DE102016010975B4 - Lawn mower with magnetic collector for knife blade fragments and metal objects - Google Patents

Abstract

The invention relates to a lawn mower (2) with a magnetic collector for knife blade fragments (1.1, 1.2) and metallic objects, having at least one permanent magnet (4a, 4b, 4c) which attracts the knife blade fragments (1.1, 1.2) and the metallic objects, and at least a device (5.1, 5.2) which holds the permanent magnet (4a, 4b, 4c) in position over a substrate.
According to the invention, at least one device (5.1, 5.2), which holds the at least one permanent magnet (4a, 4b, 4c) in position, can move the at least one permanent magnet (4a, 4b, 4c) up and down over the ground (G ) and that the at least one device which holds the at least one permanent magnet (4a, 4b, 4c) in position is a rocker tared by at least one counterweight and/or by at least one spring, the at least one permanent magnet (4a, 4b , 4c) is freely movable or attached to the seesaw via a cantilever.
The advantage of this is that the magnet collects metal objects without braking the lawnmower.

Description

The invention relates to a lawn mower with a magnetic collector for knife blade fragments and metal objects, comprising at least one permanent magnet which attracts the knife blade fragments and the metal objects, and at least one device which holds the permanent magnet in position over a ground.

Modern lawnmowers, in particular battery-powered lawnmowers, have a lower power than lawnmowers with internal combustion engines or with mains-powered electric motors in order to make the lawnmower as light as possible. A battery or rechargeable battery should have the lowest possible weight, which means that the charge capacity is correspondingly lower. These lower powered lawn mowers have a high speed rotating shear mechanism that has razor blade type or box cutter type single blades. The lawn is finely shredded by the high-speed shearing mechanism, with the lawn clippings being mulched. The very fine lawn clippings fall into the turf immediately after being shredded, where they compost in a comparatively short time and act as lawn fertilizer. The high speed of the rather very fine knives leads to their high sensitivity to breakage on stones, metal objects, but also on small branches lying in the grass, chestnuts or acorns. When the fine knife blades break, fragments of knife blades fall into the grass and remain there, posing a high risk of injury for children playing or for people walking barefoot across the automatically mowed lawn.

In the pamphlet U.S. 3,646,736 A teaches a lawn mower having a magnet assembly for picking up nails, tin cans and other items of magnetic material from the ground. However, the magnet must be lowered by hand at a location that can be assessed as suitable using a lever or rod construction. Similarly, the partly magnetic roller in the publication JP 2004113091A learned lawn mower can be adjusted via a height adjustment mechanism. The pamphlet US 2003/0 043 005 A1 teaches a modular magnetic tool system adapted to be mounted under a lawnmower, but does not disclose any specific means for efficient and comfortable operation in this use. The one in the pamphlet EP 2 883 437 A1 Although the lawnmower taught has permanent magnets which are arranged in a wheel of the lawnmower and move with this, they are designed according to their function to support the sensory detection of the possibly abnormal state of movement of the driven wheel and not to collect metal parts.

In the US patent U.S. 3,084,495 A it is proposed to attach a trailer to the lawnmower, which has electromagnets or very strong permanent magnets across the width of the shearing mechanism. These magnets are designed to pick up bits of metal from the blade fragments that may accrue while mowing. Towing a trailer with very strong permanent magnets or even the use of electromagnets is unthinkable for an automatic, battery or accumulator-operated lawnmower. The deliberately low capacity of the battery or rechargeable battery would be overused by the trailer or by the electromagnet. Even pulling a towing magnet through the turf behind the automatic, battery-powered lawnmower would significantly reduce the operating time of the lawnmower between two charging cycles, because the towing magnet exerts a not inconsiderable braking effect on the lawnmower.

The object on which the invention is based is therefore to provide a lawnmower which can collect fragments of the blades of a shearing mechanism and which overcomes the disadvantages of the prior art.

The object on which the invention is based is achieved in that at least one device, which holds the at least one permanent magnet in position, guides the at least one permanent magnet over the ground so that it can move up and down. Further advantageous configurations are specified in the subclaims to claim 1.

According to the invention, it is therefore provided that one or more permanent magnets do not have to be dragged or pulled across the lawn with the aid of a mobile device such as a trailer. Rather, it is provided that the at least one permanent magnet rises and falls when the mower is moving. The at least one permanent magnet can be raised and lowered mechanically, for example by a crank mechanism that is connected to the wheels of the lawn mower or to a separate drive. But it is also possible to trigger the lifting and lowering only on request, for example by one or more metal detectors. Finally, it would also be possible to arrange the at least one permanent magnet in one or more than one wheel of the mower, where the permanent magnet rotates with the wheel. In this case, it would be provided that the at least one device which has the at least one permanent mag neten in position is a wheel of the lawn mower, wherein the at least one magnet is arranged in the wheel and there near the outer periphery of the wheel. Instead of the wheel, a roller could also be considered. The regular or sporadic lowering of the at least one permanent magnet has the advantage that the braking effect does not occur when towing. Also, it is not necessary to use a very strong magnet, such as is the case when the magnet is held at a constant height above the lawn. What is surprising about the movement of the at least one permanent magnet according to the invention is that despite the supposedly small area on which the at least one permanent magnet actually touches the lawn, the collection efficiency does not suffer. Metal parts that are run over by the mower are picked up by the at least one permanent magnet.

In an advantageous embodiment of the invention, it is provided that the at least one device, which holds the at least one permanent magnet in position, lowers and raises the at least one permanent magnet regularly or on demand. A drive is intended for this purpose, which lowers the at least one permanent magnet on regular request or after detection of a metal part and raises it again shortly thereafter. According to the invention, the at least one device that holds the at least one permanent magnet in position is a seesaw tared by at least one counterweight and/or by at least one spring, with the at least one permanent magnet being freely movable or attached to the seesaw via a cantilever is. The tared seesaw has the advantage that the energy for raising and lowering the permanent magnet only has to overcome the friction of the seesaw and the weight of the metal parts that are picked up. The balanced rocker thus helps to save considerable energy, which is rare on board an automatic lawn mower.

As already mentioned, it can also be provided that the lawnmower has at least one device for detecting metal, which, when metal is detected, sends a request signal to the device for lowering the at least one device, which holds the at least one permanent magnet in position. Since a metal detector, even when used continuously, consumes much less energy than the mechanical up and down movement of the permanent magnet, battery charging can also be saved in this way.

When lowering the permanent magnet, it could happen that it gets caught in grass nests, in small plants or in small branches on the ground. In order to prevent the lawnmower from being undesirably fixed as a result, a further embodiment of the invention provides for the at least one permanent magnet to be accommodated in a teardrop-shaped housing, with the tapered side of the teardrop shape pointing in the direction of the suspension and the widened side of the teardrop shape in Direction of the sub-surface shows or that the at least one permanent magnet is accommodated in a reduced hull-shaped housing, with the top side of the hull shape pointing in the direction of the suspension and the keel side of the hull shape pointing in the direction of the sub-surface. This is to prevent the permanent magnet from getting caught on the ground. The teardrop shape and the hull shape have proven to be the best.

When using more than one permanent magnet, care must be taken to ensure that the various permanent magnets do not attract one another and thus magnetically wedge or fixate one another. If there is more than one permanent magnet, it is provided that the permanent magnets are suspended in such a way that they cannot touch and are preferably restricted in their mobility so that they only come so close that the permanent magnets cannot be moved into a stable position by their attraction move state.

A lawnmower equipped with the device for collecting metal objects does not necessarily have to mow lawns alone. Provision can also be made for the lawnmower to be a battery-operated, automatic lawnmower which has two operating modes which are independent of one another, a first operating mode comprising “mowing the lawn” and a second operating mode comprising “searching for metal”. Provision can thus be made for the lawn mower to search for metal during the night or when it is idle and to mow the lawn at times when noise is acceptable. Provision can therefore be made for the “search for metal” operating mode to be executed in a time-controlled manner, with this operating mode preferably being active during general quiet times, such as at night or during midday.

Furthermore, it can be provided that a signal light indicates that the at least one device for detecting metal detected metal on the last search trip and thus indicates that there may be metal objects on the at least one permanent magnet.

• 1 Skizzierung eines Messerbruchs eines Scherwerks eines automatischen Rasenmähers,
• 2.1 Skizzierung eines Hecks eines automatischen Rasenmähers mit einem Magnetkamm im angehobenen Zustand,
• 2.2 Skizzierung eines Hecks eines automatischen Rasenmähers mit einem Magnetkamm im abgesenkten Zustand,
• 3 Skizzierung eines Hecks eines automatischen Rasenmähers mit Permanentmagneten in den Rädern,
• 4 Skizzierung eines automatischen Rasenmähers mit einem an einer Wippe aufgehängten Permanentmagneten in einem schiffrumpfförmigen Gehäuse.

The invention is explained in more detail with reference to the following figures. It shows:

• 1 Sketch of a blade breakage of a clipper of an automatic lawn mower,
• 2 .1 sketching of a rear of an automatic lawn mower with a magnetic comb in the raised state;
• 2 .2 sketching of a rear of an automatic lawnmower with a magnetic comb when lowered,
• 3 Sketching a rear of an automatic lawn mower with permanent magnets in the wheels,
• 4 Sketch of an automatic lawn mower with a permanent magnet suspended from a seesaw in a ship's hull-shaped housing.

In 1 a typical individual blade 1 of a heavy mechanism of an automatic lawn mower 2 is shown. The left, undamaged individual blade 1 can suffer the fracture shown on the right side if it touches the ground, if it touches a stone or if it breaks due to wear and tear. The knife breaks into a first knife blade fragment 1.1 and a knife blade fragment 1.2 shown as an example, which falls into the turf G as a substrate and poses a very serious risk of injury to people there.

In 2 .1 is a rear view of an automatic lawnmower 2 with a magnetic comb 3 in the raised state, the magnetic comb 3 consisting of permanent magnets 4a suspended on a common axis 5.2. The permanent magnets 4a are accommodated in drop-shaped housings T in this example. To lift the permanent magnet 4a of the magnetic comb 3, two levers 5.1 lift a common axis 5.2 on which the permanent magnets 4a are lined up. The individual permanent magnets 4a lined up on a common axis 5.2 have stoppers pushed on the axis 5.2 between the suspension points V as spacers, which prevent the individual permanent magnets 4a from swinging sideways at only a small angle, so that the permanent magnets 4a do not move mutually fixed by magnetic attraction. In the right side of the 2 .1 shows the axis 5 with the permanent magnet 4a hanging thereon from an axial view to show that the permanent magnets 4a in this raised state just touch the freshly mown grass at the surface or hang above the surface of the freshly mown grass.

In 2 .2 the rear of the automatic lawn mower 2 is off 2 .1 outlined with a magnetic comb 3 in the lowered state. The individual permanent magnets 4a suspended on a common axle 5 are now partly and forwards, tilted in the direction of travel of the lawnmower 2, on the freshly mown grass and remain there only for a short time due to the lowering and lifting mechanism while the lawnmower 2 is moving lying moment. In the right side of the 2 .1, the axis 5.2 with the permanent magnet 4a hanging from it is shown from an axial perspective, to show that the permanent magnets 4a, in this lowered state, are immersed in the freshly mown grass at an angle in the direction of travel of the lawnmower 2.

In 3 an alternative to the magnetic comb 3 is shown. In this simplest form, permanent magnets 4b are arranged on the inside of the wheels 6 of the lawnmower 2 in such a way that they are located near the outer circumference of the wheel 6. The permanent magnets 4b, which are guided past a metallic object with the respective wheel 6, thus collect the metallic objects.

In 4 an inventive form of the invention is shown, namely in the form of a permanent magnet 4c suspended from a seesaw and a cantilever, which is in the form of a drop or, as in 4 shown, can also be arranged in a hull-shaped enclosure S. The permanent magnet 4c arranged in the housing 7 in the shape of a ship's hull moves when lowered through the freshly mown grass when requested by a device 8 for detecting metal, where it attracts metallic objects. The journey of the permanent magnet 4c through the grass is in 5 shown in more detail. Similar to how a ship swims through waves in a sea, the hull-shaped enclosure S makes its way through the freshly mown grass without getting caught.

Reference List

1

single knife

1.1

Knife blade fragment

1.2

Knife blade fragment

2

mowing machine

3

magnetic comb

4a

permanent magnet

4b

permanent magnet

4c

permanent magnet

5.1

lever

5.2

axis

6

wheel

8th

Device for detecting metal

G

turf (underground)

S

hull-shaped enclosure

T

teardrop enclosure

V

suspension point

Claims (8)

Lawn mower (2) with a magnetic collector for knife blade fragments (1.1, 1.2) and metallic objects, having - at least one permanent magnet (4a, 4b, 4c) which attracts the knife blade fragments (1.1, 1.2) and the metallic objects, and - at least one device (5.1, 5.2) which holds the permanent magnet (4a, 4b, 4c) in position above a substrate, characterized in that - at least one device (5.1, 5.2) which holds the at least one permanent magnet (4a, 4b, 4c) in Holds the position, which guides the at least one permanent magnet (4a, 4b, 4c) so that it can move up and down over the substrate (G), and that - the at least one device which holds the at least one permanent magnet (4a, 4b, 4c) in position, is a seesaw tared by at least one counterweight and/or by at least one spring, the at least one permanent magnet (4a, 4b, 4c) being freely movable or attached to the seesaw via a cantilever. lawn mower after claim 1 , characterized in that the at least one device (5.1, 5.2), which holds the at least one permanent magnet (4a, 4b, 4c) in position, lowers and raises the at least one permanent magnet (4a, 4b, 4c) regularly or on demand . lawn mower after claim 2 , characterized in that it has at least one device (8) for detecting metal, which, when metal is detected, sends a request signal to the device (5.1, 5.2) for lowering, which then switches the permanent magnets (4a, 4b, 4c) briefly lowers. lawn mower after one of the Claims 1 until 3 , characterized in that the at least one permanent magnet (4b) is accommodated in a teardrop-shaped housing (T), with the tapered side of the teardrop shape pointing in the direction of the suspension and the broadened side of the teardrop shape pointing in the direction of the substrate (G), or that the at least one permanent magnet (4c) is accommodated in a reduced hull-shaped housing (S), with the top side of the hull shape pointing in the direction of the suspension and the keel side of the hull shape pointing in the direction of the subsurface (G). lawn mower after one of the Claims 1 until 4 , characterized in that with more than one permanent magnet (4a, 4b, 4c), the permanent magnets (4a, 4b, 4c) are suspended in such a way that they cannot touch each other and are preferably restricted in their mobility so that they only come so close that the permanent magnets (4a, 4b, 4c) do not move into a stable / fixed state due to their attractive force. lawn mower after one of the Claims 1 until 5 , characterized in that the lawnmower (2) is a battery-operated, automatic lawnmower (2) which has two independent operating modes, a first operating mode comprising "mowing the lawn" and a second operating mode comprising "searching for metal". lawn mower after claim 6 , characterized in that the operating mode “search for metal” is executed in a time-controlled manner, this operating mode preferably being active during general quiet times, such as at night or during lunchtime. lawn mower after claim 3 and one of the Claims 6 or 7 , characterized in that a signal light indicates that the at least one device for detecting metal (8) has detected metal on the last search trip and thus indicates that there may be metal objects on the at least one permanent magnet (4a, 4b, 4c).

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