JPH04131007A - Cutting housing of lawn mower - Google Patents

Abstract

PURPOSE:To improve finely cutting effects of lawn mower by laying a specific scroll guide wall above a cutter blade. CONSTITUTION:In a cutter housing 1, a scroll guide wall 7 extending from the inside of peripheral wall part of the whole periphery of the housing to the periphery side of a revolving shaft, dropping from the under surface side of an upper wall part 11 and forming a spiral state at least 180 degrees round the revolving shaft in a plane view is laid above a cutter blade 6, cut lawn is collected from the whole periphery to the central part of the cutter blade, dropped and finely cut by the cutter blade.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cutter housing for a lawn mower, and more particularly to the internal structure of a closed cutter housing that houses a cutter plate that rotates substantially horizontally and is open only at its lower surface. It is.

[Prior Art] In a so-called mulching lawn mower in which a cutter blade that rotates approximately horizontally is housed in a closed cutter housing with only the lower surface open, wind generated by the rotation of the cutter plate is generated around the inside of the cutter housing. The technology is disclosed in U.S. Patent No. 4,205.512, in which a force member is provided to direct the swirling flow toward the center of the cutter blade, and the grass cut by the cutter blade is dropped from above and shredded by the cutter blade again. specification and U.S. Patent No. 4,
It is known from specification No. 189,903.

[Problems to be Solved by the Invention] However, by deflecting the wind generated by the rotation of the cutter plate by hitting a tight member provided around the inside of the cutter housing, it is possible to direct the flow toward the center of the cutter blade. Since it generates wind locally and turbulence is likely to occur inside the cutter housing,
There is room for improvement in order to further shred the turfgrass.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cutter for mulching lawn mowers as described above, which can forcibly collect the grass cut by the cutter blade from all around the area and drop it to the center of the cutter plate, greatly improving the grass shredding effect. The purpose is to provide housing.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a cutter blade that is provided at the lower end of a substantially vertical rotating shaft and rotates substantially horizontally, and an upper wall portion through which the rotating shaft passes through the cutter blade. In the lawn mower housed in a cutter housing having a peripheral wall hanging down around the entire circumference and opening only the lower surface, the rotating The scroll guide wall is characterized by being provided with a scroll guide wall that extends toward the circumference of the shaft, hangs down from the lower surface side of the upper wall portion, and has a spiral shape over at least 180 degrees in plan view about the rotation shaft.

More specifically, the scroll guide wall is characterized in that the outer surface is formed as a substantially vertical surface, and the inner surface is formed as an inclined surface that becomes thinner as the wall thickness with the outer surface decreases.

[Function] Inside the cutter housing, the cutter housing extends from the inner surface of the circumferential wall around the entire circumference toward the circumferential side of the rotating shaft, hangs down from the lower surface of the upper wall, and has at least one line in plan view about the rotating shaft.
An 80-degree spiral scroll guide wall is provided above the cutter blade, so the grass cut by the cutter plate is swept away from the cutter frame from all around by the centripetal flow of wind generated along the scroll guide wall. The particles are forcibly gathered toward the center of the screen, fall, and are again cut into small pieces by the cutter blade.

In addition, the scroll guide wall has an outer surface formed as a substantially vertical surface and an inner surface formed as an inclined surface whose wall thickness becomes thinner as it goes downward, thereby preventing flow stagnation near the top of the inner surface. At the same time as removing it, turf grass may adhere to the inside surface.
<This will promote the fall of the grass onto the cutter plate.

[Example] Examples will be described below based on the accompanying drawings.

A first example of a walk-behind lawn mower 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 substantially vertical rotating shaft 5 is provided, and a cutter blade 6 is fixed at the center to the lower end of the rotating shaft 5. As a result, the cutter blade 6 is driven to rotate substantially horizontally.

The cutter housing 1 is equipped with a circumferential wall part 12 that hangs down continuously over the entire circumference of a disc-shaped upper wall part 11 via a rounded part with an appropriate curvature, that is, it is a closed type that is open only to the bottom surface. .

The cutter blade 6 has a cutting blade 61° 61 and an upward twisting portion 62, 62 for blowing air at both ends thereof, and both ends are close to the inner surface of the peripheral wall portion 12 of the cutter housing 1. There is.

Inside the cutter housing 1, there is an upper wall portion 1.
A scroll guide wall 7 is formed integrally with the scroll guide wall 1 .

As shown in FIGS. 3 and 4, the scroll guide wall 7 is located above the canter blade 6 and extends from the inner surface of the cutter housing peripheral wall portion 12 toward the peripheral side of the rotating shaft 5. It hangs down from the lower surface side of the upper wall portion 11, and in the embodiment, it has a spiral shape over 360 degrees or more in plan view with the rotation axis 5 as the center.

Furthermore, this scroll guide wall 7 has an outer surface formed into a substantially vertical surface 7.
1, and the inner surface is formed into an inclined surface 72 which becomes thinner as the wall thickness with respect to the outer channel vertical surface 71 decreases downward. Further, in the embodiment, the inner inclined surface 72 is a concave rounded surface with an appropriate curvature.

For a lawn mower having the above-mentioned scroll guide wall 7, for example, the cutter/"i-using peripheral wall portion 12 of the scroll guide wall 7 is
When the cutter blade 6 is set to cross the side portion, the cutter blade 6 normally rotates in the direction of the arrow R shown in FIG.
0 Orpm), as shown in FIG.
Since the air flow generated by the upper twist portions 62, 62 at both ends is as shown by the arrow a in FIG. 3, the effect of making the grass stand up can be obtained, contributing to an improvement in the finished product.

The swirling flow generated by the rotation of the cutter blade 6 is converted into a centripetal flow by the scroll guide wall 7, so that the grass that has been cut by the cutting blades 61, 61 at both ends of the cutter blade 6 is transferred to the scroll guide wall 7. The centripetal flow as shown in the arrow C shown in FIG. It is distributed approximately evenly over the center of the cutter blade 6, and is again finely cut by the cutting blades 61, 61 at both ends of the cutter plate 6.

Moreover, since the scroll guide wall 7 has an inner surface formed as an inclined surface 71 which is a concave rounded surface whose wall thickness with the outer path vertical surface 72 becomes thinner downwardly, the cutter hound on the upper part of the inner inclined surface 71 This eliminates flow stagnation near the lower surface of the upper wall portion 11 of the scroll guide wall 7, prevents grass from adhering to the inner surface of the scroll guide wall 7, and promotes the fall of the grass to the cutter play 1-6.

Therefore, the effect of shredding turf grass can be greatly improved by the above method.

Here, in the above embodiment, the scroll guide wall 7 is integrally formed with the cutter housing 1, but as shown in FIG. 73, the upper wall portion 1 of the cutter housing 1
1 may be integrally joined to the lower surface. Also Sufu 0
- The rugite wall 7 may be provided over at least 180 degrees in plan view.

It goes without saying that the present invention is applicable not only to the walk-behind lawn mower of the embodiment, but also to the closed cutter housing of a riding lawn mower.

[Effects of the Invention] As described above, according to the present invention, in a lawn mower for mulching, a blade is provided in a closed cutter housing that extends from the inner surface of the peripheral wall around the entire circumference of the cutter housing toward the periphery of the rotating shaft. A scroll guide wall that hangs down from the lower surface of the upper wall and has a spiral shape of at least 180 degrees in plan view about the axis of rotation is provided above the cutter blade, so that the grass cut by the cutter blade can be easily moved through the scroll guide wall. Due to the centripetal flow of wind generated along the turf, the turf grass can be forcibly gathered from all around to the center of the cutter blade and fall, allowing the cutter blade to finely cut the turfgrass again, greatly improving the grass shredding effect.

Further, as claimed in claim 2, the outer surface is formed into a substantially vertical surface,
If the inner surface is formed as a scroll guide wall with an inclined surface where the wall thickness decreases downward, the inclined surface will eliminate stagnation of the flow near the top of the inner surface, and will also allow grass to adhere to the inner surface. By doing so, you can encourage the grass to fall onto the cutter plate.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing a walk-behind lawn mower as an example to which the present invention is applied, FIG. 2 is a vertical side view of a cutter housing portion, and FIG. 3 is a perspective view showing the internal structure of the cutter housing along with its operation. FIG. 4 is a bottom view showing the scroll guide wall in the cutter housing, and FIG. 5 is an exploded perspective view of the cutter housing and scroll guide wall in the case of separate types. DESCRIPTION OF SYMBOLS 1... Cutter housing, 11... Upper wall part, 12
... Peripheral wall part, 6 ... Cutter plate, 61 - Cutting blade, 62 ... Upper twist part, 7 ... Scroll kite wall, 71 ... Outer path vertical surface, 72 ... Inner inclined surface .

Claims (2)

[Claims] (1) A cutter blade that is provided at the lower end of a substantially vertical rotating shaft and rotates substantially horizontally is provided with a peripheral wall that hangs down over the entire circumference of the upper wall that the rotating shaft passes through, leaving only the lower surface open. In a lawn mower housed in a cutter housing, the cutter blade extends from the inner surface of the peripheral wall toward the circumferential side of the rotating shaft and extends from the lower surface of the upper wall above the cutter blade in the cutter housing. A cutter housing for a lawn mower, characterized in that a scroll guide wall is provided which hangs down and forms a spiral over at least 180 degrees in plan view about the rotation axis. (2) In the scroll guide wall, the outer surface is formed to be a substantially vertical surface, and the inner surface is formed to be an inclined surface whose wall thickness becomes thinner downwardly. Lawn mower cutter housing.