JPH05340226A - Variable lift valve - Google Patents

Abstract

PURPOSE:To improve the drive responsiveness of a rocker arm and a valve body by carrying out the valve body control without adding the inertial weight to a valve system by installing the first and second revolution members which can revolve in parallel to the axis direction of the valve body and a driving means for revolutionally driving the second revolution member on a fulcrum varying mechanism and permitting the mutual engagement at the position in deflection from the axis. CONSTITUTION:One end of a rocker arm 15 is engaged with the upper end of a valve body 13. The rocker arm 15 is swung around the center of swing, accompanied with the revolution of a cam 17. The position of the fulcrum 16 of the rocker arm 15 is varied by a fulcrum varying mechanism 21. The first revolution member 22 which is turnable through a supporting part 22 is engaged with the rocker arm 15. The position of the fulcrum 16 is the position in deflection from each revolution axis of the first and second revolution members 23 and 25. Each revolution axis of the first and second revolution members 23 and 25 is set parallel to the axis direction of the valve body 13. The second revolution member 25 is revolution-driven by a driving means 41. Accordingly, the valve body control is carried out without adding the inertial weight to a valve system, and the excellent drive responsiveness of the cam, rocker arm, and the valve body can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable lift valve, which is used, for example, to change the lift amount of an intake / exhaust valve of an engine.

[0002]

2. Description of the Related Art As a prior art relating to the present invention, there is a "valve device for an internal combustion engine" disclosed in Japanese Patent Application Laid-Open No. 2-78720. This conventional technique will be described with reference to FIG. 4. The rocker arms 71, 72, 73 are swingably arranged around a rocker shaft 74. here,
The rocker arms 71 and 73 are engaged with the respective valve bodies (not shown), and the rocker arm 71 is provided with a low speed cam (not shown) (not shown) and the rocker arm 72 is provided with not shown high speed cam (not shown). Are engaged with perfect circular cams (projection amount 0). Here, the two valve bodies act as two intake valves (or exhaust valves) arranged in one cylinder. Rocker arms 71, 72, 7
3, continuous cylinders 75, 76, 77 are formed,
Pistons 78, 79, 80 divided into three parts are slidably inserted therein. Further, a pressure chamber 81 is formed by the cylinder 75 and the piston 78, and a spring 84 is arranged in the pressure chamber 81 and the rocker shaft 7
The oil pressure is supplied from the oil supply passage 82 formed in the engine 4 through the oil passage 83 formed in the rocker arm 71. On the other hand, a spring chamber 85 is formed by the cylinder 77 and the piston 80, and a spring 86 arranged inside thereof urges the pistons 78, 79, 80 upward in the drawing.

In this "valve system for internal combustion engine", the state shown in FIG. 4 is when the internal combustion engine has a low load, the amount of hydraulic pressure supplied to the pressure chamber 81 is small, and each piston 78, 79, 80 has a spring 86. The contacting surfaces are in sliding contact with each other at the positions shown in the figure by the urging force of. Therefore, the rocker arm 71 swings only by the low speed cam, the rocker arm 72 swings only by the high speed cam, and the rocker arm 73 does not swing because it engages with the perfect circular cam. As a result, the rocker arm 71
Only the valve element that engages with opens and closes with a small stroke. That is, only one intake valve is opened / closed in one cylinder.

On the other hand, when the internal combustion engine is under heavy load, the amount of hydraulic pressure supplied to the pressure chamber 81 is increased so that the pistons 78, 79,
80 moves downward in the drawing against the biasing force of the spring 86. As a result, the piston 75 moves to the rocker arm 71,
The rocker arms 71, 72, 73 are integrally connected by the pistons 75, 76 because the pistons 76 are located so as to connect the rocker arms 72, 73 with each other. At this time, the high-speed cam moves more than the rocker arm 7 than the low-speed cam swings the rocker arm 71.
Since the amount of rocking 2 is larger, the integrated rocker arms 71, 72, 73 rock according to the profile of the high speed cam. Therefore, both the valve bodies engaging with the rocker arms 71 and 73 open and close with a large stroke. That is,
There are two intake valves opened and closed in one cylinder. As a result, a larger amount of air can be taken into the combustion chamber (not shown) than when the internal combustion engine has a low load.

[0005]

However, in the above-mentioned "valve device for internal combustion engine", three rocker arms for opening and closing two valve bodies are required, and the rocker arms are provided with pistons, springs and the like. Since it is installed, the inertial weight of the valve train is increased, which is disadvantageous in the open / close response of the valve body.

In view of this, the present invention has as its technical subject to perform valve body control without adding inertial weight to the valve train.

[0007]

[Constitution of the invention]

[0008]

The technical means of the present invention taken to solve the above-mentioned technical problems of the present invention includes a valve body, a rocker arm having one end engaged with the valve body, and a rocker arm. A variable lift valve is composed of a cam that opens and closes the valve element via a fulcrum and a fulcrum variable mechanism that engages with the other end of the rocker arm. It has two rotating members and a driving means for driving the second rotating member to rotate, and the first and second rotating members are engaged with each other at a position eccentric to the rotation shaft thereof.

[0009]

According to the above-mentioned technical means of the present invention,
The second rotating member engages with each other at a position eccentric to the rotating shaft, and this engaging position acts as a fulcrum of the rocker arm. As a result, the fulcrum of the rocker arm changes according to the amount of rotation of the first and second rotating members, and the lift amount of the valve element is variable.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the technical means of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, a valve body (intake valve or exhaust valve) 13 is arranged in an intake passage (or exhaust passage) 12 of an engine 11 so as to be separable from a valve seat 14. One end of a rocker arm 15 is engaged with the upper end of the valve body 13 in the drawing, and the rocker arm 15 is swung with the rotation of a cam 17 around a fulcrum 16 as its swing center. A roller 18 is provided at a contact portion between the rocker arm 15 and the cam 17, and the cam 17 is connected to the engine 11 via a cam shaft 40.
It is driven by an output shaft (not shown). Engine 11
A spring 20 is arranged between the main body and the cotter 19 fixedly mounted on the valve body 13, and urges the valve body 13 in a direction to be seated on the valve seat 14.

The position of the fulcrum 16 of the rocker arm 15 is made variable by a fulcrum changing mechanism 21. The rocker arm 15 includes a first rotating member 2 which is rotatable via a support 22.
3 is engaged, and the spherical concave portion 24 is formed in the first rotating member 23.
Are formed. Then, the spherical concave portion 24 has a second
The spherical convex portion 26 of the rotating member 25 is engaged. That is, the fulcrum 16 is composed of the spherical concave portion 24 and the spherical convex portion 26, and the position of the fulcrum 16 is eccentric to the rotation shafts of the first and second rotating members 23 and 25. The rotation axes of the first and second rotating members 23 and 25 are parallel to the axial direction of the valve body 13.

The second rotating member 25 is rotationally driven by the driving means 41 as shown in FIG.

That is, the pinion gear 42 formed around the lower end of the second rotating member 25 and the rack 43 mesh with each other, and the rack 43 reciprocates in the direction perpendicular to the axial direction of the second rotating member 25. It is driven by a hydraulic control means (not shown).

The second rotating member 25 is the lash adjuster 2
It forms part of 7. That is, the bottomed tubular housing 28 of the lash adjuster 27 is embedded in the main body of the engine 11, and the cylinders 29 and 30 are fitted in the housing 28. The second rotating member 25 acting as a piston is slidably inserted into the cylinder 29, and the piston 31 of the cylinder 30 is slidably inserted therein. The interior of the piston 31 is divided into two spaces by the communication hole 32, one of which forms a pressure chamber 33 together with the bottom of the cylinder 30, and the other of which forms a reservoir chamber 34 together with the space inside the second rotating member 25. The communication hole 32 is opened / closed by a check valve 35 arranged in the pressure chamber 33, so that the pressure in the pressure chamber 33 is always kept constant. Further, in the pressure chamber 33 and the reservoir chamber 34, an oil supply passage 36 communicating with an oil pressure source (not shown), an oil passage 37 formed in the housing 28, the cylinder 29, and the second rotating member 25,
Hydraulic pressure is supplied via 38 and 39.

The operation of the variable lift valve having the above structure will be described. The cam shaft 40 and the cam 17 rotate as the engine 11 starts. As a result, cam 1
Rocker arm 15 is a fulcrum based on the profile of 7
The rocker arm 15 swings about 6 and the valve body 13 is opened and closed by the left end of the rocker arm 15 in the figure. Now the engine 11
When the load is high, the drive unit 41 controls the rotational position of the second rotating member 25 so that the fulcrum 16 comes to the position shown in FIG. As a result, the rocking amount of the rocker arm 15 at the left end in the drawing increases and the lift amount of the valve body 13 increases, so that a large amount of air is supplied from the intake passage 12 to the combustion chamber (not shown).

Further, when the engine 11 is under a low load, the driving means 4 is arranged so that the fulcrum 16 comes to the position shown in FIG.
1 controls the rotational position of the second rotating member 25.
That is, the rack 43 moves from the state shown in FIG.
2 is rotated to rotate the second rotating member 25,
The first rotating member 23 via the spherical concave portion 24 and the spherical convex portion 26.
Also rotates integrally around the support portion 22. As a result,
Since the rocking amount of the rocker arm 15 at the left end in the drawing is relatively small and the lift amount of the valve body 13 is small, the air supplied from the intake passage 12 to the combustion chamber is relatively small.

The position of the fulcrum 16 is not limited to the position shown in FIGS. 1 and 3, but the rotation amounts of the first and second rotating members 23 and 25 are controlled according to the load of the engine 11. The position of the fulcrum 16 may be continuously variable.

[0019]

As described above, in the variable lift valve of the present invention, the first and second rotating members are engaged with each other at a position eccentric with respect to the rotating shaft thereof, and this engaging position swings the rocker arm. Since it acts as a fulcrum, the fulcrum of the rocker arm changes depending on the amount of rotation of the first and second rotating members, and the lift amount of the valve element can be made variable. When changing the lift amount of this valve body,
Since there is no additional weight on the cam, rocker arm and valve body, that is, no inertial weight is added, the drive response of the cam, rocker arm and valve body is excellent.

Further, the amount of rotation of the first and second rotating members can be set to an arbitrary amount, and the fulcrum position of the rocker arm can be continuously changed. Therefore, the lift amount of the valve body can also be continuously changed. Can be

[Brief description of drawings]

FIG. 1 is a partial sectional view of a variable lift valve according to an embodiment of the present invention.

FIG. 2 shows an enlarged configuration diagram of a main part in FIG.

FIG. 3 is a sectional view of a main part of a variable lift valve in a state different from that of FIG.

FIG. 4 is a sectional view of a main part of a valve operating system for an internal combustion engine according to the related art.

[Explanation of symbols]

 13 valve body, 15 rocker arm, 17 cam, 21 fulcrum variable mechanism, 23 1st rotation member, 25 2nd rotation member, 41 drive means.

Claims (1)

[Claims] 1. A valve body, a rocker arm that engages the valve body with one end thereof, a cam that drives the valve body to open and close through the rocker arm, and a fulcrum variable mechanism that engages with the other end of the rocker arm. The fulcrum variable mechanism includes first and second rotating members that are rotatable in parallel with the axial direction of the valve body, and drive means that rotationally drives the second rotating member. A variable lift valve characterized in that the two rotary members engage with each other at a position eccentric to the rotary shaft thereof.