JP3208511B2 - Engine valves and valve guides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to an engine valve for internal combustion engine.

[0002]

2. Description of the Related Art Generally, an austenitic heat-resistant steel is often used as a material for exhaust engine valves that require heat resistance. Since this austenitic heat-resistant steel cannot be hardened by quenching, usually, as shown in FIG. 5 , a shaft end (1a) having the same shape as the shaft portion (1b) of the engine valve (1) is attached to the shaft portion (1b). ) Is welded with a martensitic chip material (2) having the same diameter as that of (1), and the portion is hardened by quenching to enhance wear resistance.

When an engine valve (1) to which such a tip (2) is welded is inserted into a valve guide (3) incorporated in a cylinder head (not shown), a large bending load is applied to the tip (2). When acting, the chip material (2) may peel off from the welding boundary, or an abnormality may occur at the welding boundary, and the chip material (2) may fall off during operation of the engine.

That is, the shaft portion (1b) of the engine valve (1)
The outer diameter of up shaft end except cotter groove (1c) has a same diameter, also because the form of the same diameter over the entire length is also the inner diameter of the valve guide (3), for example as shown in FIG. 6 When the engine valve (1) is inserted obliquely into the valve guide (3) and squeezed with a strong force to one side, the tip material (2) may peel off.

[0005] As one means for solving this problem,
The shape of the shaft end portion is that as shown in FIG.

That is, the shaft portion (1b) of the engine valve (1)
A slightly smaller diameter of the end of the shaft from slightly below the cotter groove (1c) (because it is upside down in the figure) so that even if it is obliquely inserted into the valve guide (3), as shown in the figure,
The tip material (2) and the valve guide (3) do not interfere with each other.

[0007]

However, in the conventional structure shown in FIG. 7 , since the cotter groove (1c) is also formed with a small diameter, the groove diameter is small, and the cotter groove (1c) has a cotter and a spring. When a repetitive load is applied to the valve spring assembled via the retainer, a high stress acts on that portion, which causes a problem in strength.

[0008] The present invention has been made to solve this problem, and without reducing the strength of the cotter groove,
An engine valve designed to prevent chip material from peeling
Is intended to provide

[0009]

An object of the present invention is to form a cotter groove on an outer peripheral surface of an end portion of a shaft portion having an integral structure , and to apply a hard chip material to a shaft end portion above the cotter groove portion. In the engine valve to be joined , the shaft end from slightly above the cotter groove in the shaft to the upper end of the chip material is defined by the outer diameter of the shaft.
A small diameter part that is slightly smaller than
By locating the joining portion of the chip material , a cotter groove is formed on the outer peripheral surface of the end of the integrated shaft portion, and the hard chip material is joined to the shaft end portion above the cotter groove portion. In the engine valve, the end of the shaft extending from slightly above the cotter groove in the shaft to the upper end of the chip material is connected to the
Taper whose diameter gradually decreases toward the upper end of the material
And a joining portion of the tip material at an intermediate portion of the tapered portion.
Can be achieved by positioning .

[0010]

[Function] When the engine valve is inserted into the valve guide, a slight clearance is formed between the shaft end and the valve guide, even if the shaft is inserted with a slant and the shaft is squeezed with a strong force to the side. Therefore, no bending load acts directly on the chip material. In addition, the small diameter part or the tapered part
Since the cotter groove is formed above the portion, the groove diameter of the cotter groove does not become small, and the strength of the portion does not decrease.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. The same members as those in the conventional example are denoted by the same reference numerals and described.

FIGS. 1 and 2 show an engine valve (1) according to the first aspect of the present invention.
The portion slightly above the cotter groove (1c) has the same diameter as the outer diameter of the shaft portion (1b), and the portion above the shaft end to the shaft end has a small diameter portion (4) slightly smaller than the outer diameter of the shaft portion (1b). ).

The hard tip material (2) is joined to a substantially intermediate portion of the small diameter portion (4) by projection welding or the like.

When the shaft end of the engine valve (1) is configured as described above, as shown in FIG. 2 (shown upside down),
When assembling to the engine, when inserting the shaft (1b) from the end (lower end) of the straight cylindrical valve guide (3), the shaft (1b) is inserted with a slight inclination. Even if the small diameter portion (4) and the tip material are formed, a small clearance (gap) is formed between the small diameter portion (4) and the inner surface of the valve guide (3) even if the small diameter portion (4) is pryed with a strong force to the side. (2) is the valve guide (3)
Do not interfere with. Therefore, since no bending load is applied to the tip material (2), problems such as peeling from the welding boundary (W) and partial loss of the welding boundary (W) are solved.

In addition, since the diameter of the cotter groove (1c) is the same as that of a normal valve, the strength of the portion is not impaired. Next, an engine valve (1) according to a second aspect of the present invention will be described with reference to FIGS.

The second aspect of the present invention is different from the above-mentioned one in that a taper portion which is gradually reduced in diameter toward the shaft end (upper end) is provided in a portion extending from slightly above the cotter groove (1c) to the shaft end. (5) is formed, and the tip material (2) is welded almost to the middle.

In this embodiment, as shown in FIG. 4, even when the shaft portion (1b) is inserted at an angle, as described above, when the shaft portion (1b) is inserted into the valve guide (3), as shown in FIG. The tip material (2) does not interfere with the valve guide (3), and it is possible to prevent the tip material (2) from peeling off from the welding boundary (W).

Further, the strength of the cotter groove (1c) does not decrease. Further, when the tapered portion (5) is formed, not only the insertion into the valve guide (3) becomes easy, but also a resin lip seal attached to the other end of the valve guide (3) for preventing oil from dropping. (Not shown), and is not easily damaged.

[0019]

According to the first aspect of the present invention , even if the shaft portion is inclinedly inserted into the valve guide and squeezed with a strong force to the side, the shaft end portion to which the tip material is joined can be used. Since a slight clearance is formed between the valve guides, no bending load acts on the tip material. Therefore, it does not peel off or the joint boundary is not broken. Also chip
Since the joint of the material is the middle part of the small diameter part,
Even if the end makes strong contact with the inner surface of the valve guide,
No large shear load is applied to the part
Are difficult to peel off. Furthermore, the small diameter part is larger than the cotter groove.
Because it is formed above, the groove diameter becomes smaller
And prevent the strength and rigidity of the cotter groove from decreasing.
It is.

According to the second aspect of the invention, in addition to the effects of the first aspect, the insertion of the valve guide is facilitated, as the shaft end during insertion into the valve guide, the inner surface of the valve guide A large clearance (gap) is formed between the shaft and the shaft. Even if the shaft is inserted with a large inclination and is strongly squeezed to the side, the chip material comes into strong contact with the inner surface of the valve guide and it is peeled off. The risk of doing so is even smaller.

[Brief description of the drawings]

FIG. 1 is a front view of an engine valve according to the first embodiment.

FIG. 2 is an explanatory view showing a state of insertion into a valve guide in an enlarged and inverted manner.

FIG. 3 is a front view of a main part of the engine valve according to the second embodiment.

FIG. 4 is an explanatory view showing a state of insertion into a valve guide in an enlarged and inverted manner.

FIG. 5 is a partially cutaway front view showing a conventional engine valve and a valve guide.

FIG. 6 is an explanatory view showing the state of being inserted into the valve guide in an enlarged and inverted manner.

FIG. 7 is an explanatory diagram showing another conventional example of an engine valve and its insertion state into a valve guide in an enlarged and inverted manner.

[Explanation of symbols]

 (1) Engine valve (1a) Shaft end (1b) Shaft (1c) Cotter groove (2) Tip material (3) Valve guide (4) Small diameter section (5) Tapered section (6) Valve guide (6a) Tapered section (W) Weld boundary

Claims (2)

(57) [Claims] An engine valve comprising a cotter groove formed on an outer peripheral surface of an end portion of a shaft portion having an integral structure , and a hard tip material joined to a shaft end portion above the cotter groove portion. From slightly above the cotter groove to the upper end of the chip material
The leading shaft end is a small diameter part slightly smaller than the outer diameter of the shaft part.
Then, place the joint of the tip material in the middle of this small diameter part.
An engine valve characterized by having 2. An engine valve comprising a cotter groove formed on an outer peripheral surface of an end portion of a shaft portion having an integral structure , and a hard tip material joined to a shaft end portion above the cotter groove portion. From slightly above the cotter groove to the upper end of the chip material
The shaft end reaching the top of the tip material gradually
The tapered portion is to be reduced in diameter next, and the intermediate portion of the tapered portion is
An engine valve in which a joining portion of a tip material is located .