JPH0121165Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a piston for an internal combustion engine, and more specifically, to a piston in which a ring groove is formed in the upper part of the top ring of the piston that reciprocates on the inner surface of a cylinder liner. It is something. This is applied to pistons that have a special piston ring fitted in addition to the piston ring fitted to the piston, and reduces the pressure acting on the top ring due to increased combustion pressure, preventing abnormal wear of the piston ring. Used in the field of preventing burn-in.

[Conventional technology]

In recent years, the thermal efficiency of marine diesel engines has been significantly improved, but as a result, the combustion pressure within the cylinder liner tends to increase further. Therefore, among the piston rings, the top ring closest to the combustion chamber of the piston is strongly pressed against the inner surface of the cylinder liner due to high combustion pressure, and as a result,
The piston rings must slide under high surface pressure, making them susceptible to abnormal wear and seizure of the piston rings. In order to solve this problem, measures have been taken such as increasing the hardness of the piston ring and cylinder liner, and increasing the thickness of the oil film between the piston ring and cylinder liner, but in either case there are no problems. This is sufficient and it is hoped that it will be resolved as soon as possible.

[The problem that the idea aims to solve]

As one example, a piston 1 as shown in FIG. 1, which is described in Japanese Patent Laid-Open No. 56-6048, is known. This is a ring groove formed in the upper part of the top ring of the piston that slides back and forth on the inner surface of the cylinder liner. That is, another ring groove 3 is provided on the top of the top ring 2 so that the piston 1
A seamless annular fire ring 4 is engraved on the outer periphery of the piston 1, and a seamless annular fire ring 4 is fitted thereon.

As a result, the combustion pressure acts on the top ring 2 via the fire ring 4, so that abnormal wear and seizure thereof can be reduced. but,
The fire ring may reach an unexpectedly high temperature and expand, causing a tension phenomenon between it and the inner surface of the cylinder liner, which can be dangerous. There is a drawback that the piston to which it is tightly attached must have a special shape.

By the way, in Japanese Patent Application Laid-Open No. 58-88439, there is a so-called "stepped" shape in the abutment part of the piston ring.
The following describes the formation of . However, this is simply a step to reduce gas leakage from the abutment as much as possible.
This shape is already known.

The present invention has been made to solve the above-mentioned drawbacks, and its purpose is to reduce the pressure of combustion gas acting on the top ring and to reduce the propagation of the pressure on the piston corresponding to the above-mentioned fire ring. To provide a piston for an internal combustion engine that can maintain an outer diameter smaller than the inner diameter of the cylinder liner so as to avoid the occurrence of a tension phenomenon on the cylinder liner due to a ring expanding beyond a predetermined size.

[Means to solve the problem]

The piston for an internal combustion engine of the present invention is applied to a piston in which a ring groove is formed in the upper part of a top ring of the piston that reciprocates on the inner surface of a cylinder liner. To explain its features using FIG. 2 as an example, the ring groove 14 has a latch-like fitting abutment 16 (see FIG. 3 a), and each latch 1
The gap 18 (see FIG. 6) formed in the circumferential end surfaces 17b of the cylinder liners 7A and 17B becomes zero during thermal expansion, so that the piston ring 15 that maintains an outer diameter smaller than the inner diameter of the cylinder liner 10 is fitted. That's what I did.

[Effect of idea]

According to the present invention, the piston ring at the upper part of the piston suppresses the propagation of combustion gas pressure to the top ring, making it possible to extend the life of the top ring and to avoid seizure with the cylinder liner. In addition, the latch at the joint of the piston ring is designed to be no larger than the inner diameter of the cylinder liner, which prevents the piston ring from seizing with the cylinder liner or causing abnormal wear. .

〔Example〕

Hereinafter, the present invention will be described in detail based on examples thereof.

FIG. 2 is an external view of the piston 11 reciprocating within the cylinder liner 10, where 12 is a top ring that is normally fitted to the piston 11 as a piston ring, and 13 is a second ring provided below. , one wide ring groove 14 is formed on the outer periphery of the piston 11 at the top of the top ring 12.
is formed.

15a to 15c are piston rings fitted in the ring groove 14, and the shape of the abutment part 16 is a latch-like fit in the circumferential direction, as shown in FIGS. 3a and 3b. , the inner surfaces 17a of the latches 17A and 17B of the abutment portion 16 come into contact with each other due to tension acting in the circumferential direction, and even if the piston ring 15 thermally expands in the circumferential direction and becomes longer, the inner surfaces 17a separate from each other. However, the end surface 17b comes into contact with the other side, and the outer diameter is maintained smaller than the inner diameter of the cylinder liner. That is, each latch 1
The gap 18 formed between the circumferential end surfaces 17b of 7A and 17B becomes zero during thermal expansion.

Note that the abutment portion 16 of the piston ring 15 may be vertically latch-like fitted as shown in FIGS. 4a and 4b. Since the piston ring 15 reaches a considerably high temperature, it is desirable to use heat-resistant steel and chrome plating its outer peripheral surface to improve sliding conditions with the cylinder liner.

According to the piston 11 having such a configuration, the piston ring 15 within the ring groove 14 can be caused to behave as follows, allowing the entire piston 11 to operate smoothly.

In Figure 2, the high-pressure combustion gas in the combustion chamber is
First, it acts on the plurality of piston rings 15 fitted in the ring groove 14. The outer diameter of this piston ring 15 is larger than the outer diameter of the piston 11,
Since it is smaller than the inner diameter of the cylinder liner 10, a labyrinth effect occurs between the outer peripheral surfaces of the plurality of piston rings 15 and the cylinder liner 10, and the pressure of the combustion gas flowing therein is reduced. As a result, the pressure reaching the top ring 12 is weakened and the temperature is also lowered, and the occurrence of abnormal wear and seizure with the cylinder liner 10 in the top ring 12 and furthermore in the second ring 13 is suppressed.

On the other hand, even if the piston ring 15 in the ring groove 14 expands in its circumferential direction under the influence of high temperature and high pressure, the latch 17A of the abutment part 16 that has a gap 18 at the end surface 17b as shown in FIG. ,17B
The mutual inner surfaces 17a of the two are separated from each other as shown in FIG. However, even if the gap 18 approaches zero, its outer diameter is still maintained smaller than the inner diameter of the cylinder liner, and the piston ring 15 is not stretched against the inner surface of the cylinder liner 10.

By the way, the piston ring 15 is fitted into the ring groove 14 by using the latches 17A, 1 of the abutment part 16.
7B can be disengaged from each other, so by widening the abutment part 16, the piston 1 can be easily removed.
1 can be fitted.

In the above embodiments, the number of piston rings fitted into one wide ring groove was described as three, but it goes without saying that the number is not limited to this and any number can be adopted.

As can be seen from the description of the embodiments described above, the present invention suppresses the propagation of combustion gas pressure to the top ring using the piston ring on the upper part of the piston, thereby extending the life of the top ring and preventing seizure with the cylinder liner. etc. can be avoided. In addition, the piston ring is a latch at its abutment, and the gap formed on the circumferential end face of each latch becomes zero during thermal expansion, so that it does not become larger than the inner diameter of the cylinder liner.
This prevents the piston ring from seizing with the cylinder liner or causing abnormal wear. Furthermore, by removing the latch of the piston ring, the piston can be fitted into the ring groove very easily, and the present invention can be realized without special processing on the piston itself.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a piston showing the prior art, Fig. 2 is an embodiment of the present invention, an external view of the piston reciprocating within the cylinder liner, and Fig. 3a is a piston ring adopted in the present invention. Plan view, Figure 3b
is a side view of FIG. 4a, FIG. 4a is a plan view of a piston ring with different abutments adopted in the present invention, FIG. 4b is a side view of FIG. Fig. 6 is a diagram showing the normal state at the abutment part of the piston ring which is thermally expanding in the circumferential direction. 10...Cylinder liner, 11...Piston,
12...Top ring, 14...Ring groove, 1
5, 15a-15c...piston ring, 16...
...Abutment, 17A, 17B...Latch, 17b...
...End face, 18...Gap.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A piston for an internal combustion engine in which a ring groove is formed in the upper part of the top ring of the piston that reciprocates on the inner surface of the cylinder liner, wherein a latch-like fitting abutment part is formed in the ring groove. The internal combustion engine is characterized by having a piston ring fitted therein which maintains an outer diameter smaller than the inner diameter of the cylinder liner by reducing the gap formed at the circumferential end surface of each latch to zero during thermal expansion. Engine piston. (2) The piston for an internal combustion engine according to claim 1, wherein a plurality of the piston rings are fitted into the ring groove.