EP0118516A1

EP0118516A1 - Grassmower

Info

Publication number: EP0118516A1
Application number: EP19830902887
Authority: EP
Inventors: Eberhard Maucher
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-09-04
Filing date: 1983-09-02
Publication date: 1984-09-19
Also published as: WO1984000873A1

Abstract

Tondeuse à gazon ou faucheuse dotée d'un moteur électrique encastré dans un boîtier ouvert vers le bas avec un axe perpendiculaire, d'un couteau à deux pales fixé sur l'axe du moteur, ainsi que d'une barre ou d'un archet articulé avec le boîtier et servant à sa manipulation. L'invention est une combinaison des caractéristiques suivantes: a) Le moteur électrique (1) est un moteur à haute vitesse dont le nombre de tours de travail va de 6000 à 10000 par minute. b) Le couteau est un couteau à hélice (9, 9a) qui exerce une action de succion vers le haut, parallèlement à la direction de l'axe du moteur. c) Le diamètre du cercle de coupe du couteau (9, 9a) est de 140 à 200 mm. d) Entre le moteur (1) et le couteau (9, 9a) se trouve sur l'axe du moteur (7) une roue de ventilation (8, 8a) qui souffle sur le moteur (1) de l'air de refroidissement aspiré (22) dans une soufflerie (11) concentrique par rapport à l'axe du moteur. e) Pour son déplacement, on a prévu sur le côté du manche ou de l'archet du boîtier (5) deux roues (10) ou roulettes, ainsi qu'un ou plusieurs patins (6) fixés à l'extrémité du boîtier et s'étendant au-dessous du couteau (9, 9a).Lawn mower or mower with an electric motor embedded in a box open downwards with a perpendicular axis, a two-blade knife fixed on the axis of the motor, as well as a bar or a bow articulated with the housing and used for its manipulation. The invention is a combination of the following characteristics: a) The electric motor (1) is a high speed motor, the number of working revolutions of which ranges from 6000 to 10000 per minute. b) The knife is a propeller knife (9, 9a) which exerts an upward suction action, parallel to the direction of the axis of the motor. c) The diameter of the knife cutting circle (9, 9a) is 140 to 200 mm. d) Between the motor (1) and the knife (9, 9a) is located on the axis of the motor (7) a ventilation wheel (8, 8a) which blows on the motor (1) cooling air sucked (22) in a blower (11) concentric with the motor axis. e) For its displacement, two wheels (10) or casters, as well as one or more pads (6) fixed to the end of the housing, are provided on the side of the handle or of the housing bow (5). extending below the knife (9, 9a).

Description

Lawn mower or grass cutter

The hobby gardener currently has two types of equipment available to care for his lawn. These are the lawn mowers of various sizes operated by an electric motor or carburettor motor, as well as the light lawn edge cutters that are operated exclusively by an electric motor.

The latter devices are an addition to the lawnmowers, because it is not possible with the lawnmowers of conventional design to cleanly cut the lawn on walls, house edges, projections, etc. As a rule, the front wheels of the lawnmower, which lie outside the knife cutting circle, limit the range of action of these lawnmowers.

In order not to have to laboriously remove the remaining lawn remnants from these inaccessible places, the lawn edgers came on the market a few years ago, which work with a plastic thread that is rotated by a high-speed electric motor. With the help of these thread cutters, however, the degree is not defined cut off, which sometimes results in frayed cut edges. Furthermore, there is no defined cutting height with these thread cutters of conventional embossing, which often leads to the turf being broken open and the grass plants being uprooted.

The invention is based on the object of specifying a device design which can be used both as an edge cutter and as a small lawn mower. This device design is based on a lawn mower or grass cutter, consisting of an electric motor installed in a housing that is open at the bottom with a vertically arranged axis, a double-bladed knife attached to the axis of the motor and a rod or bracket that is attached to the housing and is used to handle it.

The construction according to the invention is characterized by the combination of the following features:

a) The electric motor is designed as a high-speed motor with a working speed between 8000 and 12000, preferably of 10,000 revolutions per minute.

b) The knife is designed as a propeller knife, which exerts a suction effect upwards, parallel to the axis direction of the motor.

c) The knife has a cutting circle diameter of 140-200 mm, preferably 190 mm.

d) Between the motor and knife is on the motor axis a fan wheel is arranged, which blows cooling air sucked in via the motor into a wind tunnel running concentrically to the motor axis.

e) Two wheels or rollers and one or more runners running beneath the knife are provided for its movement on the handle or bracket side of the housing.

High-speed electric lawnmowers with a fan wheel on the motor axis are already known as so-called air cushion mowers; In these mowers, however, the fan wheel is used to generate an overpressure in the housing space below the motor, which is to lift the mower from the ground by 1 to 2 cm so that it can be moved back and forth on the lawn area - air cushion mowers have no wheels.

In contrast to this known lawn mower, a suction effect is produced in the device according to the invention by the existing fan wheel in cooperation with the propeller-shaped knife, as a result of which grass that has been depressed is erected and leaves and left-over mowing material are conveyed into a grass catcher bag. For this purpose, the underside of the housing is designed as a wind tunnel, the end of which is designed as a connection for a windsock. By limiting the cutting circle diameter of the knife to 140 to 200 mm, the peripheral speed of the cutting edges of the knife is kept within such limits despite the high engine speeds that a mulching of the ge cut lawn within the lawn cutter housing is largely avoided.

This device concept requires sufficient engine power to guide the airflow that is sucked in and used to transport the cut grass into a grass catcher bag. However, if you want a pronounced small device, which - for reasons of weight - should get by with a minimal engine power, you have to strive for optimal use of the generated air flow to extract the cut grass and to transport it into the grass catcher bag or grass catcher basket without risk of clogging the air duct .

In this case, it may be expedient to replace the radial guidance of the air flow used in the device concept according to the invention by a wind tunnel which effects an axial guidance of the air flow.

For this purpose, the housing, which is open at the bottom, is designed in the manner of a pot, in the bottom of which the motor holder is inserted concentrically and the part of the pot circumference lying in the direction of the handling rod or bracket merges into an outlet funnel to which a grass catcher bag or basket is applicable.

The advantage of this modified device design is that the air sucked in by the propeller knife and the cut grass particles taken along with this air flow are conveyed in the shortest possible way into the grass catcher bag or basket. Friction losses in the air, which arise with their radial guidance are avoided in this way.

The replacement of the front wheels of conventional lawnmowers with runners that run below the knife makes it possible to use the grass cutter according to the invention in a manner similar to the known lawn edge cutters mentioned above in corners, on house walls and other inaccessible taxes. Thus, the grass cutter according to the invention can generally replace the smaller lawn mowers on the market and the lawn edge cutters.

For the implementation of the new construction, it is recommended to use a collector motor with a working speed of around 10,000 revolutions per minute and a propeller knife with a cutting circle diameter of 190 mm. The collector motor has the advantage that its characteristic curve is better adapted to the working conditions at the intended speed than with an induction motor.

It has already been mentioned that the grass cut with the lawn mower or grass cutter according to the invention is to be removed immediately from the device via the wind tunnel. For this purpose, a grass bag or basket is attached to the end of the wind tunnel. In the case of a grass catcher basket, this can be designed as a skid or can have one or more skids, in order in this way to give the device better stability. The grass catcher can also be provided with an additional support wheel.

When replacing the front wheels of conventional lawn mowers with a runner, the latter is expediently attached to the front part of the housing symmetrically to the rear wheels. At the same time, it is advisable to attach the two rear wheels to the housing with a track width that is smaller than the diameter of the cutting circle cover. So it will. possible to mow along obstacles such as walls, fences, etc. by letting the edge of the obstacle lie tangentially to the cover of the cutting circle diameter of the lawn cutter. The spacers designed as skids on the front of the device prevent the cutting height from being varied. The mowing material that is not gripped by the cutting edge of the knife is drawn into the effective area of the cutting edges by the suction of the knife and thus also gripped by the knife.

When designing the device with axial guidance of the air flow, it is advisable to give the outlet funnel a width which corresponds to the diameter of the housing pot in order to make optimum use of the sucked-in air.

With this design, it is advisable to ensure that the pot holding and covering the motor continuously passes into the outlet funnel that rises upwards. There is then space below the outlet funnel for a storage box for two wheels or rollers which serve to move the device. These wheels or rollers are appropriately attached in the storage box so that they are ten walls of the funnel or the diameter of the pot or at least not significantly protrude. This makes it possible for the device to cut standing grass directly on walls, walls, projections, etc. without the wheel being obstructed.

In this construction, the motor mount consists of a tubular housing which encloses the stator and the rotor of the motor over its entire length and is integrated into the pot of the device housing. A fan wheel is arranged on the motor axis in the same way as in the device with radial air flow between the motor and the knife; The housing of the gate then has one or more openings on its upper side and on the parts of its underside lying in the direction of the funnel, which outside air sucked in by the fan wheel pass through the space between the stator and rotor of the motor and allow it to exit into the outlet funnel. This cooling air then takes the same route as the air drawn in by the propeller knife.

The handling rod or bracket of this device design is expediently attached to the upper boundary wall of the funnel, for which an insertion device is provided.

The grass catcher bag or basket can be designed as a stable container with gauze-shaped walls, which can be attached to the funnel opening. If you choose such a stable design, this grass catcher can also be provided with an opening flap through which the suctioned grass can be removed. Such a grass catcher can also be designed as a skid or have one or more skids. Finally, it would also be possible to provide this grass catcher with an additional support wheel.

Although the known lawn edge cutters mentioned at the outset also have certain disadvantages in addition to their advantages, for example the unclean cutting surface of grasses, it is nevertheless advisable to combine the lawn mower or grass cutter according to the invention with such a lawn edge cutter if necessary, in order to do so in the same operation if necessary, remove any remaining blades of grass.

According to a development of the invention, the thread drum of a conventional thread lawn edger should therefore also be fastened on the axis of the motor of the lawn mower or grass cutter. The high-speed motor of the grass cutter according to the invention is excellently suitable for driving such a thread drum at the same time.

When working with such a combined device, two cutting elements, namely the built-in knife and the thread of the thread drum, take effect simultaneously.

It is recommended that the knife and the effective part of the thread with respect to the thread drum their design features are coordinated so that the thread flight diameter plane overlaps the diameter plane of the knife flight circle. This linear overlap should be approximately 25 mm.

In this case, the grasses that remain in a circular ring outside the knife turning circle are cut off by the thread of the thread cutter.

In the practical development of this additional proposal, it is expedient to design the axis of the motor or a fastening device attached to it in such a way that the thread drum of a lawn edger can be optionally plugged onto this axis. So you can operate the lawn mower or the grass cutter without this thread cutter.

So that the thread of the thread cutter always has a length limited by the position of the wheels of the device, a knife limiting the thread length is attached to the lower edge of the device housing.

As is known, the free end of the thread cutter is continuously shortened during operation or, if necessary, cut off by obstacles. With a lawn edger, it is therefore necessary to pull the thread out of the drum a little at a time in order to effectively stitch the thread cutter again. It is already known that this extension of the thread can be carried out by remote control or by pressure on the thread drum. In the context of the present invention, it is particularly recommendable to use either such remote control, e.g. B. by a leading through the operating handle of the device Bowden cable or to implement the principle of pressing on the thread drum in a suitable manner. In the lawn mower or grass cutter according to the invention, such remote control or direct action on the thread drum is of particular importance because such a device is much heavier and more compact than a conventional lawn edger, so that one does not simply pull the thread out of the drum by hand can pull out another piece, as is usually the case with simple lawn edge cutters.

Regarding the construction of the lawn mower or grass cutter according to the invention, it should also be pointed out that both its housing and its engine cover can be made as an injection molded part from a plastic that complies with the safety regulations. In this way, an often desirable reduction in the weight of the device is achieved compared to metallic housing parts.

Exemplary embodiments of the lawn mower or grass cutter according to the invention are shown in the drawings.

Fig. 1 shows a grass cutter according to one variant of the invention in side view, in a section through the housing and the engine cover. 2 and 3, the device is shown in a perspective view and in FIG. 2 again in a section through the motor and housing with the grass catcher removed, while in Fig. 3 the device with attached cover and inserted handle for actuating the grass cutter is drawn.

4, 5 and 6, the second variant of the invention is drawn in one embodiment. Fig. 4 shows a vertical longitudinal section through the device, Fig. 5 is a view from below and Fig. 6 is a view from above.

According to the exemplary embodiment according to FIGS. 1 to 3, the device according to the invention has a collector motor 1, which is fastened in the housing 5 of the grass mower with a vertical motor axis. A fan wheel 8 and a two-blade knife 9 are fastened on the motor axis 7. In addition, the housing has two rear wheels 10 which are fastened to it with a track width which is smaller than the diameter of the cutting circle cover. A skid 6 is fastened symmetrically to these rear wheels 10 in the front part of the housing 5 and serves as a skid during the movement of the grass cutter. The underside of the housing 5 is also formed as a wind tunnel 11 concentrically surrounding the axis 7, which opens into a flange for attaching a grass bag 13 or a corresponding grass catcher.

The fan wheel 8 is equipped with wind blades 8a, the knife 9 at both ends propeller blades 9a. The mode of operation of the fan wheel 8 - 8a and of the knife 9 with the propeller blades 9a is that on the one hand cooling air is sucked in from the outside through the fan wheel and passed through the open motor 1, which is only enclosed by the housing cylinder 3, and is then carried away by the propeller knife 9 cut grass to get into the wind tunnel 11. The entry of the cooling air is indicated by the arrow 22, the exit from the wind tunnel 11 by the arrow 12. In addition, the propeller knife 9 air according to the arrows shown from below, d. h sucked from the ground and also transferred into the wind tunnel. When the air is sucked in from below, the blades of grass are raised and thus prepared for cutting by the propeller knife 9. The cooling air flow, which thus simultaneously transports the cut grass to the outside via the wind tunnel 11, runs in the direction of the arrows 22, 4 and 12.

To actuate the device, the housing has an actuating handle 14 which can optionally be tilted into the positions 15 shown; a device with corresponding catches is provided for this.

The operating handle 14 has an operating handle 18 at its end and a handle 17 in its upper third. In the operating handle 18, the motor switch 19 is provided, which enables the motor to be switched on via the mains cable 20 and a corresponding plug 21. A suspension device 16 is also provided on the handle 14 for fastening the grass collecting bag 13. The grass bag can be attached to this hanging device.

To protect the motor, the cover 2 is designed so that the motor is sealed off, including the housing cylinder 3, i. H. Cooling air can be drawn in for the engine, but no splash water can enter the engine. The housing 5 and the cover 2 can consist of metal or partially of metal and plastic. It is expedient, however, to manufacture these parts by injection molding from a plastic of sufficient strength in order to reduce the weight of the grass cutter to a minimum.

The runner 6 shown in the exemplary embodiment can also be designed and fastened in a different way. For example, it would be possible to hold this skid on the rear part of the housing 5, for example where the wheels are attached, or to provide two or more skids.

In the embodiment shown in FIGS. 4, 5 and 6, a pot-shaped device housing 23 can be seen, in which the motor housing 25 is integrated. The pot 23 is cut open in the direction of the operating side of the device and merges into the outlet funnel 24.

At this outlet funnel is a grass bag or basket 43 attached or attached. Since the outlet funnel 24 extends obliquely upwards, there is space below for a storage box 40 which accommodates the storage of two locomotive wheels 41.

The parts 23, 24, 25 and 40 mentioned represent a single plastic part which is expediently produced from an injection molding process which corresponds to the safety regulations.

The motor consisting of rotor 27 and stator 28 is inserted into the motor housing 25, the shaft of which first carries a fan wheel 29 on its underside and then a double-bladed knife 30. The two knife blades 31 and 32 are designed as propeller blades in order to exert a suction effect in the direction of the motor axis. The motor itself is designated 26 in FIG. 4. The lower end of the motor axis still carries a thread drum 44 corresponding to the thread drums as used in Rasehkantenschneidera.

The upper opening of the motor 26 is covered by a cover cap 33 which has air inlet openings 34 on an inclined side, through which air is sucked in under the influence of the rotating fan wheel 29 in the direction of the arrow 35 and is sucked in according to the dashed line between the rotor 27 and the stator 28. This cooling air then arrives in the outlet funnel 24 in accordance with the arrow 36 shown. An escape of this cooling air on the opposite side is prevented by a flange shoulder 49 on the motor housing 25. 4, the path of the engine cooling air is identified by the two double-hatched arrows 35 and 36. The air sucked in by the wings 31 and 32 of the knife 30 - represented by the arrows 37 and 38 - then takes its course in the direction of the hatched arrows 39.

5, the thread drum 44 can be seen, which is attached to the end of the motor axis, as well as the pulled thread 45, which is always cut to a constant length by a knife 46 attached to the lower extended boundary edge 47 of the pot-shaped device housing 23 .

The handling of this grass cutter is detected with the aid of a rod or bracket 14 which is held in an insertion guide 48 provided at the upper end of the outlet funnel 24. This handling rod has an actuating handle 18 and a handle 17 in order to be able to operate the grass cutter with both hands. A motor switch 19 is provided in the operating handle 18 and is connected to the cable 42 leading to the motor. The connection cable with plug itself is designated 20.

From Fig. 6 you can still see the already mentioned cap 33, which is shown in dashed lines in this Fig., Because it is to be thought of as removed. This cover cap must be placed watertight to prevent water from entering the motor housing. This embodiment of the invention has the advantage over that of FIGS. 1 to 3 that clogging of the suction channel with cut grass is practically no longer to be feared. This applies in particular if the outlet funnel 24 is allowed to rise at an angle between 20 and 40 degrees, preferably below 27 degrees, with respect to the horizontal.

With regard to the thread drum 44 that can be plugged onto the motor axis, it should be pointed out that knives and thread will not be used together in the illustrated device design according to FIGS. 4 to 6; d. H. predominant operation will be the fixed knife and only if blades of grass cannot be reached on the edge with it, one will cut with the thread (by putting on the thread spool). However, it is recommended that the thread drum be plugged onto the axis of the drive motor in such a way that the cutting plane of the thread is lower than the cutting plane of the knife. The difference between these two cutting planes should suitably be at least 4 mm.

Claims

Claims:

1. A lawn mower or grass cutter, consisting of an electric motor installed in a downwardly open housing with a vertically arranged axis, a two-bladed knife attached to the axis of the motor, and a rod or bracket that is hinged to the housing and is characterized by the combination of following features:

a) The electric motor (1) is designed as a high-speed motor with a working speed between 6000 and 10000 revolutions per minute.

b) The knife is designed as a propeller knife (9, 9a), which exerts a suction effect upwards, parallel to the axis direction of the motor.

c) The knife (9, 9a) has a cutting circle diameter of 140-200 mm.

d) Between the motor (1) and knife (9, 9a), a fan wheel (8, 8a) is arranged on the motor axis (7), which cooling air (22) sucked in via the motor (1) into a wind tunnel running concentrically to the motor axis (11) blows out. e) To move it, two wheels (10) or rollers and one or more runners (6) held on the edge of the housing are provided on the handle or bracket side of the housing (5) and below the knife (9, 9a).

2. A lawn mower or grass cutter containing an electric motor which is installed with a vertically arranged axis in a housing which is open at the bottom, a two-bladed knife fastened to the axis of the motor and a rod or bracket which is hinged to the housing and is characterized by the Combination of the following features:

a) the electric motor (26) is designed as a high-speed motor with a working speed between 8000 and 12000 revolutions / min., preferably one of 10,000 revolutions / min.

b) The knife (30) is designed as a propeller knife, which exerts a suction effect upwards, parallel to the axial direction of the motor (26).

c) The knife 30 has a cutting circle diameter of 140 to 200 mm, preferably of

190 mm.

d) The downwardly open housing (23) is designed in the manner of a pot, in the bottom of which the motor holder is inserted concentrically and the part of the pot circumference lying in the direction of the handling rod or bracket (14) an outlet funnel (24) passes to which a grass bag or basket (43) can be attached.

3. Grass cutter according to claim 1, characterized in that the electric motor (1) is designed as a collector motor and has a working speed of about 8000 revolutions per minute.

4. Grass cutter according to claim 1 or 2, characterized in that the propeller knife (9, 9a, 31, 32) has a cutting circle diameter of 180 mm.

5. Grass cutter according to claim 1 to 4, characterized in that a grass bag or basket (13, 43) is attached to the end of the wind tunnel (11, 24).

6. Grass cutter according to claim 1 to 5, characterized in that it has a runner (6) which is fixed symmetrically to the rear wheels (10) on the front part of the housing (5).

7. Grass cutter according to claim 1 to 5, characterized in that the wheels (10) with a track width on the housing (5) are attached, which is smaller than the diameter of the cutting circle cover.

8. Grass cutter according to claim 1 to 7, characterized in that the grass catcher (13) is designed as a skid or has one or more skids.

9. Grass cutter according to claim 1 to 8, characterized in that the grass catcher (13) is provided with an additional support wheel.

10. Grass cutter according to claim 1 to 9, characterized in that both its housing (5) and its engine cover (2) are made as injection molded parts from a plastic that meets the safety regulations.

11. Grass cutter according to claim 2, characterized in that the outlet funnel (24) has a width corresponding to the diameter of the housing pot (23).

12. Grass cutter according to claim 2 and 11, characterized in that the motor (26) holding and covering pot (23) merges continuously into the outlet funnel (24) rising upwards and that below the outlet funnel (24) a storage box (40) is provided for two wheels or rollers (41) serving to move the device.

13. Grass cutter according to claim 2, 11 and 12, characterized in that the wheels or rollers (41) are mounted such that they do not, or at least not significantly, project beyond the side walls of the funnel (24) or the diameter of the pot (23) .

14. Grass cutter according to claim 2, and 11 to 13, characterized in that the motor bracket from a stator (28) and the rotor (27) of the motor (26) over its entire length and in the pot (23) of the device integrated tubular housing (25).

15. Grass cutter according to claim 2 and 14, characterized in that on the motor axis between the motor (26) and knife (31, 32) a fan wheel (29) is arranged and that the housing (25) of the motor (26) on its top and on the parts of its underside lying in the direction of the funnel (24), one or more openings which pass through the space between the stator (28) and rotor (27) of the motor (26) and into the outside air sucked in by the fan wheel (29) Let the funnel (24) emerge.

16. Grass cutter according to claim 2 and 11 to 15, characterized in that the handling rod or bracket (14) is fixed to the upper boundary wall of the funnel (24).

17. Grass cutter according to claim 1 to 16, characterized in that the grass catcher bag or basket (43) is designed as a stable container with gauze-shaped walls, which can be attached to the funnel opening.

18. Grass cutter according to claim 17, characterized in that the grass catcher bag or basket (48) is designed such that its upper boundary surface approximates the handling rod or bracket (14).

19. Grass cutter according to claim 17 and 18, characterized in that the grass catcher is designed as a skid or has one or more skids.

20. Grass cutter according to claim 17 and 19, characterized in that the grass catcher (43) is provided with an additional support wheel.

21. Grass cutter according to claim 1 to 20, characterized in that the knife-carrying axis of the motor is designed such that the thread drum (44) of a conventional thread lawn edger can also be plugged onto it.

22. Grass cutter according to claim 21, characterized in that on the lower edge (47) of the housing (23) a thread length limiting knife (46) is attached.

23. Grass cutter according to claim 1 to 22, characterized in that the knife (39) and the effective part of the thread (45), the thread drum (44) are matched to one another such that the thread flight diameter plane overlaps the diameter plane of the knife flight circle.

24. Grass cutter according to claim 23, characterized in that the linear overlap is about 25 mm.

25. Grass cutter according to claim 21 to 24, characterized in that the thread drum (44) can be plugged onto the axis such that the cutting plane of the thread is lower, preferably by at least 4 mm, 30 than the cutting plane of the knife (5).

26. Grass cutter according to claim 21 to 25, characterized in that it has a remote control for thread extension, for. B. contains a Bowden cable.

27. Grass cutter according to claim 21 to 25, characterized in that the thread bobbin and its attachment are designed such that a thread extension is caused by the thread bobbin during a tipping process of the device.