JP2006112279A - Variable valve train for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable valve train for an internal combustion engine suppressing increase of number of parts of the internal combustion engine and drop of efficiency of assembly work of the engine. <P>SOLUTION: A shim 46 for absorbing clearance and adjusting position of arms 17, 18 in an axial direction is arranged between an output arm 18 and a cam cap 43 (vertical wall part 45) of a lift variable mechanism 14. The shim 46 is supported on a rocker shaft 15 of the mechanism 14. A projection 64 regulating rotation of the shim 46 around the rocker shaft 15 is formed on the cam cap 43 adjoining the shim 46 as one unit and is commonized with the cam cap 43. Consequently, the projection 64 which is a part for regulating rotation is simultaneously attached to a cam carrier by attaching the cam cap 43 to the cam carrier. <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, a variable valve that makes the maximum lift amount of an engine valve and the operating angle of a cam that drives the valve variable so that optimum intake characteristics can be obtained over the entire engine operating range. A mechanism that includes a mechanism and drives the mechanism in accordance with the engine operating state has been proposed (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. And a cylindrical slider fitted on the outer peripheral surface of the shaft that becomes the swing center of the arms. 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. When the slider is moved in the axial direction, the relative position of the input arm and the swing arm in the swinging direction is changed by the action of the gear, and the maximum lift amount and the operating angle are changed.

  In the variable valve mechanism, the shaft is supported by a plurality of standing wall portions arranged in parallel with the cylinder head, and the input arm and the output arm are disposed between the standing wall portions. A shim is provided between the arm and the standing wall. This shim is used as follows to absorb the clearance between the arm and the standing wall and adjust the axial position of each arm.

  The input arm and the output arm are adjusted so that the axial position becomes the reference position after being assembled to the cylinder head. After this adjustment, a clearance is generated between the arm and the standing wall. For this reason, a shim having a thickness corresponding to the clearance is selected and disposed between the arm and the standing wall portion so that the clearance is absorbed by the shim. Further, after adjusting the input arm and the output arm to the reference position, there is a case where it is desired to further finely adjust the axial positions of the arms in order to make the valve lift characteristics of the engine valve appropriate. Such fine adjustment is performed by appropriately replacing the shim with one having a different thickness.

By the way, as described above, after the shim having an appropriate thickness is disposed between the arm and the standing wall portion, it is necessary to prevent the shim from dropping out between them.
In order to avoid such dropout, it is conceivable to apply the technique disclosed in Patent Document 2 to the shim, that is, the technique for preventing the member from coming off from the shaft, so that the shim has a snap ring shape. However, when the shim is a snap ring type, when the shim is appropriately replaced with one having a different thickness in order to absorb the clearance and adjust the axial position of each arm, the shim is attached to and detached from the shaft. This causes inconvenience that work becomes difficult and workability decreases.

Therefore, it is conceivable that the shim between the arm and the standing wall portion is supported on the shaft, and a regulating member for regulating the rotation of the shim in that state around the shaft is separately attached. In this case, it is possible to easily replace the shim in a state in which the regulating member is not attached. First, the shim is appropriately replaced in that state, and an optimum thickness is selected. Then, the selected shim is arranged between the arm and the standing wall portion, a restricting member is attached, and the rotation of the shim around the shaft is restricted, thereby preventing the shim from dropping from the shaft.
JP 2001-263015 A JP-A-10-121916

  As described above, if a restricting member for restricting the rotation of the shim around the shaft is separately attached, the shim can be easily replaced while the shim can be prevented from falling off the shaft. However, by providing the restriction member separately, the number of parts of the whole internal combustion engine increases, and the number of work steps increases by the work of attaching the restriction member in the assembly work of the internal combustion engine. As a result, the efficiency of the assembly operation of the internal combustion engine is reduced, and there is a possibility that the cost of the engine is increased.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a variable motion of an internal combustion engine that can suppress an increase in the number of parts of the internal combustion engine and a decrease in efficiency of assembly work of the engine. It is to provide a valve mechanism.

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. An output arm that lifts the engine valve; and a slider that is connected to the input arm and the output arm through gears having different inclination directions of the tooth traces and is capable of reciprocating in the axial direction. In a variable valve mechanism for an internal combustion engine in which a shim is provided between a standing wall portion that supports a shaft, the shim is supported on the shaft, and is used for restricting rotation about the shaft. The engaging portion that engages with the engaged portion and restricts the rotation of the shim is made common with existing parts around the shim.

  According to the above configuration, since the existing parts around the shim and the engaging part are shared, an increase in the number of parts of the internal combustion engine can be suppressed. Furthermore, by attaching the existing parts to the internal combustion engine, the engagement portion is also attached to the internal combustion engine at the same time. For this reason, even if it provides the said engaging part, the work man-hour of the assembly operation of an internal combustion engine does not increase, and it can suppress that the efficiency of the said assembly operation falls with the increase in the work man-hour.

  In the invention according to claim 2, in the invention according to claim 1, the engaged portion of the shim is a non-arc-shaped engaged surface formed on a radially outer side of the shaft in the shim, The engaging portion is formed so as to protrude from the shim-side surface of the cam cap that forms the standing wall portion, and the engaged surface is rotated when the surface facing the engaged surface is rotated about the shaft of the shim. The gist of the present invention is that the protrusion has a shape that hooks with the surface.

  According to the above configuration, when the shim disposed between the arm and the standing wall portion tries to rotate around the axis, the engaged surface of the shim forms the protruding portion of the cam cap (more specifically, the facing surface). ) And the rotation of the shim is restricted. In this way, since the protrusion that restricts the rotation of the shim is formed on the cam cap and is shared with the cam cap, the number of parts of the internal combustion engine does not increase by the amount of the protrusion. . Further, by attaching the cam cap to the internal combustion engine, the protrusion is also attached to the internal combustion engine at the same time. For this reason, even if the protrusion is provided, the number of work steps for the assembly operation of the internal combustion engine does not increase, and it is possible to suppress a decrease in the efficiency of the assembly work as the number of work steps increases.

The invention according to claim 3 is the invention according to claim 2, wherein the engaged surface is formed in a flat shape, and the opposing surface facing the engaged surface is also formed in a flat shape. It was.
According to the above configuration, when the shim tries to rotate around the axis, the planar engaged surface is also in contact with the planar opposing surface (protrusion) and is locked, so that the rotation of the shim is restricted. The rotation regulation can be performed more reliably. In addition, when the shim is attached to and detached from the arm and the standing wall for exchanging the shim, the engaged surface which is a plane parallel to each other and the opposing surface are not easily caught, so the shim can be easily attached and detached. be able to.

  According to a fourth aspect of the present invention, in the invention according to the second or third aspect, the engaged surface is formed so as to be parallel to each other on both sides of the shim in a horizontal direction perpendicular to the axis. The protrusions of the cap are arranged on the radially outer side of one engaged surface and the radially outer side of the other engaged surface so as to sandwich the two engaged surfaces from both radial sides of the shaft. The gist of the present invention is that each of the two protrusions facing each of the engaged surfaces is formed to be parallel to each other so as to correspond to the engaged surface.

  According to the above configuration, when the shim tries to rotate around the axis, the two engaged surfaces of the shim are respectively caught on the corresponding opposing surfaces, so that the rotation of the shim can be more reliably restricted. .

  According to a fifth aspect of the invention, in the first aspect of the invention, the engaged portion of the shim is a protrusion protruding from the shim toward the radially outer side of the shaft, and the engaging portion is It is integrally formed in a case of a lost motion mechanism that urges the input arm in the valve closing direction of the engine valve, and is a clamping part that sandwiches the protrusion from both sides in the circumferential direction of the shaft when the case is assembled to the internal combustion engine. The summary.

  According to the above configuration, when the shim disposed between the arm and the standing wall portion rotates about the axis, the protrusion of the shim is caught by the holding portion integrally formed with the case of the lost motion mechanism, and the rotation of the shim Is regulated. Since the sandwiching portion that restricts the rotation of the shim is shared with the case of the lost motion mechanism, the number of parts of the internal combustion engine does not increase by the amount of the sandwiching portion provided. Further, by attaching the case of the lost motion mechanism to the internal combustion engine, the clamping portion is also attached to the internal combustion engine at the same time. For this reason, even if it provides the said clamping part, the operation man-hour of the assembly operation of an internal combustion engine does not increase, and it can suppress that the efficiency of the said assembly operation falls with the increase in the operation man-hour.

  According to a sixth aspect of the invention, in the first aspect of the invention, the engaged portion of the shim is a protrusion protruding from the shim toward the radially outer side of the shaft, and the engaging portion is The gist of the present invention is that it is formed integrally with the head cover of the internal combustion engine, and is a clamping portion that sandwiches the protrusion from both sides in the circumferential direction of the shaft when the head cover is assembled to the cylinder head.

  According to the above configuration, when the shim disposed between the arm and the standing wall portion rotates about the axis, the projection of the shim is caught by the clamping portion formed integrally with the head cover of the internal combustion engine, and the rotation of the shim is performed. Be regulated. Since the sandwiching portion that restricts the rotation of the shim is shared with the head cover, the number of parts of the internal combustion engine does not increase by the amount of the sandwiching portion provided. Furthermore, by attaching the head cover to the internal combustion engine (cylinder head), the clamping portion is also attached to the internal combustion engine at the same time. For this reason, even if it provides the said clamping part, the operation man-hour of the assembly operation of an internal combustion engine does not increase, and it can suppress that the efficiency of the said assembly operation falls with the increase in the operation man-hour.

[First Embodiment]
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 by the lost motion mechanism 20 toward the intake cam 11a, in other words, in the valve closing direction of the intake valve 9, so that the roller 19 is pressed against the intake cam 11a. ing. The lost motion mechanism 20 urges the input arm 17 in the intake valve closing direction by the elastic force of the coil spring 20b housed in the case 20a. Further, the output arm 18 is pressed against the rocker arm 21 when swinging, and lifts the intake valve 9 via 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. Further, 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 provided. 18 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 variable lift amount 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.

  As shown in FIG. 4, the rocker shaft 15 is formed in a cylindrical shape, and the control shaft 16 is inserted inside thereof. The control shaft 16 is connected to the slider 26 by a pin 51. The pin 51 is inserted into the slider 26 from the outer peripheral side of the input gear 27 a and is fitted into the outer peripheral surface of the control shaft 16 while penetrating the rocker shaft 15 and is engaged with the inner peripheral surface of the slider 26. As a result, the control shaft 16 can move integrally with the slider 26 in the axial direction.

  The movement of the pin 51 accompanying the movement of the control shaft 16 in the axial direction is allowed by a long hole (not shown) that is formed in the rocker shaft 15 in advance so as to penetrate the pin 51. Further, when the input arm 17 and the output arm 18 swing, the slider 26 is also displaced in the circumferential direction with respect to the outer peripheral surface of the rocker shaft 15, and this displacement engages the slider 51 with the pin 51 on the inner peripheral surface. In order to do so, it is allowed by a pre-formed circumferentially extending groove (not shown).

  When the control shaft 16 is displaced in the axial direction and thereby the slider 26 is displaced in the axial direction, the input arm 17 and the output arm 18 are swung by the meshing of the helical splines 27 and 29 and the helical splines 28 and 30. The relative position about is changed. Specifically, the relative position of the input arm 17 and the output arm 18 is changed so that the control shaft 16 is displaced in the direction of arrow L in FIG. The relative positions of the input arm 17 and the output arm 18 are changed so as to be separated from each other. By changing the relative positions of the input arm 17 and the output arm 18, the maximum lift amount of the intake valve 9 and the operating angle of the intake cam 11a when the output arm 18 swings due to the rotation of the intake cam 11a are made variable. .

  Next, a structure for attaching 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 will be described with reference to FIG. 5.

  The figure is a plan view of the cam carrier 41 formed on the upper part of the cylinder head 2 as viewed from above. A plurality of bearings 42 are provided in parallel on the cam carrier 41, and the intake camshaft 11, the exhaust camshaft 12, and the rocker shaft 15 are disposed on each bearing 42. A cam cap 43 is attached on each bearing 42 by a bolt 44. The bearing 42 and the cam cap 43 support the intake cam shaft 11 and the exhaust cam shaft 12 in a rotatable manner, and a standing wall portion 45 that supports the rocker shaft 15 is formed in the cam carrier 41.

  An input arm 17 and an output arm 18 supported by the rocker shaft 15 are disposed between the two standing wall portions 45, and the input arm 17 is sandwiched between the two output arms 18 among the arms 17 and 18. It has become. A shim 46 is provided between the standing wall 45 and the output arm 18 to absorb the clearance between them and adjust the axial positions of the input arm 17 and the output arm 18. One end of the control shaft 16 inserted into the rocker shaft 15 is connected to the slide actuator 47. As the slide actuator 47 is driven, the control shaft 16 is moved in the axial direction, and the relative position of the input arm 17 and the output arm 18 in the swing direction is changed.

  The lost motion mechanism 20 that urges the input arm 17 in the valve closing direction of the intake valve 9 is attached to the cam carrier 41. More specifically, the case 20 a of the mechanism 20 is attached to the cam carrier 41 by a bolt 48 so that the elastic force of the coil spring 20 b of the mechanism 20 acts on the input arm 17 in the intake valve closing direction. A head cover 49 is attached to the cam carrier 41 to which the intake camshaft 11, the exhaust camshaft 12, the lift variable mechanism 14, the lost motion mechanism 20, and the like are attached by bolts 50.

  Next, the absorption of the clearance between the standing wall 45 and the output arm 18 by the shim 46 and the adjustment of the axial positions of the input arm 17 and the output arm 18 by the shim 46 will be described in detail.

  After the input arm 17, the output arm 18, the slider 26, the rocker shaft 15, and the control shaft 16 are assembled to the cam carrier 41, the control shaft 16 is brought into the position where the input arm 17 and the output arm 18 are closest to each other as an initial position ( It is displaced to the leftmost position in the figure. Subsequently, the cam carrier 41 is fixed on a position adjusting jig for adjusting the axial positions of the input arm 17 and the output arm 18 to the reference position. As a result, as shown in FIG. 6A, the tip end of the positioning pivot 68 provided on the jig comes into contact with the output arm 18. In this state, the base circle portion of the intake cam 11a is directed toward the roller 19 side of the input arm 17, and the input arm 17 and the output arm 18 are displaced to the left in FIG. As a result, as shown in FIG. 6B, the input arm 17 and the output arm 18 are separated from each other, the roller 19 of the input arm 17 comes into contact with the base circle of the intake cam 11a, and the arms 17, 18 are moved. The axial displacement of is stopped. The positions of the arms 17 and 18 at this time are used as the reference positions of the arms 17 and 18.

  After such adjustment of the input arm 17 and the output arm 18 to the reference position, a shim 46 having a thickness corresponding to the clearance between the standing wall portion 45 and the output arm 18 opposed thereto is selected, and the selected shim 46 is used as the standing wall portion. 45 and the output arm 18. Thereby, the clearance between the standing wall portion 45 and the output arm 18 is absorbed, and the arms 17 and 18 are positioned at the reference position. Further, the axial positions of the input arm 17 and the output arm 18 have a great influence on the change of the valve lift characteristic of the intake valve 9 with respect to the displacement of the slider 26 in the axial direction. For this reason, even after the input arm 17 and the output arm 18 are positioned at the reference position as described above, the axial positions of the arms 17 and 18 are finely adjusted in order to make the valve lift characteristics of the intake valve 9 appropriate. You may want to Such fine adjustment is performed by appropriately replacing the shim 46 with a different thickness.

  Next, a structure for preventing the above-described shim 46 from falling off between the output arm 18 and the standing wall portion 45 will be described with reference to FIG. 7A is a perspective view showing a state in which the shim 46 and the cam cap 43 are attached to the cam carrier 41, and FIG. 7B is a perspective view showing the shim 46, the cam cap 43, and the cam carrier 41 attached thereto. FIG. 5 is a plan view of the lift amount variable mechanism 14 as viewed from above.

  As shown in the figure, the shim 46 includes a foot portion 61 that extends into the lower portion and extends downward, and a recess 62 formed between the foot portions 61. The distance between the feet 61, that is, the width of the recess 62 is substantially equal to the outer diameter of the rocker shaft 15. When the shim 46 is assembled to the cam carrier 41, the shim 46 is disposed on the rocker shaft 15 with the foot 61 facing downward, and is dropped between the cam cap 43 and the output arm 18 in this state. Thus, the shim 46 is supported on the shaft 15 and assembled to the cam carrier 41 in a state where the rocker shaft 15 is housed in the recess 62.

  When the shim 46 is assembled in this manner, it can be easily taken out from between the cam cap 43 and the output arm 18 simply by lifting the shim 46 upward. For this reason, when replacing the shim 46 with a different thickness, it is possible to prevent the shim 46 from being difficult to attach to and detach from the rocker shaft 15 and to avoid the disadvantage of reducing the workability of the attaching and detaching work. Can do. However, if the rocker shaft 15 is only housed in the recess 62 at the end, the shim 46 rotates around the rocker shaft 15 due to vibrations or the like during engine operation, so that the foot portion 61 rises and the shim from the shaft 15 rises. There is a risk that 46 will drop off. In order to avoid this, it is conceivable to separately attach a regulating member for regulating the rotation of the shim 46 supported on the rocker shaft 15 around the shaft 15. In this case, while the shim 46 can be easily replaced, it is possible to prevent the shim 46 from dropping from the rocker shaft 15, but the efficiency of the assembly work of the engine 1 is increased by the amount of work of assembling the regulating member. The decrease is as described in the column [Problems to be solved by the invention].

  In order to cope with this, in the present embodiment, a protrusion 64 that restricts the rotation of the shim 46 around the rocker shaft 15 is formed on the cam cap 43 that is an existing part around the shim 46. An engaged surface 63 that catches the protrusion 64 during rotation is formed, and the rotation of the shim 46 is restricted by the protrusion 64 and the engaged surface 63.

  Here, the formation of the protrusion 64 on the cam cap 43 means that a portion for restricting the rotation of the shim 46 is shared with the cam cap 43. For this reason, in order to regulate the rotation of the shim 46, an increase in the number of parts can be suppressed. In addition, by attaching the cam cap 43 to the cam carrier 41 (bearing 42) with the bolt 44, the portion (protrusion 64) for restricting the rotation of the shim 46 is also attached to the cam carrier 41 at the same time. . Therefore, even if the protrusion 64 is provided, the work man-hour for the assembly work of the engine 1 does not increase, and it is possible to suppress a decrease in the efficiency of the assembly work as the work man-hour increases.

Hereinafter, the detail of the said to-be-engaged surface 63 and the protrusion 64 is demonstrated.
The engaged surfaces 63 of the shim 46 are respectively formed on both sides in the radial direction of the rocker shaft 15 in the shim 46, more specifically on both sides in the horizontal direction orthogonal to the shaft 15. These two engaged surfaces 63 are formed in a shape other than an arc shape centering on the axis of the rocker shaft 15, specifically, a flat shape extending in parallel with each other and perpendicular to the horizontal plane.

  On the other hand, the protrusion 64 of the cam cap 43 is formed to protrude from the surface of the cam cap 43 on the output arm 18 side, and sandwiches the two engaged surfaces 63 of the shim 46 from both radial sides of the rocker shaft 15. Are provided on the radially outer side of one engaged surface 63 and on the radially outer side of the other engaged surface 63, respectively. The surface 64a of each of the protrusions 64 facing the two engaged surfaces 63 is shaped so as to be caught with the engaged surface 63 when the shim 46 rotates around the rocker shaft 15, specifically, the two engaged surfaces. Corresponding to the surface 63, they are parallel to each other and are formed in a planar shape extending perpendicular to the horizontal plane.

  Since the engaged surface 63 and the opposed surface 64a are both planar shapes extending perpendicular to the horizontal plane, the engaged surface is removed when the shim 46 is attached to or detached from the cam cap 43 and the output arm 18 for replacement. The surface 63 and the opposing surface 64a are not easily caught. For this reason, the shim 46 can be easily attached and detached. Further, when the shim 46 is mounted between the cam cap 43 and the output arm 18 and attempts to rotate around the rocker shaft 15 due to vibration during engine operation, the two engaged surfaces of the shim 46 63 is caught by the opposing surface 64a of the protrusion 64 corresponding to each, and rotation of the shim 46 is controlled.

According to the embodiment described in detail above, the following effects can be obtained.
(1) Since the protrusion 64 that restricts the rotation of the shim 46 around the rocker shaft 15 is formed integrally with the cam cap 43 adjacent to the shim 46, the protrusion 64 is shared with the cam cap 43. It is possible to suppress an increase in the number of parts that accompanies the provision of a portion that restricts rotation. Furthermore, by attaching the cam cap 43 to the cam carrier 41, the protrusion 64, which is the part that restricts the rotation, is also attached to the cam carrier 41 at the same time. For this reason, by providing the protrusion 64, the work man-hour for the assembly work of the engine 1 does not increase, and it is possible to suppress a decrease in the efficiency of the assembly work as the work man-hour increases.

  (2) When the shim 46 arranged between the cam cap 43 and the output arm 18 and on the rocker shaft 15 tries to rotate around the shaft 15, a planar engaged surface formed on the shim 46. 63 is caught by the flat opposing surface 64a formed in the protrusion 64 of the cam cap 43, whereby the rotation of the shim 46 is restricted. In particular, two engaged surfaces 63 are provided so as to be parallel, and two protrusions 64 are provided so as to sandwich the two engaged surfaces 63 from both radial sides of the rocker shaft 15. Since the two engaged surfaces 63 are hooked on the corresponding opposing surfaces 64a, the rotation restriction of the shim 46 described above can be performed more reliably. Therefore, it is possible to accurately suppress the shim 46 from rotating and dropping off from the rocker shaft 15 until the foot 61 is raised.

  (3) Since the engaged surface 63 and the opposed surface 64a are formed in a planar shape perpendicular to the horizontal plane, when the shim 46 is attached to or detached from the cam cap 43 and the output arm 18, these engaged surfaces The mating surface 63 and the opposed surface 64a are not easily caught. Accordingly, the shim 46 for replacement can be easily attached and detached.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, instead of providing the cam cap 43 with a portion that restricts the rotation of the shim 46 around the rocker shaft 15 as in the first embodiment, the case 20a of the lost motion mechanism 20 that is an existing part around the shim 46 is provided. It is intended to be provided.

  FIG. 8 is a schematic diagram showing the shim 46 and the structure for restricting the rotation of the shim 46 in this embodiment. As shown in the figure, a protrusion 65 protruding toward the radially outer side (upward in the figure) of the rocker shaft 15 is formed on the upper portion of the shim 46 as a portion used for restricting the rotation of the shim 46. . In addition, the case 20 a of the lost motion mechanism 20 is integrally formed with a holding portion 66 that holds the protrusion 65 from both sides in the circumferential direction of the rocker shaft 15 as a portion that restricts the rotation of the shim 46. The holding portion 66 includes a pair of lower protrusions 66a protruding downward, and the protrusions 65 are sandwiched from both sides in the circumferential direction of the rocker shaft 15 by the lower protrusions 66a. And about the clamping part 66, when the case 20a is attached to the cam carrier 41 with the volt | bolt 48, a pair of lower protrusion part 66a will come to the position which clamps the shim 46 arrange | positioned between the cam cap 43 and the output arm 18. The case 20a is formed in advance.

  In this embodiment, the shim 46 is replaced with the case 20 a removed from the cam carrier 41. At this time, attachment / detachment of the shim 46 between the cam cap 43 and the output arm 18 can be easily performed because there is nothing that is caught around the shim 46 during the attachment / detachment. After the replacement of the shim 46 is completed, the shim 46 is arranged on the rocker shaft 15 so that the protrusion 65 protrudes upward, and the case 20a is attached to the cam carrier 41 in this state. By attaching the case 20a, the projection 65 of the shim 46 is sandwiched between the clamping portions 66 (a pair of lower projections 66a) of the case 20a. For this reason, when the shim 46 tries to rotate around the rocker shaft 15, the protrusion 65 is caught by the lower protrusion 66a, and the rotation of the shim 46 is restricted.

In the present embodiment, the following effects can be obtained.
(4) By removing the case 20a from the cam carrier 41, the shim 46 for replacement can be easily attached and detached.

  (5) The sandwiching portion 66 that restricts the rotation of the shim 46 is formed integrally with the case 20a of the lost motion mechanism 20 that is an existing part around the shim 46, and is shared with the case 20a. It is possible to suppress an increase in the number of parts that accompanies the provision of a portion that restricts rotation. Furthermore, by attaching the case 20 a to the cam carrier 41, the clamping portion 66, which is a part that restricts the rotation, is also attached to the cam carrier 41 at the same time. For this reason, by providing the clamping part 66, the work man-hour for the assembly work of the engine 1 does not increase, and it is possible to suppress a decrease in the efficiency of the assembly work as the work man-hour increases.

  (6) The rotation restriction of the shim 46 is realized by pinching the protrusion 65 from both sides in the circumferential direction of the rocker shaft 15 by the pair of lower protrusions 66a in the holding portion 66. For this reason, the protrusion 65 is caught by the lower protrusion 66a regardless of whether the shim 46 is about to rotate to one side in the circumferential direction of the rocker shaft 15 or to the other side in the circumferential direction. The rotation is restricted. Therefore, it is possible to accurately suppress the shim 46 from rotating and falling off the rocker shaft 15 until the foot 61 is raised.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. In this embodiment, instead of providing a portion for restricting the rotation of the shim 46 around the rocker shaft 15 in the case 20a of the lost motion mechanism 20 as in the second embodiment, the head cover 49 which is an existing component around the shim 46 is provided. It is intended to be provided.

  FIG. 9 is a schematic diagram showing the shim 46 and the structure for restricting the rotation of the shim 46 in this embodiment. As shown in the figure, the head cover 49 is integrally formed with a clamping portion 67 that clamps the protrusions 65 of the shim 46 from both sides in the circumferential direction of the rocker shaft 15 as a portion for restricting the rotation of the shim 46. The clamping portion 67 includes a pair of lower protrusions 67a protruding downward, and the protrusions 65 are sandwiched from both sides in the circumferential direction of the rocker shaft 15 by the lower protrusions 67a. And about the clamping part 67, when the head cover 49 is attached to the cam carrier 41 with the volt | bolt 50, a pair of lower protrusion part 67a arrange | positions the said protrusion 65 of the shim 46 arrange | positioned between the cam cap 43 and the output arm 18. The head cover 49 is formed in advance so as to be in a sandwiched position.

  In this embodiment, the shim 46 is replaced with the head cover 49 removed from the cam carrier 41. After the replacement of the shim 46 is completed, the shim 46 is arranged on the rocker shaft 15 so that the protrusion 65 protrudes upward, and the head cover 49 is attached to the cam carrier 41 in this state. When the head cover 49 is attached, the projection 65 of the shim 46 is sandwiched between the clamping portions 67 (the pair of lower projections 67a) of the head cover 49. For this reason, when the shim 46 tries to rotate around the rocker shaft 15, the protrusion 65 is caught by the lower protrusion 67a, and the rotation of the shim 46 is restricted.

In the present embodiment, the following effects can be obtained.
(7) By removing the head cover 49 from the cam carrier 41, the shim 46 for replacement can be easily attached and detached.

  (8) The clamping portion 67 that restricts the rotation of the shim 46 is formed integrally with the head cover 49 that is an existing component around the shim 46 and is shared with the head cover 49. The increase in the number of parts accompanying provision can be suppressed. Furthermore, by attaching the head cover 49 to the cam carrier 41, the clamping portion 67, which is the part that restricts the rotation, is also attached to the cam carrier 41 at the same time. For this reason, by providing the clamping part 67, the work man-hours for the assembly work of the engine 1 do not increase, and it is possible to suppress a decrease in the efficiency of the assembly work as the work man-hours increase.

  (9) The rotation restriction of the shim 46 is realized by pinching the protrusion 65 between the pair of lower protrusions 67a of the holding portion 67 from both sides in the circumferential direction of the rocker shaft 15. Therefore, the protrusion 65 is caught by the lower protrusion 67a regardless of whether the shim 46 is about to rotate to one side of the rocker shaft 15 or the other side of the rocker shaft 15. The rotation is restricted. Therefore, it is possible to accurately suppress the shim 46 from rotating and falling off the rocker shaft 15 until the foot 61 is raised.

In addition, each said embodiment can also be changed as follows, for example.
The cam cap 43, the case 20a of the lost motion mechanism 20 and the head cover 49 are illustrated as existing parts around the shim 46 that integrally form a member that restricts the rotation of the shim 46, but other peripheral parts are used. Also good.

In the first embodiment, the two engaged surfaces 63 are not necessarily provided, and one of the surfaces to be engaged may be omitted, and an arcuate surface centering on the axis of the rocker shaft 15 may be used.
The engaged surface 63 of the first embodiment does not necessarily have to be formed in a flat shape, and may be formed in any shape as long as it has a shape other than an arc shape centered on the axis of the rocker shaft 15. Is possible.

  The opposing surface 64a of the first embodiment does not necessarily have to be formed in a flat shape, and may be formed in an arbitrary shape as long as the engaged surface 63 is caught when the shim 46 is about to rotate. Is possible.

  In the second and third embodiments, the protruding direction of the protrusion 65 only needs to be directed upward from the horizontal so that the protrusion 65 can be sandwiched by the sandwiching portions 66 and 67 when the case 20a and the head cover 49 are attached. It does not necessarily have to be directly above.

  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 1st 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. The disassembled perspective view which shows the internal structure of a lift amount variable mechanism. The top view which shows the cam carrier of a cylinder head. (A) And (b) is an enlarged view of an input arm, an output arm, etc. for explaining a reference position adjustment method of an input arm and an output arm. (A) is the perspective view of the shim periphery which shows the shim drop prevention structure of 1st Embodiment, (b) is the top view which looked at the said shim periphery from upper direction. Schematic which shows the shim drop-off prevention structure of 2nd Embodiment. Schematic which shows the shim drop-off prevention structure of 3rd Embodiment.

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 ... Lost motion Mechanism, 20a ... Case, 20b ... Coil spring, 21 ... Rocker arm, 22 ... Rush adjuster, 23 ... Roller, 24 ... Valve spring, 26 ... Slider, 27 ... Helical spline, 27a ... Input gear, 28 ... Helical spline, 28a ... Internal gear, 29 ... helical spline, 29a ... output gear, 30 ... helica Spline, 30a ... internal gear, 41 ... cam carrier 42 ... bearing, 43 ... cam cap, 44 ... bolt, 45 ... standing wall, 46 ... shim, 47 ... slide actuator, 48 ... bolt, 49 ... head cover, 50 ... bolt , 51 ... pin, 61 ... foot, 62 ... recess, 63 ... engaged surface (engaged portion), 64 ... projection (engagement portion), 64a ... opposed surface, 65 ... projection (engaged portion) ), 66... Sandwiching part (engaging part), 66 a... Lower projecting part, 67... Clamping part (engaging part), 67 a.

Claims (6)

An input arm that is pushed by a rotating cam and swings about an axis, an output arm that swings about the axis based on the swing of the input arm and lifts the engine valve, the input arm, and the output An internal combustion engine comprising a slider connected to the arms via gears having different tooth inclination directions and reciprocally movable in the axial direction, and a shim provided between the arms and a standing wall portion supporting the shaft In the variable valve mechanism of the engine,
The shim is supported on the shaft, and includes an engaged portion used for restricting rotation around the shaft.
A variable valve mechanism for an internal combustion engine, characterized in that an engaging portion that engages with the engaged portion and restricts rotation of the shim is shared with existing parts around the shim. The engaged portion of the shim is a non-arc-shaped engaged surface formed on the outer side in the radial direction of the shaft in the shim,
The engaging portion is formed to protrude from the shim-side surface of the cam cap that forms the standing wall portion, and the surface to be engaged with the engaged surface during rotation about the axis of the shim. The variable valve mechanism for an internal combustion engine according to claim 1, wherein the projecting portion has a shape that hooks with a surface. The variable valve mechanism for an internal combustion engine according to claim 2, wherein the engaged surface is formed in a flat shape, and the facing surface facing the engaged surface is also formed in a flat shape. The engaged surfaces are formed so as to be parallel to each other on both sides in a horizontal direction perpendicular to the axis of the shim,
The projecting portion of the cam cap has the radially outer side of one engaged surface and the radially outer side of the other engaged surface so that the two engaged surfaces are sandwiched from both radial sides of the shaft. And provided respectively.
The variable motion of the internal combustion engine according to claim 2 or 3, wherein surfaces of the two protrusions facing each of the engaged surfaces are formed in parallel with each other so as to correspond to the engaged surfaces. Valve mechanism. The engaged portion of the shim is a protrusion protruding from the shim toward the radially outer side of the shaft,
The engaging portion is integrally formed with a case of a lost motion mechanism that urges the input arm in the valve closing direction of the engine valve, and the protrusion is inserted from both sides in the circumferential direction of the shaft when the case is assembled to the internal combustion engine. The variable valve mechanism for an internal combustion engine according to claim 1, wherein the variable valve mechanism is an sandwiching part. The engaged portion of the shim is a protrusion protruding from the shim toward the radially outer side of the shaft,
2. The internal combustion engine according to claim 1, wherein the engaging portion is formed integrally with a head cover of the internal combustion engine, and is a sandwiching portion that sandwiches the protrusion from both sides in the circumferential direction of the shaft when the head cover is assembled to the cylinder head. Variable valve mechanism.

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