JPS597539Y2 - Double intake internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a dual-intake internal combustion engine having a low-speed swirl port and a high-speed output port.

A swirl port is used as an intake port for an internal combustion engine to add swirl to the air-fuel mixture mainly in the low-to-medium speed range to improve combustion and achieve lean mixture or high-rate EGR;
In order to compensate for the significant drop in suction efficiency with only swirl ports in the high-speed range, the dual-intake type is equipped with an output port that has low intake resistance and therefore improves air-fuel mixture suction efficiency to ensure the specified full-open output. An internal combustion engine is known (Japanese Unexamined Patent Publication No. 42806/1983).

In this case, there are two ways to open and close both ports with two intake valves, and one where both ports are double cylindrical and open and close at the same time with a single intake valve.
Independent intake passages are connected to the primary side and the secondary side of the double-barrel carburetor so that air-fuel mixture is separately supplied to both ports.

As a result, it cannot be applied to systems other than double-barrel carburetors, such as SU carburetors, which have a single air supply system, and it is necessary to separate the intake manifold into primary and secondary passages at the collecting part. The structure becomes more complex and the weight increases, and furthermore, the suction resistance on the secondary side increases and the full-open output decreases, and when the secondary throttle valve is fully open during low-speed operation, the negative pressure generated on the secondary side increases. The mixture or combustion gas on the primary side flows around into the secondary intake passage, causing problems such as a decrease in the primary flow velocity when the intake valve is opened, weakening the swirl, and reducing the combustion improvement effect.

The present invention was proposed to solve this problem.The branch part of the intake passage and the intake port are separated into two passages, and a secondary throttle valve is provided on the secondary side of the passage, while a secondary throttle valve is provided upstream of this throttle valve. The purpose of the present invention is to provide a dual intake internal combustion engine in which the primary and secondary passages are merged so as to share them.

Examples will be described below with reference to the drawings.

In FIGS. 1 and 2, 1 is a cylinder head, 2 is a cylinder block, 3 is a piston, and 4 is a combustion chamber.

Furthermore, 5 is an intake valve, 6 is an exhaust valve, 7 is an intake port 8
indicates an exhaust port.

The intake port 7 is separated into a primary side swirl port}7a and a secondary side output port}7b via a partition 9.
7a is a so-called low port where the inflow angle of the air-fuel mixture is close to horizontal, and the penetration of the swirl (in-cylinder gas flow) caused by the intake valve 5 being unevenly distributed from the center of the combustion chamber (center of the cylinder bore) when viewed in plan. While increasing the force (increasing the number of turns in the cylinder until the air mixture collides with the top surface of the piston when the piston 3 descends), the bow}7
b brings the inflow angle of the air-fuel mixture close to the cylinder bore axis direction to reduce suction resistance, and mainly prevents deterioration of suction efficiency in the high-speed range.

A primary passage 11 is connected to the branch portion 10 a of the intake manifold 10 by connecting to both ports } 7 a and 7 b.
a and a secondary passageway 11b are formed through the partition wall 12,
A secondary throttle valve 13 opens and closes this secondary passage 11b.

The starting point A of this partition wall 12 is located at the swirl port 7.
A position that causes a swirl in the intake air from a, ie, an upstream position near the junction of the intake pipe and the head, is sufficient.

The throttle valves 13 of each secondary passage 11b are fixed to a common valve shaft 14 and set to have the same opening degree;
The main throttle valve 15 provided in the merging intake passage 11 upstream of the branch portion 9 interlocks with the main throttle valve 15 via, for example, a link 16 and levers 17a, 17b, and a lever 17b is inserted into the elongated hole 18 of the link 16.
The rotating tip of the main throttle valve 15 is loosely fitted so that the secondary throttle valve 13 starts to open after the main throttle valve 15 opens a certain amount or more.

By changing the lever ratio of the levers 17a and 17b, the secondary throttle valve 13 can be fully opened in synchronization with the fully opening of the main throttle valve 15.

Upstream of the main throttle valve 15, a so-called SU carburetor main body 19 is provided.
is provided with a piston 20 that responds to negative pressure proportional to the intake air flow rate, and a fuel nozzle 22 that moves back and forth through a fuel nozzle 21 attached to the piston 20, so that the piston 20 expands and contracts according to the intake air amount. It operates to maintain a constant flow rate through the nozzle portion (therefore, the negative fuel suction pressure) and to supply fuel in proportion to the nozzle opening area determined based on the position of the twenty-one dollar 21.

In the structure described above, in the engine low-medium speed range, the secondary throttle valve 13 is closed, so that all of the intake air-fuel mixture is Flows into the primary passage 11 a side and further swirl po}
The air is drawn into the combustion chamber 4 from 7a in synchronization with the opening of the intake valve 5 while creating a swirling flow.

Therefore, stable combustion can be obtained by this swirl, and it is possible to achieve leaner mixture or higher rate EGR without impairing drivability.

On the other hand, since the secondary throttle valve 13 is closed, the secondary passage 11b and output port 7b of each air passage do not communicate with each other, and therefore the primary air-fuel mixture flows into the secondary passage of the other air passage. It is possible to reliably prevent the gas from going around, prevent a decrease in the flow velocity of the swirl port 7a, and strengthen the swirling flow, thereby making it possible to effectively promote combustion based on the gas flow.

In the high speed range of the engine, when the opening degree of the main throttle valve 15 exceeds a predetermined value, the lever 17b of the throttle valve 13 engages with the end of the long hole 18 of the link 16, and the secondary throttle valve 13 opens. start.

Therefore, the air-fuel mixture flows into both the primary and secondary passages 11a and 11b, and at this time, the secondary output port {7b} has low suction resistance, so compared to when the mixture was supplied only from the swirl port {7a}. As a result, the overall suction efficiency is significantly improved, and therefore, a predetermined operating output performance can be ensured without reducing the engine's full-throttle output.

Next, in the embodiment shown in FIG. 3, the present invention is applied when a double-barrel carburetor 25 is provided. The intake passages 11 are made to merge in the same way as in the internal combustion engine.

However, the downstream side of the branch portion 10a is separated into a primary passage 11a and a secondary passage 11b, as in the embodiment described above.

FIG. 4 shows a case in which the present invention is applied to an engine that is equipped with a fuel injection valve (not shown) in the intake port 7 and injects fuel according to the amount of intake air. Primary and secondary passages 1 in the branch 31
There is basically no difference in the fact that the partition wall 33 is provided to partition the sections 1a and 11b, and the throttle valve 13 is provided in the secondary passage 11b.

Furthermore, Fig. 5 shows the swirl port 7a and the output port 7b.
In this example, the ports 7a and 7b are opened and closed by the intake valves 5a and 5b, but the present invention can of course be applied to this system as well.

As described above, according to the present invention, it is possible to apply the
A double intake system can be applied, and the structure of the intake manifold is simplified and intake resistance is reduced, and the full-open output is particularly improved. Even if the latter parts are not completely independent, the swirl can be strengthened by preventing the air-fuel mixture from going around to the secondary passage in the low-to-medium speed range, and improvement in combustion characteristics can be expected.

In the above embodiment, the secondary throttle valve was mechanically linked to the main throttle valve, but the negative pressure proportional to the amount of intake air is taken out and the secondary throttle valve is opened via the diaphragm device. It is also possible to do so.

Furthermore, the opening and closing may be performed mechanically or electrically by detecting engine suction negative pressure or rotational speed.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of the first embodiment of the present invention, Fig. 2 is a transverse sectional view of the same, Fig. 3 is a longitudinal sectional view of another embodiment, and Fig. 4 A shows the opening of the other embodiment. A cross-sectional view of the intake manifold, FIG. 5 is a cross-sectional view showing an embodiment of the multiple intake valve system. 1...Cylinder head, 2...Cylinder block, 3...Piston, 4...
Combustion chamber, 5...Intake valve, 7a...Primary swirl port, 7b...Secondary output port, 9
......Bulkhead, 11 a...List intake passage, 1l b...Secondary intake passage, 11...
・Intake passage, 12... Bulkhead, 13...
Secondary throttle valve, 15... Main throttle valve, 16...
Link, 17 a, 17 b... Throttle valve lever, 19... SU carburetor body, 25...
Double-barrel carburetor, 30...Intake manifold, 3
1... Branch, 33... Bulkhead.

Claims (2)

[Scope of utility model registration request] 1. In the low and medium speed range of the engine, the mixture is supplied through the primary side swale port to create a rotational motion in the mixture flow flowing into the combustion chamber, and in the high speed range, the mixture is also supplied through the secondary side output port with low suction resistance. In a multi-cylinder internal combustion engine, primary and secondary intake passages are formed in each branch part of the intake manifold through a partition wall to communicate with the two ports, respectively. A double-intake internal combustion engine in which a secondary throttle valve provided in a secondary intake passage for each cylinder is linked directly or indirectly with a main throttle valve in a collective intake passage upstream of a branch section. 2. The dual-intake internal combustion engine according to claim 1, wherein the secondary throttle valve is fully closed in the engine low-medium speed range and opens in accordance with the amount of intake air in the high-speed range.