JPH0538579Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a lawn mower having a plurality of cutter blades attached to a rotary drive shaft.

[Conventional technology]

A lawn mower has a cutter blade attached to a rotating shaft driven by an engine or the like, and cuts grass by rotating the cutter blade in a horizontal plane.

In this case, in order to prevent the cutter blade and rotational drive shaft from being damaged in the event that the rotating cutter blade collides with an obstacle such as a stone, the following measures are taken, for example, as shown in USP 3158977 and USP 3109274. The cutter blade is equipped with a pair of cutter blades that are supported by a rotary drive shaft and extend in opposite directions, and in the unlikely event that one cutter blade collides with an obstacle such as a stone and stops its rotation. It is known that the other cutter blade is able to rotate relative to the cutter blade that collided with the obstacle to reduce the impact upon collision.

[The problem that the idea attempts to solve]

However, in the case of USP 3158977, although it is convenient to use a common cutter blade, the cutting height position of the blade part is different, resulting in poor finish when mowing the lawn. We are prepared.

On the other hand, in USP 3109274, the shapes of the upper and lower cutter blades are changed to align the cutting height positions, but in this case, the shapes of the cutter blades in the pair are different, so the combination However, it has the disadvantages of poor attachability and productivity.

The present invention has been made in view of the above points, and is a lawn mower equipped with at least a pair of cutter blades that are supported by a rotary drive shaft, extend in opposite directions, have blades at their tips, and are arranged above and below. The cutting height position of the upper and lower cutter blades is the same to ensure a good finish when mowing the lawn, and the same upper and lower cutter blades can be used to avoid the possibility of incorrect assembly. The purpose is to eliminate this problem, simplify assembly, and improve productivity.

[Means to solve the problem]

The structure of the present invention that achieves the above object includes at least a pair of cutter blades that are supported by a rotary drive shaft that protrudes into a cutter housing, extend in opposite directions, have blades at their tips, and are arranged one above the other. In the lawn mower, a spacer is interposed between the support parts of the upper and lower cutter blades, and the downwardly inclined lower surface of the plate provided above the upper cutter blade allows the upper cutter blade to be connected to the upper cutter blade. It is characterized in that the blades are pressed against each other and tilted downward, so that the height positions of the blade portions of the pair of cutter blades are the same.

Alternatively, a protrusion may be provided on the lower surface of the plate, and the upper cutter blade may be pressed against the upper cutter blade by the protrusion so as to be tilted downward, so that the blades of the pair of cutter blades are at the same height. good.

In the above, it is desirable that a protrusion protruding toward the lower surface of the upper cutter blade be inserted into the protrusion engagement hole formed in the lower cutter blade.

[Effect]

The cutter blade adjacent to the plate is pressed against the plate by the inclined lower surface or protrusion and tilted downward to lower the height of the tip of the cutter blade. Make it the same height.

〔Example〕

Figure 1 is a side view of the lawn mower, Figure 2 is a cross-sectional view of its main parts, Figure 3 is a cross-sectional view taken along the - line in Figure 2, Figure 4 is a cross-sectional view taken along the same line, and Figure 5 is a blade holder plate. FIG. 6 is a longitudinal sectional view of the cutter blade in the longitudinal direction, and FIG. 6 is a longitudinal sectional view of the projection of the blade holder plate in the width direction of the cutter blade.

In FIG. 1, a lawn mower 1 includes a front wheel 3 at the front of a cutter housing 2 and a rear wheel 4 at the rear, a handle 5 extending rearward from the rear end of the cutter housing 2, and a handle 5 extending rearward from the rear end of the cutter housing 2. Engine 6 is mounted on top. A cutter blade 7 that is rotationally driven by the engine 6 is housed in the cutter housing 2.

In the following, the cutter blade 7 is shown in FIGS. 2 to 4.
The rotational drive part will be explained in detail.

A crankshaft 8 of the engine 6 extends vertically downward within the cutter housing 2, and a cutter blade 7 is attached to the lower end of the shaft 8 via a clutch/brake mechanism 9.

To explain the clutch/brake mechanism 9, a rotating plate 11 is fixed to the lower end of the crankshaft 8 by a key 10.
A clutch disk 13, which is urged against the rotating plate 11 by a spring 12, is inserted through the crankshaft 8 and is provided below the clutch disk 13. Therefore, the power of the crankshaft 8 is transmitted from the rotating plate 1.
1 and is transmitted to the clutch disk 13.

A stopper plate 14 and a blade holder plate 15 are sequentially disposed below the clutch disk 13, and these are connected to the clutch disk 13 by a connecting pin 16 so as to rotate together with the clutch disk 13. There is. Therefore, the power transmitted from the crankshaft 8 to the clutch disk 13 is transmitted to the blade holder plate 15.

This blade holder plate 15 is fitted onto the outer periphery of the lower end of a large diameter of a blade mounting cylinder 17 consisting of a small diameter part and a large diameter part connected thereto, and is fixed together by welding, and the blade mounting cylinder 17 has a large diameter. The bearing 18 is press-fitted into the section, its end is caulked, and the bearing 18 is inserted into the lower end of the crankshaft 8.
By interposing a washer 19 on the lower end surface of the crankshaft 8 and fixing it with a bolt 20 from the lower end,
The bearing 18 is held between the boss portion of the rotating plate 11 and the washer 19, the blade mounting cylinder 17 is rotatably mounted to the crankshaft 8, and the blade holder plate 15 fixed to the blade mounting cylinder 17 is It becomes rotatable with respect to the crankshaft 8.

The spring 12 is a coil spring, and is disposed between the blade holder plate 15 and the clutch disk 13 on the outside of the large diameter portion of the blade mounting cylinder 17, and the stopper plate 14 is inserted through the spring 12. It is arranged on the blade holder plate 15.

On the other hand, a brake plate 21 is disposed above the rotating plate 11 so as to pass through the crankshaft 8. A bolt 22 is fixed to the lower end surface of the case 6a of the engine 6, and this bolt 22 passes through the brake plate 21.
2 is equipped with a return spring 23 that urges the brake plate 21 upward. The brake plate 21 has a larger outer diameter than the rotary plate 11, and its outer peripheral end located outside the rotary plate 11 is disposed at substantially the same height as the rotary plate 11 to form a brake portion 21a.
The clutch disk 13 has approximately the same outer diameter as the brake plate 21.

Further, a control plate 24 is arranged above the brake plate 21, and a bearing 25 is press-fitted into a cylindrical part provided in the center of the control plate 24, and the control plate 24 is inserted into the upper part of the rotating plate 11 of the crankshaft 8. The bearing 25 is held between the boss portion of the rotary plate 11 by a retaining ring 26, and the control plate 24 is rotatably provided with respect to the crankshaft 8.

A ball retainer 28 holding balls 27 is interposed between the control plate 24 and the brake plate 21, and the balls 27 are held in a recess 21b provided in the brake plate 21.
and a cam groove 24a provided in the control plate 24.

When the clutch/brake lever (not shown) is not operated, the brake plate 21 is pushed down by the control plate 24 via the ball 27, and the brake portion 21a of the brake plate 21 presses against the clutch disc 13, causing it to move downward. The clutch disk 13 is pressed down to disconnect the rotary plate 11 and the clutch disk 13, so that the power from the crankshaft 8 is not transmitted to the cutter blade 7. When the clutch/brake lever is squeezed, the wire 29 connected to it is pulled, the control plate 24 rotates, the cam groove 24a moves, the position of the ball 27 within the cam groove 24a changes, and the return spring 23 moves the brake plate 21 upward and away from the clutch disk 13, and the clutch disk 1 is pressed upward by the spring 12.
3 is pressed against the rotating plate 11, power from the rotating plate 11 is transmitted to the clutch disk 13, and the cutter blade 7 is rotated.

When the clutch/brake lever is released, the control plate 24 is rotated by the return spring 30 and returns to its original position, the brake plate 21 is pushed down, and the brake part 21a pushes the clutch disc 13. The rotary plate 11 is pressed downward to disconnect the rotating plate 11 and the clutch disk 13, and at the same time, the brake is applied.

The cutter blade 7 is composed of two cutter blades 7a and 7b. The two cutter blades 7a and 7b are made of elongated plate members having the same shape and the same thickness, and each has a mounting hole 31 at the center of impact. The position of the center of impact of the cutter blade is a position where L ₁ L ₂ m=.
Here, m is the mass, I is the moment of inertia around the center of gravity, L ₁ is the distance between the center of gravity and the center of impact, and L ₂ is the distance between the center of gravity and the collision position. Two cutter blades 7a are attached to the small diameter portion of the blade mounting cylinder 17.
The two cutter blades 7a and 7b are fixed to the shoulder portion of the blade mounting cylinder 17 by inserting the attachment hole 31 of the cutter blade 7b and screwing the nut 32 into the threaded portion formed on the outer periphery of the small diameter portion. The upper cutter blade 7 is attached to the blade holder plate 15.
A pair of protrusions 33 projecting downward are formed on both sides in the width direction of a, and the cutter blade 7a disposed between the protrusions 33 rotates in the same direction as the blade holder plate 15 rotates. Note that a pair of protrusions 33 provided on the blade holder plate 15 are provided on each side of the crankshaft 8 in the longitudinal direction of the cutter blade 7a. The upper and lower cutter blades 7a and 7b are engaged with each other by a projection 43 and a projection engagement hole 42, which will be described later, and normally rotate together.

The two cutter blades 7a, 7b are provided with a blade portion 34 on one side edge in the width direction of the tip portion and a blade 35 standing up on the other side edge, and the blade portions of the two cutter blades 7a, 7b are Next, a structure for making the cutting heights of No. 34 at the same height position will be explained.

That is, the small diameter portion of the blade mounting cylinder 17 has two
A spacer 36 is interposed between the two cutter blades 7a and 7b, so that the two cutter blades 7
A space is provided in the vertical direction between a and 7b.
The blade holder plate 15 is not horizontally arranged, but is arranged from the center to the cutter blades 7a, 7.
The blade holder plate 15 presses the upper cutter blade 7a downward, tilts the upper cutter blade 7a downward, and removes the tip of the blade. The position of the part 34 is lowered to be at the same height as the position of the blade part 34 of the lower cutter blade 7b. Although the blade holder plate 15 described above is entirely inclined, it is not limited to this, and may of course be a plate member having a horizontal upper surface and a downwardly inclined lower surface.

In addition to the above, as shown in FIGS. 7 and 8, a projection 50 projecting downward is provided on the blade holder plate 15, and the upper cutter blade 7a is pressed downward by this projection 50. Alternatively, the upper cutter blade 7a may be tilted downward so that the height positions of the blade portions 34 of the two cutter blades 7a and 7b are the same.

In this way, since the upper cutter blade 7a is pressed against the blade holder plate 15 and bent downward, the nut 3 fixed to the lower part of the cutter blades 7a and 7b is bent by the repulsive force.
2 is prevented from loosening.

In addition, the cutter blades 7a and 7b are narrowed at the center and protrude upward in the cross section in the width direction.
It is composed of a flat central part 37 that projects upward, a pair of flat side parts 38 that are one step lower than the central part 37, and an inclined part 39 that connects them. The connection portion between the upper surface of the central portion 37 and the upper surface of the inclined portion 39 forms a smooth curved surface. Note that the cross section in the width direction near the mounting hole 31 has a flat central portion 4 that protrudes upward.
0 and an inclined portion 4 extending outward and downward from both ends thereof.
It consists of 1.

The cutter blades 7a and 7b have a protrusion engagement hole 42 formed in a flat central portion 37 that protrudes above the end opposite to the blade portion 34, and the attachment hole 31 and the blade portion 34 are connected to each other. A protrusion 4 formed by recessing the flat central part 37 upwardly protruding between
3 is provided, and two cutter blades 7a, 7 are provided.
b is attached to the blade mounting cylinder 17 with the spacer 36 interposed, the protrusion 43 of the upper cutter blade 7a is inserted into and engaged with the protrusion engagement hole 42 of the lower cutter blade 7b. ing. Note that although it is desirable to provide the protrusion 43 and the protrusion engagement hole 42, they may not be provided. Therefore, as mentioned above, the blade holder plate 15
The upper cutter blade 7a is tilted downward, but the lower cutter blade 7b
Also, the portion on the side of the projection engagement hole 42 into which the projection 43 of the upper cutter blade 7a is inserted and engaged is inclined downward. However, even if the upper cutter blade 7a tilts downward, the lower end of the lower cutter blade 7b on the blade portion 34 side does not press against the upper surface of the lower cutter blade 7b. It cannot be tilted downward.

When the protrusion 43 is inserted into the protrusion engagement hole 42, the two cutter blades 7a and 7b rotate together with support from the center of gravity. In the event that the cutter blade collides with an object and its rotation is stopped, the protrusion 43 is disengaged from the protrusion engagement hole 42 by the rotational force of the other cutter blade, and the other cutter blade rotates. It collides with one of the cutter blades, which is stopped by an obstacle, and stops. In this case, when one cutter blade collides, the other cutter blade is separated from the other cutter blade and the integral relationship is broken, so one cutter blade becomes the center of impact support and the crank caused by the collision. The influence on the shaft 8 etc. will be minimal. In addition, the other cutter blade that has been separated from one cutter blade also supports the center of impact, and even when this other cutter blade collides, the impact of the collision can be minimized.

[Effect of idea]

As described above, according to the present invention, the cutting height positions of the upper and lower cutter blades are the same, which results in a good finish when cutting the grass.
In this case, since a common blade can be used for the upper and lower cutter blades, there is no risk of incorrect assembly during assembly, which makes assembly easy and improves productivity.

[Brief explanation of the drawing]

Figures 1 to 8 show one embodiment of the present invention, Figure 1 is a side view of the lawn mower, Figure 2 is a sectional view of its main parts, Figure 3 is a sectional view taken along the - line in Figure 2, and Figure 4 is a sectional view of the lawn mower. The figure is the same.
5 is a longitudinal sectional view of the blade holder plate in the longitudinal direction of the cutter blade; FIG. 6 is a longitudinal sectional view of the projection of the blade holder plate in the width direction of the cutter blade;
7 and 8 show another example of the blade holder plate, FIG. 7 is a longitudinal sectional view of the blade holder plate in the longitudinal direction of the cutter blade, and FIG. 8 is a cutter blade of the protrusion of the blade holder plate. FIG. 3 is a longitudinal cross-sectional view of the blade in the width direction. 1 is a lawn mower, 2 is a cutter housing, 3 is a front wheel, 4 is a rear wheel, 5 is a handle, 6 is an engine, 6
a is an engine case, 7, 7a, 7b are cutter blades, 8 is a crankshaft, 9 is a clutch/brake mechanism, 10 is a key, 11 is a rotating plate, 12, 23, 30 is a spring, 13 is a clutch disk, 14 is a stopper plate, 1
5 is a blade holder plate, 16 is a connecting pin, 17 is a blade mounting cylinder, 18 and 25 are bearings, 19 is a washer, 20 and 22 are bolts,
21 is a brake plate, 21a is a brake part,
21b is a concave portion, 24 is a control plate,
24a is a cam groove, 26 is a retaining ring, 27 is a ball,
28 is a ball retainer, 29 is a wire, 31
is a mounting hole, 32 is a nut, 33, 43, 50 are projections, 34 is a blade portion, 35 is a blade, 36 is a spacer, 37, 40 is a center portion, 38 is a side portion, 39,
41 is an inclined portion, and 42 is a protrusion engagement hole.

Claims (1)

[Claims for Utility Model Registration] (1) At least a pair of cutter blades that are supported by a rotary drive shaft that protrudes into a cutter housing, extend in opposite directions, have blades at their tips, and are arranged one above the other. In the lawn mower, a spacer is interposed between the support parts of the upper and lower cutter blades, and the downwardly inclined lower surface of the plate provided above the upper cutter blade allows the upper cutter blade to be connected to the upper cutter blade. A lawn mower characterized in that the blades are pressed against each other and are inclined downward, so that the height positions of the blade portions of the pair of cutter blades are the same. (2) In a lawn mower equipped with at least a pair of cutter blades, which are supported by a rotary drive shaft protruding into a cutter housing, extend in opposite directions, have a cutting edge at the tip, and are arranged one above the other, A spacer is interposed between the supporting parts of the cutter blade, and a projection protruding from the lower surface of the plate provided at the upper part of the upper cutter blade pushes the upper cutter blade downward. A lawnmower characterized in that the blades of the pair of cutter blades are inclined at the same height. (3) Claim 1 or 2, wherein a protrusion protruding from the lower surface of the upper cutter blade is inserted into the protrusion engagement hole formed in the lower cutter blade.
Lawn mower listed.