JPS6324133B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an intake system for an internal combustion engine, and more particularly to the structure of a partition wall that separates both ports of an intake system that has dual ports and the branching point of the two ports is located within the cylinder head. .

In automotive internal combustion engines, in order to achieve both low fuel consumption and high output performance under high-speed loads, internal combustion engines have independent dual intake ports, one of which is a helical port and the other a straight port. has already been proposed. By the way, when adopting the dual intake port system, it is necessary to reduce the passage wall area to reduce fuel adhesion to the wall surface, reduce the amount of unburned hydrocarbons released, and improve driveability. In order to reduce the space occupied by the cylinder head and facilitate cooling of the combustion chamber, it is desirable to form both ports into twin ports, so-called Siamese ports, which are branched from each other within the cylinder head. However, in this case, compared to two independent ports, or compared to a case where a throttle valve is provided on at least one of the ports, the two ports have a much stronger influence on each other, and the two ports have a much stronger influence on each other. Depending on how the ports are connected or how the two ports are separated from each other within the cylinder head, the degree to which the aforementioned effects related to lower fuel consumption and higher output performance can be obtained varies greatly. come.

The present invention effectively achieves reduced fuel consumption in the low to medium speed range and high output performance in the high speed range in a Siamese port where one port is a helical port and the branching point of the two ports is inside the cylinder head. The purpose of the present invention is to provide a mutual isolation structure between two ports.

In order to achieve this object, in the intake system of the internal combustion engine of the present invention, the main intake port consisting of a helical port and the auxiliary intake port consisting of a straight port are connected to a Siamese port where the branching point of both ports is within the cylinder head. The main intake port and the sub-intake port are separated from each other by a partition wall extending from the downstream side to the upstream side of the Siamese port, and the upper part of the passage cross section of the Siamese port The partition wall extends for a long time to a position on the upstream side, and extends shorter toward the lower part of the passage cross section, and remains at a position on the downstream side. By adopting this configuration, the flow near the upper wall of the Siamese port is separated early by the partition wall and guided over a sufficient distance within the helical port, so that a strong flow is generated inside the combustion chamber in the low and medium speed range. It is possible to generate a swirl and reduce fuel consumption. In addition, the flow near the lower wall surface flows within a large cross section that includes the main and auxiliary intake ports up to the vicinity of the intake valve, so it is less susceptible to throttling resistance from the wall surface, and high volumetric efficiency can be ensured. The action is most effective in the high speed range, and can guarantee high output in the high speed range.

Preferred embodiments of the intake system for an internal combustion engine according to the present invention will be described below with reference to the drawings. 1 to 8 show an intake passage according to a first embodiment of the present invention. First, FIGS. 1 and 2 show the structure in the vicinity of the cylinder head. In the figures, 1 is the cylinder head, 2 is the cylinder bore, and the cylinder bore 2 is shown only its position by an imaginary line. In the area of the cylinder bore 2 there are two intake ports 3,
4 and one exhaust port 5 (there may be two exhaust ports), and each port 3,
4 and 5 are opened and closed by respective intake valves 6 and 7 and exhaust valves.

One of the two intake ports, that is, the main intake port 3, is longer than the other intake port, that is, the auxiliary intake port 4, has a larger passage cross-sectional area, and is formed in a helical shape. The sub-intake port 4 extends substantially straight. The auxiliary intake port 4 branches from the inner peripheral side of the helical shape of the main intake port, and its branching point 8 is located at the cylinder head 1.
Located within. Between the branch point 8 and the intake valves 6, 7, the two ports 3, 4 have no special throttle valves.

As shown in FIG. 3, the main intake port 3 consists of an introduction section 3a that extends almost straight and a spiral section 3b that extends downstream in series with the introduction section 3a.
b is bent downward at the end on the exit side,
The cylinder head opens into the combustion chamber recess 9 through a cylindrical portion having a circular cross section. The helical inner wall surface 10 of the main intake port 3 is directed toward the helical outer wall surface 12 as it approaches the upper wall surface 11 of the passage cross section of the main intake port 3 and as it goes downstream. The helical main intake port 3 has a flow path that narrows toward the upper part of the passage cross section and toward the downstream side. Further, the upper wall surface 11 of the main intake port 3 gradually descends as it goes downstream.

On the other hand, auxiliary intake port 4, which is a straight port,
As shown in FIG. 3, it branches from the introduction part 3a of the main intake port 3, extends almost straight, bends downward at the end, and connects to the opposite side of the spark plug 13 via a cylindrical part with a circular cross section. It opens into a lower flat surface 14 of the cylinder head which forms the upper surface of a large skid area. The upper wall surface 15 of the straight port 4 gradually descends toward the downstream.

The main intake port 3 and the sub-intake port 4 are connected to the partition wall 1
separated from each other by 6. As shown in FIG. 1, the partition wall 16 extends from the downstream side to the upstream side of the Siamese port, and the closer to the upper side of the passage cross section of the Siamese port, the closer to the Siamese port inlet 17, that is, the upstream position. It extends for a long time until the bottom of the cross section of the passage, and it extends for a shorter length toward the lower side of the passage cross section, and stays at a position on the downstream side. 4 to 6 show the extension of the partition wall 16 between the main intake port 3 and the sub-intake port 4 in the progression of the cross section from the upstream side to the downstream side of the Siamese port. As shown in the figure, on the upstream side, the partition wall 16 exists only at a portion close to the upper wall surface 11, and as it moves downstream, it exists at a position closer to the lower wall surface 18, and further downstream, both ports 3 and 4 are completely isolated. Therefore, when both ports 3 and 4 are viewed along a horizontal imaginary plane, they are as shown in FIGS. 7 and 8, and when viewed along the horizontal plane at the top of the cross section of the passage, as shown in FIG. The main intake port 3 and the auxiliary intake port are separated from each other from an upstream position, and when viewed along the horizontal plane at the bottom of the passage cross section, as shown in Figure 8,
The port passage has a large cross section including both the main and sub ports 3 and 4 up to the vicinity of the intake valve 7. In addition,
In the first embodiment, the upper wall surface 11 of the main intake port 3 and the upper wall surface 15 of the auxiliary intake port 4 are located at substantially the same height as each other in the separated position.

9 to 13 show an intake passage according to a second embodiment of the present invention. In this embodiment, the upper wall surface 15 of the sub-intake port 4 is provided at a lower position than the upper wall surface 11 of the main intake port 3,
The auxiliary intake port 4 communicates with a lower position in the passage cross section of the main intake port 3 via the partition wall 16. The other configurations are the same as the first embodiment,
Corresponding parts are given the same reference numerals as those in the first embodiment, and explanations regarding the configuration will be omitted.

Next, the effects of the first embodiment and the second embodiment will be explained.

First, the flow flowing in the upper part of the passage cross section of the Siamese port is early separated into the main intake port 3 side and the sub intake port 4 side because the partition wall 16 extends upstream at the upper part. Since the partition wall 16 bulges toward the outer circumferential wall surface 12 of the helical port, the intake air flowing into the main intake port 3 side is diverted toward the outer circumferential wall surface 12, and flows over a long distance toward the outer circumferential wall surface 12 of the helical port. Due to the throttle and the lowering of the upper wall surface 11, a swirling and descending force is applied while increasing the speed, and after entering the spiral portion 3b and generating a strong swirling flow there, it passes through the gap between the intake valve 6 and the valve seat. The gas then enters the combustion chamber, creating a powerful eddy current, so-called swirl. Further, the air flowing into the sub-intake port 4 side flows in a straight line, bends downward at the terminal end of the port 4, and is sucked into the combustion chamber. In this way, the flow in the upper part of the passage cross section, especially on the helical port 3 side, is
It is effective in generating swirl, but in the low and medium speed range of the engine, the flow resistance due to the helical shape is not so large, so a large amount of air-fuel mixture flows to the main intake port 3 side, which reduces the stability of combustion due to the generation of swirl. As a result, the lean limit of the mixture ratio can be further improved to the lean side, and fuel efficiency can be improved.

On the other hand, since the partition wall 16 has retreated downstream, the flow flowing in the lower part of the passage cross section of the Siamese port flows within the large cross section of the main and sub intake ports until it reaches the vicinity of the intake valve 7 of the sub intake port 4. It is not until it reaches around 7 that it separates and flows into the combustion chamber. Moreover,
On the main intake port 3 side, the lower part of the passage cross section is not as constricted as the upper part, so the speed increase and the flow along the helical outer peripheral surface are relaxed, and the swirling flow as strong as the upper part does not occur. Therefore, the flow resistance and restriction resistance due to the swirling flow are small, and the viscous resistance of the partition wall surface is also small, which is effective in securing the intake air flow rate and achieving high filling.
Therefore, in the high-speed range of the engine, the amount of intake air increases, and as a result, the flow resistance of the flow flowing through the upper end of the Siamese port, especially the upper end on the helical port side, increases and the rate of flow passing through the passage decreases. Since the lower portion secures the intake flow rate as described above, high output performance can be obtained even in the high speed range.

As described above, when using the intake system of the internal combustion engine of the present invention, the structure of the partition wall effectively makes the flow action different between the upper and lower passage cross sections of the Siamese port. The flow in the upper part of the engine ensures the generation of a strong swirl, and by improving the lean limit, it is possible to improve fuel efficiency, and in the high-speed range, the flow in the lower part of the engine allows high volumetric efficiency to be obtained, maintaining high output performance. can do.

In addition, other general effects can naturally be obtained by using the Siamese port structure within the cylinder head. For example, compared to two independent ports, there are fewer partition walls, which reduces fuel adhesion to the wall surface, reduces the release of unburned hydrocarbons, and improves drivability. Furthermore, compared to two independent ports, the space occupied by the water jacket on the upper surface of the combustion chamber wall can be increased, and fuel efficiency can be achieved by improving the cooling effect and the concomitant knock limit. Furthermore, by using Siamese, an integral core can be used during manufacturing, improving the manufacturing accuracy of the combustion chamber port arrangement and suppressing variations in performance of mass-produced engines.

[Brief explanation of the drawing]

1 is a longitudinal sectional view of an intake system of an internal combustion engine according to a first embodiment of the present invention, FIG. 2 is a plan view of the intake system of FIG. 1, and FIG. FIG. 4 is a vertical sectional view of the Siamese port taken along the - line in FIG. 1, FIG. 5 is a longitudinal sectional view of the Siamese port taken along the - line in FIG. 1, and FIG. The figures are a longitudinal sectional view of the Siamese port taken along the - line in Fig. 1, Fig. 7 is a cross-sectional view of the Siamese port at the upper part of the passage cross-section, Fig. 8 is a cross-sectional view of the Siamese port at the lower part of the passage cross-section, and Fig. 9 10 is a longitudinal cross-sectional view of an intake system of an internal combustion engine according to a second embodiment of the present invention, FIG. 10 is a perspective view showing only the Siamese port in FIG. 9, and FIG.
Fig. 12 is a vertical cross-sectional view of the Siamese port along the line XI-XI in Fig. 9, Fig. 13 is a longitudinal cross-sectional view of the Siamese port along the - line in Fig. 9. Longitudinal cross-sectional view of
It is. 1... Cylinder head, 3... Main intake port,
3a... Introduction part, 3b... Spiral part, 4... Sub-intake port, 6... Intake valve, 7... Intake valve, 8... Branch point, 10... Main intake port inner peripheral side wall surface, 11...
...Main intake port top wall surface, 12...Main intake port outer peripheral side wall surface, 15...Sub-intake port top wall surface, 16...
...Bulkhead, 17...Siamese Port entrance.

Claims (1)

[Claims] 1 A main intake port consisting of a helical port and a sub-intake port consisting of a straight port are configured into a Siamese port where the branch point of both ports is inside the cylinder head, and the inside of the Siamese port that separates the main intake port and sub-intake port is connected from downstream. An intake system for an internal combustion engine, characterized in that a partition wall extending upstream is extended upstream toward the upper part of the passage cross section of a Siamese port, and is extended shorter toward the lower part of the passage cross section.