Note: Descriptions are shown in the official language in which they were submitted.
~49~
BACKGROUND OF THE INVENTION
. .
- This invention relates to a filter device for remov-
- ing dust from air and to a method of producing the same. The
present invention is particularly concerned with dusting filters
for use in electric vacuum cleaners and suction cleaning filters
operatively associa-ted with internal combustion engines.
Conventional filter devices of the type referred to
~ have used a filter medium of relatively rigid material bent to
! form a plurality of parallel folds and shaped into a hollow
cylinder having the folds running axially thereof, and a pair :
of end plates of metallic or plastic material attached to both
ends of the hollow cylindrical filter medium. One of the end
plates has a central aperture communicating with the interior
of the hollow cylinder.
Each metallic end plate has been attached to an end
of the corrugated filter cylinder by first placing the end plate ~:
agai.nst the cylinder and then flxing the abutting portions to
each other by means of a binder. In order to attach the plastic
end plate to the end of ~he corrugated filter cylinder, it has
~20 been generally practiced to preliminarily place the corrugated
filter cylinder in place within a mold of predetermined shape
for molding the end plate and injecting a corresponding plastic ~:
: material into the mold to form the end plate integral with the .
filter cylinder:so as to embed the end portion of the filter
cylinder
.' '
:: '
.
-- 2
- ~04942~
into the end plate thus molded. The manufacturing of filter
--. devices as above described has been ineffic.ient from the view-
point of the assemblage and correspondingly productivity is low.
This is principally because the filter medium is required to be
preliminarily formed into a hollow cylinder and so on.
Sl~MM~RY OF THE: INVENTION
Accordingly the present provides an improved filter
device for removing dust from air, for example, a dusting filter
device for -the electric vacuum cleaner or a suction cleaning
filter device for the internal combustion engine including an
improved corrugated filter medium prevented from being deformed
and/or damaged due -to external forces and which can be readily
manufactured.
According to the present invention there is provided
a filter device comprising a pair of identical filtration units
each including a corrugated filter medium produced by preliminarily ~.
: bending a flat filter medium to form a plurality of parallel
folds, and a frame-shaped wall of synthetic resin integrally .
molded on the peripheral edge portion of said filter medium, said
pair of filtration units superposing each other to dispose said
Eilter media in opposite relationship and being interconnected
in-to a unitary structure by having the respective frame-shaped
walls fixed to each other, and a window disposed on the inter-
connected frame-shaped walls to communicate an internal space
defined by both said filter media and said frame-shaped walls
with the exterior of the filter device.
, Preferably, a portion of the frame-shaped wall dis-
:~ posed at the lateral edge of the corrugated filter
~ 30
. .
.
,.~
~ 94Z~
. medium embedded in the wall parallel to the folds thereof may
} have a plurality of ridges disposed at predetermined intervals
on the inner surface thereof, and the lateral edge of the filter
~ .
; medium is bent and deformed to be similar in configuration to
tha~ inner surface of the frame-shaped wall provided with the
, ridges.
i Conveniently, a portion of the ~ra~e-shaped wall
disposed at the lateral edge of the filter medium parallel to
the folds thereof may have a plurality of depressions disposed
at predetermlned intervals on the outer surface thereof and ~ :
each of the depressions has a depth sufficient to expose one
portion of the filter medium thereto.
BRIEF DESCRIPTION OF T~E DRAWINGS :
, . . .
The present invention will become more readily
apparent from the following detailed description taken in
conjunction with the accompanying drawings in which:
Figure 1 is a plan view of a filter device constructed
'J :
in accordance with the principles of the present invention; .
Figure 2 is a side elevational view of the device ~:
shown in Figure l;
Figure 3 is a fragmental cross sectional view taken
;l along the line III-III of Figure l;
Figure 4 is a fragmental cross sectional view taken
: along the line of IV~IV of Figure l;
`:' Figure ~ is a longitudinal sectional view taken
~ ~ '
... .
., .
:~ 30
,
. ,; '
'~
; 4 ~ :
1~ ~049~Zl
,. . , .-
along the line V-Y of Figure 1; .
Figure 6 is a fragmental perspective view of the
~' . filter medium shown in Figure 1; .
Figure 7 is a cross sectional view of one .
portion of a mold for molding the frame-shaped wall .
shown in Figures 19 3, 4 and 5;
:- Figure 8 is a perspective view of a modification ~ :-
of the present invention with parts cut away to be .
. illustrated in section; and
Figure 9 is a longitudinal sectional view of the
. arrangement shown in Figure 8.
. .
I DESCRIPTION OF THE PREFERRED EMBODIMENTS
,l Referring now to the drawings and Figure 1 in
i! 15 particular, it is seen that an arrangement disclosed
,j herein comprises a rectangular corrugated filter medium :
of permeable material)as will be described3generally
t~ , . .
,',~? designated by the reference numeral 10 and bent to have
a plurality of parallel folds 12, and a frame-shaped wall
20 ~ of any suitable synthetic resin generally designated by ~ ~
~! th~ reference numeral 20 and having embedded therein the ~, ..
.I lentire peripheral edge of the filter medium 10 to
. maintain the filter medium 10 in.a generally flat
surface. ~ : ~
~ The wall 20 is shown in Figure 1 as being .
rectangular and includlng a pair of opposite wall ...
portions 20a parallel to the folds 12 of -the filter
medium ~0 .nd a pair ol opposlte wall portions 20b
: - 5 -
~'~ .
~:` :
~49~
perpendicular to the folds 12, that is, facing the corrugated
cross sec~ional ends of the filter medium 10. One of the wall
portions 20b, in this case, the lower wall portion 20_ as
viewed in Figure 1 is greater in both width and height than
the other or upper wall portions 20 ~ Each of the wall portions
20a has a plurality of flat ridges 22, three being shown dis-
I posed at predetermined intervals on the inner wall surface to
run lengthwise thereof. As best shown in Figure 3, each wall :~
portion 20a has also a plurality of rectangular depressions
24, in this case four, disposed between the ridges 22 andbetween the outermost ridges 22 and the adjacent wall portions
20b on the lower half as viewed in Figure 3 or the upper half
as viewed in Figure 2 of the outer-wall surface. Each depres- .
sion 2~ extends from one end of the outer wall 20a surface to
about the middle portion thereof and has a depth sufficient to
permit the adjacent lateral edge portion of the corrugated
I filter medium 10 to be partly exposed to the depression 24 as
: shown in Figures 2 and 3.
The broader wall portion 20b is cut awa~ to be formed
with a rectangular opening 26 open at the upper side as viewed
in Figure 5 and substantially e~ual in width to the corrugated
filter medium 10. The broader wall portion 20b further has
a guide me~er 28 projecting from the outer wall surface
to be coextensive and in opposite relationship with the
opening 26.
, ,`, . ' ' "
.
.
:
~ - 6 -
11D494Zl ~
According to the principles of the present
invention, the filter medium lO is first prepared by
forming a mixture of pulped cotton linters and chemical
~! fibers such as rayons, as a binder, into a web having a
thickness of about l mm. The web thus formed is
impregnated with a thermosttting resin such as a phenol
~"~ resin or a melamine resin~to produce a flat filter
A` ~ medium. Then1after having~cut into predetermined
~, lengthsJeach of the flat filter media is preliminarily
lO bent to form a plurality of folds substantially
f parallel to one another, resulting in a corrugated
filter medium lO including parallel folds 12 as best
shown in Figure 6.
In order to fixedly attach the frame-shaped wall
15 20 to the corrugated filter medium lO~the latter is
put in place with a mold as show~ in Figure 7. As
~ shown in Figure 7, the mold includes a lower half DA
,~1 . and an upper half DB. In their assembled position,
,` both halves DA and DB cooperate with each other to have `
;, 20 the inner and outer wall surfaces suitable for molding ~,
the frame-shaped wall 20 including the ridges 22, the
depressions 24Jthe opening 26~and the guide member 28
while at the same time the corrugated filter medium lO
is carried therebetween. More specifically, the upper
,25 mold half DB forms the inner surface of the frame-shaped `
wall 20 and is provided on each of the outer opposite
wall surface portions engaging the lateral edges of the i
filter medium lO parallel to the folds 12 with a
,~ - 7 -
.~'``~
'' .
. . .
1~49~Z~L
plurality of cavities (not shown) at predetermined intervals
complementary in shape to the ridges 22. The lower mold half
DA forms the outer surface of the wall 20 and is provided on
~ each of the inner opposite surface portions facing those
j outer wall surface portions of the upper mold half DB including
the cavities with a plurality of protrusions SA corresponding
in position and complementary in shape to the depressions 24 :
on the frame-shaped wall 20. Also those portions of the lower
and upper halves DA and DB forming the wall portions 20b have
respective inner and outer wall surfaces complementary in shape
;. - . .
to the corresponding surfaces of the wall portions 20b. When-
asse~led, both mold halves DA and DB form therebetween a space
in which the frame~shaped wall 20 is molded. That space is
typically designated by the reference character S in Figure 7.
The corrugated filter medium 10 is put between the superposed.
mold halves by having each of the opposite lateral edge portions
parallel to the folds 12 thereof sandwiched at a plurality of
its portions, in this case, four sandwiched between the pro-
trusions SA on the lower half DA and the adjacent portions of
the upper half DB as shown in Figure 7. It is noted that the
filter medium 10 is disposed between the upper and lower halves
DB and DA while it is maintained somewhat expanded as compared
with its natural state in order to prevent the lateral edges
of the filter medium from slacking after molding.
Under these circumstances, extrusion molding technique
: is utilized to inject any suitable synthetic resin under a ~:
: predetermined pressure into the assembled mold to fill the space
S (see Figure 7) between the upper and 1ower halves with the ~.
synthetic resin. After having been cooled to room temperature, .
30 the upper half DB is separated from the lower half DA to remove
from the mold the filter medium 10 having the resinous frame~
.
shaped wall 20 as above described integrally fixed to the
:, j.: .
- 8 ~
~ .
, . . . .
9~2~
perimeter thereof with the entire peripheral edge embedded
therein the wall 20.
; During this molding, those portions oE the peripheral
edge of the filter medium 10 between the upper and lower mold
halves DB and DA located in the above mentioned cavities on
the upper half DB are responsive to the particular extrusion
molding pressure to be bent and deformed into a concave form
following the shape of the cavities, as shown at dotted line
! in Figure 1. This is because those portion of the filter
medium 10 located in the cavities are somewhat spaced away from
the surfaces of the cavities. Therefore that portion of the
peripheral edge of the filter medium 10 extending along each
of the wall portion 20a is integrally connected to that wall
portion and similar in proEile to the latter. Further the
thermosetting resin impregnated into the material of the filter
medium is heated by using forming heat developed upon extru-
sion molding and hardened thereby to impart to the entire area
of the filter medium 10 a suitable rigidity.
The filter device as above described in conjunction
with Figures l through 7 has several advantages. For example,
the filter medium 10 is prevented from slacking on the lateral
edge portions extending along the wall portions 20a. This is
because the lateral edge portion of the filter medium 10 is
locally deformed due to the presence of the ridges 20a on the
wall portion 22 and integrally connected in the deformed state
to the latter. Due to this local deformation of the lateral
edge portions o~ the filter medium, the connection of the
filter medium 10 to the frame-shaped wall 20 is different on
the ridges 22 from on the remaining portion of the wall portion
- 30 20a, ensuring the intimate connection therebetween. Further
one portion o~ the filter medium 10 and particularly a portion of
the lateral ed~e thereof parallel to the folds 12 is expose~ to
'' ' : "
: -- 9 _
- . :
., : ~ :. .
~49~
each of the depressions 24 disposed on the outer surface of
the wall portion 20a and therefore whether the connection of
the filter medium to the frame-shaped wall is good can readily
be determined externally.
While the arrangement of Figure 1 may be disposed
, in a stream of air required to be filtered, a pair of such
arrangements can be preferably connected together as shown in
Figure 8. In the arrangement shown in Figure 8, the arrange-
ment of Figure 1 is superposed on another identical arrangement
by having both frame-shaped walls 20 disposed upon each other
so as to direct all the ridges 22 on the wall portions 20a to a
space defined
,", .
.
., .
~ ~,
~ 30
..
.
- 10 -
- ~ :
` ~ 10494Z~ ~ ,
¦ by both a pair of filter media 10 and a pair of frame-
¦ shaped walls 20. Then the walls 20 are fixedly secured ~
¦ to each other by any suitable means~ Thus the openings .
¦ 26 disposed on both broader wall portions 20b directly
¦ oppose to form a rectangular vent window W communicating ;
¦ the interior with the exterior of the arrangement thus
¦ assembled.
¦ Disposed within the space defined by the filter
, ¦ media and frame-shaped walls are a plurality of substan-
i 10 ¦ tially E-shaped vibration members 30 for each pair of
¦ opposite wave crests on the opposite filter media 10.
¦ As shown in Figure 9, each vibration member 30 is
¦ carried by the interconnected1 shorter wall portions 20b
¦ in cantilever manner and includes a pair of upper and
~ 15 ¦ lower legs 30a disposed in a pair of opposite folds on
j ~ both filter media 10 and a central ~g~ 3Qb disposed
therebetween. The upper and lower legs 30a extend short
of the broader wall portion 20b while the central leg
30b al50 extends toward the same wall portion 20b but
shorter than the legs 30a. ~ ~,~
, I An operating element 32 is slidably fitted into
! Ithe vent window W and includes a upper and lower protru-
sion adapted to be guide by the upper and lower guide
member~ 2~. The operating element 32 further has a~
elongated actuator plate 34 projecting from the inner `
end thereof dlsposed in the interior of the arrangement.
When the operating element 32 is moved along the vent t
window W, the actu~tor plate 34 can successively ~4~P
. , , .
~','
.`. ' .
'. j:
. . ~,
~4942~l
the free ends of the central vibration legs 30b thereby to
vibrate the vibration members 30 in succession. Thereby
the vibration legs 30a strike the inside of the folds 12 of
3 the both filter media lO one after another, resulting in the
vibration of the filter media lO.
The arrangement of Figure 8 is disposed in a stream
of air while isolating the suction side from the delivery
side thereof by means of a packing 36 tightly fitted onto
and interconnecting the broader wall portions 20_. The
packing 36 also serves to maintain the two filter devices 10-20
interconnected. The stream of air passes through both filter
media lO to be cleared of dust entrained therein. Then the
stream of air free from dust is delivered through -the vent
window W. If the filter media lO have been clogged with a
large amount of dust accumulated thereon, then the operating
element 32 can be leftwards and rightwards moved along the vent
! window W to vibrate the vibration members 34 in succession
as above described to vibrate the filter media lO thereby to
remove dust accumulated on the latter.
From the foregoing it will be appreciated that the
present invention provides filter devices ensuring that the
corrugated filter medium is hermetically connected to the
frame-shaped wall, improved in reliability and less complex
to produce than prior art devices. Thus the present ~ilter
device can be efficiently mass-produced.
''
(~ .
,. :
/ 30
: . . -
:
~ - 12 -
