JPS58101250A - Piston for internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the cooling effect by casting a hollow finned aluminium material associated with an oil injection port and exhaust port at the crown section of a piston thus forming a highly accurate oil cooling piston structure. CONSTITUTION:A hollow aluminium member 19 associated with an oil injection port 13 and an oil exhaust port 18 is casted at the crown section 2 of a piston 1, and a plurality of fins are formed at the inside. The oil injection port 13 is conducted through an oil path 14 provided in the piston body and an oil supply hole 17 provided in a piston pin 3 to an oil path space 12 in the piston pin 3. The oil is supplied through an oil path 17 and an oil hole 17a in a connecting rod 15 to the oil path space 12, where the oil entered into a hollow aluminium member 19 will flow out through an exhaust port 18 to the outside of the piston pin 3.

Description

DETAILED DESCRIPTION OF THE INVENTION The WR #'i of the present invention is used for a piston Kll of an internal combustion engine to increase the cooling effect of oil.

It is well known that increasing the compression ratio is effective in improving the fuel efficiency of internal combustion engines, but when increasing the compression ratio, knocking occurs, especially under high load conditions. Currently, the compression ratio is limited.

Knocking occurs when the end gas (end gas) 11K rises and causes spontaneous combustion, but in order to suppress this, it is necessary to lower the combustion chamber wall temperature in the end gas section and lower the end gas temperature. Effective. In this sense, it is desirable to lower the piston top surface device in order to suppress the occurrence of knocking.

Conventional cooling of pistons involves spraying lubricating oil onto the lower surface of the piston from below the piston body, and the heat of the piston is taken away by this oil, and the piston heat is transferred through the piston linker to the cylinder block heat conduction. This is accomplished primarily by escaping.

However, conventional piston cooling has the following various problems. First, the oil that is sprinkled on the piston may fall before it fully contacts the surface of the piston's lower surface, or even if it contacts the piston's lower surface, the oil falls off due to its own weight. There was no cooling.

Furthermore, since the oil is not evenly sprayed over the entire lower surface of the piston, the piston is distorted due to thermal deformation, increasing piston friction, and there is also a risk of adversely affecting piston rings.

Furthermore, with the conventional piston structure, even if the bottom surface of the piston is cooled with oil, a large amount of heat escapes to the cylinder pipes through heat conduction through the piston rings, causing thermal deformation of the piston ring grooves and piston rings. This causes problems such as oil scraping up and a decrease in the durability of the piston rings.

The present invention aims to increase the contact time and contact area between the piston and piston cooling oil in order to solve the problems that existed in conventional piston cooling.

i-9 Another object of the present invention is to achieve piston cooling mainly by oil cooling in order to eliminate the problems caused by cooling piston rings due to heat conduction. It is intended to provide an oil cooling passage inside, but in this case, with the conventional manufacturing method, the thickness of the rounded piston crown part of the floating round piston during casting may become uncertain and become extremely thin. It is also an object of the present invention to provide a piston with a cooling passage formed so as to ensure the required wall thickness of the piston crown.

In order to achieve these objects, in the piston of the internal engine of the present invention, a finned hollow aluminum RIB material is formed in advance using a sand mold or the like, and a scissor hollow aluminum RIB member is fixed to the mold used for manufacturing the piston. In this state, pour the molten metal of aluminum alloy into the piston crown 1iK casting, and use the internal space of the hollow aluminum member as an oil cooling path. By supplying oil to this, increasing the contact time and contact area with the oil, and by keeping the mold immovable during manufacturing, it became possible to leave an inner shape with the exact required thickness on the piston crown. ing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a piston for an internal engine according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a tenth embodiment in which the present invention is applied to a piston having no recess on the top surface of the piston. In the figure, 1 is the piston body, 2 is the so-called crown part at the top of the piston, 3 is the piston pin, 4 is the bottle boss part which is the fitting part of the piston pin 3, and 4a is the piston weight reduction and piston back part. I was bedded. A guide groove for supplying oil or sprayed oil to the fitting portion through the hole 4b to promote lubrication is clearly visible. 5 is the first
Groove for piston ring, 6 is groove for second piston ring, 7
is a groove for an oil ring, and the structure from 1 to 7 is based on the structure of a normal piston.

An annular oil circulation path 8 is formed in the crown II2, and fins 9 are formed on the circular surface. The upper end of this oil circulation path 8 is located above the position of the first piston ring groove 5, and the wall thickness between the outermost peripheral wall surface of the oil circulation path 8 and the first piston ring groove 50 is as follows:
It is suitably small and thin, allowing heat to be transferred to the piston ring side. The piston pin 3 has a partition wall 10J in the center and a plug lla which is a blind cover at one end, forming a space 12 inside the piston pin 3.The space 12 is an annular oil circulation An oil hole 17 is inserted into the oil inlet 13 provided in the path 8.
b.

The oil supply groove 14a1 communicates with each other via the oil passage 14. In addition, the space 12 includes an oil passage 16 formed in the connecting rod 15, and an oil hole 1 in the oil supply groove 16a.
It is connected via 7m. An oil discharge port 18 is provided at a position 180 apart from the oil inlet 13 of the oil circulation path 8, and the oil that has passed through the oil circulation path 8 is discharged downward.

The finned oil circulation path 8 in the piston is manufactured as follows. First, only the finned annular hollow aluminum member 111 in the portion indicated by the broken line in FIG. 1 is made in advance from an aluminum alloy using a sand mold or the like. In this case, the finned hollow aluminum member 19 may be produced by splitting the annular body vertically (2'), or by dividing it into two or more pieces in the circumferential direction, and then forming these into two or more pieces. They may be combined to form an annular body. The inner diameter of the finned annular member 19 is machined. This finned annular hollow aluminum member 19 is selected from molds B and 0 consisting of three combination molds as shown in Nos. 2 to 4WJ. The finned annular hollow aluminum member does not float even when molten metal is poured into it by fitting it into the protruding part of the mold.
In this state, aluminum alloy is poured indoors, and the fin-sealing annular hollow AKZS material 19 is cast into the piston crown part 2. After the molten metal has solidified, first remove the central one of the metal bases, B, and O. Then, by placing mold B or C into the empty 9 molds, the mold is removed, and the material for this piston is completed.

After that, the material is machined (land, skirt part, etc.), and the oil inlet 13, oil passage 14, and oil outlet 18 are drilled and drilled, and the oil supply groove 14a is formed. , the piston l is completed by driving in the plug llb, which is a blank lid.

In the above manufacturing process, since the finned annular hollow aluminum member 19 is immobile during casting, the thickness of the crown portion 2 of the piston 1 is accurately formed. The thickness of the crown part of a gasoline engine piston is approximately 5 mm, and if the manufacturing method was to simply cast a hollow aluminum member, the metal would float during pouring, resulting in a manufacturing error of several inches, resulting in a failure in production. It is almost impossible to manufacture a piston having an oil cooling passage in the round part as in the invention, and it is only possible to manufacture it by using the casting method with an integrated metal holder as described above. Note that the broken lines shown in FIG. 1 indicate the boundaries of the casting. FIG. 5 shows a second embodiment of the present invention. In the above description, a case was shown in which the oil supply to the oil circulation path 8 was achieved by connecting the oil passage in the connecting rod, but in this embodiment KTh, a case was shown in which the oil supply to the oil circulation path 8 was carried out by an oil jet. It shows the case. 22 in the diagram
is an oil jet pipe that opens upward and has nine oil jet ports 23, and is connected to the oil passage in the cylinder tab I-tsuku 24.The oil jet pipe is connected to the oil passage in the cylinder tab I-tsuku 24. oil inlet 1
3 and enters the oil l1lII path 8 yen 0 Other 0 configuration Hiro, ot'' corresponding to No. 11131111 Part KJ [111i and the same reference numerals are given, and the explanation will be omitted.

Figures 186 and 7 show the present invention on the top surface of the piston! !
III! In this embodiment, the finned hollow aluminum member 19 is separately manufactured using Wpll or the like, and is not connected to the mold. After processing the fitting part (part 41 in the figure) ~, gold 11B or 00 central out l111 or d
By fitting, it is established and cast in good condition. Other steps are similar to those in the first embodiment, so their explanation will be omitted.

In this embodiment, the part without the concave 1B25,')t)
Opposite side of bladder! A hollow aluminum member with fins is cast in the dovetail end part that rests on the gas part, and the inside is used as the oil circulation path 8, and the part 4at that fits into the central outlet lIB or C' part of gold 11B or C is the oil discharge port 58. ing. Other configurations are similar to the first embodiment.

The operation of the present invention will now be explained.

First, the cooling oil supplied to the oil inlet 13 and the foil circulation path 8 is accompanied by the piston lO reciprocating 11jK, and while flowing on the oil circulation path wall surface, it gradually flows to the oil outlet 18. The piston is kept in the oil circulation path for a period of time to cool the piston and rise in temperature, and the oil eventually comes out of the oil outlet 18 and falls. Further, the oil in the oil circulation path 8 takes away a large amount of heat from the piston due to the effect of increasing the contact area of the fins 9.

9. If the oil circulation path 8 is annular as in the first and second embodiments, the piston is cooled evenly around the circumference, so uneven thermal deformation is less likely to occur. So,
Large piston friction is suppressed from occurring.

Furthermore, the oil circulation path 8 is connected to the first piston ring groove 5.
Since the piston ring is formed above the piston ring, most of the heat is removed by the oil, and troubles caused by heat being transmitted to the piston ring are suppressed.

Therefore, the piston of the internal combustion engine of the present invention provides the following various effects. First, since the oil retention time and contact area of the piston are increased, efficient piston cooling becomes possible.
The temperature at the top surface of the piston can be reduced accordingly.

Thereby, it is possible to lower the end gas temperature and suppress the occurrence of knocking, and it is possible to improve fuel efficiency by increasing the compression ratio.

In addition, the piston can be cooled mainly by oil cooling, and the oil circulation path is annular, which enables uniform cooling, which minimizes thermal deformation of the piston and distortion of the piston ring groove. can reduce piston friction.

Furthermore, since the oil circulation path is configured by a casting that is integrated into the mold, it is possible to provide an accurate and highly precise oil cooling piston structure, and it is possible to manufacture pistons with the above configuration, function and effect. It can be done.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a piston according to an eleventh embodiment of the present invention, FIG. Figure 4 is a schematic diagram of a mold used for manufacturing the piston, Figure 5 is a vertical sectional view of a piston according to the second embodiment of the present invention Q, and Figure 6 is a schematic diagram of the piston according to the third embodiment of the present invention. FIG. 7 is a longitudinal sectional view of such a piston, and FIG. 7 is a plan view of the piston shown in FIG. 1...Piston 2...Crown part 3...Piston pin 4...Piston pin boss 5...tJ1 piston ring groove 6...
・Second piston ring groove 7...Oil ring groove 8...Oil circulation path 9...Fin 10...Piston pin 3 circle partition wall 11...・Mekla-5 lid plug 12...Piston pin 3 circle oil passage space 13...
・Oil inlet 14--Oil passage 15--Connecting rod 16--Oil passage 17 in the connecting rod
...Oil supply hole 18 provided in the piston pin ...Oil discharge port 19 ...Hollow aluminum construction member 22 ...Oil jet pipe 23 ...Oil spout 24 ...Cylinder block, B, O... Kanaya 1jlS3 Kyo Figure 4

Claims (1)

[Claims] (1) A hollow aluminum member with fins is cast into the crown of the piston, an oil inlet and an outlet are formed at appropriate locations on the hollow aluminum member, and the hollow space inside the hollow aluminum member is used as an oil circulation path. A piston for an internal combustion engine characterized by: