JP2000291418A - Variable valve train for internal combustion engines - Google Patents

Abstract

(57) [Problem] To improve the detection accuracy by directly detecting the rotational position of a swing cam (18) that actually presses a valve lifter (20). SOLUTION: When a drive shaft 16 is rotated in synchronization with rotation of an engine, an oscillating cam externally fitted on an outer periphery of the drive shaft 16 via an eccentric cam 28, a ring-shaped link 30, a rocker arm 26, and a rod-shaped link 32. 18 swings and the intake / exhaust valve 12
To open and close. When the rotation of the control shaft 22 is controlled, the position of the control cam 24, which is the center of swing of the rocker arm 26, changes, and the valve lift characteristics are variably controlled. Swing cam 18
A pair of cam lobes 60 slidingly contacting the valve lifter 20;
62 are provided. A step recessed radially inward is provided on the outer peripheral surface of one cam lobe 62, and this step is used as a target 72 detected by a rotation position detection sensor attached to the cylinder head 14 side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve operating apparatus for an internal combustion engine, which can change the opening / closing timing of an intake / exhaust valve and the valve lift amount according to the operating state of the engine. About technology.

[0002]

2. Description of the Related Art Conventionally, there have been proposed various variable valve operating devices that variably control the opening / closing timing and operating angle of intake valves and exhaust valves in accordance with the operation state of an internal combustion engine. Techniques for detecting how the actual valve lift characteristics are controlled in this type of variable valve operating device have been proposed.

As an example, FIG. 15 shows a variable valve apparatus for an internal combustion engine described in Japanese Patent Application Laid-Open No. 8-260923. In this variable valve operating device, an annular disk 3 is interposed between a flange portion of a sleeve connected to a drive shaft 1 and a flange portion of a camshaft 2, and when the center thereof is eccentric, rotation becomes non-uniform. The valve lift characteristics change. The disk housing 4 holding the annular disk 3 is supported by the first eccentric cam 5 and the second eccentric cam 6.
When the first eccentric cam 5 is rotationally displaced by the hydraulic actuator 7, the disk housing 4 moves and the annular disk 3 is moved.
Of the eccentricity of the light source changes. At one end of the control shaft 8 of the first eccentric cam 5, a potentiometer 9 for detecting the rotational position of the control shaft 8 is provided.
Is mounted, and an actual valve lift characteristic is estimated based on the rotational position of the control shaft 8.

[0004] A technique similar to this is described in, for example, Japanese Patent Application Laid-Open No. 9-268906.

[0005]

However, in such a conventional variable valve apparatus for an internal combustion engine, the valve opening / closing timing of the intake / exhaust valve is indirectly estimated from the rotational position of the control shaft 8. Due to the configuration, an error is likely to occur between the actual valve opening and closing timing due to the valve reaction force, the clearance of the link mechanism, and the like.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional problem, and directly changes the rotational position of an oscillating cam which is actually slidably brought into contact with an intake / exhaust valve to open and close. Is detected.

That is, the variable valve apparatus for an internal combustion engine according to the first aspect of the present invention slides on a drive shaft that rotates in synchronization with the rotation of the engine and an intake / exhaust valve to open and close the intake / exhaust valve. A swinging cam rotatably fitted to the outer periphery of the drive shaft, a control shaft rotationally controlled within a predetermined control angle range, and a control eccentrically fixed to the outer periphery of the control shaft. A cam, a rocker arm rotatably fitted to the outer periphery of the control cam, an eccentric cam eccentrically fixed to the outer periphery of the drive shaft, and a rocker arm rotatably fitted to the outer periphery of the eccentric cam. A ring-shaped link rotatably connected to one end; a rod-shaped link rotatably connected to both the other end of the rocker arm and the swing cam; and a detecting means for detecting a rotational position of the swing cam. Then on The swing cam, is characterized in that a target detected by said detection means.

With the above arrangement, when the drive shaft rotates in conjunction with the rotation of the engine, the swing cam swings within a predetermined angle range via the eccentric cam, ring link, rocker arm, and rod link. The intake and exhaust valves are respectively opened and closed. Further, by controlling the rotation of the control shaft, the distance between the axis of the control cam, which is the rocking center of the rocker arm, and the axis of the drive shaft changes. As a result, the opening / closing timing of the intake / exhaust valve (actuation) Angle) and the lift amount change. Specifically, the closer the distance between the two axes is, the larger the operating angle and the lift amount are.

As described above, in the present invention, since the swing cam for driving the intake / exhaust valve is rotatably fitted to the outer periphery of the drive shaft, there is a possibility that the center of the swing cam is displaced with respect to the drive shaft. In addition, the members constituting the link mechanism can be integrated around the drive shaft to reduce the size of the device. In addition, since the connecting portions of the members are in surface contact, they have excellent wear resistance and are easy to lubricate.

In the present invention, since the target of the oscillating cam is detected by the detecting means, the rotational position of the oscillating cam that is actually in sliding contact with the intake / exhaust valve can be directly detected. Accordingly, there is no possibility that the detection accuracy is reduced due to an error due to a clearance or the like of each link member, and more accurate variable control of the valve lift characteristic can be performed.

Further, the invention according to claim 2 is characterized in that a step in the radial direction is provided at least on the outer peripheral surface of one cam lobe of the swing cam, and this step is used as the target.

As described above, since the target is formed by the step using the outer peripheral surface of the cam lobe for opening and closing the intake / exhaust valve, the weight and the number of parts are not increased.

More preferably, as in the invention of claim 3,
The detection means is, for example, a rotation position detection sensor attached to the cylinder head in a posture facing the outer peripheral surface of the cam lobe. The cam usage range is such that the target slides or faces the valve lifter of the suction / exhaust valve in the outer peripheral surface of the cam lobe so as not to face or slide against the suction / exhaust valve (valve lifter thereof). It is set at a position outside the range.

According to a fourth aspect of the present invention, the swing cam includes a pair of cam lobes slidingly contacting a valve lifter of the intake / exhaust valve.
A journal portion provided between the two cam lobes and rotatably supported on the cylinder head via a bracket, wherein the target is offset toward the journal portion with respect to the axial center of the cam lobe.

According to the fourth aspect of the present invention, if the swing cam falls down in the axial direction about the journal portion supported on the cylinder head side, the target is moved to the journal portion on which the fall is relatively small. Is located, so that a decrease in the detection accuracy due to the above-described falling can be effectively suppressed.

According to a fifth aspect of the present invention, at least two cam lobes are provided on one swing cam, and the rod-shaped link is connected to one cam lobe, and the target is provided on the other cam lobe. It is characterized by:

That is, since the cam lobe to which the rod-shaped link is connected is relatively large in size and layout is restricted due to the requirement of strength, it is better to provide a target on the other cam lobe if a rotation position detecting sensor or a target is provided. Layout flexibility is increased.

The invention according to claim 6 is characterized in that a target is detected by the detection means before and after the swing cam is pulled up most in the valve closing direction.

In this case, it is possible to detect both the lift start timing and the lift end timing before and after the swing cam is pulled up most in the valve closing direction, that is, during one cycle, by a set of targets and detection means. Even if the control shaft hunts due to the valve reaction force or the inertia force of the link itself in the high engine speed range, the detection is performed before and after the start and end of the lift in which the control shaft runout is relatively small. A decrease in the detection accuracy of the detection sensor can be effectively suppressed.

[0020]

According to the present invention, the target of the oscillating cam which is actually in sliding contact with the intake / exhaust valve is directly detected by the detecting means. As a result, detection can be performed with sufficient accuracy, and the valve lift characteristics can be variably controlled with high accuracy.

In particular, by detecting the swing cam before and after the swing cam is pulled up most in the valve closing direction as in the invention of the sixth aspect, a set of targets and detection means can be used.
It is possible to detect both the start and end timings of the lift. Further, since the detection is performed before and after the start and end of the lift in which the control shaft swing is relatively small, a decrease in the detection accuracy due to the hunting of the control shaft can be effectively suppressed.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 show a first embodiment in which the variable valve apparatus according to the present invention is applied to an internal combustion engine in which each cylinder is provided with a pair of intake valves and a pair of exhaust valves.

A drive shaft 16 extending in the front-rear direction of the engine over all cylinders is provided on an upper portion of the cylinder head 14 on each of an intake valve side and an exhaust valve side. Each drive shaft 16
Has a hollow shape with a lubricating oil passage formed therein, and as shown in FIG. 4, rotates from a crankshaft of the engine via a timing chain 11 wound around a driven sprocket provided at one end thereof. The force is transmitted, and the engine rotates in synchronization with the rotation of the engine.

The intake and exhaust valves 12 (intake valve 12A and exhaust valve 12B) are opened and closed around each drive shaft 16, and the lift characteristics (operating angle and valve lift amount) of the intake and exhaust valves 12 are adjusted. A variable valve device for variably controlling is provided. The configuration of each part of the variable valve apparatus is basically the same on the intake valve side and on the exhaust valve side, and the same reference numerals are used here for explanation.

That is, a hollow shaft-shaped swing cam 18 is rotatably fitted on the outer periphery of each drive shaft 16. The swing cam 18 has a pair of cam lobes 60 and 62 slidably in contact with a valve lifter 20 as a transmission member provided at the upper end of the pair of intake and exhaust valves 12 of each cylinder. -The exhaust valve 12 is opened and closed. A cylindrical journal 64 having a relatively large diameter is provided between the cam lobes 60 and 62.

Above the drive shaft 16, there is provided a control shaft 22, which is rotationally driven within a predetermined control range by an actuator 50 (FIG. 3) or the like, substantially in parallel with the drive shaft 16. An eccentric cylindrical control cam 24 is fixed to the outer periphery of the control shaft 22 by press fitting or the like. This control cam 2
The axis 4 is eccentric with respect to the axis of the control shaft 22 by a predetermined amount. A base of a rocker arm 26 is rotatably fitted around the outer periphery of the control cam 24.

On the other hand, an eccentric cylindrical eccentric cam 28 is fixed to the outer periphery of the drive shaft 16 by press fitting or the like. The axis of the eccentric cam 28 is eccentric with respect to the axis of the drive shaft 16 by a predetermined amount. A base of a ring-shaped link 30 is rotatably fitted around the outer periphery of the eccentric cam 28. The distal end of the ring-shaped link 30 and one end of the rocker arm 26 are connected via a first pin 34 so as to be relatively rotatable.

The other end of the rocker arm 26 and the tip of the swing cam 18 are linked via a rod-like link 32. That is, the other end of the rocker arm 26 and one end of the rod-shaped link 32 are connected to each other via the second pin 36 so as to be relatively rotatable, and the other end of the rod-shaped link 32 and the tip of the swing cam 18 are connected to the third pin. They are connected via a pin 38 so as to be relatively rotatable. More specifically, the third pin 38 is
As shown in FIG. 2, one of the first cam lobes 60 of the swing cam 18, a flange portion 66 protruding radially from the outer periphery of the swing cam 18, and an axial gap between the both 60 and 66. It is inserted over the rod-like link 32.

An upper bracket 40 and a lower bracket 4 as bearings are provided above the cylinder head 14.
2 are fixed by bolts 44. As shown in FIG. 2, the journal 64 of the swing cam 18 is rotatably supported between the upper part of the cylinder head 14 and the lower bracket 42, and the upper bracket 40
The control shaft 22 is rotatably supported between the lower bracket and the lower bracket.

The actuator 50 is fixed to the rear end of the cylinder head 14 via an actuator case 52, as shown in FIG. In the actuator case 52, an output shaft 54 of the actuator 50 is provided.
And a second gear 58 fixed to the rear end of the control shaft 22 on the intake side.
6, 58 mesh with each other.

The actuator 50 rotates and holds the control shaft 22 within a predetermined control angle range, and its operation is controlled by a controller (not shown) that detects the operating state of the internal combustion engine. This controller calculates the operating state of the engine based on detection signals from various sensors such as a crank angle sensor, an air flow meter, a water temperature sensor, and a rotational position detection sensor 70 described later, and the like. The control signal is output to the

Although omitted here, the control shaft 22 on the exhaust valve side also has the actuator 5 similar to the intake valve side.
The driving is controlled by 0 (or other driving means) or the like.

With the above configuration, when the drive shaft 16 rotates in conjunction with the rotation of the engine, the swing cam 18 is moved through the eccentric cam 28, the ring-shaped link 30, the rocker arm 26, and the rod-shaped link 32 within a predetermined angle range. And the intake and exhaust valves 12 are opened and closed, respectively. Further, by controlling the rotation of the control shaft 22 to a predetermined control position, the distance between the axis of the control cam 24, which is the swing center of the rocker arm 26, and the axis of the drive shaft 16 changes. The opening / closing timing (operating angle) and lift of the intake / exhaust valve 12 change. Specifically, the closer the distance between the two axes is, the larger the operating angle and the lift amount are.

As described above, in this embodiment, the intake / exhaust valve 12
Is rotatably fitted to the outer periphery of the drive shaft 16, so that there is no possibility that the center of the swing cam 18 with respect to the drive shaft 16 is displaced. The members can be concentrated around the drive shaft 16 to reduce the size of the device. In addition, since the connecting portions of the members are in surface contact, they have excellent wear resistance and are easy to lubricate.

In this embodiment, a rotation position detection sensor 70 as a detecting means for directly detecting the rotation position of the swing cam 18 is attached to the cylinder head 14, while the rotation position detection sensor 70 is attached to the swing cam 18. A target 72 detected by the sensor 70 is provided.

More specifically, as shown in FIG. 4, the target 72 is a second cam lobe 62 on the engine front side of the swing cam 18 of the # 1 cylinder closest to the engine side (left side in FIG. 4).
That is, it is provided on the second cam lobe 62 different from the first cam lobe 60 to which the driving force is transmitted via the rod-shaped link 32 and the third pin 38.

When the target 72 is provided on the second cam lobe 62 as described above, the size and the size of the target 72 are relatively large due to the demand for strength.
The degree of freedom in the layout of the rotational position detection sensor 70 and the target 72 is greater than when the target is provided on the first cam lobe 60 having a large layout restriction.

Further, the rotational position detecting sensor 70 is shown in FIG.
As shown in FIG. 5, the second cam lobe 62 is mounted on the cylinder head 14 side via a mounting bracket 68 fixed to the lower bracket 42 of the # 1 cylinder, and is mounted when the target 72 crosses. A change in the distance to the outer peripheral surface of the cam lobe 62 is detected.

FIGS. 6A and 6B show the minimum lift state in which the valve lift (and the operating angle) is minimized by controlling the rotation of the control shaft 22. More specifically, the rocker arm 2 is shown in FIGS.
The axis of the control cam 24 serving as the swing center of the drive shaft 6 and the drive shaft 16
Shows the state where the distance from the axis center is the largest,
7C and 7D show the maximum lift state in which the valve lift (and the operating angle) is maximized by controlling the rotation of the control shaft 22, more specifically, the axis of the control cam 24 and the drive shaft 16.
3 shows a state in which the distance from the axis to the center is minimum.
(A) and (c) show the state in which the swing cam 18 is pulled up most in the valve closing direction (clockwise in the figure) with the rotation of the drive shaft 16, and (b) and (d) show the state. , Drive shaft 16
Shows a state where the swing cam 18 is pushed down in the valve opening direction (counterclockwise direction in the figure) with the rotation of.

Here, in the outer peripheral surface of the cam lobe 62, the cam use range R which actually slides on the top surface of the valve lifter 20 and is opposed to the top surface of the valve lifter 20 when the cam lift is most raised in the minimum lift state shown in FIG. From the travel position P1 of FIG. 7 to the travel position P2 of the case where the seat is pushed down the most in the maximum lift state shown in FIG. 8D (see FIG. 8).

In this embodiment, a step which is largely depressed radially inward is provided at a position deviating from the cam use range R by a predetermined amount in the low lift direction (counterclockwise direction in FIG. 8).
This is the target 72. That is, the outer peripheral surface of the second cam lobe 62 is a large-diameter portion 74 having a smooth cylindrical surface forming the cam use range R at the target 72.
And a smooth cylindrical small-diameter portion 76 are provided with a large diameter difference.

Then, the cam lobe 62 is connected to the valve lifter 20.
At the timing of starting to press, as shown in FIG. 8, the target 72 crosses in front of the rotational position detection sensor 70, and the target 72 is set to be detected by the rotational position detection sensor 70. More specifically, as shown in FIG. 7C, the target 72 is set to cross the front of the rotational position detection sensor 70 before and after the swing cam 18 is pulled up in the valve closing direction most.

As a result, as shown in FIG. 9, the target 72 is detected by the sensor 70 immediately after the start and the end of the lift of the intake / exhaust valve 12. 9B shows an output when a gap sensor is used as the rotation position detection sensor 70, and FIG. 9C shows an output when a magnetic sensor is used as the rotation position detection sensor 70. I have. In either case, the output is set to exceed the slice level when crossing the target 72. Then, the operating angle of the intake / exhaust valve 12 with respect to the angle of the drive shaft 16 is calculated based on both outputs immediately after the start of the lift and immediately before the end of the lift.

The size and position of the target 72 are set so that the sensor 70 can reliably detect the target 72 irrespective of the shape of the swing cam 18 and the swing state (illegal movement due to inertia). I have.

As described above, in this embodiment, since the rotational position of the swing cam 18 for actually pressing the valve lifter 20 is directly detected, sufficient detection accuracy can be obtained regardless of the clearance of each link member. As a result, highly accurate variable control of the valve lift characteristics can be performed.

In this embodiment, since the swing cam 18 swings within a predetermined range, both the valve lift start point and the valve lift end point are determined by the swing cam 18.
Is the rotational position in which the valve is most raised in the valve closing direction (Fig. 6
(A), the state of FIG. 7 (c)). Therefore, by setting the target 72 to cross the front of the rotational position detection sensor 70 before and after the swing cam 18 is pulled up in the valve closing direction as in the present embodiment, a set of sensors 7
0, the target 72 can detect both the lift start and end timings.

Further, the target 72 is moved to the cam use range R.
Because of the stepped shape utilizing the large diameter portion 74 forming
There is no increase in weight or number of parts.

Further, since the detection timing is set immediately after the lift start timing and immediately before the lift end timing, even if the control shaft 22 hunts due to the valve reaction force or the inertia force of the link itself in the high engine speed region, A decrease in detection accuracy by the rotation position detection sensor 70 can be suppressed to a minimum.

This point will be described in detail with reference to FIG. 10. In the low engine speed range (for example, 2000 rpm), since the swing width of the control shaft 22 is small, the rotational position detection sensor 70 detects the timing at any time during one cycle. There is no big difference in sensing.

However, in the high engine speed range (6000r
At (pm), the swing width of the control shaft 22 is relatively large, so that the lift characteristics of the intake / exhaust valve 12 fluctuate relatively largely. Here, in this embodiment, the rotation position is detected by the rotation position detection sensor 70 before and after the start and end of the lift of the intake / exhaust valve 12 in which the swing width of the control shaft 22 is relatively small in one cycle. Therefore, it is possible to effectively suppress a decrease in accuracy due to the swing of the control shaft 22 as compared with the case where the detection is performed near the maximum lift of the intake / exhaust valve 12 in which the swing width of the control shaft 22 is relatively large. it can.

FIG. 11 shows a second embodiment of the present invention. In the following embodiments, the description of the above-described portions will be omitted by omitting the same reference numerals and omitting the overlapping description as appropriate, and only the portions different from the above-described embodiment will be described.

On the outer peripheral surface of the cam lobe 62 forming the cam use range R, a base circle section R1 having a constant diameter that does not lift the intake / exhaust valve 12, and the start / end of the lift of the intake / exhaust valve 12 (end) ), And an event section R3 in which the valve lifter 20 is lifted by pressing the valve lifter 20.

In this embodiment, when the swing cam 18 is pushed down in the valve opening direction (counterclockwise direction in the figure) (the state shown in FIG. 11), the rotational position detection sensor 70 is set in the base circle section. It is set so as to face R1 or the ramp section R2. In other words, it is set so that at least the event section R3 does not pass in front of the rotational position detection sensor 70.

The rotational position detecting sensor 70 is provided with a cam lobe 62.
The position of the target 72 at which the distance to the target 72 changes greatly is detected. Therefore, if the event section R3 of the cam lobe 62 is configured to pass in front of the rotation position detection sensor 70, erroneous detection is prevented in the event section R3 in which the distance to the rotation position detection sensor 70 greatly changes. In addition, it is necessary to set a large step in the target 72 portion. However, since the large-diameter portion 74 forming the step of the target 72 smoothly continues to the cam use range R, it is difficult to actually increase the step.

According to this embodiment, since the event section R3 does not pass in front of the rotational position detection sensor 70,
As described above, the detection accuracy of the target 72 can be sufficiently ensured without forcibly increasing the step.

Next, a third embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

In this embodiment, the axial width of the target 72A in the cam lobe 62 is made relatively small, and the axial positions of the target 72A and the sensor 70 facing the target 72A are determined. It is offset toward the journal portion 64 (left side in FIG. 12) with respect to the axial center. And, mainly for the purpose of weight reduction, a cutout portion 80 is set in the circumferential portion from the base circle section R1 having a relatively small valve reaction force to the target 72A and in the axial direction on the side opposite to the journal portion 64. ing.

Like the oscillating cam 18 of this embodiment, the oscillating cam 18 has a pair of cam lobes 60 and 62 that are divided for each cylinder and operate the intake and exhaust valves 12.
In a configuration in which one journal portion 64 supported on the cylinder head 14 side is provided between 0 and 62, tilting in the axial direction is likely to occur. This fall is the journal part 64
And becomes larger as the distance from the journal portion 64 increases. Accordingly, by offsetting the target 72A toward the journal portion 64 as in the present embodiment, it is possible to effectively suppress a decrease in detection accuracy due to the tilting of the swing cam 18.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a variable valve apparatus for an internal combustion engine according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the variable valve device.

FIG. 3 is a top view showing the rear side of the internal combustion engine.

FIG. 4 is a top view corresponding to the front side of the internal combustion engine.

FIG. 5 is a configuration diagram of the variable valve operating device.

FIG. 6 is a sectional view showing a minimum lift state by rotation control of a control shaft.

FIG. 7 is a sectional view showing a maximum lift state by rotation control of a control shaft.

FIG. 8 is an explanatory diagram showing a state where a target of the swing cam crosses in front of a rotational position detection sensor.

FIG. 9 is a characteristic diagram showing a valve lift characteristic and a sensor output with respect to a drive shaft angle.

FIG. 10 is a characteristic diagram showing a valve lift characteristic and an angle change of a control shaft with respect to an angle of a drive shaft.

FIG. 11 is an explanatory view showing a main part of a second embodiment of the present invention.

FIG. 12 is a sectional view showing a third embodiment of the present invention.

FIG. 13 is a view corresponding to arrow A in FIG. 12;

FIG. 14 is a sectional view showing a third embodiment.

FIG. 15 is an exploded perspective view showing a variable valve device for an internal combustion engine according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 ... Intake / exhaust valve 14 ... Cylinder head 16 ... Drive shaft 18 ... Swing cam 20 ... Valve lifter 22 ... Control shaft 24 ... Control cam 26 ... Rocker arm 28 ... Eccentric cam 30 ... Ring link 32 ... Rod link 60, 62 ... Cam lobe 64 ... Journal part 70 ... Rotation position detection sensor 72 ... Target

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Keisuke Takeda 1370 Onna, Atsugi-shi, Kanagawa F-term in Unisia Gex Co., Ltd. (reference) 3G016 AA08 AA12 AA19 BA23 BA28 BA36 BA39 BB04 CA04 CA21 CA22 CA25 CA32 CA44 CA47 CA48 DA23 FA29 GA01 GA02 3G092 AA11 DA01 DA02 DA05 DG03 EA13 EA25 FA06 FA13 FA48 FA50 HA01Z HA13X HA13Z HE03Z HE08Z

Claims (6)

[Claims] 1. A drive shaft that rotates in synchronization with rotation of an engine, a cam lobe that slides on an intake / exhaust valve to open and close the intake / exhaust valve, and is rotatably mounted on an outer periphery of the drive shaft. A swinging cam to be fitted, a control shaft rotationally controlled within a predetermined control angle range, a control cam eccentrically fixed to the outer periphery of the control shaft, and a rocker arm rotatably fitted to the outer periphery of the control cam. An eccentric cam fixed eccentrically to the outer periphery of the drive shaft; a ring-shaped link rotatably fitted to the outer periphery of the eccentric cam and rotatably connected to one end of the rocker arm; A rod-shaped link rotatably connected to both the end and the rocking cam; and a detecting means for detecting a rotational position of the rocking cam. A target detected by the detecting means on the rocking cam. To A variable valve train for an internal combustion engine, wherein the variable valve train is provided. 2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein a step in the radial direction is provided at least on an outer peripheral surface of one cam lobe of the swing cam, and the step is used as the target. . 3. The detecting means is a rotational position detecting sensor attached to a cylinder head in a posture pointing toward the outer peripheral surface of the cam lobe, and the target is configured such that the suction / exhaust is performed within the outer peripheral surface of the cam lobe. 3. The variable valve operating device for an internal combustion engine according to claim 2, wherein the variable valve operating device is set at a position out of a cam use range that slides or opposes a valve lifter of the valve. 4. The swinging cam comprises a pair of cam lobes slidingly in contact with a valve lifter of an intake / exhaust valve, and a journal provided between the two cam lobes and rotatably supported on a cylinder head via a bracket. The variable valve train for an internal combustion engine according to any one of claims 1 to 3, wherein the target is offset toward the journal with respect to the axial center of the cam lobe. 5. One swing cam is provided with at least two cam lobes, one of the cam lobes is connected to the rod-shaped link, and the other cam lobe is provided with the target. A variable valve train for an internal combustion engine according to claim 1. 6. The internal combustion engine according to claim 1, wherein the target is detected by the detection means before and after the swing cam is pulled up in the valve closing direction. Variable valve gear of the engine.