JPS5834277Y2 - Intake system for multi-cylinder engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an intake system for a multi-cylinder engine having a pair of cylinders each having a throttle valve and having an independent primary intake passage and a secondary intake passage.

Conventionally, the intake system of a multi-cylinder engine has been provided with a communication passage that communicates the intake passages of each cylinder with each other downstream of the throttle valve, and a communication passage that connects the intake passages of some cylinders with each other downstream of the communication passage for deceleration or idling. A shutter valve that is fully closed during operation with high intake negative pressure and low charging efficiency is provided to cut off the supply of air-fuel mixture to the cylinder downstream of the shutter valve that is pressed during the above operation, and to close the air-fuel mixture to the cylinder downstream of the shutter valve that is pressed during the above operation. There is a known method that increases the charging efficiency of the cylinder, improves combustion, and reduces the emission of unburned components by concentrating on the
2-18342).

The present invention addresses various problems when applying such a shutter valve system to an intake system of a multi-cylinder engine having a pair of cylinders each having a throttle valve and having an independent primary intake passage and a secondary intake passage. This is to solve the problem.

In conventional shutter valves of this type, the shutter valve was installed so that the rotation axis of the shutter valve was parallel to the rotation axis of the throttle valve, which not only made it difficult to install the shutter valve, but also caused problems in the communication passage. There was a problem that processing or setting was difficult.

That is, in order to ensure good transient response immediately after the shutter valve is fully closed, the length of the communication path must be as short as possible, and while the shutter valve is fully closed, It is necessary to provide the shutter valve in a position where fuel flowing along the wall of the intake passage does not accumulate on the shutter valve.

In addition, since the rotational axis of the throttle valve needs to be the same axis for both primary intake passages, it must be in a straight line direction connecting the cross-sectional centers of the respective primary intake passages by the shortest distance.

Therefore, when the rotation axis of the shutter valve is set parallel to the rotation axis of the throttle valve as described above, and the communication passage is set to the shortest distance, the rotation axis of the throttle valve, the rotation axis of the shutter valve, and the axis of the communication passage The direction is
When the axes are parallel to each other, it becomes ＼.

By the way, in the above structure, since the inclination direction of the shutter valve and the direction of the communication passage when fully closed are inevitably perpendicular to each other, it is difficult to guide the fuel dammed by the shutter valve from the communication passage to the other primary intake passage. There is a problem in that when the shutter valve is opened, the accumulated fuel flows into the previously closed cylinder, causing car knock.

Additionally, to avoid this problem, the opening of the communication passage can be set to match the inclination direction of the shutter valve, but in this case, the communication passage must be bent within the intake manifold. First, since the length of the passage becomes long, as mentioned above, there arises a problem that the transient response that occurs immediately after the shutter valve is fully closed is significantly deteriorated.

This invention was made in order to solve the problems of the conventional shutter-pulf system as described above. By providing only the primary intake passage and providing a communication passage that communicates each secondary intake passage in the axial direction of the throttle valve, the communication passage can be set at the shortest distance without the problem of fuel accumulation.
Therefore, it is an object of the present invention to provide an intake system for a multi-cylinder engine that can facilitate the mounting structure of the shutter valve and the fabrication of the communication passage.

This invention will be described in more detail below with reference to the illustrated embodiments.

In Fig. 1, 1 is basically a 4-barrel carburetor consisting of two mutually independent carburetors arranged side by side, 2P and 3P are the primary intake passages of each cylinder, and 28 and 3S are the primary intake passages of each cylinder. A secondary intake passage, 5 is a P-p communication passage that connects the mutually independent primary intake passages 2P and 3P with each other, and 6 and 7 are used to connect the primary intake passages 2P and 3P of each cylinder to the secondary intake passages 2S and 3S. These are P-8 communication paths that communicate with each other.

Further, 8 is a relatively flat mixing chamber with a circular horizontal cross section that communicates with both primary intake passages 2P and 3P via small-diameter distribution passages 9 and 10, and 11 communicates with the outer periphery of the mixing chamber 8 from the vertical direction. An air bypass passage with an idle port 12 opened slightly above the communication portion changes the direction of the air flowing down the air bypass passage 11 approximately at right angles and guides it into the mixing chamber B. The air flow promotes vaporization and atomization of the fuel led out from the idle port 12, and the resulting mixture is evenly distributed to each secondary intake passage 2P, 3P via the distribution passage 9-10. do.

In this case, in order to improve the □ kissing effect in the □Kishifugu chamber 8, for example, blow-by gas is opened at a position opposite to the communication portion 11a of the bypass air passage 11 in the diametrical direction of the □Kishifugu chamber 8. A recirculation passage 14 is provided, and when the ventilation valve 15 provided in the middle of the passage 14 is opened, the bypass air passage 11 is opened.
It is preferable to cause the air flow from the mixing chamber 8 to collide with the blowby gas flow from the blowby gas return passage 14 to generate turbulent flow within the mixing chamber 8.

Note that instead of the blow-by gas, vaporized fuel may be introduced, or both may be introduced together.

As shown in FIG. 2, the first and second cylinders E 1 yE
The P-P communication passage 5 that communicates the primary intake passages 2P and 3P that communicate with each other is connected to the first communication passage 16 provided in the upper and lower two stages.
, the second communication path 11.

The first communication passage 16 utilizes a carburetor insulator 20 interposed between the throttle chamber 18 and the intake manifold 19, and a communication groove 2 provided in the insulator 20.
0a and the upper surface of the partition wall 19a of the intake manifold 19, a communication passage with a relatively large passage cross-sectional area is formed at a position close to each throttle valve 2T, 3T.

Further, the second communication passage 1T is provided downstream of the first communication passage 16 as a communication passage having a relatively small passage area and is bored in the partition wall portion 19a of the intake manifold 19.

21 is one primary intake passage 2 immediately downstream of the second communication passage 17;
This is a shutter valve installed at P.

The shutter valve 21 completely closes one of the primary intake passages 2P during idling operation or deceleration operation of the engine, thereby blocking the air-fuel mixture to the cylinder E1 downstream thereof, and mainly through the first communication passage 16. The mixture supplied to one primary intake passage 2P is transferred to the other primary intake passage 3P.
A butterfly valve for bypassing the valve 21
As shown in FIG. 1, the axial direction 13 of the 0 rotation axis (third rotation axis) 21a is a common rotation axis (first rotation axis) 22 of the throttle valves 2T and 3T of each secondary intake passage 2P and 3P.
axial direction 11 and each secondary intake passage 2S.

3S throttle valve (not shown) common rotation axis (
The rotation axis is set in a direction perpendicular to the axial direction 12 of the second rotation axis.

In this case, as shown in FIG.
Therefore, when the shutter valve 21 is fully closed, the lower edge 21b of the shutter valve 21 in the inclined direction is aligned with the bottom surface 17a of the second communication path 17.
The upper surface of the shutter valve 21 can guide the liquid fuel to the second communicating path 17.

On the other hand, P which communicates the primary intake passage 2P on the side where the shutter valve 21 is provided and the secondary intake passage 2S forming a pair therewith
The -8 communication passage 6 is communicated with the primary intake passage 2P downstream of the shutter valve 21, and when the shutter valve 21 is fully closed, communication with the other P-8 communication passage 1 is cut off by the shutter valve 21.

This is to prevent the air-fuel mixture from flowing into the secondary intake passage 2S via the p-8 communication passage 6 when the shutter valve 21 is fully closed.

Note that the other P-8 communication passage 7 does not have the above-mentioned problem and can be provided at the easiest position, for example, on the upper wall surface of the intake manifold 19.

1. For example, during operation with large intake negative pressure, such as during idle link or deceleration, the shutter valve 21 is fully closed, and the air is supplied from the main nozzle or mixing chamber 8 to one primary intake passage 2P via the distribution passage 9. The air-fuel mixture is mainly supplied to the first and second primary intake passages 3P.
It is bypassed via communication passages 16 and 17.

As a result, while the supply of all air-fuel mixture to the first cylinder E1 is cut off, the filling efficiency of the second cylinder E2 is improved by the air-fuel mixture for two cylinders supplied from the other primary intake passage 3P, and the filling efficiency is improved. It exhibits good flammability and completely ignites.

In this case, the air-fuel mixture in the secondary intake passage 2P is mainly introduced from the first communication passage 16 to the other primary intake passage 3P, and the liquid fuel flowing down along the wall of the secondary intake passage 2P is completely closed. The flow is blocked by the shutter valve 21, collected in the second communication passage 17 along the slope of the shutter valve 21, flows into the other intake passage 3P through the second communication passage 17, and is required for the second cylinder E2. Supplied as fuel.

Also, during operation with low intake negative pressure and good combustion, the shutter valve 21 is fully opened and the throttle valve 2T
, main nozzle system, slow port (
(not shown) and the mixing chamber 8 are supplied to each cylinder E through the respective primary intake passages 2P and 3P.
1t E2 is supplied and burns well.

In this case, the P-P communication passage 5, particularly the first communication passage 16, alleviates intake pulsation and eliminates unbalance of intake negative pressure caused by uneven carburetor settings, guarantees equal distribution of fuel, and In addition, an imbalance in the intake negative pressure that may occur due to poor sealing of the secondary throttle valve (not shown) can be avoided by connecting the secondary intake passages 2S and 38 to the P-8 communication passage 6, the first communication passage 16, and the P-8 communication passage 6, the first communication passage 16, and -8 This problem can be solved by communicating with each other through the communication path 7.

In addition, in the above embodiment, the P-P communication path 5 is connected to the first communication path 1.
6 and the second communication path 17, it is not necessarily limited to this, and it is also possible to use two communication paths.

However, if the P-p communication passage 5 is provided downstream of the intake passage, interference between intake and exhaust will increase, causing problems such as output loss, and the independent intake passage becomes meaningless.

It is preferable to provide it near the downstream of 3T.

Therefore, the shutter valve 21 also needs to be provided upstream of the intake passage in order to prevent the formation of a pool of liquid fuel.

Therefore, in the embodiment, the shutter valve 2 is located near the joint surface of the intake manifold 19 with the carburetor insulator 20.
0 is set.

In some cases, the cab insulator 20 may be made thicker and the shutter valve 21 may be incorporated therein.

As described above, this invention has the advantage that the first rotation axis of the primary throttle valve and the second rotation axis of the secondary throttle valve are parallel to each other in the axial direction of the first and second rotation axes. A shutter valve is attached to the third rotating shaft having perpendicular axial directions, and a communication passage connecting each secondary intake passage is provided parallel to the first rotating shaft. The present invention provides an intake system for a multi-cylinder engine, characterized in that an intake passage is completely closed downstream of a throttle valve.

According to this invention, the shutter valve opening/closing mechanism can be incorporated without interfering with the throttle valve opening/closing mechanism, making it possible to simplify the shutter valve device. Utilizing the inclination of the valve, fuel can be collected in the communication passage of both primary intake passages, reliably preventing accumulation of fuel, and the communication passage can be set at the shortest distance. Processing can be facilitated.

[Brief explanation of the drawing]

FIG. 1 is an explanatory horizontal cross-sectional view showing the bottom of the carburetor of the intake system of a multi-cylinder engine according to an embodiment of this invention, and FIG.
FIG. 2 is an explanatory diagram of a vertical cross section along the line I-I in the figure. 2P, 3P...-Next intake passage, 2T, 3T...-Next throttle valve, 5...P-P connection A path, 21...
Shutter valve, 11... - Direction of the rotation axis of the downstream throttle valve, 12... Direction of the rotation axis of the secondary throttle valve, 13... Direction of the rotation axis of the shutter valve.

Claims (1)

[Claims for Utility Model Registration] A pair of cylinders each having a throttle valve and an independent primary intake passage and a secondary intake passage, the throttle valves of each secondary intake passage being fixed to the same first rotating shaft. In addition, in an intake system of a multi-cylinder engine in which the throttle valve of each secondary intake passage is fixed to a second rotating shaft supported in parallel with the first rotating shaft, the throttle valve downstream of each of the secondary intake passages is A shutter valve fixed to a third rotating shaft supported in a direction orthogonal to the first and second rotating shafts is provided in a communicating passage communicating in the direction of the first rotating shaft, and in one of the primary intake passages downstream near the communicating passage. An intake device for a multi-cylinder engine, characterized in that the third rotating shaft is rotated during deceleration or idling, and the shutter valve is closed, thereby blocking the air-fuel mixture to the downstream cylinder. .