WO2024134333A1 - Système d'actionnement d'une soupape d'admission d'un moteur à combustion interne - Google Patents

Système d'actionnement d'une soupape d'admission d'un moteur à combustion interne Download PDF

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Publication number
WO2024134333A1
WO2024134333A1 PCT/IB2023/062228 IB2023062228W WO2024134333A1 WO 2024134333 A1 WO2024134333 A1 WO 2024134333A1 IB 2023062228 W IB2023062228 W IB 2023062228W WO 2024134333 A1 WO2024134333 A1 WO 2024134333A1
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WIPO (PCT)
Prior art keywords
cam
valve
intake
intake valve
intake valves
Prior art date
Application number
PCT/IB2023/062228
Other languages
English (en)
Inventor
Raffaele Ricco
Marcello Gargano
Original Assignee
C.R.F. Società Consortile Per Azioni
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Filing date
Publication date
Application filed by C.R.F. Società Consortile Per Azioni filed Critical C.R.F. Società Consortile Per Azioni
Publication of WO2024134333A1 publication Critical patent/WO2024134333A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
    • F01L9/10—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic
    • F01L9/11—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic in which the action of a cam is being transmitted to a valve by a liquid column
    • F01L9/12—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic in which the action of a cam is being transmitted to a valve by a liquid column with a liquid chamber between a piston actuated by a cam and a piston acting on a valve stem
    • F01L9/14—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic in which the action of a cam is being transmitted to a valve by a liquid column with a liquid chamber between a piston actuated by a cam and a piston acting on a valve stem the volume of the chamber being variable, e.g. for varying the lift or the timing of a valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
    • F01L13/0036—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/26—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
    • F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
    • F01L1/3442—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear using hydraulic chambers with variable volume to transmit the rotating force
    • F01L2001/34423—Details relating to the hydraulic feeding circuit
    • F01L2001/34446—Fluid accumulators for the feeding circuit
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
    • F01L2013/10—Auxiliary actuators for variable valve timing
    • F01L2013/105—Hydraulic motors

Definitions

  • the present invention regards an actuating system for an intake valve associated with a cylinder in an internal combustion engine according to the preamble of claim 1 .
  • the Applicant has long developed internal combustion engines equipped with a variable actuating system for the engine intake valves, marketed under the “Multi-air” brand, having the characteristics indicated above.
  • the same Applicant is the owner of various patents and patent applications relating to engines equipped with a system of the type specified above and to components of this system.
  • Figure 1 of the attached drawings shows a cross-sectional view of a cylinder head of an internal combustion engine according to the art described in document EP 0 803 642 B1.
  • the cylinder head illustrated in Figure 1 and indicated therein with the reference numeral 1 is applied to an inline four-cylinder engine, provided that the variable actuating system illustrated therein is of general application.
  • the head 1 comprises, for each cylinder, a cavity 2 formed in the base surface 3 of the head and defining the combustion chamber.
  • In the cavity 2 there are two intake ducts 4, 5 (duct 5 is illustrated with a dashed line) and two exhaust ducts 6 (only one of which is visible in the drawing).
  • the communication of the two intake ducts 4, 5 with the combustion chamber 2 is controlled by two traditional mushroom-type intake valves 7 (only one of which is visible in the figure), each comprising a stem 8 that is slidably mounted in the body of the head 1.
  • Each valve 7 is recalled towards the closed position by springs 9 interposed between an inner surface of the head 1 and a cup end 10 of the valve.
  • the communication of the two exhaust ducts 6 with the combustion chamber is controlled by two valves 70 (one of which is visible in the figure), also of a traditional type, which also have associated return springs towards the closed position.
  • each intake valve 7 is controlled, as described below, by a camshaft 11 rotatably mounted about an axis 12 within head supports 1 and comprising a plurality of cams 14 for actuating the intake valves 7 of the internal combustion engine.
  • Each cam 14 that controls an intake valve 7 cooperates with the plate 15 of a tappet 16 slidably mounted along an axis 17 which, in the case of the example illustrated in the aforementioned document, is substantially directed at 90° with respect to the axis of the valve 7.
  • the plate 15 is recalled against the cam 14 by a spring associated therewith.
  • the tappet 16 constitutes a pumping piston, or master piston, slidably mounted within a bushing 18 carried by a body 19 of a preassembled assembly 20 incorporating all the electrical and hydraulic devices associated with the actuation of the intake valves, according to that described in detail below.
  • a separate assembly 20 may be provided for each cylinder of the engine.
  • the master piston 16 is able to transmit a thrust to the stem 8 of the valve 7, in order to cause the valve to open against the action of the elastic means 9 by means of pressurized fluid (preferably oil coming from the lubrication circuit of the engine) present in a volume of pressurized fluid C to which the master piston 16 faces, and by means of a slave piston 21 slidably mounted within a cylindrical body constituted by a bushing 22, which is also carried by the body 19 of the preassembled assembly 20.
  • pressurized fluid preferably oil coming from the lubrication circuit of the engine
  • the volume of pressurized fluid C associated with each intake valve 7 can be made to communicate with an environment at a lower pressure, constituted by an exhaust channel 23, by means of a solenoid valve 24.
  • the channel 23 is configured to receive oil from the lubrication circuit of the engine, fed by the pump of the lubrication circuit, by means of a duct having one or more air purge siphons and a nonreturn valve (see, for example, EP-A-1 243 761 and EP-A-1 555 398 by the Applicant).
  • the solenoid valve 24 may be of any known type suitable for the function illustrated herein, and is controlled by electronic control means 25 according to signals S indicative of operating parameters of the engine and/or of the variable actuating system of the engine valves, such as the accelerator position and the number of engine revolutions, or the oil temperature or viscosity in the variable actuating system of the valves.
  • the solenoid of the solenoid valve 24 When the solenoid of the solenoid valve 24 is energized, the solenoid valve is closed, so as to maintain the volume of fluid C under pressure and to enable the actuation of each intake valve 7 by the respective cam 14, by means of the master piston 16, the slave piston 21 and the volume of oil contained therein.
  • the solenoid valve 24 When the solenoid of the solenoid valve 24 is de-energized, the solenoid valve opens so that the volume C enters into communication with the channel 23 and the pressurized fluid present in the volume C flows into that channel. Consequently, decoupling of the cam 14 and the master piston 16 from the intake valve 7 is obtained, which then returns quickly to its closed position under the action of the return springs 9.
  • the exhaust channels 23 of the various solenoid valves 24 all lead into the same longitudinal channel 26 communicating with pressure accumulators 270, one of which is visible in Figure 1.
  • Each accumulator is substantially constituted by a cylindrical body within which a piston is mounted, defining a chamber of the accumulator communicating with the low pressure environment defined by the exhaust channels 23, 26.
  • a helical spring inside the accumulator recalls the accumulator piston towards a position wherein the reception volume of the fluid inside the accumulator is minimal. If the solenoid valve 24 is opened at an instant wherein the master piston 16 is in a compression state of the fluid present in the volume C, part of the pressurized fluid present in the volume C flows towards the accumulator 270.
  • the master piston 16 with the associated bushing 18, the slave piston 21 with the associated bushing 22, the solenoid valve 24 and the channels 23, 26 are carried or formed in the aforesaid body 19 of the preassembled assembly 20 for the sake of speed and ease of assembly of the engine.
  • the exhaust valves 70 associated with each cylinder are traditionally controlled by a respective camshaft 28 through respective tappets 29, although in principle, the application of the variable actuating system to the exhaust valves is not excluded. This also applies to the present invention.
  • variable volume chamber defined within the bushing 22 and facing the slave piston 21 communicates with the volume of pressurized fluid C by means of an opening 30 formed in an end wall of the bushing 22.
  • This opening 30 is engaged by an end nose 31 of the piston 21 in order to implement the hydraulic braking of the movement of the valve 7 during closing, when the valve is next to the closed position, as the oil present in the variable volume chamber is forced to flow into the volume of pressurized fluid C by passing through the clearance existing between the end nose 31 and the wall of the opening 30 engaged therein.
  • the chamber of pressurized fluid C and the variable volume chamber of the slave piston 21 communicate with each other by means of internal passages formed in the body of the slave piston 21 and controlled by a non-return valve 32 that only allows the flow of fluid from the pressurized volume C to the variable volume chamber of the slave piston 21.
  • Various alternative embodiments of the hydraulic braking device of the slave piston 21 have been proposed in the past by the same Applicant (see, for example, EP-A-1 091 097 and EP-A-1 344 900).
  • the object of the hydraulic braking device is to avoid a strong impact (and consequent noise) of the valve 7 against its seat when the valve 7 returns rapidly to the closed position as a result of an early opening of the solenoid valve 24.
  • each intake valve may be controlled in “multi-lift” mode, that is, according to two or more repeated opening and closing “subcycles”. In each sub-cycle, the intake valve opens and then closes completely.
  • the electronic control unit is therefore able to obtain a change in the instant of opening and/or the instant of closing and/or the lift of the intake valve, as a function of one or more operative parameters of the engine. This allows maximum efficiency of the engine and the lowest fuel consumption, in all operating conditions.
  • a hydraulic clearance compensation device (“lash adjuster”) may be interposed between the slave piston 21 and the stem of the engine valve 7. This solution is, for example, described in the document EP-A-1 635 045 by the same Applicant.
  • Figure 1A shows, by way of example, the different lift profiles of an intake valve that can be achieved with the Multiair system; the outermost curve, indicated with N, represents the lift profile corresponding to the profile of the cam 14, i.e. the operating mode called “Full Lift”, wherein the control valve 24 never discharges the chamber C of pressurized fluid, so that the intake valve has a movement corresponding to the entire cam profile.
  • Figure 1 B shows the lift profile N, corresponding to the “Full Lift” case, and the EIVC lift profile corresponding to the case of early closing of the intake valve (“Early Intake Valve Closing”).
  • hybrid motor-vehicles of the type wherein the internal combustion engine is essentially dedicated to recharging the batteries powering the vehicle's electric traction motor, makes it increasingly convenient to create relatively simple internal combustion engines, with operation limited to a narrow portion of the quoted plane of the engine (the rpm - torque diagram), located around the point of maximum engine efficiency.
  • the rpm - torque diagram the rpm - torque diagram
  • engines of this type there is no need for variable actuation of the intake valves such as that which can be achieved with the “Multiair” system.
  • the same need for simplification may also exist in non-electric vehicles, where simple and low-cost solutions are to be preferred.
  • the implementation - using the Multiair device - of EIVC type strategies involves a loss of energy due to the failure to release the compression energy of the intake valve return spring.
  • the energy stored by the spring is proportional to the movement of the valve itself up to the position it reached immediately before closing: this loss, in some operating conditions, may be significant and nullify the reduction of the suction work in the cylinder allowed by the EIVC implementation.
  • Figure 1 C schematically shows what is illustrated above.
  • a mass M compresses a spring S following the engagement of the mass M against a cam P which, in the diagram, moves to the left (the spring S corresponds to the spring 9 and the mass M corresponds to the mass of the valve 7 in Figure 1 ).
  • the compression work is indicated in the lower part with a negative sign (-); during the final step of engagement with the cam, the spring returns the compression work (+) so that in this case there is no loss.
  • Another source of loss during an EIVC actuation, consists of the volume of oil pumped by the master piston, but allowed to flow back towards the discharge environment without being put under pressure: the amount of this volume is given by the difference of the integral subtended by the full lift curve and the integral of the area subtended by the EIVC curve.
  • this oil is not put under pressure, it represents a loss as the master piston must push it through a series of passages that introduce pressure losses, said loss being proportional to the volume sent to the discharge.
  • the ideal objective would be to have a relatively rapid opening movement of the intake valve, a maintenance of the open condition of the intake valve for a certain angular range of rotation of the crankshaft, and then a very rapid closing movement of the intake valve, limiting the movement of the intake valve as much as possible so as to reduce the compression work of the spring associated therewith.
  • a primary object of the present invention is to respond to this double need.
  • the object of the present invention is to improve the system proposed by the Applicant in the document WO 2022219440 A1 , in order to increase combustion efficiency and reduce harmful emissions.
  • the invention has as its object a system having the aforesaid characteristics known from the document WO 2022219440 A1 and further characterized in that said first cam has two lobes configured and arranged to cause a first opening period and a second opening period of the intake valve at each revolution of the cam, and in that said second cam also has two lobes configured and arranged in such a way as to cause the opening of the control valve and the consequent sudden closing of the intake valve, in advance compared to the closing of the intake valve which would be caused by the two lobes of the first cam.
  • control valve that controls the communication between the volume of pressurized fluid and the lower pressure environment is not a solenoid valve as in the case of the known “Multiair” system, but is a valve mechanically controlled by a dedicated cam, arranged on the camshaft.
  • the present invention is characterized in that, thanks to the provision of two lobes both on the first cam and on the second cam, the system is able to cause, at each revolution of the camshaft, a first opening period and a second opening period of the intake valve.
  • the two lobes of the first cam and the two lobes of the second cam are configured in such a way that: said first opening period of the intake valve of each cylinder begins substantially when the respective piston is at its TDC and ends when the respective piston is substantially halfway between its TDC and its BDC, wherein said second opening period of the intake valve of each cylinder is of a first type (2A) or of a second type (2B), wherein said second opening period of the first type (2A) begins when the piston has passed 4/5 of its path from TDC to BDC and has not yet reached its BDC, preferably at not more than 30° of crank angle before BDC, and at not less than 20° of crank angle before BDC, wherein said second opening period of the first type (2A) ends when the piston has passed the BDC and is in the process of rising towards the TDC, preferably at at least 20° of crank angle after the BDC, and at not more than 30° of crank angle after the BDC, wherein the second opening period of the second type (2B) starts
  • the device according to the invention is - in any case - compatible with other intake valve control devices, such as, for example, with phase variator devices - of any known type - suitable for varying the angular position of the camshaft relative to the crankshaft.
  • the first cam may be of the type known per se, comprising several axially offset profiles, which can be activated selectively.
  • control valve has a valve member which is normally in a closed position of the control valve and which is configured to be biased, directly or indirectly, by the aforesaid second cam towards an open position of the control valve.
  • the control valve may be of any known type, for example, of the “poppet valve” or “slide valve” type, with a movable member that can be moved between two operating positions wherein it closes or opens the communication between two inlets/outlets of the valve.
  • the first cam is configured for an opening of the intake valve substantially close to the Top Dead Center (TDC) of the mobile piston in the cylinder with which the intake valve is associated, and for a closing of the intake valve in advance of the Bottom Dead Center (BDC).
  • TDC Top Dead Center
  • BDC Bottom Dead Center
  • the slave piston of the intake valve actuation system is associated with a limiting device which discharges a hydraulic chamber containing the volume of fluid that activates the slave piston when the latter has moved by a predetermined distance, in such a way that the intake valve has a maximum lift which is reduced compared to the theoretical maximum lift caused by said first cam, and which remains constant for a given angular range of the crankshaft rotation, up to the crank angle value at which the intake valve suddenly closes due to the opening of the control valve.
  • the mechanical connection between the second cam and the moving member of the control valve is configured in such a way that the moving member of the control valve begins to move towards its open position after an initial lifting step of said second cam.
  • each intake valve is associated with a respective actuating system, with a respective first cam and a respective control valve: in this way it is possible to differentiate the laws of actuation of the intake valves.
  • the asymmetric actuation of the intake valves in particular at low engine speeds, allows the establishment of swirl motions in the combustion chamber which favor the mixing of the air charge with the fuel injected with direct injection and consequent reduction of particulate matter and hydrocarbons.
  • each of the two intake valves of the same cylinder is associated with a respective second cam for the mechanical control of the respective control valve, even if the possibility is not excluded of providing a single second cam for the actuation of the two control valves associated with the two intake valves of the same cylinder.
  • the ratio between the diameter of the master piston and the diameter of the slave piston (which is associated with the hydraulic brake of the corresponding intake valve) may be optimized to reduce said excursion by maximizing the opening speed of the intake valve.
  • a single first cam and a single second cam may be provided to simultaneously control the two intake valves associated with the same cylinder.
  • a single master piston may be provided to control the two slave pistons of the intake valves by means of a single volume of pressurized fluid which may be discharged by means of a single control valve.
  • the diameters of the slave pistons associated with the intake valves may have different values, so as to differentiate the opening profiles of the two intake valves.
  • different limiting devices may be provided, associated with the two slave pistons, so as to differentiate the maximum lift of the two intake valves.
  • the return springs towards the closed position of the two intake valves of each cylinder may have different characteristics, so as to differentiate the closing speed of the two intake valves.
  • the first cams are configured and arranged in such a way that one of the two intake valves of each cylinder opens after the other intake valve has already opened and closed again.
  • FIG. 1 is a cross-sectional view of a cylinder head of an internal combustion engine provided with a variable actuation system of the intake valve, according to the prior art illustrated in the document EP 0 803642 B1 and discussed above, - Figures 1A, 1 B, 1 C are diagrams, already discussed above, which illustrate operating modes of the known system,
  • FIG. 2 is a diagram of the actuation system according to the prior art from the document WO 2022219440 A1 of the Applicant,
  • FIG. 3 illustrate an embodiment example of the control valve used in the known system illustrated in the document WO 2022219440 A1 , in two different operating conditions,
  • FIG. 5 is a diagram showing the profiles of the first cam and the second cam forming part of the system known from the document WO 2022219440 A1 , and the lift diagram of the intake valve obtainable with this system, compared to the lift diagram of the intake valve in a conventional mechanical system,
  • FIG. 6 is a diagram showing the advantages of the system known from the document WO 2022219440 A1 .
  • FIG. 7 is a diagram of the system according to the present invention.
  • FIGS. 8-10 are diagrams showing the lift profiles of the intake valves of an engine cylinder, which can be achieved using the system according to the invention, in the case of application to an engine with two intake valves for each cylinder.
  • Figure 2 shows an intake valve 7 which is actuated by a slave piston 21 which receives pressurized fluid from a pressurized fluid chamber C following the pumping action of a master piston 16, which is actuated mechanically, directly or indirectly, by a cam 14A of a camshaft 11 .
  • the control valve 24, which controls the communication between the pressurized fluid chamber C and the reduced pressure environment, communicating with the pressure accumulator 270 is not an electrically-operated valve.
  • the valve 24 has a mobile member 24A which is mechanically controlled, directly or indirectly, by a dedicated cam 14B arranged on the camshaft 11 carrying the cams 11A for operating the intake valves.
  • Figures 3, 4 show the closed condition and the open condition of an embodiment example of the mechanical valve 24.
  • the valve 24 is a “poppet valve”, with a valve body 240 having an axial cavity 241 communicating with two openings 242, 243 connected, respectively, to the pressurized fluid chamber C and to the reduced pressure environment 270.
  • a septum 242 Inside the cavity 241 there is a septum 242 with an opening acting as a valve seat for a ball disc 245 pushed by a spring 246 towards a closing position of the valve seat.
  • a mobile member 247 slides in the cavity 241 with a pin 248 configured for pushing the ball disc 245 towards an open position of the valve seat, against the action of the spring 246 ( Figure 4) following a movement towards the bottom (with reference to the figures) of the mobile member 247.
  • the mobile member 247 has an end external to the valve body, indicated by 248, which is actuated, directly or indirectly (by means of a mechanical transmission of any known type) by the second cam 14B.
  • Figure 5 still refers to the known system of Figure 1 .
  • the line N shows the lift diagram of an intake valve in a conventional mechanical actuation system of the intake valves.
  • the diagram N shows the valve displacement as the crank angle varies.
  • the values of 360° and 540° in the diagram of Figure 5 correspond to the positions of TDC (Top Dead Center) and BDC (Bottom Dead Center) of the piston in the cylinder with which the intake valve is associated.
  • Diagrams A and B show the profiles of the first cam 14A and the second cam 14B, represented as a variation of the radial dimension of the cam as the crank angle varies.
  • the first cam 14A causes the opening of the intake valve associated therewith substantially at the TDC, and would cause a closure of the intake valve with a certain advance with respect to the BDC, in the example at approximately 490°.
  • the second cam 14B begins to intervene, causing a movement of the mobile member of the control valve 24 to its open position, which determines a rapid closing of the intake valve, in advance of the closure that would be dictated by the profile of the first cam 14A.
  • the diagram X indicates the lift profile of the intake valve obtainable with the system of Figure 2. As can be seen, from a point P where the intake valve starts opening to a point Q, the intake valve opens due to the hydraulic actuation by the master piston 16 caused by the first cam 14A.
  • the slope of the initial section of the curve X may be greater than the slope of the initial section of the curve (corresponding to the cam 14A), by appropriately sizing the ratio of the diameters of the master piston 16 and of the slave piston 21 (with which the hydraulic brake of the intake valve is associated).
  • the slave cylinder wherein the slave piston 21 is mobile is associated with an exhaust port 21 A, communicating with the low pressure environment 270, which discharges the volume of fluid that pushes the slave piston 21 when the slave piston 21 has completed a stroke H, corresponding to an identical opening stroke of the inspiration valve 7. Therefore, at point Q, before the intake valve 7 reaches the maximum lift that would derive from the profile A of the first cam 14A, the intake valve 7 stops and remains in this open position for a given angular range of the rotation of the crankshaft (in the example from about 400° to about 450°) up to a point R.
  • the mechanical transmission between the second cam 14B and the movable member of the control valve 24 is configured in such a way that the movable member 24A begins to move towards its open position only after the second cam 14B has reached its operating point Z in Figure 5, corresponding to a lift which - in the example - is approximately 0.2 cm.
  • the pressurized fluid discharges into the environment at reduced pressure and the intake valve 7 closes rapidly: this step corresponds to the section RS in the diagram X, which is almost vertical.
  • the system of Figure 2 is, therefore, capable of creating a substantially squared lift diagram X, with a relatively steep opening section, an intermediate section with constant opening, and an extremely steep closing section, which is optimal for the purposes of improving the efficiency of the engine and, in particular, for the purposes of increasing the combustion speed in the cylinder.
  • Figure 6 allows us to appreciate the advantages of the system of Figure 2 compared to the case of EIVC implementation with the Multiair system: the maximum opening of the valve is reduced by Ax and, consequently, the compression work of the spring 9 is lower and the compression work lost is lower when the motion of the valve is disconnected from the motion of the master piston 16, discharging the volume C. Furthermore, the overall volume of oil pumped by the master piston 16 (area subtended by curve A) is significantly reduced compared to that pumped in the Multiair case (area subtended by the curve N) and, therefore, the pressure loss associated with the leakage of said volumes through the different channels of the hydraulic circuit is significantly reduced.
  • the system achieves a drastic simplification and a reduction in losses in the case of EIVC actuations compared to the “Multiair” system according to the prior art, being intended for applications wherein the availability of a variable actuation of the intake valves is excessive, but at the same time gives rise to a control of the intake valves that would not be possible to obtain with a traditional mechanical cam drive.
  • each of said intake valves may be associated with an actuation system of the type described above, with a respective first cam, a respective second cam, a respective master piston and a respective slave piston, as well as a respective control valve: this configuration allows an asymmetric actuation of the intake valves and the possibility of generating air motions particularly favorable to improving the mixing of air and fuel and to increasing the turbulent kinetic energy.
  • each intake valve is also associated with a respective second cam for the mechanical actuation of the respective control valve, but the possibility of providing a single second cam 14B to control the two control valves 24 associated with the two intake valves of the same cylinder is not excluded.
  • the engine with a device, of a known type, with a cam 14A having an additional portion of different profile axially adjacent to the main portion, and which can be activated in certain engine operating conditions, so that the master piston 16 is actuated by this additional portion, so as to move the intake valve according to a curve of the type of curve N of Figure 5: in this case, therefore, the second cam 14B does not intervene and closing occurs according to a traditional method.
  • a single first cam and a single second cam may be also provided to simultaneously control the two intake valves associated with the same cylinder.
  • a single master piston may be expected to control the two slave pistons of the intake valves by means of a single volume of pressurized fluid, which can be discharged by means of a single control valve.
  • the diameters of the slave pistons associated with the intake valves may have different values, so as to differentiate the opening profiles of the two intake valves.
  • different limiting devices may be provided, which are associated with the two slave pistons, so as to differentiate the maximum lift of the two intake valves.
  • the return springs towards the closed position of the two intake valves of each cylinder may have different characteristics, so as to differentiate the closing speed of the two intake valves.
  • the first cams are configured and arranged in such a way that one of the two intake valves of each cylinder opens after the other intake valve has already opened and closed again.
  • Figure 7 illustrates a diagram of the system according to the present invention.
  • the system according to the invention differs from the known system of Figure 2 in that the first cam 14A has two lobes A1 , A2 configured and arranged to determine a first opening period and a second opening period of the intake valve 7 at each revolution of the cam, and in that the second cam 14B also has two lobes B1 , B2 configured and arranged in such a way as to cause the opening of the control valve 24, and the consequent sudden closing of the intake valve 7, in advance with respect to the closing of the intake valve, which would be caused by the two lobes A1 , A2 of the first cam 14A.
  • the two lobes A1 , A2 of the first cam 14A and the two lobes B1 , B2 of the second cam may be formed in one piece with the cam, or they may be part of separate and axially offset elements, rigidly connected in rotation with each other or with the camshaft 11 .
  • the system according to the invention may also be applied to an engine with a single intake valve per cylinder or to an engine with two intake valves per cylinder.
  • the two intake valves of the same cylinder may be controlled, by means of a common hydraulic circuit, by a single first cam, with which a single second cam is associated.
  • the two intake valves of the same cylinder may be controlled, by means of two respective hydraulic circuits, by two respective first cams, with which two respective second cams are associated.
  • the camshaft is associated with a phase variator device of any known type, capable of varying the angular position of the camshaft with respect to the crankshaft.
  • the first cam has several profiles that are axially offset and can be selectively activated, according to a known technique.
  • Figures 8-10 are diagrams showing the lift profiles of the intake valve, or of each intake valve, of an engine cylinder, achievable by the system according to the invention.
  • the two lobes A1 , A2 of the first cam 14A and the two lobes B1 , B2 of the second cam 14B are configured in such a way that:
  • the first period of opening of the intake valve, or of each intake valve, of each cylinder substantially begins when the respective piston is at its TDC and ends when the piston is substantially halfway between the TDC and the BDC (see for example curve 1 B in Figure 8, where the TDC corresponds to the 360° crank angle and the BDC corresponds to the 540° crank angle),
  • the second opening period of the intake valve, or of each intake valve, of each cylinder is of a first type (2A) or of a second type (2B).
  • the two types 2A and 2B of the second opening period of the intake valve are illustrated as an example in Figure 8 (see profiles 2A and 2B).
  • the second opening period begins when the piston has passed 4/5 of its path from TDC to BDC and has not yet reached its BDC, preferably at no more than 30° of crank angle before the BDC, and no less than 20° of crank angle before the BDC. Furthermore, in the case of the profile 2A of the first type, the second opening period of the intake valve ends when the piston has passed the BDC and is in the process of rising towards the TDC, preferably at least 20° of crank angle after the BDC, and no more than 30° of crank angle after the BDC.
  • the second opening period begins when the piston has passed the BDC and is in the process of rising towards the TDC, preferably at least 20° of crank angle after the BDC, and at no more than 30° of crank angle after the BDC. Furthermore, in the case of the profile 2B of the second type, the second opening period ends at at least 80° of crank angle after the BDC, and at no more than 100° of crank angle after the BDC.
  • Figure 8 of the attached drawings shows the lift profiles C1 , C2 which would be caused by the two lobes A1 , A2 of the first cam 14A, at the first opening period and the second opening period of the intake valve. Thanks to the intervention of the control valve 24, which can discharge the hydraulic circuit, in the first opening period the lift profile may become the profile 1 B, while in the second opening period the lift profile may become the profile 2A of the first type or the profile 2B of the second type.
  • a phase variator device can be provided associated with the camshaft, which controls the intake valve, capable of delaying the entire lift profile by approximately 40° of crank angle (obviously in this case the first opening would also be translated).
  • C is the lift profile that would be caused by a conventional type cam (with a single lobe)
  • 1 A, 1 B are the lift profiles in the first opening period before and after an intervention of the phase variator device
  • 2A, 2B are the two lift profiles of the second opening period before and after the intervention of the phase variator device.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve Device For Special Equipments (AREA)

Abstract

L'invention concerne un système d'actionnement d'une soupape d'admission associée à un cylindre d'un moteur à combustion interne, qui comprend un piston esclave (21) qui actionne la soupape d'admission (7) et qui est commandé hydrauliquement au moyen d'un volume de fluide sous pression (C) par un piston maître (16) entraîné par une première came (14A) d'un arbre à cames (11). Une soupape de commande (24) commande la communication entre un volume de fluide sous pression (C) et un environnement à pression inférieure auquel est raccordé un accumulateur de fluide (270). La soupape de régulation (24) est commandée mécaniquement par une seconde came (14B) portée par l'arbre à cames (11) et qui exerce la fonction unique de commande de la soupape de régulation (24). La première came (14A) comporte deux lobes (A1, A2) conçus et agencés pour déterminer une première période d'ouverture et une seconde période d'ouverture de la soupape d'admission (7) à chaque révolution de la came. La seconde came (14B) comporte deux lobes (B1, B2) conçus et agencés de manière à déterminer l'ouverture de la soupape de commande (24), et la fermeture subite conséquente de la soupape d'admission (7), avant la fermeture de la soupape d'admission, qui serait provoquée par les deux lobes (A1, A2) de la première came (14A).
PCT/IB2023/062228 2022-12-21 2023-12-05 Système d'actionnement d'une soupape d'admission d'un moteur à combustion interne WO2024134333A1 (fr)

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Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0803642B1 (fr) 1996-04-24 2000-11-15 C.R.F. Società Consortile per Azioni Moteur à combustion interne avec soupapes à commande variable
EP1091097A1 (fr) 1999-10-06 2001-04-11 C.R.F. Società Consortile per Azioni Ameliorations d'un dispositif de commande de soupape variable pour moteur à combustion interne
EP1243761A1 (fr) 2001-03-23 2002-09-25 C.R.F. Società Consortile per Azioni Moteur à combustion interne avec système hydraulique pour actionnement variable des soupapes et moyens pour compenser les variations de volume du fluide hydraulique
EP1344900A2 (fr) 2002-03-15 2003-09-17 C.R.F. Società Consortile per Azioni Moteur à combustion interne aux plusieurs cylindres avec commande des soupapes variable et dispositif à freinage aux soupapes
EP1555398A1 (fr) 2004-01-16 2005-07-20 C.R.F. Societa' Consortile per Azioni Moteur à combustion interne à simple arbre à cames commandant les soupapes d'échappement de façon mécanique, et les soupapes d'admission à l'aide d'un dispositif hydraulique à commande electronique
EP1635045A1 (fr) 2004-09-14 2006-03-15 C.R.F. Società Consortile per Azioni Moteur à combustion avec soupapes à réglage action variable avec des poussoirs à l'extérieur des actionneurs
EP1726790A1 (fr) 2005-05-24 2006-11-29 C.R.F. Societa' Consortile per Azioni Système et procédé de contrôle de la charge et de la combustion d'un moteur à combustion interne par un actionnement de soupape incluant plusieurs levées successives par cycle
US20160215661A1 (en) * 2015-01-26 2016-07-28 Jiangsu Gongda Power Technologies Co., Ltd. Engine valve actuation system
US20220010702A1 (en) * 2020-07-07 2022-01-13 Ford Global Technologies, Llc Systems and methods for providing compression release with continuous variable valve lift
WO2022219440A1 (fr) 2021-04-13 2022-10-20 C.R.F. Società Consortile Per Azioni Système d'actionnement d'une soupape d'admission d'un moteur à combustion interne

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0803642B1 (fr) 1996-04-24 2000-11-15 C.R.F. Società Consortile per Azioni Moteur à combustion interne avec soupapes à commande variable
EP1091097A1 (fr) 1999-10-06 2001-04-11 C.R.F. Società Consortile per Azioni Ameliorations d'un dispositif de commande de soupape variable pour moteur à combustion interne
EP1243761A1 (fr) 2001-03-23 2002-09-25 C.R.F. Società Consortile per Azioni Moteur à combustion interne avec système hydraulique pour actionnement variable des soupapes et moyens pour compenser les variations de volume du fluide hydraulique
EP1344900A2 (fr) 2002-03-15 2003-09-17 C.R.F. Società Consortile per Azioni Moteur à combustion interne aux plusieurs cylindres avec commande des soupapes variable et dispositif à freinage aux soupapes
EP1555398A1 (fr) 2004-01-16 2005-07-20 C.R.F. Societa' Consortile per Azioni Moteur à combustion interne à simple arbre à cames commandant les soupapes d'échappement de façon mécanique, et les soupapes d'admission à l'aide d'un dispositif hydraulique à commande electronique
EP1635045A1 (fr) 2004-09-14 2006-03-15 C.R.F. Società Consortile per Azioni Moteur à combustion avec soupapes à réglage action variable avec des poussoirs à l'extérieur des actionneurs
EP1726790A1 (fr) 2005-05-24 2006-11-29 C.R.F. Societa' Consortile per Azioni Système et procédé de contrôle de la charge et de la combustion d'un moteur à combustion interne par un actionnement de soupape incluant plusieurs levées successives par cycle
US20160215661A1 (en) * 2015-01-26 2016-07-28 Jiangsu Gongda Power Technologies Co., Ltd. Engine valve actuation system
US20220010702A1 (en) * 2020-07-07 2022-01-13 Ford Global Technologies, Llc Systems and methods for providing compression release with continuous variable valve lift
WO2022219440A1 (fr) 2021-04-13 2022-10-20 C.R.F. Società Consortile Per Azioni Système d'actionnement d'une soupape d'admission d'un moteur à combustion interne

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