VACUUM CLEANER

Abstract

A vacuum cleaner including a cleaner head defining a suction chamber and having an agitator arranged to be rotated by an agitator motor, a dirt separator, a vacuum motor arranged to draw air into the suction chamber and then into the dirt separator, and a controller. The controller is configured to monitor the electrical load of the agitator motor, compare the magnitude of the electrical load to a threshold, and selectively adjust the electrical power delivered to the vacuum motor. The controller is configured either to increase the electrical power delivered to the vacuum motor to a predetermined upper power level if the electrical load is greater than the threshold, or to decrease the electrical power delivered to the vacuum motor to a predetermined lower power level if the electrical load is smaller than the threshold.

Claims

1. A vacuum cleaner comprising: a cleaner head defining a suction chamber and having an agitator arranged to be rotated by an agitator motor; a dirt separator; a vacuum motor arranged to draw air into the suction chamber and then into the dirt separator; and a controller configured to monitor an electrical load of the agitator motor, compare a magnitude of the electrical load to a threshold, and selectively adjust the electrical power delivered to the vacuum motor, wherein the controller is configured to at least one of: increase the electrical power delivered to the vacuum motor to a predetermined upper power level when the electrical load is greater than the threshold, and decrease the electrical power delivered to the vacuum motor to a predetermined lower power level when the electrical load is smaller than the threshold.

2. The vacuum cleaner of claim 1, wherein the controller is configured both to increase the power delivered to the vacuum motor to the upper power level when the electrical load is greater than the threshold, and to decrease the power delivered to the vacuum motor to the lower power level when the electrical load is smaller than the threshold.

3. The vacuum cleaner of claim 2, wherein the controller can be set to supply to the vacuum motor no other power level except the upper power level and the lower power level.

4. The vacuum cleaner of claim 2, wherein the controller is configured to continue monitoring the electrical load of the agitator after making an adjustment to the power delivered to the vacuum motor, and to make a further adjustment upon detecting that the electrical load of the agitator motor has crossed over the threshold.

5. The vacuum cleaner of claim 1, wherein the controller is configured to monitor the agitator motor electrical load in terms of current draw of the electrical motor, and compare the current draw detected to a current threshold.

6. The vacuum cleaner of claim 1, wherein the controller is configured to retain a record of the power level that was being delivered to the vacuum motor when the vacuum cleaner was last turned off, and is configured to resume delivery of that power level to the vacuum motor when the vacuum cleaner is next turned on.

7. The vacuum cleaner of claim 1, wherein the controller is configured to deliver a predetermined initial power level, which does not correspond to the upper power level or the lower power level, to the vacuum motor when the vacuum cleaner is turned off and then on again.

8. The vacuum cleaner of claim 1, wherein the controller is configured to adjust the power delivered to the vacuum motor to the upper or lower power level gradually.

9. The vacuum cleaner of claim 8, where the controller is configured to adjust the power delivered to the vacuum motor to the upper or lower power level over a time of at least 0.5 seconds.

10. The vacuum cleaner of claim 8, wherein the controller is configured to adjust the power delivered to the vacuum motor to the upper or lower power level over a time of no more than 6 seconds.

11. The vacuum cleaner of claim 1, wherein the controller is further configured to compare the magnitude of the electrical load to a spike threshold which is higher than said threshold, and to decrease the power delivered to the vacuum motor if the electrical load is larger than the spike threshold.

12. The vacuum cleaner of claim 1, wherein the controller is configured to decrease the power delivered to the vacuum motor, in response to the electrical load being larger than the spike threshold, as a step change.

13. The vacuum cleaner of claim 1, wherein the threshold is a discrete value.

14. The vacuum cleaner of claim 1, wherein the controller is configured to at least one of: increase the electrical power delivered to the vacuum motor to a predetermined upper power level when the electrical load is greater than the threshold, and decrease the electrical power delivered to the vacuum motor to a predetermined lower power level when the electrical load is smaller than the threshold when the controller is in a first mode, and wherein the controller has a second mode.

15. The vacuum cleaner of claim 14, wherein the controller is configured to supply a single predetermined power level to the vacuum motor when the controller is in the second mode.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0064] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0065] FIG. 1 is a perspective view of a vacuum cleaner according to a first embodiment of the invention;

[0066] FIG. 2 is a view of a cleaner head of the vacuum cleaner of FIG. 1, shown from underneath;

[0067] FIG. 3 is a schematic illustration of electrical components of the vacuum cleaner of FIG. 1;

[0068] FIG. 4 is a schematic flow chart showing the control operations performed by a controller of the vacuum cleaner of FIG. 1;

[0069] FIG. 5 is a schematic flow chart showing the control operations performed by a controller of a vacuum cleaner according to a second embodiment of the invention; and

[0070] FIG. 6 is a schematic flow chart showing the control operations performed by a controller of a vacuum cleaner according to a third embodiment of the invention.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0071] Throughout the description and drawings, corresponding reference numerals denote corresponding features.

[0072] 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. It has a cleaner head 4 connected to a main body 6 by a generally tubular elongate wand 8. The cleaner head 4 is also connectable directly to the main body 6 to transform the vacuum cleaner 2 into a handheld vacuum cleaner.

[0073] The main body 6 comprises a dirt separator 10 which in this case is a cyclonic separator. The cyclonic separator has a first cyclone stage 12 comprising a single cyclone, and a second cyclone stage 14 comprising a plurality of cyclones 16 arranged in parallel. The main body 6 also has a removable filter assembly 18 provided with vents 20 through which air can be exhausted from the vacuum cleaner 2.

[0074] In this case the main body 6 of the vacuum cleaner 2 has a pistol grip 22 positioned to be held by the user. At an upper end of the pistol grip 22 is an on/off switch in the form of a trigger (not visible) which must be held (i.e. pulled) in order to keep the vacuum cleaner turned on. As soon as the user releases the trigger, the vacuum cleaner is turned off. Positioned beneath a lower end of the pistol grip 22 is a battery pack 26 which comprises a plurality of rechargeable cells (not visible). A controller in the form of a PBC (not visible), and a vacuum motor (not visible) comprising a fan driven by an electric motor are provided in the main body 6 behind the dirt separator 10.

[0075] The cleaner head 4 is shown from underneath in FIG. 2. The cleaner head 4 has a casing 30 which defines a suction chamber 32 and a sole plate 34. The sole plate 34 has a suction opening 36 through which air can enter the suction chamber 32, and wheels 37 for engaging a floor surface. The casing 30 defines an outlet 38 through which air can pass from the suction chamber 32 into the wand 6.

[0076] Positioned inside the suction chamber 32 is an agitator 40 in the form of a brush bar. The agitator 40 can be driven to rotate inside the suction chamber 32 by an agitator motor (not visible). The agitator motor of this embodiment is received inside, more specifically fully inside, the agitator 40. The agitator 40 has helical arrays of bristles (not shown) projecting from grooves 42, and is positioned in the suction chamber such that the bristles project out of the suction chamber 34 through the suction opening 36.

[0077] FIG. 3 is a schematic representation of the electrical components of the vacuum cleaner 2, in which the trigger 24, the cells 27 of the battery pack 26, the bristles 43 of the agitator 40, the controller 50, the vacuum motor 52 and the agitator motor 54 are visible. Basic operation of the vacuum cleaner will now be described with reference to FIG. 3 in combination with FIGS. 1 and 2.

[0078] When the user pulls the trigger 24, the controller 50 supplies electrical power from the cells 27 of the battery pack 26 to the vacuum motor 52. This creates a flow of air through the machine so as to generate suction. Air with dirt entrained therein is sucked into the cleaner head 4, into the suction chamber 32 through the suction opening 36. From there, the air is sucked through the outlet 38 of the cleaner head 4, along the wand 6 and into the dirt separator 10. Entrained dirt is removed by the dirt separator 10 and then the relatively clean air is drawn through the vacuum motor, through the filter assembly 18 and out of the vacuum cleaner 2 through the vents 20.

[0079] In addition, when the trigger 24 is pulled the controller 50 also supplies electrical power from the battery pack 26 to the agitator motor 54, through wires 56 running along the inside of the wand, so as to rotate the agitator 40. When the cleaner head 4 is on a hard floor, it is supported by the wheels 37 and the sole plate 34 and agitator 40 are spaced apart from the floor surface. When the cleaner head 4 is resting on a carpeted surface, the wheels 37 sink into the pile of the carpet and the sole plate 34 (along with the rest of the cleaner head 4) is therefore positioned further down. This allows carpet fibres to protrude towards (and potentially through) the suction opening 36, whereupon they are disturbed by bristles 42 of the rotating agitator 40 so as to loosen dirt and dust therefrom.

[0080] The controller 50 monitors the electrical load of the agitator motor 54, compares the magnitude of the electrical load to a threshold, and selectively adjusts the electrical power delivered to the vacuum motor 52 as a result. In this case, the controller monitors the electrical load in terms of the current draw of the agitator motor 54, and compares this to a current threshold. The current threshold in this embodiment is a range, from 1.5 A to 2 A. The operation of the controller 50 will now be described in more detail with reference to FIGS. 1 to 3 in combination with FIG. 4, which is a flow chart showing the decision steps and actions performed by the controller 50.

[0081] When the vacuum cleaner 2 is turned on by pulling the trigger 24, the controller 50 supplies electrical power to the vacuum motor 52 at an initial power level. This is shown in block A. In this case the initial power level is 130 W.

[0082] As discussed above, when the trigger 24 is pulled the controller 50 also supplies electrical power to the agitator motor 54. In this embodiment, however, the controller 50 does not adjust the electrical power delivered to the agitator motor 54. Accordingly, the supply of power to the agitator motor 54 is not represented in FIG. 4.

[0083] After supplying electrical power to the vacuum motor 52 and agitator 54, the controller detects the current draw of the agitator motor 54 (block B). It then compares the measured value to the threshold range. More particularly, the controller 50 queries whether or not the detected current draw is larger than the threshold range (i.e. larger than 2 A), as shown in block C. If the detected current draw is above the current threshold then the controller 50 increases the electrical power delivered to the vacuum motor 52 from the initial power level to an upper power level (block D). In this case the upper power level is 180 W.

[0084] If the detected current draw is not larger than the threshold range, the controller again compares the detected current draw to the threshold, in this case querying whether or not the detected current draw of the agitator motor 54 is smaller than the threshold range (i.e. less than 1.5 A). This is shown in block E. If this is the case then the controller 50 decreases the electrical power delivered to the vacuum motor 52 from the initial power level to a lower power level (block F). In this embodiment the lower power level is 80 W.

[0085] If the detected current draw is neither above nor below the threshold (i.e. is between 1.5 A and 2 A) the controller 50 does not make an adjustment and continues to deliver the initial power level to the vacuum motor. Whether or not a power level adjustment is made after performing the above comparison(s) between the current draw and the threshold, the controller then implements a time delay (block G) before detecting the current draw of the agitator motor 54 again (block A). The time delay of this embodiment is 0.3 seconds. In other words the controller 50 monitors the current draw periodically with a time period of 0.3 seconds. In other embodiments, however, the time delay may be omitted so that the controller monitors the agitator motor 54 current draw continually (notwithstanding any negligible time delay caused by the controller implementing some of blocks B-F).

[0086] After the time delay has been performed (block G) and the agitator motor current draw measured (block B), the controller 50 compares the new value to the threshold (blocks C and E) again. If the measured value has the same position relative to the threshold range (i.e. above, below or within the threshold range) then no adjustment is made, the time delay (block G) is implemented and the cycle repeats again. However, if the measured current draw has changed position relative to the threshold then an adjustment may be made. For instance, if the current draw was previously within the threshold but had moved to above the threshold then the controller 50 would increase the power delivered to the vacuum motor from the initial power level to the upper power level. As another example, if the current draw was previously above the threshold but had moved to below the threshold then the controller 50 would decrease the power delivered to the vacuum motor 52 from the upper power level to the lower power level. If, on the other hand, the current draw was previously above or below the threshold but had then moved to within the threshold, no adjustment would be made and the power delivered to the vacuum motor 52 would remain at the same power level (i.e. the upper power level or lower power level).

[0087] It will be understood from FIG. 4 that as long as the current draw of the agitator motor 54 remains within the threshold after the machine is turned on, the power level delivered to the vacuum motor will be the initial power level. However, the threshold and power levels have been selected to make this scenario unlikely in practice. The controller 50 is expected to adjust the power level to the upper power level or lower power level relatively quickly (if not during the first cycle of the steps shown in FIG. 4). It will be understood that once the first adjustment to the power level has been made by the controller 50, the controller becomes set to supply to the vacuum motor 52 no other power level except the low power level and upper power level. In other words, it becomes set and will only supply either 80 W or 180 W to the vacuum motor 52.

[0088] It is noteworthy that in this embodiment, whenever the controller makes an adjustment to the power level supplied to the vacuum motor 52, it does so gradually rather than making a step change to the power level. More particularly, it adjusts the power level over a period of around two seconds. This avoids sudden changes to the speed of the vacuum motor 52 (resulting from sudden changes to the power supplied) which may confuse the user.

[0089] FIG. 5 is a flow chart showing the decision steps and actions performed by a controller of a vacuum cleaner according to a second embodiment of the invention. The second embodiment is generally the same as the first embodiment, therefore only the differences will be described here.

[0090] In the second embodiment, in each cycle the controller 50 compares the detected current draw of the agitator motor 54 to a spike threshold (block H), before the current draw is compared to the threshold described above (blocks C and E). In this case the spike threshold is a discrete value, namely 5 A. If the current draw exceeds the spike threshold (i.e. is more than 5 A) then the controller 50 decreases the electrical power delivered to the vacuum motor 52, in this case setting it to the lower power level (i.e. 80 W). This is shown in block I. Whereas the adjustments made in blocks D and F are gradual, the adjustment made in block I is stepwisethe power is dropped to the lower power level as rapidly as the controller can achieve.

[0091] After the power level has been adjusted in step I, the controller implements the time delay (block G) and then re-measures the current draw (block B), starting the cycle again. If the current draw was and remains above the spike threshold then the controller 50 will continue to deliver the lower power level to the vacuum motor 52 (as it will if the current draw drops from above the spike threshold to below the threshold (i.e. from above 5 A to below 1.5 A) during a single time delay period). However, if the current draw now lies between the threshold and the spike threshold then the controller 50 will deliver the upper power level to the vacuum motor 52.

[0092] For the avoidance of doubt, while the current draw of the agitator motor 54 remains below the spike threshold, the vacuum cleaner 2 of the second embodiment will behave in the same manner as that of the first embodiment.

[0093] FIG. 6 is a flow chart showing the decision steps and actions performed by a controller of a vacuum cleaner according to a third embodiment of the invention. This embodiment is also similar to the first embodiment, therefore again only the differences will be described here.

[0094] In this embodiment the controller 50 includes a memory in which it stores a record of the power level which was being delivered to the vacuum motor 52 when the vacuum cleaner 2 was last turned off. Further, rather than delivering an initial power level to the vacuum motor 52 when the vacuum cleaner 2 is first turned on, the controller 50 delivers the power level which was being delivered when the vacuum cleaner was last turned off.

[0095] Whenever the controller 50 makes an adjustment, it writes (or overwrites) into the memory a record of the power level which is now being delivered (blocks J and K). Thus, when the vacuum cleaner 2 is turned off the memory will contain a record of the last power level which was set (either the upper power level or the lower power level). When the vacuum cleaner 2 is turned on again, the controller retrieves that record from the memory (block L) and delivers the associated power level to the vacuum motor 52 (block M).

[0096] Since in this embodiment the controller 50 delivers either the upper power level or the lower power level straight away, rather than delivering an initial power level, the controller can be considered to be pre-set to supply to the vacuum motor 52 no other power level except the low power level and upper power level.

[0097] That being said, in the third embodiment the behaviour of the controller discussed above only takes place when the controller is in a first mode. The controller 50 also has a second mode which is a min mode, and a third mode which is a max mode. When the controller 50 is in the min mode it supplies to the vacuum motor 52 a constant power level which is below the lower power level (in this case 70 W). Similarly, when the controller 50 is in the max mode it supplies to the vacuum motor 52 a constant power level which is above the upper power level (in this case 190 W). The mode of the controller 50 can be set using a three-position slider switch 58 on the main body 6, an example of which is visible in FIG. 1.

[0098] 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, in a modification of the third embodiment the power level delivered to the vacuum motor 52 when the controller 50 is in min mode may be above the lower power level (for instance 90 W) and/or the power level delivered to the vacuum motor 52 when the controller 50 is in max mode may be below the upper power level (for instance 170 W).