JPH0518901Y2 - - 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 particularly, to a mower blade attachment device that can reliably attach a mower blade to an output shaft of a gear case included in a brush cutter and can easily remove the mower blade.

[Prior Art] Most conventionally known brush cutters have a small engine as a power source attached to one end of the main operating rod, and the output of this engine is passed through the inside of the main operating rod. The power is input to the gear case installed at the other end of the main operating rod through the transmission shaft.
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 disc-shaped cutting blade holder is integrally fixed to the output shaft, and the cutting blade that is in close contact with the cutting blade holder is fitted into the output shaft, and the male threaded part formed on the output shaft is inserted into the output shaft. The mower blade is fastened to the output shaft by screwing in a fixing nut.

[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, replacing, or removing the cutting blade, it is necessary to tighten and loosen double nuts, which is very troublesome, and women and girls who have little understanding of machines may not be able to replace the cutting blade. Also, since the output shaft is normally rotated to the left, it is tightened using a left-handed screw, so if an inexperienced operator replaces the cutting blade, it may not be tightened securely. It is a danger. Therefore, with this invention, the cutting blade can be attached and detached with a relatively simple operation, and the faster the cutting blade rotates, the tighter the cutting blade can be fixed. The purpose is to provide a device.

[Means to solve the problem]

In order to achieve the above objectives, this invention has an engine at one end of the main operating rod, a gear case at the other end, a cutting blade retainer attached to the output shaft of this gear case, and an output In a mower blade mounting device for a brush cutter, which is equipped with a mower blade clamping base that is attached to the shaft and attaches the mower blade between this mower blade holder, the mower blade is drilled in the center and has a clearance around the output shaft. A fastening base having a plurality of pawls formed in a mounting hole with a diameter that allows insertion, and a screw base that is accommodated in the mounting hole of the fastening base and can be screwed onto the output shaft,
The clamping table has a slider that is housed in an internal space and moves toward the outer periphery due to centrifugal force and rises slightly, and a friction plate that presses the cutting blade against the cutting blade retainer by the movement of the slider. , the screw base has a receiving piece that expands in the radial direction, and when this receiving piece is stacked on the claw piece of the fastening base, both are rotated and integrated in the output axis direction by a click mechanism, and the friction plate and The present invention is characterized in that the cutting blade is fixed by friction between the cutting blade holder and the cutting blade at a predetermined number of revolutions or more.

[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 Once it is free, you can remove the fastening base, friction plate, and cutting blade by removing the screw base.

【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 a large diameter portion 2A of the output shaft 2 near the gear case 1 is provided with a spline groove, and a small diameter portion 2B is provided near the lower end of the output shaft 2. has a left-handed male thread. Further, on the lower surface of the gear case 1, a disc-shaped cutting blade retainer 3 is attached to the spline of the large diameter portion 2A and is 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 formed through B. The diameter of the stepped portion 3B of the boss portion 3C is determined to fit into the center hole _X1 of the cutting blade X. The small-diameter portion 2B of the output shaft 2 is loosely inserted into a mounting hole 4A, which serves as a mounting portion provided at the center of the fastening table 4. This fastening table 4 has a container shape with a gently curved lower surface 41.
A donut-shaped boss portion 42 into which a friction plate to be described later is fitted is formed on the upper side of the center, and the outer diameter of the boss portion 42 is slightly smaller than the outer diameter of the flange portion 3A of the cutting blade retainer 3. There is. Further, a donut-shaped space is formed on the outer periphery of the boss portion 42, and the bottom surface becomes gradually shallower toward the outer periphery to form a tapered surface 43.
The outer periphery of the slider accommodating space 44 is a rim 45, and the fastening table 4 is attached to the output shaft 2 on the outer periphery of the rim 45.
An unevenness 45A is provided for a finger rest when attaching and detaching the screw base 7 screwed into the screw base 7. The open surface of the slider housing space 44 is covered with a donut-shaped leaf spring 5 as a friction plate, and the inner peripheral edge 5A of the leaf spring 5 is press-fitted into the inner peripheral wall of the boss portion 42 of the fastening table 4. The outer peripheral edge is free and fits into the shallow step 45B formed in the rim 45, and is constantly trying to return to the flat state by the man. In addition, a plurality of balls 6, rolls, wedges, etc. (not shown) as movers are accommodated in the mover accommodation space 44, and the diameter of the balls 6 is closer to the center of the mover accommodation space 44. In the portion shown in FIG. 3, the dimensions are determined so that the portion hits the leaf spring 5 when moved in the outer circumferential direction along the tapered surface 43 without contacting the leaf spring 5, and a wedge effect can be expected. They can be lined up in a line along the outer periphery of 42. Further, the mounting hole 4A drilled in the center of the fastening base 4 has three claw pieces 46 projecting radially toward the center, one of which is provided with a female threaded hole 46A, and this female screw A caterpillar type click screw 47 is screwed into the hole 46A.
The inside of the ball 47A is hollow, and the ball 47A protrudes to the extent that it does not fall off due to the push spring 47B. The male threaded portion of the small diameter portion 2B of the output shaft 2 is connected to the female threaded portion 71A of the boss portion 71 provided at the center of the screw base 4.
The back of the boss portion 71 is a large diameter hole in which the large diameter portion 2A of the output shaft 2 is accommodated. Three claw-shaped receiving pieces 72 protruding in the radial direction are formed on the outer periphery of this screw base 7, and the claw pieces 46
Ball 47A
A notch 72A invaginated is formed. Therefore, by rotating the fastening base 4 by an appropriate angle with respect to the screw base 7 screwed to the output shaft 2, the claw piece 46 and the receiving piece 72 are overlapped. Receiving piece 7
In one of No. 2, the ball 47A of the click screw 47 catches the notch 72A of the receiving piece and can resist the direction of rotation. When attaching the cutting blade X to the output shaft ₂ , first screw the output shaft 2 into the center hole ₁ into the stepped portion 3B of the boss portion 3C of the cutting blade retainer 3, fit the tightening base 4 into the screw base 7, and remove the cutting blade retainer 3.
The flange portion 3A is brought into contact with the cutting blade X, and the leaf spring 5, which is a friction plate, is brought into contact with the cutting blade X. In this state, rotate the tightening table 4 a little and tighten the ball 4 on the side of the tightening table 4.
7A is fitted into the notch 72A on the screw base 7 side to complete the installation. Since the rotational speed of the engine is not very high when the engine is started, no large centrifugal force acts on the ball 6 even when the output shaft 2 rotates. Therefore, the ball 6 is in a floating state near the center of the mover housing space 44 in proportion to the magnitude of the centrifugal force applied. In this state, the output shaft 2, the fastening base 4,
Even if the screw head 7 is rotated, the cutting blade
It is not a direct integral combination with
Since the connection is based only on frictional contact, it functions as a clutch until enough frictional force is generated between the friction plate and the cutting blade to transmit torque to the cutting blade X, and the cutting blade X functions as a clutch. The blade X itself is in a rotating state where it is gently rotated. As the engine speed increases, the output shaft 2 also rotates at high speed, and the centrifugal force acting on the ball 6 increases, causing the ball 6 to move along the tapered surface 43 toward the outer periphery of the slider housing space 44. Moving. The ball 6 is located between the tapered surface 43 and the leaf spring 5, and moves toward the outer periphery in proportion to the magnitude of the centrifugal force, so if a centrifugal force that exceeds the elasticity of the leaf spring 5 acts, in other words, the engine When the leaf spring 5 rotates at a high speed, it is pushed up by the ball 6 against its own 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 to ,
The cutting blade X is rotated integrally with the cutting blade retainer 3, screw stand 7, and fastening stand 4. In the low rotational range of the engine, there is no centrifugal force acting on the ball 6 that strongly presses the leaf spring 5 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 existence of the mechanism, the mower blade X does not rotate, and conversely, when the mower blade X bites into the tree and becomes locked, the friction between the mower blade X and the output shaft 2, and eventually the engine This allows the sudden increase in load to be absorbed. In particular, when removing the cutting blade
Simply put your finger on 5A and rotate it a little to disengage it from the screw base 4 and remove the tightening base 4 downward.
The cutting blade X can be released from the output shaft 2, making the replacement work of the cutting blade X easy. The bottom surface of the mover housing space 44 of the fastening table 4, that is, the tape surface 43, is provided with a tape so that the ball 6 as a mover is stabilized inside the rim 45, as shown in FIGS. 4 and 5. It is also preferable to form small protrusions 45X along the inner surface of the rim 45 in accordance with the number of balls so that each ball can stand independently when centrifugal force is acting on the balls 6. Further, as shown in FIGS. 6 to 8, small protrusions 43X for preventing the balls 6 from rolling are formed along the circumferential direction on the bottom surface of the slider housing space 44, corresponding to the number of balls 6, It is also good to prevent the ball 6 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 movable element is provided, and the movable element is moved by centrifugal force, and the friction plate provided on the clamping base is pressed against the cutting blade, resulting in a frictional force that allows the mower to be integrated with the output shaft and the clamping base. At the same time, the clamping base is loosely fitted to the output shaft, and the clamping base, which is loosely fitted due to the screw base connected to the output shaft, is installed between the cutting blade retainer and the cutting blade rotates at a predetermined speed. Since the configuration is such that it can be pressed, the following effects can be obtained. (a) Since the friction 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) The centrifugal clutch provided on the engine crankshaft can be omitted and the output shaft and engine can be directly connected, simplifying the mechanism. (d) In particular, removing the fastening base from the screw base makes it easier to replace the cutting blade.

[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 figures are a sectional view taken along the line in FIG. 2, FIG. 4 is a plan view of another embodiment of the fastening base, FIG. 5 is a sectional view taken along the line in FIG. 4, and FIG. 6 is a further embodiment. FIG. 7 is a plan view of the fastening base according to the example, FIG. 7 is a sectional view taken along the line 6--FIG. 8, and FIG. 8 is a sectional view taken along the line 6-- FIG. 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...Tightening base, 4A...Mounting hole, 41...Bottom surface,
42...Boss portion, 43...Tapered surface, 44...Movers housing space, 45...Rim, 45A...Irregularities,
46...Female screw hole, 47...Click screw, 47
A...Ball, 47B...Press spring, 5...Leaf spring, 5A...Inner peripheral edge, 6...Ball, 7...Screw head, 71...Boss portion.

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. A mower blade attachment device for a brush cutter, which is equipped with a mower blade fastening base for attaching a mower blade, has a plurality of pawl pieces formed in a mounting hole that is drilled in the center and has a diameter that allows the output shaft to be inserted with sufficient clearance around the output shaft. It includes a tightening stand and a screw stand that is accommodated in the mounting hole of the tightening stand and can be screwed onto the output shaft,
The clamping table has a slider that is housed in an internal space and moves toward the outer periphery due to centrifugal force and rises slightly, and a friction plate that presses the cutting blade against the cutting blade retainer by the movement of the slider. , the screw base has a receiving piece that expands in the radial direction, and when this receiving piece is stacked on the claw piece of the fastening base, both are rotated and integrated in the output axis direction by a click mechanism, and the friction plate and A mower blade attachment device for a brush cutter, characterized in that the mower blade is fixed by friction between the mower blade holder and the mower blade at a predetermined number of revolutions or more.