JP6713877B2 - Cutting blade - Google Patents

Description

The present invention relates to a resin plate-shaped cutting blade attached to a front end of an operating rod of a brush cutter, and a cutting blade attached to a rotary shaft of a lawn mower.

Patent Documents 1 and 2 disclose a rotary blade unit used in a brush cutter for cutting grass, grass and the like. The rotary blade unit used in this brush cutter is detachably attached to the front end of the operating rod that is gripped and used by the operator, and the rotary blade unit is rotatably attached to the front end of the operating rod. A substrate and a cutting blade swingably supported by the rotating substrate are provided. In this rotary blade unit, when the rotating substrate is rotated by driving the electric motor of the brush cutter, the cutting blade opens in the centrifugal direction by the centrifugal force, and the cutting blade rotates in the opened state together with the rotating substrate. When the rotary blade unit is rotated in this manner and the rotary blade unit is moved horizontally along the ground by the operation of the operating rod, grass or the like is cut and cut off by the cutting blade that rotates together with the rotary substrate.

JP, 2005-146771, A WO99/30552

The rotary blade unit described in Patent Document 1 described above uses a metal sheet metal member including a cutting blade. In order to rotate the rotary blade unit composed of a metal plate member made of metal, it was preferable to use a brush cutter having an engine having a high driving force or a large electric motor as a drive source. In recent years, a brush cutter that uses a small electric motor as a drive source to reduce noise has been developed. In a brush cutter that uses a small electric motor as a drive source, a lightweight resin material is used. It is preferable to use the rotary blade unit, which has a reduced load on the electric motor. When a small electric motor was adopted for the brush cutter to reduce noise, the wind noise generated when the cutting blade of the rotary blade unit rotated was noticeable due to the reduction of the driving noise of the electric motor.

Further, since the blade portion of the cutting blade of Patent Document 2 has a corrugated waveform in which the protrusion and the recess are continuous with the same width, an object to be cut such as grass is easily caught by the protrusion. ing. However, since too many protrusions are formed on the corrugated blade, many objects such as grass are caught by more protrusions than necessary, and a large load is placed on the electric motor that rotates the rotary blade unit. There is a problem that power consumption increases due to the occurrence. An object of the present invention is to provide a cutting blade that reduces wind noise during rotation as much as possible and that does not increase power consumption by catching an object to be cut such as grass more than necessary.

In order to solve the above problems, the present invention is a cutting blade for resin mowing that is detachably attached to a rotating body and extends in a plate shape in the centrifugal direction of the rotating body, and the cutting blade is directed outward in the centrifugal direction. The present invention provides a cutting blade, which has a shape curving rearward in the rotational direction as it goes to, and has a spindle-shaped cross-sectional shape in the rotational direction of the cutting blade such that a central portion in the rotational direction swells.

In the cutting blade configured as described above, since the cross-sectional shape in the rotation direction of the cutting blade is a spindle shape so that the central portion in the rotation direction swells, it is possible to improve the flow of air passing around the cutting blade. As a result, it is possible to reduce wind noise when the cutting blade rotates, and reduce the load on the prime mover that rotates the cutting blade.

Further, in order to solve the above problems, the present invention is a cutting blade for resin mowing, which is detachably attached to a rotating body and extends in a plate shape in the centrifugal direction of the rotating body, and the cutting blade is in the centrifugal direction. As it goes to, the blade has a curved shape that is curved backward in the rotation direction of the rotating body, and the blade portion formed on the front side in the rotation direction of the cutting blade is formed in a corrugated shape in which protrusions and recesses are alternately continuous in the centrifugal direction. The present invention provides a cutting blade, characterized in that the width thereof is formed to be narrower than the width of the recess.

In the cutting blade configured as described above, since the blade portion formed on the front side in the rotation direction of the cutting blade is formed in a waveform in which the protrusions and the recesses are alternately continuous in the centrifugal direction, the object to be cut such as grass is It can be easily caught by being caught by the protrusion and the width of the protrusion is made narrower than the width of the recess, so the number of protrusions of the corrugated blade can be relatively reduced, and the corrugated blade The protrusions of the parts are prevented from catching grass or other objects to be cut more than necessary, and the load on the drive source for rotating the cutting blade can be reduced.

Further, in order to solve the above-mentioned problems, the present invention is a cutting blade for resin mowing, which is detachably attached to a rotating body and extends in a plate shape in the centrifugal direction of the rotating body, and the rotation direction of the cutting blade. Also, the present invention provides a cutting blade characterized in that a small protrusion that reduces the vortex of air passing therethrough is formed on a surface orthogonal to the centrifugal direction.

In the cutting blade configured as described above, since the small protrusions that reduce the vortex of the passing air are formed on the surface orthogonal to the rotation direction and the centrifugal direction of the cutting blade, the air passing around the cutting blade is small. As a result of turbulent flow, large vortices are no longer generated due to diffusion, and wind noise when the cutting blade rotates can be reduced. In such a cutting blade, the cutting blade is also applied to a shape that is curved backward in the rotational direction of the rotary body as it advances in the centrifugal direction.

It is a perspective view of the brush cutter which attached the rotary blade unit which uses the cutting blade of this invention. It is a top view of a rotary blade unit, and is a top view (a) of the position where the cutting blade opened, and a plan view (b) of the position where the cutting blade is closed to the rotating body side. It is a top view of a cutting blade.

An embodiment in which the cutting blade of the present invention is attached to a brush cutter will be described below with reference to the accompanying drawings. As shown in FIG. 1, the brush cutter 10 is provided with a slender cylindrical operation rod 11 extending in the front-rear direction, a motor unit 12 provided at a front end portion of the operation rod 11, and a rear end portion of the operation rod 11. And a control unit 14.

The motor unit 12 includes a motor housing 13 fixed to the front end of the operating rod 11, and an electric motor (not shown) provided in the motor housing 13. A drive shaft (not shown) rotated by driving the electric motor is provided so as to project downward from the motor housing 13. A brushless DC motor is adopted as the electric motor of this embodiment, and the drive noise of the electric motor is lower than that when an engine or an AC motor is adopted as another drive source. A rotary blade unit 20 having a cutting blade 22 described below is detachably attached to the drive shaft.

The control unit 14 includes a control housing 15 fixed to the rear end of the operating rod 11, and a controller for controlling the operation of the electric motor in the control housing 15. A battery pack 16 for supplying electric power to the electric motor is detachably attached to the rear end of the control housing 15, and the battery pack 16 is connected to the electric motor by an electric cord arranged in the operating rod 11. .. A substantially annular operation handle 17 to be gripped by a worker is provided at an intermediate portion of the operation rod 11 in the front-rear direction, and a grip handle 18 having a larger outer diameter than the operation rod 11 is provided at the rear portion of the operation rod 11. There is. The grip handle 18 is provided with a switch 19 for driving the electric motor, and the electric motor is driven by receiving power from the battery pack 16 when the switch 19 is turned on.

As shown in FIG. 2, the rotary blade unit 20 is for cutting an object to be cut such as grass or turfgrass that grows on the ground, and a substantially disk-shaped rotating body 21 fixed to a drive shaft of an electric motor, It is provided with three cutting blades 22 which are swingably fixed to the rotating body 21. The rotary body 21 and the cutting blade 22 of the rotary blade unit 20 are formed by molding a lightweight resin material, and the rotary blade unit 20 is designed to reduce the load on the electric motor as compared with a metal blade. .. Three cutting blades 22 are swingably supported at circumferentially equidistant positions on the periphery of the rotating body 21.

As shown in FIGS. 2 and 3, the cutting blade 22 is made of a resin material in the shape of an elongated plate, and the cutting blade 22 has a boss portion 22 a formed at the base end portion that swings around the periphery of the rotating body 21. It is movably supported. When the rotor 21 does not rotate and no centrifugal force is applied, the cutting blade 22 can freely rotate around the periphery of the rotor 21 as shown in the positions shown in FIGS. 2(a) and 2(b). Has become. When the rotating body 21 is rotated and a centrifugal force is applied, as shown in FIG. 2A, the tip end of the cutting blade 22 opens away from the rotating body 21, and the cutting blade 22 centrifuges the rotating body 21. It extends in the direction (radial direction).

As shown in FIG. 3, a blade portion 22b is formed on the front side (the traveling direction side of the rotation direction) of the cutting blade 22 in the rotation direction, and the cross-sectional shape of the cutting blade 22 in the rotation direction is the central portion in the rotation direction. It has a spindle shape (streamline) that makes it swell. Specifically, the cross-sectional shape of the cutting blade 22 in the rotation direction is such that the tip of the blade portion 22b of the cutting blade 22 is sharp, and the cutting blade 22 advances from the blade portion 22b on the front side in the rotation direction to the central portion in the rotation direction. It swells and becomes thinner again as it goes from the central portion in the rotational direction to the rear side in the rotational direction.

As shown in FIG. 3, the blade portion 22b on the front side in the rotation direction of the cutting blade 22 has a waveform in which the protrusions 22b1 and the recesses 22b2 are alternately continuous in the centrifugal direction (the radial direction of the rotating body 21). .. The blade portion 22b has a central portion C (indicated by a chain double-dashed line in FIG. 3) in the height direction between the top portion (the highest portion) of the protrusion 22b1 and the bottom portion (the lowest portion) of the recess 22b. Divided into the recesses 22b2, the width W1 of the protrusion 22b1 is formed narrower than the width W2 of the recess 22b2. By making the width W1 of the protrusion 22b1 narrower than the width W2 of the recess 22b2, the number of the protrusions 22b1 of the corrugated blade portion 22b can be relatively reduced, and when the cutting blade 22 is rotating, grass etc. The object to be cut is prevented from being caught by the protrusion 22b1 more than necessary.

As shown in FIG. 3, a large number of small protrusions are formed on the surface orthogonal to the rotation direction and the centrifugal direction of the cutting blade 22 (the upper surface and the lower surface when the rotating body 21 is horizontally arranged so that the axial direction is vertical). 22c are formed, and these small protrusions 22c have a function of reducing the vortex of the air passing through the cutting blade 22 and reducing the wind noise of the cutting blade 22.

In the brush cutter 10 configured as described above, when the operator grips the operation handle 17 and the grip handle 18 and turns on the switch 19 to drive the electric motor, the rotating body 21 of the rotary blade unit 20 rotates. Then, the cutting blade 22 swingably supported by the rotating body 21 swings by the centrifugal force so as to open from the closed position in FIG. 2B to the position in FIG. 2A. When the rotary blade unit 20 is moved left and right along the ground, grass, grass and the like growing from the ground are mowed by the cutting blade 22 that rotates together with the rotating body 21.

In the brush cutter 10 configured as described above, the cutting blade 22 has a spindle-shaped cross-sectional shape in the rotational direction such that the central portion in the rotational direction swells. Thereby, the flow of air passing around the cutting blade 22 when the cutting blade 22 is rotated can be improved, the wind noise when the cutting blade 22 is rotated can be reduced, and the cutting blade 22 can be reduced. It has become possible to reduce the load on the electric motor (motor) that rotates the motor 22. The effect obtained by making the cross-sectional shape of the cutting blade 22 in the rotation direction a spindle shape is that the width W1 of the protrusion 22b1 of the corrugated blade portion 22b of the cutting blade 22 is the same as the width W2 of the recess. The present invention can be obtained even in the case where the cutting blade 22 is not formed with the small protrusions 22c.

Further, the cutting blade 22 has a shape curved backward (in a direction opposite to the rotation direction) of the rotation direction of the rotating body 21 as it advances in the centrifugal direction, and the blade portion 22b formed on the front side in the rotation direction of the cutting blade 22 is centrifugal. The protruding portions 22b1 and the recessed portions 22b2 are formed in a corrugated shape that alternates in the direction. By doing so, an object to be cut such as grass is caught on the protrusion 22b1 and can be easily cut. Further, in the blade portion 22b of the cutting blade 22, the width W1 of the protrusion 22b1 is formed to be narrower than the width W2 of the recess 22b2. Thereby, the number of the protrusions 22b1 of the corrugated blade portion 22b can be relatively reduced, and an object to be cut such as grass is less likely to be caught by the protrusion 22b1 of the corrugated blade portion 22b more than necessary, and the cutting blade The load on the electric motor (driving source) that rotates the electric motor 22 can be reduced, and the power consumption of the battery pack 16 that supplies power to the electric motor can be reduced. The action and effect obtained by making the width W1 of the protrusion 22b1 of the corrugated blade portion 22b of the cutting blade 22 narrower than the width W2 of the recess 22b2 is, when the cross-sectional shape of the cutting blade 22 in the rotational direction is not spindle-shaped, The cutting blade 22 is obtained without forming the small protrusion 22c.

In addition, a large number of vortices of air passing therethrough are formed on the surface orthogonal to the rotational direction and the centrifugal direction of the cutting blade 22 (the upper surface and the lower surface when the rotating body 21 is horizontally arranged such that the axial direction is vertical). A small protrusion 22c is formed. When the cutting blade 22 is rotated, the air passing around the cutting blade 22 is diffused by the small projections 22c to generate a small turbulent flow, and a large vortex is suppressed from being generated around the cutting blade 22. As a result, the wind noise can be reduced when the cutting blade 22 rotates. The small protrusions 22c are not limited to the case where the cutting blade 22 is curved backward in the rotational direction, and the same operational effect is obtained when the cutting blade 22 is linearly extended in the centrifugal direction. Can be obtained. Further, the effect obtained by forming the small protrusion 22c on the cutting blade 22 is that the width of the protrusion 22b1 of the corrugated blade portion 22b of the cutting blade 22 when the sectional shape of the cutting blade 22 in the rotation direction is not spindle-shaped. Even if W1 has the same width as the width W2 of the recess, it can be obtained.

The cutting blade of this embodiment is swingably supported by the rotary blade unit provided at the front end of the operating rod of the brush cutter, but the present invention is not limited to this, and the traveling type You may use it for the cutting blade attached to the rotating shaft rotated by an electric motor in the lower part of the housing of a lawn mower.

22... Cutting blade, 22b... Blade portion, 22b1... Projection portion, 22b2... Recessed portion, 22c... Small protrusion.

Claims (3)

Removably attached to the rotating body, a resin plate-shaped cutting blade for cutting grass that extends in the centrifugal direction of the rotating body,
The cutting blade is a shape curved rearward in the rotational direction as it travels in the distal direction outwardly,
Wherein the blade portion formed on the front side in the rotational direction of the cutting blade is formed in a waveform continuous alternating peaks and recesses in the centrifugal direction,
The protrusion is projected in the rotation direction,
The recess is recessed in a direction opposite to the rotation direction,
The blade is divided into the protrusion and the recess at the center in the height direction between the top of the protrusion and the bottom of the recess.
The cutting blade is characterized in that the width of the protrusion is narrower than the width of the recess in the centrifugal direction . The cutting blade according to claim 1,
Cutting blade, characterized in that the plane orthogonal to the rotation direction and the centrifugal direction of the cutting blade forming small projections which reduce the swirl of the air passing through. The cutting blade according to claim 1 or 2 ,
A cutting blade , wherein a cross-sectional shape of the cutting blade in the rotation direction is a spindle shape in which a central portion in the rotation direction swells .

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