BLOWER

Abstract

A blower may comprise: a fan configured to be driven by an electric motor; a blower tube having an air passage in which air flows by rotation of the fan; a nozzle disposed downstream relative to the blower tube in an air flow direction and having a discharge port configured to discharge the air; and a first sound absorbing member disposed on the blower tube and/or the nozzle at a position downstream relative to the fan in the air flow direction. When viewed in a cross section of the blower that is perpendicular to the air flow direction, in at least a portion of a region on which the first sound absorbing member is disposed, an area of the first sound absorbing member may be 60% or more and 200% or less of a flow passage area of the blower tube and/or the nozzle.

Description

CROSS REFERENCE TO RELATED APPLICATION(S

This application claims priority from Japanese Patent Application No. 2025-001700 filed on January 6, 2025. The entire content of the priority application is incorporated herein by reference.

TECHNICAL FIELD

The disclosure herein relates to a blower.

BACKGROUND ART

Japanese Patent Application Publication No. 2016-78005 describes a blower. The blower includes an electric motor, a fan configured to be driven by the electric motor, a blower tube having an air passage in which air flows by rotation of the fan, a nozzle disposed downstream relative to the blower tube in an air flow direction and having a discharge port configured to discharge the air, and a sound absorbing member disposed on the blower tube at a position upstream relative to the fan in the air flow direction.

SUMMARY

In the above-mentioned blower, it is desired that noise leaking outside from the fan through the nozzle is reduced. The present teachings provide an art that allows to suppress noise leaking outside from a fan through a nozzle.

A blower disclosed herein may comprise: an electric motor; a fan configured to be driven by the electric motor; a blower tube having an air passage in which air flows by rotation of the fan; a nozzle disposed downstream relative to the blower tube in an air flow direction and having a discharge port configured to discharge the air; and a first sound absorbing member disposed on the blower tube and/or the nozzle at a position downstream relative to the fan in the air flow direction. When viewed in a cross section of the blower that is perpendicular to the air flow direction, in at least a portion of a region on which the first sound absorbing member is disposed, an area of the first sound absorbing member may be 60% or more and 200% or less of a flow passage area of the blower tube and/or the nozzle.

In the above-described configuration, the first sound absorbing member is disposed on the blower tube and/or the nozzle at the position downstream relative to the fan in the air flow direction. Also, when viewed in the cross section of the blower that is perpendicular to the air flow direction, in at least a portion of the region on which the first sound absorbing member is disposed, the area of the first sound absorbing member is 60% or more and 200% or less of the flow passage area of the blower tube and/or the nozzle. Due to this, the noise leaking outside from the fan through the nozzle can be suppressed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a perspective view seeing a blower 2 according to the first embodiment from a front right side.

FIG. 2 illustrates a perspective view seeing the blower 2 according to the first embodiment from a front left side.

FIG. 3 illustrates a trigger 14 of the blower 2 and its surroundings, with a right-side grip housing 20 according to the first embodiment detached therefrom, from the right side.

FIG. 4 illustrates a perspective view seeing the blower 2, with the right-side grip housing 20 according to the first embodiment detached therefrom, from a rear right side.

FIG. 5 illustrates a cross-sectional view of the blower 2, with a grip housing 10 according to the first embodiment detached therefrom.

FIG. 6 illustrates an enlarged view of a portion VI in FIG. 5.

FIG. 7 illustrates a cross-sectional view of the blower 2 at a position where a plurality of guide vanes (stationary vanes) 76 according to the first embodiment is disposed.

FIG. 8 illustrates a cross-sectional view of the blower 2 at a position where an axial fan 88 according to the first embodiment is disposed.

FIG. 9 illustrates a cross-sectional view of the blower 2 at a position where a first sound absorbing member 102 according to the first embodiment is disposed.

FIG. 10 illustrates a cross-sectional view of the blower 2 at a position where a second sound absorbing member 104 according to the first embodiment is disposed.

FIG. 11 illustrates the axial fan 88 according to the first embodiment from the right side.

FIG. 12 shows measuring results when a thickness T1 of the first sound absorbing member 102 is changed in the blower 2 according to the first embodiment.

FIG. 13 shows measuring results of a sound power level when a length L1 of the first sound absorbing member 102 is changed in the blower 2 according to the first embodiment.

FIG. 14 illustrates a cross-sectional view of a blower 2A with a grip housing 10 according to the second embodiment detached therefrom.

FIG. 15 illustrates a cross-sectional view of the blower 2A at a position where a blower tube 154 according to the second embodiment is disposed.

FIG. 16 illustrates a cross-sectional view of a blower 2B with a grip housing 10 

according to the third embodiment detached therefrom.

FIG. 17 illustrates a cross-sectional view of the blower 2B at a position where a blower tube 254 according to the third embodiment is disposed.

FIG. 18 illustrates a cross-sectional view of a rear portion of a blower 2C with a grip housing 10 according to the fourth embodiment detached therefrom.

FIG. 19 illustrates a cross-sectional view of the blower 2C at a position where a second sound absorbing member 404 and a third sound absorbing member 406 according to the fourth embodiment are disposed.

FIG. 20 illustrates the blower 2C according to the fourth embodiment from the rear side.

DETAILED DESCRIPTION

Representative, non-limiting examples of the present disclosure will now be described in further detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the present disclosure. Furthermore, each of the additional features and teachings disclosed below may be utilized separately or in conjunction with other features and teachings to provide improved blowers, as well as methods for using and manufacturing the same.‍

Moreover, combinations of features and steps disclosed in the following detailed description may not be necessary to practice the present disclosure in the broadest sense, and are instead taught merely to particularly describe representative examples of the present disclosure. Furthermore, various features of the above-described and below-described representative examples, as well as the various independent and dependent claims, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.‍

All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

In one or more embodiments, a length along the air flow direction of the at least portion of the region on which the first sound absorbing member is disposed may be 150 mm or more and 250 mm or less.

In the above configuration, the first sound absorbing member can effectively absorb noise generated from the fan, and also the first sound absorbing member can be downsized.

In one or more embodiments, a volume of the first sound absorbing member may be 8.0×10⁵ mm³ or more and 3.6×10⁶ mm³or less.

In the above configuration, the first sound absorbing member can effectively absorb noise generated from the fan, and also the first sound absorbing member can be downsized.

In one or more embodiments, at least a portion of the first sound absorbing member is disposed at a position where a flow passage area of the blower tube and/or the nozzle decreases.

In many blowers, position(s) where a flow passage area decreases exist in the blower tube and/or nozzle in order to accelerate the flow speed of the air. According to the above configuration, by disposing the first sound absorbing member at such position where the flow passage area decreases, the blower can be downsized as compared to when the first sound absorbing member is disposed elsewhere.

In one or more embodiments, the fan may be an axial fan disposed inside the blower tube.

In the above configuration, the noise generated from the axial fan can be effectively suppressed from leaking outside from within the blower tube through the nozzle.

In the above embodiment, a flow passage area of the blower tube at a position at which the axial fan is disposed may be smaller than a flow passage area of the blower tube and/or the nozzle at a downstream end of the first sound absorbing member in the air flow direction.

If the flow passage area of the blower tube at the position at which the axial fan is disposed is greater than the flow passage area of the blower tube and/or the nozzle at the downstream end of the first sound absorbing member in the air flow direction, it is difficult for air to be discharged from the discharge port and thus the axial fan needs to feed the air at a relatively high pressure. In this case, because pressure change near the axial fan increases, noise leaking outside from the axial fan through the nozzle can possibly be increased. In the above configuration, the pressure when the axial fan feeds the air can be made smaller, and thus pressure change of the air near the axial fan can be made smaller. Due to this, noise leaking outside from the axial fan through the nozzle can be suppressed.

In one or more embodiments, the axial fan may comprise a hub and a plurality of blades disposed on an outer side surface of the hub. A product of a number of the plurality of blades and a rated rotational speed of the axial fan may be 2.6×10⁵ or more and 1.2×10⁶ or less.

The frequency of sound generated by rotation of the axial fan varies depending on the product of the number of the plurality of blades and the rated rotational speed of the axial fan. In the above configuration, the frequency of the sound generated by rotation of the axial fan falls outside the most-disturbing frequency range for the operator. Due to this, even when the noise leaks outside the blower, discomfort the operator feels can be reduced.

In one or more embodiments, the first sound absorbing member may include a sponge member. The sponge herein mentioned broadly means porous flexible materials.

In the above configuration, the sound energy of noise generated from the fan translates into thermal energy due to the sponge member when the noise passes through the first sound absorbing member. Due to this, noise leaking outside from the fan through the nozzle can be suppressed.

In one or more embodiments, the sponge member may be constituted of urethane.

According to the above configuration, noise leaking outside from the fan through the nozzle can be more effectively suppressed.

In one or more embodiments, the first sound absorbing member may be disposed on the nozzle.

In the above configuration, it is easier to manufacture the blower than when the first sound absorbing member is disposed on the blower tube.

In one or more embodiments, the blower may further comprise a second sound absorbing member disposed on the blower tube at a position upstream relative to the fan in the air flow direction.

In the above configuration, the noise leaking outside from the fan through the blower tube at the position upstream of the fan can be suppressed.

In one or more embodiments, a length of the first sound absorbing member along the air flow direction may be greater than a length of the second sound absorbing member along the air flow direction.

In the above configuration, the first sound absorbing member can effectively absorb the noise and also can suppress the noise leaking outside from the axial fan through the nozzle.

First Embodiment

A blower 2 shown in FIGS. 1, 2 is used for blowing and gathering fallen leaves for example. The blower 2 comprises a grip housing 10, a power cable 12, a trigger 14, a cruise control lever 16, and a control part 18 (see FIG. 4). Here, in the following description, a longitudinal direction of the blower 2 will be termed a front-rear direction, a direction perpendicular to the front-rear direction will be termed an up-down direction of the blower 2, and a direction perpendicular to both the front-rear and up-down directions will be termed a left-right direction of the blower 2.

The grip housing 10 is composed of a right-side grip housing 20 and a left-side grip housing 22. The right-side grip housing 20 defines the outer shape of the right half of the grip housing 10, and the left-side grip housing 22 defines the outer shape of the left half of the grip housing 10.

The grip housing 10 comprises a first housing 24, a second housing 26, a third housing 28, and a fourth housing 30. The first housing 24, the second housing 26, the third housing 28, and the fourth housing 30 are integrally configured with each other. The first housing 24 extends in the longitudinal direction. The second housing 26 extends from a front portion of an upper surface of the first housing 24 to a rear upper side. The third housing 28 extends from a rear portion of the upper surface of the first housing 24 to the rear upper side. The fourth housing 30 extends from an upper portion of a rear surface of the second housing 26 toward an upper portion of a front surface of the third housing 28. The cross-sectional shape of the fourth housing 30 is substantially circular. The fourth housing 30 is configured to be grasped by an operator. The power cable 12 is connected to the rear surface of the third housing 28. The blower 2 is supplied with electric power via the power cable 12. The power cable 12 is connected to a back-pack type battery (not illustrated) configured to be worn on his/her back by the operator or to an external power supply (not illustrated).

A main power switch 32 and a main power LED 34 are disposed on an upper surface of the third housing 28. The main power switch 32 receives operations for switching between an ON state and an OFF state of the blower 2 from the operator. The main power LED 34 indicates the ON state and the OFF state of the blower 2.

The trigger 14 is attached below a front portion of the fourth housing 30. The operator can operate the trigger 14 with a finger of his/her hand which is grasping the fourth housing 30. As illustrated in FIG. 3, the trigger 14 comprises a trigger operation part 36, a trigger protrusion 38, and a switch push-in part 40. The trigger operation part 36, the trigger protrusion 38, and the switch push-in part 40 are configured integrally with each other. The trigger operation part 36 is supported by the second housing 26 so as to be pivotable about a pivot axis AX1. The pivot axis AX1 is disposed at the front end of the trigger operation part 36. When the trigger operation part 36 is operated to be pushed in by the operator, the trigger operation part 36 pivots about the pivot axis AX1.

The trigger protrusion 38 and the switch push-in part 40 are disposed within the second housing 26. The trigger protrusion 38 is disposed at the front end of the trigger operation part 36. The trigger protrusion 38 extends in a direction which is substantially perpendicular to the upper surface of the trigger operation part 36. The switch push-in part 40 is disposed at the front end of the trigger operation part 36. The switch push-in part 40 extends from the trigger operation part 36 to a front upper side. The trigger protrusion 38 and the switch push-in part 40 pivot about the pivot axis AX1 integrally with the trigger operation part 36. When the trigger operation part 36 pivots, the switch push-in part 40 pushes in the first switch 42 downward. Also, when the trigger operation part 36 pivots beyond a predetermined position, a plate member 44 is pushed rearward, by which a second switch 46 is pushed in.

As illustrated in FIGS. 1, 2, the cruise control lever 16 is attached to the second housing 26 at a position near a connection portion between the second housing 26 and the fourth housing 30. As illustrated in FIG. 3, the cruise control lever 16 is configured to pivot about a pivot axis AX2. The pivot axis AX2 is disposed above and rearward from the pivot axis AX1. Here, a cushion (not illustrated) is disposed between the cruise control lever 16 and the second housing 26. The cruise control lever 16 is held at a desired position by friction received from the cushion. As illustrated in FIG. 2, the cruise control lever 16 comprises a lever operation part 48 and a stopper 50 (see FIG. 3). The lever operation part 48 is disposed outside the second housing 26. The lever operation part 48 is configured to be operated by the operator. As illustrated in FIG. 3, the stopper 50 is disposed inside the second housing 26. When the lever operation part 48 is operated, the stopper 50 pivots about the pivot axis AX2. The stopper 50 is configured to contact the trigger protrusion 38 from the rear side. When the stopper 50 pivots further frontward from the state of being in contact with the trigger protrusion 38 from the rear side, the trigger protrusion 38 pivots frontward, by which the trigger 14 is pushed in. In the state where the stopper 50 is in contact with the trigger protrusion 38, the trigger protrusion 38 cannot return to the rear side any further. Due to this, the trigger 14 is maintained in the state of being pushed in.

As illustrated in FIGS. 1, 2, the front face of the first housing 24 has an opening 52. The opening 52 is disposed near a connection portion between the first housing 24 and the second housing 26. The opening 52 connects inside and outside of the grip housing 10.

As illustrated in FIG. 4, the control part 18 is disposed inside the first housing 24. The control part 18 is disposed along the front-rear direction and the left-right direction. The control part 18 is disposed near the connection portion between the first housing 24 and the second housing 26. In the up-down direction, the control part 18 is disposed above the opening 52. Although not illustrated, the control part 18 is composed of a control board including a microcontroller and a plurality of switching devices and a casing to which the control board is attached. The switching devices are for examples IGBTs or MOSFETs. The switching devices are configured to be switched between the ON state and the OFF state by being controlled by the microcontroller.

As illustrated in FIG. 5, the blower 2 further comprises a blower tube 54, a nozzle 60, and a cover member 62. The blower tube 54 comprises a motor housing 56, a rear housing 58, and a front housing 66. The motor housing 56 is disposed inside the first housing 24 (see FIG. 1).

The rear housing 58 is coupled to the rear end of the motor housing 56, and protrudes rearward from the rear end of the first housing 24. Also, the rear housing 58 is fixed to the first housing 24. The front housing 66 is coupled to the front end of the motor housing 56, and protrudes frontward from the front end of the first housing 24. The front housing 66 is fixed to the first housing 24. The nozzle 60 is detachably coupled to the front end of the front housing 66. The blower tube 54 has an air passage 55 therein. The air passage 55 comprises an upstream air passage 64, an intermediate air passage 82, and a downstream air passage 72.

As illustrated in FIG. 5, the rear housing 58 has a tubular shape in which the diameter of the internal circumferential surface decreases from rear to front. The rear housing 58 has the upstream air passage 64 therein. The cover member 62 is attached to the rear end of the rear housing 58. The cover member 62 covers an opening at the rear end of the rear housing 58. The cover member 62 has a plurality of intake ports 62a. The plurality of intake ports 62a extends through the cover member 62 in the front-rear direction (i.e., axial direction of the rotation axis of the axial fan 88). The plurality of intake ports 62a connects outside of the blower 2 and the upstream air passage 64 of the rear housing 58. The plurality of intake ports 62a is disposed over the entirety of the cover member 62.

As illustrated in FIG. 6, the front housing 66 has a tubular shape in which a diameter of an internal circumferential surface decreases from rear to front. The front housing 66 has the downstream air passage 72 therein. Although not illustrated, the upper end of the front housing 66 has an opening, and the opening is disposed below the control part 18. As illustrated in FIG. 5, the nozzle 60 comprises a first nozzle 68 and a second nozzle 70. The first nozzle 68 is detachably attached to the front end of the front housing 66. The second nozzle 70 is detachably attached to the front end of the first nozzle 68. The first nozzle 68 and the second nozzle 70 have tubular shapes. A discharge port 70a is defined at the distal end of the second nozzle 70.

As illustrated in FIG. 6, the motor housing 56 comprises an outer tubular member 74, a plurality of guide vanes (stationary vanes) 76, an inner tubular member 78, and a lid member 80. The outer tubular member 74, the plurality of guide vanes 76, and the inner tubular member 78 are integrally configured with each other. The outer tubular member 74 has a tubular shape extending in the front-rear direction. The outer tubular member 74 has the intermediate air passage 82 therein. The upstream end of the intermediate air passage 82 communicates with the upstream air passage 64 of the rear housing 58, and the downstream end of the intermediate air passage 82 communicates with the downstream air passage 72 of the front housing 66. As illustrated in FIG. 7, the plurality of guide vanes 76 extends from the inner circumferential surface of the outer tubular member 74 toward the central axis of the outer tubular member 74. The plurality of guide vanes 76 is disposed at equal intervals in the circumferential direction of the inner circumferential surface of the outer tubular member 74.

The inner tubular member 78 is disposed inside the outer tubular member 74. The inner tubular member 78 extends in the front-rear direction. The plurality of guide vanes 76 extending from the inner circumferential surface of the outer tubular member 74 is connected to the outer circumferential surface of the inner tubular member 78. As illustrated in FIG. 6, the lid member 80 is attached to the rear end of the inner tubular member 78. The lid member 80 closes a rear end opening 78a of the inner tubular member 78. A plurality of holes (not illustrated) is defined at the rear end of the lid member 80. A cone 84 is attached to the front end of the inner tubular member 78. The diameter of the outer circumferential surface of the cone 84 decreases from rear to front. A tip opening 84a is defined at the distal end of the cone 84.

The blower 2 further comprises an electric motor 86 and an axial fan 88. The electric motor 86 is for example a brushless motor of an inner rotor type. In a modification, the electric motor 86 may be a brushless motor of an outer rotor type or may be a brushed motor. The electric motor 86 rotates with electric power supplied through the power cable 12 (see FIG. 1). The electric motor 86 comprises a rotor 90, a stator 92, and a shaft 94. The rotor 90 and the stator 92 are disposed inside the inner tubular member 78. The rotor 90 extends in the front-rear direction. The rotation center of the rotor 90 is the same as the center of the inner circumferential surface of the outer tubular member 74. The stator 92 surrounds the outer circumferential surface of the rotor 90. The shaft 94 extends rearward from within the inner tubular member 78, and then extends through the lid member 80 to the outside of the inner tubular member 78. The shaft 94 is rotatably supported by the lid member 80 via a bearing 96. The shaft 94 rotates integrally with the rotor 90.

Operation of the electric motor 86 is controlled by the microcontroller (not illustrated) of the control part 18 (see FIG. 4) performing controls for switching the ON state and the OFF state of the switching devices (not illustrated). When the first switch 42 (see FIG. 4) is pushed in, the electric motor 86 is controlled at a rotation speed depending on a degree at which the first switch 42 is pushed in. Here, as the degree of the first switch 42 being pushed in increases, the rotation speed of the electric motor 86 increases. On the other hand, when the second switch 46 (see FIG. 4) is pushed in, the electric motor 86 is controlled at a predetermined rotation speed. In the present embodiment, the rotation speed of the electric motor 86 when the second switch 46 is pushed in is greater than the maximum value of the rotation speed of the electric motor 86 when the first switch 42 is pushed in.

The axial fan 88 is attached to the rear end of the shaft 94. The axial fan 88 is disposed inside the outer tubular member 74. The axial fan 88 rotates by operation of the electric motor 86. The axial fan 88 comprises a hub 98 and a plurality of blades 100. The hub 98 and the plurality of blades 100 are configured integrally with each other. As illustrated in FIG. 8, the plurality of blades 100 is disposed at equal intervals along the circumferential direction of an outer side surface 98a of the hub 98.

Next, a blowing operation using the blower 2 shown in FIGS. 1, 2 will be described. When the trigger 14 is operated by the operator while the blower 2 is in the ON state, the electric motor 86 (see FIG. 6) is driven by control of the control part 18 (see FIG. 4). As illustrated in FIG. 6, the axial fan 88 rotates integrally with the shaft 94 of the electric motor 86. When the axial fan 88 rotates, a negative pressure is generated at the rear side of the axial fan 88. Due to this, the air flows from the plurality of intake ports 62a of the cover member 62 into the upstream air passage 64 of the rear housing 58 and flows in the intermediate air passage 82 of the outer tubular member 74, as illustrated in FIG. 5. Thereafter, the air is sent farther downstream by the axial fan 88, flows in the downstream air passage 72 of the front housing 66, flows in the nozzle 60, and is discharged from the discharge port 70a of the second nozzle 70. Further, as illustrated in FIG. 6, a portion of the air sent by the axial fan 88 enters the inside of the inner tubular member 78 through the plurality of holes (not illustrated) defined at the rear end of the lid member 80, flows frontward inside the inner tubular member 78, and then flows from the tip opening 84a of the cone 84 to the downstream air passage 72. Due to this, the electric motor 86 is cooled. Further, a portion of the air flowing in the downstream air passage 72 flows in the opening (not illustrated) at the upper end of the front housing 66, and flows to the outside of the front housing 66. As illustrated in FIG. 4, the air having flowed out flows between the lower surface of the control part 18 and the outer circumferential surface of the front housing 66, and flows from the opening 52 to the outside of the grip housing 10. Due to this, the control part 18 is cooled.

As illustrated in FIG. 5, the blower 2 further comprises a first sound absorbing member 102 and a second sound absorbing member 104. The first sound absorbing member 102 and the second sound absorbing member 104 are sponge members. The sponge members herein mentioned broadly mean a porous flexible material. The sponge member in the present embodiment is constituted of urethane.

As illustrated in FIG. 5, the first sound absorbing member 102 is disposed on the first nozzle 68. A portion of the first nozzle 68 comprises a sound absorbing member mount part 68a, having the diameter of the inner circumferential surface greater than those of the other portions. The first sound absorbing member 102 has a tubular shape extending in the front-rear direction. As illustrated in FIG. 9, the first sound absorbing member 102 is disposed along the inner circumferential surface in the sound absorbing member mount part 68a of the first nozzle 68. As illustrated in FIG. 5, the diameter of the inner circumferential surface of the first sound absorbing member 102 disposed at the sound absorbing member mount part 68a is substantially equal to both of the diameter of the inner circumferential surface at a portion where the sound absorbing member mount part 68a of the first nozzle 68 is not disposed and the diameter of the inner circumferential surface of the second nozzle 70.

As illustrated in FIG. 5, the second sound absorbing member 104 is disposed in the rear housing 58. The second sound absorbing member 104 has a tubular shape in which the diameter of the inner circumferential surface gradually decreases from rear to front. As illustrated in FIG. 10, the second sound absorbing member 104 is divided into four, and is disposed along the inner circumferential surface of the rear housing 58. The diameter of the inner circumferential surface of the second sound absorbing member 104 near the front end of the rear housing 58 is substantially equal to the diameter of the inner circumferential surface of the outer tubular member 74.

As illustrated in FIG. 5, in the present embodiment, a length L1 of the first sound absorbing member 102 along the air flow direction (i.e., direction from rear to front) is longer than a length L2 of the second sound absorbing member 104 along the air flow direction. The length L1 of the first sound absorbing member 102 along the air flow direction is for example 150mm or more and 250mm or less. The length L2 of the second sound absorbing member 104 along the air flow direction is for example 80mm or more and 160mm or less.

In the present embodiment, when viewed in the cross section of the blower 2 that is perpendicular to the air flow direction, a thickness T1 of the first sound absorbing member 102 is thicker than a thickness T2 of the second sound absorbing member 104 (see FIGS. 9, 10). Here, this means that the thickness T1 of the first sound absorbing member 102 in any cross section perpendicular to the air flow direction is always thicker than the thickness T2 of the second sound absorbing member 104 in that cross section perpendicular to the air flow direction. When viewed in the cross section of the blower 2 that is perpendicular to the air flow direction, the thickness T1 of the first sound absorbing member 102 is for example 13mm or more and 30mm or less. Here, this means that the thickness T1 of the first sound absorbing member 102 in, at least, one cross section perpendicular to the air flow direction is for example 13mm or more and 30mm or less. Also, when viewed in the cross section of the blower 2 that is perpendicular to the air flow direction, the thickness T2 of the second sound absorbing member 104 is for example 10mm or more and 30mm or less. Also, in this case also, it is meant that the thickness T2 of the second sound absorbing member 104 in, at least, one cross section perpendicular to the air flow direction is for example 10mm or more and 30mm or less.

Next, the flow passage areas of the respective parts in the blower 2 will be described. Here, the flow passage area herein means an area in which the air can flow. Although details will be described below, if there is a component which inhibits passing of the air in the flow passage in which the air flows, the flow passage area needs to be calculated considering such component.

As illustrated in FIG. 5, in the present embodiment, the flow passage area of the motor housing 56 at the position where the axial fan 88 is disposed is smaller than the flow passage area of the first nozzle 68 at a downstream end 102a of the first sound absorbing member 102 in the air flow direction. The flow passage area of the motor housing 56 at the position at which the axial fan 88 is disposed can be calculated by subtracting an average cross-sectional area of the plurality of blades 100 from the area of a donut-shaped part defined by an inner diameter D1 of the outer tubular member 74 and an outer diameter D2 of the hub 98 of the axial fan 88 as illustrated in FIG. 8. As illustrated in FIG. 11, the average cross-sectional area of the plurality of blades 100 can be calculated by dividing a total value of the volumes of the plurality of blades 100 by a length L3 of the plurality of blades 100 in its axial direction (i.e., front-rear direction). The length L3 of the plurality of blades 100 in the axial direction can be measured as a length of the plurality of blades 100 from its front end 100a to its rear end 100b. As illustrated in FIG. 5, the flow passage area of the first nozzle 68 at the downstream end 102a of the first sound absorbing member 102 in the air flow direction can be calculated by using, for example, the inner diameter D3 of the first sound absorbing member 102 at the downstream end 102a of the first sound absorbing member 102.

As illustrated in FIG. 9, in a region in which the first sound absorbing member 102 is disposed, when viewed in the cross section of the blower 2 that is perpendicular to the air flow direction, the area of the first sound absorbing member 102 is 60% or more and 200% or less of the flow passage area of the first nozzle 68 (i.e., area of the portion on the inner side relative to the first sound absorbing member 102). Here, in the present embodiment, in the region on which the first sound absorbing member 102 is disposed, the area of the first sound absorbing member 102 in any cross section perpendicular to the air flow direction is always 60% or more and 200% or less of the flow passage area of the first nozzle 68 in that cross section. When viewed in the cross section of the blower 2 that is perpendicular to the air flow direction, the area of the first sound absorbing member 102 can be calculated as, for example, the area of a donut-shaped part defined by an outer diameter D4 of the first sound absorbing member 102 and an inner diameter D5 of the first sound absorbing member 102. Here, in the present embodiment, the outer diameter D4 of the first sound absorbing member 102 and the inner diameter D5 of the first sound absorbing member 102 are always constant in any cross section perpendicular to the air flow direction. Also, D5 coincides D3 at the downstream end 102a of the first sound absorbing member 102.

FIG. 12 shows measurement results of a sound power level when the thickness T1 of the first sound absorbing member 102 is changed in the blower 2 of the present embodiment. When the thickness T1 of the first sound absorbing member 102 is 10mm, 15mm, 17mm, the area of the first sound absorbing member 102 is respectively 44%, 69%, 96% of the flow passage area of the first nozzle 68. In these measurements, wind force (product of wind pressure and flow passage area) was 20N, the diameter of the inner circumferential surface of the first sound absorbing member 102 disposed at the sound absorbing member mount part 68a and the diameter of the inner circumferential surface of the discharge port 70a were 100mm, and the length L1 of the first sound absorbing member 102 was 170mm. It was observed that, as viewed in the cross section of the blower 2 that is perpendicular to the air flow direction, when the area of the first sound absorbing member 102 is 60% or more of the flow passage area of the first nozzle 68, that is, when the thickness T1 of the first sound absorbing member 102 is substantially 13mm or more, the sound power level significantly dropped, and that, as viewed in the cross section of the blower 2 that is perpendicular to the air flow direction, when the area of the first sound absorbing member 102 is 80% or more of the flow passage area of the first nozzle 68, that is, when the thickness T1 of the first sound absorbing member 102 is substantially 17mm or more, the sound power level further significantly dropped.

FIG. 13 shows measurement results of the sound power level when the length L1 of the first sound absorbing member 102 is changed in the blower 2 of the present embodiment. In these measurements, wind force (product of wind pressure and flow passage area) was 20N, the diameter of the inner circumferential surface of the first sound absorbing member 102 disposed at the sound absorbing member mount part 68a and the diameter of the inner circumferential surface of the discharge port 70a were 100mm, and the thickness T1 of the first sound absorbing member 102 was 20mm. It was confirmed that the sound power level remarkably dropped along with the increase of the length L1 of the first sound absorbing member 102 within the range of the length L1 of the first sound absorbing member 102 from 70mm to 120mm. The sound power level can be considered as being in an inverse proportionate relationship with the length L1 of the first sound absorbing member 102 within the above-mentioned range. It was also confirmed that the sound power level significantly dropped along with the increase of the length L1 of the first sound absorbing member 102 within the range of the length L1 of the first sound absorbing member 102 from 120mm to 150mm and that the sound power level mildly dropped when the length L1 of the first sound absorbing member 102 is 150mm or more.

Second Embodiment

In the second embodiment, only points differing from the first embodiment will be described, and the points that are the same as the first embodiment will be given the same reference numerals, by which descriptions thereof may be omitted. As illustrated in FIGS. 14, 15, in a blower 2A of the present embodiment, the blower tube 154 comprises the motor housing 56, the rear housing 58, and a front housing 166. The blower tube 154 has an air passage 155 therein. The air passage 155 comprises the upstream air passage 64, the intermediate air passage 82, and a downstream air passage 172.

The front housing 166 has a tubular shape extending in the front-rear direction. The front housing 166 has the downstream air passage 172 therein. As illustrated in FIG. 15, an opening 166c is defined at the upper end of the front housing 166, and the opening 166c is disposed below the control part 18. The air passing through the opening 166c cools the control part 18. As illustrated in FIGS. 14, 15, a nozzle 160 comprises a first nozzle 168. A discharge port 168a is defined at the distal end of the first nozzle 168. The first nozzle 168 is detachably attached to the front housing 166. A plurality of protrusions 166b is disposed at the distal end of the front housing 166, and front housing mount grooves 168b are defined at the rear end of the first nozzle 168. The first nozzle 168 is configured to be detachably attached to the front housing 166 by inserting and removing the protrusions 166b of the front housing 166 into and from the front housing mount grooves 168b of the first nozzle 168.

As illustrated in FIG. 14, the first nozzle 168 has a tubular shape extending in the front-rear direction. The discharge port 168a is defined at the distal end of the first nozzle 168. The diameter of the inner circumferential surface of the first nozzle 168 is constant from its rear end to a first shrinking part 168c, shrinks at the first shrinking part 168c, further shrinks at a second shrinking part 168d, and is constant from the second shrinking part 168d to its distal end.

A sound absorbing member mount part 166a with the diameter of the inner circumferential surface being greater than those of the other parts is disposed in a portion of the front housing 166. The sound absorbing member mount part 166a of the front housing 166 has its diameter of the inner circumferential surface decreasing from rear to front. At a position where the sound absorbing member mount part 166a of the front housing 166 is not provided, the diameter of the inner circumferential surface is constant. A first sound absorbing member 202 has a tubular shape extending in the front-rear direction. The first sound absorbing member 202 is disposed along the inner circumferential surface at the sound absorbing member mount part 166a of the front housing 166. The first sound absorbing member 202 disposed at the sound absorbing member mount part 166a has the diameters of its outer circumferential surface and its inner circumferential surface decreasing from rear to front, but its thickness is constant. The diameter of the inner circumferential surface of the first sound absorbing member 202 disposed at the sound absorbing member mount part 166a is substantially equal to each of the diameter of the inner circumferential surface of the motor housing 56 and the diameter of the inner circumferential surface of the position where the sound absorbing member mount part 166a of the front housing 166 is not provided. As illustrated in FIG. 14, a length L4 of the first sound absorbing member 202 along the air flow direction (i.e., direction from rear to front) is longer than the length L2 of the second sound absorbing member 104 along the air flow direction. The length L4 of the first sound absorbing member 202 along the air flow direction is for example 150mm or more and 250mm or less. The volume of the first sound absorbing member 202 is 8.0×10⁵ mm³ or more and 3.6×10⁶ mm³ or less. The first sound absorbing member 202 is a sponge member, and the sponge member of the present embodiment is constituted of urethane.

In the front housing 166, a guard member 167 is disposed between the sound absorbing member mount part 166a and the plurality of protrusions 166b. That is, the sound absorbing member mount part 166a and the first sound absorbing member 202 mounted thereon are disposed rearward of the guard member 167 as well as each of the plurality of protrusions 166b. The guard member 167 comprises a plurality of through holes 167a. Due to this, the air passes through the downstream air passage 72 of the front housing 166, and is discharged out of the discharge port 168a of the first nozzle 168, and meanwhile if a user puts his/her hand into the discharge port 168a of the first nozzle 168, the user’s hand can be avoided from reaching a position on the rear side relative to the guard member 167.

As illustrated in FIG. 15, the front end of the first sound absorbing member 202 is disposed frontward of the front end of the control part 18. The rear end of the first sound absorbing member 202 is disposed rearward of the rear end of the control part 18. The first sound absorbing member 202 is disposed frontward of each of the third housing 28 and the fourth housing 30, and is disposed frontward of the first switch 42.

Next, the flow passage areas of the respective parts in the blower 2A will be described. As illustrated in FIGS. 14, 15, when viewed in the cross section of the blower 2A that is perpendicular to the air flow direction, in the region on which the first sound absorbing member 202 is disposed, the area of the first sound absorbing member 202 is 60% or more and 200% or less of the flow passage area of the front housing 166 (i.e., area of the portion on the inner side relative to the first sound absorbing member 202). Here, in the present embodiment, in the region on which the first sound absorbing member 202 is disposed, the area of the first sound absorbing member 202 in any cross section perpendicular to the air flow direction is always 60% or more and 200% or less of the flow passage area of the front housing 166 in such cross section. When viewed in the cross section of the blower 2A that is perpendicular to the air flow direction, the area of the first sound absorbing member 202 can be calculated as the area of a donut-shaped part defined by the outer diameter of the first sound absorbing member 202 and the inner diameter of the first sound absorbing member 202 (see FIG. 5).

The flow passage area of the front housing 166 decreases from a downstream end 84b of the cone 84 in the air flow direction to a downstream end 202b of the first sound absorbing member 202 in the air flow direction. An upstream-side end 202a of the first sound absorbing member 202 in the air flow direction is located upstream of the downstream end 84b of the cone 84 in the air flow direction.

Third Embodiment

In the third embodiment, only points differing from the second embodiment will be described, and the points that are the same as the second embodiment will be given the same reference numerals, by which descriptions thereof may be omitted. As illustrated in FIGS. 16, 17, in a blower 2B of the present embodiment, the blower tube 254 comprises the motor housing 56, the rear housing 58, and a front housing 266. The blower tube 254 has an air passage 255 therein. The air passage 255 comprises the upstream air passage 64, the intermediate air passage 82, and a downstream air passage 272.

The front housing 266 has a tubular shape extending in the front-rear direction. The front housing 266 has the downstream air passage 272 therein. As illustrated in FIG. 17, the opening 166c is defined at the upper end of the front housing 266, and the opening 166c is disposed below the control part 18. The air passing through the opening 166c cools the control part 18.

The rear end of the front housing 266 comprises a sound absorbing member mount part 266a with the diameter of the inner circumferential surface being greater than those of the other parts. A shrinking part 266b in which the diameter of the inner circumferential surface shrinks is disposed downstream of the sound absorbing member mount part 266a of the front housing 266. The diameter of the inner circumferential surface of the front housing 266 is constant at the sound absorbing member mount part 266a, shrinks at the shrinking part 266b, and is constant at the distal side relative to the shrinking part 266b. The first sound absorbing member 302 has a tubular shape extending in the front-rear direction. The first sound absorbing member 302 is disposed along the inner circumferential surface at the sound absorbing member mount part 266a of the front housing 266. The diameter of the inner circumferential surface of a first sound absorbing member 302 disposed at the sound absorbing member mount part 266a is substantially equal to both of the diameter of the inner circumferential surface at the rear end of the shrinking part 266b of the front housing 266 and the diameter of the inner circumferential surface of the motor housing 56. In the first sound absorbing member 302 disposed at the sound absorbing member mount part 266a, the diameters of its outer circumferential surface and its inner circumferential surface are constant, and its thickness is also constant. As illustrated in FIG. 16, a length L5 of the first sound absorbing member 302 along the air flow direction (i.e. direction from rear to front) is longer than the length L2 of the second sound absorbing member 104 along the air flow direction. The length L5 of the first sound absorbing member 302 along the air flow direction is for example 150mm or more and 250mm or less. The volume of the first sound absorbing member 302 is 8.0×10⁵ mm³ or more and 3.6×10⁶ mm³ or less. The first sound absorbing member 302 is a sponge member, and the sponge member in the present embodiment is constituted of urethane.

The guard member 167 is disposed in the front housing 266. The sound absorbing member mount part 266a and the first sound absorbing member 302 mounted thereon are disposed rearward of each of the shrinking part 266b, the guard member 167, and the plurality of protrusions 166b.

As illustrated in FIG. 17, the front end of the first sound absorbing member 302 is disposed frontward of the front end of the control part 18. The rear end of the first sound absorbing member 302 is located rearward of the rear end of the control part 18. The first sound absorbing member 302 is located frontward of each of the third housing 28 and the fourth housing 30, and is located frontward of the first switch 42.

Next, the flow passage areas of the respective parts in a blower 2B will be described. As illustrated in FIGS. 16, 17, when viewed in the cross section of the blower 2B that is perpendicular to the air flow direction, in the region on which the first sound absorbing member 302 is disposed, the area of the first sound absorbing member 302 is 60% or more and 200% or less of the flow passage area of the front housing 166 (i.e., area of the portion on the inner side relative to the first sound absorbing member 302). Here, in the present embodiment, in the region on which the first sound absorbing member 302 is disposed, the area of the first sound absorbing member 302 in any cross section perpendicular to the air flow direction is always 60% or more and 200% or less of the flow passage area of the front housing 166 in such cross section. When viewed in the cross section of the blower 2B that is perpendicular to the air flow direction, the area of the first sound absorbing member 302 can be calculated as, for example, the area of a donut-shaped part defined by the outer diameter of the first sound absorbing member 302 and the inner diameter of the first sound absorbing member 302 (see FIG. 5).

Fourth Embodiment

In the fourth embodiment, only the points differing from the first embodiment will be described, and the points that are the same as the first embodiment will be given the same reference numerals, by which descriptions thereof may be omitted. As illustrated in FIGS. 18, 19, the blower 2C of the present embodiment comprises the first sound absorbing member 102, the second sound absorbing member 404, and the third sound absorbing member 406. Each of the second sound absorbing member 404 and the third sound absorbing member 406 is a sponge member. The sponge member herein mentioned means broadly porous flexible materials. The sponge member in the present embodiment is constituted of urethane.

The second sound absorbing member 404 is disposed in the rear housing 58. The second sound absorbing member 404 has a tubular shape in which the diameter of its inner circumferential surface gradually decreases from rear to front. As illustrated in FIG. 19, the second sound absorbing member 404 is divided into four, and is disposed along the inner circumferential surface of the rear housing 58. As illustrated in FIG. 18, the diameter of the inner circumferential surface of the second sound absorbing member 404 near the front end of the rear housing 58 is substantially equal to the diameter of the inner circumferential surface of the outer tubular member 74.

A third sound absorbing member 406 is disposed in a cover member 362. The central portion of the cover member 362 comprises a base part 362a and a tubular sound absorbing member mount part 362b protruding frontward from the base part 362a. The base part 362a and the sound absorbing member mount part 362b are configured integrally with each other. The diameter of the outer circumferential surface of the sound absorbing member mount part 362b is smaller than the diameter of the outer circumferential surface of the base part 362a. The third sound absorbing member 406 has a tubular shape extending in the front-rear direction. The third sound absorbing member 406 is disposed along the outer circumferential surface at the sound absorbing member mount part 362b of the cover member 362. A flow‑straightening member 363 is attached to the front end of the sound absorbing member mount part 362b. The flow‑straightening member 363 has a tubular shape in which the diameter of the outer circumferential surface increases from rear to front. The diameter of the outer circumferential surface of the third sound absorbing member 406 disposed at the sound absorbing member mount part 362b is smaller than the diameter of the base part 362a and is substantially equal to the diameter of the outer circumferential surface of the rear end of the flow‑straightening member 363. The diameter of the outer circumferential surface of the front end of the flow‑straightening member 363 is substantially equal to the diameter of the outer side surface 98a at the flow‑straightening member 363 of the hub 98. The flow‑straightening member 363 is located rearward of the axial fan 88.

In the present embodiment, a length L7 of the third sound absorbing member 406 along the air flow direction (i.e., direction from rear to front) is shorter than both the length L1 of the first sound absorbing member 102 (see FIG. 5) along the air flow direction and a length L6 of the second sound absorbing member 404 along the air flow direction. The length L6 of the second sound absorbing member 404 along the air flow direction is for example 98mm or more and 160mm or less. The length L7 of the third sound absorbing member 406 along the air flow direction is for example 50mm or more and 80mm or less.

As illustrated in FIG. 19, in the present embodiment, when viewed in the cross section of the blower 2C that is perpendicular to the air flow direction, a thickness T4 of the third sound absorbing member 406 is substantially equal to both the thickness T1 of the first sound absorbing member 102 (see FIG. 9) and a thickness T3 of the second sound absorbing member 404. When viewed in the cross section of the blower 2C that is perpendicular to the air flow direction, the thickness T3 of the second sound absorbing member 404 is for example 10mm or more and 30mm or less. Here, this means that the thickness T3 of the second sound absorbing member 404, at least, in one cross section perpendicular to the air flow direction is for example 10mm or more and 30mm or less. Also, when viewed in the cross section of the blower 2C that is perpendicular to the air flow direction, the thickness T4 of the third sound absorbing member 406 is for example 10mm or more and 30mm or less. Here, in this case also, it means that the thickness T4 of the third sound absorbing member 406, at least, in one cross section perpendicular to the air flow direction is for example 10mm or more and 30mm or less.

As illustrated in FIG. 20, the base part 362a does not comprise an intake port 62a, but an intake part 362c provided with the plurality of intake ports 62a is disposed around the base part 362a. As illustrated in FIG. 18, the diameter of the base part 362a is greater than the diameter of the outer side surface 98a of the hub 98 in the axial fan 88. The outer circumferential surface of the base part 362a is located radially inward of the distal ends of the blades 100 of the axial fan 88.

The inventors of the present application confirmed that in the blower 2C of the present embodiment, the average of the peak value of the sound power level of NZ sound measured at two rear positions of the blower 2C significantly dropped as compared to a configuration where the center portion of the upstream air passage 64 does not comprise the third sound absorbing member 406. Due to this, it was confirmed that the NZ sound leaking outside through the blower tube 54 upstream of the axial fan 88 can be reduced by providing the third sound absorbing member 406 at the center portion of the upstream air passage 64. Also, the inventors also confirmed that, in the blower 2C of the present embodiment, the average of the peak value of the sound power level of the NZ sound measured at the two rear positions of the blower 2C significantly dropped as compared to a configuration where the diameter of the base part 362a is made equal to the diameter of the outer circumferential surface of the third sound absorbing member 406. Due to this, it was confirmed that, by making the diameter of the base part 362a located at the center of the cover member 362 relatively great (in the present embodiment, making it greater than the diameter of the outer side surface 98a of the hub 98 in the axial fan 88), the NZ sound leaking outside through the blower tube 54 upstream of the axial fan 88 can be reduced. This can be attributed to the fact that at least a portion of the NZ sound traveling outside through the blower tube 54 upstream of the axial fan 88 is reflected back by the base part 362a at the center of the cover member 362, as a result of which the NZ sound leaking outside through the blower tube 54 upstream of the axial fan 88 was reduced. The frequency of the NZ sound can be determined by the number of the plurality of blades 100 and the rotation speed of the axial fan 88.

Modifications

In the first to fourth embodiments, when viewed in the cross section of the blower that is perpendicular to the air flow direction, in at least a portion of the region on which the first sound absorbing member 102, 202, 302 is disposed, the area of the first sound absorbing member 102, 202, 302 may be 60% or more and 200% or less of the flow passage area of the blower tube 54, 154, 254 and/or the flow passage area of the nozzle 60, 160, and in the other portion of the region on which the first sound absorbing member 102, 202, 302 is disposed, when viewed in the cross section of the blower that is perpendicular to the air flow direction, the area of the first sound absorbing member 102, 202, 302 may not be 60% or more and 200% or less of the flow passage area of the blower tube 54, 154, 254 and/or the flow passage area of the nozzle 60, 160. Alternatively, the first sound absorbing member 102, 202, 302 in the first to fourth embodiments may be divided in two or more and disposed at discrete positions in the air flow direction. Alternatively, the first sound absorbing member 102, 202, 302 in the first to third embodiments may be divided into two or more and be disposed at discrete positions in the circumferential direction. Alternatively, in the second and third embodiments, the first sound absorbing member 202, 302 of which thickness is made half may disposed along the inner circumferential surface of the blower tube 154, 254 and also the first sound absorbing member 202, 302 of which thickness is made half may be disposed on the outer circumferential surface of the inner tubular member 78 and/or the outer circumferential surface of the cone 84.

In the first to fourth embodiments, as long as the first sound absorbing member 102, 202, 302 is located downstream of the axial fan 88, the first sound absorbing member 102, 202, 302 may be disposed across both the blower tube 54, 154, 254 and the nozzle 60, 160. In this case, the flow passage area of the blower tube 54, 154, 254 and/or the flow passage area of the nozzle 60, 160 may be suitably calculated depending on the position at which the first sound absorbing member 102, 202, 302 is disposed.

In the first to fourth embodiments, when viewed in the cross section of the blower that is perpendicular to the air flow direction, the length measured along the air flow direction of the portion in which the area of first sound absorbing member 102, 202, 302 is 60% or more and 200% or less of the flow passage area of the blower tube 54, 154, 254 and/or the nozzle 60, 160 may be less than 150 mm or longer than 250 mm.

In the first to fourth embodiments, the volume of the first sound absorbing member 102, 202, 302 may be smaller than 8.0×10⁵ mm³and larger than 3.6×10⁶ mm³.

In the second embodiment, the entirety of the first sound absorbing member 202 may be disposed at the position where the flow passage area of the blower tube 154 decreases.

The blower 2, 2A, 2B, 2C of the first to fourth embodiments may comprise a centrifugal fan instead of the axial fan 88.

In the blower 2, 2A, 2B of the first to third embodiments, the length L1, L4, L5 of the first sound absorbing member 102, 202, 302 along the air flow direction may be equal to the length L2 of the second sound absorbing member 104 along the air flow direction, or may be shorter than the length L2 of the second sound absorbing member 104 along the air flow direction.

The blower 2, 2A, 2B, 2C of the first to fourth embodiments may not comprise the second sound absorbing member 104, 404.

In the blower 2, 2A, 2B, 2C of the first to fourth embodiments, the second sound absorbing member 104, 404 may not be divided into four.

In the first embodiment, the first nozzle 68 may be integrated with the front housing 66. That is, only the second nozzle 70 may be detachably attached.

In the blower 2C of the fourth embodiment, the third sound absorbing member 406 may be disposed at the hub 98 of the axial fan 88, instead of being in the cover member 362. That is, the sound absorbing member mount part 362b at which the third sound absorbing member 406 is disposed may be disposed at the hub 98 of the axial fan 88, instead of being at the cover member 362.

In the blower 2C of the fourth embodiment, the diameter of the outer circumferential surface of the flow‑straightening member 363 may be constant. In this case, the diameter of the outer circumferential surface of the third sound absorbing member 406 disposed at the sound absorbing member mount part 362b may be substantially equal to the diameter of the outer circumferential surface of the flow‑straightening member 363 and the diameter of the outer side surface 98a of the hub 98.

In the blower 2C of the fourth embodiment, the flow‑straightening member 363 may not be disposed. In this case, the diameter of the outer circumferential surface of the third sound absorbing member 406 disposed at the sound absorbing member mount part 362b may be substantially equal to the diameter of the outer side surface 98a of the hub 98.

In the blower 2C of the fourth embodiment, the plurality of intake ports 62a may be defined on the base part 362a, and a portion of or all of the plurality of intake ports 62a defined on the base part 362a may be covered by separate intake port cover member(s).

In the blower 2C of the fourth embodiment, the length L7 of the third sound absorbing member 406 along the air flow direction may be equal to the length L1 of the first sound absorbing member 102 along the air flow direction, or may be longer than the length L1 of the first sound absorbing member 102 along the air flow direction.

In the blower 2C of the fourth embodiment, the length L7 of the third sound absorbing member 406 along the air flow direction may be equal to the length L6 of the second sound absorbing member 404 along the air flow direction, or alternatively, may be longer than the length L6 of the second sound absorbing member 404 along the air flow direction.

In the blower 2C of the fourth embodiment, when viewed in the cross section of the blower 2C that is perpendicular to the air flow direction, the thickness T4 of the third sound absorbing member 406 may be thinner than the thickness T1 of the first sound absorbing member 102, or alternatively, may be thicker than the thickness T1 of the first sound absorbing member 102.

In the blower 2C of the fourth embodiment, when viewed in the cross section of the blower 2C that is perpendicular to the air flow direction, the thickness T4 of the third sound absorbing member 406 may be thinner than the thickness T3 of the second sound absorbing member 404, or alternatively, thicker than the thickness T3 of the second sound absorbing member 404.

In the blower 2C of the fourth embodiment, the third sound absorbing member 406 may not be provided. In this case, the diameter of the outer circumferential surface of the base part 362a disposed at the center portion of the cover member 362 is preferably relatively great, and for example, is preferably greater than the diameter of the outer side surface 98a of the hub 98 in the axial fan 88.

Features of Embodiments

In one or more of the above-mentioned embodiments, the blower 2, 2A, 2B, 2C comprises: the electric motor 86; the axial fan 88 (example of a fan) configured to be driven by the electric motor 86; the blower tube 54, 154, 254 having the air passage 55, 155, 255 in which air flows by rotation of the axial fan 88; the nozzle 60, 160 disposed downstream relative to the blower tube 54, 154, 254 in the air flow direction and having the discharge port 70a, 168a configured to discharge the air; and the first sound absorbing member 102, 202, 302 disposed on the blower tube 154, 254 and/or the nozzle 60 at a position downstream relative to the axial fan 88 in the air flow direction. When viewed in a cross section of the blower 2, 2A, 2B, 2C that is perpendicular to the air flow direction, in at least a portion of a region on which the first sound absorbing member 102, 202, 302 is disposed, the area of the first sound absorbing member 102, 202, 302 is 60% or more and 200% or less of the flow passage area of the blower tube 54, 154, 254 and/or the nozzle 60, 160.

In the above configuration, the first sound absorbing member 102, 202, 302 is disposed on the blower tube 54, 154, 254 and/or the nozzle 60, 160 at a position downstream relative to the axial fan 88 in the air flow direction. When viewed in the cross section of the blower that is perpendicular to the air flow direction, in the at least portion of the region on which the first sound absorbing member 102, 202, 302 is disposed, the area of the first sound absorbing member 102, 202, 302 is 60% or more and 200% or less of the flow passage area of the blower tube 54, 154, 254 and/or the nozzle 60, 160. Due to this, noise leaking outside from the axial fan 88 outside through the nozzle 60, 160 can be suppressed.

In one or more of the above-mentioned embodiments, the length along the air flow direction of the at least portion of the region on which the first sound absorbing member 102, 202, 302 is disposed (i.e., the portion where, when viewed in the cross section of the blower that is perpendicular to the air flow direction, the area of the first sound absorbing member 102, 202, 302 is 60% or more and 200% or less of the flow passage area of the blower tube 54, 154, 254 and/or the nozzle 60, 160) is 150 mm or more and 250 mm or less.

In the above configuration, the first sound absorbing member 102, 202, 302 can effectively absorb noise generated from the axial fan 88, and also the first sound absorbing member 102, 202, 302 can be downsized.

In one or more of the above-mentioned embodiments, the volume of the first sound absorbing member 102, 202, 302 is 8×10⁵ mm³or more and 3.6×10⁶ mm³ or less.

In the above configuration, the first sound absorbing member 102 can effectively absorb noise generated from the axial fan 88, and also the first sound absorbing member 102 can be downsized.

In one or more of the above-mentioned embodiments, at least a portion of the first sound absorbing member 202 is disposed at the position where the flow passage area of the blower tube 154 decreases.

In many blowers 2, 2A, 2B, 2C, position(s) where the flow passage area decreases exist in the blower tube 154 and/or the nozzle 160 in order to accelerate the flow speed of the air. According to the above configuration, by disposing the first sound absorbing member 202 at such position with decreased flow passage area, the blower 2A can be downsized as compared to when the first sound absorbing member 202 is disposed elsewhere.

In one or more of the above-mentioned embodiments, the axial fan 88 is disposed inside the blower tube 54, 154, 254.

In the above configuration, noise generated from the axial fan 88 can be effectively suppressed from leaking outside from within the blower tube 54, 154, 254 inside through the nozzle 60, 160.

In one or more of the above-mentioned embodiments, the flow passage area of the blower tube 54, 154, 254 at the position at which the axial fan 88 is disposed is smaller than the flow passage area of the blower tube 54, 154, 254 and/or the nozzle 60, 160 at the downstream end 102a, 202b of the first sound absorbing member 102, 202, 302 in the air flow direction.

If the flow passage area of the blower tube 54, 154, 254 at the position at which the axial fan 88 is disposed is greater than the flow passage area of the blower tube 54, 154, 254 and/or the nozzle 60, 160 at the downstream end 102a, 202b of the first sound absorbing member 102, 202, 302 in the air flow direction, it is difficult for air to be discharged from the discharge port 70a, 168a, and thus the axial fan 88 needs to feed the air at a relatively high pressure. In this case, because pressure change near the axial fan 88 increases, noise leaking outside from the axial fan 88 through the nozzle 60, 160 can possibly be increased. In the above configuration, the pressure when the axial fan 88 feeds the air can be made smaller, and thus pressure change of the air near the axial fan 88 can be made smaller. Due to this, noise leaking outside from the axial fan 88 through the nozzle 60, 160 can be suppressed.

In one or more of the above-mentioned embodiments, the axial fan 88 comprises the hub 98 and the plurality of blades 100 disposed on the outer side surface 98a of the hub 98. In this case, although this is an example, the product of the number of the plurality of blades 100 and the rated rotational speed of the axial fan 88 is 2.6×10⁵ or more and 1.2×10⁶ or less.

The frequency of sound generated by rotation of the axial fan 88 varies depending on the product of the number of the number of the plurality of blades 100 and the rated rotational speed of the axial fan 88. In the above configuration, the frequency of the sound generated by rotation of the axial fan 88 falls outside the most-disturbing frequency range for the operator. Due to this, even when the noise leaks outside the blower 2, 2A, 2B, 2C, discomfort the operator feels can be reduced.

In one or more of the above-mentioned embodiments, the first sound absorbing member 102, 202, 302 includes a sponge member. The sponge herein mentioned broadly means porous flexible materials.

In the above configuration, the sound energy of noise generated from the axial fan 88 translates into thermal energy due to the sponge member when the noise passes through the first sound absorbing member 102, 202, 302. Due to this, noise leaking outside from the axial fan 88 through the nozzle 60 can be suppressed.

Also, the above sponge member is constituted of urethane.

According to the above configuration, noise leaking outside from the axial fan 88 through the nozzle 60, 160 can be effectively suppressed.

In one or more of the above-mentioned embodiments, the first sound absorbing member 102 is disposed on the nozzle 60.

In the above configuration, it is easier to manufacture the blower 2 than when the first sound absorbing member 102 is disposed on the blower tube 54.

In one or more of the above-mentioned embodiments, the blower 2, 2A, 2B, 2C further comprises the second sound absorbing member 104, 404 disposed on the blower tube 54, 154, 254 at a position upstream relative to the axial fan 88 in the air flow direction.

In the above configuration, the noise leaking outside from the axial fan 88 through the blower tube 54, 154, 254 at the position upstream of the axial fan 88 can be suppressed.

In one or more of the above-mentioned embodiments, the length L1, L4, L5 of the first sound absorbing member 102, 202, 302 along the air flow direction is greater than the length L2 of the second sound absorbing member 104 along the air flow direction.

In the above configuration, the noise can be effectively absorbed by the first sound absorbing member 102, 202, 302, and the noise leaking outside from the axial fan 88 through the nozzle 60, 160 can be suppressed.

In one or more of the above-mentioned embodiments, the blower 2, 2A, 2B, 2C further comprises the second sound absorbing member 104, 404 disposed on a circumference of the upstream air passage 64. According to such configuration, the NZ sound leaking outside from the axial fan 88 through the blower tube 54, 154, 254 at the position upstream of the axial fan 88 can be suppressed.

In one or more of the above-mentioned embodiments, the blower 2C further comprises the third sound absorbing member 406 disposed at the central portion of the upstream air passage 64. According to such configuration, the NZ sound leaking outside from the axial fan 88 through the blower tube 54 at the position upstream of the axial fan 88 can be suppressed.

In one or more of the above-mentioned embodiments, the length L7 of the third sound absorbing member 406 along the air flow direction is 50mm or more and 80mm or less. According to such configuration, the NZ sound leaking outside from the axial fan 88 through the blower tube 54 at the position upstream of the axial fan 88 can be effectively suppressed, while the third sound absorbing member 406 can be downsized.

In one or more of the above-mentioned embodiments, when viewed in the cross section of the blower that is perpendicular to the air flow direction, the thickness T4 of the third sound absorbing member 406 is 10mm or more and 30mm or less. According to such configuration, the NZ sound leaking outside from the axial fan 88 through the blower tube 54 upstream of the axial fan 88 can be effectively suppressed, while the third sound absorbing member 406 can be downsized.

In one or more of the above-mentioned embodiments, the third sound absorbing member 406 is disposed on the cover member 362. In the configuration where the third sound absorbing member 406 is disposed at the hub 98 of the axial fan 88, the third sound absorbing member 406 rotates with the axial fan 88. Due to this, according to the above configuration, as compared to a configuration where the third sound absorbing member 406 is disposed at the hub 98 of the axial fan 88, the weight of the part which rotates with the axial fan 88 can be made smaller, by which vibration due to the rotation of the axial fan 88 can be reduced.

In one or more of the above-mentioned embodiments, the diameter of the outer circumferential surface of the third sound absorbing member 406 is equal to or less than the diameter of the outer side surface 98a of the hub 98 in the axial fan 88. According to such configuration, the flow of air flowing from the plurality of intake ports 62a of the cover member 362 into the upstream air passage 64 of the rear housing 58 can be suppressed from being inhibited when the rotation of the axial fan 88 has caused negative pressure on the rear side of the axial fan 88.

In one or more of the above-mentioned embodiments, the outer circumferential surface of the front end of the flow‑straightening member 363 and/or the diameter of the outer circumferential surface of the front end of the third sound absorbing member 406 are substantially equal to the diameter of the outer side surface 98a of the hub 98. According to such configuration, the air having flowed from the intake ports 62a of the cover member 362 into the upstream air passage 64 can smoothly flow from the front end of the flow‑straightening member 363 and/or the front end of the third sound absorbing member 406 toward the hub 98.

In one or more of the above-mentioned embodiments, the plurality of intake ports 62a extends through the cover member 62 in the axial direction of the rotation axis of the axial fan 88. According to such configuration, as compared to the configuration where the plurality of intake ports 62a does not extend through the cover member 62 in the axial direction of the rotation axis of the axial fan 88, the air having flowed from the intake ports 62a of the cover member 362 into the upstream air passage 64 can flow more smoothly toward the axial fan 88. Also, pressure loss in the blower 2, 2A, 2B, 2C can be reduced.

In one or more of the above-mentioned embodiments, the base part 362a or an intake port cover member through which air cannot pass is disposed at the central portion of the cover member 62. The diameter of the outer circumferential surface of the base part 362a or the intake port cover member is greater than the diameter of the outer side surface 98a of the hub 98 in the axial fan 88. Also, the outer circumferential surface of the base part 362a or the outer circumferential surface of the intake port cover member is positioned radially inward of the distal ends of the blades 100 of the axial fan 88. According to such configuration, the NZ sound leaking outside from the axial fan 88 through the blower tube 54 at the position upstream of the axial fan 88 can be effectively suppressed.

Claims

1. A blower comprising:

an electric motor;

a fan configured to be driven by the electric motor;

a blower tube having an air passage in which air flows by rotation of the fan;

a nozzle disposed downstream relative to the blower tube in an air flow direction and having a discharge port configured to discharge the air; and

a first sound absorbing member disposed on the blower tube and/or the nozzle at a position downstream relative to the fan in the air flow direction,

wherein when viewed in a cross section of the blower that is perpendicular to the air flow direction, in at least a portion of a region on which the first sound absorbing member is disposed, an area of the first sound absorbing member is 60% or more and 200% or less of a flow passage area of the blower tube and/or the nozzle.

2. The blower according to claim 1, wherein a length along the air flow direction of the at least portion of the region on which the first sound absorbing member is disposed is 150 mm or more and 250 mm or less.

3. The blower according to claim 1, wherein a volume of the first sound absorbing member is 8.0×105 mm3 or more and 3.6×106 mm3 or less.

4. The blower according to claim 1, wherein at least a portion of the first sound absorbing member is disposed at a position where a flow passage area of the blower tube and/or the nozzle decreases.

5. The blower according to claim 1, wherein the fan is an axial fan disposed inside the blower tube.

6. The blower according to claim 5, wherein a flow passage area of the blower tube at a position at which the axial fan is disposed is smaller than a flow passage area of the blower tube and/or the nozzle at a downstream end of the first sound absorbing member in the air flow direction.

7. The blower according to claim 5, wherein the axial fan comprises a hub and a plurality of blades disposed on an outer side surface of the hub, and a product of a number of the plurality of blades and a rated rotational speed of the axial fan is 2.6×105 or more and 1.2×106or less.

8. The blower according to claim 1, wherein the first sound absorbing member includes a sponge member.

9. The blower according to claim 8, wherein the sponge member is constituted of urethane.

10. The blower according to claim 1, wherein the first sound absorbing member is disposed on the nozzle.

11. The blower according to claim 1, further comprising a second sound absorbing member disposed on the blower tube at a position upstream relative to the fan in the air flow direction.

12. The blower according to claim 11, wherein a length of the first sound absorbing member along the air flow direction is greater than a length of the second sound absorbing member along the air flow direction.

13. The blower according to claim 2, wherein a volume of the first sound absorbing member is 8.0×105 mm3 or more and 3.6×106 mm3 or less, at least a portion of the first sound absorbing member is disposed at a position where a flow passage area of the blower tube and/or the nozzle decreases, the fan is an axial fan disposed inside the blower tube, a flow passage area of the blower tube at a position at which the axial fan is disposed is smaller than a flow passage area of the blower tube and/or the nozzle at a downstream end of the first sound absorbing member in the air flow direction, the axial fan comprises a hub and a plurality of blades disposed on an outer side surface of the hub, a product of a number of the plurality of blades and a rated rotational speed of the axial fan is 2.6×105or more and 1.2×106or less, the first sound absorbing member includes a sponge member, the sponge member is constituted of urethane, the first sound absorbing member is disposed on the nozzle, the blower further comprises a second sound absorbing member disposed on the blower tube at a position upstream relative to the fan in the air flow direction, and a length along the air flow direction of the first sound absorbing member is greater than a length along the air flow direction of the second sound absorbing member.