JPH0621301Y2 - Cutting blade mounting device for brush cutter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a cutting blade mounting device for a brush cutter, and more specifically, it securely mounts a cutting blade on an output shaft of a gear case of the brush cutter, and The present invention relates to a mounting device having a double nut function for loosening a fastening portion.

[Conventional technology]

In many of the conventionally known brush cutters, a small engine as a power source is attached to one end of the operating main rod, and the output of this engine is passed through a transmission shaft that penetrates through the inside of the operating main rod. Input to a gear case provided at the other end of the operating main rod, and is configured so that the cutting blade is fastened and fixed by the cutting blade retainer attached to the output shaft of the gear case and the fastening washer of the cutting blade. It is a thing.

More specifically, a disc-shaped cutting blade presser is integrally fixed to the output shaft, and a cutting blade closely attached to the cutting blade presser is fitted on the output shaft, and a male screw portion formed on the output shaft. The cutting blade is fastened to the output shaft by screwing a fixed nut and a lock nut onto the output shaft, which is a so-called double nut mounting type.

[Problems to be solved by the device]

By the way, since the cutting blade can rotate at a high speed of several thousand revolutions per minute, if the cutting blade may fall off during high-speed rotation, the cutting blade will rotate around and the accident will occur. For safety reasons, it is desirable that the cutting blade be fastened to the output shaft with a double nut.

Therefore, when installing or replacing the cutting blade, tightening or loosening the double nut is required when the cutting blade is attached, and it is very troublesome.In the case of women and women who have little knowledge of the machine, the cutting blade may not be replaced, and normally, Since the output shaft is rotated counterclockwise, it is tightened with the left screw.
If an inexperienced operator replaces the cutting blade, the fastening may not be securely performed, which is extremely dangerous.

Therefore, this invention allows the cutting blade to be attached and detached by a relatively simple operation, and the cutting blade can be tightened and fixed as the cutting blade rotates at a higher speed, and furthermore, the mounting by screwing at the time of high speed rotation. It is an object of the present invention to provide a mounting device having a loosening function similar to fastening with a double nut to a portion.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention has an engine at one end of an operating main rod and a gear case at the other end, and a cutting blade restrainer attached to an output shaft of this gear case and an output. A cutting blade attachment device for a brush cutter, which is attached to a shaft and has a cutting blade fastening base for mounting the cutting blade between the cutting blade presser, and the fastening base is screwed to the output shaft. Part, a moving member housed between the housings formed inside and moving by centrifugal force, a friction plate that presses the cutting blade against the cutting blade holder by the movement of this moving member, and is attached to the fastening table. The centrifugal governor and a drive unit that pushes down the fastening table by the centrifugal force generated in the centrifugal governor, and the friction plate has its inner peripheral edge fixed to the fastening table, and the friction plate When the number of revolutions exceeds the specified value, the cutting blade is fixed by friction and the Parts are characterized by being configured to Domesuru so loosening the attachment portion by expanding between the fastening base and the cutting blade kept in motion of the centrifugal governor.

[Action]

In the cutting blade mounting device of the present invention, the moving element housed in the internal space of the fastening table is moved in the radial direction by the centrifugal force generated by the high speed rotation of the output shaft, and the friction plate is lifted by this movement. Tightens the cutting blade firmly against the blade
Further, the driving unit driven by the centrifugal force generated in the centrifugal governor applies a frictional force to the screwing portion of the mounting portion, and functions like a double nut. When the rotation of the output shaft decreases, the tightening force also decreases as the centrifugal force decreases, the relationship between the output shaft and the cutting blade becomes free, and the double nut function of the drive unit is canceled.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. First, FIG. 1 is a partial cross-sectional view showing a cutting blade of a brush cutter and an output shaft portion of a gear case to which the cutting blade is attached. Reference numeral 1 indicates a gear case including a reduction mechanism, for example. A stepped output shaft 2 is provided in a projecting manner. The output shaft 2 has a large diameter portion 2A near the gear case 1 and a small diameter portion 2B near the lower end thereof, and a spline groove is formed on the large diameter portion 2A. The small diameter portion 2B is formed with a left-handed male thread portion.

Furthermore, a disc-shaped cutting blade holder 3 is provided on the lower surface of the gear case 1.
Is fitted into the spline groove of the large diameter portion 2A and is in a closed state. ing.
The diameter of this boss portion 3C is determined to fit into the center hole X ₁ of the cutting blade X.

A left-hand thread is formed on the small-diameter portion 2B of the output shaft 2, and the fastening base 4 is screwed into the small-diameter portion 2B by screwing a female screw hole 4A as a mounting portion provided at the center thereof. Be worn.

The fastening base 4 has a container-like shape whose lower surface 41 has a gentle curved surface, and has a donut-shaped boss at the center thereof.
42 is formed, and the outer diameter of the boss portion 42 is slightly smaller than the outer diameter of the step portion 3B of the cutting blade retainer 3,
The outer peripheral portion has a step portion 42A.

Further, a donut-shaped space having a tapered surface 43 is formed on the outer periphery of the boss portion 42 so that the bottom surface gradually becomes shallower toward the outer periphery, and a mover accommodation space for accommodating the ball 7 as a mover is formed.
44, and the outer peripheral edge of the mover housing space 44 is a rim.
45, and the outer periphery of the rim 45 has a fastening base 4 for the output shaft 2
There is a concavo-convex 45A that can be used as a finger suspension for screwing or loosening. A partition wall 46 is formed in the mover housing space so that the ball 7 does not move to the center of the space.

The open surface of the mover accommodating space 44 is covered with a donut type leaf spring 5 as a friction plate, and the inner peripheral edge 5A of the leaf spring 5 is fitted to the step portion 42A of the boss portion 42, and the leaf spring is The outer peripheral edge of 5 is in a free state, and the step portion 45B of the rim 45 of the fastening base 4 is
Elasticity is trying to return to a flat state at all times so that

In addition, a plurality of balls 7 as a mover, rolls, wedges, etc. (not shown) are accommodated in the mover accommodation space 44, and the diameter of the ball 7 is closer to the center of the mover accommodation space 44. In the part of, the tapered surface 43 does not come into contact with the leaf spring 5.
The wedge effect can be expected by setting the dimension of the leaf spring 5 when the leaf spring 5 moves in the outer circumferential direction.

A plurality of drive cams 62 as a drive unit supported by a support shaft 61 are attached to the upper end edge of the boss portion 42 of the fastening base 4 along the circumferential direction, and one end of a governor arm 63 is attached to each support shaft 61. Is fixed, and the weight 64 is fixed to the tip end of the centrifugal governor 6. The drive cam 62 and the surface of the cutting blade retainer 3 that comes into contact with the surface of the drive cam 62 are rough surfaces, and friction is generated in the contact state.

When the cutting blade X is attached to the output shaft 2,
The center hole X1 is fitted into the boss portion 3C of the cutting blade retainer 3 and the female screw hole 4A of the fastening base 4 is screwed into the small diameter portion 2B of the output shaft 2 to form the flange portion 3A of the cutting blade retainer 3. , The leaf spring 5 is tightened.

When the engine starts, its speed is not so high,
Even if the output shaft 2 rotates, a large centrifugal force does not act on the ball 7, and the ball 7 is in the floating state in the vicinity of the partition wall 46 of the moving element housing space 44 in proportion to the magnitude of the centrifugal force applied. Has become.

In this state, even if the output shaft 2 and the fastening base 4 are rotated, the coupling force between the leaf spring 5 and the cutting blade X is not generated until the ball 7 is subjected to a large centrifugal force, I also function as a clutch.

As the engine speed increases, the rotation of the output shaft 2 also becomes a high-speed rotation, the centrifugal force acting on the ball 7 increases, and the ball 7 moves along the tapered surface 43 to the outer periphery of the mover housing space 44. Moving. Since the ball 7 is located between the tapered surface 43 and the leaf spring 5 and moves to the outer periphery in proportion to the magnitude of the centrifugal force, a centrifugal force exceeding the elasticity of the leaf spring 5 acts. In other words, the engine runs at high speed. In the rotating state, the leaf spring 5 is pushed up by the ball 7 against self-elasticity, and a strong frictional force is generated between the leaf spring 5 and the cutting blade X. This frictional force causes the output shaft 2 and the cutting blade 2 to cut. Blade holder 3, fastening table 4
Together with this, the cutting blade X is rotated.

Further, as the number of rotations increases, a centrifugal force is applied to the weight 64 that constitutes the centrifugal governor 6, and when the weight 64 rises, the governor arm 63 rotates and expands in diameter, so that the drive cam is passed through the support shaft 61. By rotating 62 to insert it between the fastening base 4 and the cutting blade retainer 3, the fastening base 4 is pushed down and pressure is applied to the threaded portion to perform a locking action.

In the low rotation region of the engine, a centrifugal force that acts on the ball 7 to strongly press the leaf spring 5 against the cutting blade X is not generated, so that a kind of centrifugal clutch is provided between the cutting blade X and the output shaft 2. There is a mechanism and the cutting blade X is in a low rotation state. Conversely, when the cutting blade X bites into a tree and is locked and the engine is overloaded, the cutting blade X and the output shaft 2, As a result, the engine suddenly stops, or the output drops at a low speed, so that the centrifugal force disappears and the ball 7 moves in the direction of eliminating friction, and only the cutting blade X is locked and the engine suddenly stops. It is possible to prevent a sudden increase in load.

[Other Examples]

In the above embodiments, the centrifugal governor 6 moves in a plane along the axis of the output shaft. However, as shown in FIGS. 4 and 5, in the plane along the rotation direction. The centrifugal governor 8 whose diameter is expanded by is provided to form a wedge 82 as a drive unit at the end of the support shaft 81, and a weight 84 is formed at the tip of the governor arm 83 so that the weight of another centrifugal governor is reduced. It may be connected by a tension spring 85 so as to always attract each other.

[Other Examples]

Further, as shown in FIGS. 6 and 7, a cylindrical slider 91 that can slide along the output shaft 2 is provided between the fastening base 4 and the cutting blade retainer 3, and the slider 91 and the fastening base 3 are provided. A centrifugal governor 9 composed of a weight 93 supported by a pair of governor arms 92 may be provided between the centrifugal governor 9 and the control unit 4.

In this case, for example, in the case where two weights 93 are arranged in the circumferential direction, the weights 93 and 93 at the symmetrical positions are
It is pulled to the center by a tension spring 94. The weight 93 can utilize the weight of the boss portion connecting the connecting end portion 92A of the governor arm 92 with the pin 92B.

In addition, as shown in FIGS. 8 and 9, on the bottom surface of the moving element accommodating space 44 of the fastening table 4, that is, the tapered surface 43, the ball 7 as a moving element is stabilized inside the rim 45. It is also preferable to form small protrusions 45X along the inner surface of the rim 45 so as to correspond to the number of balls so that each ball can be independent when the centrifugal force acts on the balls 7.

Further, as shown in FIGS. 10 to 12, small projections 43X for preventing rolling of the balls 7 are formed along the circumferential direction on the bottom surface of the moving element housing space 44 in correspondence with the number of the balls 7.
It is also good to prevent the ball 7 from straying in the circumferential direction.

[Effect of device]

As is clear from the above description, the cutting blade attaching device of the brush cutter of the present invention fixes the inner peripheral edge of the friction plate to the fastening table which is attached to the output shaft and fastens the cutting blade to the cutting blade holder. , The space inside the fastening table is provided with a moving element that expands to the outer circumference by the action of centrifugal force, and the movement of this moving element due to the centrifugal force causes the friction plate provided on the fastening table to be pressed against the cutting blade. It is configured so that it can be integrated with the output shaft and the fastening base by frictional force, and the centrifugal force generated by the centrifugal governor rotating with the fastening base is used to press the fastening base in the opposite direction to the screwing direction. Since it is configured, the following effects can be obtained.

(a). The cutting blade can be easily attached and detached without the use of tools by only screwing in and removing the fastening base.

(b) As the engine speed increases, the centrifugal force generated in the centrifugal governor causes the fastening table to be locked by the double nut, causing looseness between the fastening table and the output shaft. Absent.

(c). When the engine output is in the low range, for example, in the idling state, the power transmission between the cutting blade and the output shaft due to the friction plate is not directly performed, and the cutting blade is not in the forcible drive state. Yes, it is safe because the cutting blade does not rotate when the engine is started.

[Brief description of drawings]

The attached drawings show an embodiment of the present invention. FIG. 1 is a side sectional view of a main part, FIG. 2 is a sectional view of a fastening base, FIG. 3 is a plan view of the fastening base, and FIG. FIG. 5 is a side sectional view of an essential part according to the embodiment,
FIG. 6 is a sectional view taken along line VV of FIG. 4, FIG. 6 is a sectional side view of a main part of still another embodiment, FIG. 7 is a sectional view taken along line VII-VII of FIG. The top view by other examples of a fastening stand,
9 is a sectional view taken along the line IX-IX in FIG. 8, FIG. 10 is a plan view of a fastening base according to still another embodiment, and FIG.
FIG. 11 is a cross-sectional view taken along the line XI-XI. 1 ... Gear case 2 ... Output shaft, 2A ... Large diameter part, 2B ... Small diameter part 3 ... Cutting blade restraint, 3A ... Flange part, 3B ... Step part, 3C ...
… Boss part 4 …… Clamping base, 4A …… Female screw hole, 41 …… Lower surface, 42 …… Boss part, 43 …… Tapered surface, 44 …… Motor accommodating space, 45 ……
Rim, 45A …… Concave and convex 5 …… Leaf spring 6,7,8 …… Centrifugal governor, 61 …… Spindle, 62 …… Drive cam, 6
3 …… Governor arm, 64 …… Weight, 7 …… Ball

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. An operating main rod has an engine at one end thereof and a gear case at the other end thereof, and a cutting blade retainer attached to an output shaft of the gear case, and a cutting blade retainer attached to the output shaft. In a cutting blade mounting device for a brush cutter, which includes a cutting blade fastening base for mounting a cutting blade between the fastening blades, the fastening base is provided with a mounting portion that is screwed to the output shaft, and an accommodation space formed inside. A moving element that is stored and moves by centrifugal force, a friction plate that presses the cutting blade against the cutting blade restraint by the movement of this moving element, a centrifugal governor attached to the fastening base, and this centrifugal governor. The friction plate has an inner peripheral edge fixed to the fastening table and has a driving unit that pushes down the fastening table by the generated centrifugal force. The blade is frictionally fixed, and the drive unit is tightened by the movement of the centrifugal governor. A cutting blade mounting arrangement brush cutter, characterized by being configured to Domesuru so loosening the attachment portion by expanding between the cutting blade suppressed.