JP5294156B2 - Variable valve operating device for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine, and more particularly to a variable valve operating apparatus for an internal combustion engine that continuously changes the lift characteristics of the engine valve.

  In order to continuously change the lift amount and operating angle of the engine valve in accordance with the operating state of the internal combustion engine, the internal combustion engine of the vehicle supports a swing cam for lifting the engine valve on the control shaft so as to be swingable. The cam follower that swings by the rotating cam of the cam shaft and swings the swing cam is connected to the swing cam via the position change mechanism, and the relative positional relationship of the swing cam with respect to the cam follower is changed by the position change mechanism. Some of them are provided with a variable valve gear that changes the lift characteristics of the engine valve.

Japanese Patent No. 3799944

  The variable valve mechanism and the air amount control device for an internal combustion engine according to Patent Document 1 change the relative phase difference between the input portion and the output portion of the mediation drive mechanism, that is, cam the control shaft (control shaft) different from the cam shaft. The phase of the swing cam for output to the input rocker arm and the roller rocker arm is changed by the meshing of the helical spline, and at this time, the meshing change of the helical spline is realized by the movement of the control shaft in the axial direction.

However, conventionally, in the variable valve mechanism of the internal combustion engine according to Patent Document 1 described above, the phase is controlled by the axial movement of the control shaft, so that the valve lift error between the cylinders is large due to the temperature difference of the internal combustion engine. There was a problem of becoming. This is because the cylinder head, which is a component, is made of aluminum and the control shaft is made of iron, so that changes in the lengths of the cylinder head and the control shaft due to temperature differ. In addition, the helical spline is difficult to manufacture and has the disadvantage of increasing costs.
In addition, the variable valve operating apparatus configured as described above has a disadvantage that the valve lift amount is variable but the cam timing for operating the engine valve is fixed, which tends to be disadvantageous in terms of performance.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a variable valve operating apparatus for an internal combustion engine that eliminates variations in lift characteristics for each engine valve due to a difference in mature expansion between parts and improves manufacturability.

  According to the present invention, a swing cam for lifting an engine valve is swingably supported on a control shaft, and a cam follower that swings the swing cam and swings the swing cam via a position changing mechanism is provided on the swing cam. In the variable valve operating apparatus for an internal combustion engine, the lift shaft of the engine valve is changed by changing a relative positional relationship of the swing cam with respect to the cam follower by the position changing mechanism. A circular eccentric eccentric shaft portion having an eccentricity with respect to the control shaft is formed, and the cam follower is swingably supported by the eccentric shaft portion, and the cam follower is externally mounted with the eccentric shaft portion as a rotation shaft. Forming a toothed gear, forming an internal gear that meshes with the external gear with the control shaft as a rotation axis on the swing cam, and changing the position by the eccentric shaft portion, the external gear, and the internal gear. The control shaft is rotated at the time of changing the opening / closing characteristics of the engine valve, the external gear is revolved around the axis of the control shaft by the eccentric shaft portion, and the external gear is revolved Moving the meshing point of the internal gear with respect to the external gear in the circumferential direction of the internal gear, and changing the position of the swing cam with respect to the cam follower as the meshing point of the internal gear moves. Features.

  The present invention can eliminate variations in lift characteristics for each engine valve due to a difference in mature expansion between components, and can improve manufacturability.

FIG. 1 is a perspective view of a variable valve operating apparatus for an internal combustion engine. (Example) FIG. 2 is an exploded view of a variable valve operating apparatus for an internal combustion engine. (Example) FIG. 3 is a cross-sectional view of a variable valve operating apparatus for an internal combustion engine. (Example) FIG. 4 (A) is a view showing the operation of the engine valve during small lift / non-operation. FIG. 4B is a diagram showing an operation at the time of small lift / operation of the engine valve. (Example) FIG. 5 (A) is a diagram showing the operation of the engine valve when the engine is lifted and not operated. FIG. 5B is a diagram showing the operation of the engine valve during a large lift / operation. (Example) FIG. 6 is a diagram showing the relationship between the lift amount of the engine valve and the opening / closing timing. (Example)

  The purpose of this invention is to eliminate variations in the lift characteristics of each engine valve due to the difference in mature expansion between parts, and to improve manufacturability. The position change mechanism is constituted by the gears, and the position of the swing cam with respect to the cam follower is changed by rotation of the control shaft.

1 to 6 show an embodiment of the present invention.
In FIG. 3, reference numeral 1 denotes an internal combustion engine mounted on a vehicle. Hereinafter, the crank axis direction of the internal combustion engine 1 will be referred to as the front-rear direction, the cylinder axis direction will be referred to as the up-down direction, and the direction orthogonal to the crank axis and the cylinder axis will be described as the left-right direction.
As shown in FIGS. 1 to 3, the internal combustion engine 1 is provided with an engine valve 2 composed of an intake valve or an exhaust valve that opens and closes a port composed of an intake port or an exhaust port communicating with the combustion chamber of the cylinder head. . As shown in FIG. 3, the engine valve 2 is supported by the cylinder head so that the axis C is inclined at a predetermined angle and is movable in the vertical direction when viewed from the front.
The engine valve 2 is composed of a one-side engine valve 2A disposed in front and an other-side engine valve 2B disposed rearward along with the one-side engine valve 2A.
The one-side engine valve 2A is composed of a one-side valve head 3A at the front end portion that is in contact with and away from the opening of the port, and a one-side valve stem 4A in which the front end side is connected to the one-side valve head 3A. The other-side engine valve 2B is composed of the other-side valve head 3B at the front end portion that is brought into contact with and separated from the opening of the port, and the other-side valve stem 4B having the front-end side connected to the other-side valve head 3B.
Here, the one-side valve head 3 </ b> A and the other-side valve head 3 </ b> B constitute the valve head 3. The one-side valve stem 4A and the other-side valve stem 4B constitute the valve stem 4.

The internal combustion engine 1 is provided with a roller finger follower (RFF: rocker arm) 5 that moves and opens and closes the engine valve 2 in the axial direction (vertical direction).
The roller finger follower 5 includes a one-side roller finger follower 5A corresponding to the one-side engine valve 2A and an other-side roller finger follower 5B corresponding to the other-side engine valve 2B.
The one-side roller finger follower 5A is rotatably provided on a one-side arm portion 6A arranged in a horizontal direction and in a left-right direction and a one-side roller shaft 7A supported on the central portion of the one-side arm portion 6A. The one side roller 8A, the one side valve contact portion 9A formed at the left end portion of the one side arm portion 6A, and the one side adjuster support portion 10A formed at the right end portion of the one side arm portion 6A. . The one-side adjuster support portion 10A is supported by the top sphere portion of the one-side hydraulic lash adjuster 11A.
The other-side roller finger follower 5B is rotatably provided on the other-side arm portion 6B arranged in the horizontal direction and in the left-right direction, and on the other-side roller shaft 7B supported on the central portion of the other-side arm portion 6B. The other side roller 8B, the other side valve contact portion 9B formed at the left end portion of the other side arm portion 6B, and the other side adjuster support portion 10B formed at the right end portion of the other side arm portion 6B. . The other side adjuster support portion 10B is supported by the top sphere portion of the other side hydraulic lash adjuster 11B.
Here, the one-side arm portion 6 </ b> A and the other-side arm portion 6 </ b> B constitute the arm portion 6. The one side roller shaft 7 </ b> A and the other side roller shaft 7 </ b> B constitute a roller shaft 7. The one side roller 8 </ b> A and the other side roller 8 </ b> B constitute a roller 8. The one-side adjuster support portion 10 </ b> A and the other-side adjuster support portion 10 </ b> B constitute the adjuster support portion 10. The one-side hydraulic lash adjuster 11 </ b> A and the other-side hydraulic lash adjuster 11 </ b> B constitute the hydraulic lash adjuster 11.

  A camshaft 12 that rotates in synchronization with the crankshaft of the internal combustion engine 1 and operates the engine valve 2 is supported on the cylinder head of the internal combustion engine 1 in the front-rear direction. A rotating cam 13 is integrally provided on the cam shaft 12. The rotating cam 13 includes a base circle portion 14 and a cam portion 15 protruding in the radial direction from the base circle portion 14.

The internal combustion engine 1 is provided with a variable valve gear 16 that changes the lift characteristics of the engine valve 2.
As shown in FIGS. 1 to 3, the variable valve operating device 16 includes a control shaft 17 disposed between the engine valve 2 and the cam shaft 12 in parallel with the cam shaft 12 in the front-rear direction. The rotation of the control shaft 17 is controlled by an actuator 18 composed of an electric motor or the like. The actuator 18 is driven and controlled by the control means 19.
As shown in FIGS. 2 and 3, the control shaft 17 includes a one-side shaft portion 20 having a predetermined diameter at the front end portion, and the other-side shaft portion 21 having the same diameter as the one-side shaft portion 20 at the rear end portion. The diameter between the side shaft portion 20 and the other side shaft portion 21 is larger than the diameter of the one side shaft portion 20 and the other side shaft portion 21 and the axis is predetermined with respect to the one side shaft portion 20 and the other side shaft portion 21. And a circular eccentric shaft portion 22 that is eccentric with an eccentric amount (offset) e of the first shaft portion, that is, an eccentric shaft portion that is eccentric with respect to the axis O1 of the one side shaft portion 20 and the other side shaft portion 21. The shaft center O2 of 22 is set eccentrically in the radial direction by the amount of eccentricity e, and the eccentric shaft portion 22 rotates eccentrically about the shaft center O1 of the one side shaft portion 20 and the other side shaft portion 21.

The control shaft 17 is provided with a swing cam 23 that is supported by the control shaft 17 so as to be swingable and lifts the engine valve 2.
The swing cam 23 includes a one-side swing cam 23A disposed on the one-side shaft portion 20 and an other-side swing cam 23B disposed on the other-side shaft portion 21.
The one-side swing cam 23A includes a one-side base circle portion 24A that does not lift the one-side engine valve 2A, and a one-side cam portion 25A that protrudes in the radial direction from the one-side base circle portion 24A and lifts the one-side engine valve 2A. And. As shown in FIG. 2, a one-side cavity portion 26A having an inner diameter larger than the diameter of the one-side shaft portion 20 is formed on the inner periphery of the one-side base circle portion 24A. One side internal gear 27A as a spur gear is formed on the inner peripheral surface. The center of the one-side base circle portion 24 </ b> A is arranged coaxially with the one-side shaft portion 20. In addition, a one-side support portion 29A including a one-side shaft hole 28A through which the one-side shaft portion 20 passes is connected to the outer end portion of the one-side base circle portion 24A so as to protrude in the axial direction. That is, the one-side swing cam 23A includes the one-side base circular portion 24A that does not transmit the lift of the cam portion 15 of the rotating cam 13 of the cam shaft 12 to the one-side roller finger follower 5A, and the cam of the rotating cam 13 of the cam shaft 12. And a one-side cam portion 25A that transmits the lift of the portion 15 to the one-side roller finger follower 5A. Further, since the center of the one-side base circle portion 24A is coaxial with the one-side shaft portion 20 of the control shaft 17, even if the control shaft 17 rotates, the one-side roller finger follower 5A is not pushed and moved.
The other-side swing cam 23B includes an other-side base circle portion 24B that does not lift the other-side engine valve 2B, and an other-side cam portion 25B that protrudes radially from the other-side base circle portion 24B and lifts the other-side engine valve 2B. And. As shown in FIG. 2, an inner cavity 26B having an inner diameter larger than the diameter of the other shaft 21 is formed on the inner circumference of the other base circle 24B. The other internal gear 27B as a spur gear is formed on the inner peripheral surface. The center of the other-side base circle portion 24B is arranged coaxially with the other-side shaft portion 21. In addition, an other side support portion 29B including an other side shaft hole 28B through which the other side shaft portion 21 passes is connected to the outer end portion of the other side base circle portion 24B so as to protrude in the axial direction. That is, the other-side swing cam 23B includes the other-side base circular portion 24B that does not transmit the lift of the cam portion 15 of the rotating cam 13 of the camshaft 12 to the other-side roller finger follower 5B, and the cam of the rotating cam 13 of the camshaft 12. The other side cam part 25B which transmits the lift of the part 15 to the other side roller finger follower 5B is provided. Further, since the center of the other-side base circle portion 24B is coaxial with the other-side shaft portion 21 of the control shaft 17, the other-side roller finger follower 5B is not pushed and moved even if the control shaft 17 rotates.
Here, the one-side base circle portion 24 </ b> A and the other-side base circle portion 24 </ b> B constitute the base circle portion 24 of the swing cam 23. The one-side cam portion 25A and the other-side cam portion 25B constitute the cam portion 25 of the swing cam 23. The one side cavity portion 26 </ b> A and the other side cavity portion 26 </ b> B constitute the cavity portion 26 of the swing cam 23. The one side internal gear 27 </ b> A and the other side internal gear 27 </ b> B constitute the internal gear 27 of the swing cam 23.

A cam follower (rocker arm) 31 is connected to the swing cam 23 via a position changing mechanism 30. The cam follower 31 swings by the rotating cam 13 of the cam shaft 12 and swings the swing cam 23.
The cam follower 31 includes a tubular body 33 having a shaft insertion hole 32 fitted to the eccentric shaft portion 22 of the control shaft 17, and a pair of protrusions projecting toward the camshaft 12 at the axial central portion of the tubular body 33. A roller support portion 34, 34, a roller pin 35 supported by the pair of roller support portions 34, 34, and a roller 36 rotatably supported by the roller pin 35 between the pair of roller support portions 34, 34; The eccentric shaft portion 22 is slidably supported.

As shown in FIGS. 2 and 3, the tubular main body 33 has a one-side external gear 37 </ b> A as a spur gear that meshes with the one-side internal gear 27 </ b> A using the eccentric shaft portion 22 as a rotation shaft. Is formed at the front end portion, and the other side external gear 37B is formed at the rear end portion as a spur gear that meshes with the other side internal gear 27B of the other side swing cam 23B with the eccentric shaft portion 22 as the rotation shaft. Yes.
The one-side external gear 37A and the other-side external gear 37B constitute the external gear 37 of the cam follower 31.
The one-side external gear 37A, the other-side external gear 37B, and the eccentric shaft portion 22 are disposed inside the one-side cavity portion 26A and the other-side cavity portion 26B. Thereby, the axial direction length of the eccentric shaft part 22 can be shortened, and the mountability to the internal combustion engine 1 of the variable valve apparatus 16 can be improved.
As shown in FIG. 3, the axis of the one-side external gear 37 </ b> A and the other-side external gear 37 </ b> B is arranged coaxially with the swing center of the cam follower 31. The axis of the one-side internal gear 27 </ b> A and the other-side internal gear 27 </ b> B is arranged coaxially with the swing center of the swing cam 23. Therefore, the one-side internal gear 27A / other-side internal gear 27B and the one-side external gear 37A / other-side external gear 37B are eccentrically engaged by an eccentric amount e.
In this embodiment, the position changing mechanism 30 is configured as a cycloid mechanism by the eccentric shaft portion 22, the one side internal gear 27A, the other side internal gear 27B, the one side external gear 37A, and the other side external gear 37B. Then, the relative positional relationship between the one-side swing cam 23A and the other-side swing cam 23B with respect to the cam follower 31 is changed to change the lift characteristics of the one-side engine valve 2A and the other-side engine valve 2B.

As shown in FIG. 3, the one side internal gear 27A, the other side internal gear 27B, and the one side external gear 37A, etc. of the tubular body 33 of the cam follower 31 are provided. The side external gear 37B meshes with the eccentric direction of the eccentric shaft portion 22. Therefore, the number of teeth of the one-side internal gear 27A / other-side internal gear 27B and the one-side external gear 37A / other-side external gear 37B is determined by the eccentricity e.
Since the one-side swing cam 23A and the other-side swing cam 23B are arranged at the front end portion and the rear end portion of the tubular main body 33 of the cam follower 31, two valves can be driven by one cam follower 31. And

In the structure of the variable valve operating apparatus 16 according to this embodiment, the control shaft 17, the cam follower 31, and the swing cam 23 are provided between the cam shaft 12 and the roller finger follower 5 with respect to the conventional roller rocker valve operating system. 4 and 5, the angle (β) between the cam follower 31 and the swing cam 23 is changed by the rotation (α) of the control shaft 17, and the lift of the engine valve 2 is Change the amount continuously.
As shown in FIG. 3, the variable valve operating device 16 operates the engine valve 2 by pressing the roller finger follower 5 by the swing cam 23. However, the roller finger follower 5 is replaced with a tappet or the like. Thus, the structure can be applied to various valve systems.

In the variable valve operating device 16, when changing the opening / closing characteristics of the engine valve 2, the control shaft 17 is rotated, and the external gear 37 is revolved around the axis of the control shaft 17 by the eccentric shaft portion 22. Due to the revolution of the external gear 37, the meshing point G (see FIGS. 4 and 5) of the internal gear 27 with respect to the external gear 37 is moved in the circumferential direction of the internal gear 27. Along with the movement, the position of the swing cam 23 relative to the cam follower 31 is changed.
As described above, the position changing mechanism 30 is configured by the cycloid mechanism including the eccentric shaft portion 22 of the control shaft 17, the external gear 37 of the cam follower 31, and the internal gear 27 of the swing cam 23. Since the position of the swing cam 23 relative to the cam follower 31 is changed to change the lift characteristic of the engine valve 2, the lift characteristic of the engine valve 2 is affected by the relative thermal expansion difference between the control shaft 17 and the internal combustion engine 1. It can be made a structure that does not receive
Further, since the position changing mechanism 30 is constituted by the external gear 37 and the internal gear 27 which are made of a spur gear that is easy to manufacture as compared with the conventional helical spline, the structure is simplified and the variable valve operating device is achieved. The productivity of 16 can be improved.

Further, when the control shaft 17 rotates, the cam follower 31 moves along the outer periphery of the rotating cam 13 while the cam follower 31 moves along the outer periphery of the rotating cam 13, while the lift amount of the engine valve 2 changes due to the movement of the swing cam 23. When the control shaft 17 is rotated in a direction in which the lift amount of the valve 2 decreases, the contact point between the cam follower 31 and the rotating cam 13 moves in the direction opposite to the rotating direction of the rotating cam 13 (advance angle side). .
As a result, as the lift amount of the engine valve 2 decreases, the cam timing at which the engine valve 2 closes can be advanced, and the pumping loss can be reduced.

Next, the operation during lift of the variable valve device 16 will be described with reference to FIGS.
As shown in FIG. 4A, in order to decrease the lift amount when the engine valve 2 is not operated, the control shaft 17 is rotated counterclockwise, and the angle of rotation of the control shaft 17 with respect to the reference position is α1. Along with this, the external gear 37 revolves counterclockwise around the axis O1 of the one side shaft portion 20 and the other side shaft portion 21 by the eccentric shaft portion 22, and the sandwiching angle between the cam follower 31 and the swing cam 23 Is reduced to β1, and the contact position between the rotating cam 13 and the cam follower 31 moves in the advance direction to become γ1. At this time, even if the cam portion 15 of the rotating cam 13 comes into contact with the roller 36 and swings the swing cam 23, the swing cam 23 and the roller 8 of the roller finger follower 5 are moved as shown in FIG. Are almost in contact with each other via the base circle portion 24, the engine valve 2 hardly lifts, and the lift amount is minimized (small lift state) (see R1 in FIG. 6).

As shown in FIG. 5A, in order to increase the lift amount when the engine valve 2 is not operated, the control shaft 17 is rotated counterclockwise and the angle with respect to the reference position is changed from the angle α1 to the angle α2. The external gear 37 rotates clockwise around the axis O2 of the eccentric shaft portion 22, and the cam follower 31 slides to the right by the position changing mechanism 30 that functions as a cycloid mechanism (FIG. 5A). The contact position between the rotating cam 13 and the cam follower 31 is changed from γ1 to γ2, and the valve timing is retarded. Further, the swing cam 23 rotates clockwise (in the valve opening direction) around the axis O1 of the one-side shaft portion 20 and the other-side shaft portion 21, and the sandwiching angle between the cam follower 31 and the swing cam 23 is from β1. Expands to β2.
At this time, since the sandwiching angle is β2> β1, the swing cam 23 and the roller finger follower 5 come into contact with each other via the cam portion 25 when the engine valve 2 is operated as shown in FIG. Since the range increases, the roller finger follower 5 swings largely around the top ball portion of the hydraulic lash adjuster 11, and the engine valve 2 operates greatly (large lift state) (see R2 in FIG. 6).
As shown in FIG. 6, in the relationship between the lift amount of the engine valve 2 and the opening / closing timing, the position of the maximum lift (the top of the lift curve) moves in the advance direction as the lift amount decreases.
This is because when the lift amount of the engine valve 2 is decreased, the contact position between the car follower 31 and the rotating cam 13 moves in the direction opposite to the rotating direction of the rotating cam 13 (advance direction), and the opening / closing timing of the engine valve 2 is Because it gets early. Therefore, when the engine valve 2 is slightly lifted, the engine valve 2 can be controlled to be quickly closed, and pumping loss can be reduced and fuel consumption can be improved.
Further, since control in the axial direction of the control shaft is not required as in the prior art, it is possible to obtain stable accuracy even with a small lift without being affected by the thermal expansion coefficient of the component material due to temperature change.

And in this Example, the following advantages are acquired by employ | adopting the position change mechanism 30 as a cycloid mechanism.
Due to the deceleration principle of the cycloid mechanism, the displacement angle α is greater than the displacement angle β. That is, when the rotation of the swing cam 23 is viewed from the rotation of the control shaft 17, (α2−α1)> (β2−β1) is established, and large deceleration is possible. The control shaft 17 is less susceptible to torque fluctuations. That is, the reliability of the actuator 18 that drives the control shaft 17 is improved.
Further, since the internal gear 27 of the swing cam 23 and the external gear 37 of the cam follower 31 are in a relationship between the external gear and the internal gear, a large meshing rate (tooth surface meshing rate) can be secured, and the slip rate can be reduced. Thus, it is advantageous for improving the reliability of the tooth surface.
Further, since the eccentricity e of the rotation shafts of the internal gear 27 and the external gear 37 is usually very small, even when the rotary cam 13 is operated, the slippage of both gears is very small, and the reliability of the tooth surface can be improved. It is advantageous for improvement.

In the present invention, two cam gears are attached to one cam follower, and two valves are driven by one cam portion. However, the cam follower has two cam followers and two cam followers. Is also possible.
Further, although a roller finger follower (RFF) type valve operating system has been described as an example, the present invention can also be applied to a direct hitting valve operating system using a tappet or the like.

  The variable valve operating apparatus according to the present invention can be applied to internal combustion engines of various vehicles.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Engine valve 5 Roller finger follower 12 Cam shaft 13 Rotating cam 16 Variable valve operating device 17 Control shaft 20 One side shaft portion 21 Other side shaft portion 22 Eccentric shaft portion 23 Swing cam 23A One side swing cam 23B Other Side swing cam 26 Cavity 26A One side cavity 26B Other side cavity 27 Internal gear 27A One side internal gear 27B Other side internal gear 31 Cam follower 33 Tubular body 37 External gear 37A One side external gear 37B Other Side external gear

Claims (3)

  A swing cam that lifts the engine valve is swingably supported on the control shaft, and a cam follower that swings by the rotating cam and swings the swing cam is connected to the swing cam via a position change mechanism, In the variable valve operating apparatus for an internal combustion engine, in which the lift valve characteristic of the engine valve is changed by changing the relative positional relationship of the swing cam with respect to the cam follower by the position changing mechanism, the control shaft includes the control shaft. A circularly eccentric eccentric shaft portion having an eccentric shaft center is formed, and the cam follower is swingably supported on the eccentric shaft portion, and an external gear having the eccentric shaft portion as a rotation shaft is formed on the cam follower. An internal gear that meshes with the external gear is formed on the swing cam with the control shaft as a rotation axis, and the position change mechanism is configured by the eccentric shaft portion, the external gear, and the internal gear. When the opening / closing characteristics of the engine valve are changed, the control shaft is rotated, the eccentric shaft portion revolves the external gear around the axis of the control shaft, and the external gear revolves with respect to the external gear. An internal combustion engine characterized in that the meshing point of the internal gear is moved in the circumferential direction of the internal gear, and the position of the swing cam with respect to the cam follower is changed with the movement of the meshing point of the internal gear. Variable valve gear.   When the control shaft rotates, the cam follower moves along the outer periphery of the rotating cam, while the cam follower moves along the outer periphery of the rotating cam, and the lift amount of the engine valve changes due to the movement of the swing cam. The contact point between the cam follower and the rotating cam moves in a direction opposite to the rotating direction of the rotating cam when the control shaft is rotated in a direction in which the lift amount of the rotating cam decreases. 2. A variable valve operating apparatus for an internal combustion engine according to 1.   The swing cam includes a base circular portion that does not lift the engine valve and a cam portion that protrudes in a radial direction from the base circular portion, and a hollow portion is formed on an inner periphery of the base portion. 2. The variable valve operating apparatus for an internal combustion engine according to claim 1, wherein the internal gear is formed on a surface, and the external gear and the eccentric shaft portion are disposed inside the cavity portion.

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