Patent Description:
As a handheld working machine for cutting or clipping branches and leaves, there has been generally known a hedge trimmer equipped with a reciprocating blade apparatus having reciprocating blades, like a hair clipper, as disclosed, for example, in <CIT>.

Here, the reciprocating blade has an advantage over a rotary blade or a nylon cutter used in a common brush cutter in that it produces little scattering substances during the work. With this advantage of the reciprocating blade, a brush cutter for cutting grass on the ground has been proposed, for example, in <CIT>, which includes a reciprocating blade apparatus mounted to the top end of a handheld operating rod.

With the above-described related art, the power is transmitted to a gearing system in the transmission case via the drive shaft, and the reciprocating blades are coupled to a crank arm of the gearing system. The gearing system transmits the power from the drive shaft to a transmission shaft pivotally supported in the transmission case to rotate the transmission shaft. This rotation of the transmission shaft allows a crank arm coupled to a crank to rotate about an eccentric axis to swing the top end of the crank arm about a fixed axis. By this means, the reciprocating blades coupled to the top end of the crank arm are reciprocated for the swing width.

The gearing system according to the above-described related art has a structure where the top end of the crank arm is moved also in a direction intersecting the moving direction of the reciprocating blades due to the arc motion of the top end of the crank arm, and the movement is cleared by the connecting part of the top end of the crank arm and the blades. Accordingly, vibrations in a direction different from the reciprocating motion of the blades are applied to the blades. This prevents the blades from smoothly reciprocating, and consequently, tends to cause a problem with vibrations and noise.

<CIT>, which is a document having been published after the priority date of the present application, discloses a reciprocating blade apparatus according to the preamble of claim <NUM>. Other reciprocation blade apparatuses with related technology are disclosed in <CIT> and <CIT>.

To solve the above-described problem, it is desirable to provide a reciprocating blade apparatus capable of smoothly reciprocating the blades of the reciprocating blade apparatus, and preventing the vibrations and noise of the brush cutter equipped with the reciprocating blade apparatus.

Above mentioned technical problem is solved by a reciprocating blade apparatus according to claim <NUM>.

According to the present invention, the joint members of the power train are guided to be able to move along the axis line which is parallel to the moving direction of the reciprocating blades and runs through the rotation axis of the eccentric cams. Therefore, it is possible to smoothly reciprocate the blades of the reciprocating blade apparatus, and prevent the vibrations and noise of the brush cutter equipped with the reciprocating blade apparatus.

Advantageous embodiments of the invention are characterized by the features of the dependent claims.

The same reference numbers in the different drawings indicate the same functional parts, and therefore repeated description for each of the drawings is omitted.

As illustrated in <FIG> and <FIG>, a reciprocating blade apparatus <NUM> includes a pair of reciprocating blades <NUM> (hereinafter referred to as "blade member"), a transmission case <NUM>, and a blade support member <NUM>. The reciprocating blade apparatus <NUM> is configured to cut and mow plants and so forth by sliding and reciprocating the blade member <NUM> relative to one another.

The blade member <NUM> includes two blades 2A and 2B made of metal plates which are stacked in the thickness direction (Z direction in the drawings). Each of the blades 2A and 2B of the blade member <NUM> includes a base <NUM> as a flat plate extending in the longitudinal direction (X direction in the drawings) and a plurality of teeth <NUM> protruding in the direction (Y direction in the drawings) intersecting the longitudinal direction.

The base <NUM> of each of the blades 2A and 2B is supported by the blade support member <NUM>, and includes a plurality of long holes 20A formed along the longitudinal direction (X direction in the drawings) of the blade member <NUM>. Adjustment screws described later as fastening members penetrate the long holes 20A. These long holes 20A regulate the moving direction of the blade member <NUM> reciprocating.

The teeth <NUM> may be provided in both sides of each of the blades 2A and 2B in Y direction as illustrated, or provided in one side. These teeth <NUM> are like comb-like blades of a hair clipper. The two blades 2A and 2B slide relative to one another in the longitudinal direction to cut the plants between the teeth <NUM> of the blades 2A and 2B.

The transmission case 3A includes a power train to reciprocate the blade member <NUM>. The power train is configured to convert the rotation of a drive shaft (not illustrated) to reciprocating motion, and includes reciprocating members <NUM> (30A and 30B) such as connecting rods which are reciprocably supported in the longitudinal direction (X direction in the drawings) of the blade member <NUM>, and a pair of eccentric cams <NUM>.

As illustrated in <FIG> and <FIG>, the reciprocating members <NUM> (30A and 30B) include joints 30t formed at their top ends which are coupled to the bases <NUM> of the blades 2A and 2B, respectively. Each of the joints 30t includes a convex portion protruding in the direction (Y direction in the drawings) orthogonal to the longitudinal direction of the blade member <NUM>. Meanwhile, a concave portion 20B is formed in the base <NUM> to engage with the convex portion of the joint 30t.

Each of the reciprocating members <NUM> (30A, 30B) includes a fitting hole <NUM> in which the eccentric cams <NUM> are fitted, and guide holes 30n. Guide members 32A are fixed to the transmission case <NUM> via support members <NUM>, and engaged with the guide holes 30n of the reciprocating members <NUM>. The guide holes 30n are provided on the right and left sides of the fitting hole <NUM> along X direction in <FIG>.

The blade support member <NUM> is attached to the transmission case <NUM>, and sandwiches the bases <NUM> of the pair of blades 2A and 2B therebetween to allow the blade member <NUM> to move in the longitudinal direction (X direction in the drawings). As illustrated in <FIG>, the blade support member <NUM> includes a pair of support plates (upper support plate 4A and lower support plate 4B) extending in the longitudinal direction (X direction) of the blade member <NUM>.

The upper support plate 4A and the lower support plate 4B of the blade support member <NUM> are fastened via spacers <NUM> to make a space to accommodate the blades member <NUM>. The upper support plate 4A and the lower support plate 4B are individually attached to the transmission case <NUM> while keeping the space. The blade member <NUM> is accommodated in the space and detachably attached to the blade support member <NUM>.

Here, how to fasten and support the blade member <NUM> and the blade support member <NUM> will be described. First, attachment screws <NUM> are screwed into screw holes 41A of the upper support plate 4A via holes 3A of the transmission case <NUM> to independently attach the upper support plate 4A of the blade support member <NUM> to the transmission case <NUM>. Meanwhile, the upper support plate 4A and the lower support plate 4B are fastened by fastening screws <NUM> at fastening points 42A without interfering with the blade member <NUM>. The fastening screws <NUM> penetrate the holes of the lower support plate 4B and the spacers <NUM>, and are screwed into the fastening points 42A of the upper support plate 4A. By this means, the upper support plate 4A and the lower support plate 4B are fastened while keeping the space for the thickness of the spacers <NUM>, and attached to the transmission case <NUM>. In this case, the upper support plate 4A and the lower support plate 4B are coupled to one another by the fastening screws <NUM> via the spacers <NUM>, and the fastened portion serves as a joint of bamboo. By this means, it is possible to improve the rigidity of the blade member <NUM> and the blade support member <NUM> while reducing the weight.

The pair of blades 2A and 2B sandwiched between the upper support plate 4A and the lower support plate 4B is reciprocably supported by the blade support member <NUM> with the adjustment screws <NUM> (43A, 43B, 43C and 43D) at points different from the fastening points 42A. Here, the two adjustment screws 43A and 43D of the four adjustment screws <NUM> are inserted into washers <NUM> and screwed into screw holes <NUM> of the upper support plate 4A via the long holes 20A of the blade member <NUM>, and fixed by fixing nuts <NUM>. In addition, the other two adjustment screws 43B and 43C are inserted into the holes of the lower support plate 4B, and screwed into the screw holes <NUM> of the upper support plate 4A via the long holes 20A of the blade member <NUM>, and fixed by the fixing nuts <NUM>.

In this case, the distance between the washer <NUM> and the upper support plate 4A is adjusted by the adjustment screws 43A and 43D, and therefore it is possible to adjust the distance between the two blades 2A and 2B sandwiched between the washer <NUM> and the upper support plate 4A. In addition, the distance between the upper support plate 4A and the lower support plate 4B is adjusted by the adjustment screws 43B and 43D, and therefore it is possible to adjust the distance between the two blades 2A and 2B sandwiched between the upper support plate 4A and the lower support plate 4B.

As illustrated in <FIG> and <FIG>, the blade member <NUM> is coupled to the power train in the transmission case <NUM> simply by coupling the joints 30t of the reciprocating members <NUM> to the bases <NUM> of the blade member <NUM>, and engaging the convex portions of the joints 30t with the concave portions 20B of the bases <NUM> caving in the direction in which the convex portions protrude. Therefore, it is possible to easily detach the blade member <NUM> from the transmission case <NUM> and the blade support member <NUM> by pulling out the blade member <NUM> in Y direction.

Here, in a case where the concave portion 20B is provided near the center of each of the bases <NUM> in the longitudinal direction, the concave portion 20B can be easily engaged with the convex portion of the joint 30t of the reciprocating member <NUM> simply by aligning approximately the center of the base <NUM> with approximately the center of the blade support member <NUM>. By this means, it is possible to readily couple the blade member <NUM> to the power train. Meanwhile, even in a case where the concave portion 20B is not provided near the center of the base <NUM>, the joint 30t of the reciprocating member <NUM> can be seen between the upper support plate 4A and the lower support plate 4B, and therefore it is possible to easily engage the joint 30t with the concave portion 20B of the base <NUM>, watching the convex portion of the joint 30t.

In addition, in a case where the blade member <NUM> is detached from the blade support member <NUM>, when the joint 30t of the reciprocating member <NUM> engaged with the concave portion 20B of the blade 2A overlaps the joint 30t of the reciprocating member <NUM> engaged with the concave portion 20B of the blade 2B, it is easy not only to detach the blade member <NUM> but also to attach the blade member <NUM>. However, when the blades 2A and 2B are stopped during the reciprocating motion of them, the concave portions 20B of the blades 2A and 2B are not aligned with one another, and also the joints 30t are not aligned with one another.

Therefore, alignment holes <NUM> of the upper support plate 4A, alignment holes <NUM> of the blade 2A, alignment holes <NUM> of the blade 2B, and alignment holes <NUM> of the lower support plate 4B are provided to align the blades 2A and 2B with one another when the blade member <NUM> is stopped. After the blade member <NUM> is stopped, the blades 2A and 2B can be aligned with one another by inserting a tool such as a flat-blade screwdriver into the alignment holes <NUM> to <NUM>, and therefore it is possible to align the concave portions 20B of the blades 2A and 2B with one another before the blade member <NUM> is detached from the blade support member <NUM>. By this means, it is possible to overlap the joints 30t engaged with the concave portions 20B with one other. This alignment makes it easy to attach and detach the blade member <NUM> to and from the blade support member <NUM>. In order to check the alignment, a plurality of holes are formed in the upper support plate 4A and the blades 2A and 2B, which overlap with each other when the alignment is successfully done.

In the transmission case <NUM>, the rotation of the drive shaft is transmitted via the gear of the power train to rotate the pair of eccentric cams <NUM> about a rotation axis 31X. The pair of eccentric cams <NUM> includes disc bodies rotating together about an eccentric axis with a phase difference of <NUM> degrees. The eccentric cams <NUM> are fitted into the fitting holes <NUM> of the pair of reciprocating members 30A and 30B, respectively.

As illustrated in <FIG>, the guide holes 30n provided on the both sides of the fitting holes <NUM> of each of the reciprocating members 30A and 30B extend parallel to the direction in which the blade member <NUM> reciprocates. In addition, the guide members 32A engaged with the guide holes 30n are provided on an axis line Gp running through a center Op of the rotation axis 31X of the eccentric cams <NUM>, and are spaced the same distance L from the center Op of the rotation axis 31X. By this means, the pair of reciprocating members 30A and 30B is guided to be able to move along the axis line Gp which is parallel to the moving direction of the blade member <NUM> and runs through the center Op of the rotation axis 31X of the eccentric cams <NUM>.

With this power train, the pair of reciprocating members 30A and 30B coupled to the blade member <NUM> is guided to linearly move by the pair of guide members 32A which are provided to pass through the center Op of the rotation axis 31X of the eccentric cams <NUM> and are spaced the same distance L from the center Op of the rotation axis 31X. This makes it possible to apply the reaction force of the guide members 32A and the eccentric cams <NUM> to the pair of reciprocating members 30A and 30B in a balanced manner, and therefore to allow the blade member <NUM> to smoothly reciprocate. By this means, it is possible to prevent the vibrations and noise from occurring during the operation of the blade member <NUM> (2A and 2B).

Moreover, the reciprocating members 30A and 30B include the joints 30t as convex portions protruding in the direction orthogonal to the axis line Gp along which the reciprocating members 30A and 30B are guided, and the joints 30t are engaged with the concave portions 20B formed in the bases <NUM> of the blade member <NUM> in the direction orthogonal to the axis line Gp. By this means, the motion of the reciprocating members 30A and 30B moving parallel to the axis line Gp efficiently reciprocate the blade members <NUM>. Therefore, it is possible to stably reciprocate the blade member <NUM> without wobbling. Moreover, it is possible to shorten the distance between the axis line Gp and the bases <NUM> of the blade member <NUM>, and therefore to efficiently transmit the motion of the reciprocating members 30A and 30B to the blade members <NUM>.

<FIG> illustrates an example of handheld working machine including the reciprocating blade apparatus <NUM>. As illustrated in <FIG>, a handheld working machine <NUM> includes an operating rod <NUM>, and the top end of the operating rod <NUM> is mounted to an operating rod mount <NUM> of the transmission case <NUM>. The operating rod mount <NUM> is mounted to the transmission case <NUM> via an angle adjustment mechanism 33A. The angle adjustment mechanism 33A can adjust the rising angle of the operating rod <NUM> from the working surface of the blade member <NUM>.

A drive shaft (not illustrated) configured to transmit the power to the power train is provided in the operating rod <NUM>. In addition, a drive unit <NUM> configured to drive the drive shaft is provided at the base end of the operating rod <NUM>, and an operating handle <NUM> is provided in the base end side of the operating rod <NUM>. The operating handle <NUM> includes a grip 13A above the operating rod <NUM>.

The drive unit <NUM> is configured to drive the reciprocating blade apparatus <NUM> via the drive shaft in the operating rod <NUM>, and includes a housing <NUM> to accommodate a motor disposed approximately coaxially with the operating rod <NUM>. A rear handle 14A including an operating switch 14B configured to turn on and off the reciprocating blade apparatus <NUM> is provided in the housing <NUM>. A battery unit <NUM> configured to supply electric power to the motor in the housing <NUM> is externally attached to the housing <NUM>.

This handheld working machine <NUM> is an electric brush cutter equipped with the reciprocating blade apparatus <NUM>. The longitudinal direction of the blade member <NUM> intersects the longitudinal direction of the operating rod <NUM>, and therefore the reciprocating blade apparatus <NUM> is provided at the top end of the operating rod <NUM> to form a T-shape. This handheld working machine <NUM> performs brush cutting by driving the reciprocating blade apparatus <NUM> to move the reciprocating blade apparatus <NUM> along the ground while the worker holds the operating handle <NUM> and the rear handle 14A of the housing <NUM> by the hands to keep a predetermined rising angle of the operating rod <NUM> from the ground.

With this handheld working machine <NUM>, the width of the blade member <NUM> of the reciprocating blade apparatus <NUM> is the effective width, and therefore the worker simply pushes the operating rod <NUM> without shaking the operating rod <NUM> from side to side, and consequently it is possible to do the brush cutting with the effective width. Therefore, it is possible to perform the brush cutting by speedily moving the reciprocating blade apparatus <NUM> forward, and consequently to improve the efficiency of the brush cutting. Moreover, the reciprocating blades are used, and therefore it is possible to reduce the scattering substances during the brush cutting. By this means, it is possible to ensure the safety of the worker and the surrounding of the worker, and prevent the damage of other people's properties near the working site during the brush cutting. Moreover, when the teeth <NUM> of the blade member <NUM> are provided on both the front and back sides, it is possible to easily cut plants left uncut by pulling the handheld working machine <NUM> to the worker.

Furthermore, the handheld working machine <NUM> allows comfortable work with little vibration and prevents the noise due to the reciprocating motion of the blade member <NUM>. Therefore, it is possible to allow the work without harmful effects on the surrounding of the working site due to the noise.

Claim 1:
A reciprocating blade apparatus (<NUM>) comprising:
a pair of reciprocating blades (2A, 2B) stacked on one another in a thickness direction; and
a transmission case (<NUM>) including a power train configured to convert the rotation of a drive shaft to reciprocating motion of the pair of reciprocating blades (2A, 2B),
the power train including:
a pair of eccentric cams (<NUM>); and
a pair of reciprocating members (30A, 30B) including fitting holes (<NUM>) in which the eccentric cams (<NUM>) are fitted, respectively,
wherein the pair of reciprocating members (30A, 30B) is guided to be able to move along an axis line (Gp) which is parallel to a moving direction of the pair of reciprocating blades (2A, 2B),
wherein each of the pair of reciprocating members (30A, 30B) includes a pair of guide holes (30n) formed on both sides of a fitting hole (<NUM>); and
wherein the transmission case (<NUM>) includes a pair of guide members (32A) engaged with the guide holes (30n),
characterized in that the pair of eccentric cams (<NUM>) includes disc bodies rotating together about an eccentric rotation axis (31X) with a phase difference of <NUM> degrees, wherein the rotation of the drive shaft is transmitted via the gear of the power train to rotate the pair of eccentric cams (<NUM>) about said rotation axis (31X), and wherein said axis line (Gp) runs through said rotation axis (31X).