CA2244544A1 - A detection means for filter means in vacuum cleaners - Google Patents

Abstract

A detection means for filter means in vacuum cleaners, into which in addition to a vacuum cleaner bag at least one additional filter is able to be inserted. It comprises a sensor means responsive to the filter means inserted into said vacuum cleaner and switch means controlled by said sensor means for preventing switching of the vacuum cleaner motor if said filter means is not correctly recognized. The at least one electronic sensor means responsive to a detectable element in or on at least one additional filter by means of electromagnetic waves is connected with the switching means via an evaluating or processing means, adapted to check the correct position and design of the at least one detectable element. This renders possible not only the checking of the presence of an additional filter in the vacuum cleaner but furthermore its right placement and the right design for the respective vacuum cleaner so that impairment of and damage to the vacuum cleaner due to fitting the wrong additional filter may be avoided.

Description

CA 02244~44 l998-08-04 --A DETECTION MEANS FOR A FILTER MEANS
IN VACUUM CLEANERS--The invention relates to a detection means for filter means in vacuum cleaners, into which in addition to a vacuum cleaner bag at least one additional filter is able to be inserted, comprising a sensor means responsive to the filter means inserted into said vacuum cleaner and switch means controlled by said sensor means for preventing switching on of the vacuum cleaner motor if said filter means is not correctly recognized.
The German patent publication 2,603,110, the German patent publication 3,434,209 and the US patent 2,839,156 each disclose such a detection means, in the case of which the connection member of the vacuum cleaner bag inserted into the vacuum cleaner actuates a switch so that in this manner the presence of the vacuum cleaner bag is recognized. It is only when the switch is actuated that the vacuum cleaner motor can be switched on. Furthermore the German patent publication 2,655,547, the British patent publication 1,440,174 and the US patent 4,184,225 disclose pneumatic arrangements in the case of which the presence of the vacuum cleaner bag is detected pneumatically and in the case of which it is only in the case of detection of a vacuum cleaner bag that switching on of the vacuum cleaner motor is possible.
Although the known detection means do render it possible to prevent switching on of the motor when the filter bag is not inserted, there is however the danger of the wrong additional filter being inserted leading to the likelihood of operational failure occurring.
One object of the invention is to provide a detection means of the type initially mentioned by means of which not only switching on of the vacuum cleaner without an additional filter being fitted but also switching on with the wrong or a CA 02244~44 1998-08-04 wrongly inserted additional vacuum cleaner bag may be effectively prevented.
In order to achieve these and/or other objects appearing from the present specification, claims and drawings, in the present invention the at least one electronic sensor means responsive to a detectable element in or on at least one additional filter by means of electromagnetic waves is connected with the switching means via an evaluating or processing means, adapted to check the correct position and design of the at least one detectable element.
The detection means of the invention means that switching on of the vacuum cleaner is reliably prevented with the wrong additional filter, even if such inserted wrong additional filter possesses a shape, which corresponds to that of the correct additional filter. If an unsuitable additional filter of less good quality or one unable to fit properly owing to it having the wrong dimensions while happening to possess the same geometry is used, such additional filter, which for instance is a micro-filter, cannot fulfill and comply with the promised performance in the case of an overly coarse filtering action, something likely to lead to complaints and customer dissatisfaction.
Furthermore insufficient passage of dust through an over~y dense, incorrect additional filter may lead to an impairment of the vacuum cleaner's performance or even to damage to the vacuum cleaner motor. With the detection means in accordance with the invention it is possible for the correct additional filter to be reliably detected or recognized so that optimum operation as a vacuum cleaner is maintained and disadvantages through having overly large or small pores in the filter are avoided. In addition such detection means can reliably detect a wrongly inserted additional filter or the absence of a filter. Furthermore as regards the ever increasing requirements of product liability the detection means in accordance with the invention turns out to be extremely CA 02244~44 1998-08-04 advantageous.
Further advantageous developments of the invention are defined in the claims.
It is convenient for the sensor means to also be designed to additionally be responsive to a detectable element in or on the vacuum cleaner bag or of the plate-like connection member and to check the correct position and design of the same. As a result the protective means of the vacuum cleaner and the guarantee of reliable operation is still further improved.
Owing to the provision of at least the sensor means and the evaluating means and preferably furthermore of the switching means in the form of a structural unit on at least one printed circuit board and/or the design in the form of an integrated circuit the detection means of the invention can be produced without structural changes being necessary to depart from the design of conventional vacuum cleaners or, respectively, vacuum cleaner housings. The structural unit can in a simple and economic manner be arranged in or on a wall of the vacuum cleaner housing operatively adjacent to the at least one detectable element, the wall provided with the structural unit of the vacuum cleaner housing being arranged essentially directly adjacent to the at least one detectable element.
For producing the electromagnetic waves the sensor means advantageously possesses at least one transmitter more particularly having an oscillating circuit, the sensor signals being formed owing to the return action of the detectable element on the transmitter and/or the electromagnetic waves. In this manner the sensor means will react extremely reliably to the configuration and design of the sensor element so that the additional filter having such detectable element, or, respectively, the connection member designed in this manner, in the respective vacuum cleaner bag may be reliably recognized.

CA 02244~44 1998-08-04 In accordance with a first and extremely advantageous embodiment the detectable element is designed in the form of a metallic sheet element and more especially as a metal plate or foil or layer, and the sensor signals are formed in a manner dependent on the eddy current damping of the transmitter. The provision of such a metallic sheet element on or in the additional filter and if required the connection member as well, may in this case be performed extremely economically, variations in the respective area and the respective configuration being possible in a simple manner.
Eor evaluation the detectable element in the evaluating means is set for a certain amplitude of the oscillation of the oscillating circuit, the threshold value stage being provided for recognition in the evaluating means, such stage receiving a signal derived from the amplitude of the oscillation of the oscillating circuit, switching on of the vacuum cleaner motor being prevented above an adjustable first threshold value. Therefore as from a certain area of the detectable element, that is to say as from a certain degree of damping the prevention of switching on is overridden.
Even more reliable recognition of the correct additional filter or, respectively, vacuum cleaner bag is achieved if additionally below a second adjustable lower threshold value the switching of the vacuum cleaner motor is prevented. This means that, for instance, an additional filter, which may be coated with a metallic foil, or comprises metallic components, cannot be recognized as being correct.
In another advantageous embodiment the detectable element possesses means for return transmission of signals which represent a modified form of the receive electromagnetic waves, the sensor means possessing aa suitable receiving means. This means that there is an even greater degree of reliability of recognition. The modified signals may in this case have a changed frequency and/or CA 02244~44 1998-08-04 phase relationship or they may comprise a signal code. In the evaluating means corresponding recognition means are provided for returned signals modified in a predetermined manner.
Such a detectable element, which involves sophisticated and advanced technology, is preferably designed in the form of a micro-chip, which may for instance be readily arranged between different layers of the additional for the purpose of or, respectively, connection member and is able to be manufactured on a mass scale relatively economically.
In a further alternative design in accordance with the invention the transmitter may be designed in the form of a light transmitter and the detectable element can be an element adapted to return the light to a light receiver in the sensor means. As a detectable element a barcode element or a deflecting element adapted to return the light unchanged at a particular position in the sensor means is suitable.
As a further advantageous design it is possible for capacitive detection of the detectable element may be provided for.
In order to more particularly in the case of extremely simple designs of detectable elements (as for instance metallic sheet elements) to ensure extremely reliable recognition of the correct additional filter or furthermore the connection member or, respectively, filter bag, a plurality of detectable elements are arranged on or in the at least one additional filter and preferably also additionally on or in the connection member and/or the vacuum cleaner bag and are able to be sensed by a corresponding number of sensor part means of the sensor means.
The at least one additional filter is preferably a micro-filter and/or a filter cassette and/or an active carbon filter and/or combined filter as a combination of the above mentioned filters. In this respect only one additional filter or furthermore a plurality of different additional filters may be provided.

CA 02244~44 1998-08-04 Further advantageous developments and convenient forms of the invention will be understood from the following detailed descriptive disclosure of embodiments thereof in conjunction with the accompanying drawings.
Figure 1 is a simplified sectional view of an additional filter arranged on part of the housing of a vacuum cleaner.
Figure 2 is a corresponding representation of a filter bag.
Figure 3 shows a block circuit diagram of a first embodiment with a detectable element in the form of a metallic sheet element.
Figure 4 shows an arrangement of such various different detectable elements on a connection member of an additional filter in plan view.
Figure 5 is a block circuit diagram of a second embodiment of the invention, in the case of which the detectable element returns the received electromagnetic waves back in a modified form.
The detectable 1 illustrated diagrammatically in figure 1 is for example a micro-filter and comprises a plate-like filter body of a plastic fiber batt, plastic fiber fabric or some other filter material. As plastics it is possible to employ for instance polypropylene or polyester.
On a wall 2 illustrated in part of the vacuum cleaner a grid-like opening 3 is provided, which is covered over by the additional filter 1. For this purpose the wall 2 possesses a recess corresponding to the shape of the additional filter 1, in which the additional filter 1 is held by lugs 4. It is possible for the flexible additional filter 1 to be inserted in these lugs 4. It is possible for other methods of CA 02244~44 1998-08-04 attachment such as using elastic clips, pinching means, screw attachment means, pivoting attachment means or the like to be employed.
The air drawn in body vacuum cleaner firstly flows in a known manner into a vacuum cleaner bag 10, as is for example illustrated in figure 2. Here the coarse dust will remain and the filtered air will leave the vacuum cleaner housing through suitable ducts, not illustrated, to the outside.
During such passage it flows through the additional filter 11 in the form of a micro-filter, by which fine impurities, such as spores, germs, pollen and the like are retained to ensure that when the air is returned from the vacuum cleaner it will not cause any allergies or present any other danger to health.
On the edge part of the additional filter 1 metallic foil is placed as a detectable element 5. Instead of a metallic foil it is possible also to provide a metal plate or a metallized layer. On the side of the wall 2 opposite to the additional filter 1 a printed circuit board 6 is arranged adjacent to the detectable element 5, on which printed circuit board an electronic circuit is arranged for detection of the detectable element 5, such circuit being illustrated in figures 3 and 5 for instance and described with reference thereto. The detectable element 5 can more particularly in the case of a multiple layer design of the additional filter 1 be arranged between the layers, that is to say in the interior of the additional filter 1 as well and is then on the one hand protected and on the other hand not able to be seen from the outside.
Instead of a micro-filter as an additional filter 1 it is also possible for example to employ an active carbon filter or filter cassette, which contains a folded, lamella-like material and for example is in the form of an S-class filter. All such filters may be accommodated in board or plastic frames or in board or plastic housings, to which they CA 02244~44 1998-08-04 are bonded for example. It is also possible to employ combination filters, that is to say for instance a filter cassette with an integrated active carbon filter or a combined micro-filter with an active carbon filter. The detectable element can then be arranged on the filter material itself or on the frame or housing.
Furthermore it is possible to arrange a plurality of such additional filters in tandem.
The vacuum cleaner bag illustrated in 2 diagrammatically comprises the vacuum cleaner bag 10 in the strict sense, whose wall is manufactured of a material which allows the passage of air but retains dust, and a connection member 11, which is attached preferably by bonding to part of the vacuum cleaner bag 10 having an inlet opening as such.
On a wall 12, illustrated in part of a figure, of the vacuum cleaner, for which the vacuum cleaner bag is intended, a bag mounting spout 13 is provided extending into a receiving space for the vacuum cleaner bag, the connection member 11 being slipped over such spout on insertion of the vacuum cleaner bag into the vacuum cleaner so that the connection spout 13 extends through a mounting opening 14 formed in the connection member 11 and extends into the interior of the vacuum cleaner bag. In this manner it is possible for the air drawn in by the vacuum cleaner to pass into the vacuum cleaner bag, in which the dust filtered out of the air by the vacuum cleaner bag wall is retained.
The connection 11 is essentially in the form of a plate and consists of board-like, stiff material. A conventionally present closure slide and a diaphragm seal, conventionally surrounding the mounting opening 14 are not illustrated in order to make the drawing more straightforward and in the case of customary vacuum cleaner bags will not be present anyway. If a closure slide is present the connection member 11 will conventionally have several board layers or plies, as is for instance described and illustrated in German patent CA 02244~44 1998-08-04 publication 4,339,298.
For attachment of the connection member 11 on the wall 12 same possesses a holding rail 15 provided with a receiving groove for an edge part of the connection member 11, such rail being able to be replaced by two suitably shaped holding elements. On the opposite side a detent projection 16 extends through a detent opening 17 on putting the connection member 11 in place and locks the connection member 11. For this purpose it is for instance possible also to have two detent projections 16 and two detent openings 17. In other respects the type of attachment is hardly of any importance for the present invention and may for instance be in accordance with the German patent publication 4,339,297 or other prior art.
On part of the connection member 11 a metallic foil is arranged as a detectable element 18. On the side of the wall 12, which is opposite to the connection member 11 a printed circuit board 19 is arranged operatively adjacent to the detectable element 18 as illustrated in figure 1 and on such printed circuit board an electronic circuit is arranged for detection of the detectable element 18. In this respect attention is also called to the explanations on figure 1.
In the case of the working embodiment depicted in figure 3 as a block circuit diagram the oscillating circuit arrangement 20 is provided for producing electromagnetic waves and it is connected via rectifying arrangement 21 with a comparator arrangement 22, via which a triac 23 in the power circuit of a vacuum cleaner 24 may be controlled.
The manner of operation is such that the oscillating circuit excited by an excitation switch, not illustrated, of the oscillating circuit arrangement 20 transmits electromagnetic waves to the outside. The alternating current signals, produced owing to the oscillations in the electronic circuit are rectified in the rectifier arrangement 21 so that a signal will be present at its output, which is dependent on the amplitude of the oscillations. In the comparator .

CA 02244~44 1998-08-04 arrangement 20 comprising two comparators a check is performed to see whether this signal is smaller than its first threshold value Sl and is simultaneously larger than a second, lower threshold value S2. It is only when these two conditions are fulfilled that the triac becomes is turned on so that the vacuum cleaner motor 24 may be turned by means of a manual switch, not illustrated. The first threshold value S1 is in this respect so set that the output signal of the rectifier arrangement 21 is higher in undamped operation of the oscillating circuit 20 so that the triac 23 is turned off.
If now the additional filter as shown in figure 1 or the vacuum cleaner bag in accordance with for the 2 is inserted into the vacuum cleaner in the proper fashion, the detectable element 5 or, respectively, 18 will come moved to be operatively adjacent to of the oscillating circuit arrangement 20 and owing to voltages induced in the detectable element 5 or, respectively, 18 eddy currents are produced thereby, which abstract energy from the oscillating circuit and cause damping thereof. The amplitude of oscillation is accordingly reduced so that the output signal of the rectifying arrangement 21 is reduced. The two threshold values S1 and S2 are so set that the damping of the oscillating circuit 20 produced by the detectable element 5 or, respectively, 18 in the correctly mounted state of the additional filter 1 or, respectively, connection member 11 is just sufficient to reduce the output signal of the rectifier arrangement 21 below the upper threshold value S1 but however not below the lower threshold value S2 so that the condition intended is fulfilled and the triac 23 is turned on so that the vacuum cleaner motor 24 may be turned on or operated. In the case of the additional filter 1 being the wrong type or in the case of a connection member 11 without a detectable element 5 or, respectively, 18 or with a detectable element having a smaller area the threshold value S1 the threshold CA 02244~44 1998-08-04 value S; would not be gone below and the vacuum cleaner could not be operated. If on the other hand the wrong additional filter (or connection member) having an oversize detectable element were to be employed then owing to the greater damping the threshold value Sz would also be gone below so that the vacuum cleaner could again not be operated. It is only an additional filter 1 fitted with the right additional filter 5 that consequently permits operation of the vacuum cleaner.
The same will apply for the connection member 11 and the detectable element 5 to the extent here as well a corresponding detection means is provided.
In the case of a simpler design the comparator arrangement 22 could also have but one comparator so that checking would merely be to see whether a detectable element 5 or, respectively, 18 with a certain minimum size is comprised in or on the additional filter 1 or connection member 11. Instead of a triac 23 it would also be possible to employ any other known electrical or electronic switch.
In figure 4 the connection member 11 is represented in a diagrammatic plan view. In order to render possible even more reliable recognition of the right vacuum cleaner bag 10 or, respectively, the right connection member 11, on or in this connection member 11 four different detectable elements 25 through 28 are arranged; three detectable elements 25 through 27 in a rectangular form with different areas and one detectable element 28 in the form of a double strip. Assuming that the connection member 11 has been correctly inserted, four oscillating arrangements on the printed circuit board 19 will be opposite to these detectable elements 25 through 28 in a suitable arrangement, such arrangements scanning or checking the respective detectable elements 25 through 28. A
fifth oscillating circuit arrangement 33 is not opposite to any detectable element. Each of the oscillating circuit arrangements 29 through 33 is accordingly damped in a particular fashion, the oscillating circuit arrangement 33 CA 02244~44 1998-08-04 not being damped. This is checked in the comparator arrangement which is not illustrated and if in all cases the intended damping values are found, the triac 23 will be turned on. The number and arrangement of the detectable elements and oscillating circuit arrangements may naturally be modified to an unlimited extent.
An arrangement as in figure 4 may be arranged at one or, if present, more additional filters 1, for instance on the frame or housing of an additional filter as well. The manner of operation is explained with reference to figure 4.
In the case of the circuit, represented as a further working embodiment in figure 5, for checking for the right additional filter or vacuum cleaner bag or, respectively, connection member a sensor means comprises a transmitter 34 and a receiver 35 for electromagnetic waves. A detectable element 36 to be put on the additional filter 1, is in the form of a micro-chip and also comprises receiver 37 and a transmitter 38 for electromagnetic waves. In addition there is a power supply means 39 for the receiver 37 and the transmitter 38, which is either in the form of a battery or is connected with the oscillating circuit of the receiver 37 and obtains the supply power from the RF energy received in the oscillating circuit, as is disclosed for example in the German patent publication 4,110,683.
In the receiver 37 or in the transmitter 38 a converter is comprised by which the received signal is changed. This changed signal is then transmitted back by the transmitter 38 of the detectable element 36 to the receiver 35 of the detectable sensor means. Conversion may for instance be performed by changing the frequency or the phase relationship of the RF signal. As an alternative to this it is also possible for the re-transmitted signal to be modulated in a predetermined fashion so that a certain coder is transmitted to the receiver 35 of the sensor means. The signal received in the received 35 iS then checked in a decoder 40 to see CA 02244~44 1998-08-04 whether the intended information of the detectable element 36 is contained in it. If this is the case the decoder 40 will turn on the triac 23. Further possibilities of encoding the signal and re-transmission by detectable elements 36 in the form of micro-chips are disclosed in the said German patent publication 4,110,683.
A further alternative possibility is one in which the transmitter for electromagnetic waves is designed in the form of a light transmitter and the receiver for electromagnetic waves in the form of a light receiver. As a detectable element it is then possible to have a barcode or another means, which shines back the light in a changed or unchanged form to the light receiver of the sensor means. For instance a deflecting element in the detectable element a light guide may be provided, which guides back the light received at one point from the sensor means to an another point to the additional filter or, respectively, connection member, on which the light receiver is arranged.
A further alternative arrangement is one using capacitive detection of the detectable element. In this case it is possible again for the detectable element to be in the form of a conductive plate or, respectively, metallic sheet element, which constitutes a part of a capacitor of a measuring oscillating circuit.
The circuits illustrated in figures 3 and 5 as embodiments, which comprise sensor means and evaluating means, may be comprised on the printed circuit board 6 or, respectively, 19 as integrated or non-integrated circuit. In this respect it is for example also possible to design the entire circuit completely or partially in the form of an integrated circuit or in the case of there being a plurality of detectable elements at different points a plurality of printed circuit boards or other sensor means may be provided.
As a modification of figure 2 it is also possible for a detectable element or a plurality of detectable elements to CA 02244~44 1998-08-04 be placed on the vacuum cleaner bag 10 as such , which during operation normally lies against the surface of the walls of a vacuum cleaner bag space in the vacuum cleaner. Then the printed circuit board 19 and/or an integrated sensor and evaluating circuit may then be arranged on such walls. It is also possible to employ combined designs, in the case of which some detectable elements are provided on the vacuum cleaner bag 10 as such and some are arranged on the connection member 11. This is also possible for additional filters.

Claims (20)

1. A detection means for filter means in vacuum cleaners, into which in addition to a vacuum cleaner bag at least one additional filter is able to be inserted, comprising a sensor means responsive to the filter means inserted into said vacuum cleaner and switch means controlled by said sensor means for preventing switching on of the vacuum cleaner motor if said filter means is not correctly recognized, wherein the at least one electronic sensor means responsive to a detectable element in or on at least one additional filter by means of electromagnetic waves is connected with the switching means via an evaluating or processing means, adapted to check the correct position and design of the at least one detectable element.

2. The detection means as set forth in claim 1, wherein the sensor means is additionally designed to be responsive to a detectable element in or on the vacuum cleaner bag or its plate-like connection member and for checking the right position and design of the same.

3. The detection means as set forth in claim 1, wherein at least the sensor means and the evaluating means and preferably furthermore the switch means are in the form of one structural unit on at least one printed circuit board and/or are in the form of an integrated circuit.

4. The detection means as set forth in claim 3, wherein the structural unit is arranged in or on a wall surface of the vacuum cleaner housing operatively adjacent to the at least one detectable element.

5. The detection means as set forth in claim 4, wherein the wall surface having the structural unit thereon of the vacuum cleaner housing is arranged essentially adjacent to the at least one detectable element.

6. The detection means as set forth in claim 1, wherein the sensor means possesses at least one transmitter for producing the electromagnetic waves and more particularly having an oscillating circuit and wherein the sensor signals are due to the reaction of the detectable element on the transmitter and/or the electromagnetic waves.

7. The detection means as set forth in claim 6, wherein the detectable element is in the form of a metallic sheet element and more especially in the form of a metal plate, foil or layer and wherein the sensor signals are formed in a manner dependent on the damping of the transmitter due to eddy current effects.

8. The detection means as set forth in claim 7, wherein the detectable element in the evaluating means is set for a certain amplitude of oscillation of the oscillating circuit.

9. The detection means as set forth in claim 8, comprising a threshold value means in the evaluating circuit, which is supplied with a signal derived from the amplitude of the oscillations of the oscillating circuit, switching on of the vacuum cleaner motor being prevented above an adjustable first threshold value.

10. The detection means as set forth in claim 9, wherein additionally under a second adjustable threshold value switching on of the vacuum cleaner motor is prevented.

11. The detection means as set forth in claim 6, wherein said detectable element comprises means for re-transmission of signals modified in relation to the received electromagnetic waves and wherein the sensor means possesses a corresponding receiving means.

12. The detection means as set forth in claim 11, wherein the modified signals are changed in their frequency and/or their phase relationship.

13. The detection means as set forth in claim 11, wherein the changed signals are modulated and/or comprise a signal code.

14. The detection means as set forth in claim 11, wherein the evaluating means possesses recognition means for returned signals modified in a predetermined manner.

15. The detection means as set forth in claim 11, wherein the detectable element is designed in the form of micro-chip.

16. The detection means as set forth in claim 6, wherein the transmitter is designed in the form of a light transmitter and the detectable element is in the form of an element returning the light to a light receiver in the sensor means.

17. The detection means as set forth in claim 16, wherein the detectable element is designed as a barcode or as a deflecting element returning the light unchanged or changed to a particular point in the sensor means.

18. The detection means as set forth in claim 6, comprising means for capacitive detection of the detectable element.

19. The detection means as set forth in claim 6, comprising a plurality of detectable elements arranged on or in the at least one additional filter and preferably furthermore on or in the connection member and/or vacuum cleaner bag, said elements being able to be sensed by parts of the sensor means.

20. The detection means as set forth in claim 1, wherein the at least one additional filter is a micro-filter and/or a filter cassette and/or an active carbon filter and/or combined filter.