JP2024158023A - Safety cover for grass cutter and grass cutter - Google Patents

Abstract

To provide a safety cover for a grass cutter which is less likely to cause dangerous flying objects such as pebbles, can prevent contact with surrounding people and buildings, and can effectively cut grass.
SOLUTION
The grass cutter safety cover has an attachment member for attachment to the grass cutter, a rotary blade cover portion which covers the tip of the rotary blade of the grass cutter, and a grass guide portion which is adjacent to the rotary blade cover portion and protrudes outward beyond the outer periphery of the rotary blade, the rotary blade cover portion and the grass guide portion having upper and lower plate members arranged at a predetermined distance, the tip sides of the upper and lower plate members have tip edges which are curved outwardly and the rear sides have edges which are curved inwardly and a tip protective member is provided along the tip edges connecting the upper and lower plate members.
[Selected figure] Figure 2

Description

This invention relates to a safety cover for a lawnmower that covers the tip of the lawnmower's rotary blade.

Graders with rotating blades are prone to coming into contact with pebbles and other debris during operation, which can be dangerous if debris is deflected by the rotating blade and strikes the worker or people nearby. There have also been many accidents in which the rotating blades have come into contact with people, causing injury, or come into contact with walls or trees, causing damage.

Cited documents 1 and 2 describe providing a cover behind the rotary blade to prevent debris from flying toward the user. Cited document 3 describes a retrofit protective cover unit for a lawnmower that completely covers the cutting blade unit.

JP 2023-43107 A JP 2023-16652 A Registered Utility Model Publication No. 3241211

The anti-scattering covers described in Patent Document 1 and Cited Document 2 can prevent flying debris from flying towards the user. However, these do not prevent flying debris from occurring, but rather catch the flying debris. While pieces of grass are not particularly dangerous, pebbles and other debris can be dangerous if they hit people other than the user, and contact with pebbles can damage the linear cutter and rotary blade. In addition, the front of the linear cutter is completely open, so there is a risk of contact with nearby people or buildings during operation.

The protective cover unit described in Cited Document 3 covers the entire top and sides, which is thought to be more effective at preventing the spread of flying debris. However, it still cannot prevent the blade from coming into contact with pebbles or gravel. Because the cover prevents the user from seeing underneath, there is a risk that the blade may hit a pebble without noticing. Also, if the entire periphery is covered, it becomes difficult for the blade to come into contact with the grass, making it impossible to mow the grass.

The objective of this invention is to provide a safety cover for a lawnmower that is less likely to scatter dangerous debris such as pebbles, prevents contact with nearby people and structures, and allows for effective mowing.

In order to solve the above problems, the grass cutter safety cover of the present invention comprises an attachment member for attaching to the grass cutter;
A rotary blade cover that covers a tip of the rotary blade of the grass cutter;
A grass guide portion is adjacent to the rotary blade cover portion and protrudes outward from the outer periphery of the rotary blade,
The rotary blade cover and the grass guide have upper and lower plates arranged parallel to each other at a predetermined interval,
The tip sides of the upper plate and the lower plate have tip edges that are curved outwardly,
The rear side has an inwardly convex curved edge,
A tip protection member is provided along the tip edge connecting the upper plate material and the lower plate material.

The mounting member has a main pipe connecting member that contacts the main pipe of the grass cutter, and a fixing member that detachably connects the main pipe connecting member to the main pipe,
The mounting member is separated into a main pipe connecting member side and a rotary blade cover side, and the main pipe connecting member side and the rotary blade cover side are detachably connected by a screw,
The leading edge of the upper plate and the lower plate has an arc having a radius approximately equal to the distance from the rear end of the mower to the leading edge of the rotary blade,
The rear edge of the upper plate and the lower plate has two arcs having a radius approximately equal to the radius of the rotary blade;
An outwardly expanding grass introduction space can be formed between the rear edge and the outer periphery of the rotary blade.

The grass cutter of the present invention comprises a main pipe, a rotary blade provided at a tip end of the main pipe, a drive source provided at a rear end of the main pipe for driving the rotary blade, and a grass cutter safety cover attached to the main pipe,
The grass cutter safety cover has an attachment member attached to a main pipe, a rotary blade cover part that covers the tip of the rotary blade, and a grass guide part that is adjacent to the rotary blade cover part and protrudes outward beyond the outer periphery of the rotary blade,
The rotary blade cover and the grass guide have upper and lower plates arranged parallel to each other at a predetermined interval,
The upper plate and the lower plate have a leading edge that is convex outwardly and is an arc with a radius approximately equal to the distance from the rear end of the mower to the tip of the rotary blade, and a trailing edge that is convex inwardly and has two arcs with radii approximately equal to the radius of the rotary blade,
An outwardly expanding grass introduction space is formed between the rear edge and the outer periphery of the rotary blade.

The grass cutter safety cover of this invention can prevent pebbles and other objects from flying and can prevent the rotary blade from coming into contact with people or buildings in the vicinity. It also improves grass cutting efficiency, reducing energy consumption and working time.

FIG. FIG. 2 is a plan view showing the grass cutter safety cover. FIG. 4 is an enlarged plan view showing the vicinity of a dividing portion of the band-shaped member. FIG. FIG. FIG.

A description of an embodiment of the present invention will be given with reference to the drawings. This is a perspective view of a grass cutter. The grass cutter 20 has a main pipe 21 that serves as a pole, with a rotary blade 22 at the tip of the main pipe 21 and a drive source 23 at the rear end for driving the rotary blade. A waist rest 24 is provided near the rear end, and a handle 25 is provided slightly forward of the waist rest 24. A shaft (not shown) is provided inside the main pipe 21 as a transmission member, and power is transmitted to the rotary blade 22 by the drive source 23.

The above is the main structure of a typical grass cutter. The operator holds the handle 25, places his/her hips against the hip rest 24, and cuts the grass by placing the rotary blade 22, which rotates due to the power of the drive source 23, against the grass. At this time, the operator moves the handle 25 left and right to swing the rotary blade 22 widely as he/she moves forward. In this invention, the grass cutter safety cover 1 is attached at the position where the rotary blade 22 is located.

The grass cutter safety cover will now be described. Figure 2 is a plan view of the grass cutter safety cover, and Figure 3 is a side view of the same. The grass cutter safety cover 1 has an attachment member 2 for attachment to the grass cutter 20, a rotary blade cover part 3 that covers the tip of the rotary blade 22 of the grass cutter 20, and a grass guide part 4 that is adjacent to the rotary blade cover part 3 and protrudes outward beyond the outer periphery of the rotary blade 22.

The mounting member 2 may be any member capable of being firmly fixed to the grass cutter safety cover 1 of the grass cutter 20, but here, an example in which the mounting member 2 is attached to the main pipe 21 of the grass cutter 20 will be described. A half-pipe-shaped main pipe connecting member 5 having an inner peripheral surface capable of contacting the outer peripheral surface of the main pipe 21 is provided. In addition, a portion that prevents interference with the rotating shaft 26 is formed at a location that should overlap with the rotating shaft 26 of the grass cutter 20. For example, a hole through which the rotating shaft 26 can pass may be provided. Here, a cap-shaped member 6 is provided that forms a space in which the rotating shaft 26 can be stored without contacting it, and further, following the cap-shaped member 6, a strip-shaped member 7 extends parallel to the rotational surface of the rotating blade 22 toward the tip of the rotating blade 22.
The grass cutter safety cover 1 may be provided with a hinge portion so that the bending angle can be adjusted. For example, a hinge portion using a through bolt and nut can be provided at the connection between the cap-shaped member 6 and the band-shaped member 7a. In the grass cutter 20, the axis of the main pipe 21 and the rotation plane of the rotary blade 22 are not aligned in a straight line, but are bent at a certain angle, which varies depending on the model of grass cutter. If a hinge portion is provided, the angle can be adjusted to suit the grass cutter to which it is attached, and fixed at that angle by tightening the nut.

The band-shaped member 7 extends to the rotary blade cover part 3. The band-shaped member 7 may be formed from a single member, in which case the grass cutter safety cover 1 is formed as a single unit. In this example, the band-shaped member 7 is divided into an attachment member side 7a connected to the cap member 7 and a rotary blade cover part side 7b connected to the rotary blade cover part 3, and these are overlapped at their ends and detachably connected by two locking screws 8. Here, an adjustment part 17 such as a long hole along the length is formed on either the attachment member side 7a or the rotary blade cover part side 3b, so that the amount of protrusion of the rotary blade cover part 3 from the attachment member 2 can be adjusted.

Figure 4 is an enlarged plan view showing the vicinity of the split portion of the band-shaped member, and Figure 5 is an exploded side view of the same. In this example, a slit 17 is provided in the band-shaped member 7a on the mounting member side, which serves as an adjustment portion. The tip of the band-shaped member 7a on the mounting member side is open, and the slit 17 is formed from this slit toward the cap member. This band-shaped member 7a is on the upper side when overlapped. On the other hand, the rotary blade cover part side 7b is on the lower side when overlapped. Two male threads 8a are provided on the upper surface of the rotary blade cover part side 7b. These male threads 8a are fixed vertically to the upper surface of the rotary blade cover part side 7b by welding. The two male threads 8a are passed through the slits 17, a rectangular plate-shaped washer is attached from above the mounting member side 7a, and the nut 8b is further tightened to firmly connect the mounting member side 7a and the rotary blade cover part side 7b. In this way, in this example, the male threads 8a and the nut 8b form a set screw. By welding the male thread portion 8a to the rotary blade cover side 7b, no parts protrude from the underside of the rotary blade cover side 7b that faces the rotary blade 22, and a sufficient distance can be maintained between the rotary blade 22.

Two pipe stays 9 are attached to the main pipe connection member 5 of the mounting member 2, and are fixed to the main pipe 21 by stay fixing screws 10. One stay fixing screw 10 is attached to the rear end of the main pipe connection member 5, and the other is attached near the cap member 7. This firmly fixes the grass cutter safety cover 1 to the main pipe 21 so that it does not rotate or move back and forth.

The rotary blade cover section 3 and grass guide section 4 will now be described. These are parts that are constructed as an integrated unit. The upper plate material 11 and the lower plate material 12 are provided at a specified distance. This distance is a distance that allows the rotary blade 22 to fit between them without touching them, and is preferably between 10 mm and 20 mm. The width of the upper plate material 11 and the lower plate material 12, i.e., the distance between both ends of the tip edge 13, is the same as the diameter of the rotary blade 22. The upper plate material 11 and the lower plate material 12 are made of metal plates such as steel plates with a thickness of between 0.5 mm and 2.0 mm.

The leading edge 13 of the upper plate 11 and the lower plate 12 is a curved line seen from above that is convex outward, i.e. the central part is convex toward the leading edge. This curve is preferably a circular arc, and in this example, the leading edge 13 is an arc with a radius that is approximately the same length as the distance from the rear end of the grass cutter 1 to the tip of the rotary blade 22.

The rear edge 14 of the upper plate 12 and the lower plate 13, which face the leading edge 13, will now be described. An inwardly convex curve, i.e., a curve convex toward the leading edge, is formed on each of the two ends of the trailing edge 14. This curve is also preferably an arc, and its radius is preferably smaller than the radius of the arc of the leading edge 13. Here, this curve of the trailing edge 14 is an arc with a radius roughly the same as the radius of the rotary blade 22.

A vertical plate is provided between the upper plate 11 and the lower plate 12 along the leading edge 13 as a leading edge protection member 15. The lower plate 12 is supported by the upper plate 11 by this leading edge protection member 15. The leading edge 13 side is also in a closed state by the leading edge protection member 15. On the other hand, there is no such member at the rear edge 14, and it is in an open state.

The upper plate material 11, the lower plate material 12 and the tip protection member 15 form an integrated member, the center of which becomes the rotary blade cover part 3. In this area, the tip of the rotary blade 22 is not exposed and does not come into contact with the outside.

The grass guide section 4 continues on both sides of the rotary blade cover section 3. The grass guide section 4 is shaped like a sickle and protrudes outward from the outer circumference of the rotary blade 22. Between the arc of the rear edge 14 and the outer circumference of the rotary blade 22, there is a space that widens outward, forming a grass introduction space 16.

As described above, the shapes of the rotary blade cover part 3 and the grass guide part 4 are selected according to the size of the rotary blade 22 of the grass cutter 1. As typical grass cutters mainly use ones with diameters of 230 mm and 255 mm, two types of rotary blade cover part 3 and grass guide part 4 are provided in shapes to suit the respective sizes.

Next, we will explain the operation and usage of this grass cutter safety cover. The grass cutter safety cover 1 can be provided as a separate component from the main body of the grass cutter 20. Here, we will explain using such an example.

The mounting member side 7a and the rotary blade cover side 7b of the band plate-like member 7 are separated. Then, the main pipe connection member 5 is placed against the main pipe 21, and the cap-like member 5 is positioned so as to cover the rotary shaft 26. The two pipe stays 9 are attached to the main pipe connection member 5, and the main pipe connection member 5 is fixed to the main pipe 21 by tightening them with the stay fixing screws 10.

The rotary blade cover part side 7b of the band plate member 7 is aligned with the mounting member side 7a, and the tip of the rotary blade 22 is placed between the upper plate material 11 and the lower plate material 12 of the rotary blade cover part 3. Then, while adjusting the position of the rotary blade cover part 3 with the adjustment part 17, the set screw 8 is tightened to connect the mounting member side 7a and the rotary blade cover part side 7b. In this way, the grass cutter safety cover 1 is attached to the grass cutter 20. In this example, the adjustment part 17 is a slit with an open tip, so the rotary blade cover part side 7b can be easily attached.

The grass cutting operation can be performed in almost the same way as with a conventional grass cutter. The drive source 23 is driven to rotate the rotary blade 22, and the handle 25 is turned left and right to swing the rotary blade 22 and move forward little by little.

When the grass cutter 1 is swung from side to side, the rotary blade cover part 3 and the grass guide part 4 are also swung from side to side. For example, when it is swung to the right, the right grass guide part 4 moves to the right while pushing aside the grass. The tip part moves along an arc whose radius is approximately the distance from the rear end of the grass cutter 1 to the tip of the rotary blade 22. Grass ahead of this arc is left in front of the tip edge 13 without being cut. Here, the tip edge 13 is also an arc whose radius is approximately the distance from the rear end of the grass cutter 1 to the tip of the rotary blade 22, so each point on the curve of the tip edge 13 moves along the trajectory of the tip caused by the swinging of the grass cutter 1. Therefore, it moves smoothly with almost no force from the grass remaining in front. The grass in front does not get caught.

On the other hand, grass that is in front of the arc enters the grass introduction space 16 between the rear edge 14 and the outer periphery of the rotary blade 22, and is guided to the intersection of the rear edge 14 and the outer periphery of the rotary blade 22. It is then cut by the rotary blade 22, and the cut grass slides over the upper plate 11 to the other side and falls.

Figure 6 is an enlarged view of arrow A, showing the state in which grass is being cut. The grass x is guided to the intersection of the rear edge 14 and the outer periphery of the rotary blade 22, and one side (the right side in this figure) is pressed against it by the upper plate 11 and the lower plate 12. The rotary blade 22 then hits it from the opposite side (the left side in this figure).

Because the grass x is soft and flexible, in the case of a normal lawnmower, it tilts to avoid the blade and tries to get under the rotary blade 22. However, in the lawnmower safety cover of the present invention, the grass x is held down by the upper plate material 11 and the lower plate material 12, and the rotary blade 22 cuts into it vertically, so it is cut reliably. The cutting efficiency is good, and the grass can be cut effectively even if the rotation speed of the rotary blade 22 is low. This makes it possible to reduce the fuel and electricity consumed by the drive source 23. In addition, the drive source 23 can be made small with low output and torque, making the lawnmower lightweight and inexpensive. Furthermore, the operating time can be shortened.

Even if the grass is already leaning, it is lifted by the upper plate 11 and the lower plate 12 and pressed vertically against the rotary blade 22. The rotary cover part 3 is provided on both the left and right sides of the rotary blade cover part 3, so it can be cut equally well even when swung to the left.

The tip of the rotary blade 22 is the part most likely to come into contact with surrounding objects, but it is covered by the rotary cover part 3 and does not come into contact with objects above or below. This prevents injury to people from coming into contact with it. It also prevents contact with trees, walls, etc. in the work area, preventing damage to these objects or the rotary blade. Dangerous flying debris is also not generated by contact with pebbles, etc. Furthermore, a tip protection member 15 is provided on the tip edge 13, so it is less likely to get entangled even if strings, wires, etc. are lying on the ground.

When replacing the rotary blade 22, remove the set screw 8 and separate the mounting member side 7a and the rotary blade cover side 7b of the strip-shaped member 7. This allows the rotary blade cover 3 and grass guide 4 to be easily removed. The underside of the rotary blade 22 is open, so the old rotary blade 22 can be removed from the rotating shaft 26 by normal procedures and a new rotary blade can be attached. By connecting the mounting member side 7a and the rotary blade cover side 7b with the set screw 8, grass cutting can be resumed. By making the adjustment part 17 a slit with an open tip as shown in Figure 4, the rotary blade cover side 7b can be easily attached and detached by simply loosening the nut 8b without having to completely remove it from the male threaded part 8a.

1. Grass cutter safety cover 2. Mounting member 3. Rotary blade cover portion 4. Grass guide portion 5. Main pipe connection member 6. Cap-shaped member 7. Band-shaped member 8. Set screw 8a, male thread portion 8b, nut 9. Pipe stay 10. Stay fixing screw 11. Upper plate material 12. Lower plate material 13. Front edge 14. Rear edge 15. Front end protection member 16. Grass introduction space 17. Adjustment portion (slit)
18. Washer 20. Grass trimmer 21. Main pipe 22. Rotary blade 23. Driving source 24. Waist rest 25. Handle 26. Rotary shaft x. Grass

Claims (3)

A mounting member to be attached to the grass cutter;
A rotary blade cover that covers a tip of the rotary blade of the grass cutter;
A grass guide portion is adjacent to the rotary blade cover portion and protrudes outward from the outer periphery of the rotary blade,
The rotary blade cover and the grass guide have upper and lower plates arranged parallel to each other at a predetermined interval,
The tip sides of the upper plate and the lower plate have tip edges that are curved outwardly,
The rear side has an inwardly convex curved edge,
A safety cover for a lawnmower is provided with a tip protection member that connects an upper plate material and a lower plate material along the tip edge. The mounting member has a main pipe connecting member that contacts the main pipe of the grass cutter, and a fixing member that detachably connects the main pipe connecting member to the main pipe,
The mounting member is separated into a main pipe connecting member side and a rotary blade cover side, and the main pipe connecting member side and the rotary blade cover side are detachably connected by a screw,
The leading edge of the upper plate and the lower plate has an arc having a radius approximately equal to the distance from the rear end of the mower to the leading edge of the rotary blade,
The rear edge of the upper plate and the lower plate has two arcs having a radius approximately equal to the radius of the rotary blade;
2. A grass cutter safety cover according to claim 1, wherein an outwardly expanding grass guide space is formed between the rear edge and the outer periphery of the rotary blade. The grass cutter includes a main pipe, a rotary blade provided at a tip of the main pipe, a drive source provided at a rear end of the main pipe for driving the rotary blade, and a grass cutter safety cover attached to the main pipe,
The grass cutter safety cover has an attachment member attached to a main pipe, a rotary blade cover part that covers the tip of the rotary blade, and a grass guide part that is adjacent to the rotary blade cover part and protrudes outward beyond the outer periphery of the rotary blade,
The rotary blade cover and the grass guide have upper and lower plates arranged parallel to each other at a predetermined interval,
The upper plate and the lower plate have a leading edge that is outwardly convex and is an arc with a radius approximately equal to the distance from the rear end of the grass cutter to the tip of the rotary blade, and a trailing edge that is inwardly convex and has two arcs with radii approximately equal to the radius of the rotary blade,
This grass cutter has a grass introduction space that widens outward between the rear edge and the outer periphery of the rotary blade.

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