US20110146023A1

US20110146023A1 - Backpack power tool

Info

Publication number: US20110146023A1
Application number: US12/967,426
Authority: US
Inventors: Kenji Wada; Yuki MIZUKOSHI; Ryo Sunazuka
Original assignee: Makita Corp
Current assignee: Makita Corp
Priority date: 2009-12-18
Filing date: 2010-12-14
Publication date: 2011-06-23
Also published as: CN102102683A; JP2011127541A

Abstract

A vibration proofing property is provided in a backpack power tool. A backpack power tool has a backpack carrying part 103 which can be carried on user's back, and a tool body 105 mounted on the backpack carrying part 103. Elastic members 133, 135 are provided which connect the tool body 105 and a body support region 113 of the backpack carrying part 103. The elastic members 133, 135 deform by receiving the weight of the tool body 105 and vibration which is caused in the tool body 105 by rotation of the rotator 123, and thereby reduce transmission of the vibration from the tool body 105 to the backpack carrying part 103.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a backpack power tool which is carried on user's back and used for a predetermined working operation.
2. Description of the Related Art
As an example of a backpack power tool, Japanese non-examined laid-open Patent Publication No. 2008-2310 discloses a backpack power blower which is used for cleaning operation of gathering fallen leaves or cut grass. The known backpack power blower mainly includes a backpack carrying part to be carried on user's back, and a tool body having an internal combustion engine and a blower which is driven by the internal combustion engine. The tool body is mounted on the backpack carrying part via a coil spring.
In the above-described known backpack power blower, vibration caused in tool body when driving the internal combustion engine is prevent by the coil spring from being transmitted to the backpack carrying part. In the tool body, however, not only the driving of the internal combustion engine causes vertical vibration, but rotation of the blower causes vibration. The vibration caused by such rotation is not particularly considered in the known art.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to improve a vibration proofing property in a backpack power tool.
Above-described object can be achieved by the claimed invention. According to the invention, a representative backpack power tool is provided which includes a backpack carrying part, a tool body, a rotator, a driving mechanism, a back contact region, a body support region, and an elastic member. The backpack carrying part is carried on user's back. The tool body is mounted on the backpack carrying part. The rotator is provided as a component of the tool body. The driving mechanism is provided as a component of the tool body. The driving mechanism rotationally drives the rotator in a vertical plane. The back contact region forms part of the backpack carrying part. The back contact region contacts the back of the user. The body support region forms part of the backpack carrying part. The body support region extends transversely from the back contact region. The elastic member is disposed between the tool body and the body support region. The elastic member connects the tool body and the body support region. The “backpack power tool” according to this invention typically represents a backpack power blower for use in cleaning operation of blowing and gathering fallen leaves or cut grass, but it may also widely include a backpack bush cutter for cutting grass or mowing lawn, and a backpack power spray for spraying agricultural chemicals or herbicide.
According to the invention, the elastic member deforms by receiving the weight of the tool body and vibration which is caused in the tool body by rotation of the rotator. Thus, the elastic member reduces transmission of the vibration from the tool body to the backpack carrying part. The “rotator” according to the invention typically represents a blower, and it is preferably arranged to rotate in a vertical plane. Further, the “driving mechanism” typically represents an internal combustion engine, but it also suitably includes an electric motor.
According to this invention, not only as for vibration caused by driving of the driving mechanism, but as for vibration caused in the direction of rotation (the circumferential direction) by rotation of the rotator, transmission of the vibration from the tool body to the backpack carrying part can be reduced.
According to a further aspect of this invention, the elastic member may comprise a coil spring and the coil spring deforms according to spring constants of the coil spring in a compressing direction and a shearing direction (direction of oblique displacement) and thereby reduces transmission of vibration of the tool body from the tool body to the backpack carrying part. If the elastic member is formed, for example, of rubber and arranged to receive vibration by utilizing its deformation in the shearing direction, its vibration absorbing effect can be enhanced, but its durability may be decreased. According to this invention, by using the coil spring, the vibration absorbing effect can be enhanced by utilizing its deformation which is caused according to the spring constant in the shearing direction, while the durability can be maintained.
According to a further aspect of this invention, the coil spring is arranged such that its central axis extends obliquely toward an axis of rotation of the rotator with respect to the vertical direction when the user carries the backpack carrying part on the back. According to this aspect, by such oblique arrangement, the coil spring can rationally receive vibration caused in the direction of rotation by rotation of the rotator while receiving the weight of the tool body, by deforming in the compressing direction and the shearing direction.
According to a further aspect of this invention, in the construction in which the central axis of the coil spring extends obliquely toward the axis of rotation of the rotator, at least two coil springs may be arranged on right and left sides of a vertical line passing through (crossing) the axis of rotation of the rotator. According to this invention, the coil spring can be arranged to efficiently proof vibration in consideration of the balance of vibration.
According to a further aspect of this invention, the rotator may be arranged on a near side with respect to the back contact region of the backpack carrying part which contacts the user's back, and the driving mechanism maybe arranged on a far side. Further, a rotator housing part may be provided as a component of the tool body and has a circumferential surface for housing the rotator. The elastic member may be disposed between the circumferential surface of the rotator housing part and the body support region of the backpack carrying part. According to this aspect, the elastic member can be arranged closer to the back contact region, so that vibration transmitted to the backpack carrying part can be effectively avoided from being amplified in the body support region and transmitted to the back of the user.
According to a further aspect of this invention, the elastic member may be arranged with reference to the position of a center of gravity of the tool body. The manner in which the elastic member is “arranged with reference to the position of a center of gravity” in this invention represents the manner in which the elastic member is arranged in a vertical plane containing the center of gravity. According to this aspect, the vibration proofing function can be performed in a balanced state in the fore-and-aft direction and the lateral direction with the backpack power tool carried on the back of the user.
According to a further aspect of this invention, the rotator comprises an impeller of the blower, and the driving mechanism comprises an internal combustion engine. According to this aspect, in the backpack power blower for use in cleaning operation of gathering fallen leaves or cut grass, not only as for vibration caused by driving of the internal combustion engine, but for vibration caused in the direction of rotation by rotation of the impeller of the blower, transmission of the vibration from the tool body to the backpack carrying part can be reduced.
According to the invention, a vibration proofing property is improved in a backpack power tool.
Other objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an entire backpack power tool according to an embodiment of the invention.

FIG. 2 is a side view of the backpack power tool.

FIG. 3 is a vertical section of the backpack power tool when viewed from the rear.

FIG. 4 is a perspective view showing the backpack power tool in use.

DETAILED DESCRIPTION OF THE INVENTION

Each of the additional features and method steps disclosed above and below may be utilized separately or in conjunction with other features and method steps to provide and manufacture improved backpack power tool and method for using such backpack power tool and devices utilized therein. Representative examples of the present invention, which examples utilized many of these additional features and method steps in conjunction, will now be described in detail with reference to the drawings. This detailed description is merely intended to teach a person skilled in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Only the claims define the scope of the claimed invention. Therefore, combinations of features and steps disclosed within the following detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe some representative examples of the invention, which detailed description will now be given with reference to the accompanying drawings.
A representative embodiment of the invention is now described with reference to FIGS. 1 to 4. In this embodiment, a backpack power blower is described as a representative embodiment of a backpack power tool according to the invention. As shown in FIGS. 1 and 2, a backpack power blower 101 mainly includes a backpack carrier 103 which can be carried by a user on the back, and a power blower 105 which is mounted on the backpack carrier 103. The backpack carrier 103 and the power blower 105 are features that correspond to the “backpack carrying part” and the “tool body”, respectively, according to the invention.
The backpack carrier 103 is generally L-shaped in side view and includes a back pad part (back contact part) 111 which extends vertically and contacts the back of the user when carried by the user on the back, and a base 113 which extends horizontally from the lower end of the back contact part 111 and on which the power blower 105 is mounted. Each of the back contact part 111 and the base 113 has a frame structure formed by bending a pipe into a generally square shape. The back contact part 111 and the base 113 are features that correspond to the “back contact region” and the “body support region”, respectively, according to the invention. As shown in FIG. 5, the backpack carrier 103 further includes a backpack carrying band 115 and is carried on the back of the user via the backpack carrying band 115. The backpack carrying band 115 is designed to be detachable from the back contact part 111. In the following description, for the sake of convenience of explanation, the side of the back contact part 111 (the left side as viewed in FIG. 2) is taken as the front and the extending side (the right side as viewed in FIG. 2) of the base 113 extending from the end of the back contact part 111 as the rear.
The power blower 105 mainly includes a blower 121 and an internal combustion engine 131 that rotationally drives the blower 121. The internal combustion engine 131 is a feature that corresponds to the “driving mechanism” according to this invention. As shown in FIG. 3, the blower 121 includes an impeller (hereinafter referred to as a blower fan) 123 and a housing 125 that houses the blower fan 123. The blower fan 123 and the housing 125 are features that correspond to the “rotator” and the “rotator housing part”, respectively, in this invention.
An air blowoff pipe 128 is connected to an air outlet port 125 a formed in the housing 125, via an elbow pipe 126 and a bellows-like flexible pipe 127. As shown in FIGS. 1 and 2, an operating member in the form of a handgrip 129 for operating the blowoff pipe 128 is provided on the blowoff pipe 128. By holding the handgrip 129 and operating a control member of the internal combustion engine 131 and the blowoff pipe 128, the user can perform an operation of blowing and gathering fallen leaves or cut grass by air which is blown out through an outlet port 128 a of the blowoff pipe 128.
As shown in FIGS. 1 and 2, the blower 121 and the internal combustion engine 131 are arranged one behind the other, or with the internal combustion engine 131 behind the blower 121. At least outer shell components (housings) of the blower 121 and the internal combustion engine 131 are formed in one piece.
A vibration proofing structure of the power blower 105 which is mounted on the backpack carrier 103 is now described. The vibration proofing structure according to this embodiment mainly includes a plurality of (two) coil springs 133, 135 disposed between the base 113 of the backpack carrier 103 and the power blower 105. The coil springs 133, 135 are features that correspond to the “elastic member” in this invention. The coil springs 133, 135 deform by receiving the weight of the power blower 105 and vibration caused in the power blower 105 and can thereby reduce or prevent transmission of the vibration from the power blower 105 to the backpack carrier 103.
In this embodiment, the two coil springs 133, 135 deform according to the spring constants in the compressing direction and in the shearing direction of the coil springs and thereby reduce or prevent transmission of vibration which is caused when the power blower 105 is driven, to the backpack carrier 103. Specifically, as shown in FIG. 3, the two coil springs 133, 135 are arranged in symmetry with respect to a vertical line P extending vertically through (across) a rotary shaft 123 a of the blower fan 123 and arranged such that the central axes of the coil springs 133, 135 extend obliquely toward the axis of rotation (the rotary shaft 123 a) of the blower fan 123 (such that the central axes form an inverted V-shape when viewed from the front or the rear). By such arrangement, the right and left coil springs 133, 135 receive vertical vibration caused by driving of the internal combustion engine 131 and vibration caused in the direction of rotation (the circumferential direction) by rotation of the blower fan 123 of the blower 121 while supporting the weight of the power blower 105 and thereby deform in the compressing direction and in the shearing direction (the direction of oblique displacement). By such deformation, transmission of the vibration from the power blower 105 to the backpack carrier 103 can be reduced or prevented.
The right and left coil springs 133, 135 are disposed between the upper surface of the base 113 of the backpack carrier 103 and the lower surface of the circumferential surface region of the housing 125 which houses the blower fan 123. The coil springs 133, 135 are fastened at one axial end to the upper surface of the base 113 via spring receiving bracket 133 a, 135 a and at the other end to the lower surface of the housing 125 via spring receiving bracket 133 b, 135 b.
Further, one coil spring (not shown) is disposed generally in the middle in the lateral direction (on a vertical line passing through (crossing) the axis of rotation of the blower fan 123) between a rear surface of an upper end portion of the back contact part 111 of the backpack carrier 103 and a front surface of an upper end portion of the housing 125 of the blower 121 and arranged such that the central axis of the coil spring extends generally horizontally in the fore-and-all direction. Specifically, the power blower 105 is supported at two points on the base 113 and one point on the back contact part 111 by the coil springs 133, 135, and it is held contactless at any other points with respect to the backpack carrier 103.
In this embodiment, the power blower 105 is mounted on the backpack carrier 103 via the coil springs 133, 135, and the coil springs 133, 135 deform by receiving the weight of the power blower 105 and vibration caused in the direction of rotation by rotation of the blower fan 123 and can thereby prevent transmission of the vibration from the power blower 105 to the backpack carrier 103. Further, in this embodiment, the coil springs 133, 135 are arranged such that the central axes of the coil springs 133, 135 extend obliquely toward the axis of rotation of the blower fan 123. With this arrangement, the coil springs 133, 135 can deform in the compressing direction and in the shearing direction and thereby absorb vertical vibration caused by driving of the internal combustion engine 131 and vibration caused in the direction of rotation by rotation of the blower fan 123, so that transmission of the vibration from the power blower 105 to the backpack carrier 103 can be reduced.
Further, in this embodiment, it is constructed such that vibration is absorbed by deformation of the coil springs 133, 135 in the compressing direction and in the shearing direction. If the vibration-proofing member is formed, for example, of rubber and arranged to receive vibration by utilizing its deformation in the shearing direction, its vibration absorbing effect can be enhanced, but its durability may be decreased. According to this invention, by using the coil springs 133, 135, the vibration absorbing effect can be enhanced by utilizing deformation which is caused according to the spring constant in the shearing direction, while the durability can be maintained.
In this embodiment, the two coil springs 133, 135 are arranged in symmetry with respect to the vertical line P extending through the axis of rotation of the blower fan 123. Therefore, the weight of the power blower 105 and vibration caused by driving the power blower 105 can be received in a balanced manner in the lateral direction. Such a symmetrical arrangement is effective, for example, if the center of gravity of the power blower 105 lies on the vertical line P. Actually, however, the center of gravity of the power blower 105 may be displaced to the right or the left off the vertical line P. Therefore, in such a case, preferably, the two coil springs 133, 135 are arranged in a position to achieve right and left weight balance with respect to the vertical line P, so that efficient vibration proofing can be realized.
Further, vibration is not always caused in the same manner on the right and left sides of the vertical line P. For example, the manner of vibration on the side having the air outlet port 125 a differs from that on the other side not having the air outlet port 125 a. Further, the direction of vibration acting on the left coil spring 133 differs from that on the right coil spring 135 according to the direction of rotation of the blower fan 123 (In FIG. 3, because the blower fan 123 rotates clockwise, vibration acts upward on the left coil spring 133 and downward on the right coil spring 135). Therefore, preferably, the right and left coil springs 133, 135 are adjusted in position and angle and disposed such that efficient vibration proofing can be achieved by receiving vibration evenly on the right and left sides.
Further, in this embodiment, the blower 121 and the internal combustion engine 131 are arranged one behind the other, or with the internal combustion engine 131 behind the blower 121, and the circumferential surface of the housing 125 of the blower 121 is supported by the coil springs 133, 135. With this construction, the distance from the back contact part 111 of the backpack carrier 103 to the coil springs 133, 135 can be made shorter, for example, compared with a construction in which the coil springs 133, 135 support the internal combustion engine 131. Therefore, vibration transmitted to the base 113 of the backpack carrier 103 can be avoided from being amplified at the base 113 and transmitted to the back of the user, and heat generated in the internal combustion engine 131 can also be avoided from adversely affecting the user.
The invention is not limited to the above-described embodiment, but can be appropriately modified or changed. For example, in this embodiment, the circumferential surface of the housing 125 of the blower 121 is supported by the coil springs 133, 135, but it may be modified such that the coil springs 133, 135 are arranged in symmetry with respect to a vertical line passing through the center of gravity of the power blower 105. In this case, the weight of the power blower 105 and vibration caused by driving the power blower 105 can be received not only in the lateral direction but in the fore-and-aft direction in a balanced manner.
Further, in this embodiment, the base 113 is formed to extend rearward from the lower edge of the back contact part 111, and the power blower 105 is mounted on the upper surface of the base 113. It may however be modified, for example, such that a support part is formed to extend rearward from the upper edge of the back contact part 111 and the power blower 105 is hung and supported via the coil springs 133, 135 with respect to the support part. In this case, preferably, the coil springs 133, 135 are arranged in symmetry with respect to the vertical line P passing through the axis of rotation of the blower fan 123 such that the central axes of the coil springs extend obliquely toward each other to form a V-shape when viewed from the front or the rear. Further, the means for driving the blower 121 may be an electric motor in place of the internal combustion engine 131.
Further, in this embodiment, the backpack power blower is described as a representative example of the backpack power tool according to the invention. However, the invention can be applied not only to the backpack power blower, but to a backpack bush cutter for cutting grass or mowing lawn, or a backpack power sprayer for spraying agricultural chemicals or herbicide.

DESCRIPTION OF NUMERALS

101 backpack power blower
103 backpack carrier (backpack carrying part)
105 power blower (tool body)
111 back contact part (back contact region)
113 base (body support region)
115 backpack carrying band
121 blower
123 blower fan (rotator)
123 a rotary shaft
125 housing
125 a outlet port
126 elbow pipe
127 flexible pipe
128 blowoff pipe
128 a outlet port
129 handgrip
131 internal combustion engine (driving mechanism)
133 coil spring (elastic member)
135 coil spring (elastic member)
133 a, 133 b spring receiving bracket
135 a, 135 b spring receiving bracket

Claims

1. A backpack power tool comprising:

a backpack carrying part carried on user's back,

a tool body mounted on the backpack carrying part,

a rotator provided as a component of the tool body,

a driving mechanism provided as a component of the tool body to rotationally drive the rotator in a vertical plane,

a back contact region which forms part of the backpack carrying part and contacts the back of the user,

a body support region which forms part of the backpack carrying part and extends transversely from the back contact region, and

an elastic member which is disposed between the tool body and the body support region and connects the tool body and the body support region,

wherein the elastic member deforms by receiving the weight of the tool body and vibration which is caused in the tool body by rotation of the rotator, and thereby reduces transmission of the vibration from the tool body to the backpack carrying part.

2. The backpack power tool according to claim 1, wherein the elastic member comprises a coil spring, and the coil spring deforms according to spring constants of the coil spring in a compressing direction and a shearing direction and thereby reduces transmission of vibration of the tool body from the tool body to the backpack carrying part.

3. The backpack power tool according to claim 2, wherein t the coil spring is arranged such that its central axis extends obliquely toward an axis of rotation of the rotator with respect to a vertical direction when the user carries the backpack carrying part on the back.

4. The backpack power tool according to claim 3, wherein two coil springs are respectively arranged on right and left sides of a vertical line passing through the axis of rotation of the rotator.

5. The backpack power tool according to claim 1, wherein the rotator is arranged on a near side with respect to the back contact region of the backpack carrying part which contacts the user's back, and the driving mechanism is arranged on a far side, wherein the backpack power tool further includes a rotator housing part provided as a component of the tool body and having a circumferential surface for housing the rotator, and wherein the elastic member is disposed between the circumferential surface of the rotator housing part and the body support region.

6. The backpack power tool according to claim 1, wherein the elastic member is arranged with reference to the position of a center of gravity of the tool body.

7. The backpack power tool according to claim 1, wherein the rotator comprises an impeller of the blower, and the driving mechanism comprises an internal combustion engine.