JPS6350532B2 - - Google Patents

Description

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

[Conventional technology] In order to achieve both low fuel consumption and high output performance in internal combustion engines for automobiles, an internal combustion engine has been developed in which the intake ports are independent dual ports, one of which is a helical port and the other is a straight port. The institution has already been proposed.

By the way, when adopting the dual intake port system, it is necessary to reduce the area of the passage wall to reduce the amount of fuel adhering to the wall surface, reduce the amount of unburned hydrocarbons released, and improve driveability. In order to reduce the space occupied by the passage and facilitate cooling of the combustion chamber, it is desirable to construct both ports into so-called Siamese ports, which are twin ports that diverge from each other within the cylinder head (for example, Publication No. 48-40606,
(Japanese Patent Publication No. 40-26281, Japanese Patent Publication No. 55-19901).

[Problems to be Solved by the Invention] With a dual port, compared to two independent ports, or compared to a case where a throttle valve is provided on at least one of the ports, the mutual influence of the two ports is much greater. Depending on how the two ports are related to each other and the structure of each port, swirl and microturbulence can be generated, and the resulting reduction in fuel consumption, high output performance, and aperture can be achieved. The degree to which various effects, such as the possibility of eliminating valves and the accompanying simplification of the system, are achieved differs greatly.

For more details, see the above-mentioned Japanese Patent Publication No. 48-40606,
If the main and sub ports are oriented tangentially in the same direction to the combustion chamber, as in the Siamese port disclosed in Japanese Patent Publication No. 40-26281, the collision between the flows from both ports will be insufficient and the piston top The collision speed with the surface also becomes small, and the generation of microturbulence becomes insufficient. In addition, the above-mentioned Unexamined Patent Publication No. 55-
When the auxiliary port is opened diagonally in the vertical direction into the combustion chamber, as in the Siamese port of Publication No. 19901, the amount of intake air flowing into the combustion chamber from between the intake valve and the valve seat of the auxiliary port is increased in the diagonal direction. There are more and more
The amount of intake air introduced from the auxiliary port is uneven in the circumferential direction of the combustion chamber, resulting in a problem that microturbulence cannot be uniformly generated in the circumferential direction of the combustion chamber.

Additionally, if the squeezing area is located far from the spark plug to prevent the pilot flame from being blown out by the squishing, this squeezing area is at the end of the flame propagation, which can cause knocking. It is also desirable to have a structure that can effectively cool the squish area, which is likely to become a site where self-ignition occurs.

The present invention provides an intake valve provided in a sub-intake port and its valve seat in a Siamese port in which one port is a helical port and the other port is a straight port, and the branching point of the two intake ports is inside the cylinder head. The amount of intake air flowing into the combustion chamber through the gap is made uniform in the circumferential direction of the intake valve, and this intake air is caused to collide with the top surface of the piston near the bottom dead center at an angle close to a right angle to generate sufficient microturbulence. The primary objective is to generate microturbulence due to the flow from the sub-intake port without weakening the swirl generated by the flow from the main intake port. By generating lens and swirl, it is possible to effectively achieve low fuel consumption in the low-to-medium speed range and high output in the high-speed range, and maintain these effects even if the intake control valve is eliminated. An object of the present invention is to provide an intake device for an internal combustion engine that can simplify the system by eliminating a throttle valve.

A second object of the present invention is to provide an intake system for an internal combustion engine that cools a squish area by intake air from a sub-intake port.

[Means for Solving the Problems] In order to achieve this object, the intake system for an internal combustion engine of the present invention includes an introduction section extending substantially linearly, a spiral section connected to the introduction section and extending spirally, and a spiral section connected to the introduction section extending spirally. A main intake port consisting of a helical port having a cylindrical part connected to the spiral part and extending downward, and a sub-intake port consisting of a straight port extending almost linearly and further bent downward and extending linearly,
The branch point of both ports is configured into a Siamese port located within the cylinder head. Further, the outlet portion of the auxiliary intake port to the combustion chamber opens into a squish area located on the opposite side of the spark plug in a direction parallel to the top surface of the piston. Furthermore, the auxiliary intake port has an outlet portion (a portion that bends downward and then extends downward) into the combustion chamber that is a straight portion where the port centerline and the entire inner circumferential wall surface extend linearly in the axial direction of the outlet portion. It is formed into a cylindrical shape.

[Function] With this structure, the intake air that flows through the main intake port becomes a swirling flow while passing through the main intake port, enters the combustion chamber, generates a swirling flow in the combustion chamber, and then flows through the auxiliary intake port. By passing through the cylindrical outlet section with a straight section, the intake air flow direction is essentially directed downward, and the annular gap between the valve and the seat allows for uniform combustion without being biased around the valve. Air flows out into the chamber in an umbrella shape at an angle of approximately 45 degrees with the valve axis (because the angle of the back of the valve umbrella is approximately 45 degrees to allow intake air to flow out).
Pulled by the movement of the descending piston, the umbrella-shaped flow is changed into a flow that goes downward in the direction of the bore axis (in a direction perpendicular to the top surface of the piston), and the center of the initial umbrella-shaped flow is centered around the bore. By colliding with the top surface of the piston near the bottom dead center of the piston, a large amount of microturbulence is generated almost uniformly in the circumferential direction, and the upward movement of the piston moves this sufficient amount of microturbulence upward. push up to
This swirling flow and minute turbulence improves combustion and fuel efficiency, and even if the throttle valve is eliminated and swirl generation is weakened, the presence of minute turbulence still provides good performance, making it possible to eliminate the intake control valve. It becomes possible.

In addition, since the sub-intake port opens into the squish area, the intake air from the sub-intake port (the intake air is at a low temperature) directly cools the squish area, thereby suppressing the occurrence of knocking.

[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 the cylinder head, 2 is the cylinder bore, and within the area of the cylinder bore 2, there are two intake ports 3 and 4 (main intake port 3 and auxiliary intake port 4) and one exhaust port 5 (the exhaust port is two Each port 3, 4, 5 is opened and closed by an intake valve 6, 7 and an exhaust valve, respectively. The throat area of the auxiliary intake port 4 is smaller than the throat areas of the main intake port 3 and the exhaust port 5.

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, and has a larger passage cross-sectional area.
Moreover, it is formed in a helical shape (shape to be described later). The auxiliary intake port 4 extends substantially straight (straight in the sense that it has a portion that extends substantially horizontally and a portion that extends substantially straight downward, as will be described later, but does not have a spiral portion). 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 valve or intake control valve.

As shown in FIGS. 3 and 4, the main intake port 3 includes an introduction section 3a extending almost straight, and a spiral section connected to the introduction section 3a in which the axis of the spiral extends substantially downward and the passage is spiral. 3b, and a relatively short cylindrical portion 3c extending substantially downward from the terminal end of the spiral portion 3b with respect to the bore axis, and opens into the combustion chamber recess 9 at the lower end of the cylindrical portion 3c. There is.
Helical inner wall surface 10 of main intake port 3
bulges out toward the helical-shaped outer peripheral side 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 closer to the wall surface 11 or downstream, the narrower the flow path becomes. 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 FIGS. 3 and 4, it branches from the introduction part 3a of the main intake port 3, extends almost horizontally and almost straight at the straight part 4a, and bends downward at the end. A hollow cylindrical shape having a circular cross section with a diameter longer than that of the cylindrical part 3c of the main intake port 3, and a straight part whose central axis and the entire inner peripheral wall surface extend along a straight axis in the axial direction (the axial direction of the outlet part). The outlet part 4b is formed and extends downward parallel or almost parallel to the central axis of the cylinder bore 2, defining the upper surface of a large squish area located on the opposite side of the spark plug 13 when viewed in a direction parallel to the top surface of the piston. The lower end of the cylinder head is open to a flat surface 14. This relatively long cylindrical outlet section 4b is narrowed down to a slightly smaller diameter in the middle, so that the speed can be increased slightly. The intake valve 7 is provided in the opening, and intake air flows into the combustion chamber through a gap between the intake valve 7 and the valve seat. The shape of the umbrella portion 7a of the intake valve 7 is such that intake air flows into the combustion chamber at an angle of about 45 degrees. Note that the upper wall surface 15 of the horizontally extending straight portion 4a of the sub-intake port 4 gradually descends as it goes downstream.

The auxiliary intake port 4 is separated from the main intake port 3 by a partition 16, but in this case, the port is arranged so that the upper wall surface 15 of the auxiliary intake port 4 is at a lower position than the upper wall surface 11 of the main intake port 3. separated by 16. The partition wall 16 extends toward a position closer to the Siamese port inlet 17 toward the upper side of the passage cross section of the Siamese port, that is, toward the upstream side, and recedes toward the downstream side toward the lower side of the passage cross section. 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 are separated from each other at the lower position of the cross-section of the passage on the downstream side. The difference in height between the upper wall surfaces 11 and 15 of both ports 3 and 4 and the partition wall 1
6, the auxiliary intake port 4 branches from the main intake port 3 at a low portion of the passage cross section of the main intake port 3, that is, at a portion along the lower wall surface of the main intake port 3 and where the partition wall 16 is present. Therefore, there is communication below that point. Note that 19 is a fuel injection valve.

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

First, the intake air flowing into the Siamese port is separated from the main intake port 3 and the sub-intake port 4 by the partition wall 16.
It is separated into two parts and flows into the combustion chamber.

In the main intake port 3, the flow along the upper wall surface 11 is directed toward the outer circumference because the side wall surface of the partition wall 16 that constitutes the helical inner circumference side wall surface 10 bulges toward the helical-shaped outer circumference side wall surface 12. It drifts to the side, is given a swirling and descending force while being accelerated by the flow restriction and the lowering of the upper wall surface 11, and after entering the spiral portion 3b and generating a strong swirling flow there,
The air enters the combustion chamber through the gap between the intake valve 6 and its valve seat, generating a powerful swirling flow, so-called swirl. In the low and medium speed range, the increase in resistance due to the swirling flow is not so large, so a large amount of intake air flows through the main intake port 3, and therefore combustion is stable in the low and medium speed range, improving the lean limit and achieving low fuel consumption. development is promoted. The flow along the lower wall surface 18 of the main intake port 3 is throttled less than the flow along the upper wall surface 11, and the sub-intake port 4 has a partition wall 18.
6 Since it communicates over a certain distance below,
Swirl generation does not contribute to the flow along the upper wall surface 11, but when the flow becomes high speed and the flow resistance at the upper part of the passage cross section increases, a portion of the flow flows toward the sub-intake port 4 side. Since it flows into the combustion chamber through the air flow, it contributes more to maintaining the amount of inflow air than the flow along the upper wall surface 11, and in order to ensure the amount of inflow and enable high charging efficiency, especially in the high speed range, Work effectively.

The auxiliary intake port 4 also contributes to ensuring high output in the high speed range. In other words, even if the flow resistance on the main intake port 3 side increases due to the helical shape in the high speed range, the flow resistance of the straight port auxiliary intake port 4 does not increase as much as the main intake port 3. In this case, the secondary flow flowing from the lower cross section of the main intake port 3 to the sub-intake port 4 through the lower part of the partition wall 16 increases, and the amount of intake air flowing through the sub-intake port 4 increases, resulting in high volumetric efficiency and high output. is ensured.

Intake air flowing into the auxiliary intake port 4 passes through the straight part 4a, is bent downward at its terminal end, flows into the cylindrical outlet 4b, where it becomes a nearly vertical downward flow, and flows between the intake valve 7 and its valve seat. It flows into the combustion chamber through the gap. This cylindrical outlet section 4
b is relatively long, so by passing through it, the flow does not flow in a biased direction at the lower end of the outlet section 4b, but becomes an almost uniform flow over the entire cross section of the lower end of the outlet section 4b, and from around the intake valve 7. The flow flows almost uniformly around the intake valve axis, forming a conical flow of approximately 45 degrees along the valve face. Since this flow hits the swirling flow that entered the combustion chamber through the main intake port 3, which is a helical port, and the swirling flow induced by this swirling flow from above, it does not weaken the swirl. In addition, the flow flowing in from the auxiliary intake port 4 is pulled downward in the combustion chamber as the piston moves downward, and turns into a downward flow that is almost perpendicular to the top surface of the piston, and when the piston moves upward, A flow with downward inertia collides with the top surface of the piston at a nearly right angle and therefore at maximum velocity, generating a large amount of minute turbulence called microturbulence near the bottom dead center of the piston. The swirl and micro-turbulence are lifted in accordance with the upward movement of the piston without substantially reducing the strength of the swirl and micro-turbulence, and are ignited by the ignition of the spark plug 13 and burned. Due to the presence of this minute turbulence, combustion is sufficiently stabilized, combustibility and fuel efficiency are improved, and there is no need to use two independent ports or a control valve such as a throttle valve on at least one of the dual ports. Even without it, sufficient combustion stability is obtained and the throttle valve can be eliminated in the Siamese port configuration in the cylinder head.

In addition, since the auxiliary intake port 4 opens into the squish area, the squish area that is prone to self-ignition, which normally causes knocking, is directly cooled with low-temperature intake air, and the squish area is defined. This effectively prevents the occurrence of knotting by cooling the wall surface where it is located.

[Effects of the Invention] As described above, when using the intake system for an internal combustion engine of the present invention, the outlet portion of the sub-intake port is
Center line and all inner circumferential walls (all inner circumferential walls of straight sections)
is formed into a cylindrical shape with a straight part extending linearly in the axial direction of the outlet, so the flow from the sub-intake port becomes almost uniform around the axis of the intake valve provided at the sub-intake port and flows into the combustion chamber. This flow is pulled by the descending piston and becomes a flow in the axial direction of the bore, and its center is brought to the center of the bore, and the swirl from above is generated in the combustion chamber by the swirling flow that has flowed through the main intake port. Since it collides at a right angle, it does not weaken the swirl, and it collides at maximum speed because it is almost perpendicular to the piston top surface near the bottom dead center of the piston, and therefore does not have an oblique component, effectively generating a large amount of microturbulence. This undiminished swirl and a large amount of microturbulence can be pushed up by a piston, ignited by a spark plug, and combusted, thus improving the lean limit, stabilizing and improving combustion, and improving fuel efficiency. . Furthermore, by using a straight port as the auxiliary intake port, high output can be obtained even at high speeds. Furthermore, due to the unweakened swirl and a large amount of microturbulence, combustion can be stabilized even if the intake control valve is eliminated. Therefore, even if a Siamese port system is adopted that branches within the cylinder head, the intake control valve can be eliminated, simplifying the system and reducing flow resistance.

Furthermore, since the auxiliary intake port is opened to the squish area, the squish area can be directly and effectively cooled, and knocking can be prevented from occurring.

In addition, other effects can be obtained by adopting a Siamese port configuration that branches within the cylinder head. For example, the number of partition walls is reduced compared to the two independent ports, which reduces the amount of fuel adhering to the wall surface, reduces the release of unburned hydrocarbons, and improves drivability. Furthermore, compared to the 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, Siamese porting allows the use of an integral core during manufacturing, which also reduces variations in performance in mass-produced engines.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of the vicinity of a cylinder head equipped with an intake system of an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the cylinder head of FIG. 1, and FIG. 1 and 2, and FIG. 4 is a perspective view of the Siamese port shown in FIG. 3. 1... Cylinder head, 3... Main intake port (helical port), 3a... Introduction part, 3b... Spiral part, 4... Sub-intake port (straight port),
4a... straight part, 4b... cylindrical outlet part, 7...
...Intake valve, 10...Inner peripheral side wall surface of main intake port,
DESCRIPTION OF SYMBOLS 11... Upper wall surface of the main intake port, 12... Outer peripheral side wall surface of the main intake port, 16... Partition wall, 17... Siamese port inlet.

Claims (1)

[Claims] 1. A main intake port consisting of a helical port having an introduction part extending in a substantially straight line, a spiral part connected to the introduction part and extending in a spiral shape, and a cylindrical part connected to the spiral part and extending downward; A auxiliary intake port consisting of a straight port that extends and further bends downward to extend in a straight line is configured as a Siamese port with a branching point of both ports in the cylinder head, and an outlet portion of the auxiliary intake port to the combustion chamber is configured. An opening is made in the squeezing area located on the opposite side of the spark plug in a direction parallel to the top surface of the piston, and the outlet part of the sub-intake port to the combustion chamber is arranged so that the center line and the entire inner circumferential wall surface are aligned with the outlet part axis. An intake device for an internal combustion engine, characterized in that it is formed into a cylindrical shape with a straight portion extending linearly in a direction.