JP4245543B2 - Variable valve mechanism for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve mechanism for an internal combustion engine in which a clearance between a main body of a valve characteristic adjusting mechanism and a reference wall is absorbed by a shim.

  A variable valve mechanism is known in which a mechanism provided on a cylinder head of an internal combustion engine is driven by an axial movement of a control shaft to adjust valve characteristics such as a valve lift amount and a valve working angle of an intake valve and an exhaust valve. (For example, refer to Patent Document 1).

  In such a variable valve mechanism, a support pipe (hereinafter referred to as “rocker shaft”) in which a control shaft is disposed in order to swingably support a mediating drive mechanism used as a valve characteristic adjusting mechanism is supported. ) Is inserted through the center axis position of the mediation drive mechanism. Thus, the intermediate drive mechanism can swing while being supported by the rocker shaft when the valve is driven.

  The rocker shaft is supported by standing walls provided on the cylinder head side on both sides of each intermediate drive mechanism. As a result, the axial reference position in the mediation drive mechanism arranged for each cylinder is determined based on the standing wall. By setting the reference position determined by such a standing wall portion with high accuracy for each cylinder, the valve characteristic adjustment amount by the control shaft can be prevented from varying among the cylinders.

  However, since there is a gap between the reference wall portion (the above-mentioned standing wall portion) formed on the cylinder head and the reference position, the clearance between the intermediate drive mechanism arranged at the reference position and the reference wall portion is actually absorbed. Select and place shims of appropriate thickness.

  Thus, it is necessary to prevent the shim from falling off from the internal combustion engine after the shim having an appropriate thickness is applied between the reference wall portion and the intermediate drive mechanism. For this purpose, for example, a configuration in which a recess is formed in the shim and the rocker shaft is accommodated in the recess so as to straddle the rocker shaft is conceivable.

  However, if the rocker shaft is simply housed in the recess, the shim may rotate around the rocker shaft due to vibration during operation of the internal combustion engine or the like, and the opening of the recess may be above the rocker shaft. In such a state, the shim may come off the rocker shaft and fall off.

Although it is different from a shim, there is a technique in which a groove is formed in a shaft and a ring is fitted in a valve gear for an internal combustion engine to prevent the member from coming off (see, for example, Patent Document 2).
It can be considered that such a snap ring type shape is applied to the shim of Patent Document 1 to prevent it from coming off the rocker shaft.
Japanese Patent Laid-Open No. 2001-263015 (page 7-8, FIG. 5-20) JP-A-10-121916 (page 3, FIG. 5)

  However, if shims with various thicknesses for clearance absorption are made into a snap ring type, it is particularly difficult to attach and detach the shim to the rocker shaft. Clearance absorption work by exchanging shims with various thicknesses is extremely workable. It will be low.

  It is an object of the present invention to provide a variable valve mechanism that can reliably prevent a shim from absorbing a clearance between a main body of a valve characteristic adjusting mechanism and a reference wall, and can be easily attached and detached for shim selection. Is.

In the following, means for achieving the above object and its effects are described.
The variable valve mechanism for an internal combustion engine according to claim 1 is a control shaft that changes the valve characteristic adjustment amount of the internal combustion engine by the valve characteristic adjustment mechanism by being axially moved by an actuator, and a direction coaxial with the control shaft And a rocker shaft that supports the valve characteristic adjustment mechanism, and a reference position of the main body of the valve characteristic adjustment mechanism by preventing the main body of the valve characteristic adjustment mechanism from following the axial movement of the control shaft. A reference wall portion to be set, and a clearance between the reference wall portion and the main body of the valve characteristic adjusting mechanism disposed between the reference wall portion and the main body of the valve characteristic adjusting mechanism disposed at a reference position. a variable valve mechanism for an internal combustion engine provided with a shim to absorb, the rocker shaft, the outer peripheral surface at positions before Symbol shim Only a portion of the circumferential direction forms a retraction plane retracted to the center axis side from the cylindrical base outer peripheral surface, said shim, a recess for accommodating the rocker shaft in the retracted surface position, the An interval between two opposing inner surfaces of the recess is set to be larger than a width of the rocker shaft on the receding surface and smaller than a diameter of a cylindrical base outer peripheral surface of the rocker shaft.

  The rocker shaft has the above-described receding surface, and in the recess for housing the rocker shaft provided in the shim, the distance between the two inner surfaces facing each other is larger than the width of the rocker shaft on the receding surface. For this reason, it is easy for the shim to house and remove the rocker shaft in the recess during clearance absorption work, and the shim replacement workability is improved.

  Further, since the distance between the two opposing inner surfaces of the recess is set to be smaller than the diameter of the cylindrical base outer peripheral surface of the rocker shaft, even if vibration occurs during operation of the internal combustion engine after the shim is installed, the shim Is prevented from rotating around the rocker shaft. For this reason, the opening part of a recessed part does not become above a rocker shaft, and it can prevent that a shim remove | deviates from a rocker shaft and falls.

  Therefore, the variable valve mechanism according to the present invention can surely prevent the shim from absorbing the clearance between the main body of the valve characteristic adjusting mechanism and the reference wall portion, and can easily perform the attaching / detaching operation for selecting the shim.

The variable valve mechanism for an internal combustion engine according to claim 2 is characterized in that, in claim 1, the receding surface is formed as a flat surface.
Even if the receding surface is flat, it is possible to reliably prevent the shim from absorbing the clearance between the main body of the valve characteristic adjusting mechanism and the reference wall, and to facilitate the attachment / detachment work for shim selection. A variable valve mechanism can be realized.

  According to a third aspect of the present invention, there is provided the variable valve mechanism for the internal combustion engine according to the first or second aspect, wherein the two receding surfaces are provided at opposing positions in the circumferential direction of the outer peripheral surface of the rocker shaft. Features.

Even if one receding surface produces an effect, by providing two at the opposed positions, it is possible to more reliably enhance the prevention of shim rotation and ease of attachment / detachment.
According to a fourth aspect of the present invention, in the variable valve mechanism for an internal combustion engine according to the third aspect, the receding surface is two parallel planes.

Even when two receding surfaces are provided, the rotation of the shim and the ease of attachment / detachment can be improved more reliably by using two parallel planes.
A variable valve mechanism for an internal combustion engine according to a fifth aspect is characterized in that in any one of the first to fourth aspects, two opposing inner surfaces of the recess of the shim are two parallel planes.

As described above, the two inner surfaces facing each other in the concave portion of the shim can also prevent the shim from rotating and be easily attached / detached by using two parallel planes.
The variable valve mechanism for an internal combustion engine according to claim 6, wherein the valve characteristic adjusting mechanism is configured such that the slider gear is moved in the axial direction in the main body by the control shaft. Accordingly, the valve characteristic adjustment amount is changed by the helical spline engagement between the main body and the slider gear, and the receding surface is formed in the axial direction from at least the shim arrangement position to the internal space of the main body. It is characterized by.

  As described above, since the receding surface is formed from at least the shim arrangement position to the internal space in the main body of the valve characteristic adjusting mechanism, a gap is generated between the rocker shaft and the main body at the receding surface portion. . Therefore, the positive or negative pressure of gas or liquid generated by the volume change in the main body when the slider gear moves in the axial direction can be discharged to the outside through this gap.

  Further, when the pressure is discharged, the distance between the two inner surfaces of the shim recess facing each other is larger than the width of the rocker shaft on the receding surface, so there is a gap between the inner surface of the shim recess and the outer peripheral surface of the rocker shaft. Has occurred.

  Therefore, the gap generated between the rocker shaft and the main body and the gap generated between the inner surface of the recessed portion of the shim and the outer peripheral surface of the rocker shaft cause the pressure generated in the main body of the valve characteristic adjusting mechanism. Emission becomes easy, and the valve characteristics of the internal combustion engine can be adjusted by the actuator with less energy.

  In particular, if two receding surfaces are formed at opposite positions on the rocker shaft, a gap is formed between the rocker shaft and the main body, and between the inner surface of the recess of the shim and the outer peripheral surface of the rocker shaft. Continuity with the gap is further ensured, and the energy saving effect can be further enhanced.

  The variable valve mechanism for an internal combustion engine according to claim 7, wherein the valve characteristic adjusting mechanism is configured such that a slider gear is moved in the axial direction in the main body by the control shaft. As a result, the valve characteristic adjustment amount is changed by the helical spline engagement between the main body and the slider gear, and a part of the outer peripheral surface of the rocker shaft in the circumferential direction extends from the cylindrical base outer peripheral surface to the central axis side. A second receding surface formed in a receded state is formed over the interior space of the main body continuously from the receding surface.

  It is not necessary to relate the width of the rocker shaft on the receding surface to the distance between the two inner surfaces facing each other in the recess of the shim up to the part reaching the internal space of the valve characteristic adjusting mechanism that is not directly related to the shim.

  For this reason, a second receding surface that is not constrained by the distance between the two inner surfaces facing each other in the concave portion of the shim may be formed over the inner space of the main body in succession to the receding surface for preventing the shim from rotating. good.

  Also due to this, a gap formed between the rocker shaft and the main body and a gap formed between the inner surface of the recess of the shim and the outer peripheral surface of the rocker shaft are generated in the main body of the valve characteristic adjusting mechanism. The pressure can be easily discharged, and the valve characteristics of the internal combustion engine can be adjusted by the actuator with less energy.

  In particular, if two surfaces formed by combining the receding surface and the second receding surface are formed at opposing positions on the rocker shaft, a gap formed between the rocker shaft and the main body, and the shim Continuity with the gap formed between the inner surface of the recess and the outer peripheral surface of the rocker shaft is further ensured, and the energy saving effect can be further enhanced.

[Embodiment 1]
1 and 2 show the configuration of a variable valve mechanism in a gasoline engine (hereinafter abbreviated as “engine”) 2 as a multi-cylinder internal combustion engine to which the above-described invention is applied. FIG. 1 shows a longitudinal section of one cylinder. FIG. 2 is a plan view for mainly explaining the configuration on the cam carrier 150 in the upper configuration of the engine 2.

The engine 2 of the present embodiment is for a vehicle and includes a cylinder block 4, a piston 6, and a cylinder head 8 attached on the cylinder block 4.
The cylinder block 4 is formed with a plurality of cylinders, in this embodiment, four cylinders 2a. Each cylinder 2a is formed with a combustion chamber 10 partitioned by the cylinder block 4, the piston 6 and the cylinder head 8. ing. The number of cylinders may be 1 to 3, and may be 5 or more. Further, as in the present embodiment, it may not be an in-line 4-cylinder, but may be a V-type or other arrangement.

  In each cylinder 2a, four valves, two intake valves 12 and two exhaust valves 16, are arranged. The intake valve 12 opens and closes the intake port 14, and the exhaust valve 16 opens and closes the exhaust port 18. The intake ports 14 of all the cylinders 2a are connected to a surge tank via an intake manifold, and distribute the air supplied from the surge tank side to each cylinder 2a. A fuel injection valve is arranged in each intake port 14 or intake manifold so as to inject fuel into the intake port 14 of each cylinder 2a. In addition to the configuration in which fuel is injected on the upstream side of the intake valve 12 as described above, a direct injection gasoline engine that directly injects fuel into each combustion chamber 10 may be used.

  The engine 2 of the present embodiment can adjust the intake air amount by changing the valve lift amount of the intake valve 12. Actually, when the valve lift amount changes, the valve working angle also changes at the same time. Therefore, the description of the valve lift amount also serves as an explanation of the valve working angle.

  In the engine 2 of the present embodiment, a throttle valve is disposed in the intake passage upstream of the surge tank. The throttle valve is normally fully opened when the intake air amount is adjusted by adjusting the valve lift amount of the intake valve 12. As the throttle valve opening control, for example, the throttle valve is fully opened when the engine 2 is started, and the throttle valve is fully closed when the engine 2 is stopped. If the valve lift adjustment of the intake valve 12 becomes impossible for some reason, or if the intake air amount cannot be adjusted sufficiently by adjusting the valve lift of the intake valve 12, the throttle valve opening The intake air amount is controlled by the control.

  The lift drive of the intake valve 12 is possible by transmitting the valve drive force of the intake cam 45a provided on the intake camshaft 45 via the intermediate drive mechanism 120 and the roller rocker arm 52 arranged in the cylinder head 8. It has become. In this valve drive force transmission, the valve lift amount of the intake valve 12 is adjusted by changing the transmission state by the mediation drive mechanism 120 by the function of the slide actuator 100. The intake camshaft 45 is linked to the rotation of the crankshaft 49 of the engine 2 at 1/2 the rotational speed via the timing sprocket provided in the variable valve timing mechanism 140 disposed at one end and the timing chain 47. is doing.

  The exhaust valve 16 of each cylinder 2a is opened and closed by a constant valve lift amount via a roller rocker arm 54 by an exhaust cam 46a provided on an exhaust camshaft 46 that rotates in conjunction with the rotation of the engine 2. The exhaust camshaft 46 is linked to the rotation of the crankshaft 49 of the engine 2 at a half speed through a timing chain 47 and a timing sprocket provided in a valve timing variable mechanism 142 disposed at one end. is doing. Each exhaust port 18 of each cylinder 2a is connected to an exhaust manifold, and exhaust is discharged to the outside through a catalytic converter for purification.

  The intake camshaft 45, the exhaust camshaft 46, the slide actuator 100, the intermediate drive mechanism 120, and the variable valve timing mechanisms 140 and 142 described above are integrated on the cam carrier 150.

  As shown in FIG. 2, the cam carrier 150 forming a part of the cylinder head 8 is integrally formed as a whole in a rectangular shape corresponding to the outer peripheral shape of the upper surface of the cylinder head 8 on the main body side. In the side walls 154, 156, 158, 160, four bearings 162 are arranged in parallel and are integrally formed with the side walls 154 to 160. Of the side walls 154 to 160, the front side wall 154 also serves as a bearing.

  An intake camshaft 45 and an exhaust camshaft 46 are rotatably supported in parallel by the four bearings 162 and the front side wall 154. Further, between the intake camshaft 45 and the side wall 158, four intermediate drive mechanisms 120 provided for each cylinder are supported by the rocker shaft 130 and arranged. The front side wall 154 and the bearing 162 are covered with a cam cap 152 to prevent the intake camshaft 45, the exhaust camshaft 46, and the rocker shaft 130 from falling off.

  The both sides of each intermediate drive mechanism 120 in the axial direction absorb the clearance generated between the bearing 162 or the front side wall 154 and the bearing 162 or the front side wall 154 when the intermediate drive mechanism 120 is disposed at the reference position. A shim 164 is disposed.

  Here, the configuration of the shim 164 is shown in FIG. 3, (A) is a plan view of the shim 164, (B) is a bottom view, (C) is a left side view, (D) is a perspective view, and (E) is a front view. The shim 164 includes a disc-shaped base portion 164a, a pickup portion 164b that protrudes from the outer periphery of the base portion 164a, and a concave portion 164c that is formed from the side facing the pickup portion 164b to the center portion of the base portion 164a. Yes. Two inner surfaces 164d facing each other in the recess 164c form parallel planes. This interval is set to Da.

  When adjusting the variable valve mechanism reference state, a plurality of types of shims 164 with different thicknesses ds of the base 164a are prepared. Then, an appropriate thickness ds is set for the shim 164 on the opposite side (right side in FIG. 2) of each intermediate drive mechanism 120 so that the valve lift adjustment amount of the intermediate drive mechanism 120 is the same between the cylinders. The shim 164 is selected and inserted. The shim 164 on the slide actuator 100 side (left side in FIG. 2) of each mediation drive mechanism 120 is connected to each mediation drive mechanism 120 so that each mediation drive mechanism 120 is always in close contact with the right shim 164 in FIG. A shim 164 having a thickness ds that absorbs the clearance with the bearing 162 is selected and inserted. Thus, the axial position of the mediation drive mechanism 120 is adjusted to an accurate reference position, and the valve lift amounts of the intake valves 12 of all the cylinders 2a by the slide actuator 100 are always set to the same adjustment amount.

  Next, the mediation drive mechanism 120 will be described. 4 is a perspective view of the mediation drive mechanism 120, and FIG. 5 is a partially cutaway perspective view. 5A is a partially broken perspective view of the front side, and FIG. 5B is a partially broken perspective view of the back side. 6 is an exploded perspective view, and FIG. 7 is a cutaway perspective view showing the configuration of the outer portion (corresponding to the main body) of the intermediate drive mechanism 120 corresponding to FIG. Except for FIG. 7, the intermediate drive mechanism 120 is illustrated as being disposed on the rocker shaft 130.

  The intermediate drive mechanism 120 includes an input portion 122 provided in the center of FIG. 4, a first swing cam 124 provided on one end side of the input portion 122, and a first swing cam 124 provided on the opposite side of the first swing cam 124. 2 includes a rocking cam 126 and a slider gear 128 (FIGS. 5 and 6) disposed therein.

  The housing 122a of the input part 122 forms a space in the axial direction inside, and a helical spline 122b (FIG. 7) formed in a spiral shape of a right-hand screw is formed in the axial direction on the inner peripheral surface of this space. Further, two parallel arms 122c and 122d are formed so as to protrude from the outer peripheral surface of the housing 122a. A shaft 122e parallel to the axial direction of the housing 122a is stretched over the tips of the arms 122c and 122d, and a roller 122f is rotatably attached. As shown in FIG. 1, a biasing force is applied to the arms 122c and 122d or the housing 122a by a spring 129 or the like, so that the roller 122f is always in contact with the intake cam 45a. Such a spring 129 is provided between the input part 122 and the cylinder head 8 or the rocker shaft 130, for example.

  The housing 124a of the first swing cam 124 forms a space in the axial direction inside, and a helical spline 124b (FIG. 7) formed in a spiral shape of a left-hand screw in the axial direction is formed on the inner peripheral surface of the internal space. Forming. One end of the internal space of the housing 124a is covered with a ring-shaped bearing portion 124c having a circular bearing hole 124f as a center. The bearing hole 124 f is formed to have the same diameter as the base outer peripheral surface 130 d (FIG. 11) of the rocker shaft 130 and is penetrated by the rocker shaft 130. Further, a substantially triangular nose 124d protrudes from the outer peripheral surface. One side of the nose 124d forms a cam surface 124e.

  The housing 126a of the second swing cam 126 forms a space in the axial direction inside, and a helical spline 126b (FIG. 7) formed in a spiral shape of a left-hand screw in the axial direction is formed on the inner peripheral surface of the internal space. Forming. One end of the internal space of the housing 126a is covered with a ring-shaped bearing portion 126c having a circular bearing hole 126f as a center. The bearing hole 126f is formed to have the same diameter as the base outer peripheral surface 130d (FIG. 11) of the rocker shaft 130, and is penetrated by the rocker shaft 130. Further, a substantially triangular nose 126d protrudes from the outer peripheral surface. One side of the nose 126d forms a cam surface 126e.

  As shown in FIG. 6, the first swing cam 124 and the second swing cam 126 are arranged so that the end faces are coaxially contacted from both sides with respect to the input portion 122, and the whole is shown in FIG. As shown, it has a substantially cylindrical shape with an internal space.

  Details of the slider gear 128 disposed in the internal space constituted by the input portion 122 and the two swing cams 124 and 126 are shown in FIGS. 8A is a plan view, FIG. 8B is a front view, and FIG. 8C is a right side view. FIG. 9 is a perspective view, and FIG. 10 is a perspective view cut vertically along the axis.

  The slider gear 128 has a substantially cylindrical shape, and an input helical spline 128a formed in a spiral shape of a right-hand thread is formed at the center of the outer peripheral surface. A first output helical spline 128c is formed on one end side of the input helical spline 128a so as to have a left-handed spiral shape with a small diameter portion 128b interposed therebetween. On the opposite side of the first output helical spline 128c, a second output helical spline 128e formed in a spiral shape of a left-hand thread with a small diameter portion 128d interposed therebetween is formed. The output helical splines 128c and 128e have the same outer diameter, but are formed to have an outer diameter smaller than the diameter of the groove portion of the input helical spline 128a.

  A through hole 128f through which the rocker shaft 130 passes is formed in the slider gear 128 in the central axis direction. A circumferential groove 128g is formed in the circumferential direction on the inner circumferential surface of the through hole 128f at the position of the input helical spline 128a. The circumferential groove 128g is formed with a pin insertion hole 128h penetrating to the outside in one radial direction.

  The rocker shaft 130 that supports the entire intermediate drive mechanism 120 by passing through the bearing holes 124f and 126f of the swing cams 124 and 126 and the through hole 128f of the slider gear 128 will be described. A portion of the rocker shaft 130 is shown in the perspective views of FIGS. (A) and (B) are the perspective views shown by the arrangement | positioning which differs 180 degrees around an axis | shaft. As shown in FIG. 2, the rocker shaft 130 is provided in common with the four mediating drive mechanisms 120.

  The rocker shaft 130 has a long hole 130a that is formed long in the axial direction at a position corresponding to each intermediate drive mechanism 120. The long hole 130 a is formed so as to penetrate to the internal space 130 b of the rocker shaft 130.

  As shown in FIG. 11A, two flat receding surfaces 130c are provided adjacent to the longitudinal direction of the long hole 130a. Further, two receding surfaces 130c are provided at different positions around the 180 ° axis with respect to these two receding surfaces 130c as shown in FIG.

  Two receding surfaces 130c having the same axial position and different around the 180 ° axis form a set of parallel planes. As a result, two sets of receding surfaces 130c are formed in each intermediary drive mechanism 120, and a total of eight sets of receding surfaces 130c are formed in one rocker shaft 130.

  The receding surface 130c is formed by flattening the cylindrical base outer peripheral surface 130d of the rocker shaft 130 by cutting or the like, and is a surface receding from the base outer peripheral surface 130d of the rocker shaft 130 to the axial side. ing.

  Further, in the internal space 130b of the rocker shaft 130, a control shaft 132, which shows a part in the axial direction in the perspective view of FIG. 11C, is slidable in the axial direction as shown in FIG. 11D. It is arranged through. The control shaft 132 is also provided in common with the four mediating drive mechanisms 120.

  Although the control shaft 132 is formed in a round bar shape, a support hole 132b in a direction perpendicular to the axis is provided at a position corresponding to each intermediary drive mechanism 120 as shown in FIG. By inserting the base end portion of the control pin 132a into each of the support holes 132b, the control pin 132a can be supported by protruding in the direction perpendicular to the axis.

  When the control shaft 132 is disposed inside the rocker shaft 130, the tip of each control pin 132a passes through the long hole 130a formed in the rocker shaft 130, as shown in the partially cutaway view of FIG. The slider gear 128 is inserted into a circumferential groove 128g formed on the inner circumferential surface.

  One end side (right side in FIG. 2) of the control shaft 132 is a free end, but the base end side (left side in FIG. 2) forms a ball screw shaft driven by the slide actuator 100. As a result, a driving force in the axial direction can be received from the slide actuator 100 via the ball screw mechanism 210. Note that a ball screw shaft may be formed separately from the control shaft 132 and incorporated in the ball screw mechanism 210. In this case, for example, the control shaft 132 can be driven in the axial direction by the slide actuator 100 by contacting or joining the base end side of the control shaft 132 and the tip end side of the ball screw shaft on the cam carrier 150. To do.

  As shown in FIG. 2, shims 164 are provided on both sides of the intermediate drive mechanism 120 between the first swing cam 124 and the bearing 162 and between the second swing cam 126 and the front side wall 154 or the bearing 162, respectively. Is arranged. The axial position of the receding surface 130c on the rocker shaft 130 is set so that these shims 164 are arranged at the position of the receding surface 130c described above.

  As shown in FIG. 13, the distance Da between the inner surfaces 164d of the shim 164 is set larger than the distance between the two receding surfaces 130c constituting the set, that is, the width Dc of the rocker shaft 130 in the receding surface 130c portion. Further, the interval Da between the inner surfaces 164d is set to be smaller than the width of the rocker shaft 130 at a portion other than the receding surface 130c, that is, the diameter Db of the cylindrical base outer peripheral surface 130d of the rocker shaft 130.

  The variable valve mechanism is assembled as follows. First, the control shaft 132 is inserted into the rocker shaft 130. The slider gear 128 described above is attached to the control shaft 132 through the long hole 130a of the rocker shaft 130 by the control pin 132a for each cylinder 2a. As a result, each slider gear 128 is interlocked with the axial movement of the control shaft 132. Then, the input unit 122 and the swing cams 124 and 126 are combined with the slider gears 128 by helical spline engagement to complete the intermediate drive mechanism 120 for each cylinder 2a.

  As described above, the rocker shaft 130 to which the intermediate drive mechanism 120 is attached is disposed on the cam carrier 150. At the same time, the intake camshaft 45 and the exhaust camshaft 46 are also arranged on the cam carrier 150. The rocker shaft 130 is fixed by the cam cap 152, and the intake cam shaft 45 and the exhaust cam shaft 46 are rotatably supported.

  In addition, the base end side of the control shaft 132 disposed in the rocker shaft 130 is incorporated in the ball screw mechanism 210 of the slide actuator 100. Alternatively, the base end side of the control shaft 132 is brought into contact with or joined to the tip of the ball screw shaft incorporated in the ball screw mechanism 210. At this time, the slide actuator 100 is set to the initial driving position, so that the control shaft 132 is disposed at the initial position in the axial direction.

  However, even if the control shaft 132 inside the rocker shaft 130 is in the initial position, the input portion 122 and the swing cams 124 and 126 which are the main body of the intermediate drive mechanism 120 are in the reference arrangement corresponding to the initial position of the control shaft 132. Not necessarily. In FIG. 2, the front side wall 154 or the bearing 162 on the right side of each intermediate drive mechanism 120 determines the arrangement of the intermediate drive mechanism 120, but the position of the left side surface of the front side wall 154 or the bearing 162 is actually the cam carrier 150. At the time of manufacture, it is molded so as to be on the right side of the reference position. Therefore, the shim 164 is used to adjust the reference position with high accuracy.

  Here, in the mediation drive mechanism 120, the reference arrangement corresponding to the initial position of the control shaft 132 is an arrangement in which the minimum valve lift amount shown in FIG. However, in the state of being arranged on the cam carrier 150, as shown in FIG. 14A, the positional relationship between the noses 124d and 126d and the roller 122f is closer to the minimum valve lift amount.

  Therefore, the variable valve mechanism reference state adjusting method is executed as follows. First, the cam carrier 150 is fixed on a jig for adjusting the reference arrangement. As a result, as shown in FIG. 14A, the tips of positioning pivots p1 and p2 provided on the jig come into contact with the cam surfaces 124e and 126e of the noses 124d and 126d.

  The base circle portion of the intake camshaft 45 is directed toward the roller 122f. However, at this time, as described above, since the positions of the noses 124d and 126d and the roller 122f are closer than the minimum valve lift amount, the roller 122f is not in contact with the intake camshaft 45. When the intake camshaft 45 is disposed later on the cam carrier 150, a special jig corresponding to the shape of the base circle portion of the intake camshaft 45 may be used.

  Next, the mediation drive mechanism 120 is moved to the slide actuator 100 side by pushing the mediation drive mechanism 120 in the axial direction toward the slide actuator 100 side by a mechanical force such as hydraulic pressure or manually. Since the slider gear 128 in the intermediate drive mechanism 120 is engaged with the control shaft 132 by the control pin 132a, the slider gear 128 does not move in the axial direction, and the input portion 122 and the swing cams 124, 126 are in the axial direction. Move to. Accordingly, the slider gear 128 moves in the H direction shown in FIGS. 4 and 5 relative to the input portion 122 and the swing cams 124 and 126 in the intermediate drive mechanism 120. In conjunction with this movement, the noses 124d and 126d and the roller 122f begin to separate.

  Finally, as shown in FIG. 14B, the roller 122f comes into contact with the base circle portion of the intake camshaft 45, and further movement of the intermediate drive mechanism 120 in the axial direction becomes impossible. The axial position of the mediation drive mechanism 120 on the rocker shaft 130 at this time is a reference arrangement corresponding to the initial position of the control shaft 132, and corresponds to the state shown in FIG.

  At this time, the thickness ds conforms to the clearance between the bearing 162 including the cam cap 152 or the front side wall 154 generated on the right side (opposite side of the slide actuator 100) of the intermediate drive mechanism 120 shown in FIG. The shim 164 is selected and disposed on the receding surface 130c as shown in FIGS. As a result, the reference arrangement of the mediation drive mechanism 120 is determined. As shown in FIGS. 15A and 15B, the left side (slide actuator 100 side) of the intermediate drive mechanism 120 has a thickness that matches the clearance generated between the bearing 162 including the cam cap 152. A shim 164 having a length ds is selected and disposed on the receding surface 130c. 15A shows the arrangement state of the shim 164 as viewed from the front of the intermediate drive mechanism 120, FIG. 15B shows the arrangement state of the shim 164 as viewed from the left side of the intermediate drive mechanism 120, and FIG. The arrangement state of the shim 164 as viewed from the right side surface of the mediation drive mechanism 120 is shown.

  In this way, the intermediate drive mechanism 120 determines the reference position by the right shim 164 in FIG. 2, restricts the movement of the first swing cam 124 by the left shim 164, and in particular, lift drive force for the intake valve 12. Can be prevented from falling off from the slider gear 128.

  By repeating this variable valve mechanism reference state adjusting method for the intermediate drive mechanism 120 of each cylinder, the reference arrangement of the intermediate drive mechanism 120 is set for all cylinders using two shims 164 as shown in the perspective view of FIG. High accuracy can be set.

  In the selection operation of the shim 164, as shown in FIG. 13, the distance Da between the inner surfaces 164d of the shim 164 is larger than the width Dc between the receding surfaces 130c, so that the rocker shaft 130 is shown in FIG. And a sufficient allowance between the receding surface 130c. For this reason, when the shim 164 is selected, it is possible to easily attach and detach the rocker shaft 130 to the receding surface 130c.

  Thus, the configuration on the cam carrier 150 is completed. As shown in FIGS. 1 and 2, the variable valve mechanism can be incorporated into the engine 2 by attaching the cam carrier 150 to the main body of the cylinder head 8.

  In the engine 2 using the variable valve mechanism configured as described above, the ball screw mechanism 210 is driven by the slide actuator 100 and the control shaft 132 is moved in the axial direction, whereby the slider gear 128 inside the mediation drive mechanism 120 is moved. Adjust the axial position of.

  As shown in FIG. 12, since the slider gear 128 is engaged with the control pin 132a by the circumferential groove 128g, the slider gear 128 can swing about the axis regardless of the position of the control pin 132a. Further, the input helical spline 128 a of the slider gear 128 is engaged with the helical spline 122 b inside the input unit 122. The first output helical spline 128 c is meshed with the helical spline 124 b inside the first swing cam 124, and the second output helical spline 128 e is meshed with the helical spline 126 b inside the second swing cam 126. Here, the input side splines 122b, 128a and the output side splines 124b, 128c, 126b, 128e have different twist angles. Actually, the twist direction itself has a different shape.

  From this, by adjusting the axial movement amount of the slider gear 128 in the internal space of the mediation drive mechanism 120, the function of the helical splines 128a, 122b, 128c, 124b, 128e, 126b and the input portion 122 are swung. The cams 124 and 126 can be rotated relative to each other. Thus, the positional relationship between the roller 122f and the noses 124d and 126d can be changed, and the valve lift amount of the intake valve 12 can be adjusted.

  Here, FIG. 18 shows a state of the mediation drive mechanism 120 when the drive force of the slide actuator 100 is adjusted and the control shaft 132 is moved in the L direction (arrow in FIGS. 4 and 5) as much as possible. 18A is when the intake valve 12 is closed, and FIG. 18B is when the valve is open. In this case, the positional relationship between the roller 122f of the input unit 122 and the noses 124d and 126d of the swing cams 124 and 126 is the closest, that is, the same state as in FIG. Therefore, as shown in FIG. 18B, even if the intake cam 45a pushes down the roller 122f of the input portion 122 to the maximum extent, the push-down amount of the rocker roller 52a by the cam surfaces 124e and 126e of the noses 124d and 126d is minimized. The valve lift amount of the intake valve 12 is minimized. Therefore, the amount of intake air from the intake port 14 into the combustion chamber 10 is also minimized.

  FIG. 19 shows the state of the mediation drive mechanism 120 when the drive force of the slide actuator 100 is adjusted and the control shaft 132 is moved in the H direction (arrows in FIGS. 4 and 5) as much as possible. 19A is when the intake valve 12 is closed, and FIG. 19B is when the valve is open. In this case, the positional relationship between the roller 122f of the input unit 122 and the noses 124d and 126d of the swing cams 124 and 126 is the farthest. For this reason, as shown in FIG. 19B, when the intake cam 45a pushes down the roller 122f of the input portion 122 to the maximum extent, the push-down amount of the rocker roller 52a by the cam surfaces 124e and 126e of the noses 124d and 126d is maximized. The valve lift amount of the intake valve 12 is maximized. Therefore, the amount of intake air from the intake port 14 into the combustion chamber 10 is also maximized.

  By adjusting the axial position of the control shaft 132 continuously between the state of FIG. 18 and the state of FIG. 19 by the slide actuator 100, the valve lift amount of the intake valve 12 can be continuously adjusted. That is, in the present embodiment, it is possible to adjust the intake air amount steplessly without using a throttle valve.

  As shown in FIG. 18B, in the initial position state, the valve lift amount when the intake valve 12 is opened produces a certain degree of opening. As described above, the valve lift amount “0”, that is, the intake valve 12 may be completely closed. In this case, the intake air amount is “0”.

  When such an engine is operated, as shown in FIG. 17A, vibration is transmitted to each shim 164 arranged on the rocker shaft 130, and there is a case where a force for rotating the shim 164 around the rocker shaft 130 is applied. is there. However, even if the shim 164 rotates, the distance Da between the inner surfaces 164d of the shim 164 is smaller than the diameter Db of the cylindrical base outer peripheral surface 130d of the rocker shaft 130. Therefore, as shown in FIG. Only a slight rotation is allowed for the rocker shaft 130. Therefore, the shim 164 does not rotate greatly, and the opening of the recess 164c (FIGS. 3 and 13) of the shim 164 does not move to the upper part of the rocker shaft 130, so that the shim 164 does not fall off the rocker shaft 130. .

  As shown in FIGS. 4 to 7, circular bearing holes 124 f and 126 f are formed in the bearing portions 124 c and 126 c of the swing cams 124 and 126 to swing about the rocker shaft 130. The receding surface 130c provided on the rocker shaft 130 is not limited to the position where the shim 164 is supported, but passes through the bearing holes 124f and 126f and reaches the internal space of the swing cams 124 and 126. Thus, a gap 130e (FIGS. 1, 13, 14, 17 to 19) that connects the inside and the outside of the swing cams 124 and 126 is formed.

  Furthermore, the shims 164 that are in close contact with the bearing portions 124c and 126c are shown in FIGS. 17A and 17B because the interval Da between the inner surfaces 164d of the recesses 164c is larger than the width Dc between the receding surfaces 130c. Thus, a gap 164f is generated. Therefore, the gap 130e between the rocking cams 124 and 126 and the rocker shaft 130 is not closed by the shim 164 but is connected to the gap 164f between the shim 164 and the rocker shaft 130. The exit is secured.

  In this way, the internal space of the swing cams 124, 126, which is closed on one side by the slider gear 128, is always in communication with the outside through the gap 130e and the gap 164f using the receding surface 130c. Therefore, even if the volume of the internal space of the rocking cams 124 and 126 changes due to the axial movement of the slider gear 128 accompanying the axial movement of the control shaft 132, the internal positive pressure and negative pressure are transferred from the gap 130e and the gap 164f. Can be discharged.

According to the first embodiment described above, the following effects can be obtained.
(I). As shown in FIG. 13, the distance Da between the inner surfaces 164d of the shim 164 is larger than the width Dc between the receding surfaces 130c. For this reason, a sufficient margin is provided between the rocker shaft 130 and the receding surface 130c, and when the shim 164 is selected, the attaching / detaching operation to the rocking shaft 130c portion of the rocker shaft 130 can be facilitated.

  Further, the distance Da between the inner surfaces 164d is smaller than the diameter Db of the cylindrical base outer peripheral surface 130d of the rocker shaft 130. For this reason, the shim 164 is only allowed to rotate slightly with respect to the rocker shaft 130 and does not rotate greatly, so that the shim 164 does not fall off the rocker shaft 130.

  Therefore, a shim that absorbs the clearance between the main body (the input portion 122 and the swing cams 124 and 126) of the valve characteristic adjusting mechanism (the intermediate drive mechanism 120) and the reference wall portion (the front side wall 154 and the bearing 162 including the cam cap 152). The 164 can be reliably prevented from falling off, and the attaching / detaching operation for selecting the shim 164 can be easily performed.

  (B). The receding surface 130 c of the rocker shaft 130 is formed in the axial direction from the position where the shim 164 is disposed to the internal space of the swing cams 124 and 126. As described above, the positive pressure of gas (here, air) or liquid (here, lubricating oil) generated in the swing cams 124, 126 when the slider gear 128 moves in the axial direction in the gaps 130e, 164f. And negative pressure can be easily discharged to the outside of the mediation drive mechanism 120.

Therefore, the valve characteristics of the engine 2 can be adjusted by the slide actuator 100 with less energy.
Particularly, since two receding surfaces 130c are formed in the rocker shaft 130 in the circumferential direction, the continuity of the two gaps 130e and 164f is further ensured, and the energy saving effect can be further enhanced.

[Embodiment 2]
A rocker shaft 230 of the present embodiment is shown in FIG. In FIG. 20, (A) and (B) are perspective views showing an arrangement different by 180 ° around the axis. (C) is a perspective view of a state where the control shaft 132 is disposed in the internal space 230 b of the rocker shaft 230. FIG. 21 is a perspective view in a state where the rocker shaft 230 and the mediation drive mechanism 220 are combined. FIG. 21A is a front perspective view, and FIG. 21B is a rear perspective view.

Since other configurations are the same as those of the first embodiment, the same configurations will be described with the same reference numerals with reference to the drawings of the first embodiment.
In the rocker shaft 230 of the present embodiment, the receding surface 230c is formed only in the portion where the shim 164 is disposed, and does not reach the swing cams 224, 226. Therefore, when combined with the mediation drive mechanism 220, the pressure in the rocking cams 224 and 226 cannot be discharged by the receding surface 230c. Therefore, through holes 224g and 226g communicating with the internal space are formed on the outer peripheral surfaces of the swing cams 224 and 226.

  The relationship between the distance Da between the inner surfaces 164d of the shim 164, the diameter Db of the cylindrical base outer peripheral surface 230d of the rocker shaft 230, and the width Dc between the receding surfaces 230c is the same as the relationship shown in FIG.

According to the second embodiment described above, the following effects can be obtained.
(I). The effect (a) of the first embodiment is produced.
(B). Through the through holes 224g and 226g provided on the outer peripheral surfaces of the swing cams 224 and 226, positive and negative pressures of gas and liquid generated in the swing cams 224 and 226 when the slider gear 128 moves in the axial direction It can be easily discharged to the outside of the mediation drive mechanism 220. Therefore, it is possible to adjust the valve characteristic of the engine by the slide actuator with less energy.

[Embodiment 3]
As shown in FIG. 22, the rocker shaft 330 according to the present embodiment has two kinds of receding surfaces, ie, a shim disposition receding surface 330c and a pressure exhausting receding surface 330d (corresponding to the second receding surface) through a step. In a continuous state, four locations are formed for each mediation drive mechanism 120. 22, (A) and (B) are perspective views showing an arrangement different by 180 ° around the axis, and (C) is a perspective view showing a state in which the control shaft 132 is arranged in the internal space 330b of the rocker shaft 330. FIG. It is. FIG. 23 is a perspective view of the state in which the rocker shaft 330 and the mediation drive mechanism 120 are combined. FIG. 23A is a front perspective view, and FIG. 23B is a rear perspective view.

Since other configurations are the same as those of the first embodiment, the same configurations will be described with the same reference numerals with reference to the drawings of the first embodiment.
In the rocker shaft 330 of the present embodiment, the shim disposition receding surface 330c is formed with a smaller receding amount, that is, shallower than the pressure exhausting receding surface 330d. Since it is formed so shallow, the width Dc between the shim disposition receding surfaces 330c is larger than that of the first embodiment. However, the magnitude relationship among the distance Da between the inner surfaces of the shims, the diameter Db of the cylindrical base outer peripheral surface 330e of the rocker shaft 330, and the width Dc between the shim placement receding surfaces 330c is similar to that of the first embodiment. <Da <Db is set. Therefore, it is easy to attach and detach the shim to and from the shim disposition receding surface 330c, and after the shim is installed, the shim does not rotate around the rocker shaft 330, thereby preventing the shim from falling off.

  The pressure discharge receding surface 330d is formed slightly outside the swing cams 124 and 126 and deeper than the shim disposition receding surface 330c. A sufficient gap is formed between 126f. Thus, the pressure in the swing cams 124 and 126 can be quickly discharged when the slider gear 128 is moved.

According to the third embodiment described above, the following effects can be obtained.
(I). The effects (a) and (b) of the first embodiment are produced. Further, since the shim disposition receding surface 330c is formed shallower than the pressure exhausting receding surface 330d, the effect of quickly exhausting the pressure in the rocking cams 124 and 126 can be maintained high, and the rigidity of the rocker shaft 330 can be increased. It can be kept higher.

[Embodiment 4]
In the rocker shaft 430 of the present embodiment, as shown in FIG. 24, the receding surface 430c is formed at two phase positions for each of the mediation drive mechanisms 120 at phase positions 180 degrees different from the long holes 430a around the axis. 24 (A) and 24 (B) are perspective views showing an arrangement different by 180 ° around the axis, and FIG. 24 (C) is a perspective view showing a state where the control shaft 132 is arranged in the internal space 430b of the rocker shaft 430. It is.

Since other configurations are the same as those of the first embodiment, the same configurations will be described with the same reference numerals with reference to the drawings of the first embodiment.
In the rocker shaft 430 of the present embodiment, one kind of the receding surface 430c is the same as in the first embodiment, but there are only two receding surfaces 430c corresponding to each intermediate drive mechanism 120. There are some differences.

  And as shown in FIG. 25, the space | interval Da of the inner surface 464d of the shim 464 is larger than the width | variety Dc of the rocker shaft 430 in the receding surface 430c part. Further, the interval Da between the inner surfaces 464d is set to be smaller than the width of the rocker shaft 430 at a portion other than the receding surface 430c, that is, the diameter Db of the cylindrical base outer peripheral surface 430d of the rocker shaft 430.

  Therefore, as shown in FIG. 26A, there is a sufficient margin between the inner surface 464d of the shim 464 and the outer peripheral surface of the rocker shaft 430, and the shim 464 can be attached to and detached from the retracted surface 430c of the rocker shaft 430. Easy to do.

  Even if the shim 464 rotates after the shim 464 is arranged, the distance Da between the inner surfaces 464d of the shim 464 is smaller than the diameter Db of the cylindrical base outer peripheral surface 430d of the rocker shaft 430, and therefore, as shown in FIG. Thus, the shim 464 is only allowed to rotate slightly with respect to the rocker shaft 430. Therefore, the shim 464 does not rotate greatly, and the opening in the recess 464c of the shim 464 does not move to the upper part of the rocker shaft 430, so that the shim 464 does not fall off the rocker shaft 430.

  Further, as described in the first embodiment, the internal space of the swing cams 124 and 126 is communicated with the outside through the gap 430e generated by the receding surface 430c. Therefore, even if the volume of the internal space of the swing cams 124 and 126 changes due to the axial movement of the slider gear accompanying the axial movement of the control shaft 132, the internal positive pressure or negative pressure can be discharged from the gap 430e. it can.

According to the fourth embodiment described above, the following effects can be obtained.
(I). The effects (a) and (b) of the first embodiment are produced. Furthermore, since the two receding surfaces 430c are formed for each intermediate drive mechanism 120 only on one side of the rocker shaft 430, processing is facilitated and the rigidity of the rocker shaft 430 can be maintained high.

[Other embodiments]
(A). In each of the above embodiments, the receding surface is a flat surface, but the interval Da between the inner surfaces of the recesses of the shim is larger than the width Dc of the rocker shaft in the receding surface portion, and from the diameter Db of the cylindrical base outer peripheral surface of the rocker shaft. Therefore, it may be a curved surface such as a cylinder having a larger radius than the outer peripheral surface of the base.

  (B). In the third embodiment, as shown in FIG. 22, the pressure discharge receding surface 330d of the rocker shaft 330 is deeper than the shim disposition receding surface 330c. Conversely, the pressure exhaust receding surface 330d is replaced with the shim disposition receding surface 330c. It may be shallower.

  (C). In each of the above embodiments, an example of an engine using a cam carrier has been described. However, the present invention can also be applied to an engine in which an intermediate drive mechanism and a camshaft are arranged directly on the cylinder head body.

  The engine can be applied not only to a gasoline engine but also to a diesel engine. It can be applied not only to vehicles but also to engines for other purposes. Furthermore, it can be applied not only to the variable valve mechanism for adjusting the valve lift amount of the intake valve, but also to the variable valve mechanism for adjusting the valve lift amount of the exhaust valve, adjusting the valve lift amount of both the intake valve and the exhaust valve. It can also be applied to a variable valve mechanism for

FIG. 3 is a longitudinal cross-sectional view of the engine and variable valve mechanism of the first embodiment. The top view which shows the upper part structure of the said engine. FIG. 3 is a configuration explanatory diagram of a shim according to the first embodiment. FIG. 3 is a perspective view of a rocker shaft, a control shaft, and an intermediate drive mechanism that are used in the variable valve mechanism of the first embodiment. FIG. 3 is a partially broken perspective view of the mediation drive mechanism according to the first embodiment. FIG. 3 is an exploded perspective view of the mediation drive mechanism according to the first embodiment. FIG. 3 is a cutaway perspective view of the main body of the mediation drive mechanism according to the first embodiment. FIG. 3 is a configuration explanatory diagram of a slider gear disposed in the mediation drive mechanism of the first embodiment. FIG. 3 is a perspective view of the slider gear according to the first embodiment. FIG. 3 is a vertically broken perspective view of the slider gear according to the first embodiment. FIG. 2 is a configuration explanatory diagram of a rocker shaft and a control shaft according to the first embodiment. FIG. 3 is a partially broken perspective view of the mediation drive mechanism according to the first embodiment. FIG. 3 is an explanatory diagram of a dimensional relationship between the shim and the rocker shaft according to the first embodiment. FIG. 6 is a drive state explanatory diagram of an intermediate drive mechanism at the time of initial position adjustment in the first embodiment. FIG. 3 is an explanatory diagram of shim arrangement on the rocker shaft according to the first embodiment. FIG. 3 is an explanatory diagram illustrating an arrangement state of all shims on the rocker shaft according to the first embodiment. FIG. 3 is a diagram illustrating the arrangement and rotation state of shims on the rocker shaft according to the first embodiment. FIG. 5 is an operation explanatory diagram of the mediation drive mechanism of the first embodiment. FIG. 5 is an operation explanatory diagram of the mediation drive mechanism of the first embodiment. FIG. 4 is a configuration explanatory diagram of a rocker shaft and a control shaft according to a second embodiment. FIG. 10 is a partially broken perspective view of an intermediary drive mechanism according to a second embodiment. FIG. 5 is a configuration explanatory diagram of a rocker shaft and a control shaft according to a third embodiment. FIG. 10 is a partially broken perspective view of an intermediary drive mechanism according to a third embodiment. FIG. 6 is a configuration explanatory diagram of a rocker shaft and a control shaft according to a fourth embodiment. FIG. 6 is an explanatory diagram of a dimensional relationship between a shim and a rocker shaft according to a fourth embodiment. FIG. 10 is a diagram for explaining the arrangement and rotation state of shims on the rocker shaft according to the fourth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Engine, 2a ... Cylinder, 4 ... Cylinder block, 6 ... Piston, 8 ... Cylinder head, 10 ... Combustion chamber, 12 ... Intake valve, 14 ... Intake port, 16 ... Exhaust valve, 18 ... Exhaust port, 45 ... Intake Camshaft, 45a ... intake cam, 46 ... exhaust camshaft, 46a ... exhaust cam, 47 ... timing chain, 49 ... crankshaft, 52 ... roller rocker arm, 52a ... rocker roller, 54 ... roller rocker arm, 100 ... slide actuator 120 ... Intermediate drive mechanism, 122 ... Input section, 122a ... Housing, 122b ... Helical spline, 122c, 122d ... Arm, 122e ... Shaft, 122f ... Roller, 124 ... First swing cam, 124a ... Housing, 124b ... Helical Spline, 124c ... bearing portion, 12 d ... Nose, 124e ... Cam surface, 124f ... Bearing hole, 126 ... Second swing cam, 126a ... Housing, 126b ... Helical spline, 126c ... Bearing portion, 126d ... Nose, 126e ... Cam surface, 126f ... Bearing hole, 128 ... Slider gear, 128a ... Input helical spline, 128b ... Small diameter portion, 128c ... First output helical spline, 128d ... Small diameter portion, 128e ... Second output helical spline, 128f ... Through hole, 128g ... Circumferential groove, 128h ... pin insertion hole, 129 ... spring, 130 ... rocker shaft, 130a ... long hole, 130b ... internal space, 130c ... retracted surface, 130d ... base outer peripheral surface, 130e ... gap, 132 ... control shaft, 132a ... control pin, 132b ... support hole, 140, 142 ... valve tie 150, cam carrier, 152 ... cam cap, 154 ... front side wall, 156, 158, 160 ... side wall, 162 ... bearing, 164 ... shim, 164a ... base, 164b ... pickup, 164c ... recess, 164d ... Inner surface, 164f ... Gap, 210 ... Ball screw mechanism, 220 ... Intermediate drive mechanism, 224,226 ... Oscillating cam, 224g, 226g ... Through hole, 230 ... Rocker shaft, 230b ... Internal space, 230c ... Backward surface, 230d ... Base Outer peripheral surface, 330 ... Rocker shaft, 330b ... Internal space, 330c ... Retreat surface for shim arrangement, 330d ... Retreat surface for pressure discharge, 330e ... Outer surface of base, 430 ... Rocker shaft, 430a ... Long hole, 430b ... Internal space, 430c ... retreat surface, 430d ... base outer peripheral surface, 430e ... gap, 464 ... shim, 464c ... concave portion, 464d ... inner surface, p1, p2 ... pivot.

Claims (7)

A control shaft that changes the valve characteristic adjustment amount of the internal combustion engine by the valve characteristic adjustment mechanism by being moved in the axial direction by an actuator, and a rocker shaft that is arranged coaxially with the control shaft and supports the valve characteristic adjustment mechanism. A reference wall portion for setting a reference position of the main body of the valve characteristic adjusting mechanism by preventing the main body of the valve characteristic adjusting mechanism from following the axial movement of the control shaft, and the reference wall portion and the valve characteristic A variable valve mechanism for an internal combustion engine comprising a shim that is disposed between a main body of the adjusting mechanism and that absorbs a clearance between the main body of the valve characteristic adjusting mechanism arranged at a reference position and the reference wall. There,
The rocker shaft forms a retraction plane only a portion in the circumferential direction of the outer peripheral surface is retracted to the center axis side from the cylindrical base outer peripheral surface at the location of front alkoxy arm,
The shim forms a recess for accommodating the rocker shaft at the position of the receding surface, and the interval between two opposing inner surfaces in the recess is larger than the width of the rocker shaft on the receding surface, and the rocker shaft A variable valve mechanism for an internal combustion engine, wherein the variable valve mechanism is set to be smaller than a diameter of a cylindrical base outer peripheral surface. 2. The variable valve mechanism for an internal combustion engine according to claim 1, wherein the receding surface is formed as a flat surface. 3. The variable valve mechanism for an internal combustion engine according to claim 1, wherein two receding surfaces are provided at opposing positions in the circumferential direction of the outer peripheral surface of the rocker shaft. 4. The variable valve mechanism for an internal combustion engine according to claim 3, wherein the receding surface is two parallel planes. 5. The variable valve mechanism for an internal combustion engine according to claim 1, wherein two opposing inner surfaces of the shim recess are two parallel planes. The valve characteristic adjusting mechanism according to any one of claims 1 to 5, wherein the valve gear adjusting mechanism is engaged by helical spline engagement between the main body and the slider gear when the slider gear is moved in the axial direction by the control shaft in the main body. As the valve characteristic adjustment amount is changed,
The variable valve mechanism for an internal combustion engine, wherein the receding surface is formed in the axial direction from at least the shim arrangement position to the internal space of the main body. The valve characteristic adjusting mechanism according to any one of claims 1 to 5, wherein the valve gear adjusting mechanism is engaged by helical spline engagement between the main body and the slider gear when the slider gear is moved in the axial direction by the control shaft in the main body. As the valve characteristic adjustment amount is changed,
A second receding surface formed such that a part of the outer peripheral surface of the rocker shaft in the circumferential direction recedes from the cylindrical base outer peripheral surface toward the central axis side is continuous with the receding surface of the main body. A variable valve mechanism for an internal combustion engine, wherein the variable valve mechanism is formed over an internal space.

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