JP2789391B2 - Hollow valves for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mushroom-shaped hollow valve used as an intake / exhaust valve of an internal combustion engine.

[0002]

2. Description of the Related Art The most hindrance in increasing the allowable rotation speed of an engine is an increase in the inertial mass due to the weight of the valve train, and when the total weight of the components constituting the valve train increases, Due to its inertia, the follow-up performance of the valve body with respect to the cam decreases as the rotation speed increases, and the output of the valve body decreases due to the fluctuation of the valve body.

[0003] Hollow valves are very effective in reducing the weight of the valve body and reducing the inertial mass of the valve train, and are therefore employed in some high-powered engines. Some hollow valves of this type have a hollow hole formed simply on the central axis from the umbrella to the shaft end (for example, the Japanese Utility Model Application No. 56-1473).
Japanese Patent Application Laid-Open No. 62-102806), and those in which a cooling medium such as metallic sodium is sealed in the hollow hole to reduce the heat load.

In general, as shown in FIG. 2, these hollow valves have a terminal having a cotter groove (3) on the other end surface of a shaft (2) having an umbrella (1) connected to one end (lower end). The member (4) is joined by friction welding or resistance welding, etc., and the shaft (2) and the terminal member (4)
The hollow hole (5) formed on the center axis of the above is sealed.

As described above, in the hollow valve joined at the shaft portion, even if a large tensile load is repeatedly applied to the shaft portion (2) at the time of valve operation, the joint portion serves as a starting point to prevent fatigue failure or the like. In addition, it is necessary to increase the bonding strength.

Conventionally, the thickness of the shaft (2) and the end member (4) has been increased.
By increasing the thickness of (t) as a whole, the cross-sectional area of the joint is increased to increase the strength of the joint.

[0007]

As described above, simply increasing the thickness (t) of the shaft (2) and the terminal member (4) inevitably increases the weight of the valve body. This goes against the weight reduction that is the original purpose of the hollow valve. Further, since the volume of the hollow hole (5) also becomes small, the heat exchange property and the cooling property when a cooling medium such as metallic sodium is sealed in the hollow hole (5) are reduced.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to reduce the thickness of a shaft portion as much as possible without reducing the strength of a joint portion with a terminal member. An object of the present invention is to provide a hollow valve for an internal combustion engine which is thin and thus lightweight and highly reliable.

[0009]

An object of the present invention is to provide a shaft member having an umbrella portion connected at one end and having a hollow hole formed therein, and a terminal member concentrically attached to the other end where the hollow hole opens. By joining, in the hollow valve for an internal combustion engine in which the hollow hole is closed, it can be achieved by making the joint portion of the shaft portion with the terminal member thicker than other portions. Preferably, a bottomed hole communicating with the hollow portion on the shaft portion side is formed in the terminal member. (Claim 2).

[0010]

The joint area of the terminal member can be increased simply by increasing the thickness of the joint, so that the joint area can be increased and the joint strength can be increased. Therefore, it is not necessary to increase the thickness of the entire shaft portion, which leads to a lighter valve body. . When the bottomed hole is formed in the terminal member, the weight of the valve body can be further reduced. (Claim 2).

[0011]

An embodiment of the present invention will be described below with reference to the drawings. The same members as those in the above-described conventional example are denoted by the same reference numerals and described. FIG. 1 shows a hollow valve according to the present invention, in which an umbrella (1) is continuously provided at a lower end, and the umbrella (1) side is a wrapper on a central axis extending from the umbrella (1) to a terminal. A shaft portion (2) having a hollow hole (6) having a large diameter formed by machining or the like, and concentrically joined to the upper end surface of the opening by friction welding or resistance welding or the like. And a terminal member (4) having a bottomed hole (7).

A hollow hole (6) formed in the lower end surface of the umbrella (1).
The processing opening (8) is closed by a closing member (9). The upper end of the shaft (2), that is, the terminal member (4)
The thickness (t ₁ ) of the joint portion is formed to be thicker inward than the thickness of the other shaft portion, and that portion is a hollow hole (6) in the lower portion.
It is a small diameter portion (6a) smaller than the inner diameter of.

[0013] Also, the thickness of the bottomed hole (7) portions of the terminal members (4) side, the thickness of the shaft section (2) side (t ₁₎ and are substantially equally formed, bottomed holes (7 ) And the small diameter portion (6a) on the shaft portion side are aligned and communicate with each other.

In order to form the hollow hole (6) on the shaft (2) side, first, a small drill (gun drill) for forming a small diameter portion (6a) at the shaft end is vertically penetrated. A through hole having an inner diameter (d ₁ ) is formed. Then, insert a drill slightly larger in diameter than the above drill from the front side of the umbrella to a point just before the tip reaches the shaft end, and a hollow hole with an inner diameter (d ₂ ) larger than the inner diameter (d ₁ )
Drill (6).

Finally, a boring tool or the like may be inserted from the front side of the umbrella, and the umbrella (1) side may be enlarged in a trumpet shape. In this case, the shaft end is formed as a thick portion having a thickness (t ₁ ).
Also, without drilling a through-hole with an inner diameter (d ₁ ) as described above,
After drilling the small diameter portion (6a) of the required depth of the internal diameter than the shaft end (d _1), is inserted from the inside diameter (d ₂₎ Umbrella front drill for drilling, communicates with the small diameter portion (6a) May be.

As described above, when the thickness (t ₁ ) of only the joining portion is increased, the cross-sectional area of the joining portion is increased, so that the required joining strength can be obtained. Since the thickness of the other parts can be reduced to the minimum thickness having the required mechanical strength, the weight of the valve body can be further reduced.

Moreover, the volume (surface area) of the hollow (6) increases and the thickness of the main part of the shaft (2) decreases, so that a cooling medium (such as sodium metal) is placed in the hollow (6). (Not shown) and the heat transfer efficiency from the shaft portion (2) to the valve guide (G) are increased, and the heat load on the umbrella portion (1) can be reduced.

The present invention is not limited to the above embodiments, but can take various forms. For example, terminal member (4)
May be used as a solid material having no bottomed hole (7) and joined to the open end of the shaft (2).

If the shaft portion (2) including the umbrella portion (1) and the terminal member (4) are formed by plastic working such as swaging or bulging, and at the same time, the thickness of the joint is changed, Only the thickness (t ₁ ) can be easily increased.

In the embodiment, the diameter of the hollow hole (6) on the umbrella portion (1) side is expanded in a trumpet shape. May change.

[0021]

According to the present invention, the joining strength can be increased only by increasing the thickness of the joining portion of the terminal member. Therefore, it is not necessary to increase the thickness of the entire shaft portion more than necessary. Significant weight reduction compared to conventional hollow valves. Further, if a bottomed hole is formed on the end member side, the weight can be further reduced (claim 2).

[Brief description of the drawings]

FIG. 1 is a central longitudinal sectional front view of an embodiment of the present invention.

FIG. 2 is a front view in the center longitudinal section of a conventional hollow valve.

[Description of Signs] (1) Head (2) Shaft (3) Cotter groove (4) Terminal member (6) Hollow hole (6a) Small diameter part (7) Bottomed hole (8) Opening (9) Closed Parts (G) Valve guide (d ₁ ) (d ₂ ) Inner diameter (t ₁ ) Wall thickness

Claims (2)

(57) [Claims] 1. A terminal member is concentrically joined to the other end of a shaft portion having an umbrella portion connected to one end thereof and having a hollow hole formed therein, the terminal hole being open. A hollow valve for an internal combustion engine, wherein a thickness of a joint portion of the shaft portion with a terminal member is made thicker than other portions. 2. The hollow valve for an internal combustion engine according to claim 1, wherein the terminal member has a bottomed hole communicating with the hollow hole on the shaft portion side.