JPH0513142Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a cutting blade device particularly suitable for use in a brush cutter.

Conventional technology Conventionally, the cutting blade device of a brush cutter used for mowing grass etc. uses a driving force from a prime mover such as an internal combustion engine to drive a disc-shaped cutting blade rotatably attached to the tip of an operating stick. It is generally configured to rotate at high speed in one direction to perform tasks such as mowing grass. However, in conventional brush cutter blade devices, the rotation speed of the cutting blades is extremely high, and as a result, the operator or the like may inadvertently touch the cutting blades, which rotate at high speed, or be blown away by the cutting blades. It has drawbacks such as being injured by hitting stones, etc. In order to improve this problem, a so-called clipper-type cutting blade device has been proposed in which two elongated plate-shaped cutting blades are overlapped and reciprocated relative to each other to cut grass. This type of cutting blade device is safe for the operator because the movement of the cutting blade is performed at a relatively low speed. The mechanism that converts it into driving force is quite complex and heavy, making it difficult to cut the grass by swinging the operating stick from side to side as a brush cutter, and its manufacturing and assembly is time consuming and costly.

Problems to be Solved by the Invention Therefore, an object of the present invention is to eliminate the drawbacks of the conventional technology and provide a mowing blade device for a brush cutter that is simple in structure, safe, and convenient.

Means for Solving the Problems That is, the reversible cutting blade device according to the present invention rotatably supports a drive shaft to which a drive gear is attached to the main body,
The axes of a pair of driven gears having the same diameter that mesh with the drive gear on both sides of the drive gear are positioned on a straight line passing through the axis of the drive shaft, and are rotatably supported by the main body, and the driven gears are rotatably supported by the main body. Eccentric cam portions having the same diameter are integrally provided in the main body, and a pair of plate-shaped cutting blades each having a cutting portion are supported in a stacked manner on the main body so as to be rotatable relative to each other about the axis of the drive shaft. , and each of the cutting blades is formed with a cam elongated hole and a cam part clearance hole that respectively engage with the eccentric cam part, centered on the axis of the driven gear, and the cam elongated hole of the one cutting blade and the cam part relief hole are respectively formed around the axis of the driven gear. It is characterized by a structure in which the cam part of the other cutting blade is arranged to overlap with the escape hole of the cam part.

Function: Therefore, when the drive shaft rotates, the pair of driven gears are rotated in opposite directions via the drive gear,
Thereby, the pair of cutting blades are rotated in opposite directions through engagement between the eccentric cam portion and the cam elongated hole, and the respective blades are engaged with each other to cut weeds and the like.

Embodiments Next, the present invention will be described based on embodiments shown in the drawings.

The reversible cutting blade device of the illustrated embodiment has a main body 1 made of aluminum alloy or the like, and the main body 1 is removably attached at its base 2 to the front end of a control rod (not shown) of a brush cutter. . As shown in FIG. 1, the main body 1 has a drive shaft 3 rotatably supported in the center thereof by bearings 4 and 5, and the drive shaft 3 is connected at its upper end 6 to the operating rod. arrow A in FIG. 2 is connected to a transmission shaft (not shown) through the transmission shaft by driving force from a prime mover such as an internal combustion engine installed at the rear end of the operation stick.
It is designed to be rotationally driven in the direction of.

The drive shaft 3 has a drive gear 8 fixed to its lower end 7, and a pair of driven gears 9 of the same shape are mounted on opposite sides of the drive gear 8 in the diametrical direction.
and 10 are meshingly engaged with the drive gear 8. The driven gears 9 and 10 are connected to the main body 1.
The shafts are supported by support shafts 11 and 12, which are press-fitted into the shafts, respectively, so that they can rotate in directions opposite to each other as indicated by arrows B and C in FIG. Looking at FIG. 1, the driven gear 9 on the right side is integrally formed with a circular driving side cam portion 13 eccentric to the right support shaft 11 on its lower surface, and similarly, the driven gear 10 on the left side is A circular drive-side cam portion 14 eccentric to the left support shaft 12 is integrally formed on its lower surface. A wear-resistant sleeve member 15 is loosely fitted onto the outer peripheral surfaces of both the cam portions 13 and 14, respectively.

The lower end portion 7 of the drive shaft 3 has a pair of disc-shaped cutting blades 17 and 18 disposed vertically in two layers via a bearing 16 in a portion further below the attachment portion of the drive gear 8, and rotates. supported as possible. The bearing 16 supports the cutting blades 17 and 18 so that they can rotate independently with respect to the drive shaft 3, and acts as a fulcrum for slidingly reversing the cutting blades 17 and 18 independently of each other. The pair of cutting blades 17 and 1
8 are formed in the same shape as each other, and as shown in FIG. Oval driven-side cam elongated holes 20 are formed in portions deviated radially outward from the radial direction. The cam elongated hole 20 of the lower cutting blade 17 is arranged coaxially with the right support shaft 11, and the cam portion 13 of the driven gear 9 is arranged within the cam elongated hole 20. The sleeve member 15
The outer peripheral surface of the cam is slidably engaged with the inner peripheral surface of the elongated cam hole 20. Similarly, the cam elongated hole 20 of the upper cutting blade 18 is arranged coaxially with the left support shaft 12, and the cam portion 14 of the driven gear 10 is arranged within the cam elongated hole 20 and its sleeve member. The outer peripheral surface of the cam 15 is slidably engaged with the inner peripheral surface of the cam elongated hole 20. Further, the lower cutting blade 17 has a large-diameter cam escape hole 21 so as not to come into contact with the cam part 14 of the left driven gear 10 during operation. The blade 18 has a cam part escape hole 21 so as not to come into contact with the cam part 13 of the right driven gear 9. As shown in FIG. When contacting the inner peripheral point D of the lower cam elongated hole 20 located at the farthest position from the center of the cutting blade 17 on the side, that is, the center O of the drive gear 8, the left cam part 14 passes through the sleeve member 15. The cutting blade 18 is set to contact an inner peripheral point E of the upper cam elongated hole 20 at a position closest to the center of the upper cutting blade 18, that is, the center O of the drive gear 8. When both sleeve members 15 are worn out due to sliding contact with the driven side cam elongated holes 20, 20 of the upper and lower cutting blades 17, 18, they can be easily repaired by replacing only the sleeve member 15. .

The pair of upper and lower cutting blades 17 and 18 have four circumferential grooves 22 and 23 formed near their outer peripheries, separated by an angle of, for example, 90 degrees, and the grooves 22 and 23 are mutually adjacent to each other. arranged in alignment. The lower surface of the lower cutting blade 17 is covered with a cover plate 24, and four bolts 25
However, the cover plate 24 is connected to the main body 1 by the cover plate 24, the grooves 22 and 23 in which the upper and lower cutting blades 17 and 18 are aligned, and the nut 26 that passes through the main body 1 and is screwed thereto. It is attached to the main body 1 with the cutting blades 17 and 18 slidably sandwiched therebetween. Note that it is preferable that the bolt 25 is provided with a double nut tightening so that the clamping force of the cutting blades 17 and 18 can be adjusted. A circumferential groove 27 is formed on the inner surface of the peripheral edge portion of the main body 1 facing the upper surface of the upper cutting blade 18, and a piano wire ring 28 is formed in the circumferential groove 27.
and 29 are arranged. The piano wire ring 2
8 and 29 contact the upper surface of the upper cutting blade 18 to separate the main body 1 from the cutting blade 18, thereby minimizing the kinetic friction of the cutting blade 18 and preventing wear between the main body 1 and the cutting blade 18. do.

Further, a suitable dust seal ring is disposed inside the piano wire ring 28 to take dust-proofing measures into consideration for the cutting blade drive mechanism.

With the above-described configuration, the upper and lower cutting blades 17 and 18
When the drive shaft 3 and the drive gear 8 rotate in the direction of arrow A when is in the position shown in FIG. 2, the two driven gears 9 and 10 are rotated in opposite directions in the directions of arrows B and C, respectively. Therefore, the driving side cam parts 13 and 14 also rotate in the directions of arrows B and C in opposite directions to each other, and the driven side cam elongated hole 2
0 and 20, and while the driven gears 9 and 10 rotate half a rotation, the cutting blades 17 and 18 rotate counterclockwise and clockwise, respectively, in opposite directions, and the blades of the cutting blades 17 and 18 rotate in opposite directions. 19 can cut weeds etc. by interlocking with each other. When the driven gears 9 and 10 are further rotated and the cam portions 13 and 14 are further rotated by 180 degrees, the cutting blades 17 and 18 are respectively reversely rotated in the opposite direction and returned to their original positions. In this way, the cam parts 13 and 14 each rotate with a cam stroke θ, so that the cutting blades 17 and 18 cancel each other's inertial forces over the cutting blade stroke 2θ, and are relatively repeatedly oscillated. move.

Therefore, mowing work can be carried out safely and efficiently using the same method as with conventional rotary blade type brush cutters.

Effects of the invention With the structure of the invention explained above, the invention has the following effects:
The mechanism for reversing and oscillating the cutting blade is formed by a simple integral structure of gears and cam parts, and a pair of cutting blades can be formed as parts with the same shape, making it easy to share parts and improving mechanical balance. The reversible type mower blade has a simple structure and can be manufactured at low cost, and is economical by reducing parts costs. Provides equipment that enables work to be carried out safely and comfortably.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a main part of a brush cutter blade device showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the - arrow in FIG. 1. 1... Main body, 3... Drive shaft, 8... Drive gear,
9, 10... Driven gear, 13, 14... Drive side cam section, 17, 18... Cutting blade, 19... Blade section, 2
0, 21... Driven side cam elongated hole.

Claims (1)

[Scope of utility model registration request] A drive shaft 3 to which a drive gear 8 is attached is rotatably supported by the main body 1, and a pair of driven gears 9 of the same diameter meshingly engage with the drive gear on both sides of the drive gear.
10 is positioned on a straight line passing through the axis of the drive shaft and is rotatably supported by the main body, and eccentric cam parts 13 and 14 of the same diameter are each integrally provided on the driven gear, and the blade part 19 is A pair of plate-shaped cutting blades 17 and 18 are supported on the main body in a two-layered manner so as to be rotatable relative to each other about the axis of the drive shaft, and each of the cutting blades has a pair of plate-shaped cutting blades 17 and 18 attached to the eccentric cam portion. A cam elongated hole 20 and a cam part relief hole 21 that engage with each other are respectively formed around the axis of the driven gear, and the cam elongated hole of the one cutting blade and the cam part escape hole of the other cutting blade are formed respectively. A reversible cutting blade device characterized in that the blades are arranged in a combined manner.