Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • 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
  • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
  • F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
  • F01L13/0036—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/12—Transmitting gear between valve drive and valve
  • F01L1/18—Rocking arms or levers
• • 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
  • F01L1/185—Overhead end-pivot rocking arms
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/26—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/26—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder
  • F01L1/267—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of two or more valves operated simultaneously by same transmitting-gear; peculiar to machines or engines with more than two lift-valves per cylinder with means for varying the timing or the lift of the valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
  • F01L13/0005—Deactivating valves
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
  • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
  • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
  • F01L13/0015—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque
  • F01L13/0036—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction
  • F01L2013/0052—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for optimising engine performances by modifying valve lift according to various working parameters, e.g. rotational speed, load, torque the valves being driven by two or more cams with different shape, size or timing or a single cam profiled in axial and radial direction with cams provided on an axially slidable sleeve
• • 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
  • F01L2820/031—Electromagnets

Definitions

• the invention relates to a variable valve actuation apparatus for an internal combustion engine.
• JP-A-6-33714 discloses a variable valve actuation apparatus for an internal combustion engine.
• This related-art variable valve actuation apparatus includes an intake or exhaust valve, a low-speed cam, a high-speed cam, a main rocker arm that is drivable by the low-speed cam and that drives the intake valve or the exhaust valve, and a sub-rocker arm that is driven by the high-speed cam.
• the variable valve actuation apparatus includes a hydraulic piston mechanism as mode switch means for switching between a non-coordination mode in which the sub-rocker arm is not coordinated with the main rocker arm and a coordination mode in which the sub-rocker arm is coordinated with the main rocker arm.
• the actuator's drive force needed in order to drive a member that is driven by the actuator becomes inconveniently large if the inertia of the member is large, or if the friction force that occurs on the member when the actuator drives the member is large. Therefore, in order to switch the opening characteristic of valves while minimizing the required power, it is desirable that the inertia of the foregoing member be small and that the friction force that occurs on the member be small.
• the invention provides a variable valve actuation apparatus for an internal combustion engine which reduces the inertia of a member that is driven by an actuator and reduces the friction that occurs on the member, and which favorably switches the opening characteristic of valves that are provided for at least two cylinders of the engine in association with motion performed by the actuator.
• a variable valve actuation apparatus for an internal combustion engine in accordance with a first aspect of the invention includes: transfer members that are disposed between cams and valves and that transfer operating force of the cams to the valves; a camshaft on which the cams are provided; a guide rail provided on an outer peripheral surface of a cylindrical portion that is provided on the camshaft; a main displacement member which has an engagement portion that is engageable with and disengageable from the guide rail and which is displaceable in an axis direction of the camshaft; a member-linked shaft which is linked to the main displacement member in such a manner that, relative to the member linked shaft, the main displacement member is allowed to rotate and is constrained from moving in the axis direction; and an actuator that produces drive force for engaging the engagement portion of the main displacement member with the guide rail, wherein when the actuator operates, the main displacement member rotates about the member-linked shaft so that the engagement portion engages with the guide rail, and in association with displacement of the main displacement member and the member-linked shaft that occurs when the
• the main displacement member and the member-linked shaft is linked together in such a manner that relative rotation therebetween is possible, the main displacement member rotates alone without involving rotation of the member-linked shaft, when the actuator operates so as to engage the engagement portion of the main displacement member with the guide rail. Therefore, according to the first aspect, it becomes possible to reduce the inertia of the member that is driven by the actuator and reduce the friction force that occurs on the member, and to favorably switch the opening characteristic of valves that are provided for at least two cylinders in association with motion performed by the actuator.
• the main displacement member, the guide rail and the actuator may be provided corresponding to at least one but not all of the cylinders of the internal combustion engine
• the variable valve actuation apparatus may further include a subsidiary displacement member which is provided for at least one other cylinder that is not provided with the main displacement member, and which is displaced in operative connection with the main displacement member via the member-linked shaft, and the state of motion of the transfer member provided for the cylinder that is provided with the main displacement member may change in association with the displacement of the main displacement member that occurs when the engagement portion and the guide rail are engaged, and the state of motion of the transfer member provided for the at least one other cylinder that is provided with the subsidiary displacement member may change in association with the displacement of the subsidiary displacement member which is in operative connection with the displacement of the main displacement member.
• the inertia of the member that is driven by the actuator can be reduced, and the friction force that occurs on the member can be reduced.
• the state of motion of the transfer member of each cylinder can be changed through the utilization of the displacement of the main displacement member and the displacement of the subsidiary displacement member that is in operative connection with the displacement of the main displacement member.
• the transfer member for each of the at least two cylinders, may include a first rocker arm that is oscillatable synchronously with the cams, and a second rocker arm that is able to push the valves
• the variable valve actuation apparatus may further include a switch pin that is disposed movably in a pin hole formed in the first rocker arm and in a pin hole formed in the second rocker arm, and the switch pin for the cylinder provided with the main displacement member may be displaced in operative connection with the displacement of the main displacement member, and the switch pin for the at least one cylinder that is provided with the subsidiary displacement member may be displaced in operative connection with the displacement of the subsidiary displacement member, and for the cylinder provided with the main displacement member, the first rocker arm and the second rocker arm may be switched via the switch pin between a linked state in which the first rocker arm and the second rocker arm are linked together and an unlinked state in which linkage between the first rocker arm and the second rocker arm is removed, in
• the member-linked shaft may be disposed within a rocker shaft that supports the first rocker arms and the second rocker arms.
• the second rocker arm may be used for a plurality of the valves that are provided for a cylinder.
• a mounting space for the main displacement member and the subsidiary displacement member can be secured by utilizing the unoccupied space obtained as a result of the use of the second rocker arm for two or more valves provided for a cylinder, in comparison with a construction in which one valve is driven by one second rocker arm.
• an outer peripheral surface of the member-linked shaft may be provided with a groove that has an annular or arcuate shape, and the member-linked shaft may penetrate an interior of the main displacement member, and the variable valve actuation apparatus may further include a pin that penetrates the main displacement member and that engages with the groove.
• FIG. 1 is a perspective view showing a variable valve actuation apparatus for an internal combustion engine according to an embodiment of the invention
• FIG. 2A and FIG. 2B are sectional views of portions of the variable valve actuation apparatus shown in FIG. 1, except a camshaft, which are taken on a plane that includes the axis of a rocker shaft shown in FIG 1 and the axis of a switch pin also shown in FIG. 1;
• FIG 3 is an exploded perspective view of characteristic component elements of the variable valve actuation apparatus shown in FIG 1;
• FIG 4 is a view of the variable valve actuation apparatus of FIG. 1 which is taken in an axis direction of the camshaft (and the rocker shaft) (more specifically, the direction indicated by an arrow 4A in FIG 2A).
• FIG 1 is a perspective view showing a variable valve actuation apparatus 10 for an internal combustion engine 1 according to Embodiment 1 of the invention.
• FIG 1 the illustration of a later-described camshaft 18 is omitted.
• FIG 1 shows only two cylinders (cylinders No. 1 and No.
• the internal combustion engine 1 of Embodiment 1 is, for example, an in-line four-cylinder engine that has four cylinders (No. 1 to No. 4). Besides, each cylinder of the internal combustion engine 1 is provided with two intake valves and two exhaust valves.
• the variable valve actuation apparatus 10 functions as an apparatus that drives two intake valves or two exhaust valves that are disposed on each cylinder.
• each cylinder of the internal combustion engine 1 is provided with a first rocker arm 12 and a second rocker arm 14 that are adjacent to each other.
• the rocker arms 12 and 14 of each cylinder are rotatably (oscillatably) supported by one rocker shaft 16.
• FIG. 2A and FIG 2B are sectional views of portions of the variable valve actuation apparatus 10 excluding a camshaft 18, which are taken on a plane that includes the axis of the rocker shaft 16 shown in FIG. 1 and the axis of a switch pin 38 described below.
• FIG. 2A shows the variable valve actuation apparatus 10 in a linked state described below
• FIG 2B shows the variable valve actuation apparatus 10 in an unlinked state described below.
• the camshaft 18 is linked to a crankshaft (not shown) by a timing chain or a timing belt so as to rotate at half the speed of the crankshaft.
• the camshaft 18 is provided with a main cam 20 and a subsidiary cam 22 for each cylinder.
• the rocker shaft 16 is disposed parallel to the camshaft 18.
• the main cams 20 are each constructed as a cam that has an arcuate base circle portion that is coaxial with the camshaft 18 (i.e., a lift cam), and a nose portion formed so that a portion of the base circle portion is expanded radially outward.
• the subsidiary cams 22 are each constructed as a cam that has only a base circle portion (i.e., a zero-lift cam).
• the first rocker arm 12 has a first roller 24 that is rotatably attached at such a position on the first rocker arm 12 that the first roller 24 can contact the main cam 20.
• the first rocker arm 12 is urged so that the first roller 24 is always in contact with the main cam 20, by a coil spring (not shown) that is attached to the rocker shaft 16.
• the first rocker arm 12 constructed as described above oscillates about the rocker shaft 16 that serves as a fulcrum, through cooperation of the operating force of the main cam 20 and the force of the aforementioned coil spring.
• the second rocker arm 14 has a second roller 26 that is rotatably attached at such a position on the second rocker arm 14 that the second roller 26 can contact the subsidiary cam 22.
• the rocker shaft 16 is supported by a cam carrier 27 (or a cylinder head or the like) that is a stationary member of the internal combustion engine 1, via a lash adjuster (not shown).
• the second roller 26 provided on the second rocker arm 14 is urged toward the subsidiary cam 22 as the second roller 26 receives upward force from the lash adjuster.
• an opposite end portion of the second rocker arm 14 from the rocker shaft side thereof is provided with a contact portion 14a that contacts two valves 28.
• the second rocker arm 14 is used for both valves 28. More specifically, the second rocker arm 14 is disposed so as to be at an intermediate position between the two valves 28 that are provided for each cylinder. Besides, each valve 28 is urged in the closing direction by a valve spring 30 as shown in FIG 1.
• variable valve actuation apparatus 10 includes a switching mechanism 32 that switches between the linked state in which the first rocker arm 12 and the second rocker arm 14 are linked together (see FIG 2A) and the unlinked state in which the linkage between the first rocker arm 12 and the second rocker arm 14 is removed. Due to the provision of the switching mechanism 32, the opening characteristic of the valves 28 is switched by switching between the state in which the operating force of the main cam 20 is transferred to the second rocker arm 14 via the first rocker arm 12 (the foregoing linked state) and the state in which the operating force of the main cam 20 is not transferred to the second rocker arm 14 (the foregoing unlinked state).
• a first pin hole 34a concentric with the first roller 24 is formed within a spindle 34 of the first roller 24.
• a second pin hole 36a concentric with the second roller 26 is formed within a spindle 36 of the second roller 26.
• the centers of the pin holes 34a and 36a are disposed on an arc whose center is the rocker shaft 16, which is the rotation center of the rocker arms 12 and 14. Then, when the first roller 24 is in contact with the base circle portion of the main cam 20 and the second roller 26 is in contact with the base circle portion of the subsidiary cam 22, the position of the first pin hole 34a coincides with the position of the second pin hole 36a in a view in the axis direction.
• a cylindrical switch pin 38 is slidably disposed in the pin holes 34a and 36a. Besides, an opposite end portion of the first pin hole 34a from the second rocker arm 14 is closed, and a second rocker arm 14-side end portion of the first pin hole 34a is open.
• the first pin hole 34a contains therein a return spring 40 that urges the switch pin 38 in the direction to the second rocker arm 14 (hereinafter, referred to as "advancement direction of the switch pin"). More specifically, the return spring 40 is constructed so as to always urge the switch pin 38 to the second rocker arm 14 side when it is actually mounted.
• the second pin hole 36a is a penetration hole in which a cylindrical piston 42 is slidably inserted. Furthermore, for the cylinder No. 1, a first link arm 44 that has an arm portion 44a that contacts the piston 42 is disposed at a side surface of the second rocker arm 14 opposite the first rocker arm 12-side surface thereof. The first link arm 44 is attached to the rocker shaft 16.
• a second link arm 46 that has an arm portion 46a that contacts the piston 42 is disposed at a side surface of the second rocker arm 14 opposite the first rocker arm 12-side surface thereof.
• the second link arm 46 is attached to the rocker shaft 16.
• the first link arm 44 is different from the second link arm 46 in the following respects. That is, a distal end of the arm portion 44a of the first link arm 44 is provided with a projected portion 44b that is projected toward a peripheral surface of the camshaft 18. Besides, an opposite end portion of the first link arm 44 from the arm portion 44a is provided with a pressurization surface 44c that is pressurized by an electromagnetic solenoid 54 (described below).
• the link arms provided for the cylinders No. 3 and No. 4 are the same as the second link arm 46 of the cylinder No. 2.
• FIG 3 is an exploded perspective view of characteristic component elements of the variable valve actuation apparatus 10 shown in FIG 1.
• FIG. 3 omits the first roller 24, the second roller 26, the switch pin 38 disposed in the first and second rollers, etc.
• FIG 4 shows a view of the variable valve actuation apparatus 10 of FIG. 1 which is taken from the axis direction of the camshaft 18 (and of the rocker shaft 16) (more specifically, from the direction indicated by the arrow 4A in FIG. 2A).
• the rocker shaft 16 has a hollow shape.
• a link shaft 48 is inserted slidably relative to the rocker shaft
• the link shaft 48 is provided for enabling the first link arm 44 disposed for the cylinder No. 1 and the second link arms 46 disposed for the cylinders No. 2 to No. 4 to be simultaneously displaced in the axis direction of the rocker shaft 16.
• the link shaft 48 is provided with four annular grooves 48a that correspond to the placement sites of the link arms 44 and 46 of the four cylinders, as shown mainly in FIG 3. Besides, a peripheral surface of the rocker shaft 16 is provided with four penetration holes 16a that correspond to the annular grooves 48a of the link shaft 48.
• the link shaft 48 and the rocker shaft 16 in which the link shaft 48 is inserted penetrate an interior of each link arm 44, 46.
• the link arms 44 and 46 have press-fit pin holes 44d and 46b, respectively, each of which receives a press-fit pin 50 that is press-fitted thereinto, as shown in FIG 3.
• the press-fit pins 50, each penetrating a wall of a corresponding one of the link arms 44 and 46 through its pressure-fit hole 44d, 46b, are engaged with the corresponding annular grooves 48a, as shown in FIG 4.
• each penetration hole 16a of the rocker shaft 16 has such a generous size as to avoid causing interference between the press-fit pin 50 and the electromagnetic solenoid 54 and therefore avoid impeding the rotation of the first link arm 44 (or the second link arm 46) when the first link arm 44 (or the second link arm 46) rotates in association with motion of the electromagnetic solenoid 54.
• each penetration hole 16a has such an elongated hole shape as to avoid causing interference between the penetration hole 16a and the press-fit pin 50 and therefore avoid impeding the movement of the link shaft 48 when the link shaft 48 moves in the axis direction thereof in association with motion of the electromagnetic solenoid 54.
• the first link arm 44 is linked to the link shaft 48 in such a manner that the first link arm 44 is allowed to freely rotate but is constrained from moving in the axis direction of the link shaft 48.
• the second link arms 46 are also linked to the link shaft 48 in such a manner that the second link arms 46 are allowed to freely rotate but are constrained from moving in the axis direction.
• a cylindrical portion 18a that has a cylindrical shape is provided on an outer peripheral surface of the camshaft 18 which faces a projected portion 44b that is provided on the arm portion 44a of the first link arm 44.
• An outer peripheral surface of the cylindrical portion 18a is provided with a helical guide rail 52 that extends in a circumferential direction.
• the guide rail 52 is formed as a helical groove.
• the switching mechanism 32 includes an electromagnetic solenoid 54 as an actuator that produces drive force for causing the projected portion 44b to be engaged with (inserted into) the guide rail 52.
• the electromagnetic solenoid 54 is duty-controlled on the basis of commands from an electronic control unit (ECU) 56.
• the ECU 56 is an electronic control unit that controls the state of operation of the internal combustion engine 1.
• the electromagnetic solenoid 54 is fixed to a stationary member, such as the cam carrier 27 or the like, at such a position that a drive shaft 54a of the solenoid 54 is able to pressurize the pressurization surface 44c of the first link arm 44 toward the guide rail 52.
• the orientation of the helix of the guide rail 52 is set such that when the camshaft 18 rotates in a predetermined rotation direction shown in FIG 4 while the projected portion 44b is inserted in the helical groove, the first link arm 44, the link shaft 48 that moves in operative connection with the first link arm 44, and the second link arms 46 that are driven by the link shaft 48 are displaced in the leftward direction in FIG. 2. More concretely, the leftward direction in FIG. 2 is the direction in which each of the first link arm 44 and the second link arms 46 approaches its adjacent rocker arms 12 and 14 while pushing the switch pin 38 in the withdrawal direction thereof (that is opposite the foregoing advancement direction of the switch pin) against the force of the return spring 40.
• the position of the first link arm 44 in FIG 2A that is, the position of the first link arm 44 at which the switch pin 38 is inserted in both the first pin hole 34a and the second pin hole 36a due to force of the return spring 40, is referred to as "displacement end Pmaxl".
• the first link arm 44 is positioned at the displacement end Pmaxl, the first rocker arm 12 and the second rocker arm 14 assume the foregoing linked state.
• Embodiment 1 is constructed so that the first link arm 44 is displaced between the displacement end Pmaxl and the displacement end Pmax2, in a range determined by the guide rail 52 guiding the projected portion 44b.
• the guide rail 52 is provided with a shallow bottom portion 52c in which the guide rail 52 gradually becomes shallower with rotation of the camshaft 18, as a predetermined section of the guide rail 52 on a terminating end 52b side which is used after the first link arm 44 reaches the displacement end Pmax2.
• the depth of the guide rail 52 except the shallow bottom portion 52c is constant.
• the first link arm 44 is provided with a cut-out portion 44e that is formed in a recess shape by cutting out a portion of the pressurization surface 44c.
• the pressurization surface 44c is provided so that contact thereof with the drive shaft 54a is maintained while the first link arm 44 is displaced from the displacement end Pmaxl to the displacement end Pmax2. Then, the cut-out portion 44e is provided at such a site on the first link arm 44 as to be engageable with the drive shaft 54a when the projected portion 44b is taken out from the guide rail 52 to the surface of the cylindrical portion 18a due to operation of the shallow bottom portion 52c during a state in which the first link arm 44 is positioned at the displacement end Pmax2. [0046] The cut-out portion 44e is formed so as to engage with the drive shaft
• the switching mechanism 32 is constructed of the switch pin 38, the return spring 40, the piston 42, the first link arm 44, the second link arm 46, the link shaft 48, the press-fit pin 50, the guide rail 52, and the electromagnetic solenoid 54 whose electrification is controlled by the ECU 56.
• a valve stop motion is performed when the ECU 56 detects a demand for executing a predetermined valve stop motion, for example, a demand for the fuel-cut of the internal combustion engine 1, and the like.
• a predetermined valve stop motion for example, a demand for the fuel-cut of the internal combustion engine 1, and the like.
• the electrification of the electromagnetic solenoid 54 is started at a predetermined timing.
• the first link arm 44 rotates about the rocker shaft 16 (the link shaft 48) clockwise in FIG 4.
• the first link arm 44 is linked to the link shaft 48 in such a manner as to be rotatable. Therefore, the link shaft 48 does not rotate while the first link arm 44 rotates.
• the first link arm 44 is held in a state in which the projected portion 44b is apart from the camshaft 18 and in which the drive shaft 54a bears the force of the return spring 40. Therefore, the state in which the first rocker arm 12 and the second rocker arm 14 are unlinked from each other, that is, the valve stopped state, is maintained. Besides, according to the motion of the drive shaft 54a holding the first link arm 44 through the utilization of the cut-out portion 44e, it is possible to maintain the valve stopped state while avoiding occurrence of friction and abrasion of the drive shaft 54a associated with the sliding between the drive shaft 54a and the camshaft 18 when the camshaft 18 rotates.
• a valve returning motion for returning the valve state from the valve stopped state to the valve acting state is performed when the ECU 56 detects a demand for executing a predetermined valve returning motion, for example, a demand for return from the fuel-cut (a demand for discontinuation of the fuel-cut), or the like.
• This valve returning motion is started by turning off the electrification of the electromagnetic solenoid 54 at a predetermined timing. When the electrification of the electromagnetic solenoid 54 is turned off, the engagement between the cut-out portion 44e of the first link arm 44 and the drive shaft 54a of the electromagnetic solenoid 54 is removed.
• the force for retaining the switch pin 38 within the first pin hole 34a against the force of the return spring 40 disappears. Due to this, the force of the return spring 40 moves the switch pin 38 in the advancement direction, bringing back the state in which the first rocker arm 12 and the second rocker arm 14 are linked together via the switch pin 38, that is, the state in which the lift motion of the valves 28 can be carried out by the operating force of the main cams 20. Besides, as the switch pin 38 moves in the advancement direction due to the force of the return spring 40, the first link arm 44 (as well as the link shaft 48 and the second link arm 46 that is operatively connected to the first link arm 44) is returned from the displacement end Pmax2 to the displacement end Pmaxl by the piston 42.
• the position of the first link arm 44 in the axis direction is moved between the displacement end Pmaxl and the displacement end Pmax2 by utilizing the turning on and off of the electrification of the electromagnetic solenoid 54, the torque of the camshaft 18, and the force of the return spring 40. Therefore, as for the cylinder No. 1 equipped with the first link arm 44, it becomes possible to switch the motion state of the valves 28 between the valve acting state and the valve stopped state. Furthermore, as for the other cylinders (No. 2 to No.
• the motion state of the valves 28 disposed for the four cylinders of the internal combustion engine 1 can be switched by using one electromagnetic solenoid 54.
• the valve stopped state can be brought about with high response during one rotation of the camshaft 18, by utilizing the torque of the camshaft 18.
• the first link arm 44 is linked to the link shaft 48 in such a manner that, relative to the link shaft 48, the first link arm 44 is allowed to freely rotate but is constrained from moving in the axis direction. According to this linking method, the first link arm 44 will rotate alone without involving rotation of the link shaft 48, when the electromagnetic solenoid 54 presses the first link arm 44. Unlike this construction, in a construction in which the first link arm is fixed to the link shaft, when the first link arm is rotated due to electrification of the electromagnetic solenoid, the link shaft will rotate together therewith.
• the first link arm 44 and the link shaft 48 are constructed so as to be rotatable relative to each other.
• the inertia of the member that is driven by the electromagnetic solenoid 54 in order to engage the projected portion 44b with the guide rail 52 can be made small, and the friction force that occurs on the member can be made small. Therefore, the required thrust of the electromagnetic solenoid 54 can be favorably reduced, and the size of the electromagnetic solenoid 54 can be reduced.
• the first link arm 44 and the second link arms 46 are mounted on the rocker shaft 16 that functions as a support shaft for the first rocker arms 12 and the second rocker arms 14.
• the two valves 28 of each cylinder are simultaneously driven by the second rocker arm 14 that has the contact portion 14a that contacts the two valves 28.
• This construction in comparison with a construction in which one valve is driven by one second rocker arm, makes it possible to utilize the unoccupied space obtained as a result of the use of a second rocker arm 14 for two valves in order to mount the first link arm 44 and the second link arms 46 for switching the motion state of the valves 28. Due to this, by effectively utilizing the space present over the cylinder head of the internal combustion engine 1, it is possible to improve the mountability of the variable valve actuation apparatus 10 on the internal combustion engine 1.
• the link shaft 48 that transfers the drive force of the first link arm 44 engaged with the guide rail 52 to the second link arms 46 of the other cylinders is disposed within the rocker shaft 16.
• This construction in comparison with a construction in which the link shaft is supported by a member apart from the rocker shaft, makes it possible to effectively utilize the space present over the cylinder head of the internal combustion engine 1 in order to improve the mountability of the variable valve actuation apparatus 10 on the internal combustion engine 1.
• the construction eliminates the need for component parts for supporting the link shaft.
• variable valve actuation apparatus of the invention is not limited to the foregoing constructions as long as the opening characteristic of valves that are provided for at least two cylinders is switched as the motion state of a transfer member is switched in association with displacement of a main displacement member and a member-linked shaft which occurs when the engagement portion and the guide rail are engaged.
• the member that is displaced so as to switch the state of motion of the transfer member in association with displacement of the main displacement member and the member-linked shaft which occurs when the engagement portion and the guide rail are engaged is not limited to the switch pin 38.
• the foregoing member may also be a member that causes an operation in which in association with the movement of the main displacement portion and the member-linked shaft, the rocker arm is displaced on the rocker shaft in the axis direction of the rocker shaft, so that the cam that contacts the rocker arm is switched to another cam and therefore the state of motion of the rocker arm is switched.
• the foregoing member may also be a member that causes an operation in which in association with the displacement of the main displacement member and the member-linked shaft, the roller is displaced on the rocker arm in the axis direction of the spindle of the roller, so that the cam that contacts the roller is switched to another cam and therefore the state of motion of the rocker arm (transfer member) is switched.
• the foregoing member may also be a member that causes an operation in which in association with displacement of the main displacement member and the member-linked shaft, the rocker shaft itself is displaced in its own axis direction, so that the cam that contacts the rocker shaft is switched to another cam and therefore the state of motion of the rocker arm is switched.
• the foregoing member may also be a member that causes an operation in which in association with displacement of the main displacement member and the member-linked shaft, the member equipped with two kinds of cams is displaced in the axis direction of the camshaft, so that the cam that contacts the transfer member is switched to another cam and therefore the state of motion of the transfer member is switched.
• Embodiment 1 is described above with reference to an example that is the variable valve actuation apparatus 10 that drives the two valves that are disposed on each one of the four cylinders of the internal combustion engine 1.
• the variable valve actuation apparatus of the invention is not limited to the foregoing constructions but may have any construction as long as the opening characteristics of the valves provided for at least two cylinders are switched. That is, the variable valve actuation apparatus of the invention may be, for example, an apparatus constructed so as to drive the valves of all the cylinders of the internal combustion engine that has two or more cylinders, or may also be an apparatus constructed so as to drive the valves of at least two cylinders of an internal combustion engine that has three or more cylinders.
• the cylinder equipped with elements that correspond to the foregoing components is not limited so, but may be any one or more of the cylinders of the engine as long as the foregoing cylinder does not correspond to each one of the cylinders.
• the first link arm 44 and the second link arms 46 are rotatably supported by utilizing the rocker shaft 16 that is provided for supporting the first rocker arm 12 and the second rocker arms 14.
• the member that supports the main displacement member or the subsidiary displacement member in the invention is not limited to the rocker shaft. That is, the member that supports the main displacement member and the subsidiary displacement member in the invention may be, for example, a shaft that is provided separately from the rocker shaft. Alternatively, the main displacement member and the subsidiary displacement member in the invention may be supported only by a member that functions as a member-linked shaft in the invention (for example, by the ring shaft 48).
• the link shaft 48 is disposed within the rocker shaft 16.
• the technique of disposing the member-linked shaft in the invention is not limited to this disposal, but it is also permissible to adopt, for example, a construction in which a shaft that functions as the member-linked shaft is provided at an outer peripheral side of the rocker shaft.
• the link shaft 48 is provided with the annular grooves 48a that engage with the press-fit pins 50, in order to link the first link arm 44 (and the second link arms 46 as well) to the link shaft 48 in such a manner that the first link arm 44 is allowed to rotate relative to the link shaft 48, and is constrained from moving in the axis direction of the link shaft 48.
• the element provided for realizing the function of linking the main displacement member in such a manner that the main displacement member is allowed to freely rotate and is constrained from moving in the axis direction does not need to be the annular grooves 48a.
• the grooves may be arcuate grooves.
• the subsidiary cams 22 are zero-lift cams
• the subsidiary cam in the invention is not limited to a zero-lift cam. That is, in a construction as in the foregoing variable valve actuation apparatus 10, the subsidiary cams may have a nose portion that achieves a smaller lift than the nose portion of the main cams 20.
• Embodiment 1 described above includes the electromagnetic solenoid 54 as an actuator that produces drive force for engaging the projected portion 44b with the guide rail 52. Therefore, the opening characteristic of the valves 28 can be switched by utilizing the actuator that is excellent in responsiveness.
• the actuator is not limited so, but may also be, for example, a hydraulically driven actuator.
• the main cams 20 function as a "cam” in the first aspect of the invention
• the first rocker arms 12 and the second rocker arms 14 each function as a "transfer member” in the first aspect
• the projected portion 44b functions as an "engagement portion” in the first aspect
• the first link arm 44 functions as a "main displacement member” in the first aspect
• the link shaft 48 functions as a "member-linked shaft” in the first aspect
• the electromagnetic solenoid 54 functions as an "actuator” in the first aspect.
• the second link arms 46 each function as a "subsidiary displacement member” in the first aspect.
• the annular grooves 48a function as a "groove” in the first aspect
• the press-fit pins 50 function as a "pin” in the first aspect.

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

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• 2009
  • 2009-05-28 JP JP2009129481A patent/JP4752949B2/ja not_active Expired - Fee Related
• 2010
  • 2010-05-26 WO PCT/IB2010/001237 patent/WO2010136875A1/en active Application Filing
  • 2010-05-26 EP EP10725857A patent/EP2435670A1/en not_active Withdrawn
  • 2010-05-26 US US13/318,870 patent/US20120055428A1/en not_active Abandoned
  • 2010-05-26 CN CN2010800235187A patent/CN102449275A/zh active Pending
  • 2010-05-26 KR KR1020117028366A patent/KR20120012478A/ko not_active Application Discontinuation

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