EP1238189A1

EP1238189A1 - Method and device for modifying compression rate to optimize operating conditions of reciprocating piston engines

Info

Publication number: EP1238189A1
Application number: EP00985347A
Authority: EP
Inventors: Michel Marchisseau
Original assignee: Individual
Current assignee: Marchisseau Michel; IFP Energies Nouvelles IFPEN
Priority date: 1999-11-30
Filing date: 2000-11-28
Publication date: 2002-09-11
Anticipated expiration: 2020-11-28
Also published as: KR100720327B1; JP2003515696A; DE60017940T2; ES2237479T3; WO2001040641A9; DE60017940D1; EP1238189B1; US6789515B1; KR20020081217A; AU2179601A; JP4505170B2; WO2001040641A1

Abstract

The invention concerns the modification of compression rate by using technological components similar to conventional components of engines. The turbines (26) and (81) mounted to operate in opposite direction drive a screw (32) and displace the pivot (29) which articulates the rod (35) integral with an eccentric (8a) located between the rod small end (6a) and the crankpin (5). The invention is particularly designed to increase power performance and reduce polluting waste in engines.

Description

Method and device for modifying the compression ratio in order to optimize the operation of reciprocating piston engines.

Technical area

The present invention relates to a method and a device, reactive and consuming very little energy, for continuously optimizing the compression ratio, in particular of reciprocating piston engines. This invention is especially relevant for improving the energy efficiency of engines which are not used continuously at their maximum load or which use multiple fuels of different octane numbers. This invention is compatible with a very low level of pollution and is suitable in particular for reciprocating piston engines whose cylinders are arranged either flat, or in N, or in line. In this document, the designation noted “compression ratio” designates the geometric compression ratio of an internal combustion engine with reciprocating pistons.

Prior art

Continuous optimization of the compression ratio is relevant for reducing fuel consumption and contributing to the greenhouse effect for areas of use where engines are not fully loaded and for engines that use multiple fuels d 'different octane numbers.

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

Continuous optimization of the compression ratio is relevant for keeping an engine in compression ignition mode of a premix of oxidizer and fuel. Such a mode of operation, described in particular in WO 99 42718 A, allows to achieve a very low ^emission level ^of nitrogen oxides. Furthermore, the optimization of the compression ratio is compatible with the usual systems for reducing nitrogen oxide emissions such as exhaust gas recycling systems (EGR) or catalysts for nitrogen oxides.

Various solutions for modifying the compression ratio of reciprocating piston engines are part of the prior art. A summary is set out below.

A known solution for varying the compression ratio consists in placing a moving part in the cylinder head. Patent WO 99 13206 A describes an example. The sliding of this part must be ensured in the presence of gases during combustion. The interstices must be reduced to a minimum to limit unburnt. The moving part takes place with the valves in the cylinder head and participates in the shape of the combustion chamber. US patent A 2,770,224 mentions an engine, the block of which is divided into two articulated parts makes it possible to vary the distance between each piston and the corresponding cylinder head. WO 93 23664 A discloses a solution for controlling this type of device. The effort to separate the two parts of the engine block is used to reduce the compression ratio and to store energy. The stored energy is then used to increase the compression ratio when the engine load decreases. The operating hysteresis is limited by energy supplied by an actuator. The structure of the engine block is designed and dimensioned to ensure the mechanical strength of the connection between the two articulated parts of the engine block as well as to minimize vibrations.

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

One category of solutions consists in modifying the length of the connecting rod, for example by adding a joint which modifies the straightness of the connecting rod. Patents EP 0 520 637 A and DE 195 02 820 A can be classified in this category of solutions. The additional parts which transmit the forces between the pistons and the crankshaft crank pins must be designed and dimensioned accordingly to ensure the required reliability.

Another category of solutions, more particularly suited to in-line engines, includes eccentrics mounted on the crankshaft bearings in order to modify the distance between the crankshaft axis and the cylinder head. The 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 service life. Patent DE 297 19 343 U discloses a device for ensuring the alignment of the crankshaft with the transmission. A pinion mounted at the end of the crankshaft meshes an internal gear mounted on the flywheel. The teeth of these gears must resist the modes of rotary vibration of the crankshaft, ensuring the longevity and silence required for operation.

Patent WO 91 10051 A mentions an eccentric, placed between the foot of each connecting rod and the corresponding crankpin of the crankshaft, the angular setting of which is obtained by means of gears. These gears must be designed and produced to ensure the 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 relate to an eccentric, mounted either at the head or at the foot of each connecting rod, the angular position of which is actuated by hydraulic and stabilized by a removable finger. This finger must be designed and sized to ensure the required reliability and longevity. This device allows discreet adjustment of the compression ratio. Statement of the invention

The subject of the invention is a method and a device for continuously optimizing the compression ratio, within ranges determined by construction, in particular for cylinder engines either in line, V or flat. The invention has the advantage as regards the necessary technologies, of being compatible with current technologies used industrially for cylinder heads, engine blocks, crankshafts and their connections with transmissions. It also has the advantage as regards its implementation, of allowing the use of technologies similar to the technologies already mastered and made reliable on reciprocating piston engines. The particular embodiments according to the invention have other advantages mentioned in the following of this description.

The present invention applies to internal combustion engines with reciprocating pistons driven by a crankshaft. Each of these engines comprises one or a plurality of combustion chambers and a casing. The casing is defined for the present 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 crankshaft bearings. The axis of rotation of the crankshaft journals is called the crankshaft axis. These engines also include a

(or more) cylinder head (s) which is (are) either separate (s) or integral with the housing. Each piston is linked to a crankpin of the crankshaft in particular by a piston pin, a connecting rod and an eccentric. This eccentric is placed between the foot of the connecting rod and the crankpin of the crankshaft corresponding to the same combustion chamber. The modification of the angular setting of one of these eccentrics relative to the casing causes a variation in the compression ratio of the chamber corresponding combustion. For the description and the claims of the present invention, a piston is in top dead center for each complete revolution of the crankshaft, when the distance is minimum between this piston and the corresponding cylinder head.

The method according to the invention 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 proper functioning and the possibilities of realization: - move a point in a plane orthogonal to the axis of the crankshaft; 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 mentioned 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 crankshaft axis and maintain parallelism and a fixed distance between the two aforementioned geometric axes, so that their direction when the piston is in top dead center, and the direction of displacement of the point mentioned in the first paragraph are distinct; maintain a fixed relative position between the geometric axis object of the choice cited in the preceding paragraph, and the eccentric placed between the connecting rod end and the crankshaft crankpin. The vocabulary defined below will be used in the remainder of this description to designate the points, the planes and the geometric axes of the method according to the invention described in the preceding paragraph: the point which is moved in a plane orthogonal to the axis of the crankshaft will be called the moving point; - the plane orthogonal to the crankshaft in which the moving point moves 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 moving point which articulates the articulated axis, and wherein ^the articulated axis is maintained, will be called the projection plane; the projection of the moving point on the projection plane 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 fixed to the eccentric will be called the lever plane. For engines which have several combustion chambers, the method according to the invention is applied to each combustion chamber whose modification of the compression ratio is sought.

The method according to the invention will be better understood on reading the seven paragraphs written below. These seven paragraphs relate to the method according to the invention, for modifying the compression ratio of a single combustion chamber of the engine. The embodiments according to the invention relate to the exact geometric characteristics mentioned in the process. However, all designs are manufactured with deviations from the exact target values. These possible deviations from the exact geometric characteristics are within tolerances compatible with the possibilities of embodiments according to the method and allow the engine to function properly.

The plane of the moving point, the projection plane and the lever plane are defined relative to the axis of the crankshaft. However, the crankshaft and its axis have no possibility of axial translation relative to the casing. The plane of the moving point, the projection plane and the lever plane therefore always have the same relative positions relative to the housing. The displacements of the articulated axis, of the axis fixed to the eccentric, of the movable point and of the articulation point are relative displacements relative to the casing. 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. Neither of these two axes changes plan during the process according to the invention. These characteristics have in particular the consequences, obtained in practice with possible deviations compatible with the proper functioning and the possibilities of realization, listed below: the articulated axis and the axis fixed to the eccentric have the same direction; any movement of the articulated axis is only possible in the projection plane; any movement of the axis fixed to the eccentric is only possible in the lever plane; any translation of the articulated axis with a component perpendicular to itself causes the axis fixed to the eccentric according to 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 articulated axis 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 about the axis of the corresponding crankpin of the 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, either the embodiment allows the translations cited in this paragraph, or the realization does not allow them. The method according to the invention is therefore compatible with devices for which the operation induces a variation in the distance between the point of articulation and the axis of the corresponding crankpin of the crankshaft. The method according to the invention is also compatible with devices which do not allow the distance between the articulation point and the axis of the corresponding crankpin of the crankshaft to be varied.

The angular setting of the eccentric on its crank pin is dependent on the angular setting of the axis fixed to the eccentric and of the articulated axis relative to the casing. A two distinct positions of the moving point in the plane of the moving point, the direction between the two distinct positions of the moving point is not parallel to the direction of ^the hinge axle and the shaft fixed to the eccentric when the piston is in top dead center, corresponds to two different angular settings of the articulated axis, of the axis fixed to the eccentric and the eccentric, with respect to the casing. These two angular settings correspond to two different compression ratios except for the special cases where these two angular settings correspond to the same distance between the axis of the crankshaft and the axis of the connecting rod. This paragraph lists several particular applications of the method according to the invention given by way of nonlimiting examples. For the first, the movable point and the articulation point are in the same plane perpendicular to the axis of the crankshaft. For the second, the mobile point is confused with the point of articulation. For these two particular applications, the plane of the mobile point is coincident with the projection plane. For the third, the articulated axis and the axis fixed to 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 combined. For these last two particular applications, the projection plane and the leverage plane are combined. All possible combinations of the aforementioned particular applications are applications of the method according to ^the invention.

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

According to another characteristic, the method according to the invention also applies to internal combustion thermal engines also comprising an electronic device for calculating optimal values for controlling the operation of these engines, sensors for measuring the values of physical quantities which characterize the operation of these motors, devices for adjusting commands for the operation of these motors to the values calculated by the calculation device mentioned above. This process comprises three phases carried out during the operation of the motors, the first phase consists in measuring the values of physical quantities which characterize the operation of these motors, these physical quantities comprising the compression ratio, the second phase consists in calculating, as a function of the physical quantities measured in the first phase, the optimal values of controlled parameters of the engine to maximize energy efficiency and minimize polluting emissions, these controlled parameters including the compression ratio, the third phase consists, for each cylinder, of performing the functions described below: move a point in a plane orthogonal to the axis of the crankshaft; 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 mentioned 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 parallelism and a fixed distance between the two aforementioned geometric axes, so that their direction when the piston is in top dead center, and the direction of displacement of the point mentioned in the first paragraph of this third phase, are distinct; maintain a fixed relative position between the geometric axis object of the choice mentioned in the preceding paragraph, and the eccentric placed between the connecting rod end and the crankpin of the crankshaft; - control the displacement of the point mentioned in the first paragraph of this third phase in order to make the compression ratio converge towards the optimal value calculated in the second phase.

For the other characteristic of the method described in the preceding paragraph, the compression ratio is measured by measuring a physical quantity which makes it possible to calculate this compression ratio, for example: the measurement of the displacement of the point of articulation. The other physical quantities measured according to this method form part of the physical quantities taken into account usually for the control of internal combustion engines with reciprocating pistons. The controlled parameters of the engine to maximize energy efficiency and minimize polluting emissions, other than the compression ratio, are part of the controlled parameters usually used for controlling internal combustion engines with reciprocating pistons.

According to another characteristic of the invention, the process described above is supplemented, on the one hand by the calculation in the second phase: of the quantities of air and fuel admitted for combustion as well as of the trigger angle combustion, as a function of the values of physical quantities which characterize the operation of the motors measured in the first phase, in particular the compression ratio, on the other hand by the control in the third phase of the devices for obtaining the quantity of intake air, quantity of fuel admitted, combustion initiation angle, in order to make the values of these three controlled parameters converge towards the values calculated in the second phase as a function in particular of the compression ratio.

The dosage of the quantity of air admitted for low loads presents several benefits. The temperature at the end of combustion can be lower and therefore promote mechanical longevity, energy efficiency and the fight against emissions of nitrogen oxides. It is also a relevant parameter for maintaining an engine in compression ignition mode of a pre-mixture of oxidizer and fuel. It should be noted that the intake of intake air obtained by adjusting the timing of the intake valves is relevant for limiting pressure losses on intake.

The device according to the invention, integrated into an internal combustion engine with reciprocating pistons driven by a main crankshaft comprising an eccentric placed between the foot of each connecting rod and the corresponding crankpin of the main crankshaft 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 complementary characteristics of the device according to the invention, for each eccentric placed between a connecting rod end and the corresponding crankpin of the main crankshaft, the rod is integral with the eccentric and part of this rod slides in an articulated part on the pivot axis. This pivot is fixed or articulated, either on a slide, or on the articulated arms of a pendulum. The slide or balance is guided by a guidance system and controlled in position. The assembly is constructed to respect, during operation, geometric characteristics included in tolerances compatible with the possibilities of realization as well as with the proper functioning of the device and the 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, of the slide or of the articulated arms are carried out 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 complementary characteristics of the device according to the invention, for each eccentric placed between a connecting rod end and the corresponding crankpin of the main crankshaft, part of the rod slides in a part integral with the eccentric. This sliding rod is also integral with a part articulated on the axis of the pivot. This pivot is fixed or articulated, either on a slide, or on the articulated arms of a pendulum. The slide or balance is guided by a guidance system and controlled in position. The assembly is constructed to respect, during operation, geometric characteristics included in tolerances compatible with the possibilities of realization as well as with the proper functioning of the device and the 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 displacements of the pivot, of the slide 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 main crankshaft.

According to a third list of complementary characteristics of the device according to the invention, for each eccentric placed between a connecting rod foot and the corresponding crankpin of the main crankshaft, the rod is integral with the eccentric and with 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 the articulated arms of the pendulums which make it possible to orient the rods integral with the eccentrics placed between the connecting rod ends and the corresponding crank pins of the main crankshaft are arranged to form an orientation crankshaft.

Each pivot which articulates the direction of a rod secured to an eccentric forms a crankpin of this orientation crankshaft and each articulated arm of the corresponding pendulum forms a lever connecting this crankpin to the corresponding journal of this orientation crankshaft. The crankshaft is guided and oriented by a guidance system. This guidance system comprises a frame articulated on an axis fixed relative to the casing and controlled in position. The fixed parts of the bearings of the orientation crankshaft are integral with this articulated frame. The guidance system and the orientation crankshaft are constructed to comply, during operation, with geometrical characteristics included within tolerances compatible with the possibilities of realization as well as with the proper functioning of the device and of the engine. These geometrical characteristics are as follows: the axis of articulation of the chassis coincides with the axis of the main crankshaft; - Each pivot and the axis of the orientation crankshaft are parallel to the axis of the main crankshaft; the displacements of each pivot are carried out along planes perpendicular to the axis of the main crankshaft; the length of the lever of each crankpin of the orientation crankshaft is equal to the length of the lever of the corresponding crankshaft belonging to the main crankshaft; - The orientation crankshaft is linked in rotation 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 connecting rod foot and the corresponding crankpin of the main crankshaft is oriented using a rod whose direction is articulated on a ball joint. The other characteristics mentioned above are unchanged. The device according to the invention or its construction variant described in the preceding paragraph, associated with any one of the three lists of additional characteristics mentioned above complies with all the requirements of the method according to the invention. Indeed, the guidance system, the pivot or the ball joint, the slide or the balance, defined above, conform to the characteristics described in the foregoing according to the invention for the movable point, the articulation point, the point plane mobile and the projection plane. The pivot or the ball joint forms a point of articulation, its displacements and the displacements of the slide or of each articulated arm of the pendulum form planes perpendicular to the axis of the main crankshaft; these planes correspond to the definition of the projection plane and the plane of the moving point. Several points of the slide and of the pendulum correspond to the definition of the mobile point. The projection of the rod direction onto the projection plane 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 which corresponds to the definition of the lever plane. The projection of the rod direction on the lever plane corresponds to the definition of the axis fixed to the eccentric.

According to a fourth list of complementary characteristics of the invention, the engine includes an electronic computer. The position of the slide or the articulated arms, for each eccentric placed between a connecting rod end and the corresponding crankpin of the main crankshaft, is calculated by the electronic computer, 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 construction variant, alone or associated with any one of the three other lists of complementary characteristics mentioned above.

According to another characteristic, an actuator uses a part of the exhaust gas fenthalpy to help modify the compression ratio. According to another characteristic, the device according to the invention, in any of the versions described above, incorporates the characteristic described in the preceding paragraph.

The use of a part of fenthalpy of the exhaust gases has the advantage of being able to reduce the loss of energy by the exhaust pipe, to actuate the device for modifying the compression ratio in order to improve the energy efficiency .

According to another characteristic, at least one turbine powered by exhaust gases is used to modify the compression ratio of the engine. According to another characteristic, the device according to the invention, in any of the versions described above, incorporates the characteristic described in the preceding paragraph.

According to another characteristic, a hydraulic actuator makes it possible to actuate the device for modifying the compression ratio.

According to another characteristic, a gas cylinder acts on a booster cylinder in order to provide hydraulic pressure to modify 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 eccentrics placed between the connecting rod ends and the crank pins of the main crankshaft are secured to one or more fingers and this or these fingers are all oriented towards a half-space defined by a plane secured to the eccentric, this plane containing the axis of the crank pin.

This design minimizes mass and size.

According to another characteristic of the invention, two eccentrics are joined, with an angular offset, so that the axes of their internal diameter are coincident.

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

Brief description of the drawings

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 appended drawings in which:

FIG. 1 is a diagram which illustrates the characteristics of the method according to the invention.

- Figure 2 shows two schematic cross-sectional views of a cylinder engine arranged in line, the compression ratio modification mechanism comprises a rod secured to the eccentric which slides relative to a slide; FIG. 3 represents two schematic cross-sectional views of a cylinder engine arranged in line, the compression ratio modification mechanism comprising a rod secured to the eccentric which slides relative to a balance;

- Figure 4 shows two schematic cross-sectional views of a cylinder engine arranged in line, the compression ratio modification mechanism comprises a rod integral with the eccentric which slides relative to a crankshaft ^of orientation;

- Figure 5 represents a device which makes it possible to modify the timing of the orientation crankshaft shown in fig 3

FIG. 6 represents two schematic views in transverse sections of a cylinder engine arranged in line, the compression ratio modification mechanism comprising a rod secured to the eccentric and a piece guided on the crankpin of a crankshaft d 'orientation;

FIG. 7 represents two schematic cross-sectional views of an engine with cylinders arranged in line, the compression ratio modification mechanism of which comprises a rod which slides relative to the eccentric and which is integral with a part guided by the pivot;

- Figure 8 shows a schematic cross-sectional view of an engine with cylinders arranged in a V, the compression ratio modification mechanism comprises a rod secured to the eccentric which slides relative to a balance; 9 shows a schematic view in cross section of an opposed engine having a modification mechanism of the compression ratio includes a rod integral with ^the eccentric which slides relative to a slider;

- Figure 11 to 14 show several construction variants of two contiguous eccentrics comprising one or more fingers located in a half-plane passing through its axis.

Ways to realize the invention

Figure 1 shows the foot of a connecting rod (6) in which is located an eccentric (8) mounted on a crankpin (5) of the main crankshaft (4) of a reciprocating piston engine. The lever arms (3) of the main crankshaft (4) connects the crankpin (5) to the journal (2). The other elements of FIG. 1 are constructed by following the prescriptions of the method according to the invention. The planes (7), (9) and (10) are positioned perpendicular to the axis (1) of the main crankshaft (4); they have no possibility of translation relative to the axis (1) of the main crankshaft (4); they respectively represent the lever plane (7), the articulation plane (9) and the plane of movement of the movable point (10). The point (12) is placed in the plane of the mobile point (10); this point represents the moving point (12). The projection of the movable point (12) in a direction (13) on the articulation plane (9) defines the point (14); this point represents the point of articulation (14). The geometric axis (15) is contained in the articulation plane (9) at a fixed distance from the articulation point (14) represented by the line (11); the geometric axis (15) is articulated around the point of articulation (14); this geometric axis (15) represents the articulated axis (15). The geometric axis (16) is contained in the lever plane (7); it is parallel to the articulated axis (15) and fixed to the eccentric (16). The geometric axis (16) represents ^the axis fixed to ^the eccentric (16); its distance from the articulated axis (15) must remain constant during operation. The geometrical characteristics described in this paragraph are maintained during the operation according to the method with deviations included in tolerances compatible with the correct operation according to the method and the possibilities of realization.

During operation, when the movable point (12) is moved in a direction distinct from the direction of the articulated axis (15), its displacement takes place in the plane of the movable point (10) and drives the articulation point (14) in the articulation plane (9). This displacement of the articulation point (14) displaces the articulated axis (15) according to a radial component to itself; the articulated axis (15) remains parallel and at constant distance from the axis fixed to the eccentric (8). The articulated axis (15) and the axis fixed to the eccentric (16) therefore pivot around the point of articulation (14) and around the crank pin (5) of the main crankshaft (4). Consequently, the displacement 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 movable point (12), the direction between these two positions not being parallel to the direction of the articulated axis (15) and of the axis fixed to the eccentric (16), corresponds to two rates different compression of the corresponding combustion chamber, except for the particular case where the two positions do not change the distance between ^the axis (1) of the main crankshaft (4) and the axis of the gudgeon (6).

The engine (20) in which the process and the device operate comprises at least one cylinder head (21), (21a), (21b), a combustion chamber, a main crankshaft (4), a casing (24) which secures the or the combustion chambers 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 ball foot (6), (6a), (6b ).

The preferred way of carrying out the invention is shown in FIGS. 8 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 main crankshaft (4). The rod (35) slides in the articulated part (30) fixed to the pivot (29). The pivot (29), represented by a circle in dotted lines in FIG. 8, is articulated in the articulated arms of a pendulum (39). The balance guide system (39) comprises the pivot axis (38) represented by a circle in dotted lines in FIG. 8. The balance (39) pivots during operation around this pivot axis (38). The position of the pivot axis (38) allows operation without interference with the mobile engine assembly (20). The assembly is constructed to respect, during operation, geometric characteristics included in tolerances compatible with the possibilities of realization as well as with the proper functioning of the device and the motor. These geometric characteristics are as follows: the axis of the sliding portion 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 articulated arms of the balance (39) are made in projection planes (9) and displacement planes of the movable point (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 wheel (39) are slaved in position using the device described below. A gear is fixed on one of the articulated arms of the balance (39). The other arms of the balance (39) are secured in rotation to this gear by the crosspieces (31). The aforementioned gear meshes with the screw (32). The screw (32) is guided in rotation in the casing (24) and coupled in rotation to two turbines (26) and (81) by means of 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) supplies the screw (32) with a torque in the opposite direction to the torque provided by the another turbine (81). These two turbines (26) and (81) are supplied by the exhaust gases from the engine (20) by means of pipes and slave valves, not shown. These valves are controlled by an engine computer (20) in order to make the engine compression ratio (20) converge towards the values calculated by this computer. FIG. 8 shows the preferred way to carry out the invention applied to an engine whose cylinders are arranged in V. This preferred way to carry out the invention also applies to engines whose cylinders are arranged either in line or in opposition , or in several V. Figure 3 presents, for an in-line motor, 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 lever arms d 'a pendulum (39). The moving part is balanced by the balancing weights (25). Another way of guiding each pivot (29) in accordance with the method, is either to articulate each pivot (29) in a slide (28), or to fix each pivot (29) in a slide (28). The guide system of each slide (28) comprises for example a rectilinear guide (33) whose guide direction is contained in projection planes (9) and planes of the mobile point (10) perpendicular to the axis (1 ) of the main crankshaft (4). This other way of carrying out the guiding of the pivot (29) is illustrated in FIGS. 2 and 9. FIG. 9 relates to an engine with opposite cylinders. The rod (35) is integral with the eccentric

(8a) and articulated on the ball joint (91). The ball joint (91) is guided in the slide (28).

One way of limiting the number of actuators of a motor (20) equipped with several cylinders (23) and of a device for modifying the compression ratio with several slides (28), consists in linking the slides (28) between them by crosspieces (31). Two slides (28) are each driven by a screw (32). The two screws (32) are linked by a kinematic chain in order to obtain identical displacements for all the slides (28). Another way of orienting the eccentric (8), (8a), (8b) with the rod (35) consists in sliding the rod (35) in the bore of an angular orientation part (70) integral with the eccentric (8), (8a), (8b) and to fix the rod (35) to an articulated part (61) which pivots on ^the pivot axis (29) during operation. Figure 7 illustrates this construction. Another way to realize ^the invention is shown in Figure 6.

For each eccentric (8), (8a), (8b) placed between a connecting rod 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 an orientation crankshaft. This orientation crankshaft is formed of pivots (29a), (29b), (29c), the levers (41) connecting the pivots (29a), (29b), (29c) to the pins (42) corresponding to this crankshaft d 'orientation. The orientation crankshaft is guided and oriented by a guide system which comprises a chassis (60) articulated around an axis coincident with the axis of the main crankshaft (4). The bearings of the orientation crankshaft are fixed to the chassis (60). The guidance system and the orientation crankshaft are constructed to respect, during operation, geometric characteristics included within tolerances compatible with the possibilities of realization as well as with the proper functioning of the device and of the motor. These geometric characteristics are as follows: the displacements of each pivot (29a), (29b), (29c) are produced in the plane (9) perpendicular to the axis (1) of the main crankshaft (4), each pivot (29a ), (29b). (29c) and the axis (1) of the orientation crankshaft are parallel to the axis (1) of the main crankshaft (4), the axis of articulation of the chassis coincides with the axis (1) of the crankshaft main (4), the length of the levers (41) of each crankpin of the orientation crankshaft which constitutes the pivots (29a), (29b), (29c) is equal to the length of the levers (3) of the crankpin (5) corresponding to the main crankshaft (4), the orientation crankshaft is linked in rotation 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 characteristic is obtained thanks to the fact that the main crankshaft (4) and the orientation crankshaft each have three levers (41) and (3) offset by one hundred and twenty degrees. The three pivots (29a), (29b), (29c) are partially represented in FIG. 6.

For all the ways of guiding the pivot (29), (29a), (29b), (29c) described above, either the slide (28), or the articulated arms of the pendulum (39), or the chassis (60 ) can be driven by a screw (32) coupled to a single turbine (26) via a speed reducer (27) and a brake (34) controlled by the engine computer. The pitch of the screw (32) is such that the mechanical drive is reversible. The mounting direction of the turbine (26) allows to ^increase the compression ratio. The thrusts of the connecting rods on the eccentrics motorize the reduction in the compression ratio. The brake (34) makes it possible to control the direction of modification of the compression ratio or to stop this modification. The construction described in this paragraph is illustrated in Figures 2, 3, 6 and 7.

The mechanism for changing the compression ratio shown in FIG. 9 is driven by a hydraulic cylinder (93). This hydraulic cylinder is supplied by the pipes (55) and (56). It is linked to the slide (28) via the rod (92). Figures 4 and 5 show another way to realize the invention.

For each eccentric (8), (8a), (8b) placed between a connecting rod 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 an orientation crankshaft. This orientation crankshaft is formed of pivots (29), levers (41) connecting the pins (29) with trunnions (42) corresponding to this crankshaft ^orientation. This orientation crankshaft is guided in bearings (43) whose fixed parts are integral with the casing (24). This orientation crankshaft is linked in rotation to the 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 orientation crankshaft relative to the main crankshaft (4) can be modified during operation by means of the variable timing device (54). The variable timing device (54) is hydraulically actuated; it is supplied with hydraulic fluid through the pipes (55) and (56).

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

Another way to supply pressurized liquid to the hydraulic cylinder (93) or the variable timing device (54) is shown in FIG. 10. A gas cylinder (103) actuates a booster cylinder (106). The inlet pipes (100a), (100b) of the chambers (102a), (102b) of the gas spring (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 free air. Each of the two chambers (107a), (107b) of the booster cylinder (106) is connected to a hydraulic pipe (55) or (56) supplying the hydraulic cylinder (93) or the variable timing device (54) , via two parallel branches, one of which is fitted with a valve (108c), (108b) and the other with a valve (108a), (108d) and a non-return valve ( 109a), (109b). This non-return valve (109a), (109b) stops the flow of hydraulic liquid in the corresponding branch to the overpressure cylinder (106). Thus, 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 movement possible of the piston of the booster is the displacement which decreases the volume of the chamber (107a), (107b) connected to the closed valve (108c) or (108b). This arrangement therefore makes it possible both to easily control the direction of modification of the compression ratio and to use the exhaust gases.

According to another characteristic, the two chambers (107a), (107b) of the booster (106) are also connected to a hydraulic reserve by means of two non-return valves (109c), (109d). The mounting direction of these two non-return valves (109c), (109d) only allows the passage of the liquid from the hydraulic reserve to the supercharger (106). This assembly allows the booster to be filled in the event of a leak, 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 motor suction (20). This variant is not shown in the figures.

The eccentrics (8), (8a), (8b) are formed by 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 more cheeks (50). The plate (52) forms the interface between the rod (35) and the finger (s) (90). The finger (s) (90) are extended by the cheeks (50). When these parts are assembled on the engine (20), the finger (s) (90) are outside the size of the connecting rod cap and connects the plate (52), while the cheek (s) (50) are partially integrated or completely in the thickness of the foot of the connecting rod 6 or of the cap of the connecting rod 6 and connects the eccentrics (8), (8a), (8b).

According to the preferred way 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 defined half-space by a plane (110) integral with the eccentric (8), (8a), (8b), this plane containing the axis (120) of the internal diameter of the eccentric (8), (8a), (8b) . This half-space is symbolized in FIG. 11 by the rectangle (111). The axis (120) of the internal diameter of the eccentric (8), (8a), (8b) coincides with the axis of the crank pin (5) of the main crankshaft (4) when these parts are assembled on the engine ( 20)

Figures 12 to 14 show several ways of constructing the connection between two eccentrics (8a), (8b) placed side by side 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 in a non-removable manner on the half-shell (122) closest to the rod (35). The two cheeks (50) are placed on either side of the assembly formed by the two eccentrics (8a), (8b) joined. The half shell (121) is fixed to the half shell (122) by fixing screws (130).

Industrial application possibilities

This invention can be applied to reciprocating piston engines and compressors driven by a crankshaft, the combustion chambers or compression chambers of which are arranged either in line, or in opposition, or in N, or according to a plurality of V.

Claims

1) Method applying to internal combustion thermal engines comprising one or more combustion chambers individually constituted in particular by: a cylinder head (21), (21a), (21b) clean or common to several combustion chambers, a jacket (23 ), (23a), (23b), a reciprocating piston (22), (22a), a connecting rod (6), (6a), (6b), a crankshaft (4), an eccentric (8), ( 8a), (8b) placed between the big end (6), (6a), (6b) and the crankpin (5) corresponding to the crankshaft (4), characterized in that this process 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 proper functioning and the possibilities of realization:

- move a point (12) in a plane (10) orthogonal to the axis (1) of the crankshaft (4);

- maintain a geometric axis (15) in a plane (9) orthogonal to the axis (1) of the crankshaft (4) and articulate this geometric axis (15) around the point of intersection (14) of the projection of the point ( 12) cited in the preceding paragraph with the plane (9) of rotation of this geometric axis (15); choose another geometric axis (16) contained in a plane (7) also orthogonal to the axis (1) of the crankshaft (4) and maintain the parallelism and a fixed distance between the two aforementioned geometric axes (15) and (16) , so that their direction when the piston (22), (22a) is in top dead center, and the direction of movement of the point (12) mentioned in the first paragraph are distinct;

- maintain a fixed relative position between the geometric axis (16) object of the choice mentioned in the preceding paragraph, and the eccentric (8) placed between the connecting rod end (6) and the crankpin (5) of the crankshaft (4 ).

2) Device integrated into an internal combustion engine (20) with reciprocating pistons (22), (22a) driven by a main crankshaft (4) comprising an eccentric (8), (8a), (8b) placed between the foot of each connecting rod (6), (6a), (6b) and the corresponding crankpin (5) of the main crankshaft (4) is characterized in that each eccentric (8), (8a), (8b) placed between the foot of each connecting rod (6), (6a), (6b) and the crankpin (5) corresponding to the main crankshaft (4) is oriented using a rod (35) whose direction is articulated on a pivot (29), (29a), (29b), (29c).

3) Device integrated into an internal combustion engine (20) with reciprocating pistons (22), (22a) driven by a main crankshaft (4) comprising an eccentric (8), (8a), (8b) placed between the foot of each connecting rod (6), (6a), (6b) and the crankpin (5) corresponding to the main crankshaft (4) characterized in that on the one hand each eccentric (8), (8a), (8b) placed between the foot of each connecting rod (6), (6a), (6b) and the crankpin ( 5) corresponding to the main crankshaft (4) is oriented using a rod (35) whose direction is articulated on a pivot (29), (29a), (29b), (29c), on the other hand the rod (35) is integral with the eccentric (8), (8a), (8b) and part of this rod (35) slides in an articulated part (30) on the axis of the pivot (29), ( 29a), (29b), (29c), this pivot (29), (29a), (29b), (29c) is fixed or articulated, either on a slide (28) or on the articulated arms of a pendulum (39), this slide (28) or these articulated arms of the balance (39) are guided by a guidance system and controlled in position, the assembly is constructed to respect, during operation, geometric characteristics included within compatible tolerances with the possibilities of realization as well as with the b is operation of the device and of the motor (20), the geometrical characteristics being such that the axis of the sliding portion of the rod (35) is in a plane (7) perpendicular to ^the axis (1) of the main crankshaft (4 ), the movements of the pivot (29), (29a). (29b), (29c), of the slide (28) or of the articulated arms are produced in planes (9) and (10) perpendicular to the axis (1) of the main crankshaft (4), the axis of the pivot ( 29), (29a), (29b), (29c) is parallel to the axis (1) of the main crankshaft (4).

4) Device integrated into an internal combustion engine (20) with reciprocating pistons (22), (22a) driven by a main crankshaft (4) comprising an eccentric (8), (8a), (8b) placed between the foot of each connecting rod (6), (6a), (6b) and the crankpin (5) corresponding to the main crankshaft (4) characterized in that on the one hand each eccentric (8), (8a), (8b) placed between the foot of each connecting rod (6), (6a), (6b) and the crankpin (5) corresponding to the main crankshaft (4) is oriented using a rod (35) whose direction is articulated on a pivot ( 29), (29a), (29b), (29c), on the other hand, part of the rod (35) slides in an angular orientation part (70) integral with the eccentric (8), (8a) , (8b), this sliding rod (35) is also integral with an articulated part (61) on the axis of the pivot (29), (29a), (29b), (29c), this pivot (29), ( 29a), (29b), (29c) is fixed or articulated, either on a slide (28), or on the articulated arms of a pendulum (39), this slide (28) or this pendulum (39) is guided by a guidance system and slaved in position, the assembly is constructed to respect, during operation, geometric characteristics included within tolerances compatible with the possibilities of realization as well as 'with the proper functioning of the device and the engine, these geometrical characteristics are such that the axis of the couhssante part of the rod (35) is in a plane (7) perpendicular to the axis (1) of the main crankshaft (4 ), the movements of the pivot (29), (29a), (29b), (29c), the ram (28) or articulated arms are in planes (9) and (10) perpendicular to ^the axis (1 ) of the crankshaft main (4), the axis of the pivot (29), (29a), (29b), (29c) is parallel to the axis (1) of the main crankshaft (4).

5) Device integrated into an internal combustion engine (20) with reciprocating pistons (22), (22a) driven by a main crankshaft (4) comprising an eccentric (8), (8a), (8b) placed between the foot of each connecting rod (6), (6a), (6b) and the crankpin (5) corresponding to the main crankshaft (4) characterized in that on the one hand each eccentric (8), (8a), (8b) placed between the foot of each connecting rod (6), (6a), (6b) and the crankpin (5) corresponding to the main crankshaft (4) is oriented using a rod (35) whose direction is articulated on a pivot ( 29), (29a), (29b), (29c), on the other hand the rod (35) is integral with the eccentric (8), (8a), (8b) and an articulated part (61) by the axis of the pivot (29), (29a), (29b), (29c), the pivot (29), (29a), (29b), (29c) is fixed on the articulated arms of a pendulum ( 39), these articulated arms are guided and controlled in position, the assembly formed by all the pivots (29), (29a), (29b), (29c) and all the articulated arms of the pendulums (39) which allow to orient the rods (35) integral with the eccentrics (8), (8a), (8b) placed between the connecting rod ends (6), (6a), (6b) and the corresponding crank pins (5) of the crankshaft main (4) are arranged to form an orientation crankshaft, each pivot (29), (29a), (29b), (29c) which articulates the direction of a rod (35) integral with an eccentric (8) , (8a), (8b) forms a crankpin of this orientation crankshaft and each articulated arm of the corresponding pendulum forms a lever (41) connecting this crankpin to the journal (42) corresponding to this orientation crankshaft, the crankshaft orientation is guided and oriented by a guidance system, this guidance system comprises a frame (60) articulated on a fixed axis relative to the casing (24), the fixed parts of the bearings (43) of the orientation crankshaft are integral with this chassis (60), the guidance system and the orientation crankshaft are constructed to respect, during operation, Geometric ics included in tolerances compatible with the possibilities of realization as well as with the good functioning of the device and the motor (20), these geometrical characteristics are the following: - the axis of articulation of the chassis (60) is confused with the axis (1) of the main crankshaft (4);

- Each pivot (29), (29a), (29b), (29c) and the axis of the orientation crankshaft are parallel to the axis (1) of the main crankshaft (4);

- The displacements of each pivot (29), (29a), (29b), (29c) are perpendicular to the axis (1) of the main crankshaft (4); the length of the lever (41) of each crankpin (40) of the orientation crankshaft is equal to the length of the lever (3) of the corresponding crankpin (5) belonging to the main crankshaft (4); the orientation crankshaft is linked in rotation to the main crankshaft (4) so that the levers (3) and 41) of crankpin (5) and (40) of these two crankshafts are always parallel.

6) Device according to any one of claims 2 to 5 characterized in that this device comprises an actuator (26), (81), (103) which uses part of the ^enthalpy of the exhaust gas to contribute to change the compression ratio of the engine (20).

7) Device according to any one of claims 2 to 5 characterized in that at least one turbine (26) supplied by exhaust gas allows to actuate the mechanism for modifying the compression ratio

8) Device according to any one of claims 2 to 5 characterized in that a gas cylinder (103) acts on a booster cylinder (106) to provide hydraulic pressure to act on the rate modification device compression. 9) Device according to any one of claims 2 to 5, the eccentrics (8), (8a), (8b) placed between the connecting rod ends (6) and the crank pins (5) of the main crankshaft (4) are integral one or more fingers (90) characterized in that the finger (s) (90) integral with each eccentric (8), (8a), (8b) placed between a connecting rod foot (6) and a crank pin (5) main crankshaft (4), are all oriented towards a half-space defined by a plane (110) integral with the eccentric (8), (8a), (8b), this plane (110) containing the axis of the crankpin (5).

10) Device according to any one of claims 2 to 5 characterized in that two eccentrics (8), (8a), (8b) are secured, with an angular offset, so that the axes (120) of their internal diameter are confused.