VACUUM CLEANER

FIELD OF THE INVENTION

The present invention relates to a vacuum cleaner comprising cleaning tools having different types of dirt separator.

BACKGROUND OF THE INVENTION

A vacuum cleaner may include different cleaning tools for performing different cleaning tasks. For example, a vacuum cleaner may include a cleaning tool having relatively stiff bristles for removing stubborn dirt from carpeted surfaces, and a further cleaning tool having relatively soft bristles for sweeping dirt from delicate surfaces.

SUMMARY OF THE INVENTION

The present invention provides a vacuum cleaner comprising: a suction unit; a first cleaning tool attachable to the suction unit, the first cleaning tool comprising a first dirt separator; and a second cleaning tool attachable to the suction unit, the second cleaning tool comprising a second dirt separator, wherein the first dirt separator and the second dirt separator employ different mechanisms for separating dirt from an airflow.

By providing a vacuum cleaner that comprises cleaning tools having different dirt separators, cleaning tasks may be made easier. In particular, each cleaning tool may comprise a dirt separator that is better suited to the intended cleaning task. For example, the first cleaning tool may be used for cleaning large areas, such as floor surfaces, and the first dirt separator may be relatively large with a large dirt capacity. The second cleaning tool, on the other hand, may be used for spot cleaning (e.g. picking up crumbs or dusting surfaces) and thus the second dirt separator may be relatively small with a small dirt capacity. By employing a smaller and lighter dirt separator in the second cleaning tool, the task of spot cleaning is made easier.

With existing vacuum cleaners, the same dirt separator is used with each cleaning tool. The dirt separator may be relatively large, which then makes certain cleaning tasks difficult and cumbersome. Alternatively, the dirt separator may be relatively small but then has a relatively poor separation efficiency and/or a small dirt capacity.

With the vacuum cleaner of the present invention, cleaning tasks may be made easier whilst also achieving a good overall cleaning performance. In particular, a cleaning tool may be selected having a separation efficiency and/or dirt capacity that is that is best suited to the cleaning task. For example, the first cleaning tool may be used for cleaning tasks that require the pickup and separation of both coarse dirt and fine dirt. The second cleaning tool, on the other hand, may be used for cleaning tasks that require the separation of only coarse dirt or fine dirt.

Each of the cleaning tools may comprise a suction inlet through which dirt from a surface is drawn into the vacuum cleaner. As a result, each cleaning tool is capable of both picking up dirt from a surface and then separating the dirt from the airflow.

At least one of the cleaning tools may comprise a first suction nozzle attachable to the dirt separator, and a second, different suction nozzle attachable to the dirt separator. This then further increases the flexibility of the vacuum cleaner, making cleaning tasks easier still. For example, the second cleaning tool may be used for spot cleaning and the second dirt separator may have a relatively small dirt capacity. The second cleaning tool may then have different suction nozzles for the different spot cleaning tasks. For example, the second cleaning tool may comprise a first suction nozzle have stiff bristles for removing stubborn dirt from carpeted surfaces, and a second suction nozzle having soft bristles for sweeping dust from delicate surfaces.

The first cleaning tool may comprise one or more first dirt-dislodging elements for dislodging dirt from a surface to be cleaned, and the second cleaning tool may comprise one or more second, different dirt-dislodging elements. The dirt-dislodging elements may comprise, for example, bristles, lint pickers, felt or rubber strips. By providing cleaning tools with different dirt-dislodging elements, the performance of each cleaning tool may be better suited to different cleaning tasks. For example, the first cleaning tool may comprise relatively stiff bristles for removing dirt from floor surfaces, and the second cleaning tool may comprise relatively soft bristles from removing dust from delicate surfaces.

At least one of the cleaning tools may comprise an agitator moveable to agitate a surface to be cleaned, and a drive assembly for driving the agitator. This then has the advantage that the vacuum cleaner has at least one cleaning tool that is well suited at removing dirt from carpeted surfaces.

Each dirt separator may comprise a dirt collection chamber for collecting dirt separated by the dirt separator. This then has the advantage that each cleaning tool forms a standalone unit. As a result, when the dirt collection chamber of the first cleaning tool is full, a user is not required to empty the dirt collection chamber in order to continue cleaning. Instead, the user can switch to the second cleaning tool in order to continue cleaning.

The first dirt separator may be a cyclonic separator, and the second dirt separator is a non-cyclonic separator. Moreover, the second dirt separator may comprise at least one of a filter, a mesh screen, an inertial separator, a gravitational separator, and a rotating body that throws dirt into a dirt collection chamber. A cyclonic separator has the advantage that it is capable of removing both coarse dirt and fine dirt at relatively high separation efficiencies. However, the pressure drop across a cyclonic separator may be high. By employing a non-cyclonic separator in the second cleaning tool, a higher level of suction may be achieved at the suction inlet at the expense of separation efficiency.

The vacuum cleaner may comprise a third cleaning tool attachable to the suction unit. The third cleaning tool then comprises a third dirt separator, and the first, second and third dirt separators employ different mechanisms for separating dirt from an airflow. The provision of a third cleaning tool having a dirt separator that is different to that of the first and second cleaning tools further increases the flexibility of the vacuum cleaner, making different cleaning tasks easier still.

The suction unit may comprise a suction motor and at least one of the cleaning tools may comprise an electric motor. The electric motor may be used to drive a brushbar or other agitator of the cleaning tool. Alternatively, the electric motor may be used to drive a rotating body of the dirt separator, such as a perforated disc.

The suction unit may comprise a suction motor which operates at a first power when the first cleaning tool is attached to the suction unit, and at a second, different power when the second cleaning tool is attached to the suction unit. As a result, improvements in the energy efficiency of the vacuum cleaner may be achieved. For example, for the cleaning task that the second cleaning tool is intended to perform, a lower level of suction at the suction inlet may be sufficient or indeed desired. As a result, the suction motor may operate at a lower power when the second cleaning tool is attached. Alternatively, the second dirt separator may have a lower pressure drop than the first dirt separator. As a result, the second cleaning tool is able to achieve the same level of suction (at the suction inlet) as the first cleaning tool by operating the suction motor at lower power. Where the vacuum cleaner is battery operated, any improvements in energy efficiency may extend the runtime of the vacuum cleaner.

The suction unit may form a handle of the vacuum cleaner. As a result, a relatively compact and lightweight vacuum cleaner may be achieved.

The suction unit may be cylindrical in shape. This the has the advantage that the suction unit provides a convenient shape for the user to grip.

The suction unit may comprise a suction motor and a battery pack housed within a body. This then has the advantage that cleaning tasks may be performed more easily. For example, there is no power cord that might otherwise hinder or restrict movement of the vacuum cleaner or restrict where the vacuum cleaner can used.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIG. 1 illustrates a vacuum cleaner in accordance with the present invention;

FIG. 2 illustrates a first cleaning tool of the vacuum cleaner;

FIG. 3 illustrates a second cleaning tool of the vacuum cleaner;

FIG. 4 illustrates a third cleaning tool of the vacuum cleaner;

FIG. 5 illustrates a fourth cleaning tool of the vacuum cleaner;

FIG. 6 illustrates four different suction nozzles forming part of the cleaning tool of FIG. 5;

FIG. 7 illustrates a fifth cleaning tool of the vacuum cleaner;

FIG. 8 illustrates a sixth cleaning tool of the vacuum cleaner; and

FIG. 9 illustrates a vacuum cleaner comprising a seventh cleaning tool.

DETAILED DESCRIPTION OF THE INVENTION

The vacuum cleaner 10 of FIG. 1 comprises a suction unit 20, which is removably attachable to one of a plurality of cleaning tools 30.

The suction unit 20 comprises a suction motor 21 and a battery pack 22 housed within a body 23. The battery pack 22 is coupled to and supplies electrical power to the suction motor 21. The body 23 comprises an inlet 24 through which an airflow is drawn into the suction unit 20 by the suction motor 21, and an outlet 25 (in the form of a plurality of openings) through which the airflow is discharged from the suction unit 20. The suction unit 20 further comprises a power button 26 and a mode button 27. The power button 26 is used to power on and off the suction unit 20 and thus the vacuum cleaner 10, whilst the mode button 27 is used to select different modes of operation, such as low and high suction.

The suction unit 20 is removably attachable to each cleaning tool 30 of the vacuum cleaner 10. For example, the suction unit 20 may comprise a first part 28 of a catch mechanism, provided at an end of the body 23, and each of the cleaning tools 30 may comprise a second part 38 of the catch mechanism. The suction unit 20 may also comprise electrical terminals 29 at the end of the body 23 for supplying electrical power from the battery pack 22 to a cleaning tool 30 attached to the suction unit 20.

The suction unit 20 is cylindrical in shape and forms a handle of the vacuum cleaner 10. A user grips and manipulates the suction unit 20 in order to manoeuvre the attached cleaning tool 30 over a surface to be cleaned.

FIG. 2 shows a first cleaning tool 100 of the vacuum cleaner 10. The first cleaning tool 100 comprises a suction nozzle 110, a dirt separator 120, and an outlet duct 130.

The suction nozzle 110 comprises a duct 111 having a suction inlet 112 at one end. The duct 111 is attached to the dirt separator 120 at the opposite end and provides an airflow path from the suction inlet 112 to the dirt separator 120.

The dirt separator 120 is a gravitational separator and comprises a separation chamber 121 having an inlet 122 and an outlet 123, and a dirt collection chamber located 124 below the separation chamber 121. The dirt separator 120 further comprises a mesh screen 125 located upstream of the outlet 123. Dirt-laden air enters the separation chamber 121 via the inlet 122 and is drawn towards the outlet 123. Dirt entrained in the air collides with the mesh screen 125, whereupon the dirt loses its momentum and falls under the force of gravity into the dirt collection chamber 124. The cleansed air then passes though the mesh screen 124 and exits the separator 120. The dirt separator 120 comprises a hinged base 126, which can be opened to remove dirt collected within the dirt collection chamber 124.

The outlet duct 130 is attached at one end to the dirt separator 120, and is removably attachable to the suction unit 20 at an opposite end. The outlet duct 130 provides an airflow path from the outlet 123 of the dirt separator 120 to the inlet 24 of the suction unit 20.

During use of the vacuum cleaner 10, the suction nozzle 110 of the cleaning tool 100 is placed onto or near a surface to be cleaned. Where the cleaning surface is a carpeted surface or an upholstered surface, the suction nozzle 110 may be moved against the surface in order to agitate and dislodge dirt from the surface. Suction generated by the suction unit 20 causes dirt-laden air to be drawn into the cleaning tool 100 via the suction inlet 112. The dirt-laden air is carried along the duct 111 of the suction nozzle 110 to the dirt separator 120. Dirt entrained in the air is then separated by the dirt separator 120 and collects in the dirt collection chamber 124, whilst the cleansed air is drawn into the suction unit 20 via the outlet duct 130.

FIG. 3 shows a second cleaning tool 200 of the vacuum cleaner 10. The second cleaning tool 200 comprises a suction nozzle 210, a dirt separator 220, and an outlet duct 230.

The suction nozzle 210 comprises a duct 211 and a dusting brush 215. The duct 211 bends through 90 degrees and comprises a suction inlet 212 at one end, and is removably attached to the outlet duct 230 at the opposite end. The dusting brush 215 is attached to the duct 211 via spokes 217 and comprises a plurality of bristles 216 that extend beyond the suction inlet 212.

The dirt separator 220 is a filter and comprises a filter medium 221, a frame 222, an end cap 223 and a seal 224. The filter medium 221 forms a hollow tube that is held open at one end by the frame 222, and is closed at an opposite end by the end cap 223. The frame 222 comprises a disc-shaped body 225 having a central opening, and a tab 227 attached to the body 225 by spokes 228. The seal 224 is provided around the outside of the body 225 of the frame 222. The dirt separator 220 is removably positioned within the duct 211 of the suction nozzle 210. When positioned within the duct 211, the seal 224 creates a seal between the frame 222 of the dirt separator 220 and the duct 211 of the suction nozzle 210.

The outlet duct 230 is removably attached at one end to the duct 211 of the suction nozzle 210, and is removably attachable to the suction unit 20 at an opposite end.

During use of the vacuum cleaner 10, the dusting brush 215 is swept across a surface to be cleaned, causing dirt to be dislodged from the surface. Suction generated by the suction unit 20 causes the dislodged dirt to be drawn into the cleaning tool 200 via the suction inlet 212. The dirt-laden air is then carried along the duct 211 of the suction nozzle 210 to the dirt separator 220. The dirt-laden air is then drawn through the filter medium 221 of the dirt separator 220, causing dirt to be separated from the air and retained by the filter medium 221. The cleansed air is then drawn through the central opening in the frame 222 of the dirt separator 220 and into the suction unit 20 via the outlet duct 230. In order to remove and clean the dirt separator 220, the outlet duct 230 is first detached from the suction nozzle 210. The dirt separator 220 is then removed from the suction nozzle 210 by grasping and pulling the tab 227.

FIG. 4 shows a third cleaning tool 300 of the vacuum cleaner 10. The third cleaning tool 300 comprises a suction nozzle 310, a dirt separator 320, and an outlet duct 330.

The suction nozzle 310 comprises a housing 311, a suction inlet 312, a brushbar assembly 314, and a duct 315. The housing 311 defines a chamber 316 within which the brushbar assembly 314 is mounted. The suction inlet 312 is provided on an underside of the housing 311, and the duct 315 extends rearwardly from the housing 311 and provides an airflow path from the suction inlet 312 to the dirt separator 320.

The brushbar assembly 314 comprises a brushbar 340 rotatably mounted to the housing 311, and a drive assembly 345 for driving the brushbar 340. The brushbar 340 comprises a cylindrical body 341 that surrounds the drive assembly 345 and to which are secured bristles 342, flicker strips, or other means for agitating and dislodging dirt from a surface to be cleaned. The drive assembly 345 comprises an electric motor 346 and a transmission (not shown) for transmitting torque generated by the electric motor 346 to the brushbar 340. The electric motor 346 is powered by electrical power supplied by the battery pack 22 of the suction unit 20. In the embodiment shown in FIG. 4, the drive assembly 345 is located inside the brushbar 340. Alternatively, the drive assembly 345 may be located outside of the brushbar 340. Moreover, rather than an electric motor 346, the drive assembly 345 may comprise alternative means, such as an air turbine, for generating the torque necessary to drive the brushbar 340.

The dirt separator 320 is an inertial separator and comprises a separation chamber 321 having an inlet 322 and an outlet 323, and a dirt collection chamber 324. The dirt separator 320 further comprises a separation wall 325 and a mesh screen 326. Dirt-laden air enters the separation chamber 321 via the inlet 322. The dirt-laden air turns through 90 degrees and follows a path parallel to the separation wall 325. Upon passing the end of the separation wall 325, the air turns through 180 degrees and follows a path parallel to the separation wall 325 but in an opposite direction. Relatively heavy dirt entrained in the air is unable to match the turn taken by the air due to its greater inertia and instead continues along a straighter path. The dirt collects in the dirt collection chamber 324 whilst the cleansed air exits the separator 320 via the outlet 323. The mesh screen 326 extends from an end of the separation wall 325 to an outer wall of the dirt separator 320. The air turning through 180 degrees passes through the mesh screen 326 before exiting the separator 320. The mesh screen 326 therefore acts to protect the suction unit 20 by ensuring that dirt of a certain size is prevented from inadvertently exiting the separation chamber 321. An outer wall of the dirt separator chamber 320 may be arranged to hinge or slide in order to remove dirt collected within the dirt collection chamber 324.

The outlet duct 330 is attached at one end to the dirt separator 320, and is removably attachable to the suction unit 20 at an opposite end. The outlet duct 330 provides an airflow path from the outlet 323 of the dirt separator 320 to the inlet 24 of the suction unit 20.

During use of the vacuum cleaner 10, the suction nozzle 310 is placed onto the surface to be cleaned. The cleaning tool 300 is intended primarily for use on a carpeted surface, where the brushbar 340 acts to beat or agitate the piles of the carpet in order to better release trapped dirt. Suction generated by the suction unit 20 causes dirt-laden air to be drawn into the cleaning tool 300 via the suction inlet 312. The dirt-laden air is carried along the duct 311 of the suction nozzle 310 to the dirt separator 320. Dirt entrained in the air is then separated by the dirt separator 320 and collects in the dirt collection chamber 324, whilst the cleansed air is drawn into the suction unit 20 via the outlet duct 330.

FIG. 5 shows a fourth cleaning tool 400 of the vacuum cleaner 10. The fourth cleaning tool 400 comprises a dirt separator 420, and an outlet duct 430. The cleaning tool 400 also comprises a plurality of suction nozzles, such as those shown in FIG. 6. Each of the suction nozzles is removably attachable to the dirt separator 420.

The dirt separator 420 is a cyclonic separator and comprises a separation chamber 421 having an inlet 422 and an outlet 423, a dirt collection chamber 424 located below the separation chamber 421, and a mesh screen 425. Dirt-laden air enters the separation chamber 421 tangentially via the inlet 422. The dirt-laden air then spirals around the separation chamber 421, causing dirt to be separated from the air. The cleansed air passes through the mesh screen 425 and exits the separator 420 via the outlet 423, whilst the separated dirt collects in the dirt collection chamber 424. Again, the dirt separator 420 comprises a hinged base 426, which can be opened to remove the dirt collected in the dirt collection chamber 424.

The cleaning tool 400 comprises a plurality of suction nozzles, each of which is removably attachable to the dirt separator 420. By way of example, FIG. 6 illustrates four suction nozzles 410a-410d. Each of the suction nozzles 410a-410d comprises a suction inlet through which dirt-laden air is drawn into the suction nozzle, and a duct for carrying the dirt-laden air from the suction inlet to the dirt separator. The first suction nozzle 410a (FIG. 6a) comprises a plurality of relatively stiff bristles 415a that surround the suction inlet. The first suction nozzle 410a is intended for use in removing stubborn or trapped dirt from carpeted surfaces, upholstery and the like. The second suction nozzle 410b (FIG. 6b) comprises a plurality of relative soft bristles 415b, which again surround the suction inlet. The second suction nozzle 410b is intended to sweep and lift dust from delicate surfaces. The third suction nozzle 410c (FIG. 6c) comprises a relatively narrow, elongate duct 411c and is intended for use in removing dirt from crevices and other hard-to-reach places. The fourth suction nozzle 410d (FIG. 6d) is similar to the suction nozzle 310 of the cleaning tool 300 of FIG. 4 and comprises a rotatable brushbar 440d. The brushbar 440d comprises a cylindrical body to which alternate narrow and wide strips of bristles 442d,443d are attached. Each narrow strip comprises relatively long carbon fibre bristles 442d. Each wide strip comprises relatively short, soft nylon bristles 443d formed as a dense pile. The fourth suction nozzle 440d is intended to be used on hard floors, such as wooden, stone or tiled floors. As the brushbar 440d rotates, the short bristles 443d are crushed between the body of the brushbar 440d and the floor to create an effective seal between the brushbar 440d and the floor. As a result, higher airflow speeds may be achieved which in turn entrain more of the dirt. The long bristles 442d flex on contacting the surface and act to sweep dirt up into the suction nozzle 410d.

FIG. 7 shows a fifth cleaning tool 500 of the vacuum cleaner 10. The fifth cleaning tool 500 comprises a dirt separator 520, and an outlet duct 530. Like the fourth cleaning tool of FIG. 5, the fifth cleaning tool 500 comprises a plurality of suction nozzles, such as those shown in FIG. 6, which are removably attachable to the dirt separator 520.

The dirt separator 520 is an inertial separator similar in many respects to that of FIG. 4. The dirt separator 520 comprises a separation chamber 521 having an inlet 522 and an outlet 523, and a dirt collection chamber 524 located below the separation chamber 521. The dirt separator 520 further comprises a separation duct 525 located within the separation chamber 521, and a mesh screen 526 provided at one end of the separation duct 521. Dirt-laden air enters the separation chamber 521 via the inlet 522. The dirt-laden air moves downwards along a path parallel to the separation duct 521. Upon passing the end of the separation duct 521, the air turns through 180 degrees and enters the separation duct 521. Relatively heavy dirt entrained in the air is unable to match the turn taken by the air due to its greater inertia and instead continues along a downward path and into the dirt collection chamber 524. The cleansed air then moves upward through the separation duct 521 and exits the separator 520 via the air outlet 523. The mesh screen 526 acts to protect the suction unit 20 by ensuring that dirt of a certain size is prevented from inadvertently exiting the separation chamber 521.

FIG. 8 shows a sixth cleaning tool 600 of the vacuum cleaner 10. The sixth cleaning tool 600 comprises a dirt separator 620, and an outlet duct 630. Again, as with the fourth and fifth cleaning tools of FIGS. 5 and 7, the sixth cleaning tool 600 comprises a plurality of suction nozzles, such as those shown in FIG. 6, which are removably attachable to the dirt separator 620.

The dirt separator 620 comprises a separation chamber 621, an inlet duct 622, a disc assembly 623, and a dirt collection chamber 624 located beneath the separation chamber 621. The inlet duct 622 extends within the separation chamber 621 and terminates a short distance from the disc assembly 623. One end of the inlet duct 622 defines an inlet to the separation chamber 621. The opposite end of the inlet duct 622 is attachable to a suction nozzle. The disc assembly 623 comprises a disc 625 driven by an electric motor 626. The disc 625 comprises a central non-perforated region surrounded by a perforated region. The disc 625 is located at and covers an outlet of the separation chamber 621. Dirt-laden air enters the separation chamber 621 via the inlet duct 622 and is directed at the centre of the disc 625. The central non-perforated region of the disc 625 causes the dirt-laden air to turn and move radially outward (i.e. in a direction normal to the rotational axis). The rotating disc 625 imparts tangential forces to the dirt-laden air, causing the air to swirl. As the dirt-laden air moves radially outward over the surface of the disc 625, the tangential forces imparted to the dirt and air increase. Upon reaching the perforated region of the disc, the air is drawn through the perforations in the disc. This requires a further turn in the direction of the air. Relatively heavy dirt entrained in the air is unable to match the turn of the air due to its greater inertia. As a result, rather than being drawn through the perforations in the disc 625, the dirt continues to move radially outwards and falls into the dirt collection chamber 624 located below. Again, the dirt separator 620 comprises a hinged base 628, which can be opened to remove the dirt collected within the dirt collection chamber 624.

FIG. 9 shows the suction unit 20 attached to a seventh cleaning tool 700. The seventh cleaning tool 700 comprise a suction nozzle 710, a tubular wand 740, a dirt separator 720 and an outlet duct 730.

The suction nozzle 710 is similar to that of FIGS. 4 and 7(d) and comprises a housing, a suction inlet, a brushbar, and a duct. The suction inlet is provided on an underside of the housing, the brushbar is rotatable mounted within the housing, and the duct extends rearwardly from the housing and provides an airflow path from the suction inlet to the tubular wand 740.

The tubular wand 740 is removably attached at one end to the suction nozzle 710, and at the opposite end to the dirt separator 720. The wand 740 provides an airflow path from the suction nozzle 710 to the dirt separator 720.

The dirt separator 720 is a cyclonic separator of the type described in GB2569820A and comprises a first separation stage and a second separation stage located downstream of the first separation stage. Each separation stage comprise a separation chamber for separating dirt from an airflow using cyclonic action, and a dirt collection chamber for collecting the separated dirt.

The outlet duct 730 is attached at one end to the dirt separator 720, and is removably attached to the suction unit 20 at an opposite end. The outlet duct provides an airflow path from an outlet of the dirt separator 720 to the inlet 24 of the suction unit 20.

During use of the vacuum cleaner 10, a user grips and manipulates the suction unit 20 in order to the manoeuvre the suction nozzle 710 over a surface to be cleaned. The provision of the tubular wand 740 enables the vacuum cleaner 10 to be used by a user in a standing position.

Different configurations are possible with the vacuum cleaner 10 of FIG. 9. For example, the tubular wand 740 may be removed and the dirt separator 720 may be attached to the suction nozzle 710 in order to achieve a more compact arrangement. The suction nozzle 710 may be changed, perhaps for one of the suction nozzles shown in FIG. 6. Furthermore, the dirt separator 720 may be attached to the suction nozzle 710, and the tubular wand 740 may be attached at one end to the dirt separator 720 and at the opposite end to the suction unit 20. As a result, the dirt separator 720 is moved further from the suction unit 20. This then has the advantage of reducing the weight in the hand of the user. However, a potential disadvantage of this arrangement is that the dirt separator 720 may impede or restrict movement of the suction nozzle 710 around or under furniture.

With the vacuum cleaner of the present invention, the suction unit may be attached to cleaning tools having different dirt separators. As a result, cleaning tasks may be made easier. For example, the vacuum cleaner of FIG. 9 may be used to clean floor surfaces. When the vacuum cleaner is subsequently used to clean, say, crumbs from a kitchen worktop, the suction unit may be detached from the cleaning tool 700 of FIG. 9 and attached to the cleaning tool 100 of FIG. 2. This then makes the cleaning task easier for the user. In particular, the relatively large and heavy dirt separator 720 of the cleaning tool of FIG. 9 may be discarded in favour of the small and light dirt separator 120 of the cleaning tool of FIG. 2. Similarly, when the vacuum cleaner of FIG. 9 is subsequently used to clean dust from delicate surfaces, the suction unit may be detached from the cleaning tool 700 of FIG. 9 and attached to the cleaning tool 300 of FIG. 2.

With existing vacuum cleaners, the same dirt separator must be used with each cleaning tool. The dirt separator is often relatively large, which makes certain cleaning tasks more difficult and cumbersome. Alternatively, the dirt separator may be relatively small but then has a relatively poor separation efficiency.

With the vacuum cleaner of the present invention, cleaning tasks may be made easier whilst also achieving a good overall cleaning performance. In particular, a cleaning tool may be selected having a separation efficiency that is that is best suited to the cleaning task. For example, the cleaning tool 700 of FIG. 9 may be used for cleaning tasks that require the pickup and separation of both coarse dirt and fine dirt. The cleaning tool 100 of FIG. 2 may be used for cleaning tasks that require the separation of coarse dirt only, whilst the cleaning tool 200 of FIG. 3 may be used for cleaning tasks that require the separation of fine dirt only.

Other benefits may be realised with the vacuum cleaner of the present invention. For example, with the dirt separator 720 of the cleaning tool 700 of FIG. 9, dirt-laden air spins at relatively high speeds within the separation chamber. Consequently, if the vacuum cleaner were used to catch an insect for subsequent release, there is a strong likelihood that the insect will be injured or killed. By contrast, the dirt separator 120 of the cleaning tool 100 of FIG. 2 is less aggressive and may be used to catch the insect without injury.

Energy efficiencies may be achieved with the vacuum cleaner of the present invention. As a result, the runtime of the vacuum cleaner may be increased. For example, different cleaning tools may require different levels of suction at the suction inlet in order to best perform the intended cleaning task. Rather than operating the suction motor at a single, relatively high power, the suction motor may instead operate at different electrical powers according to the cleaning tool that is attached. As a result, savings in electrical power may be achieved. In a further example, the pressure drop across each dirt separator is likely to be different. For example, the pressure drop across the dirt separator 720 of FIG. 9, which has two stages of cyclonic separation, is likely to be significantly higher than that across the dirt separator of FIG. 2. When using the cleaning tool of FIG. 9, the suction motor operates at a given electrical power in order to achieve a given level of suction at the suction inlet. When using the cleaning tool of FIG. 2, the same level of suction may be achieved by operating the suction motor at a lower electrical power. So again, savings in electrical power may be achieved.

Changes in the electrical power drawn by the suction motor 21 may be controlled by the user using the mode button 27. So, for example, upon switching from the cleaning tool 700 of FIG. 9 to the cleaning tool 100 of FIG. 2, the user may select a lower power for the suction motor 21 using the mode button 27. Alternatively, the suction unit 20 may automatically control the electrical power drawn by the suction motor 21 according the type of cleaning tool that is attached. In particular, the suction motor 21 may operate at a first power when a first cleaning tool (e.g. 700) is attached to the suction unit 20, and the suction motor 21 may operate at a second, different power when a second cleaning tool (e.g. 100) is attached to the suction unit 20.

The cleaning tools described above are provided by way of example only. The vacuum cleaner may comprise additional and/or alternative cleaning tools, so long as at least two cleaning tools are provided that have different dirt separators. Accordingly, in a more general sense, the vacuum cleaner may be said to comprise a suction unit to which are attachable a first cleaning tool and a second cleaning. The first cleaning tool comprises a first dirt separator, the second cleaning tool comprises a second dirt separator, and the first dirt separator and the second dirt separator employ different types of separation. That is to say that the first dirt separator and the second dirt separator employ different mechanisms for separating dirt from an airflow. So, for example, a filter medium (which separates dirt primarily by impaction, interception and diffusion) employs very different mechanism to, say, a cyclonic separator (which separates dirt primarily by centrifugal forces).

Each dirt separator may employ more than one type of separation. For example, with the dirt separator 500 of FIG. 7, dirt is first removed by inertial separation. Additional dirt of a certain size is then removed by the mesh screen 526, which employs surface filtration in order to remove the dirt. As a further example, the dirt separator 400 of FIG. 5 may further comprise a filter medium for filtering the air after passing through the mesh screen 425. Consequently, the first dirt separator and the second dirt separator may employ more than one type of separation. Moreover, the two separators may employ a type of separation that is common to both separators. Nevertheless, the first dirt separator employs at least one type of separation that differs from that employed by the second dirt separator, i.e. the first dirt separator employs at least one mechanism for removing dirt that differs from that of the second dirt separator.

As well as having different dirt separators, the cleaning tools may comprise different features or elements for dislodging dirt from a surface to be cleaned. In the embodiments described above, some of the suction nozzles comprise dirt-dislodging elements in the form of bristles. The bristles then vary in type, lengths and/or stiffnesses. The cleaning tools may comprise additional and/or alternative types of dirt-dislodging elements, such as lint pickers, felt strips, and rubber strips. By providing cleaning tools with different dirt-dislodging elements, the performance of each cleaning tool may be better suited to different cleaning tasks. The dirt-dislodging elements may be static or they may form part of a brushbar or other agitator that moves to agitate the cleaning surface.

In the embodiments described above, the suction unit comprises a battery pack that supplies electrical power to the suction motor. Conceivably, the battery pack may be omitted and the suction motor may instead be powered by mains electricity. However, the provision of a battery pack has the advantage that cleaning tasks may be performed more easily. For example, there is no power cord that might otherwise hinder or restrict movement of the vacuum cleaner or restrict where the vacuum cleaner can used.

VACUUM CLEANER

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