AT389991B - DEVICE FOR DISPLAYING THE FILLING LEVEL OF THE FILTER BAG IN HAND VACUUM CLEANERS - Google Patents

Description

No. 389991

The invention relates to a device for displaying the degree of filling of the filter bag in hand-held vacuum cleaners, in which the filter bag is connected downstream of the blower and a silencer is arranged in front of the filter bag, the display consisting of a pressure cell with a membrane.

Hand-held vacuum cleaners in which the filter bag is connected downstream of the blower and a silencer is arranged in front of the filter bag are known (cf. US-A-2125 850 and AT-PS 359 963).

Also known are handheld vacuum cleaners without a silencer, in which a load cell with a bendable or displaceable membrane is provided to indicate the degree of filling of the filter bag (cf. US-A-2 230 113, US-A-2 099 391 and CH-PS 316 709).

Pressure transducers, which have a membrane that is subjected to differential pressure and mechanically switches an electrical switch, are installed in vacuum cleaners with silencers as separate components, which are then connected to the pressure chambers to be monitored via hoses. Since these hoses have a small cross-section, it is necessary in rooms exposed to dust to filter them on their end faces so that they do not become blocked.

The object of the invention is to integrate a device for displaying the degree of filling of the filter bag in a handheld vacuum cleaner with a silencer that no additional connecting lines have to be created and additional filter devices can be omitted.

According to the invention the object is achieved in that the muffler housing is provided with a pot-like bulge which is covered by a retaining ring which bears a membrane, and the bulge in the floor is provided with an opening which forms an air connection to the inner part of the muffler.

It is thus advantageously achieved that a device for displaying the degree of filling of the filter bag can be used in a handheld vacuum cleaner without many additional parts and without additional connecting lines.

According to a further feature of the invention, a filter fleece is arranged in front of the opening provided in the bottom of the bulge.

An exemplary embodiment of the invention is described below with the aid of the drawing, in which FIG. 1 shows a sectional drawing through a hand-held vacuum cleaner with a silencer and pressure sensor, and FIG. 2 shows an enlarged detail from FIG. 1, which shows the arrangement of the pressure sensor.

Fig. 1 shows the section through a motor head (1) of a handheld vacuum cleaner. This motor head (1) consists of a double-walled housing (2) and an electric motor (3) arranged in this housing (2) which drives a suction fan (4). On the side (5) the motor head (1) is connected to nozzles or additional devices (not shown) and on the side (6) the connection to a dust filter bag (not shown) is made. It is therefore a handheld vacuum cleaner with a filter bag connected downstream of the suction fan (4).

Since, in such vacuum cleaner models, the dust filter bag is usually only surrounded by a fabric basket or a thin shell, all the noises generated by the electric motor (3) and suction fan (4) emerge directly to the rear.

Therefore, a silencer (7) is interposed in the motor head (1) to keep the noise level very low.

If a device for displaying the degree of filling is now to be installed in such a hand-held vacuum cleaner, it works in the overpressure range, ie. that is, the pressure query must take place on the way from the suction fan (4) to the dust filter bag.

There are usual problems with clogging problems and the silencer (7) is designed as a so-called absorption silencer (see Fig. 2), the pressure sensing device (8) is arranged directly on the silencer housing (9) and the absorption material (10) is used as a filter

The partial section in Fig. 2 illustrates the structure of the pressure sensing device (8) on the muffler housing (9). The muffler (7) consists of the muffler housing (9) and the absorption material (10) arranged therein, which is covered in the airway (represented by an arrow) with a perforated tube (11). A tube (12), which comes from the suction fan (4), engages in the tube (11) as a ventilation connection. In the vicinity of this connection point, the silencer housing (9) has a pot-like bulge (13). This pot-like bulge (13) forms the pressure chamber (14) for the membrane (15). Via the opening (16) in its base (24), the intermediate space (17) and the absorption material (10), it has an air connection to the main air path running in the tube (11).

These airways are shown by arrows.

The pot-like bulge (13) is closed by the membrane (15). The membrane (15) is held by a retaining ring (18) which overlaps a bead (20) on the bulge (13) with hooks (19) and is riveted to a pin (21) elsewhere. The membrane (15) carries in the middle a fixed plate (22) which, when the membrane (15) is deflected upwards, via the lever (23) has a z. B. can operate electrical switch.

If necessary, a filter fleece (25) can also be arranged in front of the opening (16). -2-

Claims (2)

No. 389991 PATENT CLAIMS 1. Device for displaying the degree of filling of the filter bag in handheld vacuum cleaners, in which the filter bag is connected downstream of the blower and a silencer is arranged in front of the filter bag, the display device consisting of a pressure transducer with a membrane, characterized in that the silencer housing (9) is provided with a pot-like bulge (13) which is covered by a retaining ring (18) carrying a membrane (15), and the bulge (13) in the floor is provided with an opening (16) which provides an air connection to the inner part of the silencer (7). 2. Device according to claim 1, characterized in that a filter fleece (25) is arranged in front of the opening (16) Hiezu 1 sheet drawing -3-