JP2011127489A - Variable valve gear of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce fuel consumption of an internal combustion engine, by improving controllability of a lift quantity and the lift timing of an engine valve, while reducing a driving loss. <P>SOLUTION: Therefor, this variable valve gear of the internal combustion engine changes the lift characteristic of the engine valve by changing the relative positional relationship of first and second rocker arms by a position changing mechanism. An eccentric shaft part is formed on a control shaft, and an external teeth gear with the eccentric shaft part as a rotary shaft is formed in the first rocker arm rockably supported by the eccentric shaft part, and an internal teeth gear meshing with the external teeth gear with the control shaft as the rotary shaft is formed in the second rocker arm. A position changing mechanism is constituted of the eccentric shaft part, the external teeth gear and the internal teeth gear, and when changing the lift characteristic of the engine valve, the external teeth gear is revolved around the control shaft by the eccentric shaft part, and the meshing point of the internal teeth gear to the external teeth gear is moved in the peripheral direction of the internal teeth gear by the revolution of the external teeth gear, and the position of the second rocker arm to the first rocker arm is changed in response to the movement of the meshing point. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a variable valve operating apparatus for an internal combustion engine, and in particular, is capable of reducing the drive loss, improving the controllability of the lift amount and lift timing of the engine valve, and reducing the fuel consumption of the internal combustion engine. The present invention relates to a variable valve device.

In an internal combustion engine of a vehicle, a swing cam that lifts an engine valve is supported on a cam shaft provided with a rotating cam so as to be swingable, and the control shaft parallel to the cam shaft is swung by the rotating cam and the swing cam. A rocker arm that swings the moving cam is supported in a swingable manner, and the rocker arm is divided into a first rocker arm that swings by the rotating cam and a second rocker arm that swings the swing cam, and the first rocker arm and the The second rocker arm is connected via a position changing mechanism, and the position changing mechanism changes the relative positional relationship between the first rocker arm and the second rocker arm to change the lift characteristics of the engine valve. Some have a variable valve system.
Japanese Patent No. 3881883 discloses a drive cam fixed to the outer periphery of a drive shaft that is driven to rotate by a crankshaft, a rocker arm that swings by rotation of a drive cam linked to one end, and the other end of the rocker arm. A variable valve operating apparatus is described that includes a swing cam that opens an engine valve in association with each other, an actuator that changes a swing fulcrum of a rocker arm, and a control unit that drives and controls the actuator according to the engine operating state. Yes.

Japanese Patent No. 3881883

By the way, in a variable valve device for a conventional internal combustion engine, for example, in the variable valve mechanism disclosed in Japanese Patent Application Laid-Open No. 2006-152926 and the like, the rocking fulcrum of the rocker arm is changed by an eccentric shaft. Thus, the lift amount of the engine valve is changed.
In this case, in order to greatly change the lift amount, it is necessary to move the rocker arm rocking center in the radial direction with respect to the rocking cam rocking center.
Therefore, even if the lift amount becomes variable, the lift timing hardly changes.
In order to obtain a fuel efficiency effect with the variable valve mechanism, it is effective to close the valve early as the lift amount decreases, but the lift timing of the engine valve does not change.
Also, in order to change the lift amount significantly, it is necessary to make the eccentric amount of the eccentric shaft relatively large. As a result, it is necessary to increase the diameter of the eccentric shaft, making the engine more compact and reducing the friction. There is a disadvantage that it is disadvantageous.

  The present invention relates to a variable valve operating apparatus for an internal combustion engine that changes the lift characteristics of an engine valve, reduces drive loss, improves controllability of the lift amount and lift timing of the engine valve, and reduces fuel consumption of the internal combustion engine. Is the purpose.

  Accordingly, in order to eliminate the above-described disadvantages, the present invention supports a swing cam that lifts an engine valve on a cam shaft provided with a rotary cam so as to swing, and the rotary cam is mounted on a control shaft parallel to the cam shaft. And a rocker arm that rocks the rocking cam and swingably supports the rocker arm. The rocker arm is divided into a first rocker arm that rocks by the rotating cam and a second rocker arm that rocks the rocking cam. The first rocker arm and the second rocker arm are connected via a position changing mechanism, and the relative positional relationship between the first rocker arm and the second rocker arm is changed by the position changing mechanism to change the engine valve. In the variable valve operating apparatus for an internal combustion engine in which the lift characteristics are changed, a circular eccentric shaft portion is formed on the control shaft so that the shaft center is eccentric with respect to the control shaft. The first rocker arm 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 first rocker arm, and the control shaft is used as the rotation shaft on the second rocker arm. An internal gear that meshes with an external gear is formed, and the position change mechanism is configured by the eccentric shaft portion, the external gear, and the internal gear, and the control shaft is rotated when the lift characteristic of the engine valve is changed. The external gear is caused to revolve around the axis of the control shaft by the eccentric shaft portion, and the meshing point of the internal gear with respect to the external gear is determined by the revolution of the external gear in the circumferential direction of the internal gear. And the position of the second rocker arm with respect to the first rocker arm is changed with the movement of the meshing point.

As described above in detail, according to the present invention, the swing cam for lifting the engine valve is supported on the cam shaft provided with the rotating cam so as to be swingable, and the control shaft parallel to the cam shaft is swung by the rotating cam. In addition, a rocker arm that swings the swing cam is supported in a swingable manner, and the rocker arm is divided into a first rocker arm that swings by the rotating cam and a second rocker arm that swings the swing cam. A variable movement of the internal combustion engine in which the rocker arm is connected via a position changing mechanism, and the relative positional relationship between the first rocker arm and the second rocker arm is changed by the position changing mechanism to change the lift characteristics of the engine valve. In the valve device, the control shaft is formed with a circular eccentric shaft portion whose center is eccentric with respect to the control shaft, and the first rocker arm is swingably supported on the eccentric shaft portion and the first An external gear having an eccentric shaft portion as a rotation shaft is formed on the rocker arm, and an internal gear meshing with the external gear is formed on the second rocker arm using the control shaft as a rotation shaft. The eccentric shaft portion, the external gear and the internal gear are formed. The position change mechanism is configured to rotate the control shaft when changing the lift characteristics of the engine valve, and the eccentric gear rotates the external gear around the axis of the control shaft, and the external gear revolves around the external gear. The meshing point of the internal gear with respect to the gear is moved in the circumferential direction of the internal gear, and the position of the second rocker arm with respect to the first rocker arm is changed as the meshing point moves.
Therefore, in the present invention, when the control shaft is rotated, the eccentric gear rotates the external gear around the axis of the control shaft, rotates the internal gear meshing with the external gear, and rotates the second rocker arm with respect to the first rocker arm. The position of the second rocker arm with respect to the first rocker arm can be adjusted by the eccentric shaft and gears, and the eccentric shaft is compared with the one that only moves the rocking fulcrum of the rocker arm at the eccentric shaft. The amount of eccentricity and the outer diameter can be reduced. Therefore, the frictional resistance between the rocker arm and the eccentric shaft portion can be reduced, and the driving loss of the variable valve mechanism can be reduced.
Further, in the present invention, when the lift amount of the engine valve is changed, the external gear of the first rocker arm is movable on the inner periphery of the internal gear of the second rocker arm, and the contact point of the first rocker arm with respect to the rotating cam is the outer peripheral surface of the rotating cam. Move along. Therefore, the lift timing can be changed simultaneously with the lift amount of the engine valve. As a result, the engine valve can be controlled to advance the closing timing as the lift amount decreases, and the pumping loss of the internal combustion engine can be reduced.
According to the above two points, the present invention can reduce the fuel consumption of the internal combustion engine.

FIG. 1 is a sectional view of a variable valve operating apparatus for an internal combustion engine. Example 1 FIG. 2 is a perspective view of a variable valve operating apparatus for an internal combustion engine. Example 1 FIG. 3 is an exploded perspective view of a variable valve operating apparatus for an internal combustion engine. Example 1 4A and 4B show the variable valve system of the internal combustion engine when it is not in operation. FIG. 4A is an explanatory diagram when the large lift is inactive, and FIG. 4B is an explanatory diagram when the small valve is inactive. Example 1 FIGS. 5A and 5B show the time of operation of the variable valve device of the internal combustion engine. FIG. 5A is an explanatory view when the large lift is operated, and FIG. 5B is an explanatory view when the small lift is operated. Example 1 FIG. 6 is a diagram showing the relationship between the valve lift amount and the timing. Example 1

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

1 to 6 show an embodiment of the present invention.
1 to 3, reference numeral 1 denotes a variable valve operating apparatus for an internal combustion engine (not shown).
A cylinder head (not shown) of the internal combustion engine is provided with an engine valve 2 consisting of an intake valve or an exhaust valve for opening and closing a port consisting of an intake port or an exhaust port communicating with a combustion chamber (not shown).
As shown in FIGS. 1 to 3, the engine valve 2 includes a valve head 3 that is brought into contact with and separated from the opening of the port, and a valve stem 4 having a distal end side connected to the valve head 3.
As shown in FIGS. 1 to 3, the engine valve 2 is disposed on the cylinder head with its axis inclined at a predetermined angle when viewed from the front, and the valve stem 4 is supported on the cylinder head so as to be movable in the axial direction. Has been.
Further, in the engine valve 2, a retainer (not shown) is fixed to the outer peripheral surface on the base end face side of the valve stem 4, and a valve spring fitted to the valve stem 4 between the retainer and a seat portion of the cylinder head. (Not shown) is urged in the valve closing direction.
At this time, the engine valve 2 includes, for example, two first and second engine valves 2-1 and 2-2, and the first of these first and second engine valves 2-1 and 2-2. The roller finger follower (also referred to as “RFF”) 5, that is, one side of the first and second roller finger followers 5-1 and 5-2 contacts the upper ends of the second valve stems 4-1 and 4-2. And the other side of the first and second roller finger followers 5-1 and 5-2 to the hydraulic lash adjuster 6, that is, the first and second hydraulic lash adjusters 6-1 and 6-2. It is swingably connected.

The variable valve operating apparatus 1 supports a swing cam 9 that lifts the engine valve 2 on a cam shaft 8 having a rotating cam 7 so as to be swingable.
At this time, as shown in FIG. 2 and FIG. 3, the swing cam 9 is arranged so that the rotary cam 7 is in contact with the longitudinal center portions of the first and second roller finger followers 5-1 and 5-2. The first and second swing cams 9-1 and 9-2 are arranged on both sides.
The variable valve operating apparatus 1 swingably supports a rocker arm 11 that swings on the control shaft 10 parallel to the camshaft 8 by the rotary cam 7 and swings the swing cam 9. The rocker arm 11 is divided into a first rocker arm 12 that swings by the rotating cam 7 and a second rocker arm 13 that swings the swing cam 9.
That is, as shown in FIGS. 1 to 3, the control shaft 10 is rotated by the actuator 14, and the first rocker arm 12 and the second rocker arm 13 are swingably supported on the control shaft 10.
At this time, the second rocker arm 13 is disposed on both sides of the first rocker arm 12, and the first and second rocker arms 9-1 and 9-2 are swung respectively. 2. Consists of a rocker arm 16 on the other side.
As shown in FIGS. 1 to 3, the first rocker arm 12 includes a through-hole portion 12-1 through which the control shaft 10 passes and a roller 12-2 that contacts the rotating cam 7 provided on the cam shaft 8. I have.
The second / one-side rocker arm 15 includes a one-side through hole 15-1 that allows the control shaft 10 to pass therethrough, and a one-side roller 15-2 that contacts the first swing cam 9-1. On the other hand, the second / other-side rocker arm 16 includes an other-side through-hole portion 16-1 that allows the control shaft 10 to pass therethrough and an other-side roller 16-2 that contacts the second swing cam 9-2. ing.
Further, the variable valve operating apparatus 1 connects the first rocker arm 12 and the second rocker arm 13 via a position changing mechanism 17, and the position changing mechanism 17 allows the first rocker arm 12 and the second rocker arm 13 to be connected. And the lift characteristic of the engine valve 2 is changed.

The control shaft 10 includes a circular eccentric shaft portion 18 whose axis is eccentric with respect to the axis of the control shaft 10, and supports the first rocker arm 12 on the eccentric shaft portion 18 so as to be swingable. In addition, an external gear 19 having the eccentric shaft portion 18 as a rotation axis is formed on the first rocker arm 12. The second rocker arm 13 is supported on the control shaft 10, and the internal gear 20 that meshes with the external gear 19 is formed on the second rocker arm 13 with the control shaft 10 as a rotation shaft. The position changing mechanism 17 is constituted by a cycloid mechanism including the eccentric shaft portion 18, the external gear 19, and the internal gear 20. When changing the lift characteristic of the engine valve 2, the control shaft 10 is rotated, and the eccentric gear portion 18 revolves the external gear 19 around the axis of the control shaft 10. Due to the revolution of the external gear 19, the meshing point of the internal gear 20 with respect to the external gear 19 is moved in the circumferential direction of the internal gear 20, and the second relative to the first rocker arm 12 as the meshing point moves. The position of the rocker arm 13 is changed.
Specifically, as shown in FIG. 1, the control shaft 10 is formed with a circular eccentric shaft portion 18 in which the axis O2 is eccentric with respect to the rotation center O1 of the control shaft 10.
Moreover, when forming the through-hole part 12-1 of the said 1st rocker arm 12, the said external gear 19 is formed in the outer periphery of the pipe part provided with this through-hole part 12-1, and the through-hole part 12-1 is formed. The control shaft 10 is passed through, and the first rocker arm 12 is swingably supported by the eccentric shaft portion 18, and the eccentric shaft portion 18 is used as the rotation shaft of the external gear 19.
At this time, as shown in FIG. 3, the external gear 19 has first and second external gears 19-1 projecting in opposite directions so as to extend in the axial direction of the control shaft 10 from the first rocker arm 12, respectively. 19-2.
Further, the second and one side rocker arms 15 and the second and other side rocker arms 16 of the second rocker arm 13 have a one side through hole 15-1 through which the control shaft 10 penetrates, as shown in FIG. The internal gear 20 is formed coaxially with the through-hole portion 16-1, that is, the control shaft 10 is the center of rotation.
At this time, the internal gear 20 includes first and second internal gears 20-1 and 20-2 that mesh with the first and second external gears 19-1 and 19-2 of the external gear 19, respectively. .
The position changing mechanism 17 is configured by the eccentric shaft portion 18, the external gear 19, and the internal gear 20, and when the lift characteristic of the engine valve 2 is changed, the control shaft 10 is rotated, The external gear 19 is revolved around the axis of the control shaft 10 by the eccentric shaft portion 18, and the meshing point of the internal gear 20 with respect to the external gear 19 is determined by the revolution of the external gear 19. The position of the second rocker arm 13 with respect to the first rocker arm 12 is changed as the meshing point moves.
That is, the control shaft 10 is rotated to revolve the external gear 19 around the axis of the control shaft 10, and the meshing point of the internal gear 20 with the external gear 19 is set in the circumferential direction of the internal gear 20. Move. The position of the second rocker arm 13 relative to the first rocker arm 12 is changed by moving the meshing point between the position shown in FIG. 4A and the position shown in FIG.
Therefore, in the present invention, when the control shaft 10 is rotated, the eccentric shaft portion 18 causes the external gear 19 to revolve around the axis of the control shaft 10, the internal gear 20 meshing with the external gear 19 is rotated, and Since the position of the second rocker arm 13 relative to the first rocker arm 12 is changed, the position of the second rocker arm 13 relative to the first rocker arm 12 can be adjusted by the revolving movement of the eccentric shaft portion 18 and the gears. As a result, the eccentric amount and the outer diameter of the eccentric shaft portion 18 can be reduced as compared with the case where the rocker arm swinging fulcrum is moved. Therefore, the frictional resistance between the rocker arm and the eccentric shaft portion can be reduced, and the driving loss of the variable valve mechanism can be reduced.
In the present invention, the contact point of the first rocker arm 12 with respect to the rotating cam 7 moves along the outer peripheral surface of the rotating cam 7 when the lift amount of the engine valve 2 is changed. Therefore, the lift timing can be changed simultaneously with the lift amount of the engine valve 2. In the present invention, when the lift amount of the engine valve 2 is changed from the maximum to the minimum, the eccentric shaft portion 18 moves in the direction opposite to the rotary cam 7. As a result, it is possible to control the engine valve 2 so that the valve closing timing is advanced as the lift amount decreases, and the pumping loss of the internal combustion engine can be reduced.
According to the above two points, the present invention can reduce the fuel consumption of the internal combustion engine.

Hereinafter, an operation for changing the lift amount of the engine valve 2 will be described. FIG. 4A shows a state where the lift amount is maximized when the engine valve 2 is closed. An angle α1 (the straight line connecting the axis O2 of the eccentric shaft portion 18 and the rotation center O1 of the control shaft 10 with the axis O2 of the eccentric shaft portion 18 on the left side of the rotation center O1 of the control shaft 10) Hereinafter, the angle of the control axis is referred to as almost zero. As a result, the sandwiching angle β1 of the first and second rocker arms 12 and 13 is minimized, and the swing cam 9 is swung by a predetermined amount in the opening direction of the engine valve 2 within a range in which the engine valve 2 does not open. At this time, the contact angle between the rotating cam 7 and the first rocker arm 12 is γ1, and the valve timing is in the most retarded state.
Then, as shown in FIG. 5A, when the rotating cam 7 swings the swing cam 9 via the rocker arm 11, the swing cam is formed so as to protrude outward from the base portion B, and the engine The roller finger follower 5 is pushed down at the tip of the lift portion that lifts the valve 2, and the lift amount of the engine valve 2 increases to become a “large lift”.
When the lift amount of the engine valve 2 is changed from the maximum to the minimum, the control shaft 10 is rotated clockwise from the position shown in FIG. 4A to the position shown in FIG. The axis O2 is moved to the right side of the rotation center O1 of the control shaft 10, and the angle of the control shaft 10 is set to α2. As a result, the sandwiching angle of the first and second rocker arms 12 and 13 increases from “β1” to “β2”, and the swing cam 9 pressed against the second rocker arm 13 by a return spring (not shown) swings in the valve closing direction. To do.
Therefore, as shown in FIG. 5 (b), even if the rotating cam 7 swings the swing cam 9 via the rocker arm 11, the swing cam 9 is a roller finger follower at the base portion B that does not lift the engine valve 2. Since the section in contact with 5 increases from the section in contact with the roller finger follower 5 at the lift portion L that lifts the engine valve 2, the engine valve 2 hardly lifts and becomes a “small lift”.
Further, when the control shaft 10 is rotated clockwise from the position of FIG. 4A to the position of FIG. 4B to change the angle of the control shaft 10 from “α1” to “α2”, the control shaft 10 The rotation direction of the rotary cam 7 is opposite to the rotation direction of the rotary cam 7, and the roller 12-2 of the first rocker arm 12 moves in a direction in which the valve timing advances with respect to the rotary cam 7.
Therefore, the timing of closing the valve can be advanced as the lift amount of the engine valve 2 becomes smaller, and the pumping loss of the internal combustion engine can be reduced.

Further, as shown in FIGS. 4A and 4B, when the lift amount of the engine valve 2 is changed from the maximum to the minimum, the axis O2 of the eccentric shaft portion 18 is the rotation center O1 of the control shaft 10. It was made to rotate about 180 degrees centering on this.
As a result, when shifting from the large lift of FIG. 4A to the small lift of FIG. 4B, the roller 12-2 of the first rocker arm 12 is 2e by the eccentric portion e (see FIG. 1) of the control shaft 10. Move to the right by the minute.
That is, the contact position γ between the roller 12-2 of the first rocker arm 12 and the rotating cam 7 changes from “γ1” to “γ2”.
At this time, since the relationship of “γ1> γ2” is established, if the rotation direction of the rotating cam 7 is counterclockwise, the operation timing of the rotating cam 7 becomes earlier as the lift becomes smaller, as shown in FIG. Quick closing operation becomes possible.
Accordingly, when the valve closing timing is advanced as the lift amount of the engine valve 2 decreases, the relative movement amount of the first rocker arm 12 with respect to the second rocker arm 13 is increased, and the rotating cam 7 of the first rocker arm 12 is increased. The amount of movement of the contact point with respect to can be increased. Therefore, the timing of closing the engine valve 2 can be greatly advanced as the lift amount of the engine valve 2 is reduced, and the pumping loss reduction effect can be increased.

  The present invention is not limited to the above-described embodiments, and various application modifications can be made.

For example, in the embodiment of the present invention, two external gears are attached to one rocker arm and two valves are driven by one rotary cam 7. However, two rotary cams 7 and two rocker arms are used. A structure is also possible.
In the embodiment of the present invention, a roller finger follower (also referred to as “RFF”) type valve operating system is disclosed. However, the present invention can also be applied to a direct hitting valve operating system.
Furthermore, in the embodiment of the present invention, the roller is used at the contact point between the second rocker arm and the swing cam, but it is also possible to connect the second rocker arm and the swing cam with a link.

DESCRIPTION OF SYMBOLS 1 Variable valve operating apparatus of internal combustion engine 2 Engine valve 3 Valve head 4 Valve stem 5 Roller finger follower 6 Hydraulic lash adjuster 7 Rotating cam 8 Cam shaft 9 Oscillating cam 10 Control shaft 11 Rocker arm 12 1st rocker arm 13 2nd rocker arm DESCRIPTION OF SYMBOLS 14 Actuator 17 Position change mechanism 18 Eccentric shaft part 19 External gear 20 Internal gear O1 Control shaft rotation center O2 Shaft center B Base part L Lift part

Claims (3)

  A rocker arm that swingably supports a swing cam that lifts an engine valve on a cam shaft provided with a rotary cam, and that swings on the control shaft parallel to the cam shaft by the rotary cam and swings the swing cam. The rocker arm is divided into a first rocker arm that rocks by the rotating cam and a second rocker arm that rocks the rocking cam, and the positions of the first rocker arm and the second rocker arm are changed. A variable valve for an internal combustion engine, which is connected via a mechanism and changes the lift characteristic of the engine valve by changing the relative positional relationship between the first rocker arm and the second rocker arm by the position changing mechanism. In the apparatus, the control shaft is formed with a circular eccentric shaft portion whose center is eccentric with respect to the control shaft, and the first rocker arm is swingably supported by the eccentric shaft portion. In addition, an external gear having the eccentric shaft portion as a rotation shaft is formed on the first rocker arm, and an internal gear meshing with the external gear is formed on the second rocker arm by using the control shaft as a rotation shaft. The shaft portion, the external gear, and the internal gear constitute the position changing mechanism, the control shaft is rotated when the lift characteristic of the engine valve is changed, and the external gear is controlled by the eccentric shaft portion. Revolving around the axis of the shaft, and by revolving the external gear, the meshing point of the internal gear with respect to the external gear is moved in the circumferential direction of the internal gear, and the first gear is moved along with the movement of the meshing point. A variable valve operating apparatus for an internal combustion engine, wherein the position of the second rocker arm with respect to the rocker arm is changed.   2. The variable valve for an internal combustion engine according to claim 1, wherein when the lift amount of the engine valve is changed from maximum to minimum, the eccentric shaft portion rotates in a direction opposite to the rotary cam. apparatus.   The variable valve operating apparatus for an internal combustion engine according to claim 2, wherein the eccentric shaft portion is rotated by 180 ° about the center of the control shaft.

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