Engine with variable volumetric ratio

A four-stroke internal combustion engine having the following successive phases:

• an intake phase, a compression phase, an expansion phase and an exhaust phase, said engine operating by a combustion selected from the group comprising of self-combustion, controlled ignition and combinations thereof, whereby said engine includes:
• a cylinder housing component having:
• a first series of cylinders, each having an axis and a diameter, and
• a second series of cylinders, each having an axis and diameter,
• whereby the cylinders of the first series having a larger diameter than the diameter of the cylinders of the second series, and whereby the cylinder housing has an upper face along which the cylinders are open,
• a cylinder head part covering at least partly the upper face of the cylinder housing component, said cylinder head part being associated at least with inlet valves and exhaust valves at least for the first series of cylinders,
• a first series of pistons, each piston of said first series being adapted to be driven by an alternative movement in a cylinder of the first series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• a second series of pistons, each piston of said second series being adapted to be driven by an alternative movement in a cylinder of the second series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• whereby the displacement length of the piston of the cylinder of the first series is larger than the displacement length of the piston of the cylinder of the second series,
• a first crankshaft and a second crankshaft with rotational axes parallel to one another, the first crankshaft having a crank with a large stroke, whilst the second crankshaft has a crank with a small stroke, less than the large stroke of the crank of the first crankshaft, the said crankshafts being adapted to be coupled at the same rotational speed, by a gear train and a variably timed transmission;
• at least one variably timed transmission acting on an element selected from the group comprising of the crankshafts, pieces connected to the crankshafts and pieces of the gear train adapted for coupling the crankshafts at the same rotational speed, said variably timed transmission being adapted for adjusting at least a relative angular position between the crankshafts, said relative angular position between the crankshafts being defined by the angle formed between the crank of the first crankshaft and a line parallel to the crank of the second crankshaft and crossing the rotational axis of the first crankshaft;
• in which each piston, being associated with a connecting rod, is operated by a crank of a crankshaft, the crank with the small stroke of the second crankshaft operating the rod of the piston moving within the small cylinder, whilst the crank with the large stroke of the first crankshaft operates the rod of the piston moving within the large cylinder,
• in which the first series of cylinders is laid out above the first crankshaft, whilst the second series of cylinders is laid out above the second crankshaft,
• in which each cylinder of the first series communicates with at least one cylinder of the second series via a clearance space, in such a way as to form a pair of two cylinders communicating with one another to allow the gases to pass from one cylinder to the other, independently of the position of the pistons moving within the said cylinders, and
• in which the upper face of the cylinder housing component is provided with channels forming distinct passages for each pair of cylinders, a channel for one pair of cylinders extending between a cylinder from the first series and a cylinder from the second series, whereby each channel for one pair of cylinders has a mean width determined along the upper face of between 0.5 and 0.8 times the mean of the diameters of the cylinders of the said pair of cylinders, and a minimum width determined along the upper face of between 0.5 and 0.8 times the mean of the diameters of the cylinders of the said pair of cylinders.

A four-stroke internal combustion engine having the following successive phases:

• an intake phase, a compression phase, an expansion phase and an exhaust phase, said engine operating by a combustion selected from the group comprising of self-combustion, controlled ignition and combinations thereof, whereby said engine includes:
• a cylinder housing component having:
• a first series of cylinders, each having an axis and a diameter, and
• a second series of cylinders, each having an axis and diameter,
• whereby the cylinders of the first series having a larger diameter than the diameter of the cylinders of the second series, and whereby the cylinder housing has an upper face along which the cylinders are open,
• a cylinder head part covering at least partly the upper face of the cylinder housing component, said cylinder head part being associated at least with inlet valves and exhaust valves at least for the first series of cylinders,
• a first series of pistons, each piston of said first series being adapted to be driven by an alternative movement in a cylinder of the first series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• a second series of pistons, each piston of said second series being adapted to be driven by an alternative movement in a cylinder of the second series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• whereby the displacement length of the piston of the cylinder of the first series is larger than the displacement length of the piston of the cylinder of the second series,
• a first crankshaft and a second crankshaft with rotational axes parallel to one another, the first crankshaft having a crank with a large stroke, whilst the second crankshaft has a crank with a small stroke, less than the large stroke of the crank of the first crankshaft, the said crankshafts being adapted to be coupled at the same rotational speed, by a gear train and a variably timed transmission;
• at least one variably timed transmission acting on an element selected from the group comprising of the crankshafts, pieces connected to the crankshafts and pieces of the gear train adapted for coupling the crankshafts at the same rotational speed, said variably timed transmission being adapted for adjusting at least a relative angular position between the crankshafts, said relative angular position between the crankshafts being defined by the angle formed between the crank of the first crankshaft and a line parallel to the crank of the second crankshaft and crossing the rotational axis of the first crankshaft;
• in which each piston, being associated with a connecting rod, is operated by a crank of a crankshaft, the crank with the small stroke of the second crankshaft operating the rod of the piston moving within the small cylinder, whilst the crank with the large stroke of the first crankshaft operates the rod of the piston moving within the large cylinder,
• in which the first series of cylinders is laid out above the first crankshaft, whilst the second series of cylinders is laid out above the second crankshaft,
• in which each cylinder of the first series communicates with at least one cylinder of the second series via a clearance space, in such a way as to form a pair of two cylinders communicating with one another to allow the gases to pass from one cylinder to the other, independently of the position of the pistons moving within the said cylinders, and
• in which the upper face of the cylinder housing component is provided with channels forming distinct passages for each pair of cylinders, a channel for one pair of cylinders extending between a cylinder from the first series and a cylinder from the second series, whereby each channel for one pair of cylinders has a mean width determined along the upper face of between 0.5 and 0.8 times the mean of the diameters of the cylinders of the said pair of cylinders,
• whereby said engine further comprises a layout for the variably timed transmission, the said layout being adapted to receive, at least in part, a device for controlling a phase angle difference between the first and second lines of crankshafts,
• in which the first and second crankshafts are associated, respectively, with a first driving wheel and a second driving wheel, whereby a transmission means extends between said driving wheels,
• in which an engine flywheel is mounted on the shaft of the first crankshaft, whilst the variably timed transmission is mounted on the shaft of the second crankshaft, and in which the shafts of said first and second crankshafts are adapted for positioning the variably timed transmission next to the engine flywheel,
• whereby the control for the variably timed transmission includes a directly connected guidance cylinder to monitor the phase angle difference between the second crankshaft and the first crankshaft.

A four-stroke internal combustion engine having the following successive phases:

• an intake phase, a compression phase, an expansion phase and an exhaust phase, said engine operating by a combustion selected from the group comprising of self-combustion, controlled ignition and combinations thereof, whereby said engine includes:
• a cylinder housing component having:
• a first series of cylinders, each having an axis and a diameter, and
• a second series of cylinders, each having an axis and diameter,
• whereby the cylinders of the first series having a larger diameter than the diameter of the cylinders of the second series, and whereby the cylinder housing has an upper face along which the cylinders are open,
• a cylinder head part covering at least partly the upper face of the cylinder housing component, said cylinder head part being associated at least with inlet valves and exhaust valves at least for the first series of cylinders,
• a first series of pistons, each piston of said first series being adapted to be driven by an alternative movement in a cylinder of the first series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• a second series of pistons, each piston of said second series being adapted to be driven by an alternative movement in a cylinder of the second series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• whereby the displacement length of the piston of the cylinder of the first series is larger than the displacement length of the piston of the cylinder of the second series,
• a first crankshaft and a second crankshaft with rotational axes parallel to one another, the first crankshaft having a crank with a large stroke, whilst the second crankshaft has a crank with a small stroke, less than the large stroke of the crank of the first crankshaft, the said crankshafts being adapted to be coupled at the same rotational speed, by a gear train and a variably timed transmission;
• at least one variably timed transmission acting on an element selected from the group comprising of the crankshafts, pieces connected to the crankshafts and pieces of the gear train adapted for coupling the crankshafts at the same rotational speed, said variably timed transmission being adapted for adjusting at least a relative angular position between the crankshafts, said relative angular position between the crankshafts being defined by the angle formed between the crank of the first crankshaft and a line parallel to the crank of the second crankshaft and crossing the rotational axis of the first crankshaft;
• in which each piston, being associated with a connecting rod, is operated by a crank of a crankshaft, the crank with the small stroke of the second crankshaft operating the rod of the piston moving within the small cylinder, whilst the crank with the large stroke of the first crankshaft operates the rod of the piston moving within the large cylinder,
• in which the first series of cylinders is laid out above the first crankshaft, whilst the second series of cylinders is laid out above the second crankshaft,
• in which each cylinder of the first series communicates with at least one cylinder of the second series via a clearance space, in such a way as to form a pair of two cylinders communicating with one another to allow the gases to pass from one cylinder to the other, independently of the position of the pistons moving within the said cylinders, and
• in which the upper face of the cylinder housing component is provided with channels forming distinct passages for each pair of cylinders, a channel for one pair of cylinders extending between a cylinder from the first series and a cylinder from the second series, whereby each channel for one pair of cylinders has a mean width determined along the upper face of between 0.5 and 0.8 times the mean of the diameters of the cylinders of the said pair of cylinders,
• whereby said engine further comprises a variably timed transmission comprising an assembly separated from the shaft of the second crankshaft, in which the variably timed transmission is fitted with a bearing plate which is fixed by centering in an orifice provided for in the cylinder housing, and in which the variably timed transmission contains a shaft of which one end has external splines, whilst the shaft of the second crankshaft is associated with an element or has a portion with a recess with internal splines adapted to co-operate with the external splines of the shaft to ensure that the shafts are coupled to one another, while still permitting an axial displacement between them.

A four-stroke internal combustion engine having the following successive phases:

• an intake phase, a compression phase, an expansion phase and an exhaust phase, said engine operating by a combustion selected from the group comprising of self-combustion, controlled ignition and combinations thereof, whereby said engine includes:
• a cylinder housing component having:
• a first series of cylinders, each having an axis and a diameter, and
• a second series of cylinders, each having an axis and diameter,
• whereby the cylinders of the first series having a larger diameter than the diameter of the cylinders of the second series, and whereby the cylinder housing has an upper face along which the cylinders are open,
• a cylinder head part covering at least partly the upper face of the cylinder housing component, said cylinder head part being associated at least with inlet valves and exhaust valves at least for the first series of cylinders,
• a first series of pistons, each piston of said first series being adapted to be driven by an alternative movement in a cylinder of the first series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• a second series of pistons, each piston of said second series being adapted to be driven by an alternative movement in a cylinder of the second series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• whereby the displacement length of the piston of the cylinder of the first series is larger than the displacement length of the piston of the cylinder of the second series,
• a first crankshaft and a second crankshaft with rotational axes parallel to one another, the first crankshaft having a crank with a large stroke, whilst the second crankshaft has a crank with a small stroke, less than the large stroke of the crank of the first crankshaft, the said crankshafts being adapted to be coupled at the same rotational speed, by a gear train and a variably timed transmission;
• at least one variably timed transmission acting on an element selected from the group comprising of the crankshafts, pieces connected to the crankshafts and pieces of the gear train adapted for coupling the crankshafts at the same rotational speed, said variably timed transmission being adapted for adjusting at least a relative angular position between the crankshafts, said relative angular position between the crankshafts being defined by the angle formed between the crank of the first crankshaft and a line parallel to the crank of the second crankshaft and crossing the rotational axis of the first crankshaft;
• in which each piston, being associated with a connecting rod, is operated by a crank of a crankshaft, the crank with the small stroke of the second crankshaft operating the rod of the piston moving within the small cylinder, whilst the crank with the large stroke of the first crankshaft operates the rod of the piston moving within the large cylinder,
• in which the first series of cylinders is laid out above the first crankshaft, whilst the second series of cylinders is laid out above the second crankshaft,
• in which each cylinder of the first series communicates with at least one cylinder of the second series via a clearance space, in such a way as to form a pair of two cylinders communicating with one another to allow the gases to pass from one cylinder to the other, independently of the position of the pistons moving within the said cylinders, and
• in which the upper face of the cylinder housing component is provided with channels forming distinct passages for each pair of cylinders, a channel for one pair of cylinders extending between a cylinder from the first series and a cylinder from the second series, whereby each channel for one pair of cylinders has a mean width determined along the upper face of between 0.5 and 0.8 times the mean of the diameters of the cylinders of the said pair of cylinders,
• in which the cylinder head gasket extends substantially in a plane, whereby, in relation to the cylinder head gasket plane, the axis of the cylinders of the first series of large cylinders is positioned substantially perpendicular to the cylinder head plane,
• in which the pistons of the small cylinders of the second series are provided with a boss rectifying the form of the combustion chamber, said boss having at least one face substantially parallel to the cylinder head gasket plane,
• in which said face substantially parallel to the cylinder head gasket plane has an area equal to at least 60% to 90% of the area of the small cylinder of the second series, measured in the cylinder head gasket plane,
• in which the piston of the cylinders of the first series has a face substantially parallel to the cylinder head gasket plane, the said face having a hollow portion adapted to be opened onto a channel for one pair of cylinders, and
• in which the variably timed transmission is orientated around an end of the small crankshaft next to the engine flywheel.

A four-stroke internal combustion engine having the following successive phases:

• an intake phase, a compression phase, an expansion phase and an exhaust phase, said engine operating by a combustion selected from the group comprising of self-combustion, controlled ignition and combinations thereof, whereby said engine includes:
• a cylinder housing component having:
• a first series of cylinders, each having an axis and a diameter, and
• a second series of cylinders, each having an axis and diameter,
• whereby the cylinders of the first series haying a larger diameter than the diameter of the cylinders of the second series, and whereby the cylinder housing has an upper face along which the cylinders are open,
• a cylinder head part covering at least partly the upper face of the cylinder housing component, said cylinder head part being associated at least with inlet valves and exhaust valves at least for the first series of cylinders,
• a first series of pistons, each piston of said first series being adapted to be driven by an alternative movement in a cylinder of the first series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• a second series of pistons, each piston of said second series being adapted to be driven by an alternative movement in a cylinder of the second series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• whereby the displacement length of the piston of the cylinder of the first series is larger than the displacement length of the piston of the cylinder of the second series,
• a first crankshaft and a second crankshaft with rotational axes parallel to one another, the first crankshaft having a crank with a large stroke, whilst the second crankshaft has a crank with a small stroke, less than the large stroke of the crank of the first crankshaft, the said crankshafts being adapted to be coupled at the same rotational speed, by a gear train and a variably timed transmission;
• at least one variably timed transmission acting on an element selected from the group comprising of the crankshafts, pieces connected to the crankshafts and pieces of the gear train adapted for coupling the crankshafts at the same rotational speed, said variably timed transmission being adapted for adjusting at least a relative angular position between the crankshafts, said relative angular position between the crankshafts being defined by the angle formed between the crank of the first crankshaft and a line parallel to the crank of the second crankshaft and crossing the rotational axis of the first crankshaft;
• in which each piston, being associated with a connecting rod, is operated by a crank of a crankshaft, the crank with the small stroke of the second crankshaft operating the rod of the piston moving within the small cylinder, whilst the crank with the large stroke of the first crankshaft operates the rod of the piston moving within the large cylinder,
• in which the first series of cylinders is laid out above the first crankshaft, whilst the second series of cylinders is laid out above the second crankshaft,
• in which each cylinder of the first series communicates with at least one cylinder of the second series via a clearance space, in such a way as to form a pair of two cylinders communicating with one another to allow the gases to pass from one cylinder to the other, independently of the position of the pistons moving within the said cylinders,
• in which the upper face of the cylinder housing component is provided with channels forming distinct passages for each pair of cylinders, a channel for one pair of cylinders extending between a cylinder from the first series and a cylinder from the second series, whereby each channel for one pair of cylinders has a mean width determined along the upper face of between 0.5 and 0.8 times the mean of the diameters of the cylinders of the said pair of cylinders, and
• in which in which the variably timed transmission is controlled by a system comprising at least a guidance cylinder in direct contact adapted to monitor a phase angle difference between the short-stroke crankshaft of the second series of cylinders and the long-stroke crankshaft of the first series of cylinders.

A four-stroke internal combustion engine having the following successive phases:

• an intake phase, a compression phase, an expansion phase and an exhaust phase, said engine operating by a combustion selected from the group comprising of self-combustion, controlled ignition and combinations thereof, whereby said engine includes:
• a cylinder housing component having:
• a first series of cylinders, each having an axis and a diameter, and
• a second series of cylinders, each having an axis and diameter,
• whereby the cylinders of the first series having a larger diameter than the diameter of the cylinders of the second series, and whereby the cylinder housing has an upper face along which the cylinders are open,
• a cylinder head part covering at least partly the upper face of the cylinder housing component, said cylinder head part being associated at least with inlet valves and exhaust valves at least for the first series of cylinders,
• a first series of pistons, each piston of said first series being adapted to be driven by an alternative movement in a cylinder of the first series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• a second series of pistons, each piston of said second series being adapted to be driven by an alternative movement in a cylinder of the second series of cylinders along a displacement length each of said pistons being associated with a connecting rod,
• whereby the displacement length of the piston of the cylinder of the first series is larger than the displacement length of the piston of the cylinder of the second series,
• a first crankshaft and a second crankshaft with rotational axes parallel to one another, the first crankshaft having a crank with a large stroke, whilst the second crankshaft has a crank with a small stroke, less than the large stroke of the crank of the first crankshaft, the said crankshafts being adapted to be coupled at the same rotational speed, by a gear train and a variably timed transmission;
• at least one variably timed transmission acting on an element selected from the group comprising of the crankshafts, pieces connected to the crankshafts and pieces of the gear train adapted for coupling the crankshafts at the same rotational speed, said variably timed transmission being adapted for adjusting at least a relative angular position between the crankshafts, said relative angular position between the crankshafts being defined by the angle formed between the crank of the first crankshaft and a line parallel to the crank of the second crankshaft and crossing the rotational axis of the first crankshaft;
• in which each piston, being associated with a connecting rod, is operated by a crank of a crankshaft, the crank with the small stroke of the second crankshaft operating the rod of the piston moving within the small cylinder, whilst the crank with the large stroke of the first crankshaft operates the rod of the piston moving within the large cylinder,
• in which the first series of cylinders is laid out above the first crankshaft, whilst the second series of cylinders is laid out above the second crankshaft,
• in which each cylinder of the first series communicates with at least one cylinder of the second series via a clearance space, in such a way as to form a pair of two cylinders communicating with one another to allow the gases to pass from one cylinder to the other, independently of the position of the pistons moving within the said cylinders,
• in which the upper face of the cylinder housing component is provided with channels forming distinct passages for each pair of cylinders, a channel for one pair of cylinders extending between a cylinder from the first series and a cylinder from the second series, whereby each channel for one pair of cylinders has a mean width determined along the upper face of between 0.5 and 0.8 times the mean of the diameters of the cylinders of the said pair of cylinders, and
• in which the variably timed transmission comprises a control mechanism adapted to vary a relative lead angle between the crank of the second crankshaft and the crank of the first crankshaft, by means of a hydraulic force amplifier having a controlled thrustor acting on the variably timed transmission, said transmission altering at the end of the compression phase of the piston in the larger cylinder, the compression ratio of the engine between a minimum and a maximum, said minimum and maximum compression ratios depending on:
• a) the ratio between the displacement of the larger cylinder and the displacement of the smaller cylinder, and
• b) the ratio between, on the one hand, the total volume of the smaller cylinder and the larger cylinder and between, on the other hand, the volume of the clearance space and an additional volume created in the smaller cylinder at the end of the compression phase of the piston in the larger cylinder, the variably timed transmission adjusting the lead angle between the crank of the second crankshaft and the crank of the first crankshaft, so as to obtain said compression ratios, said lead angle varying between a maximum so that an angle of at least 90° is obtained between the connecting rod of the piston in the smaller cylinder and the crank of the second crankshaft, at the end of the compression phase of the piston in the larger cylinder, in order to define the minimum compression ratio, and a minimum so that the lead angle corresponds, at the end of the compression phase of the piston in the larger cylinder, to the appropriate position of the piston in the smaller cylinder to create the additional volume required to obtain the maximum compression ratio, the crank of the second crankshaft forming an angle with the connecting rod of the piston in the smaller cylinder.

A four-stroke internal combustion engine having the following successive phases:

• an intake phase, a compression phase, an expansion phase and an exhaust phase, said engine operating by a combustion selected from the group comprising of self-combustion, controlled ignition and combinations thereof, whereby said engine includes:
• a cylinder housing component having:
• a first series of cylinders, each having an axis and a diameter, and
• a second series of cylinders, each having an axis and diameter,
• whereby the cylinders of the first series having a larger diameter than the diameter of the cylinders of the second series, and whereby the cylinder housing has an upper face along which the cylinders are open,
• a cylinder head part covering at least partly the upper face of the cylinder housing component, said cylinder head part being associated at least with inlet valves and exhaust valves at least for the first series of cylinders,
• a first series of pistons, each piston of said first series being adapted to be driven by an alternative movement in a cylinder of the first series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• a second series of pistons, each piston of said second series being adapted to be driven by an alternative movement in a cylinder of the second series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• whereby the displacement length of the piston of the cylinder of the first series is larger than the displacement length of the piston of the cylinder of the second series,
• a first crankshaft and a second crankshaft with rotational axes parallel to one another, the first crankshaft having a crank with a large stroke, whilst the second crankshaft has a crank with a small stroke, less than the large stroke of the crank of the first crankshaft, the said crankshafts being adapted to be coupled at the same rotational speed, by a gear train and a variably timed transmission;
• at least one variably timed transmission acting on an element selected from the group comprising of the crankshafts, pieces connected to the crankshafts and pieces of the gear train adapted for coupling the crankshafts at the same rotational speed, said variably timed transmission being adapted for adjusting at least a relative angular position between the crankshafts, said relative angular position between the crankshafts being defined by the angle formed between the crank of the first crankshaft and a line parallel to the crank of the second crankshaft and crossing the rotational axis of the first crankshaft;
• in which each piston, being associated with a connecting rod, is operated by a crank of a crankshaft, the crank with the small stroke of the second crankshaft operating the rod of the piston moving within the small cylinder, whilst the crank with the large stroke of the first crankshaft operates the rod of the piston moving within the large cylinder,
• in which the first series of cylinders is laid out above the first crankshaft, whilst the second series of cylinders is laid out above the second crankshaft,
• in which each cylinder of the first series communicates with at least one cylinder of the second series via a clearance space, in such a way as to form a pair of two cylinders communicating with one another to allow the gases to pass from one cylinder to the other, independently of the position of the pistons moving within the said cylinders, and
• in which the upper face of the cylinder housing component is provided with channels forming distinct passages for each pair of cylinders, a channel for one pair of cylinders extending between a cylinder from the first series and a cylinder from the second series, whereby each channel for one pair of cylinders has a mean width determined along the upper face of between 0.5 and 0.8 times the mean of the diameters of the cylinders of the said pair of cylinders,
• in which the crank of the first crankshaft of the first series of cylinders passes tbrough a top dead centre and a bottom dead centre during its rotation, in which the two crankshafts of the first and second series of cylinders are arranged to define a minimum working space for the two crankshafts, in such a way that a minimal ratio is obtained between the displacements of two paired cylinders and in which the variably timed transmission travels between a start-of-travel position and an end-of-travel position, the minimum compression ratio of the paired cylinders being obtained at the end-of-travel of the variably timed transmission and calculated according to the following formula:
• V
• ⁢
• ⁢
• 1
• +
• [
• V
• ⁢
• ⁢
• 2
• -
• Vr
• (
• α
• ⁢
• ⁢
• maximum
• )
• ]
• +
• ve
• ve
• +
• Va
• ⁡
• (
• αmaximum
• )
• =
• P
• ⁢
• ⁢
• minimum
• in which
• V1:
• displacement of the larger cylinder of the paired cylinders;
• V2:
• displacement of the smaller cylinder of the paired cylinders
• Ve:
• volume of the clearance space of the paired cylinders required for gas transfer between the cylinders, without excessive lamination;
• (α maximum):
• lead angle of the crank of the second crankshaft, at the end-of-travel of the variably timed transmission;
• Vr(α maximum):
• compressed air volume at the end-of-travel of the variably timed transmission, defined by the lead angle of the crank of the second crankshaft, when the crank of the first crankshaft is located at its bottom dead centre, at the end of the intake phase;
• Va(α maximum):
• additional volume added to the clearance space volume, at the end-of-travel of the variably timed transmission, defined by the lead angle of the crank of the second crankshaft, when the crank of the first crankshaft is located at its top dead centre, at the end of the compression phase, and
• in which the variably timed transmission includes three superimposed concentric elements, namely an internal element made up of a transmission shaft, an external element made up of a sleeve carrying a gear for the coupling of the two crankshafts, and an intermediate element positioned between the said internal and external elements and made up of a tube which is sliding in relation to the said internal and external elements, the sleeve being maintained in a bearing plate, by means of a bearing,
• in which the second crankshaft has a shaft, one end of which is abutting with one end of the transmission shaft, the said ends having corresponding male and female splines to make it possible to couple them, and the three elements are self-centred in relation to the shaft of the second crankshaft during the fastening of the bearing plate onto an orifice of the cylinder housing, allowing for the removal of the transmission without removing the second crankshaft,
• in which a bearing housing carries a fastening ring forming a seating for an external ring of a bearing, said bearing having an internal ring fastened onto the sleeve in such a way as to maintain the transmission shaft,
• in which a spacer extends between the internal ring of the bearing and the internal ring of the bearing, this spacer compensating for the separation space between the said rings and axially maintaining the bearing ring of the bearing against a shoulder of the sleeve,
• in which a single nut ensures the fastening of the internal rings, of the bearings and of the spacer on the sleeve,
• in which the transmission shaft has, on the fastening ring side, straight splines onto which the sliding tube is engaged, having straight splines on its internal face, in such a way as to slide linearly on the transmission shaft,
• in which the sleeve has helical splines on its internal face,
• in which the sliding tube has one end permanently free outside the sleeve, the said end being interdependent with an internal ring of a two-row angular contact bearing, the said bearing having an external ring which is interdependent with a holding member on the cylinder, and
• in which the helical splines are arranged in such a way that the sliding tube, in being displaced outside the sleeve, reduces the angular feed of the crank of the second crankshaft in relation to the crank of the first crankshaft or vice versa.

A four-stroke internal combustion engine having the following successive phases:

• an intake phase, a compression phase, an expansion phase and an exhaust phase, said engine operating by a combustion selected from the group comprising of self-combustion, controlled ignition and combinations thereof, whereby said engine includes:
• a cylinder housing component having:
• a first series of cylinders, each having an axis and a diameter, and
• a second series of cylinders, each having an axis and diameter,
• whereby the cylinders of the first series having a larger diameter than the diameter of the cylinders of the second series, and whereby the cylinder housing has an upper face along which the cylinders are open,
• a cylinder head part covering at least partly the upper face of the cylinder housing component, said cylinder head part being associated at least with inlet valves and exhaust valves at least for the first series of cylinders,
• a first series of pistons, each piston of said first series being adapted to be driven by an alternative movement in a cylinder of the first series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• a second series of pistons, each piston of said second series being adapted to be driven by an alternative movement in a cylinder of the second series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• whereby the displacement length of the piston of the cylinder of the first series is larger than the displacement length of the piston of the cylinder of the second series,
• a first crankshaft and a second crankshaft with rotational axes parallel to one another, the first crankshaft having a crank with a large stroke, whilst the second crankshaft has a crank with a small stroke, less than the large stroke of the crank of the first crankshaft, the said crankshafts being adapted to be coupled at the same rotational speed, by a gear train and a variably timed transmission;
• at least one variably timed transmission acting on an element selected from the group comprising of the crankshafts, pieces connected to the crankshafts and pieces of the gear train adapted for coupling the crankshafts at the same rotational speed, said variably timed transmission being adapted for adjusting at least a relative angular position between the crankshafts, said relative angular position between the crankshafts being defined by the angle formed between the crank of the first crankshaft and a line parallel to the crank of the second crankshaft and crossing the rotational axis of the first crankshaft;
• in which each piston, being associated with a connecting rod, is operated by a crank of a crankshaft, the crank with the small stroke of the second crankshaft operating the rod of the piston moving within the small cylinder, whilst the crank with the large stroke of the first crankshaft operates the rod of the piston moving within the large cylinder,
• in which the first series of cylinders is laid out above the first crankshaft, whilst the second series of cylinders is laid out above the second crankshaft,
• in which each cylinder of the first series communicates with at least one cylinder of the second series via a clearance space, in such a way as to form a pair of two cylinders communicating with one another to allow the gases to pass from one cylinder to the other, independently of the position of the pistons moving within the said cylinders, and
• in which the upper face of the cylinder housing component is provided with channels forming distinct passages for each pair of cylinders, a channel for one pair of cylinders extending between a cylinder from the first series and a cylinder from the second series, whereby each channel for one pair of cylinders has a mean width determined along the upper face of between 0.5 and 0.8 times the mean of the diameters of the cylinders of the said pair of cylinders,
• whereby said engine is a four-stroke internal combustion engine, said engine further comprising an oil sump positioned beneath the crankshaft of the cylinders of the first series, while the crankshaft of the pistons of the cylinders of the second series is enclosed in the cylinder housing above one face of the housing and at a level located above the oil sump, the said face being inclined towards the oil sump, said inclined face of the cylinder housing being advantageously fitted with an access panel for the crankshaft of the pistons of the cylinders of the second series.

A four-stroke internal combustion engine having the following successive phases:

• an intake phase, a compression phase, an expansion phase and an exhaust phase, said engine operating by a combustion selected from the group comprising of self-combustion, controlled ignition and combinations thereof, whereby said engine includes:
• a cylinder housing component having:
• a first series of cylinders, each having an axis and a diameter, and
• a second series of cylinders, each having an axis and diameter,
• whereby the cylinders of the first series having a larger diameter than the diameter of the cylinders of the second series, and whereby the cylinder housing has an upper face along which the cylinders are open,
• a cylinder head part covering at least partly the upper face of the cylinder housing component, said cylinder head part being associated at least with inlet valves and exhaust valves at least for the first series of cylinders,
• a first series of pistons, each piston of said first series being adapted to be driven by an alternative movement in a cylinder of the first series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• a second series of pistons, each piston of said second series being adapted to be driven by an alternative movement in a cylinder of the second series of cylinders along a displacement length, each of said pistons being associated with a connecting rod,
• whereby the displacement length of the piston of the cylinder of the first series is larger than the displacement length of the piston of the cylinder of the second series,
• a first crankshaft and a second crankshaft with rotational axes parallel to one another, the first crankshaft having a crank with a large stroke, whilst the second crankshaft has a crank with a small stroke, less than the large stroke of the crank of the first crankshaft, the said crankshafts being adapted to be coupled at the same rotational speed, by a gear train and a variably timed transmission;
• at least one variably timed transmission acting on an element selected from the group comprising of the crankshafts, pieces connected to the crankshafts and pieces of the gear train adapted for coupling the crankshafts at the same rotational speed, said variably timed transmission being adapted for adjusting at least a relative angular position between the crankshafts, said relative angular position between the crankshafts being defined by the angle formed between the crank of the first crankshaft and a line parallel to the crank of the second crankshaft and crossing the rotational axis of the first crankshaft;
• in which each piston, being associated with a connecting rod, is operated by a crank of a crankshaft, the crank with the small stroke of the second crankshaft operating the rod of the piston moving within the small cylinder, whilst the crank with the large stroke of the first crankshaft operates the rod of the piston moving within the large cylinder,
• in which the first series of cylinders is laid out above the first crankshaft, whilst the second series of cylinders is laid out above the second crankshaft,
• in which each cylinder of the first series communicates with at least one cylinder of the second series via a clearance space, in such a way as to form a pair of two cylinders communicating with one another to allow the gases to pass from one cylinder to the other, independently of the position of the pistons moving within the said cylinders, and
• in which the upper face of the cylinder housing component is provided with channels forming distinct passages for each pair of cylinders, a channel for one pair of cylinders extending between a cylinder from the first series and a cylinder from the second series, whereby each channel for one pair of cylinders has a mean width determined along the upper face of between 0.5 and 0.8 times the mean of the diameters of the cylinders of the said pair of cylinders,
• whereby said engine is a four-stroke internal combustion engine, whereby the cylinder housing comprises a coupling housing part, and whereby the engine further comprises an oil sump located beneath the cylinder housing.

A machine comprising a four-stroke internal combustion engine having an intake phase, a compression phase, an expansion phase and an exhaust phase, said engine operating by self-combustion or by controlled ignition, including:

• a cylinder housing component having a first series of cylinders, each having an axis and a diameter, and a second series of cylinders (3), each having an axis and diameter, the cylinders (2) of the first series having a larger displacement and diameter than the displacement and the diameter of the cylinders (3) of the second series (3),
• pistons (6,8), each piston being adapted to be driven by an alternative movement in a cylinder and being associated with a connecting rod,
• two crankshafts with rotational axes parallel to one another, a first crankshaft (4) having a crank with a large stroke, whilst a second crankshaft (5) has a crank with a small stroke, less than the long stroke of the crank of the first crankshaft, the said crankshafts (4,5) being adapted to be coupled at the same rotational speed, by at least a gear train (14,16),
• at least one variably timed transmission (10) acting on an element selected from the group comprising of the crankshafts, pieces connected to the crankshafts and pieces of the gear train adapted for coupling the crankshafts at the same rotational speed, said variably timed transmission being adapted for adjusting at least a relative angular position between the crankshafts, said relative angular position between the crankshafts being defined by the angle formed between the crank of the first crankshaft and a line parallel to the crank of the second crankshaft and crossing the rotational axis of the first crankshaft;
• in which each piston, being associated with a connecting rod (7,9), is operated by a crank of a crankshaft, the short-stroke handle of the second crankshaft (5) operating the rod (9) of the piston (8) moving within the small cylinder (3), whilst the large-stroke crank of the first crankshaft (4) operates the lever (7) of the piston (6) moving within the large cylinder (2),
• in which the first series of cylinders (2) is laid out above the first crankshaft (4), whilst the second series of cylinders (3) is laid out above the second crankshaft (5),
• in which each cylinder (2) of the first series communicates with at least one cylinder (3) of the second series via a clearance space, in such a way as to form a pair of two cylinders (2,3) communicating with one another to allow the gases to pass from one cylinder to the other, independently of the position of the pistons (6,8) moving within the said cylinders (2,3),
• in which the cylinder housing component displays a face along which the cylinders are open, channels being formed in the said face to form distinct passages for each pair of cylinders, a channel for one pair of cylinders extending between a large cylinder from the first series and a small cylinder from the second series, said channel having a width determined at said face selected from the group comprising of a mean width and a minimal width of between 0.5 and 0.8 times the mean of the diameters of the cylinders connected by the said channel, and
• in which the variably timed transmission includes an element selected from the group comprising of a tube and a shaft, said element sliding axially in relation to the rotational axis of the crankshaft of the pistons of the cylinders of the second series for generating a movement travel of the variably timed transmission, the engine comprising at least one stop means to limit the movement travel of the variably timed transmission between a start-of-stroke and an end-of-stroke.