Suction head for a vacuum cleaner and method of operation

Abstract

This invention relates to a suction head (10) for a vacuum cleaner and method of operation. The suction head (10) has a bottom surface (26) and one or more floor-engaging parts (36) adjacent to the bottom surface (26), an opening (24) in the bottom surface (26) and a rotatable brush (30) located at the opening (24). The suction head (10) has a front end (16) and a rear end (18), the front end (16) having a recess (22) in communication with the opening (24). A movable strip (42) is located in the recess (22), the movable strip (42) being movable between a first position and a second position, the bottom edge of the movable strip 4(2) being closer to the plane of the floor-engaging parts (36) in its first position than in its second position. At least one first element (54) is connected to the movable strip (42) and is able to project to the plane of the floor-engaging parts (36). At least one second element (56) is also connected to the movable strip (42), the second element(s) (56) being configured differently to the first element(s) (54), the second element(s) (56) being able to project to the plane of the floor-engaging parts (36) and being configured to move the movable strip (42) to a third position in use. The bottom edge of the movable strip (42) is closer to the plane of the floor-engaging parts (36) in its second position than in its third position. According to the method of operation, the movable strip (42) moves to its first position during backwards movement of the suction head (10) and to its third position during forwards movement of the suction head (10), the movable strip (42) moving to its third position in two stages.

Claims

1. A suction head for a vacuum cleaner, the suction head having a bottom surface and one or more floor-engaging parts adjacent to the bottom surface, an opening in the bottom surface and a rotatable brush located at the opening, the suction head having a front end and a rear end, the front end having a recess in communication with the opening, a movable strip located in the recess, the movable strip being movable between a first position and a second position, the bottom edge of the movable strip being closer to the plane of the floor-engaging parts in its first position than in its second position, at least one first element connected to the movable strip, the first element(s) being able to project to the plane of the floor-engaging parts and being configured to move the movable strip from the first position to the second position in use, at least one second element also connected to the movable strip, the second element(s) being configured differently to the first element(s), the second element(s) being able to project to the plane of the floor-engaging parts and being configured to move the movable strip to a third position in use, the bottom edge of the movable strip being closer to the plane of the floor-engaging parts in its second position than in its third position.

2. The suction head according to claim 1 in which the first and second elements project below the bottom edge of the movable strip in its first position.

3. The suction head according to claim 2 in which the first and second elements project below the bottom edge of the movable strip in its first position by the same distance.

4. The suction head according to claim 1 in which the first and second elements project below the bottom edge of the movable strip in its first position by the same distance.

5. The suction head according to claim 1 in which the first element is oriented at a first angle relative to the movable strip, and the second element is oriented at a second angle relative to the movable strip, the first angle being less than the second angle.

6. The suction head according to claim 5 in which the first angle is less than 10, and the second angle is between around 20 and around 45.

7. The suction head according to claim 1 in which the first element is spaced from the plane of the floor-engaging parts in the third position.

8. The suction head according to claim 1 in which the bottom edge of the movable strip in its third position is spaced from the plane of the floor-engaging parts by around 10 mm.

9. The suction head according to claim 1 in which the first and second elements are configured to move the movable strip to its third position when the suction head is moving forwards, and to move the movable strip to its first position when the suction head is moving backwards.

10. The suction head according to claim 1 in which a unitary component comprising a fixed strip and the movable strip is located in the recess.

11. The suction head according to claim 10 in which the fixed strip and the movable strip are interconnected by a line of reduced material thickness.

12. The suction head according to claim 1 having a flexible strip behind the opening and further strips to the sides of the opening.

13. The suction head according to claim 1 having a resilient member projecting at the front end, a part of the resilient member being located above the recess, further parts of the resilient member being located at opposed sides of the recess.

14. The suction head according to claim 13 in which the resilient member is continuous.

15. The suction head according to claim 13 in which the resilient member lies immediately adjacent to the top and each of the sides of the recess.

16. The suction head according to claim 13 in which the front end has a planar surface, the resilient member being mounted to the planar surface.

17. The suction head according to claim 16 in which the resilient member terminates at a distance from the plane of the floor-engaging parts.

18. The suction head according to claim 17 in which the front end has a chamfered surface joined to the planar surface, the resilient member terminating at the junction of the planar and chamfered surfaces.

19. A method of operation of a vacuum cleaner having a suction head according to claim 1, the suction head being moved across a floor, the movable strip adopting its first position during backwards movement of the suction head and its third position during forwards movement of the suction head, the third position being reached in two stages, the first stage comprising the first element(s) engaging the floor surface and moving the movable strip towards its second position and also moving the second elements in a direction towards the floor, the second stage comprising the second element(s) engaging the floor and moving the movable strip to its third position.

20. The method of claim 19 in which there is an overlap between the first and second stages when the first element(s) and the second element(s) act together in moving the movable strip.

21. The method of claim 19 in which the second element(s) engage the floor when the movable strip is in its first position and are moved into greater engagement with the floor surface during the first stage.

22. The method of claim 19 in which the first element(s) move away from the floor during the second stage.

Description

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) The invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a perspective view of a suction head according to the first and second aspects of the present invention;

(3) FIG. 2 is a front view of the suction head of FIG. 1;

(4) FIG. 3 is an underside view of part of the suction head of FIG. 1;

(5) FIG. 4 is a perspective view of the movable strip and first and second elements according to the second aspect of the invention; and

(6) FIG. 5 is an enlarged side view of part of the suction head of FIG. 1.

DETAILED DESCRIPTION

(7) The suction head 10 is part of a battery-powered vacuum cleaner. As such, the suction head has a battery, a motor, an impeller and a dirt-collection chamber, none of which can be seen in FIG. 1, but all of which will be readily understood by a person skilled in this art.

(8) The suction head 10 has an on-off switch 12 and therefore carries all of the operating componentry of the vacuum cleaner. The handle 14 is used only to manoeuvre the suction head 10 across a floor or other surface being cleaned.

(9) The present invention, according to both aspects, does not depend upon the other components of the suction head, and could if desired by used on the suction head of a mains-powered vacuum cleaner of the cylinder or upright type. The significant benefits of the present invention in terms of cleaning efficiency are most appropriate for a battery-powered vacuum cleaner, however, such as that of FIG. 1.

(10) The suction head 10 has a front end 16 and a rear end 18. It will be understood that the suction head 10 is most usually moved across the surface being cleaned (by way of the handle 14) in a reciprocating motion, towards and away from the user, and alternately towards and away from the bottom right-hand corner of the page as viewed in FIG. 1. For the avoidance of doubt, forwards movement is herein defined as towards the bottom right-hand corner of the page in FIG. 1 (with the front end 16 leading), and backwards movement is defined as away from that corner of the page (with the rear end 18 leading).

(11) The front end 16 comprises a substantially flat and vertical surface 20, ideally of a substantially rigid plastics material. The surface 20 is connected to the sides of the suction head by rounded corners, in known fashion. The surface 20 is shaped to define a recess 22 which communicates with the opening 24 (FIG. 3) in the bottom surface 26 of the suction head 10. A rotatable brush 30 is located in the opening 24, and the projecting bristles 32 extend through the opening 24 to engage the surface being cleaned, in known fashion.

(12) Also in known fashion, the bottom surface 26 of the suction head 10 is held above the surface being cleaned 34 (FIG. 5) by wheels 36 at its rear end and further wheels, rollers or slides (not shown) at its front end. The wheels 36 and the further wheels, rollers or slides are the floor-engaging parts of the suction head and together define a plane of the floor-engaging parts. In use upon a hard surface such as that shown in FIG. 5, the plane of the floor-engaging parts corresponds to the floor (i.e. the surface being cleaned) 34.

(13) A gap G is therefore created between the bottom surface 26 of the suction head 10 and the floor surface 34. In use, air flows (substantially horizontally) from outside the suction head 10 through the gap G and into the opening 24. It will be understood that the floor 34 may have a covering such as carpet, in which case the gap G will be reduced by the distance by which the wheels (etc.) press into that covering.

(14) The recess 22 cannot be seen in the figures because it is occupied, partly by a fixed strip 40 and partly by a movable strip 42, the movable strip being shown in its first (lowered) position. As explained below, however, when the movable strip 42 is moved to its third (raised) position relatively large pieces of dirt and debris can pass through the recess 22 where they can be engaged by the rotatable brush 30. The rotatable brush, or the airflow into the suction head, or both, act to lift those pieces into the suction head 10 and carry them into the dirt-collection chamber for subsequent disposal.

(15) A continuous resilient member 44 is located on the front end 16 and projects slightly from the front end (in this embodiment by around 3 mm). The resilient member 44 is mounted to the surface 20 and in this embodiment lies close to the recess 22.

(16) The resilient member 44 has a (substantially horizontal) part which runs across the surface 20 immediately above the recess 22, in a similar fashion to a conventional bumper used for impact protection. Importantly, however, the resilient member 44 differs in having a downwardly-extending part 46 to each side of the recess 22. The downwardly-extending parts 46 continue to the bottom edge of the surface 20 and therefore terminate close to the bottom of the suction head 10 and close to the floor 34.

(17) In this embodiment the distance D (FIG. 5) between the bottom edge of the parts 46 of the resilient member 44 and the plane of the floor-engaging parts is 20 mm. Whilst it would be possible to continue the resilient member closer to the bottom of the suction head 10 (most appropriately by extending the flat surface 20 downwardly) that is not necessary. In particular, it is desirable to have a chamfered bottom edge of the front end 16 so that the suction head 10 can ride up over the edges of carpets, threshold strips and the like. Also, encouraging airflow through the recess 22 below the bottom edges of the parts 42 is advantageous as that airflow is very close to the surface being cleaned.

(18) The particular benefit of the first aspect of the invention can be appreciated most clearly from FIG. 1. When the front end 16 of the suction head 10 is moved into engagement with a wall, skirting board or stair riser for example, the surface 20 will lie parallel to the wall across its full area. The whole length of the resilient member 44, including importantly the parts 46, will also engage the wall, and can form an effective seal with the wall. The entire airflow into the recess 22 (which comprises a large proportion of the airflow into the opening 24) must therefore pass around the bottom ends of the parts 46, very close to the bottom of the wall. It will be recognised that most suction heads cannot be manipulated so that the rotatable brush engages the bottom edge of the wall, and as such dirt and debris collect at the bottom edge of the wall. Encouraging a rapid flow of air adjacent to the bottom edge of the wall acts to dislodge much or all of the dirt and debris located there, and once dislodged that dirt and debris is much more likely to pass through the recess 22 and be collected by the suction head 10.

(19) Whilst the resilient member 44 is designed primarily to provide an effective seal against a vertical wall, skirting board, stair riser and the like, in the present embodiment it functions also as impact protection. The resilient member 44 therefore avoids the requirement for a separate bumper at the front end 16.

(20) The drawings also show the movable strip 42 according to the second aspect of the invention. As seen in FIG. 4, the movable strip 42 and the fixed strip 40 are formed as a unitary structure carrying clips 48 by which it may be removably secured to the remainder of the suction head 10. This removable mounting allows the component 40, 42 to be replaced when worn.

(21) The component 40, 42 has a line 50 of reduced thickness and about which the movable strip 42 pivots relative to the fixed strip 40. The movable strip 42 has a projecting stop 52 which acts to limit the forwards pivoting movement of the movable strip when the vacuum cleaner is moving backwards (FIG. 5 showing the limit of the forwards (clockwise in this view) pivoting movement).

(22) The component 40, 42 is located in the recess 22 and when the movable strip 42 is in the first position as drawn the fixed strip 40 and the movable strip 42 together substantially fill the recess 22. As will be understood from FIG. 1, when the movable strip 42 is in this lowered position, airflow through the recess 22 is largely prevented, and air enters the opening from the front end 16 by way of the small gap g (FIG. 5) between the bottom of the movable strip 42 and the floor 34.

(23) It can be arranged that a movable strip according to GB patent 2 389 306 is located behind the opening 24, and further strips (such as for example lint strips) are located to the sides of the opening 24, so that the area through which air must flow into the opening 24 is very restricted and the speed of that airflow is high.

(24) The movable strip 42 carries two first elements (or tabs) 54 and two second elements (or tabs) 56. The first and second elements 54, 56 operate together, sequentially, to control the position of the movable strip, as explained below.

(25) It will be seen from FIG. 5 in particular that both of the first and second elements 54, 56 project below the bottom edge of the movable strip 42. The additional projecting distance may be relatively small, for example 0.5 mm, but this is sufficient to ensure that the movable strip 42 does not engage the floor 34 in its lowered or raised positions and is therefore protected from undue wear, whilst the first and second elements 54, 56 can engage the floor 34.

(26) In this embodiment both of the first and second elements 54, 56 project below the bottom edge of the movable strip 42 by the same distance but that is not necessarily the case and in other embodiments the first element can project further than the second element.

(27) The movable strip 42 is in its first (lowered) position in FIG. 5, which is the position adopted when the suction head in moving backwards (to the right as drawn in FIG. 5), i.e. with the front end 16 trailing. In that position, the gap g between the bottom edge of the movable strip 42 and the floor 34 is minimised, ensuring that the maximum quantity of dirt or debris is dragged across the surface by the movable element 42 and maintained within the region of the opening 24. Also, the speed of the air flowing through the gap g from the front end 16 is maximised, and importantly the speed of the airflow through any crevice in the floor 34 adjacent to the opening 24 is also maximised.

(28) Whilst it could be arranged that the gap g is zero when the movable strip 42 is in its first position (so that the bottom edges of the first elements 54, second elements 56 and movable strip 42 all lie in the same plane engaging the floor 34) that is not preferred as it would result in wear of the movable strip 42. Instead, a small gap g is preferred as shown in FIG. 5

(29) If the direction of movement of the suction head 10 is reversed so that the front end 16 becomes the leading end, the first and second elements 54, 56 act sequentially to lift the movable strip 42. Alternatively stated, the differing configurations of the first and second elements 54, 56 provide a two-stage movement for the movable strip 42. Specifically, because in this embodiment the first and second elements 54, 56 both engage the surface 34 they both urge the movable strip to pivot anti-clockwise as viewed in FIG. 5.

(30) The whole of the movable strip 42, including all that can be seen in FIG. 5, can pivot anti-clockwise about the fold line 50, relative to the fixed strip 40, in this embodiment by around 40. It is arranged that the first and second elements 54, 56 are of the same material, and are substantially the same thickness. The shorter length of the first elements 54 makes them more rigid, however, and it is this greater rigidity which causes the first element 54 to assume greater control over the initial pivoting movement of the movable strip 42.

(31) As the movable strip 42 pivots anti-clockwise as drawn in FIG. 5, it will be understood that the bottom edge of the second element 56 is driven into greater engagement with the floor 34. In this embodiment the floor 34 is a hard surface, so that the second element 56 is caused to deform by its increased engagement with the floor. In any event, the pivoting of the movable strip 42 continues (even after the bottom edge of the first element 54 is lifted away from the floor 34) as the second element is forced to rotate anti-clockwise past (or alternatively stated to flip underneath) the fixed strip 40. Stops can be provided to limit the pivoting movement of the movable strip 42, but preferably the movement can continue until the bottom edge of the second element 56 is about to leave the floor 34.

(32) The limit of pivoting movement of the movable strip 42 defines the third or raised position of the movable strip 42. In that position there is a relatively large gap (not shown) between the bottom edge of the movable element 42 and the floor 34 through which relatively large pieces of dirt and debris can pass. In some embodiments the gap may be as large as the gap G, for example around 5 mm when fully open. It will be understood that when the movable element 42 is in its third position the speed at which air flows through the recess 22 is reduced commensurate with the increased area through which the air can flow. The suction head 10 is therefore suited to collecting larger pieces of debris on its forwards strokes, and to collecting dust and smaller pieces of dirt (particularly from within crevices in the surface being cleaned) on its backwards strokes.

(33) When the suction head 10 is again moved backwards, the engagement of the bottom edge of the second element 56 with the floor 34 causes the movable element 42 to pivot clockwise. At some point the bottom edge of the first element 54 also engages the surface 34 and further ensures the pivoting of the movable strip 42 back to its first position.

(34) It will be understood that the first element 54 alone could not achieve the same degree of angular movement of the movable strip 42, nor therefore the same increase in the gap g below the bottom edge of the movable strip 42 and the floor 34. Importantly, the second element 56 acting alone cannot reliably achieve that movement either and it has been found that without the first element 54 the second element 56 often simply moves across the surface 34 and does not flip underneath the fixed strip 40. Thus, tests conducted by the inventor have shown that the sequential (two-stage) operation of the first and second elements 54, 56 is necessary to achieve reliable movement of the movable strip between its first and third positions, without requiring an increased engagement with the floor 34 and thereby unacceptable wear.

(35) In one embodiment, the first elements 54 alone can pivot the movable strip 42 to a second (intermediate) position in which the bottom edge is raised by around 4 mm. The first and second elements 54, 56 acting sequentially can, however, raise the bottom edge by around 10 mm. Attempts to provide a similar 10 mm of lift with a single element acting alone result in unreliable operation and/or unacceptable wear.

(36) It will be understood that the maximum distance by which the movable strip 42 can be lifted is determined primarily by the distance L (FIG. 5), i.e. the distance by which the second element 56 protrudes from the movable strip 42.

(37) In the embodiment shown the movable element 42 is substantially vertical in its first position. The first element 54 is aligned substantially vertical also, so that the angle between these components is 0. The angle between the second element 56 and the movable strip 42 is around 30 in this embodiment.

(38) It will be observed from FIG. 5 that in the first position the first and second elements 54, 56 project forwardly beyond the front end 16, and in particular beyond the resilient member 44. Whilst it might be considered that the first and second elements 54, 56 would impair the ability of the resilient member 44 to seal to a vertical wall or the like that is not the case as when the suction head 10 is moved forwardly into engagement with the wall the first and second elements 54, 56 are not in the position of FIG. 5, but are pivoted anti-clockwise from that position, and do not project as far as the resilient member 44.

(39) It will be understood that the material of the movable strip 42, and in particular the first and second elements 54, 56 should be flexible and resistant to wear. A suitable material for these components is polyurethane. One suitable material for the resilient member 44 is thermoplastic elastomer (TPE), but other rubberised materials used for the bumpers of vacuum cleaners could be used.