BACKPACK-TYPE AIR BLOWING WORKING MACHINE

Abstract

Disclosed is a backpack-type air-blowing working machine in which a volute casing incorporating a centrifugal fan configured to be driven by an electric motor is assembled in an upstanding manner to a backpack frame to be carried on the back of an operator using shoulder straps during use. The backpack-type air-blowing working machine includes a rechargeable battery pack connected to the electric motor and detachably attached to the backpack frame, such that a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the rear thereof is located below a rotation axis of the centrifugal fan, and a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the side thereof is located forward of a rear end of the volute casing.

Description

TECHNICAL FIELD

The present invention relates to a backpack-type air-blowing working machine for use in cleaning small pieces such as fallen leaves or mown grass, and more particularly to a backpack-type air-blowing working machine in which a volute casing incorporating a centrifugal fan configured to be driven by an electric motor is assembled to a backpack frame.

BACKGROUND ART

U.S. Pat. No. 6,006,400 discloses a backpack blower which comprises: a volute casing mounted to a cross-sectionally L-shaped backpack frame to be carried on the back of an operator (i.e., a user or a worker); a centrifugal fan rotatably pivoted within the volute casing; an electric motor assembled to a rear side of the volute casing and operable to rotate the centrifugal fan, and a battery attached to a lower horizontal frame portion of the backpack frame. This backpack blower is configured such that the centrifugal fan in the volute casing is rotated by the electric motor operated by electric power fed from the battery, and air sucked into the volute casing according to the rotation of the centrifugal fan is blown out from a blowout port of the volute casing.

In the backpack blower, the large-size electric motor is disposed behind the volute casing, and attached to a longitudinally intermediate region of the lower horizontal frame portion of the backpack frame. Therefore, an operator carries the backpack frame of backpack blower on his/her back using shoulder straps during use, a position of the center of gravity of the backpack blower will lie relatively rearward y, so that the operator is likely to fall down rearwardly, leading to difficulty in cleaning work.

Moreover, the battery for feeding electric power to the electric motor is fixed to the lower horizontal frame portion of the backpack frame by a screw through a bracket. This means that the backpack blower is not designed supposing that the battery is frequently detached and charged. Therefore, for charging the battery, it is necessary to carry the backpack blower to a vicinity of a power supply, or to detach the bracket for each charging operation. Thus, it is necessary to take time and effort for the battery charging operation.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a backpack-type air-blowing working machine capable of eliminating the above difficulty. Specifically, according to a first aspect of the present invention, there is provided a backpack-type air-blowing working machine which comprises: a backpack frame having at least a back plate portion conformable to the back of an operator, wherein the backpack frame is configured to be carried on the back of the operator through the back plate portion using shoulder straps; a volute casing mounted to the backpack frame at a position rearward of the back plate portion, in such a manner that a center of a volute is set in a direction intersecting a planar direction of the back plate portion; a centrifugal fan rotatably supported within the volute casing; an electric motor assembled to the volute casing and operable to rotate the centrifugal fan; and a rechargeable battery pack attached to the backpack frame and operable to feed electric power to the electric motor, wherein the backpack-type air-blowing working machine is configured such that a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the rear thereof located below a rotation axis of the centrifugal fan, and a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the side thereof is located forward of a rear end of the volute casing.

In backpack-type air-blowing working machine configured as above, the position of the center of gravity of the backpack-type air-blowing working machine as viewed from the rear thereof is located below the rotation axis of the centrifugal fan, and the position of the center of gravity of the backpack-type air-blowing working machine as viewed from the side thereof is located forward of the rear end of the volute casing Thus, when an operator performs cleaning operation while carrying the backpack-type air-blowing working machine on his/her back using shoulder traps, a weight of the backpack-type air-blowing working machine is supported by the lumbar region of the operator, and therefore the backpack-type air-blowing working machine is stabilized, so that the operator becomes less likely to fall down rearwardly, thereby making it possible to more easily manipulate the air-blowing working machine to reduce fatigue of the operator.

Preferably, in the above backpack-type air-blowing working machine, the battery pack is disassemblably assembled onto a support rack portion provided to extend rearwardly and horizontally from a lower end of the back plate portion of the backpack frame and located just beneath the volute casing. This makes it possible to facilitate a charging operation for the battery pack to increase operating efficiency. Further, in implementation of the present invention, the battery pack may be composed of a plurality of rechargeable battery packs. Each of the plurality of rechargeable battery packs is connected to the electric motor, and each of the plurality of rechargeable battery packs is assembled in a manner that allows for disassembly of the respective battery pack from the electric motor. In this case, it becomes possible to enhance convenience of the backpack-type air-blowing working machine using a battery pack standardly utilized in various electric tools and electric gardening machines.

In implementation of the present invention, the backpack-type air-blowing working machine is preferably configured such that, when it is placed on a horizontal mounting surface such that the back plate portion is in a standing posture, the back plate portion is kept in the standing posture, in both of a state in which the battery pack is attached to the support rack portion of the backpack frame and a state after the battery pack is detached from the support rack portion. In this case, there is no need to support the backpack-type air-blowing working machine by hand to maintain standing posture, before and after attachment of the battery pack, so that it becomes possible to facilitate the detaching and attaching operations for charging the battery pack. Preferably, the volute casing is configured such that one of opposite ends thereof in a rightward-leftward direction has a blowing tube portion formed to blow out air therefrom and communicated with and connected to a blowing duct, and the other end thereof in the rightward-left direction has a joint with respect to the battery pack. In this case, the blowing duct is disposed on the one end of the volute casing in the rightward-leftward direction, and the battery pack is disposed on the other end of the volute casing in the rightward-leftward direction, so that it becomes possible to provide good weight balance in the rightward-leftward direction during use of the backpack-type air-blowing working machine. Preferably, the backpack-type air-blowing working machine is configured such that the position of the center of gravity of the backpack-type air-blowing working machine as viewed from the rear thereof is located within a region extending from a center line of the backpack frame in each of a rightward direction and a leftward direction, by a length of 10% of a maximum width of the backpack frame in the rightward-leftward direction. In this case, it becomes possible to prevent a load from being largely imposed on one of the right and left shoulders of the operator carrying the backpack frame on the back.

In addition to the above backpack-type air-blowing working machine, according to other aspects of the present invention, there are provided the following backpack-type air-blowing working machines. According to a second aspect of the present invention, there is provided a backpack-type air-blowing working machine in which a pair of volute casings arranged side-by-side in a forward-rearward direction and incorporating, respectively, a pair of centrifugal fans each configured to be driven by a respective one of a pair of front and rear electric motors arranged in a coaxial relation are assembled in an upstanding manner to a backpack frame to be carried on e back of an operator using shoulder straps during use. This backpack-type air-blowing working machine comprises a pair of rechargeable battery packs connected, respectively, to the electric motors, wherein the rechargeable battery packs are detachably attached to the backpack frame, such that a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the rear thereof is located below a rotation axis of the centrifugal fans, and a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the side thereof is located forward of a rear end of the volute casing, and wherein airflows blown out from respective blowing ports of the volute casings according to rotation of the centrifugal fans during operation of the electric motors are merged together and discharged from a blowing duct.

According to a third aspect of the present invention, there is provided a backpack-type air-blowing working machine including a pair of upper and lower volute casings. Each of the volute casings incorporate a centrifugal fan configured to be driven by an electric motor. Each of the volute casing is assembled in an upstanding manner to a backpack frame to be carried on the back of an operator using shoulder straps during use. This backpack-type air-blowing working machine comprises a rechargeable battery pack connected to each of the electric motors, wherein the rechargeable battery pack is detachably attached to the backpack frame, such that a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the rear thereof is located below an output shaft of the electric motor for driving the centrifugal fan in the upper volute casing, and a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the side thereof is located forward of rear ends of the pair of upper and lower volute casings, and wherein airflows blown out from respective blowing ports of the volute casings according to rotation of the centrifugal fans during operation of the electric motor are merged together and discharged from a blowing duct.

In the backpack-type air-blowing working machines according the second and third aspects of the present invention, a small-size fan may be used as each of the pair of centrifugal fans configured to be driven, respectively, by two small-size electric motors. Thus, as compared to a case of using a large-size fan configured to be driven by a single large-size electric motor, it becomes possible to reduce blowing noise, and obtain an airflow volume enough for cleaning by merging airflows from the centrifugal fans arranged side-by-side in the forward-rearward or upward-downward direction. Further, a pair of centrifugal fans each configured to be driven by an independent electric motor are incorporated, respectively, in the pair of volute casings disposed side-by-side in the forward-rearward or upward-downward direction to form a pair of individual blower units, so that it becomes possible to simplify assembling operation for the backpack-type air-blowing working machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a backpack-type air-blowing working machine according to a first embodiment of the present invention.

FIG. 2 is a vertical sectional view of the backpack-type air-blowing working machine depicted in FIG. 1, at a central position in a rightward-leftward direction.

FIG. 3 is a rear view of the backpack-type air-blowing working machine, in a state after a cover depicted in FIG. 2 is detached.

FIG. 4 is a vertical sectional view of a backpack-type air-blowing working machine according to a second embodiment of the present invention, at a central position in the rightward-leftward direction.

FIG. 5 is a horizontal sectional view depicting respective blowing tube portions of a pair of front and rear volute casings depicted in FIG. 4.

FIG. 6 is a sectional view depicting a coupling portion between the blowing tube portions and a blowing duct depicted in FIG. 5.

FIG. 7 is a vertical sectional view depicting a modification of the blower unit of the backpack-type air-blowing working machine depicted in FIG. 4.

FIG. 8a is a left side view of a backpack-type air-blowing working machine according to a third embodiment of the present invention.

FIG. 8b is a rear view of e backpack-type air-blowing working machine in FIG. 8a.

FIG. 9 is a vertical sectional view of the backpack-type air-blowing working machine depicted in FIG. 8b, at a position of each rotation axis thereof.

FIG. 10a is a left side view depicting backpack-type air-blowing working machine according to a fourth embodiment of the present invention.

FIG. 10b is a rear view of backpack-type air-blowing working machine in FIG. 10a.

FIG. 11 is a vertical sectional view of the backpack-type air-blowing working machine depicted in FIG. 10b, at a position of each rotation axis thereof.

FIG. 12a is a vertical sectional view of a backpack-type air-blowing working machine according to another embodiment of the present invention, at a position of each rotation axis thereof.

FIG. 12b is a vertical sectional view of a backpack-type air-blowing working machine according to yet another embodiment of the present invention, at a position of each rotation axis thereof.

FIG. 13a is a vertical sectional view of a backpack-type air-blowing working machine according to still another embodiment of the present invention, at a position of each rotation axis thereof.

FIG. 13b is a vertical sectional view of a backpack-type air-blowing working machine according to yet still another embodiment of the present invention, at a position of each rotation axis thereof.

FIG. 14 is a vertical sectional view of a backpack-type air-blowing working machine according to another further embodiment of the present invention, at a position of each rotation axis thereof.

FIG. 15a is a vertical sectional view of a backpack-type air-blowing working machine according to yet a further embodiment of the present invention, at a position of each rotation axis thereof.

FIG. 15b is a vertical sectional view of a backpack-type air-blowing working machine according to still a further embodiment of the present invention, at a position of each rotation axis thereof.

DESCRIPTION OF EMBODIMENTS

With reference to the accompanying drawings, a backpack-type air-blowing working machine of the present invention will be described based on various embodiments thereof, wherein the same elements or components will be described by assigning the same reference sign thereto.

First Embodiment

As depicted in FIGS. 1 to 3, a backpack-type air-blowing working machine 10 according to a first embodiment of the present invention comprises: a backpack frame 11 having a back plate portion 12 having a shape conforming to the back of an operator (i.e., a user or a worker); a spiral-shaped volute casing 21 assembled in a standing manner to the backpack frame 11 at a position rearward of the back plate portion 12; a centrifugal fan 22 rotatably pivoted within the volute casing 21; an electric motor 23 assembled to the volute casing 21 and operable to rotate the centrifugal fan 22; four (a plurality of) rechargeable battery packs 40 detachably attached to the backpack frame 11 at a position underneath the volute casing 21 and connected to the electric motor 23; and a control device 41 for controlling driving of the electric motor 23 and electric power feeding from the battery packs 40. In the first embodiment, a position of the center G of gravity of the backpack-type air-blowing working machine 10 as viewed from the rear thereof is located below a rotation axis (central axis) 22a of the centrifugal fan 22, and a position of the center G of gravity of the backpack-type air-blowing working machine 10 as viewed from the side thereof is located forward of a rear end of the volute casing 21.

The backpack frame 11 is configured to be carried on the back of the operator using shoulder straps 13. Each shoulder strap 13 is attached to a respective one of right and left ends of the back plate portions 12 of the backpack frame 11. The backpack frame 11 also has a support rack portion 14 integrally formed with the back plate portion 12 to extend horizontally and rearwardly from a lower end of the back plate portion 12, and the support rack portion 14 of the backpack frame 11 is formed with an air introduction port 14a for introducing therethrough air into a blower unit 20 composed of the volute casing 21, the centrifugal fan 22 and the electric motor 23. The blower unit 20 is configured to rotate the centrifugal fan 22 in the volute casing 21 according to the electric motor 23 to discharge air from a blowing port 21c at a distal end of an aftermentioned blowing tube portion 21b.

As depicted in FIG. 3, the volute casing 21 has a rear wall formed with an air suction port 21a, and a right wall provided with a blowing tube portion 21b extending outwardly. A blowing port 21c formed at a distal end of the blowing tube portion 21b is communicated with and connected to a blowing duct 30. As depicted in FIG. 2, the electric motor 23 is attached to a front wall of the volute casing 21. The centrifugal fan 22 is fixed to an output shaft 23a of the electric motor 23, within the volute casing 21. In this embodiment, as the electric motor 23, an outer rotor-type electric motor is employed. By rotatably attaching the centrifugal fan 22 to the output shaft 23a of the electric motor 23 integrally assembled to the front wall of the volute casing 21, the blower unit 20 is assembled in a standing manner, as a single unit, to the backpack frame 11 through a coil spring 15 (vibration damping means). In this embodiment, the centrifugal fan 22 is directly attached to the output shaft 23a of the electric motor 23, and the output shaft 23a of the electric motor 23 is disposed in coaxial relation to the rotation axis 22a of the centrifugal fan 22. The battery packs 40 and the control device 41 are mounted to the support rack portion 14 of the backpack frame 11 located just beneath the blower unit 20, as mentioned below.

As depicted in FIG. 1, the blowing duct 30 connected to the blowing port 21c of the volute casing 21 comprises a flexible duct 32 connected to a distal end of an elbow duct 31, and a straight duct 33 connected to a distal end of the flexible duct 32. A grip 34 to be gripped by an operator is attached to the straight duct 33, and a nozzle is attached to a distal end of the straight duct 33. During cleaning operation, an operator can manipulate the blowing duct 30 so as to direct the distal nozzle of the blowing duct 30 in a desired direction gripping the grip 34.

As depicted in FIGS. 2 and 3, on an upper surface of a rear end of the support rack portion 14 of the backpack frame 11, four joints (attachments) 16 for joining the battery packs 40 thereto are arranged side-by-side in a rightward-leftward direction. Through a sliding movement in forward-rearward direction, each of the battery packs 40 is detachably joined to a respective one of the joints 16. As each of the battery packs 40, it is possible to employ a type of battery pack is rechargeable by a battery charger (not depicted), in a state after it is detached from the joint 16, and commonly usable as a power supply for other electric gardening machines and various electric tools.

The control device 41 is disposed on an upper surface of a front end of the support rack portion 14 of the backpack frame 11. The control device 41 is operable to control driving of the electric motor 23 and control electric power feeding from the battery packs 40 to the electric motor 23. As depicted in FIGS. 1 and 2, the backpack frame 11 is provided with a cover 42 which covers the blower unit 20 and the control device 41, and the battery packs 40 are attached to the support rack portion 14 of the backpack frame 11 at positions outside the cover 42. The cover 42 is detachably attached to the backpack frame 11 so as to enable the blower unit 20 and the control device 41 be subjected to maintenance.

During use of the backpack-type air-blowing working machine 10 configured as above, an operator carries the backpack frame 11 on his/her back by putting the shoulder straps 13 over his/her shoulders, and starts to drive the electric motor 23 by electric power fed from the battery packs 40. Thus, the centrifugal fan 22 is rotated within the volute casing 21, and air sucked from the air suction port 21a into the volute casing 21 is discharged from the blowing port 21c into the blowing duct 30 and finally blown out from the distal nozzle of the blowing duct 30 toward the ground. Thus, the operator can move the distal nozzle of the blowing duct 30 in the rightward-leftward direction while gripping the grip 34 so as to blow and collect fallen leaves spread over the ground in a wide range.

The above backpack-type air-blowing working machine 10 is configured such that the electric motor 23 is driven by electric power fed from the battery packs 40. Thus, depending on mounting positions of the electric motor 23 and the four battery packs 40 to be mounted as heavy loads to the backpack frame 11, a difference arises in terms of usability or fatigue level in a situation where an operator performs cleaning operation while carrying the backpack-type air-blowing working machine 10 on his/her back. In this regard, the present inventors has ascertained that, when a position of the center of gravity of the backpack-type air-blowing working machine 10 is located close to an operator at a lower position as much as possible, it is possible to improve usability of the backpack-type air-blowing working machine 10 and reduce fatigue of the operator.

In the first embodiment configured by taking into account the above matter, the volute casing 21 is disposed in a standing manner rearward of the back plate portion 12, in such a manner that an axis of a volute of volute casing 21 is located in orthogonal relation to the back plate portion 12. In this way, a length of the backpack frame 11 in the forward-rearward direction is reduced to enable the volute casing 21 to be disposed at a position closer to the back of an operator. Further, in the first embodiment, the electric motor 23 as a heavy load is fixed to the front wall of the volute casing 21 so as to conic close to the back of an operator. Furthermore, in the first embodiment, the battery packs 40 are assembled, respectively, to the joints 16 on the support rack portion 14 formed to extend rearwardly and horizontally from the lower end of the back plate portion 12 of the backpack frame 11 and located just beneath the volute casing 21, in such a manner as to be disassemblable in the forward-rearward direction.

Thus, in the backpack-type air-blowing working machine 10 according to the first embodiment, in a state in which an operator stands while carrying the backpack-type air-blowing working machine 10 on his/her back, a position of the center G of gravity of the backpack-type air-blowing working machine 10 as viewed from the rear thereof is located below the rotation axis 22a of the centrifugal fan 22, and a position of the center G of gravity of the backpack-type air-blowing working machine 10 as viewed from the side thereof is located forward of the rear end of the volute casing 21, particularly, in the first embodiment, located forward of a center line Cf of the volute casing 21 in the forward-rearward direction, as depicted in FIGS. 2 and 3. It has been ascertained that when an operator performs cleaning operation while carrying the backpack-type air-blowing working machine 10 on his/her shoulder using the shoulder straps 13, a weight of the backpack-type air-blowing working machine 10 is supported by the lumbar region of the operator, and therefore the backpack-type air-blowing working machine 10 is stabilized, so that the operator becomes less likely to rearwardly, thereby making it possible to more easily manipulate the air-blowing working machine 10 to reduce fatigue of the operator. In this way, even when an operator performs cleaning operation while carrying the backpack-type air-blowing working machine 10 on his/her back, it becomes possible to prevent the shoulder straps 13 from be put over the shoulders of the operator in such a manner as to pull the operator rearwardly, and thus enable the operator to become less likely to fall down rearwardly and thus become less likely to fatigue.

In the first embodiment, in charging operation for the battery packs 40, the battery packs 40 can be detached from the support rack portion 14 without detaching, from the backpack frame 11, the cover 42 covering the blower unit 20 and the control device 41, so that it becomes possible to detach the battery packs 40 without taking time and effort for detaching the cover 42.

In the first embodiment, when the backpack-type air-blowing working machine 10 is placed on a horizontal mounting surface such that the back plate portion 12 is in a standing posture, the back plate portion 12 is kept in the standing posture, in both of the state in which the battery packs 40 are attached to the support rack portion 14 of the backpack frame 11 and the state after the battery packs 40 are detached from the support rack portion 14. Thus, there is no need to support the backpack-type air-blowing working machine 10 by hand to maintain the standing posture, before and after attachment of the battery packs 40, so that it becomes possible to facilitate the detaching and attaching operations for charging the battery packs 40.

In the first embodiment, the position of the center G of gravity of the backpack-type air-blowing working machine 10 as viewed from the rear thereof is located within a region Cw extending from a center line C of the backpack frame 11 in each of a rightward direction and a leftward direction, by a length of 10% of a maximum width of the backpack frame 11 in the rightward-leftward direction, so that it becomes possible to prevent a load from being largely imposed on one of the right and left shoulders of the operator carrying the backpack frame 11 on his/her back. Further, in the first embodiment, respective sets of the four (plurality of) joints 16 and the four (plurality of) battery packs 40 are equally divided into two and arranged on both sides of a center line of the backpack frame 11 in the rightward-leftward direction. This makes it possible to provide good weight balance in the rightward-leftward direction of the backpack-type air-blowing working machine 10.

Second Embodiment

As depicted in FIGS. 4 to 6, in a backpack-type air-blowing working machine 10 according to a second embodiment of the present invention, a pair of front and rear volute casings 21A, 21B internally provided, respectively, with a pair of centrifugal fans 22A, 22B each configured to be driven by a respective one of a pair of front and rear electric motors 23A, 23B arranged in coaxial relation are assembled in a standing manner to a backpack frame 11. Positions of the rear volute casing 21B and the rear centrifugal fan 22B are also shown in FIG. 3.

As depicted in FIG. 4, the first electric motor 23A is integrally assembled to a rear wall of the front-side first volute casing 21A, and the first centrifugal fan 22A is rotatably attached to an output shaft 23Aa of the first electric motor 23A within the first volute casing 21A, to form a first blower unit 20A. As depicted in FIGS. 4 and 5, the first volute casing 21A has a front wall formed with an air suction port 21Aa, and a right wall provided with a blowing tube portion 21Ab serving as a spiral-shaped outer distal end. The second electric motor 23B is integrally assembled to a front wall of the rear-side second volute casing 21B, and the second centrifugal fan 22B is rotatably attached to an output shaft 23Ba of the second electric motor 23B within the second volute casing 21B, to form a second blower unit 20B. As depicted in FIG. 5, the second volute casing 21B has a rear wall formed with an air suction port 21Ba, and a right wall provided with a blowing tube portion 21Bb serving as a spiral-shaped outer distal end. Respective blowing ports 21Ac, 21Bc of the first and second volute casings 21A, 21B are communicated with and connected to an elbow duct 31 of a blowing duct 30 so as to enable airflows discharged from the blowing tube portions 21Ab, 21Bb to be merged together and discharged thereinto.

The first volute casing 21A is formed such that a spiral-shaped air passage is gradually expanded toward the blowing port 21Ac. More specifically, it is formed such that, toward the blowing port 21Ac, a spiral-shaped air passage is gradually expanded rearwardly in an axial direction of a volute of the first volute casing 21A. The second volute casing 21B is formed such that a spiral-shaped air passage is gradually expanded toward the blowing port 21Bc. More specifically, it is formed such that, toward the blowing port 21Bc, the spiral-shaped air passage is gradually expanded forwardly in an axial direction of a volute of the second volute casing 21B. As above, the first and second volute casings 21A, 21B are displaced to gradually come closer to each other in the axial direction, toward the blowing ports 21Ac, 21Bc, and respective distal ends of the blowing tube portions 21Ab, 21Bb of the first and second volute casings 21A, 21B are communicated with and connected to an inlet region 31a of the blowing duct 30.

In the first embodiment, the blowing tube portions 21Ab, 21Bb of the first and second volute casings 21A, 21B are displaced to gradually come closer to each other in the axial direction, toward the blowing ports 21Ac, 21Bc, airflows discharged from the blowing tube portions 21Ab, 21Bb are merged such that a discharge direction of air blown out from the blowing port 21Ac of the blowing tube portion 21Ab and a discharge direction of air blown out from the blowing port 21Bc of the blowing tube portion 21Bb intersect each other at an angle θ of 5° (see FIG. 6).

As with the first embodiment, the volute casing 21A is fixed to a back plate portion 12 through a coil spring 15, so that the first blower unit 20A is elastically supported by the backpack frame 11. Further, the second electric motor 20B is coaxially fixed to the first electric motor 23A, so that the second blower unit 20B is elastically supported by the backpack frame 11 through the first blower unit 20A.

Battery packs 40 for feeding electric power to the electric motors 23A, 23B are attached onto a support rack portion 14 formed to extend rearwardly and horizontally from a lower end of the back plate portion 12 of the backpack frame 11 and located just beneath the volute casings 21A, 21B, in such a manner as to be detachable in a frontward-rearward direction, as with the first embodiment. A control device 41 for controlling driving of the electric motors 23A, 23B is also attached to an upper surface of a front end of support rack portion 14. Remaining major structures are the same as those in the first embodiment.

The backpack-type air-blowing working machine 10 according to the second embodiment configured such that air is blown by the first centrifugal fan 22A, and the second centrifugal fan 22B which is a separate component from the first centrifugal fan 22A, and respective airflows from the first and second centrifugal fans 22A, 22B are merged in the inlet region 31a of the blowing duct 30. In the backpack-type air-blowing working machine 10 according to the second embodiment, when the fan is reduced in size, it is possible to obtain a sufficient airflow volume by the two centrifugal fans 22A, 22B, while reducing blowing noise as compared to the case of using a single large fan. Further, the backpack-type air-blowing working machine 10 according to the second embodiment comprises the first electric motor 23A for rotating the first centrifugal fan 22A, and the second electric motor 23B for rotating the second centrifugal fan 22B. This makes it possible to facilitate reduction in size of each of the first and second electric motors 23A, 23B and keep down driving noise generated from the first and second electric motors 23A, 23B as compared to the case of using a single large fan to rotate the first and second centrifugal fans 22A, 22B.

The backpack-type air-blowing working machine 10 according to the second embodiment is configured such that airflows blown out from the blowing ports 21Ac, 21Bc of the first and second volute casings 21A, 21B of the first and second blower units 20A, 20B are merged in the inlet region 31a of the blowing duct 30 and then discharged. In the second embodiment, the angle θ defined by a course direction of air discharged from the blowing port 21Ac of the first volute casing 21A and a course direction of air discharged from the blowing port 21Bc of the second volute casing 21B is set to 5° so as to allow the two course directions to become maximally close to parallel relation. This makes it possible to reduce a situation where respective airflows blown out from the blowing ports 21Ac, 21Bc of the first and second volute casings 21A, 21B collide with each other to cause a reduction in airflow volume. It should be noted that the angle θ defined by the course direction of air discharged from the blowing port 21Ac of the first volute casing 21A and the course direction of air discharged from the blowing port 21Bc of the second volute casing 21B is not limited to 5°, but may be appropriately set in the range of 5° to 45°. In this case, it is also possible to obtain a required effect.

In the backpack-type air-blowing working machine 10 according to the second embodiment, the electric motors 23A, 23B as heavy loads are arranged as forward as possible to come close to the back of an operator, and the battery packs 40 are assembled onto the support rack portion 14 of the backpack frame 11 in such a manner as to be disassemblable in the forward-rearward direction, as with the first embodiment. In a state in which an operator stands while carrying the backpack-type air-blowing working machine 10 on his/her back, a position of the center G of gravity of the backpack-type air-blowing working machine 10 as viewed from the rear thereof is located below respective rotation axes 22Aa, 22Ba of the centrifugal fans 22A, 22B, and a position of the center G of gravity of the backpack-type air-blowing working machine 10 as viewed from the side thereof is located forward of a rear end of the rear-side second volute casing 21B, particularly, in the second embodiment, located forward of a center line Cf of the rear-side second volute casing 21B in the forward-rearward direction. (Although FIG. 3 is a rear view of the backpack-type air-blowing working machine 10 according to the first embodiment, the backpack-type air-blowing working machine 10 according to the second embodiment can be depicted in the same manner as that in FIG. 3. Thus, the reference signs in the second embodiment are added to corresponding reference signs in FIG. 3 in brackets.) It has been ascertained that when an operator performs cleaning operation while carrying the backpack-type air-blowing working machine 10 on his/her shoulder using the shoulder straps 13, it becomes possible to prevent the shoulder straps 13 from be put over the shoulders of the operator in such a manner as to pull the operator rearwardly, and thus enable the operator to become less likely to fall down rearwardly and thus become less likely fatigue. Remaining functions/effects are the same as those in the first embodiment.

As depicted in FIG. 7, in a modification of the backpack-type air-blowing working machine 10 according to the second embodiment, the first blower unit 20A and the second blower unit 20B each lying in a horizontal posture are arranged one-above-the-other, and assembled to the backpack frame 11. In this case, the air suction port 21Aa is provided in an upper wall of the first blower unit 20A, and the air suction port 21Ba is provided in a lower wall of the second blower unit 20B. Remaining structures are substantially the same as those in the second embodiment.

Third Embodiment

As depicted in FIGS. 8a, 8b and 9, a backpack-type air-blowing working machine 10 according to a third embodiment of the present invention is characterized in that a first blower unit 20A and a second blower unit 20B are arranged one-above-the-other at a position behind an aftermentioned back plate portion 12. In the third embodiment, the first blower unit 20A and the second blower unit 20B are arranged one-above-the-other at a position offset rightwardly from a center line of a back plate portion 12 of a backpack frame 11 in a rightward-leftward direction (see FIG. 8b), in order to achieve a weight balance when aftermentioned battery packs 40 are arranged side-by-side in an upward-downward direction, in a left end region of back plate portion 12.

As depicted in FIG. 9, a first electric motor 32A is integrally assembled to a front wall of an upper-side first volute casing 21A, and a first centrifugal fan 22A is rotatably attached to an output shaft 23Aa of the first electric motor 23A within the first volute casing 21A, to form the first blower unit 20A. Similarly, a second electric motor 23B is integrally assembled to a front wall of a lower-side second volute casing 21B, and a second centrifugal fan 22B is rotatably attached to an output shaft 23Ba of the second electric motor 23B within the second volute casing 21B, to form the second blower unit 20B.

As depicted in FIGS. 8a, 8b and 9, each of the first and second volute casings 21A, 21B has a rear wall formed with an air suction port (21Aa, 21Ba), and a right wall provided with a blowing tube portion (21Ab, 21Bb) serving as a spiral-shaped outer distal end. Respective blowing ports 21Ac, 21Bc of the first and second volute casings 21A, 21B are communicated with and connected to an inlet region 31a of a blowing duct 30, respectively, through a first connection duct 24A and a second connection duct 24B, so that airflows discharged from the blowing tube portions 21Ab, 21Bb are merged together through the first and second connection ducts 24A, 24B, and introduced into the blowing duct 30.

In the left end region of the back plate portion 12, four joints (attachments) 16 for four battery packs 40 are arranged side-by-side in the upward-downward direction. Through a sliding movement in a forward-rearward direction, each of the battery packs 40 is detachably attached to a respective one of the joints 16. The four battery packs 40 are detachably attached, respectively, to the joints 16 of the backpack frame 11, at positions outside a cover 42. Further, the four battery packs 40 is attached to the left end region of the back plate portion 12 in order to achieve a weight balance in the rightward-leftward direction, with respect to the blowing duct 30 communicated with and connected to the blowing ports 21Ac, 21Bc of the first and second volute casings 21A, 21B on a right side of the backpack frame 11.

In the backpack-type air-blowing working machine 10 according to the third embodiment, the electric motors 23A, 23B assembled to the first and second volute casings 21A, 21B are arranged just behind the back plate portion 12, and the battery packs 40 are arranged below a rotation axis 22Aa of the upper-side first centrifugal fan 22A. Thus, a position of the center G of gravity of the backpack-type air-blowing working machine 10 as viewed from the rear thereof is located below the rotation axis 22Aa of the upper-side first centrifugal fan 22A, and a position of the center G of gravity of the backpack-type air-blowing working machine 10 as viewed from the side thereof is located forward of rear ends of the first and second volute casings 21A, 21B, particularly, in the third embodiment, located forward of a center line Cf of the first and second volute casings 21A, 21B in the forward-rearward direction. In this way, even when an operator performs cleaning operation while carrying the backpack-type air-blowing working machine 10 on his/her back, it becomes possible to prevent shoulder straps 13 from be put over the shoulders of the operator in such a manner as to pull the operator rearwardly, thereby facilitating the cleaning operation. In the third embodiment, the position of the center G of gravity of the backpack-type air-blowing working machine as viewed from the rear thereof is located within a region Cw extending from a center line C of the backpack frame 11 in each of a rightward direction and a leftward direction, by a length of 10% of a maximum width of the backpack frame 11 in the rightward-leftward direction, so that it becomes possible to prevent a load from being largely imposed on one of the right and left shoulders of the operator carrying the backpack frame 11 on the back.

In the third embodiment, when the backpack-type air-blowing working machine 10 is placed on a horizontal mounting surface such that the back plate portion 12 is in a standing posture, the hack plate portion 12 is kept in the standing posture, in both of a state in which the battery packs 40 are attached to the joints 16 of back plate portion 12 of the backpack frame 11 and a state after the battery packs 40 are detached from the joints 16 of the back plate portion 12. Thus, there is no need to support the backpack-type air-blowing working machine 10 by hand to maintain the standing posture, before and after attachment of the battery packs 40, so that it becomes possible to facilitate the detaching and attaching operations for charging the battery packs 40.

In the backpack-type air-blowing working machine 10 according to the third embodiment, each of the volute casings 21A, 21B has a respective blowing tube portion 21Ab, 21Bb for blowing out air, on a right side thereof as one side in the rightward-leftward direction, and the blowing duct 30 is communicated with and connected to the blowing tube portion 21Ab, 21Bb. On the other hand, the joints 16 for the battery packs 40 are provided on a left side of the backpack frame 11 as the other side in the rightward-leftward direction. That is, the blowing duct 30 is disposed on the right side as one side in the rightward-leftward direction, and the battery packs 40 are arranged on the left side as the other side in the rightward-leftward direction, so that becomes possible to provide good weight balance in the rightward-leftward direction during use of the backpack-type air-blowing working machine 10.

In the backpack-type air-blowing working machine 10 according to the third embodiment, airflows blown out from the blowing ports 21Ac, 21Bc of the first and second volute casings 21A, 21B of the first and second blower units 20A, 20B are merged in the inlet region 31a of the blowing duct 30 through the first and second connection ducts 24A, 24B, and then discharged. In the third embodiment, an angle θ defined by a course direction of air discharged from the blowing port 21Ac of the first volute casing 21A and a course direction of air discharged from the blowing port 21Bc of the second volute casing 21B is set to 45°. This makes it possible to reduce a situation where respective airflows blown out from the blowing ports 21Ac, 21Bc of the first and second volute casings 21A, 21B collide with each other to cause a reduction in airflow volume. As regards other functions/effects, it is possible to obtain the same functions/effects as those in the second embodiment.

Fourth Embodiment

As depicted in FIGS. 10a, 10b and 11, in a backpack-type air-blowing working machine 10 according to a fourth embodiment of the present invention, a first blower unit 20A and a second blower unit 20B are arranged one-above-the-other at a position behind a back plate portion 12, as with the third embodiment. Further, the lower-side second blower unit 20B is disposed offset rearwardly from the first blower unit 20A so as to eliminate interference or contact between a lower portion of the upper-side first blower unit 20A and an upper portion of the lower-side second blower unit 20B, and the upper-side first blower unit 20A is disposed at a lower position than that in the third embodiment. In the fourth embodiment, the first blower unit 20A and the second blower unit 20B are arranged rearwardly as compared to the position in the third embodiment. Thus, a plurality of battery packs 40 can be arranged to come close to a central region of the back plate portion 12. Further, the first blower unit 20A and the second blower unit 20B are arranged in an overlapping manner in the upward-downward direction, so that an angle θ defined by a course direction of air discharged from a blowing port 21Ac of a first volute casing 21A and a course direction of air discharged from a blowing port 21Bc of a second volute casing 21B can be set to 8.5°. Thus, the angle θ can be reduced to a smaller value than that in the third embodiment. This makes it possible to reduce the situation where respective airflows blown out from the blowing ports 21Ac, 21Bc collide with each other to cause a reduction in airflow volume, more effectively as compared to the third embodiment. As regards other functions/effects, it is possible to obtain the same functions/effects as those in the third embodiment.

Other Embodiments

In implementation of the present invention, as in a modification of the backpack-type air-blowing working machine 10 according to the fourth embodiment depicted in FIG. 12a, each of the first and second blower units 20A, 20B may be turned back-to-front, and the upper-side first blower unit 20A may be disposed forward of the lower-side second blower unit 20B, i.e., the lower-side second blower unit 20B may be disposed rearward of the upper-side first blower unit 20A. Alternatively, as in another modification depicted in FIG. 12b, the upper-side first blower unit 20A may be disposed rearward of the lower-side second blower unit 20B, i.e., the lower-side second blower unit 20B may be disposed forward of the upper-side first blower unit 20A.

Further, as depicted in FIG. 13a, the air suction port 21Aa of the upper-side first blower unit 20A may be disposed to face rearwardly, and the air suction port 21Ba of the lower-side second blower unit 20B may be disposed to face forwardly. In this case, each of the blowing tube portions 21Ab, 21Bb of the first and second blower units 20A, 20B extends downwardly, and each of the blowing ports 21Ac, 21Bc faces obliquely downwardly. In this modification, the angle θ defined by the course direction of air discharged from the blowing port 21Ac of the first volute casing 21A and the course direction of air discharged from the blowing port 21Bc of the second volute casing 21B is set in the range of 5° to 45°, and airflows discharged from the volute casings 21A, 21B are merged in the inlet region 31a of the blowing duct 30, so that it becomes possible to suppress the possibility that respective airflows blown out from the blowing ports 21Ac, 21Bc collide with each other.

Further, as depicted in FIG. 13b, a spiral direction of a volute in the volute casing of the lower-side second blower unit 20B may be reversed to enable the blowing port 21Bc to face obliquely upwardly.

A backpack-type air-blowing working machine 10 according an embodiment depicted in FIG. 14 is characterized in that a first blower unit 20A and a second blower unit 20B are arranged one-above-the-other at a position behind a back plate portion 12, and each of output shafts 23Aa, 23Ba of first and second electric motors 23A, 23B each operable to drive a respective one of first and second centrifugal fans 22A, 22B is disposed to incline obliquely downwardly in a rearward direction at an inclination angle of 45°. In this embodiment, as with the aforementioned embodiments, a position of the center G of gravity of the backpack-type air-blowing working machine 10 as viewed from the rear thereof is located below a rotation axis 22Aa of the first centrifugal fan 22A, and a position of the center G of gravity of the backpack-type air-blowing working machine 10 as viewed from the side thereof is located forward of a center line of the first and second volute casings 21A, 21B in the forward-rearward direction, so that even when an operator performs cleaning operation while carrying the backpack-type air-blowing working machine 10 on his/her back, it becomes possible to prevent shoulder straps 13 from be put over the shoulders of the operator in such a manner as to pull the operator rearwardly, thereby facilitating the cleaning operation.

In implementation of the present invention, as depicted in FIG. 15a, a first blower unit 20A and a second blower unit 20B may be arranged such that each of an air suction port 21Aa and an air suction port 21Ba thereof faces forwardly and obliquely downwardly. Alternatively, as depicted in FIG. 15b, the first and second volute casings 21A, 21B may be arranged such that each of the air suction ports 21Aa, 21Ba thereof faces forwardly and obliquely upwardly. In these embodiments, each of the first and second blower units 20A, 20B is inclined by 45°. However, this inclination angle is not limited to 45°. Further, the first volute casing 21A and the second volute casing 21B may be inclined, respectively, at different inclination angles.

In the above embodiments, it is desirable to avoid forming an opening in the cover 42 if possible. Further, in the backpack frame 11, the back plate portion 12 is formed with an air introduction port 12a, and the support rack portion 14 is formed with the air introduction port 14a. Alternatively, only the support rack portion 14 is formed with the air introduction port 14a. In the case where only the support rack portion 14 is formed with the air introduction port 14a, a space defined by the backpack frame 11 and the cover 42 is opened to the outside only via the air introduction port 14a of the support rack portion 14, so that it becomes possible to reduce noise to be felt by an operator. In the above embodiments, a sound absorption material may be provided on an inner surface of the cover 42, or a sound absorption material such as sponge or a sound absorption structure such as a silencer may be provided in the first and second volute casings 21A, 21B or a blowing passage such as the blowing duct 30. This makes it possible to further reduce noise to be felt by an operator.

The functions/effects arising from the reductions in size of fan and the electric motor, and the merging of airflows from the blowing ports, based on providing two blower units, i.e., the first and second blower units 20A, 20B, can be obtained in any other suitable type of backpack-type air-blowing working machine. For example, a fan is not limited to a centrifugal fan, but an axial flow fan or a diagonal flow fan provided in a cylindrical casing may be used to obtain the same functions/effects. Further, in addition to a prime mover composed of an electric motor, an engine-type prime mover composed of an internal combustion engine may be used to obtain the same functions/effects.

Claims

1. A backpack-type air-blowing working machine comprising: a backpack frame having at least a back plate portion conformable to the back of an operator, the backpack frame being configured to be carried on the back of the operator through the back plate portion using shoulder straps;a volute casing mounted to the backpack frame at a position rearward of the back plate portion, in such a manner that a center of a volute is set in a direction intersecting a planar direction of the back plate portion;a centrifugal fan rotatably supported within the volute casing;an electric motor assembled to the volute casing and operable to rotate the centrifugal fan; anda rechargeable battery pack attached to the backpack frame and operable to feed electric power to the electric motor,wherein the backpack-type air-blowing working machine is configured such that a position of the center of gravity of the backpack-type air-blowing working machine as viewed from a rear thereof is located below a rotation axis of the centrifugal fan, and a position of the center of gravity of the backpack-type air-blowing working machine as viewed from a side thereof is located forward of a rear end of the volute casing.

2. The backpack-type air-blowing working machine as recited in claim 1, wherein the backpack frame further has a support rack portion provided to extend rearwardly from a lower end of the back plate portion and located just beneath the volute casing, and wherein the battery pack is assembled onto the support rack portion in such a manner as to be disassemblable in a forward-rearward direction.

3. The backpack-type air-blowing working machine as recited in claim 1, wherein the backpack frame further has a support rack portion provided to extend rearwardly and horizontally from a lower end of the backpack frame and located just beneath the volute casing, and the battery pack is composed of a plurality of rechargeable battery packs, each of the plurality of rechargeable battery packs is connected to the electric motor, and each of the plurality of rechargeable battery packs is assembled onto the support rack in a manner that allows for disassembly of the respective battery pack from the electric motor in a forward-rearward direction.

4. The backpack-type air-blowing working machine as recited in claim 2, which comprises a cover covering the volute casing, the cover being detachably attached to the backpack frame in such a manner that the battery pack assembled onto the support rack portion is located outside the cover.

5. The backpack-type air-blowing working machine as recited in claim 1, wherein the volute casing is configured such that one of opposite ends thereof in a rightward-leftward direction has a blowing tube portion formed to blow out air therefrom and communicated with and connected to a blowing duct, and the other end thereof in the rightward-leftward direction has a joint with respect to the battery pack.

6. The backpack-type air-blowing working machine as recited in claim 5, wherein the battery pack is composed of a plurality of rechargeable battery packs each of the plurality of rechargeable battery packs is connected to the electric motor, the plurality of rechargeable battery packs being arranged on one side of the back plate portion of the backpack frame in the rightward-leftward direction to extend in an upward-downward direction, and attached to the back plate portion in such a manner that allows for disassembly of the respective battery pack from the electric motor in a forward-rearward direction.

7. The backpack-type air-blowing working machine as recited in claim 2, which is configured such that, when the backpack-type air-blowing working machine is placed on a horizontal mounting surface such that the back plate portion is in a standing posture, the backpack-type air-blowing working machine stands by itself while keeping the back plate portion in the standing posture, in both of a state in which the battery pack is attached to the support rack portion and a state after the battery pack is detached from the support rack portion.

8. The backpack-type air-blowing working machine as recited in claim 1, which is configured such that the position of the center of gravity of the backpack-type air-blowing working machine as viewed from the rear thereof is located within a region extending from a center line of the backpack frame in each of a rightward direction and a leftward direction, by a length of 10% of a maximum width of the backpack frame in the rightward-leftward direction.

9. A backpack-type air-blowing working machine in which a pair of volute casings arranged side-by-side in a forward-rearward direction and incorporating, respectively, a pair of centrifugal fans each configured to be driven by a respective one of a pair of front and rear electric motors arranged in a coaxial relation are assembled in an upstanding manner to a backpack frame to be carried on the back of an operator using shoulder straps during use, the backpack-type air-blowing working machine comprising: a pair of rechargeable battery packs connected, respectively, to the electric motors, wherein the rechargeable battery packs are detachably attached to the backpack frame, such that a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the rear thereof is located below a rotation axis of the centrifugal fans, and a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the side thereof is located forward of a rear end of the volute casing,and wherein airflows blown out from respective blowing ports of the volute casings according to rotation of the centrifugal fans during operation of the electric motors are merged together and discharged from a blowing duct.

10. A backpack-type air-blowing working machine in which a pair of upper and lower volute casings each incorporating a centrifugal fan configured to be driven by an electric motor are assembled in an upstanding manner to a backpack frame to be carried on the back of an operator using shoulder straps during use, the backpack-type air-blowing working machine comprising: a rechargeable battery pack connected to each of the electric motors, wherein the rechargeable battery pack is detachably attached to the backpack frame, such that a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the rear thereof is located below an output shaft of the electric motor for driving the centrifugal fan in the upper volute casing, and a position of the center of gravity of the backpack-type air-blowing working machine as viewed from the side thereof is located forward of rear ends of the pair of upper and lower volute casings,and wherein airflows blown out from respective blowing ports of the volute casings according to rotation of the centrifugal fans during operation of the electric motor are merged together and discharged from a blowing duct.