Vacuum cleaner dust container filling indicator device

An indicator mounted on a vacuum cleaner housing for showing at any given time the degree of filling of the dust container. The indicator includes bellows which are connected to both the outside of the dust container and the interior of the vacuum cleaner housing whereby the bellows are acted upon under the influence of the changing pressure differential to respectively expand or contract the bellows thereby indicating the degree of clogging of the dust container.

BACKGROUND OF THE INVENTION 
Devices for visually indicating the amount of dust and dirt present in a 
vacuum cleaner dust bag or container are known. Most often these devices 
depend upon the difference in pressure between the outside of the vacuum 
cleaner and the inside of the dust container in order to displace or 
rotate an element within a sealed casing. The movement of the element 
corresponds to the degree of filling of the dust container. Devices of 
this type have a serious disadvantage in that they require the use of 
sealing rings and specially designed air filters in order to insure the 
dependable functioning of the indicating device. Naturally, the use of 
sealing means and filtering devices increases the cost of manufacture of 
the above-mentioned indicating devices, as well as requiring periodic 
inspection in order to insure the faultless operation of these indicators. 
SUMMARY OF THE INVENTION 
The present invention relates to an inexpensive but reliable indicator 
device for a vacuum cleaner dust container which shows the amount of 
filling of the dust container at any given time and while the vacuum 
cleaner is either operative or inoperative. 
It is an object of the present invention to provide an indicator device for 
a vacuum cleaner having a bellows arrangement in a closed, at least 
partially transparent container, which communicates with both the 
atmosphere and the interior of the housing for the vacuum cleaner so that 
the difference in pressure results in the movement of the indicator means 
to show the degree of filling of the dust container. 
It is another object of the present invention to provide a means for 
blocking the retrograde movement of the indicator device so that a correct 
reading may be obtained even if the vacuum cleaner is inoperative. 
A further object of the present invention is to provide a finger-operated 
means for returning the indicator member of the indicating device to its 
initial position when an empty dirt receptacle is placed in position 
within the vacuum cleaner housing.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The indicator device is referred to generally by the reference numeral 10 
and is shown arranged on a vacuum cleaner housing. The casing 11 for the 
indicator device 10 is at least partially transparent so that the 
indicating means therein can be easily observed from the exterior of the 
vacuum cleaner. Furthermore, the indicator device comprises two bellows 12 
and 13 which are attached to a frame 14, the latter being in the form of 
an inverted U. As seen in FIG. 1, one downwardly directed leg or end piece 
15 of the frame 14 supports the bellows 12 while the other downwardly 
directed leg or end piece 16 supports the bellows 13. It should be noted 
that the bellows 12 communicates by means of a first air conduit 17 with 
the outside of the dust container or the atmosphere, while the bellows 13 
communicates by means of a second air conduit 18 with the interior of the 
dust container in the vacuum cleaner housing. 
The indicator device 10 is shown tiltably arranged in the casing 11 around 
a pivot pin 19 and under the influence of the varying air pressure 
differential between the outside atmosphere and the inside of the dust 
container (not shown). The frame 14 exercises a translatory movement 
against the action of a spring 20 through the bellows 12 and 13. The 
spring has one end attached to the frame 14 and its other end to the 
tiltable portion of the indicator device, as shown in FIG. 3. As seen in 
FIGS. 3 and 4, the position of the bellows 13 can be observed through the 
sight glass 21 in an exterior surface of the indicator device casing 11. 
This observation will reveal the amount of clogging or filling of the dust 
bag or dust container at any given time. 
A blocking device for stopping the movement of the bellows is provided so 
that the bellows remain in the position last reached because of the 
momentary pressure differential, and thus indicates the filling condition 
of the dust container. An indication is given even when the motor-fan unit 
of the vacuum cleaner is inoperative. Thus, it is possible to determine 
whether the dust container has to be replaced even before using the 
apparatus. 
The blocking device comprising a notched surface 22 secured at opposite 
ends to the inside of legs 15 and 16 and arranged between the legs 15 and 
16 of the frame 14, and is firmly attached to the same. The notches 
cooperating with a pawl-like projection 23 on the body of the indicating 
device. When the pressure differential increases, because of the 
decreasing absolute pressure prevailing on the outside of the dust 
container, the frame 14 is moved gradually with the aid of the bellows 12, 
13 from the initial position, shown in FIG. 1, to the end position 
indicated in FIG. 2. A tension spring 24 biases the projection 23 
continually into contact with the grooved surface 22. In this manner the 
frame 14, and thereby also the bellows 12 and 13 are fixed in the position 
that is reached at any given moment, even when the motor-fan unit has 
stopped operating. In this manner, the bellows 13, in its blocked 
position, indicates the filling amount of the dust container, which can be 
readily observed through the sight glass 21. 
In order to return the bellows to their initial position the indicating 
device can be provided with a knob 25 accessible from the outside of the 
vacuum cleaner. If the knob 25 is depressed the entire indicating device 
is swung a small amount inwardly until its movement is stopped by an 
abutment surface 26. A further depression of the knob 25 removes the 
projection 23 from its contact with the notched surface 22, and the frame 
together with the bellows is returned by the action of spring 20 to its 
initial position shown in FIG. 1. Alternatively, the blocking device can 
be actuated to its zero position via a bar connected to a cover enclosing 
the dust container space (not shown). 
The above embodiment is, of course, not intended to limit the invention to 
any extent. Several modifications are thus possible within the scope of 
the annexed patent claims defining the invention.