JPH0518902Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This invention relates to a mower blade attachment device for a brush cutter, and more specifically, a mower blade attachment device that securely and safely attaches the mower blade to the output shaft of the gear case of the brush cutter, and also allows for easy removal for replacement. Regarding equipment.

[Conventional technology]

In most of the conventionally known brush cutters, a small engine is attached to one end of the main operating rod as a power source, and the output of this engine is transmitted through a transmission shaft that passes through the inside of the main operating rod. is input to the gear case provided at the other end of the main operating rod.
The cutting blade is configured to be fastened and fixed by a cutting blade retainer attached to the output shaft of the gear case and a fastening washer for the cutting blade. More specifically, a disk-shaped cutting blade holder is integrally fixed to the output shaft, and the cutting blade that comes into close contact with the cutting blade holder is fitted into the output shaft, and a male threaded portion formed on the output shaft is formed. The cutting blade is tightened to the output shaft by screwing in a fixing nut to the output shaft.

[Problem that the idea aims to solve]

By the way, mower blades can rotate at high speeds of several thousand revolutions per minute, so if the mower blades fall off while rotating at high speeds, the mower blades may fly around while rotating and cause an unexpected accident. will occur. Therefore, the cutting blade is often fastened to the output shaft with a double nut. Therefore, when installing or replacing the cutting blade, it is necessary to tighten and loosen the double nuts, which is very troublesome, and women and girls with little knowledge of machines may not be able to replace the cutting blade. Since the output shaft is rotated to the left, it is fastened with a left-hand thread, so if an inexperienced operator replaces the cutting blade, the fastening may not be done reliably, which is extremely dangerous. Therefore, with this invention, it is possible to attach and detach the cutting blade with a relatively simple operation.Moreover, the faster the cutting blade rotates, the tighter the cutting blade can be tightened and fixed, and the replacement work of the cutting blade is easy. The object of the present invention is to provide a mounting device that allows for

[Means to solve the problem]

In order to achieve the above-mentioned purpose, this invention includes a mounting base that is attached to the output shaft by screw connection, and a click stop mechanism that is spline-coupled to the output shaft and is connected to the mounting base. a clamping base, and an operation ring fitted onto the clamping base and biased to push out the ball of the click stop mechanism, and the clamping base is rotated. It has a mover that can be moved outward by the generated centrifugal force, and a friction plate that is pressed against the cutting blade by the outward movement of the mover, and the operating ring is pulled down along the output shaft against a push spring. Accordingly, the clamping base can be released from the mounting base by releasing the clip stop mechanism, and the cutting blade is fixed by friction between the friction plate and the cutting blade retainer at a predetermined rotation speed or more. It is characterized by:

[Effect]

In the mower blade mounting device of this invention, the slider housed in the internal space of the clamping base moves in the radial direction due to the centrifugal force generated by the high-speed rotation of the output shaft, and the friction plate rises due to this movement. When the cutting blade is strongly tightened against the cutting blade retainer and the rotation of the output shaft decreases, the tightening force also decreases as the centrifugal force decreases, and the relationship between the output shaft and the cutting blade becomes If you want to remove the cutting blade, simply pull down the operating ring to release the binding of the cutting blade.

【Example】

Embodiments of this invention will be described below with reference to the attached drawings. First, FIG. 1 is a partial cross-sectional view showing the cutting blade of a brush cutter and the output shaft portion of a gear case to which it is attached. Reference numeral 1 indicates a gear case that includes, for example, a reduction mechanism, and the lower surface of the gear case 1 has a A stepped output shaft 2 is provided protrudingly, and the output shaft 2 has a large diameter portion 2A near the gear case 1, a small diameter portion 2B near the lower end, and a spline groove is carved in the large diameter portion 2A. A left-handed male thread is formed in the small diameter part 2B. Further, on the lower surface of the gear case 1, a disc-shaped cutting blade retainer 3 is fitted into the spline portion of the large diameter portion 2A and placed in a closed state.
has a stepped portion 3 at the center of the flange portion 3A on its periphery.
A boss portion 3C is provided via B. The diameter of this stepped portion 3B is determined to fit into the center hole _X1 of the cutting blade X. A substantially cylindrical mounting base 4 is screwed into the small diameter portion 2B of the output shaft 2 through a female threaded hole 4A provided at the center thereof as a mounting portion. A straight portion 41, a notch 42, and a spline portion 43 are formed on the outer peripheral surface of the mounting base 4 from above. A shaft hole 4B into which the large diameter portion 2A of the output shaft 2 is fitted is formed at the center of the upper end surrounded by the straight portion 41. A fastening base 5 is fitted into the spline portion 43 and the straight portion 41 of the mounting base 4 . This fastening table 5 has a window hole 51 through which a ball (to be described later) can be seen in the center hole 5A, and a spline part 52, and a flange-type spring receiver 53 is screwed or press-fitted into the outer peripheral surface opposite to the spline part 52. It is integrated by The fastening table 5 has a container shape as a whole, and has a boss portion 54 in the center, a circular step portion 55 is formed on the upper end surface of the boss portion 54, and a bottom surface is formed around the boss portion 54. A tapered surface 56 is formed on the outer circumference, and a mover housing space 57 is formed for accommodating a ball as a mover with a shallow outer circumference. A concave and convex portion 58A for resting a finger is formed. The diameter of the boss portion 54 is approximately equal to that of the flange portion 3A of the cutting blade retainer 3, and the stepped portion 55 is located inside the flange portion 3A. Further, a shallow step portion 58B is provided at the upper end of the rim portion 58.
, and the outer circumferential edge of a donut-shaped leaf spring 6 serving as a friction plate whose inner circumferential edge 61 is fitted and fixed to the stepped portion 55 of the boss portion 54 is located. This leaf spring 6
has a flat plate shape due to its self-elasticity, and closes the movable element accommodation space 57 to restrain the balls 7, rolls, and wedges as movable elements accommodated in the movable element accommodation space 57. The diameter of this ball 7 is set so that it does not come into contact with the leaf spring 6 at the inner periphery of the slider housing space 57 and can push up the leaf spring 6 at its outer periphery. A deep groove 59 is provided in the bottom surface of the fastening base 5 along the diameter direction, and the lower ends of the mounting base 4 and the fastening base 5 are exposed in this groove 59. There is. Furthermore, a cylinder-shaped operation ring 8 is fitted around the outer periphery of the spring receiver 53 of the fastening base 5, and a cylinder portion 51A having a window hole 51 and a spline portion 52 is housed in the space at the center thereof. An end 81A of the push spring 81 hits the spring receiver 53, and the other end hits the inner step 82 of the operating ring 8, thereby pushing the operating ring 8 upward. A ball 83 with a click stop function is housed in the center of the operating ring 8.
3 is fitted into the notch 42 of the mounting base 4 through the window hole 51 to form a click stop mechanism, and when the operating ring 8 is pulled down, a small evacuation space 84 formed in the center of the operating ring 8 is inserted. I am now able to move out towards the future. The ball 83 with a click stop function provided on the operation ring 8 of the above embodiment is composed of a cam and a pawl, and the cam and pawl are constantly recessed through the window hole 51 provided on the inner circumferential wall of the fastening base 5. The protruding cam and pawl are inserted into the notch 42 of the mounting base 4.
It is also possible to configure a click stop mechanism that engages with the operating ring 8, and to accommodate it in a small retraction space 84 formed at the center of the operating ring 8 when the operating ring 8 is pulled down. When the cutting blade X is attached to the output shaft 2, the mounting base 4 is
The upper edge of the upper end portion is screwed into the female screw hole 4A of the
Apply it to the boss part 3C of the cutting blade retainer 3, then press the cutting blade
into the stepped portion 3B, and attach the fastening base 5 to the mounting base 4.
The leaf spring 6 is brought into contact with the cutting blade X by spline connection. Since the rotational speed of the engine is not very high when the engine is started, even when the output shaft 2 rotates, no large centrifugal force acts on the ball 7, and the ball 7 is located near the center of the mover housing space 57, so that the centrifugal force applied to the ball 7 is not very high. It is in a floating state in proportion to the magnitude of the force. In this state, the output shaft 2 and the fastening base 5
Even if it is rotated, the cutting blade Until sufficient frictional force is generated between the friction plate and the cutting blade to cause the cutting blade to move, it functions as a clutch, and the cutting blade X itself is in a rotational state where it is only gently rotated. . As the engine speed increases, the output shaft 2 also rotates at high speed, and the centrifugal force acting on the ball 7 increases, causing the ball 7 to move along the tapered surface 56 to the outer periphery of the slider housing space 57. Moving. The ball 7 is located between the tapered surface 56 and the leaf spring 6 and moves toward the outer periphery in proportion to the magnitude of the centrifugal force, so when a centrifugal force that exceeds the elasticity of the leaf spring 6 acts, in other words, the ball 7 moves at high speed. When the leaf spring 6 is in a rotating state, it is pushed up by the ball 7 against its own elasticity, and a strong frictional force is generated between the leaf spring 6 and the cutting blade X. This frictional force causes the output shaft 2 and the cutting blade The cutting blade X is rotated integrally with the blade retainer 3 and the fastening base 5. In the low rotational range of the engine, there is no centrifugal force acting on the ball 7 that strongly presses the leaf spring 6 against the cutting blade X, so there is a kind of centrifugal clutch between the cutting blade X and the output shaft 2. Due to the presence of the mechanism, the cutting blade X does not rotate, and conversely, when the cutting blade Friction can absorb sudden increases in load. The bottom surface of the slider housing space 57 of the fastening table 5, that is, the tapered surface 56, is provided with a groove so that the ball 7 as a slider is stabilized inside the rim portion 58, as shown in FIGS. 7 and 8. It is also preferable to form small protrusions 58X along the inner surface of the rim in accordance with the number of balls so that each ball can become independent when centrifugal force is acting on the balls 7. Furthermore, as shown in FIGS. 9 to 11, a small protrusion 58Y to prevent the ball 7 from rolling is formed along the circumferential direction on the bottom surface of the slider housing space 57.
It is also preferable to form the ball 7 according to the number of balls 7 to prevent the ball 7 from straying in the circumferential direction.

[Effect of the idea]

As is clear from the above explanation, the mowing blade attachment device of the brush cutter of this invention is attached to the output shaft and tightens the mowing blade against the mowing blade retainer, and the clamping base is expanded to the outer periphery due to the action of centrifugal force. A slider is provided, and the movement of the slider due to centrifugal force causes the friction plate provided on the clamping base to be pressed against the cutting blade, thereby making it possible to integrate with the output shaft and the clamping base. The clamping base is integrated with a click stop mechanism for the mounting base screwed onto the output shaft through spline connection, and the click stop mechanism can be released by operating an operating ring fitted to the clamping base. By configuring it, you can get the following effects: (a) Since the frictional force for fixing the cutting blade increases in proportion to the increase in engine output, the cutting blade can be fixed securely. (b) When the engine output is low, for example when idling, direct power transmission is cut off between the cutting blade and the output shaft, so the cutting blade rotates only slightly, and when the engine starts, the cutting blade rotates as the engine rotates. It is safe as it does not rotate. (c) In particular, since the clamping base is only attached in the axial direction to the output shaft mounting base by a click stop mechanism, the clamping base can be removed simply by pulling down the operating ring. The cutting blade can be removed with one touch. (d) The centrifugal clutch provided on the engine crankshaft can be omitted and the output shaft and engine can be directly connected, simplifying the mechanism.

[Brief explanation of the drawing]

The attached drawings show an embodiment of this invention, in which Figure 1 is a side sectional view of the main part, Figure 2 is a bottom view of the fastening base, and Figure 3 is a bottom view of the fastening base.
The figure is a sectional view taken along line - in figure 2, figure 4 is a plan view of the mounting base, figure 5 is a sectional view taken along line - in figure 4, figure 6 is a bottom view of the same, and figure 7 is a fastener. 8 is a sectional view taken along the line of FIG. 7, FIG. 9 is a plan view of a fastening table according to another embodiment, and FIG. 10 is a sectional view taken along the line of FIG. 1. FIG. 11 is an enlarged sectional view taken along the line of FIG. 9. 1...Gear case, 2...Output shaft, 2A...Large diameter section, 2B...Small diameter section, 3...Mower blade retainer, 3A...
...Flange part, 3B...Step part, 3C...Boss part,
4... Mounting base, 4A... Female screw hole, 41... Straight part, 42... Notch, 43... Spline part, 5... Fastening base, 5A... Center hole, 51... Window hole, 52... ... Spline part, 53 ... Spring receiver, 5
4...Boss part, 55...Step part, 56...Tapered surface, 57...Movers housing space, 58...Rim part,
58A... unevenness, 59... concave groove, 6... plate spring,
61...Inner peripheral edge, 7...Ball, 8...Operation ring,
81... Pressing spring, 81A... End of pressing spring, 82
...Inner peripheral step, 83...Ball.

Claims (1)

[Scope of utility model registration request] The main operating rod has an engine at one end, a gear case at the other end, and a cutting blade holder attached to the output shaft of this gear case. In a mower blade mounting device for a brush cutter, which is equipped with a mower blade fastening base to which the mower blade is attached, the mower blade is attached to the output shaft by a screw connection, and the attachment base is spline-coupled to the output shaft. The tightening device comprises a fastening base having a click stop mechanism, and an operation ring fitted onto the fastening base and biased to push out a ball of the click stop mechanism. The mounting base has a slider that can be moved outwardly by centrifugal force generated by rotation, and a friction plate that is pressed against the cutting blade by the outward movement of the slider. By being pulled down along the axis, the clip stop mechanism can be released and the clamping base can be released from the mounting base, and the cutting blade is fixed by friction between the friction plate and the cutting blade retainer at a predetermined rotation speed or more. A mower blade attachment device for a brush cutter, characterized in that it is configured as follows.