JPH07127467A - Engine intake system - Google Patents

Abstract

(57) [Summary] [Purpose] To guide the air-fuel mixture from the air-fuel mixture intake port in a prescribed direction in the upper part of the combustion chamber without providing protrusions that obstruct the flow in the combustion chamber or form a quench zone. Make it possible to promote stratification. [Composition] An intake port for introducing fresh air and an intake port 5 for supplying air-fuel mixture are provided for each cylinder, and the intake port 5 for supplying air-fuel mixture is opened with a delay. Then, at least the intake valve 12 on the air-fuel mixture introduction side is set so that the incident angle θ of the valve shaft is less than 90 ° when viewed from the cylinder axis A side with respect to the combustion chamber ceiling surface, and the valve peripheral portion thereof has a predetermined clearance. A recess 15 is formed on the ceiling surface of the combustion chamber, the recess 15 being deeper toward the periphery of the combustion chamber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine intake device, and more particularly, to an intake port dedicated to generating and supplying an air-fuel mixture in addition to an intake port for supplying fresh air. The present invention relates to an engine intake device for achieving stratification by making them different.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Utility Model Laid-Open No. 61-1867.
As described in Japanese Patent Publication No. 32, No. 32, a plurality of intake ports are provided, one of which is for supplying the air-fuel mixture, and the other intake port is for introducing fresh air, and an intake port for introducing fresh air. On the other hand, by setting the valve timing so that the opening timing of the intake port for supplying the air-fuel mixture is delayed, a swirl flow is generated in the combustion chamber and the air-fuel mixture is introduced above the fresh air to promote stratification. In addition, a mask surrounding the periphery of the intake valve on the air-fuel mixture supply side is formed to guide the air-fuel mixture to the center of the combustion chamber to promote stratification and to form a squish area with the upper surface of the piston. Then, in order to improve combustion by a rapid flow due to squish, it is known to provide a ridge protruding downward on the inner wall surface of the cylinder head. Separately, it has been conventionally performed to arrange an intake port in the combustion chamber so as to generate a tumble flow (longitudinal vortex flow) and improve combustion by the tumble flow.

[0003]

As described above, the squish is formed by providing the intake port for supplying the air-fuel mixture in addition to the intake port for introducing the fresh air, and providing the ridge or the protrusion below the inner wall surface of the cylinder head. When the area is formed and a mask for air-fuel mixture guidance is formed around the intake port for air-fuel mixture supply, the flow in the combustion chamber such as swirl flow or tumble flow is affected by the complicated shape of the protrusion. As a result, the burnability may deteriorate, and if the air-fuel ratio is large and the burnup is slow in lean burn, the squish area is in the quench zone.
Therefore, a large amount of unburned components such as HC may be discharged.

The present invention has been made to solve such a problem, and the mixing from the intake port for supplying the air-fuel mixture without the provision of protrusions that obstruct the flow in the combustion chamber or form a quench zone. The purpose is to guide air to a predetermined position above the combustion chamber so as to promote stratification.

[0005]

According to the present invention, two types of intake ports for introducing fresh air and for supplying air-fuel mixture are provided for each cylinder.
The present invention relates to an engine intake device in which a poppet-type intake valve is arranged in each, and the valve timing is set so that the opening timing of the intake port for supplying the air-fuel mixture is delayed with respect to the intake port for introducing fresh air. Of the intake valves, at least the intake valve arranged in the intake port for supplying the air-fuel mixture is set such that the incident angle from the cylinder axis side with respect to the combustion chamber ceiling surface around the intake valve is less than 90 °. Is characterized in that a recessed portion that surrounds the peripheral portion of the intake valve with a predetermined clearance is formed deeper toward the combustion chamber peripheral side, and a port opening is formed in the recessed portion.

The intake port for introducing fresh air may generate a tumble flow in the cylinder axial direction in the combustion chamber,
In that case, the intake port for supplying the air-fuel mixture can be arranged so as to open to the combustion chamber at a peripheral position where it is subjected to the scraping action of the tumble flow.

Further, in order to strengthen the tumble flow, the respective intake valves arranged in the two types of intake ports are less than 90 ° in incidence angle from the cylinder axis side to the combustion chamber ceiling surface around the intake valves. With such a setting, recesses that are deeper toward the periphery of the combustion chamber are formed on the ceiling surface of the combustion chamber so as to surround the peripheral portions of the intake valves with a predetermined clearance, and the port openings are formed in the recesses. Can be configured.

[0008]

The intake valve arranged in the intake port for supplying the air-fuel mixture is set to have a tilt angle of less than 90 ° with respect to the ceiling surface of the combustion chamber. As a natural configuration, the peripheral edge of the intake valve whose inclination angle is set to less than 90 ° is surrounded by a recess deeper toward the periphery of the combustion chamber with a predetermined clearance, and a port opening is formed in the recess. . When fresh air is introduced from the intake port for introducing fresh air into the combustion chamber and then the intake port for supplying the air-fuel mixture is opened later to supply the air-fuel mixture, the side wall surface around the combustion chamber in the recess is The air-fuel mixture is guided to the upper part of the combustion chamber by acting as a mask or a deflector for guiding the air-fuel mixture, and a gas-air mixture layer is formed around the spark plug.

Further, according to the structure of the present invention, since the mask is formed in a natural shape without protruding into the combustion chamber, when a tumble flow is generated in the combustion chamber by the intake port for introducing fresh air, the tumble flow is generated. The flow is not obstructed by the mask. Moreover, in this case, even if the intake port for introducing the air-fuel mixture is opened at a position around the combustion chamber where the intake port for introducing fresh air is far from the ignition plug and the tumble flow is scraped up. The flow of the air-fuel mixture to the spark plug side is further promoted by the scraping action of the tumble flow, and the air-fuel mixture is prevented from flowing to the opposite side and fuel is attached to the wall surface. Therefore, by opening the intake port for supplying the air-fuel mixture in the vicinity of the combustion chamber, the intake port for introducing fresh air can have a sufficient diameter, and the charging efficiency can be improved.

Further, not only the intake valve on the air-fuel mixture supply side but also the intake valve on the fresh-air supply side is set to have a tilt angle of less than 90 °, and a similar concave portion is formed. The flow of the fresh air introduced from the intake port for supplying air is guided by the wall surface of the recess in the direction of the tumble flow generation and is blocked from flowing in the opposite direction. As a result, the tumble flow is strengthened and the tumble flow is also increased. The scratching action of the mixture is enhanced, and the stratification of the air-fuel mixture is further promoted.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1. 1 is a vertical cross-sectional view of a cylinder head portion of an engine according to a first embodiment of the present invention, and FIG. 2 is a view of a combustion chamber of the engine seen from a lower surface of the cylinder head.

In the figure, 1 is a cylinder head,
Reference numeral 2 is a pent roof type combustion chamber formed in the cylinder head. The cylinder head 1 is fixed to a cylinder block (not shown), and the combustion chamber 2 is arranged at the upper end of each cylinder bore provided in the cylinder block. Pistons are arranged in the cylinder bores, and the pistons are connected to the crankshaft by a connecting rod in a predetermined phase.

The cylinder head 1 is provided with first and second two fresh air intake ports 3 and 4 and an air-fuel mixture intake port 5 for each cylinder. Two exhaust ports 6 and 7 are provided.

The combustion chamber 2 has a ceiling surface inclined toward the intake side and the exhaust side with a center line B in the cylinder row direction as a boundary. A plug hole 8 is provided in the cylinder head 1 so as to be located at the center of the combustion chamber 2, and the spark plug 9 is provided in the plug hole 8 so as to be slightly inclined toward the exhaust side with respect to the cylinder axis A.
Is installed. Further, the air-fuel mixture supply port 5 has an opening at the periphery of the combustion chamber 2 and the center line B in the cylinder row direction.
Are arranged so as to be located on the center line C of the combustion chamber in the direction orthogonal to the direction. The first fresh air intake port 3 and the second fresh air intake port 4 have their openings for supplying the air-fuel mixture. It is arranged so as to be located in the intake side half portion which is line-symmetric with respect to the center line C passing through the opening of the port 5 and the plug hole 8. Further, the two exhaust ports 6 and 7 are arranged such that their respective openings are located in the exhaust-side half of the combustion chamber 2 which is line-symmetric with respect to the center line C.

Poppet-type valves driven in synchronism with the crankshaft are provided at the openings of the respective ports. That is, the first intake valve 10 is provided at the opening of the first fresh air intake port 3, and the second intake valve 11 is provided at the opening of the second fresh air intake port 4. A third intake valve 12 is provided at the opening of the intake port 5 for supplying air-fuel mixture. The first exhaust port 6 is provided with a first exhaust valve 13, and the second exhaust port 7 is provided with a second exhaust valve 14. The valve shafts of the first and second two intake valves 10 and 11 for introducing fresh air are arranged vertically to the ceiling surface of the combustion chamber, and the exhaust valves 13 and 14 for exhausting the combustion chamber also have the same ceiling. It is placed perpendicular to the plane. On the other hand, the third intake valve 12 for introducing the air-fuel mixture
Is set such that the incident angle θ of the valve shaft is less than 90 ° when viewed from the cylinder axis A side with respect to the ceiling surface of the combustion chamber. Then, by setting such an incident angle θ, a concave portion 15 that becomes deeper toward the peripheral side is provided on the combustion chamber ceiling surface according to the angle formed between the valve face surface and the combustion chamber ceiling surface. An opening of the intake port 5 for supplying the air-fuel mixture is formed at 15.

The recess 15 forms a mask whose wall surface on the peripheral side of the combustion chamber has a maximum height h _i , and directs the air-fuel mixture supplied from the air-fuel mixture intake port 5 toward the center of the combustion chamber 2. The peripheral portion of the third intake valve 12 is surrounded with a predetermined clearance so as to be guided. Here, the mask height h _i for the valve lift L of the third intake valve 12, h _i
It is set so that ≈L and the relation of hi ≧ L is satisfied.
Further, in order to increase the lean limit (limit air-fuel ratio of lean burn), the relationship between the valve lift L and the valve diameter D is L =
Experiments have confirmed that 0.22D is optimal. Therefore, h _i is D ≧ h _i ≧ 0.22D
It is said that the relationship of is satisfied.

First and second fresh air intake ports 3, 4
Both open straight to the combustion chamber 2 and introduce only fresh air toward the exhaust ports 6 and 7, thereby generating a tumble flow in the cylinder axis direction. On the other hand, the intake port 5 for supplying the air-fuel mixture also opens straight toward the spark plug 9. Intake port 5 for supplying air-fuel mixture
Is supplied with pressurized air from a supercharger (not shown) via the control valve 16, and further fuel is injected from the fuel injection valve 17 before opening. Then, the fuel and the pressurized air are mixed in the closed space to generate a mixture having a relatively high pressure.
When the intake valve 12 is opened, the mixture enters the combustion chamber 2 and flows between the tumble flows toward the spark plug 9.

In contrast to the first and second intake valves 10 and 11 that open and close the fresh air intake ports 3 and 4, the third intake valve 12 that opens and closes the mixture supply intake port 5 opens later. Is set to FIG. 3 shows these intake valves 10, 11,
12 is a lift characteristic diagram of FIG. The third intake valve 12 begins to open near the maximum lift of the first and second intake valves 10, 11. As a result, first, the first and second intake valves 10,
11 opens and the combustion chamber 2 from the intake ports 3 and 4 for fresh air introduction
Fresh air is introduced into the inside, and a tumble flow is generated inside the combustion chamber 2 that expands to the cylinder bore side. Then, when the air-fuel mixture supply intake port 5 is opened after that, the air-fuel mixture is guided by the combustion chamber peripheral side wall surface of the recess 15 and flows to the upper part of the combustion chamber, forming a gas-fuel mixture layer in the vicinity of the ignition plug 9. . At that time, the flow of the air-fuel mixture toward the spark plug is further promoted by the scraping action of the tumble flow.

Example 2. FIG. 4 is a vertical cross-sectional view of a cylinder head portion of an engine according to a second embodiment of the present invention, and FIG. 5 is a view of a combustion chamber of the engine seen from the lower surface of the cylinder head.

In the second embodiment, the third intake valve 12 that opens and closes the intake port 5 for supplying the air-fuel mixture is viewed from the cylinder axis A side with respect to the ceiling surface of the combustion chamber, as in the first embodiment. The incident angle θ of the valve shaft is set to be less than 90 °, and a recess 15 is provided on the combustion chamber ceiling surface so as to become deeper toward the peripheral side according to the angle between the valve face surface and the combustion chamber ceiling surface. An opening of the intake port 5 for supplying the air-fuel mixture is formed at 15. Further, the first and second intake valves 10 and 11 for introducing fresh air also have an incident angle θ of 9
Recesses 18 and 19 which are less than 0 ° and become deeper toward the peripheral side are provided. The openings of the intake ports 3 and 4 for introducing fresh air are formed in the recesses 18 and 19. Other configurations are similar to those of the first embodiment. In the figure, the same parts as those in the first embodiment are designated by the same reference numerals.

Also in the case of the second embodiment, first, the first and second intake valves 10 and 11 are opened to introduce fresh air air into the combustion chamber 2 from the fresh air intake ports 3 and 4, and the cylinder bore is opened. After the tumble flow is generated inside the combustion chamber 2 which expands to the side, the intake port 5 for supplying the air-fuel mixture is opened with a delay, and the air-fuel mixture flows to the upper part of the combustion chamber. At this time, the flow of the fresh air introduced from the fresh air intake ports 3 and 4 is changed to the concave portion 1 described above.
The tumble flow is strengthened by the masking action of 8 and 19, and the stratification is further promoted.

Example 3. FIG. 6 is a vertical cross-sectional view of a cylinder head portion of an engine according to a third embodiment of the present invention, and FIG. 7 is a view of a combustion chamber of the engine seen from the lower surface of the cylinder head.

In the third embodiment, the plug hole 8 is provided on the center line C orthogonal to the combustion chamber center line B in the cylinder row direction at the position deviated from the center of the combustion chamber 2 toward the exhaust side, and the same center line is provided. The air-fuel mixture supply port 5 is arranged so that the opening is located at a position near the center on C, which is slightly off from the center of the combustion chamber 2 toward the intake side. Then, the first fresh air intake port 3 and the second fresh air intake port 4 have their openings with respect to the center line C passing through the opening of the mixture supply port 5 and the plug hole 8. It is arranged so as to be located near the periphery of the intake side half that is line symmetrical. The valve shafts of the first and second intake valves 10 and 11 for introducing fresh air are arranged perpendicularly to the ceiling surface of the combustion chamber, and only the third intake valve 12 for introducing air-fuel mixture burns. The angle of incidence θ of the valve shaft is set to less than 90 ° when viewed from the side of the cylinder axis A with respect to the ceiling surface of the room, and the concave portion 15 is formed so as to become deeper toward the peripheral side as in the case of the first embodiment. ing. An opening of the intake port 5 for supplying the air-fuel mixture is formed in the recess 15. Other configurations are similar to those of the first embodiment.

Example 4. FIG. 8 is a vertical cross-sectional view of a cylinder head portion of an engine according to a fourth embodiment of the present invention, and FIG. 9 is a view of a combustion chamber of the engine seen from the lower surface of the cylinder head.

In the fourth embodiment, the arrangement of the plug hole 8 and each port is the same as that of the third embodiment, but the third embodiment for opening and closing the intake port 5 for supplying the air-fuel mixture is the same as the second embodiment.
Not only the intake valve 12 but also the first and second intake valves 10 and 11 for introducing fresh air, the incident angle θ is set to less than 90 °, and the concave portions 18 and 19 are formed so as to become deeper toward the peripheral side. It was done like this. Other configurations are similar to those of the third embodiment.

Although the embodiment in which two intake ports for introducing fresh air and two exhaust ports are provided for each cylinder has been described above, the number or arrangement of these intake ports and exhaust ports is the same as in the above embodiment. It goes without saying that it is not limited to ones.

As described above, according to the present invention, the mask for forming the air-fuel mixture layer is formed without providing protrusions that obstruct the flow in the combustion chamber or form the quench zone. It is possible to improve the combustibility with a compact structure.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a cylinder head portion of an engine according to a first embodiment of the present invention.

FIG. 2 is a view of the combustion chamber of the engine according to the first embodiment of the present invention as seen from the lower surface of the cylinder head.

FIG. 3 is a valve lift characteristic diagram of the engine according to the first embodiment of the present invention.

FIG. 4 is a vertical sectional view of a cylinder head portion of an engine according to a second embodiment of the present invention.

FIG. 5 is a diagram of a combustion chamber of an engine according to a second embodiment of the present invention as seen from a lower surface of a cylinder head.

FIG. 6 is a vertical sectional view of a cylinder head portion of an engine according to a third embodiment of the present invention.

FIG. 7 is a diagram of a combustion chamber of an engine according to a third embodiment of the present invention as viewed from the bottom surface of a cylinder head.

FIG. 8 is a vertical sectional view of a cylinder head portion of an engine according to a fourth embodiment of the present invention.

FIG. 9 is a diagram of a combustion chamber of an engine according to a fourth embodiment of the present invention as seen from a lower surface of a cylinder head.

[Explanation of symbols]

 1 Cylinder Head 2 Combustion Chamber 3,4 Intake Port for Fresh Air Introduction 5 Intake Port for Mixture Mixture 8 Plug Hole 9 Spark Plug 10, 11, 12 Intake Valve 15 Recess

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area F02B 29/08 F 31/02 C F02M 69/00 360 BC

Claims (3)

[Claims] 1. Two for introducing fresh air and for supplying air-fuel mixture for each cylinder
There are three types of intake ports, poppet type intake valves are installed in each, and the intake timing of the engine is set so that the opening timing of the intake port for supplying the air-fuel mixture is delayed relative to the intake port for introducing fresh air. In the device, at least one of the intake valves disposed in the intake port for supplying the air-fuel mixture is set such that an incident angle from the cylinder axis side to the combustion chamber ceiling surface around the intake valve is less than 90 °, An intake device for an engine, wherein a recessed portion that surrounds a peripheral portion of the intake valve with a predetermined clearance is provided on the ceiling surface of the combustion chamber and is deeper toward the combustion chamber peripheral side, and a port opening is formed in the recessed portion. 2. The intake port for introducing fresh air is for generating a tumble flow in the cylinder axial direction in the combustion chamber, and the intake port for supplying air-fuel mixture is burned at a peripheral position where it is subjected to the scraping action of the tumble flow. The intake system for an engine according to claim 1, wherein the intake system is arranged so as to open to the chamber. 3. The respective intake valves arranged in the two types of intake ports are set such that the incident angle from the cylinder axis side to the ceiling surface of the combustion chamber around the intake valves is less than 90 °. 3. The engine according to claim 2, wherein recesses are provided on the ceiling surface so as to surround the peripheral portions of the intake valves with a predetermined clearance, and the recesses are deeper toward the periphery of the combustion chamber, and the respective port openings are formed in the recesses. Intake device.