JP4407598B2 - Variable valve mechanism for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve mechanism for making it possible to change the operating characteristics of an intake valve and an exhaust valve of an internal combustion engine.

  The variable valve mechanism is provided with a rocker shaft fixed to the internal combustion engine, a control shaft disposed in the shaft so as to be movable in the axial direction, and a lift amount of the engine valve provided on the rocker shaft. And a plurality of valve lift mechanisms to be changed (see, for example, Patent Document 1).

  The rocker shaft is provided in parallel with the camshaft of the intake valve or the exhaust valve. On the rocker shaft, a valve lift mechanism is provided at a position corresponding to each cylinder.

  This valve lift mechanism is provided on a slider gear that is movable in conjunction with an axial displacement of the control shaft, an input arm that is provided on the slider gear and is driven by a cam of the camshaft, and a slider gear. And an output arm for changing the valve lift amount.

  The slider gear is formed with an input side helical spline that meshes with the input arm and an output side helical spline that meshes with the output arm. The inclination direction of the teeth of the input side helical spline and the inclination direction of the teeth of the output side helical spline are formed in opposite directions.

  On the other hand, a helical spline that meshes with the input-side helical spline of the slider gear is formed on the inner peripheral surface of the input arm, and similarly, a helical spline that meshes with the output-side helical spline of the slider gear. Splines are formed.

As a result, when the slider gear is displaced in the axial direction together with the control shaft, the relative positions of the slider gear, the input arm and the output arm in the axial direction change, and the torsional forces in the opposite directions with respect to the input arm and the output arm are changed. Is to be granted. As a result, the input arm and the output arm are rotated relative to each other, the relative phase difference between the two is changed, and the valve lift amount of each cylinder can be changed.
JP 2001-263015 A

  In the conventional variable valve mechanism, the valve lift mechanism is disposed so that the input arm and the output arm are in contact with each other at the adjacent end surfaces. In this case, foreign matter in oil easily enters between the end surfaces of both arms and the meshing portion between the helical splines of both arms and each helical spline of the slider gear. A configuration was considered in which one end face is fitted to the other end face.

However, since the input arm and the output arm rotate relative to each other due to the displacement of the slider gear in the axial direction, if the fitting clearance between the end faces of the input arm and the output arm is set small, the slider gear with respect to the rocker shaft There is a concern that even if the arms are slightly displaced in the radial direction, the fitting gap is clogged, and friction is generated in the relative rotation between the input arm and the output arm, resulting in poor movement. It was.

  Therefore, the present invention has been made in view of the above-described circumstances, and enables efficient relative rotation of the input arm and the output arm, and the output arm and the rocker shaft, while efficiently improving the operation characteristics of the valve. The present invention provides a variable valve mechanism for an internal combustion engine that can be changed.

In order to solve the above-described problems, according to the present invention, in a variable valve mechanism that can change the operation characteristics of an intake valve or an exhaust valve of an internal combustion engine, a valve lift mechanism is provided between the intake valve or the exhaust valve and the camshaft. The valve lift mechanism is disposed on a rocker shaft in which the control shaft is inserted so as to be displaceable in the axial direction and can be interlocked with the displacement of the control shaft. An input arm that receives a driving force from the shaft; and an output arm that is mounted on the slider gear so as to be adjacent to the input arm in the axial direction and lifts the valve. Are provided with an input side helical spline and an output side helical spline, and the input arm A helical spline that meshes with the input side helical spline of the slider gear is provided on the inner circumferential surface, and a helical spline that meshes with the output side helical spline of the slider gear is provided on the inner circumferential surface. By engaging with each other, the input arm and the output arm are supported with respect to the slider gear, and the output arm is rotated by a predetermined angle with respect to the input arm due to the axial displacement of the control shaft, so that the operating characteristics of the valve are improved. These input and output arms are adjacent to each other in the axial direction, and end portions adjacent to each other in the radial direction are provided with cylindrical portions that are fitted so as to face each other in a non-contact manner. The radial facing distance between the cylinder parts of the arm and output arm It is characterized in that it is set larger than the allowable displacement amount in the radial direction of the entire valve lift mechanism relative to the shaft.

In this configuration, short, and an axial inner end portion of the output arm of the both sides of the axial end portion of the input arm, and a so-called faucet fitting, axially between opposing the input arm and the output arm in a radial direction and out It is in a form that closes. Thereby, it is possible to make it difficult for foreign matter in the oil existing on the outside of both arms to enter the inside of both arms. In addition, the fitting portion between the input arm and the output arm is a loose fit in a form that does not interfere with each other so as to face each other in a non-contact manner in the radial direction. Thereby, the movement at the time of relative rotation of both arms is made smooth. Further, in the above configuration, the input arm and the output arm that are externally mounted on the slider gear bear the load of both arms at the meshing portion of the input side helical spline or the output side helical spline of the slider gear. It becomes possible to suppress or prevent radial interference at the cylindrical portion of the arm, and smooth relative rotation is possible.

  In the variable valve mechanism having the above-described configuration, the inner peripheral surface of the output arm on the side opposite to the input arm faces non-contact with the outer peripheral surface of the rocker shaft, and this non-contact facing interval Is characterized in that it is set larger than the radial displacement of the entire valve lift mechanism relative to the rocker shaft.

  In this configuration, the rotating output arm and the inner rocker shaft are opposed to each other in a non-contact manner and do not interfere with each other in the radial direction. Reduced to enable smooth rotation.

Here, when the fitting clearance dimension between the rocker shaft and the slider gear is Δh ₁ , and the radial displacement allowable dimension of the output arm with respect to the slider gear is Δh ₂ , the diameter between the cylindrical portion of the input arm and the cylindrical portion of the output arm The facing distance Δh _{3 in the} direction is
Δh ₃ > Δh ₁ + Δh ₂
It is preferable to satisfy.

Further, when the fitting clearance dimension between the rocker shaft and the slider gear is Δh ₁ and the radial displacement allowable dimension of the output arm relative to the slider gear is Δh ₂ , the distance between the inner peripheral surface of the end of the output arm and the outer peripheral surface of the rocker shaft The non-contact facing distance Δh ₄ is the following formula:
Δh ₄ > Δh ₁ + Δh ₂
It is preferable to be configured to satisfy.

  According to such a configuration, the radial opposing distance between the cylindrical portions of the input arm and the output arm, and the non-contact opposing distance between the output arm and the rocker shaft are determined by the radial displacement of the entire valve lift mechanism with respect to the rocker shaft. The valve lift mechanism can be operated efficiently without causing friction between them.

  According to the present invention, it is possible to suppress or prevent foreign matter in the external oil from entering the input arm and the output arm, and to smoothly rotate the input arm and the output arm relative to each other. Is possible.

  The best mode for carrying out a variable valve mechanism for an internal combustion engine according to the present invention will be described below with reference to the drawings. In the following description, an example in which the variable valve mechanism of the present invention is applied to an in-line four-cylinder DOHC engine is given.

  1 to 8 show a variable valve mechanism for an internal combustion engine according to the present invention, FIG. 1 is a plan view schematically showing the variable valve mechanism, and FIG. 2 is a sectional view taken along line D1-D1 in FIG. FIG. 3 is a perspective view of the variable valve mechanism of FIG. 4 is an exploded perspective view of the valve lift mechanism of FIG. 3, FIG. 5 is an exploded perspective view showing the relationship between the slider gear and the rocker shaft of the valve lift mechanism of FIG. 3, and FIG. 6 is the valve lift mechanism 4 of FIG. It is a perspective view which fractures | ruptures and shows the upper half. FIG. 7 is an operation explanatory diagram when the relative phase difference between the input arm and the output arm in FIG. 1 is maximized, and FIG. 8 is an operation explanatory diagram when the relative phase difference is minimized. 7 and 8, (a) shows the valve closed state, and (b) shows the valve opened state.

  The internal combustion engine 1 includes a cylinder block 11 and a cylinder head 12 mounted on the cylinder block 11.

  A plurality of cylinders 13 are provided in the cylinder block 11. In the illustrated embodiment, four cylinders 13 are provided, and each cylinder 13 is provided with an intake valve 14 that opens and closes an intake port and an exhaust valve 15 that opens and closes an exhaust port.

  In each cylinder 13, an intake camshaft 16 having an intake cam 17 is provided in the vicinity of the intake valve 14, and an exhaust camshaft 18 having an exhaust cam 19 is provided in the vicinity of the exhaust valve 15.

  The intake camshaft 16 and the exhaust camshaft 18 are rotationally driven by a crankshaft via a timing chain 23 that is an output shaft of the internal combustion engine 1, and the intake valve 14 and the exhaust valve 15 are lifted through this rotation.

  Of these valves 14 and 15, the intake valve 16 is lifted by the rotation of the intake camshaft 16 rotatably supported by the plurality of partition walls 21, and the variable valve mechanism 3 continuously increases the valve lift amount and the operating angle. It can be changed automatically.

  The variable valve mechanism 3 is disposed between the intake cam 17 of the intake camshaft 16 and the roller rocker arm 24. One end of the roller rocker arm 24 is supported by the lash adjuster 25 and the other end is in contact with the tappet 14 a at the upper end of the intake valve 14.

  The variable valve mechanism 3 includes a rocker shaft 31, a control shaft 32, an actuator 33, and a valve lift mechanism 4.

  The rocker shaft 31 is attached to a large number of partition walls 21 provided at regular intervals on the cylinder head 12 so as to be immovable in the axial direction and the circumferential direction, and is parallel to the intake camshaft 16, that is, in the cylinder arrangement direction ( It is arrange | positioned along the arrow F, R direction in FIG. In FIG. 3, an arrow F indicates a direction away from the actuator 33, and an arrow R indicates a direction approaching the actuator 33.

  A control shaft 32 is inserted into the rocker shaft 31 so as to be slidable in the axial direction. The control shaft 32 is driven to advance and retract in the axial direction by an actuator 33.

  A valve lift mechanism 4 is provided on the rocker shaft 31 at a position corresponding to each cylinder 13. Each valve lift mechanism 4 includes an input arm 41, an output arm 42, and a slider gear 43.

  The input arm 41 has a cylindrical housing 41a, and a helical spline 41b that meshes with the input-side helical spline 43a of the slider gear 43 is formed on the inner peripheral surface thereof. Further, a pair of forks 41cL and 41cR projecting radially outward is provided on the outer periphery of the housing 41a, and a support shaft 41d parallel to the rocker shaft 31 is interposed between the pair of forks 41cL and 41cR. The roller 41e is rotatably supported.

  The output arm 42 includes cylindrical housings 42a provided on both sides in the axial direction of the input arm 41, and a helical spline 42b that meshes with the output-side helical spline 43b of the slider gear 43 is formed on the inner peripheral surface thereof. ing. Further, a nose 42c is provided on the outer periphery of the housing 42a so as to protrude outward in the radial direction. The nose 42c is formed in a substantially triangular shape in a side view, and has a cam surface 42d whose one side is curved in a concave shape. In addition, the housing 42a of each output arm 42 has a rocker shaft 31 inserted through an end that is opposite to the adjacent input arm 41 in the axial direction, and faces the outer peripheral surface of the rocker shaft 31 in a non-contact manner. Inner flange portions 422 extending inward are formed.

  A slider gear 43 is disposed in an internal space defined by the input arm 41 and the two output arms 42. The slider gear 43 is externally mounted on the rocker shaft 31 so as to be movable in the axial direction in conjunction with the control shaft 32.

The slider gear 43 is formed in a cylindrical shape having a through hole 43c in the center, and an input-side helical spline 43a that meshes with the helical spline 41b of the input arm 41 is provided in the middle in the axial direction on the outer periphery thereof. On both sides in the direction, output-side helical splines 43b that mesh with the helical splines 42b of the output arm 42 are formed. The output side helical spline 43b has a smaller outer diameter than the input side helical spline 43a. The input-side helical spline 43a and the output-side helical spline 43b are formed so that the inclination directions of the teeth are opposite.

  The roller 41e of the input arm 41 is urged so as to be always pressed against the intake cam 17a by a lost motion spring 26 disposed in a compressed state on the cylinder head 2. The roller 24a of the roller rocker arm 24 is pressed against either the base circular portion of the housing 42a of the output arm 42 or the cam surface 42d of the nose 42c by the valve spring 14b of the intake valve 14. With this relationship, the input arm 41 is swung by the rotation of the intake cam 17a, and the intake valve 14 is lifted via the roller rocker arm 24 by the output arm 42 that swings integrally with the input arm 41. It is like that.

  Here, the slider gear 43 will be described in connection with the rocker shaft 31 and the control shaft 32.

  In the slider gear 43, between the input side helical spline 43a and the one output side helical spline 43b, a long hole 43d that penetrates inward and outward in the radial direction and extends in the circumferential direction is provided. In the rocker shaft 31, a long hole 31 a that penetrates inward and outward in the radial direction and extends in the axial direction is formed at a position corresponding to the long hole 43 d of the slider gear 43. An insertion hole 32 a is formed at a position of the control shaft 32 corresponding to the long hole 31 a of the rocker shaft 31.

  Then, the rocker shaft 31 is inserted into the through hole 43c of the slider gear 43, and a locking pin 44 is inserted at a location where the long hole 43d of the slider gear 43 and the long hole 31a of the rocker shaft 31 intersect. One end of the pin 44 is fixed to the insertion hole 32 a of the control shaft 32 inserted into the control shaft 32.

The slider gear 43 assembled in this way operates as follows.
(A) The locking pin 44 can move along the long hole 31 a of the rocker shaft 31. For this reason, when the control shaft 32 is moved in the axial direction, the slider gear 43 moves in the axial direction in conjunction with the control shaft 32.
(B) Since the locking pin 44 is inserted into the elongated hole 43 d of the slider gear 43, when the torque of the intake camshaft 16 is transmitted to the input arm 41, the slider gear 43 swings around the rocker shaft 31. To do.

  Thus, the slider gear 43 can move in the axial direction on the rocker shaft 31 while the position in the axial direction on the control shaft 32 is fixed. The slider gear 43 can swing around the rocker shaft 31 (control shaft 32) as a fulcrum.

  In such a valve lift mechanism 4, the input side helical spline 43 a of the slider gear 43 and the helical spline 41 b of the input arm 41 are supported by being engaged with each other. Further, the output-side helical spline 43b of the slider gear 43 and the helical spline 42b of the output arm 42 are also engaged with each other and supported.

Therefore, by moving the slider gear 43 together with the control shaft 32 in the axial direction and changing the relative position in the axial direction between the slider gear 43 and the input arm 41 and the output arm 42, the input arm 41 and the output arm 42 are changed. Twisting forces in opposite directions are applied. Thereby, the input arm 41 and the output arm 42 are relatively rotated, and the relative phase difference between the input arm 41 (roller 41e) and the output arm 42 (nose 42c) is changed.

  In the variable valve mechanism 3, the slider gears 43 for each cylinder 13 are fixed to a common control shaft 32, so that all the cylinders 13 are associated with the axial displacement of the control shaft 32. The lift amount of the intake valve 14 is simultaneously changed.

  Next, the operation will be described.

  As shown in FIG. 7A, when the base circle portion of the intake cam 17 is in contact with the roller 41e of the input arm 41, the roller 24a of the roller rocker arm 24 is moved to the base circle portion of the housing 42a of the output arm 42. Is in contact with. Therefore, the intake valve 14 is maintained in a state where the lift amount is “0” (a state where the intake port 14P of the internal combustion engine 1 is closed).

  When the roller 41 e of the input arm 41 is pushed down through the lift portion of the intake cam 17 with the clockwise rotation of the intake cam shaft 16, the input arm 41 is opposite to the rocker shaft 31 as shown in FIG. It rotates in the clockwise direction (arrow A direction). As a result, the output arm 42 and the slider gear 43 rotate together.

  As a result, the cam surface 42d formed on the nose 42c of the output arm 42 contacts the roller 24a of the roller rocker arm 24, and the roller 24a is pushed down by the pressing of the cam surface 42d.

  As shown in FIG. 7B, when the roller 24a of the roller rocker arm 24 is pressed by the cam surface 42d, the roller rocker arm 24 swings around the contact portion with the lash adjuster 25, and the intake valve 14 is opened.

  In a state where the control shaft 32 moves to the maximum in the direction away from the actuator 33 (the direction of arrow F in FIG. 3), the roller 41e of the input arm 41 and the nose 42c of the output arm 42 around the axis of the rocker shaft 31 The relative phase difference of becomes the maximum.

  As a result, when the intake cam 17 pushes down the roller 41e to the maximum, the displacement difference of the roller 24a of the roller rocker arm 24 becomes the largest, and the intake valve 14 is opened and closed with the maximum valve lift and operating angle.

  As shown in FIG. 8A, when the base circular portion of the intake cam 17 is in contact with the roller 41e of the input arm 41, the contact position between the output arm 42 and the roller 24a is maximized from the cam surface 42d. Is far away. When the intake camshaft 16 rotates and the roller 41e of the input arm 41 is pushed down by the lift portion of the intake cam 17, the input arm 41 and the output arm 42 rotate together.

However, in this case, since the contact position between the output arm 42 and the roller 24a is farthest from the cam surface 42d, the output arm until the pressing of the roller 24a of the roller rocker arm 24 by the cam surface 42d is started. The amount of rotation 43 is larger than that in the operating state shown in FIG. Further, when the roller 41e of the input arm 41 is pushed down through the lift portion of the intake cam 17, the range of the cam surface 42d that comes into contact with the roller 24a is reduced to only a part of the base end side of the nose 42c. For this reason, the rocking amount of the roller rocker arm 24 corresponding to the depression of the roller 41e by the lift portion of the intake cam 17 becomes small.

  As shown in FIG. 8B, the intake valve 14 is opened with a smaller valve lift amount due to the small swing amount of the roller rocker arm 24.

  Further, when the control shaft 32 is moved to the maximum in the direction approaching the actuator 33 (the arrow R direction in FIG. 3), the relative phase difference between the roller 41e and the nose 42c around the central axis 30 of the rocker shaft 31 is minimum. It becomes.

  As a result, the displacement amount of the roller 24a when the intake cam 17 pushes the roller 41e to the maximum is minimized, and the intake valve 14 is opened and closed with the minimum valve lift amount and operating angle.

  Next, the fitting of the valve lift mechanism, which is a characteristic component of this embodiment, will be described. 9 is an arrow view showing a cross section taken along line D2-D2 of FIG. 1, and FIG. 10 is an explanatory diagram showing an enlarged part of the valve lift mechanism 4 of FIG.

  As described above, in the valve lift mechanism 4, the input arm 41 and the output arm 42 are disposed between the partition walls 21 and 21 via the inter-cylinder adjustment shim 27. And the edge part which these input arms 41 and the output arms 42 adjoin in an axial direction is comprised so that it can mutually fit.

  In the valve lift mechanism 4 in this embodiment, both end portions in the axial direction of the input arm 41 and inner end portions in the axial direction of the output arms 42 on both sides thereof are so-called inlay fitting, and the fitting portion has a diameter. Loose fit so as not to interfere with direction.

  First, cylindrical portions 411 and 411 extending outward in the axial direction are provided at both axial ends of the cylindrical housing 41a of the input arm 41.

  The outer diameters of both the cylindrical portions 411 are set to be the same as the outer diameter of the cylindrical housing 41a, so that the outer peripheral surface of the cylindrical portion 411 and the outer peripheral surface of the cylindrical housing 41a are flush with each other in the axial direction. ing. Further, the inner diameters of both cylindrical portions 411 are set larger than the inscribed circle diameter connecting the respective tooth tips of the helical spline 41b provided on the inner circumference of the cylindrical housing 41a. A step is formed between the peripheral surface and an inscribed circle connecting the tooth tips of the helical spline 41b.

  Next, an axially inner end portion of the cylindrical housing 42a of the output arm 42, that is, an end portion facing the input arm 41 in the axial direction, has a stepped small diameter cylindrical portion whose outer diameter is smaller than the outer diameter of the cylindrical housing 42a. 421 is provided.

  The small-diameter cylindrical portion 421 of the output arm 42 is fitted in the inner periphery of the cylindrical portion 411 of the input arm 41 in a non-contact manner, and the gap between the axially opposite sides of the input arm 41 and the output arm 42 is closed inside and outside in the radial direction. It seems to have come off. This makes it difficult for foreign matter in the oil existing outside the arms 41 and 42 to enter the inside of the arms 41 and 42.

  However, the radial facing distance between the cylindrical portion 411 of the input arm 41 and the small-diameter cylindrical portion 421 of the output arm 42 does not interfere with each other in the radial direction when the input arm 41 and the output arm 42 are relatively rotated. It is set relatively large.

  Specifically, the cylindrical portion 411 of the input arm 41 and the small-diameter cylindrical portion 421 of the output arm 42 have a facing interval set to be larger than a predetermined dimension in the radial direction. .

As shown in FIG. 10, fitting clearances H ₁₁ and H ₁₂ are provided between the through hole 43 c of the slider gear 43 and the rocker shaft 31 inserted inside thereof. Here, the total dimension of these fitting gaps H ₁₁ and H ₁₂ is set as a fitting gap dimension Δh ₁ between the slider gear 43 and the rocker shaft 31.

Further, meshing gaps H ₂₁ and H ₂₂ are provided between the output-side helical spline 43b of the slider gear 43 and the helical spline 42b of the output arm 42 meshed therewith. Here, the total dimension of the meshing gaps H ₂₁ and H ₂₂ is a radial displacement allowable dimension Δh ₂ between the slider gear 43 and the output arm 42.

  As described above, the position of the slider gear 43 in the axial direction is fixed on the control shaft 32. However, the slider gear 43 can move relatively in the axial direction on the rocker shaft 31, and the rocker shaft 31 is used as a fulcrum. Rotate. As a result, the output arm 42 rotates on the rocker shaft 31 by a predetermined angle with respect to the input arm 41.

Therefore, the amount of radial displacement of the valve lift mechanism 4 with respect to the control shaft 32 at this time, that is, Δh ₁ + Δh ₂ is the radial opposition between the cylindrical portion 411 of the input arm 41 and the small-diameter cylindrical portion 421 of the output arm 42. If the interval is Δh ₃ (= H ₃₁ + H ₃₂ ), the system is configured to satisfy the expression (1).

Δh ₃ > Δh ₁ + Δh ₂ (1)
Thereby, even if the valve lift mechanism 4 is displaced in the radial direction with respect to the control shaft 32, there is a margin in the facing distance Δh ₃ between the input arm 41 and the output arm 42, and the displacement amount in the radial direction is allowed. The cylindrical portion 411 of the input arm 41 and the small-diameter cylindrical portion 421 of the output arm 42 do not interfere with each other in the radial direction, so that the movements of both the arms 41 and 42 during relative rotation can be made smooth.

  Since both arms 41 and 42 and the slider gear 43 bear a load at the meshing portion of each helical spline, the cylindrical portion 411 of the input arm 41 and the small diameter cylindrical portion 421 of the output arm 42 are connected to each other. By setting the facing distance of such a dimension, it is possible to suppress or prevent radial interference, and smooth relative rotation is possible.

  Further, an inner flange portion 422 extending inward in the radial direction is provided at the outer end portion in the axial direction of the cylindrical housing 42 a of the output arm 42, that is, the end portion on the side opposite to the input arm 41. The inner diameter of the inner flange 422 is set to be smaller than the inscribed circle diameter connecting the tooth tips of the helical spline 42b provided on the inner periphery of the cylindrical housing 42a.

  The inner collar portion 422 of the output arm 42 is opposed to the outer peripheral surface of the rocker shaft 31 at a predetermined interval in the radial direction. The radial facing interval is opposed to the non-rotating rocker shaft 31. The output arm 42 is set to be relatively large so as not to interfere when it rotates.

Specifically, as shown in FIG. 10, opposed spaces H ₄₁ and H ₄₂ are provided in the radial direction between the inner flange portion 422 and the outer peripheral surface of the rocker shaft 31.

Here, the total dimension of these facing intervals H ₄₁ and H ₄₂ is set to the inner collar portion 42 of the output arm 42.
2 and the rocker shaft 31, the non-contact facing distance Δh _{4 in} the radial direction is configured so that the non-contact facing distance Δh ₄ (= H ₄₁ + H ₄₂ ) satisfies the formula (2).

Δh ₄ > Δh ₁ + Δh ₂ (2)
As a result, even if the valve lift mechanism 4 is displaced in the radial direction with respect to the control shaft 32, the output arm 42 is allowed by the non-contact facing distance Δh ₄ between the output arm 42 and the rocker shaft 31. It is possible to move smoothly without interfering when turning up.

  Therefore, the input arm 41 and the output arm 42 of the valve lift mechanism 4 rotate smoothly on the rocker shaft 31 with the friction at the time of relative rotation being greatly reduced, and the operating characteristics of the intake valve 14 are efficiently changed. It becomes possible to do.

  Note that the configuration of the cylindrical portion of the input arm 41 and the output arm 42 is not limited to the form of the cylindrical portion 411 and the small-diameter cylindrical portion 421 as described above. The arm may be provided with a small-diameter cylindrical portion to have a loose fit that does not interfere with each other in the radial direction. In any configuration, by providing a cylindrical portion facing the input arm 41 and the output arm 42 in a non-contact manner, foreign matters in the oil do not enter the inside of the arms 41 and 42, and smooth relative rotation is achieved. It will be possible to move.

1 is a plan view schematically showing a variable valve mechanism for an internal combustion engine according to the present invention. It is an arrow line view of the D1-D1 line cross section in FIG. It is a perspective view of the variable valve mechanism of FIG. FIG. 4 is an exploded perspective view of the valve lift mechanism of FIG. 3. It is a disassembled perspective view which shows the relationship between the slider gear and rocker shaft of the valve lift mechanism of FIG. It is a perspective view which fractures | ruptures and shows the upper half of the valve lift mechanism 4 of FIG. FIG. 6 is an operation explanatory diagram when the relative phase difference between the input arm and the output arm in FIG. 1 is maximized. FIG. 6 is an operation explanatory diagram when the relative phase difference between the input arm and the output arm in FIG. 1 is minimized. It is an arrow line view which shows the D2-D2 line cross section of FIG. It is explanatory drawing which expands and shows partially the valve lift mechanism 4 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 11 Cylinder block 12 Cylinder head 13 Cylinder 14 Intake valve 15 Exhaust valve 16 Intake cam shaft 17 Intake cam 18 Exhaust cam shaft 19 Exhaust cam 21 Partition 23 Timing chain 24 Roller rocker arm 24a Roller 25 Rush adjuster 26 Lost motion spring 27 Shim 3 Variable valve mechanism 30 Center shaft 31 Rocker shaft 31a Long hole 32 Control shaft 32a Insertion hole 33 Actuator 4 Valve lift mechanism 41 Input arm 41a Housing 41b Helical spline 41cL, 41cR Fork 41d Support shaft 41e Roller 411 Cylindrical portion 42 Output arm 42a Housing 42b Helical spline 42c Nose 42d Cam surface 421 Small diameter cylindrical portion 422 Inner flange 43 Slider gear 4 3a Input side helical spline 43b Output side helical spline 43c Through hole 43d Long hole 44 Locking pin

Claims (4)

In a variable valve mechanism that can change the operating characteristics of an intake valve or an exhaust valve of an internal combustion engine,
A valve lift mechanism is arranged between the intake valve or exhaust valve and the camshaft,
This valve lift mechanism is arranged on a rocker shaft in which the control shaft is inserted so as to be displaceable in the axial direction and can be interlocked with the displacement of the control shaft, and is mounted on the slider gear and driven from the camshaft. An input arm that receives force, an output arm that is mounted on the slider gear adjacent to the input arm in the axial direction and lifts the valve, and
On the outer periphery of the slider gear, there are provided an input-side helical spline and an output-side helical spline in which the inclination direction of the teeth is opposite, and an helical surface that meshes with the input-side helical spline of the slider gear on the inner peripheral surface of the input arm. A spline is provided, and a helical spline that meshes with the output-side helical spline of the slider gear is provided on the inner peripheral surface of the output arm, and when these helical splines are meshed with each other, the input arm and the output arm are connected to the slider gear. Is configured to change the operating characteristics of the valve by rotating the output arm by a predetermined angle with respect to the input arm by the axial displacement of the control shaft,
In these input arms and output arms, cylindrical portions that are fitted so as to face each other in a non-contact manner are provided on the ends adjacent to each other in the axial direction.
A variable valve mechanism for an internal combustion engine, characterized in that a radial facing distance between both cylindrical portions of the input arm and the output arm is set to be larger than a radial displacement allowable amount of the entire valve lift mechanism with respect to the rocker shaft. . The inner peripheral surface of the output arm on the side opposite to the input arm faces non-contact with the outer peripheral surface of the rocker shaft,
2. The variable valve mechanism for an internal combustion engine according to claim 1, wherein the non-contact facing distance is set to be larger than a radial displacement amount of the entire valve lift mechanism with respect to the rocker shaft. When the fitting clearance dimension between the rocker shaft and the slider gear is Δh ₁ , and the radial displacement allowable dimension of the output arm relative to the slider gear is Δh ₂ , the radial facing between the cylindrical portion of the input arm and the cylindrical portion of the output arm The interval Δh ₃ is
Δh ₃ > Δh ₁ + Δh ₂
The variable valve mechanism for an internal combustion engine according to claim 1 or 2, wherein: Non-contact between the inner peripheral surface of the end of the output arm and the outer peripheral surface of the rocker shaft when the fitting clearance between the rocker shaft and the slider gear is Δh ₁ and the allowable radial displacement of the output arm relative to the slider gear is Δh ₂ The facing interval Δh ₄ is
Δh ₄ > Δh ₁ + Δh ₂
The variable valve mechanism for an internal combustion engine according to claim 2 or 3, wherein:

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