JPH10131727A - Variable valve system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously and infinitely adjust the lifting quantity of a valve in simple structure by providing a moving member freely movable in the longitudinal direction of a rocker arm, making it work as a fulcrum for the swing of the rocker arm and making the fulcrum for the swing of the rocker arm variable by moving the moving member. SOLUTION: When a rotary cam is rotated, and the cam circle contacts the contacting section 43 of a rocker arm 4, the rocker arm 4 is pushed down swings around a swing fulcrum A counterclockwise. This makes the projection 42 of the rocker arm 4 push down a slider 72, and this slider 72 pushes down an intake valve 3. In the next step, when a pinion gear 62 is rotated in a direction, a rack gear 61 slides along a guide section 22 in a direction. This makes a slider 41 slide together with a ball 63 in a direction, making the swing fulcrum A move approaching a variable datum point B. Therefore, the distance between the swing fulcrum A and the engaging point of the projection 42 and engaging groove 72a becomes short, shortening the length of the rocker arm 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve apparatus capable of adjusting a lift amount of a valve (an intake valve or an exhaust valve) that is opened and closed in synchronization with a crankshaft in an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as this kind of variable valve train,
Japanese Patent Application Laid-Open No. 6-280523 is known. It has a rotating cam that is rotated in synchronization with the crankshaft of the internal combustion engine, a rocker arm that is swung by the rotation of the rotating cam to lift the valve, and a variable mechanism that makes the rocking fulcrum of the rocker arm variable. Thus, the valve lift can be adjusted.

In this conventional apparatus, the variable mechanism is constituted by a large number of support links for defining a virtual rocking fulcrum of the rocker arm and supporting the rocker arm, and the rocking fulcrum of the rocker arm is moved by the movement of the large number of support links. The valve lift was adjusted continuously and steplessly by varying

[0004]

However, in the above-mentioned conventional device, a large number of support links are required to change the rocking fulcrum of the rocker arm, so that the structure is complicated, the number of parts is large, and the cost is low. It is disadvantageous both in terms of space and space. Further, since the rocking fulcrum of the rocker arm is virtually defined by a large number of support links, there is a possibility that the play present at the connecting portion of each link may move the rocking fulcrum of the rocker arm, and as a result, the lift amount of the valve However, it was not stable, and there was a risk of subtle changes.

Therefore, an object of the present invention is to make the rocking fulcrum of the rocker arm variable with a simpler structure.

[0006]

In order to solve the above-mentioned technical problem, the technical means adopted in the present invention is to guide the variable mechanism so that the rocker arm cannot slide with respect to the valve in the length direction of the rocker arm. A guide member that constitutes a variable reference point of the rocking arm of the rocker arm; and a rocking arm of the rocker arm that is supported by the rocker arm and that is movable with respect to the rocker arm in the length direction of the rocker arm. And a movable member.

According to this technical means, since the movable member movable in the length direction of the rocker arm forms the rocking fulcrum of the rocker arm, the rocking fulcrum of the rocker arm can be changed by moving this movable member. . Therefore, the variable mechanism can have a simple structure as compared with the related art.

More preferably, the movable member includes a first slider into which the rocker arm is movably fitted in the length direction of the rocker arm, and a rack gear supported movably in the length direction of the rocker arm. It is preferable to include a pinion gear meshed with the rack gear and linked to a drive source, and a spherical member disposed between the rack gear and the first slider and serving as a swing fulcrum of the rocker arm. .

[0009] More preferably, a second slider is provided between the rocker arm and the valve so as to be movable in the axial direction of the valve.
And a guide having a guide hole for movably supporting the slider.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a variable valve train includes a rotary cam 1 which is itself known and is rotated in synchronization with a crankshaft (not shown) of an internal combustion engine. A rocker arm 4 which lifts an intake valve 3 which opens and closes an intake hole 21 formed in a cylinder head 2 by being swung by the rotation of the cylinder head 2 against a valve spring 31.
And a variable mechanism 5 for changing the swing fulcrum A of the rocker arm 4
It has. The rocker arm 4 has, at one end, a shaft portion 71 to be inserted into a slider 63 of the movable member 6 described later, and at the other end, an arc-shaped projection 42 to be inserted into a slider 72 of the guide member 7 described later. I have.

The variable mechanism 5 is disposed between the rocker arm 4 and the cylinder head 2 and has a rocking fulcrum A of the rocker arm 4.
The movable member 6 and the guide member 7 disposed between the rocker arm 4 and the cylinder head 2 and the intake valve 3 and constituting the variable reference point B of the swing fulcrum A of the rocker arm 4
Mainly.

As shown in FIGS. 1 and 2, the movable member 6 includes a rack gear 61, a pinion gear 62, a slider 6
3 and a pair of balls 64. Cylinder head 2
Is formed with a guide portion 22 extending in the length direction of the rocker arm 4 (the left-right direction in FIG. 1).
1 is movably supported on the cylinder head 2 by the guide portion 22 in the longitudinal direction of the rocker arm 4. The tooth portion 61a of the rack gear 61 is formed in the length direction of the rocker arm 4. Further, the rack gear 61 is provided with a pair of hemispherically concave receiving surfaces 61b of the rocker arm 4, as shown in FIG. They are formed side by side in a direction perpendicular to the length direction (the left-right direction shown in FIG. 2; hereinafter, referred to as an axial direction). The pinion gear 62 is a rack gear 6
It is in mesh with the first tooth portion 62 and is linked to a drive source (not shown) such as a motor or an oil pump. Slider 63
Are supported by the rocker arm 4. This slider 6
A fitting hole 63a is formed in the end face of the shaft 3 so as to face the shaft portion 41 of the rocker arm 4. The fitting hole 63a has
The shaft portion 41 of the rocker arm 4 is fitted so as to be relatively slidable in the length direction of the rocker arm 4. This allows
The movable member 6 is movable with respect to the rocker arm 4 in the length direction of the rocker arm 4. As shown in FIG. 2, a pair of hemispherical concave receiving surfaces 63 b are formed on the bottom surface of the slider 63 so as to face the pair of receiving surfaces 61 b of the rack gear 61 and are arranged in parallel in the axial direction. The pair of balls 64 are disposed in the pair of receiving surfaces 61b of the rack gear 61 and the pair of receiving surfaces 63b of the slider 63, respectively, and support the slider 63 so as to be swingable with respect to the rack gear 61. It should be noted that a cylindrical member extending in the axial direction may be used instead of the pair of balls 64. In this case, the receiving surface 61b and the receiving surface 63b have a semicircular shape corresponding thereto.

As shown in FIGS. 1 and 3, the guide member 7 has a guide 71 and a slider 72. The guide 71 is fixed to the cylinder head 2, and a guide hole 71 a extending in the valve axial direction (vertical direction in FIG. 1) is formed coaxially with the shaft 32 of the intake valve 3. The slider 72 is provided in the guide hole 71a, and is movable along the guide hole 71a. The slider 72 is provided between the protrusion 42 of the rocker arm 4 and the intake valve 3.
Is located between the shaft tip 32a and the upper end thereof.
A hemispherical concave engaging groove 72a with which the protruding portion 42 is engaged is formed, and the lower end has a protruding portion 72 abutting on the shaft tip 32a.
b is formed. The protrusion 42 of the rocker arm 4 is engaged with the engagement groove 72a of the slider 72. As a result, the rocker arm 4 cannot move in the length direction.

With such a configuration, the ball 64 of the movable member 6 constitutes the swing fulcrum A of the rocker arm 4, and the engagement between the projection 42 of the rocker arm 4 and the engagement groove 72 a of the slider 72 of the guide member 7. The combination becomes the variable reference point B of the rocking fulcrum A of the rocker arm 4. Further, relative sliding between the rocker arm 4 and the slider changes the length from the swing fulcrum A to the variable reference point B, that is, the length of the rocker arm 4. That is, the slider 63 of the movable member 6 forms a part of the rocker arm 4 and divides the rocker arm 4 into two parts so as to be extendable and contractible in its length direction.

Next, the operation will be described.

As shown in FIGS. 4 and 5, the rotary cam 1 rotates and its cam circle is moved to the contact portion 72 of the rocker arm 4.
, The rocker arm 4 is pushed down and swings around the swing fulcrum A in the counterclockwise direction shown in FIGS. As a result, the protrusion 42 of the rocker arm 4 pushes down the slider 72, and the slider 72 pushes down the intake valve 3 against the urging force of the valve spring 31. As a result, the contact between the valve portion 33 of the intake valve 3 and the seat surface 21a of the intake hole 21 is released, and the intake hole 21 is opened (FIGS. 4 and 5).
Dotted line state). When the rotating cam 1 further rotates and its base circle comes into contact with the contact portion 43 of the rocker arm 4,
Since the depression of the rocker arm 4 is released, the rocker arm 4, the slider 72 and the intake valve 3 are pushed up by the urging force of the valve spring 31. As a result, the valve portion 33 of the intake valve 3 comes into contact with the seat surface 21a of the intake hole 21, and the intake hole 21 is closed (the state shown by the solid lines in FIGS. 4 and 5). At this time, the movement trajectory of the protrusion 42 and the slider 72
The movement trajectory is absorbed by the protrusion 42 sliding relative to the engagement groove 72a within the engagement groove 72a, thereby suppressing the occurrence of the rocker arm 4 from twisting. In addition, the slider 72 disposed between the intake valve 3 and the rocker arm 4 does not cause the intake valve 3 to receive a lateral load due to the movement of the projection 42 of the rocker arm 4.

When the pinion gear 62 rotates in one direction due to the operation of the drive source, the rack gear 61 slides in one direction along the guide portion 22 by meshing between the tooth portion 61a and the pinion gear 62. At this time, the rocker arm 4 is
The movement of the rack gear 61 in the length direction is restricted by the engagement of the rack gear 61 with the engagement groove 72a, so that the slider 41 slides in one direction with the ball 63 integrally with the rack gear 61 with respect to the rocker arm 4. Then, the swing fulcrum A moves so as to approach the variable reference point B. As a result, the distance L1 from the swing fulcrum A to the engagement point (action point) between the protrusion 42 and the engagement groove 72a becomes shorter, that is, the length of the rocker arm 4 becomes shorter, and the swing fulcrum A with respect to the distance L1 becomes shorter. The distance L2 to the contact point (point of force) between the contact portion 43 and the rotary cam 1 is as shown in FIG. As a result, the intake valve 3
The intake hole 21 is opened and closed by the lift amount of L3.

When the pinion gear 62 rotates in the other direction due to the operation of the drive source, the rack gear 61 slides in the other direction along the guide portion 22 due to the meshing of the teeth 61a and the pinion gear 62. At this time, the rocker arm 4 is
The movement of the rack gear 61 in the length direction is restricted by the engagement of the rack gear 61 with the engagement groove 72a. Then, the swing fulcrum A moves away from the variable reference point B. As a result, the distance L1 from the swing fulcrum A to the engagement point (action point) between the protrusion 42 and the engagement groove 72a becomes longer, that is, the length of the rocker arm 4 becomes longer. The distance L2 to the contact point (point of force) between the contact portion 43 and the rotary cam 1 is as shown in FIG. As a result, the intake valve 3 opens and closes the intake hole 21 with the lift amount of L4.

The lift of the intake valve 3 shown in FIGS. 4 and 5 is illustrated in FIG. As can be seen from FIG. 6, the lift amount L4 in the state of FIG. 5 is smaller than the lift amount L3 in the state of FIG. Thus, the swing fulcrum A
Is moved, the lift amount of the intake valve 3 is varied continuously and steplessly. Therefore, the lift amount can be more reliably changed with a simpler structure than that in which the lift point of the intake valve 3 is changed by moving the power point.

The operation of the drive source is controlled based on the engine speed and load. Further, in the above-described embodiment of the present invention, the description has been made by applying the present invention to the intake valve 3, but it goes without saying that the present invention can also be applied to the exhaust valve.

[0021]

According to the present invention, a guide member forming a variable reference point of the rocking arm fulcrum and a movable member forming a rocking fulcrum of the rocker arm are provided, and the movable member is moved to move the rocker arm. Since the rocking fulcrum is changed by changing the length, the rocking fulcrum of the rocker arm can be changed with a smaller number of parts having a simple structure as compared with the related art. As a result, cost and space can be improved as compared with the related art. Also, there is less backlash between the constituent parts than in the prior art, and a more stable valve lift can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a variable valve device according to the present invention.

FIG. 2 is a sectional view taken along line CC of FIG.

FIG. 3 is a sectional view taken along line DD of FIG. 1;

FIG. 4 is a view showing the operation of the variable valve apparatus according to the present invention in a state where the lift amount is large.

FIG. 5 is a view showing the operation of the variable valve apparatus according to the present invention in a state where the lift amount is small.

FIG. 6 is a diagram showing a lift state of a valve of the variable valve apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating cam 3 Valve 4 Rocker arm 5 Variable mechanism 6 Movable member 7 Guide member A Swing fulcrum B Variable reference point 61 Rack gear 63 Slider (first slider) 64 Ball (spherical member) 71 Guide 72 Slider (second slider) 71a Guide hole

Claims (3)

[Claims] 1. A rotary cam that is rotated in synchronization with a crankshaft of an internal combustion engine, a rocker arm that is swung by the rotation of the rotary cam to lift a valve, and a variable mechanism that makes a rocking fulcrum of the rocker arm variable. In the variable valve operating apparatus having a lift amount of the valve that can be adjusted, the variable mechanism guides the rocker arm immovably with respect to the valve in a length direction of the rocker arm. A guide member that constitutes a variable reference point of a swing fulcrum, and a movable member that is supported by the rocker arm and that is movable with respect to the rocker arm in the length direction of the rocker arm and that constitutes a swing fulcrum of the rocker arm. A variable valve train having and configured. 2. A first slider in which the rocker arm is movably fitted in the length direction of the rocker arm, a rack gear supported movably in the length direction of the rocker arm, and the rack gear. And a spherical member which is disposed between the rack gear and the first slider and serves as a rocking fulcrum of the rocker arm.
The variable valve train according to claim 1. 3. A second slider disposed between the rocker arm and the valve so as to be movable in an axial direction of the valve, and the guide member is supported so as to be movable and movable. The variable valve train according to claim 1, further comprising: a guide having a guide hole formed.