JP2020183708A - Variable valve mechanism of internal combustion engine - Google Patents

Abstract

To make a second locker arm hardly fall down when a first locker arm is displaced in a locker shaft longitudinal direction.SOLUTION: A variable valve mechanism 1 includes a first locker arm 10 which oscillates by being pushed by a cam 3, and a second locker arm 45 which oscillates by being pushed by the first locker arm 10. A base end part of the first locker arm 10 is supported by a locker shaft 9 so as to be displaceable in a locker shaft longitudinal direction. A base end part of the second locker arm 45 is supported by a pivot 46, and a pad part 48 for pressing a valve V is arranged at a tip part of the second locker arm 45. When the first locker arm 10 is displaced in the locker shaft longitudinal direction, the oscillation of the first locker arm 10 is changed, and the oscillation of the second locker arm 45 is also changed. The center of gravity G of the second locker arm 45 is located below a virtual tangent L which is drawn to the pad part 48 from a center P of a spherical part of the pivot 46.SELECTED DRAWING: Figure 6

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. 7 (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 rocker shaft length direction according to the selected spiral grooves 54 and 55, and the cam 53 abuts on the roller 59 or It is a mechanism that switches whether or not to abut and changes the swing of the rocker arm body 57.

JP-A-2014-224496

In the variable valve mechanism 51 described above, it is necessary to provide a roller guide 63 that holds the side surface of the roller 59 (which is a separate part from the rocker arm body 57) so as to be displaced in the axial length direction together with the link arm 60. Therefore, the structure was complicated.

Therefore, in the present applicant, not only the roller 59 is displaced in the rocker shaft longitudinal direction with respect to the rocker arm main body 57, but the rocker arm is displaced together with the roller in the rocker shaft longitudinal direction, so that the component is different from the rocker arm. We are considering a plan to eliminate the need for roller guides. Further, the rocker arm of the same plan is used as the first rocker arm, and a second rocker arm that is pressed by the first rocker arm and swings is provided below the first rocker arm, and the second rocker arm is being considered to be supported by a pivot.

However, in the same plan, when the first rocker arm is displaced in the long direction of the rocker shaft, there is a problem that the second rocker arm in contact with the first rocker arm moves in the long direction of the rocker shaft and easily falls down.

Therefore, an object of the present invention is to make it difficult for the second rocker arm to fall when the first rocker arm is displaced in the longitudinal direction of the rocker shaft.

The present invention
A first rocker arm (10) provided below the cam (3) and pressed by the cam (3) to swing.
A second rocker arm (10) provided below the first rocker arm (10) and pressed by the first rocker arm (10) to swing.
The base end of the first rocker arm (10) is displaceably supported by the rocker shaft (9) in the longitudinal direction of the rocker shaft.
The base end portion of the second rocker arm (45) is supported by the pivot (46), and a pad portion (48) for pressing the valve (V) is provided at the tip end portion of the second rocker arm (45).
When the first rocker arm (10) is displaced in the longitudinal direction of the rocker shaft, the swing of the first rocker arm (10) changes, and the swing of the second rocker arm (45) also changes.
The center of gravity (G) of the second rocker arm (45) is below the virtual tangent (L) drawn from the center of the ball portion (P) of the pivot (46) to the pad portion (48). Variable valve mechanism.

According to the present invention, when the first rocker arm is displaced in the longitudinal direction of the rocker shaft, the second rocker arm can be prevented from falling.

FIG. 1 is a perspective view of the variable valve mechanism of the 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 the first rocker arm and the link arm of the same mechanism, and FIG. 3B is a cross-sectional view of the first rocker arm of the same mechanism cut at the roller position. FIG. 4A is a side sectional view of the mechanism cut at the boundary position between the first 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 front views of the mechanism, where FIG. 5A shows when the roller is displaced to the first cam position, and FIG. 5B shows when the roller is displaced to the second cam position. FIG. 6A is a front view and a side sectional view of the second rocker arm of the same mechanism, and FIG. 6B is a front view and a side sectional view of the second rocker arm of the comparative example. 7A and 7B show a conventional variable valve mechanism, where FIG. 7A is a perspective view and FIG. 7B is a cross-sectional view.

1. 1. First Rocker Arm The first rocker arm may include rollers with which the cams come into contact. The number of rollers may be one or a plurality, but two on the left and right are preferable in terms of left-right balance.

2. The number of the second rocker arms may be one or a plurality, but two left and right are preferable in terms of left-right balance.
The second rocker arm may include a roller with which the first rocker arm abuts.

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.
The variable valve mechanism 1 of the embodiment shown in FIGS. 1 to 6 (a) is
A first rocker arm 10 provided below the cam 3 and pressed by the cam 3 to swing.
A second rocker arm 10 provided below the first rocker arm 10 and pressed by the first rocker arm 10 to swing is included.
The base end of the first rocker arm 10 is supported by the rocker shaft 9 so as to be displaceable in the longitudinal direction of the rocker shaft.
The base end portion of the second rocker arm 45 is supported by the pivot 46, and a pad portion 48 for pressing the valve V is provided at the tip end portion of the second rocker arm 45.
A variable valve mechanism in which when the first rocker arm 10 is displaced in the longitudinal direction of the rocker shaft, the swing of the first rocker arm 10 changes and the swing of the second rocker arm 45 changes.
The center of gravity G of the second rocker arm 45 is below the virtual tangent line L drawn from the center P of the ball portion of the pivot 46 to the pad portion 48.

When the first rocker arm 10 is displaced in the longitudinal direction of the rocker shaft, the swing of the first rocker arm 10 changes, and the swing of the second rocker arm 45 changes as follows.
The camshaft 2 is provided with a cam 3 and two spiral grooves 5 and 7.
A first 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. It is switched whether the cam 3 abuts or does not abut.
The roller 16 is positioned so as not to be substantially displaced relative to the rocker shaft 9 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 first rocker arm 10 to be displaced together with the roller 16 in the long direction of the rocker shaft.
As described above, when the first rocker arm 10 is displaced in the longitudinal direction of the rocker shaft, the swing of the first rocker arm 10 changes depending on whether the cam 3 abuts or does not abut on the roller 16, and the second rocker arm 45 The swing of is also changed.

When the cam 3 does not abut on the roller 16, another cam does not abut on the roller, another zero-lift circular cam abuts on the roller, and a cam with another nose profile hits the roller. Although the contacting mode can be exemplified, in this embodiment, the cam 4 having another nose profile comes into contact with the roller.

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. The left and right sides of FIG. 2 viewed from the rear side appear opposite to those of 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.

[First rocker arm]
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 first 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 first rocker arm 10 is a dual type first 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 first rocker arms 11 and 12 have a base portion 14 that is fitted onto the rocker shaft 9 and supported as described above, a pair of side wall portions 17, 17 separated in the axial length direction, and a pair of side wall portions 17, Includes a bottom 18 connecting the bottoms of the 17. Since the left-right length of the first rocker arm 10 is smaller than that between the two cam supports 27, the first 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 first rocker arms 11 and 12 have a roller shaft 15 bridged between the pair of side wall portions 17 and 17, and a shaft that can rotate around the roller shaft 15 via a needle roller. Includes the worn rollers 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. ..

[Second rocker arm]
The second rocker arm 45 is a roller rocker arm, the base end portion in the length direction is supported by the pivot 46, the roller 47 is rotatably attached to the middle portion in the length direction, and the valve V is pressed against the tip end portion in the length direction. A pad portion 48 is formed. Two second rocker arms 45 are provided side by side below the first rocker arm 10, and each roller 47 is pressed by the lower surface of the swinging first rocker arm 10. By this pressing, the second rocker arm 45 swings and presses the valve V.

As shown in FIG. 6A, the center of gravity G of the second rocker arm 45 is below the virtual tangent line L drawn from the center P of the ball portion of the pivot 46 to the pad portion 48 and is low. Therefore, when the first rocker arm 10 is displaced in the long direction of the rocker shaft, the second rocker arm 45 is difficult to move in the long direction of the rocker shaft, and thus is hard to fall down.
On the other hand, as in the second rocker arm 45'of the comparative example shown in FIG. 6B, the center of gravity G'is drawn from the virtual tangent line L'drawn from the ball center P'of the pivot 46' to the pad 48'. If it is too high, when the first rocker arm 10'is displaced in the long direction of the rocker shaft, the second rocker arm 45'moves in the long direction of the rocker shaft and easily falls down.

[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 first rocker arm 10, and can be displaced in the axial length direction together with the first rocker arm 10 and the roller 16.

The thrust position on the d1 side of the first 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 of 16 is also determined. In other words, the side surface of the cam support 27 (or cam cap 28) regulates the displacement end of the first rocker arm 10 on the d1 side in the axial length direction in the thrust direction.
The thrust position on the d2 side of the first 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 of 16 is also determined. In other words, the side surface of the cam support 27 (or cam cap 28) regulates one end in the thrust direction of the first rocker arm 10 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 first 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. , The concave catch 34 formed on the base 14 of the left rocker arm 11 to which the convex latch 33 engages.
The urging structure 30 that urges the first 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. , The concave catch 34 formed on the base 14 of the right rocker arm 12 to which the convex latch 33 engages.
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 first 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 first rocker arm 10 to each thrust position. Since the first rocker arm 10 is held at each thrust position by this urging, it is assumed that 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. However, the first rocker arm 10 and the link arm 20 are not 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 first 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 first rocker arm 10 is determined by the contact between the first rocker arm 10 and the cam support 27, and the urging structure 30 urges the first rocker arm 10 to the thrust position.

Then, the roller 16 is pressed by the second cam 4, the first rocker arm 10 swings, the second rocker arm 45 swings, and two valves V are simultaneously lifted 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 first 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 first rocker arm 10 is determined by the contact between the first rocker arm 10 and the cam support 27, and the urging structure 30 urges the first rocker arm 10 to the thrust position.

Then, the roller 16 is pressed by the first cam 3, the first rocker arm 10 swings, the second rocker arm 45 swings, and two valves V are simultaneously lifted with a high lift and a narrow working angle. This valve operating mode is mainly used in the high speed rotation range.

According to this embodiment, the following effects can be obtained.
(A) The thrust positions of the first rocker arm 10 and the roller 16 are set by a small number of members (the first 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. By deciding, the durability of the spiral grooves 5 and 7 and the engaging arms 23 and 24 can be improved, and the accuracy of the thrust position can be improved and the variation can be reduced by the small number of the members. In addition, the small number of the members makes it possible to reduce costs by relaxing the tolerance of the members.
(A) It is possible to prevent the link arm 20 from being displaced to an unintended position at a timing when neither of the two engaging arms 23 and 24 engages with the spiral grooves 5 and 7.
(C) The structure is simplified because it is not necessary to provide a roller guide that holds the side surface of the roller (which is a separate part from the first rocker arm) as in the conventional example so as to be displaced in the axial length direction together with the link arm. To do.
(D) The roller shaft 15 provided on the first rocker arm 10 can be shortened to substantially the same as the roller width. When the roller shaft 15 is short as described above, when a load is input to the roller 16, the deflection of the roller shaft 15 is small, so that the mechanical rigidity is improved.
(E) Since the center of gravity G of the second rocker arm 45 is lower than the virtual tangent line L drawn from the center P of the ball portion of the pivot 46 to the pad portion 48, the first rocker arm 10 is displaced when it is displaced in the longitudinal direction of the rocker shaft. The two rocker arm 45 does not easily fall over.

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.
(2) The number of rollers included in the first rocker arm 10 may be one or a plurality, but two on the left and right are preferable in terms of left-right balance.
(3) The rotating device is not particularly limited, and examples thereof include a hydraulic mechanism, an electric motor mechanism, and the like, in addition to the electromagnetic solenoid.

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 1st 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 45 Second rocker arm 46 Pivot 47 Roller 48 Pad part G Center of gravity of second rocker arm L Virtual Radial P Pivot bulb center V valve

Claims (1)

A first rocker arm (10) provided below the cam (3) and pressed by the cam (3) to swing.
A second rocker arm (10) provided below the first rocker arm (10) and pressed by the first rocker arm (10) to swing.
The base end of the first rocker arm (10) is displaceably supported by the rocker shaft (9) in the longitudinal direction of the rocker shaft.
The base end portion of the second rocker arm (45) is supported by the pivot (46), and a pad portion (48) for pressing the valve (V) is provided at the tip end portion of the second rocker arm (45).
When the first rocker arm (10) is displaced in the longitudinal direction of the rocker shaft, the swing of the first rocker arm (10) changes, and the swing of the second rocker arm (45) also changes.
The center of gravity (G) of the second rocker arm (45) is below the virtual tangent (L) drawn from the center of the ball portion (P) of the pivot (46) to the pad portion (48). Variable valve mechanism.

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