JPS5936091B2 - engine intake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention effectively generates swirl within the combustion chamber to improve combustibility, and also makes the strength of the swirl in each cylinder approximately the same to prevent torque fluctuations. The present invention relates to an intake system for an engine.

Conventionally, engine intake systems have been equipped with a low-load intake port and a high-load intake port for each cylinder, and a single intake valve that opens and closes both intake ports. A device equipped with an on-off valve that opens when a load is applied has been proposed (Utility Model Publication No. 1983-61118).

The intake system of this engine closes the high-load intake port with an on-off valve during low-load conditions, allowing intake air to be drawn into the combustion chamber only from the low-load intake port, increasing the intake flow rate and strengthening the swirl. , which promotes fuel atomization and improves combustion performance and fuel efficiency.At the same time, when the load is high, the on-off valve opens and intake air is drawn from the high-load intake port in addition to the low-load intake port, improving charging efficiency. This has the advantage of improving output performance.

However, the above-mentioned conventional engine intake system is difficult to effectively generate swirl in relation to the inlet manifold and the low-load intake port, and to make the strength of swirl in each cylinder the same. There are two types of inlet manifolds (the so-called banana type and the tournament type).

) is not related to the placement and direction of the low-load intake port, so the flow of intake air to the low-load intake port becomes weak in some cylinders, as shown below. This method has the disadvantage that the swirl cannot be strengthened, and that there is an imbalance in the strength of the swirl between the cylinders.

In other words, the intake system of the conventional engine described above uses a 1- to 3-ment type inlet manifold, and all the low-load intake boats are offset in the same direction of the cylinder row with respect to the center of the combustion chamber. It is oriented in a direction parallel to and opens into the combustion chamber.

However, in a tournament-type inlet manifold, in the intake passages to the two outer cylinders, the intake air flows strongly toward the outside due to intake inertia, while in the intake passages to the inner two cylinders, the intake air flows inward due to intake inertia. The flow is strongly biased towards.

However, as mentioned above, in the intake system of the above-mentioned conventional engine, each low-load intake port is offset in the same direction of the cylinder row with respect to the upper middle of the combustion chamber. The intake port can be offset outward in the direction of the cylinder row from the center of the combustion chamber to strengthen the swirl along the strong flow of intake air. Since it is offset inward in the direction of the cylinder row and does not follow the strong flow of intake air, it is not possible to strengthen the swirl.

Similarly, in both inner cylinders, one low-load intake port can strengthen the swirl along the strong flow of intake air, and the other low-load intake port is not along the strong flow of intake air, so Swirl cannot be strengthened.

Therefore, the conventional engine intake system described above cannot effectively generate swirl for all cylinders, and cannot sufficiently improve combustion performance and fuel efficiency.
This has the drawback that an imbalance occurs in the strength of the swirl between the cylinders, resulting in torque fluctuations.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks by associating the bias of the intake air flow in the intake passage determined by the type of inlet manifold with the arrangement and direction of the low-load port. It is an object of the present invention to provide a novel intake system for an engine that can effectively generate swirl and make the strength of swirl in each cylinder substantially the same.

Therefore, the structure and operation of the present invention is that each of the four cylinders is provided with a lower low-load intake port and an upper high-load intake port that are separated from each other by a partition wall, and both intake boats are opened and closed. In an engine having a single intake valve and communicating each intake port with the fuel supply device through an inlet manifold, the inlet manifold is formed into a banana shape to reduce flow loss due to bending of the passage. The flow of intake air in the intake passage (ζ) is biased outward in the direction of the cylinder row, while
The inner wall surface of each low-load intake port of each set of cylinders in the cylinder row direction is inclined, and the center of the low-load intake port is offset outward in the cylinder row direction with respect to the center of the combustion chamber. By arranging each low-load intake port along the direction of strong intake air flow, swirl is effectively generated, improving combustion performance and fuel efficiency, and reducing swirl in the combustion chamber of each cylinder. The feature is that the strength is kept approximately the same and no variation of 1 herk occurs.

The present invention will be described in detail below with reference to the illustrated embodiments.

Fig. 1 shows one cylinder A, where 1 is a cylinder arranged vertically, 2 is a cylinder head, 3 is a combustion chamber, 4 is an intake port formed in the cylinder head 2, and 5 is an intake port 4 arranged in a downward direction. A low-load intake port 6 is located above and supplies the air-fuel mixture to the combustion chamber 3 in a horizontal direction.A high-load intake port is located above and supplies the air-fuel mixture to the combustion chamber 3 in a direction inclined with respect to the horizontal plane. 8 is a single intake valve that opens and closes both the low-load intake port 6 and the high-load intake port 7 at the opening to the combustion chamber 3; 11 is an example of a fuel supply device; a vaporizer, 12 is a vaporizer 11,
An inlet manifold 13 connects the low-load intake ports 1 to 6 and the high-load intake port 7, and 13 is rotatably supported on the inlet manifold 12 by a shaft 14, and is an on-off valve that opens and closes the high-load intake port 7. The on-off valve 13 is closed during low load, and the air-fuel mixture is supplied to the combustion chamber 3 only from the low-load intake port 6, increasing the flow velocity of the air-fuel mixture and strengthening the swirl within the combustion chamber 3. to promote fuel atomization and improve combustion performance and fuel efficiency.It also opens at high loads and transfers the air-fuel mixture to the intake port 6 for low loads.
and is supplied to the combustion chamber 3 from the high-load intake port 7,
It is designed to improve suction efficiency, charging efficiency, and output efficiency.

Note that 15 is an exhaust boat formed on the cylinder head 2;
16 is the exhaust valve, 17 is the camshaft, 18° 18 is the rocker arm shirt l-119, 19 is the rocker arm, 20
．． 20 is a valve spring.

On the other hand, in FIG. 2, B, C, and D are cylinders having substantially the same structure as the cylinder A described above.

The above four cylinders A, B, C, and D are each cylinder i, i
, i, i are arranged vertically, and the cylinders i, i, i, i are arranged on the same horizontal plane to form a linear cylinder row.

The inlet manifold 12 that supplies the air-fuel mixture to each of the cylinders A, B, C, and D is formed into a banana shape.

Therefore, the bending of the intake passage 25 formed by the manifold 12 and the intake boat 4 to the inlet 1 is less than when a tournament-type manifold is used, and the intake resistance due to the bending of the intake passage 25 is reduced. At the same time, the air-fuel mixture flowing from the base 25F of the intake passage 25 to the branch passages 25A, 25B, 25c, and 25D tends to flow outward in the cylinder row direction due to its inertia.

That is, as shown by the arrows vA, VB, vc, and VD in FIG.
In 25D, the flow velocity is faster and the flow rate is larger in the outer portion in the cylinder row direction.

The low-load intake ports 6, 6, 6.6 of each of the above cylinders A, B, C, ]) are divided into two groups with the center of the cylinder row as the boundary, and the low-load intake ports of the cylinders A, B, C, ]) are divided into two groups with the center of the cylinder row as the border. Intake port 9
, 6 and center lines Xc, XD of the other set of low-load intake ports 6.6 are symmetrically inclined outward in the cylinder row direction.

That is, as shown in FIG. 2.3.4, the inner wall surface 27 of each low-load intake port 6 in the cylinder row direction is aligned with the center line XA, XB,
XC, XI) are inclined so as to be offset outward in the cylinder row direction with respect to the center of each combustion chamber 3.

In the engine intake system configured as described above, the engine is currently in a low load state, and each cylinder A and B is in a low load state.

It is assumed that the high-load intake ports 7 of C and D are closed by on-off valves 13.

At this time, from the carburetor 11 to the inlet manifold 12
The branch passage 25A passes through the base 25F of the.

25B, 250. Since the inlet manifold is banana-shaped, the air-fuel mixture flowing into 250.
As shown in A, VB, VC, and VD, the flow is biased toward the center of all cylinder rows so that the outward flow in the direction of the cylinder rows is stronger, and since the on-off valve 13 is closed, each cylinder A, B, C.

It flows only into the low-load intake boats 6.6, 6, and 6 of D, and the flow speed is increased.

These low-load intake ports for each cylinder A, B, C, and D 6.6
, 6.6 are all inner wall surfaces 27, 2 in the cylinder row direction.
7, 27, 27, each low load intake port 1-6,
6, 6, 6 center lines XA, XB.

Since xc and xD are inclined so that xc and xD are offset outward in the cylinder row direction with respect to the center of the combustion chamber 3, and matched in the direction of the strong flow of the air-fuel mixture, the air-fuel mixture is 11
There is little resistance due to the 4-stroke 3, and it is guided smoothly horizontally into each combustion chamber 3, and into each cylinder A, B, C, D as indicated by the arrows SA, SB, and Sc in Fig. 2.

A strong horizontal squall as shown at SD is effectively generated, and the swirl strength of each cylinder A, B, C, and D is approximately equal.

Therefore, by effectively generating this stool, combustion performance and fuel efficiency are greatly improved, and each cylinder A and B
, C, I') by equalizing the strength of the swirl,
The 1-herk fluctuation of the engine is extremely reduced, and drivability is greatly improved.

Next, assuming that the engine is operating under high load, the opening/closing valves of each cylinder A, , B, C, and D are 13.13°1.
3.13 opens, the mixture flows to the low load intake port 6.6
, 6.6 and high-load intake bows 1 to 7 degrees 7.7.7 to the combustion chambers 3, 3, and 3.3, improving charging efficiency and improving output performance.

As is clear from the above description, the engine intake system of the present invention has four cylinders each provided with a lower low-load intake port and an upper high-load intake port that are opened and closed by a single intake valve. The above-mentioned intake boats and the fuel supply device are communicated with each other via a banana-shaped inlet manifold to bias the flow of intake air outward in the direction of the cylinder row, and to direct the flow of the intake air outward in the direction of the cylinder row of each of the above-mentioned low-load intake ports. The inner wall surface is tilted so that the center of each low-load intake port is offset outward in the cylinder row direction from the center of the combustion chamber, so that each low-load intake port has a strong intake air. Because they are arranged along the flow, they can effectively generate a strong swirl, improving combustion performance and fuel efficiency, as well as making the strength of the swirl uniform for each cylinder and preventing torque fluctuations. You can do it like this.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of one embodiment of the present invention, FIG. 2 is a cross-sectional view of the above-mentioned embodiment, and FIGS. 3 and 4 are cross-sectional views of essential parts, respectively. 3... Combustion chamber, 5... Partition wall, 6...
...Intake port for low load, 7...Intake port for high load, 8...Intake valve, 11...
Carburetor, 12...Banana-shaped inlet manifold, 13...Opening/closing valve, 27...Wall surface.

Claims (1)

[Claims] Equipped with 14 cylinders, each cylinder is opened and closed by a single intake valve and divided by a partition wall, with a low-load intake port located below and a high-load intake port located above. In the engine, the upstream end of each intake port is connected to an inlet manifold that communicates with a fuel supply device at one end, the inlet manifold is a banana-shaped inlet manifold, and each branch of the banana-shaped inlet manifold The low-load intake ports and high-load intake ports of each cylinder are connected to the passages, while the low-load intake ports of the two sets of cylinders, which are divided at the center in the cylinder row direction, are connected so that their centers are in the cylinder row direction. An intake system for an engine, characterized in that an inner wall surface in a cylinder row direction is inclined outward and in a direction offset from the center of a combustion chamber.