JPH09222007A - Engine valve gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the uneven wear of a stem tip part so as to improve the life of a stem by providing a relative movement regulating means for regulating relative movement between a body and a slider and bringing the slider moved in the axial direction of an intake/discharge valve and the stem tip part into contact with each other. SOLUTION: An engine valve system is provided with a relative movement regulating means for regulating relative movement between bodies 20, 23 and 24 and a slider 32. When relative movement is regulated, after a cam 11 is engaged with the body 20, the body 20 is moved together with the slider 32 and a stem 15 against the pressing force of a first spring 18 and thus an intake/ discharge valve 14 is opened/closed. After the regulation of the relative movement is released, the intake/discharge valve 14 is placed in a constantly stopped state. That is, since the slider 32 moved in the axial direction of the intake/ discharge valve 14 and the stem tip part are contacted with each other, the load of a direction orthogonal to the axial center of the stem 15 is prevented from being applied on the stem tip part. Thus, shaving of the stem tip part is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine valve operating system having a valve stop mechanism for stopping intake and exhaust valves.

[0002]

2. Description of the Related Art Heretofore, as a valve operating system of this type of engine, one disclosed in Japanese Patent Laid-Open No. 6-10637 has been known. This is an intake / exhaust valve that opens and closes an intake hole or an exhaust hole that opens in the engine combustion chamber, a valve stem connected to the intake / exhaust valve, a cam supported by a cam shaft, and a gap between the cam and the valve stem. And a valve stop mechanism capable of maintaining the intake and exhaust valves in the closed state. Here, the valve stopping mechanism includes a body slidably disposed in the cylinder head in the axial direction of the intake / exhaust valve, a body hole formed in the body, and having a shaft center orthogonal to the shaft center of the stem, A first stem insertion / extraction hole extending in the axial direction of the stem, wherein the hydraulic pressure acting on one end slides in the body hole so that the stem tip can enter the stem insertion / extraction hole.
A plunger that is biased to a position, and a spring that biases the plunger against the hydraulic pressure and maintains the plunger at a second position where the stem tip cannot enter the stem entry / exit hole when the hydraulic pressure is not acting. A slider made of wear-resistant material attached to the plunger so as to come into contact with the tip of the valve stem when the intake / exhaust valve operates, and a valve spring that biases the valve stem in the direction of closing the intake / exhaust valve. ing.

In the above-mentioned device, the slider made of the wear resistant material avoids the contact between the plunger and the tip of the valve stem to prevent the uneven wear of the plunger and the deviation of its axial center.

[0004]

However, in the above-mentioned device, although the contact between the plunger and the tip of the valve stem can be avoided, the slider that moves together with the plunger in the direction orthogonal to the axis of the valve stem and the tip of the valve stem. Because of the contact with the valve stem, a load from the slider in the direction orthogonal to the axis of the valve stem acts on the stem tip, causing the valve stem tip to wear unevenly, resulting in
If used for a long time, the tip of the valve stem may be scraped. Therefore, as the valve stem is used for a long period of time, the lift amount of the intake / exhaust valve is gradually reduced, which causes a problem that an appropriate lift amount cannot be secured. That is, there is a problem that the life of the valve stem is shortened.

Therefore, the present invention aims to suppress the uneven wear of the tip of the valve stem and improve the life of the valve stem.
It is a technical issue.

[0006]

The technical means taken in the invention of claim 1 to solve the above technical problems are as follows:
An intake / exhaust valve that opens and closes an intake hole or an exhaust hole that opens in the combustion chamber of the engine, a first spring that biases the stem in a direction to close the intake / exhaust valve, a cam, and between the cam and the intake / exhaust valve. A valve stop mechanism provided, wherein the valve stop mechanism is provided in a hole formed in the cylinder head of the engine so as to be movable in the axial direction of the intake / exhaust valve, and contacts the cam. A slider having a bottomed cylindrical shape, which is arranged in the hole so as to be movable in the axial direction of the intake / exhaust valve and relatively movable with respect to the body, and has an outer bottom portion in contact with the stem tip portion, and one end supported by the body, The other end is composed of a second spring supported on the inner bottom of the slider, and a relative movement restricting means capable of restricting relative movement between the body and the slider.

When the relative movement regulating means regulates the relative movement between the body and the slider, when the cam engages with the body, the body moves together with the slider and the stem against the biasing force of the first spring. As a result, the intake and exhaust valves are opened and closed.

On the other hand, when the relative movement regulating means releases the regulation of the relative movement between the body and the slider, even if the cam engages with the body and the body moves in the direction to open the intake / exhaust valve, Since the force acting on the body is not transmitted to the slider and the stem, the stem moves in the direction of closing the intake / exhaust valve while pressing the slider by the first spring. As a result, the intake / exhaust valve always remains inactive.

According to the above technical means, the slider moving in the axial direction of the intake / exhaust valve is brought into contact with the stem tip portion, so that a load is applied to the stem tip portion in a direction orthogonal to the stem axis. As a result, uneven wear of the stem tip is suppressed, and the stem tip is not scraped. Therefore, the life of the valve stem is improved.

Further, by making the slider have a bottomed cylindrical shape and supporting one end of the second spring on the inner bottom, the spring length when the spring is compressed can be stored inside the slider, and the axial length of the valve stop mechanism can be reduced. It can be shortened.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

A valve operating system for an engine will be described with reference to FIGS. Here, FIGS. 1 to 3 show the valve operating device of the engine when the intake and exhaust valves are operating (opening and closing),
4 and 5 show the valve operating device of the engine when the intake and exhaust valves are at rest (at a stop).

A valve operating system 10 for an engine shown in FIG. 1 is mounted on a cam 11 supported by a cam shaft (not shown) and a seat surface 13 formed on a cylinder head 12 of the engine to be installed in an engine combustion chamber (not shown). Intake and exhaust valve 14 for opening and closing an intake hole or an exhaust hole (not shown) that opens
And a valve stem (stem) connected to the intake / exhaust valve 14.
15 and a retainer 17 fixed on the outer circumference of the valve stem 15 via a cotter 16 at one end, and the intake / exhaust valve 1
A valve spring (first spring) 18 for urging the valve stem 15 in the direction of closing the valve 4 and a valve stop mechanism 19 arranged between the cam 11 and the valve stem 15. The valve stem 15 is made of a heat resistant material (heat resistant steel, for example).

In the valve stop mechanism 19, an outer body 20 having a bottomed cylindrical shape is slidable in a cylinder hole 12a formed in the cylinder head 12 of the engine so as to extend in the axial direction of the intake / exhaust valve 14. A disc-shaped outer shim 21 having an engagement surface with the cam 11 is arranged on the upper surface of the outer body 20. This Outer Shim 21
The clearance between the base circle of the cam 11 and the valve stop mechanism 19 is adjusted, and the outer diameter of the outer shim 21 is slightly smaller than the diameter of the cylinder hole 12a.

In the inner space 22 of the outer body 20,
Two vertically divided inner bodies 23, 24 are arranged so as to be movable integrally with the outer body 20. A spring 25 is arranged between the lower inner body 24 and the bottom surface of the cylinder hole 12a.
24 is urged in a direction of pressing the outer body 20 (that is, a direction of closing the intake / exhaust valve 14). A spring seat 26 is arranged between the spring 25 and the lower inner body 24. The upper inner body 23 is
It is supported so as to be unable to rotate relative to the outer body 20 via a rotation stop pin 27. The lower inner body 24 has a first axial center that matches the central axis of the valve stem 15.
The slider guide hole 28 is formed, and the upper inner body 23
A second slider guide hole 29 having an axial center coinciding with the axial center of the valve stem 14 and having a diameter larger than the diameter of the first slider guide hole 28 is formed in the. A body hole having an axis perpendicular to the axis of the valve stem 15 is formed between the inner bodies 23 and 24.
The second slider guide holes 28 and 29 intersect each other.
In addition, the outer body 20 and the inner body 23,
24 constitutes the body of the present invention. Further, both the inner bodies 23 and 24 described above may be integrated, or the outer body 20 and the inner bodies 23 and 24 may be integrated.

A slider 32 is slidably guided in the first and second slider guide holes 28 and 29 so as to be constantly in contact with the valve stem 15, and the slider 32 is
A spring (second spring) 33 arranged between the outer body 20 and the bottom surface of the outer body 20 urges the intake / exhaust valve 14 in the opening direction. The biasing force of the spring 33 is set to be smaller than the biasing force of the valve spring 18. More specifically, the slider 32 has a bottomed cylindrical shape with a substantially U-shaped cross section, and an annular groove 321 is formed in a flange portion of the outer peripheral portion thereof, and an inner bottom portion 322 supports one end of the spring 33. The outer bottom portion 323 is in contact with the valve stem 15.

The annular groove 321 is opened in the radial direction of the slider 32, can overlap the body hole, and has an opening width substantially the same as the axial width of the body hole. The outer circumference of the slider 32 is
The diameter is substantially the same as the diameter of the first slider guide hole 28. The flange portion of the slider 32 has an outer peripheral surface protruding in the radial direction of the slider 32 so as to form the upper surface of the annular groove 321, and the outer diameter thereof is substantially the same as the diameter of the second slider guide hole 29. The slider is made of a wear resistant material (for example, carburized material).

As shown in FIG. 3, the plate 3 having the same opening width as the annular groove 321 of the slider 32, that is, the width of the body hole in the intake / exhaust valve axial direction, is formed in the body hole.
4 is slidably guided. A through hole 35 penetrating the intake / exhaust valve 14 in the axial direction is formed in the plate 34, and the diameter of the through hole 35 is substantially the same as the outer diameter of the slider 32. The plate 34 itself enters the annular groove 321 formed in the slider 32 (that is, straddles the body hole 31 and the annular groove 321) at the first position (FIG. 1, FIG.
It moves from the state shown in FIGS. 2 and 3) to the second position (state shown in FIGS. 4 and 5) where it itself leaves the annular groove 321. Here, when the plate 34 is in the first position, the axis of the through hole 35 is deviated from the axis of the slider 32 as shown in FIGS. Inner Body 23,
It is immovable relative to 24. On the other hand, when the plate 34 is in the second position, the axial center of the through hole 35 coincides with the axial center of the slider 32 as shown in FIG. 5, so that the slider 32 together with the valve stem 15 as shown in FIG. , 24 relative to each other. The plate 34 is made of a wear resistant material (for example, carburized material).

A hydraulic chamber 36 is formed between the left end of the plate 34 and the outer body 20, and hydraulic pressure in an oil pan (not shown) is formed in the outer passage 20 and a hydraulic passage 37 formed in the cylinder head 12 by a hydraulic pump or the like. It is adapted to be supplied through an annular groove 38 and a passage 39. The hydraulic pressure supplied to the hydraulic chamber 36 is determined according to the operating state of the engine such as the engine speed and the engine load, and the state of FIG. 3 and the state of FIG. 5 can be arbitrarily switched.

On the other hand, a spring chamber 40 is formed between the right end of the plate 34 and the outer body 21. The spring chamber 40 has a width in the axial direction larger than the axial width of the body hole. Is formed by processing. A spring 41 is arranged in the spring chamber 40, and urges the plate 34 in a direction that opposes the hydraulic pressure, that is, in a direction that reduces the volume of the hydraulic chamber 36. Here, the urging force of the spring 41 is set to be smaller than the force of the hydraulic pressure, and when the hydraulic pressure is not acting in the hydraulic chamber 36, the urging force of the spring 41 causes the plate 34 to move to the positions shown in FIGS. It is maintained in the first position shown.

Next, the fitting portion between the annular groove 321 and the plate 34 will be described in the second and third embodiments. In the second embodiment shown in FIG. 6, the slider 32
The annular groove 321 formed by the flange portion of
1b, a tapered portion is formed, and the tapered portion 34 is fitted to the fitting portion of the plate 34 with the annular groove 321.
a and 34b are provided. In the third embodiment shown in FIG. 7, the taper angle of the annular groove 321 formed by the flange portion of the slider 32 is directed in the direction opposite to that in FIG.

The operation of the engine valve operating system 10 configured as described above will be described.

When the engine is started, a cam shaft (not shown) starts to rotate, and as a result, the cam 11 is rotationally driven. First, if you want to open and close the intake / exhaust valve 14 at all times,
The hydraulic pressure is supplied to the hydraulic chamber 36 to switch to the state shown in FIG. As a result, the plate 34 is in the first position and the plate 34
Part of it enters the annular groove 321 formed in the slider 32 (that is, the plate 34 straddles the body hole and the annular groove 321), so that the plate 34 is in the first position as shown in FIGS. Stop. This prevents relative movement between the slider 32 and the plate 34, that is, the outer body 20 and the inner bodies 23, 24.

Therefore, when the cam 11 contacts the outer shim 21 at the base circle and the rotation advances from the state shown in FIG. 1 to contact the outer shim 21 at the cam surface, the outer body 20 and the inner bodies 23, 24 together with the slider 32 together with the valve spring 18 are moved. And, it begins to sink downward in the figure against the biasing force of the spring 25 (see FIG. 2). That is, while the outer shim 21 is engaged with the cam surface of the cam 11, the force is transmitted to the outer body 20 → inner body 23 → plate 34 → slider 32 → valve stem 15 → intake / exhaust valve 14, and the cam surface cam The intake / exhaust valve 14 moves downward in the drawing against the biasing force of the valve spring 18 in accordance with the profile, and the intake / exhaust valve is separated from the seat surface 13 to perform intake or exhaust. At this time, the outer body 21 may rotate with respect to the cylinder hole 15a. In that case, however, since the outer shim 20 has a disc shape, the cam 11 always engages with the outer shim 21. The area of the engaging region of is always constant.

On the other hand, when it is desired to suspend the operation of the intake / exhaust valve 14, hydraulic pressure against the spring 41 is put in the hydraulic chamber 36 and the plate 34 is slid to the state shown in FIG. As a result, the plate 34 moves from the first position to the second position, a part of the plate 34 comes out of the annular groove 321, and the plate 34 has an axial center of the through hole 35 as shown in FIG. That is, the slider 32 stops at the second position that coincides with the axial center of the slider 32. As a result, the slider 32 and the plate 34, that is, the outer body 20 and the inner body 2
Relative movement between 3 and 24 is possible.

Therefore, even if the rotation of the cam 11 advances from the state where the cam 11 is in contact with the outer shim 21 at the base circle and the cam surface begins to make contact with the outer shim 21, the force of the cam 11 is transmitted to the outer body 20 and the inner bodies 23, 24. ,
It is not transmitted to the slider 32 and the valve stem 15. As a result, the slider 32 is pushed by the valve stem 15 by the urging force of the valve spring 18,
While being guided by the first slider guide hole 28 and the through hole 35, and the flange portion by the second slider guide hole 29, they move upward in the drawing against the biasing force of the spring 33 (see FIG. 4). In this way, since the force generated by the cam 11 is not transmitted to the intake / exhaust valve 14, the intake / exhaust valve 14 is maintained in the closed state, that is, the state in which it is seated on the seat surface 13, and intake or exhaust is not performed. Also at this time, the cam 11 is the outer shim 2
1, the area of the engagement area of the cam surface at that time is always constant.

As described above, in this embodiment, since the slider that abuts on the valve stem 15 is interposed between the valve stem 15 and the plate 34 that move in the directions orthogonal to each other, the tip end of the valve stem 15 is Plate 3
Since the contact of No. 4 is avoided, the partial wear of the tip portion of the valve stem 15 can be suppressed, and the tip portion of the valve stem 15 is not scraped even after long-term use. Therefore, the life of the valve stem 15 is improved.

Further, the slider 32 has a cylindrical shape with a bottom,
One end of the spring 33 is connected to the inner bottom portion 322 of the slider 32.
Since the spring 33 is held inside the slider 32 as shown in FIG. 4, when the spring 33 is compressed, the axial length of the valve stop mechanism can be shortened.

Further, as shown in FIG. 6, since the tapered portion is provided in the annular groove 321 of the slider 32 and the engaging portion of the plate 34, the engagement can be easily released from the first position to the second position. The switching response is improved. As shown in FIG. 7, the plate 34 is a flat plate as in the first embodiment, and the tapered portion is formed only in the annular groove 321 of the slider 32, so that the contact area of the engaging portion is reduced and At the time of switching from the position to the second position, the engaging portion adheres due to the presence of oil or the like that moves the plate,
The phenomenon that the engaging portion becomes difficult to separate does not occur.

Various embodiments are conceivable for the embodiment relating to the improvement of the response of switching from the first position to the second position, and the slider is not a taper as large as that shown in FIG. 32 annular grooves 32
The same effect can be obtained by forming a slight taper surface on each of the tip end portion of No. 1 and the upper surface of the plate 34.

[0031]

The invention of claim 1 has the following effects.

Since the slider moving in the axial direction of the intake / exhaust valve is brought into contact with the stem tip, a load is not applied to the stem tip in a direction orthogonal to the stem axis.
As a result, uneven wear of the stem tip can be suppressed. Therefore, even if the stem is used for a long period of time, the tip of the stem is not scraped.

Further, since the slider has a cylindrical shape with a bottom and one end of the spring is held by the inner bottom portion of the slider, the spring when the spring is compressed can be housed inside the slider, so that the shaft of the valve stop mechanism can be stored. The direction length can be shortened.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a cam of a valve operating system for an engine (when an intake / exhaust valve is operating) according to a first embodiment on a base surface.

FIG. 2 is a cross-sectional view when the cam surface of the valve operating system for an engine according to the first embodiment (when an intake / exhaust valve is operating) is in contact.

3 is a cross-sectional view taken along the line AA in FIG.

FIG. 4 is a cross-sectional view of a valve operating system for an engine (when intake and exhaust valves are at rest) according to the first embodiment.

FIG. 5 is a sectional view taken along line BB in FIG. 4;

FIG. 6 is an enlarged cross-sectional view of a slider and a plate when the plate of the second embodiment is present at the first position.

FIG. 7 is an enlarged cross-sectional view of a slider and a plate when the plate of the third embodiment is present at the first position.

[Explanation of symbols]

 10 Engine Valve Device 11 Cam 12 Cylinder Head 12a Cylinder Hole (Hole) 14 Intake / Exhaust Valve 15 Valve Stem (Stem) 18 Valve Spring (First Spring) 19 Valve Stop Mechanism 20 Outerbody 23, 24 Inner Body 26 Spring (4th) 32) Slider 321 Ring groove 322 Inner bottom of slider 323 Outer bottom of slider 33 Spring 34 Plate

Claims (1)

[Claims] 1. An intake / exhaust valve that opens and closes an intake hole or an exhaust hole that opens into a combustion chamber of an engine, a first spring that biases the stem in a direction of closing the intake and exhaust valve, a cam, and the cam. And a valve stop mechanism disposed between the intake and exhaust valves, the valve stop mechanism being movable in the axial direction of the intake and exhaust valves in a hole formed in the cylinder head of the engine. The body is disposed in contact with the cam, and the body is disposed in the hole so as to be movable in the axial direction of the intake / exhaust valve and relatively movable with respect to the body. A bottomed cylindrical slider, a second spring having one end supported by the body and the other end supported by the inner bottom portion of the slider, and a relative member capable of restricting relative movement between the body and the slider. An engine having a movement restricting means Valve operating device.