SUCTION TOOL

Abstract

A suction tool for a vacuum cleaner includes an outlet for connection to a vacuum cleaner; a main inlet in fluid communication with the outlet via a main suction passage; and an auxiliary inlet in fluid communication with the outlet via an auxiliary suction passage. The auxiliary suction passage includes a flow limiting device which is movable between first and second configurations, the flow limiting device obstructing air flow through the auxiliary suction passage to a greater extent when in the second configuration than when in the first configuration. The flow limiting device is configured to move to the second position in response to the pressure within the main suction passage dropping beneath a predetermined threshold.

Description

BACKGROUND

Suction tools for vacuum cleaners take a number of different forms, but all have an inlet for entry of dirty air into the suction tool, an outlet through which said air can exit the tool and enter a vacuum cleaner (for instance via a wand or hose), and a suction passage providing fluid communication therebetween. In some tools the suction passage includes a suction chamber within which a rotating brush bar is provided, the brush bar extending slightly out of the inlet for agitating a surface being cleaned.

Some suction tools include an auxiliary inlet in communication with the outlet via an auxiliary suction passage, through which a second stream can flow through the tool. This can perform many different functions. For instance, the auxiliary suction passage may form a bleed passage through which air can enter the cleaner head, preventing blockage of the main inlet from causing the pressure inside the tool to become too low (which could cause the tool to ‘limpet’ down onto a surface being cleaned, or place undue strain on the vacuum motor of the vacuum cleaner to which the tool is attached). As another example, air flow through the auxiliary suction passage may be used to drive a turbine to rotate a brush bar, or to cool a component such as an electric motor for driving a brush bar.

It is known to include a valve in the auxiliary flow passage which is closed when pressure inside the tool is relatively high and opens when pressure inside the tool is relatively low so that flow through the auxiliary suction passage only takes place in some circumstances (so that, for example, flow through a bleed only takes place when pressure inside the cleaner head is low enough for limpeting to be more likely). However, the opening of the auxiliary flow passage when pressure drops low enough can cause a drop in pickup performance of the machine. Further, when the drop in pressure inside the tool is due to a clog in the main suction passage, the opening of the auxiliary suction passage can reduce the possibility of the clog being cleared by suction power alone.

SUMMARY

According to a first aspect of the present invention there is provided a suction tool for a vacuum cleaner, the suction tool comprising:

• • an outlet for connection to a vacuum cleaner;
  • a main inlet in fluid communication with the outlet via a main suction passage; and
  • an auxiliary inlet in fluid communication with the outlet via an auxiliary suction passage, wherein:
  • the auxiliary suction passage includes a flow limiting device which is movable between first and second configurations, the flow limiting device obstructing air flow through the auxiliary suction passage to a greater extent when in the second configuration than when in the first configuration; and
  • the flow limiting device is configured to move to the second position in response to the pressure within the main suction passage dropping beneath a predetermined threshold.

The pressure in the main suction passage may drop below the threshold when the suction tool is being pushed firmly against a surface in the hope of performing particularly thorough cleaning. In such circumstances the flow limiting device moving to the more restrictive position can maximise the pressure difference between the inside and outside of the suction tool, by reducing or eliminating airflow into the tool through the auxiliary suction passage, thereby increasing the speed of air into the main inlet and thus boosting pickup performance.

Instead or as well, the pressure in the main suction passage may drop below the threshold when the main suction passage is clogged, for instance after sucking up a large piece of debris. In such circumstances the flow limiting device moving to the more restrictive position can maximise the pressure difference between the inside and outside of the suction tool, improving the chances that the clog will be cleared and pass through the tool without requiring intervention by the user.

The suction tool may comprise a rotatable brush bar and the auxiliary suction passage is associated with a drive mechanism of the brush bar.

For example, the auxiliary suction passage may pass over or through one of the components of the drive mechanism. This may allow airflow through the auxiliary suction passage to drive the brush bar (for instance via a turbine).

As one alternative, the auxiliary suction passage may be a bleed passage arranged to provide air flow into the suction tool for the sake of preventing ‘limpetting’.

The drive mechanism may comprise an electric motor, and the auxiliary suction path may run through or near the electric motor so that air running through the auxiliary suction path can cool the electric motor.

Where brush bars are driven by a motor, the motor is often more susceptible to overheating than other drive components. The auxiliary suction path running through or near the motor can therefore be particularly effective at preventing overheating of the drive mechanism as a while.

Instead or as well, the auxiliary suction path may run through or near a different component of the drive mechanisms such as a gearbox, or a different component altogether such as a bearing which rotatably supports the brush bar.

The brush bar may be hollow, and the auxiliary suction passage may extend into the brush bar.

The auxiliary suction path extending into the brush bar can allow it to reach components of the drive mechanism which are housed inside the brush bar, for instance for the purposes of cooling.

As an alternative, the auxiliary suction tool may remain external to the brush bar.

The flow limiting device may be configured to substantially close the auxiliary flow passage when in the second configuration.

The effect of the flow limiting device becoming more restrictive when the pressure drops low enough, as described above, can be magnified if the flow limiting device substantially closes the auxiliary flow passage.

Alternatively, the flow limiting device may be configured to allow air flow through the auxiliary flow passage when in the second configuration.

Although this may reduce the effect of the flow limiting device in comparison to an arrangement where it substantially closes the auxiliary flow passage when in the second configuration, in some contexts this reduction may be an acceptable sacrifice in order to preserve the functionality of the auxiliary suction passage. For example, where the auxiliary suction passage cools a brush bar motor, a slight (but still minimised) compromise in pickup may be worthwhile in order to ensure that the brush bar motor is still cooled sufficiently for it to withstand relatively long periods of intense cleaning.

Optionally:

• • the flow limiting device is movable from the first configuration to the second configuration via an intermediate configuration;
  • when in the intermediate configuration the flow limiting device obstructs air flow through the auxiliary suction passage to a greater extent than when in the first configuration but a lesser extent than when in the second configuration; and
  • the flow limiting device is configured to move from the first position to the intermediate position in response to the pressure within the main suction passage dropping beneath a higher predetermined threshold, and to move from the intermediate position to the second position in response to the pressure within the main suction passage dropping beneath a lower predetermined threshold.

In other words, the flow limiting device may gradually increase in its obstructiveness as pressure in the main suction passage gradually falls. This can allow the flow through the auxiliary suction passage to more closely matched to the requirements of the cleaner head. For example when the pressure in the main suction passage starts to drop it may suggest that a user is pushing the tool harder against a surface in the hope of cleaning more thoroughly and the proportion of flow going through the main inlet rather than auxiliary inlet can be increased, then if the pressure in the main suction passage drops yet lower the user may be pushing the tool particularly hard against the surface and the tool can react by still further increasing the proportion of air flow which runs through the main suction inlet. This may happen continually, or in a series of steps.

As an alternative, the flow limiting device may have two discrete positions and switch between the two at a specific single threshold value.

The primary suction passage and auxiliary suction passage may intersect and form a common suction passage which extends to the outlet.

This can reduce the complexity of ducting within the suction tool. Also, by selecting the position at which the primary and auxiliary suction paths meet, the flow of air through the two passageways can be altered.

For example, the primary suction passage may include a suction chamber, and the auxiliary suction passage may intersect the primary suction passage at the suction chamber.

The pressure within the suction chamber can often be higher than the pressure elsewhere in the primary suction passage, due to its relatively large cross sectional area. The auxiliary suction opening exiting into this area therefore means that a relatively small proportion of air flow through the tool flows through the auxiliary suction passage.

As an alternative, the primary suction passage may include a suction chamber, and the auxiliary suction passage may intersect the primary suction passage downstream of the suction chamber.

The part of the primary flow path upstream of the suction chamber is generally at a lower pressure than the suction chamber, due to its relatively narrow cross sectional area. The auxiliary suction opening exiting into this area therefore means that a relatively large proportion of air flow through the tool flows through the auxiliary suction passage.

The flow limiting device may be biased to the first position, and be movable to the second position, against said bias, under action of air flowing through the auxiliary suction passage.

For example, the flow limiting device may comprise a deformable element which narrows in the upstream direction and defines a central aperture, the deformable element being configured to be deformed inwardly by air flowing through the auxiliary suction path, thereby reducing the cross sectional area of the central aperture.

This may allow the flow limiting device and thus the tool as a whole to be advantageously simple and therefore and reliable or easy to assemble, advantageously compact and/or advantageously lightweight.

As another example, the flow limiting device may comprise a valve element movable relative to a valve seat, respective surfaces of the valve element and valve seat being positioned closer together when the flow limiting device is in the second position than when in the first position.

This may allow the behaviour of the flow limiting device to be defined with advantageous ease and/or predictability with suitable selection of component sizes and/or the strength of the component responsible for biasing, in comparison to an arrangement which relies on more complex interactions (for example the behaviour of an elastically deformable element, which may be subject to variations in shape and/or hardness, and/or subject to harmonic influences).

The flow limiting device may comprise a deformable passageway running through a neutral pressure zone, the deformable passageway being configured to be crushed under ambient pressure in the neutral pressure zone so as to move the deformable passageway to the second position.

This may allow the flow limiting device to have a particularly simple mode of operation and/or to be less vulnerable to clogging.

According to a second aspect of the invention, there is provided a suction tool for a vacuum cleaner, the suction tool comprising:

• • an outlet for connection to a vacuum cleaner;
  • a main inlet in fluid communication with the outlet via a main suction passage; and
  • an auxiliary inlet in fluid communication with the outlet via an auxiliary suction passage, wherein:
  • the auxiliary suction passage includes a flow limiting device which is movable between first and second configurations, the flow limiting device obstructing air flow through the auxiliary suction passage to a greater extent when in the second configuration than when in the first configuration; and
  • the flow limiting device is configured to move to the second position in response to the flow rate of air through the auxiliary suction passage exceeding a predetermined threshold.

According to a third aspect of the invention there is provided a vacuum cleaner comprising a suction tool as aforementioned.

Features described above in relation to the first aspect of the invention are equally applicable to each of the second and third aspects of the invention, and vice versa.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be described with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a stick vacuum cleaner according to a first embodiment of the invention;

FIG. 2 is a bottom perspective view of the cleaner head of the vacuum cleaner of FIG. 1;

FIG. 3 is a cross sectional view through a cleaner head of the vacuum cleaner of FIG. 1;

FIG. 4 is a rear perspective view of the cleaner head of FIGS. 1 and 2, with a top cover removed;

FIG. 5 is a perspective view of a flow limiting device of the first embodiment;

FIG. 6 is a cross-sectional view of a flow limiting device of a second embodiment of the invention; and

FIG. 7 is a rear perspective view of a cleaner head of a third embodiment of the invention, with a top cover removed.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

Throughout the description and drawings, corresponding reference numerals denote corresponding features.

FIG. 1 shows a vacuum cleaner 2 according to a first embodiment of the invention. The vacuum cleaner 2 of this embodiment is a stick vacuum cleaner, which comprises a handheld vacuum cleaner 4 attachable to a suction tool in the form of a cleaner head 6 via an elongate rigid wand 8. The handheld vacuum cleaner 4 comprises a vacuum motor (not shown) which is supplied by power from a battery pack 10, and a dirt separator 12 with an inlet 14 at its front. The handheld vacuum cleaner 4 is not material to the present invention, therefore will not be described in detail.

The cleaner head 6 is shown in more detail in FIGS. 2 to 4. It has an outlet 20 which is connected to the handheld vacuum cleaner 4 by the wand 8 via a wheeled articulated neck 21, and a main inlet in the form of an opening 22 in a ground-contacting sole plate 24. A main suction passage 26 extends from the main inlet 22 to the outlet 20 and includes a suction chamber 28 within which a hollow rotatable brush bar 30 is provided. A top cover 32 extends over the top of the cleaner head.

As well as a main inlet 22 and main suction passage 26, the cleaner head 6 has an auxiliary inlet in the form of a grille 40 and an auxiliary suction passage 42. In this particular case the auxiliary inlet 40 is provided in the right hand side wall of the cleaner head 6, and the auxiliary suction passage 42 is associated with a drive mechanism 44 of the brush bar 30. More particularly, the auxiliary suction passage 42 enters the right hand side of the brush bar 30, flows through a cantilevered motor support 45 of the drive mechanism and then through an electric motor 46 of the drive mechanism 44 which drives the brush bar 30, through a duct 47 in the brush bar 30 and into an end chamber 49. The auxiliary suction passage 42 then runs upward and rearward within the end chamber, passes through a straight pipe 50 in a space 51 beneath the top cover 32, and intersects the main suction passage 26 downstream of the suction chamber 28 at a hole 53 shortly before the outlet 20. Accordingly, the final part 52 of the fluid path through the cleaner head 6, which extends to the outlet 20 (and through the neck 21) from the point where the main suction passage 26 and auxiliary suction passage 42 intersect, is a common suction passage.

The auxiliary suction passage 42 includes a flow limiting device, which in this embodiment is positioned within the straight pipe 50. FIG. 5 shows the flow limiting device 60 in isolation. In this embodiment, the flow limiting device takes the form of a deformable element 62, in this case made of elastomeric rubber. It has an annular boss 63 which seals against the inside of the straight pipe 50, and a projection 65 which narrows in the upstream direction and defines a central aperture 64.

The flow limiting device 60 is movable between a first configuration, as shown in FIG. 5, to a second configuration. In the second configuration, the narrower end of the deformable element 62 is crushed inward and the aperture 64 is squashed closed. In this second configuration with the aperture 64 closed, no or virtually no air can flow through the auxiliary suction passage 42. Thus, in the second configuration the flow limiting device is more obstructive to air flow through the auxiliary suction passage 42 than when in the first configuration. Due to the resilient nature of the deformable element 62, it is biased to the first configuration and must be moved to the second configuration against that bias by an external force. When that external force is removed, the deformable element 62 (and thus the flow limiting device 60 as a whole) springs back to the first configuration.

The flow limiting device 60 is configured to move from the first configuration to the second configuration in response to the air pressure within the main suction passage 26 dropping below a threshold. More particularly, when the pressure in the main suction passage 26 is above the threshold then relatively little air is drawn through the auxiliary suction passage 42. As the pressure in the main suction passage 26 begins to fall, this draws more air through the auxiliary suction passage. When the pressure in the main suction passage 26 drops below the threshold, sufficient air is drawn through the auxiliary suction passage 42 for the air to deform the deformable element 62 against the bias provided by its resilient nature. The aperture 64 then snaps shut, the flow limiting device 60 is in the second configuration, and no more air can pass through the auxiliary suction passage 42.

With the flow limiting device 60 in the second configuration, the pressure difference across the deformable element 62 holds the aperture 64 closed. When the pressure within the main suction passage raises sufficiently, however, the resilient bias of the deformable element 62 causes the aperture 64 to open again and the flow limiting device returns to the first configuration.

A flow limiting device 60 according to a second embodiment of the invention, which may for example be used in place of that of the first embodiment within the straight pipe 50 of the cleaner head 6, is shown in FIG. 6. The flow limiting device 60 of this embodiment has a valve member 70 which is movable along a spindle 72 relative to a valve seat 74.

Like that of the first embodiment, the flow limiting device 60 of this embodiment has a first configuration and a second configuration. FIG. 6 shows the flow limiting device 60 in the first configuration. With the flow limiting device 60 in the second configuration, the valve member 70 abuts the valve seat 74. With the flow limiting device 60 in the first configuration air can flow through the relatively wide gap between the valve member 70 and the valve seat 74. With the valve member 70 abutting the valve seat 74, however, this gap is completely closed. Accordingly, like the flow limiting device of the first embodiment, this flow limiting device 60 is more obstructive to flow through the auxiliary suction passage when in the second configuration than when in the first configuration.

The flow limiting device 60 of this embodiment, like that of the previous embodiment, is biased to the first configuration. In this case, the flow limiting device 60 includes a compression spring 76 positioned around the spindle 72 and held between the valve seat 74 and the valve member 70. In use, when the pressure in the main suction passage 26 is relatively high then air in the auxiliary suction passage 42 can simply flow past the valve member and then through the valve seat. When the pressure in the main suction passage 26 drops below, however, the air flows through the auxiliary suction passage 42 sufficiently quickly for the valve member to be forced towards the valve seat 74 (i.e. the flow limiting device 60 to be moved away from the first configuration and towards the second configuration).

The flow limiting device 60 of this embodiment does not move from the first configuration to the second configuration in a sudden and complete jump like that of the first embodiment, however. In this case, the flow limiting device 60 moves from the first configuration to the second configuration via an intermediate configuration. In the intermediate configuration the flow limiting device 60 is more restrictive to air flow through the auxiliary suction passage 42 than when in the first configuration, but less restrictive than when in the second configuration.

In this specific embodiment, the flow limiting device 60 moves through a continuum of configurations any one of which may be referred to as the intermediate configuration. When the pressure in the main suction passage 26 is above a higher threshold, the flow through the auxiliary suction passage 42 is going too slowly to move the valve member 70, as outlined above. Once the pressure in the main suction passage 26 drops below the higher threshold, the air in the auxiliary suction passage 42 moves quickly enough to move the valve member 70 towards the valve seat 74. This compresses the spring 76, however, and the spring acts to prevent the valve member 70 from moving any further. Continued reduction in pressure in the main suction passage 26 speeds up the air flow in the auxiliary suction passage 42, which moves the valve member 70 closer towards valve seat 74. This results in further compression of the spring 76, and thus increase in the force urging the valve member 70 away from the valve seat so that the valve member still does not reach the valve seat 74. Once the pressure in the main suction passage 26 drops still further, below a lower threshold, the speed of air through the auxiliary suction passage 26 is sufficient to force the valve member 70 against the valve seat 74. The flow limiting device 60 then reaches the second configuration.

Whereas the flow limiting device 60 of the first embodiment prevents air flow through the auxiliary suction passage 42, the same is not true of the flow limiting device 60 of this embodiment. The valve member 70 is provided with a set of through-holes 78 which allow some air to pass along the auxiliary suction passage even with the valve member 70 pressed against the valve seat 74. The auxiliary suction passage 42 of this embodiment, therefore, is never fully closed.

FIG. 7 shows a cleaner head 6 according to a third embodiment of the invention, which is a modification of the first embodiment therefore only the differences will be described here. In this embodiment, the flow limiting device 60 is formed by a part of the straight pipe 50 itself. In this embodiment the top cover (not shown) has holes though it which ensures that the space 51 through which the straight pipe 50 runs forms a neutral pressure zone (i.e. a zone at ambient pressure), and part of the straight pipe 50 is made of resilient elastomeric material and forms a flow limiting device 60 in the form of a deformable passageway. When the pressure in the main suction passage 26 is relatively high the pressure within the straight pipe 50 is also relatively high, the deformable passageway 60 has the usual shape of a pipe (i.e. it occupies the first configuration). As pressure within the main suction passage 26 falls, however, pressure within the straight pipe 50 also falls and the deformable passageway 60 begins to be crushed by ambient pressure. This, in turn, reduces the cross sectional area available for air flow inside the deformable passageway 60 and the passageway therefore becomes more obstructive. Further reductions in pressure lead to further crushing of the deformable passageway 60 until it becomes completely closed. An increase of pressure within the primary suction passage 26 has the opposite effect, allowing the deformable passageway to spring back towards its original shape and the cross sectional area within the deformable passageway to increase.

It will be appreciated that numerous modifications to the above described embodiments may be made without departing from the scope of invention as defined in the appended claims. For instance, the deformable element may be shaped so that it moves from the first configuration to the second configuration via one or more intermediate configurations. As another example, in a modification of the second embodiment the valve member may not be provided with through-holes so that it can fully close the auxiliary suction passage when in the second configuration.

Claims

1. A suction tool for a vacuum cleaner, the suction tool comprising: an outlet for connection to a vacuum cleaner;a main inlet in fluid communication with the outlet via a main suction passage; andan auxiliary inlet in fluid communication with the outlet via an auxiliary suction passage,wherein:the auxiliary suction passage includes a flow limiting device which is movable between first and second configurations, the flow limiting device obstructing air flow through the auxiliary suction passage to a greater extent when in the second configuration than when in the first configuration; and wherein:the flow limiting device is movable from the first configuration to the second configuration via an intermediate configuration;when in the intermediate configuration the flow limiting device obstructs air flow through the auxiliary suction passage to a greater extent than when in the first configuration but a lesser extent than when in the second configuration; andthe flow limiting device is configured to move from the first position to the intermediate position in response to the pressure within the main suction passage dropping beneath a higher predetermined threshold, and to move from the intermediate position to the second position in response to the pressure within the main suction passage dropping beneath a lower predetermined threshold.

2. The suction tool according to claim 1 wherein the suction tool comprises a rotatable brush bar and the auxiliary suction passage is associated with a drive mechanism of the brush bar.

3. The suction tool according to claim 2 wherein the drive mechanism comprises an electric motor, and the auxiliary suction path runs through or near the electric motor so that air running through the auxiliary suction path can cool the electric motor.

4. The suction tool according to claim 1 wherein the brush bar is hollow, and the auxiliary suction passage extends into the brush bar.

5. The suction tool according to claim 2 wherein the flow limiting device is configured to substantially close the auxiliary flow passage when in the second configuration.

6. The suction tool according to claim 1 wherein the flow limiting device is configured to allow air flow through the auxiliary flow passage when in the second configuration.

7. The suction tool according to claim 1 wherein the primary suction passage and auxiliary suction passages intersect and form a common suction passage which extends to the outlet.

8. The suction tool according to claim 7 wherein the primary suction passage includes a suction chamber, and the auxiliary suction passage intersects the primary suction passage at the suction chamber.

9. The suction tool according to claim 1 wherein the primary suction passage includes a suction chamber, and the auxiliary suction passage intersects the primary suction passage downstream of the suction chamber.

10. The suction tool according to claim 1 wherein the flow limiting device is biased to the first position, and is movable to the second position, against said bias, under action of air flowing through the auxiliary suction passage.

11. The suction tool according to claim 10 wherein the flow limiting device comprises a valve element movable relative to a valve seat, respective surfaces of the valve element and valve seat being positioned closer together when the flow limiting device is in the second position than when in the first position.

12. The vacuum cleaner according to claim 11 wherein the valve element is moveable along a spindle relative to the valve seat.

13. The vacuum cleaner according to claim 12 wherein the flow limiting device comprises a compression spring positioned around the spindle and held between the valve element and the valve seat.

14. The vacuum cleaner according to claim 11 wherein the valve element comprises a set of through-holes which allow air flow through the auxiliary flow passage when the flow limiting device is in the second configuration.

15. A vacuum cleaner comprising the suction tool according to claim 1.

16. A suction tool for a vacuum cleaner, the suction tool comprising: an outlet for connection to a vacuum cleaner;a main inlet in fluid communication with the outlet via a main suction passage;an auxiliary inlet in fluid communication with the outlet via an auxiliary suction passage;a rotatable brush bar; andan electric motor configured to drive the brush bar,wherein:the auxiliary suction passage includes a flow limiting device which is movable between first and second configurations, the flow limiting device obstructing air flow through the auxiliary suction passage to a greater extent when in the second configuration than when in the first configuration; andthe flow limiting device is configured to move to the second position in response to the pressure within the main suction passage dropping beneath a predetermined threshold.

17. The suction tool according to claim 16 wherein the auxiliary suction passage is associated with a drive mechanism of the brush bar.

18. The suction tool according to claim 17 wherein the auxiliary suction path runs through or near the electric motor so that air running through the auxiliary suction path can cool the electric motor.

19. The suction tool according to claim 16 wherein the brush bar is hollow, and the auxiliary suction passage extends into the brush bar.

20. The suction tool according to claim 16 wherein the flow limiting device is configured to substantially close the auxiliary flow passage when in the second configuration.