JPH0430341Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to an intake system for an internal combustion engine.

[Conventional technology]

In order to generate a strong swirling flow around the cylinder axis in the combustion chamber during low-load engine operation, and to ensure high charging efficiency during high-load engine operation, the helical intake port protrudes from one side to the other side and is designed to provide intake air. A partition wall extending from immediately upstream of the valve toward the upstream side of the helical-type intake port is formed within the helical-type intake port, and the protruding tip edge of the partition wall is placed with a gap from the other side of the above-mentioned intake port, and this partition wall forms a helical-type intake port. An internal combustion engine is known in which the inside of an intake port is divided into an upper passage and a lower passage, and an intake control valve that is fully opened during engine high load operation is provided in the lower passage (see Japanese Utility Model Application Publication No. 150945/1983). In this internal combustion engine, most of the intake air flows into the upper passage by closing the intake control valve during low-load engine operation, and then this intake air is combusted while swirling in the spiral part of the helical intake passage. Since it flows into the chamber, a strong swirling flow around the cylinder axis is generated in the combustion chamber.

[Problem that the invention attempts to solve]

However, when a swirling flow around the cylinder axis is generated in the combustion chamber, fuel droplets in the mixture supplied into the combustion chamber gather around the combustion chamber due to centrifugal force and adhere to the inner circumferential wall of the cylinder. The adhering fuel remains in the annular gap between the top land of the piston and the inner circumferential wall of the cylinder, that is, the piston clevis. However, since the piston clevis is a quench area and cannot be reached by the flame, the fuel accumulated in the piston clevis is discharged from the combustion chamber as unburned HC. There is a problem in that unburned HC is discharged into the engine exhaust system. Further, in the above-mentioned internal combustion engine, since the intake port is formed in a helical shape, the flow resistance is large, and thus there is a problem that high charging efficiency cannot be obtained when the engine is operated under high load.

[Means to solve the problem]

According to the present invention, in order to solve the above problems,
The intake port includes a first intake valve and a second intake valve, and the intake port is a straight port that extends from the intake port inlet in a substantially horizontal direction and then gradually curves downward toward the first intake valve. A partition is formed in the intake port that protrudes from one side surface toward the other side surface and extends from around the first intake valve stem toward the upstream side of the intake port, and the protruding tip edge of the partition wall is arranged at a distance from the other side surface of the intake port. At the same time, the partition wall divides the inside of the intake port into an upper passage and a lower passage.
An intake control valve that is divided and fully opened during high engine load operation is provided in the lower passage, and a second intake valve is arranged in the lower passage downstream of the intake control valve.

〔Example〕

1 and 2, 1 is a cylinder block, 2 is a piston, 3 is a cylinder head, 4 is a combustion chamber, 5 is a first intake valve, and 6 is a second intake valve having a smaller diameter than the first intake valve 5. An intake valve 7 indicates an exhaust valve, and 8 indicates an intake port common to the first intake valve 5 and the second intake valve 6. The intake port 8 as a whole consists of a straight port that extends in a substantially horizontal direction from the intake port inlet part 9 and then gradually curves downward toward the first intake valve 5. The width of the intake port 8 from the second intake valve 6 to the first intake valve 5 is wider than the width from the second intake valve 6 to the first intake valve 5.

As shown in FIGS. 1 to 5, a partition wall 10 projects from an intermediate height position of one side surface 8a of the intake port 8 toward the other side surface 8b of the intake port 8. As shown in FIGS. This partition wall 10 extends from around the stem 5a of the first intake valve 5 to the intake port inlet portion 9, and the protruding tip edge 11 of the partition wall 10 is spaced apart from the other side surface 8b of the intake port over its entire length. . This partition wall 10
As a result, the inside of the intake port 8 is divided into an upper passage 12 located above the partition wall 10 and a lower passage 13 located below the partition wall 10. As shown in FIG. 3, a partition wall 10
However, as can be seen from FIGS. 2, 4, and 5, the root portion 14 of the partition wall 10 rises as it approaches the first intake valve 5, and the protruding tip edge 11 of the partition wall 10 As it approaches the first intake valve 5, it descends slightly. Therefore, the angle of inclination in the cross section of the partition wall 10 becomes gradually steeper as it approaches the first intake valve 5. As shown in FIG. 2, the upper inner wall 15 of the second intake valve 6 is curved, and this curved inner wall 15 smoothly connects to the lower wall surface of the partition wall 10.

An intake control valve 16 is arranged at the entrance of the lower passage 13, and the intake control valve 16 is connected to an actuator 18 via a link mechanism 17. The intake control valve 16 is closed by the actuator 18 as shown by the solid line in FIG. 2 when the engine is operating at a low to medium load, and is fully opened as shown by the broken line in FIG. 2 when the engine is operating at a high load. Actuator 18 can thus be formed from a negative pressure diaphragm device that connects a negative pressure diaphragm chamber into intake port 8 . A fuel injection valve 19 is arranged on the upper wall surface of the intake port 8, and fuel is injected from the fuel injection valve 19 into the upper passage 12.

As described above, the intake control valve 16 is closed when the engine is operating at a low to medium load. At this time, most of the intake air is sent into the upper passage 12. Fuel is injected into this intake air, and the air-fuel mixture thus formed travels along the upper wall surface of the intake port 8, then changes direction downward along the curved upper wall surface above the first intake valve 5, and then turns downward along the curved upper wall surface above the first intake valve 5. As shown by K, it flows downward into the periphery of the combustion chamber 4. In addition, the broken line 2'
indicates when the piston 2 has descended. The air-fuel mixture that has entered the combustion chamber 4 collides with the top surface of the piston 2 and changes direction, thus generating a swirling flow around the horizontal axis within the combustion chamber 4. Therefore, the fuel particles contained in the air-fuel mixture adhere to the top surface of the piston 2 due to inertial force or centrifugal force. However, since this adhering fuel is combusted, it does not become unburned HC, and thus the amount of unburned HC discharged can be reduced. Note that, as shown in FIGS. 1 and 2, the second intake valve 6 is arranged in the lower passage 13 downstream of the intake control valve 16. Therefore, when the intake control valve 16 is closed, the intake control valve 1
6 prevents intake air from flowing into the lower passage 13, the intake air does not flow much into the combustion chamber 4 through the second intake valve 6, and most of the intake air flows into the upper passage 12. The air flows into the combustion chamber 4 from the first intake valve 5 through the first intake valve 5 . Further, since the root portion 14 of the partition wall 10 is gradually raised toward the first intake valve 5, the mixed air flow flowing in the upper passage 12 is collected on the upper wall surface of the intake port 8 and its speed is increased. Therefore, a large amount of air-fuel mixture flows into the combustion chamber 4 at a high velocity as shown by arrow K, so that a strong swirling flow is generated within the combustion chamber 4.

On the other hand, during high-load engine operation, the intake control valve 16 is fully opened, so that intake air also flows in from the lower passage 13. The intake air that has flowed into the lower passage 13 flows into the combustion chamber 4 via the second intake valve 6 on the one hand;
On the other hand, it flows into the combustion chamber 4 via the first intake valve 5 . In this way, during high engine load operation, the entire cross-sectional area of the intake port 8 is used as the intake air flow path.
Moreover, a large amount of air flows into the combustion chamber 4 from the second intake valve 6.
High filling efficiency can be achieved because the fuel is supplied within the tank. Furthermore, since the intake port 8 is formed as a straight port with low flow resistance as a whole, the filling efficiency is further improved. Further, the second intake valve 6 has a lower intake port inlet portion 9 than the first intake valve 5.
Since the second intake valve 6 is located close to the second intake valve 6, the passage resistance from the intake port inlet 9 to the second intake valve 6 is small, and the filling efficiency is further improved compared to the case where a pair of intake valves are arranged in parallel. be able to.

[Effect of idea]

As described above, according to the present invention, the intake port consisting of a straight port is divided into an upper passage and a lower passage by a partition wall, and the second intake valve is disposed in the lower passage downstream of the intake control valve. There is. Therefore, when the intake control valve is closed during engine low-medium load operation, the intake control valve prevents intake air from flowing into the lower passage, so that the intake air does not enter the combustion chamber through the second intake valve. Most of the intake air flows into the combustion chamber from the first intake valve through the upper passage. In this way, when the engine is running at low load, most of the intake air flows through the upper passage and from the first intake valve, so a strong swirling flow around the horizontal axis is generated in the combustion chamber, and the droplet fuel is thus generated. It is possible to suppress the generation of unburned HC due to the adhesion of HC, and to obtain good combustion by generating a strong swirling flow. Further, when the intake control valve opens during high engine load operation, a large amount of intake air is also supplied into the combustion chamber from the second intake valve, so that high charging efficiency can be obtained during high engine load operation.

[Brief explanation of the drawing]

Fig. 1 is a plan sectional view of the cylinder head taken along the partition wall, Fig. 2 is a side sectional view of Fig. 1, Fig. 3 is a sectional view taken along the - line in Fig. 1, and Fig. 4 is a sectional view taken along the - line in Fig. 1. The figure is a sectional view taken along the - line in FIG. 1, and FIG. 5 is a sectional view taken along the - line in FIG. 1. 5...First intake valve, 6...Second intake valve, 8...
Intake passage, 10... Partition wall, 12... Upper passage, 1
3... lower passage, 16... intake control valve.

Claims (1)

[Scope of utility model registration request] The intake port includes a first intake valve and a second intake valve, and the intake port is a straight port that extends from the intake port inlet in a substantially horizontal direction and then gradually curves downward toward the first intake valve. A partition is formed in the intake port that projects from above the side surface toward the other side surface and extends from around the first intake valve stem toward the upstream side of the intake port, and the protruding tip edge of the partition wall is spaced apart from the other side surface of the intake port. At the same time, the inside of the intake port is divided into an upper passage and a lower passage by the partition wall, and an intake control valve that opens fully during engine high load operation is provided in the lower passage, and a second intake control valve is provided in the lower passage downstream of the intake control valve. An internal combustion engine intake system with an intake valve.