JPS6350531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of an intake passage of an internal combustion engine employing a dual intake system.

[Prior Art] Conventionally, a motor is provided with a first intake port and a second intake port, and the first intake port is configured to have a larger flow path area than the second intake port, and is used as a main intake port.
The main intake port is formed in a helical shape, and the second
A throttle valve is installed in the sub-intake port of the intake port, and with this structure, the throttle valve is fully closed in the engine low and medium speed range, and intake air is supplied to the combustion chamber through the helical-type main intake port. A strong swirl is generated within the combustion chamber to ensure stable combustion, while at engine high speeds the throttle valve is fully opened to supply intake air into the combustion chamber from both the main intake port and the auxiliary intake port. By doing so,
Internal combustion engines have been proposed that achieve high output by increasing charging efficiency (for example, Japanese Patent Application Laid-Open No. 1986-
Publication No. 112308, Japanese Patent Application Publication No. 1984-84127, Publication No. 1984-84127, Japanese Patent Application Publication No.
54-95816). Providing a throttle valve in this type of intake passage increases the flow resistance of intake air and complicates the structure, so in order to improve this, the throttle valve was removed (for example,
Publication No. 26281, Japanese Patent Publication No. 48-40606, Japanese Patent Publication No. 1973
A structure of an intake passage consisting of two independent ports has already been proposed (for example, Japanese Patent Laid-Open Nos. 1983-69721 and 1983-1989).
Publication No. 148229).

[Problems to be Solved by the Invention] However, in the above conventional dual intake port in which the main intake port is a helical port, and the structure of the intake passage without a throttle valve, it is possible to reduce the In order to prevent the flow from being biased toward the auxiliary intake port in the high speed range, the main intake port and the auxiliary intake port were configured as independent intake passages, and for this reason, independent cores were used in the manufacture of the intake passages. However, there is a problem in that the manufacturing precision inevitably deteriorates, and in the case of mass production, variations in the manufacturing precision may cause variations in performance.

In addition, in the case of two independent ports, the passage wall area becomes large and the amount of fuel adhering to the wall increases, so it is necessary to consider reducing the release of unburned hydrocarbons and improving drivability. Since the intake passage in the head occupies a large space, there was also the problem that it was necessary to consider improving the cooling performance of the combustion chamber.

Also, Special Publication No. 40-26281, Special Publication No. 48-
40606, Japanese Patent Application Laid-Open No. 54-57007, etc.
When at least one of the two intake ports is opened tangentially to the combustion chamber to generate a swirl within the combustion chamber, in order not to weaken the speed of the airflow flowing into the combustion chamber, it is necessary to The port must open diagonally into the combustion chamber, and there is not enough space for a water jacket between the port and the bottom surface of the cylinder head, and the bottom surface of the cylinder head cannot be cooled sufficiently, making knocking more likely to occur. There were issues such as this.

The present invention makes it possible to use an integrated core in order to eliminate such variations in manufacturing accuracy, and also reduces the passage wall area compared to two independent ports.
To provide an intake passage which can reduce the space occupied by the intake passage and also provide a sufficient space for installing a water jacket between an intake port and the lower surface of a cylinder head.

Furthermore, the present invention provides an intake passage that ensures sufficient flow to the helical port in the low and medium speed range even in an intake passage that is manufactured using the above-mentioned integrated core and has a compact passage. Another purpose is to provide structure.

[Means for Solving the Problems] In order to achieve these objects, in the intake passage of the internal combustion engine of the present invention, the axis of the introduction part and the spiral constituting the intake passage is arranged downward from the introduction part. It has a spiral part that is bent and extended into a spiral shape,
The main intake port consists of a helical port that itself generates a swirling flow, and the sub-intake port consists of a straight port that extends almost horizontally in a straight line and then bends downward and extends in a straight line. A Siamese port is formed, and a branch of the Siamese port is located within the cylinder head. Further, the intake manifold connected to the Siamese port is oriented toward the outer periphery of the helical port shape of the main intake port at the outflow portion to the Siamese port.

[Function] In this structure, the Siamese port configuration in the cylinder head makes it possible to use an integrated core in which the core for making the main intake port is integrated with the core for making the auxiliary intake port, and to make the port more compact. , improves manufacturing accuracy, reduces unburned hydrocarbons, and improves drivability.

Furthermore, by adopting the inflow directional shape, sufficient flow to the helical main intake port is ensured in the low and medium speed range even with a Siamese port configuration in which the ports branch within the cylinder head.

Furthermore, the axis of the spiral of the spiral portion of the main intake port extends downward after being bent from the introduction portion;
The auxiliary intake port is also bent downward and extends downward, allowing for sufficient space for installing a water jacket between the intake port and the bottom surface of the cylinder head. Knocking can be suppressed by proper cooling. The reason why the main intake port can be provided with such a downwardly extending portion is because the main intake port of the present invention is a helical port that has a spiral portion and can generate a swirling flow by itself. This is because there is no need to open diagonally into the combustion chamber; conventional ports, which open tangentially to the combustion chamber and diagonally when viewed vertically, do not require such sufficient space for installing a water jacket. Can not.

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

1 and 2 show an intake passage according to a first embodiment of the present invention. In the figure, 1 is the cylinder head, and 2 is the cylinder bore of each cylinder, which is shown by imaginary lines in FIG. This cylinder bore 2
Two intake ports 3 and 4 (main intake port 3, auxiliary intake port 4) and one exhaust port 5 (there may be two exhaust ports) are opened in the inner area, and each port 3, 4, and 5 are opened and closed by intake valves 6, 7, and exhaust valve 8, respectively. Note that the intake valve 7 of the auxiliary intake port 4 has a smaller diameter than the intake valve 6 and exhaust valve 8 of the main intake port 3.

One of the two intake ports (main intake port) 3 has a passage cross-sectional area larger than the other intake port (sub-intake port) 4, and is formed in a helical port shape. More specifically, the main intake port 3 has a substantially linear introduction portion 3 on the inlet side.
a, and an exit side spiral part 3b whose spiral axis is bent from the downstream end of the introduction part 3a and extends downward, a passage is formed in a spiral shape around the valve axis, and opens into the combustion chamber at the lower end. It's summery. The auxiliary intake port 4 extends substantially horizontally in a substantially straight line, is further bent downward, and extends substantially linearly downward to open into the combustion chamber. The auxiliary intake port 4 is the introduction part 3 of the main intake port 3
The intake ports 3 and 4 are branched into twins from the inner peripheral side of a, and the two intake ports 3 and 4 are Siamese ports. The two intake ports 3 and 4 are separated by a partition wall 9, and the starting position of the partition wall 9, that is, the branching part 10 between the main intake port 3 and the sub-intake port 4, is inside the cylinder head 1, and is located in the Siamese cylinder head. It is located at a position closer to the combustion chamber than the inlet portion 11 of the port. The upper wall surface 12 of the main intake port 3 is gradually lowered as it goes downstream from the inflow portion 11. Further, the wall surface 13 of the partition wall 9 that constitutes the inner peripheral wall surface of the helical port bulges toward the outer peripheral wall surface 14 of the helical port shape as it approaches the upper wall surface 12 and as it goes downstream, that is, the main intake port 3 The flow path becomes narrower at the top and downstream. At the exits of ports 3 and 4, both ports open substantially downward into the combustion chamber. Since the ports 3 and 4 have portions extending downward, the water jacket extends into the space inside the cylinder head between the ports 3 and 4 and the lower surface of the cylinder head, and the lower surface of the cylinder head is fully occupied. It's starting to cool down. The main intake port 3 and exhaust port 5 are located in the cylinder head combustion chamber recess 1.
5, and the auxiliary intake port 4 is connected to the combustion chamber.
For example, it opens into a flat squeezing area 17 which preferably has a large area and is located opposite the spark plug 16. Note that the throat diameter of the auxiliary intake port 4 is set smaller than the throat diameter of the main intake port 3. 18, 19, and 20 are valve stem guides for each port 3, 4, and 5, respectively. Note that the inflow section 11 of the Siamese port is connected to one outflow section 22 of the intake manifold 21. Each outflow portion of the intake manifold 21 is oriented toward the outer periphery of the helical port shape of the main intake port 3 . (Specific means for directing the inflow will be explained in the second and third embodiments described later.) Next, the operation in the intake passage according to the first embodiment configured as described above will be explained. First, regarding manufacturing, the Siamese port manufacturing core 30 is one in which a main intake port manufacturing part 31 and a sub-intake port manufacturing part 32 are integrally formed, as shown in FIG. can be used, and there is no need to use separate cores.
Therefore, manufacturing accuracy is improved and variations in performance in mass-produced engines are suppressed. By adopting this structure, the dual port is significantly more compact than the conventional two independent ports.

In addition, since the main intake port 3 and the auxiliary intake port 4 extend downward on the opening side to the combustion chamber, a water jacket can be installed between the ports 3, 4 and the lower surface of the cylinder head. Sufficient space can be taken up, the lower surface of the cylinder head can be sufficiently cooled, and the occurrence of knocking can be effectively prevented.

Regarding the flow in the intake passage, in the low to medium speed range, the main intake port 3 has a larger cross-sectional area than the sub-intake port 4, as the intake air flows from the intake manifold 21 to the Siamese port that branches within the cylinder head. Because of this and the fact that each outflow portion 22 of the intake manifold 21 is oriented toward the outer circumferential side of the helical shape of the main intake port 3, a large amount of air tends to flow toward the main intake port 3. The intake air flowing into the main intake port 3, which is a helical port, is accelerated because the flow path gradually narrows at the introduction part 3a, and because the upper wall surface is gradually lowered, a downward force is applied to the spiral part 3b. It flows into the combustion chamber through the gap formed between the main intake valve 6 and its valve seat, generating a strong swirling flow therein, and generates a strong swirling flow inside the combustion chamber. This stabilizes combustion, improves the lean limit, and promotes lower fuel consumption.

On the other hand, at high speeds, the flow rate of intake air flowing through the Siamese port increases, but the flow resistance due to the helical shape of the main intake port 3 gradually increases, and the proportion of flow flowing into the auxiliary intake port 4 of the straight port, where resistance increases less, increases. increases, ensuring high filling efficiency and maintaining high output performance.

FIG. 3 shows an intake passage according to a second embodiment of the invention. In this embodiment, the intake passage described in the first embodiment is applied as is, and the structure of the intake manifold connected to the inlet side of the Siamese port is distinctive. In Fig. 3, an intake manifold 2 is connected to the inflow section 11 of the Siamese port.
One outlet 22 of 1 is connected. The intake manifold outflow portion 22 has an upper wall surface 23, a lower wall surface 24, and side wall surfaces 25, 26. Among the side wall surfaces 25, 26, the side wall surface 25 that is continuous with the helical port-shaped outer peripheral side wall surface 14 of the Siamese port is a Siamese port. It is smoothly connected to the outer peripheral side wall surface of the port inflow section 11. However, among the side wall surfaces 25 and 26 of the intake manifold outflow portion 22, the inner peripheral wall surface 26 corresponding to the extension of the inner peripheral wall surface 13 of the helical port shape of the Siamese port gradually faces the opposing side wall surface 25 toward the downstream side. A bulging portion 27 is formed that protrudes from the intake manifold 21 and the cylinder head 1.
A step 28 is formed by the downstream end surface of the bulge 27 at the boundary between the bulge 27 and the bulge 27 .

In the second embodiment configured in this way,
The intake air flowing from the intake manifold 21 into the Siamese port in the cylinder head is further directed toward the main intake port 3 side by the bulge 27 on the inner circumferential side wall surface 26 of the intake manifold outlet 22, and the flow is directed toward the main intake port 3 side. Strongly directed toward the outer periphery. Therefore, the swirling flow within the combustion chamber in the low and medium speed range is further strengthened by the presence of the bulge 27, thereby further improving the lean limit and promoting fuel efficiency. Note that in the high speed range, the flow resistance of the main intake port 3 which is a helical port increases, but high volumetric efficiency (high filling effect) is not achieved by the auxiliary intake port 4 which is a straight port as in the first embodiment. As a result, high output can be obtained. In a high-speed range where the intake air flow is fast, the negative pressure generated in the stagnation part of the flow immediately downstream of the step part 28 becomes large, and the effect of bending the flow toward the sub-intake port 4 side becomes stronger due to the Coanda effect. Therefore, the flow rate on the side of the sub-intake port 4 increases, and it is possible to further improve the filling efficiency.

FIG. 4 shows an intake passage according to a third embodiment of the present invention. This embodiment differs from the second embodiment in the structure of the intake direction of the flow from the intake manifold to the Siamese port. In FIG. 4, the central axis 33 of the outflow section 22 of the intake manifold 21 is directed toward the outer peripheral wall surface 14 of the helical port shape of the main intake port 3 with respect to the central axis 34 of the Siamese port inflow section 11. , central axis 3
3 and 34 are bent and intersect with each other at the boundary between the intake manifold 21 and the cylinder head 1.
With this structure, the intake air flowing from the intake manifold 21 to the Siamese port inflow section 11 is directed so as to flow strongly toward the main intake port 3, which is a helical port. This promotes the generation of swirling flow within the combustion chamber by the main intake port 3 in the low and medium speed range. Other configurations and operations are similar to those in the first and second embodiments, so similar parts are designated by the same reference numerals as in FIGS. 1 to 3 and their explanation will be omitted.

[Effects of the Invention] As described above, the following effects can be obtained by using the intake passage of the internal combustion engine of the present invention.

First, in a dual intake system, by using the Siamese port method that branches within the cylinder head, it is possible to use an integrated core in which the core for making the main intake port and the core for making the auxiliary intake port are integrated, and the port in the combustion chamber This improves the manufacturing precision of the layout and reduces performance variations in mass-produced engines.

Therefore, accurate intake control is possible in order to extend the combustible air-fuel ratio limit to the lean side, and it is possible to contribute to low fuel consumption by improving the lean limit.

Also, because it is a Siamese port,
Compared to two independent ports, there are fewer partition walls and the inner wall area of the port can be reduced, so the amount of fuel adhering to the wall can be reduced, reducing unburned hydrocarbons and improving drivability.

In addition, the main intake port that generates a swirling flow in the combustion chamber itself has a swirling part that generates a strong swirling flow, so it is necessary to open the main intake port vertically diagonally into the combustion chamber. Since the spiral part can be opened into the combustion chamber by extending its axis downward, and the auxiliary intake port also opens into the combustion chamber through the downwardly extending part, the connection between the port and the lower surface of the cylinder head is In the meantime, more space can be secured in the cylinder head for arranging the water jacket, further preventing knocking and further improving fuel efficiency.

Furthermore, the shape of the intake manifold is oriented toward the helical main intake port side of the Siamese port, which increases the intake control effect of the main intake port, especially in low speed and low load ranges, and improves combustion stability and flammability. It is possible to expand the range (especially the lean range) and improve fuel efficiency.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of an intake passage of an internal combustion engine according to the present invention, FIG. 2 is a cross-sectional view of an intake passage of an internal combustion engine according to a first embodiment of the present invention, and FIG. 3 is a cross-sectional view of an intake passage of an internal combustion engine according to a first embodiment of the present invention. Cross-sectional view of an intake passage of an internal combustion engine according to an example, No. 4
The figure is a cross-sectional view of an intake passage of an internal combustion engine according to a third embodiment of the present invention, and FIG. 5 shows an example of a core that can be used for manufacturing the Siamese port part of the intake passage of an internal combustion engine of the present invention. It is an enlarged perspective view. 1...Cylinder head, 2...Cylinder bore,
3...Main intake port (helical port), 3a...
...Introduction part, 3b...Swirl part, 4...Sub-intake port (straight port), 5...Exhaust port, 6,7
...Intake valve, 8...Exhaust valve, 9...Bulkhead, 10...
...branch part, 11...Siamese port inflow part,
12... Main intake port upper wall surface, 13... Main intake port inner peripheral side wall surface, 14... Main intake port outer peripheral side wall surface, 15... Combustion chamber recess, 16... Spark plug, 17... Squeeze area, 21...Intake manifold, 22...Intake manifold outlet, 27
...Bulging part (projection part), 28... Step part, 30...
Middle child.

Claims (1)

[Scope of Claims] 1. It has an introduction part that extends in a substantially straight line and a spiral part whose axis is bent from the downstream end of the introduction part, extends downward, and is formed in a spiral shape around the valve axis. An intake passage for an internal combustion engine having a main intake port consisting of a helical port and a sub intake port consisting of a straight port extending substantially horizontally in a substantially straight line and further bent downward and extending linearly,
The main intake port and the auxiliary intake port are configured as a Siamese port with a branching portion of both within the cylinder head, an inflow port of the Siamese port is connected to an outflow portion of the intake manifold, and the outflow portion of the intake manifold is connected to the inlet port of the Siamese port. An intake passage for an internal combustion engine, characterized in that the inflow is directed toward the outer periphery of a helical main intake port. 2. The inflow direction of the outflow portion of the intake manifold is
Intake of an internal combustion engine according to claim 1, wherein intake is performed by a bulge formed on a side wall surface that is continuous with an extension of the helical inner peripheral side wall surface of the main intake port in the intake manifold outlet part. aisle. 3. The inflow of the intake manifold outlet is directed by directing the passage center axis of the intake manifold outlet toward the helical outer wall surface of the main intake port. Intake passage of internal combustion engine.