Improvements in Bag Filters for Air with Automatic Apparatus for Separating the Dust.
Year: 1898

page_text: Date of Application, 29th June, 1898-Accepted, 15th Oct., 1898
COMPLETE SPECIFICATION.
Improvements in Bag Filters for Air with Automatic Apparatus
for Separating the Dust.
I, WILHELM BETH, Engineer, of Lubeck, in the Empire of Germany, 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
statement:-
This invention relates to an improvement in the construction of bag filters with
automatic apparatus for separating the dust from the sides of the filter.
According to this invention the bag filters are composed substantially of sacks or
bags made of suitable material and with their openings turned downwards; and
through which the air is drawn or forced by means of an air exhauster whereby
the particles of dust contained in the air remain adhering to the inside of the bag.
For this purpose, when the exhauster is acting, the bags are placed in a case
which is made tight on all sides, and the hollow space in which is in communica-
tion with the exhaust channel, and only the bags, the openings of which are shut
off from this hollow space, communicate with the channel which conveys the air
charged with dust.
After the air charged with dust is drawn off for a certain time and a layer of
dust has collected on the inside of the filter, the dust is shaken off by means of
an automatic apparatus, assisted by a counter current of air, and falls into a col-
lecting chamber.
In order that the action of the filter may be continuous, one bag at a time is
cleaned out in the case of an apparatus with two bags, and two bags at a time in
the case of an apparatus having 4 or more bags, whereby it is possible according to
the required filtering surfaces to remove 10 pairs (10 x 2) of bags from one casing
for the purpose of being cleaned out from 10 divisions or compartments one after
the other.
In the accompanying drawings the invention is represented as applied to a
filter containing two pairs of bags.
Fig. 1 is a side elevation of a filter casing.
Fig. 2 a front view of the upper part of the casing with the beating apparatus.
Fig. 3 is a side view in section of the casing.
Fig. 4 is a plan of Fig. 2.
Fig. 5 represents the whole arrangement for a number of pairs of filtering bags.
The filtering bags a are completely separated from each other in pairs by
means of a partition wall win the case of a filter with two bags each is thus
separated from the other-in the casing G being suspended by means of
arms h h (which are pressed upwards by strong springs f) with the assistance of
the bow i c is the junction tube for the exhauster, furnished with a throttle
valve d; e the inlet channel for the air charged with dust and g the collecting
chamber for the dust that has been beaten out.
In forms of construction hitherto employed the beating of the bags is effected
in the following manner the suspension arins h h of the bags are slowly lowered
by means of rotating cams, so that the bags hang slack and the space inside the

page_text: same is thereby reduced, whereupon the arms are suddenly raised and the rigid
form quickly re-assumed by the bags, so that a sudden increase of space occurs.
The beating is now effected in another manner, as the bags are only slightly
lowered, and the lowering and sudden rigid drawing follow one another many times
in rapid succession, whereby a powerful vibration or shaking of the bags is pro-
duced. Experience shows that, in this way a more thorough cleansing is effected.
The beating apparatus is driven by a pulley k connected to the intermediate
cog gearing which transmits the motion to the main shaft by means of
toothed wheels. The main shaft A carries cam discs o o¹ which are seated on a
boss common to both and a crank disc p, which by means of an intermediate
rod p¹ imparts a reciprocating motion to the pawl lever r which is pivoted to
the pin on the frame, and the pawl of which sets in motion a ratchet wheel R.
The ratchet wheel R is fixed on a shaft B arranged parallel to the main
shaft A. The shaft B moreover bears grooved discs C, one of which serves for
the lateral displacement of each pair of cams.
The groove n in the disc C is cam shaped in one ог more places and serves
for oscillating sideways of its pin a controlling levert rotably pivoted to the
pin on the frame G and which lever has a roller t¹ which engages in the groove n of
the disc C, and a fork 2 (Fig. 2 and 3) engaging in the boss of the cam discs o, and
thereby (as explained also by Fig. 2) moving the cam disc o either to the left (Fig. 2)
under the arm or the disc o¹ to the right under the arm h¹.
Whilst then the groove cam slides over the roller t¹ the cams of the disc o or o¹
effect in combination with the spring plate f the raising and lowering, in rapid
succession, of the particular arm (h or h¹) and thereby pull back the bags into a rigid
state.
In order that the lateral displacement of the cam discs o and o¹ may be effected
quickly, so as to prevent the cams from coming too soon into contact with the
levers h or h¹, a second pawl 8¹³ is arranged on the lever r, which pawl slides on a
smooth edge u of the wheel R as long as the roller t¹ runs in the regular part of the
groove, whilst shortly before the passing of the groove cam the pawl 8¹ falls into a
notch formed in the edge u of the wheel R, (as shown in Fig. 1) so that the wheel R
is rotated by means of the pawl 8¹ which moves quicker than the pawl 8, the result of
which is that the roller must quickly pass the slanting ascent of the groove cam.
If the wheel R be again turned round by the action of the pawl 8, the pawl & slides
again on the edge u until a fresh notch of the same has been passed.
In the form of construction here described what is essential and claimed as novel is
that the cam discs o o' are arranged on a special shaft and the ratchet wheel R with
the grooved disc C on a second shaft lying parallel to the first, and in this way the
object of the invention described in the opening of the specification is attained,
namely that for a large number of filtering bags only a simple locking and unlocking
apparatus consisting of a wheel R, pawl lever with pawls 8 81, and crank levers p p¹ is
necessary.
The shafts A B are guided in front of the filtering cases and carry, suitable to the
position of the suspension arms h h¹ for the filtering bags arranged in pairs or as a
pair, the cam discs o o¹ and each a grooved disc C. At the ends of the shafts A and B
or at a suitable middle position in the same the pulley k and the engaging and
disengaging mechanism R are arranged.
In order that in the case of a long row of filter bags (Fig. 5) the shaking of the
same may not occur simultaneously, but at suitable intervals, it is only necessary that
the grooved discs C should be adjusted or fixed on the shaft so that the cam parts of
the grooves pass in the suitable intervals of time from the roller of the controlling
levert of the cam discs and for this purpose the notches have to be formed in the
edge u of the ratchet wheel R for the pawl s¹.
Whilst a pair of filtering bags (for example, that which is on the left in Fig. 2) is
shaken, the suction action of the exhauster for the chambers of these is arrested by
means of the throttle valve d in the junction tube c. The valve d is fixed on a

page_text: shaft with pin d¹ which is bent and engages in a fork v of the controlling levert and
is drawn against the casing walls by means of a spring d2 as is shown by Fig. 3.
The bend in the pin d lies in the plane of the throttle valve flap or wing d, so
that, when the flap takes its middle position the tension of the spring d² is ineffective
whilst when the pin is rotated by the fork of the lever t, the spring draws the
valve d firmly against the wall of the tube c.
After the closing of the chamber of the pair of bags on the left, Fig. 2 the
exhauster continues to act on the pair at the right, but, as the partition w between
the two pairs of filters extends only to the bottom or floor in which the edges of the
bags are tightly fastened the effect of the suction will make itself so far evident also
in relation to the pair of bags at the left, as the air is drawn out of the chamber of
this pair of bags through the sides of the bags inwards and out of the lower opening
of the same into the lower opening of the adjoining pair of bags; thus, in the
chamber to the left a certain vacuum will be created.
This vacuum is now utilised in the following manner for the better cleaning of the
sides of the bags. In the cover of the junction tube c is a perforation y or y¹ for
each bag chamber and on the cover is a disc q firmly connected to the shaft of the
throttle valve d and having a part cut out to the extent of a fourth of a circle which
in the middle position of the valve d comes over both openings y y¹, but when the
disc is rotated sets free one of them-for instance y in Fig. 4.
In consequence of this opening there is a disturbance in the chamber of the pair
of bags on the left, the air presses through the side of the bag and materially assists
the beating action, whilst at the same time carrying off the dust.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. Improvements in dust filters with automatic shaking apparatus characterised by
cam discs which are arranged on a special shaft A in conjunction or in common with
a spring which effects the rapid raising and lowering of filtering bags a suspended
on arms h h¹, and thereby causes the dust to fall down the shaft A carrying the
driving pulley k or being driven thereby with the assistance of intermediate cog
gear; whilst a ratchet and pawl mechanism R is arranged on a second shaft B
parallel to the first, this second shaft moreover bearing the grooved disc C, which
with the assistance of the controlling levert displaces the cam discs o o¹ all for the
purpose of effecting the working of a large number of filter bags operated by a single
engaging and disengaging mechanism substantially as described.
2. In the dust filter described under Claim 1, the arrangement of a throttle valve
d actuated from the controlling levert of the cam discs o o¹ this throttle valve being
in the junction tube c for the exhauster; and the arrangement of air inlet openings
y y¹ in the tube c and a dise q opening and closing the same from time to time, for
the purpose after the closing of the throttle valve, of introducing air from without
into the bag chamber in which there is a vacuum and thereby to assist the operation
of cleansing.
Dated this 20th day of June 1800
WHEATLEY & MACKENZIE,
40, Chancery Lane, London, W.C., Agents.