JPS6267219A - Auxiliary combustion chamber for engine - Google Patents

Abstract

PURPOSE:To increase the fastening force of a cylinder section by temperating the section made of a martensitic heat resistant steel after it has been fitted onto a member consisting of an auxiliary chamber so as to be transformed into a sorbite structure. CONSTITUTION:A cylinder section 5 is made of a martensitic heat resistant steel, weight percentages compositions of which are C of 0.13-0.45%, Si of 0.3-2.5%, Mn of 0.5-1.0%, Cr of 10.0-13.0%, Mo of 0.3-1.3%, and Fe of the rest. The cylinder section 5, which is transformed substantially into a martensite structure by heat treatment after it has been machined, is heated up to 500-600 deg.C which is lower than the temperature for tempering, then is fitted onto the outer periphery of a member consisting of an auxiliary chamber 4 by means of shrink fit, and then the cylinder section 5 can be transformed into a sorbite structure by heating the cylinder section 5 up to 750-800 deg.C. The fastening force of the cylinder section 5 can be sharply increased by making good use of the shrinking force of a metal structure, which is produced when the metal is transformed into the sorbite structure by means of tempering.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine sub-combustion chamber, and more particularly to an engine sub-combustion chamber in which a heat-resistant metal cylindrical member is fitted to the outer circumference of a ceramic sub-chamber component. Regarding the auxiliary combustion chamber (prior art) The auxiliary combustion chamber of a diesel engine (hereinafter referred to as the auxiliary chamber) is exposed to high-temperature combustion gas of approximately 1000°C, and it is desirable to maintain it at a high temperature to improve ignitability. ,
Recently, the auxiliary chamber (112) is made of a ceramic material with excellent heat resistance, which is divided into two parts at the bottom. A sub-combustion chamber for an engine is known in which a cylindrical member made of heat-resistant metal is shrink-fitted to the outer circumference of a sub-chamber constituent member to maintain the proper positional relationship (see Utility Model Application No. 175118/1983). )
.

Conventionally, the metal cylindrical member is hardened to have a substantially martensitic structure, for example, 5IJS4.
The cylindrical member is made of martensitic heat-resistant steel such as 03, and the cylindrical member is tempered to form a sorbite structure in order to improve strength and toughness. They were fitted together by shrink fitting.

(Problem to be solved by the invention) By the way, the combustion gas temperature in the pre-chamber is about 1000 to 120
Since the temperature reaches as high as 0°C, heat transfer from the auxiliary chamber constituent members causes the temperature to rise to about 500 to 750°C near both upper ends of the cylindrical member, and to about 700 to 830°C in the middle part of the cylindrical member.

Since the temperature indicated by l- is higher than the temperature at the time of shrink fitting, the effect of shrink fitting is almost lost, and for example, as shown in FIG. This swells, and the tightening force for tightening the sub-chamber constituent member 104 from the outside becomes extremely weak.

As a result, the auxiliary chamber constituent member 104 is divided into upper and lower halves.
Problems may arise, such as the edges of the mating surfaces 104a being damaged, the relatively thin middle part of the sub-chamber component 104 cracking due to combustion gas pressure, and gaps occurring between the mating surfaces 1048.

Incidentally, even if the subchamber constituent members are integrally formed in the upper and lower parts,
Problems such as cracking of the middle part of the sub-chamber forming member occur.

(Means for Solving the Problems) The auxiliary combustion chamber of the engine according to the present invention includes a ceramic auxiliary chamber component constituting the auxiliary chamber, and a metal member fitted to the outer periphery of the solid chamber component. In the auxiliary combustion chamber of an engine equipped with a cylinder member, 1. The foot member has a weight ratio of 0.13 to 0.
．． 45% C, 0.3-2.5% Si and 0.5-1.
0% Mn and 10.0~13.0% C'' and 0.3~1
．． The cylindrical member is made of martensitic heat-resistant steel with a substantially martensitic structure consisting of 3% MO and the balance substantially composed of Fe, and this cylindrical member is shrink-fitted to the sub-chamber constituent member. It has been processed to form a sorbite structure.

(Function) Since the sub-combustion chamber of the engine according to the present invention is configured as described above, the following effects can be obtained.

First, in relation to the components of the cylindrical member, 0.3 to 2.
Contains 5% Si and 0.5-1.0% Mn, improving hardenability and preventing embrittlement.
Since it contains 13.0% Cr, heat resistance is improved and the coefficient of thermal expansion becomes an appropriate value, and since it contains 0.3 to 1.3% Mo, it improves hardenability, strength, and hot resistance. The creep strength at the steel sheet is improved and temper brittleness is also prevented.

Since the cylindrical member is substantially made of martensitic heat-resistant steel having a martensitic structure, it can be changed into a sorbite structure by tempering it.

After shrink-fitting the cylindrical member to the auxiliary chamber constituent member, the structure is tempered to change from martensitic structure to sorbite structure, so in addition to the tightening force due to shrink-fitting, A strong clamping force is generated due to the contraction of the metal structure.

(Effects of the Invention) According to the sub-combustion chamber of the engine according to the present invention, as explained above, the cylindrical member made of martensitic heat-resistant steel substantially woven with martensitic structure I is used as the sub-chamber constituent member. After shrink-fitting, tempering is performed to change the structure to a sorbite structure, so the shrinkage of the metal structure when changing from martensitic structure to sorbite structure is effectively used to significantly strengthen the clamping force of the cylinder member against the sub-chamber constituent members. Even when the cylindrical member is thermally expanded during operation, the auxiliary combustion chamber can be restrained with a sufficient tightening force to prevent damage to the auxiliary combustion chamber, thereby providing a highly durable auxiliary combustion chamber.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, an auxiliary combustion chamber 3 is configured in a cylinder head 2 at a position near the outer periphery of a cylinder bore 1 of a diesel engine and at a position facing a slightly outer periphery thereof as follows.

That is, the sub-combustion chamber 3 basically consists of a sub-chamber constituent member 4 divided into two vertically and a cylindrical member 5 fitted to the outer circumferential portion of the sub-chamber constituent member 4. is fitted into the substantially cylindrical recess 6 of the cylinder head 2 from below, and the lower end flange-like portion 5 of the cylindrical member 5 is assembled integrally with the cylindrical member 5.
By fitting a into the lower end fitting part 6a of the recess 6 and the first and second ends of the cylinder member 5 into the upper end fitting part 6b of the recess 6,
Can be assembled.

- A combustion chamber 7 is formed inside the leg side chamber component 4, and this combustion chamber 7 has a nozzle 8 that is diagonally directed toward the center of the cylinder pore 1 in the bottom wall of the sub-chamber component 4. A fuel injector 9 is obliquely mounted on the cylinder head 2 in communication with the combustion chamber and above the four parts 6, and the nozzle of this injector 9 is inserted into a circular hole 10 in the upper wall of the subchamber component 4.
facing the combustion chamber 7 through the fuel injector 9, a glow plug ll'IJ< is mounted on the side closer to the center of the engine than the fuel injector 9; It has entered the combustion chamber 7.

Further, an annular elastic seal member 12 made of stainless steel is interposed between the upper end outer circumferential portion of the sub-chamber component 4 and one wall surface of the four parts 6 facing thereto, and a ring-shaped elastic seal member 12 made of stainless steel is interposed between the upper end outer circumferential portion of the sub-chamber constituent member 4 and one wall surface of the four portions 6 facing thereto. A cylindrical heat insulating space 13 is formed on the outer peripheral side of the cylindrical member 5 at the upper end of the cylindrical member 5 .

The subchamber component 4 is made of silicon nitride (s), which has excellent heat resistance.
+5N4), and is divided into an upper half 4a and a lower half 4b for convenience of molding, and these are the above-mentioned cylindrical member 5.
It is held in a predetermined positional relationship and reinforced to withstand the combustion gas pressure.

The cylindrical member 5 has an auxiliary chamber forming member 4 which is divided into upper and lower parts.
A and 4b are held in a predetermined positional relationship and the outer peripheral part of the sub-chamber constituent member 4 is pressed with sufficient contact pressure so that the ceramic sub-chamber constituent member 4 is not damaged by the combustion gas pressure. Since the temperature distribution of the cylindrical member 5 during engine operation is at a high temperature as shown in FIG. 2, the cylindrical member 5 needs to be made of heat-resistant steel with excellent strength.

The cylindrical member 5 is heated to 500 to 600°C and fitted to the outer circumference of the sub-chamber component 4 by shrink fitting. However, since the cylindrical member 5 is in a high temperature state higher than the shrink fitting iU&, tightening by shrink fitting is performed. Most of the effect is lost.

The present invention aims to significantly strengthen the tightening force of the cylindrical member 5 by focusing on the contraction of the metal structure when the martensitic m weave in heat-resistant steel or the like changes to a sorbite structure through tempering.

Therefore, the cylindrical member 5 is manufactured from martensitic heat-resistant steel, and after the machining is completed, it is quenched to have a substantially martensitic structure, and the cylindrical member 5 with this martensitic structure is heated at a temperature lower than the tempering temperature. 500～
The sub-chamber component 4 is heated to a temperature of 600°C and shrink-fitted.
Finally, the cylindrical member 5 having the martensitic structure is heated to a temperature of 750 to 800° C. to be tempered, thereby converting it into the cylindrical member 5 having the sorbite structure.

However, the above-mentioned tempering treatment may be performed before the above-mentioned auxiliary combustion chamber 3 is assembled to the cylinder head 2, but since most of the cylindrical member 5 is heated to the above-mentioned tempering temperature during engine operation, the tempering Before the treatment, the auxiliary combustion chamber 3 may be assembled to the cylinder head 2 so that the secondary combustion chamber 3 is naturally tempered during operation of the engine.

The martensitic heat-resistant steel applied to the cylinder member 5 is desirably made of heat-resistant steel containing the components listed in the component range column of Table 1 below.

The items listed in the column of component range are as follows: The cylindrical member 5 was manufactured using the three types of martensitic heat-resistant steels listed in Table 1, and as a result of the following tests, good performance was obtained. , is set to cover the composition range of the above three types of heat-resistant steel.

(Left space on this page) Table 1 (Composition of martensitic heat-resistant steel) Table 1 (continued) Note 2 The composition of the above martensitic heat-resistant steel is Ii" e
It goes without saying that the other components are expressed in weight%, and the remainder is F"e. Also, the above S II H3 and S tJ H600 are listed in JIS standards, and TAF is 11.
This is the YSS standard symbol of Tatekinzoku Co., Ltd.

As shown in Table 1 above, the inclusion of appropriate amounts of Si and Mn improves hardenability and prevents embrittlement, and the inclusion of an appropriate amount of Ni improves hardenability, machinability, and high-temperature strength. The grain size was made finer, and Cr was added to Jyen gold. The heat resistance is improved, the thermal expansion coefficient does not become too large, and the inclusion of an appropriate amount of MO promotes L-liauthnitization (improves hardenability), prevents temper brittleness, and hot creep strength. The aim is to improve
By incorporating Nb, heat resistance and oxidation resistance are improved. When it is impregnated with (1) through (1), the crystal grains are made finer and the heat resistance is improved.
Prevents red heat brittleness at a temperature of 0°C.

Next, examples of quenching, firing, and tempering treatments performed on the cylindrical member 5 made of three types of martensitic heat-resistant steels (StJH3, TAF, and 5UH60(1) shown in FIG. 1) are shown in FIG. I will explain about it.

The hardening treatment and firing process in the examples are as described in Table 2 below.

Table 2 (Quenching Treatment/Sintering Temperature and Time) The above-mentioned quenching treatment is carried out to change the ausnitite structure of the cylindrical member 5 to a martensitic structure and improve its strength and heat resistance.

The annealing treatment after the above-mentioned firing changes the martensitic structure of the cylindrical member 5 to a sorbite structure, thereby improving its strength.
This is done to improve the elasticity and to strengthen the tightening force of the cylindrical member 5 against the sub-chamber forming member 4 by the contraction force when the martensitic structure changes to the sorbite structure.

In the above three types of martensitic heat-resistant steels, the tempering temperature when changing from martensitic structure to tsurupai weave is if! The temperature is higher than that for conventional carbon steel, about 750-800°C.

As can be seen from the temperature distribution in FIG. 2, most of the cylindrical member 5 other than the upper and lower ends is heated to the above-mentioned tempering temperature during engine operation. Accordingly, the cylindrical member 5 was tempered.

The measurement results of the contact pressure between the cylindrical member 5 and the subchamber component 4 are shown in Table 3.

Table 3 (Contact pressure between cylindrical member and auxiliary chamber constituent members) Remarks The contact pressures in Table 2 are values when the cylindrical member 5 is at room temperature.

As can be seen from Table 3 above, compared to the case where the cylindrical member 5 is simply shrink-fitted, when the cylindrical member 5 is tempered after shrink-fitting, the contact pressure of the cylindrical member 5 decreases due to contraction when changing from martensitic structure to sorbite structure. Tightening force is increased by 65-75%. Further, since the high temperature part changes to a sorbite structure, the shrinkage rate is high, and thermal deformation (thermal expansion) of the cylindrical member 5 is suppressed, and as a result, the entire subchamber constituent member can be tightened with uniform force.

In this embodiment, a case has been described in which the sub-chamber constituent member 4 is divided into two parts vertically, but it goes without saying that the above-mentioned cylindrical member 5 can be similarly applied to the case where the sub-chamber constituent member 4 is integrally formed. .

[Brief explanation of drawings]

Of the drawings, Figures 1 and 2 show an embodiment of the present invention. Figure 1 is a vertical cross-sectional view of the sub-combustion chamber of a diesel engine and its surrounding structure, and Figure 2 is a vertical cross-sectional view of the auxiliary combustion chamber of a diesel engine and its surrounding structure. FIG. 3 is an explanatory diagram illustrating deformation due to thermal expansion of a cylindrical member in a conventional sub-combustion chamber. 3. Sub-combustion chamber, 4. Sub-chamber constituent member, 5. Cylindrical member.

Claims (1)

[Claims] (1) In a sub-combustion chamber of an engine comprising a sub-chamber component made of ceramic and a metal cylindrical member fitted to the outer circumference of the sub-chamber component, the cylindrical member is 0.13-0.45% C and 0.3-2.5% by weight
% Si and 0.5-1.0% Mn and 10.0-13.
It is made of martensitic heat-resistant steel with a substantially martensitic structure consisting of 0% Cr, 0.3 to 1.3% Mo, and the balance substantially composed of Fe, and this cylindrical member is A sub-combustion chamber for an engine, characterized in that the component is shrink-fitted and then tempered to form a sorbite structure.