (35) is integral with the eccentric (8) and slides in the articulated part (30) guided on the pivot (29). The pivots (29) constitute crank pins of a crankshaft orientation. This steering crankshaft is formed of pivots (29), levers (41) connecting the pivots (29) corresponding to the trunnions (42) of this orientation crankshaft. This steering crankshaft is guided in bearings (43) whose fixed parts are integral with the housing (24). This orientation crankshaft is linked in rotation to main crankshaft (4) with a toothed belt, not shown, and two pulleys (53) and (57) of the same diameter and having the same number of teeth. The angular setting of the crankshaft orientation relative to the main crankshaft (4) can be modified during operation by means of the variable setting device (54). The variable setting device (54) is hydraulically actuated; he is supplied with hydraulic fluid via the lines (55) and (56).

The hydraulic cylinder (93) or the variable setting device (54) can be powered by a hydraulic pump, not shown in the figures.

Another way to supply liquid under pressure to the jack hydraulic valve (93) or the variable setting device (54) is shown in FIG. 10. A gas cylinder (103) actuates an overpressure cylinder (106). Pipelines (100a), (100b) of the chambers (102a), (102b) of the gas cylinder (103) are controlled by valves (101a), (101b) and supplied with exhaust gas. The outlet pipes (105a), (105b) are controlled by valves (104a), (104b) and connected to the open air. Each of the two chambers (107a), (107b) of the overpressure ram (106) is connected to a hydraulic supply line (55) or (56) of the hydraulic cylinder (93) or the variable setting device (54), by via two parallel branches, one of which is equipped with a valve (108c), (108b) and the other of a valve (108a), (108d) and a non-return valve (109a), (109b). This non-return valve (109a), (109b) stops the flow of liquid hydraulic in the corresponding branch to the presser cylinder (106). So, if one of the two valves (108c) or (108b) which is not in series with a non-return valve (109a), (109b) is closed, while the other three hydraulic valves are open, the only possible displacement of the piston of the presser is the displacement which decreases the volume of the chamber (107a), (107b) connected to the closed valve (108c) or (108b). This arrangement thus makes it possible at the same time to easily control the meaning of change the compression ratio and use the exhaust gas.

According to another characteristic, the two chambers (107a), (107b) of the presser (106) are also connected to a hydraulic reserve via two check valves (109c), (109d). The mounting direction of these two flaps anti-return device (109c), (109d) allows only the passage of the liquid from the hydraulic reserve to the presser (106). This assembly makes it possible to fill the overpressure in case of leakage, within the limit of the capacity of the oil reserve.

According to a variant of the construction of the assembly consisting of the gas cylinder (103) and the overpressure cylinder (106), the outlet pipes (105a), (105b) of the gas cylinder (103) are connected to the suction of the engine (20). This variant is not shown in the figures.

The eccentrics (8), (8a), (8b) are formed of two half-shells (121) and (122). This construction shown in Figures 11 to 14 facilitates assembly.

Figures 11 to 12 show the rigid connection between the rod (35) and the eccentric (8), (8a), (8b). This rigid connection between the rod (35) and the eccentric (8), (8a), (8b) comprises a plate (52), one or more fingers (90) and one or several cheeks (50). The plate (52) forms the interface between the rod (35) and the fingers (90). The finger or fingers (90) are extended by the cheeks (50). When these parts are assembled on the motor (20), the finger or fingers (90) are outside the size of the connecting rod cap and connects the plate (52), while the cheeks (50) are integrated partially or totally in the thickness of the foot of the connecting rod 6 or the connecting rod cap 6 and connects the eccentrics (8), (8a), (8b).

According to the preferred manner of fixing the rod (35) to the eccentric (8), (8a), (8b), the finger or fingers (90) integral with the cheeks (50) are all oriented towards a half-space defined by a plane (110) integral with the eccentric (8), (8a), (8b), this plane containing the axis (120) of the inside diameter of the eccentric (8), (8a), (8b). This half space is symbolized in Figure 11 by the rectangle (111). The axis (120) of the inside diameter of the eccentric (8), (8a), (8b) coincides with the axis of the crankpin (5) of the main crankshaft (4) when these parts are assembled on the motor (20)

Figures 12 to 14 show several ways of building the link between two eccentrics (8a), (8b) contiguous and the rod (35). In Figure (12), the cheeks (50) separate the two eccentrics (8a), (8b). In FIGS. 13 and 14, two cheeks (50) are fixed releasably on the half shell (122) the most close to the rod (35). The two cheeks (50) are placed on either side of the set formed of two eccentric (8a), (8b) contiguous. The half shell (121) is fixed to the half-shell (122) by fixing screws (130).

Possibilities of industrial application

This invention can be applied to engines and reciprocating compressors crankshaft-powered alternators, including combustion chambers or compression chambers are arranged either in line, in opposition, or in V, either according to a plurality of V.

Claims (12)

1. Device for modifying the compression ratio of an internal combustion engine comprising at least one combustion chamber bounded by a cylinder head (21, 21a, 21b), a cylinder (23, 23a, 23b) and a reciprocating piston (22, 22a, 22b), said piston being connected to a connecting rod (6, 6a, 6b) connected to a crankshaft (4) carrying an eccentric (8, 8a, 8b) interposed between the big end of said connecting rod and the crank pin (5) of said crankshaft, said eccentric being connected in rotation to one end of a rod (35) which can be displaced angularly and is connected to a part (30), characterised in that the part (30) pivots on a pin (29) carried by displacement means (28; 39; 41; 42) allowing the angular adjustment of said eccentric to be changed.
2. Device according to claim 1, characterised in that the part (30) comprises sliding means for the rod (35).
3. Device according to claim 1, characterised in that the displacement means comprise a slide (28).
4. Device according to claim 1, characterised in that the displacement means comprise a rocker (39).
5. Device according to claim 1, characterised in that the displacement means comprise a orientating crankshaft (41, 42).
6. Device according to any one of claims 1 to 5, characterised in that it comprises at least one actuator (26, 54, 81, 93, 103, 106) for the displacement means (28; 39; 41; 42).
7. Device according to claim 6, characterised in that the actuator is a turbine (26, 81) fed by exhaust gases from the engine.
8. Device according to claim 6, characterised in that the actuator is a hydraulic jack (93, 106).
9. Device according to claim 8, characterised in that a gas jack (103) acts on the hydraulic jack (106).
10. Device according to claim 6, characterised in that the actuator is a variable adjusting device (54).
11. Device according to one of claims 6 or 7, characterised in that the actuator (26, 81) operates a screw (32) connected to the displacement means (28, 39).
12. Device according to claim 1, characterised in that the eccentric (8) comprises two eccentrics (8a, 8b) locked one to the other with an angular offset and connected in rotation to the same rod (35).

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