GB2333685A

GB2333685A - Lawn mower

Info

Publication number: GB2333685A
Application number: GB9900542A
Authority: GB
Inventors: Klaus Duerkopp; Herbert Funke; Dietmar Hartmann
Original assignee: Sabo-Maschinenfabrik GmbH; SABO Maschinenfabrik GmbH
Current assignee: Sabo-Maschinenfabrik GmbH; SABO Maschinenfabrik GmbH
Priority date: 1998-02-03
Filing date: 1999-01-11
Publication date: 1999-08-04
Anticipated expiration: 2019-01-11
Also published as: FR2774254A1; GB2333685B; FR2774254B1; NL1010999C2

Abstract

In a lawn mower there is provided a guiding channel 25 with a suction aperture 26 for receiving cut material and an outlet aperture 27 for transferring the cut material to a collecting device 19. The collecting device 19 is associated with a fan 28 which generates a suction flow in the collecting device 19 and in the guiding channel 25. The cutter 13 comprises at least one blade which is wingless. The suction aperture 26 of the guiding channel 25 in the mowing chamber 5 is arranged above the cutting region of the cutter 13, which cutting region is positioned in front if viewed in the normal mowing direction 12. The suction end 29 of the fan 28 is connected to the collecting device 19.

Description

-I- 2333685 Lawn mower with collecting device for the cut material The

invention relates to a lawn mower having a housing which is movable on a lawn surface to be mowed, which is manually guidable by means of a guiding bar and which encloses a mowing chamber which is open towards the lawn surface; having a cutter which is arranged in the mowing chamber so as to be rotatingly drivable around a vertical axis of rotation by a motor; having a collecting device for the cut material separated by the cutter, which collecting device is attached to the housing; having a guiding. channel which comprises a suction aperture for receiving the cut material and an outlet aperture for passing on the cut material, as well as a fan which generates a suction flow in the collecting device.

Such a lawn mower is described in EP 0 457 433 Bl. It is an air cushion mower whose fan generates an air flow which generates an excess pressure in the mowing chamber so that the housing glides on said cushion on the lawn surface. The fan sucks the air out of the collecting device attached to the housing. The collecting device is attached to the housing towards the guiding bar. With the exception of one suction aperture, the collecting device is designed so as to be closed. The suction aperture in the collecting device is arranged close to the lawn surface and is located behind the cutter positioned in front if viewed in the direction of mowing. With this type of arrangement, the cut material initially separated by the mower cutter is deposited on the lawn surface and subsequently - when passed over by the suction aperture sucked into the collecting device. The disadvantage of this embodiment is that the cut material, after having been separated, is first deposited on the lawn surface and then sucked up, an operation which requires a relatively large amount of energy.

The above-described principle is also mentioned in EP 0 643 905 A2 which, additionally, proposes a lawn mower whose housing is movable on wheels and wherein the fan arranged equi-axially relative to the driveshaft sucks the air out of the collecting device and into the mowing chamber. The cut material separated by the cutter is deposited on the ground and received by the collecting device following in the direction of mowing when the suction aperture of same passes over the cut material. The disadvantage of this embodiment is that the cut material is first deposited on the ground and then sucked up by a high suction force.

It is the object of the invention to provide a lawn mower which requires only a small amount of energy for cutting the grass and for transferring the cut material into the collecting device.

In accordance with the invention, the objective is achieved in that there is provided a lawn mower having a 1 housing which is movable on a lawn surface to be mowed, which is manually guidable by means of a guiding bar and which encloses a mowing chamber which is open towards the lawn surface; having a cutter which is arranged in the mowing chamber so as to be rotatingly drivable around a vertical axis of rotation by a motor; having a collecting device for the cut material separated by the cutter, which collecting device is attached to the housing; having a guiding channel which comprises a suction aperture for receiving the cut material and an outlet aperture for passing on the cut material to the collecting device; having a fan which generates a suction flow in the collecting device and in the guiding channel, with the cutter comprising at least one wingless blade, with the suction aperture of the guiding channel being connected to a suction portion of the housing, which suction portion is arranged in the mowing chamber above the cutting region of the cutter, which cutting region, in the normal cutting direction, is positioned in front, and with the suction end of the fan being connected to the collecting device.

The advantage of this embodiment is that the suction portion and the special arrangement of the suction aperture of the guiding channel ensure that the energy required for transporting the cut material is reduced to a minimum, because the cut material is sucked up when it is still in the floating condition in the mowing chamber. Furthermore, the wingless design of the blades also considerably reduces the energy requirements for the mowing operation. In addition, as compared to standard mowers with rear ejection, the wingless design of the blade achieves a considerable reduction in noise. This also applies relative to mowers wherein the effect of the wind wing is achieved by cranking the cutter bar in the region of the blade. In this embodiment, the achievable air flow is very low relative to the energy requirements. The mowing cutter and the blades have to be as f lat as possible so as to achieve the smallest possible flow cross- section during rotation.

By using wingless blades, considerable energy savings are achieved. The cutter can have different designs; for instance, it is possible to choose a cutter bar whose blade portions are attached to its radially outer regions. Alternati vely, it is possible to select an assembly wherein, at one plate, several cutters are attached so as to be circumferentially distributed, which cutters have the shape of a flat iron whose ends are provided with blades. Furthermore, it is possible to arrange a plurality of blades of the sawing tooth type on the circumference of the plate.

The suction portion is preferably formed by an indentation which is directed away from the cutter and which is provided in the ceiling which closes off the mowing chamber towards the top, away from the lawn surface. In addition it is proposed that the cross section of the indentation increases in the direction of rotation of the cutter, that the indentation extends in the form of a sector of a circular ring around the axis of rotation of the cutter at an angle of less than 360 degrees, preferably of approximately 180 degrees and that, in the region of its largest cross-section, the indentation is connected to the suction aperture of the guiding channel. In this way, it is possible to achieve advantageous guiding conditions for the mowed grass. However, to achieve an advantageous mode of operation, it is also sufficient for the suction portion to be formed directly by the mowing chamber portion located between a housing ceiling upwardly sealing the mowing chamber on the one hand, and the cutting region of the cutter on the other hand, and for the suction aperture for the guiding channel to be formed in said mowing chamber portion in the ceiling.

In a first embodiment of the mower it is possible to use the gap between the housing and the lawn surface for sucking in the air. However, there is preferably provided a specific air entry. For this purpose, the housing comprises at least one air entry aperture which is connected to the mowing chamber, and according to a first embodiment, the air entry aperture can be arranged near the suction aperture of the guiding channel. This ensures a rapid removal of the cut material from the cutting region. The cross-section of the air entry aperture can be variable.

Furthermore, because of the low energy consumption it is possible to provide the motor for driving the cutter in the form of an electric motor and to drive the fan also by an electric motor, with the drive for the fan being mechanically branched off from the electric motor for the cutter. However, it is particularly advantageous to provide separate electric motors for driving the cutter and the fan, and because of the low energy consumption, it is possible to use a battery for supplying the drives with energy. Furthermore, in a case where the fan is provided with a separate drive, it is possible for the power of the fan to be controllable. The fan power can be controlled by varying the speed and/or the ejection cross-section of the fan. Furthermore, it is possible for the fan to be associated with the collecting device. The collecting device can be removably connected to the housing, i.e. it can comprise a container attachable to the housing or it may form a receiving chamber which receives a collecting container separated therefrom, with the receiving chamber being at least partially enclosed so as to be air-tight and with the fan being associated with the receiving chamber. To provide a completely airtight seal, part of the collecting container can then form a wall of the receiving chamber. Furthermore, the transport of the cut material in the guiding channel can be controlled by designing the 'outlet aperture of the guiding channel so as to be variable.

In a preferred embodiment, the lawn mower is designed so as to be movable on wheels on the lawn surface. For this purpose the wheels are associated with the housing.

Preferred embodiments of the invention are diagrammatically illustrated in the drawing and explained in greater detail with reference thereto.

Figure 1 is a simplified longitudinal section through an inventive lawn mower in a first embodiment.

Figure 2 is a view from below into the mowing chamber to illustrate the cross-section of the suction aperture.

Figures 3 and 4 show two embodiments which deviate from the cutter according to Figure 2.

Figure 5 shows a further embodiment of an inventive lawn mower, with air being supplied into the front region of the mowing chamber from the upper end of the housing.

Figure 6 shows only the housing of the lawn mower, with air entering at the front face of the housing.

Figure 7 is a simplified longitudinal section through an inventive lawn mower having a fan which is drivable by a separate electric motor.

Figure 8 is a simplified illustration, partially in a longitudinal section, of a lawn mower having an indentation in the housing.

Figure 9 is a simplified illustration of the lawn mower according to Figure 8, in a front view.

In an embodiment of the lawn mower according to Figures 1 and 2, there is provided a housing 1 which is movable by a total of four wheels 2 at the corners, i.e. at the front part 10 and the rear part 11, on a lawn surface 4 for working same. The housing 1 comprises a mowing chamber 5 in the central region which, towards the top, is delimited by the ceiling 7. Towards the bottom, i.e. towards the lawn surface 4, the mowing chamber 5 is open. The opening has been given the reference number 6. The housing 1 is movable on the lawn surface 4 by means of a guiding bar 3 which can be gripped manually by an operative, with the standard mowing direction 12 extending in the direction of the arrow. The front end positioned in front when viewed in the mowing direction 12 has been given the reference number 8 and the rear end positioned at the rear when viewed in the mowing direction 12 has been given the reference number 9. The electric motor 17 supplied by the battery 18 is secured to the outside of the ceiling 7 of the mowing chamber 5.

The electric motor 17 comprises a driveshaft 15 which rotates around the axis of rotation 14. A cutter 13 in the form of a cutter bar is secured to said driveshaft 15 and, at its radially outer portions, comprises blade portions 16 extending over the length L. When viewed in a cross- section, the cutter 13 is planar across its entire width, with the exception of the ground portion in the region of the blade 16, so that the projecting face in the direction of rotation assumes a minimum.

In the ceiling 7, the housing comprises a suction aperture 26 which is approximately kidney-shaped and covers at least a substantial part of the cutting region of the blade 13 when the mower moves in the mowing direction 12. It can be seen that the blade 16 of the cutter 13 is positioned in the region of the radial extension of the suction aperture 26, with reference to the axis of rotation 14. The blade 13 rotates in the direction of the arrow shown in Figure 2 around the axis of rotation 14. The suction aperture 26 ends in a guiding channel 25 which, in turn, ends in a collecting device 19 with the outlet aperture 27. The collecting device 19 comprises walls 22 and a cover 23 which seal said collecting device in a substantially air-tight way and form a receiving chamber 20. Into the receiving chamber 20 there is i. nserted a separate collecting container 21. In the wall of the receiving chamber 20 there is provided an aperture which is provided with a grid 24 to prevent the passage of any cut material. Said aperture is followed by a suction channel 31 which is guided towards the rear part 11 of the housing 1 and in whose lower end, in the region of the ceiling 7, there is provided an aperture to which there is connected a fan 28 whose suction end 29 points towards the suction channel 31. The 1 ejection end 30 points into the downwardly opening rear part 11. The rotor of the fan is drivable by a driving belt 32 which is driven by the driveshaft 15 of the motor 17, i.e. the driving energy for the fan 28 is branched off from the driving motor 17 for the cutter 13. In this way there is generated a suction flow in the suction channel 31, which suction flow is indicated by large arrows and which, due to the fact that the suction channel 31 communicates with the receiving chamber 20, continues to flow into the receiving chamber 20 and into the guiding channel 25. In consequence, the cut material, which is still in the floating condition, is sucked off directly above the cutting region where the grass is separated by the blade 16 of the cutter 13. The floating cut material is indicated by the small arrow. The cut material passes through the suction aperture 26 and enters the guiding channel 25; it is transported by the air flow, leaves through the outlet aperture 27 and enters the collecting chamber 21.

In the process, the air is sucked from the mowing chamber 5 in the cutting region from below, i.e. from the lawn surface 4.

Figure 3 shows an embodiment of the cutter 113 which deviates from the cutter embodiment according to Figure 2 and is of the cutter bar type. There is provided a plate 33 at which there are arranged three bar-shaped blades 116 so as to be circumferentially distributed. The blades 116 are flat. The plate 33 can assume several shapes. It is possible to select a shape which is flow-friendly. Figure 4 shows a further embodiment of a cutter 213, with individual circumferentially distributed blades 216 being arranged at a plate 33, so that a kind of saw tooth shape is achieved.

Figures 5 to 9 show embodiments of inventive lawn mowers which deviate from the embodiment according to Figure 1, with any parts corresponding to those of Figure 1 being provided with reference numbers which are increased by 500 in the embodiment according to Figure 5, by 600 in the embodiment according to Figure 6, by 700 in the embodiment according to Figure 7, and by 800 in the embodiment according to Figures 8 and 9, relative to thos'e shown in Figures 1 and 2.

Figure 5 deviates from the embodiment according to Figure 1 in that there is provided an air supply, with the front part 510, i.e. towards the front 508, in the ceiling 507, being provided with an upwardly directed air entry aperture 535 and an air supply channel 534 which is guided from said air region of the cutter.

entry aperture towards the cutting This means that the air required for transporting the cut material is partially guided through the aperture 506 and through the air entry aperture 535 and the air supply channel 534 close to the suction aperture 526. The cutter may be provided in one of the designs as shown in Figures 2 to 4 Figure 6 only shows the lower part, i.e. the housing 601. The air supply is effected in the region of the end face of the front part 610 which faces the front end 608 and through apertures 635 in the wall of the mowing chamber 605 towards the cutting region of the cutter.

In the embodiment according to Figure 7 a fan 728 is arranged in one of the walls delimiting the receiving chamber 720, which fan 728 is drivable by a separate electric motor, so that the speed of said motor can be controlled separately. Such an embodiment is particularly advantageous because the power of both electric motors 717, 736 can be controlled independently of each other. However, preference is given to an embodiment wherein only the power of the motor 736 driving the fan is controlled.

The embodiments according to Figures 8 and 9 will be described jointly below. Figure 8 shows the housing 801 in a longitudinal section, with the remaining components not being shown in section. In the ceiling 807, the housing 801 comprises an indentation 837 which is directed away from the cutter 813. The indentation 837 extends in the form of a circular ring around the axis of rotation 814 of the cutter 813. The cross-section of the indentation 837 increases continuously in the direction of rotation of the cutter 813. In the region of the largest cross-section, the indentation 837 is connected to the suction aperture 826 of the guiding channel 825. The guiding channel 825 is connected to the collecting device 819 by means of its outlet aperture. The collecting device 819 is secured to the rear part 811 so as to backwardly project beyond same. The fan 8.28 is arranged at the wall of the collecting device 819 which faces the front end 811 of the housing.

The suction portion is thus formed in the indentation 837 which is directed away from the cutter 813 and which is formed in the ceiling 807 of the housing 801, which ceiling 807 seals the mowing chamber 805 upwardly, away from the ground. In consequence, the cut material, when being sucked up, is guided in the indentation 837 from where it reaches the guiding channel 825. In an advantageous embodiment, the indentation 837 extends over an angle of 180 degrees in the cutting region of the cutter 813.

List of 1 2, 3, 4, 5, 505, 605, 6, 506, 606, 7, 507, 8, 508, 9, 509, 10, 510, 11, 711, 12 13, 14, is, 16, 17, 18, 19, 20, 21, 22, 23, reference numbers 501, 601, 701, 801 502, 602, 702, 802 503, 703 504, 604, 704, 804 705, 805 806 707, 807 608, 708, 808 609, 709, 809 610, 710, 810 811 113, 213, 813 514, 614, 714, 814 815 116, 216 517, 617, 717 518, 718 519, 719, 819 520, 720 521, 721 522, 722 523, 723 housing wheels guiding bar lawn surface mowing chamber aperture ceiling front end rear end front part rear part mowing direction cutter axis of rotation driveshaft blade motor battery collecting device receiving chamber collecting container wall cover A, 524 grid 25, 525, 725, 825 guiding channel 26, 526, 626, 726, 826 528, 628, 728, 827 suction aperture f an 29, 529, 829 suction end 30, 530, 830 31, 531 32 33 534 535, 635 736 837 L ejection end suction channel driving belt plate air supply channel air entry aperture fan motor indentation blade length

Claims

1. A lawn mower having a housing (1, 501, 601, 701) which is movable on a lawn surface (4, 504, 604, 704) to be mowed, which is manually guidable by means of a guiding bar (3, 503, 703) and which encloses a mowing chamber (5, 505, 605, 705) which is open towards the lawn surface (4, 504, 604, 704); having a cutter (13, 113, 213) which is arranged in the mowing chamber (5, 505, 605, 705) so as to be rotatingly drivable around a vertical axis of rotation (14, 514, 614, 714) by a motor (17, 517, 617, 717); having a collecting device (19, 519, 719) for the cut material separated by the cutter (13, 113, 213), which collecting device is attached to the housing (1, 501, 601, 701); having a guiding channel (25, 525, 725) which comprises a suction aperture (26, 526, 726) for receiving the cut material and an outlet aperture (27, 527, 727) for passing on the cut material to the collecting device (19, 519, 719); having a fan (28, 528, 628, 728) which generates a suction flow in the collecting device (19, 519, 719) and in the guiding channel (25, 525, 725), with the cutter (13, 113, 213) comprising at least one wingless blade (16, 116, 216), with the suction aperture (26, 526, 626, 726) of the guiding channel (25, 525, 725) being connected to a suction portion of the housing, which suction portion is arranged in the mowing chamber (5, 505, 605, 705) above the cutting region of the cutter (13, 113, 213), which cutting in the normal cutting direction (12), with the suction end (29, 628, 728) being connected to 519, 719).

region, positioned in front, and 529) of the fan (28, 528, the collecting device (19,

2. A lawn mower according to claim 1, characterised in is that the suction portion is formed by an indentation (837) which is directed away from the cutter (813) and which is provided in the ceiling (807) which closes off the mowing chamber (805) towards the top, away from the lawn surface (804).

3. A lawn mower according to claim 2, characterised in that the cross-section of the indentation (837) increases in the direction of rotation of the cutter (813), that the indentation (83-) extends in the form of a sector of a circular ring around the axis of rotation (814) of the cutter (813) at an angle of less than 360 degrees, especially of approximately 180 degrees, and that, in the region of its largest crosssection, the indentation (837) is connected to the suction aperture (826) of the guiding channel (825).

4. A lawn mower according to claim 1, characterised in that the suction portion is formed directly by the mowing chamber portion located between a ceiling (7, 507, 707) of the housing (1, 501, 601, 701), which ceiling upwardly seals the mowing chamber (5, 505, 605, 705), on the one hand, and the cutting region of the cutter (13, 113, 213) on the other hand, and that the suction aperture (26, 526, 626, 726) for the guiding channel (25, 525f 725) is formed in said mowing chamber portion in the ceiling (7, 507, 707).

5. A lawn mower according to claim 1, characterised in that the housing (501, 601) comprises at least one air entry aperture (535, 635) which is connected to the mowing chamber (505, 605).

6. A lawn mower according to claim 5, characterised in that the air entry aperture (535, 635) is arranged near the suction aperture (526, 626) of the guiding channel (525).

7. A lawn mower according to any one of claims 5 or 6, characterised in that the cross-section of the air entry aperture is variable.

8. A lawn mover according to claim characterised in that the motor (17, 517, 617, 717) for driving the cutter (13, 113, 213) is provided in the form of an electric motor and that the fan (28, 528, 628) is rotatingly drivable by the motor (17, 517, 617).

9. A lawn mower according to claim 1, characterised in that the fan (728) is associated with a separate electric motor (736) for driving purposes.

1O.A lawn mower according to any one of claims 8 or 9, characterised in that for supplying the energy for the drives (17, S17, 617, 717) of the cutter (13, 113, 213) and/or fan (28, 528, 628, 728), there is provided a battery (18, 518, 718).

11.A lawn mower according to any one of claims 9 and 10, characterised in 4 that the power of the fan (28, 528, controllable.

628, 728) is

12.A lawn mower according to claim 11, characterised in that for power controlling purposes, the speed and/or the ejection crosssection of the fan (28, 528, 628, 728) can be varied.

13.A lawn mower according to any one of claims 1 to 12, characterised in that the fan (728) is associated with the collecting device (719).

14.A lawn mower according to claim 1, characterised in that the collecting device (19, 519, 719) comprises a receiving chamber (20, 520, 720) associated with the housing (1, 501, 701) and a collecting container (21, 521, 721) which is separated therefrom and which is at least partially enclosed by the receiving chamber (20, 520, 720), and that the fan (28, 528, 628, 728) is associated with the receiving chamber (20, 520, 720).

15.A lawn mower according to claim 1, characterised in that the cross-section of the outlet aperture (27, 527, 727) of the guiding channel (25, 525, 725) is variable.

16. A lawn mower according to claim 1, characterised in that the housing (1, 510, 601, 701) is associated with wheels (2, 502, 602, 702) on which it is movable on the lawn surface (4, 504, 604, 704).