JP5124115B2 - Resonator - Google Patents

Description

The present invention relates to a resonator that attenuates acoustic energy by resonating an engine intake sound of an automobile in a resonance box.

As a relational expression of the natural acoustic frequency of the resonator, the following formula 1 is known as a formula of the natural acoustic frequency f ₀ of the Helmholtz resonator.

Mechanical Acoustic Engineering (Corona) 40 pages (4.99)

Here, f ₀ is the natural acoustic frequency, c is the speed of sound, S is the cross-sectional area of the conduit, L (in lower case) L is the length of the conduit, and V is the volume of the resonance box.

As can be seen from Equation 1, when designing a resonator with the intention of a low natural acoustic frequency, it is effective to lengthen the length L of the conduit, so that the conduit 3 as shown in FIG. A long resonator 1 may be set.

FIG. 1 is a perspective view of the resonator 1. The edge 12 of the conduit 3 of the resonator 1 and the intake pipe 2 separate from the resonator 1 are welded, that is, melt bonded.

2 and 3 are cross-sectional views taken along line AA of FIG. 1, and FIG. FIG. 3 shows a state before welding with the outer peripheral portion 13 of the conductive hole 11 provided in the welded seat 10 of the intake pipe 2 and the edge portion 12 of the conventional conductive tube 3. Represents the state after welding.

As shown in FIG. 3, the melted portions of the edge portion 12 and the outer peripheral portion 13 are crimped to protrude to the side to form a welding burr 6, and the welding burr 6 generates the conductive tube 3. Since the effective inner diameter d of the conductive tube 3 is reduced and the cross-sectional area S of the conductive tube 3 is reduced as the numerical formula 1 implies, the natural acoustic frequency f _{0 of the} resonator 1 is also reduced. 6 had to be processed by post-processing.

There is an example as disclosed in FIG. 3 in Patent Document 1 as a conventional technique related to the processing of the welding burrs of the resonator, but in this example, there is no guide tube or the guide tube has a very short shape. For this reason, the method as disclosed in Patent Document 1 cannot be applied to a resonator having a long conductor portion as shown in FIG.
JP-A-5-77321

The problem to be solved is that the effective inner diameter of the conduit is reduced by welding burrs, and the cross-sectional area S of the conduit is reduced as the equation 1 implies, so that the natural acoustic frequency f _{0 of the} resonator is also reduced. Since it becomes small, it is necessary to process the welding burr by post-processing. The present invention has been made to solve the above-described points.

The present invention is based on blow molding of a thermoplastic resin.
A resonator that is provided with a stepped portion extending in a direction in which both the inner and outer diameters of the conduit are increased at the end of the conduit integrated with the resonance box, and a welding burr chamber in the step. The most important feature is to provide a resonator formed by welding the outer peripheral portion of the conduction hole provided on the welding seat of the intake pipe made of thermoplastic resin and the edge of the stepped portion.

According to the present invention, since the stepped portion extending in the direction of increasing the diameter of the conductive tube is provided at the end portion of the conductive tube integrated with the resonance box, the welding burr is generated in the welding burr chamber of the stepped portion. Therefore, there is an advantage that the diameter of the conduit is not narrowed and the welding burr need not be processed in post-processing.

For the purpose of eliminating the need to process the welding burr in post-processing, at the end of the conduit integrated with the resonance box, a stepped portion extending in the direction of increasing the diameter of both the inner and outer diameters of the conduit, By providing a welding burr chamber in the step,
This was achieved without compromising the economics of blow molding.

The configuration of the present invention will be described based on the embodiments of the invention as follows. In addition, the same code | symbol as a prior art example represents the same member.

FIG. 4 is a view showing one embodiment of the present invention, and corresponds to the AA cross section of FIG.
A stepped portion 7 that widens in the direction of increasing the diameter of the conduit 3 at the end of the conduit 3 of the resonator 1 by blow molding of thermoplastic resin.
And a welding burr chamber 8 in the stepped portion 7.
Is provided.

Next, the operation of the present invention will be described. A semi-molten thermoplastic resin parison (not shown) is suspended in a split mold (not shown), and the split mold is clamped.

The thermoplastic resin applied to the parison is not limited to polypropylene, but polyethylene, other polyolefin resins, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins, polyacetal resins, syndiotactic. Any resin that can be blow molded, such as polystyrene, polystyrene, rubber-modified polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, modified polyphenylene oxide, polyphenylene sulfide, and polycarbonate, may be used. Further, a composite material obtained by kneading glass fiber, carbon fiber, boron fiber, calcium sulfate, calcium carbonate, or the like with the thermoplastic resin may be used.

Thereafter, compressed air is blown into the parison, and the blow molding of the resonator 1 is completed.

Similarly, blow molding of the intake pipe 2 is completed.

The resonator 1 and the intake pipe 2 formed by the above process are welded as shown in FIG.

Examples of the welding method include hot plate welding, ultrasonic welding, friction welding, and the like, and any method may be used.

Since the welding burr 6 generated at this time remains in the welding burr chamber 8 of the stepped portion 7 as shown in FIG. 4, the effective inner diameter d of the conductive tube 3 is not reduced.

In the above embodiment, the intake pipe 2 is formed by blow molding. However, thermoplastic resin injection molding may be used.

As described in the above embodiments, according to the present invention, by blow molding of thermoplastic resin
A resonator that is provided with a stepped portion extending in the direction of increasing the inner diameter and outer diameter of the conduit at the end of the conduit integrated with the resonance box, and a welding burr chamber in the step. Therefore, since the weld burr is generated in the weld burr chamber of the step portion, the effective inner diameter of the conduit is not narrowed, and there is no need to process the weld burr in post-processing. is there.

The present invention is applicable to a resonator for automobiles.

A perspective view of a conventional resonator It is AA sectional drawing of FIG. 1, and represents the state before welding of the conventional resonator. It is AA sectional drawing of FIG. 1, and represents the state after welding of the conventional resonator. It is an AA cross-section equivalent view of FIG. 1, and represents the state after welding of the resonator of the present invention.

DESCRIPTION OF SYMBOLS 1 Resonator 2 Intake pipe 3 Conductor tube 4 Resonance box 6 Weld burr 7 Step part 8 Weld burr chamber 10 Weld seat 11 Conduction hole 12 Edge part 13 Outer part d Effective diameter of guide pipe

Claims (1)

By blow molding of thermoplastic resin
A resonator that is provided with a stepped portion extending in a direction in which both the inner and outer diameters of the conduit are increased at the end of the conduit integrated with the resonance box, and a welding burr chamber in the step. A resonator comprising: an outer peripheral portion of a conduction hole provided in a welding seat of an intake pipe made of a thermoplastic resin, and an edge portion of the step portion.