JPS5852325Y2 - Engine subchamber - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of an auxiliary combustion chamber of an engine, particularly a diesel engine, which is constructed by inserting a cap made of ceramic material.

Constructing the sub-combustion chamber of the engine with a highly insulating ceramic material increases the compression temperature due to reduced cooling water loss, reduces ignition delay, and reduces noise and harmful exhaust components such as nitrogen oxides (NOX). It is known that the reduction effect of

3 and 4 show examples in which a conventional mouthpiece made of ceramic material is used in the sub-combustion chamber of an engine. In the conventional example shown in FIG. Therefore, as shown in characteristic A in FIG. 5, which is a comparative characteristic diagram showing the relationship between average effective pressure and cap temperature, heat transfer is good and the overall temperature of the cap 10 can be kept at a relatively low temperature. However, the difference in temperature between the portion 10a of the cap located above the cylinder bore and the portion 10b of the cap located above the cylinder rad gasket 40 is large, causing a large thermal strain inside the cap. Since the entire circumferential wall of the cylinder head 20 is in close contact with the cylinder head 20, the heat conduction area increases and the temperature of the mouthpiece decreases too much, which has the disadvantage of inhibiting combustion at partial loads or when the cooling water temperature is low.

In addition, in order to eliminate the above-mentioned drawbacks and malfunctions, we have added
Fig. 4 shows an example of a cap in which a gap S of 0.1 to 1.0 mm width is provided around the entire circumference.
As shown in , the temperature of the base 10 itself reaches a significantly high temperature, and at the same time, the temperature difference between the portions 10a and 10b becomes significant, resulting in an even greater thermal strain.

This invention was devised in view of the above-mentioned two drawbacks of the conventional examples.It suppresses the temperature rise of the cap during combustion to a relatively low temperature, and extremely reduces the temperature difference inside the cap, thereby improving durability and reliability. The aim is to provide a sub-combustion chamber with high performance, and its gist is that the sub-combustion chamber is constructed by fixing a cap made of ceramic material to the insertion recess of the sub-combustion chamber provided above the lower surface of the cylinder head, and In a sub-combustion chamber of an engine in which a part of the mouthpiece is located on the cylinder rad gasket, a member with high thermal conductivity is interposed between the peripheral wall of the part of the mouthpiece located on the cylinder bore and the cylinder head. In addition, a gap is provided between the cylinder head and the peripheral wall of the portion located on the radial gasket of the cylinder, and an embodiment thereof will be described below with reference to the drawings.

Reference numeral 1 designates a cylinder body of a diesel engine, in which a piston 2 having a main combustion chamber 2a formed at the top thereof is slidably fitted into a cylinder bore 1a, and a cylinder head 4 is mounted above the piston 2 via a cylinder gasket 3. It is placed.

The head 4 has a recess 5a that constitutes the upper chamber of the auxiliary combustion chamber 5, and a recess 5a that is slightly larger than the recess 5a, into which the cap 6 made of ceramic material, which is a heat-insulating and durable member, that constitutes the lower chamber is inserted below the recess 5a. A recessed portion 5b is formed in the button and the auxiliary combustion chamber 5.
An injection nozzle 8 is disposed above the fuel tank to spray fuel into the fuel tank.

As described above, the cap 6 is made of a ceramic material that is a heat-insulating fireproof member with excellent heat insulation properties, and has a recess 6a that forms a sub-combustion chamber inside, and a nozzle 6b that communicates with the main combustion chamber 2a.
and a radial gasket 3 to the cylinder.
An annular gap 6e of 0.1 to 1.0 mm is formed on the outer surface of the peripheral wall excluding the fitting portion 6d of the upper portion 6c with the head 4.

Further, an annular gap 6g similar to the annular gap 6e is formed on the outer surface of the circumferential wall of a portion 6f located above the cylinder bore of the cap 6, and a member 7 with excellent thermal conductivity such as copper is fitted into the gap 6g. It is equipped.

When the button is pressed during operation of the engine having the auxiliary combustion chamber 5 configured as described above, the portion 6f of the mouthpiece located above the cylinder bore, which reaches a high temperature, communicates with the head 4 via the member 7 having good thermal conductivity. Because of this, heat is easily transferred to the member 7 and the head 4, so a significant temperature rise is suppressed, and the portion 6c side located on the gasket 3, where the temperature rise is relatively small, is formed on its outer periphery. Since they are separated from the head 4 by an annular gap 6e, heat transfer is poor and the temperature rise is maintained at a nearly constant level as shown by characteristic C in FIG. 3
Although it is slightly higher than the characteristic A of the conventional example shown in the figure, the 4th
This can be kept lower than the characteristic B of the conventional example shown in the figure, and the temperature difference between the image portions 6f and 60 can also be made smaller than that of any of the conventional examples.

Therefore, it is possible to prevent compression cracking during cooling as in the conventional example shown in Fig. 3, suppress an excessive rise in temperature as in the conventional example shown in Fig. 4, and furthermore prevent destruction due to thermal strain caused by a significant temperature difference. There is an effect.

As described above, according to the present invention, it is possible to arbitrarily secure the combustion chamber wall temperature necessary for combustion, prevent the breakage of the mouthpiece due to compression cracking and thermal distortion, and provide a highly durable and reliable auxiliary combustion chamber. There is.

Furthermore, since the sub-combustion chamber according to the present invention requires only the annular gap 6e to be formed in the conventional heat-insulating cap, it is easy to apply the sub-combustion chamber to the sub-combustion chamber of a conventional engine, and has extremely excellent practical effects.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view showing an embodiment of the auxiliary combustion chamber of the present invention, Figure 2 is a plan view of the same embodiment, Figures 3 and 4 are longitudinal sectional views of the conventional example, and Figure 5 is a longitudinal sectional view of the embodiment of the invention. FIG. 7 is a comparative characteristic diagram showing the relationship between average effective pressure and mouthpiece temperature with a conventional example. 1a Niji cylinder bore, 3 Niji cylinder gasket, 4 Niji cylinder head, 5: Sub-combustion chamber, 5b: Insertion recess, 6: Ceramic mouthpiece, 6c: Portion of the mouthpiece located on the gasket, 6e: Annular gap, 6f: Of the mouthpiece. Portion located above the cylinder bore, 7: A member with high thermal conductivity.

Claims (1)

[Scope of utility model registration request] A auxiliary combustion chamber is formed by fixing a cap made of a ceramic material to an insertion recess of the auxiliary combustion chamber provided above the lower surface of the cylinder head, and a part of the bonnet is positioned on the cylinder radial gasket. In the auxiliary combustion chamber of the engine, a highly thermally conductive member is interposed between the peripheral wall of the part of the mouthpiece located above the cylinder bore and the insertion recess, and the peripheral wall of the part located above the cylinder radial gasket and the cylinder head. An auxiliary combustion chamber for an engine, characterized in that a gap is provided between the auxiliary combustion chamber and the auxiliary combustion chamber.