JPS5870038A - Piston of internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve the heat insulating effect by elongating legs for fitting an upper piston in piston pins and spacing the legs away from a cavity wall, in a piston of a heat insulating type formed by upper and lower pistons. CONSTITUTION:The upper piston 21 made of a low heat transmitting material and having a piston crown part 24, cavity wall 25 and a riing carrier part 30 is fitted in a piston pin 23 by a pair of legs 31 and 32 extending downwardly from the ring carrier part 30. On the other hand, a lower piston 22 making contact with the cylinder wall at the lower part of the upper piston 21 has a pair of pin bosses 33 and 34, and fitted in a piston pin 23 at the outer sides 31 and 32 of the upper piston 21. The rear surfaces of the piston crown part 24 of the upper piston 21 and the cavity wall part 25 thereof are covered with a sheet metal 38 whose peripheral edge part is cast by holding a gap therebetween.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to improve MtlJ+I and improve HC, etc. in the piston of an internal combustion engine, particularly a diesel engine, by using a so-called heat insulating method that prevents heat loss from the piston crown and cavity wall. Regarding types of pistons.

Conventionally, there is a piston of this type as shown in FIG. 1, for example. This is disclosed in Japanese Unexamined Patent Publication No. 54-9312, etc., in which the piston is made of a low heat conductive material such as cast iron for heat insulation, and the upper piston is in sliding contact with the 'ζ cylinder wall through the piston ring. 1 and on the F side Il! It is divided into 1 part pin 2 made of aluminum or the like which makes contact with the cylinder wall, and is constructed by fitting one piston pin 34 with a loose fit.

Specifically, the upper piston l is provided with a piston crown part 4, a bowl-shaped cavity wall part 6 forming a combustion chamber 5 in the center thereof, and '111-third piston ring grooves 7, 8.9. It has a ring carrier part 10 to which a screw ring is attached 7, and a pair of leg parts 11 and 12 for fitting into the piston pin 3 extend from the cavity wall part 6 to the T-horns. In addition, the lower screw 1 and 2 are 1.1:
It is in contact with the 7 cylinder piston on the -F side of the llp + screw 1- I, and has a pair of piston bosses 13.14. 20) Pin boss part +3. If history has a connecting rod 1
One piston is configured by being fitted with five or one piston pin 3.

In addition, in use, the leg portion If of the upper piston l, 1
2 is marked A, and to prevent seizure from occurring at the contact part with the piston pin, the piston pin is cooled by scattering t and f from the 16 toward the legs 11 and 12. There is.

However, in such a conventional piston, legs 11 and 12 for fitting the upper screw 1 to the piston pin 3 extend from the cavity wall 6, and are made of a low thermal conductive material. As a result of the effect, the screw 1 crown part 4 and the cavity wall s6 are very close to IIJllll&A, so the leg part 1
1.12 is also quite high temperature.

Therefore, in order to prevent seizing due to lack of oil film between the legs 11 and 12 and the piston pin 3, it is necessary to
It is necessary to cool down the leg parts 11.12 frequently through 1+111 i+to 11.12, and this results in more heat being rescued from around the combustion chamber 5 through 1+111 i+to 11.12, which reduces the insulation effect. However, there was a problem in that it was not possible to improve thermal efficiency or to construct Emison-Nichi's modified 6 such as HC.

The present invention has been made in view of these conventional problems, and the leg portion for fitting the upper piston to the piston pin extends from the ring carrier portion, and the leg portion is attached to the piston crown portion. Furthermore, a low heat conductive sheet metal material 1 is placed near the connection between the piston crown and the link carrier to cover the back surfaces of the piston crown and the cavity wall with a gap between them. The purpose is to solve the above-mentioned problems by providing the material by casting.

Hereinafter, the present invention will be explained based on the drawings.

Figures 2 and 3i show examples of one of the inventions.

To explain the structure, the one-L piston 21 made of a low heat conductive material includes a screw-in crown part 24, a bowl-shaped cavity wall part 26 for forming a combustion chamber 25 in the center, and first to third parts. The ring carrier part 3 is provided with piston ring grooves 27, 28, 29 and on which the piston ring is mounted.
0, and a pair of legs 31 and 32 extending downward from the ring carrier portion 30 to fit onto the piston pin 23.

Then, the screw crown part 24 and the cavity wall part 2
A gap 37 is maintained with respect to the back surface of 6' (a sheet metal material 38 with low thermal conductivity is arranged to cover these, and this sheet metal material 38 is connected to the screw 1, the screw part 24 and the link carrier part at the edges of L and 'J). The connecting portion with the piston crown portion 24 is cast in the vicinity of the link groove 27 and the like. In addition, ;31) As LJl-, the thrust sensor
The 4M u IW Q) ribs 40 provided in the side direction are holes for removing medium sand, salt core, etc. to form the gap 37.

In addition, (the part piston 22 is the one that contacts the cylinder wall below the upper piston 2X), and a pair of inner piston bosses 133
, 34.

Here, the leg portions 31 and 32 of the upper piston 21 and the pin supports 4333 and 34 of the lower piston 22, a pair of spacers 41 and 42, and a connecting rod 35 are fitted into one piston pin 23, and one The piston is composed of:

Incidentally, reference numeral 36 denotes an oil jet that sprays oil toward the leg portions 31 and 32 to prevent seizure with the piston pin 23.

Next, the action will be explained.

Although not shown, a cylinder head is located on the F section piston 210 side, and high pressure fuel is injected into the combustion chamber 25 from an injection valve attached to the cylinder head.

The fuel is atomized and mixed with air due to air flow such as a swirl formed in the combustion chamber 25, and ignition occurs due to the heat of compression and combustion proceeds. A part of the back of the combustion chamber 4 adheres to the wall of the combustion chamber 25 due to the penetrating force of the injection, but is vaporized by the heat of the wall surface (regarding combustion).

Here, since the area around the combustion chamber 25 is made of a low heat conductive material, there is little heat escaping through the piston to the cooling water or engine oil, and it can be effectively used as exhaust heat. Since the combustion chamber 25 wall becomes high in temperature, it promotes vaporization of attached fuel droplets and improves mixing with air, thereby increasing air utilization efficiency and improving combustion.

Particularly in the case of the present invention, a sheet metal material 38 is provided with a gap 37 maintained on the back side of the piston crown 24 and the cavity wall 26 that forms the combustion chamber 25 at the center thereof, and this gap;
Since the air layer inside is used as a heat insulating layer, the above effect can be further enhanced by the heat insulating effect. In addition, the gap 37
It may also be filled with insulation material.

In addition, the sheet metal material 38 for heat insulation generates heat when oil from the oil inlet 36 or oil splashes scraped up by the crank shirt 1 or the like comes into contact with the high-temperature piston crown portion 24 and the cavity wall portion 2. Prevents carbonization and deterioration of oil.

Therefore, by selecting the oil die 1360 direction and cooling the legs 31.32, a special oil deflector is not required.

Moreover, 1IL116B31. Since it is extended from 324t'J 7M330, the temperature can be kept low, so cooling with oil is reduced.

Historically, the sheet metal material 38 was cast near the connection between the piston crown section 24 and the ring carrier section 30, and had the effect of making it difficult for heat to escape to the ring carrier section 30 side. 11. Reduce running clearance, reduce waste volume. This has the effect of increasing the durability of the piston ring by +b+1.

Other embodiments are shown in FIGS. 4 and 5. In this embodiment, parts that are the same as those in the above-described embodiment are marked with the same symbol (J), and only different parts will be explained.

This example is a sheet metal material 380) 1:, 1 kA^1ζ1
A passage member 44 that forms an oil passage 43 all around the inner wall of the ring carrier portion 30 is attached to the side thereof. The passage member 44 has an oil outlet [145] and an oil outlet l.
] 46 and is closed by the other part ``C'' inner wall of the ring carrier part 30 to form an I-shape. ] is returned to the crank chamber side from the oil outlet 46 through the oil passage 43.

In the case of this embodiment, since the ring carrier B'30 can be cooled in 1 minute, the running clearance between the ring wall and the piston can be reduced, and the volume of the cavity can be increased. This is effective in terms of combustion.Also, the action of the quotient W gas on the first screw ring is eliminated, which increases the durability of the ring. It is possible to attach old parts to the upper surface side of the piston crown part 24, and the ring carrier part 30 can be shortened.

Is this how it is in history? The formation of the oil passage 43 also has the advantage that when using a rounded core, the passage member 44 can be used to suppress the ζ shape.

As explained above, according to the present invention, the leg portion of the upper piston that fits into the piston pin is extended from the ring carrier portion, and the piston crown portion and the cavity wall portion are made of sheet metal while maintaining a gap on the back side. Since the combustion chamber is covered with a heat insulating layer, the heat insulating layer of the screw-in crown portion and the cavity wall portion can be saved, and heat loss from the combustion chamber can be reduced. In addition, since the wall surface of the combustion chamber is maintained at a high temperature, vaporization of fuel droplets adhering to the wall surface is promoted, and mixing with air is improved, thereby improving combustion. In addition, the heat flow t1 from the piston crown to the link carrier 61ζ leg is small (
Therefore, there is less need to cool the legs with oil, and furthermore, the oil scattered in the crank chamber, such as cooling oil, does not adhere to the high-temperature cavity walls, which prevents wasted cooling and oil deterioration. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the conventional example, Fig. 2 is a cross-sectional view of an embodiment of the present invention, and No. 3171 is III-■ in Fig. 2]
Cross-sectional view, Fig. 4 41 Other implementation f (small 4° cross-sectional view, Fig. 5 is a cross-sectional view taken along ■-■ of Fig. 4. 21... Upper screw 1 22... Lower screw ]n2
3... Piston pin 24... Piston crown part 25... Combustion chamber 26... Cavity wall part 30... Ring carrier part 31. 32... Leg part 37... Gap 38... Sheet metal material patent applicant [Ichisan Jidosha Co., Ltd. 1 agent Patent attorney Fujio Sasashima (11) Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] The upper piston is made of a low heat conductive material and is in sliding contact with the cylinder wall via a piston link, and the lower piston is in sliding contact directly with the cylinder wall on the other side. In a piston of an internal combustion engine that is respectively fitted and coupled to a piston pin, the leg part of the upper piston for fitting to the piston pin is extended from the ring carrier part on which the piston ring is attached, while the upper piston 1. Cast a root metal material that covers the piston crown part and the back surface of the cavity wall part while maintaining a gap to the back surface of the piston crown part and the cavity wall part. A piston for an internal combustion engine characterized by the following: