JP2979155B2 - Intake and exhaust valves for internal combustion engines - Google Patents

Description

The present invention relates to, for example, an intake / exhaust valve for an internal combustion engine in which a valve body is formed of titanium or a titanium alloy, and in particular, wear resistance of a shaft end surface of a stem. The present invention relates to an intake and exhaust valve with improved performance.

[Conventional technology]

The biggest obstacle to increasing the allowable engine speed is the increase in the inertial mass due to the weight of the valve train.If the total weight of the valve train components increases, the inertia of the valve train increases the speed. As the rotation increases, the followability of the valve body with respect to the cam decreases, and the valve body generates a dance, which causes a decrease in output.

From such a viewpoint, an attempt has been made to make the valve body lighter by manufacturing the valve body from titanium or a titanium alloy having low specific gravity and excellent heat resistance instead of steel.

[Problems to be solved by the invention]

However, in the intake / exhaust valve whose valve body is made of titanium or a titanium alloy, since the hardness of titanium or the like is as low as about 30 to 40 in Rockwell hardness (HRC), a large repetitive load accompanying the opening and closing of the valve constantly acts. The wear resistance of the stem end face becomes a problem.

In order to solve this problem, an abrasion-resistant material such as stellite is overlaid on the shaft end face of the stem, or a high-hardness steel material is joined to the end of the stem.

However, stellite is not only expensive, but also requires a large facility cost for constructing the stellite and a long construction time, resulting in a large production cost.

Further, when a wear-resistant steel material is joined to the end of the stem by welding or the like, thermal deformation or distortion may occur due to a difference in melting point or the like.

The present invention has been made in view of the above problems, and an object thereof is to provide an inexpensive intake / exhaust valve for an internal combustion engine by increasing the wear resistance of a shaft end surface of a stem by simple means. Is to do.

[Means for solving the problem]

To achieve the above object, the present invention is configured as follows.

(1) An umbrella portion is continuously provided at one end of the stem, and a concave portion is formed at least at a portion of the shaft end surface, which is the other end of the stem, in sliding contact with the valve driving member, and the concave portion has a height higher than the material of the valve body. In an intake / exhaust valve for an internal combustion engine fitted with a wear-resistant body made of a hard material having a high hardness, the wear-resistant body has a center positioned below the shaft end face of the stem and aligned with the shaft end face of the stem above the center. The stem is made of a chipped sphere having a cut surface, and the shaft end of the stem is caulked so that the inner surface of the recessed part of the stem comes into close contact with the outer peripheral surface above the center of the chipped sphere.

(2) An umbrella portion is continuously provided at one end of the stem, and a concave portion is formed in at least a portion of the shaft end surface, which is the other end of the stem, in sliding contact with the valve driving member, and the concave portion has a height higher than the material of the valve body. In an intake / exhaust valve for an internal combustion engine fitted with a wear-resistant body made of a hard material made of a hard material having a hardness, the wear-resistant body has a conical base surface located below the shaft end face of the stem, and a cone-shaped It shall consist essentially of a truncated cone having a cutting surface that is aligned with the axial end surface of the stem above the base surface,
The shaft end of the stem is swaged so that the inner surface of the recess of the stem is in close contact with the outer peripheral surface above the base surface of the truncated cone in the truncated cone.

(3) An umbrella portion is continuously provided at one end of the stem, and a concave portion is formed at least in a portion of the shaft end surface, which is the other end of the stem, in sliding contact with the valve driving member, and the concave portion is higher than the material of the valve body. In an intake / exhaust valve for an internal combustion engine fitted with a wear-resistant body made of a hard material made of a hard material having a hardness, the wear-resistant body has a conical base surface located below the shaft end face of the stem, and a cone-shaped The truncated quadrangular pyramid has a cut surface aligned with the axial end surface of the stem above the basal plane portion, and the concave portion of the stem is formed on the outer peripheral surface of the truncated quadrangular pyramid above the conical base surface portion. The end of the stem shaft is swaged so that the inner surfaces are in close contact.

(Operation)

Since the wear-resistant body made of a hard material is fitted to the shaft end face of the stem, the wear resistance of that portion is enhanced.

Further, since the wear-resistant body is fitted only into the recessed portion of the stem end face, the weight increase of the valve body can be minimized.

Furthermore, since the wear-resistant body is fixed by mechanical means such as caulking without using thermal bonding means such as welding, not only there is no danger of thermal deformation such as thermal strain occurring on the shaft end face of the stem, but also cost is reduced. This is also advantageous.

In addition, as a hard material, a specific shape such as a broken sphere or a truncated cone is used, and these are caulked while maintaining a specific positional relationship with respect to the shaft end surface of the stem, so that when the valve is opened and closed, Even under severe use conditions, the hard material does not fall out of the concave portion of the stem end face.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the intake / exhaust valve according to the first aspect of the present invention, and a valve body (3) comprising an umbrella (1) and a stem (2).
Is formed of titanium or a titanium alloy.

(4) is an annular concave groove provided at the end of the stem (2) for engaging a cotter (not shown).

The central portion of the shaft end face (2a) of the stem (2) has an opening area larger than the area where the rocker arm (5) slides when assembled to the engine, and the center is slightly lower than the end face position. A substantially hemispherical recessed portion (6) is formed. The recess (6) is generally formed at the same time as forging or by subsequent machining.

The recess (6) is made of a hard material having a higher hardness than titanium or a titanium alloy, and is aligned with the shaft end surface (2a) of the stem (2) and located above the center of the sphere at the upper end. Abraded wear-resistant body (7) having a cutting surface
The center is located slightly below the shaft end surface (2a) of the stem (2), and the outer peripheral surface above the center of the chipped wear-resistant body (7) is located on the inner surface of the concave portion (6) of the stem (2). It is fitted so as to be in close contact.

It is preferable to take measures to prevent the chipped spherical wear-resistant body (7) from coming off after the fitting as follows.

That is, as shown in FIG. 2, a steel ball (8) for a bearing having the same diameter as the hemispherical recess (6) formed on the shaft end face (2a) of the stem (2) is properly fitted. After the joining, the shaft end (2a) of the stem (2) is strongly pressed in the axial direction by a press or the like and caulked to prevent the stem (2) from coming off.

Then, only the part protruding above the shaft end face (2a)
Alternatively, if the entire shaft end surface (2a) of the stem (2) is cut off by grinding or the like, an intake / exhaust valve as shown in FIG. 1 is formed.

As in this embodiment, the concave portion (6) has a spherical shape.
When a chipped spherical wear-resistant body (7) made of a hard material is fitted thereto, a load at the time of opening and closing the valve is dispersed, and a concentrated portion of stress is prevented from being generated. The strength and rigidity are increased.

As shown in FIG. 3, the concave portion (6) may be a cylindrical concave portion (9) having a conical bottom surface as it is drilled. By doing so, the workability of the recess (9) is improved.

FIG. 4 shows an embodiment of the intake / exhaust valve according to the second aspect of the present invention.

In this embodiment, a frustro-conical wear-resistant body made of a hard material such as hardened steel is provided in a flat shallow-bottom recess (10) formed at the center of the shaft end surface (2a) of a stem (2). After fitting (11), the shaft end of the stem (2) is caulked by forcibly pressing it in the axial direction, and furthermore, the portion protruding from the shaft end surface (2a) of the stem (2) is cut off to obtain the stem (2). ) Is aligned with the shaft end face (2a).

The invention according to claim 3 may use a quadrangular pyramid-shaped wear-resistant body instead of the truncated conical wear-resistant body (11).

As described above, in each of the above embodiments,
Since the abrasion-resistant bodies (7) and (11), which are made of hard material and have a spherical or frusto-conical shape, are all fixed by mechanical means at room temperature without using thermal bonding means such as welding, cost is reduced. Moreover, there is no possibility that thermal distortion, thermal deformation, or the like will occur at the shaft end of the stem (2).

In addition, a wear-resistant body made of a hard material is fitted to only the portion of the shaft end surface (2a) of the stem (2) that is in sliding contact with the rocker arm (5) to enhance wear resistance. )
The weight increase is very small.

The hard material used in each of the above embodiments may be an alloy steel based on Co, Ni, or Fe, ceramics, or a wear-resistant plastic such as ultrahigh molecular weight polyethylene.

In both of the above embodiments, the stem (2) has been described as a solid material. However, the present invention provides a hollow body on the central axis from the umbrella (1) of the valve body (3) to a proper position of the stem (2). The present invention can be applied to a hollow valve having a hole or a hollow valve in which a cooling medium is sealed in the hollow hole.

The material of the valve body (3) is not limited to the above-mentioned titanium or titanium alloy, but may be an aluminum alloy or other low specific gravity material.

〔The invention's effect〕

According to the present invention, the recess formed on the end face of the stem includes:
Since the wear resistance of the shaft end face of the stem can be increased by a simple means of fitting and crimping a wear-resistant body made of a hard material, an inexpensive intake / exhaust valve can be provided.

Also, since the wear-resistant body is fixed by mechanical means, there is no risk of thermal deformation occurring at the shaft end of the stem, and a hard material having a specific shape is fixed in a specific mode. Even under severe operating conditions at the time of opening and closing, the hard material does not fall off from the recessed portion of the stem end face.

[Brief description of the drawings]

FIG. 1 is a central vertical sectional front view showing a first embodiment of an intake / exhaust valve of the present invention, FIG. 2 is a central vertical sectional enlarged front view of a main part also showing a manufacturing procedure, and FIG. FIG. 4 is a central longitudinal sectional front view of a main part showing a second embodiment of the intake / exhaust valve according to the present invention. (1) Head (2) Stem (2a) Shaft end face (3) Valve (4) Annular groove (5) Rocker arm (valve drive member) (6) Depressed part (7) Spherical wear-resistant body (8) ) Steel ball (9) (10) Concave part (11) Frusto-conical wear-resistant body

Claims (3)

(57) [Claims] An umbrella portion is connected to one end of a stem, and a concave portion is formed at least in a portion of the shaft end surface, which is the other end of the stem, in sliding contact with a valve driving member, and the concave portion is made of a material of a valve body. In an intake / exhaust valve for an internal combustion engine fitted with a wear-resistant body made of a high-hardness material, the wear-resistant body has a center located below the shaft end face of the stem,
And a cut-off sphere having a cut surface aligned with the shaft end face of the stem above the center, and the shaft end of the stem is arranged so that the inner surface of the concave portion of the stem is in close contact with the outer peripheral surface of the cut-off sphere above the center. An intake / exhaust valve for an internal combustion engine, wherein a portion is caulked. 2. An umbrella portion is connected to one end of a stem, and a recess is formed at least in a portion of the shaft end surface, which is the other end of the stem, in sliding contact with a valve driving member. Also, in the intake / exhaust valve for an internal combustion engine fitted with a wear-resistant body made of a hard material having a high hardness, the wear-resistant body is formed such that the conical base surface is located below the shaft end surface of the stem, and the conical base surface. The truncated cone has a truncated cone having a cutting surface aligned with the shaft end face of the stem, and the inner surface of the concave portion of the stem is in close contact with the outer peripheral surface of the truncated cone above the base surface of the cone. An intake / exhaust valve for an internal combustion engine, characterized in that the shaft end of the stem is caulked. 3. An umbrella portion is continuously provided at one end of the stem, and a concave portion is formed at least in a portion of the shaft end surface, which is the other end of the stem, in sliding contact with the valve driving member. Also, in the intake / exhaust valve for an internal combustion engine fitted with a wear-resistant body made of a hard material having a high hardness, the wear-resistant body is formed such that the conical base surface is located below the shaft end surface of the stem, and the conical base surface is The truncated quadrangular pyramid having a cutting surface that is aligned with the axial end surface of the stem at a higher level, and the inner surface of the concave portion of the stem is formed on the outer peripheral surface of the truncated quadrangular pyramid above the base surface of the cone. An intake / exhaust valve for an internal combustion engine, wherein a shaft end of a stem is caulked so as to be in close contact.