JPS5827161Y2 - combination piston - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a combination piston in which a crown portion and a skirt portion are integrally molded, and a piston pin boss portion is fixed to the resulting outer shell.

Conventional piston pin bosses in which the skirt portion and piston pin boss portion are integrally molded have a complicated internal structure, resulting in poor castability and difficulty in thin-walled molding.

Furthermore, since the structure is complex, complex thermal analysis and design expertise are required to suppress local thermal deformation.

Furthermore, depending on the operating conditions, uneven thermal deformation is unavoidable, and problems such as piston slump and poor lubrication are likely to occur.

It is an object of the present invention to avoid the above-mentioned problems and to easily form a cooling chamber with a large cooling effect.

Further, weight reduction and improvement in pressure resistance are also one of the objectives of the present invention.

The present invention will be explained below based on the drawings.

Reference numeral 1 in FIG. 1 denotes a piston outer shell, which is composed of a crown part 2 and a skirt part 3 that are integrally cast, and is generally a single-layered structure in the shape of a bottom opening.

Reference numeral 4 denotes an annular lip projecting downward from the lower surface of the crown portion 2, and its lower end surface 5 serves as a joint surface with the piston pin boss portion 6.

The piston pin boss portion 6 is also a thin-walled comb-like member with a downwardly opening arc-shaped cross-section and is cast separately.
An annular rib 8 integrally protrudes upward from the upper surface and is in pressure contact with the lip 4 at the surface 5.

Reference numeral 9 denotes a cylindrical outer surface of the boss portion 60, which closely fits into the cylindrical inner surface 10 of the skirt portion 30.

11 is a compression ring groove, 12 is an oil ring groove, the ring zone of the skirt portion 3 is slightly thicker, and a horizontal lip 14 integrated with the boss portion 6 is provided on the inner surface 13 of the O-ring 1.
It is about to fit through 5.

16 and 17 are oil holes for introducing cooling oil supplied from below the boss portion 6 into the central cooling chamber 18 and the annular cooling chamber 19;
20 is an annular chamber, 21 is a relief hole that connects the chamber 20 and the oil ring groove 12, and 22 is an oil hole that connects the chamber 20 and a chamber inside the piston.

The central cooling chamber 18 has a large volume, and its bottom surface is formed in a downward-opening arc shape, that is, a so-called mid-height shape.

Further, the oil hole 16 is formed in the center of the earthen wall of the boss portion 6.

In FIG. 2, which shows the cross section taken along the line ■-■ in FIG. 25'
26 is a screw hole, and 26 is a plug nand for reducing unevenness on the top surface of the piston.

To manufacture the illustrated piston, the piston outer shell 1 and the piston pin boss part 6 are cast separately, and after the necessary machining is performed, the boss part 6 is inserted into the outer shell 1 and firmly connected with bolts 24. do.

During operation, cooling oil is supplied from below the boss portion 6 to the skirt portion 3. It collides with the inner surface of the boss part 6 to cool that part, and a part of it is guided by the arc-shaped inner surface of the boss part 60 and enters the chamber 18 through the oil hole 16, cooling the lower surface of the crown part 2, and further The oil enters the chamber 19 through the oil hole 17 and cools the crown portion 2 and ring zone.

The oil scraped off from the inner surface of the cylinder by the oil ring enters the chamber 20 through the relief hole 21, part of it is released into the piston from the oil hole 22, and the remaining part is released into the inner surface of the skirt part 1.
0 and the outer surface 9 of the boss portion, forming an oil film there and flowing down little by little.

As a means for fixing the piston pin boss part 6 to the piston outer shell 1, a snap ring can be installed between the skirt part 3 and the boss part 60, and the boss part 6 can be attached at a position avoiding the upper part of the spin hole 7. A bolt can also be screwed upward into the screw hole of the crown part 2 from the 6 side.

As explained above, the present invention has the crown part 2 and the neck part 1.
It consists of an outer shell 1 integrally having a portion 3, and a piston pin boss part 6 fixed to the inside of this outer shell 1. An upwardly directed annular lip 8 is formed on the lower surface of the crown portion 2, and a downwardly directed annular rib 4 is formed on the lower surface of the crown portion 2. , a central cooling chamber 18 and an annular cooling chamber 19 are formed, each having an arcuate bottom opening downward and having a large volume.

Both cooling chambers 18 and 19 communicate with each other through an oil hole 17 in the lip 8 of the boss, and the central cooling chamber 18 is opened downward through an oil hole 16 in the center of the earthen wall of the boss, and is connected to the inner circumferential surface of the skirt portion 3. An annular chamber 20 communicating with the oil ring groove 12 is formed between the outer circumferential surface of the boss portion 6, and an O-ring 15 is disposed between the annular chamber 20 and the annular cooling chamber 19, so that the inside of both the cooling chambers 18, 19 is The feature is that a certain amount of cooling oil can be stored in the tank, which has the following advantages.

(1) It is possible to simultaneously achieve weight reduction and improved pressure resistance against explosive force.

That is, an outer shell 1 and a boss portion 6 fixed to the inside of this outer shell 1.
is formed separately, and the boss portion 6 is formed into a thin arc-shaped comb shape that opens downward, so the piston can be significantly reduced in weight.
Moreover, the pressure resistance against explosive force inside the combustion chamber is also improved.

(2) The piston outer shell 1 and the piston pin boss part 6 can be molded in advance with thermal deformation in mind, and the two can be joined by fitting or other means, so that 1. local internal stress,
Heat deformation can be suppressed.

(3) The crown part 2 and skirt part 3 are integrally molded,
Since it is generally cylindrical, thermal expansion in the axial direction is uniform and deformation is reduced as much as possible.

(4) While cooling oil is stored in the cooling chambers 18 and 19, other oil is effectively used to significantly reduce piston slump.

That is, since the annular chamber 20 communicating with the oil ring groove 12 is formed between the boss portion 6 and the skirt portion 30, a portion of the oil scraped off from the inner surface of the liner is transferred from the annular chamber 20 to the skirt portion 3 and the boss portion 6. It is transmitted to the fitting part and forms an oil film there.

In other words, while cooling oil is stored in the cooling chambers 18 and 19, an oil film can be formed on the fitting portion between the skirt portion 3 and the boss portion 6 using another oil, and piston slump can be significantly reduced. can.

This reduces liner cavitation and engine mechanical noise.

(5) The piston cooling effect is extremely large.

That is, on the lower surface side of the crown portion 2, which is heated the most.

A central cooling chamber 18 and an annular cooling chamber 19 with large volumes are formed, and a certain amount of cooling oil can be collected in both cooling chambers 18 and 19 by means of an O-ring 15, so that the cooling chamber 18 can be closed by the vertical movement of the piston. , 19, the cooling oil is shaken violently together with the air, and the cooling oil is shaken violently in the crown portion 2.
and ring zone efficiently.

(6) Taking advantage of the fact that the piston outer shell 1 and the boss portion 6 are separate bodies, the cooling chamber 1 with a large cooling effect as described above is created.
8 and 19 can be easily formed.

That is, ribs 8, 4, etc. are formed on the boss portion 6 and the crown portion 2, and an O-ring 15 is provided between the boss portion 6 and the inner surface 13 of the outer shell.
By fitting and fixing the boss portion 6 into the piston outer shell 1, it is possible to easily form cooling chambers 18 and 19 having a large volume capable of storing cooling oil.

(7) The cooling effect on the inner surface of the boss portion 6, the flow of cooling oil into the cooling chamber 18, and the storing and shaking effects of the cooling oil within the cooling chamber 18 can be performed extremely smoothly.

That is, since the boss part 6 is formed into a thin-walled kelp shape with a downwardly opening circular arc cross-sectional shape, the cooling oil supplied from below the boss part 6 comes into contact with the circular arc-shaped inner surface of the boss part 6 almost everywhere, The inner surface of the portion 6 is cooled well, and the oil is smoothly guided to the oil hole 16 in the center of the earthen wall of the boss portion 6, and efficiently flows into the central cooling chamber 18.

In addition, since the bottom surface of the central cooling chamber 18 also has a downward-opening circular arc cross-sectional shape, the central cooling chamber 18
The cooling oil that enters the central cooling chamber 18 reliably accumulates in the central cooling chamber 18, and can exhibit a good shaking cooling effect.

In addition, the above three effects can be achieved simply by forming the boss part 6 into an arcuate shape and by forming the oil hole 16 in the center of the earthen wall of the boss part 6. Therefore, there is no need to provide a special cooling oil guide pipe, etc., the cost is low, and manufacturing and assembly are simple.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view of the silk-combining piston according to the present invention;
The figure is a partial cross-sectional view taken along the line ■-■ in FIG. 1...Piston outer shell, 2...Crown part, 3...Skirt part, 6...Piston pin boss part, 4゜8...・Rib, 12...
...Oil ring groove, 15...O ring, 16
, 17... Oil hole, 18... Central cooling chamber, 19... Annular cooling chamber, 20... Annular chamber, 21... relief groove.

Claims (1)

[Scope of utility model registration request] an outer shell 1 integrally having a crown part 2 and a skirt part 3;
It consists of a piston pin boss part 6 fixed to the inside of the outer shell 1, and the boss part 6 is formed into a thin kelp shape with a downwardly opening arcuate cross section, and an upward annular lip 8 is formed on its upper surface, and the crown part 2 A downward annular rib 4 is formed on the lower surface of the 1
The ribs 8 and 4 form a central cooling chamber 18 and an annular cooling chamber 19 whose bottom surfaces are arcuate and open downward and have a large volume between the lower surface of the crown portion 2 and the upper surface of the boss portion 6 which has an arc-shaped cross section that opens downward.
, and both cooling chambers 18 and 19 are connected to the oil hole 1 of the boss lip 8.
7, the central cooling chamber 18 is opened downward through the oil hole 16 in the center of the upper wall of the boss part, and the skirt part 3
An oil ring groove 12 is provided between the inner circumferential surface of the boss portion 6 and the outer circumferential surface of the boss portion 6.
An annular chamber 20 is formed which communicates with the annular cooling chamber 19, and an O-ring 15 is arranged between the annular chamber 20 and the annular cooling chamber 19.
A combination piston characterized in that a certain amount of cooling oil can be collected within the 8°19.