WO2019146165A1

WO2019146165A1 - Silencer

Info

Publication number: WO2019146165A1
Application number: PCT/JP2018/036933
Authority: WO
Inventors: 秀明高野
Original assignee: 株式会社マキタ
Priority date: 2018-01-23
Filing date: 2018-10-02
Publication date: 2019-08-01
Also published as: JP2019127723A

Abstract

A silencer 40 connected to the air blowing pipe 30 of an air blowing working machine 10 is provided with: a silencer pipe 41 connected to the air blowing pipe 30 and having a sound absorbing material 42 disposed on the inner peripheral surface thereof; and a reflecting protrusion 43 which is provided protruding inward from the inner peripheral surface of the silencer pipe 41, and by which air flowing through the radial center of the silencer pipe 41 is reflected and caused to flow along and around the periphery of the sound absorbing material 42.

Description

Silencer

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a silencer used by being connected to an air duct of a blower working machine such as a blower.

JP-A-2015-083816 discloses a blower which blows out air to blow and collect fallen leaves and the like. The blower includes a blower unit mounted on a back and forth frame to eject air, and an air duct connected to the air duct portion of the blower unit, so that the air delivered from the blower unit is ejected from the tip of the air duct. .

In an air blower such as a blower disclosed in JP-A-2015-083816, for example, the engine of the drive source of the blower unit is replaced with an electric motor to reduce driving noise, or on the inner circumferential surface of the air duct. There has been developed a system in which noise generated from a blower working machine is minimized as much as possible by arranging a sound absorbing material to reduce the blast noise generated from the air passing through the blast tube. However, even if the sound absorbing material is disposed on the inner peripheral surface of the air blow pipe, although the air flow noise generated from the air passing around the inner peripheral surface of the air blow pipe can be reduced, it passes through the central portion in the radial direction of the air blow pipe. The blowing noise generated from the air could not be reduced. An object of this invention is to aim at reduction of the blowing noise which arises from the air which passes the blast pipe of a ventilation work machine.

In order to solve the above-mentioned problems, the present invention is a silencer connected to a blast tube of a blower working machine, and the silencer is a silencer tube connected to the blast tube and having a sound absorbing material disposed on the inner circumferential surface And a reflective protrusion provided so as to project inward from the inner peripheral surface of the muffling pipe, and reflecting air passing through a central portion in the radial direction of the muffling pipe to pass around the sound absorbing material. To provide a silencer.

In the silencer configured as described above, when air sent from the air blowing pipe passes through the muffling pipe, not only the air blowing noise generated from the air passing around the inner peripheral surface of the muffling pipe can be reduced by the sound absorbing material By reflecting the air passing through the central portion in the radial direction of the sound deadening pipe so as to pass the periphery of the sound absorbing material by the reflecting projection, the effect of reducing the blowing noise can be enhanced.

In the silencer comprised as mentioned above, it is preferable that the length in the axial direction of the muffling pipe of a reflective protrusion shall be 200 mm or more. By making the reflecting protrusion 200 mm or more, it becomes possible to reflect an acoustic wave of noise of 190 to 260 mm (f = 1.3 to 1.8 kHz) generated by this kind of blower working machine around the sound absorbing material. The In addition, in this silencer, it is preferable to make a reflective protrusion 300 mm or less.

In addition, it is preferable to set the maximum projected area of the reflective projection as viewed from the direction in which the air flows in the blast pipe to 10% to 30% of the cross-sectional area in the radial direction of the muffling pipe. In addition, it is preferable that the reflecting projection be formed into a spindle shape in which the width is expanded after advancing in the axial direction of the muffling pipe and then narrowed again. In this case, it is possible to sufficiently reduce the blowing noise while securing a sufficient amount of air passing through the muffle tube.

In the silencer configured as described above, a plurality of reflective protrusions may be arranged in the circumferential direction of the muffle tube, and in this case, the plurality of reflective protrusions are arranged mutually offset in the axial direction of the muffle tube You may

It is a side view of the blower using the silencer of the present invention. It is a perspective view of a silencer. It is an axial side view of a silencer. It is AA sectional drawing. It is a perspective view of the silencer of other embodiments. It is the side view seen from the axial direction of the silencer of FIG.

Representative and non-limiting embodiments of the present invention are described in detail below with reference to the drawings. This detailed description is merely intended to show the person skilled in the art the details for practicing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Also, the additional features disclosed and the invention can be used separately or together with other features and inventions to provide a further improved silencer.

Also, the combination of features and processes disclosed in the following detailed description is not essential to the practice of the present invention in its broadest sense, and in particular, to illustrate representative examples of the present invention. It is described. Furthermore, various features of the following representative embodiments, as well as various features of what is described in the claims, can be used to provide additional and useful embodiments of the present invention. It does not have to be combined as in the example or in the order listed.

All the features described in the present specification and / or the claims are different from the configuration of the features described in the examples and / or the claims, the disclosure at the beginning of the application, and the identification described in the claims. It is intended to be disclosed individually and independently of one another as a limitation on matters. In addition, the descriptions of all numerical ranges and groups or groups are intended to disclose intermediate constructions as limitations on the initial disclosure of the application as well as specific matters described in the claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a backpack blower, which is an embodiment of a portable blower working apparatus using a silencer according to the present invention, will be described below with reference to the attached drawings. As shown in FIG. 1, the backpack blower 10 includes a backpack frame 11 carried by a worker, a blower unit 20 mounted on the backpack frame 11, a blower tube 30 connected to a blower duct 21 a of the blower unit 20, and a blower. And a silencer 40 interposed in the pipe 30. The backrest frame 11 is for the worker to carry the blower unit 20 on his back. The backrest frame 11 is composed of a back plate 12 disposed along the back of the worker and a pedestal 13 extending rearward from the lower end of the back plate 12 and is L-shaped when viewed from the side. . A volute 21 is mounted on the front side of the pedestal portion 13 of the backrest frame 11.

As shown in FIG. 1, the blower unit 20 includes a volute 21, an impeller (not shown) rotatably provided in the volute 21, and a motor 22 that rotates the impeller. An air duct 21 a is formed on the side of the volute 21, and the air sent out in the centrifugal direction by the rotation of the impeller in the volute 21 is ejected from the air duct 21 a.

As shown in FIG. 1, the air duct 30a is connected to the air duct 21a, and the air duct 30 is connected to the elbow pipe 31 rotatably connected to the air duct 21a and the bellows connected to the elbow pipe 31. A pipe 32 and a straight pipe 33 connected to the bellows pipe 32 via the silencer 40 are provided. An operation handle 34 is provided on the air duct 30, and the operation handle 34 enables the operation of the air duct 30. Further, a throttle lever 34a is provided on the operation handle 34, and the output of the motor 22 is adjusted by the operation of the throttle lever 34a. In this embodiment, the operation handle 34 is attached to the air duct 30 via the silencer 40.

As shown in FIGS. 1 to 4, the silencer 40 is for reducing the blowing noise passing through the blower tube 30, and the silencer 40 is interposed between the bellows tube 32 and the straight tube 33 of the blower tube 30. A mounted muffle tube 41 is provided. As shown in FIG. 4, a sound absorbing material 42 is attached to the inner peripheral surface of the muffling pipe 41, and the sound absorbing material 42 has a function of absorbing and reducing the blowing noise passing through the muffling pipe 41. There is. The sound absorbing material 42 attached to the inner circumferential surface of the muffle tube 41 is made of a foamed polyurethane material having a thickness of 10 mm, and a coating having a smooth surface having a thickness of 100 μm is formed on the surface of the sound absorbing material 42. The inner diameter when the sound absorbing material 42 of the muffling pipe 41 is not attached is 900 mm, and the inner diameter when the sound absorbing material 42 of the muffling pipe 41 is provided is 700 mm. The inner diameter of the portion provided with the sound absorbing material 42 of the muffling pipe 41 is substantially the same as the inner diameter of the air blowing pipe 30, and does not serve as a resistance to air flowing from the air blowing pipe 30 through the muffling pipe 41.

As shown in FIGS. 2 to 4, the muffling pipe 41 is provided with a reflecting projection 43 projecting inward, and the reflecting projection 43 muffles the air passing through the central portion in the radial direction of the muffling pipe 41. It is reflected so as to pass around the sound absorbing material 42 provided on the inner circumferential surface of the tube 41. The reflecting projections 43 are provided on both sides in the radial direction of the muffling pipe 41, and the reflecting projections 43 have a spindle shape in which the width is expanded as it proceeds in the axial direction of the muffling pipe 41 and then narrowed again. The length in the axial direction of the reflective protrusion 43 is 250 mm, and the sound wave of the noise of wavelength 190 to 260 mm (f = 1.3 to 1.8 kHz) generated by the backpack blower 10 is reflected around the sound absorbing material 42 I am trying to By setting the length in the axial direction of the reflective protrusion 43 to 200 mm or more, and more preferably 300 mm or less, sound waves of noise of wavelength 190 to 260 mm (f = 1.3 to 1.8 kHz) can be absorbed by the sound absorbing material 42 Suitable for reflecting around the

In addition, a substantially central portion in the axial direction of the reflective protrusion 43 is a portion that protrudes inward most, and the width of this portion is 30 mm and the height is 30 mm. The maximum projected area of the reflective projection 43 as viewed from the flow direction of the air in the air blow pipe 30 is a ratio of 10% of the cross sectional area of the sound deadening pipe 41 in the radial direction. The cross-sectional area of the reflective protrusion 43 is 20% of the cross-sectional area of the muffle tube 41 by providing the reflective protrusion 43. By setting the maximum projected area of the two reflecting projections 43 to be 20% of the cross-sectional area of the muffling pipe 41, the amount of air passing through the muffling pipe 41 can be sufficiently secured, and the blowing noise can be sufficiently reduced. it can. When the maximum projected area of the reflective projection 43 is 10% to 30% of the cross-sectional area of the muffling pipe 41 in the radial direction, a sufficient amount of air passing through the muffling pipe 41 is ensured, and the blowing noise is reduced. It can be reduced sufficiently. As shown in FIGS. 5 and 6, the reflecting projections 43 disposed on both sides in the radial direction may be in contact with each other. Further, in this embodiment, the two reflecting protrusions 43 are arranged at the same position in the axial direction of the muffling pipe 41, but the invention is not limited thereto. The two reflecting protrusions 43 are mutually arranged in the axial direction of the muffling pipe 41 It may be arranged at different positions.

The operation of the backpack type blower 10 configured as described above will be described. When the prime mover 22 is driven by the operation of the throttle lever 34a, the impeller rotates, and the air sucked from the intake opening on the front side of the volute 21 is blown out in the centrifugal direction by the rotating impeller and the blown out air is The pressure is increased in the vortex type air flow path and sent to the air flow duct 21 a, and the air blown out from the air flow duct 21 a is blown out to the ground through the air flow pipe 30 and the silencer 40. When the worker grips the operation handle 34 of the air duct 30 and swings the tip opening to the left and right on the front side of the worker, fallen leaves and the like widely scattered on the ground are blown and collected.

A silencer 40 is interposed in the air duct 30 of the backpack type blower 10 configured as described above, and the silencer 40 is connected to the air duct 30 and a noise absorber 42 is disposed on the inner peripheral surface thereof. A pipe 41 and a reflection projection 43 which protrudes inward from the inner peripheral surface of the muffling pipe 41 and reflects air passing through the central portion in the radial direction of the muffling pipe 41 so as to pass the periphery of the sound absorbing material 42 Is provided. When the air sent from the bellows tube 32 of the air duct 30 passes through the muffling pipe 41, not only the air noise generated from the air passing around the inner peripheral surface of the muffling pipe 41 can be reduced by the sound absorbing material 42, but The air passing through the central portion in the radial direction 41 is reflected by the reflective projection 43 so as to pass the periphery of the sound absorbing material 42, so that the reduction effect of the blowing noise can be enhanced. Thus, the silencer 40 can reduce not only the blowing noise generated from the air passing around the inner peripheral surface of the muffle tube 41 but also the blowing noise generated from the air passing through the central portion in the radial direction, It became possible to enhance the effect of reducing blowing noise.

In this silencer 40, the length of the reflective protrusion 43 in the axial direction of the muffle tube 41 is 250 mm, and the reflective protrusion is set to 200 mm or more, and more preferably 300 mm or less in a more preferable range. A sound wave of noise having a wavelength of 190 to 260 mm (f = 1.3 to 1.8 kHz) can be reflected around the sound absorbing material 42, and the effect of reducing the blowing noise can be enhanced.

In this silencer 40, the maximum projected area of the two reflecting projections 43 as viewed from the flow direction of the air in the blast tube 30 (muffle tube 41) is 10% as 20% of the cross-sectional area of the muffle tube 41 in radial direction It is set to be included in the range of ~ 30%. In addition, the reflecting protrusion 43 is formed into a spindle shape which is narrowed in the axial direction of the muffling pipe 41 and expanded again after the width thereof is expanded. As a result, after sufficiently securing the amount of air passing through the muffle tube 41, the blowing noise can be sufficiently reduced.

In the above embodiment, although the silencer 40 is described as an embodiment of the blower type work machine which is an example of the blower working machine, the silencer 40 of the present invention is another kind of blower work machine like a dust collector, hand-held blower Alternatively, it may be applied to a hand-held dust collector.

Claims

It is a silencer connected to the blast tube of the blower work machine,
The silencer is provided with a muffling pipe connected to the air blowing pipe and having a sound absorbing material disposed on the inner circumferential surface, and is provided so as to protrude inward from the inner circumferential surface of the muffling pipe. A silencer having a reflective projection for reflecting air passing through the central portion to pass around the sound absorbing material.
In the silencer according to claim 1,
The silencer having a length of 200 mm or more in the axial direction of the muffling pipe of the reflection protrusion.
In the silencer according to claim 2,
The silencer having a length of 300 mm or less in the axial direction of the muffling pipe of the reflection protrusion.
The silencer according to any one of claims 1 to 3
A silencer, wherein a maximum projected area of the reflecting protrusion as viewed in a direction in which air flows in the air blowing pipe is 10% to 30% of a cross-sectional area in the radial direction of the muffling pipe.
The silencer according to any one of claims 1 to 4
A silencer having a spindle shape in which the reflecting projection is expanded in the axial direction of the muffling pipe to expand and then narrow again.
The silencer according to any one of claims 1 to 5,
A silencer, wherein a plurality of the reflection protrusions are arranged in the circumferential direction of the muffling pipe.
In the silencer according to claim 6,
A silencer, wherein the plurality of reflecting protrusions are arranged mutually offset in the axial direction of the muffling pipe.