FR2817706A1 - AUTOMATIC DEVICE FOR DRAWING OUT THE LAWN MOWER CUTTING WIRE - Google Patents

Abstract

The device comprises a spool of wire in a wire casing connected to an output shaft. The cutting wire (13) wound on the spool of wire, is retained by a rock wheel having a plurality of rocks (5), one of which is stopped by a starting block (6) which is connected to a return plate (7) pushed back by a spring (9) towards the rock (5) against the action of the centrifugal force on the stop block (6) .Application to the stabilized automatic lengthening of the cutting line of a lawn mower.

Description

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AUTOMATIC EXTERNAL DRAWING DEVICE
OF LAWN MOWER CUTTING WIRE
The present invention relates to a lawn mower, more particularly to an automatic device for drawing outward the cutting line of a lawn mower.

 Lawn mowers, like common power tools, are used primarily to cut the lawn flush. Their cutting head generally comprises two parts, one of which comprises an electric motor and the other of which comprises a member for cutting the lawn. The lawn cutting member can be of two different types: the cutting wheel type and the wire box type. The first member cuts the grass with blades, while the last member uses the cutting force generated by the high speed rotation of a cutting wire capable of cutting the grass. Both types of lawn mower experience abrasion after being used for a certain period of time. For lawn mowers of the cutting wheel type, the worn blades will be replaced by abrasion. For the type of wire box mower, the abrasion will shorten the effective length of the cutting head, and as a result the cutting line can no longer work efficiently until it has been replaced by a drawn line. outward from the wire wheel. In addition, the abrasion of the cutting line is faster than that of the blades. Consequently, it is necessary for an operator to frequently lengthen the cutting line during use of the cutting mower, to be sure that the cutting line has a sufficient active length and to maintain in the best operating condition the Lawn mower. This forces the operator to do an additional amount of work.

 The object of the present invention is precisely to overcome the drawbacks of prior art wire lawnmowers and to provide an automatic device for drawing the cutting line of a lawnmower to the outside. The device according to the present invention is capable of stretching outward the cutting line automatically after abrasion of the cutting line, in order to maintain the correct working length of the cutting line, and to keep the lawn mower in permanently at its best operating condition.

 The present invention provides a device for drawing outward the cutting line of a lawn mower. The device according to the invention comprises: a wire housing connected to an output shaft, a wire coil in the wire housing, a cutting wire wound on the wire coil, and it is characterized in that a wheel with rocks provided

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 a plurality of rocks is arranged on the wire spool, a stop block is placed in the pressing position on one of the rocks, a return plate is arranged on the stop block, the return plate and a spring are mounted on a core pin, the core pin is fixed to the wire housing in a diametrical direction, and the spring presses the stop block against the rock.

 The present invention further provides a device for drawing outward the cutting line of a lawn mower of the type described above and characterized in that a core spindle hole is disposed on the wire housing according to a diametrical direction, the core pin is a bolt-shaped pin and is mounted on the wire housing, the screw being screwed through the core pin hole, the stop block is arranged in the wire housing, the plate on the stop block is mounted on the core pin through a guide hole in the upper part of the wire case, a guide bar is arranged on the lining wall of the wire case next to the stop block .

The automatic device for drawing the cutting line of a lawnmower to the outside, according to the present invention, has the following advantages:
1. When abrasion shortens the effective length of the cutting line, the cutting resistance will decrease, which increases the speed of rotation of the electric motor, thereby increasing the centrifugal force. Then, the stop block, due to the greater centrifugal force, overcomes the elastic force of the spring to leave the rock. In the meantime, the spool of wire is driven by the centrifugal force of the cutting line to automatically rotate on a rock, so as to stretch the cutting line outwards. Then, the cutting resistance increases and the speed of rotation of the electric motor decreases, so that the centrifugal force acting on the stop block is less than the elastic force of the spring, and finally the stop block comes to press under the action of the spring the next rock.

 2. The device for drawing outward the cutting line of a lawn mower according to the present invention has a simple structure and convenient operation. It is mainly capable of automatically stretching the cutting line outwards, in order to maintain the correct working length of the cutting line and to keep the lawn mower permanently in its best operating condition.

 Other objects, characteristics and advantages will appear on reading the description of an embodiment of the invention, given by way of nonlimiting example and with reference to the appended drawing in which:

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- la figure 1 est une vue frontale du dispositif automatique d'étirage vers l'extérieur du fil de coupe d'une tondeuse à gazon, selon la présente inven- tion ; - la figure 2 est une vue de dessus du dispositif automatique d'étirage vers l'extérieur du fil de coupe d'une tondeuse à gazon selon la présente inven- tion ; - la figure 3 est une vue fragmentaire à plus grande échelle de la partie A à la figure 1 ; - les figures 4,5 et 6 représentent des états de fonctionnement du dispositif selon la présente invention.

- Figure 1 is a front view of the automatic device for drawing outward the cutting line of a lawn mower, according to the present invention; - Figure 2 is a top view of the automatic device for drawing outward the cutting line of a lawn mower according to the present invention; - Figure 3 is a fragmentary view on a larger scale of part A in Figure 1; - Figures 4,5 and 6 show operating states of the device according to the present invention.

 In the drawing, 1 designates an output shaft, 2 designates a wire casing, 3 designates a spool of wire, 4 designates a rock wheel, 5 designates a rock, 6 designates a stop block, 7 designates a return plate , 8 designates a core pin, 9 designates a spring, 10 designates a hole to accommodate the core pin, 11 designates a guide hole, 12 designates a guide bar and 13 designates a cutting wire.

 Figures 1 and 2 show the automatic device for drawing outward the cutting line of a lawn mower according to the present invention. As shown in FIGS. 1 and 2, the automatic device for drawing the cutting line of a lawn mower according to the present invention to the outside comprises: a wire box 2 connected to an output shaft 1, a spool of wire 3 disposed in the wire housing 2, a plurality of turns of wire 13A wound on the wire spool 3, and the ends of the wire extended outward from the wire housing 2 to form the cutting wire 13, a rock wheel 4 arranged on the wire spool 3, a plurality of rocks 5 arranged on the rock wheel 4, a stop block 6 arranged to press on one of the rocks 5, a return plate 7 disposed against the stop block 6, a core pin 8 (Figure 3) on which are mounted the return plate and a spring 9, and a piece of cutting wire 13. When the stop block 6 blocks the rock 5, the roller wire 3 is integrated in the wire housing 2. Referring to Figure 3, an extr emitted from the core pin 8 is fixed to the wire housing 2 in the diametrical direction and the spring 9 pushes the return plate 7 so that the stop block 6 remains on the rock 5. A hole 10 to accommodate the core pin is arranged on the wall of the wire housing mentioned above, in the diametrical direction. The core pin 8 is a bolt-shaped pin and it is mounted on the wire housing 2 with the screw 8A which passes through the core pin hole 10. The return plate 7 on the stop block 6 is mounted on the core pin 8 through a guide hole 11 in the upper part of the wire housing 2. On the lining wall of the wire housing 2, a bar 12 guide is arranged next to the stop block 6 which, under the action of the spring 9 and

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 of the centrifugal force F, moves along the guide hole 11 and the guide bar 12 in the diametrical direction.

 The present invention uses the stop block 6 and the rock wheel 4 to connect or disconnect the wire spool 3 and the wire case 2. The stop block 6, under the action of the spring 9 and the centrifugal force, moves along the diametrical direction in the guide hole 11 inside the wire housing 2. When the stop block 6 blocks a rock 5, the wire housing 2 is connected with the wire spool 3 and this the latter will rotate with the wire housing 3. When the stop block 6 detaches from the rock 5, the wire coil 3 is impregnated by the centrifugal force acting on the cutting wire 13 and it rotates freely relative to the wire housing 2. In this way, the cutting line 13 extends to a correct length.

 Figures 4,5 and 6 show the operating state of the automatic device for drawing out the cutting line of a lawnmower, according to the present invention. As shown in Figure 4, the lawn mower turns in direction B. When the abrasion shortens the cutting line 13, the cutting resistance is reduced, so that the speed of rotation of the output axis 1 increases , and thus the centrifugal force increases. The stop block 6 then overcomes, due to the greater centrifugal force F, the elastic force of the spring 9 to move towards the centrifugal direction, that is to say towards the outside. As shown in FIG. 5, when the stop block 6 continues to move towards the centrifugal direction, the stop block 6 ends up escaping from the rock 5. The coil of wire 3 is then subjected to the centrifugal force s' acting on the cutting line 13, and turns in direction C (see FIG. 5) with respect to the wire box, overcoming the blocking of the rock, so as to stretch the cutting line 13 outwards. After this step, as shown in FIG. 6, the cutting resistance increases and the speed of rotation of the output axis 1 slows down, so that the centrifugal force acting on the stop block 6 is less than the elastic return force of the spring 9. After this step, the stop block 6 moves towards the centripetal direction (that is to say towards the inside) and comes to press the next rock (retaining ramp) 5.

 The present invention has a simple structure and convenient operation. The device according to the invention is mainly capable of automatically stretching the cutting line outward, to maintain the correct working length of the cutting line and to keep the lawn mower permanently in its best operating condition.

 Of course, the present invention is not limited to the embodiment described and shown, but it is capable of numerous variants easily accessible to those skilled in the art, without departing from the scope and of the spirit of the invention.

Claims (2)

 CLAIMS 1. Automatic device for drawing outward the cutting line of a lawn mower, comprising: a wire box (2) connected to an output shaft (1), a wire spool (3) in the wire housing (2), a cutting wire (13) wound on the wire spool (3), characterized in that a rock wheel (4) provided with a plurality of rocks or retaining ramps (5 ) is placed on the wire spool (3), a stop block (6) is placed in the pressing position on one of the rocks (5), a return plate (7) is placed on the stop block ( 6), the return plate (7) and a spring (9) are mounted on a core pin (8), the core pin (8) is fixed to the wire housing (2) in the diametrical direction, and the spring (9) presses the stop block (6) against the rock (5).  2. Automatic device for drawing outward the cutting line of a lawn mower according to claim 1, characterized in that a hole (10) in the core spindle is arranged on the wire housing (2) in the diametrical direction, the core pin (10) is a bolt-shaped pin and is mounted on the wire housing (2), the screw being screwed into the hole (10) of the core pin, the stop block (6) is arranged in the wire housing (2), the return plate (7) on the stop block (6) is mounted on the core pin (8) through a guide hole (11) at the upper part of the wire box (2), a guide bar (12) is arranged on the lining wall of the wire box (2) next to the stop block (6).