Year: 1886

page_text: I, MORITZ MARTIN, manufacturer, residing at Bitterfeld, Kingdom of Prussia,
German Empire, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following specification :-
My invention relates to dust-collectors in which the filtering surfaces are cleaned
from adhering dust by a back-draught of air, and the improvements consist in the
construction of the said filtering surfaces of flexible shallow bags adapted to be
bent one way and the other by the alternating currents of air acting thereon, and
in the particular means employed for producing the back-draught quickly so as
thereby to throw the said bags with a jerk from one extreme position into the
other, in order to shake off the greater portion of the adhering dust at once, and to
loosen the remaining portion for facilitating its removal by the wind. The said
improvements may as well be applied to apparatuses in which the air-currents are
produced by suction as to such in which they are obtained by pressure.
On the annexed sheet of drawings a dust-collector provided with my improve-
ments is represented by Fig. 1 in longitudinal section, by Fig. 2 in an end view
and by Fig. 3 in sectional plan. Figs. 4, 5 and 6 are detail views of portions of
the operating mechanism.
In Fig. 1 the bag-like main filtering surfaces are marked by the letter a, those
of an auxiliary filter by b. Both surfaces are fastened to suitable frames, and they
are so arranged together with these and a partition-walls in a box, that the
compartments j, i and i¹ are formed. Into the compartment j is conveyed the
dust-laden air by the pipe d in which there is a throttle-valve q. The compart-
ment i communicates on one hand by a way of communication, constituted by the
apertures e, h¹ and chamber g¹, with the outer air, on the other hand by a way,
formed by the apertures e', h³ and chamber g, with an exhauster, whereas the
compartment is in communication by means of the apertures e², h² and chamber g
with the same exhauster, and by means of the aperture h (Fig. 3) chamber g² and
aperture h³ with the outer air. Over the apertures e, e¹, e³ grates are fixed carrying
corresponding slide-valves f, f¹, f, while in front of the aperture h³ there is a
grate with the slide-valve f³. From the bottom of the compartment j extend
downward the spouts c with the valves p, which are kept closed during the greater
part of the time of working of the apparatus.

page_text: The said slide-valves and the throttle-valve q require to be alternately so
adjusted that, during the period of filtration through the main filter a, an air-
current passes in the direction of the dotted arrows from the pipe d upwards
through a to h, and that, simultaneously, air entering at h³, is sucked downward
through the auxiliary filter b for cleaning the same; whereas during the time the
main filter is cleaned, the air entering from the outside at h¹ moves downward
through a and upward through b to h², according to the arrows drawn in full
lines. This adjustment of the slide-valves and of the valve is brought about, in
combination with the springs o, o¹, o², by the cam-disks n, t and r (see also Figs. 4,
5 and 6) keyed on a common shaft m, operated by a pulley 7 through the medium
of the shaft and the worm-wheel gearing. The disk n has such a form that,
in acting on the bar 2' of the slide-valve f³, it will keep the latter closed during
the greater part of its rotation, but that, when a notch of the disk comes opposite
to the end of the bar 2¹, it will release the said bar, whereupon the spring o¹ opens
the valve quickly. The function of the disk tis to operate, in combination with
the lever y and the spring o, on the bþar z and thereby on the slide-valves f, f¹, fa
fixed to 2, and its form is such that, during the greater part of its rotation, the
valves fand f* will be closed and the valve f¹ open, whereas for a short time the
said valves, being released by the disk, will be brought into the opposite position
by the action of the spring o. The disk finally, by means of its rim projecting
upwardly, and a crank fixed on the axle of the throttle-valve q, keeps the valve q
closed, but, during each rotation, allows the spring o², Fig. 2, to open the same for
a short time.
The three cam-disks are so arranged in respect to each other that the slide-
valves f, f¹, f' and f³ and the valve q will simultaneously assume the following
positions.
While the filtration through the main filter goes on, the valve q and the slide-
valve f¹ are open, the slide-valves fand f³ closed, and, during the greater portion
of the time, the valve f³ is also closed. The exhaustor, communicating with the
aperture 2, then produces an air-current which passes according to the dotted
arrows from the pipe d through compartment j, filter a, compartment i, aperture e¹
and chamber to the said aperture h³. By means of the air-pressure acting on the
filtering-surfaces a, these have been bent or thrown upward, as is shown by dotted
lines, and the dust is being deposited on the under side of the said surfaces. The
filtration may thus be continued, for instance, for two minutes. The operation of
the slide-valve f³ I shall describe hereafter.
During the time the filter a is being cleaned, the valve 9 and the slide-valves f¹
and fare closed, the slide-valves fand f2 open. The exhauster then draws air
from the outside through the aperture h¹ and produces the current indicated by
the arrows drawn in full lines, and the course of which is from h¹ through
chamber g¹ aperture e, compartment i, filter a, compartment j, filter b, compart-
ment, aperture e³, and chamber g to the aperture 2. The position of the slide-
valves and of the valve q being changed quickly at the commencement of this
period, the filtering surfaces a will be suddenly bent or thrown downward into the
position shown in Fig. 1 by full lines, whereby the adhering dust is shaken off.
By means of the inverted air-current the process of cleaning the filter is thereupon
completed in a few seconds. The dust detached from the filter a partly falls to
the bottom of the compartment ; and collects on the valves p, while the remaining
part, which is carried along with the air-current, is separated out from the same
and retained by the filter 6, the bag-shaped surfaces whereof are, at the time, bent
upward.
The filter b now also requires to be cleaned from dust, and for this purpose an
air-current is produced during the described period of filtration through the main
filter; by opening for a short while the slide-valve f³. When this valve opens, air
enters from the outside through the aperture h³, chamber g³ and aperture h into
the compartment ", bends the filtering surfaces 6 suddenly downward so as to
shake off the dust, and then fully cleans them by its passage through the same into
'

page_text: compartment j. On percolating thereupon the filter a the air is again freed from
the dust it had carried along from filter b, and finally it escapes, together with the
air from d, through compartment i, aperture e¹, chamber g and aperture h² to the
exhauster. The filter 6 is preferably cleaned at the beginning of the filtering
period, a very short time, say about a second, being then sufficient therefor.
For the removal of the dust collecting in the compartment j, the apparatus may
be provided with any suitable contrivance. The drawing shows for this purpose
the two spouts c with the throttle-valves p. These valves are fixed on a common
axle w, which may be partially rotated one way by the crank c¹, the lever u and
the tooth v on the cam-disk r, and the other way by a spring. When the tooth v
opens the valves p, the dust falls into bags tied to the spouts c. This procedure
requires but a moment of time and does not cause an interruption in the filtration,
but only a slight passing diminution in the efficiency of the apparatus.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what
I claim is:
1. In dust-collectors having filtering surfaces for separating the dust from the
air, and provided with means for producing alternating currents of air through the
said surfaces, the construction of the filtering surfaces of flexible bags adapted to
be bent inside out and vice-versa by the said currents, substantially as and for the
purpose described.
2. In a dust collector, the two filters a and b consisting of flexible bags arranged
together with a partition-walls within a box so as to form the compartments j, i
and piped for supply of dust-laden air to compartment j, ways of communi-
cation leading from either compartment i and into the outer air and to an
exhauster, slide-valves f, f¹, f, f³ arranged in the said ways, valve q in pipe d,
rotating cam-disks n, t, r, springs o, o, o' and means of connection between the
said cam-disks and the valves, all combined and operating together substantially
as and for the purpose described.
D
J
M1 1000