JPH0583328U - Internal combustion engine combustion chamber structure - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the lean burn limit in a multi-valve internal combustion engine in which a plurality of intake ports are arranged in parallel on one side of an upper wall surface of a combustion chamber. A spark plug 9 is arranged substantially in the center of the upper wall surface of the combustion chamber 5, and squish areas 6 and 17 are provided at one end peripheral edge and the other peripheral edge of the upper end of the combustion chamber 5 on the intake port 6 side, respectively. The squish flow 18 from the squish area 16 on one side is jetted along the upper wall surface of the combustion chamber 5, and the squish flow 19 from the squish area 17 on the other side is jetted along the top surface of the piston 4. , The combustion chamber 5 with the squish flows 18 and 19 even at the end of the compression process.
A vertical swirl flow is left inside, fuel is collected on the swirl flow in the center of the combustion chamber 5, and ignition is improved by igniting with a spark plug 9 arranged in the center,
As a whole, it enables combustion with a lean air-fuel mixture.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a combustion chamber structure for an internal combustion engine, and more particularly to a combustion chamber structure for improving a lean burn limit in a multi-valve internal combustion engine having a plurality of intake valves.

[0002]

[Prior Art]

 For example, as disclosed in Japanese Patent Laid-Open No. 59-158319 and Japanese Utility Model Laid-Open No. 57-31531, the top surface of the piston in a multi-valve internal combustion engine having a pair of intake valves and a pair of exhaust valves. A squish area is provided between the squish area and the inner wall surface of the cylinder head to eject a squish flow from the squish area at the end of the compression process to generate turbulence in the combustion chamber, thereby increasing the flame propagation speed and suppressing knocking. Such a method is conventionally known.

Further, in the multi-valve internal combustion engine, as shown in FIG. 4, a pair of intake ports 21 are provided in the combustion chamber 20 so as to form a pair of vertical vortices (tumbles), and intake air on the lower surface of the cylinder head 22 is provided. Flat portions 23 and 24 are provided on the peripheral portions of the port side and the exhaust port side to generate a squish flow 26 between the flat surface of the piston 25 and the top surface of the flat piston 25 at the end of the compression process. It is known to have a combustion chamber structure that is converted into various turbulence to improve combustion.

[0004]

[Problems to be solved by the device]

 By the way, there is known a method of using a lean air-fuel mixture to improve fuel efficiency, but in the combustion chamber structure of a multi-valve internal combustion engine as shown in FIG. 4, rapid combustion is caused by turbulence formed by the squish flow 26. Even if it can be realized, there is a problem that the lean combustion limit cannot be significantly improved because the air-fuel mixture distribution in the combustion chamber 20 is homogenized.

The present invention has been made in view of such conventional problems, and an object thereof is to provide a combustion chamber structure of an internal combustion engine capable of improving a lean burn limit in a multi-valve internal combustion engine.

[0006]

[Means for Solving the Problems]

 The combustion chamber structure of the internal combustion engine of the present invention is a combustion chamber structure of an internal combustion engine in which a plurality of intake ports are arranged in parallel on one side of the upper wall surface of the combustion chamber. The squish area is located at the center of the squish area on the upper and lower edges of the combustion chamber, and the squish flow from the squish area on one side is jetted out along the upper wall of the combustion chamber and on the other side. The squish flow from the squish area is characterized by being ejected along the top surface of the piston.

[0007]

[Action]

 According to the present invention, at the end of the compression process, the squish flow is ejected from the squish area on one side of the intake port and the squish area on the other side along the upper wall surface of the combustion chamber and the top surface of the piston, respectively. Vertical swirl flow remains in the combustion chamber at the end of the compression process in order to prevent the vertical vortices formed in the combustion chamber by the intake air from the ports from collapsing at the end of the compression process and to promote this. As a result, the fuel rides on the swirling flow and gathers in the center of the combustion chamber, and the air-fuel mixture in the central portion becomes richer.Ignition is good because the ignition plug located in the central portion ignites, and as a whole, Combustion with a lean mixture is possible, and the lean burn limit can be greatly improved.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, 1 is a cylinder block and 2 is a cylinder head. A piston 4 is slidably fitted in a cylinder bore 3 formed in the cylinder block 1, and combustion is performed in a space surrounded by the peripheral wall surface of the cylinder bore 3, the top surface of the piston 4 and the bottom surface of the cylinder head 2. Chamber 5 is constructed. As shown in FIG. 2, on the upper wall surface of the combustion chamber 5, that is, on the surface of the cylinder head 2 facing the combustion chamber 5, a pair of intake ports 6 are formed in parallel on one side and on the other side. A pair of exhaust ports 7 are formed in parallel with each other, and a mounting hole 8 for a spark plug 9 is formed at a substantially central portion. The upper wall surface of the combustion chamber 5 inclines upward from one end on the intake port 6 side toward the central part, and inclines downward from the central part toward the appropriate distance from the other end toward the center. Moreover, it is inclined upward from that position toward the other side end, and is connected to the vertical cylindrical surface at the other side end, and there are a mountain-shaped recess 10 sandwiching the central part and a triangular recess 11 at the other side end. Has been formed.

On the other hand, at the top of the piston 4, as shown in FIG. 3, the one end on the intake port 6 side is inclined upward toward the center corresponding to the skirt of the chevron-shaped recess 10. An inclined protrusion 12 is formed, and an inclined protrusion 13 that inclines upward toward the other end is formed at the other side end corresponding to the triangular concave portion 11. Further, these inclined protrusions 12, A concave curved surface 14 that is recessed downward from the top of the inclined projection 12 and is smoothly connected to the inclined surface of the inclined projection 13 is formed on the top surface of the piston 13, and a curved concave portion 15 is formed on the top surface of the piston 4. Are formed. Thus, when the piston 4 is at the top dead center, the combustion chamber 5 is formed between the chevron-shaped recess 10 of the cylinder head 2 and the curved recess 15 on the top surface of the piston 4, and one side end thereof is formed. The squish area 16 on the suction side is formed by the skirt of the recess 10 and the inclined projection 12, and the squish area 17 on the exhaust side is formed by the triangular recess 11 and the inclined projection 13 at the other end. It Thus, as shown by the arrow in FIG. 1, the squish flow 18 from the squish area 16 on the intake side is jetted along the upper wall surface of the combustion chamber 5, and the squish flow 19 from the squish area 17 on the exhaust side is the piston. It is jetted along the top surface composed of the concave curved surface 14 of 4.

In the above-described structure, the air-fuel mixture sucked into the combustion chamber 5 from the pair of intake ports 6 in the intake stroke forms vertical vortices, and when the compression stroke is next performed, the vertical vortices are vertically compressed. At the end of the piston 4 approaching the top dead center, the longitudinal vortices tend to be crushed, but in the present embodiment, the squish flow 18 from the squish area 16 on the intake side and the squish area 17 on the exhaust side are Since the squish flow 19 of each jets out along the upper wall surface of the combustion chamber 5 and the top surface of the piston, the vertical vortices in the combustion chamber are accelerated and promoted by these squish flows 18 and 19, and at the end of the compression process. Also, a vertical swirl flow remains in the combustion chamber 5. As a result, the fuel in the sucked air-fuel mixture rides on the swirling flow and gathers in the center of the combustion chamber 5, so that the air-fuel mixture becomes rich in the center of the combustion chamber 5. Further, since the air-fuel mixture is ignited by the spark plug 7 arranged in the center portion, the ignitability is good, and once the air-fuel mixture is ignited, the turbulence of the air-fuel mixture is large, so that rapid combustion can be achieved even with a slightly thin air-fuel mixture. Thus, even if the intake air-fuel mixture is thin as a whole, combustion is possible, and the lean burn limit can be greatly improved, thus improving fuel efficiency.

[0012]

[Effect of the device]

 According to the combustion chamber structure of the internal combustion engine of the present invention, at the end of the compression process, the squish flow flows from the squish area on one side of the intake port and the squish area on the other side along the upper wall surface of the combustion chamber and the top surface of the piston, respectively. The vertical vortices formed in the combustion chamber are prevented from collapsing at the end of the compression process due to the intake air from the intake port, and this is promoted, and combustion is performed at the end of the compression process. Since a vertical swirl flow remains in the chamber, the fuel rides on the swirl flow and gathers in the center of the combustion chamber, and the air-fuel mixture in the central part becomes thicker, and the ignition plug located in the central part improves the ignitability. As a whole, combustion with a lean air-fuel mixture is possible, the lean combustion limit can be greatly improved, and fuel consumption can be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of an embodiment of a combustion chamber structure of an internal combustion engine of the present invention.

2A and 2B show a cylinder head of the embodiment, FIG. 2A is a vertical sectional view, FIG. 2B is a bottom view, and FIG. 2C is a sectional view taken along line AA of FIG.

FIG. 3 shows the piston of the embodiment, (a) is a plan view,
(B) is a longitudinal cross-sectional view, (c) is a BB cross-sectional view of (a).

FIG. 4 is a vertical cross-sectional view of a main part of a combustion chamber structure of an internal combustion engine of a conventional example.

[Explanation of symbols]

 4 Piston 5 Combustion chamber 9 Spark plug 16 Intake side squish area 17 Exhaust side squish area 18 Squish flow 19 Squish flow

Claims (1)

[Scope of utility model registration request] 1. In a combustion chamber structure of an internal combustion engine in which a plurality of intake ports are arranged in parallel on one side of an upper wall surface of the combustion chamber, an ignition plug is arranged substantially at the center of the upper wall surface of the combustion chamber,
A squish area is provided on the one side peripheral edge and the other side peripheral edge of the upper end of the combustion chamber, and the squish flow from the one side squish area is ejected along the upper wall surface of the combustion chamber.
A squish flow from the squish area on the other side is configured to be ejected along the top surface of the piston, which is a combustion chamber structure of an internal combustion engine.