DE3918237A1 - Electric vacuum cleaner with fine dust filter - uses several filter stages in series each utilising replaceable filter element - Google Patents

Abstract

The dust filter is inserted in the path of the discharged air from the vacuum cleaner fan and uses a number of individual filter stages (11a...11c) in series each of which uses a replacable filter element e.g. an electrostatic filter mat. Pref. the filter stages (11a...11c) are arranged in a cyclic sequence within a filter cassette, allowing the leading filter element (11a) nearest to the fan to be removed with a replacement filter element (11a') fitted behind the rearmost filter element (11c). A sensor may be incorporated for indicating when the filter replacement is necessary. ADVANTAGE - Allows removal of dust particles in micrometre range.

Description

The object of the invention relates to a vacuum cleaner with a fine dust filter in the exhaust air flow of the engine blows, the fine dust filter in a filter cassette or the like. is arranged interchangeably.

In a known vacuum cleaner (DE-GM 87 08 240) that is secondary filter made of electret filter material covered under a removable or swiveling housing cover exchangeable in an assigned filter cassette arranged. In addition to the purely mechanical filter effect this post-filter has an electrostatic filter effect given by the particularly fine dust in the size range is detected by 1 µm without excessive air resistance reduce the effectiveness of the vacuum cleaner. The known Post-filter, however, does not have an optimal filter effect for respirable fine dust particles in the area below 1 µm. However, such a filter effect is special for allergic to house dust or pollen People very important.

The invention is based, with little cost, the task the filter effect of the fine dust filter was the same consistently good service and user friendliness to optimize a filter change.

The task is given with a generic dust Sucker solved by the features of claim 1.

Advantageous refinements emerge from the subclaims forth.  

By connecting several identical filters in series becomes a significant increase in the filter effect of the finest dust filter possible in the range below 1 µm. The rear Changing the same filter mats causes an extension the duration of the fine dust particles in the filter medium and thus also an improved separation, whereby especially when using the electret filter mats as a single filter which is also between the same individual filter building electrical fields in the sense of a more closely meshed filters. They also gather at the series connection different dust fractions in the Sequence of flow through the individual filters. It is sufficient for example, that after a certain operating time only the first individual filter lying in the flow direction removed and behind the last single filter, which on is least loaded, a new individual filter in the Row is inserted. This ensures that how So far, only a single filter mat has to be replaced.

The following description serves to explain the Object according to the invention, of which an execution example is shown graphically. It shows:

. 1 in partial section of a vacuum cleaner in a perspective view with open dust chamber cover at which a micro-filter as a post filter for the exhaust air of the suction fan is arranged in Fig of a filter cartridge,

Figs. 2 and 3 are each a schematic representation of the composite of several individual filters as a multiple filter fine dust postfilter.

For the installation of the post-filter selected in Fig. 1, a cylinder vacuum cleaner ( 1 ) has been used, which is shown in the cut-out in part and has a housing ( 2 ) which is accessible in a dust collecting chamber ( 4 ) accessible via a housing cover ( 3 ) and a downstream one Blower room ( 5 ) is divided.

In the dust collecting chamber ( 4 ) a dust filter bag ( 6 ) is inserted, which, when the housing cover is closed, is connected in a known manner with a plug-in connection for a suction hose leading to the dust collecting chamber ( 4 ) and on the housing cover ( 3 ), not shown. The housing cover ( 3 ) for the dust collecting space ( 4 ) covers part of the blower chamber housing, which in the covered housing part ( 7 ) has a plurality of air outlet openings ( 8 ) designed to discharge the exhaust air of the vacuum cleaner ( 7 ). The blowout grille ( 8 ) connected to the blower compartment housing is combined with a foldable exhaust air grille ( 9 ) and forms with this a filter cassette ( 10 ) for receiving a fine dust filter ( 11 ), which serves as an exhaust air filter for the exhaust air flow from the engine fan. The foldable exhaust grille ( 9 ) is designed as a lockable cassette cover.

The aforementioned fine dust filter ( 11 ), as also schematically illustrated in FIGS. 2 and 3, is designed as a multiple filter with the same individual filters ( 11 a , 11 b , 11 c ) connected in series, which are preferably cyclically exchangeable in the filter cassette ( 10 ) are kept. At least two, but advantageously three separate individual filters ( 11 a to 11 c ) form the multiple filter. The individual filters ( 11 a to 11 c ) consist of electrostatic filter mats made of electret filter material and each belong to the same filter class. The effect of each individual filter mat is such that fine dust in the size range around 1 µm is retained from the exhaust air flow from the suction fan. In the interaction of the three same individual filters, however, fine dust of less than 1 µm is also retained, since on the one hand a longer dwell time of the fine dust is achieved in the filter medium and on the other hand electrostatic fields also build up between the individual filters which retain this fine dust.

The multiple filters are connected in series filter even finer mesh (mechanical filter effect) and enhanced in its electrostatic effect (electro static filter effect).

As already mentioned, the individual filters are placed one above the other in a cyclical, interchangeable sequence in the filter cassette ( 10 ), with the individual filter ( 11 a ) located below in the flow direction (see arrow) of the exhaust air flow being removed after a certain operating time, starting from FIG. 2 and for this a new single filter ( 11 a ′) is placed behind the last single filter ( 11 c ). This results in the arrangement shown in FIG. 3 after the filter replacement. Later, when the filter is changed again, the single filter ( 11 b ) must be removed, after which a new filter ( 11 b ′) must be inserted behind the previously inserted single filter ( 11 a ′) in the multiple filter block, etc.

Deviating from the preferred replacement sequence of the individual filters ( 11 a to 11 c ), the filter exchange can of course also take place in such a way that, for example, the entire filter package or the multiple filter is replaced after a certain operating time of the vacuum cleaner. With three individual filters for the multiple filter, two individual filters can also be replaced. The individual filters can be inserted and removed in a simple manner using the hinged filter cassette. The figure shows how, for example, the lower individual filter ( 11 a ) is removed and then a new individual filter ( 11 a ') is placed on top of the filter package.

As an indicator for the filter change, e.g. that in itself known differential pressure methods are used, where the flow pressure before and after the multiple filter is scanned and evaluated. For example, a sensed increased differential pressure, so the request is made  "Filter change" or the display "Filter dirty" via a signal device assigned to the vacuum cleaner. If the differential pressure is equal to or approximately zero, then can use this as an error indicator for the absence of the multiple filters or a single filter and used for display to be brought. In this case, the surveillance also prevent the vacuum cleaner from starting.

Claims (5)

1. Vacuum cleaner with a fine dust filter in the exhaust air flow from the engine fan, the fine dust filter being arranged interchangeably in a filter cassette or the like, characterized in that the fine dust filter ( 11 ) as a multiple filter with the same exchangeable individual filters ( 11 a to 11 c ; 11 a , to 11 c ') is formed in series connection. 2. Vacuum cleaner according to claim 1, characterized in that at least two separate individual filters form the multiple filter ( 11 ) and consist of electrostatic filter mats. 3. Vacuum cleaner according to claim 1 and 2, characterized in that the individual filters ( 11 a to 11 c ) are arranged in a cyclically interchangeable sequence in the filter cartridge ( 10 ). 4. Vacuum cleaner according to claim 1 and 3, characterized in that preferably three individual filters ( 11 a to 11 c ) are easily seen, the first individual filter ( 11 a ) located in the flow direction of the exhaust air stream being removed and a new individual filter ( 11 a ') is placed behind the last single filter ( 11 c ) of the multiple filter ( 11 ). 5. Vacuum cleaner according to one or more of claims 1 to 4, characterized in that the vacuum cleaner ( 1 ) has a preferably based on the differential pressure principle control device for sensing and displaying a filter change and / or for reporting a missing filter.