JPH062045U - Electronic muffler installation air duct - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent the reduction of the muffling effect when the electronic muffler is installed immediately after the elbow part in an electronic muffler installation air duct. In the blower pipe 20 in which the electronic silencer 1 is arranged immediately after the elbow portion 21, the elbow portion 21 is used as a duct cross-sectional area expansion portion, or the elbow portion 21 and the electronic silencer 1 are installed. A pipeline cross-sectional area enlarged portion is provided between the pipeline 22 and the upstream end portion, and the pipeline end portion 22a of the pipeline 22 and the pipeline sectional area enlarged portion have a gentle change in cross-sectional area.
It is characterized by being connected by.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a blower pipe, and more particularly, to a blower pipe provided with a muffling device that electronically muffles a propagation sound propagating in a duct.

[0002]

[Prior art]

 Conventionally, sound-absorbing material or a pipe structure such as an expanded type or a bent type has been put to practical use for silencing the propagating sound propagating in the duct of the blower pipe. On the other hand, in recent years, an electronic muffling device has been developed which impinges a sound wave propagating from a noise source with a sound wave having an opposite phase and the same sound pressure; This electronic silencer is superior to the old type silencer in that it has a smaller silencer, low pressure loss, and a large silence effect in the low frequency band.

Next, the configuration and operation of this conventional electronic silencer will be described with reference to FIG. In FIG. 3, reference numeral 1 is an electronic silencer, 2 is a blower pipe, 3 is an arrow indicating a blowing direction, 4 is arranged in the blower pipe 2, and detects noise propagating from a noise source upstream of blowing air. The sensor microphones 5 and 5 are controllers for producing signals of the opposite phase and the same sound pressure radiated from the speaker 6 based on the signal from the first sensor microphone 4, respectively.

That is, the controller 5 transfers the transfer function from the first sensor microphone 4 to the speaker 6, which is the output end, and the first sensor microphone 4 in the conduit 2 a to the speaker 6 or downstream of the speaker 6. The transfer function up to the second sensor microphone 7 disposed in the pipe 2a on the side is compared, and the transfer that is multiplied by the first sensor microphone 4 so that the signal having the same sound pressure in the opposite phase is emitted from the speaker 6 I'm making a function. In addition, reference numerals 8, 9, and 10 respectively represent signal cables.

[0005]

However, in such a conventional electronic silencer, the main operation of the controller 4 is to create a transfer function as described above. Therefore, the transfer function in the blower pipe has a larger muffling effect and is more durable when the temporal change is as small as possible. Therefore, it is necessary to have a steady flow in the air duct system of the electronic muffler.However, in the conventional air duct, when this electronic muffler was installed immediately after the elbow, laminar flow separation occurred in the elbow. There was a problem that turbulent vortices were generated and the above-mentioned condition of steady flow was not satisfied.

It is an object of the present invention to provide a blower tube that prevents a reduction in the silencing effect when an electronic silencing device must be installed immediately after such an elbow part.

[0007]

[Means for Solving the Problems]

 The electronic muffler-equipped air blower of the present invention is provided with an expanded duct cross-sectional area between the elbow part or the elbow part of the upstream of the conduit where the electronic muffler is installed and the microphone of the electronic muffler. The present invention is characterized in that a pipeline in which a silencer is installed and the pipeline cross-sectional area enlarged portion are connected by a pipeline having a gentle change in cross-sectional area.

[0008]

[Action]

 According to the blower pipe with the electronic silencer of the present invention, the wind velocity in the duct becomes smaller (slower) in proportion to the cross-sectional area due to the enlarged duct cross-sectional area. Therefore, even in the elbow part, the separation of the laminar flow from the wall of the conduit is small, and the smooth cross-sectional area change to the original cross-sectional area promptly restores the steady flow, and the electronic silencer is installed. Through the pipeline.

[0009]

【Example】

 Hereinafter, the electronic muffler-installed air duct of the present invention will be described in more detail with reference to the embodiments shown in the drawings. FIG. 1 shows a blower pipe 20 with an electronic silencer according to an embodiment of the present invention. The blower pipe 20 is provided with an elbow portion 21, and the same device as the conventional electronic silencer 1 is installed in a pipe line 22 immediately after the elbow portion 21.

[0010] elbow section 21 constituting the blower tube 20, and the cross-sectional area of the duct other than the elbow and S _1, is formed to expand to a larger S ₂ from the S _1, thus The elbow portion 21 itself constitutes a section for enlarging the sectional area of the conduit. The downstream end 21a of the elbow 21 is connected to the upstream end 22a of the conduit 22 provided with the electronic silencer 1 by a conduit 23 having a gentle cross-sectional area change.

According to the electronic muffler-installed blower pipe 20 as described above, the airflow velocity in the pipeline becomes smaller or slower in proportion to the cross-sectional area due to the portion 21 that is the duct cross-sectional area expanding portion. Therefore, in the elbow portion 21, the separation of the laminar flow from the conduit wall is small, and the original cross-sectional area S ₁ It quickly returns to a steady flow by passing through the pipe line 23 having a gentle cross-sectional area change, and passes through the pipe line 22 in which the electronic silencer 1 is installed. Therefore, the transfer function in the conduit 22 changes little with time, so that the silencing effect is large and has a long duration.

By the way, the size of the cross-sectional area S ₂ in the expanded cross-sectional area of the duct, and the rate of change in the cross-sectional area of the duct 23 with a gentle change in cross-section are determined by the flow velocity of the blown air.

In the above-described embodiment, the duct cross-sectional area enlarged portion is formed in the elbow portion of the blower pipe, but as shown in FIG. 2, the elbow portion 31 having the cross-sectional area S ₁ and the electronic silencer 1 are installed. The same effect can be obtained even if the conduit cross-sectional area enlarged portion 32 having a cross-sectional area S _{2 and} the conduit 23 having a gentle cross-sectional area change are interposed between the conduit 22 and the upstream end 22a.

[0014]

[Effect of device]

 As described above, according to the electronic muffler-installed air duct of the present invention, the duct cross-sectional area expansion part is provided between the elbow part or the elbow part and the upstream end of the conduit where the electronic muffler is installed. By installing the electronic silencer and connecting the duct cross-sectional area expansion section with a pipe with a gently changing cross-sectional area, the air flow in the duct where the electronic silencer is installed is always maintained. Since a steady flow state can be achieved, even if an electronic muffling device is installed immediately after the elbow part, the electronic muffling effect is not deteriorated. Therefore, the electronic muffling device is installed immediately after the elbow part like this. Even in this case, it is not necessary to lengthen the air duct system, and it is possible to shorten the air duct.

[Submission date] January 29, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

[Prior art]

Conventionally, sound-absorbing material or a pipe structure such as an expanded type or a bent type has been put to practical use for silencing the propagating sound propagating in the duct of the blower pipe. On the other hand, with respect to the propagation sound from recent noise source, to radiate sound waves of this reverse phase a and same sound pressure, i.e. the electronic silencer for performing silencing by wave interference it has been developed. This electronic silencer is superior to the old type silencer in that it has a smaller silencer, low pressure loss, and a large silence effect in the low frequency band.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Delete

[Brief description of drawings]

FIG. 1 is a structural explanatory view schematically showing a blower pipe with an electronic silencer according to an embodiment of the present invention.

FIG. 2 is a structural explanatory view schematically showing an electronic muffler-installed air duct according to another embodiment of the present invention.

FIG. 3 is a structural explanatory view schematically showing a conventional electronic silencer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electronic silencer 4 First sensor microphone 5 Controller 6 Speaker 7 Second sensor microphone 20 Electronic silencer installation air duct 21 Elbow part 22 Electronic silencer installation pipeline 23 Pipeline with gentle cross-sectional area change

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[Procedure amendment]

[Submission date] January 29, 1993

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (1)

[Scope of utility model registration request] 1. A sound wave propagating from a noise source propagating in a pipe is detected by a microphone, and a sound wave having an opposite phase and the same sound pressure is generated from a speaker installed on the downstream side of the microphone. In an electronic muffler-installed air duct, in which an electronic muffler that muffles sound waves propagated by sound wave interference on the downstream side of the speaker is installed immediately after the elbow portion of the pipeline,
The elbow portion is a conduit cross sectional area enlarging portion, or a duct cross sectional area enlarging portion is provided between the elbow portion and the microphone of the electronic silencer, and the conduit in which the electronic silencer is installed and the A blower pipe with an electronic silencer, characterized in that the enlarged duct cross-sectional area is connected by a duct with a gentle cross-sectional area change.