JP5447211B2 - Variable valve operating device for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine, and more particularly to a variable valve operating apparatus for an internal combustion engine that changes a valve lift amount by changing a relative position between a swing cam and a roller provided on a rocker arm.

2. Description of the Related Art A valve mechanism of an internal combustion engine includes a mechanism in which a roller provided on a rocker arm that opens and closes an intake valve and an exhaust valve is pushed down directly by a cam of a rotating camshaft to swing the rocker arm. In such a valve operating mechanism, in order to increase the valve lift, the center of the base circle of the cam is arranged on a straight line passing through the center of the roller and parallel to the axis of the valve.
In addition, a valve follower mechanism for an internal combustion engine is provided with a cam follower that contacts the camshaft cam and a rocker cam that contacts the rocker arm roller between the camshaft and the rocker arm, and this rocking cam is linked to the cam follower. In addition, there is a variable valve mechanism that allows the valve lift to be changed by changing the relative position of the swing cam with respect to the rocker arm.

JP 2001-263015 A

  The variable valve mechanism and the intake air amount control device for an internal combustion engine according to Patent Document 1 have a structure in which the valve lift amount can be changed by changing the relative position of the rocking cam with respect to the rocker arm. The rocker cam is moved in a direction orthogonal to the direction away from the exhaust camshaft from above the rocker arm, and a swing cam provided with a cam follower is disposed above the rocker arm.

By the way, conventionally, in the variable valve mechanism of the internal combustion engine according to Patent Document 1 described above, the swing cam has a center of the base circle passing through the center of the roller provided on the rocker arm and on a straight line parallel to the axis of the valve. It is arranged to be located. For this reason, when the valve is lifted to the maximum by the rocking cam, the rocking cam pushes the roller in an oblique direction with respect to the rocking direction of the rocker arm, increasing the sliding resistance of the rocker arm and increasing the durability of the rocker arm. There was an inconvenience that caused a decrease in the performance.
Further, as described above, when the swing cam is arranged so that the center of the base circle portion is positioned on a straight line passing through the center of the roller provided on the rocker arm and parallel to the axis of the valve, the camshaft is positioned at the cylinder. There is a problem that the shilling head is enlarged due to the distance from the center line. In particular, when the valve timing changing mechanism for changing the valve timing is arranged coaxially with the camshaft, there is a disadvantage that the shilling head is further enlarged. It was.

  Accordingly, an object of the present invention is to reduce the size of a variable valve operating apparatus for an internal combustion engine that changes the valve lift amount by changing the relative position between a rocking cam and a roller provided on the rocker arm, and the durability of the rocker arm. An object of the present invention is to provide a variable valve operating apparatus for an internal combustion engine that improves the engine.

  In the present invention, the intake valve and the exhaust valve are arranged on both sides of the cylinder center line with the axis line inclined so that the distance between the intake valve and the exhaust valve increases upward, and the valve is swung by the driving force transmitted to each roller. Each rocker arm for opening and closing is disposed above each valve, an intake camshaft and an exhaust camshaft are respectively disposed above each rocker arm, and the intake camshaft is arranged in a direction perpendicular to the cylinder center line. A rocking cam, which is disposed at a position farther from the exhaust camshaft than the roller of the rocker arm on the side, and includes a base circular portion and a lift cam portion protruding radially outward from the base circular portion, is located above the roller of the rocker arm. A cam follower that is swingably arranged and swings by rotation of the intake camshaft is connected to the swing cam so as to be relatively rotatable. The lift cam portion of the swing cam pushes down the rocker arm roller to lift the intake valve, while changing the relative position of the swing cam with respect to the rocker arm roller to change the lift amount of the intake valve. In the variable valve system for an internal combustion engine to be changed, when the variable valve system is viewed from the axial direction of the intake camshaft, the rocking fulcrum of the rocker arm on the intake valve side is a cylinder center line with respect to the intake valve The swing cam is disposed so that the lift cam portion extends from the base circle portion to the intake camshaft side, and the base circle portion of the swing cam is the roller arm roller on the intake valve side. In contact with the roller of the rocker arm on the intake valve side of a straight line extending in parallel with the axis of the intake valve. Characterized in that was.

  The variable valve operating apparatus for an internal combustion engine according to the present invention can reduce the size by moving the swing cam and the intake camshaft closer to the cylinder center line side, and can improve the durability of the rocker arm.

FIG. 1 is a sectional view of a valve gear for an internal combustion engine. (Example) FIG. 2 is a cross-sectional view of a variable valve operating device arranged on the intake side of the internal combustion engine. (Example) FIG. 3 is a front view showing the position of the swing cam of the variable valve operating apparatus. (Example) FIG. 4 is an exploded view of the variable valve operating apparatus. (Example) FIG. 5 is a front view showing the operation of the intake valve before a large lift / lift (when not lifted). (Example) FIG. 6 is a front view showing the operation of the intake valve during a large lift / lift. (Example) FIG. 7 is a front view showing the operation of the intake valve before small lift / lift (when not lifted). (Example) FIG. 8 is a front view showing the operation of the intake valve during small lift / lift. (Example) FIG. 9 is a front view showing another shape of the intake rocker arm. (Modification) FIG. 10 is a front view showing a variable valve operating apparatus in which the swing cam is arranged on a straight line passing through the center of the roller of the intake rocker arm and parallel to the axis of the intake valve. (Reference example)

  An object of the present invention is to reduce the size and improve the durability of a rocker arm in a variable valve operating apparatus for an internal combustion engine that changes a valve lift amount by changing a relative position between a swing cam and a roller provided on a rocker arm. Is realized by bringing the swing cam and the intake camshaft closer to the cylinder center line side.

1 to 8 show an embodiment of the present invention.
1 and 2, 1 is an internal combustion engine mounted on a vehicle, 2 is a cylinder block, 3 is a cylinder head, and 4 is a combustion chamber. Hereinafter, the crank axis direction of the internal combustion engine 1 is defined as the front-rear direction, the cylinder center line C1 direction is defined as the up-down direction, and the direction orthogonal to the crank axis line and the cylinder center line C1 is defined as the left-right direction.
The cylinder head 3 is formed with an intake side upper wall 7 having an intake port 5 and an intake valve through-hole 6 in the vertical direction above the intake port 5 on the intake side, and at the exhaust side, An exhaust-side upper wall portion 10 having an exhaust valve through-hole 9 in the vertical direction is formed at the port 8 and above the exhaust port 8.
The cylinder head 3 is provided with an intake valve 11 inserted in the intake valve through-hole 6 at the intake-side upper wall portion 7 so as to be able to reciprocate, and at the exhaust-side upper wall portion 10 with an exhaust valve through-hole. An exhaust valve 12 inserted through 9 is provided so as to be able to reciprocate.
The axis C2 of the intake valve 11 and the axis C3 of the exhaust valve 12 are disposed on both sides of the cylinder center line C1 so as to incline so that the distance from each other increases upward.
An intake side retainer 13 is fixed to the intake valve 11 at an upper end portion, and an intake side valve spring 14 is fitted between the intake side retainer 13 and the upper surface of the intake side upper wall portion 7. An exhaust side retainer 15 is fixed to the exhaust valve 12 at an upper end portion, and an exhaust side valve spring 16 is fitted between the exhaust side retainer 15 and the upper surface of the exhaust side upper wall portion 10.

Further, a valve operating device 17 for operating the intake valve 11 and the exhaust valve 12 is provided on the upper portion of the cylinder head 3. The valve operating device 17 includes a variable valve operating device 18 capable of changing a valve lift amount and a rocker type valve operating device 19 having a fixed valve lift amount, and the variable valve operating device 18 is disposed on the intake side. A rocker type valve gear 19 is disposed on the exhaust side.
The variable valve operating device 18 includes an intake cam shaft 23 provided with an intake cam 22 including an intake base circle portion 20 and an intake lift cam portion 21, and the intake valve 11 is operated by the rotation of the intake cam shaft 23. The rocker type valve gear 19 includes an exhaust cam shaft 27 provided with an exhaust cam 26 including an exhaust base circular portion 24 and an exhaust lift cam portion 25, and the exhaust valve 12 is operated by the rotation of the exhaust cam shaft 27.
The intake camshaft 23 and the exhaust camshaft 27 are respectively provided with an intake valve timing mechanism 43 and an exhaust valve timing mechanism 61 that change the rotational phase of the intake camshaft 23 and the exhaust camshaft 27 with respect to the crankshaft at axial ends. Prepare.

As shown in FIGS. 2 and 4, the variable valve operating device 18 includes an intake rocker arm 28 between the intake camshaft 23 and the intake valve 11. The intake rocker arm 28 includes an intake arm portion 29 arranged horizontally and horizontally, and an intake rocker roller 31 rotatably provided on an intake roller pin 30 supported at a central portion of the intake arm portion 29. And an intake valve contact portion 32 formed at the right end portion (tip portion) of the intake arm portion 29 and an intake arm support portion 33 formed at the left end portion (base end portion) of the intake arm portion 29. The intake arm support portion 33 is connected to an intake protrusion upper end portion 36 of an intake hydraulic adjuster 35 attached to the intake side installation portion 34 of the intake side upper wall portion 7. The intake protrusion upper end portion 36 serves as a swing fulcrum G1 of the intake rocker arm 28.
The intake rocker arm 28 swings by the driving force transmitted to the intake rocker roller 31 to open and close the intake valve 11 and is disposed above the intake valve 11. An intake camshaft 23 is disposed above the intake rocker arm 28. As shown in FIG. 1, the intake camshaft 23 is disposed at a position farther from the exhaust camshaft 27 than the intake rocker roller 31 of the intake rocker arm 28 in the direction orthogonal to the cylinder center line C1.

  Further, the variable valve device 18 is provided with a swing cam 37 above the intake rocker roller 31 of the intake rocker arm 28. The swing cam 37 is formed in a cylindrical shape, and has a base circle portion 38, a lift cam portion 39 projecting radially outward from the base circle portion 38, and a ring shape formed on the inner peripheral surface of the base circle portion 38. The inner teeth 40 are provided so as to be swingable by the control shaft 41 above the intake rocker roller 31. The control shaft 41 is arranged in parallel with the intake camshaft 23 and is controlled to rotate by the control means 42.

Further, as shown in FIG. 4, the variable valve operating device 18 swings the swing cam 37 in synchronization with the rotation of the intake cam 22 and includes a cam follower 44 connected to the swing cam 37 so as to be relatively rotatable. Prepare.
The cam follower 44 includes a tubular body 46 having a cylindrical insertion hole 45, a pair of roller support portions 47 and 47 projecting radially outward on the intake camshaft 23 side at an axial central portion of the tubular body 46, A roller pin 48 supported by the roller support portions 47 and 47 and a cam follower roller 49 rotatably supported by the roller pin 48 between the pair of roller support portions 47 and 47 are provided. External teeth 50 and 50 meshing with the outer peripheral surface of the tubular body 46 at both ends in the axial direction, that is, in an eccentric state with the inner teeth 40 of the swing cam 37 at both ends of the pair of roller support portions 47 and 47. Is provided.

The tubular body 46 is supported by the control shaft 41 via the cylindrical member 51. The cylindrical member 51 has a cylindrical portion 52 whose axis is coaxial with the control shaft 41 and supports the swing cam 37, and whose shaft center is eccentric from the axis of the control shaft 41 and has a bowl-shaped thrust receiving portion 53. The eccentric cam part 54 connected with the axial direction edge part of the cylindrical part 52 is provided.
As shown in FIG. 2, the eccentric cam portion 54 has an axial center 54 </ b> C that is eccentric from the axial center 51 </ b> C of the inner peripheral portion of the cylindrical member 51 by an eccentric amount f, and the cylindrical insertion hole 45 of the tubular body 46. Is slidably inserted. Therefore, the cam follower 44 swings about the shaft center 54 </ b> C eccentric by the amount of eccentricity f with respect to the center of the control shaft 41, and transmits the driving force from the external teeth 50 to the internal teeth 40 of the swing cam 37.

The cylindrical member 51 is provided with a position adjusting mechanism 55 that adjusts the mounting position of the eccentric cam portion 54 with respect to the control shaft 41. The position adjusting mechanism 55 includes a long hole 56 formed in the circumferential direction of the cylindrical portion 52, a fastening bolt 58 that passes through the long hole 56 and is fastened to the screw holes 57 and 57 of the control shaft 41, and the fastening bolt. The spacer 59 is disposed between the head portion 58 and the cylindrical portion 52 and is curved along the outer peripheral surface of the cylindrical portion 52. The spacer 59 and the thrust receiving portion 53 position the swing cam 37 in the axial direction.
Further, a jig adjusting hole 60 for inserting a jig is formed in the cylindrical portion 52 on the same circumference as the long hole 56.
Thereby, in the intake valve timing mechanism 43, the intake rocker roller 31 is pushed down by the lift cam portion 39 of the swing cam 37 to lift the intake valve 11, while the relative position of the swing cam 37 to the intake rocker roller 31 is changed. Then, the valve lift amount of the intake valve 11 is changed.

In the variable valve operating device 18, before the intake valve 11 is lifted or lifted (when not in operation), the shaft center 54 </ b> C of the eccentric cam portion 54 is moved with respect to the shaft center of the control shaft 41 as shown in FIG. 5. When positioned on the right side, the swing cam 37 comes into contact with the intake rocker roller 31 of the intake rocker arm 28 at a portion of the base circle portion 38 close to the lift cam portion 39.
Then, as shown in FIG. 6, when the intake camshaft 23 rotates, the intake cam 22 pushes the cam follower roller 49 of the cam follower 44 and swings the swing cam 37 together with the cam follower 44. As the swing cam 37 swings, the swing cam 37 presses the intake rocker roller 31 of the intake rocker arm 28 at the radially outer portion of the lift cam portion 39, and the intake valve 11 is operated greatly to be in a large lift state. It becomes.

On the other hand, when the control shaft 41 is rotated clockwise as shown in FIG. 7 in the variable valve apparatus 18 before the intake valve 11 is slightly lifted or lifted (during non-operation), the external teeth 50 of the cam follower 44 are rotated. 50 revolves clockwise around the control shaft 41, and the meshing position of the outer teeth 50, 50 of the cam follower 44 and the inner teeth 40 of the swing cam 37 rotates clockwise along the inner periphery of the inner teeth 40. As a result of the movement of the engagement between the two, the swing cam 37 rotates clockwise, and the portion of the base circle portion 38 that is away from the lift cam portion 39 comes into contact with the intake rocker roller 31 of the intake rocker arm 28.
As shown in FIG. 8, when the intake camshaft 23 rotates, the swing cam 37 swings in conjunction with the cam follower 44 as in FIG. 6, but the base circle 38 contacts the intake roller rocker 31. The range to be operated becomes relatively long, and the radially inner portion of the lift cam portion 39 of the swing cam 37 slightly presses the intake rocker roller 31 of the intake rocker arm 28, so that the intake valve 11 is operated to enter a small lift state. .

  The rocker type valve gear 19 includes an exhaust rocker arm 62 as shown in FIG. The exhaust rocker arm 62 is rotatably provided on an exhaust arm portion 63 disposed in a horizontal direction and in a horizontal direction, and an exhaust roller pin 64 supported on a central portion of the exhaust arm portion 63. An exhaust rocker roller 65 that contacts the exhaust cam 26, an exhaust valve contact portion 66 that is formed at the right end portion (tip portion) of the exhaust arm portion 63 and contacts the upper end portion of the exhaust valve 12, and a left end portion of the exhaust arm portion 63 ( And an exhaust-side arm support portion 67 formed at the base end portion. An exhaust-side protruding upper end portion 70 of an exhaust hydraulic adjuster 69 attached to the exhaust-side installation portion 68 of the exhaust-side upper wall portion 10 is connected to the exhaust-side arm support portion 67. The exhaust-side protruding upper end 70 serves as a swing fulcrum G2 of the exhaust rocker arm 62. The exhaust rocker arm 62 swings by the driving force transmitted to the exhaust rocker roller 65 to open and close the exhaust valve 12 and is disposed above the exhaust valve 12.

In this embodiment, as shown in FIGS. 1 to 3, when the variable valve device 18 is viewed from the axial direction of the intake camshaft 23, the swing fulcrum G1 of the intake rocker arm 28 that lifts the intake valve 11 is used as the intake valve. 11, the swing cam 37 is disposed so that the lift cam portion 39 extends from the base circle portion 38 toward the intake camshaft 23, and the base circle portion 38 is disposed on the intake valve 11 side. The intake rocker roller 31 is in contact with the intake rocker roller 31 on the intake valve 11 side of a straight line C4 that passes through the center 31C of the intake rocker roller 31 of the intake rocker arm 28 and extends parallel to the axis C2 of the intake valve 11.
Thus, when the variable valve device 18 is viewed from the axial direction of the intake camshaft 23, the swing fulcrum G1 of the intake rocker arm 28 that lifts the intake valve 11 is opposite to the cylinder center line C1 with respect to the intake valve 11. 1 can reduce the sandwiching angle α between the intake valve 11 and the exhaust valve 12, as shown in FIG.
The swing cam 37 is arranged so that the lift cam portion 39 extends from the base circle portion 38 toward the intake camshaft 23 side, and the base circle portion 38 passes through the center 31C of the intake rocker roller 31 of the intake rocker arm 28 on the intake valve 11 side. Since the intake rocker roller 31 is brought into contact with the intake rocker roller 31 on the intake valve 11 side with respect to the straight line C4 extending in parallel with the axis C2 of the intake valve 11, the swing cam 37 and the intake camshaft 23 are arranged close to the cylinder center line C1 side. The variable valve device 18 can be downsized.
Compared with the case where the base circle 38 is brought into contact with the intake rocker roller 31 in the vicinity of a straight line C4 extending through the center 31C of the intake rocker roller 31 of the intake rocker arm 28 on the intake valve 11 side and extending in parallel with the axis C2 of the intake valve 11. When the intake valve 11 is lifted to the maximum, the direction of the force acting on the intake rocker roller 31 from the lift cam portion 39 can be made closer to the swinging direction of the intake rocker arm 28.
For this reason, of the force acting on the intake rocker roller 31 from the lift cam portion 39, the component force in the direction orthogonal to the swinging direction of the intake rocker arm 28 is reduced, the drive loss of the intake rocker arm 28 is reduced, and the durability of the intake rocker arm 28 is increased. Can be improved.
As a result, as shown in FIG. 1, the distance L between the cylinder center line C1 and the center 23C of the intake camshaft 23 is shortened to reduce the size of the variable valve operating device 18, and the durability of the intake rocker arm 28 is improved. Can be improved.

That is, as shown in FIG. 10, when the center 37C of the swing cam 37 is disposed on a straight line C5 passing through the center 31C of the intake rocker roller 31 and parallel to the axis C2 of the intake valve 11, the intake valve 11 is lifted to the maximum. When the swing cam 37 swings to the position, the angle θ formed with the horizontal direction at the point where the lower surface of the lift cam portion 39 of the swing cam 37 contacts the intake rocker roller 31 becomes considerably large. For this reason, an excessive lateral load F1 acts on the intake hydraulic type adjuster 35, which is not preferable.
Therefore, in this embodiment, as shown in FIG. 1, the swing cam 37 is moved from the straight line C4 to the exhaust side by a distance e, and the base circular portion 38 of the swing cam 37 is moved around the center 31C of the intake rocker roller 31. Since the intake rocker roller 31 is brought into contact with the intake valve 11 on the intake valve 11 side of the straight line C4 parallel to the axis C2 of the intake valve 11, the lateral load F2 of the swing cam 37 is relieved, which is advantageous for the operation of the intake hydraulic adjuster 35. It becomes.
Therefore, as shown in FIG. 3, the angle θ formed with the horizontal line at the point where the lower surface of the lift cam portion 39 of the swing cam 37 contacts the intake rocker roller 31 is smaller than the angle shown in the example of FIG. 10. The swing center 37C of the swing cam 37 is eccentric with respect to the straight line C4 by a distance e close to the radius of the intake rocker roller 31.
By the way, in the variable valve operating apparatus 18 of the present invention, the intake camshaft 23 is arranged at a position farther from the exhaust camshaft 27 than the intake rocker roller 31 of the intake rocker arm 28 on the intake valve 11 side in the direction orthogonal to the cylinder axis. However, when the intake camshaft is moved to the exhaust side with respect to the position of the intake camshaft of the base internal combustion engine, the distance between the intake camshaft and the exhaust camshaft becomes too narrow than that of the base internal combustion engine. Because. If the distance between the intake camshaft and the exhaust camshaft is too narrow, it is difficult to mount components such as a hydraulic actuator that changes the valve timing on both ends of the intake camshaft and the exhaust camshaft.
Therefore, in this embodiment, as shown in FIG. 1, the intake camshaft 23 is disposed on the intake side (opposite the exhaust side) with respect to the internal combustion engine 1, so that the intake camshaft 23 and the exhaust camshaft 27 are An intake valve timing changing mechanism 43 that can secure a sufficient interval and changes the valve timing of the intake valve 11 is arranged coaxially with the intake camshaft 23, and an exhaust valve timing changing mechanism 61 that changes the valve timing of the exhaust valve 12. Can be arranged coaxially with the exhaust camshaft 27.

As shown in FIG. 1, an intake valve timing changing mechanism 43 that changes the valve timing of the intake valve 11 with respect to the intake camshaft 23 is arranged coaxially, and the valve timing of the exhaust valve 12 with respect to the exhaust camshaft 27. An exhaust valve timing changing mechanism 61 for changing the position is arranged coaxially.
As a result, in the variable valve operating device 18, the swing cam 37 and the intake camshaft 23 are placed in the cylinder as much as possible while the swing cam 37 for lifting the intake valve 11 is disposed between the intake camshaft 23 and the exhaust camshaft 27. It can be close to the center line C1. As a result, it is possible to reduce the size of the variable valve gear 18 that can change the valve lift amount and the valve timing.

FIG. 9 shows a modification according to the present invention.
In this modified example, as shown in FIG. 9, the intake rocker arm 28 is brought into contact with the intake protruding upper end 36 of the intake hydraulic adjuster 35 and the upper end of the intake valve 11 whose longitudinal ends are the swing fulcrums G1. The intake arm portion 29 is provided with an intake rocker roller 31 at the longitudinal center of the intake arm portion 29. When the intake arm portion 29 is viewed from the center direction of the intake rocker roller 31, the intake arm portion 29 includes the intake rocker roller 31. A curved portion 73 that is curved so that the upper wall 71 approaches the lower wall 72 from the center 31C to the intake valve 11 side is formed, and the base circular portion 38 of the swing cam 37 is disposed above the curved portion 73. In this case, in the intake arm portion 29 of the intake rocker arm 28, a space S is formed above the upper wall 71, the height H1 of the right portion is set lower than the height H2 of the left portion, and the rigidity of the left portion is set. Is set larger than the rigidity of the right side portion.
Therefore, as shown in FIG. 9, the force by which the swing cam 37 pushes the intake rocker roller 31 acts on the swing fulcrum G1 side of the intake rocker arm 26 with respect to the center 31C of the intake rocker roller 31. The arm portion 29 can be relatively lower in rigidity on the intake valve 11 side than the center 31C of the intake rocker roller 31 with respect to the rigidity on the swing fulcrum G1 side than the center 31C of the intake rocker roller 31. A curved portion 73 is formed by bending the upper wall 71 so as to approach the lower wall 72 from the center 31C of the intake rocker roller 31 in the portion 29, and above the base circular portion 38 of the swing cam 37. The variable valve device 18 can be further reduced in size by arranging.
That is, the load P1 acting on the intake rocker roller 31 from the swing cam 37 is the left intake hydraulic adjuster 35 side when viewed from the center 31C of the intake rocker roller 31. In FIG. 9, P2 is a load from the intake hydraulic adjuster 35, and P3 is a load from the intake valve 11.
Therefore, the strength and rigidity of the intake rocker arm 28 may be smaller on the right intake valve 11 side than the left side of the center 31C of the intake rocker roller 31, and the height of the intake rocker arm 28 is accordingly reduced. It is possible to arrange the base circular portion 38 of the swing cam 37 in the vacant space S, and the valve operating system can be made compact.

  The variable valve operating apparatus according to the present invention can be applied to internal combustion engines of various vehicles.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3 Cylinder head 11 Intake valve 17 Valve mechanism of internal combustion engine 18 Variable valve mechanism of intake side 19 Roller type valve mechanism of exhaust side 22 Intake cam 23 Intake cam shaft 26 Exhaust cam 27 Exhaust cam shaft 28 Intake rocker arm DESCRIPTION OF SYMBOLS 29 Intake arm part 31 Intake rocker roller 35 Intake hydraulic type adjuster 37 Oscillating cam 38 Base circle part 39 Lift cam part 40 Internal tooth 41 Control shaft 43 Intake valve timing change mechanism 44 Cam follower 46 Tubular member 51 Cylindrical member 54 Eccentric cam part 61 Exhaust valve Timing change mechanism 71 Upper wall 72 Lower wall 73 Bending portion

Claims (3)

  The intake valve and the exhaust valve are arranged on both sides of the cylinder center line so that the distance between the intake valve and the exhaust valve increases toward the upper side, and the valves are opened and closed by swinging by the driving force transmitted to each roller. A rocker arm is disposed above each valve, an intake camshaft and an exhaust camshaft are respectively disposed above each rocker arm, and the intake camshaft is disposed in a direction perpendicular to the cylinder center line of the rocker arm on the intake valve side. A swing cam, which is disposed at a position farther from the exhaust cam shaft than the roller and includes a base circular portion and a lift cam portion projecting radially outward from the base circular portion, is swingable above the roller of the rocker arm. And a cam follower that is rocked by the rotation of the intake camshaft is connected to the rocking cam so as to be relatively rotatable. A lift cam portion of a cam pushes down a roller of the rocker arm to lift the intake valve, while changing a relative position of the swing cam with respect to the roller of the rocker arm to change the lift amount of the intake valve. In the variable valve operating apparatus, when the variable valve operating apparatus is viewed from the axial direction of the intake camshaft, the rocking arm of the rocker arm on the intake valve side is disposed on the opposite side of the cylinder center line with respect to the intake valve. The swing cam is disposed so that the lift cam portion extends from the base circle portion to the intake camshaft side, and the base circle portion of the swing cam passes through the center of the roller of the rocker arm on the intake valve side. The rocker arm roller is brought into contact with the intake valve side of a straight line extending in parallel with the valve axis. The variable valve device for an internal combustion engine that.   The rocker arm includes an arm portion that is in contact with an upper end portion of the swing fulcrum and an upper end portion of the intake valve at both longitudinal ends, and the roller is provided at the longitudinal center portion of the arm portion. When the portion is viewed from the center direction of the roller, a curved portion is formed in the arm portion so as to bend from the center of the roller toward the intake valve so that the upper wall approaches the lower wall. 2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein a base circle portion of the swing cam is disposed in the internal combustion engine.   An intake valve timing changing mechanism for changing the valve timing of the intake valve is coaxially disposed with respect to the intake camshaft, and an exhaust valve timing changing mechanism for changing the valve timing of the exhaust valve is coaxially provided with respect to the exhaust camshaft. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein

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