JPS6035529B2 - Combustion chamber of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a combustion chamber of an internal combustion engine that takes exhaust gas measures into consideration.

In order to suppress the generation of harmful components in exhaust gas, especially nitrogen oxides (hereinafter referred to as N○×), it is necessary to lower the maximum combustion temperature in the combustion chamber. It is common to retard the engine, and it is effective to create a lean mixture.

However, depending on the operating conditions of the engine, the ignition timing must not only be retarded but also advanced, which requires a very complex control device. Furthermore, retarding the engine speed increases fuel consumption and reduces output. Furthermore, various inconveniences occur, such as poor drivability when changing the ignition timing. Furthermore, when the mixture is made lean, there is a problem in that ignitability deteriorates and combustion becomes unstable. In view of the above facts, the present invention has been developed so that the maximum combustion temperature in the combustion chamber is low without ignition retardation, and the ignition performance is good even with a lean mixture, so that combustion is performed with a small amount of N○× generated. It attempts to provide the structure of the combustion chamber.

To achieve this objective, the combustion chamber according to the present invention allows fresh air to flow toward the spark plug during the compression stroke, thereby improving ignition performance, and allowing slow combustion at the initial stage of ignition, resulting in a long combustion time. This structure is characterized in that the maximum combustion temperature can be suppressed to a low level and the amount of N○× generated can be reduced to a predetermined value.

More specifically, the inner wall of the cylinder head is configured to intersect two surfaces including an intake valve and an exhaust valve, and these surfaces form a valley bottom, and a recess is provided at one end of the valley bottom. Install a spark plug in the recess,
The inner wall of the cylinder head at the other end of the valley bottom facing the ignition plug is formed into a slope that becomes shallower toward the outer periphery, and in the compression stroke, the air-fuel mixture that advances toward the center along the slope is ignited along the valley bottom. In the compression stroke, the air-fuel mixture flows toward the ignition plug to improve ignition, and the long walls of the valley bottom are formed on both sides in front of the ignition plug to reduce the flame propagation distance. It is made longer to slow down the burning rate.

In addition, U.S. Patent No. 2843103, U.S. Pat.
Japanese Patent Publication No. 139684 describes a spark plug in which air-fuel mixture flows through the spark plug, but the cross section of these passages is not valley-shaped, and the
Publication No. 90805 describes a device that is provided with a passage through which the air-fuel mixture flows toward the ignition plug, but since the starting end of the passage closes into the main combustion chamber, these
This invention is significantly different from the present invention in the structure of the passage leading to the ignition plug.

This will be explained below with reference to the drawings. In the figure, numeral 1 is a cylinder, 2 is a piston, and the top of the piston 2 has a warhead-shaped peak 5 formed therein. 3 is a cylinder head, and 4 is a combustion chamber formed inside the cylinder head, which is configured so as to intersect two surfaces including an intake port 7 and an exhaust port 8 on the inner wall thereof, and by these surfaces. A valley bottom part 9 is formed, a narrow inner recess part 12 is provided at one end of the valley bottom part, and a spark plug 13 is mounted in the depth thereof, so that the electrode thereof is exposed to the valley part.

Then, the inner wall of the cylinder head at the other end of the valley bottom 9 facing the spark plug 13 is formed into a slope 6 that becomes shallower toward the outer periphery. It is designed to flow towards. On the other hand, the piston 2 is configured such that the slope 5a of the peak 5 at the top of the piston 2 approaches the slope 6 as much as possible at the top dead center, and the peak 5 has a recess as a relief so that the intake valve and the exhaust valve do not hit each other. 15 and 16 are provided.

Due to the structure of the piston top and the shape of the combustion chamber as described above, the inhaled fresh air tends to concentrate along the inner wall of the cylinder.

During the compression stroke, this fresh air is compressed by the piston 2 along the inner wall of the outer periphery of the combustion chamber, and moves toward the center at high speed, especially along the slope 6 on the opposite side of the spark plug 13, and along the valley bottom 9 as shown by the arrow. The flow converges toward the center as shown by a, flows toward the ignition plug 13, and gathers in the concave portion 12. Therefore, even a lean mixture can be ignited very well and ignited reliably. When the air-fuel mixture is ignited by the spark plug 13, the flame is blocked by the walls on both sides of the valley bottom 9 and cannot extend laterally. Since it extends forward and forward, it does not spread all at once, so the combustion speed is slowed down and the combustion time is sustained for a long time.

In this way, at the beginning of combustion, combustion takes place in the combustion chamber above the piston peak 5, and as the piston descends, the flame spreads to the space between the slope 5a and the slope 6 and the outer periphery of the peak 5. It extends into the space above the flat part 5b and completes combustion in the entire combustion chamber. Since combustion takes place in two stages,
The combustion time becomes longer, especially at part load, where the combustion rate slows down and the combustion time is sustained for a longer period of time. As is clear from the above description, according to the present invention, during compression, fresh air flows along the valley bottom toward the ignition plug and concentrates there, so that even a lean air-fuel mixture is reliably ignited. Furthermore, since there are long walls forming valley bottoms on both sides of the front of the ignition plug, this blocks the flame and prevents it from spreading at once, thus slowing down the initial combustion speed and prolonging the combustion time. ,
As a result, combustion becomes slow and the maximum combustion temperature becomes low.
This, together with the combustion of a lean mixture, can reduce the amount of N0x generated, and as a result, the amount of N0x generated can be sufficiently suppressed even without ignition retardation. . Therefore, since the ignition timing control device only needs to advance the ignition timing, the structure can be simplified, and since the ignition timing control device does not retard the ignition timing, both fuel efficiency, output, and drivability are improved.

Furthermore, these can be achieved simply by forming the combustion chamber shape as described above, and no other special equipment is required, so the structure is extremely simple.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main parts of the cylinder and cylinder head of an internal combustion engine to which the present invention is applied, and FIG. 2 is a cross-sectional view taken along A-A in FIG.
The arrow view and FIG. 3 are exploded perspective views showing the inside of the combustion chamber. 1...Cylinder, 2"""piston, 3...Cylinder head, 4...Combustion chamber, 5...Mountain part, 5a...
...Slope, 5b...Flat area, 6...
Inclined part, 7... Intake ○, 8... Exhaust port, 9
... Valley bottom, 10, 11 ... Bank, 12.
...Recessed portion, 13... Spark plug, 14...
...Wall, 15, 16... recess. 3 large figures of 1 figure and 3 figures

Claims (1)

[Claims] 1 The inner wall of the cylinder head is configured to intersect two surfaces including an intake valve and an exhaust valve, these surfaces form a valley bottom, a recess is provided at one end of the valley bottom, and an ignition is carried in the recess. The plug is attached, and the inner wall of the cylinder head at the other end of the valley bottom facing the spark plug is formed into a slope that becomes shallower toward the outer periphery, so that during the compression stroke, the air-fuel mixture moves toward the center along the slope. A combustion chamber of an internal combustion engine, characterized in that the combustion chamber is configured to flow along a valley bottom toward an ignition plug.