Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B75/00—Other engines
  • F02B75/28—Engines with two or more pistons reciprocating within same cylinder or within essentially coaxial cylinders
  • F02B75/285—Engines with two or more pistons reciprocating within same cylinder or within essentially coaxial cylinders comprising a free auxiliary piston
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
  • F01B31/00—Component parts, details, or accessories not provided for in, or of interest apart from, other groups
  • F01B31/14—Changing of compression ratio
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01B—MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
  • F01B7/00—Machines or engines with two or more pistons reciprocating within same cylinder or within essentially coaxial cylinders
  • F01B7/16—Machines or engines with two or more pistons reciprocating within same cylinder or within essentially coaxial cylinders with pistons synchronously moving in tandem arrangement
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B75/00—Other engines
  • F02B75/04—Engines with variable distances between pistons at top dead-centre positions and cylinder heads
  • F02B75/044—Engines with variable distances between pistons at top dead-centre positions and cylinder heads by means of an adjustable piston length

Definitions

• the invention relates to internal combustion engines, and in particular piston engines having a combustion chamber whose displacement or volumetric ratio is variable.
• the maximum energy efficiency of piston internal combustion engines is generally recorded at full load, that is to say when the throttle valve is fully open, and the engine speed where the average effective cycle pressure. motor is at its maximum value. At these operating conditions correspond, for each engine, a power and a defined speed value.
• the engine speed of a motor vehicle varies very frequently during urban use.
• Power and maximum efficiency are strongly influenced by engine displacement.
• the consumption of high displacement engines is particularly high, they being placed in operating conditions far removed from their optimal conditions.
• the high-capacity engines have better use in other operating conditions, for example on high speed motorway journeys.
• a motor of a given displacement is frequently used in conditions of use for which it is not optimized.
• the power and the maximum efficiency regime are also strongly influenced by the volumetric ratio, that is to say the ratio between the volume of the combustion chamber at top dead center and the volume of the combustion chamber at the top. bottom dead point.
• the volumetric ratio is defined taking into account the maximum load conditions of the engine and the fuel used. However, at partial load, this volumetric ratio is too low to ensure optimal energy efficiency.
• variable distribution solutions make it possible to limit the air load at low speed and to optimize it at high speed.
• Another solution proposes to interrupt the ignition of some cylinders with intermediate charges.
• Another solution proposes cylinder liners selectively coupling to the cylinder or to an outer jacket to modify the displacement of the engine.
• Another solution has a connecting rod of variable length.
• Another solution modifies the volumetric ratio by moving the high casing relative to the low casing.
• US70661 18 discloses a combustion engine with variable volumetric ratio.
• This engine comprises a piston provided with an inner member and an outer member.
• the outer member of the piston is slidably guided in an axial direction by a cylinder liner.
• the upper face of the outer element delimits the lower part of the combustion chamber.
• the inner member of the piston is slidably mounted axially inside the outer member.
• the internal piston element is connected to a connecting rod.
• a cam mechanism is interposed between the inner member and the outer member and changes their relative axial positions.
• the cam mechanism includes inclined faces driven in rotation about the axial direction. These inclined faces are in contact with inclined faces of the outer member. The relative rotation between these inclined faces thus leads to an axial displacement of the external element.
• the cam mechanism is actuated by a hydraulic circuit comprising a conduit formed inside the connecting rod. The volumetric ratio is increased when the outer member is moved away from the inner member.
• the invention aims to solve one or more of these disadvantages.
• the invention thus relates to an internal combustion engine, comprising:
• a first piston guided in axial sliding in the cylinder and secured to a transmission mechanism
• said transmission mechanism comprises a rod articulated on the first piston.
• the first piston describes a back-and-forth movement between a top dead center and a bottom dead center
• the means for introducing a variable volume of fluid are constituted by an associated pipe provided with means to interrupt the flow of fluid, opening into the cylinder.
• the engine comprises a first conduit dedicated to the admission of the fluid into the control chamber and a second conduit dedicated to the discharge of the fluid out of the control chamber.
• the first piston describes a movement back and forth between a top dead center and a bottom dead center, the pipe or lines for the admission and the discharge of the fluid open into the cylinder in an area facing the control chamber when the first piston is in its bottom dead center.
• the engine further comprises means for guiding the second piston, to maintain it perpendicular to the axis of the cylinder.
• the second piston is free, its movement resulting solely from the forces exerted on the one hand by the gases present in the combustion chamber defined by the cylinder head and said second piston and on the other hand by the first piston, through the control chamber.
• the engine further comprises return means linking the two pistons.
• the motor further comprises means forming stops defining a space.
• first and second pistons are each provided with at least one sealing segment.
• the engine further comprises means for detecting the position of the second piston.
• openings are drilled in the second piston to put in fluid communication the control chamber and the combustion chamber between the second piston and the cylinder head.
• the second piston is in abutment on the cylinder head.
• the engine according to the invention may be of the spark ignition type, or configured to achieve compression ignition of a mixture present in the combustion chamber between the second piston and the cylinder head.
• the present invention also relates to a control method of a combustion engine, adapted to allow a modification of the displacement or volumetric ratio.
• a control method of an internal combustion engine comprising a cylinder head, a cylinder defined axially by the cylinder head, a first piston guided in axial sliding by the cylinder and intended to drive.
• a transmission mechanism comprising a crankshaft via a connecting rod, a second piston disposed between the cylinder head and the first piston, the second piston being guided in axial sliding by the cylinder and axially movable relative to the first piston, a chamber control system separating the first and second pistons, characterized by a step of controlled introduction of a fluid into said control chamber.
• “Rear” of the piston is preferably a compressible fluid, such as a gas, more particularly such fresh air taken for example from the engine intake circuit. As this air is then compressed by the method according to the invention, it can advantageously be used as such for the intake of fresh air from the engine.
• the compressible fluid is an exhaust gas.
• the method advantageously comprises the controlled introduction of fluid when the piston is substantially at the bottom dead center at the end of the intake phase.
• the method according to the invention is applied to a four-stroke engine and comprises the steps of introducing a fuel mixture into the combustion chamber between the piston and the engine.
• cylinder head (during an intake phase; introduction of a determined volume of exhaust gas into a control chamber interposed between the piston and the transmission mechanism, when the piston is substantially at the bottom dead center at the end of the phase intake of embodiment of performing the ignition of the fuel mixture when the piston is substantially at the top dead center and discharge of the exhaust gas out of the control chamber when the piston is substantially at the bottom dead center at the end of the phase of relaxation.
• the volume of fluid acting on the face of the piston opposite the cylinder head is measured and regulated as a function of a set value of fluid quantity.
• the method also comprises determining at least one parameter among the engine speed, the engine load, the position of the piston in its engine cycle, the volume of fluid acting. on the face of the piston opposite to the cylinder head, the pressure in a combustion chamber between the piston and the cylinder head and the flow rate of air admitted to the chamber, and wherein the introduction of fluid is controlled according to the determined parameter.
• the step of controlled introduction of a fluid into said control chamber is conducted to modify the volumetric ratio of the engine and in that said fluid is incompressible.
• the fluid is oil, in particular the engine lubricating oil - in which case it may be advantageous to provide an oil tank with a volume greater than one. conventional oil tank.
• the introduction of the fluid is preferably carried out when the piston is substantially at the bottom dead center at the end of the intake phase and the discharge of the fluid is on the other hand when the piston is substantially at the bottom dead center at the end of the relaxation phase.
• the volume of fluid acting on the face of the piston opposite to the cylinder head is measured and regulated as a function of a fluid quantity set point value.
• the method also comprises determining at least one parameter among the engine speed, the engine load, the position of the piston in its engine cycle, the volume of fluid acting. on the face of the piston opposite to the cylinder head, the pressure in a combustion chamber between the piston and the cylinder head and the flow rate of air admitted to the chamber, and wherein the introduction of fluid is controlled according to the determined parameter.
• the methods according to the invention which make it possible to modify the displacement or the volumetric ratio of a combustion engine apply both to the engines whose fuel mixture introduced into the combustion chamber, between the piston and the cylinder head. , is ignited in a controlled manner (typically with a spark plug or engine called “gasoline”), or is ignited by compression (engine called “diesel”).
• FIG. 1 is a diagrammatic sectional view of a first embodiment of an engine according to the invention
• FIGS 2 to 4 are sectional views showing different phases of operation of the motor of Figure 1;
• FIG. 5 is a sectional view of a first variant of the motor of FIG. 1;
• FIG. 6 is a sectional view of a second variant of the engine of FIG. 1;
• FIG. 7 is a sectional view of a third variant of the engine of FIG. 1;
• FIG. 8 is a sectional view of a fourth variant of the engine of FIG. 1;
• FIGS. 9 to 11 are sectional views of a second embodiment of an engine according to the invention, illustrating the operation during a reduction of the displacement;
• FIGS. 12 to 14 are sectional views of the second embodiment, illustrating the operation during a displacement increase
• FIGS. 15 to 20 are sectional views of a third embodiment of an engine, illustrating its operation during different phases.
• the cubic capacity is defined by the difference in the volume of the combustion chamber between the bottom dead center and the top dead center of the piston.
• the volumetric ratio is defined as the ratio between the volume of the combustion chamber at the bottom dead point and the volume of the combustion chamber at top dead center.
• the invention proposes placing two pistons guided in axial sliding inside a cylinder.
• the first of the two pistons is secured to a transmission mechanism.
• a control chamber separates the two pistons.
• the control chamber has a variable volume and means allow to introduce a controlled manner a fluid in the control chamber between the two pistons.
• the filling level of the control chamber and allows to vary the cylinder capacity or the volumetric ratio of the cylinder by limiting the connections between the two pistons.
• This solution requires a reduced number of mechanical elements, which facilitates the assembly of the engine, reduces its overall cost and increases its reliability.
• the modifications made to the cubic capacity or to the volumetric ratio being made inside the cylinder itself these modifications can be implemented in a very short time, over a few engine cycles only.
• the invention is easily adaptable to motor structures broadcast in large series.
• the invention can be implemented in conjunction with other techniques such as direct injection, supercharging, exhaust gas recirculation or variable distribution.
• FIG. 1 is a schematic sectional view of a first embodiment of an internal combustion engine 1 according to the invention.
• the engine 1 comprises in known manner a cylinder block 2 in which a cylinder is formed to form a combustion chamber 21.
• the engine 1 also comprises a first piston 3 guided in axial sliding by the cylinder.
• the piston 3 is intended to drive a transmission mechanism comprising a crankshaft (not shown) via a connecting rod 6.
• the rod 6 is articulated on the first piston 3.
• the piston 3 thus comprises a shaft connecting rod 31 connected to the connecting rod 6.
• the connecting rod 6 is connected to a crankshaft.
• the engine 1 also comprises a second piston 4 disposed between a cylinder head 7 and the first piston 3.
• the piston 4 is guided in axial sliding by the cylinder.
• the piston 4 is axially movable relative to the first piston 3.
• a control chamber 22 separates the pistons 3 and 4 and has a variable volume.
• the second piston 4, the cylinder and the cylinder head 7 define the combustion chamber 21.
• the piston 4 is free, its movement resulting solely from the forces exerted on the one hand by the gases present in the combustion chamber 21 and on the other hand by the fluid present in the control chamber 22.
• the engine 1 also comprises a fluid inlet conduit 81 opening into the cylinder. In the position of the pistons 3 and 4 illustrated, the intake duct 81 opens into the control chamber 22.
• the piston 3 is here arranged at low dead point while the piston 4 is disposed in an intermediate axial position in the cylinder.
• the conduit 81 is intended to supply the control chamber 22 with incompressible fluid, such as for example oil, so that the displacement of the piston 4 relative to the piston 3 leads to modify the volumetric ratio of the cylinder.
• the engine 1 comprises an incompressible liquid supply 8 in communication with the conduit 81.
• the liquid will be advantageously insensitive to cavitation.
• the incompressible liquid may be engine lubricating oil, so that this fluid allows both control of the volume of the control chamber 22 and lubrication of the sliding between the pistons 3 and 4 and the cylinder. This oil is for example taken from a sump of engine oil.
• the engine 1 also comprises a control device 9 controlling the supply 8.
• the supply 8 is in this case carried out in the form of a pump.
• the engine 1 further comprises means for interrupting the flow of fluid opening into the cylinder, in the form of a valve 82 selectively closing the conduit
• the control device 9 controls the opening or closing of the valve
• the duct 81, the valve 82 and the control device 9 form means for the controlled introduction of the fluid into the control chamber 22, the invention being of course not limited to this particular example of means of control. introduction.
• the engine 1 also comprises a fluid discharge conduit 83 opening at the side wall of the cylinder.
• the duct 83 is in communication with the control chamber 22 during the stroke of the pistons 3 and 4.
• This duct 83 is selectively closed by a valve 84, the opening or closing of which is controlled by the control device 9.
• the engine is of the controlled ignition type.
• the cylinder head 7 of the engine illustrated comprises, in a manner known per se, an intake valve 71, an exhaust valve 72 and a controlled spark plug 73.
• the person skilled in the art will of course recognize that the shape of the cylinder head may be more specifically adapted, for example with a general dome shape, for such a controlled ignition, or modified in the case of compression ignition (so-called diesel type engine).
• the piston 3 is provided with a fire segment 32, a sealing segment 33 and a scraper segment 34.
• the fire section 33 is intended to maintain the incompressible liquid inside the chamber 22.
• the scraper segment 34 is intended to prevent engine oil present in the low engine from rising in the control chamber 22.
• the fire segment 32 normally used to prevent the spread of combustion flame to the low engine may possibly be omitted in the present case because of the presence of the control chamber, if it does not contain flammable fluid.
• the piston 4 is provided with a sealing segment 41.
• the segment 41 avoids a communication between the gas of the combustion chamber 21 and the incompressible liquid of the control chamber 22.
• a second segment, of cut type Fire can also be provided on this free piston.
• FIGS 2 to 4 illustrate different phases of operation of an engine including the engine of the first embodiment.
• FIG. 2 illustrates the end of an admission phase.
• the intake valve 71 is still open and the piston 3 is located at the bottom dead center.
• Exhaust valve 72 is closed.
• the control chamber 22 is then in communication with the ducts 81 and 83.
• the control device 9 controls an increase in the volumetric ratio.
• the valve 84 is closed to prevent the liquid from being discharged from the control chamber 22.
• the valve 82 is then opened to discharge incompressible liquid into the control chamber 22 and thus increase its volume.
• the piston 4 is thus spaced axially from the piston 3.
• the volume of the combustion chamber 21 is decreased accordingly.
• Figure 3 illustrates the ignition phase.
• the piston 3 is in top dead center.
• the piston 4 is kept away from the piston 3 by the liquid present in the control chamber 22.
• the volume of the combustion chamber 21 is then reduced.
• the valves 71 and 72 being closed, the mixture present in the combustion chamber 21 is compressed by the piston 4.
• the spark plug 73 ignites the compressed mixture.
• the valves 82 and 84 are closed, to avoid a discharge of the incompressible liquid in the low engine.
• the volume of the control chamber 22 is substantially constant during the stroke of the piston 3 between the bottom dead center and the top dead center.
• the piston 4 follows the axial stroke of the piston 3 during the compression phase.
• the volume of the combustion chamber 21 having been reduced by the same amount at the bottom dead point and the top dead center, it can easily be deduced that the volumetric ratio is increased during the increase of the volume of liquid in the chamber. 22.
• the volumetric ratio may in particular be increased when the engine is not at full load or operating at a speed below the maximum power mode.
• the displacement remains fixed, the volume swept by the piston 4 remaining defined by the stroke of the piston 3.
• FIG. 4 illustrates the end of the expansion phase, the piston 3 being at the bottom dead center.
• the control chamber 22 is again in communication with the ducts 81 and 83.
• the control device 9 controls a reduction of the volumetric ratio.
• the valve 82 is closed to prevent the liquid from being introduced into the control chamber 22.
• the valve 84 is then opened to discharge liquid out of the control chamber 22 and thus reduce its volume.
• the piston 4 is thus brought closer axially to the piston 3.
• the volume of the combustion chamber 21 is increased accordingly.
• the volumetric ratio is thus reduced.
• the volumetric ratio may especially be reduced at full load or at a speed corresponding to the maximum power of the engine.
• the decrease or increase of the volume of the control chamber 22 may be carried out gradually during several successive motor cycles.
• the decrease or the increase in the volume of the control chamber 22 can be achieved when the piston 3 is at the bottom dead center, either at the end of the intake phase, or at the end of the expansion phase.
• the filling of the control chamber 22 is performed at the end of admission, when the pressure in the combustion chamber 21 is low.
• the liquid is preferably discharged from the control chamber when the pressure in the combustion chamber 21 is higher, for example at the end of the expansion phase.
• the energy required to change the volume of the control chamber 22 is reduced.
• the volume of the liquid in the control chamber 22 can be regulated so as to take into account the liquid leaks at the level of the segmentation or the expansion of the liquid in the control chamber 22.
• FIG. 5 illustrates a variant of the first embodiment.
• a return member exerts a spreading force between the first and second pistons 3 and 4.
• Such a return member promotes the filling of the control chamber 22 by creating a vacuum in this control chamber.
• This return member is in the form of a helical spring 43.
• the radial position of the spring 43 is defined by studs 42 and 35 respectively formed in the pistons 4 and 3.
• the studs 42 and 35 project axially in the control chamber. 22.
• the duct 81 is used both for filling and discharging the control chamber 22. The pressure in the combustion chamber 21 during the expansion phase then makes it possible to discharge the control chamber 22 when the valve 82 is open.
• FIG. 6 illustrates another variant of the first embodiment.
• the piston 3 has a stop 37 and the piston 4 has a stop 45. These stops 37 and 45 cooperate to clamp the maximum spacing between the pistons 3 and 4. These 37 and 45 stops may also allow the piston 3 to recall the piston 4 during its race towards the bottom dead center.
• the stop 37 is formed in the form of a shoulder extending radially outwardly relative to the upper portion 36 of the piston 3.
• the stop 45 can be made in the form of a shoulder extending radially inwardly relative to a portion 44 projecting axially from a lower face of the piston 4.
• Figure 7 further illustrates a variant of the first embodiment. According to this variant, a third piston 5 is guided in axial sliding by the cylinder.
• This third piston 5 is disposed between the first and second pistons 3 and 4, inside the control chamber 22.
• the third piston 5 has perforations 51 communicating its upper and lower faces. Liquid can thus flow through the perforations 51.
• Helical springs 47 are moreover arranged between the pistons 4 and 5, thus urging them towards a position where they are separated from each other. The radial position of the springs 47 is defined by studs 46 formed on the lower face of the piston 4. A damping between the pistons 4 and 5 is thus achieved.
• the third piston 5 advantageously has a segment 52 at its periphery.
• Figure 8 illustrates another variant of the first embodiment.
• the piston 4 has a recess 48 and the piston 3 has a stud 38 of complementary shape to the recess 48.
• this fluid dampens the movements between the pistons 3 and 4 when they come close to the bottom dead center and the amount of fluid is reduced. Indeed, the evacuation of the fluid out of the recess 48 is then limited by the stud 38.
• this variant corresponds to a compression ignition engine.
• FIGS. 9 to 14 are schematic sectional views of a second embodiment of an internal combustion engine 1 according to the invention.
• the engine 1 comprises a cylinder block 2 similar to that of the first embodiment.
• the pistons 3 and 4 and the control chamber 22 formed between them are similar to the first embodiment.
• the piston 3 also comprises a connecting shaft connected to a connecting rod, in order to drive a crankshaft.
• the cylinder block 2 is overhung by a cylinder head 7 similar to that of the first embodiment.
• the engine 1 comprises an intake duct 85 opening into the cylinder. In the position of the pistons 3 and 4 illustrated in FIGS. 9 and 12, the conduit 85 opens into the control chamber 22.
• the engine 1 further comprises a valve 86 selectively closing the conduit 85.
• the conduit 85 is for supplying the control chamber 22 with gas, so compressible fluid.
• the conduit 85 is also intended for the gas discharge present in the control chamber 22.
• the displacement of the piston 4 relative to the piston 3 leads to modify the cylinder capacity in the cylinder, which corresponds to the volume swept by the upper face of the piston.
• the conduit 85 is in communication with a gas supply.
• a control device 9 controls the closing or the opening of the valve 86.
• Figures 9 to 1 1 illustrate the operation of the engine during a reduction in displacement.
• Figure 9 illustrates the end of an admission phase.
• the intake valve 71 is still open and the piston 3 is located at the bottom dead center.
• Exhaust valve 72 is closed.
• the control chamber 22 is then in communication with the conduit 85.
• the control device 9 controls a decrease in the displacement.
• the pressure of the gas supplied by the source being greater than the pressure of the gas in the control chamber 22, the opening of the valve 86 leads to the filling of the control chamber 22.
• the piston 4 is then axially spaced from the piston 3.
• the volume of the combustion chamber 21 is decreased accordingly.
• FIG 10 illustrates the ignition phase.
• the valve 86 is closed to prevent a flow of gas from the conduit 85 down the engine.
• the piston 3 is at the top dead center and the spark plug 73 ignites the mixture present in the combustion chamber 21. Due to the sliding assembly of the piston 4 with respect to the cylinder, the pressure between the combustion chamber 21 and the control chamber 22 balances. The spacing between the pistons 3 and 4 is thus reduced, because of the pressure in the combustion chamber 21 and the compressibility of the gas in the control chamber 22. The position of the piston 4 at the top dead center is therefore little changed by the filling of the control chamber 22. The stroke of the piston 4 is thus reduced, and consequently the The displacement is also reduced by the filling of the control chamber 22.
• the volumetric ratio in the cylinder is defined by the stroke of the piston 3 and is then substantially unchanged.
• Figure 1 1 illustrates the end of the expansion phase, the piston 3 being at the bottom dead center.
• the work generated by the combustion in the form of pressure is relayed by the gas of the control chamber 22, and transmitted to the piston 3.
• the valve 86 is closed in order to maintain the filling of the control chamber 22 with gas. Indeed, the pressure in the control chamber 22 at this time may be greater than the pressure of the gas supply.
• Figures 12 to 14 illustrate the operation of the engine during an increase in displacement.
• Figure 12 illustrates the end of the expansion phase, initially with the two valves closed and the piston 3 located at the bottom dead center.
• the control chamber 22 is then in communication with the conduit 85.
• the control device 9 controls an increase in the displacement.
• the conduit 85 is then connected to a low pressure zone in order to at least partially discharge the control chamber 22.
• the piston 4 is then brought closer to the piston 3.
• the volume of the combustion chamber 21 is increased accordingly.
• FIG 13 illustrates the ignition phase.
• the valve 86 is closed to prevent gas exchange between the conduit 85 and the low engine.
• the piston 3 is at the top dead center and the spark plug 73 ignites the mixture present in the combustion chamber 21.
• the spacing between the pistons 3 and 4 is reduced, because of the pressure in the combustion chamber 21 and the compressibility the gas still present in the control chamber 22.
• the stroke of the piston 4 is thus increased, and therefore the displacement is also increased by the discharge of the control chamber 22.
• the volumetric ratio in the cylinder is then substantially unchanged.
• Figure 14 illustrates the end of the expansion phase, the piston 3 being at the bottom dead center.
• the valve 86 is closed to prevent the filling of the control chamber 22 with gas.
• the displacement can be adapted to the desired amount of air to achieve combustion in the chamber 21.
• a gasoline engine one then obtains homogeneous stoichiometric combustion easy to post- treat, regardless of the point of engine operation. This is achieved without generating negative work during the low-pressure cycle of the motor cycle.
• the fluid used to change the filling of the control chamber 22 may be air.
• the gas is advantageously exhaust gas from the engine. Indeed, the exhaust gas has a heat capacity greater than that of air. The thermodynamic efficiency of the engine is thus improved.
• the duct 85 then forms a bypass from the exhaust duct - or an exhaust gas recirculation duct EGR said duct.
• control chamber 22 may be devoid of segments, to allow a slight gas communication between the control chamber 22 and the combustion chamber 21.
• Figures 15 to 20 illustrate a third embodiment, wherein the filling of the control chamber 22 with exhaust gas is used to compress the mixture of the combustion chamber 21.
• the engine 1 has a structure substantially identical to that of the second embodiment.
• the engine 1 has two ducts opening into the cylinder.
• the ducts are closed selectively by respective valves 87 and 88.
• the opening of the valves 87 and 88 is controlled by a control device 9.
• the ducts also communicate with an unillustrated exhaust gas discharge duct.
• FIG. 15 illustrates the beginning of an admission phase.
• the piston 3 descends from the top dead center.
• the intake valve 71 is open, which leads to the introduction of mixture in the combustion chamber 21.
• the valves 87 and 88 are closed.
• the control chamber 22 is substantially empty.
• FIG. 16 illustrates the beginning of a compression phase.
• the piston 3 is at the bottom dead center and the inlet valve 71 closes.
• the valve 87 is open and exhaust gases enter the control chamber 22.
• the piston 4 is then separated from the piston 3 and compresses the mixture present in the combustion chamber 21.
• Figure 17 illustrates the ignition phase.
• the piston 3 reaches the top dead center.
• the mixture is compressed in the combustion chamber 21 and ignited by the candle 73.
• the valves 87 and 88 are closed.
• Figures 18 and 19 illustrate the end of the relaxation phase.
• the piston 3 goes down to reach the bottom dead center.
• the valve 88 is open.
• the pressure in the combustion chamber 21 and the inertia of the piston 4 lead to the discharge of the gases out of the control chamber 22.
• FIG. 20 illustrates an escape phase. Pistons 3 and 4 go back to their top dead center.
• the exhaust valve 72 is open, which leads to the expulsion of the exhaust gas from the combustion chamber 21.
• the valves 87 and 88 are closed.
• the fluid used for filling the control chamber 22 is either a gas or an incompressible liquid.
• a depression or an overpressure can be generated in the combustion chamber 21 with respect to a conventional motor cycle, in order to suck or expel fluid in the control chamber 22.
• the depression or the overpressure can be generated. by means of a Variable distribution or by means of an intake phase-shifter creating a depression at the low dead point of admission.
• the shape of the piston 4 can be adapted to optimize its sliding in the cylinder.
• the piston 4 may in particular have an axially extending skirt.
• the piston 4 will thus be maintained perpendicular to the axis of the cylinder.
• the piston 4 may have a flat upper face, a bowl-shaped upper surface, or any other suitable surface depending on the type of motor.
• the piston 4 will be sized to withstand the thermomechanical stresses associated with combustion. By a choice of materials and a suitable shape, the piston 4 will have a relatively low mass.
• the piston 4 may have a single segment 41, for example using a segment as described in documents EP1719901 or US20060249913.
• the piston 4 illustrated has only one segment 41, the piston 4 may have a greater number of segments, for example including a scraper segment under the segment 41.
• the piston 4 may have openings in fluid communication with the control chamber 22 and the combustion chamber 21. This allows in particular to create turbulence in the fuel mixture present in the combustion chamber at top dead center, to increase the burning rate during ignition. The polluting emissions are then reduced and the overall efficiency of the cycle is improved.
• the piston 3 is not in contact with the combustion chamber 21.
• the piston 3 undergoes reduced mechanical and thermal stresses compared to a combustion engine piston according to the state of the art.
• the piston 3 can thus be lightened and have a shape promoting a reduction of friction with the cylinder.
• the piston 3 may also be provided with a single segment.
• the control device 9 may comprise probes that are not illustrated, establishing operating parameters of the motor, such as the engine speed, the load, the position of the first piston 3 or the crankshaft in the engine cycle, or the position of the second piston 4 in the cylinder.
• An electromagnetic sensor may in particular be arranged behind the wall of the cylinder, in order to determine a moment of passage of the piston 4. Sensors may also be installed to determine the gas pressure in the combustion chamber 21, the air flow admitted into the combustion chamber, or the flow of fluid entering or leaving the control chamber 22.
• the control device 9 may include a calculator determining commands for admission or discharge of the fluid present in the control chamber 22, depending the engine speed, the load and the position of the piston 3.
• the computer may also control the admission or discharge of the fluid depending on the fuel used for combustion.
• the calculator may in particular provide shutter or opening commands of the valves of the intake or discharge ducts.
• the duct 81, the valve 82 and the supply 8 can be integrated in the form of an injector. Furthermore, for a multicylinder engine, a common supply 8 for the different cylinders can be provided.
• the figures represent only one conduit for the fluid inlet and one conduit for the discharge of the fluid. The invention may also be implemented with several intake or discharge ducts.
• the ducts 81, 83, 85 of the illustrated examples open into a side wall of the cylinder, it is also possible to consider putting the control chamber 22 in communication with the fluid by other types of ducts. It can be envisaged that the duct passes through the connecting rod 6 and the upper part of the first piston 3.
• control chamber is essentially defined by a bladder, through which the movement of the piston will be transmitted to a connecting rod (in which case the rod may be hinged to a second piston as in the case proposed above or by any other medium but it does not necessarily need to be sealed, because it is only to guide the sliding of the piston in the cylinder).

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• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Output Control And Ontrol Of Special Type Engine (AREA)
• Lubrication Of Internal Combustion Engines (AREA)

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• 2008
  • 2008-10-09 EP EP08842745A patent/EP2201233A2/de not_active Withdrawn
  • 2008-10-09 WO PCT/FR2008/051831 patent/WO2009053621A2/fr active Application Filing

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