Sealing Member and Sealing System Comprising The Sealing Member

Abstract

A sealing member (2), for waterproof sealing of a volume, comprises a hollow, generally cylindrical body and a sealing area (5a, 5b) at the respective axial ends thereof. At least one sealing area (5a) comprises a first radially extending portion (6) and a second portion (7) extending in a reverse direction partly overlapping the first portion. The second portion (7) has a free end and is arranged for pressing towards the first portion (6), thereby forming a seal with the first portion (6).

A sealing system comprises a sealing member (2) as above, a sealing seat (9) for abutment against the sealing member (2), and a counterpart surface (11), for pressing the sealing member (2) against the sealing seat (9). The sealing seat (9) comprises an inclined surface (10).

A work tool (1) comprising the above-mentioned sealing system has at least one sealing area (5a) of the sealing member (2) pressed between a housing (4) and a chassis (3) of the work tool (1).

Claims

1. A sealing member, for waterproof sealing of a volume, the sealing member comprising a hollow, generally cylindrical body and a first sealing area and a second sealing area at respective axial ends thereof, wherein at least one of the first and second sealing areas comprises a radially extending first portion and a second portion extending in a reverse direction partly overlapping the first portion and having a free edge, wherein the second portion is arranged for pressing towards the first portion, thereby forming a seal with the first portion.

2. The sealing member according to claim 1, wherein at least one of the first and the second portions is curved, to form the first sealing area with an oval cross-section when the first and second portions are pressed towards one another.

3. The sealing member according to claim 1, wherein at least one of the first and the second portions is curved, to form the first sealing area with a ring-shaped cross-section when the first and second portions are pressed towards one another.

4. The sealing member according to claim 1, wherein the first and second portions enclose a volume of air when pressed towards one another.

5. The sealing member according to claim 1, wherein the first and second portions together form a C-shaped cross-section in an unloaded state.

6. The sealing member according to claim 1, wherein the generally cylindrical body is pleated to form a bellows.

7. A sealing system comprising the sealing member according to claim 1, a sealing seat for abutment against the sealing member, and a counterpart surface, for pressing the sealing member against the sealing seat.

8. The sealing system according to claim 7, wherein the sealing seat comprises an inclined surface, such that a transition between the first and second portions of the first sealing area abuts the inclined surface.

9. The sealing system according to claim 8, wherein the sealing seat extends in a circle, and the inclined surface is frusto-conical.

10. The sealing system according to claim 7, wherein the sealing seat comprises a circumferential bead at a free edge thereof.

11. The sealing system according to claim 7, wherein the counterpart surface comprises a circumferential bead.

12. The sealing system according to claim 10, wherein the first sealing area comprises a recess for interlocking engagement with the bead.

13. A work tool comprising the sealing system according to claim 7, wherein the first sealing area of the sealing member is pressed between a hole in a screen and an item extending through the screen.

14. The work tool according to claim 13, wherein at least one of the screen and the item is manufactured from plastics.

15. The work tool according to claim 13, wherein the work tool is a robotic work tool.

16. The work tool according to claim 13, wherein the work tool is a lawn mower.

17. The work tool according to claim 16, wherein the screen is a lower plate of a chassis, and the item is a part of a housing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used for similar elements, wherein:

[0043] FIG. 1 is a sectional view of a robotic work tool, comprising a sealing member according to the disclosure;

[0044] FIG. 2a is a closeup sectional view of the sealing member in a first state;

[0045] FIG. 2b is a view according to FIG. 2a of the sealing member in a second state; and

[0046] FIG. 2c is a view according to FIGS. 2a and 2b of the sealing member in a third state.

[0047] All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate the embodiments, wherein other parts may be omitted.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0048] FIG. 1 illustrates a work tool 1, which in the disclosed embodiment is a robotic lawn mower. The lawn mower 1 comprises a chassis 3 with wheels 17 and a housing 4, which is movably attached to the chassis 3. A lawn mowing unit 18 comprising knives 19 extends downwards through the housing 4 and chassis 3. The lawn mowing unit 18 is surrounded by a sealing member 2, which to a large extent protects the lawn mowing unit 18 from dirt and debris from the lawn mowing. The sealing member 2 has a generally cylindrical shape, and is provided with circumferential pleats, in order to form a bellows-like shape that will accommodate the vertical movement of the lawn mowing unit 18, when the cutting height is adjusted.

[0049] The sealing member 2 is attached at its upper end to the work tool 1, preferably clamped between the chassis 3 and the housing 4. The joint between the chassis 3 and the housing 4 needs to be sealed to provide water and dirt to enter the inner spaces of the chassis 3, so that the lifespan of the work tool 1 will be as long as possible. Also, since the outside of the chassis 3 should be regularly cleaned, the joint between the chassis and the housing 4, where the sealing member 2 is fixed, needs to be watertight as well, in order to keep water from entering the inside of the chassis 3.

[0050] FIG. 2a discloses the sealing member 2 in greater detail. Only a section of the sealing member 2 is disclosed, but since the sealing member 2 and its fixation are approximately cylindrical, all the necessary information should be apparent from FIGS. 2a-2c.

[0051] At the axial ends of the sealing member 2, there are sealing areas 5a, 5b. The lower sealing area 5b is attached to the lower end of the lawn mowing unit 18, so that the knives 19 extend therefrom, but the details of the sealing will not be a part of the present disclosure.

[0052] The upper sealing area 5a of the sealing member 2 is arranged to be clamped between a sealing seat 9 arranged on the chassis 3 and a counterpart surface 11 arranged on the housing 4. A first portion 6 of the sealing area 5a extends radially outwards from the upper end of the sealing member 2. A second portion 7 of the sealing area 5a is joined to the first portion 6 and extends inwards, i. e. in a reverse direction as compared to the first portion. The second portion 7 overlaps the first portion 6 as seen in an axial direction of the sealing member 2. In an unloaded state, as shown in FIG. 2a, the second portion 7 and the first portion 6 are arranged at a distance from one another, together forming a circumferential sealing area 5a with a C-shaped cross-section. The first 6 and second 7 portions are joined at a transition 20. The second portion 7 of the sealing area 5a has a free end 8, which is directed inwards in the radial direction of the sealing member 2.

[0053] In FIG. 2a, the sealing area 5a of the sealing member 2 is positioned on the sealing seat 9 of the chassis 3. The first portion 6 is in contact with a planar, annular area 21 of the sealing seat 9. The transition 20 lightly touches an annular, inclined surface 10 of the sealing seat 9. The inclined surface 10 has a frustoconical shape, which is arranged radially outside of the planar annular area 21 of the sealing seat 9.

[0054] At the radially inner end of the sealing seat 9 an annular bead 12 may be provided. Also, a circumferential recess 15 may be provided between the annular bead 12 and the planar annular area 21. The sealing member 2 may be provided with a circumferential recess 14 mating with the annular bead 12. The sealing member 2 may also be provided with a circumferential bead 16 mating with the circumferential recess 15 of the sealing seat 9. The sealing member 2 may form a labyrinth seal with the sealing seat 9 due to the respective beads 12, 16 and recesses 14, 15. Also, the beads 12, 16 and recesses 14, 15 may serve to position the sealing member 2 correctly before it is clamped between the chassis 3 and the housing 4.

[0055] The counterpart surface 11, formed on the lower part of the housing 4, may be planar, to contact with the upper side of the second portion 7 of the sealing area 5a, when the housing 4 is brought into contact with the chassis 3. In order to increase the clamping effect further, an annular bead 13 may be arranged on the counterpart surface 11, in the disclosed arrangement opposite the bead 12.

[0056] FIG. 2b discloses a second state of the sealing arrangement shown in FIG. 2a. The assembly of the chassis 3 and the housing 4 has started, and the sealing area 5a is partly compressed. The second portion 7 is in contact with the counterpart surface 11, and it has been compressed towards the first portion 6, and may form a tubular shape, where the free end 8 of the second portion 7 may be in contact with an upper lip 22 of the sealing area 5a. Air may be enclosed in the tubular shape formed by the first and second portions 6, 7 of the sealing area 5a, which may make the sealing area 5a readily compressible, while the second portion 7 and the transition 20 are elastic, and are ready to regain their original shape when the pressure from the counterpart surface 11 is decreased. The partly compressed sealing area 5a may also start to exert a pressure radially on the inclined surface 10 in contact with the transition 20, which extends radially outwards when the sealing area 5a is compressed.

[0057] In FIG. 2c, the sealing area 5a is fully compressed. The chassis 3 and the housing 4 have reached their final mounted positions, and the sealing area 5a is compressed between the sealing seat 9 and the counterpart surface 11. In this state the transition 20 seals against a major part of the inclined, frustoconical surface 10. Also, there is a sealing abutment of the second portion 7 of the sealing area 5a against the counterpart surface 11.

[0058] In order to reach this compressed, sealing state, the tubular shape shown in FIG. 2b has been compressed, which has required a smaller compression force, than the compression of a solid sealing ring, e. g. an O-ring, would have required. The limited force needed will result in a limited counter force on the sealing seat 9 and the counterpart surface 11. The components, i. e. the chassis 3 and the housing 4, are manufactured from plastics. For this reason, the superior sealing effect obtained with a limited force is advantageous. The risks of deformations and creeping of the comprised components are limited or eliminated.

[0059] The circumferential bead 13 next to the counterpart surface 11 clamps the sealing member 2 against the bead 12 on the sealing seat 9. There may be a certain sealing effect in the abutment of the beads 12, 13 against the sealing member 2, but a non-negligible effect is that of fixing the sealing member 2 in its position.

[0060] The labyrinth seal formed with the respective beads 12, 16 and recesses 14, 15 (see FIG. 2a) of the sealing seat 9 and the sealing member 2, and described above in connection with FIG. 2a, may work as a complement to the sealing effect of the first 6 and second 7 portions of the sealing area 5a.

[0061] The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.

[0062] For example, although a robotic lawn mower 1 has been disclosed as an example, it needs to be emphasized that the disclosed sealing member may be applied in many other work tools, i.e. not only lawn mowers and not only work tools that are robotic. The sealing member 2 may be of many different general configurations, while the disclosed configuration of the sealing area 5a in at least one end thereof is one and the same.

[0063] In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality.