JP2006097566A - Variable valve system for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce friction force acting on an outer surface of a bushing and inner surface of a groove at a time of rotation of a slider accompanying rock of an input arm and an output arm. <P>SOLUTION: A thrust bearing 47 is provided between the outer surface 35a of the bushing and the inner surface 34a of the groove 34 in the slider 26 rotating with accompanying rock of the input arm 17 and the output arm 18. Consequently, friction force acting between the outer surface 35a and the inner surface 34a can be reduced by the thrust bearing 47 when the outer surface 35a and the inner surface 34a relatively move in a circumference direction with accompanying rotation of the slider 26. The friction force tends to increase based on action of load F acting in an axial direction as reaction force thereof at a time of lift of an intake valve by rock of the output arm 18. But the friction force can be appropriately reduced by the thrust bearing 47. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a variable valve mechanism for an internal combustion engine.

  In an internal combustion engine such as an automobile engine, the maximum lift amount of an engine valve and the operating angle of a cam that drives the valve can be made variable in order to optimize drivability and fuel consumption over the entire engine operating range. There has been proposed a variable valve mechanism that drives the mechanism in accordance with the engine operating state (see Patent Document 1).

  Such a variable valve mechanism includes an input arm that is pushed by a rotating cam and swings about a shaft, and an output arm that swings about the shaft based on the swing of the input arm and lifts the engine valve. The maximum lift amount and the operating angle are made variable by changing the relative positions of the input arm and the output arm in the swing direction around the axis. Here, a structure for changing the relative position in the swing direction of the input arm and the output arm in the variable valve mechanism will be described.

  The variable valve mechanism is provided with a cylindrical slider that is fitted on the outer peripheral surface of the shaft that becomes the swing center of the input arm and the output arm. This slider is in a state of penetrating the input arm and the output arm, and these arms are connected to the slider by gears having different inclination directions of the teeth. A control shaft is inserted into the slider. A pin protrudes from the outer peripheral surface of the control shaft and is inserted into a groove formed so as to extend in the circumferential direction of the slider, thereby connecting the control shaft and the slider. Then, the relative position of the input arm and the output arm in the swinging direction is changed by moving the control shaft together with the slider in the axial direction.

  By the way, when the control shaft is moved in the axial direction so as to change the relative position of the input arm and the output arm in the swing direction, the outer peripheral surface of the pin on the shaft is pressed against the inner surface of the groove in the slider. The slider moves in the axial direction together with the control shaft. Further, when the input arm and the output arm swing, the slider also tries to rotate in the same direction as the above-mentioned swinging direction. However, the rotation of the slider causes the groove to move in the circumferential direction of the control shaft with respect to the pin. Allowed by relative movement. At this time, the outer peripheral surface of the pin and the inner surface of the groove slide.

The pin is inserted into the groove at the tip of the pin so that the pin is pressed against the groove along the axial movement of the control shaft as described above, and the relative movement between the pin and the groove along with the swing of each arm is performed stably. It is conceivable to provide a bush to be fitted. In this case, it is possible to bring the outer side surfaces of the bush on both sides in the axial direction of the control shaft into surface contact with the inner side surfaces of the grooves. Therefore, when the pin is pressed against the groove, the force at that time is received by the entire contact surface between the outer surface of the bush and the inner surface of the groove, and the pressing can be performed stably. Further, during the relative movement between the pin and the groove, the outer surface of the bush and the inner surface of the groove are slid in a surface contact state, and the relative movement can be performed stably.
JP 2001-263015 A

  By the way, the movement of the slider in the axial direction for changing the relative position of the input arm and the output arm in the swinging direction is performed under the condition that the slider rotates in the circumferential direction as the arms swing. Therefore, when the contact surface between the outer surface of the bush and the inner surface of the groove slides due to the rotation, it is greatly influenced by the frictional force acting on the contact surface. Therefore, when this frictional force becomes large, the slider moves in the axial direction, which may increase the driving force required to move the slider in the axial direction.

  The present invention has been made in view of such circumstances, and the object thereof is to work between the outer surface of the bush and the inner surface of the groove when the slider is rotated along with the swing of the input arm and the output arm. An object of the present invention is to provide a variable valve mechanism for an internal combustion engine that can reduce the frictional force.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, an input arm that is pushed by a rotating cam and swings about an axis, and swings about the axis based on the swing of the input arm. And an output arm that lifts the engine valve. The arms are connected to the slider by gears having different inclination directions of the teeth, and the control shaft inserted in the slider is moved in the axial direction while being connected to the slider. Thus, in a variable valve mechanism for an internal combustion engine that changes the relative position of the input arm and the output arm in the swinging direction and makes the valve characteristic of the engine valve variable, the slider has a shaft periphery. Bush provided at the tip of the pin that protrudes from the outer peripheral surface of the control shaft in the groove while forming a groove extending in the direction Inserted, is provided a thrust bearing between the outer surface of the opposing said bushing and the inner surface of the groove.

  When the slider rotates with the swing of the input arm and the output arm, the outer surface of the opposing bush and the inner surface of the groove move relative to each other in the circumferential direction. However, according to the above configuration, the frictional force generated between the outer surface of the bush and the inner surface of the groove can be reduced by the thrust bearing provided between the outer surface and the inner surface. .

  According to a second aspect of the present invention, in the first aspect of the invention, the thrust bearing is subjected to an axial load when the engine valve is lifted at least among the outer surfaces on both axial sides of the bush. The gist is that it is provided on the outer surface side.

  When the engine valve lifts due to the swinging of the input arm and output arm, the reaction force at that time is transmitted from the engine valve to the slider via the output arm, and a load is applied to the slider on one side in the axial direction. Become. Based on the action of this load, one inner surface of the groove is pushed toward the outer surface facing the inner surface in the bush, and the frictional force between the outer surface and the inner surface is equal to the load. There is a risk that it will become even larger. However, according to the above configuration, since the thrust bearing is provided on the outer side of the bush on the outer side on both sides in the axial direction, the frictional force is increased as described above. It can be accurately suppressed.

  According to a third aspect of the invention, in the first or second aspect of the invention, the slider includes a plurality of structures divided in the axial direction with the groove portion as a boundary, and the structures are assembled in the axial direction. The gist is that it is formed.

  According to the above configuration, when the bearing, the bush, and the like are assembled in the groove of the slider, the slider can be divided into a plurality of structures and the groove can be opened to the outside. Then, the thrust bearings and the bushes are disposed in the grooves that are open to the outside, and the plurality of structures are assembled to each other, whereby the thrust bearings and the bushes are assembled in the grooves of the slider. As described above, since the thrust bearing and the bush can be easily arranged in the groove of the slider, the assembling property of the thrust bearing and the bush to the slider is improved.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the slider includes a first structure including an input gear that meshes with an internal gear formed on an inner wall of the input arm, and an inner wall of the output arm. A shim for adjusting a relative position in the axial direction between the input arm and the output arm. The shim includes an output gear that meshes with the formed internal gear. The gist is that it is provided.

  When the first structure and the second structure are assembled to each other, if the relative positions in the circumferential direction and the axial direction are not appropriate, the relative position in the swing direction between the input arm and the output arm is Deviates from the proper state. The relative positions of these arms in the swing direction change in correspondence with the relative positions of the arms in the axial direction. For this reason, the shim between the input arm and the output arm is appropriately replaced with one having a different thickness, and the relative position of the arm in the axial direction is adjusted so that the relative position of the arm in the swinging direction is adjusted. It becomes possible to adjust. Therefore, even if the relative positions in the circumferential direction and the axial direction of both the first structure and the second structure are deviated from the proper state when the first structure and the second structure are assembled, the relative relationship in the axial direction between the input arm and the output arm due to the shim. By adjusting the positions, the relative positions of the arms in the swing direction can be adjusted to an appropriate state.

Hereinafter, a first embodiment in which the present invention is embodied in a variable valve mechanism for an automobile engine will be described with reference to FIGS.
FIG. 1 is an enlarged cross-sectional view showing a structure around a cylinder head 2 of the engine 1. In the engine 1, a combustion chamber 6 is defined by a cylinder head 2, a cylinder block 3, and a piston 5, and an intake passage 7 and an exhaust passage 8 are connected to the combustion chamber 6. The intake passage 7 and the combustion chamber 6 are communicated and blocked by the opening / closing operation of the intake valve 9, and the exhaust passage 8 and the combustion chamber 6 are communicated and blocked by the opening / closing operation of the exhaust valve 10. Become.

  The cylinder head 2 is provided with an intake camshaft 11 and an exhaust camshaft 12 for driving the intake valve 9 and the exhaust valve 10. The intake camshaft 11 and the exhaust camshaft 12 are rotated by transmission of rotation from the crankshaft of the engine 1. The intake camshaft 11 and the exhaust camshaft 12 are provided with an intake cam 11a and an exhaust cam 12a, respectively. The intake valve 9 and the exhaust valve 10 are opened and closed through integral rotation of the intake cam shaft 11 and the exhaust cam shaft 12 of the intake cam 11a and the exhaust cam 12a.

  Further, the engine 1 is provided with a variable valve mechanism that varies the valve characteristics of the engine valves such as the intake valve 9 and the exhaust valve 10. As one of such variable valve mechanisms, a lift amount variable mechanism 14 is provided between the intake cam 11a and the intake valve 9 to vary the maximum lift amount of the valve 9 and the operating angle of the intake cam 11a. . Through the driving of the variable lift amount mechanism 14, for example, the maximum lift amount and the operating angle are controlled to be larger as the engine operation state that requires a larger intake air amount is reached. This is because the larger the maximum lift amount and the operating angle, the more efficiently the air is sucked into the combustion chamber 6 from the intake passage 7 and the above-described requirements regarding the intake air amount can be satisfied.

Next, the detailed structure of the lift amount variable mechanism 14 will be described.
The variable lift amount mechanism 14 includes a rocker shaft 15 and a control shaft 16 that extend in parallel with the intake camshaft 11, an input arm 17 that is pushed by the rotating intake cam 11a and swings about the rocker shaft 15, and this input. An output arm 18 that swings about the rocker shaft 15 based on the swing of the arm 17 is provided. The input arm 17 is rotatably attached to a roller 19 and is biased toward the intake cam 11a by a coil spring 20 so that the roller 19 is pressed against the intake cam 11a. Further, the output arm 18 is pressed against the rocker arm 21 when the output arm 18 swings, and the intake valve 9 is lifted through the rocker arm 21.

  One end of the rocker arm 21 is supported by the lash adjuster 22, and the other end of the rocker arm 21 is in contact with the intake valve 9. The rocker arm 21 is urged toward the output arm 18 by the valve spring 24 of the intake valve 9, whereby a roller 23 rotatably supported between one end and the other end of the rocker arm 21 is applied to the output arm 18. It is pressed.

  Therefore, when the input arm 17 and the output arm 18 swing based on the rotation of the intake cam 11a, the output arm 18 lifts the intake valve 9 via the rocker arm 21, and the intake valve 9 is opened and closed. In the variable lift amount mechanism 14, the maximum lift amount of the intake valve 9 and the action of the intake cam 11a on the intake valve 9 are changed by changing the relative positions of the input arm 17 and the output arm 18 in the swing direction. The corner is variable. That is, as the input arm 17 and the output arm 18 are brought closer to each other in the swing direction, the maximum lift amount of the intake valve 9 and the operating angle of the intake cam 11a become smaller. Conversely, as the input arm 17 and the output arm 18 are separated from each other in the swinging direction, the maximum lift amount of the intake valve 9 and the operating angle of the intake cam 11a increase.

  Here, a structure for changing the relative position in the swing direction of the input arm 17 and the output arm 18 in the lift amount varying mechanism 14 will be described in detail with reference to FIGS.

  FIG. 2 is a cutaway perspective view showing the internal structure of the variable lift amount mechanism 14, specifically the internal structure of the input arm 17 and the output arm 18 attached to the rocker shaft 15. As shown in the figure, the rocker shaft 15 passes through the input arm 17 and the output arm 18. Further, a cylindrical slider 26 is fitted into a portion corresponding to the input arm 17 and the output arm 18 on the outer peripheral surface of the rocker shaft 15. On the outer wall of the slider 26, an input gear 27a having a helical spline 27 is provided at the longitudinal center, and an output gear 29a having a helical spline 29 is provided at both longitudinal ends.

  On the other hand, as shown in FIG. 3, an annular inner gear 28 a having a helical spline 28 is formed on the inner wall of the input arm 17, and an annular inner tooth having a helical spline 30 is formed on the inner wall of the output arm 18. A gear 30a is formed. The internal gear 28a of the input arm 17 is meshed with the input gear 27a (FIG. 2) of the slider 26, and the internal gear 30a of the output arm 18 is meshed with the output gear 29a (FIG. 2) of the slider 26. The helical splines 27 and 28 and the helical splines 29 and 30 have different inclination angles, for example, the inclination directions of the tooth traces are opposite to each other.

  The rocker shaft 15 is formed in a cylindrical shape, and a control shaft 16 connected to the slider 26 by a pin is inserted inside the rocker shaft 15. When the control shaft 16 is moved in the axial direction together with the slider 26, the relative positions of the input arm 17 and the output arm 18 in the swinging direction are changed by the meshing of the helical splines 27, 29 and the helical splines 28, 30. The

  Specifically, as the control shaft 16 is displaced in the arrow L direction, the relative positions of the input arm 17 and the output arm 18 in the swing direction are changed so as to approach each other, and the control shaft 16 is displaced in the arrow H direction. The relative positions are changed so as to be separated from each other as the distance is increased. Through the change of the relative position of the input arm 17 and the output arm 18 in the swing direction, the maximum lift amount of the intake valve 9 and the working angle of the intake cam 11a when the output arm 18 swings due to the rotation of the intake cam 11a. Is variable. The displacement in the axial direction of the control shaft 16 as described above is realized by, for example, drive control of an actuator using an electric motor.

  Next, a structure for mounting the input arm 17, the output arm 18, the slider 26, the rocker shaft 15, the control shaft 16 and the like in the lift amount variable mechanism 14 to the cylinder head 2, and a structure for connecting the slider 26 and the control shaft 16. Will be described with reference to FIG.

  As shown in the figure, the rocker shaft 15 and the control shaft 16 pass through the standing wall 45 of the cylinder head 2 and through the arms 17 and 18 sandwiched between the two standing walls 45. Yes. Of the arms 17 and 18, the input arm 17 is sandwiched between two output arms 18. A slider 26 fitted to the rocker shaft 15 is positioned inside each arm 17, 18. An input gear 27 a and an output gear 29 a of the slider 26, and an internal gear 28 a and an output arm of the input arm 17. The 18 internal gears 30a mesh with each other.

  Further, a shim 46 for adjusting the axial positions of the input arm 17 and the output arm 18 is provided between the standing wall 45 and the output arm 18. The axial positions of the input arm 17 and the output arm 18 have a great influence on the change of the maximum lift and the operating angle with respect to the displacement of the slider 26 in the axial direction. For this reason, the axial positions of the input arm 17 and the output arm 18 are adjusted to be appropriate positions by appropriately replacing the shims 46 with different thicknesses.

  A pin 51 for connecting the shaft 16 and the slider 26 is inserted in the control shaft 16 in the radial direction. Further, at a position corresponding to the pin 51 on the rocker shaft 15, an elongated hole 33 extending in the axial direction and through which the pin 51 passes is formed. Further, a groove 34 is formed at a position corresponding to the pin 51 on the inner peripheral surface of the slider 26 so as to extend in the circumferential direction (a direction orthogonal to the paper surface in the drawing) and into which the tip of the pin 51 is inserted. A bush 35 is provided at the tip of the pin 51 located in the groove 34. Outer surfaces 35a and 35b on both sides in the axial direction of the bush 35 are opposed to inner surfaces 34a and 34b of the groove 34, respectively.

  The axial movement of the control shaft 16 is allowed through movement of the pin 31 along the elongated hole 33. When the pin 51 moves along the elongated hole 33 as the control shaft 16 moves in the axial direction, one of the outer surfaces 35a and 35b on both sides in the axial direction of the control shaft 16 in the bush 35 is the inner side surface 34a ( Or the slider 26 is moved in the axial direction of the control shaft 16. Further, when the input arm 17 and the output arm 18 swing, the slider 26 is displaced (rotated) in the circumferential direction with respect to the outer peripheral surface of the rocker shaft 15. Allowed by grooves 34 that move relative to each other.

  Incidentally, the movement of the slider 26 in the axial direction is performed under the condition that the slider 26 is rotated in the circumferential direction as the input arm 17 and the output arm 18 are swung. When a frictional force acts between the side surfaces 35a and 35b and the inner side surfaces 34a and 34b of the groove 34, the frictional force is greatly affected. If this frictional force becomes large, the movement of the slider 26 in the axial direction is hindered, and the driving force required to move the slider 26 in the axial direction may increase.

  In particular, the frictional force increases between the outer side surface 35a of the bush 35 and the inner side surface 34a of the groove 34, which may lead to the problems described above. This is because when the intake valve 9 is lifted by the swinging of the input arm 17 and the output arm 18, the reaction force at that time is transmitted from the intake valve 9 to the slider 26 via the output arm 18. This is because a load F is applied to one side (in the direction of arrow F in FIG. 4). That is, when such a load F is applied, the inner side surface 34a is pushed toward the outer side surface 35a, and the frictional force acting between the two becomes large, and the above-described problem is likely to occur.

  Therefore, in this embodiment, the thrust bearing 47 is provided between the outer side surface 35a and the inner side surface 34a facing each other, in other words, on the outer side surface 35a side in the groove 34. When the outer surface 35a and the inner side surface 34a move relative to each other in the circumferential direction when the slider 26 rotates, the friction force acting between the outer surface 35a and the inner side surface 34a is reduced by the thrust bearing 47. I have to. For this reason, even if the frictional force tends to increase based on the action of the load F, the frictional force is accurately reduced by the thrust bearing 47 and causes the above-mentioned problem due to the frictional force. Can be suppressed.

The thrust bearing 47 is preferably a rolling bearing such as a ball bearing or a roller bearing in order to reduce the frictional force.
Next, the detailed structure of the slider 26 provided with the thrust bearing 47 will be described.

  The slider 26 includes a plurality of structures divided in the axial direction with the groove 34 as a boundary, more specifically, a first structure 26a and a second structure 26b. The structures 26a and 26b are arranged in the axial direction. It is formed by assembling. The first structure 26a includes an input gear 27a that meshes with the internal gear 28a of the input arm 17, and an output gear 29a that meshes with the internal gear 30a of the left output arm 18 in the drawing. The second structure 26b includes an output gear 29a that meshes with the internal gear 30a of the output arm 18 on the right side in the drawing.

FIG. 5 is a cross-sectional view showing a state in which the slider 26 is divided into a first structure 26a and a second structure 26b.
As shown in the figure, the first structure 26 a and the second structure 26 b are formed in a cylindrical shape that is fitted into the outer peripheral surface of the rocker shaft 15. In the first structure 26a, the inner diameter of the portion near the input gear 27a is larger than the inner diameter of the portion near the output gear 29a, and the inner peripheral surface of the portion near the input gear 27a and the outer peripheral surface of the rocker shaft 15 are increased. A space 48 is formed between them. In this space portion 48, the wall surface 48a near the output gear 29a is formed on the inner side surface 34a of the groove 34 when the first structure 26a and the second structure 26b are assembled together to form the slider 26 (see FIG. 4). It becomes. Further, in the second structure 26b, a portion facing the space portion 48 in the drawing has a small diameter portion having an outer diameter smaller than the outer diameter of the other portion and substantially equal to the inner diameter of the space portion 48. 49 is formed. The wall surface 49a on the distal end side of the small diameter portion 49 becomes the inner side surface 34b (see FIG. 4) of the groove 34 when the first structure 26a and the second structure 26b are assembled together to form the slider 26.

  Incidentally, the formation of the slider 26 by assembling the first structure 26a and the second structure 26b, and the assembly of the thrust bearing 47 and the bush 35 to the slider 26 are as described in [1] to [4] below. The procedure shown is done.

  [1] A thrust bearing 47 is fitted on the outer peripheral surface of the rocker shaft 15, and the thrust bearing 47 is disposed on the side opposite to the direction in which the load F acts on the long hole 33 (left side in the figure).

  [2] The pin 51 is inserted in the radial direction with respect to the outer peripheral surface of the control shaft 16 so that the pin 51 penetrates the elongated hole 33. At this time, the thrust bearing 47 is positioned on the outer surface 35 a side to which the load F is applied among the outer surfaces 35 a and 35 of the bush 35 provided at the tip portion of the pin 51.

  [3] The first structure 26a and the second structure 26b are sandwiched between the bush 35 and the thrust bearing 47, and the space 48 and the small diameter portion 49 are opposed to each other. Fit on the outer periphery. In FIG. 5, the first structure 26a is arranged on the outer surface 35a side, and the second structure 26b is arranged on the outer surface 35b side. In such a state that the slider 26 is divided into the first structure 26a and the second structure 26b, the groove 34 (space portion 48) is opened toward the thrust bearing 47 and the bush 35 side.

  [4] The first structure body 26a and the second structure body 26b are moved closer to each other along the axial direction of the rocker shaft 15, and the small-diameter portion 49 of the second structure body 26b is press-fitted into the space 48 of the first structure body 26a. . Thus, the first structure 26a and the second structure 26b are assembled and fixed to each other with the thrust bearing 47 and the bush 35 interposed therebetween, and the slider 26 is formed and the thrust bearing 47 and the bush to the slider 26 are formed. Assembling of 35 is performed. At this time, the relative positions of the first structure 26a and the second structure 26b in the circumferential direction and the axial direction are fixed.

The slider 26 formed as described above is attached to the cylinder head 2 together with the input arm 17 and the output arm 18 as shown in FIG.
However, with the slider 26 formed in this way, it is difficult to maintain the high tooth accuracy of the input gear 27a and the output gear 29a. This is because when the first structure 26a and the second structure 26b are assembled to each other in [4] above, the relative positions in the circumferential direction and the axial direction of the two structures are not necessarily set to an appropriate state with high accuracy. This is because the deviation of the relative position from the proper state affects the tooth accuracy of the input gear 27a and the output gear 29a. More specifically, if the relative position deviates from the appropriate state, the positional relationship between the input gear 27a and the output gear 29a of the first structure 26a and the output gear 29a of the second structure 26b becomes inappropriate, and these gears The tooth accuracy of 27a and 29a is reduced. As the positional relationship becomes inappropriate, the input arm 17 having the internal gear 28a that meshes with the input gear 27a of the first structure 26a and the internal tooth that meshes with the output gear 29a of the second structure 26b. The relative position with respect to the swinging direction of the output arm 18 provided with the gear 30a is deviated from proper.

  In order to cope with this, in the present embodiment, the shaft of the arms 17 and 18 is provided between the input arm 17 and the output arm 18 provided with the internal gear 30a meshing with the output gear 29a of the second structure 26b. A washer shim 50 is provided for adjusting the relative position in the direction.

  The relative positions of the arms 17 and 18 with respect to the swinging direction change corresponding to the relative positions of the arms 17 and 18 with respect to the axial direction. For this reason, the washer shim 50 is appropriately replaced with one having a different thickness, and the relative position of the arms 17 and 18 in the axial direction is adjusted, so that the relative position of the arms 17 and 18 in the swinging direction is appropriately changed. It becomes possible. Therefore, even when the first structure 26a and the second structure 26b are assembled, even if the relative positions in the circumferential direction and the axial direction of the first structure 26a and the second structure 26b deviate from the proper states, the axial direction of the arms 17 and 18 by the washer shim 50 By adjusting the relative position, the relative position in the swing direction of the arms 17 and 18 can be adjusted to an appropriate state.

  Next, how to position the arms 17 and 18 in the axial direction when the slider 26, the input arm 17 and the output arm 18 are attached to the cylinder head 2 will be described below.

  Before performing the positioning, the slider 26 is fixed at, for example, the leftmost position in FIG. 4, that is, the position where the input arm 17 and the output arm 18 are closest to each other. Then, the position adjustment in the axial direction of the output arm 18 and the input arm 17 positioned on the first structure 26a side makes the shim 46 between the output arm 18 and the left wall 45 in the drawing different in thickness. It is carried out by exchanging them appropriately. Through such position adjustment, the positions of the arms 17 and 18 in the axial direction are set to appropriate positions with respect to the output gear 29a and the input gear 27a on the first structure 26a side.

  Subsequently, the relative position of the output arm 18 positioned on the second structure 26b side with respect to the input arm 17 in the axial direction is adjusted so that the washer shim 50 between the output arm 18 and the input arm 17 has a different thickness. It is performed by exchanging appropriately. Through such adjustment of the relative position, it is possible to eliminate the deviation of the relative position from the proper state in the swing direction of the arms 17 and 18. Therefore, when the first structure 26a and the second structure 26b are assembled, even if the relative positions in the circumferential direction and the axial direction of the first structure 26a and the second structure 26b deviate from the proper state, the relative positions in the swing direction of the arms 17 and 18 are. So that the relative positions of the arms 17 and 18 in the axial direction can be adjusted.

  After such adjustment, a shim having a width corresponding to the clearance between the output arm 18 and the standing wall 45 at that time is provided between the output arm 18 on the second structure 26b side and the standing wall 45 on the right side in the drawing. 46 is arranged. Thus, the positioning of the arms 17 and 18 of the slider 26 in the axial direction is completed.

According to the embodiment described in detail above, the following effects can be obtained.
(1) A thrust bearing 47 is provided between the outer side surface 35 a of the bush 35 and the inner side surface 34 a of the groove 34. Therefore, when the slider 26 rotates with the swing of the input arm 17 and the output arm 18 and the outer side surface 35a and the inner side surface 34a move relative to each other in the circumferential direction, the outer side surface 35a and the inner side surface 34a. The thrust bearing 47 can reduce the frictional force acting between the two. The friction force tends to increase based on the action of the load F, but the friction force can be accurately reduced by the thrust bearing 47. Accordingly, it is possible to prevent the slider 26 from moving in the axial direction due to the frictional force, and consequently to prevent the driving force necessary to move the slider 26 in the axial direction from increasing. .

  (2) The slider 26 includes a first structure 26a and a second structure 26b that are divided in the axial direction with the groove 34 as a boundary, and is formed by assembling the structures 26a and 26b in the axial direction. ing. The thrust bearing 47 and the bush 35 are assembled in the groove 34 of the slider 26 in a state where the slider 26 is divided into the first structure 26a and the second structure 26b. In other words, the groove 34 ( This is performed with the space 48) open. Then, the thrust bearing 47 and the bush 35 are assembled in the groove 34 by assembling the structures 26a and 26b while sandwiching the thrust bearing 47 and the bush 35 between the first structure 26a and the second structure 26b. . Thus, since the thrust bearing 47 and the bush 35 can be easily assembled, the assemblability of the thrust bearing 47 and the bush 35 into the groove 34 of the slider 26 is improved.

  (3) When the slider 26 is formed by assembling the first structure 26a and the second structure 26b to each other, if the relative positions of the structures 26a and 26b in the circumferential direction and the axial direction are not appropriate, the first structure The relative position of the input arm 17 on the side of the body 26a and the output arm 18 on the side of the second structure 26b in the swinging direction is deviated from proper. The relative positions of the arms 17 and 18 with respect to the swinging direction change corresponding to the relative positions of the arms 17 and 18 with respect to the axial direction. For this reason, the washer shim 50 between the arms 17 and 18 is appropriately replaced with one having a different thickness, and the relative position of the arms 17 and 18 in the axial direction is adjusted, so that the swing direction of the arms 17 and 18 can be adjusted. The relative position of can be adjusted. Therefore, even when the first structure 26a and the second structure 26b are assembled, even if the relative positions in the circumferential direction and the axial direction of the first structure 26a and the second structure 26b are deviated from the proper state, the axial direction of the arms 17 and 18 by the washer shim 50 is reduced. By adjusting the relative position, the relative position in the swing direction of the arms 17 and 18 can be adjusted to an appropriate state.

In addition, the said embodiment can also be changed as follows, for example.
A washer shim may be provided between the output arm 18 and the input arm 17 on the first structure 26a side so that the relative position of the arms 17 and 18 in the axial direction can be adjusted.

-You may reverse the positional relationship of the 1st structure 26a and the 2nd structure 26b.
A thrust bearing may also be provided between the outer surface 35b of the bush 35 and the inner surface 34b of the groove 34. In this case, the frictional force acting between the outer surface 35b and the inner surface 34b can be reduced.

A thrust bear rig may be provided only between the outer side surface 35b of the bush 35 and the inner side surface 34b of the groove 34 to reduce the frictional force acting between them.
A sliding bearing may be adopted as the thrust bearing 47.

  The present invention may be applied to the engine 1 having a variable valve mechanism that varies the valve characteristics of the exhaust valve 10 such as the maximum lift amount of the exhaust valve 10 and the operating angle of the exhaust cam 12a with respect to the exhaust valve 10. .

The expanded sectional view which shows the structure around the cylinder head of the engine to which the variable valve mechanism of this embodiment was applied. The fracture | rupture perspective view which shows the internal structure of a lift amount variable mechanism. The broken perspective view which shows the internal structure of an input arm and an output arm. Sectional drawing which shows the attachment structure to the cylinder head of a slider, an input arm, and an output arm. Sectional drawing which shows the state which divided | segmented the slider into the 1st structure and the 2nd structure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Cylinder head, 3 ... Cylinder block, 5 ... Piston, 6 ... Combustion chamber, 7 ... Intake passage, 8 ... Exhaust passage, 9 ... Intake valve, 10 ... Exhaust valve, 11 ... Intake camshaft, 11a DESCRIPTION OF SYMBOLS ... Intake cam, 12 ... Exhaust cam shaft, 12a ... Exhaust cam, 14 ... Lift amount variable mechanism, 15 ... Rocker shaft, 16 ... Control shaft, 17 ... Input arm, 18 ... Output arm, 19 ... Roller, 20 ... Coil spring , 21 ... Rocker arm, 22 ... Rush adjuster, 23 ... Roller, 24 ... Valve spring, 26 ... Slider, 26a ... First structure, 26b ... Second structure, 27 ... Helical spline, 27a ... Input gear, 28 ... Helical Spline, 28a ... Internal gear, 29 ... Helical spline, 29a ... Output gear, 30 ... Helical sp Inn, 30a ... Internal gear, 33 ... Slot, 34 ... Groove, 34a, 34b ... Inner side, 35 ... Bush, 35a, 35b ... Outer side, 45 ... Standing wall, 46 ... Shim, 47 ... Thrust bearing, 48 ... space part, 48a ... wall surface, 49 ... small diameter part, 49a ... wall surface, 50 ... washer shim, 51 ... pin.

Claims (4)

An input arm that is pushed by a rotating cam and swings about an axis, and an output arm that swings about the axis based on the swing of the input arm and lifts the engine valve, and each of the arms The sliders are connected to each other by gears having different inclination directions of the tooth traces, and the control shaft inserted in the slider is moved in the axial direction while being connected to the slider, thereby swinging the input arm and the output arm. In a variable valve mechanism for an internal combustion engine that changes the relative position in the direction and makes the valve characteristic of the engine valve variable,
A groove extending in the circumferential direction of the shaft is formed in the slider, and a bush provided at a tip portion of a pin protruding from the outer peripheral surface of the control shaft is inserted into the groove, and the outer surface of the opposing bush and the A variable valve mechanism for an internal combustion engine, characterized in that a thrust bearing is provided between the inner surface of the groove. 2. The internal combustion engine according to claim 1, wherein the thrust bearing is provided on at least an outer side surface of the bush that is applied with an axial load when the engine valve is lifted. Variable valve mechanism of the engine. 3. The variable motion of the internal combustion engine according to claim 1, wherein the slider includes a plurality of structures divided in the axial direction with the groove portion as a boundary, and is formed by assembling the structures in the axial direction. Valve mechanism. The slider has a first structure including an input gear meshing with an internal gear formed on an inner wall of the input arm, and a second structure including an output gear meshing with an internal gear formed on the inner wall of the output arm. And consists of
The variable valve mechanism for an internal combustion engine according to claim 3, wherein a shim is provided between the input arm and the output arm for adjusting a relative position between the input arm and the output arm.

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