EP0456083A1 - Air filter choke indication device for vacuum cleaners, room filters and the like - Google Patents

Abstract

The invention relates to a suction cleaning device with an indication of the degree of contamination of an air filter (5) which is arranged in an air flow for separating dirt from the air flow. A measuring arrangement for the degree of contamination of the air filter (5), which is designed as a light barrier (9, 16), is provided, which is connected to a display (13). The light barrier can be designed as a fork or reflection light barrier and optically detects the degree of contamination of the air filter and converts it into an electrical output signal which is evaluated to control the display (13). <IMAGE>

Description

The invention relates to a device for displaying the degree of contamination of an air filter according to the preamble of claim 1.

Devices for monitoring the pollution of an air filter in suction cleaning devices such as vacuum cleaners or in devices for cleaning room air are known. They have a measuring arrangement for detecting the pressure difference before and after the air filter of the air flow flowing through the filter. The pressure difference increases with increasing filter loading. However, the recorded pressure values are subject to fluctuations, for example in suction cleaning devices, since the volume flow of the air flow is severely impaired by the use of the suction tool. If the suction tool lies completely on the surface to be cleaned during the cleaning process, the suction air flow is severely restricted and changes strongly in the course of the working movement with the suction tool partially or completely lifted off the surface to be cleaned. The measuring arrangement detects the pressure fluctuations and activates the display for a necessary filter change, although this is not exchanged must become. The staff is therefore very unsettled in the assessment of the filter loading and thus the time of filter cleaning or filter replacement. The indicator for the degree of contamination of the air filter is too imprecise.

The actual conditions are also unfavorable for air purification devices for cleaning room air or for humidifying room air. With regard to noise generation and to avoid drafts, the flow velocity of the air flow, that is to say the air volume flowing through the air cleaning device, is kept low in room air cleaning devices. Due to the air conveying system of these devices, the negative pressure generated by the conveying fan is relatively low, so that the pressure difference occurring when the loaded filter flows through is also very low and can therefore only be detected with great effort. To make matters more difficult with air purification devices with additional air humidification, water and lime deposits form in the filter.

The invention has for its object to develop a generic device such that volume fluctuations in the air flow do not lead to incorrect displays of the degree of contamination of the air filter.

The object is achieved according to the characterizing features of claim 1.

With the light barrier to be arranged according to the invention, the dirt loading of the air filter can be detected simply and precisely and in particular independently of volume fluctuations in the air flow. The display controlled by the light barrier is therefore very accurate. The intensity of the emitted light beam is reduced in accordance with the filter loading, the detectable reduction in the radiation intensity being converted into an electrical output signal and evaluated in an evaluation circuit. The evaluation circuit generates electrical function signals and controls, for example, an optical display for the degree of contamination of the air filter and / or acts on a control device, for example to switch off the device when the filter is added. The operator can easily and precisely recognize when to clean the filter or replace it with a new filter or, for example, with a roller belt filter, to move the loaded filter surface.

The light barrier advantageously works in the infrared range. It has been shown that such radiation can achieve high accuracy with little malfunction.

The dirt-carrying air stream advantageously flows onto the outside of the filter facing away from the light barrier, so that the light barrier lies in the clean air space of the filter. In this way, dirt deposits on the light barrier can be avoided, which could possibly lead to malfunctions.

It can be advantageous to arrange a plurality of light barriers in a distributed manner over the filter to be monitored, the output signals of the light barriers preferably being evaluated together as a sum value. It can also be expedient to use the output signals of the light barriers arranged at different points on the filter surface to produce an average signal, for example by arithmetic ones Form averaging and compare this arithmetic mean signal with a limit value or process it with an evaluation circuit.

Reflection light barriers are advantageously proposed as light barriers; fork light barriers can also be advantageously arranged. The choice of light barrier will be based on the shape and shape of the filter as well as the spatial conditions.

Fig. 1

im Längsschnitt eine schematische Darstellung eines Saugreinigungsgerätes mit einer Reflexionslichtschranke,

Fig. 2

im Querschnitt einen Faltenfilter mit einer an der Faltung angeordneten Gabellichtschranke,

Fig. 3

eine Ansicht einer Faltenfilterpatrone mit einer zugeordneten Gabellichtschranke,

Fig. 4

im Schnitt ein Flachfilter mit angeordneter Gabellichtschranke,

Fig. 5

im Schnitt ein Flachfilterband mit einer angeordneten Reflexionslichtschranke.

Further features of the invention result from the further claims, the description and the drawing, in which exemplary embodiments of the invention described in detail below are shown. Show it:

Fig. 1

in longitudinal section a schematic representation of a suction cleaning device with a reflection light barrier,

Fig. 2

in cross section a pleated filter with a fork light barrier arranged on the fold,

Fig. 3

a view of a pleated filter cartridge with an associated fork light barrier,

Fig. 4

on average a flat filter with an arranged fork light barrier,

Fig. 5

on average a flat filter belt with an arranged reflection light barrier.

The suction cleaning device shown in FIG. 1 has a dirt holding container 3, which is arranged on a chassis 2. The dirt container 3 is sealed airtight by a cover part 4. In the cover part 4, a motor fan unit with electrical switching, control and display elements is integrated in a known manner. A display 13 is provided for the degree of contamination of the air filter.

A replaceable filter 5 is also fastened to the cover part 4 and extends axially into the dirt holding container 3. The filter 5 can be a pleated filter or a filter with a smooth outer surface 12 or inner surface 37. Through a suction port 8 of the cover part 4, a dirt-laden suction air stream flows into the dirt holding container 3, flows through the filter 5 and is then blown out into the environment via the engine blower unit as a cleaned suction air stream. A suction line (not shown) is connected to the suction port 8 and is connected to a suction tool (not shown). The dirt particles contained in the suction air flow are retained by the filter 5. The larger dirt particles fall into the dirt receptacle 3, while the finer and finest dirt particles are deposited on the surface and in the filter structure of the filter 5. The more the filter 5 becomes clogged with dirt particles, the more the suction air flow of the suction cleaning device 1 is throttled. The flow resistance of the filter increases.

According to the invention, the dirt loading of the filter 5 is detected by a commercially available light barrier 9, the structure and mode of operation of which is generally known.

In the exemplary embodiment shown in FIG. 1, a reflection light barrier 9 is attached to the cover part 4 of the suction cleaning device. The light beam 6 emitted by the transmitter of the reflection light barrier 9 is aligned approximately axially with respect to the dirt holding container 3, that is to say it is approximately parallel to the outer surface 12 of the filter 5 to be monitored Deflected 90 ° so that it strikes the outer surface of the filter 5. The light beam 6 is reflected on the outer surface 12 of the filter 5 and is reflected back as a reflected light beam 7 via the reflector 10 to the receiver of the reflection light barrier 9. Due to the dirt loading of the filter 5, the reflectivity of the filter outer surface 12 decreases; in the same way, the intensity of the reflected light beam 7 is reduced as a function of the loading of dirt. In a simple manner, a limit value is set for the intensity of the reflected light beam 7, below which the light barrier 9 switches and activates the display 13, which visually indicates the necessary filter change. It can also be advantageous to detect the change in intensity of the reflected light beam 7 compared to the emitted light beam 6 and to process it in an electronic evaluation circuit. The evaluation circuit then outputs a control signal to a display and / or control device in order to display the detected operating state and / or to change it.

The reflector 10 for deflecting the axial light beam into a light beam radial or perpendicular to the filter 5 is advantageously fastened to the inner wall 11 of the dirt-holding container 3. It can also be beneficial Arrange reflector 10 on the filter 5 itself or a holder of the filter 5.

2 shows an exemplary embodiment of the invention on a pleated filter 15. The arranged light barrier is a fork light barrier 16; the use of a retro-reflective sensor can also be useful. The fork light barrier 16 is arranged in such a way that two folds 17 and 18 of the filter 15 which run towards one another at an acute angle lie with the folding edge 19 formed by them between the two legs 22 and 23. The transmitter 24 and the receiver 25 of the fork light barrier 16 are arranged in the region of the ends of the legs 22 and 23. The light beam 21 emitted by the transmitter 24 penetrates the filter folds 18 and 19 and falls on the receiver 25. The intensity of the light beam arriving at the receiver 25 is reduced by contaminating the filter surface and the filter structure. If the value falls below a predetermined limit, the fork light barrier switches through and activates the display 13, which visually indicates the necessary filter change. The reduction in intensity can also be evaluated in an electronic evaluation circuit which then controls the display 13 and / or causes a change in the operating state of the device.

As shown in Fig. 3, the fork light barrier 16 is advantageously fixed to the cartridge-like pleated filter 15 by a bracket 26. An electrical line 29 and a plug connection 30 are provided for the electrical connection to the display or the evaluation circuit. The holder 26 consists of a rod 40 arranged laterally next to the pleated filter 15, the ends of which are held in the rigid end plates 41 and 42 of the pleated filter.

The fork light barrier is attached to the rod 40, preferably adjustable along the rod. The cartridge-like pleated filter 15 is replaced together with the fork light barrier 16 as an exchange part. After changing the filter 15, it is only necessary to insert the electrical plug connection. An adjustment of the fork light barrier after changing the pleated filter 15 is not necessary. Such an adjustment would be necessary if the fork light barrier 16 were attached to the cover part 4, for example.

FIG. 4 shows the use of a fork light barrier 16 for monitoring a flat filter 31, as is used, for example, as a so-called blow-out air filter in suction cleaning devices or in room air cleaning devices. The flat filter 31 cleans the blown air flow conveyed and filtered by the suction fan of fine dust still contained. Since this blow-out air flow also contains the mostly separate cooling air flow of the motor fan unit, which is contaminated with the abrasion of the carbon brushes in commutator motors, the dirt load of the cooling air flow in the flat filter 31 is also retained.

The type of filter monitoring described can also be used advantageously in the case of flat belt filters, the so-called roll belt filters, in air purification devices.

A reflection light barrier 9 is arranged in FIG. 5 for monitoring a flat filter 31. The light beam 34 emanating from the transmitter 24 of the reflection light barrier 9 strikes the surface 35 of the flat filter 31 approximately perpendicularly, is reflected there and falls on the receiver 25 as a reflected light beam 33. The receiver 25 generates an electrical output signal that changes as a function of the intensity of the incident light beam 33. The intensity of the received light beam 33, which is changed by the filter loading, is thus forwarded as an electrical signal to an electronic evaluation circuit and implemented as a display and / or control signal.

The flow direction 32 of the filter 5 or 15 with the dirt-laden air flow can be chosen freely. A flow against the air filter in the direction of arrow 32 is advantageously provided, as shown in FIGS. 2, 4 and 5. In this way, functional impairment of the light barrier by dust deposits is largely avoided, since the light barrier is located in the cleaned exhaust air flow.

Since the filter materials can differ due to manufacturing tolerances or material changes and color variations, it is advantageously provided to arrange a further light barrier for at least one reference measurement. This reference light barrier picks up a reference measurement value at an unoccupied point of the filter, which reference value can be supplied to the electronic evaluation circuit as a base value.

It can also be advantageous to distribute a plurality of light barriers 16, 16 'over the filter surface and to evaluate the intensities of the radiation received at the individual measuring points, for example as a "sum signal" or to arithmetically average them.

It has been shown that the best functional results are achieved with radiation in the infrared range in the light barriers used (fork light barrier, reflection light barrier).

Claims (10)

Device for indicating the degree of contamination of an air filter in a suction cleaning device, room filter or the like, the air filter (5) being arranged in an air flow for separating dirt from the air flow, and with a measuring arrangement for the degree of contamination of the air filter, which is provided with an indicator ( 13) is connected
characterized in that the measuring arrangement is a light barrier (9, 16), the light beam of which is oriented approximately perpendicular to the surface of the filter. Device according to claim 1,
characterized in that the radiation from the light barrier is in the infrared range. Device according to claim 1 or 2,
characterized in that the air stream carrying dirt flows onto the side of the filter (5, 15, 31) facing away from the light barrier (9, 16). Device according to one of claims 1 to 3,
characterized in that a plurality of light barriers (9, 16, 16 ') are arranged in a distributed manner over the filter (5, 15, 31) to be monitored, the output signals of which are preferably evaluated as a sum value. Device according to one of claims 1 to 4,
characterized in that the light barrier is a reflection light barrier (9), the radiation from the reflection light barrier (9) preferably being directed via a reflector (10) onto the outer surface (12) of the filter (5) and from the filter surface (12) preferably via the Reflector (10) is reflected back to the receiver of the reflection light barrier (9). Apparatus according to claim 5 for a dust cleaning device with a dirt holding container (3) which can be closed by a cover part (4),
characterized in that the light barrier (9) is arranged on the cover part (4) and the reflector (10) is fastened to the inner wall (11) of the dirt holding container (3). Device according to one of claims 1 to 5,
characterized in that the light barrier is a fork light barrier (16). Device according to claim 7,
characterized in that the filter (5) is a pleated filter (15) and the two legs (22, 23) of the fork light barrier (16) are two pleats (17, 18) and their overlap common folding edge (19), the light beam (21) directed from the transmitter (24) to the receiver (25) penetrating the two folds (17, 18). Device according to claim 8,
characterized in that the fork light barrier (16) is fixedly connected to the pleated filter (16) by means of a holder (26) and forms an interchangeable unit with it. Device according to claim 7,
characterized in that the fork light barrier (16) with its legs (22, 23) engages over a flat filter (31) and the light beam (21) directed from the transmitter (24) to the receiver (25) penetrates the filter (31).

Images