JP2011074831A - Combustion chamber structure of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide combustion chamber structure of an internal combustion engine, which prevents the occurrence of preignition without reducing the projective degree of an ignition plug into a combustion chamber or increasing the cooling capacity of the internal combustion engine. <P>SOLUTION: A portion between intake ports 3b and a plug mounting hole 3a of a first inclined surface 3f is formed into a flat surface, and a wall surface 3g positioned between the plug mounting hole 3a and exhaust ports 3c and extending downward on the exhaust ports 3c side of the plug mounting hole 3a. The ignition plug 6 is cooled by mixed gas led to flow into the combustion chamber 5 during an intake stroke, and also the heating of the ignition plug 6 is prevented by the exhaust emissions in an exhaust stroke. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a combustion chamber structure of a spark ignition type internal combustion engine in which a mixed gas sucked into a combustion chamber is ignited by a spark plug.

  Conventionally, a combustion chamber structure of this type of internal combustion engine has a plug mounting hole for mounting a spark plug, a pair of intake ports opened and closed by an intake valve, and a pair of exhaust ports opened and closed by an exhaust valve. The plug mounting hole is provided at the center of the cylinder head side in the radial direction, each intake port is provided on one side of the plug mounting hole on the cylinder head side surface, and each exhaust port is provided on the cylinder head side surface. What was provided in the other side of the plug attachment hole is known (for example, refer to patent documents 1).

Japanese Utility Model Publication No. 62-190824

  In the combustion chamber of the internal combustion engine, when the temperature of the center electrode of the spark plug becomes high, a phenomenon called preignition occurs in which the mixed gas of fuel and air is ignited earlier than usual. In a situation where pre-ignition occurs continuously, the combustion chamber becomes hot and high in pressure, the piston ring burns in, and the intake / exhaust valve and spark plug melt, causing damage to the internal combustion engine.

  As a method for preventing pre-ignition, there is a method of reducing the amount of jumping of the spark plug into the combustion chamber or improving the cooling capacity of the internal combustion engine. However, when the fuel consumption rate of the internal combustion engine is reduced or cold There is a risk of starting failure.

  An object of the present invention is to provide a combustion chamber of an internal combustion engine that can prevent the occurrence of pre-ignition without reducing the amount of the spark plug protruding into the combustion chamber or increasing the cooling capacity of the internal combustion engine. To provide a structure.

  In order to achieve the above object, the present invention has a plug mounting hole for mounting a spark plug, a pair of intake ports opened and closed by an intake valve, and a pair of exhaust ports opened and closed by an exhaust valve, A plug mounting hole is provided in the center in the radial direction of the cylinder head side surface, each intake port is provided on one side of the plug mounting hole on the cylinder head side surface, and each exhaust port is mounted on the plug on the cylinder head side surface. In the combustion chamber structure of the internal combustion engine provided on the other side of the hole, the plug mounting located between the plug mounting hole and the exhaust port is formed with a smooth surface between each intake port and the plug mounting hole A wall surface extending toward the piston in the central axial direction of the cylinder is provided on the other side of the hole.

  As a result, the mixed gas flowing into the combustion chamber during the intake stroke flows along the smooth surface from between the intake ports to the plug mounting hole and is collected around the spark plug by the wall surface. The spark plug is cooled by the mixed gas flowing into the combustion chamber. Further, during the exhaust stroke, the exhaust gas staying around the spark plug makes it difficult for the exhaust gas flowing out from the combustion chamber to circulate around the spark plug, so the exhaust gas flowing out of the combustion chamber during the exhaust stroke Heating of the spark plug is prevented.

  According to the present invention, the spark plug can be cooled by the mixed gas flowing into the combustion chamber during the intake stroke, and the spark plug can be prevented from being heated by the exhaust gas during the exhaust stroke, so that pre-ignition can be prevented. There is no need to increase the cooling capacity of the internal combustion engine or adjust the pop-out amount of the spark plug, and the occurrence of pre-ignition can be reliably prevented.

Side surface sectional drawing of the combustion chamber which shows one Embodiment of this invention Bottom view of cylinder head Diagram showing the flow of mixed gas in the intake stroke Diagram showing the flow of mixed gas in the intake stroke Diagram showing the flow of exhaust gas in the exhaust stroke

  1 to 5 show an embodiment of the present invention. In the present embodiment, the upward direction in FIG. 1 is up, the downward direction in FIG. 1 is down, the right direction in FIG. 1 is right, the left direction in FIG. 1 is left, and the near direction in FIG. The back direction in FIG.

  An internal combustion engine having a combustion chamber structure according to the present invention includes a cylinder block 2 in which a cylinder 1 is formed, a cylinder head 3 provided on one end side of the cylinder 1, and a piston 4 provided movably in the cylinder 1. A pent roof type combustion chamber 5 is formed between the cylinder head 3 and the piston 4 in the cylinder 1.

  On the surface of the combustion chamber 5 on the cylinder head 3 side, a plug mounting hole 3a for mounting the spark plug 6, a pair of intake ports 3b opened and closed by the intake valve 7, and a pair of exhaust opened and closed by the exhaust valve 8 are provided. A mouth 3c is provided. The plug mounting hole 3a is provided at a substantially central portion in the radial direction of the cylinder 1, each intake port 3b is disposed on the left side of the plug mounting hole 3a, and the exhaust port 3c is positioned on the right side of the plug mounting hole 3a. Has been placed. An intake port 3d is connected to each intake port 3b, and an exhaust port 3e is connected to each exhaust port 3c.

  The surface of the combustion chamber 5 on the cylinder head 3 side includes a first inclined surface 3f extending slightly obliquely downward to the left from the substantially central portion in the left-right direction, and a wall surface 3g extending downward from the right end of the first inclined surface 3f. And a second inclined surface 3h extending slightly obliquely downward from the lower end of the wall surface 3g to the right side. The first inclined surface 3f is provided with plug attachment holes 3a and intake ports 3b, and the second inclined surface 3h is provided with exhaust ports 3c. A smooth surface is formed between each intake port 3b of the first inclined surface 3f and between the plug mounting hole 3a. Further, the wall surface 3g is located between the plug mounting hole 3a and each exhaust port 3c, surrounds the exhaust port 3c side of the plug mounting hole 3a, and both ends thereof extend to the left (each intake port 3b side). The distance in the front-rear direction inside the wall surface 3g is formed so as to increase from the plug mounting hole 3a toward the left side.

  In the combustion chamber of the internal combustion engine configured as described above, the mixed gas flowing into the combustion chamber 5 during the intake stroke is smooth from between the intake ports 3b to the plug mounting holes 3a as shown in FIG. It flows along the first inclined surface 3 f formed in a planar shape, flows downward in contact with the wall surface 3 g located on the exhaust port 3 c side of the plug mounting hole 3 a, and is collected around the spark plug 6. In addition, the wall surface 3g that surrounds the exhaust port 3c side of the plug mounting hole 3a and extends toward the intake port 3b has a smaller distance in the front-rear direction inside the wall surface 3g from the intake port 3b side toward the plug mounting hole 3a. As shown in FIG. 4, the mixed gas is guided in the front-rear direction and collected around the spark plug 6. As a result, the spark plug 6 is cooled by the mixed gas flowing into the combustion chamber 5 during the intake stroke.

  Further, as shown in FIG. 5, the exhaust gas flowing out from the combustion chamber 5 during the exhaust stroke circulates around the spark plug 6 as the exhaust gas stays around the spark plug 6 surrounded by the wall surface 3g. Therefore, the ignition plug 6 is prevented from being heated by the exhaust gas.

  Thus, according to the combustion chamber structure of the internal combustion engine of the present embodiment, the space between the intake ports 3b of the first inclined surface 3f and the plug mounting hole 3a is formed into a smooth surface, and the plug mounting hole 3a is formed. Since the wall surface 3g extending downward is provided on the exhaust port 3c side of the plug mounting hole 3a located between the exhaust port 3c and the exhaust port 3c, the ignition plug 6 is cooled by the mixed gas flowing into the combustion chamber 5 during the intake stroke. At the same time, it is possible to prevent the ignition plug 6 from being heated by the exhaust gas in the exhaust stroke, and it is not necessary to increase the cooling capacity of the internal combustion engine or adjust the pop-out amount of the ignition plug 6 in order to prevent preignition. The occurrence of pre-ignition can be surely prevented.

  In addition, since a smooth surface is formed between each of the intake ports 3b and the plug mounting hole 3a of the first inclined surface 3f, a reference surface for the height of the head combustion chamber is separately formed on the surface on the cylinder head 3 side. Without any problem, the plug mounting hole 3b side of the first inclined surface can be used as a reference for the height of the head combustion chamber, and the cylinder head 3 side surface can be formed symmetrically about the left-right direction. .

  Further, the wall surface 3g is formed so as to surround the exhaust port 3c side of the plug mounting hole 3a and both end portions extend to the respective intake ports 3b side, and the interval in the front-rear direction inside the wall surface 3g extending to each intake port 3b side Is formed so as to increase from the plug mounting hole 3a toward the intake port 3b, so that the mixed gas flowing into the combustion chamber 5 from the intake port 3b is guided toward the ignition plug 6 in the front-rear direction by the wall surface 3g. As a result, the spark plugs 6 can be collected around the spark plug 6, and the spark plug 6 can be cooled more reliably during the intake stroke.

  Further, since each exhaust port 3c is provided on the second inclined surface 3h extending rightward from the lower end of the wall surface 3g, the exhaust gas is smoothly circulated along the second inclined surface 3h extending from the lower end of the wall surface 3g in the exhaust stroke. It is possible to more reliably prevent the ignition plug 6 from being heated during the exhaust stroke.

  DESCRIPTION OF SYMBOLS 1 ... Cylinder, 3 ... Cylinder head, 3a ... Plug attachment hole, 3b ... Intake port, 3c ... Exhaust port, 3f ... 1st inclined surface, 3g ... Wall surface, 3h ... 2nd inclined surface, 4 ... Piston, 5 ... Combustion Chamber, 6 ... spark plug, 7 ... intake valve, 8 ... exhaust valve.

Claims (3)

It has a plug mounting hole for mounting a spark plug, a pair of intake ports that are opened and closed by an intake valve, and a pair of exhaust ports that are opened and closed by an exhaust valve. The plug mounting hole is in the radial direction of the cylinder head side surface. Combustion of an internal combustion engine provided in the center, each intake port is provided on one side of the plug mounting hole on the surface on the cylinder head side, and each exhaust port is provided on the other side of the plug mounting hole on the surface on the cylinder head side In the room structure,
A smooth surface is formed between each air inlet and the plug mounting hole.
A combustion chamber structure for an internal combustion engine, characterized in that a wall surface extending toward the piston in the central axial direction of the cylinder is provided on the other side of the plug mounting hole located between the plug mounting hole and the exhaust port. The wall surface is formed so as to surround the exhaust port side of the plug mounting hole and both end portions extend to each intake port side, and the interval inside the wall surface extending to each intake port side extends from the plug mounting hole to the intake port side. The combustion chamber structure for an internal combustion engine according to claim 1, wherein the combustion chamber structure is formed to be large. The combustion chamber structure of the internal combustion engine according to claim 1 or 2, wherein each of the exhaust ports is provided on a surface extending from the end of the cylinder in the central axis direction piston side to the other side of the wall surface.

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