JP2020183705A - Variable valve mechanism for internal combustion engine - Google Patents

Abstract

To improve the accuracy of the thrust position of a roller to reduce variations by determining the thrust position using a small number of members, and to prevent a link arm from being displaced to an unintended position at a timing when both fitted-in arms are not fitted into a spiral groove.SOLUTION: A rocker arm 10 is supported displaceably in a rocker shaft length direction by a rocker shaft 9, and the thrust position as the predetermined displacement end is determined by the side face of the rocker arm 10 abutting on the side face of a cam support 27 (or a cam cap 28) of a cylinder head. A roller 16 is positioned relative to the rocker shaft 9, and the displacement in the rocker shaft length direction of a link arm 20 causes the displacement of the rocker arm 10 in the rocker shaft length direction together with the roller 16. Besides, an energizing structure 30 is provided for energizing the rocker arm 10 to the thrust position.SELECTED DRAWING: Figure 2

Description

The present invention relates to a variable valve mechanism that drives a valve of an internal combustion engine and changes the driving state thereof according to an operating condition of the internal combustion engine.

The applicant has previously proposed the variable valve mechanism 51 of the internal combustion engine shown in FIG. 8 (Patent Document 1). In this variable valve mechanism 51, the cam shaft 52 is provided with a cam 53 and two spiral grooves 54 and 55, and the rocker arm body 57 is swingably supported by the rocker shaft 56 extending in parallel with the cam shaft 52. The rocker arm body 57 is provided with a roller shaft 58 extending in parallel with the rocker shaft 56, and the roller 59 with which the cam 53 can abut is supported on the roller shaft 58 so as to be displaceable in the longitudinal direction of the rocker shaft. , 55 The link arm 60 including the two engagement arms 61 and 62 and the roller guide 63 (sliding contact portion) holding both side surfaces of the roller 59 is displaced in the length direction of the rocker shaft. It is provided as possible. Then, the entire link arm 60 is rotated by a rotating device (not shown) so that one engaging arm 61 is engaged in one spiral groove 54, or the other engaging arm (not shown) is engaged in the other. By selecting whether to engage in the spiral groove 55, the link arm 60 and the roller 59 are displaced in the length direction of the rocker shaft according to the selected spiral grooves 54 and 55, and the cam 53 abuts on the roller 59 or It is a mechanism to switch whether to contact or not.

JP-A-2014-224496

In the variable valve mechanism 51 described above, the thrust position, which is the predetermined end of the displacement of the roller 59 in the long direction of the rocker shaft, is determined only by the spiral grooves 54 and 55 and the engaging arms 61 and 62, and thus the spiral grooves 54 and 55. There was a risk that the durability of the engagement arms 61 and 62 would become a problem.

Therefore, the present inventors determine the thrust position of the roller 59 by another member, for example, the displaced roller guide 63 is applied to a bolt screwed into a screw hole of a rocker shaft 56 via a bush (not shown). I considered that. However, in that case, the thrust position of the roller 59 is determined not only through the bush, the bolt and the screw hole, but also through a large number of parts such as the bolt and the screw hole (these are not shown) that attach the rocker shaft 56 to the cylinder head. However, there is a problem that the accuracy of the thrust position is lowered and the variation becomes large.

Further, in the link arm 60, when either of the engaging arms 61, 62 is engaged in the spiral grooves 54, 55, the engagement restricts the displacement of the link arm 60 in the axial length direction. Even if a force is applied to the link arm 60 in the axial length direction due to vibration of the internal combustion engine or the like at this time, the link arm 60 will not be displaced to an unintended position. However, at the time of switching, since the engagement between one engagement arm and the spiral groove is released and the other engagement arm engages with the spiral groove, both engagement arms 61 and 62 are momentarily engaged with the spiral groove 54, There is a timing when 55 is not engaged. If vibration or external force is applied to the valve operating mechanism at that time, the link arm 60 may be displaced to an unintended position, the position of the roller 59 with respect to the cam 53 may shift, and the cam may be in a half-riding state, or the roller guide 63 or the like may be damaged. There is a risk of

It is difficult to make the other engaging arm engage in the spiral groove before the engagement between the one engaging arm and the spiral groove is released. This is because a force is applied from the spiral groove to both engaging arms at the timing when both engaging arms are engaged in the spiral groove, and an unreasonable force is also applied to the link arm 60.

Therefore, the first problem is to determine the thrust position of the roller by a small number of members other than the spiral groove and the engagement arm, to improve the durability of the spiral groove and the engagement arm, and to improve the accuracy of the thrust position. The purpose is to reduce the variation.
The second problem is to prevent the link arm from being displaced to an unintended position at a timing when neither of the two engaging arms engages in the spiral groove.

In order to solve the first problem, the first invention
The camshaft (2) is provided with a cam (3) and two spiral grooves (5,7).
A rocker arm (10) including a roller (16) with which the cam (3) can come into contact with the rocker shaft (9) extending in parallel with the cam shaft (2) is swingably supported.
A link arm (20) including two engagement arms (23, 24) that selectively engage the two spiral grooves (5, 7) is provided so as to be displaceable in the longitudinal direction of the rocker shaft.
Two engagement arms (23, 24) are rotated by a rotating device (40) to engage one engagement arm (23) into one spiral groove (5) or the other engagement arm. By selecting whether to engage (24) with the other spiral groove (7), the link arm (20) is displaced in the rocker shaft longitudinal direction according to the selected spiral groove (5, 7), and is based on the displacement. In the variable valve mechanism of the internal combustion engine, the roller (16) is displaced in the longitudinal direction of the rocker shaft to switch whether the cam (3) abuts or does not abut on the roller (16).
The rocker arm (10) is displaceably supported by the rocker shaft (9) in the longitudinal direction of the rocker shaft, and the thrust position, which is a predetermined end of the displacement, is such that the side surface of the rocker arm (10) is the cam support (27) of the cylinder head. Determined by contacting the side surface of the cam cap (28)
The roller (16) is positioned relative to the rocker arm (10).
The displacement of the link arm (20) in the long direction of the rocker shaft is characterized in that the rocker arm (10) is displaced together with the roller (16) in the long direction of the rocker shaft.

In order to solve the second problem, the second invention is characterized in that, in addition to the first invention, an urging structure (30) for urging the rocker arm (10) to the thrust position is provided. ..

According to the first invention, the thrust positions of the rocker arm and the roller are determined by a small number of members other than the spiral groove and the engagement arm to improve the durability of the spiral groove and the engagement arm and to improve the accuracy of the thrust position. Can be improved to reduce variation.
Further, according to the second invention, it is possible to prevent the link arm from being displaced to an unintended position at a timing when neither of the two engaging arms engages in the spiral groove.

FIG. 1 is a perspective view of the variable valve mechanism of the first embodiment as viewed from the front side (front side). FIG. 2 is a perspective view of the mechanism as viewed from the rear side (rear side). FIG. 3A is a perspective view of a rocker arm and a link arm of the same mechanism, and FIG. 3B is a cross-sectional view of the rocker arm of the same mechanism cut at a roller position. FIG. 4A is a side sectional view of the mechanism cut at the boundary position between the rocker arm and the head, and FIG. 4B is a side sectional view of the mechanism cut at the position of the link arm. 5A and 5B are cross-sectional views taken along the line VV of the same mechanism, where FIG. 5A shows a time when the roller is displaced to the first cam position, and FIG. 6A and 6B are VI-VI cross-sectional views of the variable valve mechanism of the second embodiment, where FIG. 6A shows when the roller is displaced to the first cam position and FIG. 6B shows the roller is displaced to the second cam position. Show the time. 7A and 7B are VII-VII cross-sectional views of the variable valve mechanism of Example 3, where FIG. 7A shows when the roller is displaced to the first cam position, and FIG. 7B shows the roller is displaced to the second cam position. Show the time. 8A and 8B show a conventional variable valve mechanism, where FIG. 8A is a perspective view and FIG. 8B is a cross-sectional view.

1. 1. The rocker arm roller is not particularly limited, but is preferably positioned with respect to the rocker arm by being sandwiched between a pair of facing surfaces of the rocker arm facing each other in the longitudinal direction of the rocker shaft with a predetermined clearance.
The number of rollers included in the rocker arm may be one or a plurality, but two on the left and right are preferable in terms of left-right balance.
The rocker arm may drive a plurality of valves or may drive a single valve.
The rocker arm may directly drive the valve or may indirectly drive the valve (for example, the rocker arm presses the second rocker arm and the second rocker arm drives the valve).

2. Link arm The link arm is not particularly limited, but is preferably sandwiched between a pair of facing surfaces of the rocker arm facing each other in the longitudinal direction of the rocker shaft with a predetermined clearance.

3. 3. Rotating device The rotating device is not particularly limited, and examples thereof include an electromagnetic solenoid, a hydraulic mechanism, an electric motor mechanism, and the like.

4. Biasing structure The urging structure is not particularly limited, but the following aspects can be exemplified.
(1) The urging structure comprises a convex latch urged by a leaf spring and a concave catch in which a protruding latch is engaged.
(2) The urging structure comprises a ball latch urged by a coil spring and a concave catch in which the ball latch engages. In this aspect, the following more specific aspects can be exemplified.
(A) The coil spring and the ball latch are built in the rocker shaft, and the concave catch is formed in the rocker arm.
(B) The coil spring and the ball latch are built in the rocker arm, and the concave catch is formed in the rocker shaft.

5. The mode when the cam does not contact the roller The mode when the cam does not contact the roller includes a mode in which another cam does not contact the roller, a mode in which another zero-lift circular cam contacts the roller, and a roller. It can be exemplified that the cam of another nose profile comes into contact with the cam. The next embodiment is a mode in which a cam having another nose profile comes into contact with the roller.

Next, an embodiment of the present invention will be described with reference to the drawings. The structure, shape, number, etc. of each part of the embodiment are examples, and can be appropriately changed without departing from the spirit of the invention.

<Example 1>
The variable valve mechanism 1 of the first embodiment shown in FIGS. 1 to 5 is
The camshaft 2 is provided with a cam 3 and two spiral grooves 5 and 7.
A rocker arm 10 including a roller 16 with which the cam 3 can come into contact with the rocker shaft 9 extending in parallel with the cam shaft 2 is swingably supported.
A link arm 20 including two engaging arms 23 and 24 that selectively engage the two spiral grooves 5 and 7 is provided so as to be displaceable in the longitudinal direction of the rocker shaft.
The two engagement arms 23, 24 are rotated by the rotating device 40 to engage one engagement arm 23 into one spiral groove 5, or the other engagement arm 24 into the other spiral groove 7. By selecting whether to engage, the link arm 20 is displaced in the rocker shaft length direction according to the selected spiral grooves 5 and 7, and the roller 16 is displaced in the rocker shaft length direction based on the displacement, and the roller 16 is displaced. A mechanism for switching whether the cam 3 abuts or does not abut.
The rocker arm 10 is displaceably supported by the rocker shaft 9 in the longitudinal direction of the rocker shaft, and the thrust position, which is a predetermined end of the displacement, is such that the side surface of the rocker arm 10 is on the side surface of the cam support 27 (or cam cap 28) of the cylinder head. Determined by contact
The roller 16 is positioned so as not to be substantially displaced relative to the rocker arm 10 in the length direction of the rocker shaft.
The displacement of the link arm 20 in the long direction of the rocker shaft causes the rocker arm 10 to be displaced together with the roller 16 in the long direction of the rocker shaft.
It is characterized by having an urging structure 30 for urging the rocker arm 10 to the thrust position.

The camshaft length direction, the rocker shaft length direction, and the roller shaft length direction are all the same in the left-right direction in FIG. Therefore, in the following, the direction toward the left in FIG. 1 viewed from the front side is referred to as the axial length direction d1, and the direction toward the right is referred to as the axial length direction d2. The terms left and right refer to the left and right in FIG. 2 and 5 to 7 seen from the rear side appear opposite to those in FIG.

[Cam, etc.]
The camshaft 2 is inserted and rotatably supported between the cam support 27 of the cylinder head of the internal combustion engine and the cam cap 28 attached on the cam support 27 by bolts 29. Between the two cam supports 27 that are separated from each other, the camshaft 2 has the first cam 3 and the second cam 4 as drive cams and the cam rail groove in this order from the axial length direction d1 side to the axial length direction d2 side. The second spiral groove 7, the annular groove 6, and the first spiral groove 5 of the above, and the first cam 3 and the second cam 4 as drive cams are provided side by side.

The two first cams 3 are composed of a base circle having a circular cross-sectional shape and a nose having a relatively high lift and a narrow working angle protruding from the base circle, and are mainly used in a high-speed rotation range.
The two second cams 4 are composed of a base circle having a circular cross-sectional shape and a nose having a relatively low lift and a wide working angle protruding from the base circle, and are mainly used in a low speed rotation range.

The annular groove 6 is a groove for locking the link arm 20 in the axial length direction d1 and d2 so as not to be displaced, and is an annular groove that does not shift in the axial length direction.

The first spiral groove 5 is a groove for displacing the link arm 20 in the axial length direction d1, and is provided on the axial length direction d2 side of the annular groove 6. The first spiral groove 5 extends from its base end to a predetermined position in the direction opposite to the rotation direction of the camshaft 2 without shifting in the axial length directions d1 and d2, and from the predetermined position, the camshaft As it advances in the direction opposite to the rotation direction of 2, it extends spirally toward the axial length direction d1 side and joins the annular groove 6. The spirally extending portion is provided in a phase in which the tip end portion of the first engagement arm 23 engages when the base circles of the first and second cams 3 and 4 act.

The second spiral groove 7 is a groove for displacing the link arm 20 in the axial length direction d2, and is provided on the axial length direction d1 side of the annular groove 6. The second spiral groove 7 extends from its base end to a predetermined position in the direction opposite to the rotation direction of the camshaft 2 without shifting in the axial length directions d1 and d2, and from the predetermined position, the camshaft As it advances in the direction opposite to the rotation direction of 2, it extends spirally toward the axial length direction d2 and joins the annular groove 6. The spirally extending portion is provided in a phase in which the tip end portion of the second engagement arm 24 engages when the base circles of the first and second cams 3 and 4 act.

[Rocker arm, etc.]
A rocker shaft 9 extending in parallel with the cam shaft 2 is inserted through the cam support 27 of the cylinder head. Between the two cam supports 27 separated from each other, the rocker arm 10 is supported on the rocker shaft 9 so as to be swingable in the circumferential direction of the rocker shaft and displaceable in the axial length directions d1 and d2.

As shown in FIG. 3 and the like, the rocker arm 10 is a dual rocker arm in which the lower part of the left rocker arm 11 and the right rocker arm 12 is separated by a connecting portion 13 and connected. The left and right rocker arms 11 and 12 are formed of a base portion 14 fitted to the rocker shaft 9 and supported as described above, a pair of side wall portions 17 and 17 separated in the axial length direction, and a pair of side wall portions 17 and 17. A valve pressing portion for pressing the valve V is formed on the front portion of the lower surface of the bottom portion 18 including the bottom portion 18 connecting the lower portions. Since the left-right length of the rocker arm 10 is smaller than that between the two cam supports 27, the rocker arm 10 can be displaced between the two cam supports 27 in the axial length directions d1 and d2.

Further, the left and right rocker arms 11 and 12 are rotatably attached to the roller shaft 15 bridged between the pair of side wall portions 17 and 17 and the roller shaft 15 via a needle roller in the roller shaft circumferential direction. It includes a roller 16 and a roller 16. The roller 16 provides a predetermined clearance (minimum clearance for allowing the rotation of the roller 16) on the pair of first facing surfaces f1 and f1 facing the rocker shaft length direction of the pair of side wall portions 17 and 17. It is pivotally attached to the roller shaft 15 as described above in a state of being sandwiched between the two. Therefore, the roller 16 is positioned so as not to be substantially displaced relative to the rocker arms 11 and 12 in the rocker shaft axial length direction (roller shaft longitudinal direction), and is displaced together with the rocker arm 10 in the rocker shaft longitudinal direction. ..

[Link arm]
As shown in FIG. 3 and the like, the link arm 20 is separated from the tubular base portion 22 and the tubular base portion 22 in the axial length direction in the front view, and protrudes forward so as to form a V shape in the side view. It is configured to include the first engagement arm 23 and the second engagement arm 24 protruding upward.

The tubular base 22 allows a predetermined clearance (rotation of the link arm 20 is allowed) on a pair of second facing surfaces f2 and f2 facing the base 14 of the left rocker arm 11 and the base 14 of the right rocker arm 12 in the longitudinal direction of the rocker shaft. It is rotatably fitted to the rocker shaft 9 in the circumferential direction of the rocker shaft while being sandwiched with a minimum clearance). Therefore, the link arm 20 cannot be substantially displaced in the axial length direction with respect to the rocker arm 10, and can be displaced in the axial length direction together with the rocker arm 10 and the roller 16.

The thrust position on the d1 side of the rocker arm 10 in the axial length direction is determined by the left side surface of the base 14 of the left rocker arm 11 abutting against the side surface of the left cam support 27 (or cam cap 28). The thrust position on the d1 side in the axial length direction is also determined. In other words, the side surface of the cam support 27 (or cam cap 28) regulates the displacement end of the rocker arm 10 in the thrust direction on the axial length direction d1 side.
The thrust position on the d2 side of the rocker arm 10 in the axial length direction is determined by the right side surface of the base 14 of the right rocker arm 12 abutting against the side surface of the right cam support 27 (or cam cap 28). The thrust position on the d2 side in the axial length direction is also determined. In other words, the side surface of the cam support 27 (or cam cap 28) regulates one end of the rocker arm 10 in the thrust direction on the axial length direction d2 side.

A plate-shaped pressed portion 25 is provided on the back surface of the tubular base portion 22, and the lower or upper portion of the pressed portion 25 is selectively pressed forward by the rotating device 40 to rotate the link arm 20. Move.

The tip of the first engagement arm 23 is formed so that it can be engaged in the first spiral groove 5 or the annular groove 6.
The tip of the second engagement arm 24 is formed so that it can be engaged in the second spiral groove 7 or the annular groove 6.

[Biasing structure]
The urging structure 30 that urges the rocker arm 10 to the thrust position on the d1 side in the axial length direction includes a convex latch 33 urged by a leaf spring 31 attached to the back surface of the left cam support 27 with a bolt 32, and a left side. It is composed of a concave catch 34 formed on the base 14 of the rocker arm 11 to which a convex latch 33 is engaged.
The urging structure 30 that urges the rocker arm 10 to the thrust position on the d2 side in the axial length direction includes a convex latch 33 urged by a leaf spring 31 attached to the back surface of the cam support 27 on the right side with a bolt 32 and a right side. It is composed of a concave catch 34 formed on the base 14 of the rocker arm 12 to which a convex latch 33 is engaged.
Each convex latch 33 is formed by deforming an intermediate portion of the leaf spring 31, but may be attached to the leaf spring 31.

When the rocker arm 10 is determined at each thrust position in the axial length direction d1 and d2, each convex latch 33 engages with each concave catch 34 to urge the rocker arm 10 to each thrust position. Since the rocker arm 10 is held at each thrust position by this urging, even if vibration or an external force is applied to the valve operating mechanism at the timing when neither of the engaging arms 23 and 24 engages with the spiral grooves 5 and 7. The rocker arm 10 and the link arm 20 will not be displaced to unintended positions.

[Rotating device]
As shown in FIGS. 2 and 4, the rotating device 40 includes a first electromagnetic solenoid 41 for pressing the lower portion of the pressed portion 25 forward to rotate the link arm 20 in one r1 in the axial circumferential direction. The second electromagnetic solenoid 42 for pressing the upper portion of the pressed portion 25 forward to rotate the link arm 20 in the other direction r2 in the axial circumferential direction. When the electromagnetic solenoids 41 and 42 are turned on, the rod is extended to press the link arm 20, and when the rod is turned off, the rod is retracted to release the pressing.

The variable valve operation of the variable valve mechanism 1 of the embodiment configured as described above will be described.
[1] When the roller 16 is displaced to the position where the second cam 4 abuts, the second electromagnetic solenoid 42 is turned on to press the upper portion of the pressed portion 25 forward, as shown by the solid line in FIG. 4 (b). In addition, the link arm 20 is rotated in the other direction r2 in the axial circumferential direction. Due to the rotation of the link arm 20, the tip of the second engagement arm 24 engages in the second spiral groove 7, and the tip of the first engagement arm 23 exits the annular groove 6. As described above, the spirally extending portion of the second spiral groove 7 is in the phase in which the second engagement arm 24 is engaged during the base circular action, and therefore, as shown in FIGS. 1, 2 and 5 (a). As the camshaft 2 rotates, the link arm 20 is displaced along the second spiral groove 7 in the axial length direction to the other d2 when the base circle acts, and the rocker arm 10 and the roller 16 are pushed and similarly displaced. As a result, the two rollers 16 are displaced to positions where the two second cams 4 abut (and the first cam 3 does not abut), and the second engaging arm 24 enters the annular groove 6 to enter the link arm. The left-right position of 20 is maintained. Further, as described above, the thrust position of the rocker arm 10 is determined by the contact between the rocker arm 10 and the cam support 27, and the rocker arm 10 is urged to the thrust position by the urging structure 30.

Then, the roller 16 is pressed by the second cam 4, the rocker arm 10 swings, and the valve V pressed by the valve pressing portion of the left rocker arm 11 and the valve V pressed by the valve pressing portion of the right rocker arm 12. Two valves are lifted at the same time with a low lift and a wide working angle. This valve operating mode is mainly used in the low speed range.

[2] When the roller 16 is displaced to the position where the first cam 3 abuts, the first electromagnetic solenoid 41 is turned on, the lower portion of the pressed portion 25 is pressed forward, and a two-dot chain line is shown in FIG. 4 (b). As shown, the link arm 20 is rotated in one r1 in the circumferential direction. By the rotation of the link arm 20, the tip of the first engagement arm 23 engages with the first spiral groove 5, and the tip of the second engagement arm 24 exits the annular groove 6. As described above, since the spirally extending portion of the first spiral groove 5 is in the phase in which the first engagement arm 23 is engaged during the base circular action, the link arm 20 is cams as shown in FIG. 5 (b). Along with the rotation of the shaft 2, when the base circle acts, it is displaced in one direction d1 in the axial length direction along the first spiral groove 5, and the rocker arm 10 and the roller 16 are pushed to displace in the same manner. As a result, the two rollers 16 are displaced to positions where the two first cams 3 abut (and the second cam 4 does not abut), and the first engagement arm 23 enters the annular groove 6 to enter the link arm. The left-right position of 20 is maintained. Further, as described above, the thrust position of the rocker arm 10 is determined by the contact between the rocker arm 10 and the cam support 27, and the rocker arm 10 is urged to the thrust position by the urging structure 30.

Then, the roller 16 is pressed by the first cam 3, the rocker arm 10 swings, and the valve V pressed by the valve pressing portion of the left rocker arm 11 and the valve V pressed by the valve pressing portion of the right rocker arm 12. Two valves are lifted at the same time with a high lift and a narrow working angle. This valve operating mode is mainly used in the high speed rotation range.

According to Example 1, the following effects can be obtained.
(A) The thrust positions of the rocker arm 10 and the roller 16 are determined by a small number of members (rocker arm 10 itself and the cam support 27 or the cam cap 28) different from the spiral grooves 5 and 7 and the engaging arms 23 and 24, and the spiral is formed. The durability of the grooves 5 and 7 and the engagement arms 23 and 24 is enhanced, and the number of the members is small, so that the accuracy of the thrust position can be improved and the variation can be reduced. In addition, the small number of the members makes it possible to reduce costs by relaxing the tolerance of the members.
(B) It is possible to prevent the link arm from being displaced to an unintended position at a timing when neither of the two engaging arms is engaged in the spiral groove.
(C) Since it is not necessary to provide a roller guide for holding the side surface of the roller (which is a separate part from the rocker arm) together with the link arm so as to be displaced in the axial length direction as in the conventional example, the structure is simplified.
(D) The roller shaft provided on the rocker arm can be shortened to substantially the same as the roller width. When the roller shaft is short as described above, the deflection of the roller shaft is small when a load is input to the roller, so that the mechanical rigidity is improved.

<Example 2>
Next, the variable valve mechanism 1 of the second embodiment shown in FIG. 6 is different from the first embodiment only in that the urging structure 30 is changed, and the other parts are common to the first embodiment. For convenience, VI-VI is shown in FIG. 4A of Example 1 for the cut portion of FIG. 6, but Example 2 does not have the urging structure of Example 1 and Example 1 Does not have the urging structure of Example 2.

The urging structure 30 that urges the rocker arm 10 to the thrust position on the d1 side in the axial length direction includes a coil spring 36 built in a bottomed hole 35 formed on the left side of the middle portion of the rocker shaft 9 and a ball urged by the coil spring 36. It is composed of a latch 37 and a concave catch 34 formed on the inner surface of the base 14 of the left rocker arm 11 to which the ball latch 37 engages.
The urging structure 30 that urges the rocker arm 10 to the thrust position on the d2 side in the axial length direction includes a coil spring 36 built in a bottomed hole 35 formed on the right side of the middle portion of the rocker shaft 9 and a ball urged by the coil spring 36. It comprises a latch 37 and a concave catch 34 formed on the inner surface of the base 14 of the right rocker arm 12 to which the ball latch 37 engages.

When the rocker arm 10 is determined at each thrust position in the axial length direction d1 and d2, each ball latch 37 engages with each concave catch 34 to urge the rocker arm 10 to each thrust position. Since the rocker arm 10 is held at each thrust position by this urging, even if vibration or an external force is applied to the valve operating mechanism at the timing when neither of the engaging arms 23 and 24 engages with the spiral grooves 5 and 7. The rocker arm 10 and the link arm 20 will not be displaced to unintended positions.

According to Example 2, in addition to the action and effect according to Example 1, the following action and effect can be obtained.
(E) When the leaf spring 31 is used as in the first embodiment, a space for attaching the bolt 29 to the cam support 27 is required. When the ball latch 37 is used as in the second embodiment, the mechanism can be built-in, which is advantageous in terms of space.
(F) When the convex latch 33 is used as in the first embodiment, the convex latch 33 is in sliding contact with the concave catch 34 when the rocker arm 10 is swung, so that the convex latch 33 may be worn. When the ball latch 37 is used as in the second embodiment, the ball latch rotates and contacts the inner surface of the concave catch 34 or the base portion 14 when the rocker arm 10 swings, so that wear is reduced.

<Example 3>
Next, the variable valve mechanism 1 of the third embodiment shown in FIG. 7 is different from the first embodiment only in that the urging structure 30 is changed, and the other parts are common to the first embodiment. For convenience, the cut portion of FIG. 6 describes VII-VII of FIG. 4 (a) of Example 1, but Example 3 does not have the urging structure of Example 1 and Example 1 Does not have the urging structure of Example 3.

The urging structure 30 that urges the rocker arm 10 to the thrust position on the d1 side in the axial length direction is urged by the coil spring 36 built in the bottomed hole 35 formed inside the base 14 of the left rocker arm 11 and the coil spring 36. It is composed of a ball latch 37 and a concave catch 34 on which the ball latch 37 is engaged, which is formed on the left side of the middle portion of the rocker shaft 9.
The urging structure 30 that urges the rocker arm 10 to the thrust position on the d2 side in the axial length direction is urged by the coil spring 36 built in the bottomed hole 35 formed inside the base 14 of the right rocker arm 12 and the coil spring 36. It is composed of a ball latch 37 and a concave catch 34 formed on the right side of the middle portion of the rocker shaft 9 to which the ball latch 37 engages.

When the rocker arm 10 is determined at each thrust position in the axial length direction d1 and d2, each ball latch 37 engages with each concave catch 34 to urge the rocker arm 10 to each thrust position. Since the rocker arm 10 is held at each thrust position by this urging, even if vibration or an external force is applied to the valve operating mechanism at the timing when neither of the engaging arms 23 and 24 engages with the spiral grooves 5 and 7. The rocker arm 10 and the link arm 20 will not be displaced to unintended positions.

The same action and effect as in Example 2 can be obtained by Example 3. In the second embodiment, since the concave catch 34 is on the rocker arm 10 side, the rocker arm 10 can be made compact. In the third embodiment, since the concave catch 34 is on the rocker shaft 9 side, the rocker shaft 9 can be made compact.

The present invention is not limited to the above-described embodiment, and can be appropriately modified and embodied as follows, for example, without departing from the spirit of the invention.
(1) The first cam 3 and the second cam 4 are each one, and the roller 16 is one.

1 Variable valve mechanism 2 Camshaft 3 1st cam 4 2nd cam 5 1st spiral groove 6 Circular groove 7 2nd spiral groove 9 Rocker shaft 10 Rocker arm 11 Left rocker arm 12 Right rocker arm 13 Connecting part 14 Base 15 Roller shaft 16 Roller 17 Side wall 18 Bottom 20 Link arm 22 Cylindrical base 23 First engagement arm 24 Second engagement arm 25 Pressed part 27 Cam support 28 Cam cap 29 Bolt 30 Biasing structure 31 Leaf spring 32 Bolt 33 Convex latch 34 Concave catch 35 Bottomed hole 36 Coil spring 37 Ball latch 40 Rotating device 41 First electromagnetic solenoid 42 Second electromagnetic solenoid V valve

Claims (6)

The camshaft (2) is provided with a cam (3) and two spiral grooves (5,7).
A rocker arm (10) including a roller (16) with which the cam (3) can come into contact with the rocker shaft (9) extending in parallel with the cam shaft (2) is swingably supported.
A link arm (20) including two engagement arms (23, 24) that selectively engage the two spiral grooves (5, 7) is provided so as to be displaceable in the longitudinal direction of the rocker shaft.
Two engagement arms (23, 24) are rotated by a rotating device (40) to engage one engagement arm (23) into one spiral groove (5) or the other engagement arm. By selecting whether to engage (24) with the other spiral groove (7), the link arm (20) is displaced in the rocker shaft longitudinal direction according to the selected spiral groove (5, 7), and is based on the displacement. In the variable valve mechanism of the internal combustion engine, the roller (16) is displaced in the longitudinal direction of the rocker shaft to switch whether the cam (3) abuts or does not abut on the roller (16).
The rocker arm (10) is displaceably supported by the rocker shaft (9) in the longitudinal direction of the rocker shaft, and the thrust position, which is a predetermined end of the displacement, is such that the side surface of the rocker arm (10) is the cam support (27) of the cylinder head. Determined by contacting the side surface of the cam cap (28)
The roller (16) is positioned so as not to be substantially displaced relative to the rocker arm (10) in the longitudinal direction of the rocker shaft.
A variable valve mechanism of an internal combustion engine, characterized in that the displacement of the link arm (20) in the long direction of the rocker shaft causes the rocker arm (10) to be displaced together with the roller (16) in the long direction of the rocker shaft. The variable valve mechanism for an internal combustion engine according to claim 1, further comprising an urging structure (30) for urging the rocker arm (10) to a thrust position. The internal combustion engine according to claim 2, wherein the urging structure (30) includes a convex latch (33) urged by a leaf spring (31) and a concave catch (34) in which the convex latch (33) is engaged. Variable valve mechanism of the engine. The internal combustion engine according to claim 2, wherein the urging structure (30) includes a ball latch (37) urged by a coil spring (36) and a concave catch (34) in which the ball latch (37) is engaged. Variable valve mechanism. The variable valve mechanism for an internal combustion engine according to claim 4, wherein the coil spring (36) and the ball latch (37) are built in the rocker shaft (9), and the concave catch (34) is formed in the rocker arm (10). The variable valve mechanism for an internal combustion engine according to claim 4, wherein the coil spring (36) and the ball latch (37) are built in the rocker arm (10), and the concave catch (34) is formed in the rocker shaft (9).

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