JP2000282865A - Swirl generating mechanism due to level difference of combustion chamber in internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate swirls in an combustion chamber in order to enhance the combustion by controlling a jet stream, which are generated through the vertical motion of a piston with the use of a groove cut in between a level differences formed by notching the upper end of the piston and a ring-like level difference overhanging from the upper end of the combustion chamber. SOLUTION: In a swirl generating mechanism, the outer periphery of the upper end of a piston 1 is notched so as to form a ring-like level difference. Meanwhile, on the combustion chamber side, as shown in a part A of a cylinder head 2 or in a part B in a cylinder 3, a ring-like level difference is formed, overhanging into the combustion chamber. A surface, where the level difference of the piston 1 and the level difference of the combustion chamber overlap with each other, is formed therein the gap with a groove 4 carved in it, through which a jet stream is generated and the direction there of is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating piston internal combustion engine for use in automobiles and the like, which generates a vortex in a combustion chamber to improve combustion.

[0002]

2. Description of the Related Art Conventionally, in order to generate a vortex in a combustion chamber, a method of generating a vortex in an intake system, such as closing one side of an intake passage, has been adopted.

[0003]

In the method of generating a vortex in the intake system, the vortex is attenuated in the compression stroke, the volume efficiency is reduced by the resistance of the intake system, the cost of the variable intake mechanism is high, and the vortex control is high. Is difficult.

[0004]

The structure of the present invention is shown in FIG.
Next, a state diagram in which a combustion chamber divided into two parts and a piston are combined will be described. As shown in the piston 1 of FIG. 1, the outer periphery of the upper end of the piston is cut out in a ring shape to form a step, and a groove 4 for controlling the direction of the jet is formed in the outer periphery of the step. As shown in part A of the cylinder head 2 or part B of the cylinder 3 in FIG. 1, a step is formed to project the upper end of the combustion chamber inward in a ring shape, and a groove 4 for controlling the direction of the jet flow is formed on the inner periphery of the step. Engrave The overhang of this step is
A side may be the cylinder head 2 side, or B side may be the cylinder 3 side. From the outer diameter of the upper step of the piston,
A gap is created between the steps by slightly increasing the inner diameter of the step inside the upper combustion chamber, and a jet is generated from the gap by the vertical movement of the piston. The position where the groove 4 for controlling the direction of the jet is formed may be on the piston side, the combustion chamber side, or both.

[0005]

The operation of generating a jet by a step will be described with reference to FIG. As shown in the left figure, when the piston 1 rises to near the top dead center and the upper part of the piston step and the lower part of the combustion chamber overlap, a space C is formed between these steps. The space C becomes narrower as the piston rises. Therefore, the air in the space is vigorously discharged from the narrow gap D between the piston step and the combustion chamber step into the combustion chamber, where a jet is generated. Conversely, when piston 1 descends from top dead center as shown in the right figure,
The space C between the steps expands, and a flow of sucking air in the combustion chamber into the space C between the steps occurs. The operation of the present invention in each stroke in a four-stroke engine will be described with reference to FIGS. As shown in the intake stroke in FIG. 3, at the beginning of the intake in the left diagram, air is sucked from the intake valve, and a flow due to the suction of the step space is generated in the combustion chamber. Further, when the intake stroke advances and reaches the state shown in the right figure, the intake air is spread to the outer periphery in the combustion chamber by the flow caused by the intake of the step space,
It is agitated by the vortex generated by the step grooves. As shown in the compression stroke in FIG. 4, in the latter half of the compression stroke on the left, vortex is generated by the ejection of air from the step space, and the combustion chamber is stirred. At the end of the compression stroke on the right, the vortex is strongest and promotes combustion. Further, knocking is reduced due to the end gas cooling effect of the jet (squish flow) at this time. As shown in Fig. 5 ignition expansion stroke, in the ignition stroke on the left, knocking occurs because the diameter of the combustion chamber is small, compact, the flame propagation distance is short, and combustion is completed in a short time due to the step of the piston. It becomes difficult to do. This compact combustion chamber continues until the beginning of the expansion stroke as shown in the right figure. Further, in the expansion stroke on the right, the rise of the end gas pressure immediately after ignition is suppressed by the suction force of the air in the step space around the combustion chamber due to the lowering of the piston, and the occurrence of knocking due to self-ignition of the end gas is reduced. Furthermore, when the pressure in the combustion chamber becomes highest immediately after ignition, the space created by the step between the piston and the combustion chamber becomes
To function as a labyrinth packing by a combination of a narrow gap and a wide gap between the combustion chamber and the crank chamber. Further, a synergistic effect with a decrease in the internal pressure due to the lowering of the piston in the step space improves the sealing performance between the piston and the cylinder, so that blow-by gas flowing from the combustion chamber to the crank chamber is reduced. As shown in the exhaust stroke in FIG. 6, in the latter half of the exhaust in the left diagram, a jet flow is generated from the step space,
In the state shown in the right figure, the exhaust gas from the combustion chamber is exhausted to every corner by the jet. The operation of controlling the direction of the jet by the groove of the step gap will be described with reference to FIGS. As shown in FIG. 7, when the grooves are obliquely formed at the steps at equal intervals, a lateral vortex (swirl flow) is generated in the jet flow from the grooves. As shown in FIG. 8, when the grooves are concentrated on a part of the step and are vertically formed, a vertical vortex (tumble flow) is generated by the jet flow from the grooves. As shown in FIG. 9, when the grooves are concentrated on a part of the step and formed obliquely, a vortex in an oblique direction is generated by the jet from the grooves. As described above, the direction of the vortex to be generated can be freely controlled by changing the notch and the position of the groove.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a gasoline engine, stable combustion can be performed even in lean combustion by generating a vortex in a combustion chamber. In a diesel engine, by generating a vortex in the combustion chamber, it is possible to increase the ignition speed and complete combustion to suppress the generation of black smoke.

[0007]

In a gasoline engine, the vortex in the combustion chamber becomes strongest immediately before ignition, and stable combustion can be performed even in lean combustion. In addition, knocking caused by spontaneous ignition of end gas can be reduced by the effects of rapid combustion by a compact combustion chamber having a short flame propagation distance, a cooling effect by squish gas flow, a pressure drop around the combustion chamber due to suction of a stepped space, and the like. In a diesel engine, fuel is injected directly into the combustion chamber immediately before ignition.Therefore, the fuel and air are not sufficiently mixed, and black smoke is likely to be generated due to incomplete combustion. Since the air is agitated, combustion is promoted and generation of black smoke is suppressed. The blow-by gas is reduced by the labyrinth structure by the step, so that HC generation and deterioration of the lubricating oil are suppressed. It can be adopted at low cost with a simple structure that simply changes the shape of the piston and combustion chamber. Since the inflow resistance of the air does not increase in the intake system, much air can be taken in and the volume efficiency is good. The gas flow between the exhaust and fresh air is improved by the air flow around the combustion chamber due to the intake and exhaust of the step space in the intake and exhaust process. The strength and direction of the vortex can be freely controlled by setting the volume of the step space, the width of the step gap, the position and direction of the step groove.

[Brief description of the drawings]

FIG. 1 is a view showing the shapes of a combustion chamber and a piston according to the present invention, showing a state where a piston is combined in a combustion chamber divided into two parts.

FIG. 2 is a cross-sectional view in which the step space is enlarged in order to explain the jet flow generation action of the step space according to the present invention.

FIG. 3 is a view showing an operation in an intake stroke of the present invention.

FIG. 4 is a view showing an operation in a compression stroke of the present invention.

FIG. 5 is a view showing the operation of the present invention in the ignition expansion stroke.

FIG. 6 is a view showing an operation in an exhaust stroke of the present invention.

FIG. 7 is a view showing a shape of a groove for generating a lateral vortex.

FIG. 8 is a drawing showing a shape of a groove for generating a vertical vortex.

FIG. 9 is a view showing a shape of a groove for generating a diagonal vortex.

[Explanation of symbols]

 1 is a piston 2 is a cylinder head 3 is a cylinder 4 is a groove 5 is a piston pin 6 is a connecting rod A is a step overhang attached to the cylinder head side B is a step overhang attached to the cylinder side C is a step space D is a step gap

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[Procedure amendment]

[Submission date] June 26, 1999 (1999.6.2
6)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

FIG. 3

FIG. 4

FIG. 5

FIG. 6

FIG. 7

FIG. 8

FIG. 9

Claims (2)

[Claims] In a reciprocating piston internal combustion engine, a step structure is provided in which an upper end of a piston is cut out in a ring shape and an upper end of a combustion chamber is extended in a ring shape. , A mechanism to generate eddy currents in the combustion chamber and promote combustion 2. The step structure according to claim 1, wherein a groove is formed in a passage in which the jet flow is generated, and the flow direction of the jet flow is changed by the groove.
Mechanism to control eddy current