JPS60153451A - Piston for internal-combustion engine - Google Patents

Abstract

PURPOSE:To keep up temperature in a groove part as high as possible and prevent moisture from getting dewed as well as to keep off any corrosive wear on sulfuric aicd, by sticking a porous molded body close to an inner side of a cylindrical surface having a piston-ring groove of a piston which installs a cavity part leading a cooling fluid therein. CONSTITUTION:Cooling oil is fed to a head part of a piston 1 and each of cavity parts 1a and 1b for cooling a cylindrical surface having a piston-ring groove 2a. A porous molded body 6 is closely set up in an inner side of the cavity part 1a. With this constitution, the back of the ring groove 2a is prevented from being directly cooled by the cooling oil without increasing piston weight so much and, what is more, formation of sulfuric acid due to dew condensation inside the groove is kept back, thus corrosive wear is prevented from occurring.

Description

[Detailed description of the invention] The present invention relates to a piston for an internal combustion engine.

In marine diesel engines, low-quality fuel is often used to reduce fuel costs, and due to the effects of fuel residue or corrosive products such as sulfuric acid produced by combustion, the ring groove run 1' of the piston or the piston ring may be damaged. Cylinder liner wear often progresses rapidly.

As piston ring groove wear progresses, it causes a decrease in output, an increase in the amount of oil dissipation, poor startability, etc., and at the same time shortens the life of the engine.・The ring groove is induction hardened.

However, although quench-hardened ring grooves are effective against abrasion pull wear caused by combustion residue, 4J is not very effective against corrosion wear caused by corrosive products, so ], chrome plating as thick as 2'm has been applied, but it is expensive and not applying chrome plating to the ring groove results in a significant increase in cost (2).

Therefore, in order to reduce wear on the piston head and ring grooves and prevent seizure of the piston rings, large diesel pistons have a large piston head so that the piston head can be sufficiently cooled with cooling oil. Because the cavity is provided, the temperature of the ring groove is 150℃ or more even during full load exercise.
In many cases, the temperature is around 160°C.

If the sulfur content in the fuel used is low, there will be no problem at this temperature, but if low-quality fuel with a high sulfur content is used, the sulfite residue and hydrocarbons produced by the combustion of the sulfur content will be burned. Corrosive wear increases as the resulting moisture reacts to produce sulfuric acid. Corrosion of the ring groove is mainly caused by this sulfuric acid, but if the temperature of the ring groove is raised sufficiently6, moisture in the combustion gas will not condense, and therefore sulfuric acid will not be generated, and corrosive wear will be significantly reduced. It is something.

The present invention has focused on this point and has been made to solve the above problems, and the object of the present invention (3) is to maintain a high quality of the ring groove so that sulfuric acid is not generated. The purpose of this structure is to prevent corrosive wear and to make the temperature distribution in the circumferential direction of the ring groove uniform.

The gist of this is that a porous molded body is placed in close contact with the inside of the cylindrical surface having the piston ring groove, and the inside of the cylindrical surface having the piston ring groove is not directly cooled by cooling/lb. To prevent sulfuric acid from being generated within the ring groove, and furthermore, adjust the thickness of the porous molded body or arrange it partially so that the temperature of the screw ring becomes uniform. It is in.

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

FIG. 1 is a sectional view showing one embodiment of the internal combustion engine screwdriver according to the present invention, and FIG. 2 is a sectional view showing another embodiment.

In Fig. 1, 1 is a piston, la and lb are hollow parts, 2 is a crown, 2a is a ring groove, 3 is a skirt, and 4 is a hollow part.
4 is a bolt, 5.5 is a lid, and 6 is a porous body.

(4) The piston 1 is an assembled piston in which a steel crown 2 and an eight-forged skirt 3 are separately processed and assembled by tightening with a port 4.4.

A cavity 1a formed between the crown 2 and the skirt 3
and 1b are communicated by oil passages (not shown) provided radially, and the stove 1 is connected to the hollow portions 1a and 1b.
: Cooling oil is supplied through oil cooling holes provided in the piston pin and pin boss (not shown), and as the piston 1 moves up and down, the cooling oil is stirred within the cavities 1a and lb, creating a so-called cocktail shaker. This effect effectively cools the piston 1.

The porous body 6 has a crown 2 ring/M2a in the air conditioning part la.
, 2a are provided on the inner wall surface on the back side of the portion where the portions 2a are provided.

In this example, foamed nickel (porosity 98
%), and after plowing this onto the crown 2, the scars 1-3 are assembled.

Instead of providing this porous body 6, the crown 2 should be made of the same steel (5) thick material (if formed, it would prevent overcooling of the ring groove, but This is not practical because the weight of the entire piston increases significantly.

Foamed nickel is extremely lightweight and has a higher heat insulating effect than the copper phase, so according to the present invention, the purpose can be achieved without increasing the weight of the piston, and the porous body may have a uniform thickness. However, if this is provided, it is recommended that the ring groove be made thinner in areas where the temperature is relatively high and thicker in areas where the temperature is lower, so that the temperature of the ring groove is uniform.

By arranging the porous body 6 on the back surface of the rings a2a, 2a, the ring groove 2 can be formed without increasing the weight of the piston.
It is possible to prevent the back side of a and 2a from being directly cooled by the cooling oil, thereby keeping the temperature of the ring groove high, preventing the formation of sulfuric acid within the ring groove, and preventing corrosive wear. The temperature distribution in the circumferential direction of the ring groove can be made uniform.

Next, referring to FIG. 2, an internal combustion engine (6) according to the present invention Another embodiment of the piston will be described.

This is bore i￥φ200, average effective pressure 18kgf/c
This is an example in which the piston according to the present invention is used in a nt engine.

In conventional pistons without porous material, the temperature distribution in the top ring groove was uneven between 150°C and 190°C, resulting in uneven deformation of the land and poor contact with the cylinder liner. In addition, the carbon adhesion to the top runt is uneven, the ring tends to stick, and the ring groove is prone to corrosive wear due to the presence of low-temperature areas.

The piston 7 is an integral piston made of FCD (spheroidal graphite cast iron).

Therefore, when casting the piston 7, a part of the collapsible core for forming the cavity 7a is made of foamed nickel (80% porosity).
This porous body 8 is welded to the inner wall surface on the back side of the ring grooves 7b, 7b in the cavity 7a using cast walnut. At this time, the porous body 8 is not uniformly attached to the entire circumference of the core,
The circumference of the piston 7 ＼ (7) The wall thickness is increased in the area where the salinity during operation is low during operation.

When an engine using a piston formed in this manner was operated and the piston temperature was measured, the ring groove temperature could be raised uniformly to 190°C to 200°C, and the above-mentioned problem could be solved. Ta.

Since the present invention is constructed as described above, in accordance with the present invention, moisture condensation is prevented by keeping the temperature of the ring groove high, and therefore sulfuric acid is not generated within the ring groove, causing corrosive wear. In addition, the temperature distribution in the circumferential direction of the ring groove can be made uniform.

It should be noted that the present invention is not limited to the above embodiments,
In the example, foamed nickel was used as the porous molded body, but if it is a metal that can be made into solder or casting, it can be used with other porous metals such as other foamed metals or sintered metals. Alternatively, the material may be a porous ceramic material, a nonwoven fabric made of inorganic fibers, or other molded material instead of metal.

(8) When using a ceramic porous body, it is also possible to use it after plasma spraying, by welding it by means such as brazing, or by fixing it with an appropriate fastener, and the present invention incorporates all of these methods. It is inclusive.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of a piston for an internal combustion engine according to the present invention, and FIG. 2 is a sectional view showing another embodiment. ■, 7------------ Piston 1a, 1b, 7 a---=----Cavity part 2---- −−−−−−−−−−−−−−−−−
Crown 2a, 2a, 7b, 7b------Ring groove 3--------------------11---Skirt 6.8-- −−−−−−−−−−〜−〜
〜〜−・−〜−〜−− Porous body patent applicant Representative of Izumi Jidosha Kogyo Co., Ltd. (7524) Shotabe Mogami (9) Figure 2 7 Procedures? 11. Official document (method) % formula % Patent Office Officer Kazuo Wakasugi1, Indication of the case Patent Application No. 008501 of 19822, Name of the invention Piston for internal combustion engine 3, Person making the amendment Relationship to the case Patent Applicant Address: 620 Oaza, Yokoshi City, Saitama Name: Izumi Jidosha Kogyo Co., Ltd. 4, Agent ◎107 Address: 5113-0306
1-8-1-6 Akasaka, Minato-ku, Tokyo, engraving of the specification subject to amendment (no change in content) 7. Contents of amendment as shown in the attached sheet

Claims (6)

[Claims] (1) In order to cool the cylindrical surface with the piston head and piston ring groove, a cavity is provided where the cooling liquid is introduced.
The piston for an internal combustion engine as described above, wherein at least a portion of the inner cylindrical surface 1u11 having the piston ring groove is closely fitted with a porous molded body. (2) A piston for an internal combustion engine according to claim 1, wherein the porous molded body is a foamed metal. (3) The piston for an internal combustion engine according to claim 1, wherein the porous molded body is a porous ceramic body. (4) The piston for an internal combustion engine according to claim 1, wherein the porous molded body is an inorganic fiber. (5) Claim 1 in which the thickness of the porous molded body is uniform
A piston for an internal combustion engine according to items 4 to 4. (6) A pifton for an internal combustion engine according to claims 1(1) to 4, wherein the thickness of the porous molded body is changed so that the temperature distribution in the ring groove is constant.