JP2019044704A - Combustion chamber of internal combustion engine - Google Patents

Abstract

To provide a combustion chamber of an internal combustion chamber which improves the flowability of air in the combustion chamber, and can reduce a cooling loss of combustion gas accompanied with an increase in a surface area of the combustion chamber.SOLUTION: A rib 14 is formed on a recessed portion 7 formed on a bottom surface 2a of a cylinder head 2, and the rib 14 is provided between an intake port 10 and an exhaust port 12 in a circumferential direction of a side wall 9 and projects out from the side wall 9 toward an axis 5L of a piston 5. If the rib 14 is cut by a plane parallel with the axis 5L of the piston 5, the rib 14 is formed in a chevron-shape having a top portion 14A of an intermediate portion between the intake port 10 and the exhaust port 12.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a combustion chamber of an internal combustion engine.

  In an internal combustion engine, a vertical vortex generated in a combustion chamber, a so-called tumble flow, can efficiently mix intake air and fuel, so that it is necessary to generate a vertical vortex efficiently.

  As a conventional internal combustion engine of this type, one described in Patent Document 1 is known. This internal combustion engine is provided with a guide wall that is in contact with both the opening of the intake port and the opening of the exhaust port formed in the ceiling of the combustion chamber.

  A recess is formed in a part of the guide wall so as to be recessed in a direction away from the center axis of the cylinder so as to increase the volume in the combustion chamber, and the inner surface of the recess has a lower end at the center of the cylinder rather than the upper end. Inclined away from the axis.

  In a plan view of the ceiling portion of the combustion chamber as viewed from the central axis direction of the cylinder, the recess is most greatly recessed on the side near the portion closest to the exhaust port in the opening of the intake port.

  As a result, the flow rate at the portion on the exhaust port side of the opening portion of the intake port where the flow velocity of the intake air becomes relatively high can be increased. In addition to this, it is possible to prevent the intake air flowing into the combustion chamber from colliding with the guide wall or the inner wall of the cylinder and disturbing the flow, thereby enhancing the tumble flow.

Japanese Patent Laid-Open No. 2015-194082

  However, in the conventional internal combustion engine, the air that reaches the inner wall of the cylinder along the side wall of the combustion chamber from the intake port swirls also in the circumferential direction of the cylinder, and passes along the ceiling wall of the combustion chamber from the intake port. It does not consider the interference with air reaching the inner wall of the cylinder.

  As a result, the flow resistance of air reaching the inner wall of the cylinder along the ceiling wall of the combustion chamber from the intake port increases, and there is a possibility that the tumble flow cannot be efficiently enhanced.

  In addition, the conventional internal combustion engine has a guide wall in contact with both the opening of the intake port and the opening of the exhaust port, and a part of the guide wall extends in a direction away from the center axis of the cylinder. A recess is formed to increase the volume of the combustion chamber. The inner surface of the recess is inclined such that the lower end is farther from the central axis of the cylinder than the upper end.

  This complicates the shape of the combustion chamber, increases the surface area of the combustion chamber, and may increase the cooling loss of the combustion gas.

  The present invention has been made paying attention to the above situation, and can improve the air fluidity in the combustion chamber and reduce the cooling loss of the combustion gas accompanying the increase in the surface area of the combustion chamber. An object of the present invention is to provide a combustion chamber.

  In the present invention, an upper space of a combustion chamber formed by a cylinder block having a cylinder in which a piston is reciprocated and a cylinder head attached to the cylinder block is constituted by a recess formed in the bottom surface of the cylinder head. The recess is formed on the bottom surface of the cylinder head, and has a ceiling wall in which a pair of intake ports and a pair of exhaust ports are opened, and a side wall formed around the ceiling wall, and the recess Further, a combustion chamber of an internal combustion engine in which a rib for guiding a part of air flowing into the combustion chamber from the intake port to the piston side is formed, and the rib is connected to the intake port in a circumferential direction of the side wall. The rib is provided between the exhaust port, protrudes from the side wall toward the axis of the piston, and the rib is cut along a plane parallel to the axis of the piston. , Characterized in that it is formed in a chevron shape having an apex in the middle portion between the intake port and the exhaust port.

  As described above, according to the present invention, the fluidity of air in the combustion chamber can be improved, and the cooling loss of the combustion gas accompanying the increase in the surface area of the combustion chamber can be reduced.

FIG. 1 is a view showing a combustion chamber of an internal combustion engine according to an embodiment of the present invention, and is a bottom view of a cylinder head. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is a view showing a combustion chamber of an internal combustion engine according to one embodiment of the present invention, and is an enlarged view of a recess. FIG. 4 is a view showing a combustion chamber of an internal combustion engine according to one embodiment of the present invention, and is an enlarged view of a recess around a rib. FIG. 5 is a cross-sectional view taken along arrow VV in FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. 8 is a cross-sectional view taken along arrow VIII-VIII in FIG. 9 is a cross-sectional view taken along arrow IX-IX in FIG. FIG. 10 is a diagram illustrating a combustion chamber of an internal combustion engine according to an embodiment of the present invention, and is a diagram illustrating a direction of air flowing through the combustion chamber when the engine is viewed from the side. FIG. 11 is a diagram illustrating a combustion chamber of an internal combustion engine according to an embodiment of the present invention, and is a diagram illustrating a direction of air flowing through the combustion chamber when the engine is viewed from above. FIG. 12 is a diagram showing the direction of air flowing through the combustion chamber when an engine with no ribs formed in the recesses is viewed from above. FIG. 13 is a diagram showing the direction of air flowing through the combustion chamber when an engine in which no rib is formed in the recess is viewed from the side.

A combustion chamber of an internal combustion engine according to an embodiment of the present invention has an upper space of a combustion chamber formed by a cylinder block having a cylinder in which a piston is reciprocated and a cylinder head attached to the cylinder block. A recess formed in the bottom surface of the cylinder head, the recess formed in the bottom surface of the cylinder head, and a side wall formed around the ceiling wall and a pair of air inlets and a pair of air outlets. A combustion chamber of an internal combustion engine in which a rib for guiding a part of the air flowing into the combustion chamber from the intake port to the piston side is formed in the recess. When the rib is cut along a plane parallel to the axis of the piston, the rib is located at the intermediate portion between the intake and the exhaust. Summit It is formed in a chevron shape having a.
Thereby, the fluidity | liquidity of the air in a combustion chamber can be improved, and the cooling loss of the combustion gas accompanying the increase in the surface area of a combustion chamber can be reduced.

Hereinafter, a combustion chamber of an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings.
1 to 13 are views showing a combustion chamber of an internal combustion engine according to an embodiment of the present invention. In FIGS. 1 to 13, those with arrows in the up / down / left / right directions indicate that when the cylinder arrangement direction is the left / right direction, the direction orthogonal to the cylinder arrangement direction is the front / rear direction, and the engine height is The vertical direction is the vertical direction.

First, the configuration will be described.
In FIG. 1, an engine 1 as an internal combustion engine includes a cylinder head 2 and a cylinder block 3 (see FIG. 2). In FIG. 2, a cylinder 4 is formed inside a cylinder block 3, and a piston 5 is provided inside the cylinder 4 so as to be capable of reciprocating.

  The piston 5 is connected to a crankshaft (not shown) via a connecting rod (not shown), and the reciprocating motion of the piston 5 is converted into a rotational motion of the crankshaft via the connecting rod.

  A combustion chamber 6 is formed in the cylinder head 2 and the cylinder block 3. The combustion chamber 6 is composed of a space surrounded by a recess 7 formed on the bottom surface 2 a of the cylinder head 2, an inner wall (cylinder bore) of the cylinder 4, and a top surface of the piston 5.

  As a result, the upper space of the combustion chamber 6 is constituted by the recess 7 formed in the bottom surface 2 a of the cylinder head 2. Although the engine 1 of the present embodiment is composed of a three-cylinder engine, the number of cylinders of the engine 1 is not limited to three.

  2 and 3, the recess 7 of the cylinder head 2 has a ceiling wall 8 formed on the bottom surface 2 a of the cylinder head 2 and a side wall 9 formed around the ceiling wall 8. That is, the side wall 9 extends in the height direction of the recess 7, and the recess 7 is recessed in a direction (upward) away from the piston 5 from the bottom surface 2 a of the cylinder head 2.

  The ceiling wall 8 has an intake side ceiling wall 11 in which a pair of intake ports 10 are opened and an exhaust side ceiling wall 13 in which a pair of exhaust ports 12 are opened. The intake side ceiling wall 11 and the exhaust side ceiling wall 13 are In addition, it is inclined so that the center side is higher than the outer edge side of the combustion chamber 6 in the direction orthogonal to the cylinder row.

  The intake port 10 constitutes an open end of an intake port 21 (see FIG. 2) formed in the cylinder head 2, and intake air flows into the combustion chamber 6 from the intake port 21 through the intake port 10. The exhaust port 12 constitutes an open end of an exhaust port 22 (see FIG. 2) formed in the cylinder head 2, and the exhaust gas combusted in the combustion chamber 6 is discharged to the exhaust port 22 through the exhaust port 12. The

  In FIG. 2, the side wall 9 is formed around the ceiling wall 8 and extends from the ceiling wall 8 toward the bottom surface 2 a of the cylinder head 2. In FIG. 3, the side wall 9 has an arcuate side wall 9 </ b> A formed in an arc shape so as to communicate between the intake port 10 and the exhaust port 12.

  A portion of the concave portion 7 that connects the arcuate side wall 9A, the edge portion 11a of the intake-side ceiling wall 11 in the direction in which the intake ports 10 are arranged, and the edge portion 13a of the exhaust-side ceiling wall 13 in the direction in which the exhaust ports 12 are arranged. Is formed with a curved surface 7A (see FIG. 4).

  A pair of ribs 14 is provided in the recess 7, and the ribs 14 guide a part of the air flowing from the intake port 10 to the combustion chamber 6 to the piston 5 side.

  4 and 5, the rib 14 is provided between the intake port 10 and the exhaust port 12 in the circumferential direction of the recess 7 on the curved surface 7A, and extends from the arcuate side wall 9A to the combustion chamber. 6 protrudes toward the axis 5L of the piston 5.

  When the rib 14 is cut along a plane along the axis 5L of the piston 5, the rib 14 has a chevron shape having a top portion 14A at an intermediate portion between the intake port 10 and the exhaust port 12, as shown in FIGS. Is formed.

  The top portion 14 </ b> A of the rib 14 is inclined so as to approach the ceiling wall 8 side (upward) from the side wall 9 toward the axis 5 </ b> L of the piston 5.

  3 and 4, when the rib 14 is viewed from the opening edge 7 a side of the recess 7, that is, when viewed from the bottom surface 2 a side of the cylinder head 2, the rib 14 includes the intake port 10, the exhaust port 12, and the like. Are formed in a sector shape having a side 14C on the inlet side and a side 14D on the exhaust side that individually connect the circumferential side 9c and the other 9d of the arcuate side wall 9A. Yes.

  The side 14C on the air inlet side is formed in a shape in which the distance from the air inlet 10 is increased from the apex 14B toward the arcuate side wall 9A. The side 14D on the exhaust port side is formed in a shape in which the distance between the exhaust port 12 becomes narrower than the distance between the intake port 10 and the side 14C on the intake port side from the apex 14B toward the arcuate side wall 9A. Yes.

  The cylinder head 2 is formed with a plug hole 2A into which a spark plug is inserted. The plug hole 2 </ b> A is located on the inner side in the circumferential direction with respect to the intake port 10 and the exhaust port 12.

Next, the operation will be described.
As shown in FIGS. 12 and 13, in the case of the engine 1 in which the rib 14 is not formed in the recess, the intake air flowing through the intake port 21 passes between the intake port 10 and the valve head 23 </ b> A of the intake valve 23 and is in the combustion chamber 6. Flow into.

  The air W1 flowing into the combustion chamber 6 between the intake port 10 and the valve head 23A flows along the intake-side ceiling wall 11 and the exhaust-side ceiling wall 13 toward the exhaust-side inner wall 4A of the cylinder 4; The air W2 is divided into air W2 that passes through the vicinity of the side wall 9 that is the side surface of the combustion chamber 6 and travels toward the inner wall 4A on the exhaust side of the cylinder 4.

  The air W <b> 1 and W <b> 2 is directed to the piston 5 side and becomes a tumble flow that swirls in the vertical direction by the movement of the piston 5.

  However, the air W2 also turns in the lateral direction along the curved surface of the inner wall 4A on the exhaust side of the cylinder 4 and interferes with the air W1 toward the inner wall 4A on the exhaust side (the interference portion in FIG. Show). For this reason, the flow velocity of the air W1 decreases, and the tumble flow generated by the air W1 may be attenuated.

  On the other hand, in the combustion chamber 6 of the engine 1 of this embodiment, a part of the air flowing into the combustion chamber 6 from the intake port 10 is directed to the piston 5 side in the recess 7 formed in the bottom surface 2a of the cylinder head 2. A guiding rib 14 is formed.

  The rib 14 is provided between the intake port 10 and the exhaust port 12 in the circumferential direction of the side wall 9, protrudes from the side wall 9 toward the axis 5 </ b> L of the piston 5, and the rib 14 is parallel to the axis 5 </ b> L of the piston 5. When cut in a plane, the ribs 14 are formed in a chevron shape having a top portion 14 </ b> A at an intermediate portion between the intake port 10 and the exhaust port 12.

  As a result, as shown in FIGS. 10 and 11, of the air that flows into the combustion chamber 6 through the space between the intake port 10 and the valve head 23 </ b> A, the air W <b> 3 that flows along the side wall 9 that is the side surface of the combustion chamber 6. Can collide with the side 14C (see FIG. 4) of the rib 14 on the inlet side.

  At this time, the flow of the air W3 flowing into the combustion chamber 6 is changed downward so that the air W3 can be directed to the piston 5 side before reaching the exhaust-side inner wall 4A of the cylinder 4.

  For this reason, the air W1 that flows into the combustion chamber 6 through the space between the intake port 10 and the valve head 23A and moves toward the exhaust-side inner wall 4A of the cylinder 4 along the intake-side ceiling wall 11 and the exhaust-side ceiling wall 13 is air. Interference with W3 can be prevented.

  Therefore, it is possible to prevent the tumble flow flowing in the center of the combustion chamber 6 (on the axis 5L side of the piston 5) from being attenuated, increase the amount of air flowing in the center of the combustion chamber 6, and strengthen the tumble flow.

  Further, since the rib 14 is formed in a chevron shape having a top portion 14A at the intermediate portion between the intake port 10 and the exhaust port 12, air colliding with the side 14C on the intake port side of the rib 14 is allowed to enter the air on the intake port side. It can be smoothly moved from the side 14C toward the apex 14A and the apex 14B. For this reason, it is possible to prevent the intake resistance from being increased by the rib 14.

  As a result, the mixing property of air and fuel in the combustion chamber 6 can be improved, and the combustion efficiency can be improved.

  Further, by forming the ribs 14 in a chevron shape, it is possible to suppress an increase in the surface area of the combustion chambers 6 due to the ribs 14 as compared with the case where the side walls of the combustion chambers 6 are entirely curved to adjust the air flow. For this reason, it can prevent that the cooling loss of combustion gas increases.

  Thus, according to the combustion chamber 6 of the engine 1 of the present embodiment, the fluidity of the air in the combustion chamber 6 can be improved and the cooling loss of the combustion gas accompanying the increase in the surface area of the combustion chamber 6 can be reduced.

  Further, by forming the rib 14 in the recess 7, the volume of the combustion chamber 6 can be reduced while suppressing an increase in the surface area of the combustion chamber 6. For this reason, a compression ratio can be raised and the output of the engine 1 can be increased.

  Further, according to the combustion chamber 6 of the engine 1 of the present embodiment, the side wall 9 has the arc-shaped side wall 9 </ b> A formed in an arc shape between the intake port 10 and the exhaust port 12.

  When the rib 14 is viewed from the opening edge 7a side of the concave portion 7, the rib 14 has an apex 14B located between the intake port 10 and the exhaust port 12, and one circumferential direction 9c and the other 9d of the arcuate side wall 9A. Are formed in a sector shape having a side 14C on the inlet side and a side 14D on the exhaust side.

  In addition, the side 14C on the inlet side is formed in a shape in which the distance from the inlet 10 increases from the apex 14B toward the arcuate side wall 9A.

  Thereby, it can prevent that the rib 14 becomes resistance with respect to the air which flows into the circumference | surroundings of the side wall 9 from the inlet port 10, ie, the curved surface 7A, and can prevent more effectively that intake resistance increases. As a result, the mixing property of air and fuel in the combustion chamber 6 can be improved more effectively.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

  DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 2 ... Cylinder head, 3 ... Cylinder block, 4 ... Cylinder, 5 ... Piston, 5L ... Axis of piston, 6 ... Combustion chamber 7 ... a recess, 7a ... an opening edge (opening edge of the recess), 8 ... a ceiling wall, 9A ... an arc-shaped side wall, 9c ... one of the circumferential directions of the arc-shaped side wall, 9d. ..The other in the circumferential direction of the arc-shaped side wall, 10 ... inlet, 12 ... exhaust, 14 ... rib, 14A ... top (rib top), 14B ... vertex, 14C. ..Inlet side, 14D ... Exhaust side

Claims (2)

An upper space of a combustion chamber formed by a cylinder block having a cylinder in which a piston is reciprocated and a cylinder head attached to the cylinder block is constituted by a recess formed on the bottom surface of the cylinder head,
The concave portion is formed on the bottom surface of the cylinder head, and has a ceiling wall in which a pair of intake ports and a pair of exhaust ports open, and a side wall formed around the ceiling wall,
A combustion chamber of an internal combustion engine, wherein a rib for guiding a part of air flowing into the combustion chamber from the intake port to the piston side is formed in the recess;
The rib is provided between the intake port and the exhaust port in the circumferential direction of the side wall, and protrudes from the side wall toward the axis of the piston,
When the rib is cut along a plane parallel to the axis of the piston, the rib is formed in a mountain shape having a top at an intermediate portion between the intake port and the exhaust port. Combustion chamber. The side wall has an arcuate side wall formed in an arc shape between the exhaust port and the intake port,
When the rib is viewed from the opening edge side of the recess, the rib individually communicates with the apex located between the intake port and the exhaust port, and one and the other in the circumferential direction of the arc-shaped side wall. It is formed in a fan shape with the side on the intake side and the side on the exhaust side,
2. The combustion chamber of the internal combustion engine according to claim 1, wherein the side on the intake port side is formed in a shape in which a distance from the intake port becomes wider from the apex toward the arcuate side wall.

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