JPH0320521Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to a piston for internal combustion engines, and in particular to the structure of a light alloy piston in which alternative members made of heat-resistant or wear-resistant materials are cast in positions where high thermal or mechanical loads are applied. .

[Conventional technology]

In recent years, pistons made of light alloys such as aluminum are often used in internal combustion engines for automobiles in order to reduce the inertial mass of moving parts. However, since light alloy pistons have inferior thermal and mechanical strength compared to cast iron pistons, they can be used in positions where higher thermal or mechanical loads are applied than conventional pistons, for example, as shown in Figure 1. A heat-resistant, wear-resistant material such as Ni-resist or cast iron is applied to the circumference of the piston ring groove (particularly the top ring groove) formed on the side wall of the main body 3 and the recess formed at the top of the piston main body 4 as shown in FIG. Alternative members 1 and 2 consisting of are integrally cast.

[Problem that the idea aims to solve]

However, heat-resistant and wear-resistant materials such as Niresist and cast iron used as alternative members have lower thermal conductivity than light alloys such as aluminum, and also have low thermal conductivity between the alternative member 1 or 2 and the piston body 3 or 4. Since the piston has thermal resistance, its temperature rises during engine operation, resulting in a problem that melting occurs at the contact portion between the substitute member 1 or 2 and the piston body 3 or 4. One way to solve such problems is to
It is conceivable to cool the alternative member with a cooling medium such as oil. Structurally, a system that cools alternative parts by heat exchange with oil for piston cooling was developed in 1982.
It is known from the publication No. 039836. According to the piston disclosed in the above publication, an alternative member (wear-resistant ring material, ring trager) cast into the ring groove or top of the light alloy piston and a cooling cavity (so-called cooling channel) are integrated. The replacement member can be cooled by cooling (lubricating) oil flowing within the cooling cavity. Therefore, according to this device, the above-described problem, that is, the melting loss of the contact portion due to the temperature rise of the substitute member can be suppressed to some extent. However, the structure of the above device may not be able to sufficiently lower the temperature of the alternative member depending on the operating conditions of the engine. Specifically, while the internal combustion engine is operating, cooling oil constantly flows into the cooling cavity, so this oil suppresses excessive temperature rises in the piston body and alternative members. For example, during high-speed, high-load operation, the amount of heat transferred to the piston body increases as the combustion temperature increases. Therefore, the oil that flows into the cooling cavity is used to lower the temperature of the piston body, and the oil in the cooling cavity inevitably causes a temperature rise due to heat exchange with the piston body. It turns out. Therefore, due to this increase in the temperature of the oil, the temperature of the substitute member cannot be lowered much. For this reason, when the piston body is cooled by heat exchange with oil, the degree of temperature drop will be large because the piston body itself is made of a light alloy, but it has low thermal conductivity to begin with, and A temperature difference occurs between the substitute member and the substitute member whose temperature cannot be lowered, and depending on the temperature difference, melting loss at the contact portion may not be prevented or cracks may occur at the contact portion. Therefore, the present invention effectively cools an alternative member made of a heat-resistant and wear-resistant material that is integrally cast into a light alloy piston, suppresses the temperature difference at the contact area with the piston body, and reduces melting. The purpose is to prevent damage and cracks from occurring.

[Means to solve the problem]

Therefore, in order to solve the above problems, the present invention is provided with a head having a ring groove formed on the side wall and a skirt section located below the head, and which is capable of thermally or mechanically In a piston for an internal combustion engine made of a light alloy, in which a substitute member made of a heat-resistant or wear-resistant material is cast in a position where a high load is applied, a cooling member is connected to the substitute member via a connecting member, This cooling member is characterized in that it is arranged in an internal space on the back side of the piston.

[Effect]

According to the internal combustion engine piston of the present invention, since the cooling member connected to the substitute member is provided in the internal space on the back side of the piston, the temperature of the substitute member can be lowered by the oil splashing inside the piston. . At this time, since the cooling member is arranged in a non-contact state with the piston body, the temperature of the cooling member and the oil adhering to the cooling member is not affected by the heat from the piston body, making it possible to use the alternative member effectively. can be cooled down.

【Example】

Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 3 is a longitudinal sectional view showing the main parts of a piston for an internal combustion engine according to an embodiment of the present invention. In this figure, the left half is a cross section including the axis of the piston pin (not shown), and the right half is a cross section of the piston. Each section is shown perpendicular to the axis of the pin. A piston 5 for an internal combustion engine (hereinafter simply referred to as a piston) is made of a light alloy such as aluminum, and has a head 9 in which ring grooves 6, 7, and 8 are formed on the side wall, and is located below the head 9. Skirt part 1
It is composed of 0. 11 is a pin hole for inserting a piston pin (not shown). Piston rings (not shown) are loosely fitted into the ring grooves 6, 7, and 8, and the piston rings vibrate up and down within their respective ring grooves during engine operation. Among these ring grooves, especially the first ring groove 6
is closest to the combustion chamber (not shown) and has the highest temperature compared to the other ring grooves 7 and 8, and the strength of the material on its inner wall surface is significantly reduced, and due to contact with the piston ring. Easy to cause wear. Therefore, in place of the material of the piston body, an annular substitute member 12 made of Niresist, which is a heat-resistant and wear-resistant material, is cast into the first ring groove 6. 4 and 5 are diagrams showing the specific structure of the alternative member 12 used in this embodiment, and FIG. 4 is a top view showing the connection structure of the alternative member, a cooling member and a connecting member described later, Figure 5 shows V-V in Figure 4.
FIG. As described above, the alternative member 12 has an annular shape, and the annular cooling member 13 is arranged concentrically inside the alternative member 12 . The alternative member 12 and the cooling member 13 have eight connecting members 14 extending in the radial direction.
connected by. As shown in FIG.
is arranged in the internal space 15 on the back side of the piston. At this time, the cooling member 13 is disposed in a non-contact state with the piston body, and is disposed so that oil that is scattered during operation of the internal combustion engine adheres to the cooling member 13. The operation of this embodiment in the above configuration will be explained. As the internal combustion engine operates, the piston 5 reciprocates within a cylinder (not shown). At this time, piston 5
The heat inside the combustion chamber is transferred to the combustion chamber, causing the temperature of each part to rise. As the temperature rises, the temperature of the substitute member 12 cast into the ring groove 6 also rises. However, the heat of the alternative member 12 is
4 to the cooling member 13 disposed in the internal space 15 on the back side of the piston. Since the cooling member 13 is arranged so that oil that scatters as the internal combustion engine is operating is attached to it,
This oil serves as a cooling medium, and the temperature transmitted to the cooling member 13 is reduced. Furthermore, since the cooling member 13 of this embodiment is disposed in a non-contact state with the main body of the piston 8, the oil adhering to the cooling member 13 absorbs only the heat transferred via the alternative member 12 and the connecting member 14. It will be used for cooling. Therefore, the heat of the piston 5 body is transferred to this cooling member 1.
The oil adhering to the cooling member 13 without being directly transmitted to the cooling member 13 is effectively used to lower the temperature of the substitute member 12 and the connecting member 14. Note that the piston 5 body is cooled by oil that scatters and adheres to the wall surface on the back side of the piston, thereby suppressing the temperature rise. Tables 1 and 2 show the experimental conditions and experimental results when a diesel engine was used to compare the temperature states of the piston 5 according to this embodiment and the alternative member for the piston shown in FIG. It can be seen that the temperature rise of the substitute member 12 is sufficiently suppressed in each example.

【table】

[Table] As described above, according to the piston 5 according to the present embodiment, the temperature of the alternative member 12 is reliably reduced, so generation of a temperature difference at the contact portion between the alternative member 12 and the piston 5 is suppressed. This can prevent melting damage and cracking. Furthermore, in the piston 5 according to this embodiment,
The alternative member 12 and the cooling member 13 are connected by a radially extending connecting member 14, and the piston 5
It is cast through the head 9 from the outside to the inside 15. Therefore, even if the substitute member 12 were to separate from the head 9 of the piston 5, the substitute member 12 would not fall off from the head 9 of the piston 5, thereby improving reliability. You can also do it. FIG. 6 is a longitudinal sectional view showing the main parts of a piston for an internal combustion engine according to another embodiment of the present invention. In this figure as well, the left half shows a cross section including the axis of the piston pin (not shown), and the right half shows a cross section perpendicular to the axis of the piston pin. In this embodiment, the same components as those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, a recess 17 is provided on the upper surface (top) 16 of the head 9 of the piston 5 to improve combustion efficiency. The periphery 18 of this recess 17
Since it is exposed to high temperature combustion flame or combustion gas, the temperature of the upper surface (top) 16 is the highest. Therefore, if the periphery 18 of the recess 17 remains a light alloy such as aluminum, there is a risk of melting, so a ring-shaped substitute member 19 made of Niresist, which is a heat-resistant material, or cast iron is cast into the periphery 18 of the recess 17. It is rare. 7 and 8 show the specific structure of the alternative member 19, FIG. 7 is a top view showing the connection structure of the alternative member, the cooling member, and the connecting member, and FIG. 8 is the same as that of FIG. 7. - is a longitudinal cross-sectional view along the line. An annular cooling member 20 is arranged concentrically below the alternative member 19, and these two members are connected by eight connecting members 21. As shown in FIG. 6, these members include an alternative member 19 and a connecting member 21 which are cast into the head 9 of the piston 5, and a cooling member 20 which is formed in the inner space formed on the back side of the piston 5. It is located at 15. The cooling member 20 in this embodiment is also arranged in a non-contact state with the piston 5 body. Since the effects of this embodiment are the same as those of the first embodiment, only the experimental results are shown in Table 3, and their explanation will be omitted. In this comparative experiment, the temperature states of the piston 5 according to this embodiment and a substitute member for the piston shown in FIG. 2 were compared under the conditions shown in Table 1.

[Table] Although a specific embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and includes various embodiments within the scope of the claims for utility model registration. It is something that will be done.

[Effects of the invention] As described above, according to the internal combustion engine piston of the present invention, the cooling member connected to the alternative member is provided in the internal space on the back side of the piston, so the effect is improved by the oil splashing inside the piston. Therefore, it is possible to reduce the temperature of the substitute member. At this time, since the cooling member is placed in a non-contact state with the piston body, the temperature of the cooling member and the oil surrounding the cooling member is not affected by the heat from the piston body, making it possible to use the alternative member effectively. can be cooled down.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of the main part of a light alloy piston in which an alternative member made of a heat-resistant and wear-resistant material is provided in the conventional ring groove, and Figure 2 is an alternative member made of a heat-resistant material in the periphery of the recess at the top of the conventional piston. FIG. 3 is a vertical cross-sectional view showing the main parts of a piston for an internal combustion engine according to an embodiment of the present invention, and FIG. 4 shows an alternative member, a cooling member, and a connecting member. Figure 5 is a top view showing the connection structure of Figure 4.
6 is a vertical sectional view showing the structure of a piston for an internal combustion engine according to another embodiment of the present invention, and FIG. 7 is a longitudinal sectional view taken along line V, and FIG. A top view showing the connecting structure of the connecting members, and FIG. 8 is a longitudinal sectional view taken along the line - in FIG. 7. 5... Piston, 6, 7, 8... Ring groove, 9
...Head, 10...Skirt part, 12,19...
Alternative member, 13, 20...Cooling member, 14, 21
... Connection member, 15 ... Internal space on the back side of the piston, 16 ... Piston top surface (top).

Claims (1)

[Claims for Utility Model Registration] A head with a ring groove formed on the side wall and a skirt located below the head, and located at a position on the surface of the head where a high thermal or mechanical load is applied. In a light alloy internal combustion engine piston in which an alternative member made of heat-resistant or wear-resistant material is cast, a cooling member is connected to the alternative member via a connecting member, and this cooling member is connected to the back side of the piston. A piston for an internal combustion engine, characterized in that the piston is disposed in an internal space of the piston.