JPH0642432Y2 - Lawn mower cutting blade device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a cutting blade device of a lawn mower, and more particularly to a structure of a cutting blade portion of two vertically stacked cutter blades that rotate substantially horizontally.

[Prior Art] In a lawn mower in which a cutter blade that rotates substantially horizontally is housed in a cutter housing with an open lower surface, two cutter blades are stacked one above the other and the cutting blade of the upper cutter blade is located below. By locating the blade in front of the cutting blade in the direction of rotation, it is possible to mow the grass twice or to eliminate the uncut portion in the model in which a plurality of cutter blades are arranged side by side. It is known from the specification of No. 2,760,327 and Japanese Utility Model Publication No. 64-6035.

[Problems to be solved by the invention] However, since the grass that has been mowed once with the mowing blade of the upper cutter blade is laid down by the rotating wind of the blade, the second mowing with the mowing blade of the lower cutter blade is not always necessary. There is room for improvement in this respect, as it is not something that is certainly done.

Therefore, an object of the present invention is to improve lawn mower having the above-mentioned upper and lower cutting blades having upper and lower cutter blades which are positioned forward in the rotational direction, improve the finish of the lawn, and cut the grass. It is to provide a cutting blade device having improved properties.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a cutting blade for an upper cutter blade, which is provided with a cutter blade that rotates substantially horizontally and that is vertically stacked and provided at a lower end portion of a substantially vertical rotation shaft. In a lawn mower positioned in front of the cutting blade of the lower cutter blade in the rotation direction, the rotation of the cutting blade portion of the lower cutter blade is larger than the width of the cutting blade portion of the upper cutter blade in the rotation direction. The width in the direction is widened to form a ventilation path between the upper and lower cutting blade portions, and a rear side portion in the rotation direction of the cutting blade portion of the lower cutter blade is used for the wind in the ventilation passage. It is characterized in that it is formed in a substantially upward standing portion that changes its direction upward.

More specifically, the cutting blade of the upper cutter blade is projected forward about 5 mm in the rotational direction than the cutting blade of the lower cutter blade, and / or the lower cutter blade It is characterized in that a substantially upper standing portion is made higher than the cutting blade portion of the upper cutter blade.

[Operation] The upper and lower cutter blades, which are positioned in the front in the rotational direction, overlap each other in the vertical direction, and the cutter blade has an air passage between the two cutting blade portions, and the rear blade portion in the rotational direction of the lower cutting blade portion. Since it is a substantially upward standing portion, the grass grass mowed once by the preceding upper cutting blade flows through the ventilation path between the upper and lower cutting blade portions, and the negative wind of the wind flowing upwards by the substantially upper standing portion. It is pulled up by the pressure action, and is cut again by the next lower cutting blade.

In addition to surely cutting the turfgrass twice and chopping it, the mowed turfgrass blows from the ventilation path between the upper and lower cutting blades along the substantially upward standing portion of the lower cutting blade. It is thrown upwards, then drops, and is finely cut again by the upper and lower cutting blades.

In addition, from various experiments, when the upper cutting blade is projected forward about 5 mm in the rotational direction than the lower cutting blade, and the substantially upward standing portion on the rear side of the ventilation passage is set higher than the upper cutting blade portion. The best results were obtained.

[Example] An example will be described below with reference to the accompanying drawings.

First, a walk-behind lawnmower as an example to which the present invention is applied
In the figure, 1 is a cutter housing, 2 is a wheel, 3 is a handle, and 4 is an engine case. Inside the cutter housing 1, as shown in FIG. A vertical rotary shaft 5 is provided, and two upper and lower cutter blades 6 and 7 are fixed to the lower end of the rotary shaft 5 so as to overlap each other in the central portion. As a result, both cutter blades 6 and 7 are driven to rotate substantially horizontally.

The cutter housing 1 is provided with a peripheral wall portion 12 which is continuously hung down through a rounded portion having an appropriate curvature on the entire circumference of the disk-shaped upper wall portion 11, that is, a closed type which is opened only on the lower surface. .

The shapes of the upper and lower cutter blades 6 and 7 are as shown in FIG.

First, the upper cutter blade 6 has cutting blades 61, 6 on both ends thereof.
1 is formed, and the cutting blades 61, 61 are formed into diagonally cut portions 62, 62 at the rear side in the rotational direction.

The lower cutter blade 7 has a cutting blade 7 at both ends.
1, 71, and the rear portion in the rotational direction of each cutting blade 71, 71 portion is formed in a substantially upward standing portion 72, 72 having a smooth curved shape upward, and both end portions are central portions. It is a pressed plate that is bent further and lowered one step.

The upper cutter blade 6 is superposed on the lower cutter blade 7 in the longitudinal direction with the central portion thereof overlapped with each other, and the central portion is bolted to the joint plate 51 fixed to the lower end portion of the rotary shaft 5 as shown in FIG. Fix with.

In the above, as shown in FIGS. 5 and 6, the cutting blade 61 of the upper cutter blade 6 is positioned forward of the cutting blade 71 of the lower cutter blade 7 in the blade rotation direction R by a predetermined dimension a. At the same time, a predetermined clearance b is secured between the upper and lower cutting blades 61 and 71, and the substantially upper standing portion 72 of the lower cutter blade 7 has a predetermined dimension more than the cutting blade 61 portion of the upper cutter blade 6. It is formed higher by c.

The cutting blade 61 portion of the upper cutter blade 6 has a slanting cut portion 62 on the rear side in the rotational direction, the cutting blade 71 portion of the lower cutter blade 7 is wide in the rotational direction, and the rear portion thereof is smooth upward. Since it is a substantially curved upright standing portion 72, an arrow W is formed between the upper and lower cutting blades 61, 71.
As shown by, an air passage 8 is formed in which wind from the front flows upward.

In addition, as shown in Fig. 2, two upper and lower cutter blades 6,7
Both end portions of are close to the inner surface of the peripheral wall portion 12 of the cutter housing 1.

Since the lawn mower having the two upper and lower cutter blades 6 and 7 having the above-described configuration, the blades are rotated, and the leading upper cutting blade 61 is moved from the state shown in FIG. 7A to the state shown in FIG. 7B. First, the upper part of the turf grass is mowed, and then the turf grass is further mowed by the lower cutting blade 71 with a small time delay, as shown in FIG.

When the second cutting blade 71 is used for the second trimming, it flows in the ventilation passage 8 between the upper and lower cutting blades 61 and 71,
By the negative pressure suction action of the wind that flows upward along the substantially upward standing portion 72 having a smoothly curved shape, the turfgrass is removed as shown in FIG. 7 (b).
And, as shown in (c), the cutting blade 71 on the lower side can surely cut short.

Moreover, the turfgrass that was cut is almost upright from the ventilation passage 8.
Since it is blown by the wind flowing along and is blown upward as shown in FIG. 7 (c), it must be dropped on both rotating cutter blades 6,7 and finely cut again by each cutting blade 61,71. You can

As described above, it is possible to improve the grass standing and improve the finishing property, and it is possible to greatly improve the shredding effect of grass.

Here, by various experiments, the lower cutting blade 71 of the upper cutting blade 61
The best effect was obtained when the frontward protruding dimension "a" was about 5 mm and the clearance b between the upper and lower cutting blades 61, 71 was about 7 mm.

In addition to the above-described embodiments, the upper cutter blade 6 is, as shown in FIG. 8, made into two-piece cutting blade portions 65, 65, and bolts 66 are provided on both cutting blades 71, 71 of the lower cutter blade 7. , 66 and nuts 67, 67 may be attached to each other. Or conversely, the cutting blades 71, 7 of the lower cutter blade 7
One part may be two-piece.

It should be noted that the present invention may be applied not only to the walk-behind lawnmower and the hermetic cutter housing of the embodiment but also to a riding lawn mower and a discharge cutter housing.

[Advantages of the Invention] As described above, according to the present invention, in a lawn mower having cutter blades in which the upper cutting blade is positioned forward in the rotational direction and is vertically stacked, the lower cutting blade is smaller than the width of the upper cutting blade portion. The part is widened to form a ventilation path between the upper and lower cutting blade parts, and the rear part in the rotation direction of the lower cutting blade part is raised almost upward to change the direction of the wind in the ventilation path upward. Since it was formed in the part, the grass grass mowed once with the preceding upper cutting blade is pulled up by the negative pressure action of the wind that flows through the ventilation passage between the upper and lower cutting blade parts and flows upward by the substantially upward standing portion, You can cut again shortly with the next lower cutting blade, so you can improve the finish and improve the finish of the lawn, and in this way surely mow the grass twice and shred it, Remove the mowed grass from the ventilation path between the upper and lower cutting blades, approximately above the lower cutting blade. It can be finely cut by the upper and lower cutting blades while being carried by the wind that flows along the upright portion, blown upward, dropped, and again, so that the shredding effect of turfgrass can be greatly improved.

Further, as described in claims 2 and 3, the upper cutting blade is projected forward about 5 mm in the rotational direction with respect to the lower cutting blade, and the substantially upward standing portion on the rear side of the ventilation passage is made higher than the upper cutting blade portion. , You can get the best good results.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a walk-behind lawnmower as an example to which the present invention is applied, FIG. 2 is a vertical sectional side view of a cutter housing portion, and FIG. 3 is a perspective view of two cutter blades,
4 is an exploded perspective view of the rotary shaft and both cutter blades, FIG. 5 is a plan view of two cutter blades, and FIG.
Enlarged sectional views taken along the line AA in the figure, FIGS. 7 (a) to 7 (c) are explanatory views showing the cutting of turf grass, and FIG. 8 is the other cutter blade when one cutter blade is two-piece FIG. 1 ... Cutter housing, 5 ... Rotating shaft, 6 ... Upper cutter blade, 61 ... Cutting blade, 62 ... Diagonal cutting part,
7 ... Lower cutter blade, 71 ... Cutting blade, 72 ... Upper standing portion, 8 ... Ventilation passage.

Claims (3)

[Scope of utility model registration request] 1. A cutter blade which rotates substantially horizontally is provided vertically and is provided at a lower end portion of a substantially vertical rotation shaft, and a cutting blade of an upper cutter blade is arranged in front of a cutting blade of a lower cutter blade in a rotation direction. In the positioned lawn mower, the width in the rotation direction of the cutting blade portion of the lower cutter blade is made wider than the width in the rotation direction of the cutting blade portion of the upper cutter blade, and the upper and lower cutting blade portions are arranged. A ventilation path is formed between the lower cutter blade and a rear portion in the rotation direction of the cutting blade portion of the lower cutter blade, which is formed in a substantially upward standing portion that changes the direction of the wind in the ventilation path upward. Cutting blade device for lawn mowers. 2. The cutting blade of the upper cutter blade is rotated in a direction of rotation more than the cutting blade of the lower cutter blade.
The cutting blade device for a lawn mower according to claim 1, wherein the cutting blade device projects forward by 5 mm. 3. The cutting blade device for a lawn mower according to claim 1, wherein the substantially upper standing portion of the lower cutter blade is higher than the cutting blade portion of the upper cutter blade.