JPH0241282Y2 - - Google Patents

Description

[Detailed description of the invention] A. Purpose of the invention (1) Industrial application field The present invention is designed to fit and swingably support the first spherical end provided at the tip of the plunger of a hydraulic tappet. At one end of the cam follower that slides into contact with the cam,
A spherical recess is provided, and second and third spherical recesses facing each other are provided on the other end of the cam follower and a rocker arm that is swingable to open and close the valve. Second
and a valve train for an internal combustion engine in which the third spherical end is fitted into the second and third spherical recesses.

(2) Conventional technology Conventionally, in such a valve train, the opening edge of each spherical recess is generally formed at almost the same position as the center of the spherical end in the fitted state (Japanese Patent Laid-Open No. 60-1999) −
(See Publication No. 35106).

(3) Problems to be solved by the invention However, in the conventional device described above, when the plunger is held in the most contracted state due to abnormal operation of the hydraulic tappet, the second and third spherical ends and the second There is also a risk that one of the engagement states with the third spherical recess may be released and the push rod may fall off.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a valve operating system for an internal combustion engine that can prevent the push rod from falling off from the rocker arm and cam follower even if an abnormality occurs in the hydraulic tappet. purpose.

B. Structure of the invention (1) Means for solving the problem According to the invention, a first imaginary straight line connecting the centers of the first and second spherical ends in a normally fitted state;
The second and third The opening edge of at least one of the spherical recesses has a length equal to or greater than the value obtained by multiplying the stroke amount of the hydraulic tappet by the ratio of the second distance to the first distance. It is formed to protrude toward the push rod side from the center of the end portion.

(2) Effect When the plunger remains contracted due to an abnormality in the hydraulic tappet, even if the cam follower is separated from the push rod to the maximum extent, the second and third spherical ends remain within the second and third spherical recesses. ,
This prevents the push rod from falling off.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings. First, in FIG. 1, a cylinder head 1 of an internal combustion engine has a combustion chamber 2, and intake and exhaust ports 3i opening into the combustion chamber 2. , 3e are formed, and the intake and exhaust ports 3i and 3e are connected to the intake and exhaust valve 4.
It is opened and closed by i and 4e.

The intake and exhaust valves 4i, 4e are connected to valve guides 5i, 5e.
It is supported by the cylinder head 1 through the cylinder head 1 so as to be able to move up and down, and is urged toward the closing side by valve springs 6i and 6e.

A single camshaft 7 is disposed above the intake valve 4i and is connected to a crankshaft (not shown). It is rotatably supported by the cam holder 9 to which it is tied. Moreover, the camshaft 7 is provided with an intake cam 7i and an exhaust cam 7e corresponding to the intake and exhaust valves 4i and 4e. A first cam follower _{10 1} is interposed between the exhaust cam 7i and the head of the intake valve 4i, and the base end of the first cam follower 10 ₁ is connected to the support hole 11 ₁ of the cylinder head 1.
It is swingably supported by a first hydraulic tappet 12 ₁ attached to.

An intermediate portion of one side of the second cam follower 10 ₂ is in sliding contact with the exhaust cam 7e on the exhaust valve 4e side. One or lower end of the second cam follower ₁₀₂ is swingably supported by a second hydraulic tappet ₁₂₂ fitted in another support hole ₁₁₂ of the cylinder head 1.
Further, the other end, that is, the upper end of the second cam follower 10 ₂ is connected to the exhaust valve 4e via the interlocking mechanism 13.

The interlocking mechanism 13 includes a bell crank-shaped rocker arm 15 which engages the head of the exhaust valve 4e at one end to open and close the exhaust valve 4e, and is swingably supported by the cylinder head 1 via a rocker shaft 16. ,
a push rod 14 interposed between the other end of the rocker arm 15 and the other end of the second cam follower ₁₀₂ ;
It consists of

The structures of the first and second hydraulic tappets 12 ₁ , 12 ₂ are basically the same, and only the structure of the second hydraulic tappet 12 ₂ will be described in detail below.

In FIG. 2, the second hydraulic tappet 12 ₂ is
It includes a cylinder 17 that is fitted into the support hole 11 ₂ and a plunger 19 that slides on the cylinder 17 and defines a hydraulic chamber 18 . The plunger 19 is formed with an oil reservoir chamber 21 and a valve hole 22 that communicates the oil reservoir chamber 21 with the hydraulic chamber 18.
It communicates with an oil supply passage 25 of the cylinder head 1 through oil holes 23 and 24 in the side walls of the plunger 19 and the cylinder 17. Thereby, the oil reservoir chamber 21 is always filled with oil supplied from the oil supply path 25.

A cap-shaped valve cage 26 is fitted into the inner end of the plunger 19, and inside this valve cage 26 is a spherical check valve 27 that opens and closes the valve hole 22, and a spherical check valve 27 that opens and closes the valve hole 22. A biasing spring 28 is housed therein. As a result, the check valve 27 opens when the pressure in the hydraulic chamber 28 is reduced.
Operates to close the valve when pressure increases. Further, the hydraulic chamber 18 accommodates an extrusion spring 29 that urges the plunger 19 in the extension direction.

A first spherical end 19 is provided at the tip of the plunger 19.
a, and a first spherical recess 20 for fitting the _first spherical end 19a is provided at one end, that is, the lower end, of the second cam follower 102.

Further, second and third spherical recesses 33 and 34 are provided at the other end of the second cam follower 10 ₂ and the other end of the rocker arm 15 , and second and third spherical recesses 33 are provided at both ends of the push rod 14 . , 34, the second and third spherical ends 14a, 14b fit into the second and third spherical ends 14a, 14b
will be provided.

Referring also to FIG. 3, the opening edge of the second spherical recess 33 is connected to the second spherical end 1 in a normal fitted state.
It is formed so as to protrude toward the push rod 14 by a distance l3 from the center C2 of 4a.

Here, a first imaginary straight line L1 connecting the centers C1 and C2 of the first and second spherical end portions 19a and 14a that are properly fitted into the first and second spherical recesses 20 and 33, and a second cam follower 10 ₂ and the first and second spherical ends 1 from the intersection point P2 perpendicular to the second virtual straight line L2 passing through the sliding contact point P1 to the exhaust cam 7e.
The distance to the centers C1 and C2 of 9a and 14a is the first
and second distances l1 and l2. Further, the stroke amount of the plunger 19 in the second hydraulic tappet 12 ₂ is assumed to be S. Then, plunger 1
9 is in the maximum contracted state, the distance x that the second spherical recess 33 can rotate in the direction away from the second spherical end 14a is determined by the stroke ratio of the second distance l2 to the first distance l1. It is the value multiplied by the amount S. That is, x=l2/l1·S. Therefore, the protrusion amount l3 of the opening edge of the second spherical recess 33 is set to be greater than or equal to the distance x (l3≧x).

Next, the operation of this embodiment will be described. During operation of the engine, the camshaft 7 is rotationally driven from a crankshaft (not shown) via a timing transmission. At the start of the engine's intake stroke, the protruding portion of the intake cam 7i presses the first cam follower ₁₀₁ , which opens the intake valve _4i against the elastic force of the valve spring 6i, opening the intake port. Fresh air is drawn into the combustion chamber 2 through 3i.

Also, at the start of the exhaust stroke of the engine, the exhaust cam 7e
The raised portion presses the second cam follower ₁₀₂ . As a result, the second cam follower ₁₀₂ swings using the second hydraulic tappet ₁₂₁ as a fulcrum to press the push rod 14, and thereby the rocker arm 1
5 opens the exhaust valve 4e against the elastic force of the valve spring 6e, and exhaust gas is discharged from the combustion chamber 2 to the exhaust port 3e.

Here, to explain the valve head gap elimination function of the second hydraulic tappet ₁₂₂ , the exhaust cam 7e
When lifting the cam follower 10 ₂ , a pressing force is applied from the second cam follower 10 ₂ to the plunger 19 , but since the check valve 27 remains closed, hydraulic pressure is generated in the hydraulic chamber 18 . This oil pressure supports the back of the plunger 19, and one end of the second cam follower ₁₀₂ is supported by the first spherical end 19a of the plunger 19. As a result, the second cam follower ₁₀₂ swings so as to press the push rod 14, and during this period, oil in the hydraulic chamber 18 leaks slightly from the sliding gap between the cylinder 17 and the plunger 19.

When the exhaust cam 7e releases the lifting action on the second cam follower ₁₀₂ , the extrusion spring 2
9 extends the plunger 19 to bring the sliding surface of the second cam follower 10 ₂ into contact with the exhaust cam 7e. As a result, when the pressure in the hydraulic chamber 18 is reduced, the check valve 27 is opened, so that the oil in the oil reservoir chamber 21 is discharged from the valve hole 2.
2 to the hydraulic chamber 18, and the leaked oil from the hydraulic chamber 18 is replenished. In this way, from the valve head gap, that is, the exhaust cam 7e, to the exhaust valve 4
The gap in the joint leading to e is eliminated.

Now, assume that an abnormal operation of the second hydraulic tappet ₁₂₂ occurs, for example, air is trapped in the hydraulic chamber 18, or the plunger 19 seizes or becomes stuck in a contracted state. In such a case, the plunger 19 remains contracted, so when the base surface comes into sliding contact with the second cam follower 10 ₂ after passing through the protrusion of the exhaust cam 7e, the second cam follower 10 ₂ 2nd of Pushrod 14
The spherical end portion 14a can be rotated in a direction in which the spherical end portion 14a is removed from the second spherical recess 33. However, the opening edge of the second spherical recess 33 is located at the center C2 of the second spherical end 14a.
The second spherical recess 33 protrudes by a distance l3 from the second spherical end 14a, and the distance l3 is set to be greater than or equal to a distance x that allows the second spherical recess 33 to rotate in a direction away from the second spherical end 14a. Therefore, even if an abnormality occurs in the second hydraulic tappet 12 ₂ , the push rod 14 will not fall off from between the second cam follower 10 ₂ and the rocker arm 15 .

In the above embodiments, only the dimensions of the second spherical recess 33 are set based on the present invention, but the dimensions of the third spherical recess 34 may also be set based on the present invention. Both the second and third spherical recesses 33 and 34 may be set based on the present invention.

C. Effects of the invention As described above, according to the invention, the stroke amount of the plunger of the hydraulic tappet and the dimensional ratio of the first and second spherical ends up to the portion corresponding to the sliding contact position of the cam follower to the cam can be adjusted. Based on this, the amount of protrusion from the center of the second and third spherical ends of the second and third spherical recesses is determined, thereby reliably preventing the push rod from falling off even if the hydraulic tappet malfunctions. be able to.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a vertical sectional side view showing a part of an internal combustion engine equipped with the device of the present invention, FIG. 2 is an enlarged sectional view of the main part of FIG. 1,
FIG. 3 is an enlarged sectional view showing how the second spherical end is fitted into the second spherical recess. 4e...Valve, 10 ₂ ...Cam follower, 12 ₂ ...
Hydraulic tappet, 14...Push rod, 14a
...Second spherical end, 14b...Third spherical end, 1
9... Plunger, 19a... First spherical end, 2
0...First spherical recess, 33...Second spherical recess, 3
4... Third spherical recess, C1, C2... Center, l1
~l3...distance, L1...first virtual straight line, L2...
...Second virtual straight line, P1...Sliding contact point, P2...Intersection point.

Claims (1)

[Scope of utility model registration request] A first spherical recess is provided at one end of the cam follower that slides in contact with the cam, in order to fit and swingably support the first spherical end provided at the tip of the plunger of the hydraulic tappet, and the other end of the cam follower, The rocker arm, which is swingable to open and close the valve, is provided with second and third spherical recesses facing each other, and second and third spherical recesses provided at both ends of the push rod are provided with second and third spherical recesses that face each other. 3. In a valve train of an internal combustion engine fitted into a spherical recess, a first imaginary straight line connecting the centers of the first and second spherical ends in a normally fitted state passes through a sliding contact point of the cam follower to the cam. Second
When the distances from the intersection of the virtual straight line orthogonally to the centers of the first and second spherical ends are the first and second distances, the opening edge of at least one of the second and third spherical recesses is , protrudes toward the push rod from the centers of the second and third spherical ends in a normally fitted state by a length equal to or greater than the value obtained by multiplying the stroke amount of the hydraulic tappet by the ratio of the second distance to the first distance. A valve train for an internal combustion engine, characterized in that: