JPH1122428A - Valve system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve combustion by making it easy to generate an intake swirl flow at the time when intake air-fuel mixture flows in a combustion chamber in the case of making a valve an intake air valve. SOLUTION: A roughly columnar rotational guide 21 is stored in a cylindrical groove 20 free to revolve, a stem guide 10 is inserted into a hole 21a for guide of the rotational guide 21, a semi-spherical recessed surface 23 is formed on a locker arm 17, and a roughly spherical protruded part 24 along the recessed surface part 23 is formed on a valve stem 7. When the locker arm 17 is revolved and the valve stem 7 is pressurized against a spring 14, an air intake valve 8 is opened and the valve stem 7 is revolved at an angle θ through the rotational guide 21, a mushroom part 7a is biased relative to a center of a valve seat 6 and opening areas of a biased front part R1 and a biased rear part R2 become different from each other, and accordingly, an intake swirl flow is easy to be generated, and it is possible to improve combustion. As it is possible to improve combustion without providing a shroud conventionally required, restraint of a flow of intake air by the shroud is avoided, and it is possible to improve a flow coefficient and accordingly, engine performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve mechanism for an internal combustion engine used in a vehicle.

[0002]

2. Description of the Related Art FIGS. 3 and 4 show an example of a conventional valve mechanism of an internal combustion engine. 3 and 4, a cylinder head 2 is arranged on the upper surface of a cylinder block 1. The lower surface of the cylinder head 2 has a concave portion 2a
And forms a combustion chamber 4 with the cylinder 3.

[0003] An intake passage 5 is formed in the cylinder head 2. The intake passage 5 is opened in the concave portion 2a, and the valve seat 6 is press-fitted into the opening 5a. The valve seat 6 has an umbrella part 7 provided on the tip side of the valve stem 7.
a is arranged so as to be able to be seated (to open and close the intake passage 5). A valve (intake valve) 8 is constituted by the valve seat 6, the umbrella portion 7a, the valve stem 7, and the like. A hole (hereinafter referred to as a valve hole) 9 is formed in the cylinder head 2. The valve hole 9 opens at a portion of the intake passage 5 facing the opening 5a. A cylindrical stem guide 10 is fitted into the valve hole 9.
The valve guide 7 is inserted through the stem guide 10 so as to be able to advance and retreat.

One end of the stem guide 10 has a valve hole 9.
, And a substantially ring-shaped spring seat 11 is attached to the protruding portion. An annular recess 7c is formed near the top 7b of the valve stem 7. A retainer 13 is attached to the annular concave portion 7c via a cotter 12. A spring 14 is interposed between the spring seat 11 and the retainer 13, and the direction in which the intake valve 8 is closed (the umbrella portion 7a is
In the direction of seating). A substantially bottomed tubular stem seal 15 made of an elastic material is provided at one end of the stem guide 10.
Is fitted, and the valve stem 7 is inserted through a hole formed in the bottom portion 15a to seal between the valve stem 7 and the stem guide 10.

[0005] At the top 7b of the valve stem 7, a proximal end 1 is provided.
The distal end 17b of the rocker arm 17 having a substantially “く” shape, which is held by the rocker shaft 16, is brought into contact with 7 a. A camshaft 18 is provided in parallel with the rocker shaft 16. This camshaft 18
Is provided with a cam 19, which presses the valve stem 7 via the rocker arm 17 against the spring 14 according to the rotational position to open the intake valve 8 as shown in FIG. Has become.

In this valve operating mechanism of the internal combustion engine, when the valve is opened, the contact portion between the top 7b of the valve stem 7 and the stem contact surface of the tip end 17b of the rocker arm 17 moves as the rocker arm 17 rotates. While the valve stem 7 is pressed and guided by the stem guide 10,
Move linearly in the direction of the center line of. When the valve is closed,
The valve stem 7 receives the spring force of the spring 14 and is guided by the stem guide 10 in the same manner as when the valve is opened, and moves linearly in the direction of the center line of the stem guide 10.

[0007]

However, in the above-described valve train of an internal combustion engine, it is desired to improve combustion. Conventionally, as a countermeasure, for example, a shroud (not shown) is provided in the intake passage 5 above the umbrella portion 7a or the like to generate an intake vortex, and an intake mixture (hereinafter, referred to as intake) S is provided.
So that a desired tumble ratio (swirl ratio) is ensured so as to guide the fuel into the combustion chamber 4 well. However, when the shroud is provided depending on the operation state of the engine, the flow of the intake air is suppressed by the provision of the shroud, and the ease with which the intake air flows into the combustion chamber 4 (flow coefficient) deteriorates.
As a result, the characteristics (engine performance) of the internal combustion engine may be reduced.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a valve train for an internal combustion engine capable of improving engine performance.

[0009]

According to the first aspect of the present invention,
In a valve operating mechanism of an internal combustion engine for opening and closing a valve by a pressing force of a rocker arm acting on a valve stem supported to be able to advance and retreat on a stem guide and a spring force acting in a longitudinal direction of the valve stem, the rocker arm or the valve A substantially spherical or substantially cylindrical concave portion is formed on one of the stems, and a convex portion having a shape along the concave portion is provided on the other of the rocker arm or the valve stem, and the stem guide is moved in the reciprocating direction of the valve stem. Characterized by being supported so as to be swingable in a direction substantially perpendicular to the direction. According to a second aspect of the present invention, in the configuration of the first aspect, the concave portion has a substantially spherical shape, and the direction substantially perpendicular to the direction is a direction having a torsional relationship with a cam shaft that operates the rocker arm. Features.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A valve train of an internal combustion engine according to an embodiment of the present invention will be described below with reference to FIGS.
The same members and portions as those shown in FIGS. 3 and 4 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

In FIG. 1 and FIG.
Is formed with a hole (hereinafter, referred to as a valve hole) 9A whose one end opens into the intake passage 5 so as to face the opening 5a of the intake passage 5. On the other end side of the valve hole 9A, a substantially cylindrical (may be semi-cylindrical) groove (hereinafter, referred to as a groove).
It is called a cylindrical groove. ) 20 are formed. This cylindrical groove 2
A substantially cylindrical rotary guide 21 is rotatably housed in the housing. A hole (hereinafter, referred to as a guide hole) 21 a extending in the radial direction is formed in the rotation guide 21. The stem guide 10 is fitted into the guide hole 21a, and the valve guide 7 inserted into the stem guide 10 and the valve stem 7 inserted into the stem guide 10 are inserted into the center 21 of the rotation guide 21.
It can rotate about b. One end of the stem guide 10 protrudes from the guide hole 21a, and a spring seat 11 is attached to the protruding portion. In this case, the spring seat 11 is arranged in contact with the rotation guide 21. The lubrication of the stem guide 10 is performed by lubricating oil stored in the cam chamber.

A stem seal 22 made of an elastic material is fitted in the valve hole 9A. The stem seal 22 is an intake valve (valve) together with the valve stem 7 and the head 7a.
8. The stem seal 22 is provided in the valve hole 9.
A ring-shaped stem seal body 22 joined to the wall of A
a bellows portion 22b whose base end is connected to the inner peripheral side portion of the stem seal body 22a; and a ring-shaped main seal portion 22c provided on the distal end side of the bellows portion 22b and slid by the stem seal 22. When used for the intake valve, the lubricating oil on the cam chamber side is prevented from being drawn by the negative pressure of the intake passage 5 and leaking into the intake passage 5 and used for the exhaust valve. If the exhaust in the exhaust passage
The high pressure prevents leakage to the cam chamber side.

A hemispherical concave portion 23 is formed in the stem contacting surface portion of the tip side 7b of the rocker arm 17. On the top 7b of the valve stem 7, there is formed a substantially spherical convex portion 24 which slides freely on the concave surface portion 23. The rocker arm 17 is rotated by the rotation of the cam 19.
When the valve stem 7 rotates around the rocker shaft 16 and presses the valve stem 7, a counterclockwise force acts on the convex portion 24 with respect to the center 21b of the rotary guide 21.

In this valve operating mechanism of the internal combustion engine, as shown in FIG. 2, when the rocker arm 17 is rotated by being pushed by the cam 19 when the valve is opened, the tip side 17b of the rocker arm 17 is rotated.
Presses the top portion 7b of the valve stem 7 to separate the umbrella portion 7a from the valve seat 6 and open the valve.
2 moves leftward in FIG. 2 by a distance m corresponding to an angle θ described later, so that the stem guide 10 and the rotation guide 21 move the center 21 b of the rotation guide 21 while the projection 24 slides on the concave surface 23. Rotating counterclockwise by an angle θ as the center, the umbrella portion 7a of the valve stem 7 shifts to the right side in FIG. 2 with respect to the center of the valve seat 6 (the valve scissor angle changes). For this reason, the opening area of the biased front portion R ₁ (right side in FIG. 2) and the biased rear portion R ₂ of the valve stem 7 in the opening 5 a of the intake passage 5 are different from each other, and the combustion through each of the portions R ₁ and R _2. Since the amount of the intake air S flowing into the chamber 4 is different, the swirl of the intake air is easily generated, and the combustion can be improved. Further, since the combustion can be improved without providing the shroud required for improving the combustion in the related art, the suppression of the flow of the intake air-fuel mixture by the shroud is avoided, and the flow coefficient and, consequently, the engine performance can be improved. . As described above, when the valve stem 7 rotates, the stem seal 22 made of an elastic material provided in the valve hole 9A receives the rotational power of the valve stem 7 and bends to follow the valve stem 7.

In the above-described embodiment, the case where the rotary guide 21 is substantially cylindrical and the cylindrical groove 20 is provided so as to slide and guide the rotary guide 21 has been described as an example. Is formed into a spherical shape, and a substantially spherical shape (a hemispherical shape may be used) for slidingly guiding the spherical rotary guide.
May be formed. When the rotation guide is formed in such a spherical shape, the intake and exhaust valves are arranged radially with respect to the combustion chamber 4 (the inclination of the valve stem 7 is not only in the shear plane of the camshaft 18 but also in the normal direction of the plane). Also has a component.) It is possible to cope with the rotation that occurs in the plane direction including the normal line that occurs in the case. Further, in the case of the spherical shape, a structure in which the housing is formed in a half-split shape and a separate housing is fastened with bolts or the like from a problem in processing can be considered. At this time, a seal can be provided on the upper side of the stem guide 10.

In the above-described embodiment, the case where the hemispherical concave portion 23 is formed on the rocker arm 17 and the substantially spherical convex portion 24 is formed on the top 7b of the valve stem 7 has been described as an example. Alternatively, a semicircular concave portion may be formed on the rocker arm 17 and a cylindrical body may be provided on the top 7b of the valve stem 7 so as to be slidably guided by the semicircular concave portion.

In the above-described embodiment, the case where the rocker arm 17 has the hemispherical concave surface 23 and the top 7b of the valve stem 7 has the substantially spherical convex 24 has been described as an example. Instead, a hemispherical concave portion (or a semicircular concave portion) is formed on the top portion 7b of the valve stem 7, and a substantially spherical convex portion (or a cylindrical body) is formed on the rocker arm 17.
May be formed.

In the above embodiment, the case where the valve is an intake valve has been described as an example. However, an exhaust valve provided in the internal combustion engine together with the intake valve may have the same structure as the above-described mechanism. With this configuration, a common valve operating mechanism can be used for the intake valve and the exhaust valve,
Productivity can be improved as a whole device.

In the above-described embodiment, the umbrella portion 7a of the valve stem 7 is biased to the outside of the cylinder (right side in FIG. 2). On the contrary, the head portion 7a is biased to the center side of the cylinder (left side in FIG. 2). This can be achieved by adjusting the position of the camshaft 8, the position of the rocker shaft 16 (these are the centers of the shafts), and the contact position between the rocker arm 17 and the valve stem 7. The stem guide 10 is not necessarily limited to a columnar shape, and may be a rotating body, for example, a sword shape or a drum shape. The material of the stem guide 10 having the same thermal expansion as that of the cylinder head (groove) is the best because the change in clearance is reduced.

[0020]

According to the first and second aspects of the present invention, when the rocker arm pivots against the spring and presses the valve stem, the concave portion and the convex portion slide relative to each other while the valve stem slides on the valve stem. The rotating force acts, and the stem guide and, consequently, the valve stem rotate in a direction substantially perpendicular to the direction in which the valve stem advances and retreats. The valve can be opened with the body deviated from the center of the seat.
For this reason, when the valve is an intake valve, when the intake air-fuel mixture flows into the combustion chamber, an intake vortex easily occurs,
Combustion can be improved. Furthermore, since the combustion can be improved without providing the shroud required for improving the combustion in the prior art, the suppression of the flow of the intake air-fuel mixture by the shroud is avoided, and the flow coefficient is improved accordingly, and the engine performance is improved accordingly. Can be improved.

According to the second aspect of the present invention, since the concave portion is substantially spherical, the swing direction of the valve stem with respect to the rocker arm can be set in a wider range than when the concave portion is substantially cylindrical. The restrictions on the assembly of the valve stem are reduced. Furthermore, since the stem guide is swingably supported in a direction that is in a torsional relationship with the camshaft, which is a direction that is substantially perpendicular to the direction in which the valve stem moves, a direction in which the substantially perpendicular direction is not in a torsional relationship with the camshaft. As compared with the case, the stem guide and, consequently, the valve stem can be easily swung along the rotation direction of the camshaft.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a valve mechanism of an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an operation of the valve train of FIG. 1;

FIG. 3 is a cross-sectional view schematically showing one example of a conventional valve train of an internal combustion engine.

FIG. 4 is a sectional view showing the operation of the valve train of FIG. 3;

[Explanation of symbols]

 7 Valve stem 10 Stem guide 14 Spring 17 Rocker arm 21 Rotation guide

Claims (2)

[Claims] 1. A valve train mechanism for an internal combustion engine, which opens and closes a valve by a pressing force of a rocker arm acting on a valve stem supported movably on a stem guide and a spring force acting in a longitudinal direction of the valve stem. A substantially spherical or substantially cylindrical concave portion is formed on one of the rocker arm or the valve stem, and a convex portion having a shape along the concave portion is provided on the other of the rocker arm or the valve stem, and the stem guide is provided with the stem guide. A valve train mechanism for an internal combustion engine, which is supported so as to be swingable in a direction substantially perpendicular to the direction in which the valve stem moves forward and backward. 2. The internal combustion engine according to claim 1, wherein said concave portion is substantially spherical, and said substantially orthogonal direction is a direction having a torsional relationship with a camshaft that operates said rocker arm. Valve train.