JP2006152825A - Combustion chamber of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve combustion speed by enhancing a tumble flow generated in a combustion chamber. <P>SOLUTION: In a combustion chamber 9 of an internal combustion engine 1 in which a tumble flow T1 descending on an exhaust valve 6 side of an internal combustion engine and ascending on an intake valve 5 side is generated, squish parts 20, 21 for generating squish in the combustion chamber 9 are provided to the intake valve side and the exhaust valve side respectively. While the whole of or a part of the squish part 20 on the intake valve side is inclined to the ascending direction side of the tumble flow T1, the squish part 21 on the exhaust valve side is horizontal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  In an internal combustion engine in which an ignition plug is arranged at the center of the top of the combustion chamber and fuel is injected into the combustion chamber, an ignition plug is used to ignite and burn the injected fuel well at low loads with a small amount of fuel injection. It is necessary to collect the injected fuel around.

Therefore, a concave groove that extends from the bottom of the fuel injection valve to the bottom of the spark plug is formed on the piston top surface, descends along the cylinder inner wall surface below the intake valve, and then changes the direction on the piston top surface to change the exhaust valve. A tumble flow rising downward is formed in the combustion chamber. As a result, a technique for directing the injected fuel around the spark plug is disclosed (for example, see Patent Document 1).
JP-A-10-54247 Japanese Patent Laid-Open No. 11-81930 Japanese Patent Laid-Open No. 11-336551

  In order to improve the combustion speed in the combustion chamber of the internal combustion engine, it is preferable to strengthen the swirl flow (tumble flow) generated in the combustion chamber. Further, squish is also generated in the combustion chamber by the reciprocating motion of the piston. However, depending on the direction of the squish, the tumble flow generated in the combustion chamber may be canceled out.

  In view of the above problems, an object of the present invention is to enhance the tumble flow generated in the combustion chamber and improve the combustion speed.

  In order to solve the above-described problems, the present invention provides a squish portion that generates squish in a combustion chamber in a combustion chamber of an internal combustion engine in which a tumble flow that descends on the exhaust valve side of the internal combustion engine and rises on the intake valve side is generated. It is provided on each of the intake valve side and the exhaust valve side, and all or a part of the intake valve side squish part is inclined toward the rising direction side of the tumble flow, and the exhaust valve side squish part is horizontal.

  In the combustion chamber of the internal combustion engine, a tumble flow (swirl flow) is generated by opening and closing of the intake valve, and the flow direction is a direction that descends on the exhaust valve side and rises on the intake valve side. The upward direction here is the direction in which the piston moves during compression in the internal combustion engine, and the downward direction is the opposite direction.

  In addition, squish is generated by the air-fuel mixture (air) pushed out by the squish portion by the compression operation of the piston of the internal combustion engine. At this time, in the internal combustion engine described above, a squish having the same directional component as the rising direction of the tumble flow is formed at the inclined portion of the squish portion on the intake valve side. This makes it possible to further increase the strength of the tumble flow. On the other hand, a squish is formed in the horizontal direction at the squish portion on the exhaust valve side. The horizontal direction here is a direction perpendicular to the reciprocating motion of the piston. Since the tumble flow flows in the downward direction on the exhaust valve side, the possibility of hindering the flow of the tumble flow is reduced by generating a squish in the horizontal direction.

  Accordingly, in the combustion chamber of the internal combustion engine, it is possible to enhance the tumble flow generated in the combustion chamber and improve the combustion speed.

  In the combustion chamber of the internal combustion engine, the diameter of the valve body of the intake valve of the internal combustion engine may be smaller than the diameter of the valve body of the exhaust valve. By doing so, it is possible to secure a wider area for forming the squish portion on the intake side, thereby contributing to the strengthening of the tumble flow.

  In the combustion chamber of the internal combustion engine up to the above, the exhaust valve side squish area may be narrower than the intake valve side squish area. By narrowing the squish part region on the exhaust valve side, the squish formed by the squish part becomes weak, so that the combustion gas generated in the combustion chamber can be discharged more smoothly.

  In order to solve the above-described problem, the present invention provides a squish section for generating squish in the combustion chamber in each of the intake valve side and the exhaust valve side in the combustion chamber of the internal combustion engine, and All or part of the intake valve side squish part is inclined upward, and the exhaust valve side squish part is also a combustion chamber of an internal combustion engine characterized by being horizontal. That is, by changing the direction of the squish generated by the squish portion on the intake valve side and the exhaust valve side, it contributes to the strengthening of the tumble flow generated in the combustion chamber, and the combustion speed can be improved.

  It is possible to enhance the tumble flow generated in the combustion chamber and improve the combustion speed.

  Here, an embodiment of a combustion chamber of an internal combustion engine according to the present invention will be described based on the drawings.

  FIG. 1 is a block diagram showing a schematic configuration of an internal combustion engine 1 to which the present invention is applied. The internal combustion engine 1 includes a fuel injection valve 10 capable of directly injecting fuel into the combustion chamber 9, and includes an ignition plug 3 at a substantially central portion of the top of the combustion chamber 9. The fuel injection valve 10 is provided in the cylinder head 11 on the intake valve 5 side.

  In the combustion chamber 9, the piston 4 reciprocates. Accordingly, in the internal combustion engine 1, the combustion chamber 9 is defined by the inner wall surfaces of the piston 4, the cylinder 2 and the cylinder head 11. In the internal combustion engine 1, the intake passage is connected to the combustion chamber 9 through the intake port 7. Similarly, in the internal combustion engine 1, the exhaust passage is connected to the combustion chamber 9 via the exhaust port 8. Here, an intake valve 5 is provided between the intake port 7 and the combustion chamber 9, and an exhaust valve 6 is provided between the exhaust port 8 and the combustion chamber 9. Although not shown, the internal combustion engine 1 is provided with a supercharger.

  Here, the details of the combustion chamber 9 will be described with reference to FIGS. 2 and 3. FIG. 2 is a cross-sectional view of the combustion chamber 9 including the line AA in FIG. 3 in the direction of the central axis of the piston 4. Here, a squish portion is provided between the piston 4 and the cylinder head 9 to generate squish in the combustion chamber 9. Specifically, a squish part 20 is provided on the intake valve 5 side, and a squish part 21 is provided on the exhaust valve 6 side. In the squish portion 20, a part of the squish portion 20 has a protruding shape to form the protruding portion 22. The protrusion 22 has a shape inclined along the inner wall surface on the cylinder head 11 side. On the other hand, the squish portion 21 is not provided with an inclined portion and is in a horizontal state.

  In the combustion chamber 9 configured as described above, a tumble flow T1 that is a swirling flow that descends on the exhaust valve 6 side and rises on the intake valve 5 side is formed mainly by opening and closing of the intake valve 5. As the strength of the tumble flow T1 increases, the combustion speed in the combustion chamber 9 is improved, and knocking can be suppressed.

  Here, the squish S <b> 1 generated in the squish portion 20 is formed in a direction along the inner wall surface of the cylinder head 11 due to the shape of the protrusion 22. That is, the direction in which the squish S1 flows is closer to the rising direction of the tumble flow T1. The squish S2 generated in the squish portion 21 is formed in the horizontal direction, and the direction does not oppose the descending direction of the tumble flow T1. Therefore, the strength of the tumble flow T1 can be further increased by the squish S1 and the squish S2.

  FIG. 3 is a schematic view of the top surface of the piston 4. In addition, 5a and 5b represented by dotted lines in the figure are valve bodies of the intake valve 5 and the exhaust valve 6, respectively. Here, the diameter of the valve body 5 a of the intake valve 5 is set smaller than the diameter of the valve body 6 a of the exhaust valve 6. By doing so, it is possible to reduce the area of the piston top surface that is secured for the valve recess of the intake valve 5, and as a result, the area of the squish part 20 is widened and the area for providing the protrusion 22 is ensured. Becomes easy. That is, by making the valve body 5a of the intake valve 5 smaller, it is possible to increase the strength of the squish S1 and thereby contribute to the strengthening of the tumble flow T1.

  Further, since the interference between the fuel injection valve 10 and the valve body 5a is reduced by making the valve body 5a of the intake valve 5 smaller, the installation position of the fuel injection valve 10 can be made closer to the center side of the cylinder 2. It becomes. As a result, installation of the fuel injection valve 10 above the squish part 20 is avoided, and the area of the squish part 20 can be ensured as wide as possible, so that the squish S1 is generated more strongly. It becomes possible.

  Although the amount of intake air introduced into the combustion chamber 9 is reduced by reducing the diameter of the valve body 5a of the intake valve 5, the boost pressure is increased by the turbocharger provided in the internal combustion engine 1. It is possible to compensate for a decrease in the intake air amount.

  Further, by setting the diameter of the valve body 5a of the intake valve 5 to be smaller than the diameter of the valve body 6a of the exhaust valve 6, as shown in FIG. 3, the region of the squish portion 21 on the exhaust valve 6 side becomes the intake valve 5 side. It becomes narrower than the region of the side squish part 20. Accordingly, the squish S2 on the exhaust valve 6 side is weaker than the squish S1 on the intake valve 5 side, and the combustion gas generated in the combustion chamber 9 can be discharged more smoothly.

It is a figure showing the schematic structure of the internal combustion engine which concerns on the Example of this invention. It is a figure which shows schematic structure of the combustion chamber of the internal combustion engine which concerns on the Example of this invention, and the airflow in a combustion chamber. It is a figure which shows the outline of the piston top surface in the internal combustion engine which concerns on the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Cylinder 3 ... Spark plug 4 ... Piston 5 ... Intake valve 5a ... Valve body 6 ... Exhaust valve 6a ... ..Valve body 9 ... Combustion chamber 10 ... Fuel injection valve 11 ... Cylinder head 20 ... Squish part (intake valve side)
21 ... Squish part (exhaust valve side)
22 ... Projection S1 ... Squish (intake valve side)
S2 ... ・ Squish (exhaust valve side)
T1 ... Tumble style

Claims (4)

In the combustion chamber of the internal combustion engine in which a tumble flow that descends on the exhaust valve side of the internal combustion engine and rises on the intake valve side is generated,
A squish part for generating squish in the combustion chamber is provided on each of the intake valve side and the exhaust valve side, and all or part of the intake valve side squish part is inclined toward the rising direction side of the tumble flow, A combustion chamber of an internal combustion engine, wherein the exhaust valve side squish portion is horizontal.   The combustion chamber of the internal combustion engine according to claim 1, wherein the diameter of the valve body of the intake valve of the internal combustion engine is smaller than the diameter of the valve body of the exhaust valve.   3. The combustion chamber of the internal combustion engine according to claim 1, wherein a squish portion region on the exhaust valve side is narrower than a squish portion region on the intake valve side.   In a combustion chamber of an internal combustion engine, a squish portion for generating a squish in the combustion chamber is provided on each of the intake valve side and the exhaust valve side, and all or a part of the intake valve side squish portion is inclined upward. In addition, the combustion chamber of the internal combustion engine, wherein the exhaust valve side squish portion is horizontal.

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