JPH0627487B2 - Internal combustion engine intake system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an intake system for a four-valve internal combustion engine.

A four-valve internal combustion engine has been put to practical use as one in which two intake / exhaust valves are provided for each cylinder to improve intake charging efficiency.

A conventional four-valve type internal combustion engine of this type is, for example, the first
There is something like the one shown in the figure. Each cylinder has two intake / exhaust valves, and in synchronism with the combustion cycle of the engine, intake air is introduced into the combustion chamber from the intake port where these intake / exhaust valves are opened and closed, and exhausted after combustion. Is discharged from the exhaust port. That is, reference numeral 1 in the drawing is a cylinder head, and two intake valves 3 and 4 are provided in an intake port 2, and a cam 6, a tappet 7, and a push rod 8 which are rotated together with a cam shaft 5 are used. The rocker arm 9 serves to open and close the two intake valves 3 and 4 at the same time. The structure and drive of the exhaust valve are also the same (see Sankaido “Internal Combustion Engine Structural Drawings”, October 15, 1974, page 125).

However, in such a conventional intake device for a four-valve internal combustion engine, the rocker arm 9 simultaneously drives two intake valves 3 through the push rod 8 by driving the camshaft 5. 4 is a mechanism for opening the valve 4, and the two intake valves 3,
4, the intake air is introduced at the same time, which has the effect of improving the intake charging efficiency. On the other hand, since the opening area at the initial stage of opening the valve is large, a strong gas flow cannot be obtained, and atomization and mixing of fuel become insufficient. As a result, the engine output and fuel efficiency performance were insufficient.

Therefore, for example, Japanese Utility Model Laid-Open No. 56-94820, Japanese Utility Model Laid-Open No. 57-92025, and Japanese Utility Model Laid-Open No. 55-17640.
As in the technique described in Japanese Patent No. 5, the opening timing of two intake valves provided for each cylinder is made different to create a shear flow due to mutual interference of air, or blow-through to an exhaust port by air alone. However, it is difficult to cause a sufficient intake swirl flow in the cylinder, and the promotion of mixing of the injected fuel and air is insufficient.

In particular, in the conventional example described in Japanese Utility Model Laid-Open No. 55-176405, both intake valves are opened by a common valve arm and cam, so that the phase difference between the opening timings of both intake valves is set to a large value. Then, the operating angle of the intake valve that opens late and the valve lift amount become excessively small, the intake flow rate introduced from this decreases, and the overall intake charge efficiency significantly decreases, and a strong intake swirl occurs. I can't get the flow.

Means for Solving the Problems The present invention has been devised in view of the above-mentioned conventional problems, and a single intake port is arranged near the peripheral edge on one side of the cylinder, and a plurality of intake valves are provided. Are arranged in series on the upstream side and the downstream side respectively in the axial direction of, and the shape of the vicinity of the opening of the intake port where the downstream intake valve opens and closes is helical, and the upstream intake valve and the downstream intake valve Are operated by separate cams, the closing timing of each intake valve on the upstream and downstream sides and the valve lift amount are set to be substantially the same, and the opening timing of the upstream intake valve is set to the opening timing of the downstream intake valve. It is characterized in that it is set so as to be delayed by a predetermined angle from the timing, and an injection nozzle is arranged at a substantially central portion of the cylinder.

Effect According to the present invention having the above-described configuration, the intake valves on the upstream and downstream sides are arranged in series along the axial direction of the single intake port and near the peripheral edge on the one side of the cylinder. It becomes possible to generate a powerful swirling flow. In particular, since the shape of the vicinity of the opening of the intake port where the downstream side intake valve opens and closes is formed in a helical shape, the intake air that has flowed into the combustion chamber becomes a strong swirl flow (swirl) along the inner wall surface of the cylinder. It is possible to flow in the combustion chamber and generate the maximum intake flow in the entire combustion chamber.

Moreover, since the intake valves on the upstream and downstream sides are operated by separate cams, respectively, the closing timing of both intake valves and the valve lift amount can be set to be the same, and the phase difference of the opening timing can be set large. Therefore, the intake valve on the upstream side is
Since it operates with a sufficiently large operating angle and valve lift amount, and opens later than the intake valve on the downstream side, it is possible to secure a sufficient intake amount to be introduced into the combustion chamber and prevent a decrease in intake charging efficiency. At the same time, the swirl generated earlier from the intake valve on the downstream side is further strengthened. Further, the swirl is continuously strengthened until the intake valve on the downstream side is closed, so that the maximum intake flow can be generated in the combustion chamber.

Further, by providing the fuel injection nozzle in the center of the cylinder, the fuel injected from the injection nozzle is evenly distributed throughout the combustion chamber, and the fuel injection force and the extremely strong swirl as described above are mutually By interfering with each other, the mixing of fuel and air is further promoted.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

2a and 2b show an embodiment in which the present invention is applied to a direct fuel injection type diesel engine.

That is, reference numeral 11 in the drawing denotes a cylinder head, and a single intake port 16 and a single exhaust port 17 are formed inside the cylinder head. The intake / exhaust ports 16 and 1
The cylinder 7 is formed substantially parallel to both sides of the cylinder center 18, and a pair of one-end openings facing the combustion chamber are provided along the axial direction of the intake / exhaust ports 16 and 17, respectively. Further, the intake port 16 is connected to the cylinder 28
It is arranged near the peripheral edge on one side, and the shape near the one end opening is formed in a helical shape. Two intake valves 12 and 13 on the upstream side and two exhaust valves 14 on the upstream side and the downstream side, which are perpendicular to the cylinder head 11 via valve guides, are provided at one end openings of the intake and exhaust ports 16 and 17, respectively. ，
15 are provided. Therefore, each intake valve 1
2, 13 and the exhaust valves 14, 15 are intake / exhaust ports 16, 1
They are arranged in series along the axial direction of 7 and are provided on both sides of the cylinder center 18.

Further, an injection nozzle 19 for directly injecting fuel into the combustion chamber is provided at the center of the cylinder on the cylinder center 18.

Furthermore, one of the two intake valves 12 and 13 is directly driven by the linear cam 24 provided on the camshaft 22 via the valve lifter 21, and the other intake valve 13 is connected to the camshaft. It is indirectly driven by a rocker arm 23 that interlocks with a rocker arm actuating cam 25 provided at 22. That is, both intake valves 12 and 13 are
The linear cam 24 and the actuating cam 25 are independently actuated. 26 and 27 are intake valves 12 and 13, respectively.
Is a valve spring that urges the valve closing direction. The exhaust valves 14 and 15 are also driven by the same structure.

FIG. 3 shows the linear cam 2 provided on the camshaft 22.
4, the mounting positional relationship between the rocker arm actuating cam 25, the intake valve 12, the exhaust valve 14, and the rocker arm 23 is shown.

Further, the direct acting cam 24 and the rocker arm actuating cam 25 provided on the camshaft 22 have cam portions formed as shown in FIG. 4, and the intake / exhaust valves 12, 14 driven by the direct acting cam 24. Along with the rotation of the camshaft 22,
The intake / exhaust valves 13, 15 driven by the rocker arm actuating cam 25 while being lifted by the cam lift x
Lifts the cam lift y by a ratio determined by the rocker arm 23.

The cam lobes of the direct acting cam 24 and the rocker arm actuating cam 25 that drive the intake valves 12 and 13 are arranged such that the intake valve 12 on the downstream side of the intake port 16 is more than the intake valve 13 on the upstream side of the intake port. As shown in FIG. 5, the valve opening timing is set to be shifted by a predetermined angle α ° so as to be advanced. A curve I shows the valve lift of the intake valve 12, and a curve II shows the valve lift of the intake valve 13. In addition, TDC is top dead center,
BDC is bottom dead center.

Therefore, as is clear from this figure, both intake valves 1
The closing timings of 2 and 13 and the valve lift amount are set to be the same.

The operation of this embodiment will be described below.

That is, in this embodiment, the intake valves 12, 13 on the upstream and downstream sides
Are arranged in series along the axial direction of the single intake port 16 and near the peripheral edge on one side of the cylinder 28,
It is possible to generate a powerful swirling flow of intake air in the combustion chamber. Particularly, since the shape of each intake port 16 near each one end opening is formed into a helical shape that wraps around the shape of the cylinder inner wall surface, the intake air flowing into the combustion chamber swirls strongly along the inner wall surface of the cylinder 28. It becomes a flow (swirl) to flow in the combustion chamber, and it becomes possible to generate the maximum intake air flow in the entire combustion chamber.

Moreover, the cam profiles of the cams 24 and 25 can be appropriately set to a predetermined shape so that the closing timing of both intake valves 12 and 13 and the valve lift amount can be set to the same value as described above. The opening timing of the intake valve 13 is set to the intake valve 1 on the downstream side.
The retard angle can be controlled by α ° relative to the opening timing of 2. Therefore, in the early stage of intake when only the intake valve 12 on the downstream side is opened first, since the intake valve 13 on the upstream side is closed, the opening area of the intake port 16 as a whole with respect to the combustion chamber becomes small, and the throttle effect is caused. The inflow velocity of intake air becomes sufficiently high. Therefore, the intake air having a high flow velocity becomes a powerful swirling flow in the circumferential direction along the inner wall surface of the cylinder 28 and flows in the combustion chamber.

Next, when the intake valve 13 on the upstream side is opened, the intake air introduced from here rides on the strong swirl flow already formed and flows in a direction (forward flow) that strengthens the swirl. That is, in combination with the configuration in which the both intake valves 12 and 13 are arranged on the same axis of the intake port 16 as described above, the intake air flowing from the intake valves 12 and 13 flows in the same direction. They flow in an overlapping manner, and the trailing intake flow assists the preceding intake flow. Therefore, a very strong swirling main flow is formed as a whole, and at the same time, fine turbulence is generated.

Further, since the closing timings of both intake valves 12 and 13 are set to be the same and the valve lift amount is set to be sufficiently large,
A sufficient intake flow rate introduced through the intake valve 13 on the upstream side, which opens late, can be sufficiently secured to improve the charging efficiency, and the large intake flow rate can be used to increase the swirling force of the preceding intake air as described above. The swirl is further strengthened due to the subsidies. Furthermore, this swirl is continuously strengthened to the gap where the intake ends.

Due to the strong intake air thus obtained, the fuel injected into the combustion chamber by the injection nozzle 19 is promoted to be mixed with air, so that the combustion is significantly improved and the output of the engine and the fuel consumption can be improved. In particular, since the injection nozzle 19 is provided in the center of the cylinder, the fuel is evenly distributed throughout the cylinder, and the injection force and the air swirling force violently interfere with each other. Therefore, in combination with the strong intake flow and the fine turbulence, the mixing of the injection combustion and the air is further promoted, the combustion efficiency is improved, and the fuel economy and the output can be sufficiently improved.

Further, since the overlap between the opening timing of the intake valve 12 and the closing timing of the exhaust valves 14 and 15 can be made sufficiently small, it is possible to prevent blow-in of intake air into the exhaust port and the filling efficiency. Can be suppressed.

Further, in the above-mentioned embodiment, the quality of mixing of fuel and air greatly affects the fuel performance, and an example in which the present invention is applied to a direct fuel injection type diesel engine in which the effect of application of the present invention is remarkable is shown. It goes without saying that it is also applicable to institutions.

EFFECTS OF THE INVENTION As is apparent from the above description, according to the present invention, in particular, the peculiar arrangement configuration of the intake port and the plurality of intake valves and the respective intake valves are independently operated by the respective cams to close the closing timing. And the valve lift amount are set to be approximately the same, and the valve opening timing is made different, so that a sufficient intake air charging efficiency is always ensured regardless of the low speed and high speed operation of the engine, and a powerful intake air is used in the cylinder. It becomes possible to create swirls. Therefore, the fuel uniformly injected into the cylinder from the injection nozzle at the center of the cylinder violently interferes with the injection force and the powerful intake swirl to further promote the mixing of the fuel and the air.

As a result, the combustion efficiency is significantly improved, and the engine output and fuel consumption can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a main part of a conventional internal combustion engine, FIG. 2 is a sectional view showing the structure of an embodiment of the present invention, and FIG. 3 is an intake / exhaust valve, a cam, FIG. 4 is a schematic sectional view showing the mounting position relationship of the rocker arm, FIG. 4 is a view showing the relationship between the direct acting cam and the rocker arm actuating cam, and FIG. 5 is a view showing the timing of opening the two intake valves. 12, 13 ... Intake valve, 14, 15 ... Exhaust valve, 16 ...
... intake port, 17 ... exhaust port, 18 ... cylinder center, 19 ... injection nozzle, 21 ... valve lifter,
22 ... Camshaft, 23 ... Rocker arm, 24
…… Linear cam, 25 …… Rocker arm actuating cam, 28
……Cylinder.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Eiichi Onishi 1 Natsushima-cho, Yokosuka City, Kanagawa Nissan Motor Co., Ltd. Oppama Plant (56) References Japanese Patent Application No. 54-74665 (No. 55-176405) No.), the specification and drawings attached to the application of the microfilm (JP, U) Jpn. App. No. 54-39707 (Kaikai No. 55-139226) A microfilm (JP, U) of the contents of the surface photographed. A microfilm (JP, U) in which the specification and the contents of the drawings attached to the application of Japanese Patent Application No. 51-177725 (Japanese Utility Model Application No. 53-90706) are taken. , U)

Claims (1)

[Claims] 1. A single intake port is arranged near a peripheral edge on one side of a cylinder, and a plurality of intake valves are arranged in series upstream and downstream respectively along an axial direction of the intake port.
And the shape of the vicinity of the opening of the intake port at which the downstream side intake valve opens and closes is helical, and the upstream side intake valve and the downstream side intake valve are operated by separate cams, respectively, and The closing timing and the valve lift amount are set to be substantially the same, and the opening timing of the upstream side intake valve is set to be delayed by a predetermined angle from the opening timing of the downstream side intake valve. An intake device for an internal combustion engine, comprising an injection nozzle.