The present invention concerns a vacuum cleaner of the bagless type, particularly but not restrictively for domestic use, which is provided with an air filtration unit.

The vacuum cleaner according to the present invention can automatically remove foreign objects, dust and dirt which obstruct the air filtration unit.

A bagless vacuum cleaner which can automatically remove foreign objects that obstruct the filtration unit is known from document EP-A-1.629.761.

The known filtration unit comprises a fixed-type filter with pores and a plurality of rotary brushes around the filter with pores, to remove the objects that obstruct the external surface of the latter.

One disadvantage of this known solution is that it is complex and costly to make, since it is necessary to provide, as an additional component, a cleaning unit, that is, the brushes and the structure that supports them, to clean the filter.

Another known solution for cleaning the filter automatically provides a filter rotating in a commanded manner, which is made to rotate on itself by a motorization unit provided for this purpose, with cadenced timing. The rotation at intervals of the filter on itself determines a centrifugal thrust on the particles that obstruct the external surface of the filter, thus cleaning the filter.

One disadvantage of this second known solution is that it is necessary to have a motorization unit and an additional relative control unit to drive the rotation of the filter, which increases costs and the complexity of the whole.

Document US-A-2004/098827 shows a cyclonic apparatus to collect dust in a vacuum cleaner on which the preamble to the independent claim is based.

Purpose of the present invention is to achieve a vacuum cleaner which has a filtration unit with automatic cleaning capacity, which is economical and easy to make and which at the same time allows an effective cleaning of the filter.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

The present invention is set forth and characterized in the independent claim, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

In accordance with the above purpose, a bagless vacuum cleaner according to the present invention comprises a suction unit able to take in a first stream of air and dirt from the outside through a primary circuit, and a filtration unit able to filter the dirt taken in by the suction unit.

According to one feature of the present invention, the filtration unit comprises a first chamber, in fluidic connection with the primary circuit, which is able to be put in depression by the suction unit and inside which a first filter is mounted, able to rotate freely, or idle, on itself with respect to the first chamber when it is hit by the first stream taken in by the suction unit.

The free rotation of the first filter determines a centrifugal force on the particles of dirt that obstruct its external surface, allowing the automatic cleaning thereof.

The first filter is thus substantially driven by the same air arriving from suction, avoiding the constructional complexities of vacuum cleaner known in the state of the art, and in any case obtaining the automatic cleaning of the filter.

The filter is thus kept clean precisely by the stream of air taken in by the vacuum cleaner which makes it rotate, without needing cleaning accessories or auxiliary motorization devices.

In accordance with some forms of embodiment of the present invention, support means are provided, such as bearings, bronzes or other, which are able to rotatably support the first filter so as to allow the free rotation thereof with respect to the first chamber.

According to some embodiments of the present invention, the vacuum cleaner comprises a secondary circuit in which a third stream of clean air is able to flow, taken from the outside. The secondary circuit passes through one or more of the support means, so that the third stream can exert a cleaning action on the support means. In this way, the support means are always kept clean, preventing the accumulation of dirt and allowing an optimum free rotation of the first filter.

In some forms of embodiment of the present invention, the secondary circuit develops between an aperture toward the external environment and a second environment, advantageously the first chamber, able to be put under lower pressure, or depression, with respect to the external environment. The depression of the second environment determines the third stream.

In the secondary circuit a pressure equilibrium tends to be created between the negative pressure in the secondary circuit, advantageously given by the first chamber, and the positive pressure of the external environment. The tendency to pressure equilibrium in the secondary circuit generates the third stream which cleans the support means of the filter, substantially preventing the accumulation of dirt on the rotation support means.

According to one form of embodiment, the secondary circuit comprises a first passage way, which receives air from the aperture, able to direct the clean air at least onto a first of the support means, and a second passage way able to direct the clean air at least onto a second of the support means, keeping them clean during normal use.

Typically, the first filter has a substantially cylindrical external shape, and is able to rotate around its own central axis of symmetry. According to one feature of the invention, the primary circuit comprises a first pipe shaped so as to direct the first stream taken in from the outside toward the first filter, in a direction tangential to the external cylindrical surface of the filter.

According to a variant, the first filter has, on an external surface, a plurality of fins which, when hit by the stream arriving from the first pipe, are able to draw the first filter into rotation.

According to a variant of the invention, in an internal region, the first filter comprises filter means, advantageously of the porous type.

According to said variant, the external surface of the first filter has holes for the passage of the air to be filtered toward the filter means inside the first filter.

The present invention provides the passage, through the internal region, of a second stream of air with fine particles of dust not filtered by the filter means.

According to a variant of the present invention, under the first chamber there is a second chamber into which the coarse dirt filtered by the first filter falls.

Advantageously, between the first and the second chamber a conveyor element is provided, which promotes the passage of the air and dirt toward the bottom of the second chamber.

Advantageously, downstream of the first filter, a second filter is provided, able to filter at least partly, advantageously completely, the second stream of fine particles of dust not filtered by the first filter.

In accordance with other forms of embodiment, the primary circuit has an auxiliary air entrance in communication with the external environment and valve means in cooperation with said auxiliary entrance so as to selectively determine the opening or closing thereof, depending on whether the entrance of the first stream of air and dirt sucked in from the outside is free or occluded. In variant embodiments of the present invention, the valve means are associated with elastic means that normally keep the valve means closed, thus closing the auxiliary entrance. If the first main stream of air is obstructed, the increased depression inside the primary circuit causes the atmospheric pressure of the outside environment to overcome the force of the elastic means, causing the valve means to open and thus allowing the entrance of an auxiliary stream of air, which has the important advantage of keeping the filtration unit of the vacuum cleaner in rotation even in the event of an accidental obstruction of the main entrance, allowing to keep it clean by an action of centrifugation.

These and other characteristics of the present invention will become apparent from the following description of a preferential form of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

• fig. 1 is plane view from below of the vacuum cleaner according to the present invention;
• fig. 2 is a section from II to II of fig. 1;
• fig. 3 is a section from III to III of fig. 1;
• fig. 4 is an enlarged detail of fig. 3;
• fig. 5 is a section from V to V of fig. 1
• fig. 6 is a section from VI to VI of fig. 3;
• fig. 7 is a section of a variant embodiment of the vacuum cleaner in fig. 1;
• fig. 8 is an enlarged detail of fig. 7.

To facilitate comprehension, the same reference numbers have been used where possible to identify identical elements common to the drawings. It should be understood that elements and characteristics of one form of embodiment can be conveniently incorporated in other forms of embodiment without any further clarification.

With reference to fig. 1, a vacuum cleaner 10 of the bagless type according to the present invention comprises a suction unit 26, by means of which the dirt is taken in from the outside toward the inside, and a filtration unit 12 by means of which the dirt taken in is filtered, before the air taken in is again expelled.

The vacuum cleaner 10 comprises a primary circuit 19 by means of which the air taken in is made to pass inside it through multiple filtering stages and then expelled outside, as shown hereafter.

The primary circuit 19 provides an inlet, arrow I, of a first stream of dirty air taken in by the suction unit 26. The inlet is defined in correspondence with a connection mouth 16, for example for a specific cleaning or suction accessory, not shown in the drawings.

The primary circuit 19 develops from the mouth 16 along a first elbow-shaped pipe 18 (fig. 2) which then leads tangentially into the filtration unit 12.

At outlet from the filtration unit 12 the primary circuit 19 comprises a second pipe (figs. 1, 3 and 5), which connects to the suction unit 26 and subsequently a slit 36 is provided (fig. 5), through which the filtered and cleaned air is expelled outside the vacuum cleaner 10.

The filtration unit 12 comprises a housing shell 11 having a first upper chamber 20, which is part of the primary circuit 19, inside which a first filter 14 is disposed.

The first filter 14, in this case of the cyclonic type, is able to filter the coarse dirt introduced by the first stream of air arriving from the first pipe 18.

The first filter 14 rotates idly, when hit by the first stream of air, in order to automatically remove, thanks to its rotation, the dirt obstructing the external surface.

The housing shell 11 also comprises a second lower collection chamber 38, under which a second filter 22 is located in order to filter a second stream of air containing the fine particles of dust which pass through the first filter 14.

Between the first chamber 20 and the second chamber 38 a conveyor element 21 is provided, with a double inclined plane 23, advantageously with a spiral development. The conveyor element 21 is able to convey the air and the coarse dirt that are removed automatically by the rotation of the first filter 14 on itself toward the bottom of the second chamber 38 (figs. 2, 3, 4 and 5).

The first stream with coarse dirt is indicated in its travel by the arrows A, while the second stream of air with fine particles of dust is indicated in its travel by the arrows B.

The second filter 22 is thus downstream of the first filter 14 with respect to the direction of the streams of air A and B indicated in the drawings.

The second filter 22 is advantageously an absolute filter, or HEPA filter ("High Efficiency Particulate Arresting" filter).

The first filter 14 in this case is formed by a filter body 13, with a central axis Y of symmetry, which has an external cylindrical surface with through holes 15.

The holes 15 are provided for the passage of air to be filtered toward porous filter means 25 inside the filter body 13, typically of the sponge or foam type, for example a polyurethane filter (figs. 2, 3, 4, 5 and 6). The filter means 25 are disposed in an internal region 17 of the filter body 13 and filter the coarse dirt that passes with the air through the holes 15.

Advantageously, the filter means 25 are disposed inside the filter body 13, directly adjacent and in contact with the surface with holes 15 of the filter body 13, occupying all the space provided, so as not to create any interstices in which the dirt can accumulate, blocking up the filter prematurely.

The internal region 17 allows the second stream of air B, with fine particles of dust not filtered by the pores of the filter means 25, to pass toward the second filter 22.

The first filter 14 also comprises a third pipe 40, downstream of the internal region 17 following the normal travel of the air, so as to connect with the second filter 22.

The third pipe 40 extends downward from the lower base of the first filter 14 through the second chamber 38, and leads into the second filter 22, but is separate and does not communicate with the second chamber 38, that is, it is not in fluidic connection with it.

Between the filter body 13 and the third pipe 40 a wheel 32 or other disk-shaped element is provided, to connect the filter body 13 and the third pipe 40 (figs. 2, 3 and 4).

Bearings 48, 50, 53 are also provided, for the free rotation of the first filter 14, of which more will be said hereafter in the description.

The third pipe 40, forming part of the primary circuit 19, provides for the second steam B to exit from the internal region 17 of the first filter 14 toward the second filter 22 below.

The outlet of the second filter 22 opens toward a third chamber 46 of the primary circuit 19, which is fluidically connected by means of the second pipe 24 to the suction intake of the suction unit 26, in particular in correspondence with the relative electric motor 28.

The suction unit 26, when driven, thus puts into depression the first chamber 20 and the third pipe 40, taking in the air from the mouth 16 and from the first pipe 18, and thus filters both the coarse dirt through the first filter 14, arrows A, and also the fine particles of dust through the second filter 22, arrows B.

According to the present invention, the filter body 13 of the first filter 14 is made to rotate around the axis Y by the air itself as it enters tangentially into the first chamber 20.

To this purpose, the filter body 13, on its external surface with holes 15, has a plurality of shaped fins 42 which develop in a spiral along the axis Y of the filter 14. Alternatively to the spiral shape, linear fins may be provided, or other shapes. However, the spiral shape is advantageous from the fluid-dynamic point of view.

The spiral fins 42, when they are hit tangentially (fig. 6) by the stream of air entering from the elbow-shaped pipe 18, make the whole filter body 13 rotate upon itself around the axis Y. The filter body 13 of the first filter 14 is thus able to rotate at constant, high angular speed, for example comprised between about 800 rpm and about 3000 rpm.

The centrifugal force generated with said angular rotation speed of the first filter 14 allows to automatically clean the holes 15 of the first filter 14 that may have become blocked, removing the coarse dirt therefrom. The dirt is thrust in a centrifugal direction, conveyed through the double inclined plane 23 and is collected by falling, decanting on the bottom of the second chamber 38.

The second stream of air B then passes beyond the motor 28, through a series of layers 30 and 34 of sound-proofing material which advantageously act to abate the noise and also, due to their physical constitution, to filter the remaining fine particles.

Having passed through the layers 30 and 34, the second filtered stream of air B emerges outside the vacuum cleaner 10 through the slit 36 (fig. 5).

The first filter 14, including the third pipe 40, is mounted suspended inside the first chamber 20 and is free to rotate upon itself, that is, it is idle, with respect to the first chamber 20 and the housing shell 11, inside bearings 48, 50, 52.

Instead of bearings, bronzes can be used or other support means able to support the cyclonic filter rotatably so as to allow it to rotate freely, advantageously with limited or substantially zero friction.

The bearings, or equivalent support means, are advantageous inasmuch as, by causing limited friction, they promote an optimum idle rotation of the first filter 14, even if driven by a stream of air taken in and not motorized by an external motor as happens, on the contrary, in the state of the art.

In particular, there is a lower bearing 4, inside which the third pipe 40 rotates.

An intermediate bearing 50 is also provided, inside which the lower part 13a of the filter body 13 rotates and on which the wheel 32, interposed between the filter body 13 and the third pipe 40, rests.

Finally there is an upper bearing 52, inside which the upper part 13b of the filter body 13 rotates.

The present invention, according to another innovative feature, provides an automatic system to keep the lower 48 and intermediate bearing 50 clean. Typically, the lower 48 and intermediate bearing 50 are more subject to getting dirty and therefore to causing a deterioration in the performances in rotation of the first filter 14.

In fact, since the bearings 48 and 50 are located in zones subject to depression, the dirt is deposited on top of them, and compromises their performance.

On the contrary, the upper bearing 52, due to its upper position in which there are no depressions, is more protected from any accumulation of dirt.

In particular, the present invention exploits a third stream of air clean taken from outside, indicated by the arrows P in fig. 4, to clean the bearings.

The third stream P passes in secondary circuit 55 which passes through at least the lower bearing 48 and the intermediate bearing 50, keeping them clean. The clean air of the secondary circuit 55 is taken from outside, as indicated by the arrow C, by means of a small passage aperture 54.

The secondary circuit 55 comprises a first passage way 56, immediately downstream of the passage aperture 54, by means of which the stream of air P is made to pass through the lower bearing 48, keeping it clean (fig. 4).

Afterward, the same stream of clean air P passes through a second passage way 58 of the secondary circuit 55, in this case made as a coaxial interstice outside the third pipe 40, and rises up to the intermediate bearing 50, keeping this clean too.

Finally, the secondary circuit provides a third passage way 60, through which the same stream of air P enters into the first chamber 20.

Here the stream of air P is mixed with the air of the primary suction circuit 19, following the subsequent travel thereof as far as the exit slit 36.

In particular, the depression, indicated for convenience by the symbol (-) in fig. 4, that is created in the first chamber 20 following the suction action of the suction unit 26, with respect to the positive external pressure, tends to create inside the secondary circuit 55 an equilibrium with the positive external pressure, indicated for convenience by the symbol (+) in fig. 4, which consequently generates the third stream of air P which keeps clean at least the lower 48 and intermediate bearing 50.

Figs. 7 and 8 show a variant embodiment of the vacuum cleaner according to the present invention, indicated for convenience by the reference number 110.

In this variant, the vacuum cleaner 110 is provided with a valve 112, which is able to determine the opening/closing of an auxiliary air entrance 114 of the primary circuit 19 in communication with the outside environment, depending on whether the stream of air entering the mouth 16 is free or obstructed for some reason. The auxiliary stream of air compensates for the possible lack of main stream of air entering from the mouth 16, due for example to accidental blockages.

As a result, the filtration unit 12, in particular the filter body 13 of the first filter 14, is maintained in rotation even if the entrance of the air is completely occluded, thus allowing to keep the filter clean by an action of centrifugation.

Moreover, the auxiliary stream of air that is generated thanks to the opening of the entrance 114 not only maintains the rotation motion, but also is very effective in maintaining calm conditions in the second collection chamber 38 that collects the dust and/or dirt, preventing any turbulence from being generated inside it.

If the main air entrance through the mouth 16 is occluded during suction, the difference in pressure between the atmospheric pressure and the increased depression that is generated substantially instantaneously inside the primary circuit 19 determines the opening of the valve 112, which allows an auxiliary stream of air to enter which keeps the filter body 13 in rotation and rebalances the pressures in play inside the primary circuit 19.

In particular, in the form of embodiment shown in figs. 7 and 8, downstream of the elbow of the first pipe 18, the primary circuit 19 of the vacuum cleaner 110 has an aperture 116 from which a tubular connection portion 118 extends, to which the valve 112 is connected, in turn in cooperation with the auxiliary air entrance 114.

In particular, the valve 112 comprises a body 120 which has a connection 121 to connect to the tubular connection portion 118.

Inside the body 120 a closing element 122 is housed, the axial position of which is determined by a spring 124, or other elastic or resilient element associated therewith. The closing element 122 acts as a slider, between a lowered position, in which it closes the auxiliary entrance 114, and a raised position in which it allows the air to pass through the auxiliary entrance 114, as indicated by the arrow M in fig. 7.

In the lowered position the closing element 122 abuts against an abutment element 126, guaranteeing the closure of the auxiliary entrance 114, in this way not penalizing the suction performance of the vacuum cleaner 110 in its normal functioning. In the raised position of the closing element 122, the external air can enter through the auxiliary entrance 114 following a path that, passing into the tubular connection portion 118, enters into the first pipe 18 of the primary circuit 19 and can go to interact with the filtration unit 12, allowing the filter body 13 to rotate and to remain clean.

In this case, the closing element 122 is normally kept in the lowered position, to close the auxiliary entrance 114, thanks to the action of downward thrust of the spring 124.

The spring 124 is configured with an elastic coefficient such as to contrast the internal negative pressure during normal functioning, and to determine the lowered position of the closing element 122.

However, when the depression in the primary circuit 19 increases considerably due to the complete obstruction of the mouth 116, the elastic coefficient of the spring 124 is no longer able to resist the action of the external atmospheric pressure, which pushes the closing element 122 upward, overcoming the elastic force of the spring 124, taking the closing element 122 to its raised position which allows air to enter through the auxiliary entrance 114.

It is clear that modifications and/or additions of parts may be made to the vacuum cleaner 10, 110 as described heretofore, without departing from the field and scope of the present invention.

It is also clear that, although the present invention has been described with reference to specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of vacuum cleaner, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.