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' July-19, 1949.
Filed June 11, 1945
2 Sheets-Sheet 1
pf: .1
} EVE 2710175
M4244” // 34o IlA/t'
lkww E. fall/ill.”
Patented July 19, 1949
* 2,476,582
.JVilliam H. Browne and Arnold E. Pavlish, Co
lumbuskqhio, assignors, by mesne assignments,
\.__to Houglaille-Hershey Corporation, Detroit,
Mich, a corporation of Michigan
Application J line 11, 1945, Serial No. 598,892
12 Claims. (Cl. 28-—73)
This invention relates to improvements in a
ing an air cleaner?lter unit of economical ma
terial, it being also suf?ciently economical to
practice the method and produce a ?lter unit so
low in cost as togwarrant replacement of a used
dirty unit by a new one, rather than the expense,
method of making a ?lter unit, and more par
ticularly to the method of making a ?lter unit
highly desirable for use in liquid bath air cleaners
of the type used in connection with the intakes
to internal combustion engines, air compressors
"labor and material‘neeessary to cleanse the dirty
and similar apparatus, although the invention
may be practiced to- produce ?lter units having
Also an object of the instant invention is the
‘ other uses, as will be apparent to one skilled in
' provision of a new method of making a ?lter for
10. air cleaners and similar apparatus, including the
the art.
In the past, many and various types of ?lter
steps of aligning vegetable ?bers longitudinally
units for air cleaners and similar apparatus have
of the resultant unit, bonding the ?bers together,
been ‘developed, and these units have been pro
and cutting an element of predetermined size
duced by many and various methods. Insofar as
from the aligned and bonded ?bers.
~ '
commercial usage is concerned, by far the greater 5 Another object of the instant invention ‘is the
number of these formerly known ?lter units uti
lized cactus ?ber, curled cattle-tail hair, various
formations of screens, or wavy metallic wire as
a ?lter medium. Cactus or pineapple ?ber ?lter
units, commonly referred to as “Tampico”'?lters,
,were objectionable in that channeling resulted
when these units were used in air cleaners. Cat
tie-tail hair ?lter units were objectionable in’
that these units matted when used in oil bath
provision of a new method of making a ?lter unit,
including the steps of aligning vegetable ?bers
longitudinally of the resultant unit, crimping the
?bers, forming a bundle of the crimped ?bers, and
cutting the bundle to provide a ?lter unit of a
desired length.
A'further feature of the instant invention re
sides in the provision of a new and novel method
Screen formations
of producing a ?lter unit including the steps of
arranging vegetable ?bers to form a substantially
alone would not give a desirably high efllciency.
continuous elongated‘ bundle of predetermined
Perhaps the best all-around ?lter medium here
diameter, and applying 'a covering over the bundle
as the bundle is being made in a substantially
or liquid bath air cleaners.
tofore known was the wavy metallic wire me
dium especially when formed into a mass, but
continuous and complete operation, and then
that medium is objectionably expensive. In addi 30 severing the covered bundle into ?lter units of
tion, insofar as we are aware, no ?lter units for
a liquid bath air cleaner, and especially an auto
motive air cleaner, have heretofore been produced
.by any method sui?ciently economically to war
desired length.
Still a further feature of the instant invention
resides in the provision of a new and novel method
of making a ?lter unit including the steps of ar
rant discarding of a dirty ?lter unit and replace-v 35 ranging vegetable fibers in substantially parallel
relationship, ?reproo?ng the ?bers, bonding the
ment thereof by a new unit, rather than go
through the operation of cleansing the dirty unit ‘ ?bers, and then shaping and‘blnding the bonded
already in use.
With the foregoing in mind, it is an important
?bers into a mass to form a ?lter unit of prede
termined size.
object of the instant invention to provide a new 40
Still another object of the instant invention is
and novel method of making a ?lter element or
the provision of a new and novel method of mak
unit for liquid bath air cleaners and similar ap
ing a ?lter unit from vegetable ?ber, including
the steps of substantially paralleling the fibers,
?reproo?ng the same, crimping the ?bers, and
provision of a new and novel method of economi 45 then heat treating the crimped ?bers, taking ad
cally producing a ?lter unit for air cleaners and
vantage of the moisture provided by the ?re
» similar apparatus by forming the unit of vege
proo?ng to steam the crimped shape into the
Another object of the instant invention is the
table ?ber.
It is also an object of this invention to provide
It is also an object of this invention to pro
a new and novel method of making a ?lter unit 50 vide a new and novel method of making ?lter
out of sisal ?ber, the unit being highly desirable
units for air cleaners and similar apparatus,
for use in connection with liquid bath air cleaners
which method includes the steps of arranging
and similar apparatus.
vegetable ?bers into an elongated substantially
A further feature of the invention resides in
continuous core of vpredetermined size, binding
the provision of a new and novel. method of malt-
such. core, so that it will retain its shape when
severed into smaller portions, and cutting the
bound core into ?lter units of predetermined
While some of the more salient features, char
acteristics and advantages of the instant inven
tion have been above pointed ‘out, others will
method of ?reproo?ng is impregnation of the
?bers with a water-soluble ?reproo?ng or ?ame
proo?ng material that is ?re resistant. One
satisfactory substance for this purpose is a 20%
solution ‘of ammonium sulfamate in water, and
‘the ?reproo?ng operation may generally be ac
complished by immersing the carded ?bers in such
a solution, and the ?bers may be effectively ?re
proofed ‘by such an immersionof approximately
become apparent from the following descrip
tions of preferred embodiments of the method or
process of making a ?lter unit, taken in conjunc
tion with the accompanying drawigs in which 10 ?ve minutes duration, although in many cases I
less time is necessary.
apparatus employed in the practice of the method
Perhaps the optimum time for effecting the
is diagrammatically indicated, and in which:
?reproo?ng operation is just after the raw ?bers
Figure 1 is a fragmentary side elevational view
have been carded and before these ?bers have
illustrating diagrammatically steps in one em
given any ultimately desired shape, as in
bodiment of the instant invention;v
15 been
dicated at 2. If the ?reproo?ng takes place prior
Figure 2 is a top plan view of a ?lter unit re
to the carding operation, a considerable amount
:ilting from the practice of the instant inven
of the solution is wasted on the foreign material
which is subsequently removed by the carding
Figure 3 is a side elevational view of the unit
20 operation. After the ?bers have been crimped,
of Figure 2;
or otherwise shaped to a desired con?guration,
Figure 4 is a fragmentary plan view illustrating
immersion of the ?bers in a solution containing
a variation in the later steps of the method shown
water frequently destroys the shape of the ?bers
in Figure 1;
to a material extent. After the ?bers have been
Figure 5 is a fragmentary plan view of general
' character as that of Figure 4, illustrating another 25 bonded by a suitable plastic, effective ?ameproof
ing or ?reproo?ng by the simple immersion op
variation in the practice of the method;
eration is extremely difficult, and in some in
Figure 6 is a fragmentary plan view, illustrat
stances would be ineffective.
ing a still di?erent step in completing the re
It will be understood that the above method
sultant ?lter unit to provide a unit of slightly
different character than those previously shown; 30 of ?reproo?ng is only a preferredxmethod, and
fireproo?ng'may be accomplished in other ways,
Figure '7 is another fragmentary side eleva
such as by precipitation of an insoluble material
tional view indicating diagrammatically the man
within the ?ber to be fireproofed, or by the
ufacture of a ?lter unit in accordance with the
of a ?re-resistant coating on the sur
instant invention where crimping of the ?bers is .
35 face of the ?ber, but the use of a water soluble
Figure 8 is a fragmentary magni?ed plan view ‘ material is satisfactory and economical and avoids
the risk of a surface coating ?aking o? during
of a group of ?bers after the initial crimpingf
' Figure 9 is a view similar in character to Fig
ure 8 indicating the disposition of the ?bers in
the resultant. ?lter ' unit.
The instant method may be practiced to pro
duce a ?brous or. stranded ?lter unit in which
subsequent use under vibration.
Following the ?reproo?ng operation, the im
pregnated ?ber mat is then preferably passed
.between pressure rolls 3 to remove the excess
?reproo?ng solution. Then the mat of ?bers
' may be dried either in an oven as
indicated at i
or by some other method of applying su?icient
the ?bers or strands are of various kinds of vege
table material, various kinds of plastics, or of 45 heat for the purpose. The drying operation can
be' effected at a temperature in the neighbor
metal, and where the term "strand” is used here
hood of 180° to 200° F. Of course, the tempera
in and in the appended claims, the same is to be
ture required, as well as the time required de
understood as including?bers or strands com
posed of any of such materials. An economical 50 pend upon both the amount of water present and
the amount of ?ber being treated at any partic
and highly satisfactory basic material for the.
time. In general, the above range of tem
?lter unit is sisal ?ber, or a vegetable ?ber of ‘
peratures prove satisfactory, and the drying time
equivalent characteristics when used as a ?lter
may range from a minute to an hour, usually ?ve
medium, and for the purpose of clarity, the in
or ten minutes being su?icient to drive out the
stant method will be explained on the assump
water content of the applied ?reproo?ng solution.
tion that sisal ?ber is being used to make the
After the drying operation, the mat is then
?lter unit.
treated with a thermo-plastic or a thermo-setting
‘ _ Sisal or equivalent vegetable ?ber may be ob
plastic which acts as a bonding medium for the
tained in bales of raw ?bers, rather limp, and
from two to four feet in length. As received,' 60 ?bers. A suitable method of application for
the bonding medium is by spraying the mat,
the raw ?ber frequently retains part of the leaves
preferably both sides simultaneously with the
from which it was derived, and therefore a card~
aid of suitable nozzles‘ 5 and 6. The plastic thus
ing operation is preferable to remove the un»
will impregnate the ?ber. . The bonded ?ber
wanted woody inclusions.
At the outset, the ?bers, approximating three 65 will be somewhat more brittle when a thermo
setting plastic is used than when a thermoe
feet in length, may be taken from the bale or‘
other initial supply, and carded into a broad
?at mass, indicated at l in Figure 1, having an
extremely high percentage of oriented ?bers, such
plastic is used. Suitable materials for this bond
ing operation include resinous agents such as
a copolymer of vinyl chloride with vinylidene
chloride, and in some cases with an alkyd
as 99.9%. This may be accomplished with the
70 thermo-pl'astic, although other plastics may also
aid of a suitable carding machine, not shown.
be satisfactory, the above being mentioned by
Inasmuch as sisal ?bers burn rather readily, it
of example only and not by way of limita
is substantially necessary to ?reproof or flame
tion. - It is, of course, more advantageous in con
‘proof them, especially for use in an air cleaner
nection with the present invention to use a vinyl
' or the type associatedwith internal combustion
7'5 resin or an alkyd resin because they are soluble
engines where back?re may occur. One suitable
canoes ‘a . '
After the plastic hasv set, the resultant?lter ele
in organic solvents, rather than'us'e a water sol
uble -resin and risk dissolution and loss‘ of some
of the previously applied water-soluble ?re
went‘ I‘, seen in Figures 2 and 3 may be removed
from its respective mold... It is desirable to 'have
proo?ng agent.
such a mold'slightly oversized, so that there will
It is desirable to have the resultant bond ‘be-‘
tween the ?bers resilient tov some extent so" that
be a‘ tight frictional contact between the ?lter , v 5
units, by virtue of their. inherent resiliency,~and
the'?iltimate ?lter housing means in which-they
' theresultant ?lter unit possesses inherent re'-_
siliency so that the ‘unit will have the advan-,
tages of being self-‘sealing‘when pressed into a
are to be positioned for use.
Another way of shaping or packing the ?bers" ‘
?lter holdingelement in an air cleaner by virtue
of its resilient pressure against the wall of the
holding elementfand so that the unit will be
is illustrated in Figure 4 and includes. forming
the mat into what might be termedwa cylin
drical bundlepwhichr as-stated above.» will be
better enabled to resist compacting after long
substantially continuous. This operation would
usage. The vbond obtained is satisfactory if it
occur after the mat:l 'has passed the'plastic spray
has a resiliency generally between that of phenol 15 nozzles 5 and 6. In forming the bundle, the
formaldehyde resins, which mark the harder type,
mat may be shaped through-properly disposed
and the alkyd resins,"which represent the more
wheels or rotary guide members l5 and L16 .and
urged through a. converging nozzle l1 until acon- I
The relatively high melting point of vinyl ch10
tinuous bundle I 8 of'th'e desired cross-sectional
rides, however, requires the packing of the fibers 20 area and shape is provided- The bundle l8 may '
into the ultimately desired shape of the ?lter unit' = then be passed through a drier l9, and after leav-'
while the ?bers are still wet with the plastic sol-'
in: the drier end portions of the bundle'i'nay be r \ .
vent. On the other hand, the alkyd resins may
sheared off by a cutting means indicated at 20,
be permittedto dry before the ?bers are packed '
and each end- portion will be one of the ?lter~"==-*
into the desired shape of the ultimate ?lter unit. 25 units l4.
Of course, the bonding plastic might be ap
In one form of the instant invention, a covering "
plied to the ?bers either before or after the ?bers
may be provided over‘ that continuous ?ber bundle
are packed intothe ultimate shape of the filter
II, by way of spirally winding paper board 21
unit by the process of immersion. ,‘However, itwis
around the bundle until an enclosing tube 22 is
preferable to spray the plastic on the ?bers prior 30 formed‘; as shown in Figure 5. ‘The tube is wound
to packing in ‘?lter unit shape, because of the
upon the extruded bundle as it leaves the shaping
high eifective weight» of ?lters thus produced: mechanism so that the entire operation "is prefer
In general, the dust removing, e?iciency of the
ably continuous. If desired, the tubing may be
?lter unit increases with .an increase inweightv
formed seamless. In providing the tubular cov
ering, the shaped ?ber acts as a core during the‘
of ?bers employed‘ in the building of the'unitr
Where the ?bers are lumped,'or compacted’ so as
to produce in effect a single strand of multiple
. making-oi’ the tube.
The entire arrangement is then subjected to a
thickness, or a single compact matof strands, the
heat treatment or the equivalent in the drier is
e?iciency of the unit is thereby‘ decreased.
to set the applied plastic, remove any excess sol-'
Therefore, since ‘greater uniformity may be 40 vent and thus bond the ?bers together and also to
achieved by spraying the individual ?bers prior
the tubular covering 22 through fusion of the
to packing them in a ?lter unit shape, the effec
vplastic thereon at points of contact. It will be
tive weight of the'unit produced in this manner
understood that the plastic has impregnated the
is greater than the effective weight of units‘
fibers, provided the material used is a vegetable
bonded by means of an immersion bath or by 45 ?ber such as sisal, and not a metallic strand, and
spraying subsequently to packing in ?lter unit
thus the ?bers are provided with adequate stiff
ness while being bonded together into substan
It will be appreciated that all of the steps so ‘ tially a uniform ?lter mass. The heat treating
far described in connection with the instant'in
operation may satisfactorily be accomplished in a
vention may be accomplished in a single piece of 50 time of one-half to one hour, and at a tempera
apparatus. That is, a carding machine may be '
ture of 250 degrees to 300 degrees F., depending
provided and equipped with su?icient extra ‘ap
upon the particular plastic used, these ranges be
.paratus to accomplish all these steps in one con
ing given by way of example and not by way of
tinuous movement of material through the-"ma-‘
chine; During the progress through the carding
machine, the ?bers become joined at the ends
so that the ultimate ?ber mat is substantially
endless and continuous.
Following the application of the plastic bond
ing material, the mat of- ?bers is next shaped or
packed into the form of the ultimate ?lter‘unit.
Of course, the ?bers may be cut to the desired
7 length and then packed within a moldof steel,
glass, or other suitablematerial of the shape and '
After the last heating operation, the elongated
- tube with its ?ber core may be severed into desired
lengths, each length constituting an individual
?lter elementor unit “a. If end screens for the
unit are desired,'they may be used, but with a unit
of the character made under the present method,
no such end screens are necessary, the ?bers or .
strands being bonded together and to the tubular
cover encasing them. Such a unit is substantially
uniform in character, and provides a high ?lter
substantially of the size of the ultimate ?lter unit. 65; ing e?iciency. \ The entire ‘unit may be easily
This’may be accomplished by way' of a suitable
slipped into the casing-of-an air cleaner or similar
shearing mechanism diagrammatically‘ indi
apparatus, and held in position by any desired
cated at ‘l, and relatively short lengths of ?bers
8 may drop upon‘ a conveyor 9 and be advanced
into a chute or funnel in which guides them into
a mold i I. ‘The chute or funnel may be aided by
an air blast or blower, if desired.
The molds
carrying the deposited ?bers may then be trans
means, such as an easily mountable spring wire
clip. If'a metal container for the unit is desired;
the covered unit may be inserted" into a can/6r the
like. A unit of this character may be manufac
tured su?iciently economically to warrant dispo
sition of- the unit and substitution by a new unit,‘
ported by a suitable conveyor I2 through a drier ' after a period of use. It is an exceedingly simple
l3 which sets the plastic impregnating the ?bers. 75 expedient when servicing an air cleaner, to with
draw a dirty unit, discard it, and insert a new
A slightly different'embodiment of the inven
tion includes the elimination of the paper board
or equivalent covering around the ?ber core, as
seen in Figure 6. In the event an air cleaner
already containsra ?lter holding element, such as
a metallic cylinder or the equivalent, it is not es
Figure 9 a group of the same strands are indi
cated at 21 in their new disposition after leaving
the carding mechanism 2|, the crimps now being
out of phase with each other. After this second
carding operation, the ?brous mat may be treated
as above described in connection with any of the
?gures in the drawings in order to produce the
ultimate ?lter unit. Binding may be provided for
each crimped ?lter unit, either byway of a paper
sential that the ?lter unit have any covering
therearound at the time it is inserted in or re 10 board or equivalent covering around the unit, or
moved from the air cleaner. Accordingly, as the
elongated substantially endless ?ber core or
bundle I9 is produced, it may be tied at spaced in
by way of spaced ties, depending upon whether
or not in actual use a complete covering of the
unit is desired or necessary.
It will be understood, of course, that'in the
or after the ?nal heat treating operation. Then 15 practice of the present method certain steps in
tervals with a cord or tape as at Ma, either before
the elongated ?ber core may be 'cut transversely
between adjacent bindings by the cutters 20, and
the process may be omitted in the event metallic
strands are used to form the ?lter mat, such for
example as the ?reproofing step,‘ and possibly
the core is severed into individual ?lter units Mb, , other steps obvious to one skilled in the art and
each unit is tied or bound adjacent each end 20 depending upon the particular material used. For
economy of product without lossof efficiency and
thereof. Such ties will, of course, effect a bind
with highly satisfactory operation, a ?lter made
ing of the character effected by the paperboard
of sisal ?bers has proven satisfactory.
tube or equivalent substance above described.
The speci?c ?lter unit per se, and a crimping
The tying will compress the ?lter unit somewhat
the ties or bindings may be located so that when
so that after severance, each individual unit llb 25 machine per se, are more fully described and
is somewhat barrel shaped; that is, the unit will
have a greater diameter or cross-sectional area
in the central portion than at the ends where the
claimed in respective copending applications.
namely, Browne and Pavlish “Air cleaner and
?lter "unit therefor," Serial No. 598,893, ?led June
11, 1945, and Browne and Lindeman “Crimping
ties ‘are located.' Such a unit by virtue of its
smaller ends, may be readily inserted into the 30 machine,” Serial No. 624,376, ?led October 25,‘
' holding element of’an air cleaner, and no gasket
means are necessary in order to seal the unit in
From the foregoing, it is apparent that we have I
provided a new and novel method of making a
position, due to the increased size of the central
?lter unit, which is highly desirable for use in
portion of the unit which will press against the
wall of the holding element su?iciently to effect .35 liquid bath air cleaners and similar apparatus. It
will be noted that the practice of the method is
an air-tight seal and force the air to travel
economical, and the process is substantially a con
through the ?lter unit itself.
tinuous one. The product produced by practicing
Still another embodiment of the invention is
the method is also economical, highly e?lcient,
shown in Figures 7, 8 and 9 and includes the
‘ crimping of the ?bers or strands going to make 40 and readily handled,‘ so that it is a simple expedi
ent to remove a dirty ?lter unit, and substitute a.
.upthe ?lter unit. A satisfactory size of crimp is
brand new ?lter unit, rather than go to the work
one with a quarter-inch ‘pitch. The ?ber is
crimped throughout its entire length, and with all a
of the ?bers or strands so crimped, there will be
no danger of the ?bers being bonded together a
and expense of cleansing the'dirty one.
It will, of course, be understood that various
details of the process may be varied through a
wide range and the sequence of certain steps
distance along their lengths after the application
varied without departing from the principles of
of the plastic and the ?nal heat treating of it.
this invention and it is, therefore, not the purpose
The ?bers will be bonded together only at spaced
to limit the patent granted thereon otherwise
points therealong. However, it is necessary to in
clude at least two additional operations in the 50 than necessitated by the scope of the appended
method to provide a ?lter unit having crimped
?bers or strands. A suitable crimping machine
generally‘ shown at 23 may be placed'either inside
or immediately in advance of the ?rst oven or
We claim as our invention:
1. In a method of making a ?lter unit for in
sertion in the casing of an automotive air cleaner, .
heat treating apparatus I so that the crimping 55 the steps of arranging numerous strands gener
ally lengthwise of the resultant unit, bunching the
occurs immediately following the application of
strands, bonding the strands together, and ex
the ?reproofing material.. Then while the ?bers
ternally transversely binding the bunched and
are ?rmly held in crimped form they are passed
bonded strands adjacent each end thereof to form
through the ?rst oven which dries out the‘ water
from the ?reproofing material, su?icient moisture 60 a ?lter unit having end portions of less cross-sec
tional area than the intermediate body portion.
is provided by the ?reproofing material itself for
2. In a method of making a ?lter unit, the steps
steaming the crimp into the ?bers or strands. As
of arranging numerous strands generally length
stated above, the crimping may occur just prior
wise of the resultant unit, crimping the strands,
to or during the drying operation. with crimped
strands or ?bers, it is preferable to again card 65 bunching the crimped strands, breaking up the
registry of the crimps, and bonding the strands
"he mat prior to the application of the plastic as
together at points of contact.
indicated at 24 so that the crimping of one ?ber
3. In a method of making a ?lter unit, the steps
is not uniform with the crimping of adjacent
of arranging numerous strands generally length
?bers, and consequently, after the curing of the
' ' plastic the ?bers or strands will be bonded to 70 wise of the resultant unit, crimping the strands,
carding the crimped strands to break up the reg
' gether only at spaced points therealong by virtue
istry of the crimps, bunching the crimped strands
of the crimping. This is best seen in the enlarged
with the crimps of adjacent strands in irregular
showings in Figures 8 and 9, wherein a group of
order, and bonding the strands together at points.
individual strands 26 are shown as they appear
adjacent strands contact each other.
upon leaving the crimping mechanism 23, and‘in
4. In a method of making a ?lter unit, the steps
?bers out of registry, applying a wet plastic bond
of carding vegetable ?bers, applying liquid ?re
proo?ng compound to the carded ?bers, crimping
the ?bers, and heat treating the crimped?bers to
drive out the moisture therein while utilizing said
moisture to steam the crimps into the ?bers.
ing agent to the ?bers, packing the wet ?bers into
the desired shape of the ultimate ?lter unit while
wet, and heat treating the ?bers to remove mois
ture and set the plastic bond.
11. In a method of making a ?lter unit, the
5. In a method of making a ?lter unit, the steps
' steps of applying a ?reproo?ng substance to a i
of carding vegetable ?bers, applying liquid ?re
quantity of in?ammable ?bers, undulating the
proo?ng compound to the carded ?bers, crimping
?bers, separating the ?bers to bring at least the
the ?bers, and heat treating the crimped ?bers to 10 majority of undulations out of registry, apply
drive out the moisture therein while utilizing said ,
ing a liquid bonding agent to the ?bers, massing
moisture to steam the crimps into the ?bers, card
' the ?bers, heat treating the ?bers to set the
ing the crimped ?bers to break up the registry of
bonding agent to join adjacent ?bers at points
the crimps, applying a liquid bonding agent to the
of contact therebetween, and cutting a ?lter unit
- ?bers, bunching the ?bers, and heat treating the 15 from the bonded mass.
bunched ?bers to set the bonding agent.
12. In a method of making a ?lter unit for in
6. In a method of making a ?lter unit, the steps
sertion in the casing'of an automotive air cleaner,
of applying a liquid ?reproo?ng compound to a
the steps of arranging ?bers generally length
mass of vegetable ?bers, crimping the mass of
wise in the direction air is to travel through the
?bers, and heat treating the ?bers to drive out the 20 ?lter, bonding the ?bers together at spaced points
moisture therein utilizing the moisture being
to provide an inherently resilient bunch, and ex
ternally binding such bunch of ?bers adjacent
driven out to steam' the crimps into the ?bers.
7. In a method of making a ?lter unit, the steps
of carding vegetable ?bers into a ?at mat with the
?bers extending lengthwise of the resultant ?lter
unit, ?reproo?ng said mat of ?bers, applying a
liquid bonding agent to the mat of ?bers, shaping
each end thereof to compress and reduce the size
of the ends relatively to the intermediate portion
to permit ready insertion of the unit in the
cleaner casing with the intermediate portion of
the unit e?'ecting a seal against the casing wall
the mat into a'cylindrical core, heat treating the
by virtue of its inherent resiliency.
core to set the bonding agent, and cutting the core
into desired lengths.
8. In a method of making a ?lter unit, the steps
of carding vegetable ?bers into a ?at mat with the
?bers extending lengthwise of the resultant filter
references are of record in the
unit, ?reproo?ng said mat of ?bers, applying a
liquid bonding agent to the mat of ?bers, shaping 35 ?le of this patent:
the mat into a cylindrical core, heat treating the
core to set the bonding agent, binding the core
therearound at spaced intervals, and cutting the
Grabein __________ __ Apr, 1, 1913
core between adjacent bindings.
' 9. In a method of making a ?lter unit, the steps
of carding vegetable ?bers into substantially a
continuous ?at mat, applying liquid ?reproo?ng
to said mat, crimping the ?bers, heat treating the
crimped ?bers to drive out the moisture therein,
carding the crimped ?bers to break up the regis 45
try of the crimps, applying a plastic bonding
agent to the ?bers, shaping the mat into a core,
heat treating the core to set the applied plastic
and bond the ?bers together, and cutting the core
into desired lengths.
10. In a method of making a ?lter unit, the
Rheinberger _, ____ .._ Nov. 16, 1920
Burhans _________ __ Nov. 24, 1931
Simmons ________ __ Aug. 22, 1933
Wagon __________ __ Feb. 12,
Fleisher ________ _.. Sept. 22,
Fleisher __________ __ Dec. 13,
Vander Jagt ______ __ Feb. 20,
Dreyfus __________ __ July 23,
. Robinson ---,. ____ __ June 17, 1941
Redman ________ __ June 24, 1941
Planiol __________ __ Aug. 25, 1942
Simison __________ __ Feb. 23, 1943
steps of carding vegetable ?bers, applying a
soluble ?reproo?ng agent to the ?bers, crimping
the ?bers, heating the crimped ?bers to drive out
the solvent of the ?reproo?ng agent and steam 55
in the crimps, carding the crimped and ?re
proofed ?bers (to bring the crimps of adjacent
Brotz _____________ __ June 8, 1943
Briggs“ _________ _'__ June 15, 1943
Francis, Jr. _______ _ Sept. 5, 1944
Great Britain ______ __ July 1, 1943
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