INTERNAL COMBUSTION ENGINE

Description

Field of the invention

[0001] The invention belongs to the field of motion transformation systems capable of generating a continuous circular motion from an alternating rectilinear motion, and relates more particularly to an engine, in particular of the so-called internal combustion type. State of the art

[0002] The transformation of a continuous circular movement from an alternating rectilinear movement is carried out by means of a so-called connecting rod-crank mechanism. This mechanism is generally implemented in internal combustion engines in order to deliver a torque capable of setting a vehicle in motion.

[0003] Typically, an internal combustion engine comprises a crankshaft provided with one or more crankpins, the or each crankpin forming a crank around which a connecting rod pivots by one of its ends, called connecting rod big end. The connecting rod, by its opposite end, called connecting rod small end, is fixed in an articulated manner to a piston fitted in sliding mode in a cylinder. The piston forms with the cylinder, a working chamber, inside the cylinder called "combustion chamber", in which is carried out a combustion of a mixture of gas, such as air, and fuel, such than a hydrocarbon. This combustion, causing the mixture to expand, generates a thrust force on the piston which transmits, via the connecting rod, part of this force to the crank pin of the crankshaft, in view of driving the crankshaft in rotation.

[0004] The operating cycle of an internal combustion engine includes an admission phase of a mixture of fresh gas and fuel, in the combustion chamber of the or each cylinder, followed by a phase of compression of this mixture by the or each piston, then respective combustion phases of the mixture, generating an increase in the pressure in the combustion chamber, and expansion of the burnt gases, and finally a burnt gas exhaust phase.

[0005] The stroke of the piston, in the cylinder, is limited by two extreme positions, respectively called top dead center, in which the volume of the combustion chamber is minimum, and bottom dead center, in which the volume of the combustion chamber is maximum. .

[0006] One of the disadvantages of internal combustion engines of the state of the art is their low efficiency. By efficiency, we mean the ratio between the mechanical power supplied by the crankshaft and the power supplied by the fuel necessary for the combustion of the mixture of gas and fuel.

[0007] The low efficiency of internal combustion engines of the state of the art is notably due to the friction generated by the numerous moving parts making up the kinematic chain of these engines.

[0008] This friction is partly generated by the stroke of the piston along the cylinder. Indeed, during the stroke of the piston, the connecting rod forms an angle with the axis of a generatrix of the cylinder, varying according to the angular position of the crankpin, we speak of the obliqueness of the connecting rod. This obliqueness reaches a maximum value when the piston is halfway between the top dead center and the bottom dead center. Due to the relatively high value of this angle, the piston generates transverse forces, that is to say perpendicular to the longitudinal axis of the cylinder, when it slides along the cylinder. Moreover, in addition to generating friction that can cause premature wear of moving parts, these forces can generate mechanical fatigue of the crankshaft, under the action of cyclic mechanical stresses, and therefore be the cause of a rupture. of the crankshaft.

[0009] The obliqueness of the connecting rod is also the cause of strong accelerations and decelerations of the piston during its travel between the top and bottom dead centers, and vice versa. These strong accelerations and decelerations generate so-called “second order” inertial forces. These second-order forces vary twice per revolution of the crankshaft and can be the cause of the appearance of significant internal mechanical stresses in the moving parts of the engine.

[0010] The low efficiency of internal combustion engines is also due to the fact that the combustion of the gas and fuel mixture is incomplete. Indeed, due to incomplete combustion, the power that the fuel can potentially provide in the combustion chamber is not fully exploited.

[0011] The fact that the combustion is incomplete is due in particular to the insufficient durations of the compression and combustion phases. Indeed, the piston does not remain long enough in the vicinity of top dead center so as to maintain the mixture at a high compression long enough to ensure substantially complete combustion. Indeed, due to the structure of the connecting rod-crank mechanism of the engines of the state of the art, the rotation of the connecting rod around the crank pin of the crankshaft subjects the piston to a strong linear acceleration immediately after having reached the top dead center.

[0012] As an example, when the piston is near top dead center, the piston is driven to compress the mixture between ninety and one hundred percent of the maximum pressure of the mixture during a rotation of five to ten degrees of the crankshaft. Maximum mixture pressure is reached when the piston is at top dead center.

[0013] The fact that the combustion is incomplete also generates an atmospheric pollution problem insofar as unburned gases are given off during the exhaust phase. These unburned gases are also harmful to human health.

[0014] Moreover, the pistons of the internal combustion engines of the state of the art are subjected to cycles of strong acceleration and deceleration. Due to this, the pistons generate inertial forces acting on the crankshaft cyclically. In addition to the mechanical fatigue undergone by these parts, these cyclic stresses generate vibrations which may be the cause of the breakage of parts.

[0015] Another drawback of the internal combustion engines of the state of the art resides in their high weight, due to the large number of parts that they comprise. This high weight has the effect, in particular, of requiring a high power to move the vehicle comprising the engine, and therefore of generating high fuel consumption. Furthermore, the fact that internal combustion engines have a high weight complicates maintenance operations.

[0016] WO 2014 / 011122 A1 discloses an internal combustion engine according to the preamble of claim 1 and forming part of the prior art. Disclosure of Invention

[0017] The present invention aims to overcome the aforementioned drawbacks by proposing an internal combustion engine, high efficiency, light and compact.

[0018] The present invention relates in particular, according to a first aspect, to an internal combustion engine comprising at least two cylinders with parallel longitudinal axes, each cylinder comprising an opening and a piston adapted to translate inside said cylinder, said respective openings of said cylinders facing each other, said pistons being in kinematic relationship with a connecting rod-crank mechanism comprising: a spacer connecting said pistons, adapted to maintain a fixed spacing between said pistons so that a translational movement of one piston causes the same translational movement for the other piston, said pistons being respectively fixed to arms of said spacer , a crankshaft movable in rotation around an axis, arranged between the openings of the cylinders and between the longitudinal axes of said cylinders, said crankshaft comprising a crankpin, a lifter movable in rotation around the crankpin, comprising two ends arranged on either side other of said crankpin, at least one connecting rod comprising a first end, called "foot", secured to the spacer, and a second end, called "head", secured to one of the ends of the spreader bar

[0019] By the term “solid” is meant “fixed mobile in rotation”.

[0020] Because of these characteristics, the translation guidance of a piston is achieved by the other piston. Therefore, the pistons are essentially subjected to axial forces, during the combustion of the mixture, and generate little or no transverse forces in the cylinders during their sliding. The friction generated by the sliding of the pistons in the cylinders is then negligible compared to the friction generated by the sliding of the pistons in the cylinders of the engines of the state of the art. Engine efficiency is substantially increased.

[0021] In addition, the crossbar is adapted to describe an alternating rotational movement around the crank pin during the translation of the pistons in the cylinders, so as to cause the head of the connecting rod or rods to describe a non-circular trajectory. Thus, the arrival and departure speed of each piston at the top dead center is relatively reduced compared to the engines of the state of the art, so that the time during which each piston evolves in the vicinity of the top dead center is relatively high compared to the engines of the state of the art. For example, when the piston is near top dead center, the piston is driven to compress the mixture between ninety and one hundred percent of the maximum pressure of the mixture during a rotation of approximately twenty five crankshaft degrees.

[0022] As a result, the piston maintains high pressure in the combustion chamber long enough for combustion to be substantially complete. Thus, the gases discharged no longer include (or include a negligible quantity) unburned gases, a source of atmospheric pollution and harmful to human health. For example, the combustion phase is carried out during a rotation of approximately one hundred and twenty degrees of the crankshaft.

[0023] The substantially complete combustion also generates a gain in engine efficiency, and therefore a reduction in fuel consumption. At equal power, the quantity of fuel necessary for the operation of the engine is less important for the internal combustion engine which is the subject of the invention than for an internal combustion engine of the state of the art. By way of example, at equal power and under the same operating conditions, the fuel consumption of the engine that is the subject of the invention is more than 60% lower than the fuel consumption of an engine of the state of the art. .

[0024] In particular embodiments, the invention also responds to the following characteristics, implemented separately or in each of their technically effective combinations.

[0025] In particular embodiments of the invention, the arms of the spacer are connected to a spacer body comprising an opening through which the crankshaft is capable of moving.

[0026] Thanks to these characteristics, the spacer is more rigid and is therefore more suitable for restoring the forces transmitted by the pistons during the combustion phase of the mixture. In addition, the spacer is more suitable for resisting the mechanical stresses resulting from these efforts.

[0027] The pins or the crank pin of the crankshaft are capable of moving through the opening of the spacer, depending on the configuration of said opening.

[0028] In particular embodiments, the internal combustion engine comprises two connecting rods respectively fixed to the spacer by their foot, and respectively fixed to one of the ends of the crossbar by their head.

[0029] The connecting rod small ends can be respectively secured to the arms or to the spacer body, preferably at two respective points substantially diametrically opposite to each other with respect to the axis of rotation of the crankshaft journals.

[0030] In particular embodiments of the invention, the internal combustion engine comprising four cylinders arranged in pairs, symmetrically arranged on either side of a median plane P comprising the axis of rotation of the crankshaft, so that the longitudinal axis of the cylinders is perpendicular to the plane P.

[0031] In particular embodiments of the invention, the spacer comprises four arms divided into two pairs connected on either side of a spacer body.

[0032] In particular embodiments of the invention, the internal combustion engine comprises two spreaders movable in rotation around the crankpin, a connecting rod being fixed by its head to at least one of the ends of each spreader.

[0033] According to other characteristics, the internal combustion engine comprises four connecting rods respectively secured to one of the arms of the spacer by their foot, and respectively secured to one of the ends of the spreaders by their head.

[0034] According to another embodiment of the invention, the internal combustion engine comprising a plurality of sets of four cylinders juxtaposed to each other along the axis of rotation of the crankshaft, so that the pistons of each set of four cylinders are in kinematic relation with the same crankshaft.

[0035] In its various aspects, the internal combustion engine according to the invention has the particular advantage of having, for identical power, smaller dimensions and a lower mass, due to the arrangement of the cylinders and the short length of the crankshaft. By way of example, at equal power, the combustion engine according to the invention has a mass and a volume approximately three times less than an engine of the state of the art. Presentation of figures

[0036] The invention will be better understood on reading the following description, given by way of non-limiting example, and made with reference to the figures which represent: figure 1 : a schematic view of a first embodiment of an internal combustion engine, the pistons being at mid-stroke, figure 2 : a view of certain isolated elements of the internal combustion engine according to the figure 1 , picture 3 : a schematic view of the internal combustion engine according to the figure 1 , the pistons being in an extreme position, figure 4 : a view of certain isolated elements of the internal combustion engine according to the picture 3 , figure 5 : a schematic view of an internal combustion engine according to a second embodiment of the invention, the pistons being at mid-stroke, figure 6 : a view of certain isolated elements of the internal combustion engine according to the figure 5 , figure 7 : a schematic view of a connecting rod-crank mechanism of an internal combustion engine according to a third embodiment of the invention, figure 8 : a schematic view of an embodiment of a connecting rod-crank mechanism of an internal combustion engine according to the invention. Detailed description of the invention

[0037] The present invention relates to an internal combustion engine 10 comprising cylinders in each of which a piston is slidably engaged, so as to form a combustion chamber, known to those skilled in the art. The pistons are in kinematic relationship with a connecting rod-crank mechanism intended to transmit a torque capable of driving, for example, a moving vehicle.

[0038] In a first embodiment of the invention, as represented by the figures 1 to 4 , the internal combustion engine 10 comprises two cylinders 11, 11' extending respectively along two parallel longitudinal axes AA' and BB' and each comprising an opening. The cylinders 11, 11' are not coaxial and are preferably arranged on either side, and at a distance, from a median plane P, so that the longitudinal axes AA' and BB' are perpendicular to the median plane P and that their respective openings face each other.

[0039] Each cylinder 11, 11' is adapted to receive a piston 12, 12' slidably engaged, through its opening, between two extreme positions, respectively called “top dead center” and “bottom dead center”.

[0040] In the first embodiment of the invention, the connecting rod-crank mechanism comprises a spacer 13 connecting the pistons 12 and 12', and to which said pistons 12 and 12' are rigidly fixed. The spacer 13 is adapted to maintain a fixed spacing between the two pistons 12, 12', so that the movement in translation of one of the pistons 12 or 12' causes a similar movement of the other piston. So, as represented by the picture 3 , when a piston 12' is at top dead center, the other piston 12 is at bottom dead center, and vice versa.

[0041] As represented by the figure 2 and 4 , the spacer 13 comprises two arms, 131, 131', for example parallel. The arms 131, 131' of the spacer 13 extend between a first, so-called proximal end, by which the arms 131, 131' are connected on either side of a body 133 of the spacer 13, and a second end, called distal, remote from the body 133, to which a piston 12, 12' is fixed. Preferably, each piston 12 and 12' is fixed on an arm 131 and 131' with degrees of freedom in rotation, for example along axes perpendicular to the longitudinal axes of the arms, so as to correct any defects in parallelism of the cylinders between them. .

[0042] It should be noted that, on the figure 2 and 4 , the pistons are not shown. As illustrated by the figure 1 and 3 , the distal end of each arm 131, 131' is adapted to be engaged in a cylinder, with the piston 12, 12' to which it is fixed.

[0043] The connecting rod-crank mechanism also comprises a crankshaft 20 fitted with a crankpin 21 interposed between two journals 22, and at least one balancing weight 23 known to those skilled in the art. The journals 22 are mounted so as to be able to rotate, for example, in bearings known per se.

[0044] In the non-limiting example illustrated by the figure 2 , the body 133 of the spacer 13 is provided with an opening 132 configured to receive the crank pin 21, and through which said crank pin 21 is capable of moving, during, for example, the rotation of the crankshaft 20. The opening extends, for example, along a longitudinal axis perpendicular to the respective longitudinal axes AA' and BB of the cylinders 11 and 11'.

[0045] Alternatively, the body 133 of the spacer 13 can be configured such that it does not include an opening.

[0046] Preferably, the axis of rotation of the journals 22 of the crankshaft 20 is inscribed in the median plane P, and that said axis is located equidistant from each of the respective longitudinal axes AA' and BB of the cylinders 11, 11'.

[0047] The connecting rod-crank mechanism also comprises at least one connecting rod 30 secured, by one of its ends called "connecting rod foot" 31, to the distal end of one of the arms 131 or 131 ', and by its other end, called " big end » 32 to a spreader bar 40.

[0048] In other exemplary embodiments, connecting rod 30 can also be secured by its foot 31, at any point along arms 131 or 131'. This arrangement advantageously makes it possible to dimension the length of the connecting rod in an optimal manner so as to limit the second order inertia forces.

[0049] In the non-limiting example of embodiment represented by the figures 1 to 4 , the connecting rod-crank mechanism comprises two connecting rods 30 and 30' respectively secured by their foot 31 or 31' to the distal end of one of the arms 131 or 131', and by their head 32 or 32' to a spreader bar 40. Preferably, connecting rod feet 31 and 31' are integral with arms 131 and 131' at two respective points substantially diametrically opposed to each other with respect to the axis of rotation of journals 22.

[0050] As schematically shown in figures 1 to 4 , the spreader bar 40 comprises a central opening through which it is rotatably mounted around the crankpin 21, for example by means of a plain bearing known per se. The center of the rudder 40 is defined as the point with respect to which any point on the periphery of the rudder has a symmetrical point.

[0051] The spreader bar 40 extends along a longitudinal axis CC' and has two ends on either side of the crank pin 21.

[0052] Preferably, each of the ends of the crossbar 40 is secured to a connecting rod head 32, 32', by means known per se, such as a shaft housed in bores made respectively in the heads 32, 32' of the connecting rods 30, 30' and in the ends of the lifter 40.

[0053] The crossbar 40 is capable of driving each connecting rod big end 32, 32' to describe a trajectory different from the circular trajectory described by the crankpin 21 of the crankshaft, during operation of the internal combustion engine 10. Advantageously, the crossbar 40 causes each connecting rod big end 32 to describe a substantially non-circular trajectory.

[0054] The connecting rods 32 and 32' and the crossbar 40 are dimensioned so that, when the pistons are at mid-distance, the connecting rods 30 and 30' are substantially parallel.

[0055] During the operating cycle of the internal combustion engine 10 which is the subject of the present invention, when combustion is generated in the combustion chamber of a cylinder 11 or 11', a thrust force is produced on a piston 12 or 12' arranged to slide in said cylinder. Said piston then transmits, via the spacer 13, part of this force to the connecting rods 30 and 30'. The connecting rods 30 and 30' transmit these forces to the respective ends of the crossbar 40 to which they are attached, creating a moment of force causing the rotation of the said crossbar 40 around the crankpin 21, and in fact causing the rotation of the crankpin 21 around the axis of rotation of the pins 22. It should be noted that the forces applied by the connecting rods on the spreader are characterized, for one of the connecting rods, by a tensile force on the spreader 40, and for the other, by a thrust force on the rudder bar 40.

[0056] The distance between the center of the lifter 40 and the axis of rotation of each big end 32 on the lifter 40 represents a lever arm. Consequently, the intensity of the moment of force generated on the end of the crossbar 40 is proportional to the length of this distance.

[0057] These arrangements make it possible to be able to reduce the dimensions of the cylinders 11, 11' and of the pistons 12, 12', while allowing the crankshaft to deliver a relatively high torque. For a torque delivered by the crankshaft of a given value, the dimensions of the pistons and cylinders of the engine 10 which is the subject of the present invention are therefore smaller than those of the engines of the state of the art.

[0058] The two pistons 12 and 12' being kinematically linked together by means of the spacer 13, the thrust force produced on one of the pistons 12 or 12', during combustion, is also partly transmitted to the other piston 12 or 12'. The axial guidance of one of the pistons 12 or 12', during its sliding in the cylinder 11 or 11' with which it is associated, is ensured by the other piston 12 or 12' by sliding in the cylinder 11 or 11' to which he is associated. As a result, the pistons 12 and 12' are essentially subjected to axial forces and generate little or no transverse forces in the cylinders 11, 11' during their sliding. This arrangement advantageously makes it possible to significantly reduce the second order inertia forces.

[0059] During the movement of the pistons 12 and 12 'between the top and bottom dead centers, and vice versa, the forces of the connecting rods 30 and 30' on the lifter 40 cause said lifter 40 to describe substantially a circular translation movement around the axis of rotation of the trunnions 22.

[0060] When moving a piston 12 or 12' from one of its extreme positions to the other, the connecting rod 30 or 30' secured to the arm 131 or 131' to which said piston 12 or 12' is fixed, pivots around its foot 31 or 31', between two extreme angular positions, as shown in broken line in figure 2 . Each connecting rod 31 and 31' is adapted so that its head 32 or 32' describes, during an engine operating cycle, an arc of a circle at an angle a.

[0061] When the pistons 12 and 12' are respectively halfway between the top dead center and bottom dead center positions, the longitudinal axis CC' of the spreader bar 40 forms an angle β with the median plane P, as shown diagrammatically in the figure 1. Furthermore, when the pistons 12 and 12' occupy the top dead center and bottom dead center positions, the longitudinal axis CC' is parallel to the median plane P, as shown in picture 3 .

[0062] The lifter 40 is then subjected, during the movement of the pistons 12 and 12 'between their two extreme positions, to an alternating rotational movement around the crankpin 21, through an angle β with respect to the median plane P.

[0063] The spreader bar 40 therefore describes a movement consisting of a circular translation around the axis of rotation of the journals 22 and an alternating rotation around the crankpin 21.

[0064] This alternating rotation advantageously allows the pistons 12 and 12' to remain for a maximum time in the vicinity of the top and bottom dead centers.

[0065] Thus, during operation of the internal combustion engine 10, when the piston 12 or 12' is at top dead center, a high pressure, close to the maximum pressure of the mixture, is maintained longer by said piston 12 or 12' than in a prior art engine. By high pressure, close to the maximum pressure of the mixture, is meant a pressure of between ninety and one hundred percent of the maximum pressure. The maximum mixture pressure is the mixture pressure when the piston 12 or 12' is at top dead center. The amount of time during which high pressure is applied to the mixture is representative of approximately twenty five degrees of crankshaft rotation.

[0066] Advantageously, the high pressure is maintained for a sufficiently long time by said piston within the combustion chamber, to obtain substantially complete combustion of the mixture during the combustion phase.

[0067] Furthermore, this alternating rotation of the lifter 40 makes it possible in particular to greatly limit the acceleration of the piston 12, 12' due to the obliqueness of the connecting rods.

[0068] In a second embodiment, as schematically represented on the figures 5 and 6 , the internal combustion engine 10 comprises four pistons 12, 12', 12" and 12"' respectively slidably engaged in four cylinders 11, 11', 11" and 11"' each comprising an opening. Said cylinders are arranged two by two, on either side of a median plane P', the longitudinal axis of the cylinders 11, 11', 11" and 11"' being perpendicular to this plane P'. Preferably, said cylinders are arranged symmetrically on either side, and at a distance, from the median plane P', so that the cylinders 11, 11" of a pair are respectively coaxial with the cylinders 11', 11"' of the other pair, and that the openings of said cylinders 11, 11" are arranged facing the openings of cylinders 11', 11"'.

[0069] The internal combustion engine 10 according to the second embodiment has a connecting rod-crank mechanism similar to that of the first embodiment, with the exception of the number of cylinders, and consequently of piston, strut arm and connecting rod. .

[0070] Preferably, for reasons of balance of the moving masses, the axis of rotation of the journals 22 of the crankshaft 20 is located equidistant from all the cylinders 11, 11', 11" and 11"', for example, inscribed in the plane P'.

[0071] The four pistons 12, 12', 12" and 12"' are kinematically linked to each other via the spacer 13, so that the movement of two pistons 12 and 12", or 12' and 12' "of a pair causes a similar displacement of the pistons 12 and 12", or 12' and 12"' of the other pair.

[0072] Analogously to the first embodiment, the pairs of pistons 12 and 12", 12' and 12"' are fixed to the spacer 13 via pairs of arms 131 and 131', 131" and 131"' of the spacer 13 connected to the spacer body 133, as illustrated by the figure 6 . It should be noted that the pistons are not represented on the figure 6 . The pairs of arms are respectively connected on either side of the spacer body 133 so that the longitudinal axis of an arm 131 or 131' of a pair coincides with the longitudinal axis of an arm 131 " or 131"' of the other pair. Preferably, the longitudinal axes of the arms 131, 131', 131" and 131"' coincide respectively with the longitudinal axes of the cylinders 11, 11', 11" and 11"'.

[0073] As schematically shown in the figure 6 , at each distal end of the arms 131, 131', 131" and 131"' of the spacer is respectively fixed the foot 31, 31', 31" and 31"' of a connecting rod 30, 30', 30" and 30"'. Said connecting rods 30 and 30' are respectively secured by their head 32, 32' to a spreader bar 40, and said connecting rods 30" and 30"' are respectively secured by their head 32", 32"' to a second spreader bar 40'. Alternatively, each spreader bar 40, 40' can be secured to a single connecting rod 30 or 30', and 30" or 30"' respectively. Two pairs of connecting rods are respectively formed by the connecting rods 30 and 30' and by the connecting rods 30" and 30"'.

[0074] Advantageously, the connecting rods 30 and 30', and 30" and 30"' of each pair are diagonally opposed, as illustrated by the figures 5 and 6 . By “diagonally opposed” is meant that the connecting rods of each pair of connecting rods are respectively associated with the arms of each pair of arms, and that the respective longitudinal axes of the arms with which the connecting rods of the same pair are associated are distant from one another. the other.

[0075] In this embodiment of the invention, two lifters 40 and 40' are mounted so as to rotate around the crankpin 21. The lifters 40 and 40' are arranged, for example, on either side of the spacer 13, on crankpin 21.

[0076] Thus, during the displacement of the pistons 12, 12', 12" and 12"' between the top and bottom dead centers and vice versa, the forces of the connecting rods 30, 30', 30" and 30"' on each of the spreaders 40 and 40 'cause each said lifter to describe substantially a circular translational movement around the axis of rotation of the journals 22.

[0077] However, insofar as each lifter 40 and 40' is respectively associated with a pair of connecting rods 30 and 30', and 30" and 30"' diagonally opposite, the lifters 40 and 40' are led to describe, around the crank pin 21 , an alternating rotational movement, inverted with respect to each other. In other words, the rotational movement of one of the lifters 40 or 40' is symmetrical to the rotational movement of the other lifter 40 or 40' according to a plane of symmetry parallel to the plane P'. The angle formed by the longitudinal axis of one of the lifters 40 or 40' with the plane P is opposite to the angle formed by the longitudinal axis of the other lifter 40 or 40' with said plane P, with respect to this plane P.

[0078] Thus, in the same way as for the first embodiment, this alternating rotational movement allows the connecting rod heads 32, 32', 32" and 32"' to describe a non-circular trajectory during operation of the internal combustion engine 10 , that is to say, during the rotation of the spreaders 40 and 40 'about the axis of rotation of the journals 22.

[0079] Therefore, during the strokes of the pistons 12, 12', 12", 12"' respectively in the cylinders 11, 11', 11", 11"', said pistons remain long enough at top dead center to maintain a high pressure. long enough by the piston within the combustion chamber, to obtain substantially complete combustion of the mixture.

[0080] Advantageously, combustion can be carried out concomitantly in the combustion chamber of each cylinder 11 and 11", or 11' and 11"' of the same pair. The thrust forces produced by the combustion are transmitted by the pistons 12 and 12', or 12" and 12"' respectively engaged in the cylinders 11 and 11", or 11' and 11"' of said pair to the other pistons 12 and 12', or 12" and 12"' and include an axial component only. The axial guidance of one of the pistons during its sliding in the cylinder with which it is associated, is ensured by the sliding of the other pistons in the respective cylinders with which they are associated. The pistons therefore do not generate transverse forces. This arrangement advantageously makes it possible to significantly reduce the second order inertia forces.

[0081] In a third embodiment of the invention, the internal combustion engine 10 comprises two cylinders in accordance with the first embodiment described above, except that they are coaxial. Analogously to the other embodiments of the invention, a piston is slidably engaged in each cylinder.

[0082] The internal combustion engine 10 according to the third embodiment comprises a connecting rod-crank mechanism, as represented by the figure 7 , identical to that of the first embodiment, with the exception of the configuration of the spacer 13.

[0083] More particularly, analogously to the first embodiment, the pistons are kinematically linked together via the arms 131 and 131' of the spacer 13. However, in this embodiment of the invention, the arms 131 and 131' are coaxial and are arranged on either side of the spacer body 133. Preferably, the longitudinal axes of the arms 131 and 131' and the axis of rotation of the journals 22 of the crankshaft 20 are inscribed in the same plane M. This plane M is for example a median plane of the spacer 13.

[0084] The feet 31 and 31' of the connecting rods 30 and 30' are respectively secured to the spacer body 133, at two points substantially diametrically opposite to each other with respect to the axis of rotation of the journals 22. The connecting rods 30 and 30' are respectively joined by their head 32 and 32' to each of the ends of the spreader bar 40.

[0085] Alternatively, a first and a second crossbar 40 and 40' can be arranged on either side of the spacer 13 and arranged in rotation around the crankpin 21. The internal combustion engine 10 then comprises two pairs of connecting rods, each of connecting rod pairs being integral with a spreader as described above.

[0086] In another exemplary embodiment of the connecting rod-crank mechanism as represented by the figure 8 , and which can be implemented in the embodiments of the invention described above, the spacer 13 is provided with an opening 132 configured so that one of the journals 22 of the crankshaft 20 is adapted to evolve through said opening 132 during sliding of said spacer 13. Opening 132 preferably extends along a longitudinal axis parallel to the respective longitudinal axes AA' and BB' of cylinders 11 and 11'. The spacer 13 comprises arms 131, 131 'in accordance with one of the embodiments described above, connected on either side of the spacer body 133, and at the end of each of which is fixed a piston 12 or 12'.

[0087] The connecting rod-crank mechanism also comprises, for example, two connecting rods 30, 30' respectively secured by their foot 31, 31' to the arms 131, 131' or to the body 133, and by their head 32, 32' to the spreader bar 40.

[0088] Thus, analogously to the operating cycle of the internal combustion engine 10 described previously, when combustion is generated in the combustion chamber of a cylinder 11 or 11′, a thrust force is produced on a piston 12 or 12 'Slidably arranged in said cylinder. Said piston then transmits, through the spacer 13, part of this force to the connecting rods 30, 30'. The connecting rods 30, 30' transmit this force to the ends of the crossbar 40 to which they are respectively integral, creating a moment of force causing the rotation of the said crossbar 40 around the crankpin 21, and in fact causing the rotation of the crankpin 21 around the axis of rotation of the trunnions 22.

[0089] In the same way as for the previously described embodiments, one of the connecting rods 30 or 30' exerts a pulling force on the spreader bar 40, and the other exerts a pushing force on the spreader bar 40.

[0090] In other embodiments of the invention, not shown in the figures, the internal combustion engine 10 may comprise more or fewer cylinders than the engine according to the embodiments of the invention previously described. The piston number is the same as the cylinder number.

[0091] In other embodiments of the invention, the internal combustion engine 10 comprises sets of two or four cylinders arranged in series, juxtaposed to each other, along the axis of rotation of the journals, and sharing a single crankshaft . The internal combustion engine 10 preferably comprises two sets of two or four cylinders, each set of cylinders being associated with pistons in kinematic relationship with a connecting rod-crank mechanism according to one of the embodiments of the invention described above. More specifically, the crankshaft comprises two crankpins, arranged for example, at one hundred and eighty degrees relative to each other, on each of which are adjusted in rotation, one or two lifters. It should be noted that a spreader is preferably attached to two connecting rods, and is therefore associated with two pistons. Therefore, the number of lifters is equal to half the number of cylinders.

[0092] More generally, it should be noted that the embodiments considered above have been described by way of non-limiting examples, and that other variants are therefore possible.

Claims

1. An internal combustion engine (10) comprising at least two cylinders (11, 11') with parallel longitudinal axes, each cylinder comprising an opening and a piston (12, 12') capable of moving in translation inside said cylinder, said respective openings in said cylinders facing one another, said pistons being in kinematic relation with a connecting rod / crank mechanism, said connecting rod / crank mechanism comprising: - a spacer (13) connecting said pistons, adapted to maintain a fixed spacing between said pistons, such that a translational movement of one piston causes the other piston to perform the same translational movement, said pistons being respectively attached to arms (131, 131') of said spacer, - a crankshaft (20) rotatably mounted about an axis, arranged between the openings in the cylinders and between the longitudinal axes of said cylinders, said crankshaft comprising a crank pin (21), - at least one connecting rod (30) comprising a first end, referred to as the "small end" (31), secured to the spacer, and a second end, referred to as the "big end" (32), characterized in that the connecting rod / crank mechanism comprises a rocker (40) rotatably mounted about the crank pin, comprising two ends arranged on either side of said crank pin, and in that the second end, referred to as the "big end", is secured to one of the ends of the rocker.

2. The internal combustion engine (10) as claimed in claim 1, in which the arms (131, 131') of the spacer (13) are connected to a spacer body (133) including an opening (132) through which the crankshaft (20) is capable of moving.

3. The internal combustion engine (10) as claimed in either of claims 1 and 2, comprising two connecting rods (30, 30'), respectively secured to the spacer (13) by their small end (31, 31'), and respectively secured to one of the ends of the rocker (40, 40') by their big end (32, 32').

4. The internal combustion engine (10) as claimed in one of claims 1 to 3, comprising four cylinders (11, 11', 11", 11"') arranged in pairs, arranged symmetrically on either side of a median plane P in which the axis of rotation of the crankshaft is inscribed, so that the longitudinal axis of the cylinders is perpendicular to the plane P.

5. The internal combustion engine (10) as claimed in claim 4, in which the spacer (13) comprises four arms (131, 131', 131", 131"') distributed in two pairs connected on either side of a spacer body (133).

6. The internal combustion engine (10) as claimed in either of claims 4 and 5, comprising two rockers (40, 40') rotatably mounted about the crank pin (21), a connecting rod (30, 30") being secured by its big end to at least one of the ends of each rocker.

7. The internal combustion engine (10) as claimed in one of claims 4 to 6, comprising four connecting rods (30, 30', 30", 30"'), respectively secured to one of the arms (131, 131', 131", 131"') of the spacer (13) by their small end (31, 31', 31", 31"'), and respectively secured to one of the ends of the rockers (40, 40') by their big end (32, 32', 32", 32"').

8. The internal combustion engine (10) as claimed in one of claims 4 to 7, comprising a plurality of sets of four cylinders juxtaposed with one another along the axis of rotation of the crankshaft, in such a way that the pistons of each set of four cylinders are in kinematic relation with the same crankshaft.