Internal combustion engine

Abstract

An internal combustion engine including at least two cylinders with parallel longitudinal axes, each cylinder including an opening and a piston capable of moving in translation inside the cylinder, the respective openings of the cylinders facing each other, the pistons being in kinematic relation with a connecting rod-crank mechanism including: a spacer connecting the pistons, suitable for maintaining a fixed spacing between the pistons, the pistons being respectively attached to the arms of the spacer, a crankshaft rotating about an axis, arranged between the openings of the cylinders and between the longitudinal axes of the cylinders, the crankshaft comprising a crank pin, a rocker rotating about the crank pin, at least one connecting rod including a first, small end, rigidly attached to the spacer and a second, big end, rigidly attached to one of the ends of the rocker.

Claims

1. An internal combustion engine comprising at least two cylinders with parallel longitudinal axes, each cylinder comprising an opening and a piston 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, characterized in that said connecting rod/crank mechanism comprises: a spacer 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 of said spacer, a crankshaft 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, a rocker rotatably mounted about the crank pin, comprising two ends arranged on either side of said crank pin, at least one connecting rod comprising a first end, being a small end, secured to the spacer, and a second end, being a big end, secured to one of the ends of the rocker.

2. The internal combustion engine as claimed in claim 1, in which the arms of the spacer are connected to a spacer body including an opening through which the crankshaft is capable of moving.

3. The internal combustion engine as claimed in claim 1, comprising two connecting rods, respectively secured to the spacer by their small end, and respectively secured to one of the ends of the rocker by their big end.

4. The internal combustion engine as claimed in claim 1, comprising four cylinders 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 as claimed in claim 4, in which the spacer comprises four arms distributed in two pairs connected on either side of a spacer body.

6. The internal combustion engine as claimed in claim 4, comprising two rockers rotatably mounted about the crank pin, a connecting rod being secured by its big end to at least one of the ends of each rocker.

7. The internal combustion engine as claimed in claim 4, comprising four connecting rods, respectively secured to one of the arms of the spacer by their small end, and respectively secured to one of the ends of the rockers by their big end.

8. The internal combustion engine as claimed in claim 4, 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.

Description

PRESENTATION OF THE FIGURES

(1) A clearer understanding of the invention will be gained by reading the following description, provided by way of non-limiting example and with reference to the figures, which show:

(2) FIG. 1: a schematic view of a first embodiment of an internal combustion engine, the pistons being mid-stroke,

(3) FIG. 2: a view of some elements separated from the internal combustion engine according to FIG. 1,

(4) FIG. 3: a schematic view of the internal combustion engine according to FIG. 1, the pistons being in an end position,

(5) FIG. 4: a view of some elements separated from the internal combustion engine according to FIG. 3,

(6) FIG. 5: a schematic view of an internal combustion engine according to a second embodiment of the invention, the pistons being mid-stroke,

(7) FIG. 6: a view of some elements separated from the internal combustion engine according to FIG. 5,

(8) FIG. 7: a schematic view of a connecting rod/crank mechanism of an internal combustion engine according to a third embodiment of the invention,

(9) FIG. 8: a schematic view of an exemplary embodiment of a connecting rod/crank mechanism of an internal combustion engine according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(10) 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 a person skilled in the art. The pistons are in kinematic relation with a connecting rod/crank mechanism for transmitting a torque capable of driving, for example, a moving vehicle.

(11) In a first embodiment of the invention, as shown in FIGS. 1 to 4, the internal combustion engine 10 comprises two cylinders 11, 11 lying along two parallel longitudinal axes AA and BB, respectively, and each including an opening. The cylinders 11, 11 are not coaxial and are preferably arranged on either side of, and at a distance from, a median plane P, such that the longitudinal axes AA and BB are perpendicular to the median plane P and such that their openings face one another.

(12) Each cylinder 11, 11 is adapted to receive a piston 12, 12 slidably engaged, through its opening, between two end positions, respectively called top dead center and bottom dead center.

(13) 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 attached. The spacer 13 is adapted to maintain a fixed spacing between the two pistons 12, 12, such that the translational movement of one piston 12 or 12 results in a similar movement of the other piston. Thus, as shown in FIG. 3, when a piston 12 is at top dead center, the other piston 12 is at bottom dead center, and vice versa.

(14) As shown in FIGS. 2 and 4, the spacer 13 comprises two arms 131, 131, which are for example parallel. The arms 131, 131 of the spacer 13 extend between a first end, referred to as the proximal end, via which the arms 131, 131 are connected to either side of a spacer 13 body 133, and a second end, referred to as the distal end, at a distance from the body 133, to which a piston 12, 12 is attached. Preferably, each piston 12 and 12 is attached to 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 of parallelism between the cylinders.

(15) It should be noted that, in FIGS. 2 and 4, the pistons are not shown. As shown in FIGS. 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 attached.

(16) The connecting rod/crank mechanism also comprises a crankshaft 20 with a crank pin 21 interposed between two journals 22, and at least one balancing weight 23 known to a person skilled in the art. The journals 22 are rotatably mounted, for example, in bearings known per se.

(17) In the non-limiting example shown in FIG. 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 adapted to move, when, for example, the crankshaft 20 rotates. The opening lies for example along a longitudinal axis perpendicular to the longitudinal axes AA and BB of the cylinders 11 and 11, respectively.

(18) Alternatively, the body 133 of the spacer 13 may be configured such that it does not include an opening.

(19) Preferably, the axis of rotation of the journals 22 of the crankshaft 20 is inscribed in the median plane P, and said axis is located equidistant from each of the longitudinal axes AA and BB of the cylinders 11 and 11, respectively.

(20) The connecting rod/crank mechanism also comprises at least one connecting rod 30 which is secured, by one of its ends referred to as the small end 31, to the distal end of one of the arms 131 or 131, and by its other end, referred to as the big end 32, to a rocker 40.

(21) In other embodiments, the connecting rod 30 may also be secured by its small end 31 to any point along the arms 131 or 131. This arrangement advantageously makes it possible to dimension the length of the connecting rod optimally so as to limit second-order inertial forces.

(22) In the non-limiting embodiment shown in FIGS. 1 to 4, the connecting rod/crank mechanism comprises two connecting rods 30 and 30 respectively secured by their small end 31 or 31 to the distal end of one of the arms 131 or 131, and by their big end 32 or 32 to a rocker 40. Preferably, the connecting rod small ends 31 and 31 are secured to the arms 131 and 131 at two respective points substantially diametrically opposite one another relative to the axis of rotation of the journals 22.

(23) As schematically shown in FIGS. 1 to 4, the rocker 40 comprises a central opening via which it is rotatably mounted about the crank pin 21, for example by means of a smooth bearing known per se. The center of the rocker 40 is defined as the point about which any point on the periphery of the rocker has a symmetrical point.

(24) The rocker 40 lies along a longitudinal axis CC and has two ends on either side of the crank pin 21.

(25) Preferably, each of the ends of the rocker 40 is secured to a connecting rod big end 32, 32, by means known per se, such as a shaft mounted in bores made respectively in the big ends 32, 32 of the connecting rods 30, 30 and in the ends of the rocker 40.

(26) The rocker 40 is adapted to cause each connecting rod big end 32, 32 to describe a path different to the circular path described by the crank pin 21 of the crankshaft during operation of the internal combustion engine 10. Advantageously, the rocker 40 causes each connecting rod big end 32 to describe a substantially non-circular path.

(27) The connecting rods 32 and 32 and the rocker 40 are dimensioned such that when the pistons are halfway, the connecting rods 30 and 30 are substantially parallel.

(28) During the operating cycle of the internal combustion engine 10 according to the present invention, when a 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, by means of the spacer 13, a portion 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 rocker 40 to which they are secured, creating a moment of force causing rotation of said rocker 40 about the crank pin 21, and in fact causing rotation of the crank pin 21 about the axis of rotation of the journals 22. It should be noted that the forces applied by the connecting rods on the rocker are characterized, for one of the connecting rods, by a traction force on the rocker 40 and, for the other, by a thrust force on the rocker 40.

(29) The distance between the center of the rocker 40 and the axis of rotation of each connecting rod big end 32 on the rocker 40 represents a lever arm. Therefore, the intensity of the moment of force generated on the end of the rocker 40 is proportional to the length of this distance.

(30) These arrangements make it possible to reduce the dimensions of the cylinders 11, 11 and of the pistons 12, 12, while allowing the crank shaft to deliver a relatively high torque. For a torque of given value delivered by the crankshaft, the dimensions of the pistons and cylinders of the engine 10 according to the present invention are therefore smaller than in prior art engines.

(31) Since the two pistons 12 and 12 are kinematically linked to one another by virtue of the spacer 13, the thrust force produced on one of the pistons 12 or 12, during the combustion, is also partially transmitted to the other piston 12 or 12. The axial guiding of one of the pistons 12 or 12, as it slides in the cylinder 11 or 11 with which it is associated, is provided by the sliding of the other piston 12 or 12 in the cylinder 11 or 11 with which it is associated. Therefore, the pistons 12 and 12 are subjected essentially to axial forces and generate little or no transverse forces in the cylinders 11, 11 as they slide. This arrangement advantageously makes it possible to significantly reduce second-order inertial forces.

(32) When the pistons 12 and 12 move between top and bottom dead center, and vice versa, the forces of the connecting rods 30 and 30 on the rocker 40 cause said rocker 40 to describe substantially a circular translational movement about the axis of rotation of the journals 22.

(33) When a piston 12 or 12 moves from one of its end 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 attached, pivots about its small end 31 or 31, between two angular end positions, as shown in broken lines in FIG. 2. Each connecting rod 31 and 31 is adapted such that its big end 32 or 32 describes, during an engine operating cycle, an arc of a circle of angle .

(34) When the pistons 12 and 12 are each halfway between the top dead center and bottom dead center positions, the longitudinal axis CC of the rocker 40 makes an angle with the median plane P, as shown schematically in FIG. 1. Furthermore, when the pistons 12 and 12 are in the top dead center and bottom dead center positions, the longitudinal axis CC is parallel to the median plane P, as shown in FIG. 3.

(35) The rocker 40 is thus subjected, during the movement of the pistons 12 and 12 between their two end positions, to a reciprocating rotary movement about the crank pin 21 by an angle relative to the median plane P.

(36) The rocker 40 thus describes a movement composed of a circular translation about the axis of rotation of the journals 22 and a reciprocating rotation about the crank pin 21.

(37) This reciprocating rotation advantageously allows the pistons 12 and 12 to stay in the vicinity of top and bottom dead center for a maximum length of time.

(38) 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 by said piston 12 or 12 for longer than in a prior art engine. High pressure, close to the maximum pressure of the mixture, means a pressure between ninety and one hundred percent of the maximum pressure. The maximum pressure of the mixture is the pressure of the mixture when the piston 12 or 12 is at top dead center. The time for which a high pressure is applied to the mixture represents rotation of the crankshaft by approximately twenty-five degrees.

(39) Advantageously, the high pressure is maintained in the combustion chamber by said piston long enough to obtain substantially complete combustion of the mixture during the combustion phase.

(40) Moreover, this reciprocating rotation of the rocker 40 makes it possible in particular to greatly limit the acceleration of the piston 12, 12 due to the obliquity of the connecting rods.

(41) In a second embodiment, as shown schematically in FIGS. 5 and 6, the internal combustion engine 10 has four pistons 12, 12, 12 and 12 slidably engaged, respectively, in four cylinders 11, 11, 11 and 11, each comprising an opening. Said cylinders are arranged in pairs, 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 of, and at a distance from, the median plane P, such that the cylinders 11, 11 of one pair are coaxial with respect to the cylinders 11, 11 of the other pair, and such that the openings in said cylinders 11, 11 are arranged opposite the openings in the cylinders 11, 11.

(42) The internal combustion engine 10 according to the second embodiment has a connecting rod/crank mechanism similar to that of the first embodiment, except for the number of cylinders, and therefore the number of pistons, spacer arms and connecting rods.

(43) Preferably, for reasons of balance of masses in movement, the axis of rotation of the journals 22 of the crankshaft 20 is located equidistant from all of the cylinders 11, 11, 11 and 11, for example, inscribed within the plane P.

(44) The four pistons 12, 12, 12 and 12 are kinematically linked to one another via the spacer 13, such that the movement of two pistons 12 and 12, or 12 and 12, of one pair results in a similar movement of the pistons 12 and 12, or 12 and 12, of the other pair.

(45) As in the first embodiment, the pairs of pistons 12 and 12, 12 and 12 are attached to the spacer 13 by means of pairs of arms 131 and 131, 131 and 131 of the spacer 13 connected to the spacer body 133, as shown in FIG. 6. It should be noted that the pistons are not shown in FIG. 6. The pairs of arms are connected respectively on either side of the spacer body 133 such that the longitudinal axis of one 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 with the longitudinal axes of the cylinders 11, 11, 11 and 11, respectively.

(46) As shown schematically in FIG. 6, the small end 31, 31, 31 and 31 of a connecting rod 30, 30, 30 and 30 is respectively secured to each distal end of the spacer arms 131, 131, 131 and 131. Said connecting rods 30 and 30 are respectively secured by their big end 32, 32 to a rocker 40 and said connecting rods 30 and 30 are respectively secured by their big end 32, 32 to a second rocker 40. Alternatively, each rocker 40, 40 may 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 the connecting rods 30 and 30.

(47) Advantageously, the connecting rods 30 and 30, and 30 and 30 of each pair are diagonally opposite, as shown in FIGS. 5 and 6. The term diagonally opposite means 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 spaced apart from one another.

(48) In this embodiment of the invention, two rockers 40 and 40 are rotatably mounted about the crank pin 21. The rockers 40 and 40 are arranged, for example, on either side of the spacer 13, on the crank pin 21.

(49) Thus, when the pistons 12, 12, 12 and 12 move between top and bottom dead center, and vice versa, the forces of the connecting rods 30, 30, 30 and 30 on each of the rockers 40 and 40 cause each said rocker to describe substantially a circular translational movement about the axis of rotation of the journals 22.

(50) However, since each rocker 40 and 40 is respectively associated with a pair of diagonally opposite connecting rods 30 and 30, and 30 and 30, the rockers 40 and 40 are caused to describe, about the crank pin 21, a reciprocating rotary movement, inverted relative to one another. In other words, the rotational movement of one of the rockers 40 or 40 is symmetrical to the rotational movement of the other rocker 40 or 40 about a plane of symmetry parallel to the plane P. The angle made by the longitudinal axis of one of the rockers 40 or 40 with the plane P is opposite to the angle made by the longitudinal axis of the other rocker 40 or 40 with said plane P, with respect this plane P.

(51) Thus, just as for the first embodiment, this reciprocating rotary movement allows the connecting rod big ends 32, 32, 32 and 32 to describe a non-circular path during operation of the internal combustion engine 10, that is to say, upon rotation of the rockers 40 and 40 about the axis of rotation of the journals 22.

(52) Therefore, during the strokes of the pistons 12, 12, 12 and 12 in the cylinders 11, 11, 11 and 11, respectively, said pistons remain at top dead center long enough for a high pressure to be maintained by the piston within the combustion chamber long enough to obtain substantially complete combustion of the mixture.

(53) Advantageously, a combustion may be effected concomitantly in the combustion chamber of each cylinder 11 and 11, or 11 and 11, of the same pair. The thrust forces produced by 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 other pistons 12 and 12, or 12 and 12 and include only an axial component. The axial guiding of a piston as it slides in the cylinder with which it is associated, is provided 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 second-order inertial forces.

(54) In a third embodiment of the invention, the internal combustion engine 10 comprises two cylinders according to the first embodiment described above, except that they are coaxial. As in the other embodiments of the invention, a piston is slidably engaged in each cylinder.

(55) The internal combustion engine 10 according to the third embodiment comprises a connecting rod/crank mechanism as shown in FIG. 7, identical to that of the first embodiment, except for the configuration of the spacer 13.

(56) More specifically, as in the first embodiment, the pistons are kinematically linked to one another by virtue of 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.

(57) The small ends 31 and 31 of the connecting rods 30 and 30 are respectively secured to the spacer body 133 at two points substantially diametrically opposite one another relative to the axis of rotation of the journals 22. The connecting rods 30 and 30 are respectively secured by their big end 32 and 32 to each end of the rocker 40.

(58) Alternatively, a first and a second rocker 40 and 40 may be arranged on either side of the spacer 13 and arranged to rotate about the crank pin 21. The internal combustion engine 10 thus comprises two pairs of connecting rods, each connecting rod pair being secured to a rocker as described above.

(59) In another embodiment of the connecting rod/crank mechanism as shown in FIG. 8, which may be implemented in the embodiments of the invention described above, the spacer 13 has an opening 132 configured such that the journals 22 of the crankshaft 20 are adapted to move through said opening 132 during the sliding of said spacer 13. The opening 132 preferably lies along a longitudinal axis parallel to the respective longitudinal axes AA and BB of the cylinders 11 and 11. The spacer 13 comprises arms 131, 131 in accordance with one of the embodiments described above, connected to either side of the spacer body 133, and at the end of each of which a piston 12 or 12 is attached.

(60) The connecting rod/crank mechanism also includes, for example, two connecting rods 30, 30 respectively secured by their small end 31, 31 to the arms 131, 131 or to the body 133, and by their big end 32, 32 to the rocker 40.

(61) Thus, as for the operating cycle of the internal combustion engine 10 described above, when a 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, by means of the spacer 13, a portion of this force to the connecting rods 30, 30. The connecting rods 30, 30 transmit this force to the ends of the rocker 40 to which they are respectively secured, creating a moment of force causing rotation of said rocker 40 about the crank pin 21, and in fact causing rotation of the crank pin 21 about the axis of rotation of the journals 22.

(62) In the same manner as in the embodiments described above, one of the connecting rods 30 or 30 exerts a traction force on the rocker 40, and the other exerts a thrust force on the rocker 40.

(63) In other embodiments of the invention, not shown in the figures, the internal combustion engine 10 may include more or fewer cylinders than the engine according to the embodiments of the invention described above. The number of pistons is the same as the number of cylinders.

(64) In other embodiments of the invention, the internal combustion engine 10 includes sets of two or four cylinders in series, juxtaposed with one another 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 relation with a connecting rod/crank mechanism according to one of the embodiments of the invention described above. More specifically, the crankshaft includes two crank pins arranged, for example, at one hundred eighty degrees relative to one another, on each of which one or two rockers are rotatably fitted. It should be noted that a rocker is preferably secured to two connecting rods, and is thus associated with two pistons. Therefore, the number of rockers is equal to half the number of cylinders.

(65) More generally, it should be noted that the embodiments discussed above have been described as non-limiting examples, and that other variants are therefore possible.

(66) In particular, there is nothing to preclude combining, according to other examples, the various features of the various embodiments of the invention.

(67) Furthermore, the connecting rod/crank mechanism has been described in connection with a combustion engine, but may be used in an engine operating with other types of energy, such as a pressurized fluid.