JP2000337115A - Valve system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the occurrence of seizure and wear due to the deviated load of the inner peripheral edge of a locker arm base part and the outer peripheral surface of a control cam by preventing the occurrence of falling phenomenon in the direction of the width of a locker arm base part as raising of the level of a device is suppressed. SOLUTION: The drive cam 15 and the oscillation cam 17 of a drive shaft 13 are caused to link together through a link arm 24, a locker arm 23, and a link rod 25. By sliding the cam surface 22 of the oscillation cam over the upper surface of a valve lifter 16, a suction valve 12 is opened and closed. Further, one end part 23b of the locker arm is extended axially of a control shaft along a base part 23a and a notch space part 34 extending along a direction orthogonally to the control shaft is formed in a central position in a longitudinal direction between one end part and a base part. The other end part 24b of a link arm situated in the notch space part 34 is supported in a center impeller-form state through a coupling pin 26 at the fork portions on the two sides of the notch space part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve device for an internal combustion engine, and more particularly, to open and close an engine valve by a swing cam which swings in a predetermined angle range from a drive cam via a transmission mechanism such as a link arm or a rocker arm. The present invention relates to a valve train for an internal combustion engine.

[0002]

2. Description of the Related Art The opening and closing timing of intake and exhaust valves is required to improve fuel efficiency at low engine speed and low load, to ensure stable driving performance, and to secure sufficient output by improving intake charging efficiency at high speed and high load. Various valve operating devices for variably controlling the valve lift amount according to the operating state of the engine have been conventionally provided, and as an example, Japanese Patent Application Laid-Open No. H11-107725.
There is one described in the gazette of the issue.

[0003] Briefly referring to FIGS. 6 and 7, a pair of intake valves 52 slidably provided on a cylinder head 51 via a valve guide (not shown) and a bearing 53 above the cylinder head 51 will be described. A drive shaft 54 rotatably supported by the engine and transmitting torque from a crankshaft of the engine; and two drive cams 55 fixed at a center eccentric with respect to the axis of the drive shaft 54 by a predetermined amount. Similarly, it is swingably supported by the drive shaft 54 and slidably contacts the upper surface of a valve lifter 56 provided at the upper end of each intake valve 52 so that each intake valve 52 is pressed by a relative pressure with the spring force of a valve spring 57. An oscillating cam 58 for opening and closing operation, and an eccentric rotation of the driving cam 55 interposed between the oscillating cam 58 and the driving cam 55 for oscillating cam 58
Transmission mechanism 59 for transmitting and swinging to the
And a variable mechanism 60 for changing the swing position of the swing cam 58 with respect to the upper surface of the valve lifter through the valve to vary the valve lift characteristics.

The transmission mechanism 59 includes a link arm 61 in which a fitting hole 61 c of a substantially annular base end 61 a is rotatably fitted on an outer peripheral surface of a driving cam 55, and a control shaft provided on an upper end of the bearing 53. One end 62b projecting from one side of the front end of the central side base 62a is swingably supported via a center 67.
Arm 62, which is rotatably connected to the rocker arm 62, two ends 64 a, 64 b of the rocker arm 62, one end 62 b of the rocker arm 62, a diagonally opposite end 62 c, and a cam nose 58 a of the swing cam 58 via pins 65, 66, respectively. And a link rod 64 connected so as to be relatively rotatable.

The variable mechanism 60 includes a control shaft 67 whose rotational position is controlled by an actuator (not shown),
The center P1 is set on the outer periphery of the control shaft
And an eccentricity control cam 68 slidably provided in a cam hole 62d of a base 62a of the rocker arm 62.

When the drive shaft 54 and the drive cam 55 start to rotate when the engine is started, the eccentric rotational force of the drive cam 55 causes the link arm 61 to move up and down, whereby the rocker arm 62 moves through the cam hole 62d. It swings around the control cam 68 as a fulcrum.
4, the swing cam 58 swings up and down in the figure to push or release the valve lifter 56 downward by the cam surface 58b to open and close the intake valve 52.

[0007] In addition, the control shaft 6
By rotating the control cam 68 eccentrically by rotating a predetermined amount, the swing fulcrum P1 of the rocker arm 62 is changed.
As a result, the swing cam 58 changes the swing fulcrum position on the upper surface of the valve lifter 56 to the left or right in the drawing via the link rod 64, and thereby the intake valve 52
The size of the valve lift characteristics can be varied.

[0008]

However, in the above-described conventional valve train, the rocker arm 62 is bent in a substantially crank shape as shown in FIG.
2b and 62c are formed at diagonal positions of the front and rear ends of the central base 62a, and the other ends 61b of the link arm 61 are connected to the ends 62b and 62c via the connecting pins 63 and 65, respectively.
b and one end 64a of the link rod 64 are supported in a cantilevered state. Accordingly, the input load transmitted from the driving cam 55 to the one end portion 62b of the rocker arm 62 via the link arm 61 during the opening operation of the intake valve 52 is at the position A shown in FIG. 57, the other end 6 of the rocker arm 62 via the valve lifter 56, the swing cam 58 and the link rod 64.
The input load transmitted to 2c is at the point B shown in FIG.

For this reason, the intersection point C between the line segment connecting the two points A and B and the center of the control cam 68 which is the rocking fulcrum of the rocker arm 62 is the load point of the fulcrum, and this load point C is the rocker arm. The driving cam 55 within the load width W of the base portion 62a.
The position is offset toward the outer end.

Therefore, when each of the input loads acts on each of the ends 62b and 62c of the rocker arm 62, a tilting phenomenon occurs around the load point c on the base 62a, and the cam hole 62
Due to the uneven load applied to the hole edge on the load point C side of d against the outer peripheral surface of the control cam 68, seizure or wear may occur between the two.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the actual situation of the valve train according to the prior application.
According to the invention described above, a drive shaft rotatably driven by a crankshaft of an engine, a drive cam fixed to an outer periphery of the drive shaft, a center of which is deviated from an axis of the drive shaft by a predetermined amount, and one end portion of the outer periphery of the drive cam A link arm rotatably linked to the base and a base on the center side are swingably supported by a support shaft, and one end protruding from the base is rotatably connected to the other end of the link arm via a connection pin. A rocker arm linked to the rocker arm and a rocking cam pivotally linked to the other end of the rocker arm to open and close the engine valve while the cam surface is in sliding contact with a follower portion provided at the upper end of the engine valve. In the valve gear for an internal combustion engine, one end of the rocker arm extends in the axial direction of the support shaft along a base, and a cutout space portion is formed in the one end and the base along a direction orthogonal to the support shaft. And arranged in the notch space. The other end of the link arms,
The bifurcated portion on both sides of the cutout space portion is supported in a double-supported state via the connection pin.

According to this invention, a notch space is provided at the base or one end of the rocker arm extending in the direction of the support shaft, and the other end of the link arm is provided with a connecting pin at the forked portion on both sides of the notch space. Since it is supported in a double-supported state through the intermediary, the driving load point from the driving cam or the valve spring can be positioned closer to the center in the longitudinal direction of the base of the rocker arm. Therefore, the rocker arm base can be prevented from falling down.

The invention according to claim 2 is characterized in that the notch space is formed at a substantially central position in the longitudinal direction between the base and one end of the rocker arm.

Therefore, since the driving load point of the driving cam or the like with respect to the rocker arm can be moved to the center of the base, the effect of preventing the rocker arm from falling can be further promoted.

According to a third aspect of the present invention, the connecting portion for connecting the forked portions is formed over substantially half the circumference of the base located on the side opposite to one end of the rocker arm.

According to the present invention, even when the notch space is formed in the rocker arm, the cross-sectional area of the connecting portion is made sufficiently large, so that the joint rigidity at the forked portion can be prevented from lowering.

According to a fourth aspect of the present invention, the swing support point of the rocker arm is changed through a control cam rotatably provided between the support shaft and the base, thereby providing a follower for the swing cam. And a variable mechanism for changing a valve lift characteristic by changing a relative position with respect to a notch space portion of the base of the control cam and a rotation of the other end of the link arm together with the notch space portion. It is characterized in that a notch portion allowing movement is formed.

Therefore, the notch is also formed in the control cam, so that the other end of the link arm is arranged and absorbed in the notch, so that a so-called relief space is enlarged. Therefore, the height of the rocker arm and the control cam is increased. It is not necessary, and the restriction on the degree of freedom of layout in the engine room can be prevented.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the valve train according to the present invention will be described below in detail with reference to FIGS. The valve gear of this embodiment is provided with two intake valves per cylinder, as in the prior application, and with a variable mechanism that varies the valve lift of the intake valves according to the engine operating state. ing.

That is, this valve gear is rotatably mounted on a pair of intake valves 12 and 12 slidably provided on a cylinder head 11 via a valve guide (not shown) and a bearing 14 on the upper part of the cylinder head 11. Supported hollow drive shaft 1
3, two drive cams 15, 15 which are eccentric rotary cams fixed to the drive shaft 13 by press fitting or the like;
Valve lifters 16, 16, which are swingably supported on the upper ends of the respective intake valves 12, 12, are followers.
Slidably in contact with the flat upper surfaces 16a, 16a of the intake valves 12,
Oscillating cams 17 and 17 for opening and closing the drive cam 1
And a transmission mechanism 18 which is linked between the oscillating cams 5 and the oscillating cams 17 and 17 to transmit the rotational force of the drive cam 15 as the oscillating power of the oscillating cams 17 and 17, and variably changes the operating position of the transmission mechanism 18 And a variable mechanism 19 that performs the operation.

The drive shaft 13 is disposed along the longitudinal direction of the engine, and is driven by a crank of the engine via a driven sprocket (not shown) provided at one end and a timing chain wound around the driven sprocket. Rotational force is transmitted from the shaft, and the rotation direction is set clockwise (the direction of the arrow) in FIG.

As shown in FIG. 2, the bearing 14 is provided at an upper end of the cylinder head 11 to support an upper portion of the drive shaft 13, and is provided at an upper end of the main bracket 14a to be described later. And a sub-bracket 14b for rotatably supporting the control shaft 32 to be rotated.
They are fixed together from above by c.

The two driving cams 15 have a substantially ring shape as shown in FIGS. 1 to 3, and have a small diameter cam body 15a,
A flange portion 15b integrally provided on an outer end surface of the cam body 15a, and a drive shaft insertion hole 15c extending in an inner axial direction.
Are formed to penetrate and the axis X of the cam body 15a is formed.
Are offset from the axis Y of the drive shaft 13 in the radial direction by a predetermined amount. Each of the drive cams 15 is
, Which are press-fitted and fixed on both outer sides not interfering with the two valve lifters 16, 16 via drive shaft insertion holes 15c, and the outer circumferential surfaces 15 of both cam bodies 15a, 15a.
d and 15d are formed in the same cam profile.

The oscillating cam 17 has a substantially horizontal raindrop shape as shown in FIG.
3, a support hole 20a is formed through which a rotatable support is formed, and a pin hole 21a is formed through a cam nose portion 21 at one end. In addition, the swing cam 1
7, a cam surface 22 is formed on the lower surface, a base circular surface 22a on the base end portion 20 side, a ramp surface 22b extending in an arc shape from the base circular surface 22a to the cam nose portion 21 side, and a distal end side of the ramp surface 22b. Is formed, the base surface 22a, the ramp surface 22b and the top surface 22c are formed.
Are brought into contact with predetermined positions of the upper surface 16a of each valve lifter 16 in accordance with the swing position of the swing cam 17. The swing cam 17 is moved from the base circular surface 22a to the top surface 22a.
The swing direction on the cam lift side that slides in the direction c is set to the same direction as the rotation direction of the drive shaft 13.

The transmission mechanism 18 includes a rocker arm 23 disposed above the drive shaft 13 as shown in FIG. 1, a link arm 24 for linking one end 23b of the rocker arm 23 and the drive cam 15, and a rocker arm 23. Other end 2 of
A link rod 25 for linking the swing cam 17 with the swing cam 3c is provided.

As shown in FIG. 4, each of the rocker arms 23 has a cylindrical base 23a rotatably supported by a control cam 33 to be described later through a cam hole 23f, and a cylindrical base 23a.
one end 23b and the other end 23 projecting from the front and rear ends
The cylindrical base 23a is extended to a predetermined length W along the axial direction of the control shaft 32, which will be described later, and the one end 23b is the same along the edge of the base 23a. It is extended to the length. A cutout space portion 34 is formed substantially at the center of the base portion 23a and the one end portion 23b in the longitudinal direction along the direction perpendicular to the axis of the control shaft 32. Further, both sides of the notch space portion 34 are formed at the forked portions 35a and 35b. The bifurcated portions 35a and 35b are joined at their upper ends via a connecting portion 36, and the connecting portion 36 is formed over substantially half the circumference of the base portion 23a as shown in FIG. The cross-sectional area is set relatively large.

The bifurcated portions 35a, 35b are formed with pin holes 23d, 23d into which both ends of a connecting pin 26 for connecting the other end 24b of the link arm 24 are press-fitted. The portion 24b is fitted and disposed inside the cutout space portion 34 and is supported by the forked portions 35a and 35b via the connecting pin 26 in a double-supported state. On the other hand, the other end 23c of the rocker arm 23 is provided with a pin 2 that is rotatably connected to one end 25a of the link rod 25.
A pin hole 23e into which the wire 7 is press-fitted is formed.

The link arm 24 has an annular base 24a having a relatively large diameter and a protruding end 24b projecting from a predetermined position on the outer peripheral surface of the base 24a. A fitting hole 24c rotatably fitted to the outer peripheral surface of the cam body 15a of the driving cam 15 is formed, while a pin hole 24d through which the pin 26 is rotatably inserted penetrates the protruding end 24b. Is formed.

As shown in FIG. 1, the link rod 25 has a flat plate shape having a predetermined length, and is formed by bending the center of the link rod into a substantially rectangular shape. The rocker arms 25a and 25b have circular ends. 23 and the swing cam 17
Pin insertion holes 25 into which the ends of the pins 27, 28 pressed into the pin holes 23e, 21a of the end portion 21 are rotatably inserted.
c, 25d are formed through. In addition, lightening portions 25c are provided on both side surfaces of the link rod 25 in order to reduce the weight.
Are formed along the longitudinal direction.

At one end of each of the pins 27 and 28, snap rings 30 and 31 for restricting the axial movement of the link arm 24 and the link rod 25 are provided.

The variable mechanism 19 includes a control shaft 32 rotatably supported by the same bearing 14 at a position above the drive shaft 13.
And the rocker arm 23 fixed to the outer periphery of the control shaft 32.
And a control cam 33 serving as a rocking fulcrum of the control.

The control shaft 32 extends in parallel with the drive shaft 13 and is controlled by an electromagnetic actuator (not shown) provided at one end so as to rotate within a predetermined rotation angle range. Are driven by a control signal from a controller (not shown) that detects the operating state of the engine. The controller detects a current engine operation state by calculation or the like based on detection signals from various sensors such as a crank angle sensor, an air flow meter, and a water temperature sensor, and outputs a control signal to the electromagnetic actuator.

Each of the control cams 33 has a columnar shape, and the position of the axis P1 is deviated from the axis P2 of the control shaft 32 by α as shown in FIG. L is set substantially equal to the width W of the base 23a of the rocker arm 23. As shown in FIG. 5, the control cam 33 is provided with a notch space portion 34 of the rocker arm 23.
A notch 37 is formed at a central position corresponding to.
The notch 37 has the same depth as the outer diameter of the control shaft 32 and the same width as the width of the notch 34. The notch 37 cooperates with the notch space 34 to form the other end 24b of the link arm.
And free rotation are allowed.

In the following, the operation of the present embodiment will be described. First, at the time of starting the engine and at the time of low rotation and low load, the electromagnetic actuator is driven to rotate in one direction by a control signal from the controller which has detected the operation of the engine. The control shaft 32 rotates the control cam 33 to the position shown in FIG.
Is rotated to the lower left. For this reason, the rocker arm 23
The pivot fulcrum center P1 moves to the left as shown, and the other end 23b is moved to the cam nose 21 of the oscillating cam 17.
Is slightly lifted upward via the link rod 25, and the entire swing cam 17 is rotated by a predetermined amount to the position shown in the counterclockwise direction in the drawing.

In this state, the swing operation of the swing cam 17, that is, the cam lift operation of the swing cam 17 by the driving cam 15 and the transmission mechanism 18 will be described. First, as shown in FIG. 22a is the upper surface 1 of the valve lifter 16
When it is located at 6a, it is in the base circle area and the intake valve 12 is in the closed operation state.

From this state, the link arm 24 moves to the upper left with the rotation of the drive cam 15, and pushes up one end 23a of the rocker arm 23. Therefore, the rocker arm 23 swings clockwise as shown in the drawing, and presses the link rod 25 downward at the other end 23b, whereby the swing cam 17 swings clockwise, thereby starting a cam lift. It becomes a lift up section. from here,
When the drive cam 15 further rotates, the swing cam 17 swings clockwise, and reaches the maximum lift when the top surface 22c comes into contact with the upper surface 16a of the valve lifter 16. When the drive cam 15 further rotates, the swing cam 17 reverses to enter a lift down section, and further swings in the same direction to the base circle area (valve closed area) shown in FIG.

Therefore, the valve lift characteristic of the intake valve 12 is a small lift characteristic, so that the gas flow of the intake air is strengthened and the fuel efficiency is improved.

On the other hand, when the engine shifts to the engine high-speed / high-load range, the electromagnetic actuator is further driven to rotate by the control signal from the controller. Therefore, the control shaft 32 rotates the control cam 33 clockwise, and the shaft center P1 ( The thick part 33a) is moved to the upper left position in FIG. For this reason,
The entire rocker arm 23 moves in the direction of the drive shaft 13 (downward), and presses the cam nose portion 21 of the other end portion 23c of the rocking cam 17 downward via the link rod 25, whereby the entire rocking arm 17 is moved. Is rotated clockwise by a predetermined amount.
Therefore, the valve lifter upper surface 16a of the swing cam 17
The contact position of the cam surface 22 moves rightward. For this reason, when the drive cam 15 rotates and pushes up one end 23 a of the rocker arm 23 via the link arm 24,
The lift amount of the valve lifter 16 becomes large.

Therefore, in such a high-speed, high-load region, the cam lift characteristics are larger than those in the low-speed, low-load region, the valve lift is increased, and the opening timing of each intake valve 12 is advanced and the closing timing is delayed. Become. As a result, the intake charging efficiency is improved and a sufficient output is obtained.

As described above, in this embodiment, each intake valve 1
Of course, the opening / closing timing and valve lift amount of the rocker arm 23 can be made variable, and the base 23a and one end 2
3b is extended in the direction of the control shaft 32 to increase the bearing width with respect to the control cam 33. Further, the other end 24b of the link arm 24 is substantially bifurcated at the center of the one end 23b of the rocker arm 23 in the longitudinal direction. b, the input load due to the rotational force of the drive cam 15 and the input load due to the spring reaction force of the valve spring during the operation of the device, as shown in FIG. 3, in the width direction of the base 23a. It can be received at the Z point substantially at the center of the upper end.

As a result, the phenomenon of the rocker arm 23 falling down in the width direction is reliably avoided, and the entire cam surface 23f having a large surface area of the base portion 23a always slides on the outer peripheral surface of the control cam 33. Therefore, the cam hole 2 of the base 23a
It is possible to effectively prevent the occurrence of seizure and abrasion due to an uneven load between the inner peripheral edge of the 3f and the outer peripheral surface of the control cam 33.

Further, since the connecting portion 36 is formed large even if the notch space portion 34 is formed in the base portion 23a, the coupling rigidity of the forked portions 35a and 35b is prevented from being reduced. Not only does vibration not occur, but the effect of preventing the base 23a from falling down is further promoted.

In addition to the notch space 34 at the base 23a and one end 23b, a notch 37 is also formed at the control cam 33 to increase the so-called clearance space. The rocker arm 23 and the control cam 33 can be restrained from being raised higher than the notch 37. As a result, the layout in the engine room is improved, and it is not necessary to increase the height of the engine hood.

[0044]

As is apparent from the above description, claim 1
According to the invention described above, the input load due to the rotational force of the drive cam and the input load due to the spring reaction force of the valve spring during operation of the device are substantially at the center of the upper end of the rocker arm base in the width direction, that is, substantially at the center of the connecting portion. Can be received at a location. As a result, it is possible to reliably prevent the rocker arm base from falling down in the width direction. Therefore, it is possible to effectively prevent the occurrence of seizure or wear due to the uneven load between the inner peripheral edge of the rocker arm base and the outer peripheral surface of the control cam.

According to the second aspect of the present invention, the driving load point of the driving cam or the like with respect to the rocker arm can be moved toward the center of the base, so that the effect of preventing the rocker arm from falling can be further promoted.

According to the third aspect of the present invention, since the connecting portion is formed to be large in the circumferential direction even if the notch space portion is formed in the base portion, the joint rigidity at the forked portion is prevented from being reduced, and the large portion is provided at the base portion. Even if an input load is applied, not only breakage or vibration does not occur, but also the effect of preventing the base from falling down can be further promoted.

According to the fourth aspect of the present invention, not only a notch space is formed at the base and one end of the rocker arm, but also a notch is formed in the control cam so that a so-called relief space is enlarged. The other end can be disposed deeply in the notch and absorbed. Therefore, the height of the rocker arm and the control cam can be suppressed, and as a result, the height of the device can be prevented while preventing the rocker arm from falling down.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along the line AA of FIG. 2 showing one embodiment of the present invention.

FIG. 2 is a side view of the embodiment.

FIG. 3 is a plan view of the embodiment.

FIG. 4 is a perspective view showing a rocker arm provided in the embodiment.

FIG. 5 is a perspective view showing a control cam provided in the embodiment.

FIG. 6 is a cross-sectional view showing a valve train according to the prior application.

FIG. 7 is a plan view of a main part of the valve train of the prior application.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Cylinder head 12 ... Intake valve 13 ... Drive shaft 15 ... Driving cam 16 ... Valve lifter 17 ... Swing cam 18 ... Transmission mechanism 19 ... Variable mechanism 22 ... Cam surface 23 ... Rocker arm 23a ... Base 23b, 23c ... Both ends 23d ... Pin hole 24 ... Link arm 24a ... Basic end 24b ... Protrusion end 25 ... Link rod 25a, 25b ... Ends 26 ... Connecting pin 34 ... Notch space 35a, 35b ... Forked part 36 ... Connection part 37 ... Notch

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Katsuya Mogi 2nd Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 3G016 AA06 AA19 BA03 BA23 BA37 BB04 CA02 CA13 CA21 CA22 CA26 CA27 CA29 CA32 CA33 CA47 CA48 CA52 CA57 FA29 GA00 GA02

Claims (4)

[Claims] A drive shaft rotatably driven by a crankshaft of an engine; a drive cam fixed to an outer periphery of the drive shaft, a center of which is deviated by a predetermined amount from an axis of the drive shaft; A link arm rotatably linked to the base and a base on the center side are swingably supported by a support shaft, and one end protruding from the base is rotatably connected to the other end of the link arm via a connection pin. A rocker arm linked to the rocker arm and a rocking cam pivotally linked to the other end of the rocker arm to open and close the engine valve while the cam surface is in sliding contact with a follower portion provided at the upper end of the engine valve. In the valve train for an internal combustion engine, one end of the rocker arm extends in the axial direction of the support shaft along a base, and a cutout space is formed in the one end and the base in a direction perpendicular to the support shaft. Part in the notch space The other end of the link arm that is location, valve operating system for an internal combustion engine, characterized in that supported on both ends with each other through the connecting pin to the bifurcated portion of the cut-out space on both sides. 2. The valve train for an internal combustion engine according to claim 1, wherein the notch space portion is formed at a substantially central position in a longitudinal direction between a base portion and one end portion of the rocker arm. 3. The dynamics of an internal combustion engine according to claim 1, wherein the connecting portion connecting the forked portions is formed over substantially a half circumference of a base located on the opposite side to one end of the rocker arm. Valve device. 4. A relative position of the rocking cam with respect to a follower is changed by changing a rocking fulcrum of the rocker arm through a control cam rotatably provided between the support shaft and a base. A variable mechanism for varying the valve lift characteristics, and a notch portion allowing rotation of the other end of the link arm together with the notch space at an outer peripheral position corresponding to the notch space at the base of the control cam. The valve train for an internal combustion engine according to any one of claims 1 to 3, wherein the valve train is formed.