JPH0842416A - Dual duct with silencer - Google Patents

Abstract

PURPOSE:To make up such a resonator as being high in silencing effect so compact in size by forming two cavity chambers in an interspace between two branch ducts, and interconnecting them to these branch ducts, in this dual duct which bifurcates an air intake duct of an internal combustion engine, forming these double branch ducts, and supplies intake air to a cylinder group divided into two sections. CONSTITUTION:An air intake duct 2 is bifurcated into two branch ducts 3 and 4, and two cavity chambers 5 and 6 are formed in an interspace between both of them, then they are interconnected to the branch ducts 3 and 4 through two interconnecting holes 7 and 8, forming it into a resonator. These branch ducts 3 and 4 are not further branched in the downstream, whereby a silencing action by means of resonance is large enough. In addition, since there is no part overhanging to the outside from the branch ducts 3 and 4, it is compact in size and suitable for use in an automobile or the like. In addition, this dual duct is formable simultaneously and integrally by means of blow molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual duct in which an intake duct of an internal combustion engine is branched into two, which are bifurcated and each of which has a resonance silencer.

[0002]

2. Description of the Related Art In order to equalize the amount of intake air into each cylinder of a conventional multi-cylinder internal combustion engine, for example, a 6-cylinder engine is divided into two groups of three cylinders each, while two ducts for intake air are branched. There is a system in which a duct is branched and a branch duct is connected to the collector of each cylinder group so as to communicate with each other. In order to provide a resonance type silencer in this intake system, usually one resonator is attached to the upstream portion before branching, but it is known that this does not provide a sufficient silencing effect.
In addition, a secondary effect required for the resonator, that is, a torque-up effect for reducing a decrease in torque generated in a specific rotation speed range cannot be sufficiently obtained.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to obtain a sufficient noise reduction effect for an intake system having a dual duct in which an intake duct is branched and to alleviate the above torque decrease. Are assembled in a compact form for easy mounting.

[0004]

Means for Solving the Problems A branch duct is formed by bifurcating an intake duct, two cavity chambers are formed in a space between the branch ducts, and the cavity chambers communicate with one branch duct at a time. A communication hole is provided to allow the communication.

[0005]

The hollow chamber of the present invention acts as a resonator for each branch duct, and there is no branch of the duct on the downstream side near these noise sources, so a sufficient silencing effect can be obtained. Moreover, since the hollow chamber is housed inside the bifurcated branch duct, it is compactly assembled and does not require a large installation space.

[0006]

1 and 2 show an embodiment. The dual duct 1 is provided on the downstream side of the intake duct 2 of the 6-cylinder internal combustion engine.
It is composed of branch ducts 3 and 4 formed by bifurcating.
The downstream side of the branch ducts 3 and 4 is connected to a collector (not shown) divided into three cylinders. The branch ducts 3 and 4 are formed by branching the intake duct 2 into an acute-angled bifurcated shape,
Cavity chambers 5 and 6 are provided in the space between the two, and the cavity chamber 5 and the branch duct 3 are communicated with each other through a short-tube communication hole 7, and the cavity chamber 6 and the branch duct 4 are communicated with each other through a communication hole 8. Each becomes a Helmholtz type resonator.

The dual duct 1 is made of synthetic resin,
The hollow chambers 5 and 6 are also integrally formed by blow molding. That is, the parison hanging from the blow molding machine has a shape in which the lower part is enlarged, and the partition walls a, b, c,
d is pressed and deformed from both sides by rib-shaped projections provided in the mold of the matching mold, and the opposing portions are brought into close contact with each other to define the branch ducts 4 and 5 and the cavity chambers 6 and 7, and further the communication holes 7 and 8 To open.

As another embodiment, a dual duct 11 shown in FIGS. 3 and 4 has a hollow chamber 1 between branch ducts 13 and 14.
5 and 16 are formed in a tube shape, and communication holes 17 and 18 are provided at one end of the hollow chambers 15 and 16 to communicate with the branch ducts 13 and 14 to form a side branch type resonator. The ones shown in FIGS. 3 and 4 can also be integrally formed by the blow molding method as in the examples shown in FIGS.

In addition to the above, these branch ducts may be formed by molding the divided members by injection molding and welding them. The material used is not limited to synthetic resin, and the manufacturing method is arbitrary. These hollow chambers 5, 6, 15, and 16 serve as resonance chambers for the branch ducts 3, 4, 13, and 14, respectively, and have a sound deadening effect. Further, as shown in FIG. 5, when there is no resonance chamber, the torque decrease due to the interference of the air pulsating flow occurs as shown by the curve C in the specific rotation speed range, whereas the presence of the resonance chamber causes the curve D to decrease. As described above, there is a torque-up action that reduces the torque decrease.

[0010]

Since the present invention has the above-mentioned structure, it has a compact structure in which the sound deadening effect due to resonance and the torque reduction reducing effect are remarkable, and there is no portion protruding to the outside of the branch duct. Therefore, it can be arranged in a narrow space such as for an automobile engine, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment.

2 is a sectional view taken along line AA of the embodiment of FIG.

FIG. 3 is a side view of another embodiment.

FIG. 4 is a sectional view taken along line BB of the embodiment shown in FIG.

FIG. 5 is a rotational speed-torque diagram of an internal combustion engine

[Explanation of symbols]

 3, 4, 13, 14 Branch duct 5, 6, 15, 16 Cavity chamber 7, 8, 17, 18 Communication hole

Claims (1)

[Claims] 1. A dual duct in which a plurality of cylinders of an internal combustion engine are divided into two groups, an intake duct is branched into two branch ducts, and intake air is supplied from each branch duct to each cylinder group. A dual duct with a muffler in which two hollow chambers are formed in the space sandwiched by the branch ducts, and the hollow chambers are communicated with each one of the branch ducts.