FR2510345A1 - Rotary cutting blade for lawn mower - uses V=shaped notch in end or end return to create clearance with carcass skirt and reduce noise - Google Patents

Abstract

The cutting blades (2,5) are of the rotating type incorporated in lawn mowers, their ends being shaped to reduce operational noise. The end may be notched (1) to form a gap (4) between the carcass skirt (3), the notch subtending angles of 55 degrees and 60 degrees with the cutting and trailing blade edges respectively. The intersection of the notch sides may be rounded with a radius of 15mm, an alternative using a unilateral full width plate (6) dressed at right angles to the radial blade plane. A final alternative uses a blade end return (7) to provide carcase clearance (8), the fold line being angled at some 75 degrees to the cutting edge, whilst the return is angled at 30 degrees to the major blade plane.

Description

 The present invention relates to the field of construction of lawn mowers, in particular rotary blade mowers, and relates to improvements to the cutting blades of such mowers.

 I1 is well known that the rotating objects generate at their ends turbulence called "marginal eddies", which have the effect of raising their noise level, and which are combined with impact or sliding at the level of the carcass skirt.

 The object of the present invention is to overcome these disadvantages.

 It has, in fact, the object of improvements to the cutting blades of lawnmowers with rotating blades, characterized in that the blades are provided at their ends with a notch delimiting between them and the skirt of the carcass a space.

 According to an alternative embodiment of the invention, the blades are provided at their ends with an obstacle erected perpendicular to their radial plane.

 The invention will be better understood thanks to the description below, which relates to preferred embodiments, given by way of nonlimiting examples, and explained with reference to the appended schematic drawing, in which FIG. 1 is a view partial plan view of a blade according to the invention FIG. 2 is a view similar to that of FIG. 1 of an alternative embodiment of the invention, and FIG. 3 is a partial perspective view of another variant embodiment of the invention.

 In accordance with the invention, and as shown more particularly, by way of example, in FIG. 1 of the appended drawing, a first improvement to the cutting blades of rotary lawn mowers consists of a notch 1 formed in each end 2 of the blade so as to delimit a space 4 between it and the skirt 3 of the carcass.

 The shape of the groove 1 can be any, however, its edges advantageously have an angle of 55 relative to the cutting edge and an angle of 60 relative to the rear edge of the blade, a rounded radius of 15 mm joining said edges. .

 FIG. 2 represents an alternative embodiment of the invention in which the blade 5 is provided at each end with an obstacle 6, which is erected perpendicularly to its radial plane, and which is either attached to the blade 5 or integrated to the latter. This obstacle 6 can have a length equal to the width of the end of the blade or extend only over part of this width.

 According to another alternative embodiment of the invention, shown in FIG. 3, the end of the blade can also have a raised edge 7 relative to its cutting plane so as to form a space 8 between said end and the skirt of the carcass while creating an obstacle on the radial plane of the blade.

 The angle of the fold line of the raised edge 7 with respect to the cutting edge is advantageously 75 and the plane passing through this edge 7 forms an angle of 30 with the plane of the blade.

 Thanks to the invention, it is possible to significantly reduce the turbulence called "marginal eddies" as well as the shocks and slippages at the level of the carcass skirt, so that the noise generated by the cutting blade can be greatly reduced.

 Of course, the invention is not limited to the embodiments described and shown in the accompanying drawing. Modifications remain possible, in particular from the point of view of the constitution of the various elements, or by substitution of technical equivalents, without thereby departing from the scope of protection of the invention.

Claims (6)

- CLAIMS -  1. Improvements to the cutting blades of rotary lawn mowers characterized in that the blades are provided at their ends (2) with a notch (1) delimiting between them and the skirt (3) of the carcass a space ( 4).  2. Improvements according to claim 1, characterized in that the edges of the notch) advantageously have an angle of 55 relative to the cutting edge and an angle of 60 relative to the rear edge of the blade, a rounding with a radius of 15 mm joining said edges.  3. Improvements according to claim 1, characterized in that the blades (5) are provided at their ends with an obstacle / standing perpendicular to their radial plane, and which is either attached to the blade (5), or integrated to the latter.  4. Improvements according to claim 3, characterized in that the obstacle (5) has a length equal to the width of the end of the blade or extends only over a part of this width.  5. Improvements according to claim 1, characterized in that the end of the blade has an edge (7) raised relative to its cutting plane so as to form a space (8) between said end and the skirt of 1 carcass while creating an obstacle on the radial plane of the blade.  6. Improvements according to claim 5, characterized in that the angle of the fold line of the raised edge (7) relative to the cutting edge is advantageously 75 and the plane passing through this edge (7) forms with the plane of the blade an angle of 30.