US20150377253A1

US20150377253A1 - Power-operated air blowing work apparatus

Info

Publication number: US20150377253A1
Application number: US14/753,270
Authority: US
Inventors: Yoshinori Shibata; Hideaki Takano
Original assignee: Makita Corp
Current assignee: Makita Corp
Priority date: 2014-06-30
Filing date: 2015-06-29
Publication date: 2015-12-31
Also published as: DE102015008189B4; DE102015008189A1; JP6242758B2; JP2016011542A

Abstract

A power-operated air blowing work apparatus comprises: a volute casing including a centrifugal fan installed therein and having a front wall formed with an air intake aperture for sucking air from an atmosphere into the volute casing by the centrifugal fan; an engine mounted to the volute casing in a rear side of the volute casing and connected to the centrifugal fan for rotating the centrifugal fan; an engine casing covering the engine from behind the engine in the rear side of the volute casing, and an air suction passage communicating from inside the engine casing toward inside the front wall of the volute casing for drawing air in the engine casing toward inside the front wall of the volute casing.

Description

TECHNICAL FIELD

The present invention relates to a power-operated air blowing work apparatus such as a blower apparatus or a dust collector apparatus, and more particularly to an engine-driven air blowing work apparatus provided with an air-cooling configuration to efficiently air-cool the engine which drives the air blowing fan.

BACKGROUND INFORMATION

Blower apparatuses have been conventionally known and used for blowing off fallen leaves on the ground or the like. An example of blower apparatuses is disclosed in JP H11-148,122 A, in which the blower apparatus includes a centrifugal fan driven by an engine. The disclosed blower apparatus comprises a back carrier frame to be piggybacked by an operator, a volute casing including a centrifugal fan mounted on the back carrier frame, and an air-cooled engine mounted on the back carrier frame to the rear of the volute casing for driving the fan. The volute casing of this blower apparatus is of a two-stage structure, including a first volute casing and a second volute casing respectively covering front fan blades and rear fan blades disposed on a rotating disk of a centrifugal fan, wherein the fan sucks in air through the air intake port formed in the front wall of the first volute casing, sends the air at a given pressure and speed through a communicating air passage to an air intake port formed in the rear wall of the second volute casing, and further pressurizes and speeds up the air in the second volute casing before blowing out air from the air outlet duct of the volute casing. The air outlet duct of the volute casing is communicatingly coupled to the blow-off tube of the blower apparatus, so that the blower apparatus finally blows out air from the distal end of the blow-off tube.
In the disclosed blower apparatus, the communicating air passage is formed on its way with a cooling air outlet port so that a part of the air sent out from the first volute casing is blown out toward the engine from the cooling air outlet port to air-cool the engine.
As a part of the air sucked in the volute casing is blown out toward the engine to cool the engine in the above disclosed prior art blower apparatus, the volute casing includes the first and the second volute casing respectively covering the front fan blades and the rear fan blades of the centrifugal fan configured in a two stage structure and the first volute casing and the second volute casing are connected through the communicating air passage, in order to compensate the decrease in the air sending efficiency due to the loss of air used for cooling the engine on the way from the first volute casing to the second volute casing. Thus, the above disclosed blower apparatus would be complicated in structure and would be accordingly costly.

SUMMARY OF THE INVENTION

In view of the foregoing circumstances, therefore, it is a primary object of the present invention to provide a power-operated work apparatus such as a blower apparatus, in which an engine is efficiently cooled without complicating the structure of the volute casing to compensate an air sending loss.
According to the present invention, the object is accomplished by providing a power-operated air blowing work apparatus comprising: a volute casing including a centrifugal fan installed therein and having a front wall formed with an air intake aperture for sucking air into the volute casing by the centrifugal fan; an engine mounted to the volute casing in a rear side of the volute casing and connected to the centrifugal fan for rotating the centrifugal fan; an engine casing covering the engine from behind the engine in the rear side of the volute casing, and an air suction passage communicating from inside the engine casing toward inside the front wall of the volute casing for drawing air in the engine casing toward the front wall of the volute casing.
With a power-operated air blowing apparatus configured as above in which an air suction passage is provided communicating from inside the engine casing toward inside the front wall of the volute casing for drawing air in the engine casing toward inside the front wall of the volute casing, the centrifugal fan driven by the engine sucks air from the air intake aperture in the front wall of the volute casing and the air in the engine casing is also sucked toward inside the front wall via the air suction passage so that the air around the engine also flows toward the air suction passage, cooling the engine.
According to the present invention, the engine casing may preferably be formed with an air intake opening for introducing air from an atmosphere into the engine casing so that the air suction passage may draw the introduced air toward inside the front wall of the volute casing. With this configuration, the air introduced from an atmosphere into the engine casing through the air intake opening flows around the engine before drawn to inside the front wall of the volute casing, so that the engine will be efficiently cooled by the air introduced from the atmosphere. Unlike the prior art configuration as cited above, the apparatus according to the present invention does not blow out air from the volute casing into the engine casing, which means there will be no loss in the fan operation, and there will be no need of forming the volute casing of a complicated two-stage structure.
According to the present invention, the volute casing may have a rear wall formed with an air outlet aperture for directing a part of the air sucked into the volute casing through the air intake aperture to the engine casing through the air outlet aperture so that the air suction passage may draw the air in the engine casing toward inside the front wall of the volute casing. With this configuration, the air directed from the volute casing to the engine casing flows around the engine before drawn to inside the front wall of the volute casing, so that the engine will be efficiently cooled by the air directed from the volute casing. Unlike the prior art configuration as cited above, the air directed from the volute casing to the engine is drawn back to inside the front wall of the volute casing, which will minimize losses of the fanned air, and there will be no need of forming the volute casing of a complicated two-stage configuration.
According to the present invention, the engine casing may preferably be lined inside with a sound insulating member for preventing engine noise from leaking outside, and the sound insulating member may form a channel between the engine casing and the sound insulating material so that the channel will serve as a part of the air suction passage. Or alternatively, the sound insulating material itself may be provided therethrough with a penetrating hole to constitute a part of the air suction passage. Or alternatively, the air suction passage may be formed from behind the volute casing, around outside the volute casing and toward inside the front wall of the volute casing.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how the same may be practiced and will work, reference will now be made, by way of example, to the accompanying drawings, in which

FIG. 1 is a right side view of a backpack blower apparatus as an embodiment of a power-operated work apparatus according to the present invention;

FIG. 2 is a rear view of the sound insulating member formed with air suction passages and of the fuel tank;

FIG. 3 is a side view of the backpack blower apparatus according to the present invention in cross section taken along the arrowed line A-A of FIG. 2;

FIG. 4 is a side view of the backpack blower apparatus according to the present invention in cross section taken along the arrowed line B-B of FIG. 2;

FIG. 5 is a side view of the backpack blower apparatus according to the present invention in cross section taken along the arrowed line C-C of FIG. 2;

FIG. 6 is a side view of the backpack blower apparatus according to the present invention in cross section taken along the arrowed line D-D of FIG. 2;

FIG. 7 is a side view of another embodiment of the backpack blower apparatus in cross section in which the sound insulating member is not formed with an air suction passage;

FIG. 8 is a side view of a further embodiment of the backpack blower apparatus in cross section in which a bottom cover member is provided to form an air suction passage from inside the engine casing toward inside the front wall of the volute casing; and

FIG. 9 is a side view of a backpack blower apparatus according to the present invention in cross section as viewed along the same line as FIG. 4, but provided with an air outlet aperture in the rear wall of the volute casing.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention and its embodiments can now be better understood by turning to the following detailed description of the preferred embodiments with reference to the accompanying drawings. The invention will hereunder be described about a backpack blower apparatus in which the configuration according to the present invention is employed. It should be understood, however, that the configuration according to the present invention is applicable not only to a backpack blower apparatus, but also to a hand-held blower apparatus. Further, the invention is also applicable to a dust collector apparatus of a backpack type or a hand-held type.
FIG. 1 shows a right side view of a backpack blower apparatus as an embodiment of a power-operated work apparatus according to the present invention. The backpack blower apparatus 10 comprises a back carrier frame 11 for an operator to piggyback the apparatus, a blower unit 20 mounted on the back carrier frame 11 for blowing out air, and a blow-off tube (airflow tube) 27 connected to an air outlet duct 21 b of the blower unit 20 for blowing out air from the distal end of the blow-off tube 27. In the following description, the front side means the side where the operator stands to piggyback the back carrier frame 11 (i.e. the side of the back contacting member 12) with respect to the back carrier frame 11.
The back carrier frame 11 serves for the operator to piggyback the blower unit 20, and includes a back contacting member 12 to be disposed vertically along the back of the operator and a base member 13 extending horizontally rearward from the lower edge of the back contacting member 12, exhibiting an L-shaped side view. On the base member 13 is mounted the blower unit 20 via vibration absorbing (or nontransmittable) members such as coil springs or rubber bushings.
The blower unit 20 includes a volute casing 21, a centrifugal fan 22 rotatably supported in the volute casing 21, and an internal combustion engine 23 mounted to the volute casing 21 to drive the centrifugal fan 22. The volute casing 21 has a front wall formed with an air intake aperture 21 a (shown in FIG. 4) for sucking air into the volute casing by the centrifugal fan, and has an air outlet duct 21 b on the right side of the volute casing (shown in FIG. 1) for blowing out the air sucked in by the centrifugal fan through the air intake aperture 21 a. To the air outlet duct 21 b is communicatingly coupled a blow-off tube 27 so that the air blown out from the air outlet duct 21 b will be finally blown out from the distal end of the blow-off tube 27. The volute casing 21 has a rear wall, but the rear wall in this embodiment is not formed with an air outlet aperture for passing air backward, i.e. toward the engine space.
Within the volute casing 21 is rotatably supported the centrifugal fan 22, which includes a plurality of fan blades disposed on the front surface of the rotary disk. When the engine 23 drives the centrifugal fan 22, the rotating blades suck air around the front area of the rotary blades and impel the sucked air radially outward to the inner circumferential peripheral space of the volute casing to finally blow out from the air outlet duct 21 b.
The engine 23 is mounted to the rear wall of the volute casing 21 to rotate the centrifugal fan 22 with an engine casing 24 also mounted to the volute casing 21 for covering the engine 23. The engine 23 is of an air-cooled type and is cooled by the air introduced from the atmosphere into the engine casing 24. The engine casing 24 covers all around the engine 23 except the front side in the rear side of the volute casing 21. As shown in FIGS. 3-6, the engine casing 24 is provided with an air intake opening 24 a at the upper part thereof neighboring to the upper part of the volute casing 21 for introducing air from the atmosphere. The air intake opening 24 a is provided with a sound absorbing member 25 such as a rubber sponge to suppress wind noise of the air flowing through the air intake opening 24 a. Also as shown in FIGS. 2-6, the engine casing 24 is lined inside with a sound insulating member 26 made of foamed material such as polyurethane foam to inhibit the engine noise from leaking outside.
In the backpack blower apparatus 10 of the illustrated embodiment, the engine casing 24 is provided with an air suction passage 30 which communicates toward the front wall (inside the front wall, in the illustrated embodiment) of the volute casing 21 so that the air in the engine casing 24 is drawn to the front area of the volute casing 21, being sucked by the rotating fan blades of the centrifugal fan 22. As seen in FIGS. 2-6, the air suction passage 30 in the illustrated embodiment, is comprised of first through fourth air suction channels 31 (31 a, 31 b, 31 c, 31 d) formed on the surface of the sound insulating member 26 confronting the engine casing 24 and extending substantially vertically, and of first and second air suction ducts 32 (32 a, 32 b) connecting the air suction channels 31 to the front area (inside the front wall) of the volute casing 21.
As seen in FIGS. 2-6, the first through fourth air suction channels 31 a-31 d open into the engine casing 24, with the openings 31 a 1-31 d 1 located in the area containing exhaust heat from the engine 23. The opening 31 a 1 of the first air suction channel 31 a is located at the position confronting the intake port and the carburetor of the engine 23. The opening 31 b 1 of the second air suction channel 31 b is located at the position confronting the ignition plugs of the engine 23. The opening 31 c 1 of the third air suction channel 31 c is located at the position confronting the exhaust port of the engine 23. The opening 31 d 1 of the fourth air suction channel 31 d is located at the position confronting the muffler (silencer) of the engine 23. The openings 31 a 1-31 d 1 of the respective air suction channels 31 a-31 d are formed respectively across the areas containing exhaust heat from the engine 23 as seen from the air intake opening 24 a, so that the air introduced from the atmosphere through the air intake opening 24 a will flow through the areas containing exhaust heat from the engine 23. As seen in FIG. 2, the second air suction channel 31 b joins the first air suction channel 31 a at the vertically middle point so that the air introduced from the opening 31 b 1 of the second air suction channel 31 b will flow together with the air introduced from the opening 31 a 1 of the first air suction channel 31 a, while the fourth air suction channel 31 d joins the third air suction channel 31 c at the vertically middle point so that the air introduced from the opening 31 d 1 of the fourth air suction channel 31 d will flow together with the air introduced from the opening 31 c 1 of the third air suction channel 31 c.
The air suction ducts 32 (32 a, 32 b) are made of tubular members, respectively, and communicate air in the lower portion of the engine casing 24 to the lower front portion of the volute casing circumventing outside the lower part wall of the volute casing 21. The air suction ducts 32 are to draw the air in the engine casing 24 sucked through the openings 31 a 1-31 d 1 of the air suction channels 31 a-31 d, respectively, to the front portion of the volute casing 21. The air suction duct 32 a has an airflow inlet port which is connected to the lower end of the first air delivery channel 31 a, and has an airflow outlet port which is connected to the lower front portion of the volute casing 21. The air delivery duct 32 b has an airflow inlet port which is connected to the lower end of the third air delivery channel 31 c, and has an airflow outlet port which is connected to the lower front portion of the volute casing 21. In the Figures, is shown a fuel tank 34 also.
Hereinbelow will be described how the backpack blower apparatus 10 configured as above works. As the operator starts the engine 23, the centrifugal fan 22 rotates, and the air in the atmosphere is sucked through the air intake aperture 21 a in the front wall of the volute casing 21 into the volute casing 21, and the impelled air is blown out from the air outlet duct 21 b, flows through the blow-off tube 27, and is finally blown out from the distal end of the blow-off tube 27. As the centrifugal fan 22 sucks air from the atmosphere through the air intake aperture 21 a in the front wall of the volute casing 21, the front area (including inside the front wall) of the volute casing 21 shows a negative pressure and the air in the engine casing 24 is drawn to the front area of the volute casing 21 through the air suction passage 30 constituted by the air suction channels 31 (31 a-31 d). More specifically, as shown by the arrows in FIGS. 3-6, the air in the atmosphere is introduced through the air intake opening 24 a formed in the upper portion of the engine casing 24 into the engine casing 24, and the air flows through the area containing exhaust heat of the engine 23 and flows into the air suction channels 31 through the openings 31 a 1-31 d 1, and is drawn to the front area of the volute casing 21 via the air suction channels 31 and the air suction ducts 32. During the above process, the air introduced into the engine casing 24 flows by the heated part of the engine 23 and carries off the heat from the engine 24.
With the backpack blower apparatus 10 as configured above, the engine 23 drives and rotates the centrifugal fan 22, which sucks air through the air intake aperture 21 a and blows out air from the air outlet duct 21 b. As the rotating fan blades suck air, the front area in the volute casing exhibits a negative pressure. Then, the air in the engine casing 24 is sucked to the front area of the volute casing 24 via the air suction passage 30. In this process, the air in the vicinity of the engine 23 within the engine casing 24 is sucked to the front area of the volute casing 24 via the air suction passage 30.
According to this embodiment, in particular, the air in the atmosphere is sucked into the engine casing 24 through the air intake aperture 24 a, while the air within the engine casing 24 is sucked toward the front area of the volute casing 21. Thus, the air from the atmosphere flows around the engine 23 and cools the engine 23. There is no need of the atmospheric air sucked into the volute casing 21 being partly blown out into the engine casing 24 from the volute casing 21, and the entire air sucked in the volute casing 21 is used for the airflow into the blow-off tube 27, and the air blowing efficiency by the fan will not be decreased and there will be no need of a complicated structure for the volute casing such as a two-stage structure as in the aforementioned prior art apparatus to compensate a possible loss.
Among prior art blower apparatuses, there is a model that comprises a volute casing having an air intake aperture in the front wall and in the rear wall of the volute casing and comprises a centrifugal fan having fan blades on both the front surface and the rear surface of the rotating disk within the volute casing so that the centrifugal fan sucks air also from the rear side of the volute casing, i.e. from inside the engine casing for cooling the engine with airflow therein, with the air in the atmosphere being introduced into the engine casing through an air intake opening of the engine casing for cooling the engine. With such a prior art model, however, the production cost of the centrifugal fan having fan blades on both the front surface and the rear surface of the rotating disk would be accordingly high. On the contrary, with the above described embodiment, the volute casing 21 has an air intake aperture 21 a only in the front wall thereof and the centrifugal fan 22 has fan blades on the front surface of the rotating disk, as the air within the engine casing 24 is sucked toward the front area of the volute casing 21 via the air suction passage 30 for cooling the engine 23. This would decrease the production cost of the centrifugal fan 22 as compared with the mentioned prior art model.
The inner surface of the engine casing 24 is lined with the sound insulating member 26 in order to prevent the engine noise from leaking outside, wherein the sound insulating member 26 is formed with the air suction channels 31 a-31 d on the surface confronting the engine casing 24, and the spaces formed by the air suction channels 31 a-31 d between the sound insulating member 26 and the engine casing 24 constitute a part of the air suction passage 30. The air suction channels 31 a-31 d have openings 31 a 1-31 d 1, respectively, which are disposed at the positions confronting the heat exhausting portion of the engine 23. According to this structure, the air introduced into the engine casing 24 through the air intake opening 24 a from the atmosphere flows near the heat exhausting portion of the engine 23 before entering the air suction channels 31 a-31 d. Thus, the heat exhausting portion of the engine 23 is efficiently cooled by the air from the atmosphere. While in the above illustrated embodiment the air suction passage 30 is formed between the engine casing 24 and the sound insulating member 26 by the air suction channels 31 disposed on the surface of the sound insulating member 26 confronting the engine casing 24, the air suction passage 30 may alternatively be formed by a cylindrical bore disposed through the sound insulating member 26. In such a configuration, the opening of the cylindrical bore may preferably be arranged at positions confronting the heat exhausting portion of the engine 23 in the engine casing 24 to ensure the above mentioned air-cooling function.
Further alternatively, the inlet port of the air suction duct 32 may be coupled to the space below the engine 23 as shown in FIG. 7, omitting the air suction channels 31. In this embodiment, the air suction passage 30 is constituted by the air suction duct 32 only. As the inlet port of the air suction duct 32 is located across the engine 23 from the air intake opening 24 a, the air introduced into the engine casing 24 through the air intake opening 24 a from the atmosphere flows near the engine 23 to cool the engine 23 efficiently before entering the air suction duct 32.
While in the above mentioned embodiment, the space within the engine casing 23 is coupled with the space inside the front wall of the volute casing 21 via the air suction duct 32, the configuration for the air suction passage 30 may be different as shown in FIG. 8. In this embodiment, an air entrance 24 b is provided below the front part of the engine within the engine casing 24 penetrating the sound insulating member 26, and a bottom cover member 33 is provided connecting the lower front part of the engine casing 24 and the lower front part of the volute casing 21 and covering the lower wall of the volute casing 21 with some space inbetween, so that the space covered by the bottom cover member 31 communicates with the space below the front part of the engine 23 and with the space inside the front wall of the volute casing 21, thereby constituting the air suction passage 30.
While in the heretofore mentioned embodiments, the air intake opening 24 a is provided at the upper part of the engine casing 24 for introducing air from the atmosphere, the configuration for introducing air into the engine casing 24 may be different as shown in FIG. 9. In this embodiment, an air outlet aperture 21 c is formed in the rear wall of the volute casing 21 for introducing into the space within the engine casing 24 a part of the air sucked through the air intake aperture 21 a of the volute casing 21, so that the air introduced from the outlet aperture 21 c will flow around the engine 23 before flowing through the air suction passage 30 to the front area of the volute casing 21. The engine 23 will be efficiently cooled by the air flowing around the engine 23. While, in this embodiment, a part of the air sucked from the air intake aperture 21 a of the volute casing 21 flows out into the space within the engine casing 24, the air is drawn back to the front area of the volute casing 21 via the air suction passage 30, and thus a decrease in the air impelling efficiency will be minimized. So, there will be no need of providing a complicated two-stage structure of the volute casing unlike the prior art apparatus mentioned before. In the case of the embodiment shown in FIG. 9, the configuration of omitting air suction channels as shown in FIG. 7 or the configuration of providing a bottom cover member as shown in FIG. 8 in place of the air suction ducts may also be employed.
In the above described embodiments, a part of the air suction passage 30 is constituted by the air suction ducts 32 or by the space under the engine casing 24 and the volute casing 21 covered by the bottom cover member so that the air in the lower part within the engine casing 24 is drawn to the lower front part of the volute casing 21 passing around the lower circumferential wall of the volute casing 21. The present invention is not necessarily limited to such configurations. A part of the air suction passage 30 may be constituted by an air suction duct or a cover member provided in the upper portion of the engine casing 24 or in the side portion of the engine casing 24 so that the air in the upper portion or in the side portion within the engine casing 24 may be drawn to the front area of the volute casing 21 passing around the upper portion or the side portion of the outer wall of the volute casing 21. In such a configuration, the air intake opening 24 a of the engine casing 24 and the entrance to the air suction passage 30 may preferably be positioned in such a way in which the air intake opening 24 a be located across the engine 23 or at least a part of the engine 23 from the entrance to the air suction passage 30 so that the air introduced from the air intake opening 24 a flows around the engine 23 before drawn by the air suction passage to the front area of the volute casing 21. And similar merits will be obtained.
While the invention has been described about embodiments of a power-operated backpack blower apparatus 10, the invention is applicable to a power-operated hand-held blower apparatus. The invention is also applicable to a backpack dust collector or a hand-held dust collector. The same merits will be enjoyed.

Claims

What is claimed is:

1. A power-operated air blowing work apparatus comprising:

a volute casing including a centrifugal fan installed therein and having a front wall formed with an air intake aperture for sucking air from an atmosphere into the volute casing by the centrifugal fan;

an engine mounted to the volute casing in a rear side of the volute casing and connected to the centrifugal fan for rotating the centrifugal fan;

an engine casing covering the engine from behind the engine in the rear side of the volute casing, and

an air suction passage communicating from inside the engine casing toward inside the front wall of the volute casing for drawing air in the engine casing toward inside the front wall of the volute casing.

2. A power-operated air blowing work apparatus as claimed in claim 1, wherein the engine casing is formed with an air intake opening for introducing air from an atmosphere into the engine casing, wherein the air suction passage draws the introduced air in the engine casing toward inside the front wall of the volute casing.

3. A power-operated air blowing work apparatus as claimed in claim 1, wherein the volute casing has a rear wall formed with an air outlet aperture for directing a part of the air sucked into the volute casing through the air intake aperture to inside the engine casing through the air outlet aperture, wherein the air suction passage draws the directed air in the engine casing toward inside the front wall of the volute casing.

4. A power-operated air blowing work apparatus as claimed in claim 1, wherein the engine casing is lined inside with a sound insulating member for inhibiting engine noise from leaking outside, wherein the sound insulating member is formed with a channel on the surface thereof confronting the engine casing, thereby constituting a part of the air suction passage between the engine casing and the sound insulating member.

5. A power-operated air blowing work apparatus as claimed in claim 1, wherein the engine casing is lined inside with a sound insulating member for inhibiting engine noise from leaking outside, wherein the sound insulating member itself is provided with a cylindrical bore disposed therein to constitute a part of the air suction passage through the sound insulating member.

6. A power-operated air blowing work apparatus as claimed in claim 1, wherein the air suction passage is formed from behind the volute casing, around outside the volute casing and toward inside the front wall of the volute casing.