JPH07127539A - Muffling device - Google Patents

Abstract

PURPOSE:To provide a muffling device not only capable of acquiring a plurality of sound eliminating frequency ranges and sufficient reduction effect thereof even if the range of noise frequency is extensive but also successful in making it compact in, reducing manufacturing manhours and number of parts, and in manufacturing it inexpensively. CONSTITUTION:A muffling device 1 is provided with an air cleaner hose 2 having No.1 through tube 5 and No.2 through tube 6 protruded beyond its pipe wall. No.1 plastic body 3, which is blow-formed on the outer circumferece of the hose 2 with the hose 2 as its inserted component, is equipped with No.1 resonance muffling cell 7 enveloping the No.1 through tube 5 therein as its communication tube to the hose 2 and a muffling part 9 for muffling No.2 through tube 2 in a closely adhered condition. No.2 plastic body 4, which is injection-mold separately from the No.1 plastic body 3 but connected to the No.1 plastic body 3, is equipped with No.2 resonance muffling cell 13 for muffling the No.2 through tube 6 and the muffling part 9, which has a hole drilled on its end surface, as its communication tube to the hose 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler for eliminating noise generated or propagating in a flow tube.

[0002]

2. Description of the Related Art A muffler 51 provided in an intake pipe of a conventional automobile internal combustion engine.
As shown in FIG. 5, a resonance silencing chamber 53 (resonator) is provided outside the intake pipe 52 so that the intake pipe 52 and the resonance silencing chamber 53 communicate with each other by a communication pipe 54, or the intake pipe 5
It was constituted by projecting a side branch 55 on the outside of 2.

However, in the above-described muffler 51, the resonance muffler chamber 53 and the side branch 55 are separated from or protrude from the intake pipe 52 and are bulky, so that a space for disposing the muffler 51 in the engine room is secured. There was a problem that it was difficult to do. In addition, since each part was molded separately, and then assembled by the tightening ring 56 and the like, the number of steps and the number of parts were large, and the cost was high.

Therefore, as shown in FIG. 6, an intake pipe 62 having one through hole 63 in the pipe wall, and the intake pipe 62.
Has been developed as an insert part, and a silencer 61 having a blow molded body 64 having a resonance silencing chamber 65 communicating with the intake pipe 62 with the through hole 63 as a communicating hole has been developed. (Japanese Patent Laid-Open No. 1-255355
9). Since the intake pipe 62 and the blow molded body 64 are adjacent to each other, the silencer 61 can be formed compactly. Further, since the blow molded body 64 is joined to the intake pipe 62 at the same time as the blow molding, the number of steps and the number of parts are small, and the cost can be reduced.

However, the silencing frequency band due to the resonance action of the silencing device 61 is determined by the volume of the resonance silencing chamber 65 and the through hole 6.
Since only one (excluding overtones) is determined by the area and the length of 3, the sufficient reduction effect may not be obtained when the noise frequency range is wide.

The object of the present invention is to solve the above-mentioned problems, to obtain a plurality of silencing frequency bands, to obtain a sufficient reduction effect even when the noise frequency range is wide, and to make it compact. An object of the present invention is to provide a novel silencer that has a small number of steps and a small number of parts and can be manufactured at low cost.

[0007]

In order to achieve the above-mentioned object, a muffler of the present invention is provided with a flow tube having a plurality of first penetrating cylinders and second penetrating cylinders projecting from a tube wall, and the flow tube. A first resonance silencing chamber that is blow-molded on the outer periphery of the air flow tube as an insert part and surrounds the first through tube as a communication tube to the air flow tube, and the second through tube in a tightly sealed state. The first molded body having the encapsulation part to be molded, and the first molded body are molded separately, and are joined to the first molded body, and the second through cylinder and the end surface are perforated. A second molded body having a second resonance silencing chamber that surrounds the encapsulation portion as a communication tube to the air flow tube is provided.

Here, the "flow pipe" is not limited to a specific one as long as it is a pipe through which gas flows, and examples thereof include an intake pipe and an exhaust pipe of an internal combustion engine. The length, the cross-sectional shape, the disposition position, etc. of the "first penetrating cylinder and the second penetrating cylinder" can be appropriately determined. In particular, for the "first penetrating cylinder" that connects the first resonance silencing chamber to the air duct, It also includes a simple through hole formed in the wall of the trachea. Further, the first through cylinder and the second through cylinder are not limited to one each, but a plurality of each may be provided.

The "first resonance silencing chamber" and the "second resonance silencing chamber" are not limited to a particular shape or size as long as they have a volume necessary to resonate at a desired silencing frequency. A plurality of chambers may be provided for each of the first through cylinder and the second through cylinder. Further, as the "second molded body", one molded by a known molding method such as injection molding can be adopted, and as means for joining the second molded body to the first molded body, hot plate welding, vibration welding, Adhesion and the like can be exemplified.

[0010]

In the muffler of the present invention, the first resonance muffling chamber of the first molded body and the second resonance muffling chamber of the second molded body, each of which communicates with the air flow tube, perform a resonance muffling action. Therefore, a plurality of silencing frequency bands can be obtained, and a sufficient reduction effect can be obtained even when the noise frequency range is wide. Further, both the first resonance muffling chamber and the second resonance muffling chamber are provided so as to surround the communication pipes (the first penetrating cylinder, the second penetrating cylinder and the encapsulation portion), and the first molded body and the second molded body are the air ducts. This silencer can be made compact because it is adjacent to the flow tube without being separated from it. Further, since the first molded body is joined to the flow tube at the same time as the blow molding, the number of steps and the number of parts are small, and the cost can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is embodied in a muffler installed in an intake pipe of an internal combustion engine for automobiles will be described below with reference to FIG.
2 and FIG. 2. Muffler 1 of this embodiment
Comprises an air cleaner hose 2, one first molded body 3 and one second molded body 4, and each member is configured as follows.

An air cleaner hose 2 as an intake pipe connecting an air cleaner of an internal combustion engine and a fuel injection device (both not shown) is blow-molded into a cylindrical shape using a synthetic resin such as polypropylene, polyamide or polyethylene. It is made by injection molding. A first penetrating cylinder 5 and a second penetrating cylinder 6 are provided at an axially intermediate portion of the tube wall of the air cleaner hose 2 at positions separated by about 180 degrees. Each of the penetrating cylinders 5 and 6 is formed by the blow molding, which is formed as a cylinder whose outer end face is closed and then cut off the end face.

The first molded body 3 is formed by blow molding using the air cleaner hose 2 as an insert part and using the synthetic resin as described above on the outer periphery thereof. In the lower half, the first molded body 3 bulges away from the air cleaner hose 2 and constitutes a first resonance silencing chamber 7 that surrounds the first through cylinder 5 as a communication pipe to the air cleaner hose 2. In FIG. 1, a pedestal 8 for joining the second molded body 4 is formed by the blow molding on the peripheral edge of the upper surface of the first molded body 3 located on both shoulders of the first resonance silencing chamber 7. The upper half of the first molded body 3 is in close contact with the air cleaner hose 2, and in particular, is provided with the encapsulation portion 9 that encloses the second through cylinder 6 in a close contact state. Both end portions of the first molded body 3 extend to both end portions of the air cleaner hose 2, respectively, and are extended portions 10 that are in close contact with the outer peripheral surfaces of the both end portions. An annular projection 11 is provided on the outer periphery of each extended portion 10 to improve the sealing performance when a hose (not shown) is externally fitted.

The second molded body 4 is injection-molded in the shape of a hat separately from the first molded body 3 using the above-mentioned synthetic resin. A contact portion 12 that is abutted against the pedestal 8 is formed on the peripheral edge of the lower end of the second molded body 4 by the injection molding, and the contact portion 12 is joined to the pedestal 8 by hot plate welding. The second molded body 4 includes the second through-cylinder 6 and an encapsulation portion 9 having an end surface (indicating an end surface encapsulating the outer opening of the second through-cylinder 6) perforated.
It is provided with a second resonance silencing chamber 13 which surrounds it as a communication pipe to. The end surface of the enveloped portion 9 is perforated by the processing after the blow molding of the first molded body 3.

The silencer 1 of this embodiment is manufactured by the following procedure. The air cleaner hose 2 is molded by blow molding or injection molding, and the second molded body 4 is molded by injection molding. As disclosed in Japanese Patent Application Laid-Open No. 1-253559, the air cleaner hose 2 is set in a blow molding die (not shown), a parison is supplied around the air cleaner hose 2 to tighten the die, and the parison is closed. Air is blown into the inside to blow mold the first molded body 3. The end surface of the enveloped portion 9 of the first molded body 3 is perforated by drilling, cutting off, or the like. The contact portion 12 of the second molded body 4 is aligned with the pedestal 8 of the first molded body 3 and hot plate welding is performed.

In the muffler 1 of the present embodiment constructed as described above, the first resonance muffling chamber 7 and the second resonance muffling chamber 1
The resonance frequency of 3, that is, the silencing frequency band f0 is expressed by the following mathematical formula.

[0017]

## EQU1 ## f0 = (C / 2.pi.). Multidot. (S / (V.Lp)) where C = 331.5 + 0.61t: sound velocity (m /
Sec) S = πD ^2/4: cross-sectional area of the communicating pipe (inner size) D: inside diameter of the communicating pipe V: resonance silencer chamber volume Lp = L1 + 0.8D L1: length of the communicating pipe t: Temperature (℃)

In this embodiment, since the first resonance muffling chamber 7 and the second resonance muffling chamber 13 each have a resonance muffling action, by adjusting each parameter of the above equation,
Two silencing frequency bands can be obtained, and a sufficient reduction effect can be obtained even when the noise frequency range is wide. Further, both the first resonance silencing chamber 7 and the second resonance silencing chamber 13 are provided so as to surround the communication pipe (the first penetrating cylinder 5, the second penetrating cylinder 6 and the encapsulating portion 9), and the first molded body 3 and the Since the two molded bodies 4 are adjacent to the air cleaner hose 2, the muffler 1 can be made compact. Further, since the first molded body 3 is joined to the air cleaner hose 2 at the same time as the blow molding, the number of steps and the number of parts are small, and the cost can be reduced.

Next, the silencer 2 of the second embodiment shown in FIG.
1, a first through cylinder 5 and two second through cylinders 6a and 6b project from the pipe wall of the air cleaner hose 2, and the first resonance muffling chamber 7 of the first molded body 3 includes the first cleaner 3 of the air cleaner hose 2. This is different from the first embodiment in that the second moldings 4a and 4b are swelled over the entire circumference and two second moldings 4a and 4b are welded to the upper and lower portions of the first molding 3 by hot plate welding. The first resonance silencing chamber 7 surrounds the first penetrating cylinder 5 as a communication pipe to the air cleaner hose 2, and the second resonance silencing chamber 13a of the second molded body 4a is bored at the end face with the second penetrating cylinder 6a. The second resonance silencing chamber 13b of the second molded body 4b surrounds the second encapsulation section 6b and the encapsulation section 9 whose end face is perforated as a communication tube. Surrounding. It should be noted that members and the like common to the first embodiment are denoted by common reference numerals in FIG. 3 and description thereof is omitted.

According to the present embodiment, since the first resonance silencing chamber 7 and the two second resonance silencing chambers 13a and 13b each have a resonance silencing effect, the three parameters can be adjusted by adjusting each parameter of the above formula. Two silencing frequency bands are obtained.

Next, the silencer 3 of the third embodiment shown in FIG.
1 includes two second molded bodies 4a, 4 on top of the first molded body 3.
This is different from the second embodiment in that b are welded side by side on the hot plate. The same members as those in the first embodiment are designated by the same reference numerals in FIG. 4 and their description is omitted. According to this embodiment, in addition to the same effect as the second embodiment, the bulkiness in the radial direction can be suppressed as compared with the second embodiment.

The present invention is not limited to the configuration of the above-described embodiment, and is embodied in, for example, a silencer for an intake system or an exhaust system in various fluid utilizing equipment other than an internal combustion engine for automobiles.
The present invention can be embodied with any changes without departing from the spirit of the invention.

[0023]

Since the muffling device of the present invention is constructed as described above, it is possible to obtain a plurality of muffling frequency bands and not only obtain a sufficient reduction effect even when the frequency range of noise is wide. It has an excellent effect that it can be formed compactly, the number of steps and the number of parts are small, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a silencer of a first embodiment.

FIG. 2 is a partially cutaway front view of the sound deadening device.

FIG. 3 is a sectional view of a silencer according to a second embodiment.

FIG. 4 is a cross-sectional view of a silencer of a third embodiment.

FIG. 5 is a front view of a conventional silencer.

FIG. 6 is a cross-sectional view of another conventional example.

[Explanation of symbols]

 1 muffler 2 air cleaner hose as air pipe 3 first molded body 4, 4a, 4b second molded body 5 first penetrating cylinder 6, 6a, 6b second penetrating cylinder 7 first resonance silencing chamber 9 encapsulation 13, 13a, 13b 2nd resonance silencing chamber 21 Silencer 31 Silencer

Claims (1)

[Claims] 1. A flow tube having a first penetrating cylinder and a second penetrating tube projecting from a tube wall, and the first penetrating tube formed by blow molding on the outer periphery of the flow tube using the flow tube as an insert part. A first resonance silencing chamber that surrounds the first air passage as a communication tube to the air flow tube, and a first molded body that includes an encapsulating portion that encloses the second through tube in a close contact state, and the first molded body is different from the first molded body. A second resonance silencing chamber formed into a body and joined to the first formed body, and surrounding the second penetrating cylinder and the encapsulation portion having an end face perforated as a communication tube to the air flow tube. And a second molded body.