DE3007376A1 - CIRCULAR SCREW LINE HOUSING FOR LAWN MOWERS - Google Patents

Description

Γ PATENT LAWYERS JUU / θ / 6 ~]

DR.-ING. R. DÖRING _ DIPL.-PHYS. DR. J. FRICKE

"-, BRAUNSCHWEIG **" MUNICH

5501

OUTILS WOLF, Särl, WISSEMBOURG (Bas-Rhin, France)

Circular helical housing for lawn mowers

The present invention relates to a circular helical housing for lawn mowers, in particular with a knife track with a vertical axis of rotation.

There is generally a reduction in the radiated sound energy when mowing and a better filling of the grass container strived for. For this purpose, the pitch of the helix is chosen to be larger and the ejection point of the grass is placed higher on this circular helix.

In known lawnmowers of this type, there is a sudden transition between a maximum channel cross-section and a minimal duct cross-section. The air flow generated by the knife movement, which the clippings should remove, generates not inconsiderable sound vibrations at the sudden narrowing of the canal. Additionally, that the cut blades of grass are partially stuck at this point, whereby the ejection of the grass be-L is prevented. j

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The present invention is based on the object of eliminating these disadvantages.

To solve this problem, the invention provides a housing of the type mentioned, which is characterized in that away from the area of the clippings ejection, in the direction of rotation of the knife, the housing has a constantly decreasing channel cross-section has, in such a way that not ejected clippings are guided into the immediate circular path of the knife.

Further features, advantages and details of the present invention are the following description of a preferred, by no means restrictive embodiment based on can be found in the accompanying drawings.

Show it :

Figure 1 is a side view of the housing of a lawn mower constructed in accordance with the present invention;

Figure 2 is a plan view of the lawn mower according to Figure 1, different zones of the helix are indicated;

Figure 3 is a development of the helical housing, the change in cross section by changing the Dimensions parallel to the axis of rotation is illustrated;

030038/0681

FIG. 4 shows in detail the development of the helical line according to the line of movement of the cutting knife, and

FIG. 5 is a view similar to FIG. 4 to illustrate the movement of the cut grass and that in the area CE ejected proportion.

According to the invention, as shown in particular, for example, in Figures 1 to 3 of the present drawing, there is Improvement of the circular helical housing 1 in a constant throttling or reduction 2 of its channel cross-section, which is present in the zone between points A and B, i.e. so that this reduction in cross-section after the ejection channel 3, which is delimited by the zones CD and DE, entry. This reduction 2 in the cross section has the purpose of throwing out the grass, which is moving too slowly to be gathered, and brought into the immediate vicinity of the line of movement of the cutting knife, that of the grass gives the force necessary for ejection, during its passage in the cutting zone BC.

Thanks to this gradual decrease, the cross-section of the Screw curve, no sudden changes in air pressure are generated by the knife, reducing the radiated sound energy is significantly reduced.

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Figure 4 shows the movement of air within the helix and their gradual throttling in zone AB. FIG. 5 shows the path of movement of the cut grass, its emptying through the discharge duct at the level of zones CD and DE and the return of part of this grass in the reduction zone AWAY.

Thanks to the invention, the grass is no longer removed by pulsating air. The latter is instead used over a longer period of time accelerated by touching the knife. The combined effect of the kinetic energy gained by this means that each Blade of grass is issued and the centrifugal force leads to an ejection of the grass up through the ejection channel, as the cut grass the ejection energy is emitted directly by the cutting device, can have a strong, noisy effect Blowers can be dispensed with and the motor power required for this can be reduced accordingly.

030038/0681

Claims (4)

Γ PATENTANWÄLTE DR.-ING. R. DÖRING DIPL.-PHYS. DR. J. FRICKE BRAUNSCHWEIG MUNICH 5501 Claims 1. Circular helical housing for lawn mowers, characterized in that the area of the clippings ejection (3) away, in the direction of rotation of the knife, the housing (1) has a constantly decreasing channel cross-section has, in such a way that the cut material not ejected into the immediate circular path of the knife to be led. 2. Housing according to claim 1, characterized in that the housing portion (AB) of decreasing channel cross-section continuously merges into the adjoining housing section (BC). 3. Housing according to claim 1 or 2, characterized in that the housing portion (AB) of Constantly decreasing channel cross-section from the clippings ejection (3) over about 1/4 of the Extends the circumference. 4. Housing according to one or more of claims 1-3, characterized in that the Change of the channel cross-section in the direction parallel to the vertical axis of the knife course is provided. J. 030038/0681