JPS6350534B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of an intake device for an internal combustion engine.
In particular, it relates to the structure of an intake system that is a dual port and in which the branch point of the two ports is located within the cylinder head.

[Prior art] In order to achieve both low fuel consumption and high output performance at high speeds and high loads in internal combustion engines for automobiles, the intake ports are made into mutually independent dual ports, with one being a helical port and the other being a straight port. Port-configured internal combustion engines have already been proposed.

[Problems to be Solved by the Invention] By the way, when adopting the dual intake port system, it is necessary to reduce the passage wall area to reduce the amount of fuel adhering to the wall surface, thereby reducing the amount of unburned hydrocarbons released and improving drivability. In order to improve engine performance and to reduce the space occupied by the intake passage in the cylinder head to facilitate cooling of the combustion chamber, both ports are configured as twin ports, so-called Siamese ports, which are branched from each other within the cylinder head. It is hoped that 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 they are related to each other, the degree to which the above-mentioned effects related to lower fuel consumption and higher output performance can be obtained differs greatly.

The present invention provides a Siamese port in which one intake port is a helical port and the other is a straight port, and the branching point of the two intake ports is inside the cylinder head, which reduces fuel consumption in the low-to-medium speed range and improves high output in the high-speed range. The purpose is to provide an interconnection structure between two intake ports such that performance is effectively achieved.

[Means for Solving the Problems] In order to achieve this object, in the intake system for an internal combustion engine of the present invention, a main intake port consisting of a helical port and a sub-intake port consisting of a straight port are branched from both ports. A point is configured in the Siamese port inside the cylinder head,
The auxiliary intake port is branched from the main intake port such that the upper wall surface of the auxiliary intake port is at a lower position than the upper wall surface of the main intake port. Therefore, the auxiliary intake port is branched at a lower portion of the passage cross section of the main intake port.

[Function] By adopting this configuration, most of the flow along the upper wall surface of the main intake port, which plays an important role in swirl generation in the main intake port, which is a helical port, flows toward the main intake port and flows into the cylinder. The flow along the lower wall surface of the main intake port, which generates a strong swirl and has an important effect on the amount of incoming air, also flows to the side of the auxiliary intake port, which is a straight port with less resistance, and this effect occurs at high speeds. It is highly effective and enables high filling efficiency in the high speed range, and therefore high output.

[Embodiments] Hereinafter, preferred embodiments of the intake system for an internal combustion engine of the present invention will be described with reference to the drawings.

1 and 2 show a structure near a cylinder head equipped with an intake device according to an embodiment of the present invention. In the figure, 1 is a cylinder head, 2 is a cylinder bore, and only the position of the cylinder bore 2 is shown by an imaginary line. In the area of the cylinder bore 2, two intake ports 3, 4 and one exhaust port 5 (there may be two exhaust ports) are provided, and each port 3, 4, 5 has an intake valve, respectively. 6, 7 and an exhaust valve.

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

As shown in FIGS. 3 and 4, the main intake port 3 consists of an introduction section 3a that extends almost straight and a spiral section 3b that extends downstream.The axis of the spiral section 3b is aligned with the introduction section 3a. The portion 3a is bent downward from the downstream end and opens into the cylinder head combustion chamber recess 9 (see FIG. 1) through a cylindrical portion having a circular cross section. The helical inner peripheral side wall surface 10 of the main intake port 3 is
The closer you get to the upper wall surface 11 of the passage cross section, or the further downstream you go, the more it bulges out toward the helical outer wall surface 12 (see Figures 6 and 7). The flow path of the intake port 3 narrows closer to the upper wall surface 11 and downstream. In addition, the upper wall surface 11 of the main intake port 3
is gradually decreasing as it goes downstream. (1st
(See figure) On the other hand, auxiliary intake port 4, which is a straight port,
As shown in FIGS. 3 and 4, it branches from the introduction part 3a of the main intake port 3, extends almost horizontally and almost straight, bends downward at the end, and connects to the spark plug 13 through a circular section. It opens into a lower flat surface 14 of the cylinder head that defines the upper surface of a squish area with a large side surface area (see FIG. 1).
The upper wall surface 15 of the auxiliary intake port 4, which is a straight port, gradually descends toward the downstream (see FIG. 1). The auxiliary intake port 4 is separated from the main intake port 3 by a partition wall 16 (see FIGS. 1 and 2), but in this case, the upper wall surface 15 of the auxiliary intake port 4 is lower than the upper wall surface 11 of the main intake port 3. Low position (1st
The ports are arranged as shown in FIG. 4) and are separated by a partition wall 16. The partition wall 16 is
The upper part of the passage cross section of the Siamese port extends upstream to a position closer to the Siamese port inlet 17 (see FIG. 1), and the lower part of the passage cross section recedes downstream. Therefore, the main intake port 3 and the sub-intake port 4 are separated from each other at the upper part of the cross-section of the passage on the upstream side, and separated from each other at the lower position of the cross-section of the passage on the downstream side. And the upper wall surface 11 of both ports 3, 4,
15 and the structure of the partition wall 16,
The auxiliary intake port 4 branches from the main intake port 3 at a low part of the passage cross-section of the main intake port 3, that is, at a part along the lower wall surface of the main intake port 3, and communicates with the partition wall 16 below. There will be.

FIGS. 5 to 7 show the mutual positional relationship between the main intake port 3 and the sub-intake port 4 as the positions change from the upstream side to the downstream side.
As shown in the figure, the partition 16 extends from above to below, and the main intake port 3 and the sub-intake port 4 communicate with each other below the lower end of the partition 16. The communicating space becomes smaller as it goes downstream, and is eventually completely separated by the partition wall 16.
In the portion where the main intake port 3 and the sub-intake port 4 communicate with each other, the upper wall surface 15 of the sub-intake port 4
is located below the upper wall surface 11 of the main intake port 3,
The sub-intake port 4 communicates with the main intake port 3 at a lower portion of the passage cross section. The upper portion of the passage cross section of the main intake port 3 is a portion where the flow is directed toward the outer circumferential wall surface 12 due to the bulge of the partition wall 16.

Next, the operation of the intake system of the internal combustion engine having the above configuration will be explained.

The upper wall surface 15 of the sub-intake port 4 is connected to the main intake port 3
Since the sub-intake port 4 is branched from the main intake port 3 in a state below the top wall surface 11, the flow flowing along the top wall surface 11 of the main intake port 3 (therefore, the flow above the sub-intake port 4 There is a difference in action between the flow flowing above the wall surface 15) and the flow flowing along the lower wall surface 18 of the main intake port 3 (therefore, the flow flowing below the upper wall surface 15 of the sub-intake port 4). occurs. In other words, the flow along the upper wall surface 11 of the main intake port 3 cannot easily flow to the auxiliary intake port 4 because there is no auxiliary intake port 4 in the lateral direction in that part, and tends to flow through the main intake port 3 as it is. , it becomes a strong swirling flow in the swirl portion 3b and enters the combustion chamber, generating a swirl in the combustion chamber. This swirl improves combustion and improves fuel economy at all speeds: low, medium, and high. However, in the high-speed range, the resistance of the swirling flow in the spiral portion 3b increases, and in terms of filling efficiency, it is necessary to increase the filling efficiency by using another flow, that is, the flow along the lower wall surface 18 of the main intake port 3. .

The flow along the lower wall surface 18 of the main intake port 3 can easily flow to the auxiliary intake port 4 located in the lateral direction. By increasing the proportion of air flowing into the intake port 4, it is possible to suppress a decrease in the amount of intake air, ensure a sufficiently high filling efficiency even in a high speed range, and ensure a sufficiently high output in a high speed range.

In summary, the flow along the upper wall surface 11 of the main intake port 3 plays an important role in generating swirl, and
In medium and high speed ranges, most of the air flows through the main intake port 3, which is made up of helical ports, and generates a powerful swirl within the combustion chamber, contributing to improved combustion and lower fuel consumption.

The flow along the lower wall surface 18 of the main intake port 3 has an important effect on the amount of incoming air, and also flows to the side of the auxiliary intake port 4 where flow resistance is low in the high-speed range, improving filling efficiency and achieving high output performance. let

[Effects of the Invention] As described above, when using the intake system for an internal combustion engine of the present invention, the upper wall surface of the auxiliary intake port is made lower than the upper wall surface of the main intake port, and the auxiliary intake port is branched from the main intake port. This makes it possible to ensure a strong swirl in the combustion chamber over the entire speed range of low, medium, and high speeds, and to obtain high charging efficiency even in the high speed range. As a result, it is possible to improve the lean limit of the air-fuel mixture more than the conventional dual port, thereby achieving lower fuel consumption, and it is also possible to obtain higher output than the conventional one in the high speed range.

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, the number of partition walls is reduced, reducing the amount of fuel adhering to the wall surface, reducing the release of unburned hydrocarbons, and improving drivability. Furthermore, compared to two independent ports, the space occupied by the water jacket on the upper wall of the combustion chamber can be increased, and fuel efficiency can be achieved by improving the cooling effect and thereby improving the 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 for an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a plan view of the intake system of FIG. 1, and FIG. 3 is a Siamese port in FIGS. 1 and 2. A plan view showing only the
Figure 4 is a perspective view of the Siamese port in Figure 3;
Figure 5 is an enlarged sectional view of the Siamese port taken along the - line in Figure 1, Figure 6 is an enlarged sectional view of the Siamese port taken along the - line in Figure 1, and Figure 7 is taken along the - line in Figure 1. FIG. 2 is an enlarged cross-sectional view of a Siamese port. 1... Cylinder head, 3... Main intake port (helical port), 4... Sub-intake port (straight port), 8... Branch point, 9... Combustion chamber recess, 10... Inner peripheral side wall surface, 11 ... Upper wall surface of main intake port, 12 ... Outer peripheral side wall surface, 13 ... Spark plug, 14 ... Lower flat surface of cylinder head, 1
5... Upper wall surface of sub-intake port, 16... Bulkhead, 1
7...Siamese port entrance part, 18...Lower wall surface of main intake port.

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 branching point of both ports is inside the cylinder head, and the sub-intake port is configured such that the upper wall surface of the sub-intake port is connected to the main intake port. An intake device for an internal combustion engine, characterized in that the intake port is located at a lower position than the upper wall surface of the intake port and is branched from a main intake port.