US20090050087A1 - Valve Mechanism for Internal Combustion Engine - Google Patents

Valve Mechanism for Internal Combustion Engine Download PDF

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Publication number
US20090050087A1
US20090050087A1 US11/918,476 US91847606A US2009050087A1 US 20090050087 A1 US20090050087 A1 US 20090050087A1 US 91847606 A US91847606 A US 91847606A US 2009050087 A1 US2009050087 A1 US 2009050087A1
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United States
Prior art keywords
camshaft
valve
same sort
cam
cylinders
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Abandoned
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US11/918,476
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English (en)
Inventor
Shuichi Ezaki
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Toyota Motor Corp
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Individual
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Assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA reassignment TOYOTA JIDOSHA KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: EZAKI, SHUICHI
Publication of US20090050087A1 publication Critical patent/US20090050087A1/en
Abandoned legal-status Critical Current

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    • 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
    • F01L1/02—Valve drive
    • 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
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • 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
    • F01L1/02—Valve drive
    • F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
    • F01L1/047—Camshafts
    • 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
    • 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
    • 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
    • F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
    • 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
    • F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
    • F01L9/22—Valve-gear or valve arrangements actuated non-mechanically by electric means actuated by rotary motors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
    • F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
    • F02D13/0203—Variable control of intake and exhaust valves
    • F02D13/0207—Variable control of intake and exhaust valves changing valve lift or valve lift and timing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
    • F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
    • F02D13/06—Cutting-out cylinders
    • 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
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/18—Rocking arms or levers
    • F01L2001/187—Clips, e.g. for retaining rocker arm on pivot
    • 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
    • F01L2001/3445—Details relating to the hydraulic means for changing the angular relationship
    • F01L2001/34453—Locking means between driving and driven members
    • 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
    • F01L2820/00—Details on specific features characterising valve gear arrangements
    • F01L2820/03—Auxiliary actuators
    • F01L2820/032—Electric motors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to a valve mechanism for an internal combustion engine.
  • JP-A-2004-183610 uses an electric motor to drive an intake valve and an exhaust valve that are provided each cylinder.
  • a method disclosed, for instance, by JP-A-2005-171937 operates a motor in a swing drive mode, which changes the direction of camshaft rotation during a valve body lift.
  • FIGS. 28A to 28C are schematic diagrams illustrating two cams 100 , 102 that are installed over a camshaft 104 . These two cams relate to different cylinders.
  • the cam 100 is formed as a cam whose nose 100 a is formed by bulging a part of a circular base circle 100 b , which is coaxial with the camshaft 104 , outward in radial direction.
  • the cam 102 is formed as a cam whose nose 102 a is formed by bulging a part of a circular base circle 102 b , which is coaxial with the camshaft 104 , outward in radial direction.
  • the cam surfaces (including the nose 100 a and nose 102 a ) other than the surfaces of the base circles 100 b , 102 b are regarded as cam lift sections.
  • the valve closes as the valve body is brought into close contact with a valve seat by the reaction force of a valve spring. If, on the other hand, the cam lift sections come into contact with the contact members on the valve body side, the cam lift sections push the valve body upward. This causes the valve body to open against the force of the valve spring.
  • contact members e.g., rocker arm rollers, or lifters provided for the end of the valve body when a direct hit type is employed
  • the cam 100 and cam 102 are placed at different angular positions as shown in FIGS. 28A to 28C .
  • the cam 100 and cam 102 are positioned in such a manner that the angular position of the nose 100 a is 120° apart from that of the nose 102 a .
  • the angular positions of the cam 100 and cam 102 are set in accordance with the valve timing of a normal rotation drive mode, which is normally used to rotate the camshaft 104 in one direction.
  • FIG. 28A shows a case where the cam lift section which is provided from the position of the nose 100 a toward the nose 102 a is used to open/close the valve body when the cam 100 drives the valve body by swinging.
  • the cam lift section angular range of the cam 100 partly overlaps with that of the cam 102 . Therefore, the cam 100 drives the valve body of one cylinder while the cam 102 drives the valve body of the other cylinder. This makes it practically impossible to provide independent control over the phase (lift timing) and operating angle of the valve body of each cylinder.
  • the camshaft 104 cannot be rotated in a direction that represents the minimum distance between the nose 100 a and nose 102 a , and needs to be rotated greatly in the opposite direction. Further, the amount of such rotation increases when the angular position of the cam 100 becomes closer to that of the cam 102 .
  • a switch from the state shown in FIG. 28B to the state shown in FIG. 28C needs to be made instantaneously in accordance with intake stroke timing. Therefore, if the camshaft rotation angle for the switch increases, it is necessary to increase the camshaft rotation speed. This increases the power consumption of a motor. Further, if the power consumption of the motor increases, the output decreases due to heat generated by the motor.
  • a fuel injection stop operation (fuel cut-off) is recently performed, for instance, to achieve increased fuel efficiency at the time of vehicle deceleration.
  • cylinder cut-off operations are conducted by using a reduced number of cylinders for combustion depending on the operating state in a situation where the internal combustion engine has a plurality of cylinders.
  • control is exercised to halt the operations of all cylinders or some cylinders in a situation where a plurality of cylinder valve bodies are motor-driven, it is difficult to stop a particular cylinder valve body at a particular position because the camshaft is provided with cams that drive the valve bodies of a plurality of cylinders. This not only limits the degree of freedom in conducting an operation with all cylinders stopped or with some cylinders stopped, but also limits the degree of freedom in exercising valve close control to minimize or avoid catalyst deterioration during fuel cut-off.
  • An object of the present invention is to provide optimum control by increasing the degree of freedom in controlling the valve body of each cylinder within a configuration in which a single camshaft includes cams for driving the valve bodies of a plurality of cylinders.
  • the first aspect of the present invention is a valve mechanism for an internal combustion engine that uses a motor to drive for opening/closing a valve body of each cylinder, the valve mechanism comprising: a camshaft that is rotated by the motor and equipped with a plurality of cams for driving the valve body of a plurality of cylinders; and cam angle change means for changing the relative angle between the plurality of cams that are driven by the same motor.
  • the second aspect of the present invention is the valve mechanism according to the first aspect of the present invention, further comprising: control means that drives the motor while making a mode switch between a normal rotation drive mode in which the camshaft is continuously rotated in one direction to drive the valve body and a swing drive mode in which the camshaft is swung to drive the valve body, wherein the cam angle change means changes the relative angular positions of the cams when a mode switch is made.
  • the third aspect of the present invention is the valve mechanism according to the second aspect of the present invention, wherein the camshaft has the cams for driving the valve bodies of two cylinders and is formed by combining a first camshaft, which has a cam for one cylinder, and a second camshaft, which has a cam for the other cylinder; and wherein the cam angle change means changes the relative angular positions of the cam on the first camshaft and the cam on the second camshaft by changing the relative angular positions of the first camshaft and the second camshaft.
  • the fourth aspect of the present invention is the valve mechanism according to the third aspect of the present invention, further comprising: angle lock means that is provided at a junction between the first camshaft and the second camshaft to lock the relative angular positions of the first camshaft and the second camshaft in the normal rotation drive mode and in the swing drive mode, respectively.
  • the fifth aspect of the present invention is the valve mechanism according to the fourth aspect of the present invention, wherein the angle lock means includes a lock pin, which is provided for one of the first camshaft and the second camshaft, and a first engagement hole and a second engagement hole, which are made in the other of the first camshaft and the second camshaft to engage with the lock pin; wherein, in the normal rotation drive mode, the lock pin engages with the first engagement hole to lock the relative angular positions of the first camshaft and the second camshaft; and wherein, in the swing drive mode, the lock pin engages with the second engagement hole to lock the relative angular positions of the first camshaft and the second camshaft.
  • the angle lock means includes a lock pin, which is provided for one of the first camshaft and the second camshaft, and a first engagement hole and a second engagement hole, which are made in the other of the first camshaft and the second camshaft to engage with the lock pin; wherein, in the normal rotation drive mode, the lock pin engages
  • the sixth aspect of the present invention is the valve mechanism according to fifth aspect of the present invention, further comprising: lock pin disengagement means that supplies oil to the first or second engagement hole to disengage the lock pin from the first or second engagement hole, wherein the lock pin disengagement means includes an oil path that communicates with either the first engagement hole or the second engagement hole in accordance with the relative angular positions of the first camshaft and the second camshaft; wherein, in the normal rotation drive mode, the oil path communicates with only the first engagement hole, and when a mode switch is to be made to the swing drive mode, oil is supplied to the oil path to disengage the lock pin from the first engagement hole; and wherein, in the swing drive mode, the oil path communicates with only the second engagement hole, and when a mode switch is to be made to the normal rotation drive mode, oil is supplied to the oil path to disengage the lock pin from the second engagement hole.
  • the seventh aspect of the present invention is the valve mechanism according to any one of the second to sixth aspects of the present invention, wherein the valve body is an intake valve, and when a mode switch is made from the normal rotation drive mode to the swing drive mode, the valve opening timing of the valve body retards.
  • the eighth aspect of the present invention is the valve mechanism according to any one of the second to sixth aspects of the present invention, wherein the valve body is an exhaust valve, and when a mode switch is made from the normal rotation drive mode to the swing drive mode, the valve opening timing of the valve body advances.
  • the ninth aspect of the present invention is the valve mechanism according to any one of the second to eighth aspects of the present invention, further comprising: a hydraulic lash adjuster for adjusting the clearance between the valve body and the cam.
  • the tenth aspect of the present invention is the valve mechanism according to the ninth aspect of the present invention, further comprising: a rocker arm for transmitting the acting force of the cam to the valve body.
  • the eleventh aspect of the present invention is the valve mechanism according to any one of the second to tenth aspects of the present invention, wherein the motor is positioned at a longitudinal end of the camshaft.
  • the twelfth aspect of the present invention is the valve mechanism according to any one of the second to tenth aspects of the present invention, wherein the motor is positioned above the camshaft.
  • the thirteenth aspect of the present invention is the valve mechanism according to the first aspect of the present invention, wherein the internal combustion engine performs a fuel cut-off operation at the time of vehicle deceleration; and wherein, when the fuel cut-off operation is performed, the cam angle change means changes the relative angular positions of the cams so as to close the valve bodies of all cylinders.
  • the fourteenth aspects of the present invention is the valve mechanism according to the thirteenth aspect of the present invention, wherein the camshaft includes an intake valve camshaft for driving intake valves and an exhaust valve camshaft for driving exhaust valves; and wherein, when the fuel cut-off operation is performed, the cam angle change means changes the relative angular positions of the cams on at least either the intake valve camshaft or the exhaust valve camshaft so as to close the valve bodies of all cylinders.
  • the fifteenth aspect of the present invention is the valve mechanism according to the fourteenth aspect of the present invention, wherein, when the fuel cut-off operation is performed, the cam angle change means changes the relative angular positions of the cams on one of the intake valve camshaft and the exhaust valve camshaft so as to close the valve bodies of all cylinders and changes the relative angular positions of the cams on the other of the intake valve camshaft and the exhaust valve camshaft so as to open only the valve bodies of some of the all cylinders.
  • the sixteenth aspect of the present invention is the valve mechanism according to the fifteenth aspect of the present invention, wherein, when the fuel cut-off operation is performed, the cam angle change means changes the relative angular positions of the cams on the exhaust valve camshaft so as to close the valve bodies of all cylinders and changes the relative angular positions of the cams on the intake valve camshaft so as to open only the valve bodies of some of the all cylinders.
  • the seventeenth aspect of the present invention is the valve mechanism according to the fifteenth or sixteenth aspect of the present invention, wherein the some of the all cylinders are two cylinders in which pistons move in opposite directions.
  • the eighteenth aspect of the present invention is the valve mechanism according to the fifteenth or sixteenth aspect of the present invention, wherein the some of the all cylinders are two cylinders that are 180 crank angle degrees out of phase with each other.
  • the nineteenth aspect of the present invention is the valve mechanism according to the seventeenth or eighteenth aspect of the present invention, wherein the cam angle change means changes the relative angular positions of the cams so that the two cylinders open the valve bodies by the same amount.
  • the twentieth aspect of the present invention is the valve mechanism according to any one of the fifteenth to nineteenth aspects of the present invention, wherein the cam angle change means changes the amount of valve body opening in accordance with a requested vehicle speed level of a vehicle in which the internal combustion engine is mounted.
  • the relative positions of the plurality of cams driven by the same motor can be changed to increase the degree of freedom in driving the valve body. Therefore, control can be exercised, for instance, to close the valve bodies of all cylinders or open the valve bodies of some cylinders. Consequently, the open/close status of the valve bodies can be optimally controlled.
  • the relative positions of the cams for various cylinders can be changed when a mode switch is made between the normal rotation drive mode and swing mode. Therefore, the relative angular positions of the cams of various cylinders can be set apart from each other in the swing drive mode. This makes it possible to minimize the camshaft rotation angle when the valve body to be driven is changed in the swing drive mode.
  • the camshaft has cams for driving the valve bodies of two cylinders.
  • the camshaft is formed by combining the first camshaft, which has a cam for one cylinder, with the second camshaft, which has a cam for the other cylinder. Therefore, the relative angular positions of the cams for two cylinders can be changed by changing the relative angular positions of the first and second camshafts.
  • the relative angular positions of the first and second camshafts can be locked in the normal rotation drive mode and swing drive mode. Therefore, the motor can be driven in the normal rotation drive mode or swing drive mode while the relative angular positions of the cams for two cylinders are locked.
  • the relative angular positions of the first and second camshafts can be locked by engaging the lock pin with the first or second engagement hole. Further, the lock pin engages with the first engagement hole in the normal rotation drive mode and engages with the second engagement hole in the swing drive mode. Therefore, the camshaft can be driven while the relative angular positions of the first and second camshafts are locked in both modes.
  • the oil path communicates only with the first engagement hole in the normal rotation drive mode in which the lock pin is engaged with the first engagement pin, and communicates only with the second engagement hole in the swing drive mode in which the lock pin is engaged with the second engagement pin. Therefore, when the lock pin is to be disengaged, oil can be supplied only to the engagement hole with which the lock pin is engaged. This makes it possible to prevent the oil from flowing out of the engagement hole with which the lock pin is not engaged, and properly avoid an oil pressure decrease at the time of lock pin disengagement.
  • the intake valve opening timing retards when a mode switch is made from the normal rotation drive mode to the swing drive mode. Therefore, the intake valve opening timing can set apart from the top dead center of a piston. This makes it possible to properly avoid a collision between the intake valve and piston.
  • the exhaust valve opening timing advances when a mode switch is made from the normal rotation drive mode to the swing drive mode. Therefore, the exhaust valve opening timing can set apart from the top dead center of the piston. This makes it possible to properly avoid a collision between the exhaust valve and piston.
  • the hydraulic lash adjuster is included and used to adjust the clearance between the valve body and cam. Therefore, the clearance between the valve body and cam can be minimized. This eliminates the need for a preparatory zone for allowing the cam to lift the valve body, and decreases the phase angle of the cam for a valve body lift. Consequently, the motor speed for swing drive can be reduced to minimize the power consumption of the motor.
  • the rocker arm is included and used to transmit the cam's acting force to the valve body. Therefore, when the hydraulic lash adjuster is installed, the inertia for valve body operation can be reduced. This makes it possible to reduce the drive load on the motor.
  • the motor is positioned at the longitudinal end of the camshaft. This makes it possible to reduce the vertical space for the valve mechanism and suppress the height of the internal combustion engine. Since the internal combustion engine is mounted in a vehicle in an inclined position particularly when the vehicle is of a front-engine front-drive type, mountability in an engine room can be enhanced by suppressing the height of the internal combustion engine.
  • the motor is positioned above the camshaft to reduce the longitudinal camshaft space for the valve mechanism and suppress the overall length of the internal combustion engine. Since the internal combustion engine is longitudinally mounted in the vehicle particularly when the vehicle is of a front-engine rear-drive type, the overall length is suppressed to provide enhanced mountability in the engine room. Further, the internal combustion engine can be positioned toward the center of the vehicle to provide increased vehicle maneuver stability.
  • the relative angular positions of the cams are changed so as to close the valve bodies of all cylinders when a fuel cut-off operation is performed. Therefore, the air flow to an exhaust path can be stopped. This makes it possible to suppress the outflow of oxygen to a catalyst and deter catalyst deterioration.
  • At least either the intake valve camshaft or the exhaust valve camshaft can close the valve bodies of all cylinders. This makes it possible to shut off the air flow to the exhaust path.
  • At least either the intake valve camshaft or the exhaust valve camshaft closes the valve bodies of all cylinders while the other camshaft changes the relative angular positions of the cams so as to open only the valve bodies of particular cylinders. Therefore, it is possible to deliver gas to and discharge the gas out of the particular cylinders. This makes it possible to perform pumping work and apply the engine brake.
  • the exhaust valve camshaft can close the valve bodies of all cylinders and shut off the air flow to the exhaust path.
  • the intake valve camshaft changes the relative angular positions of the cams so as to open only the valve bodies of particular cylinders. Consequently, the gas can be transferred between the particular cylinders and an intake path. This makes it possible to perform pumping work and apply the engine brake.
  • the seventeenth aspect of the present invention opens only the valve bodies of two cylinders whose pistons move in opposite directions. Therefore, the gas discharged out of one cylinder can be taken into the other cylinder. In this manner, the gas can be exchanged between the two cylinders.
  • the eighteenth aspect of the present invention opens only the valve bodies of two cylinders that are 180 crank angle degrees out of phase with each other. Therefore, the gas discharged out of one cylinder can be taken into the other cylinder. In this manner, the gas can be exchanged between the two cylinders.
  • two cylinders open the valve bodies by the same amount. Therefore, when the gas is exchanged between the two cylinders, a proper amount of gas can be delivered from one cylinder to the other. This makes it possible to avoid the presence of extra gas in a gas path and prevent the generation of an unnecessary negative pressure.
  • the amount of valve body opening changes in accordance with the requested vehicle speed level of the vehicle in which the internal combustion engine is mounted. Consequently, engine braking force can be controlled in accordance with the requested vehicle speed level.
  • FIG. 1 is a schematic diagram illustrating the configuration of a system that includes an internal combustion engine valve mechanism according to each embodiment of the present invention.
  • FIG. 2 is a schematic diagram illustrating the configuration of a section around an intake valve and valve mechanism according to a first embodiment.
  • FIGS. 3A and 3B are schematic diagrams illustrating how a cam drives the intake valve.
  • FIG. 4 is a schematic diagram illustrating the relationship among internal combustion engine speed, output torque, and cam drive mode.
  • FIG. 5 is a schematic diagram illustrating in detail the configuration of a camshaft that drives the intake valves of the fourth and sixth cylinders in accordance with the first embodiment.
  • FIGS. 6A and 6B are schematic diagrams illustrating the end faces of flange sections on the camshaft.
  • FIGS. 7A and 7B are schematic diagrams illustrating the positional relationship between a fourth-cylinder cam and a sixth-cylinder cam, which are mounted on the camshaft.
  • FIG. 8 is a cross-sectional view that is taken along one-dot chain line I-I′ in FIG. 7A .
  • FIG. 9 is a schematic diagram illustrating a state in which a lock pin is disengaged from a hole by supplying oil to the hole into which the lock pin is inserted.
  • FIGS. 10A and 10B are cross-sectional views that are taken along one-dot chain line II-II′ in FIG. 8 .
  • FIG. 11 is a schematic diagram illustrating the configuration of a section around an intake valve and valve mechanism according to a second embodiment.
  • FIG. 12 is a schematic diagram illustrating in detail the configuration of a camshaft that drives the intake valves of the fifth and seventh cylinders in accordance with the second embodiment.
  • FIGS. 13A and 13B are schematic diagrams illustrating the end face of a flange section on the camshaft.
  • FIGS. 14A and 14B are schematic diagrams illustrating the positional relationship between a fifth-cylinder cam and a seventh-cylinder cam, which are mounted on the camshaft.
  • FIGS. 15A and 15B are cross-sectional views illustrating a thrust position at which oil paths are provided, like FIGS. 10A and 10B .
  • FIG. 16 is a schematic diagram illustrating the relationship between the lift amounts and crank angles of the intake valve and exhaust valve.
  • FIG. 17 is a schematic diagram illustrating an example in which a hydraulic lash adjuster is positioned at the supporting point of a rocker arm.
  • FIG. 18 is a schematic diagram illustrating an example in which a valve mechanism motor is positioned above the camshaft.
  • FIGS. 19A and 19B are schematic diagrams illustrating examples in which the relative angle between the seventh-cylinder cam 64 and fifth-cylinder cam, which are shown in FIG. 14B , is smaller than 180°.
  • FIGS. 20A and 20B are schematic diagrams illustrating intake valve/exhaust valve control that is exercised in accordance with a third embodiment.
  • FIG. 21 is a schematic diagram illustrating the configuration of a section around the valve mechanism that drives exhaust valves in accordance with the third embodiment.
  • FIG. 22 is a schematic diagram illustrating in detail the configuration of a camshaft that drives the exhaust valve in accordance with the third embodiment.
  • FIGS. 23A and 23B are schematic diagrams illustrating the end face of a flange section on a camshaft that drives the exhaust valve in accordance with the third embodiment.
  • FIGS. 24A and 24B are schematic diagrams illustrating the positional relationship among the cams on a camshaft that drives the exhaust valve in accordance with the third embodiment.
  • FIG. 25 is a schematic diagram illustrating the configuration of a section around the valve mechanism that drives intake valves in accordance with the third embodiment.
  • FIG. 26 is a schematic diagram illustrating an operation that is performed to exchange gas between the first and second cylinders in accordance with the third embodiment.
  • FIG. 27 is a timing diagram illustrating intake valve/exhaust valve control that is exercised in accordance with the third embodiment.
  • FIGS. 28A , 28 B, and 28 C are schematic diagrams illustrating adverse effects that may be produced when cams for a plurality of cylinders are mounted on a single camshaft.
  • FIG. 1 is a schematic diagram illustrating the configuration of a system that includes an internal combustion engine valve mechanism according to each embodiment of the present invention.
  • An internal combustion engine 10 communicates with an intake path 12 and an exhaust path 14 .
  • the intake path 12 includes an air filter 16 , which is positioned at an upstream end.
  • the air filter 16 includes an intake temperature sensor 18 , which detects intake temperature THA (i.e., outside air temperature).
  • THA intake temperature
  • An air flow meter 20 is positioned downstream of the air filter 16 .
  • a throttle valve 22 is installed downstream of the air flow meter 20 .
  • a throttle sensor 24 which detects the throttle opening TA, and an idle switch 26 , which turns ON when the throttle valve 22 fully closes, are positioned near the throttle valve 22 .
  • a surge tank 28 is placed downstream of the throttle valve 22 .
  • the internal combustion engine 10 includes a fuel injection valve 30 , which injects fuel into a combustion chamber (in a cylinder).
  • the fuel injection valve 30 may be used to inject fuel into an intake port.
  • the internal combustion engine 10 also includes an intake valve 32 and exhaust valve 34 .
  • the intake valve 32 is connected to a valve mechanism 36 that drives the intake valve 32 .
  • the exhaust valve 34 is connected to a valve mechanism 38 that drives the exhaust valve 34 .
  • An ignition plug is mounted inside a cylinder of the internal combustion 10 to ignite fuel that is sprayed into the combustion chamber.
  • Each cylinder of the internal combustion engine 10 has a piston 44 .
  • the piston 44 is coupled to a crankshaft 47 , which rotates when the piston 44 reciprocates.
  • the vehicle drive system and auxiliaries air-conditioner compressor, alternator, torque converter, power steering pump, etc.
  • the vehicle drive system is connected to the crankshaft 47 through a transmission (torque converter, not shown in FIG. 1 ).
  • the crankshaft 47 serves as an input shaft for the torque converter.
  • An output shaft of the torque converter is connected to a drive wheel through a differential gear.
  • a crank angle sensor 48 is mounted near the crankshaft 47 to detect the rotation angle of the crankshaft 47 .
  • the crank angle sensor 48 can detect the rotation speed of the crankshaft 47 (the rotation speed of the torque converter input shaft), that is, the engine speed.
  • a water temperature sensor 49 is mounted on a cylinder block of the internal combustion engine 10 to detect cooling water temperature.
  • an upstream catalyst (start catalyst) 42 and a downstream catalyst (NOx occlusion catalyst) 44 are serially positioned.
  • the upstream catalyst 42 has a relatively small capacity and is positioned near the internal combustion engine 10 . Therefore, the upstream catalyst 42 is heated to an activation temperature within a short period of time, for instance, for engine cold start and mainly used for exhaust purification immediately after startup.
  • the downstream catalyst 44 has a larger capacity than the upstream catalyst 42 and plays a primary role in exhaust purification after warm-up.
  • the upstream catalyst 42 and downstream catalyst 44 adsorb, absorb, or selectively adsorb and absorb to retain (occlude) NOx in the exhaust when the air-fuel ratio of incoming exhaust is lean, and reduce and purify occluded NOx with reducing components (HC and CO) when the air-fuel ratio of incoming exhaust is stoichiometric or rich.
  • the upstream catalyst 42 and downstream catalyst 44 are oxidized when they retain (occlude) oxygen contained in a gas that flows in the exhaust path 14 , and are reduced when they release oxygen in a situation where the exhaust contains the reducing components.
  • the exhaust path 14 is provided with an air-fuel ratio sensor (A/F sensor) 45 .
  • the air-fuel ratio sensor 45 is positioned upstream of the upstream catalyst 42 to detect the oxygen concentration in an exhaust gas. This sensor 45 determines the air-fuel ratio of an air-fuel mixture burned in the internal combustion engine 10 in accordance with the oxygen concentration in the exhaust gas that flows into the upstream catalyst 42 .
  • An O 2 sensor 46 is positioned downstream of the upstream catalyst 42 .
  • the O 2 sensor 46 detects whether the oxygen concentration in the exhaust gas is greater or smaller than a predetermined value.
  • This sensor 46 generates a voltage higher than a predetermine voltage (e.g., 0.45 V) when the exhaust air-fuel ratio at the sensor position is richer than the stoichiometric air-fuel ratio, and generates a voltage lower than the predetermined voltage when the exhaust air-fuel ratio is leaner than the stoichiometric air-fuel ratio. Therefore, the O 2 sensor 46 can determine whether a rich exhaust gas (exhaust gas containing HC and CO) or a lean exhaust gas (exhaust gas containing NOx) has flowed downstream of the upstream catalyst 42 .
  • a rich exhaust gas exhaust gas containing HC and CO
  • a lean exhaust gas exhaust gas containing NOx
  • a control device includes an ECU (Electronic Control Unit) 40 .
  • the ECU 40 is connected not only to the aforementioned sensors but also to a KCS sensor, which detects a knock, and various other sensors (not shown) that detect, for instance, the throttle opening, engine speed, exhaust temperature, cooling water temperature, lubricating oil temperature, or catalyst bed temperature to grasp the operating state of the internal combustion engine 10 .
  • the ECU 40 is also connected to actuators and sensors that are provided, for instance, for the aforementioned fuel injection valve 30 and valve mechanisms 36 , 38 .
  • FIG. 2 is a schematic diagram illustrating the configuration of a section around the valve mechanisms 36 , 38 .
  • This figure mainly shows the configuration of a section around a cylinder head.
  • the internal combustion engine 10 according to the present embodiment is a V-type six-cylinder internal combustion engine.
  • a first cylinder, a third cylinder, and a fifth cylinder are mounted in one bank 46
  • a second cylinder, a fourth cylinder, and a sixth cylinder are mounted in another bank 48 .
  • the bank 46 and bank 48 include the valve mechanism 36 for driving the intake valve 32 and the valve mechanism 38 for driving the exhaust valve 34 , respectively.
  • the valve mechanism 36 has basically the same configuration as the valve mechanism 38 . It is assumed that each cylinder of the internal combustion engine 10 has two intake valves 32 and two exhaust valves 34 .
  • the valve mechanism 36 mounted in the bank 46 includes two devices (valve mechanism 36 A and valve mechanism 36 B).
  • the valve mechanism 36 mounted in the bank 48 includes two devices (valve mechanism 36 C and valve mechanism 36 D).
  • the valve mechanism 36 A drives the intake valves 32 of the first cylinder, whereas the valve mechanism 36 B drives the intake valves 32 of the third and fifth cylinders.
  • the valve mechanism 36 C drives the intake valves 32 of the second cylinder, whereas the valve mechanism 36 D drives the intake valves 32 of the fourth and sixth cylinders.
  • the valve mechanism 36 A includes an electric motor (hereinafter referred to as a motor) 50 A, which serves as a driving source, a gear train 52 A, which serves as a mechanism for transmitting the rotary motion of the motor 50 A, and a camshaft 54 , which converts the rotary motion transmitted from the gear train to a linear open/close motion of the intake valves 32 .
  • a motor electric motor
  • gear train 52 A which serves as a mechanism for transmitting the rotary motion of the motor 50 A
  • camshaft 54 which converts the rotary motion transmitted from the gear train to a linear open/close motion of the intake valves 32 .
  • valve mechanism 36 B includes a motor 50 B, a gear train 52 B, and a camshaft 56 .
  • the valve mechanism 36 C includes a motor 50 C, a gear train 52 C, and a camshaft 58 .
  • valve mechanism 36 D includes a motor 50 D, a gear train 52 D, and a camshaft 60 .
  • the gear trains 52 B, 52 C, 52 D have the same configuration as the gear train 52 A.
  • a DC brushless motor or other similar motor whose rotation speed is controllable is used as the motors 50 A, 50 B, 50 C, 50 D.
  • the motors 50 A, 50 B, 50 C, 50 D include a resolver, rotary encoder, or other built-in position sensor that detects their rotational position.
  • a cam drive gear 62 and a cam 64 are installed over the peripheries of the camshafts 54 , 56 , 58 , 60 . The cam drive gear 62 and cam 64 both rotate together with the camshafts 54 , 56 , 58 , 60 .
  • the gear train 52 A transmits the rotation of a motor gear 68 A, which is installed over an output shaft of the motor 50 A, to the cam drive gear 62 on the camshaft 54 .
  • the gear train 52 A may be configured so that the motor gear 68 A and cam drive gear 62 rotate at the same speed or configured so that the cam drive gear 62 rotates at a higher speed or at a lower speed than the motor gear 68 A.
  • the gear trains 52 B, 52 C, 52 D transmit the rotation of the motor gears installed over output shafts of the motors 50 B, 50 C, 50 D to the cam drive gear 62 for the camshafts 56 , 58 , 60 .
  • the camshaft 54 is positioned above the intake valves 32 of the first cylinder.
  • the intake valves 32 of the first cylinder are opened/closed by two cams 64 that are installed over the camshaft 54 .
  • the camshaft 56 is positioned above the intake valves 32 of the third and fifth cylinders.
  • the intake valves 32 of the third and fifth cylinders are opened/closed by four cams 64 that are installed over the camshaft 56 .
  • the camshaft 58 is positioned above the intake valves 32 of the second cylinder.
  • the intake valves 32 of the second cylinder are opened/closed by two cams 64 that are installed over the camshaft 58 .
  • the camshaft 60 is positioned above the intake valves 32 of the fourth and sixth cylinders.
  • the intake valves 32 of the fourth and sixth cylinders are opened/closed by four cams 64 that are installed over the camshaft 60 .
  • the intake valves 32 may be directly driven by the cams 64 or driven through a rocker arm.
  • FIGS. 3A and 3B illustrate how the intake valve 32 is driven by the cam 64 .
  • the cam 64 is formed as a plate cam whose nose 64 a is formed by bulging a part of a circular base circle 64 b coaxial with the camshafts 54 - 60 outward in radial direction.
  • the cam 64 is profiled so that its entire circumference does not have negative curvature, that is, a convex curve is drawn outward in radial direction.
  • each intake valve 32 includes a valve stem 32 a .
  • Compressive reaction force of a valve spring pushes each intake valve 32 toward the cam 64 . If the base circle 64 b of the cam 64 faces a contact member (e.g., a rocker arm roller, or a retainer provided for the end of the intake valve 32 when a direct hit type is employed) on the intake valve side, a valve port closes as the intake valve 32 comes into close contact with a valve seat (not shown) of the intake port.
  • a contact member e.g., a rocker arm roller, or a retainer provided for the end of the intake valve 32 when a direct hit type is employed
  • FIGS. 3A and 3B also indicate two drive modes for the cam 64 : normal rotation drive mode and swing drive mode.
  • the motors 50 A- 50 D continuously rotate in one direction to rotate the cam 64 continuously in the direction of normal rotation (in the direction indicated by the arrow in FIG. 3A ) beyond a maximum lift position as indicated in FIG. 3A , that is, a position at which the nose 64 a of the cam 64 comes into contact with the contact member on the intake valve side.
  • the cam 64 reciprocates as shown in FIG. 3B while changing the rotation direction of the motors 50 A- 50 D before the maximum lift position for the normal rotation drive mode is reached.
  • the operating angle and lift timing of the intake valve 32 is controlled by varying the rotation speed of the cam 64 with respect to crankshaft rotation.
  • the maximum lift amount, operating angle, and lift timing of the intake valve 32 can be controlled by controlling the rotation speed of the cam 64 and the swing angle range of the cam 64 .
  • FIG. 4 is a schematic diagram illustrating the relationship among the engine speed and output torque of the internal combustion engine 10 and the drive modes of the cam 64 .
  • the drive modes of the cam 64 are selectively used in association with the engine speed and output torque as shown in FIG. 4 .
  • the swing drive mode is basically selected.
  • the normal rotation drive mode is basically selected. Consequently, control is exercised so as to decrease the lift amount and operating angle of the intake valve 32 in the low engine speed region and increase the lift amount and operating angle of the intake valve 32 in the high engine speed region.
  • an optimum amount of air can be delivered into an engine cylinder in accordance with the engine speed and output torque.
  • FIG. 5 is a schematic diagram illustrating in detail the configuration of the camshaft 60 .
  • the camshaft 60 includes a camshaft 60 A and a camshaft 60 B.
  • the camshaft 60 A includes two cams 64 that drive the intake valves 32 of the fourth cylinder.
  • the camshaft 60 B includes two cams 64 that drive the intake valves 32 of the sixth cylinder.
  • the camshaft 56 for driving the intake valves 32 of the third and fifth cylinders also includes two camshafts as is the case with the camshaft 60 .
  • the camshaft 60 A has a flange section 66 at its end.
  • the camshaft 60 B has a flange section 68 at its end.
  • the flange section 68 of the camshaft 60 B has a shaft 69 that protrudes from the center of the flange section 68 toward the camshaft 60 A.
  • the camshaft 60 A and camshaft 60 B are unified as the shaft 69 turnably fits into the hole 67 , thereby bringing the end face of the flange section 66 into contact with the end face of the flange section 68 .
  • FIGS. 6A and 6B are schematic diagrams illustrating the end faces of the flange sections 66 , 68 .
  • FIG. 6A shows the end face of the flange section 66
  • FIG. 6B shows the end face of the flange section 68 .
  • the end face of the flange section 66 has a reference surface 66 A and a protrusion surface 66 B.
  • the protrusion surface 66 B protrudes toward the camshaft 60 B in relation to the reference surface 66 A.
  • the boundaries between the reference surface 66 A and protrusion surface 66 B are provided with stepped sections 66 C, 66 D.
  • the end face of the flange section 68 has a reference surface 68 A and a protrusion surface 68 B as shown in FIGS. 5 and 6B .
  • the protrusion surface 68 B protrudes toward the camshaft 60 A in relation to the reference surface 68 A.
  • the boundaries between the reference surface 68 A and protrusion surface 68 B are provided with stepped sections 68 C, 68 D.
  • the reference surface 66 A of the flange section 66 is in close contact with the protrusion surface 68 B of the flange section 68
  • the reference surface 68 A of the flange section 68 is in close contact with the protrusion surface 66 B of the flange section 66 .
  • FIG. 6A there are two holes 70 , 72 in the reference surface 66 A of the flange section 66 .
  • the protrusion surface 68 B of the flange section 68 is provided with a lock pin 74 .
  • the lock pin 74 protrudes from the protrusion surface 68 B toward the camshaft 60 A.
  • the distance between the center of the shaft 69 and the center of the lock pin 74 is equal to the distance between the center of the hole 70 or hole 72 and the center of the hole 67 .
  • the inside diameters of the holes 70 , 72 and the outside diameter of the lock pin 74 are determined so that the lock pin 74 fits into the holes 70 , 72 . Therefore, while the shaft 69 is fitted into the hole 67 , the lock pin 74 can fit into the hole 70 or hole 72 as far as the angular position of the hole 70 or hole 72 agrees with that of the lock pin 74 .
  • the camshaft 60 A and camshaft 60 B can be relatively rotated.
  • the lock pin 74 is inserted into either the hole 70 or the hole 72 , the relative rotational positions of the camshaft 60 A and camshaft 60 B are locked.
  • FIGS. 7A and 7B are schematic diagrams that relate to a situation where the camshaft 60 A and camshaft 60 B are coupled together, and illustrate the positional relationship between the cam 64 on the camshaft 60 A and the cam 64 on the camshaft 60 B.
  • FIGS. 7A and 7B are views of the camshaft 60 as taken in the direction of arrow X in FIG. 5 .
  • FIG. 7A shows a state in which the lock pin 74 is inserted into the hole 70 .
  • FIG. 7B shows a state in which the lock pin 74 is inserted into the hole 72 .
  • the state shown in FIG. 7A is set when the intake valve 32 is opened/closed in the normal rotation drive mode. While the lock pin 74 is inserted into the hole 70 , the nose 64 a of the fourth-cylinder cam 64 on the camshaft 60 A is positioned 120° apart from the nose 60 a of the sixth-cylinder cam 64 on the camshaft 60 B, as shown in FIG. 7A .
  • the rotational positions can be properly locked because the relative rotational positions of the camshaft 60 A and camshaft 60 B are locked as described above by making use of the engagement between the lock pin 74 and hole 70 and the contact between the stepped section 66 C and stepped section 68 C.
  • the motor 50 D of the valve mechanism 36 D is driven in such a manner that the ratio between the number of rotations of the camshaft 60 and the number of rotations of the crankshaft is 1:2, the camshaft 60 rotates 120° between the intake stroke of the fourth cylinder and the intake stroke of the sixth cylinder. Therefore, when the camshaft 60 rotates in the direction of the arrow in FIG.
  • the intake valves 32 of the fourth and sixth cylinders can be opened/closed in accordance with the intake strokes of the fourth and sixth cylinders.
  • the number of rotations of the camshaft 60 is varied from a state in which the ratio between the number of rotations of the camshaft 60 and the number of rotations of the crankshaft is 1:2, the operating angle and lift timing for an intake valve lift can be varied.
  • the camshaft 60 needs to be greatly rotated after the intake valves 32 of one cylinder are driven, as described with reference to FIGS. 28A to 28C . This increases the power consumption of the motor.
  • the present embodiment varies the relative angular positions of the camshaft 60 A and camshaft 60 B from the state shown in FIG. 7A , and governs the positions of these camshafts so that the nose 64 a of the fourth-cylinder cam 64 on the camshaft 60 A is positioned 180° apart from the nose 60 a of the sixth-cylinder cam 64 on the camshaft 60 B as shown in FIG. 7B .
  • the rotation amount of the camshaft 60 for driving the intake valves 32 of the remaining cylinder can therefore be rendered smaller than those indicated in FIGS. 28A to 28C . More specifically, when the nose 64 a of the fourth-cylinder cam 64 is positioned 180° apart from the nose 60 a of the sixth-cylinder cam 64 on the camshaft 60 B, the rotation amount of the camshaft 60 can be rendered approximately 60° smaller than those indicated in FIGS. 28A to 28C . This makes it possible to considerably reduce the power consumption of the motor SOD when the intake valves 32 are driven in the swing drive mode.
  • FIG. 8 is a cross-sectional view that is taken along one-dot chain line I-I′ in FIG. 7A to show the vicinity of a joint between the camshaft 60 A and camshaft 60 B.
  • the shaft 69 on the flange section 68 is turnably engaged with the hole 67 in the flange section 66 .
  • the lock pin 74 is inserted into a receiver hole 68 E in the flange section 68 .
  • a compression spring 76 is positioned between the lock pin 74 and the bottom of the receiver hole 68 E.
  • An oil path 78 is connected to the holes 70 , 72 in the flange section 66 . As shown in FIGS. 6A , 6 B, 7 A, and 7 B, the oil path 78 is radially extended from the hole 67 toward the hole 70 and hole 72 .
  • the camshaft 60 B has an oil path 79 , which is provided along the rotational center axis of the camshaft 60 B.
  • the end of the oil path 79 is provided with an oil path 77 that is extended toward the outer circumference of the shaft 69 . While the camshaft 60 A and camshaft 60 B are coupled together, the oil path 77 and oil path 78 agree in thrust direction, and the oil path 77 is connected to the two oil paths 78 .
  • An oil pump delivers oil to the oil path 79 under a predetermined pressure.
  • the oil delivered to the oil path 79 is forwarded to the hole 70 and hole 72 through the oil path 77 and oil path 78 .
  • FIG. 8 shows a state in which oil pressure is exerted.
  • the pushing force of the compression spring 76 inserts the lock pin 74 into the hole 70 in the flange section 66 .
  • the relative rotational positions of the camshaft 60 A and camshaft 60 B are then set as indicated in FIG. 7A .
  • FIG. 9 shows a state in which oil is supplied to the hole 70 through the oil path 79 , oil path 77 , and oil path 78 and pressurized.
  • the hole 70 is filled with the oil, and the lock pin 74 goes into the receiver hole 68 E under oil pressure. While the lock pin 74 is placed in the receiver hole 68 E, the upper surface of the lock pin 74 is concaved below the protrusion surface 68 B of the flange section 68 . Therefore, the lock pin 74 is disengaged from the hole 70 or hole 72 so that the camshaft 60 A and camshaft 60 B can be relatively rotated.
  • FIGS. 10A and 10B are cross-sectional views that are taken along one-dot chain line II-II′ in FIG. 8 .
  • the state shown in FIG. 10A corresponds to the state shown in FIG. 7A
  • the state shown in FIG. 10B corresponds to the state shown in FIG. 7B .
  • FIG. 10A indicates that the lock pin 74 is inserted into the hole 70
  • FIG. 10B indicates that the lock pin 74 is inserted into the hole 72 .
  • the protrusion surface 68 B of the flange section 68 is constantly positioned over the two holes 70 , 72 in the flange section 66 . Since the reference surface 66 A of the flange section 66 is in close contact with the protrusion surface 68 B of the flange section 68 , the holes 70 , 72 are constantly covered with the protrusion surface 68 B.
  • the description relates to a situation where a mode switch is made from the normal rotation drive mode to the swing drive mode.
  • the cam drive gear 62 for driving the camshaft 60 is installed over the camshaft 60 B.
  • the lock pin 74 engages with the hole 70 to bring the stepped section 66 C into contact with the stepped section 68 C.
  • the rotary motion of the camshaft 60 B is transmitted to the camshaft 60 A so that the camshaft 60 A and camshaft 60 B rotate in the direction of the arrow in FIG. 7A (counterclockwise).
  • the camshaft 60 B can rotate relative to the camshaft 60 A.
  • the direction of output shaft rotation of the motor 50 D is reversed, and the rotary motion of the output shaft is transmitted to the camshaft 60 B through the cam drive gear 62 . Therefore, when the motor 50 D reverses, the camshaft 60 B rotates clockwise relative to the camshaft 60 A as viewed in FIG. 7A .
  • the reaction force of valve springs for the fourth-cylinder intake valves 32 is exerted on the cam 64 on the camshaft 60 A, and sliding resistance is generated in the rotation direction of the camshaft 60 A. Consequently, when the motor 50 D reverses with the lock pin 74 disengaged from the hole 70 , the camshaft 60 A does not rotate in the same direction as the camshaft 60 B.
  • the camshaft 60 B can rotate in any direction without regard to the rotation direction of the camshaft 60 A.
  • the camshaft 60 B receives the driving force of the motor 50 D and rotates counterclockwise relative to the camshaft 60 A as viewed in FIG. 7B .
  • sliding resistance is generated in the rotation direction of the camshaft 60 A due to the reaction force of a valve spring. Therefore, the camshaft 60 A does not rotate in the same direction as the camshaft 60 B.
  • the camshaft 56 When the intake valves 32 are to be driven in the swing drive mode, the relative position of the cam 64 is varied from the one in the normal rotation mode.
  • the camshaft 56 is provided with a third-cylinder cam 64 and a fifth-cylinder cam 64 , and the crankshaft rotates 240° between the intake stroke of the third cylinder and the intake stroke of the fifth cylinder. Therefore, when the ratio between the number of rotations of the camshaft 56 and the number of rotations of the crankshaft is 1:2, the camshaft 56 rotates 120° between the intake stroke of the third cylinder and the intake stroke of the fifth cylinder.
  • the intake valves 32 can be opened/closed in accordance with the intake strokes of the third and fifth cylinders. Further, when, in the swing drive mode, the relative angular positions of the two camshafts constituting the camshaft 56 are changed so that the third-cylinder cam 64 is positioned 180° apart from the fifth-cylinder cam 64 , the rotation amount of the camshaft 56 can be minimized in the swing drive mode.
  • the first embodiment varies the relative positions of the cams 64 from those in the normal rotation drive mode as described above. Therefore, the rotation amount of the camshaft 60 for the swing drive mode can be reduced. This makes it possible to reduce the power consumption of the motor SOD, which drives the camshaft 60 , and provide enhanced system efficiency.
  • FIG. 11 is a schematic diagram illustrating the configuration of a section around two valve mechanisms 36 , 38 according to the second embodiment. This figure mainly shows the configuration of a section around a cylinder head.
  • the internal combustion engine 10 according to the present embodiment includes eight V-type cylinders.
  • a second cylinder, a fourth cylinder, a sixth cylinder, and an eighth cylinder are mounted in one bank 80 , whereas a first cylinder, a third cylinder, a fifth cylinder, and a seventh cylinder are mounted in another bank 82 .
  • the bank 80 and bank 82 include the valve mechanism 36 for driving the intake valve 32 and the valve mechanism 38 for driving the exhaust valve 34 , respectively.
  • the valve mechanism 36 has basically the same configuration as the valve mechanism 38 . As is the case with the first embodiment, it is assumed that each cylinder of the internal combustion engine 10 has two intake valves 32 and two exhaust valves 34 .
  • the valve mechanism 36 mounted in the bank 80 includes two devices (valve mechanism 36 E and valve mechanism 36 F).
  • the valve mechanism 36 mounted in the bank 82 includes two devices (valve mechanism 36 G and valve mechanism 36 H).
  • the valve mechanism 36 E drives the intake valves 32 of the second and fourth cylinders
  • the valve mechanism 36 F drives the intake valves 32 of the sixth and eighth cylinders.
  • the valve mechanism 36 G drives the intake valves 32 of the first and third cylinders
  • the valve mechanism 36 H drives the intake valves 32 of the fifth and seventh cylinders.
  • valve mechanisms 36 E, 36 F, 36 G, 36 H include motors 50 E, 50 F, 50 G, 50 H, respectively, as a driving source.
  • the rotary motion of the motor 50 E is transmitted to a camshaft 84 through a gear train 52 E.
  • the rotary motion of the motor 50 F is transmitted to a camshaft 86 through a gear train 52 F.
  • the rotary motion of the motor 50 G is similarly transmitted to a camshaft 88 through a gear train 52 G.
  • the rotary motion of the motor 50 H is similarly transmitted to a camshaft 90 through a gear train 52 H.
  • the camshaft 84 is positioned above the intake valves 32 of the second and fourth cylinders.
  • the intake valves 32 of the secondhand fourth cylinders are opened/closed by four cams 64 that are installed over the camshaft 84 .
  • the camshaft 86 is positioned above the intake valves 32 of the sixth and eighth cylinders.
  • the intake valves 32 of the sixth and eighth cylinders are opened/closed by four cams 64 that are installed over the camshaft 86 .
  • the camshaft 88 is positioned above the intake valves 32 of the first and third cylinders.
  • the intake valves 32 of the first and third cylinders are opened/closed by four cams 64 that are installed over the camshaft 88 .
  • the camshaft 90 is positioned above the intake valves 32 of the fifth and seventh cylinders.
  • the intake valves 36 of the fifth and seventh cylinders are opened/closed by four cams 64 that are installed over the camshaft 90 .
  • the intake valves 32 of each cylinder are also driven in either the normal rotation drive mode or the swing drive mode. Therefore, the lift amounts and operating angles of the intake valves 32 of each cylinder can be freely varied as is the case with the first embodiment.
  • FIG. 12 is a schematic diagram illustrating in detail the configuration of the camshaft 90 .
  • the camshaft 90 includes a camshaft 90 A and a camshaft 90 B.
  • the camshaft 90 A has two cams 64 that drive the intake valves 32 of the fifth cylinder.
  • the camshaft 90 B has two cams 64 that drive the intake valves 32 of the seventh cylinder.
  • the camshaft 84 , camshaft 86 , and camshaft 88 include two camshafts.
  • the camshaft 90 A has a flange section 66 at its end.
  • the camshaft 90 B has a flange section 68 at its end.
  • the flange section 68 of the camshaft 90 B has a shaft 69 that protrudes from the center of the flange section 68 toward the camshaft 90 A.
  • the camshaft 90 A and camshaft 90 B are unified as the shaft 69 turnably fits into the hole 67 , thereby bringing the end face of the flange section 66 into contact with the end face of the flange section 68 .
  • FIGS. 13A and 13B are schematic diagrams illustrating the end faces of the flange sections 66 , 68 that are provided for the camshaft 90 A and camshaft 90 B.
  • FIG. 13A shows the end face of the flange section 66 of the camshaft 90 A
  • FIG. 13B shows the end face of the flange section 68 of the camshaft 90 B.
  • the end faces of the flange sections 66 , 68 are configured the same as the counterparts according to the first embodiment, which are described with reference to FIGS. 6A and 6B . More specifically, the flange section 66 has a reference surface 66 A and a protrusion surface 66 B. The boundary between the reference surface 66 A and protrusion surface 66 B is provided with stepped sections 66 C, 66 D. Similarly, the flange section 68 has a reference surface 68 A and a protrusion surface 68 B. The boundary between the reference surface 68 A and protrusion surface 68 B is provided with stepped sections 68 C, 68 D. There are two holes 70 , 72 in the reference surface 66 A of the flange section 66 . As shown in FIG. 13B , the protrusion surface 68 B of the flange section 68 is provided with a lock pin 74 . The lock pin 74 protrudes from the protrusion surface 68 B toward the camshaft 90 A.
  • the camshaft 90 A and camshaft 90 B can relatively rotate as is the case with the first embodiment.
  • the lock pin 74 is inserted into either the hole 70 or hole 72 , the relative rotational positions of the camshaft 90 A and camshaft 90 B are locked.
  • FIGS. 14A and 14B are schematic diagrams that relate to a situation where the camshaft 90 A and camshaft 90 B are coupled together and illustrate the positional relationship between the cams 64 on the camshaft 90 A and the cams 64 on the camshaft 90 B.
  • FIGS. 14A and 14B are views of the camshaft 90 as taken in the direction of arrow X in FIG. 12 .
  • FIG. 14A shows a state in which the lock pin 74 is inserted into the hole 70 .
  • FIG. 14B shows a state in which the lock pin 74 is inserted into the hole 72 .
  • the state shown in FIG. 14A is set when the intake valve 32 is opened/closed in the normal rotation drive mode. While the lock pin 74 is inserted into the hole 70 , the nose 64 a of the fifth-cylinder cam 64 on the camshaft 90 A is positioned 45° apart from the nose 60 a of the seventh-cylinder cam 64 on the camshaft 90 B, as shown in FIG. 14A .
  • the motor 50 H of the valve mechanism 36 H is driven in such a manner that the ratio between the number of rotations of the camshaft 90 and the number of rotations of the crankshaft is 1:2, the camshaft 90 rotates 45° between the intake stroke of the fifth cylinder and the intake stroke of the seventh cylinder. Therefore, when the camshaft 90 rotates in the direction of the arrow in FIG.
  • the intake valves 32 of the fifth and seventh cylinders can be opened/closed in accordance with the intake strokes of the fifth and seventh cylinders.
  • the angular positions of the cams 64 for the fifth and seventh cylinders are set as shown in FIG. 14A , it is necessary to rotate the camshaft 90 considerably, as described with reference to FIGS. 28A to 28C , after the intake valves 32 for the fifth or seventh cylinder are driven. This increases the power consumption of the motor.
  • the relative angular positions of the cams 64 for the two cylinders, which are mounted on the camshaft 90 are closer to each other than in the first embodiment. In the state shown in FIG.
  • the present embodiment when the intake valves 32 are to be opened/closed in the swing drive mode, the present embodiment also varies the relative angular positions of the camshaft 90 A and camshaft 90 B from the state shown in FIG. 14A . More specifically, the present embodiment varies the positions of these camshafts so that the nose 64 a of the fifth-cylinder cam 64 on the camshaft 90 A is positioned 180° apart from the nose 60 a of the seventh-cylinder cam 64 on the camshaft 90 B as shown in FIG. 14B .
  • the rotation amount of the camshaft 90 for driving the intake valves 32 of the remaining cylinder can therefore be reduced. This makes it possible to minimize the power consumption of the motor 50 H when the intake valves 32 are driven in the swing drive mode.
  • the oil path 78 is connected to the holes 70 , 72 in the flange section 66 .
  • the camshaft 90 B is provided with the oil path 79 and oil path 77 as is the case with the camshaft 60 B according to the first embodiment.
  • the mechanism for changing the engagement between the lock pin 74 and the hole 70 /hole 72 is configured the same as in the first embodiment.
  • FIGS. 15A and 15B are cross-sectional views illustrating a thrust position at which the oil paths 77 , 78 are provided, like FIGS. 10A and 10B , which illustrate the first embodiment.
  • the state shown in FIG. 15A corresponds the state shown in FIG. 14A
  • the state shown in FIG. 15B corresponds to the state shown in FIG. 14B .
  • FIG. 15A indicates that the lock pin 74 is inserted into the hole 70
  • FIG. 15B indicates that the lock pin 74 is inserted into the hole 72 .
  • the shape of the oil path 77 differs from the oil path shape according to the first embodiment, which was described with reference to FIGS. 10A and 10B .
  • the oil path 77 has the same width as the oil path 78 . While the lock pin 74 is engaged with the hole 70 , only the oil path 78 , which is connected to the hole 70 , is connected to the oil path 77 as shown in FIG. 15A . Further, while the lock pin 74 is engaged with the hole 72 , only the oil path 78 , which is connected to the hole 72 , is connected to the oil path 77 as shown in FIG. 15B . Therefore, when oil is supplied to the oil path 79 in the state shown in FIG.
  • the oil is delivered only to the hole 70 so that the lock pin 74 disengages from the hole 70 .
  • the oil is delivered only to the hole 72 so that the lock pin 74 disengages from the hole 72 .
  • the second embodiment differs from the first embodiment in the rotation angle of the camshaft 90 B relative to the camshaft 90 A.
  • the hole 70 will never be covered with the protrusion surface 68 B of the flange section 68 . Consequently, if the configuration for simultaneously supplying the oil to the hole 70 and hole 72 is employed as is the case with the first embodiment, the oil may flow through the hole 70 and out of the camshaft 90 , thereby making it impossible to obtain a desired oil pressure at the time of lock pin disengagement.
  • the second embodiment configures the oil path 77 so that the oil is supplied only to the hole with which the lock pin 74 is engaged. Therefore, the second embodiment prevents the oil from flowing out of the hole with which the lock pin 74 is not engaged. This makes it possible to properly prevent the oil pressure from decreasing when the lock pin 74 becomes disengaged. Further, since the oil is supplied only to the hole with which the lock pin 74 is engaged, it is possible to reduce the amount of hydraulic fluid and provide improved response at the time of lock pin disengagement.
  • Timing for disengaging the lock pin 74 from the holes 70 , 72 is the same as described in conjunction with the first embodiment.
  • the cam drive gear 62 for driving the camshaft 90 is installed over the camshaft 90 B as shown in FIG. 11 .
  • the rotation of the camshaft 90 B is transmitted to the camshaft 90 A so that the camshaft 90 A and camshaft 90 B rotate in the direction of the arrow in FIG. 14A (counterclockwise).
  • the output shaft of the motor 50 H reverses and the oil in the oil path 79 is pressurized.
  • the lock pin 74 is then disengaged from the hole 70 so that the camshaft 90 B rotates clockwise relative to the camshaft 90 A as viewed in FIG. 14A .
  • the motor 50 H When a mode switch is made from the swing drive mode to the normal rotation drive mode, the motor 50 H is driven in such a direction that the camshaft 90 B rotates counterclockwise as viewed in FIG. 14B to pressurize the oil in the oil path 79 .
  • the lock pin 74 is then disengaged from the hole 72 .
  • the camshaft 90 B receives driving force from the motor 50 H and rotates counterclockwise relative to the camshaft 90 A as viewed in FIG. 14A .
  • the stepped section 66 C comes into contact with the stepped section 68 C, the position of the hole 70 agrees with that of the lock pin 74 so that the force of the compression spring 76 inserts the lock pin 74 into the hole 70 .
  • the relative angular positions of the camshaft 90 A and camshaft 90 B are then set as shown in FIG. 14A .
  • camshaft 84 When the intake valves 32 are driven in the swing drive mode, the relative position of the cam 64 is varied from the one in the normal rotation drive mode.
  • the camshaft 84 is provided with a second-cylinder cam 64 and a fourth-cylinder cam 64 , and the crankshaft rotates 270° between the intake stroke of the second cylinder and the intake stroke of the fourth cylinder. Therefore, when the ratio between the number of rotations of the camshaft 84 and the number of rotations of the crankshaft is 1:2, the camshaft 84 rotates 135° between the intake stroke of the second cylinder and the intake stroke of the fourth cylinder.
  • the intake valves 32 can be opened/closed in accordance with the intake strokes of the second and fourth cylinders.
  • the relative angular positions of the two camshafts constituting the camshaft 84 are changed so that the second-cylinder cam 64 is positioned 180° apart from the fourth-cylinder cam 64 , the rotation amount of the camshaft 84 can be minimized in the swing drive mode.
  • the other camshafts 86 , 88 are similar to the camshaft 84 in the relative angular positions of the cams 64 in the normal rotation drive mode and in the relative angular positions of the cams 64 in the swing drive mode. As described above, the relative angular positions of the cams 64 in the normal rotation drive mode are greater for the camshaft 84 , camshaft 86 , and camshaft 88 than for the camshaft 90 .
  • FIG. 16 is a schematic diagram illustrating the relationship between the lift amounts and crank angles of an intake valve 32 and exhaust valve 34 .
  • This figure shows the lift amounts of the intake valve 32 and exhaust valve 34 within a crank angle range between an exhaust stroke and intake stroke.
  • the exhaust valve 34 first opens/closes during an exhaust stroke as shown in FIG. 16 .
  • the intake valve 32 starts opening to perform an intake stroke.
  • the first embodiment When a mode switch is made from the normal rotation drive mode to the swing drive mode, the first embodiment also rotates the camshaft 60 B clockwise relative to the camshaft 60 A as viewed in FIG. 7A .
  • the rotation direction of the camshaft 60 B is opposite to the direction of rotation in the normal rotation drive mode.
  • the lift position of the intake valve 32 of the sixth cylinder retards. Therefore, even when the relative rotational positions of the camshaft 60 A and camshaft 60 B are changed, it is possible to properly prevent the intake valve 32 from interfering with the piston 44 .
  • the valve mechanism 36 for driving the intake valve 32 is configured the same as the valve mechanism 38 for driving the exhaust valve 34 .
  • the valve mechanism 38 for driving the exhaust valve 34 it is preferred that the relative rotational positions of the two camshafts be changed to prevent the lift position of the exhaust valve 34 from retarding toward the top dead center, that is, to advance the lift position of the exhaust valve 34 . This makes it possible to properly prevent the exhaust valve 34 from interfering with the piston 44 .
  • a method for minimizing the camshaft rotation angle for driving the intake valve 32 will now be described.
  • the tappet clearance between the intake valve 32 and cam 64 can be adjusted in two ways.
  • One method is to insert a shim or the like to make mechanical adjustments.
  • the other method is to furnish a rocker arm supporting point with a hydraulic lash adjuster (HLA).
  • HLA hydraulic lash adjuster
  • FIG. 17 is a schematic diagram illustrating an example in which a hydraulic lash adjuster is positioned at the supporting point of a rocker arm, which is used to drive the intake valve 32 .
  • the end of the valve stem 32 a of the intake valve 32 is in contact with a pivot that is mounted on one end of the rocker arm 96 .
  • the force of a valve spring (not shown) is exerted on the valve stem 32 a so that the valve stem 32 a pushes the rocker arm 96 upward.
  • the other end of the rocker arm 96 is turnably supported by the hydraulic lash adjuster (HLA) 98 .
  • a roller 96 a is positioned at the center of the rocker arm 96 .
  • Camshafts 84 , 96 , 88 , 90 are installed above the roller 96 a.
  • the hydraulic lash adjuster 98 provides automatic hydraulic adjustments of the vertical position of the rocker arm 96 to automatically adjust the tappet clearance or reduce it to zero. Therefore, the cam 64 on the camshafts 84 - 90 is in constant contact with the roller 96 a as shown in FIG. 17 .
  • the tappet clearance of the intake valve 32 is mechanically adjusted, it is necessary to provide a preparatory zone at a crank angle position for the beginning of opening as shown in FIG. 16 . Since the intake valve 32 begins to lift after the end of the preparatory zone, it is necessary to rotate the camshafts 84 - 90 to an exceptional extent for the preparatory zone when a mechanical adjustment method is used.
  • the actual operating angle of the cam 64 is larger than when the hydraulic lash adjuster 98 is furnished. Therefore, the motor speed increases in the swing drive mode, thereby increasing the power consumption. Further, it is necessary to increase the phase angle between two cam noses by the amount of increase in the actual operating angle for the purpose of avoiding an overlap between the cam lift sections of two cams in the swing drive mode. This enlarges the rotation amount required for a cam change, raises the motor speed in the swing drive mode, and increases the power consumption.
  • the employed mechanism includes the hydraulic lash adjuster 98 , the preparatory zone is not needed because the tappet clearance is zero and the cam 64 is in constant contact with the roller 96 a . Therefore, the operating angles of the camshafts 84 - 90 can be reduced by furnishing the hydraulic lash adjuster 98 . This makes it possible to reduce the time required for an intake valve lift. Further, when the intake valve 32 is driven in the swing drive mode, it is possible to reduce the rotation angle for a cam change and the time required for such a change.
  • the first and second embodiments reduce the operating angle of the cam 64 by adjusting the tappet clearance with the hydraulic lash adjuster 98 . This not only increases the degree of freedom in varying the valve timing, but also reduces the drive amount of the motor 50 . Consequently, the power consumption can be minimized.
  • the employed mechanism include the rocker arm 96 as shown in FIG. 17 .
  • FIG. 18 A method for changing the position of the motor 50 for the valve mechanism 36 in accordance with the drive scheme for a vehicle in which the internal combustion engine 10 is mounted will now be described with reference to FIG. 18 .
  • the vehicle in which the internal combustion engine 10 is mounted is of a front-engine front-drive type, it is necessary to incline the bank when mounting the internal combustion engine 10 in an engine room. It is therefore preferred that the height of the internal combustion engine 10 be minimized. Consequently, when the internal combustion engine 10 is to be mounted in a front-engine front-drive vehicle, it is preferable that the height of the internal combustion engine 10 be minimized by positioning the motors 50 A- 50 H at the ends of the camshafts 54 - 60 , 84 - 90 as shown in FIGS. 2 and 11 . This makes it possible to lower the engine hood and reduce the air resistance of the vehicle.
  • FIG. 18 is a schematic diagram illustrating an example in which, in the bank 80 according to the second embodiment, the motor 50 F for the valve mechanism 36 F is positioned above the camshaft 86 .
  • the cam drive gear 62 for the camshaft 86 is positioned at an end toward the camshaft 84 . If the internal combustion engine 10 is mounted in a front-engine rear-drive vehicle, the internal combustion engine 10 is longitudinally mounted within the engine room. It is therefore preferred that the overall length of the internal combustion engine 10 be minimized. Consequently, when the internal combustion engine 10 is to be mounted in a front-engine rear-drive vehicle, it is preferable that the motor 50 F be positioned above the camshaft 86 as shown in FIG. 18 .
  • the second embodiment varies the relative positions of the cams 64 from those in the normal rotation drive mode. Therefore, the rotation amount of the camshaft 90 for the swing drive mode can be reduced. This makes it possible to reduce the power consumption of the motor 50 H, which drives the camshaft 90 , and provide enhanced system efficiency.
  • the relative angular positions of the cams 64 for two cylinders in the swing drive mode are set so that the cams 64 are positioned 180° apart from each other.
  • the relative angle between the two cams 64 may be smaller than 180° as far as the cam lift sections of the two cams 64 do not overlap in the swing drive mode.
  • FIGS. 19A and 19B illustrate examples in which the relative angle between the seventh-cylinder cam 64 and the fifth-cylinder cam, which are shown in FIG. 14B , is smaller than 180° (e.g., 160°).
  • the intake valves 32 of the seventh cylinder can be driven when swing drive is provided in the state shown in FIG. 19A .
  • the camshaft 90 is rotated in the direction of the arrow in FIG. 19A to set the angular position of the camshaft 90 as shown in FIG. 19B after the intake valves 32 of the seventh cylinder are completely driven, the intake valves 32 of the fifth cylinder can be driven.
  • the rotation angle of the camshaft 90 for a change can be rendered smaller than when the relative angle between the seventh-cylinder cam 64 and the fifth-cylinder cam is set at 1800. Consequently, it is preferable that the relative angle between the cams for two cylinders in the swing drive mode be minimized without causing the cam lift sections to overlap.
  • the third embodiment drives the intake valves 32 and exhaust valves 34 to properly control the oxygen occlusion amounts of the catalysts 42 , 44 during a fuel cut-off operation.
  • the oxygen occlusion amounts of the catalysts 42 , 44 vary with the operating state of the internal combustion engine 10 .
  • the oxygen occlusion amounts of the catalysts 42 , 44 increase due to an increase in the amount of oxygen in the exhaust.
  • control is exercised to provide a rich air-fuel ratio
  • the oxygen occlusion amounts decrease because oxygen is released from the downstream catalysts 42 , 44 due to an increase in the amount of reducing components in the exhaust.
  • the exhaust air-fuel ratio becomes rich and a large amount of oxygen is released from the catalysts 42 , 44 . Consequently, the catalysts 42 , 44 are placed in a reduction condition so that the odor of catalysts may be emitted.
  • the present embodiment exercises control (fuel cut-off) to shut off the fuel supply from the fuel injection valve 30 .
  • control fuel cut-off
  • the present embodiment closes the exhaust valves 34 of all cylinders during fuel cut-off to stop the air flow to the exhaust path 14 and shut off the oxygen supply to the catalysts 42 , 44 . This makes it possible to prevent the amounts of oxygen supply to the catalysts 42 , 44 from increasing excessively and properly suppress the deterioration of the catalysts 42 , 44 .
  • a fuel cut-off operation is mainly performed at the time of deceleration. Therefore, when the exhaust valves 34 of all cylinders are closed during fuel cut-off, the present embodiment opens predetermined intake valves 32 to perform proper pumping work and apply the engine brake during fuel cut-off driving.
  • FIGS. 20A and 20B are schematic diagrams illustrating how the present embodiment controls the intake valves 32 and exhaust valves 34 .
  • the internal combustion engine 10 according to the present embodiment includes four cylinders (first to fourth cylinders). The four cylinders are serially arranged. An explosion stroke is performed in the first, third, fourth, and second cylinders in the order named.
  • FIG. 20A shows how the exhaust valves 34 are controlled during fuel cut-off.
  • FIG. 20B shows how the intake valves 32 are controlled during fuel cut-off.
  • exhaust valve control is exercised so as to close the exhaust valves 34 of all cylinders during fuel cut-off. This makes it possible to stop the air flow to the exhaust path 14 and properly prevent the catalysts 42 , 44 from deteriorating due to excessive oxygen supply.
  • intake valve control is exercised so as to open only the intake valves 32 of the first and second cylinders. Pumping work can then be performed to exchange air between the first and second cylinders as described in detail later. Consequently, engine braking force can be generated while a fuel cut-off operation is performed for deceleration.
  • FIG. 21 is a schematic diagram illustrating the configuration of a section around the exhaust valves 34 and the valve mechanism 38 for driving the exhaust valves 34 .
  • the valve mechanism 38 drives the exhaust valves 38 of all cylinders (first to fourth cylinders).
  • the configuration of the intake valves 32 and valve mechanism 36 will be described later.
  • the third embodiment also assumes that each cylinder of the internal combustion engine 10 has two intake valves 32 and two exhaust valves 34 .
  • the valve mechanism 38 includes a motor 116 , which serves as a driving source, a gear train 118 , which serves as a mechanism for transmitting the rotary motion of the motor 116 , and a camshaft 120 , which converts the rotary motion transmitted from the gear train to a linear open/close motion of the exhaust valves 34 .
  • the rotary motion of the motor 116 is transmitted to the camshaft 120 through the gear train 118 .
  • the camshaft 120 includes a camshaft 120 A and a camshaft 120 B.
  • the camshaft 120 A is positioned above the exhaust valves 34 of the first, second, and third cylinders, and equipped with six cams 64 that drive the exhaust valves 34 of the first, second, and third cylinders.
  • the camshaft 120 B is positioned above the exhaust valves 34 of the fourth cylinder, and equipped with two cams 64 that drive the exhaust valves 34 of the fourth cylinder.
  • the periphery of the camshaft 120 A is provided with a cam drive gear 62 that rotates together with the camshaft 120 A.
  • each exhaust valve 34 is provided with a lifter 34 a .
  • Each cam 64 on the camshaft 120 comes into contact with the lifter 34 a and pushes the lifter 34 a downward to drive each exhaust valve 34 .
  • FIG. 22 is a schematic diagram illustrating in detail the configuration of the camshaft 120 .
  • the camshaft 120 A has a flange section 66 at its end.
  • the camshaft 120 B has a flange section 68 at its end.
  • the flange section 68 of the camshaft 120 B has a shaft 69 that protrudes from the center of the flange section 68 toward the camshaft 120 A.
  • the camshaft 120 A and camshaft 120 B are unified as the shaft 69 turnably fits into the hole 67 , thereby bringing the end face of the flange section 66 into contact with the end face of the flange section 68 .
  • FIGS. 23A and 23B are schematic diagrams illustrating the end faces of the flange sections 66 , 68 that are provided for the camshaft 120 A and camshaft 120 B.
  • FIG. 23A shows the end face of the flange section 66 of the camshaft 120 A
  • FIG. 23B shows the end face of the flange section 68 of the camshaft 120 B.
  • the end faces of the flange sections 66 , 68 are configured the same as the counterparts according to the first embodiment, which are described with reference to FIGS. 6A and 6B . More specifically, the flange section 66 has a reference surface 66 A and a protrusion surface 66 B. The boundary between the reference surface 66 A and protrusion surface 66 B is provided with stepped sections 66 C, 66 D. Similarly, the flange section 68 has a reference surface 68 A and a protrusion surface 68 B. The boundary between the reference surface 68 A and protrusion surface 68 B is provided with stepped sections 68 C and 68 D.
  • the protrusion surface 68 B of the flange section 68 is provided with a lock pin 74 .
  • the lock pin 74 protrudes from the protrusion surface 68 B toward the camshaft 120 A.
  • the camshaft 120 A and camshaft 120 B can relatively rotate.
  • the lock pin 74 is inserted into the hole 70 , the relative rotational positions of the camshaft 120 A and camshaft 120 B are locked.
  • FIGS. 24A and 24B are schematic diagrams that relate to a situation where the camshaft 120 A and camshaft 120 B are coupled together and illustrate the angular positions of the cams 64 on the camshaft 120 A and the cams 64 on the camshaft 120 B.
  • FIGS. 24A and 24B indicate that the lift of the fourth-cylinder exhaust valve 34 varies with the angular position of a cam 64 on the camshaft 120 B.
  • FIGS. 24A and 24B are views of the camshaft 120 as taken in the direction of arrow X in FIG. 22 .
  • FIG. 24A shows a state in which the lock pin 74 in inserted into the hole 70 .
  • FIG. 24B shows a state in which the lock pin 74 is disengaged from the hole 70 .
  • the state shown in FIG. 24A is set when the intake valve 32 is opened/closed during a normal operation (in the normal rotation drive mode or swing drive mode).
  • a normal operation in the normal rotation drive mode or swing drive mode.
  • an explosion stroke is performed in each cylinder at intervals of 180° crank angle. Since the camshaft 120 makes one revolution while the crankshaft makes two revolutions, the explosion stroke is performed in each cylinder each time the camshaft rotates 90°. Therefore, in a normal operating state in which the lock pin 74 is engaged with the hole 70 , the cams 64 for the first, third, fourth, and second cylinders are arranged in the order named and at intervals of 90° as shown in FIG. 24A .
  • FIG. 24B shows a state in which the lock pin 74 is disengaged from the hole 70 in the state shown in FIG. 24A and the camshaft 120 B is rotated relative to the camshaft 120 A. Since the mechanism for driving the lock pin 74 is configured the same as in the first and second embodiments, the lock pin 74 is driven in the same manner as described in conjunction with the first and second embodiments. More specifically, in the state shown in FIG. 24A , oil is supplied from the oil path 79 in the camshaft 120 B to the oil path 77 . In the state shown in FIG. 24A , the angular position of the oil path 77 agrees with that of the oil path 78 in the flange section 66 .
  • the oil is supplied from the oil path 77 to the hole 70 through the oil path 78 .
  • the hole 70 is filled with the oil so that the lock pin 74 is hydraulically received. This makes it possible to disengage the lock pin 74 from the hole 70 . Since the crankshaft 47 rotates even when a fuel cut-off operation is being performed, the oil can be supplied to the oil path 79 by driving an oil pump.
  • FIG. 24B shows a state in which the camshaft 120 B is further rotated after exhaust valve closure to bring the stepped section 66 D into contact with the stepped section 68 D.
  • the stepped section 66 D is in contact with the stepped section 68 D
  • the angular position of the third-cylinder cam agrees with that of the fourth-cylinder cam.
  • the exhaust valves 34 of the first to third cylinders are already closed. Therefore, in the state shown in FIG. 24B in which the lock pin 74 is disengaged from the hole 70 , the exhaust valves 34 of all cylinders (first to fourth cylinders) can be closed.
  • the valve mechanism 38 may include two motors, which respectively control the camshaft 120 A and camshaft 120 B. In this case, too, the exhaust valves 34 of all cylinders can be closed by setting the angular positions of the camshafts 120 A, 120 B as shown in FIG. 24B .
  • FIG. 25 is a schematic diagram illustrating the configuration of a section around the intake valves 32 and the valve mechanism 36 for driving the intake valves 32 .
  • This figure mainly shows the configuration of a section around a cylinder head.
  • the valve mechanism 36 includes two devices (valve mechanism 36 G and valve mechanism 36 H).
  • the valve mechanism 36 G drives the intake valves 32 of the second and third cylinders
  • the valve mechanism 36 H drives the intake valves 32 of the first and fourth cylinders.
  • valve mechanisms 36 G, 36 H include motors 50 G, 50 H, respectively, as a driving source.
  • the rotary motion of the motor 50 G is transmitted to a camshaft 110 A through a gear train 52 G.
  • the rotary motion of the motor 50 H is transmitted to a camshaft 110 B through a gear train 52 H.
  • the camshaft 110 A is positioned above the intake valves 32 of the second and third cylinders.
  • Four cams on the camshaft 110 A open/close the intake valves 32 of the second and third cylinders.
  • the camshaft 110 B is divided into two sections, which are positioned above the intake valves 32 of the first and fourth cylinders.
  • Four cams 64 on the camshaft 110 B open/close the intake valves 32 of the first and fourth cylinders.
  • the two sections of the camshaft 110 B rotate together because they are joined by a coupling member 110 C that is inserted into a through-hole in the center of the camshaft 110 .
  • FIG. 25 shows the camshaft 110 A and the two sections of the camshaft 110 B while they are separated from each other.
  • each intake valve 32 is provided with a lifter 32 a .
  • Each cam 64 on the camshafts 110 A, 110 B comes into contact with the lifter 32 a and pushes the lifter 32 a downward to drive each intake valve 32 .
  • the present embodiment opens only the intake valves 32 of the first and second cylinders by a predetermined amount by changing the relative angular positions of the camshaft 110 A and camshaft 110 B.
  • Gas exchange can then be made between the first and second cylinders to perform proper pumping work.
  • the intake valves 32 of the third and fourth cylinders close.
  • the intake valves 32 of the third and fourth cylinders close when the pistons 44 of the third and fourth cylinders are positioned midway between the top dead center and bottom dead center.
  • the exhaust valves 34 of the third and fourth cylinders are already closed. If the intake valves 32 close when a piston 44 is positioned close to the bottom dead center, the amount of air compressed when the piston 44 moves toward the top dead center increases to exhibit greater resistance.
  • FIG. 26 is a schematic diagram illustrating how gas is exchanged between the first and second cylinders.
  • This figure is a top view of the internal combustion engine 10 and intake path 12 .
  • the intake path 12 branches off downstream of the surge tank 28 and connects to all cylinders (first to fourth cylinders). Since the cylinders are connected via the surge tank 28 , gas exchange can be made between the first and second cylinders when only the intake valves 32 of the first and second cylinders are opened with all the exhaust valves 34 closed.
  • the air expelled from the first cylinder due to an ascent of the piston 44 of the first cylinder flows backward within the intake path 12 , reaches the surge tank 28 , and is taken into the second cylinder due to a descent of the piston 44 of the second cylinder.
  • the lift amount for the intake valves 32 of the first cylinder is made equal to the lift amount for the intake valves 32 of the second cylinder. This ensures that the air expelled from the first cylinder is taken into the second cylinder without excess or deficiency, and that the air expelled from the second cylinder is taken into the first cylinder without excess or deficiency. This prevents the amount of air expelled from one cylinder from exceeding the amount of air taken into the other cylinder, thereby inhibiting excess air from flowing backward toward the throttle valve 22 . The above also prevents the amount of air taken into one cylinder from exceeding the amount of air expelled from the other cylinder, thereby inhibiting an unnecessary negative pressure from being generated in the intake path 12 due to intake amount insufficiency.
  • the amount of pumping work can be adjusted by changing the lift amounts of the intake valves 32 of the first and second cylinders while ensuring that they are equal. Decreasing the lift amounts for the intake valves 32 increases the resistance produced when air passes through the intake valves 32 , thereby increasing the amount of pumping work. This provides increased engine braking force. On the other hand, increasing the lift amounts for the intake valves 32 decreases the resistance produced when air passes through the intake valves 32 , thereby decreasing the amount of pumping work. This provides decreased engine braking force. Therefore, optimum engine braking force can be generated during fuel cut-off by controlling the lift amounts for the intake valves 32 .
  • the required vehicle speed level e.g., the amount of brake pedal depression
  • FIG. 27 shows the period during which the intake valves 32 of various cylinders (first to fourth cylinders) are open (indicated by solid lines in FIG. 27 ) and the period during which the exhaust valves 34 of various cylinders are open (indicated by broken lines in FIG. 26 ).
  • an explosion stroke is performed in the first, third, fourth, and second cylinders in the order named. Therefore, the intake valves 32 and exhaust valves 34 of various cylinders open in a sequence that is indicated in FIG. 27 .
  • crank angle ⁇ 1 corresponds to the position of the camshaft 120 that is shown in FIG. 24A . It is a crank angle position that prevails immediately after the lift of the fourth-cylinder exhaust valves 34 is maximized. More specifically, when the camshaft 120 is stopped at the position of crank angle ⁇ 1 , the rotational position of the camshaft 120 is set as indicated in FIG. 24A so that the fourth-cylinder exhaust valves 34 are opened by a predetermined amount that is smaller than the maximum lift amount. Further, the exhaust valves 34 of the other cylinders (first to third cylinders) are all closed.
  • the camshaft 120 B can now rotate relative to the camshaft 120 A.
  • the camshaft 120 B rotates in the direction of arrow Y in FIG. 24A due to the reaction force of valve springs for the fourth-cylinder exhaust valves 34 .
  • the relative angular positions of the camshaft 120 A and camshaft 120 B are then set as shown in FIG. 24B so that the exhaust valves 34 of the fourth cylinder close. Consequently, the exhaust valves 34 of all cylinders close.
  • crank angle ⁇ 1 When crank angle ⁇ 1 is reached, actual control is exercised so as to stop the camshaft 120 and drive the lock pin 74 at virtually the same time. Therefore, the camshaft 120 B instantaneously rotates to the state shown in FIG. 24B . Consequently, the exhaust valves 34 of the fourth cylinder can be closed the moment crank angle ⁇ 1 is reached, as shown in FIG. 26 .
  • control is exercised to open the intake valves 32 of the first and second cylinders by a predetermined amount.
  • the intake valves 32 of the third cylinder are open at the position of crank angle ⁇ 1 . Therefore, control is exercised to close the third-cylinder intake valves 32 at the position of crank angle ⁇ 2 , which is shown in FIG. 27 , and stop the rotation of the camshaft 110 A.
  • crank angle increases by a predetermined amount from ⁇ 2 and reaches ⁇ 3
  • control is exercised to open the intake valves 32 of the first and second cylinders by a predetermined amount. More specifically, the intake valves 32 of the second cylinder are lifted by a predetermined amount by placing the camshaft 110 A at a predetermined angular position after crank angle ⁇ 3 is reached. In this instance, it is possible to lift only the second-cylinder intake valves 32 because the second-cylinder and third-cylinder cams 64 on the camshaft 111 A are 90° out of phase with each other.
  • the camshaft 110 B is set at a predetermined angular position to lift the first-cylinder intake valves 32 and second-cylinder intake valves 32 by the same amount.
  • the two camshafts 110 B are joined by the coupling member 110 C and equipped with the first-cylinder cams 64 and fourth-cylinder cams 64 .
  • the first-cylinder cams 64 and fourth-cylinder cams 64 are 90° out of phase with each other. Therefore, it is possible to lift only the intake valves 32 of the first cylinder.
  • the motor 116 drives the camshaft 120 A for the exhaust valves 34 .
  • the camshaft 120 A then rotates relative to the camshaft 120 B.
  • the acting force of the spring 76 inserts the lock pin 74 into the hole 70 .
  • the camshaft 120 A and camshaft 120 B are then unified.
  • a normal operation can be conducted in the normal rotation drive mode or swing drive mode.
  • a normal operation can be conducted in the normal rotation drive mode or swing drive mode by normally driving the motor 38 G and motor 38 H.
  • the third embodiment can stop the air flow to the exhaust path 14 because it closes the exhaust valves 34 of all cylinders during fuel cut-off. This makes it possible to stop the supply of oxygen to the catalysts 42 , 44 , and avoid an excessive supply of oxygen to the catalysts 42 , 44 . Consequently, the deterioration of the catalysts 42 , 44 can be properly suppressed.
  • the third embodiment opens, by a predetermined amount, only the intake valves 32 of two cylinders that are 180 crank angle degrees out of phase with each other. Therefore, gas exchange can be made between the two cylinders through the intake path 12 and surge tank 28 . This makes it possible to perform appropriate pumping work and properly apply the engine brake during a fuel cut-off operation.
  • the third embodiment closes all exhaust valves 34 and opens only some intake valves 32 during fuel cut-off.
  • an alternative is to close all intake valves 32 and open only some exhaust valves 34 during fuel cut-off. In this alternative case, too, it is possible to stop the air flow to the exhaust path 14 by closing all intake valves 32 and generate engine braking force by opening only some exhaust valves 34 .

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Valve Device For Special Equipments (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
US11/918,476 2005-04-28 2006-04-18 Valve Mechanism for Internal Combustion Engine Abandoned US20090050087A1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
JP2005133347 2005-04-28
JP2005-133347 2005-04-28
JP2005329111A JP2006329181A (ja) 2005-04-28 2005-11-14 内燃機関の動弁装置
JP2005-329111 2005-11-14
PCT/JP2006/308495 WO2006118063A1 (ja) 2005-04-28 2006-04-18 内燃機関の動弁装置

Publications (1)

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US20090050087A1 true US20090050087A1 (en) 2009-02-26

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US11/918,476 Abandoned US20090050087A1 (en) 2005-04-28 2006-04-18 Valve Mechanism for Internal Combustion Engine

Country Status (4)

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US (1) US20090050087A1 (enExample)
EP (1) EP1878882A4 (enExample)
JP (1) JP2006329181A (enExample)
WO (1) WO2006118063A1 (enExample)

Cited By (5)

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US20110264359A1 (en) * 2010-04-21 2011-10-27 Honda Motor Co., Ltd. Engine control system and method for stopping engine at desired engine stopping position
US20120006291A1 (en) * 2010-01-18 2012-01-12 Toyota Jidosha Kabushiki Kaisha Control apparatus for internal combustion engine
US20140032083A1 (en) * 2012-07-24 2014-01-30 Ford Global Technologies, Llc Variable valve timing for cylinder deactivation
US20180106198A1 (en) * 2016-10-19 2018-04-19 Mazda Motor Corporation Variable valve train for engine
US20180128190A1 (en) * 2015-07-08 2018-05-10 Volkswagen Aktiengesellschaft Method for switching, in an efficiency-optimized manner, a four-stroke internal combustion engine including a plurality of cylinders and a fully variable valve train between a full cylinder operation and a partial cylinder operation

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB201520766D0 (en) * 2015-11-24 2016-01-06 Camcon Auto Ltd Stator assembly
CN112727676B (zh) * 2020-12-31 2023-01-03 国投白银风电有限公司 一种快速调节风力发电机组偏航凸轮开关的装置

Citations (2)

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US20040118367A1 (en) * 2002-12-05 2004-06-24 Toyota Jidosha Kabushiki Kaisha Valve-driving system of internal combustion engine
US20070068473A1 (en) * 2003-12-12 2007-03-29 Toyota Jidosha Kabushiki Kaisha Valve gear

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JP4438157B2 (ja) * 2000-02-09 2010-03-24 株式会社デンソー 内燃機関の制御装置
JP2002227694A (ja) * 2001-02-05 2002-08-14 Nissan Motor Co Ltd エンジンのシリンダ吸入空気量算出装置
JP3849510B2 (ja) * 2001-12-04 2006-11-22 トヨタ自動車株式会社 車両のエンジン制御装置
JP4092928B2 (ja) * 2002-03-04 2008-05-28 トヨタ自動車株式会社 車両用制御装置

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040118367A1 (en) * 2002-12-05 2004-06-24 Toyota Jidosha Kabushiki Kaisha Valve-driving system of internal combustion engine
US20070068473A1 (en) * 2003-12-12 2007-03-29 Toyota Jidosha Kabushiki Kaisha Valve gear

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120006291A1 (en) * 2010-01-18 2012-01-12 Toyota Jidosha Kabushiki Kaisha Control apparatus for internal combustion engine
US8443588B2 (en) * 2010-01-18 2013-05-21 Toyota Jidosha Kabushiki Kaisha Control apparatus for internal combustion engine
US20110264359A1 (en) * 2010-04-21 2011-10-27 Honda Motor Co., Ltd. Engine control system and method for stopping engine at desired engine stopping position
US8375912B2 (en) * 2010-04-21 2013-02-19 Honda Motor Co., Ltd. Engine control system and method for stopping engine at desired engine stopping position
US20140032083A1 (en) * 2012-07-24 2014-01-30 Ford Global Technologies, Llc Variable valve timing for cylinder deactivation
US9002624B2 (en) * 2012-07-24 2015-04-07 Ford Global Technologies, Llc Variable valve timing for cylinder deactivation
US20180128190A1 (en) * 2015-07-08 2018-05-10 Volkswagen Aktiengesellschaft Method for switching, in an efficiency-optimized manner, a four-stroke internal combustion engine including a plurality of cylinders and a fully variable valve train between a full cylinder operation and a partial cylinder operation
US10107210B2 (en) * 2015-07-08 2018-10-23 Volkswagen Aktiengesellschaft Method for switching, in an efficiency-optimized manner, a four-stroke internal combustion engine including a plurality of cylinders and a fully variable valve train between a full cylinder operation and a partial cylinder operation
US20180106198A1 (en) * 2016-10-19 2018-04-19 Mazda Motor Corporation Variable valve train for engine

Also Published As

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EP1878882A4 (en) 2009-10-21
JP2006329181A (ja) 2006-12-07
WO2006118063A1 (ja) 2006-11-09
EP1878882A1 (en) 2008-01-16

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