JP2001164990A - Piston for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piston for internal combustion engine in which a stopper pin can easily be inserted into a pin hole formed in the piston and will not easily slip out from the pin hole. SOLUTION: A pin hole 18 is formed confronting a piston ring groove 8 provided in a piston 1. A stopper pin 17 for stopping the turn of a piston ring fitted in the groove 8 is inserted in the pin hole 18. In the condition that the stopper pin 17 is inserted in the pin hole 18, the stopper pin 17 is welded fast to the piston 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a piston for an internal combustion engine.

[0002]

2. Description of the Related Art As a piston for an internal combustion engine of this type, for example, Japanese Patent Laid-Open Publication No. Sho 50-215942 discloses a piston ring groove formed in a piston. 1 shows a piston for an internal combustion engine provided with a stopper pin.

The piston is formed from an aluminum alloy material, the stopper pin is formed from a stainless steel material, and the stopper pin is fixed to the piston by being pressed into a pin hole formed in the piston.

[0004]

In the conventional example, since the stopper pin is press-fitted into the pin hole, the press-fitting operation is performed when the interference of press-fitting is large or when the size of the stopper pin is small. In this case, there is a possibility that the stopper pin may be broken, and there is a possibility that press fitting becomes difficult.

Further, since the stopper pin and the piston are formed of different materials, when the internal combustion engine is thermally expanded during operation, the interference between the stopper pin and the pin hole is changed due to a difference in linear expansion coefficient of the material. Changes,
The stopper pin may come off. In particular, when a cooling cavity in which cooling oil is introduced is formed inside the piston, the press-fit length cannot be sufficiently secured due to the cooling cavity, and there is a concern that the stopper pin may come off. .

The present invention has been devised in view of the above-mentioned conventional circumstances, and is used for an internal combustion engine in which a stopper pin is easily inserted into a pin hole formed in a piston and does not easily come out of the pin hole. It is intended to provide a piston.

[0007]

SUMMARY OF THE INVENTION In view of the above, the invention according to claim 1 includes a stopper pin which faces a piston ring groove formed in a piston and serves as a detent for a piston ring mounted in the piston ring groove. In the piston for an internal combustion engine, a pin hole is formed facing the piston ring groove, a stopper pin is inserted into the pin hole, and the stopper pin and the piston are fixed by welding.

According to a second aspect of the present invention, in the configuration of the first aspect, the stopper pin is inserted with a predetermined gap into a pin hole.

According to a third aspect of the present invention, in the configuration of the first aspect of the invention, the stopper pin and the pin hole are formed in a circular cross section.

According to a fourth aspect of the present invention, in the configuration of the first aspect, welding of the piston and the stopper pin uses a heat source having a high energy density.

In this configuration, a pin hole is formed facing the piston ring groove of the piston, and a stopper pin is inserted into the pin hole. At this time, the stopper pin does not need to be press-fitted into the pin hole with a large interference.
Alternatively, it can be inserted without a gap. In particular, in the invention according to claim 2, the stopper pin is inserted with a predetermined gap into the pin hole.

The stopper pin and the piston are fixed by welding with the stopper pin inserted in the pin hole. According to the fourth aspect of the invention, the stopper pin and the piston are welded by using a heat source having a high energy density such as an electron beam, a laser beam, plasma, or a TIG arc.

Thus, the stopper pin is easily inserted into the pin hole. Further, since the stopper pin and the piston are fixed by welding, the interference between the stopper pin and the pin hole may change, or the insertion (press-fitting) length may not be sufficiently secured due to the cooling cavity. Also, the stopper pin does not come out of the pin hole.

Therefore, a piston for an internal combustion engine is obtained in which the stopper pin is easily inserted into the pin hole formed in the piston and does not easily come out of the pin hole.

In the invention according to claim 2, the stopper pin is inserted with a predetermined gap into the pin hole, so that the stopper pin is easily inserted into the pin hole.

According to the third aspect of the present invention, since the cross-sectional shape of the stopper pin and the pin hole is formed in a circular shape, the stopper pin and the pin hole can be easily processed.

Further, in the invention according to claim 4, since the welding of the piston and the stopper pin uses a heat source having a high energy density, the piston and the stopper pin are locally re-melted, and both are welded. Is done.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of an internal combustion engine piston according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of a portion A in FIG. 1, and FIG. FIG. 4 is a cross-sectional view showing an inserted state, which is substantially the same as FIG. 1, and FIG.

In the drawing, the piston indicated by reference numeral 1 is formed from an aluminum alloy material, for example, JIS AC8A material. The piston 1 has a top crown 2 in FIG. 1 and a ring land 3 following the top 2.
And a skirt portion 4 following the ring land portion 3.

A hollow combustion chamber 7 is formed in the crown 2 of the piston 1. The opening edge of the combustion chamber 7 is formed in an annular shape.

In this embodiment, two ring rings 8 and 9 are formed in the ring land 3, and the piston ring grooves 8 and 9, which are located near the crown surface 2 side, are formed. The ring groove 8 is a compression ring groove, and the piston ring groove 9 located near the skirt portion 4 is an oil ring groove.

The ring land 3 has a cooling cavity 10 formed in an annular shape in a thick portion thereof.

A pin boss portion 11 is formed on the inner peripheral side of the skirt portion 4, and the pin boss portion 11
A piston pin hole 12 is formed in the outer periphery of the piston pin.
A hollow piston pin 1 is provided in the piston pin hole 12.
3 is inserted, and the connecting rod 14 is connected to the piston pin 13.

Further, facing the piston ring groove 8,
A stopper pin 17 is provided to prevent rotation of a piston ring (not shown) mounted in the piston ring groove 8. The stopper pin 17 is formed in a cylindrical shape from a stainless steel material, is inserted into a pin hole 18 formed facing the piston ring groove 8, and is fixed by welding.

That is, the pin hole 18 is cylindrical, is formed radially with respect to the axis of the piston 1, crosses the cooling cavity 10 in the radial direction, and has a tapered tip. The ring-shaped portion 3 has a thick hole and a closed blind hole. On the other hand, the tip end of the stopper pin 17 is formed in a tapered shape substantially matching the tip shape of the pin hole 18 and inserted into the pin hole 18, and the rear end side is located in the piston ring groove 8.

At this time, the stopper pin 17 is press-fitted into the pin hole 18 with a slight interference, or is fitted without a gap. Alternatively, they are inserted with a predetermined gap.

With the stopper pin 17 inserted into the pin hole 18, the stopper pin 17 and the piston 1 are fixed by welding. A high energy density heat source such as an electron beam, a laser beam, plasma, or a TIG arc is used for welding the stopper pin 17 and the piston 1. In this embodiment, the electron beam or the like is applied to the crown 2 of the piston 1. Irradiation is performed from the side, and the distal end side of the stopper pin 17 and the thick portion of the piston 1 are welded by locally re-melting. 1 and FIG.
The hatched portions indicated by indicate remelted portions.

In such a configuration, the stopper pin 17 is press-fitted into the pin hole 18 with a slight interference, or is fitted without any gap. Alternatively, they are inserted with a predetermined gap. The stopper pin 17 and the piston 1 are fixed by welding with the stopper pin 17 inserted into the pin hole 18.

Thus, the stopper pin 17 is easily inserted into the pin hole 18. In particular, when the stopper pin 17 is inserted into the pin hole 18 with a predetermined gap, the insertion becomes easier as compared with other methods. Further, since the stopper pin 17 and the piston 1 are fixed by welding, the interference between the stopper pin 17 and the pin hole 18 changes, and the insertion (press-fit) length for the cooling cavity 10 is sufficient. The stopper pin 17 does not come out of the pin hole 18 even if it cannot be secured.

Accordingly, a piston for an internal combustion engine is obtained in which the stopper pin 17 is easily inserted into the pin hole 18 formed in the piston 1 and does not easily come out of the pin hole 18.

The stopper pin 17 and the pin hole 1
Since the cross-sectional shape of 8 is formed in a circular shape, the stopper pin 17 and the pin hole 18 can be easily processed.

The piston 1 and the stopper pin 17
Since welding with a high energy density heat source is used,
The piston 1 and the stopper pin 17 are locally re-melted and both are welded.

Although the embodiment has been described with reference to the drawings, the specific configuration is not limited to this embodiment and can be changed without departing from the spirit of the invention.
For example, although the embodiment having two piston ring grooves 8 and 9 has been described, the present invention can be applied to a piston having one or three or more piston ring grooves.

[0035]

As described above in detail, according to the present invention, a stopper pin is easily inserted into a pin hole formed in a piston and is not easily pulled out of the pin hole. A piston is obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a piston for an internal combustion engine showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a portion A in FIG. 1;

FIG. 3 is a view substantially similar to FIG. 1 showing a state in which a stopper pin of FIG. 1 is inserted into a pin hole.

FIG. 4 is an enlarged sectional view showing a portion A in FIG. 3;

[Explanation of symbols]

 1 Piston 8 Piston ring groove 17 Stopper pin 18 Pin hole

Claims (4)

[Claims] 1. A piston for an internal combustion engine having a stopper pin which faces a piston ring groove formed in a piston and prevents rotation of a piston ring mounted in the piston ring groove, wherein the pin faces the piston ring groove. A piston for an internal combustion engine, wherein a hole is formed, a stopper pin is inserted into the pin hole, and the stopper pin and the piston are fixed by welding. 2. The piston for an internal combustion engine according to claim 1, wherein said stopper pin is inserted with a predetermined gap in a pin hole. 3. The piston for an internal combustion engine according to claim 1, wherein a cross-sectional shape of the stopper pin and the pin hole is formed in a circular shape. 4. The piston for an internal combustion engine according to claim 1, wherein a high energy density heat source is used for welding the piston and the stopper pin.