Note: Descriptions are shown in the official language in which they were submitted.
Liz
The present invention refers to a method for sensing
changes in the filtering effect of filtering devices for separation
of contaminations from gaseous streams with indications of the
changes by means of signal remittance. The invention further
refers to a device for carrying out the method in question.
Sensing principles known in the art to sense the degree
of filling the filter of air filtering devices are not sufficiently
sensitive which means that the filtering device is allowed to
be filled with contaminations to a relatively high degree before
a signal is emitted. This means that the filtering device at
times runs with a reduced filtering effect.
The object of the present invention has been to eliminate
this problem and to achieve a method by means of which a
considerably more sensitive sensing function is obtained. The
object of the invention has further been to provide a simple
and reliable device to carry out the method according to the
invention.
The present invention provides a device for sensing
changes in the filtering effect of a filter means and for providing
an indication of changes in the filtering effect comprising:
a) filtering cells for separating contaminants from
a gaseous stream,
b) fan means for moving the gaseous stream through
said filter means,
c) means for detecting a voltage level between said
filtering cells,
d) means for emitting signals responsive to the voltage
level,
e) means for activating an indicating means responsive
to the emitted signals, and
f) means for deactivating said fan when the emitted
signals fall outside of a predetermined range.
,,
The present invention also provides a method of sensing
changes in the filtering effect of a filter means and providing
an indication of changes in the filtering effect comprising:
a) providing a motor driven fan for moving a gaseous
stream,
b) providing filtering cells for separating contaminant
from the gaseous stream,
c) sensing a voltage level between said filtering
cells,
do emitting signals responsive to the voltage level,
e) energizing an indicating means responsive to the
emitted signals, and
f) stopping said fan motor when the emitted signals
fall outside of a predetermined range.
The invention will now be explained with reference to
the enclosed drawings in which:-
Figure 1 schematically shows a filtering device with
a device according to the invention;
Figure 2 schematically shows a voltage field;
Figure 3 illustrates a circuit diagram of a coupling
forming part of the device according to the invention.
The device illustrated in the drawing consists of a
voltage transformer 1 and filtering device l for separation
of contaminations from gas, preferably harmful substances from
smoke from welding apparatuses. The filtering device 2 comprises
an automatically driven fan 3 and one or several removable filters
4 including filtering cells 5. The fan 3 is intended to suck
in contained air 6 in an ionized sector 7 of the filtering
lo I
device 2, where contained particles in the air stream are charged
positive to bring forth that these particles will be deposited
on the filter cells 5, which are of negative charge.
With a continuing deposit of particles on the filter
S cells 5 the capability of the latter to receive more particles
increases such that the filtering effect of the filtering device
will be unsatisfactory aster some time of use.
In order to indicate a reduced filtering function before
the filtering device 2 is allowed to continue with a reduced
filtering effect for a too long time or before the filtering
effect further decreases to an unacceptable level, the filter
cell 5 is supervised by a sensing and signal emitting device
3. This one has an electronic control circuit g (see figure
3) with inputs 10 and 11 for indicating the voltage (the so
called resonance voltage) between the filter cells 5. By normal
filtering effect the voltage between the filter cells 5 is within
the interval llQ-240V (see figure 2) and the input resonator
9 does not give any voltage to buzzer 12 and lamp 13 but continues
to give voltage to a relay to the motor of the fan 3. If the
voltage sinks below Levi or raises over 124V by filling of the
filter cells 5 with contaminations and/or by short circuit effects
in thy filter cells 5, caused by damages on collector plates
thereof (not shown) and/or as a consequence ox disruption of
ionizing cords (not shown) in the ionized sector 7, the following
takes place:
Jo .
JO 62
Voltage Signal remittance
_
108,5 constant buzzer sound
- constant light
contractor to fan motor breaks
within for example 12 seconds
108,5 loo intermittent buzzer sound
intermittent light
contractor does not break
110-124V no buzzer sound
no light
contractor does not break
124-125,5V intermittent buzzer sound
intermittent light .
contractor does not break
125,5V constant buzzer sound
lo constant light
contractor to fan motor breaks
within for example 12 seconds
Breaking of contractor to fan motor, ire. shut off fan I is
preferably late by some seconds, for example 6-20 seconds, such
that the fan 3 will not stop as a consequence of temporarily
passing metal objects whir temporarily reduces the voltage
between the filter cells 5. If however the voltage permanently
underpasses 108,5V or exceeds 125,5V the fan 3 is stopped and
can only be restarted after removal or cleaning of dirty filter
cells 5.
The values of the voltage/signal remittance chart above,
can of course vary in dependency of the style and so forth of
the parts of the sensing and signal emitting device 8 or other
parts of the system.
_ 5 _ 1212~Z
The construction of the control circuit 9 can vary,
but in figure 3 a practically useful and functionally correct
device is illustrated. It may be mentioned that the input
resonance voltage is rectified, voltage divided and filtered.
The level is regulated by means of the trimmer potentiometer
14 and constitutes a value of the purity of the filter.
The voltage is transmitted to the comparators 15 -
I and reference voltages are formed by stabilized 24V from
the unit 19.
The comparators 16 and 17 give signal at 124V respectively
lo V since voltage and the comparators 15 and 18 give signals
at 125,5 V respectively 108,5 V. The comparators 16 and 17
activate the pulse circuit 20 which feeds the buzzer 12 and
trial 21, which ignites the signal lamp 13. An intermittent
lo light and sound signal is obtained when one of the comparators
16 or 17 is activated.
The comparators 15 and 18 block the pulse circuit in
an active condition and starts the time circuit 22 which after
about 12 seconds breaks the control current to trial 23, which
causes the contractor of the feed device to fall. The unit
24 works as a drive circuit for trial 23 and the resistors
25 and 26 cause a hysterias of about lo at the levels 124V
respectively Levi to give a distinct function.
The method and the device according to the invention
are nut limited to the embodiments now described but may be
varied within the scope of the claims. Thus, signal remittance
can take place in the form of but one light signal, only sound
signal, only cut off signal or any appropriate combination thereof.
