JPS6027783Y2 - Combustion chamber of internal combustion engine - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a combustion chamber of an internal combustion engine.

One way to improve the fuel consumption rate is to increase the compression ratio of the engine, but in conventional internal combustion engines, when the compression ratio is increased and regular gasoline is used, knocking occurs, which worsens the emissions and fuel consumption rate. The result is that.

Therefore, in order to prevent knocking in such internal combustion engines, it is currently necessary to use fuel with a higher octane number than normal gasoline.

Generally speaking, it is necessary to increase the combustion speed in order to prevent the occurrence of knocking and to increase the output by making the pressure within the combustion chamber peak immediately after top dead center.

Therefore, in a high compression ratio internal combustion engine, if the combustion speed is increased to suppress the occurrence of knocking, and if the pressure in the combustion chamber peaks immediately after top dead center, the occurrence of knocking will be limited even when using normal fuel with a low octane number. Change the ignition timing to MBT (Minimum 5parkAdvan
ce for Be5t Torque), and as a result, it is possible to obtain a sufficiently high output and improve emissions and fuel consumption.

As an internal combustion engine that can bring the knocking limit ignition timing closer to The intake valve is placed in the cylinder head so that the inner wall surface of the cylinder head excluding the recess and the top surface of the piston are formed as flat surfaces, and the front surface of the intake valve is located on substantially the same plane as the flat inner wall surface of the cylinder head. An internal combustion engine is provided in which a narrow squish area of substantially uniform height is formed between the flat inner wall surface of the cylinder head and the flat top surface of the piston when the piston reaches top dead center, and the squish area is located at the center of the combustion chamber. A groove having a height interval slightly larger than the height interval of the squish area is formed between the flat inner wall surface of the cylinder head and the flat top surface of the piston, and the groove is communicated with the recess, and the groove is connected to the recess. An internal combustion engine in which a spark plug electrode is arranged has already been proposed by the present applicant (see Japanese Patent Publication No. 58-4557).

In this internal combustion engine, the exhaust gas temperature decreases because the compression ratio is high and the combustion speed is extremely fast. However, when the exhaust gas temperature decreases, even if a catalytic converter is installed in the engine exhaust system, the catalyst temperature may not be high enough. First, since the activity of the catalyst decreases in this way, it becomes difficult to purify harmful components in the exhaust gas, especially unburned HC.

An object of the present invention is to provide an internal combustion engine that reduces the amount of unburned HC in exhaust gas by purifying unburned HC in a combustion chamber.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIGS. 1 to 3, 1 is a cylinder block, 2 is a piston that has a flat top surface 2a and can reciprocate within the cylinder block 1, and 3 is a cylinder block 1.
4 is a combustion chamber formed between the piston 2 and the cylinder head 3, 5 is a cylindrical recess formed in the cylinder head 3 at the periphery of the combustion chamber 4, and 6 is an intake hole. 7 is an intake port, 8 is an exhaust valve, and 9 is an exhaust port.

The recess 5 is formed by a vertically disposed peripheral wall surface 5a and a flat bottom surface 5b, and the contour of the recess 5 is formed into a persimmon leaf shape as shown in FIG.
is placed.

On the other hand, the cylinder head inner wall surface 3a excluding the recess 5 is formed from a flat surface, and the intake valve 6 is arranged in such a way that the front surface of the bulk part of the intake valve 6 is located in the same plane as the cylinder head flat inner wall surface 3a. placed on top.

As shown in FIG. 1, when the piston 2 reaches the top dead center, the gap between the piston flat top surface 2a and the cylinder head flat inner wall surface 3a is 1 to 25 mm or less, so that the piston flat top surface A squish area is formed between the cylinder head 2a and the cylinder head flat inner wall surface 3a.

This squish area is located in the recess 5 as shown in Figure 2.
The squish area is formed to surround the cylinder bore, and the squish area is formed to have an area of 40 percent or more of the cross-sectional area of the cylinder bore.

On the other hand, a shallow groove 10 having a uniform width is formed on the flat inner wall surface 3a of the cylinder head, extending from the intake valve 6 toward the recess 5.

As shown in FIG. 2, this groove 10 has a width approximately equal to the bulk diameter of the exhaust valve 8, and is formed approximately at the center of the combustion chamber 4.

Furthermore, a notch 11 is formed in the groove 10 and communicates with the recess 5, and an electrode of a spark plug 12 is disposed within this notch 11.

Therefore, the electrode of the ignition plug 12 is placed approximately in the center of the combustion chamber 4.

Furthermore, as shown in FIGS. 2 and 3, the electrode attachment of the spark plug 12 is oriented slightly toward the recess 5 with respect to the vertical plane passing through the intake valves 6, 8 on its end face.

This is important, as experiments conducted by the present inventor have revealed that knocking cannot be suppressed when the electrode of the spark plug 12 is attached with its end face facing the intake valve 6.

According to the present invention, the inner wall surface of the cylinder head 3 excluding the exhaust valve 8 shown by hatching in FIG. 2, that is, the inner wall surface of the cylinder head located on the exhaust valve 8 side from the edge of the intake valve 6 on the exhaust valve δ side 3a, the bottom wall surface of the groove 10, and the recess 5
The peripheral wall surface 5a and the flat bottom surface 5b are coated with an unburned HC purifying catalyst.

As this catalyst, platinum, copper, nickel, palladium, iron, etc. can be used.

As can be seen from FIG. 2, the inner wall surface 3a of the cylinder head around the intake valve 6 is not coated with a catalyst to prevent knocking.

The combustible air-fuel mixture introduced into the combustion chamber 4 through the intake valve 6 during the intake stroke is compressed as the piston 2 rises, and when the piston 2 reaches about 30 degrees before top dead center, the piston flat top surface 2a A squish flow flows into the recess 5 through the groove 10 or directly from the squish area formed between the cylinder head and the cylinder head flat inner wall surface 3a.

Squish flows flowing into the recess 5 from around the recess 5 collide with each other, thereby generating strong turbulence within the recess 5.

Next, when the flammable mixture is ignited by the spark plug 12, a flame kernel is formed on the spark plug electrode body, and this flame kernel rapidly grows into the recess 5 due to the squish flow flowing in the groove 10.

Strong turbulence has occurred within the recess 5, and the recess 5
Since the ignition plug 12 is arranged so that the flame propagation distance from the ignition plug 12 to each corner of the recess within the recess is the shortest distance, the combustion speed within the recess 5 is extremely fast.

Next, the piston 2 reaches the top dead center, but at this time, the distance between the piston flat top surface 2a and the cylinder head flat inner wall surface 3a is less than the quench distance, so the flame does not propagate within the squish area.

Next, when the piston 2 descends and reaches around 15 to 25 degrees after top dead center, the pressure drop in the squish area causes the unburned air-fuel mixture and flame in the recess 5 and the groove 10 to be sucked into the squish area. Flame propagates at extremely high speed.

Next, during the exhaust stroke, when the exhaust valve 8 opens, the burnt gas in the combustion chamber 4 is discharged into the exhaust port 9 through the recess 5.

At this time, the inside of the recess 5 that constitutes a substantial combustion chamber is maintained at a high temperature partly because the ignition plug 12 is arranged near the exhaust valve 8.

As a result, the amount of unburned HC generated is small at a high compression ratio because the actuator action occurs when the recess 5 moves inward during the exhaust stroke.

Furthermore, as mentioned above, since the peripheral wall surface 5a and the flat bottom surface 5b of the recess 5 are coated with a catalyst, the burned gas comes into contact with the catalyst when passing through the recess 5, thereby reducing unburned HC in the burnt gas. will be oxidized.

Further, unburned HC in the burnt gas flowing into the recess 5 along the cylinder head flat inner wall surface 3a also comes into contact with the catalyst coated on the cylinder head flat inner wall surface 3a and is oxidized at the same time.

Next, when the piston 2 reaches near the top dead center, the burned gas in the squish area flows directly or through the groove 10 into the recess 5.
extruded inward.

At this time, since most of the burnt gas comes into contact with the catalyst coated on the flat inner wall surface 3a of the cylinder head or the bottom wall surface of the groove 10, the oxidation reaction of unburned HC in the burnt gas is further promoted. become.

As described above, according to the present invention, unburned HC in the burnt gas is purified in the combustion chamber before the burnt gas is discharged into the exhaust port, and thus even in a high compression ratio internal combustion engine. Harmful components in exhaust gas can be significantly reduced.

[Brief explanation of the drawing]

1 is a side sectional view of the internal combustion engine according to the present invention taken along line I-I in FIG. 2, FIG. 2 is a bottom view of the cylinder head in FIG. 1, and FIG. 3 is a It is a side cross-sectional view taken along the line -■. 2...Zeston, 3...Cylinder head, 4...Combustion chamber, 5...Recess, 6...
...Intake valve, 8...Exhaust valve, 10...
... Groove, 12... Spark plug.

Claims (1)

[Claims for Utility Model Registration] A cylinder in which a cylindrical recess is formed between the inner wall surface of the cylinder head in the periphery of the combustion chamber and the top surface of the piston, and an exhaust valve is provided in the cylinder head on the top surface of the recess, excluding the recess. The head inner wall surface and the top surface of the piston are formed from flat surfaces, and the intake valve is provided in the cylinder head so that the front surface of the intake valve is located almost on the same plane as the flat inner wall surface of the cylinder head, so that the piston is at the top dead center. The internal combustion engine is configured to form a squish area with a narrow spacing of approximately uniform height between the flat inner wall surface of the cylinder head and the flat top surface of the piston when the cylinder head reaches the flat top surface of the piston. A groove having a height interval slightly larger than the height interval of the squish area is formed between the wall surface and the flat top surface of the piston, and the groove is communicated with the inside of the recess, and a notch communicating with the inside of the recess is connected to the inside of the premises. The electrode mounting formed in the notch and oriented toward the recess forms an end face, and the electrode mounting is arranged on the end face, and the spark plug electrode is disposed on the end face. A combustion chamber of an internal combustion engine in which at least a portion of the wall surface is coated with a catalyst for purifying unburned HC.・