EP2835089B1 - A method of operating a vacuum cleaner for cleaning a from the vacuum cleaner comprised filter element - Google Patents

Description

The invention relates firstly to a method for operating a vacuum cleaner for cleaning a filter element enclosed by the vacuum cleaner during operation of the suction device, wherein a pressure reading of a pressure sensor associated with a volume in which the filter element is located is detected and compared with a threshold value and a downstream of the filter element arranged clean gas valve is opened in response to exceeding the threshold value to the ambient air.

The invention further relates to a vacuum cleaner with a filter element in a volume surrounding the filter element, a clean gas valve which is downstream of the volume comprising the filter element and upstream of the fan, by means of the clean gas valve between an airway in the vacuum cleaner to a blower of the vacuum cleaner and an airway is switchable to the ambient air.

Commercially available household vacuum cleaners comprise in a dust chamber a filter element, on which accumulates dust collected during operation of the vacuum cleaner. Bagless household vacuum cleaners comprise a centrifugal separator and a filter element connected downstream of the centrifugal separator. The filter element stores the emission of the centrifugal separator, namely the dust fraction passing through the centrifugal separator. Both the centrifugal separator and the filter element are located in front of the vacuum cleaner fan. In so-called central filter systems, a special embodiment of a centrifugal separator, the filter element is located as a so-called central filter within the centrifugal separator.

Regardless of the actual design of the vacuum cleaner, the filter element must be freed and cleaned regularly and at relatively short intervals in the course of its use in order to keep the suction power of the vacuum cleaner largely constant.

In a centrifugal separator with a filter element in the form of a central filter, a motor-driven scraper, which is arranged in the interior of the central filter, is used to knock off the dust from the filter folds, as described, for example, in US Pat WO 2011/12479 A is described. However, a disadvantage of this approach for back-cleaning the filter element encompassed by the vacuum cleaner is the mechanical loading of the filter folds by the scraper as a result of the deformation of the filter folds and the comparatively intensive operating noise of the scraper in the form of a "rattle" during the rotation. Furthermore, it is to be regarded as unfavorable that when cleaning the filter, the vacuum cleaner must be turned off and the user may need to interrupt the suction process.

From the DE 10 2010 029 518 A has become known a solution for the purification of a filter element in an industrial vacuum cleaner. The approach described there is based on a reversal of the air flow in the industrial vacuum cleaner, so that in the short term, the filter element is flowed through in a direction normal to the suction flow direction opposite flow direction and thus released on the filter element dust is released. However, this solution is not suitable for household vacuum cleaners, because to reverse the flow direction, a relatively large and acting as a vacuum accumulator volume is required, as is given only in industrial vacuum cleaners with the local large-volume dust chambers. Did you want the approach of DE 10 2010 029 518 A transferred to a household vacuum cleaner with a small volume dust chamber or a household vacuum cleaner with a centrifugal, would result due to the low suitability of the local dust chamber or the inner volume of the centrifugal as vacuum reservoir may still be a very short flow reversal, but in any case no sufficient air flow through the filter element and thus not sufficient Cleaning action for cleaning the respective filter element. The DE 12 45 550 B describes a method for operating a vacuum cleaner for cleaning back a filter element (3) enclosed by the vacuum cleaner during operation of the vacuum cleaner, wherein a pressure reading of a pressure sensor associated with a volume in which the filter element is located is detected and compared with the threshold value, and wherein a downstream of the filter element arranged clean gas valve is opened in response to exceeding the threshold value to the ambient air. Such a method is also known from DE 10 2005 017 568 A1 known.

The invention thus presents the problem, for household vacuum cleaners, in particular for commercially available bagless vacuum cleaners, to provide a solution for the efficient, but at the same time material-saving, cleaning of a filter element encompassed by the respective vacuum cleaner.

This object is achieved with a method for operating a vacuum cleaner and a vacuum cleaner with the features of the independent claims.

In a method according to the invention for operating a vacuum cleaner for re-cleaning a filter element covered by the vacuum cleaner during operation of the condenser, it is provided that a pressure reading of a pressure sensor associated with a volume in which the filter element is located is detected and compared with a threshold value in that a clean gas valve arranged downstream of the filter element is opened as a function of an exceeding of the threshold value to the ambient air.

The volume in which the filter element is located is either the dust chamber of the respective vacuum cleaner or, in the case of a bagless vacuum cleaner with a central filter, the centrifugal separator comprised by such a vacuum cleaner, which is often referred to as a separator in the following. Flow direction information refers, unless otherwise stated, to the normal direction of air flow in the vacuum cleaner during suction operation due to the negative pressure created by the blower of the vacuum cleaner. This also applies to the above position specification of the clean gas valve.

The method for back cleaning of the filter element is therefore based, similar to that in the DE 10 2010 029 518 A described approach, on an at least temporary reversal of the flow of air through the filter element and thus causing "backwashing" of the filter, which causes the dust deposited on the filter element and the filter element thus cleaned (regenerated) is.

In the method, a pressure measured value is detected and compared with a predetermined or predefinable threshold value. The pressure reading shows either a sufficient negative pressure in the volume in which the filter element is located, ie in the dust chamber or in the interior of the separator, or a high degree of contamination of the filter element or both. In the interests of better readability of the following explanations, instead of the term "volume in which the filter element is located", reference will only be made to a separator as an example of such a volume. Other volumes in which the filter element may be located, for example the dust chamber of a vacuum cleaner, are to be read along with each mention of a separator.

If a sufficient negative pressure exists, for example because an aerodynamically dense floor covering is sucked off or because a raw gas supply to the separator is blocked in otherwise suitable manner, the return cleaning of the filter element can be effected by reversing the direction of flow through the filter element. For this purpose, the clean gas valve arranged downstream of the filter element is opened, specifically as a function of an exceeding of the abovementioned threshold value. When the clean gas valve is opened to the ambient air, ambient air is drawn into the separator due to the negative pressure in the separator. This causes the reversal of the air flow through the filter element. The filter element is flushed with ambient air quasi. This filter backwashing releases dust deposited on the filter element and the filter element is regenerated.

Normally, the clean gas valve is designed and arranged so that it blocks the air path to the vacuum cleaner fan when opening to the ambient air. This ensures a complete reversal of the air flow and thus leads to a particularly efficient cleaning of the filter element.

The vacuum cleaner according to the invention, which comprises a filter element in a volume surrounding the filter element, for example in a separator, as well as a clean gas valve and a raw gas valve, is further characterized in that by means of the raw gas valve during suction operation of the vacuum cleaner an influx of raw gas into the Volume / the separator is blockable, wherein the raw gas valve is located upstream of the separator, and that by means of the clean gas valve, an air path in the vacuum cleaner between an airway to a blower of the vacuum cleaner and an air path to the ambient air is switchable, wherein the clean gas valve downstream of the separator and upstream the blower is located.

The vacuum cleaner according to the invention, which comprises a filter element in a volume surrounding the filter element, for example in a separator, as well as a clean gas valve and a pressure sensor is further characterized in that by means of the clean gas valve, an air path in the vacuum cleaner between an airway to a fan the vacuum cleaner and an air path to the ambient air is switchable, wherein the clean gas valve is downstream of the separator and upstream of the blower, and that the clean gas valve in response to a pressure sensor supplied by the pressure sensor is controllable.

In the vacuum cleaner with a clean gas valve and a raw gas valve can be blocked by the raw gas valve, the flow of raw gas into the separator. This ensures sufficient for a filter backwashing of the type outlined above negative pressure in the separator. A measurement of the actual negative pressure by means of a pressure sensor or the like is not necessary, but optionally possible. After blocking the raw gas supply by means of the crude gas valve, the clean gas valve can be opened to the ambient air, in particular in such a way that the air path to the fan is blocked. The negative pressure in the separator causes the flow reversal and the filter rinse.

In the vacuum cleaner with a pressure sensor, a raw gas valve is not necessary, but nevertheless optionally possible. By means of the pressure sensor it is detected whether there is sufficient negative pressure in the separator for a filter rinse. This can result from the fact that a suction nozzle of a floor nozzle of the vacuum cleaner is blocked manually or that an aerodynamically dense floor covering is extracted. The closing of the suction mouth or the dense flooring act like a closed raw gas valve. As soon as there is sufficient negative pressure, the clean gas valve can be activated so that it opens the air path in the vacuum cleaner to the ambient air, in particular in such a way that the air path to the air is released Blower is blocked. The negative pressure in the separator then again causes the flow reversal and the filter rinse.

In the above first variant of the vacuum cleaner, the filter rinse can be triggered manually or automatically. A manual triggering of the filter rinse includes User of the vacuum cleaner first the raw gas valve to block the raw gas supply and to ensure in this way a sufficient negative pressure in the separator. Then, after a short wait, the user opens the clean gas valve, causing backwashing of the filter element. Then the user returns the two valves to their original position. The filter flush can also be triggered automatically. For this purpose, a user actuates, for example, a control element provided for backwashing / regeneration of the filter element. This operator action initiates automatic triggering of the filter rinse by first automatically closing the raw gas valve, then - after a certain predetermined or specifiable waiting time - also automatically opening the clean gas valve to the ambient air to trigger the filter rinse and finally the two valves automatically be put back in their original position. Instead of triggering the automatic filter flushing by means of an operator action of the user or additionally, but independently of such an operator action, the filter flushing can be fully automatic, for example, it is automatically triggered after the lapse of a predetermined or predetermined operating time of the vacuum cleaner.

In the above second variant of the vacuum cleaner, the filter flush is normally triggered automatically, depending on the pressure reading provided by the pressure sensor. The then automatically running process for automatic filter cleaning by reversing the flow direction is the method already described above.

The approach described here and below is especially suitable for household vacuum cleaners, but is in principle suitable for all vacuum cleaner types, including industrial vacuum cleaners. Furthermore, the approach described here is basically also for use in process plants, for example in systems for air extraction or the like, into consideration to clean filter elements used there. In general, the approach described here is especially for equipment or systems, ie in particular for vacuum cleaners and the like, in which the respective filter element acts as a surface filter, because dust and the like does not interfere with such surface filters in depth and thus particularly easy in a flow reversal and dropped efficiently can be. In the case of other filter elements, at least the dust which is also deposited there on the surface can be thrown off.

The advantage of the solution according to the invention is that when used in a vacuum cleaner this is not turned off for the regeneration of the filter element and thus a possible suction process must not be interrupted, that a mechanical load on the filter folds, as they are in a back cleaning by means of one of the filter folds abutting rotating scraper results, is completely avoided and that the re-cleaning process is very quiet overall, because only the switching of a valve or possibly two valves is acoustically effective. The same applies accordingly to other applications of the approach presented here.

Advantageous embodiments and further developments of the invention will become apparent from the following subclaims. Here used backlinks indicate the further development of the subject matter of the main claim by the features of the respective subclaim. They should not be construed as a waiver of obtaining independent, objective protection for the feature combinations of the dependent claims. Furthermore, with a view to an interpretation of the claims in a closer specification of a feature in a subordinate claim, it is to be assumed that such a restriction does not exist in the respective preceding claims.

In one embodiment of the method according to a first variant, when the threshold value is exceeded before opening the clean gas valve, a raw gas valve arranged upstream of the filter element is closed. In this variant of the method, the exceeding of the threshold value due to a corresponding pressure drop across the filter element indicates a high degree of contamination of the filter element. The filter rinse is then initiated by closing the raw gas valve and then opening the clean gas valve to the ambient air for filter rinsing.

In one embodiment of the method according to a second variant, a raw gas valve arranged upstream of the filter element is closed and subsequently the clean gas valve is opened in response to an exceeding of the threshold value to the ambient air. In this variant of the method, the exceeding of the threshold value points to a sufficient negative pressure in the separator due to the blocked by means of the closed raw gas valve influx of raw gas into the separator. As soon as a sufficient negative pressure for the filter rinse is detected, the filter rinse can be initiated by opening the clean gas valve to the ambient air.

In a particular embodiment of the above-outlined method and its variants, the clean gas valve is opened several times in succession for a predetermined period of time when the threshold value is exceeded. The return cleaning of the filter element by filter rinsing then takes place by means of individual purge air pulses. As a result, a swinging back and forth of the filter element or its filter medium is triggered. This leads to an even more efficient discharge of dust attached to the filter element. The filter cleaning and the resulting regeneration of the filter element are particularly effective and efficient in this way.

In one embodiment of the method for cleaning the filter by means of individual scavenging air pulses can be provided that the raw gas valve is closed before the clean gas valve is opened for the first time, and remains closed until the clean gas valve, after this was opened for the last time to the ambient air back into his Starting position is made. Alternatively, the crude gas valve can also be opened and closed in a countercyclical manner in the event of a multiple successive opening of the clean gas valve. Especially in the last variant, the filter medium of the filter element is not only flowed through in multiple alternating directions, but the respective air pressure also causes a multiply changing deformation of the filter medium and thus a particularly effective discharge of attached dust.

As a means for carrying out the method for re-cleaning the filter element as described here and in the following, a control device encompassed by the respective device, that is, for example, a vacuum cleaner, is considered. This comprises, for example, a processing unit in the form of or in the manner of a microprocessor and a memory in which a control program executable by the processing unit is loaded, which when executed by the processing unit realizes all steps of the method. The invention is preferably implemented in software. The invention is thus on the one hand also a control program with by a computer system, namely the control device and its processing unit, executable program code instructions and on the other hand, a storage medium with such a control program, so a computer program product with program code means or other computer-executable instructions that are adapted to in a computer system cause the execution of a method as described here, and finally also a control device in whose memory such a control program is loaded or loadable as means for carrying out the method and its embodiments. As an alternative to an execution of the control program in software, execution in software and hardware, firmware, software and firmware and so forth is also possible, for example by checking that the threshold value is exceeded by the respective pressure measurement by means of a comparator implemented in hardware ,

An embodiment of the invention is shown purely schematically in the drawings and will be described in more detail below. Corresponding objects or elements are provided in all figures with the same reference numerals.

The or each embodiment is not to be understood as limiting the invention. Rather, in the context of the present disclosure, changes and modifications are possible, for example, by combination or modification of individual in combination with the described in the general or specific description part and in the claims and / or the drawings features for the skilled in the art with regard to Solution of the problem can be removed and lead by combinable features to a new object or to new process steps or process steps.

Figur 1

einen Staubsauger in einer Ausführungsform als Bodenstaubsauger,

Figur 2A, 2B

ein Filterelement aus dem Staubsauger in Figur 1 in einer Seitenansicht bzw. einer Draufsicht mit einem drehbaren Abstreifer als Reinigungsaktorik zum Rückreinigen des Filterelements,

Figur 3A, 3B

eine im Stand der Technik bekannte, alternative Möglichkeit zum Rückreinigen eines Filterelements mittels Spülluft,

Figur 4

eine Ausführungsform eines Staubsaugers mit Mitteln zum Rückreinigen eines Filterelements mittels Spülluft gemäß der Erfindung,

Figur 5A, 5B

eine Darstellung zur Veranschaulichung des in Figur 4 gezeigten Prinzips,

Figur 6

eine alternative Ausführungsform eines Staubsaugers mit Mitteln zum Rückreinigen eines Filterelements mittels Spülluft gemäß der Erfindung,

Figur 7

Kennlinien zur Erläuterung des in Figur 6 gezeigten Prinzips sowie

Figur 8A, 8B

eine Darstellung zur Veranschaulichung des in Figur 6 gezeigten Prinzips.

Show it

FIG. 1

a vacuum cleaner in one embodiment as a vacuum cleaner,

FIGS. 2A, 2B

a filter element from the vacuum cleaner in FIG. 1 in a side view and a top view with a rotatable scraper as a cleaning actuator for back cleaning of the filter element,

Figure 3A, 3B

an alternative method known in the prior art for back-cleaning a filter element by means of purging air,

FIG. 4

an embodiment of a vacuum cleaner with means for cleaning back a filter element by means of purging air according to the invention,

Figure 5A, 5B

a representation to illustrate the in FIG. 4 shown principle,

FIG. 6

an alternative embodiment of a vacuum cleaner with means for cleaning back a filter element by means of purging air according to the invention,

FIG. 7

Characteristic curves to explain the in FIG. 6 shown principle as well

FIGS. 8A, 8B

a representation to illustrate the in FIG. 6 shown principle.

The representation in FIG. 1 shows in a simplified schematic representation of a section through a vacuum cleaner 10 in one embodiment as a vacuum cleaner, the following explained new approach for all types of vacuum cleaners 10 comes into consideration and is not limited to vacuum cleaner.

The vacuum cleaner 10 comprises in a conventional manner in a dust chamber 12 a separator 14 with a turn arranged in the separator 14 filter element 16. The filter element 16 is in the illustration in FIG. 1 designed in the form of a filter cartridge and acts in the vacuum cleaner as a central filter. During operation of the vacuum cleaner 10 raw gas 18 is sucked in a manner known per se and the dust 20 contained in the raw gas 18 is mainly deposited on the filter element 16. The necessary flow air is generated in a conventional manner by means of a blower 22 and occurs through a suction hose 24, of which only one for connecting the suction hose 24 provided on the vacuum cleaner 10 connecting piece 24 is shown in the vacuum cleaner 10 a. The purified by means of the filter element 16 raw gas 18 leaves the vacuum cleaner 10 as a clean gas 26 through an optional engine filter 28th

The representation in FIG. 2A shows the filter element 16 FIG. 1 in a simplified schematic, enlarged and sectioned side view. The representation in FIG. 2B shows the same filter element 16 in a simplified and sectional top view. In the illustrations, it can be seen that the filter element 16 comprises a folded / pleated filter medium 30 which can be cleaned by means of a rotatable scraper 32 functioning as a cleaning mechanism, as described, for example, in US Pat WO 2011/12479 A is described. The scraper 32 is usually operated by means of an electric motor (not shown) and set in rotation. For this purpose, the scraper 32 is integrally formed on an axle 34 which is rotatably mounted in a filter cover 36 and a filter bottom 38 of the filter element 16. Due to the folding / pleating of the filter medium 30, this filter folds 40, in which the scraper 32 engages. When turning the scraper 32, the filter folds 40 are deformed and - in analogy to the plucking of a guitar string - vibrated. In this way, on the surface of the filter medium 30 deposited dust 20 (FIG. FIG. 1 ) dropped from the filter folds 40. The deformation of the filter folds 40, however, represents a mechanical load of the filter medium 30, so that long-term damage to the filter medium 30 are not excluded. In addition, we perceived the cleaning of the filter medium 30 by means of a scraper 32 by the user as a sometimes disturbing crackling noise. Finally, the vacuum cleaner 10 must be turned off when the cleaning mechanism is activated, so that the discarded dust 20 is not sucked back to the filter element 16, so that the user must perform appropriate operations and, if necessary, interrupt the suction process.

The illustrations in Figure 3A and Figure 3B illustrate an alternative and also, namely in industrial vacuum cleaners, (for example from the DE 10 2009 029 518 A This approach is based on a supply of scavenging air 44. For this purpose, by means of a purge air opening acting clean gas valve 46, which is downstream of the dust chamber 12, so pure side behind the dust chamber 12, arranged scavenging air 44, so ambient air , supplied against the flow direction of the raw and clean gas 18, 26, to free the filter element 16 from the dust 20.

In principle, this is a filter backwash. In suction operation, in the dust chamber 12, in the suction hose 24 and in a respective attachment (not shown) from the blower 22 ( FIG. 1 ) generated negative pressure. By opening the clean gas valve 46, for example, the dust chamber 12 is purged for a few 100 milliseconds 44 supplied and thereby increases the air pressure in the dust chamber 12. This leads to the fact that the flow reverses abruptly through the filter element 16. The case of industrial vacuum cleaners usually very large dust chamber 12, for example, about 30 liters acts as an accumulator. The larger the accumulator is and the faster the clean gas valve 46 is opened and closed, the more intense is the cleaning of the filter element 16.

However, this approach is not readily apparent to vacuum cleaners 10 in the form of household vacuum cleaners ( FIG. 1 ) Transferable, because the local comparatively small dust chamber 12 with a volume in the order of about 8 to 10 liters is not sufficient to sufficiently suction scavenging air 44 to clean the filter element 16 satisfactorily.

The following illustrations show embodiments according to the invention, wherein a solution is proposed with which even in a vacuum cleaner 10 (FIG. FIG. 1 ) in the form of a household vacuum cleaner, so a canister vacuum cleaner, a vacuum cleaner or a hand or table vacuum cleaner, a cleaning of a covered by the vacuum cleaner 10 filter element 16 can achieve by means of filter rinse.

The representation in FIG. 4 shows in a simplified schematic form the air flow in a vacuum cleaner 10. The flow path begins in the illustration on the far left with the there through the suction hose 24 (FIG. FIG. 1 ) incoming raw gas 18, which enters the separator 14 (or generally in a dust chamber 12) and exits the filter element 16 as a clean gas 26. The vacuum required for this purpose is generated by means of a blower 22 and to that extent is the presentation in FIG. 1 and the explanations made there reference.

At the in FIG. 4 shown vacuum cleaner 10 are located in the flow path two valves, namely a clean gas valve 46 / clean gas valve 46 and a Rohgasseitiges valve 48 / Rohgasventil 48. The raw gas valve 48 is located in the flow path upstream of the separator 14 (or in a vacuum cleaner 10 without separator 14 upstream of the dust chamber The clean gas valve 46 is located in the flow path downstream of the separator 14 (or in a vacuum cleaner 10 without separator 14 downstream of the dust chamber 12), in the embodiment shown immediately downstream of the separator 14. Die Both valves 46, 48 are therefore also fluidly in front of and behind the arranged in the separator 14 filter element 16 or generally in front of and behind the arranged in the dust chamber 12 filter element 16th

The raw gas valve 48 serves to close the flow path leading to the separator 14 / dust chamber 12. The crude gas valve 48 can therefore be designed as a one-way valve. The clean gas valve 46 is designed as a two-way valve and by means of the clean gas valve 46th Either the flow path to the blower 22 or a flow path for introducing purging air 44 into the separator 14 / dust chamber 12 is released. By closing the crude gas-side flow path by means of the crude gas valve 48, the maximum negative pressure of the blower 22 is built up in the separator 14 / dust chamber 12.

The following description will be continued in the interest of better readability based on the illustrated embodiment of a vacuum cleaner 10 with a separator 14. It is understood that in a vacuum cleaner 10 without such a separator 14 functionally takes the place of the separator 14 of the filter element 16 surrounding dust chamber 12. In this respect, the dust space 12 as a possible volume for introducing the scavenging air 44 during backwashing of the filter element 16 is here and below with each mention of the separator 14 read along.

For back cleaning of the filter element 16, the crude gas valve 48 is closed and then briefly or once the clean gas valve 46 is opened, so that due to the negative pressure in the separator 14 purge air 44 flows into the inner volume of the separator 14, namely in the inner volume of the separator 14 is sucked. The scavenging air 44 sucked in the way of the pressure compensation taking place in such a way flows through the filter element 16 in a direction opposite to the flow direction of the raw and clean gases 18, 26, so that a backwashing of the filter element 16 (filter backwashing) is achieved. This filter rinse or filter backwash is also referred to as backwashing the filter element 16. During filter rinsing / cleaning, the dust 20 deposited on the surface of the filter medium 30 of the filter element 16 is discarded. The filter medium 30 is thus regenerated or at least regenerated to a large extent.

The back cleaning of the filter element 16 can also be triggered automatically. For this purpose, between the two valves 48, 46 an otherwise optional analog pressure sensor 50 or a pressure switch 50 is arranged, which detects the respective pressure loss across the filter element 16 as a measure of its degree of contamination.

For automatic re-cleaning of the filter element 16, the following is then provided: Continuously or at least regularly, the negative pressure measured by the pressure sensor 50 is monitored. If a pressure measured value (negative pressure measured value) supplied by the pressure sensor 50 exceeds a predetermined or predefinable threshold value, the raw gas 18 is initially separated from the separator 14 automatically by a corresponding control of the raw gas valve 48. As a result, the maximum fan negative pressure is built up in the separator 14. After a predetermined or predefinable period of time, the lapse of which is awaited after the activation of the raw gas valve 48, for example a time interval in the order of about one second, the purging air 44 is switched on via a corresponding activation of the clean gas valve 46. The connection of the purge air 44 by means of a corresponding control of the clean gas valve 46 also takes place for a predetermined or predefinable period of time (backwash) and possibly several times in succession, between each one control of the clean gas valve 46 for switching on the scavenging air 44 a predetermined or predetermined interval time is awaited. After backwashing the filter element 16, the crude gas valve 48 is automatically opened again by a corresponding control.

The illustrations in FIG. 5A and FIG. 5B show the schematically simplified representation of a vacuum cleaner 10 in FIG. 4 with symbols of electrical engineering. Accordingly, there are the two valves 48, 46 shown as a switch. The method described above, ie the monitoring of the pressure measurement value of the pressure sensor 50, the closing of the raw gas valve 48 when the threshold value is exceeded, the subsequent and possibly multiple short-term opening of the clean gas valve 46 and the final closing of the raw gas valve 48 are controlled by a control device 52 provided for this purpose. This may be a separate control device 52, but also a device provided for controlling and / or monitoring other functions of the vacuum cleaner 10 or a functionality within such a device.

In a multiple backwashing of the filter element 16 by appropriate control of the clean gas valve 46 for switching on the scavenging air 44, the crude gas valve 48 may be permanently closed during the backwashing or each anticyclically with the opening of the clean gas valve 46 for switching on the scavenging air 44 in the meantime each short-term reopened. This is also done automatically by means of a corresponding activation of the valves 48, 46 by means of the control device 52.

The representation in FIG. 5A shows with the valves 48, 46 shown there in the form of switches the situation during normal suction, so if the raw gas 18 via the open Rohgasventil 48 and exiting at the output of the filter element 16 clean gas 26 due to the blower 22 open toward the clean gas valve 46 finally the Stausauger 10 leaves again. The representation in FIG. 5B shows with the there also shown in the form of switches valves 48, 46, the automatic control of the valves 48, 46 by means of the control device 52 due to an evaluated by means of the control device 52 and previously under control of the control device 52 at the pressure sensor 50 detected pressure reading. The control is illustrated by the two block arrows. The switching position shown by the solid lines corresponds to the in FIG. 5A shown situation. The switching position shown with dotted lines is activated during backwashing of the filter element 16.

When displayed in FIG. 5A is still shown that the controller 52, a processing unit 54 in the form of or a kind of microprocessor and a memory 56 includes. Loaded into the memory 56 is a control program 58 executable by the processing unit 54, which, when executed by the processing unit 54, implements all the steps of the respective process for back-cleaning the filter element 16. This detailed representation of the control device 52 is not repeated in the following figures for reasons of clarity, but also applies there. In the memory 56, a measure for a predetermined or specifiable waiting time between a control of the raw gas valve 48 and a (first) control of the clean gas valve 46 is stored, for example, in a designated memory location. The same applies to all other times and parameters that are taken into account in the context of the procedure.

The representation in FIG. 6 shows a specific embodiment of a vacuum cleaner 10 according to the approach proposed here. In this embodiment, there is no raw gas valve 48 (FIG. FIG. 4 . 5A, 5B ) or an existing raw gas valve 48 is not activated. Rather, only the clean gas valve 46 is controlled under control of the control device 52. In this case, its control by means of the control device 52 is carried out automatically and in dependence on a each with a header, for example a floor nozzle 62, vacuumed floor covering 64, 66 and depending on the degree of contamination of the filter element 16. The floor covering 64, 66 and the degree of contamination of the filter element sixteenth are detected by the pressure sensor 50. This is at the in FIG. 6 embodiment shown executed as an absolute value sensor.

The floor covering 64, 66 may be in the form of smooth floor or carpet. Depending on the floor covering 64, 66 and the degree of contamination of the filter element 16 are in an in FIG. 7 shown Systemkennlinienschar Δp = f (q) different operating points P1, P2, P3. The system characteristics Δp = f (q) are plotted against the volume flow q. The operating point designated by P3 symbolizes the suction on a smooth floor with a new or regenerated filter element 16, the operating point designated P1 shows the aerodynamic conditions in carpet and new or cleaned filter element 16 and the operating point denoted by P2 shows the state with saturated / dirty filter element 16 and sucking on carpet. An aerodynamic tightness of a system comprising the one hand, the vacuum cleaner 10 and the other hand, the flooring 64, 66 depends mainly on the aerodynamic tightness of the floor covering 64, 66 from. The dense pile of a carpet thus leads in comparison to a smooth floor to a significantly higher aerodynamic tightness of the entire system. With the respective aerodynamic tightness and the pressure loss and the negative pressure in the system are correlated, so that a higher aerodynamic tightness also results in a higher negative pressure in the system. On the other hand, a higher aerodynamic tightness is accompanied by a correspondingly smaller volume flow q.

In the illustration in FIG. 7 The difference between the pressure values .DELTA.p2 and .DELTA.p1 shown there corresponds to the pressure loss across the filter element 16 in the dirty state and the pressure value .DELTA.p2 to the resulting fan vacuum on a carpet and dirty filter element 16. The operating point designated P2 comes to an operating state as it is at a closed raw gas valve 48 ( Figure 5A, 5B ), very close.

The method according to which the vacuum cleaner 10 in FIG. 6 works to clean the filter element 16, is in FIGS. 8A and 8B shown, with the clean gas valve 46 again (see. FIGS. 5A, 5B ) is shown as a changeover switch to illustrate the switching between the airway to the blower 22 during normal suction operation and the airway for introducing purging air 44 during backwashing of the filter element 16. The switching of the clean gas valve 46 by means of the control device 52 is due to the size Δp2. If it is detected by means of a pressure measurement value supplied by pressure sensor 50 that when cleaning a carpet or an aerodynamically very dense floor covering a threshold determined by the size .DELTA.p2 is reached or exceeded, the clean gas valve 46 is opened by appropriate control by means of the control device 52. Then purge air 44 flows into the separator 14 and by the thus effected backwashing of the filter element 16, this is regenerated.

The representation in Figure 8A shows a situation with raised floor nozzle 62. In this situation, there can not normally be any exceeding of the above threshold. The representation in FIG. 8B shows at the same floor covering 66, namely an aerodynamically dense floor covering 66, for example, carpet floor, the situation with lying on the floor covering 66 floor nozzle 62. Due to the aerodynamic tightness of the floor covering 66 acts as a closing of the suction mouth of the floor nozzle 62, so ultimately as a closing a valve (see above: raw gas valve 48; FIG. 4 ) in the air path to the filter element 16 and the volume flow q to the filter element 16 collapses. In the separator 14 so that after a very short time the maximum negative pressure of the blower 22 is established. In this situation, under control of the control device 52, the clean gas valve 46 is controlled so that it opens to the ambient air and allows the influx of purging air 44, the negative pressure in the separator 14 is compensated by the inflowing scavenging air 44 while the filter element 16 as above already described by backwashing.

Some prominent aspects of the description presented here can thus be briefly summarized as follows: A method for operating a vacuum cleaner 10 for back cleaning a filter element 16 enclosed by the vacuum cleaner 10 during operation of the suction hood 10, wherein a pressure measurement value of a volume 12, 14 in which the filter element 16 is located, associated pressure sensor 50 is detected and compared with a threshold and wherein a downstream of the filter element 16 arranged clean gas valve 46 is opened in response to exceeding the threshold value to the ambient air, and a corresponding vacuum cleaner 10th

LIST OF REFERENCE NUMBERS

10

vacuum cleaner

12

dust chamber

14

Centrifugal separator / separator

16

filter element

18

raw gas

20

dust

22

fan

24

suction

26

clean gas

28

motor filter

30

filter media

32

scraper

34

stripper shaft

36

filter cover

38

filter bottom

40

filter pleats

44

purge air

46

Clean gas valve

48

Rohgasventil

50

Pressure sensor (or pressure switch)

52

control device

54

processing unit

56

Storage

58

control program

62

floor nozzle

64

Flooring

66

Flooring

P1

Working point filter element in new condition / carpet

P2

Working point filter element dirty / carpet floor

P3

Working point filter element when new / smooth bottom

Claims (11)

1. Method for operating a vacuum cleaner (10) for back-cleaning a filter element (16) comprised by the vacuum cleaner (10) during operation of the vacuum cleaner (10),
   a pressure measurement value of a pressure sensor (50) that is associated with a volume (12, 14) in which the filter element (16) is located being detected and compared with a threshold value, and a clean gas valve (46) arranged downstream of the filter element (16) being opened to ambient air if the threshold value is exceeded, characterised in that
   a crude gas valve (48) arranged upstream of the filter element (16) is closed and subsequently the clean gas valve (46) being opened to ambient air if the threshold value is exceeded.
2. Method according to claim 1, wherein if the threshold value is exceeded before the clean gas valve (46) is opened, a crude gas valve (48) arranged upstream of the filter element (16) is closed.
3. Method according to either claim 1 or claim 2, wherein the clean gas valve (46) is opened several times in succession for a predetermined time period in each case if the threshold value is exceeded.
4. Method according to any of claims 1, 2 or 3, wherein the crude gas valve (48) is closed before the clean gas valve (46) is opened the first time, and remains closed until the clean gas valve (46) is reclosed, after said clean gas valve has been opened for the last time.
5. Method according to claim 2, wherein when the clean gas valve (46) is opened several times in succession, the crude gas valve (48) is also opened and closed in an anti-cyclical manner.
6. Vacuum cleaner (10) comprising a filter element (16) in a volume (12, 14) surrounding the filter element (16) and a clean gas valve (46) which is located downstream of the volume (12, 14) comprising the filter element (16) and upstream of the fan (22), it being possible to switch, by means of the clean gas valve (46), between an air path in the vacuum cleaner (10) to a fan (22) of the vacuum cleaner (10) and an air path to ambient air,
   characterised by
   a crude gas valve (48), it being possible to block, by means of the crude gas valve (48), an inflow of crude gas (18) into the volume (12, 14) during suction operation of the vacuum cleaner (10), the crude gas valve (48) being located upstream of the volume (12, 14) surrounding the filter element (16).
7. Vacuum cleaner (10) according to claim 6 comprising a pressure sensor (50), wherein the clean gas valve (46) can be actuated on the basis of a pressure measurement value provided by the pressure sensor (50).
8. Vacuum cleaner (10) according to claim 6 comprising a pressure sensor (50), wherein the clean gas valve (46) and the crude gas valve (48) can be actuated on the basis of a pressure measurement value provided by the pressure sensor (50).
9. Vacuum cleaner (10) according to claim 8 comprising means (46, 48, 50, 52) for carrying out a method according to any of claims 1 to 5.
10. Vacuum cleaner (10) according to claim 9 comprising a control means (52) as one of the means for carrying out the method according to any of claims 1 to 5, wherein the control means (52) comprises a control program (58) in a memory (56), which control program implements all the steps of the method according to any of claims 1 to 6 when said control program is executed, and
    wherein a measurement for a predetermined or predeterminable waiting time between the crude gas valve (48) being actuated and the clean gas valve (46) being actuated is stored in the memory (56) in a first memory location.
11. Vacuum cleaner (10) according to claim 10, wherein in the memory (56), a numerical value for a predetermined or predeterminable number of successive switching processes of the clean gas valve (46) is stored in a second memory location, a measurement for a predetermined or predeterminable duration of opening of the clean gas valve (46) to ambient air is stored in a third memory location, and a measurement for a predetermined or predeterminable waiting time between two switching processes of the clean gas valve (46) is stored in a fourth memory location.

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