U.S. patent number 3,844,750 [Application Number 05/345,651] was granted by the patent office on 1974-10-29 for dust collector bag mounting arrangement.
This patent grant is currently assigned to Flex-Kleen Corporation. Invention is credited to Frank M. Ray.
United States Patent |
3,844,750 |
Ray |
October 29, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
DUST COLLECTOR BAG MOUNTING ARRANGEMENT
Abstract
A dust collector bag cup mounting arrangement employs a helical
coil externally secured upon the bag cage for threaded cooperation
with an internal thread surface on a collar carried by the tube
sheet. The sleeve-shaped open end portion of a filter bag extends
in air tight relation between the helical coil and the internal
thread surface to provide an arrangement which achieves a more
effective seal in that it is compatible with the operating
environment and resistant to vibration while accommodating greater
manufacturing tolerances and reducing manufacturing costs.
Inventors: |
Ray; Frank M. (Hoffman Estates,
IL) |
Assignee: |
Flex-Kleen Corporation
(Chicago, IL)
|
Family
ID: |
23355906 |
Appl.
No.: |
05/345,651 |
Filed: |
March 28, 1973 |
Current U.S.
Class: |
55/379;
55/DIG.26; 55/302 |
Current CPC
Class: |
B01D
46/02 (20130101); Y10S 55/26 (20130101) |
Current International
Class: |
B01D
46/02 (20060101); B01d 046/04 () |
Field of
Search: |
;55/302,341,374,378,379,505,506,508,507,DIG.26,DIG.33,DIG.35
;285/313,251 ;210/463,483 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lutter; Frank W.
Assistant Examiner: Lacey; David L.
Attorney, Agent or Firm: Cagney; J. Patrick
Claims
1. In a dust collector that includes a tube sheet having a separate
mounting opening for each dust collector bag unit, each bag unit
including a bag cage having one end portion terminating in an axial
outlet and a bag having an open end sleeve portion closely
surrounding said end portion of the cage, an improved bag mounting
arrangement wherein said tube sheet carries a collar bordering said
mounting opening, said collar having an internal surface leading
from said tube sheet and defining an internal helical thread,
wherein said cage carries helical thread means secured externally
around said end portion thereof for threaded cooperation with the
internal helical thread of the collar to support said cage, said
cage has a main length portion of smaller diameter than helical
thread means, and wherein said bag is of a size to fit in snug
relation over said helical thread means to extend in air-tight
relation between said internal helical thread and said helical
thread means, and to extend in slack
2. In an arrangement as defined in claim 1 wherein the internal
helical thread on said collar and said helical thread means define
cooperating multi-turn tapered thread surfaces that are of
corresponding taper and of substantially equal and uniform pitch
and that have a major thread diameter clearance relationship to
provide an axially interlocked relation
3. In an arrangement as defined in claim 1 wherein the internal
helical thread on said collar and said helical thread means define
cooperating multi-turn thread surfaces each having a taper of about
8.degree., said helical thread means having a sufficiently smaller
major thread diameter than said internal helical thread on said
collar to provide an axially interlocked relation therebetween in
effecting compression of said bag.
4. In an arrangement as defined in claim 1 and wherein said helical
thread means has an intermediate portion of maximum major thread
diameter and has end sections tapering inwardly from said
intermediate portion towards each
5. In an arrangement as defined in claim 1 and wherein said collar
is
6. In an arrangement as defined in claim 1 wherein the internal
thread on said collar defines a tapered helical thread, and wherein
said helical thread means has an intermediate portion of maximum
major thread diameter and has end sections tapering inwardly from
said intermediate portion towards each end, each end section
corresponding in pitch and taper to
7. In an arrangement as defined in claim 1 wherein said collar
defines an internal helical thread having an intermediate portion
of maximum major thread diameter and having end portions of
multi-turn inwardly tapering configuration and wherein said helical
thread means defines a multi-turn thread surface of corresponding
taper and of sufficiently smaller major thread diameter to provide
an axially interlocked relation therebetween in
8. In an arrangement as defined in claim 1 wherein said cage has
lengthwise rods extending through said helical thread means and
having outwardly offset bend portions presenting a profile matching
the internal profile of said helical thread means and a gas nozzle
member disposed within said end
9. In an arrangement as defined in claim 1 wherein the open end
sleeve portion of said bag includes a reverse bend end cuff portion
projecting axially into said end portion of the cage and a gas
nozzle member disposed in snap fit relation within said end portion
of the cage to clamp said bag
10. In an arrangement as defined in claim 1 wherein the open end
sleeve portion of said bag includes a reverse bend end cuff portion
projecting axially into said end portion of the cage and a gas
nozzle member having circumferentially spaced fins having outwardly
opening notches, said nozzle member being disposed in said end
portion of the cage with said notches of said fins in mechanically
interlocked snap fit relation thereto
11. In an arrangement as defined in claim 1 wherein said helical
thread
12. In an arrangement as defined in claim 1 wherein said cage has
lengthwise rods extending through said coil and having outwardly
offset bend portions presenting a profile matching the internal
profile of said helical thread means, said rods terminating on the
end turn of said helical wire coil and a gas nozzle member disposed
within said end portion of the cage, said gas nozzle member
disposed within said end portion of the cage, said gas nozzle
member having a peripheral helical flange mating with said end turn
and having circumferentially spaced fins provided with outwardly
opening notches for mechanical interlocking relationship with
13. In a dust collector that includes a tube sheet having a
separate mounting opening for each dust collector bag unit, each
bag unit including a bag cage having one end portion terminating in
an axial outlet and a bag having an open end sleeve portion closely
surrounding said end portion of the cage, an improved bag mounting
arrangement wherein said tube sheet carries a collar bordering said
mounting opening, said collar having an internal surface leading
from said tube sheet, and defining an internal helical thread,
wherein said cage carries helical thread means secured externally
around said end portion thereof for threaded cooperation with the
internal helical thread of the collar to support said cage, said
internal helical thread on said collar and said helical thread
means defining cooperating multi-turn tapered thread surfaces, said
tapered thread surfaces being of corresponding taper and of
substantially equal and uniform pitch, and wherein said bag extends
in air-tight relation between said internal helical htread and said
helical thread means, said helical thread means having a
sufficiently smaller major thread diameter than said internal
helical thread on said collar to effect compression of
14. In an arrangement as defined in claim 13 wherein each of said
helical thread means and said internal helical thread have a taper
of about
15. In an arrangement as defined in claim 13 and wherein said
helical thread means has an intermediate portion of maximum major
thread diameter and has end sections tapering inwardly from said
intermediate portion
16. In an arrangement as defined in claim 13 and wherein the
internal thread on said collar defines a tapered helical thread and
said helical thread means has an intermediate portion of minimum
major thread diameter and has end sections tapering outwardly from
said intermediate portion towards each end, each end section
corresponding in pitch and taper to
17. In an arrangement as defined in claim 13 and wherein said cage
has lengthwise rods extending through said helical thread means and
having outwardly offset bend portions presenting a profile matching
the internal profile of said helical thread means and a gas nozzle
member disposed within said end portion of the cage in snap fit
relation to said helical
18. In an arrangement as defined in claim 13 and wherein said cage
has a main length portion of smaller diameter than said end portion
and said bag is of a size to fit in snug relation over said helical
thread means and in
19. In an arrangement as defined in claim 13 wherein said collar
has an internal knuckle groove defining said internal helical
thread, said internal helical thread having a groove to groove
spacing of about the
20. In an arrangement as defined in claim 13 wherein said thread
means comprises a multi-turn wire coil having a turn to turn
spacing of about the same dimension as the wire diameter and
wherein said collar has an internal knuckle groove defining said
internal helical thread of a size to receive the bag and the wire
coil in snug axially sealed and interlocked relation, with said
internal helical thread having an intergroove surface of about the
same dimension as the local thread ridge of said wire for helical
sealing contact with the bag.
Description
BACKGROUND OF THE INVENTION
In dust collectors (for example, of the pulse jet reverse flow
cleaning type), a large number of sleeve type filter bags are
suspended from a tube sheet, each bag being suspended by a separate
bag cup individually secured in air sealed relation to the tube
sheet. In the pulse jet type of dust collector each bag cup is
fitted with an air nozzle which is also to be air sealed relative
to the bag cup and the tube sheet. A bag cage is supported from the
bag cup. The filter bag surrounds the bag cage and has an open end
sleeve portion which may be sealed to the bag cup by means of
clamps or which may be mechanically clamped between the end of the
cage and the bag cup.
In some instances, such dust collectors may incorporate as many as
500 filter bag units, each having a bag cup and air nozzle assembly
to be individually sealed to the main tube sheet structure. One of
the most time-consuming and expensive fabrication operations in the
manufacture of dust collectors arises in connection with the
mounting of each bag cup assembly in air sealed relation to the
tube sheet. In addition to the assembly problems associated with
manufacture, there are problems involving replacement of the filter
bags in the case of these prior art arrangements. Other features
which have presented problems in the prior art devices include the
difficulty of maintaining an adequate seal, particularly under
vibration conditions and under conditions where the gas or
particulate media being handled present an environment that cuases
chemical attack on rubber seals or that is of such high temperature
as to cause degrading of the seal. The variety of applications have
required that the prior art seal arrangements be of specialized
design. Stocking problems are unduly multiplied in order to afford
compatibility of material with the environmental conditions.
SUMMARY OF THE INVENTION
The present invention seeks to eliminate the problems described
above by providing an arrangement that is less expensive to
manufacture, easier to maintain and requires less parts, while
improving the sealing action and assuring compatibility with the
environment, all without requiring excessive stocking of
components.
In accordance with the present invention, dust collectors are
provided with an improved bag mounting arrangement wherein the tube
sheet includes a collar bordering and defining each separate
mounting opening therein, each collar having an internal surface
presenting an internal helical thread, wherein the cage carries a
mating helical thread member secured externally arount its open end
portion for threaded cooperation with the internal helical thread
of the collar in supporting the cage and wherein the bag extends in
air tight relation between the collar and the mating helical thread
member. In this arrangement sealing is achieved completely by the
bag which is comprised of a material matched to the environmental
needs of the application so that chemical and temperature effects
on the sealing are avoided.
The helical thread member is slightly larger in major thread
diameter than the cage and is sized to afford a snug fit with the
bag at the sealing area to eliminate the tendency of wrinkling of
the seal while the remainder of the bag is slack relative to the
cage to facilitate application of the bag upon the cage.
In the presently preferred embodiment the internal helical thread
of the collar is tapered and the helical thread member is in the
form of a coil that is double tapered in that it has an
intermediate portion of maximum fixed diameter and tapers inwardly
toward each end so that the same construction can be used in both
top removal and bottom removal type dust collectors. The taper of
the collar and the coil allows greater manufacturing tolerances as
between the coil size and the collar size and allows the same
structure to be used with bags of various thicknesses.
In the pulse jet type dust collector to which the invention is
particularly directed, an air nozzle member (preferably a venturi
nozzle) is mounted in snap fit relation within the open end of the
cage. The end portion of the bag is provided with a reverse bend or
bag cuff which is gripped between the interior of the cage and the
nozzle member to effect sealing at that area. More particularly,
the nozzle member is provided with circumferentially spaced
peripheral notches that engage the end turn of the coil with the
bag cuff therebetween to complete a mechanical interlock and
provide air tight sealed relationship between these parts.
A number of modifications in the collar and helical thread member
arrangement are disclosed to illustrate additional embodiments of
the invention.
Other features and advantages of the invention will be apparent
from the following description and claims and are illustrated in
the accompanying drawings which show structure embodying preferred
features of the present invention and the principles thereof, and
what is now considered to be the best mode in which to apply these
principles.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a vertical section illustrating a bag mounting
arrangement in accordance with this invention as applied to a pulse
jet type collector;
FIG. 1A is an exploded perspective view better illustrating the
arrangement of the top of the bag cage and the venturi nozzle;
FIG. 2 is an enlarged fragmentary detailed view of the sealing
relationship of the bag between the mating threads on the tube
sheet collar and the cage support coil;
FIG. 3 is a fragmentary perspective view of a bail type handle for
the venturi nozzle;
FIG. 4 is a fragmentary vertical sectional view illustrating an
alternative tube sheet collar arrangement;
FIG. 5 is a view of a helical thread sleeve for use in place of the
cage support coil;
FIGS. 6, 7 and 8 are diagrams illustrating alternative bag mounting
arrangements; and
FIG. 9 is a vertical sectional view illustrating another embodiment
utilizing a straight collar thread. Definitions;
Major thread diameter
is the diameter to the outside region of the helix defined by the
thread surface
as applied to the helical thread means 15 (or 15' in FIG. 5) it is
represented by the dimension line d.sub.1 in FIGS. 2 and 5
as applied to the internal helical thread of the collar 10C it is
represented by the dimension line d.sub.2 in FIG. 2
Local thread ridge - is the width of the thread ridge of the
helical thread means 15, 15'
as applied to the wire coil 15, it is represented by the dimension
line d.sub.3 in FIG. 2
as applied to the sleeve 15', it is represented by the dimension
line d.sub.4 in FIG. 5.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring now to the drawings and particularly to FIG. 1, a portion
of a perforated tube sheet designated generally at 10 has a
separate mounting opening for each bag unit 11 only one of which is
shown in the drawing. The region, indicated at 12, above the tube
sheet 10 is the clean air plenum and the region, indicated at 13,
below the tube sheet 10 is the entrance plenum.
In the preferred embodiment, each bag mounting arrangement utilizes
a collar 10C having an internal surface 10S leading from the plane
of the tube sheet and defining an internal helical thread of single
taper, a conventional wire cage 14 consisting of a set of internal
wire rings 14I interconnected by a set of circumferentially spaced
lengthwise extending external wire rods 14E, a helical threaded
member in the form of a coil 15 secured externally on the cage for
threaded cooperation with the collar thread and a bag 16 extending
in sealing relation between the collar thread and the helical coil
15 and having a reverse bend portion 16C defining a bag cuff that
projects into the open axial outlet of the cage 14.
In the case of a pulse jet type dust collector which is illustrated
herein for purposes of specific disclosure, a gas nozzle member 17,
here represented as being a venturi type, is mounted in snap-fit
clamping relation within the open end of the cage to engage the bag
cuff 16C between the cage 14 and the venturi nozzle member.
Generally, in the prior art, the bag cages 14 used a peripheral gap
or recess near the top to facilitate reception of a bag clamping
ring which is accessible from only one side of the tube sheet. The
present cage and bag mounting arrangement may be identical for both
top removal and bottom removal types of dust collectors. The
helical coil 15 which is shown as consisting of substantially six
complete turns, is of the same material as the cage 14 and may be
of the same or of larger or smaller gauge than the wire rod
material that constitutes the cage. The coil 15 is spot welded to
the cage at spaced locations and has its opposite ends 15E bent
inwardly of the periphery of the cage to prevent snagging with the
bag.
It will be noted that the lengthwise cage rods 14E have outwardly
offset bent portions intermediately of their upper ends to present
a profile that matches the internal profile of the coil 15 to
facilitate spot welding of the coil to the cage. The upper ends of
the cage rods 14E terminate at the points of juncture with the end
turn of the coil 15 to define a helical end profile for the cage.
Correspondingly, the venturi nozzle 17 has a helically profiled top
flange 17F to achieve full length snug seating of the venturi
flange on the end of the cage.
In the illustrated arrangement, the venturi nozzle 17 is shown with
a set of circumferentially spaced ribs 17R having notches 17N to
cooperate with the top end turn 15T of the coil to clamp the bag
cuff 16C in mechanically interlocked sealed relationship between
these parts.
For the pulse jet type arrangement shown in FIG. 1, the bag 16 is
applied to the cage 14 and the venturi 17 is mounted in snap fit
relation as shown and the entire assembly then is threaded into the
tube sheet from the bottom. Since the invention also contemplates a
top removal type dust collector (see FIG. 6), the venturi 17 may be
equipped with a hinged bail 17B which is shown in elevated position
in FIG. 1A wherein it may serve as a handle for applying torque
either to install or remove the unit. When installed, the bail 17B
is swung out of the path of the air stream. Since the assembly of
the venturi nozzle 17, the cage 14 and the bag 16 is carried out
first, the bag cuff 16C is easy to secure even if it is as short as
one-half inch, thus providing some saving on bag material.
The coil 15 being on the outside of the cage presents the largest
diameter region and is sized relative to the bag to provide a snug
fit for the bag at the region of the coil so that any tendency for
the bag material to wrinkle is eliminated.
In the preferred arrangement illustrated in FIG. 1 for purposes of
disclosure, each collar portion 10C is an integral, upwardly
converging extension of the tube sheet and, being extruded from the
tube sheet stock, is of slightly less thickness than the tube sheet
10. The illustrated collar 10C is provided with a knuckle thread to
cooperate with the wire coil 15.
In the preferred embodiment illustrated in FIG. 1, the collar
projects upwardly from the plane of the tube sheet and the knuckle
thread on the interior surface of the collar 10C is a downwardly
flaring helical thread of uniform pitch and and wire coil 15 is
shown with its intermediate turn 15I being of larger major thread
diameter than its end turns to defing a double tapered coil. The
three-turn end sections of the coil 15 are matched in size and
pitch so that the coil is reversible. As is explained hereinafter,
the double tapered coil 15 may be threaded into the collar 10C
either from the top or the bottom depending upon the arrangement of
the collar. Independently of the double taper concept there is
advantage in providing a tapered profile for both the collar and
the coil in order to accommodate greater manufacturing tolerances
between these parts and in order to adapt the parts for use with
bags of various thicknesses.
The double tapered coil arrangement is normally sized so that the
bag seal is achieved as the helical coil and bag seal in the
knuckle thread as shown in FIG. 1. Thus, the coil is intended to
come to a stop when the mating threads seal the bag material. Even
so, the arrangement allows a cage, that is installed from the
bottom (see FIG. 1), to be removed from the top. For example, where
a cage has been inserted from the bottom, it may be removed from
the top by first screwing the cage and coil downwardly sufficiently
to allow the bag to be freed and withdrawn. There is then
sufficient clearance to allow the cage and coil to be removed
through the top.
The threaded arrangement of this invention wherein the bag material
itself serves as the primary seal requires a coil of at least one
turn. In the illustrated arrangement each end section of the coil
15 presents substantially three turns to enable one element to be
used either with top or bottom removal type collectors while still
insuring sealing. Two of the active turns normally act as a seal
and the third is provided to accommodate bag thickness tolerance.
The present arrangement wherein the bag material acts as the seal
is made wrinkle free at the sealing region in that the bag is
snugly sized to the coil diameter so that the remainder of the bag
is slightly slack relative to the cage. This slack relationship
makes it easy to apply the bag over the cage. Since the bag
material is selected to be compatible with the internal environment
in the particular collector, the bag seal inherently resists
chemical attack problems and/or high temperature problems such as
plague the rubber seals that have been used in some varieties of
prior art. The standard wire cage construction that has previously
been used is particularly suitable to the coil and threaded
mounting arrangements of this invention because the cage wire is
capable of distorting slightly to accommodate tolerance variations
or out of roundness such as sometimes occur either during
manufacture or from damage during use. Such minor defects will not
impair the threaded sealing relationship.
For purposes of detailed disclosure, a particular embodiment
utilizes threads having an 8.degree. angle of taper and having a
pitch of three threads per inch. The coil is of one-eighth inch
diameter wire, this presently being optimum for strength and for
compatibility with existing cage designs which employ one-eighth
inch wire stock. This relatively close thread spacing achieves the
optimum number of engaged threads, preferably three full turns to
prevent any tendency of the cage to cock relative to the collar and
to insure a long enough bag seal region between the cage and
collar. The values given here permit use of bags of different
thickness without significant variation in the axial position of
the cage relative to the collar. The definiteness of the axial
position is important for assuring proper pulse jet cleaning
action. Typically, if the bag fabric has a thickness of
one-sixteenth inch uncompressed, it will have a thickness of one
thirty-second when compressed in sealing relationship. For a tube
sheet of 10 gauge stock the extruded collar may be drawn to a
length of 1 1/4 inch to utilize a double tapered knuckle thread,
each section of which is in excess of one half inch in length to
accommodate approximately two coil turns in active sealing
relation. For one eighth inch diameter wire coil stock, the knuckle
groove 10G of the collar is of one sixteenth inch radius while the
inter-groove thread surface 10S is flat to insure adequate
clearance for the vertical cage rods 14E when the coil wire is
recessed in the knuckle grooves. In this relationship as shown in
FIG. 2, where the knuckle grooves span a 60.degree. angle. the
primary seal is effected by compressing the bag 16 against the side
faces 10F of the groove to develop an axial lock. The bag is held
stretched against the flat knuckle surface 10S to effect a
secondary seal relative to potential leakage along the helical path
defined by this flat inter-groove surface. The term pitch or pitch
spacing as used herein refers to the distance represented by the
dimension line P in FIG. 2.
For the described arrangement with one eighth inch wire the nominal
wire pitch of three turns per inch insures proper bag sealing
between the cooperating thread structures and provides sufficient
seal length while controlling axial position. If the pitch spacing
were substantially less, it would be difficult to achieve proper
knuckle engagement and therefore it would be difficult to achieve
positive sealing. If the pitch spacing were substantially greater,
the number of sealing turns would be reduced to lose the sealing
action and to lose the axial positioning accuracy.
In the case where the gas or particulates present a corrosive
environment, the arrangement is well suited to eliminate such
problems by coating the cage wires with epoxy. The threaded
mounting arrangement of this invention accommodates epoxy coated
cages without likelihood of damage to the coating, whereas the
clamp type mountings of the prior art excessively distort the cage
and cause localized cracking of the epoxy coating leading to short
cage life.
A number of modified arrangements of the invention are illustrated
in FIGS. 4 through 9. For example, in FIG. 4 a bottom removal
arrangement is shown wherein the collar 10C is separate of and
beneath the tube sheet 10 and is secured by a bolt and nut fastener
assembly 20. The collar 10C has a machine formed knuckle thread
surface 10S of the same taper and sizing relationships described
previously. In FIG. 5 the helical thread means 15 is shown as a
hollow sleeve construction similar to that of a lamp bulb base. The
threaded sleeve 15 is shown as having its intermediate region of
maximum major thread diameter and as having a tape and pitch
spacing comprable to that previously described in connection with
the coil 15. The vertical legs 14E of the cage are again shown with
a bent profile like that of the sleeve 15; however, in this
instance, the ends of the legs 14E terminate in a common horizontal
plane at the upper extremity of the sleeve 15.
An alternative arrangement is shown in FIG. 6 wherein the
construction is essentially identical to that of FIG. 1 except that
the tube sheet 10 has its collar 10C projecting downwardly. It will
be apparent that the double tapered coil 15 is suitable for use
either with the upward collar shown in FIG. 1 or with the downward
collar as shown in FIG. 6. Actually, the same tube sheet may be
used for FIGS. 1 and 6. For convenience in disclosure the bag is
omitted in the FIG. 6 illustration.
As shown in FIG. 7, a double tapered collar 10C formed integrally
with the tube sheet 10 extends downwardly from the tube sheet
whereas in FIG. 8 the double tapered collar 10C is shown projecting
upwardly from the tube sheet. Thus, the same tube sheet may serve
for application either as shown in FIG. 7 or in FIG. 8. In each of
these arrangements the double tapered collar has a threaded
configuration, taper and pitch spacing and major thread diameter
corresponding to that previously described. Each of the double
tapered collar arrangements of FIGS. 7 and 8 can accommodate either
a top removal or bottom removal arrangement and the same coil
configuration may be used with either arrangement thus minimizing
inventory requirements.
Finally, as shown in FIG. 9, a tube sheet 10 may employ a straight
collar having a straight helical thread to cooperate with the
tapered coil arrangement previously described, a pair of such
collars each being designated 10C. Straight collars provide less
effective sealing length but straight collars facilitate removing a
coil assembly from the top even if it were inserted from the bottom
and vice versa.
Thus, while preferred constructional features of the invention are
embodied in the structure illustrated herein, it is to be
understood that changes and variations may be made by those skilled
in the art without departing from the spirit and scope of the
appended claims.
* * * * *