SI21214A - Guard and blade of engine driven mower - Google Patents

Abstract

The guard of an engine driven mower features the shape of a round panel, made preferably from steel sheet. Within its center it features a circular opening which is used for attaching to the enclosure of the driving axle of the circular mower blade. Its external diameter is slightly (within a few millimeters) larger that the external diameter of the corresponding mower blade. Along the circumference, preferably all around it there are radially oriented grooves (3) one next to the other with as little space between them as possible, which provide the guard according to the invention the look of a gearwheel featuring very thin teeth. The guard according to the invention accepts into its grooves (1) only blades of grass which are thinner than the groove (3) gap (4) width thus exposing them to the rotating drive blade beneath it, while all thicker objects are kept away from the specified knife thus protecting it against unwanted damage, while at the same time it also prevents that the blade would hit hard objects (stones), which could damage the blade or even the person mowing. Due to the close location next to the knife the blade according to the invention completely protects the person mowing against chopped pieces (small flying pieces of cut blades of grass) so that he needs no additional means of protection.

Description

The invention relates to a protective plate (shield) of a motorcycle and to a rotary knife associated therewith.

The basic task of the shield, which is attached to the scaffold frame above the rotary circular knife, is to protect the wearer from chips (pieces of grass and other herbs we mow) that fly on all sides during mowing. Existing shields, however, do a poor job, mainly because of their inappropriate shape and the distance between them and the cutter blades. For this reason, the cutter must be fitted with a protective clothing that protects the face and eyes and the legs and arms from the chips. In addition to insufficient protection against chips, existing shields cannot prevent the knife from hitting a larger solid object (such as a rock), in which case a very strong and dangerous impact can occur. The defect according to the invention completely eliminates the aforementioned defects of the existing protectors, and during mowing it prevents the user from contacting the knife, protecting it from damage, as well as damaging larger objects (eg tree stalks) while mowing the surrounding grass.

The shield according to the invention performs the said function due to its specific design and dimensions, as well as its placement with respect to the cutter's knife, from which it is minimally spaced.

The invention will be described in detail in the embodiment and shown in the drawing showing:

FIG. 1 ..... top view of the shield of the invention;

FIG. 2 .... top view of a circular knife according to the invention.

The shield 1 according to the invention takes the form of a circular plate, preferably of sheet steel. It has a circular hole at its center, which serves to be mounted on the drive shaft of the motor circular knife blade. Its outer diameter D is slightly (on the order of several millimeters) larger than the outer diameter d of the corresponding motor cutter blade. Along the circumference, preferably throughout, radially oriented grooves 3 are arranged next to each other with the smallest possible intervals, which give the visor according to the invention the appearance of a very thin gear wheel or sprocket. The depth of the grooves 3 is such that the diameter of the base circle D1 of the shield according to the invention coincides with the diameter of the base circle d1 of the corresponding motor cutter blade. The width of the grooves 3 and / or the boom of the exact mouth 4 of the grooves 3 is limited by the thickness of the stems of plants (or other objects) that are not to be damaged during mowing. Namely, the shield according to the invention lowers into its grooves 3 only herbs thinner than the width of the mouth 4 of the grooves 3, thus exposing them directly below the rotating motor knife, while preventing the thicker objects from contacting said knife, thus protecting them from unwanted damage. Therefore, the shields according to the invention are made with different groove widths 3, with the user attaching a suitable one before cutting it. More versatile, however, is the design of the invention according to the invention with narrow grooves 3 suitable for mowing grass, with one wider groove of a width of the order of 30 mm or more, which is used only if you want to cut a plant with a slightly thicker stem here and there. The shield according to the invention therefore enables very precise and easy mowing around vertical objects that are not intended to be mowed or damaged, for example, mowing grass around trees or around roadsides. In such a case, the wearer can simply lean the bevel with the shield according to the invention against the vertical wall of said object, which, because its thickness is greater than the width of the grooves 3, cannot come into contact with the cutter knife, and the bevel with the leaning shield without fear that the object would be damaged, moving around or around it.

In addition to the above, the shield according to the invention also has a safety significance in that it prevents the knife from contacting the larger surrounding objects. If a very fast rotating knife strikes a solid object, such as a larger rock or rock, it causes a relatively strong impact, which either catapults the object (stone) or bounces the object from the object (in the case of a rock), both of which pose considerable danger. This situation is practically impossible if the piece is fitted with a shield according to the invention.

When attempting to operate a scaffold equipped with a shield according to the invention, its operation proved to be effective to such an extent that the user does not need to use any additional protective means.

In addition to the described features, the shield according to the invention also participates (along with the knife) in chopping the herbs (which is basically what happens when mowing). Namely, with the lateral edges of the 5 grooves 3, it prevents the blade blades from escaping. The blade knife blade is first pushed to the edge of the blade 5, then cut close to it, making the cutting efficiency of the herbs significantly increased, even with a less sharp knife blade. Of course, this effect is possible only with the smallest possible gap between the knife and the shield in the axial direction of the drive shaft of the piece, which is one of the reasons for the closure of the shield according to the invention to the cutter knife of the invention. The second reason is that the close installation prevents the chips from flying towards the cutter.

Not only does the protector according to the invention improve the mowing efficiency by the described knife engagement, but in addition to the existing knives, it also allows the use of a knife that does not have good mowing properties on its own (without the aid of the protector according to the invention) but has good abilities ( 3) cutting of stems and branches, e.g. shrubs. The combination of the shield of the invention and such a knife, which will be described below, as it is also an object of the present invention, therefore extends the use of a hand-held power-saw to a limited extent (saw).

The rotary circular blade 2 according to the invention is made of sheet steel and has at least six blades 6, similar to the teeth of the gears, evenly spaced throughout the circumference. The blade 6 in each case is symmetrical with respect to the radially extending axis 7, extending slightly in the direction of the center (coinciding with the axis of rotation of the blade), so that its width on the base circle of diameter di is greater than the peak. The widths of the gaps, which narrow in the direction of said center in the direction of the blades, are narrowed at the base circle d! the same size class as the blade width 6 on the same radio.

Both side edges 8 of the respective blade 6 are cutting edges, since the knife according to the invention can be used on both sides, since the respective blade 6 is symmetrical with respect to said axis 7 and is therefore sharpened.

On the circumference of each blade 6 there is a groove 9, which is intended to reduce the friction on the circumference while using the knife of the invention as a saw.

The advantage of the knife according to the invention over the existing rotary mower blades is that, due to the large number of blades of the 6 blades according to the invention, the load on each blade is smaller than with the existing two or three-blade blades, which makes their life longer and the cutting process even. In the case of a knife hitting a hard object, the impact is much milder for the same reason. In addition, the symmetrical design of the said blades allows the knife to be used in accordance with the invention on both sides, which doubles the service life or the period between two grinding operations.

Experiments have shown that they have the best properties in both mowing and cutting thin branches (shrubs) and sawing, knives 2 according to the invention with ten to twelve blades

Claims (3)

A scythe guard (1), characterized in that it is attached to said piece just above the rotary knife, in the form of a circular plate whose outer diameter (D) is slightly, on the order of several millimeters, larger than the outer diameter (d ) of the corresponding cutter knife to have radially oriented grooves (3) arranged around the circumference, preferably throughout the circumference, preferably with a minimum of spacing, which give the shield according to the invention the appearance of a very thin gear wheel or chain. A scythe guard (1) according to the first claim, characterized in that the depth of the grooves (3) is such that the diameter of the foot circle (Dd of the shroud according to the invention coincides with the diameter of the foot circle (di) of the corresponding motor blade, the width of the grooves ( 3), or more precisely the mouth (4) of the grooves (3) is limited by the thickness of the stems of plants (or other objects) which are not to be damaged during mowing, whereby the shroud according to the invention releases only herbs thinner than herbs (3). the width of the mouth (4) of the grooves (3), thereby exposing them directly below the rotating motor knife, while thicker objects prevent contact with said knife, thus protecting them from unwanted damage. A scythe guard (1) according to the preceding claims, characterized in that it is attached to the rotary mower together with a rotary circular knife (2) having at least six blades (6), similar to the teeth of the gears, evenly spaced over the entire circumference. whereby each blade (6) is symmetrical with respect to the radially extending axis (7), it extends slightly in the direction of the center (coinciding with the axis of rotation of the knife) so that its width on the base circle of diameter (d ^ is greater than the crown, the width of the cutting blades) the gaps that narrow in the direction of the center as the blades (6) narrow, are on the base circle (eh) of the same size class as the width of the blades (6) on the same radius, the two lateral edges (8) of each blade (6) being the cutting edges and as such, they are sharpened and the groove (9) is located on the circumference of each blade (6). Alojz Tomazin